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+*** START OF THE PROJECT GUTENBERG EBOOK 44388 ***
+
+Transcriber’s notes:
+
+In this transcription, italic text is denoted by *asterisks* and bold
+text by =equal signs=. Subscripts are indicated by _underscores_ (e.g.
+*a*_1 and *b*_1 in Fig.5 caption) and superscripts by ^ (e.g. *a*^1. in
+Fig. 9 caption).
+
+Page footnotes (renumbered in consecutive order) are now located
+immediately below the relevant paragraphs.
+
+The rare spelling typos noted in the original text have been corrected
+silently (e.g. invividual-->individual, hyberbola-->hyperbola) but
+inconsistent use of the ligature æ/ae (e.g. palæontology/palaeontology),
+inconsistent use of alternative spellings (e.g. learned/learnt), and
+occasional inconsistencies of hyphenation have been left as in the
+original. Minor punctuation typos have been corrected silently (e.g.
+index entries with missing commas). The abbreviation viz. appears in
+both roman and italic font.
+
+Formatting of entries in the Table of Contents does not accurately
+match that of the corresponding headings in the text, particularly the
+heading Pt.I-B-3 which contains an extraneous α.
+
+In Figure 12 caption, multiple ditto marks have been replaced by the
+relevant text for greater clarity.
+
+
+
+
+
+                       THE SCIENCE AND PHILOSOPHY
+                            OF THE ORGANISM
+
+
+
+
+          AGENTS
+
+            America        The Macmillan Company
+                             64 & 66 Fifth Avenue, New York
+
+            Australasia    The Oxford University Press, Melbourne
+
+            Canada         The Macmillan Company of Canada, Ltd.
+                             27 Richmond Street West, Toronto
+
+            India          Macmillan & Company, Ltd.
+                             Macmillan Building, Bombay
+                             309 Bow Bazaar Street, Calcutta
+
+
+
+
+                                  THE
+                         SCIENCE AND PHILOSOPHY
+                            OF THE ORGANISM
+
+                 THE GIFFORD LECTURES DELIVERED BEFORE
+                       THE UNIVERSITY OF ABERDEEN
+                            IN THE YEAR 1907
+
+                                   BY
+                          HANS DRIESCH, Ph.D.
+                               HEIDELBERG
+
+
+                                 LONDON
+                         ADAM AND CHARLES BLACK
+                                  1908
+
+                         *All rights reserved*
+
+
+
+
+PREFACE
+
+
+This work is not a text-book of theoretical biology; it is a systematic
+presentment of those biological topics which bear upon the true
+philosophy of nature. The book is written in a decidedly subjective
+manner, and it seems to me that this is just what “Gifford Lectures”
+ought to be. They ought never to lose, or even try to lose, their
+decidedly personal character.
+
+My appointment as Gifford Lecturer, the news of which reached me in
+February 1906, came just at the right moment in the progress of my
+theoretical studies. I had always tried to improve my previous books by
+adding notes or altering the arrangement; I also had left a good deal of
+things unpublished, and thus I often hoped that I might have occasion
+to arrange for a new, improved, and enlarged edition of those books.
+This work then is the realisation of my hopes; it is, in its way, a
+definitive statement of all that I have to say about the Organic.
+
+The first volume of this work, containing the lectures for 1907--though
+the division into “lectures” has not been preserved--consists of Parts
+I. and II. of Section A, “The Chief Results of Analytical Biology.”
+It gives in Part I. a shortened, revised, and, as I hope, improved
+account of what was published in my *Analytische Theorie der organischen
+Entwickelung* (1894), *Die Localisation morphogenetischer Vorgänge;
+ein Beweis Vitalistischen Geschehens* (1899), and *Die organischen
+Regulationen* (1901), though for the professed biologist the two
+last-named books are by no means superseded by the new work. Part II.
+has never been published in any systematic form before, though there are
+many remarks on Systematics, Darwinism, etc., in my previous papers.
+
+The second volume--to be published in the autumn, after the delivery of
+the 1908 lectures--will begin with the third and concluding part of the
+scientific section, which is a very carefully revised and rearranged
+second edition of my book, *Die “Seele” als elementarer Naturfactor*
+(1903). The greater part of this volume, however, will be devoted to the
+“Philosophy of the Organism,” *i.e.* Section B, which, in my opinion,
+includes the most important parts of the work.
+
+Some apology is needed for my presuming to write in English. I was
+led to do so by the conviction, mistaken perhaps, that the process of
+translation would rob the lectures of that individual and personal
+character which, as I said before, seems to me so much to be desired. I
+wished nothing to come between me and my audience. I accordingly wrote
+my manuscript in English, and then submitted it to linguistic revision
+by such skilled aid as I was able to procure at Heidelberg. My reviser
+tells me that if the result of his labours leaves much to be desired,
+it is not to be wondered at, but that, being neither a biologist nor a
+philosopher, he has done his best to make me presentable to the English
+reader. If he has failed in his troublesome task, I know that it is not
+for want of care and attention, and I desire here to record my sense of
+indebtedness to him. He wishes to remain anonymous, but I am permitted
+to say that, though resident in a foreign university, he is of Scottish
+name and English birth.
+
+My gratitude to my friends at Aberdeen, in particular to Professor and
+Mrs. J. A. Thomson, for their hospitality and great kindness towards me
+cannot be expressed here; they all know that they succeeded in making me
+feel quite at home with them.
+
+I am very much obliged to my publishers, Messrs. A. and C. Black, for
+their readiness to fulfil all my wishes with respect to publication.
+
+
+The lectures contained in this book were written in English by a
+German and delivered at a Scottish university. Almost all of the ideas
+discussed in it were first conceived during the author’s long residence
+in Southern Italy. Thus this book may be witness to the truth which,
+I hope, will be universally recognised in the near future--that all
+culture, moral and intellectual and aesthetic, is not limited by the
+bounds of nationality.
+
+  HANS DRIESCH.
+
+  Heidelberg, *2nd January 1908*.
+
+
+
+
+CONTENTS OF THE FIRST VOLUME
+
+
+                             THE PROGRAMME
+
+                                                                   PAGE
+  On Lord Gifford’s Conception of “Science”                           1
+  Natural Sciences and “Natural Theology”                             3
+  Our Philosophical Basis                                             5
+  On Certain Characteristics of Biology as a Science                  9
+  The Three Different Types of Knowledge about Nature                13
+  General Plan of these Lectures                                     15
+  General Character of the Organic Form                              19
+
+
+          SECTION A.--THE CHIEF RESULTS OF ANALYTICAL BIOLOGY
+
+  PART I.--THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM
+
+  *A.* ELEMENTARY MORPHOGENESIS--
+
+    Evolutio and Epigenesis in the old Sense                         25
+    The Cell                                                         27
+    The Egg: its Maturation and Fertilisation                        31
+    The First Developmental Processes of Echinus                     33
+    Comparative Embryology                                           44
+    The First Steps of Analytical Morphogenesis                      45
+    The Limits of Pure Description in Science                        50
+
+  *B.* EXPERIMENTAL AND THEORETICAL MORPHOGENESIS--
+
+  1. THE FOUNDATIONS OF THE PHYSIOLOGY OF DEVELOPMENT.
+    “EVOLUTIO” AND “EPIGENESIS”                                      52
+
+    The Theory of Weismann                                           52
+    Experimental Morphology                                          56
+    The Work of Wilhelm Roux                                         58
+    The Experiments on the Egg of the Sea-urchin                     59
+    On the Intimate Structure of the Protoplasm of the Germ          65
+    On some Specificities of Organisation in Certain Germs           70
+    General Results of the First Period of “Entwickelungsmechanik”   71
+    Some New Results concerning Restitutions                         74
+
+  2. ANALYTICAL THEORY OF MORPHOGENESIS                              76
+
+    α. THE DISTRIBUTION OF MORPHOGENIC POTENCIES                     76
+
+      Prospective Value and Prospective Potency                      76
+      The Potencies of the Blastomeres                               79
+      The Potencies of Elementary Organs in General                  80
+      Explicit and Implicit Potencies: Primary and Secondary
+        Potencies                                                    83
+      The Morphogenetic Function of Maturation in the Light of
+        Recent Discoveries                                           85
+      The Intimate Structure of Protoplasm: Further Remarks          88
+      The Neutrality of the Concept of “Potency”                     89
+
+    β. THE “MEANS” OF MORPHOGENESIS                                  89
+
+    β′. The Internal Elementary Means of Morphogenesis                90
+
+      Some Remarks on the Importance of Surface Tension in
+        Morphogenesis                                                91
+      On Growth                                                      93
+      On Cell-division                                               94
+
+    β″. The External Means of Morphogenesis                          95
+
+      The Discoveries of Herbst                                      96
+
+    γ. THE FORMATIVE CAUSES OR STIMULI                               99
+
+      The Definition of Cause                                        99
+      Some Instances of Formative and Directive Stimuli             102
+
+    δ. THE MORPHOGENETIC HARMONIES                                  107
+
+    ε. ON RESTITUTIONS                                              110
+
+      A few Remarks on Secondary Potencies and on Secondary
+        Morphogenetic Regulations in General                        110
+      The Stimuli of Restitutions                                   113
+
+  3. THE PROBLEM OF MORPHOGENETIC LOCALISATION: THE
+     THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM--FIRST
+     PROOF OF THE AUTONOMY OF LIFE                                  118
+
+    The General Problem                                             118
+    The Morphogenetic “System”                                      119
+    The “Harmonious-equipotential System”                           122
+    Instances of “Harmonious-equipotential Systems”                 126
+    The Problem of the Factor *E*                                   132
+    No Explanation offered by “Means” or “Formative Stimuli”        132
+    No Explanation offered by a Chemical Theory of Morphogenesis    134
+    No Machine Possible Inside the Harmonious Systems               138
+    The Autonomy of Morphogenesis proved                            142
+    “Entelechy”                                                     143
+    Some General Remarks on Vitalism                                145
+    The Logic of our First Proof of Vitalism                        146
+
+  4. ON CERTAIN OTHER FEATURES OF MORPHOGENESIS ADVOCATING
+     ITS AUTONOMY                                                   150
+
+    Harmonious-equipotential Systems formed by Wandering Cells      151
+    On Certain Combined Types of Morphogenetic Systems              153
+    The “Morphaesthesia” of Noll                                    157
+    Restitutions of the Second Order                                158
+    On the “Equifinality” of Restitutions                           159
+    Remarks on “Retro-Differentiation”                              163
+
+  *C.* ADAPTATION--
+
+  INTRODUCTORY REMARKS ON REGULATIONS IN GENERAL                    165
+
+  1. MORPHOLOGICAL ADAPTATION                                       168
+
+    The Limits of the Concept of Adaptation                         168
+    Adaptations to Functional Changes from Without                  172
+    True Functional Adaptation                                      176
+    Theoretical Conclusions                                         179
+
+  2. PHYSIOLOGICAL ADAPTATION                                       184
+
+    Specific Adaptedness *not* “Adaptation”                         186
+    Primary and Secondary Adaptations in Physiology                 188
+    On Certain Pre-requisites of Adaptations in General             189
+    On Certain Groups of Primary Physiological Adaptations          190
+
+    General Remarks on Irritability                                 190
+    The Regulation of Heat Production                               193
+    Primary Regulations in the Transport of Materials and
+      Certain Phenomena of Osmotic Pressure                         194
+    Chromatic Regulations in Algae                                  197
+    Metabolic Regulations                                           198
+
+    Immunity the only Type of a Secondary Physiological
+      Adaptation                                                    204
+    No General Positive Result from this Chapter                    209
+    A few Remarks on the Limits of Regulability                     212
+
+  *D.* INHERITANCE. SECOND PROOF OF THE AUTONOMY OF LIFE--
+
+    The Material Continuity in Inheritance                          214
+    On Certain Theories which Seek to Compare Inheritance to Memory 216
+    The Complex-Equipotential System and its Rôle in Inheritance    219
+    The Second Proof of Life-Autonomy. Entelechy at the Bottom
+      of Inheritance                                                224
+    The Significance of the Material Continuity in Inheritance      227
+    The Experimental Facts about Inheritance                        228
+    The Rôle of the Nucleus in Inheritance                          233
+    Variation and Mutation                                          237
+
+  *CONCLUSIONS FROM THE FIRST MAIN PART OF THESE LECTURES*          240
+
+
+                   PART II.--SYSTEMATICS AND HISTORY
+
+  *A.* THE PRINCIPLES OF SYSTEMATICS--
+
+    Rational Systematics                                            243
+    Biological Systematics                                          246
+
+  *B.* THE THEORY OF DESCENT--
+
+  1. GENERALITIES                                                   250
+
+    The Covert Presumption of all Theories of Descent               253
+    The Small Value of Pure Phylogeny                               255
+    History and Systematics                                         257
+
+  2. THE PRINCIPLES OF DARWINISM                                    260
+
+    Natural Selection                                               261
+    Fluctuating Variation the Alleged Cause of Organic Diversity    264
+    Darwinism Fails all along the Line                              269
+
+  3. THE PRINCIPLES OF LAMARCKISM                                   271
+
+    Adaptation as the Starting-Point                                272
+    The Active Storing of Contingent Variations as a
+      Hypothetic Principle                                          273
+    Criticism of the “Inheritance of Acquired Characters”
+      assumed by Lamarckism                                         275
+    Other Principles Wanted                                         281
+    Criticism of the Hypothesis of Storing and Handing Down
+      Contingent Variations                                         282
+
+  4. THE REAL RESULTS AND THE UNSOLVED PROBLEMS OF TRANSFORMISM     290
+
+  5. THE LOGICAL VALUE OF THE ORGANIC FORM ACCORDING TO THE
+     DIFFERENT TRANSFORMISTIC THEORIES                              293
+
+    The Organic Form and Entelechy                                  294
+
+  *C.* THE LOGIC OF HISTORY                                         297
+
+  1. THE POSSIBLE ASPECTS OF HISTORY                                299
+
+  2. PHYLOGENETIC POSSIBILITIES                                     304
+
+  3. THE HISTORY OF MANKIND                                         306
+
+    Cumulations in Human History                                    308
+    Human History not an “Evolution”                                311
+    The Problem of the “Single” as such                             315
+
+  *CONCLUSIONS ABOUT SYSTEMATICS AND HISTORY IN GENERAL*            322
+
+
+
+
+THE PROGRAMME
+
+
+ON LORD GIFFORD’S CONCEPTION OF “SCIENCE”
+
+This is the first time that a biologist has occupied this place; the
+first time that a biologist is to try to carry out the intentions of the
+noble and high-minded man to whom this lectureship owes its foundation.
+
+On such an occasion it seems to be not undesirable to inquire what Lord
+Gifford’s own opinions about natural science may have been, what place
+in the whole scheme of human knowledge he may have attributed to those
+branches of it which have become almost the centre of men’s intellectual
+interest.
+
+And, indeed, on studying Lord Gifford’s bequest with the object of
+finding in it some reference to the natural sciences, one easily notes
+that he has assigned to them a very high place compared with the other
+sciences, at least in one respect: with regard to their methods.
+
+There is a highly interesting passage in his will which leaves no doubt
+about our question. After having formally declared the foundation of
+this lectureship “for Promoting, Advancing, Teaching and Diffusing
+the study of Natural Theology in the widest sense of that term,” and
+after having arranged about the special features of the lectures, he
+continues: “I wish the lecturers to treat their subject as a strictly
+natural science, the greatest of all possible sciences, indeed, in one
+sense, the only science, that of Infinite Being.... I wish it considered
+just as astronomy or chemistry is.”
+
+Of course, it is not possible to understand these words of Lord
+Gifford’s will in a quite literal sense. If, provisionally, we call
+“natural theology” the ultimate conclusions which may be drawn from a
+study of nature in connection with all other results of human sciences,
+there cannot be any doubt that these conclusions will be of a rather
+different character from the results obtained in, say, the special field
+of scientific chemistry. But, nevertheless, there are, I think, two
+points of contact between the wider and the narrower field of knowledge,
+and both of them relate to method. Lord Gifford’s own phrase, “Infinite
+Being,” shows us one of these meeting-points. In opposition to history
+of any form, natural sciences aim at discovering such truths as are
+independent of special time and of special space, such truths as are
+“ideas” in the sense of Plato; and such eternal results, indeed, always
+stand in close relation to the ultimate results of human knowledge
+in general. But besides that there is still another feature which
+may be common both to “natural theology” and to the special natural
+sciences, and which is most fully developed in the latter: freedom from
+prepossessions. This, at least, is an ideal of all natural sciences;
+I may say it is *the* ideal of them. That it was this feature which
+Lord Gifford had in view in his comparison becomes clear when we read
+in his will that the lectures on natural theology are to be delivered
+“without reference to or reliance upon any supposed special exceptional
+or so-called miraculous revelation.”
+
+So we might say that both in their logical and their moral methods,
+natural sciences are to be the prototype of “Natural Theology” in Lord
+Gifford’s sense.
+
+
+NATURAL SCIENCES AND “NATURAL THEOLOGY”
+
+But now let us study in a more systematic manner the possible relations
+of the natural sciences to natural theology as a science.
+
+How is it possible for a natural scientist to contribute to the science
+of the highest and ultimate subject of human knowledge?
+
+Almost all natural sciences have a sort of naïveté in their own spheres;
+they all stand on the ground of what has been called a naïve realism,
+as long as they are, so to say, at home. That in no way prejudices
+their own progress, but it seems to stand in the way of establishing
+contact with any higher form of human knowledge than themselves.
+One may be a first-rate organic chemist even when looking upon the
+atoms as small billiard balls, and one may make brilliant discoveries
+about the behaviour of animals even when regarding them in the most
+anthropomorphic manner--granted that one is a good observer; but it
+can hardly be admitted that our chemist would do much to advance the
+theory of matter, or our biologist to solve the problem of the relations
+between body and mind.
+
+It is only by the aid of philosophy, or I would rather say by keeping
+in constant touch with it, that natural sciences are able to acquire
+any significance for what might be called *the* science of nature in the
+most simple form. Unhappily the term “natural philosophy” is restricted
+in English to theoretical physics. This is not without a high degree of
+justification, for theoretical physics has indeed lost its naïveté and
+become a philosophy of nature; but it nevertheless is very unfortunate
+that this use of the term “natural philosophy” is established in
+this country, as we now have no proper general term descriptive of a
+natural science that is in permanent relation to philosophy, a natural
+science which does not use a single concept without justifying it
+epistemologically, *i.e.* what in German, for instance, would simply be
+called “Naturphilosophie.”
+
+Let us call it philosophy of nature; then we may say that only by
+becoming a true philosophy of nature are natural sciences of all sorts
+able to contribute to the highest questions which man’s spirit of
+inquiry can suggest.
+
+These highest questions themselves are the outcome of the combination
+of the highest results of all branches of philosophy, just as our
+philosophy of nature originated in the discussion of the results of
+all the separate natural sciences. Are those highest questions not
+only to be asked, are they to be also solved? To be solved in a way
+which does not exceed the limits of philosophy as the domain of actual
+understanding?
+
+The beginning of a long series of studies is not the right place to
+decide this important question; and so, for the present certainly,
+“natural theology” must remain a problem. In other words: it must
+remain an open question at the beginning of our studies, whether after
+all there can be any final general answer, free from contradictions,
+applicable to the totality of questions asked by all the branches of
+philosophy.
+
+But let us not be disturbed by this problematic entrance to our studies.
+Let us follow biology on its own path; let us study its transition from
+a “naïve” science to a real branch of the philosophy of nature. In this
+way we perhaps shall be able to understand what its part may be in
+solving what can be solved.
+
+That is to be our subject.
+
+
+OUR PHILOSOPHICAL BASIS
+
+We call *nature* what is given to us in space.
+
+Of course we are not obliged in these lectures to discuss the
+psychological and epistemological problems of space with its three
+dimensions, nor are we obliged to develop a general theory of reality
+and its different aspects. A few epistemological points will be
+considered later at proper times, and always in connection with results
+of theoretical biology.
+
+At present it must suffice to say that our general philosophical point
+of view will be idealistic, in the critical meaning of the word. The
+universe, and within the universe nature, in the sense just defined,
+is my phenomenon. That is what I know. I know nothing more, either
+positively or negatively; that is to say, I do not know that the world
+is *only my* phenomenon, but, on the other hand, I know nothing about
+its “absolute reality.” And more, I am not even able to describe in
+intelligible words what “absolute reality” might mean. I am fully
+entitled to state: the universe *is* as truly as I am--though in
+a somewhat different sense of “being”--and I *am* as truly as the
+universe is; but I am not entitled to state anything beyond these
+two corresponding phrases. You know that, in the history of European
+philosophy at least, Bishop Berkeley was the first clearly to outline
+the field of idealism.
+
+But my phenomenon--the world, especially nature--consists of elements
+of two different kinds: some of them are merely passive, some of them
+contain a peculiar sort of activity in themselves. The first are
+generally called sensations, but perhaps would be better called elements
+or presentations; the others are forms of construction, and, indeed,
+there is an active element embraced in them in this sense, that they
+allow, by their free combination, the discovery of principles which
+are not to be denied, which must be affirmed, whenever their meaning
+is understood. You know that I am speaking here of what are generally
+called categories and synthetic judgments *a priori*, and that it was
+Kant who, on the foundations laid by Locke, Hume, and Leibnitz, first
+gave the outlines of what may be called the real system of critical
+philosophy. Indeed, our method will be to a great extent Kantian, though
+with certain exceptions; it is to be strictly idealistic, and will not
+in the Kantian way operate with things in themselves; and it regards
+the so-called “synthetic judgment *a priori*” and the problem of the
+relation between categorical principles and experience in a somewhat
+different manner. We think it best to define the much disputed concept
+“*a priori*” as “independent of the *amount* of experience”; that is
+to say, all categories and categorical principles are brought to my
+consciousness by that fundamental event which is called experience, and
+therefore are not independent of it, but they are not inferences from
+experience, as are so-called empirical laws. We almost might say that we
+only have to be reminded of those principles by experience, and, indeed,
+we should not, I think, go very far wrong in saying that the Socratic
+doctrine, that all knowledge is recollection, holds good as far as
+categories and categorical principles are in question.
+
+But enough at present about our general philosophy.
+
+As to the philosophy of nature, there can be no doubt that, on the basis
+of principles like those we have shortly sketched, its ultimate aim must
+be to co-ordinate everything in nature with terms and principles of the
+categorical style. The philosophy of nature thus becomes a system; a
+system of which the general type is afforded by the innate constructive
+power of the Ego. In this sense the Kantian dictum remains true, that
+the Ego prescribes its own laws to nature, though, of course, “nature,”
+that is, what is given in space, must be such as to permit that sort of
+“prescription.”
+
+One often hears that all sciences, including the science of sciences,
+philosophy, have to find out what is true. What, then, may be called
+“true” by an idealistic philosopher, for whom the old realistic formula
+of the conformity between knowledge and the object cannot have any
+meaning? Besides its ordinary application to simple facts or to simple
+judgments, where the word truth only means absence of illusion or no
+false statement, truth can be claimed for a philosophical doctrine or
+for a system of such doctrines only in the sense that there are no
+contradictions amongst the parts of the doctrine or of the system
+themselves, and that there are no features in them which impel our
+categorical Ego to further analysis.
+
+Those of you who attended Professor Ward’s lectures on “Naturalism and
+Agnosticism,” or who have read his excellent book on that subject, will
+know what the aims of a theory of matter are. You will also be aware
+that, at present, there does not exist any theory of matter which can
+claim to be “true”; there are contradictions in every theory of matter,
+and, moreover, there are always some points where we are obliged to ask
+for further information and receive no answer. Experience here has not
+yet aroused all the categorical functions which are needed in order to
+form one unity out of what seem to be incompatibilities at the present
+day. Why is that? Maybe because experience is not yet complete in this
+field, but maybe also because the whole subject is so complicated
+that it takes much time to attach categorical functions to what is
+experienced.
+
+But it is not our object here to deal either with epistemology proper
+or with ontology: a full analysis of biological facts is our problem.
+Why, then, all these introductions? why all these philosophical sketches
+in fields of knowledge which have quite another relation to philosophy
+than biology has? Biology, I hear some one say, is simply and solely
+an empirical science; in some sense it is nothing but applied physics
+and chemistry, perhaps applied mechanics. There are no fundamental
+principles in biology which could bring it in any close contact with
+philosophy. Even the one and only principle which might seem to be
+an innate principle of our experience about life, the principle of
+evolution, is only a combination of more simple factors of the physical
+and chemical type.
+
+It will be my essential endeavour to convince you, in the course of
+these lectures, that such an aspect of the science of biology is wrong;
+that biology is an elemental natural science in the true sense of the
+word.
+
+But if biology is an elemental science, then, and only then, it stands
+in close relations to epistemology and ontology--in the same relations
+to them, indeed, as every natural science does which deals with true
+elements of nature, and which is willing to abandon naïve realism and
+contribute its share to the whole of human knowledge.
+
+And, therefore, a philosophical sketch is not out of place at the
+beginning of lectures on the Philosophy of the Organism. We may be
+forced, we, indeed, shall be forced, to remain for some time on the
+ground of realistic empiricism, for biology has to deal with very
+complicated experiences; but there will be a moment in our progress when
+we shall enter the realm of the elemental ontological concepts, and
+in that very moment our study of life will have become a part of real
+philosophy. It was not without good reasons, therefore, that I shortly
+sketched, as a sort of introduction to my lectures, the general point of
+view which we shall take with regard to philosophical questions, and to
+questions of the philosophy of nature in particular.
+
+
+ON CERTAIN CHARACTERISTICS OF BIOLOGY AS A SCIENCE
+
+Biology is the science of life. Practically, all of you know what a
+living being is, and therefore it is not necessary to formulate a
+definition of life, which, at the beginning of our studies, would be
+either provisional and incomplete, or else dogmatic. In some respects,
+indeed, a definition should rather be the end of a science than its
+opening.
+
+We shall study the phenomena of living organisms analytically, by the
+aid of experiment; our principal object will be to find out laws in
+these phenomena; such laws will then be further analysed, and precisely
+at that point we shall leave the realm of natural science proper.
+
+Our science is the highest of all natural sciences, for it embraces as
+its final object the actions of man, at least in so far as actions also
+are phenomena observable on living bodies.
+
+But biology is also the most difficult of all natural sciences, not
+only from the complexity of the phenomena, which it studies, but in
+particular for another reason which is seldom properly emphasised, and
+therefore will well repay us for a few words devoted to it.
+
+Except so far as the “elements” of chemistry come into account, the
+experimenter in the inorganic fields of nature is not hampered by the
+specificity of composite objects: he makes all the combinations he
+wants. He is always able to have at his disposal red rays of a desired
+wave length when and where he wants, or to have, at a given time and
+place, the precise amount of any organic compound which he wishes to
+examine. And he forces electricity and electromagnetism to obey his
+will, at least with regard to space, time, and intensity of their
+appearance.
+
+The biologist is not able to “make” life, as the physicist has made red
+rays or electromagnetism, or as the chemist has made a certain compound
+of carbon. The biologist is almost always in that strange plight in
+which the physicist would be if he always had to go to volcanoes in
+order to study the conductivity of heat, or if he had to wait for
+thunderstorms in order to study electricity. The biologist is dependent
+on the specificity of living objects as they occur in nature.
+
+A few instances may show you what great inconveniences may hence arise
+to impede practical biological research. We later on shall have to deal
+with experiments on very young embryos: parts of the germ will have
+to be destroyed in order to study what will happen with the rest. Now
+almost all germs are surrounded by a membrane; this membrane has to be
+detached before any operation is possible. But what are we to do if it
+is not possible to remove the membrane without killing the embryo? Or
+what if, as for instance in many marine animals, the membrane may be
+removed but the germs are killed by contact with sea-water? In both
+cases no experiments at all will be possible on a sort of germ which
+otherwise, for some special circumstances of its organisation, might
+have given results of importance. These results become impossible for
+only a practical, for a very secondary reason; but enough: they are
+impossible, and they might have thrown light on problems which now
+must remain problems. Quite the same thing may occur in experiments
+on physiology proper or functional physiology: one kind of animals
+survives the operation, the other kind does not, and therefore, for
+merely extrinsic reasons, the investigations have to be restricted to
+the first, though the second might have given more important results.
+And thus the biological experimenter always finds himself in a sort of
+dependence on his subjects, which can hardly be called pleasant. To a
+great extent the comparatively slow advance of biological sciences is
+due to this very fact: the unalterable specific nature of biological
+material.
+
+But there is still another feature of biology dependent on the same
+fact. If a science is tied down to specific objects in every path it
+takes, it first, of course, has to know all about those objects, and
+that requires nothing else but plain description. We now understand why
+pure description, in the most simple sense of the word, takes up such an
+enormous part of every text-book of biological science. It is not only
+morphology, the science of form, that is most actively concerned with
+description; physiology also, in its present state, is pure description
+of what the functions of the different parts of the body of animals and
+plants actually *are*, at least for about nine-tenths of its range. It
+seems to me important to press this point very emphatically, since we
+often hear that physiology is from the very beginning a much higher sort
+of knowledge than morphology, inasmuch as it is rational. That is not at
+all true of the beginning of physiology: what the functions of the liver
+or of the root are has simply to be described just as the organisation
+of the brain or of the leaf, and it makes no difference logically that
+one species of description has to use the experimental method, while the
+other has not. The experiment which only discovers what happens here or
+what happens there, possesses no kind of logical superiority over pure
+description at all.
+
+But there will be another occasion in our lectures to deal more fully
+with the logic of experiment and with the differences of descriptive
+knowledge and real rational science.
+
+
+THE THREE DIFFERENT TYPES OF KNOWLEDGE ABOUT NATURE
+
+Natural sciences cannot originate before the given phenomena of nature
+have been investigated in at least a superficial and provisional manner,
+by and for the practical needs of man. But as soon as true science
+begins in any limited field, dealing, let us say, with animals or with
+minerals, or with the properties of bodies, it at once finds itself
+confronted by two very different kinds of problems, both of them--like
+all “problems”--created in the last resort by the logical organisation
+of the human mind, or, to speak still more correctly, of the Ego.
+
+In any branch of knowledge which practical necessities have separated
+from others, and which science now tries to study methodically, there
+occur general sequences in phenomena, general orders of events. This
+uniformity is revealed only gradually, but as soon as it has shown
+itself, even in the least degree, the investigator seizes upon it. He
+now devotes himself chiefly, or even exclusively, to the generalities in
+the sequences of all changes. He is convinced that there must be a sort
+of most general and at the same time of most universal connection about
+all occurrences. This most universal connection has to be found out; at
+least it will be the ideal that always will accompany the inquiring mind
+during its researches. The “law of nature” is the ideal I am speaking
+about, an ideal which is nothing less than one of the postulates of the
+possibility of science at all.
+
+Using for our purposes a word which has been already introduced into
+terminology by the philosopher Windelband, though in a somewhat
+different sense, we shall call that part of every branch of natural
+sciences which regards the establishment of a law of nature as its
+ideal, “nomothetic,” *i.e.* “law-giving.”
+
+But while every natural science has its nomothetic side, it also has
+another half of a very different kind. This second half of every natural
+science does not care for the same general, the same universal, which
+is shown to us in every event in a different and specified kind: it
+is diversity, it is specification, that constitutes the subject of
+its interest. Its aim is to find a sufficient reason for the types of
+diversities, for the types of specifications. So in chemistry there
+has been found a systematic order in the long series of the compounds
+and of the elements; crystallography also has its different systems of
+crystals, and so on.
+
+We have already employed the word by which we shall designate this
+second half of every natural science: it is the “systematic” side of
+science.
+
+Nomothetic work on the one side and systematics on the other do, in
+fact, appear in every natural science, and besides them there are no
+other main parts. But “science” as a whole stands apart from another
+aspect of reality which is called “history.” History deals with
+particulars, with particular events at such and such a place, whilst
+science always abstracts from the particular, even in its systematic
+half.[1]
+
+[1] Windelband (*Geschichte und Naturwissenschaft*, 3 Auflage, 1904)
+gives the name “nomothetic” to the whole of our “science” and calls the
+method of history “idiographic.” We thought it better to establish three
+fundamental types of all possible branches of knowledge.
+
+
+GENERAL PLAN OF THESE LECTURES
+
+Turning now to a sort of short outline of what is to be discussed
+in the whole of our future lectures, this summer and next, it seems
+clear, without further analysis, that biology as a science has its
+nomothetic and its systematic part also; respiration and assimilation,
+for instance, have proved to be types of natural laws among living
+phenomena, and that there is a “system” of animals and plants is too
+commonly known to require further explanation here. Therefore we might
+study first biological laws, and after that biological systematics, and
+in the third place perhaps biological history. But that would hardly
+correspond to the philosophical aims of our lectures: our chief object
+is not biology as a regular science, as treated in text-books and in
+ordinary university lectures; our chief object is the Philosophy of the
+Organism, as aided and supported by scientific biology. Therefore a
+general acquaintance with biology must be assumed in these lectures, and
+the biological materials must be arranged according to their bearing on
+further, that is on philosophical, analysis.
+
+That will be done, not, of course, to the extent of my regarding every
+one of my audience as a competent biologist; on the contrary, I shall
+explain most fully all points of biology proper, and even of the most
+simple and descriptive kind of biology, which serve as bases for
+philosophical analysis. But I shall do so only if they indeed do serve
+as such bases. All our biology will be not for its own sake, but for the
+sake of philosophy.
+
+Whilst regarding the whole of the biological material with such aims,
+it seems to me best to arrange the properly scientific material which
+is to be the basis of my discussions, not along the lines which biology
+as an independent science would select,[2] but to start from the three
+different kinds of fundamental phenomena which living bodies offer to
+investigation, and to attach all systematics exclusively to one of them.
+For there will not be very much for philosophy to learn from biological
+systematics at present.
+
+[2] See J. Arth. Thomson, *The Science of Life*, London, 1899.
+
+Life is unknown to us except in association with bodies: we only know
+living bodies and call them organisms. It is the final object of all
+biology to tell us what it ultimately means to say that a body is
+“living,” and in what sorts of relation body and life stand one to the
+other.
+
+But at present it is enough to understand the terms “body” and “living”
+in the ordinary and popular sense.
+
+Regarding living bodies in this unpretentious manner, and recollecting
+what the principal characters are of all bodies we know as living ones,
+we easily find that there are three features which are never wanting
+wherever life in bodies occurs. All living bodies are specific as to
+form--they “have” a specific form, as we are accustomed to say. All
+living bodies also exhibit metabolism; that is to say, they stand in a
+relation of interchange of materials with the surrounding medium, they
+take in and give out materials, but their form can remain unchanged
+during these processes. And, in the last place, we can say that all
+living bodies move; though this faculty is more commonly known among
+animals only, even elementary science teaches the student that it also
+belongs to plants.
+
+Therefore we may ask for “laws of nature” in biology about form, about
+metabolism, and about movements. In fact, it is according to this scheme
+that we shall arrange the materials of the biological part of our
+lectures, though, as we cannot regard the three divisions as equally
+important in their bearing on our ultimate purposes, we shall not treat
+them quite on equal terms. It will appear that, at least in the present
+state of science, the problems of organic form and of organic movement
+have come into much closer relation to philosophical analysis than have
+most of the empirical data on metabolism.
+
+It is *form* particularly which can be said to occupy the very centre
+of biological interest; at least it furnishes the foundation of all
+biology. Therefore we shall begin our scientific studies with a full and
+thorough analysis of form. The science of living forms, later on, will
+afford us a key to study metabolism proper with the greatest advantage
+for our philosophical aims, and therefore the physiology of what is
+usually called the vegetative functions will be to us a sort of appendix
+to our chapters on form; only the theory of a problematic “living
+substance” and of assimilation in the most general meaning of the word
+will be reserved for the philosophical part; for very good reasons,
+as I hope to show. But our chapters on the living forms will have yet
+another appendix besides the survey of the physiology of metabolism.
+Biological systematics almost wholly rests on form, on “morphology”; and
+what hitherto has been done on the metabolical side of their problems,
+consists of a few fragments, which are far from being an equivalent to
+the morphological system; though, of course it must be granted that,
+logically, systematics, in our general meaning of the word, as the sum
+of problems about the typically different and the specific, may be
+studied on the basis of each one of the principal characteristics of
+living bodies, not only on that of their forms. Therefore, systematics
+is to be the second appendix to the chief part of our studies in
+morphology, and systematics, in its turn, will later on lead us to
+a short sketch of the historical side of biology, to the theory of
+evolution in its different forms, and to the logic of history in general.
+
+So far will our programme be carried out during this summer. Next year
+the theory of movements will conclude our merely scientific analysis,
+and the remaining part of the course next summer will be devoted to the
+philosophy of living nature. I hope that nobody will be able to accuse
+our philosophy of resting on unsound foundations. But those of you, on
+the other hand, who would be apt to regard our scientific chapters as a
+little too long compared with their philosophical results, may be asked
+to consider that a small clock-tower of a village church is generally
+less pretentious but more durable than the campanile of San Marco has
+been.
+
+Indeed, these lectures will afford more “facts” to my hearers, than
+Gifford Lectures probably have done, as a rule. But how could that
+be otherwise on the part of a naturalist? Scientific facts are the
+material that the philosophy of nature has to work with, but these
+facts, unfortunately, are not as commonly known as historical facts,
+for instance, generally are; and they must be known, in order that a
+philosophy of the organism may be of any value at all, that it may be
+more than a mere entertainment.
+
+Goethe once said, that even in so-called facts there is more “theory”
+than is usually granted; he apparently was thinking of what might be
+called the ultimate or the typical facts in science. It is with such
+typical or ultimate facts, of course, that we must become acquainted if
+our future philosophy is to be of profit to us.
+
+Certainly, there would be nothing to prevent us from arranging our
+materials in a manner exactly the reverse of that which we shall adopt;
+we could begin with a general principle about the organic, and could
+try to deduce all its special features from that principle, and such a
+way perhaps would seem to be the more fascinating method of argument.
+But though logical it would not be psychological, and therefore would
+be rather unnatural. And thus our *most* general principle about the
+organic will not come on the scene before the eighteenth of these twenty
+lectures, although it is not a mere inference or deduction from the
+former lectures: it will be a culmination of the whole, and we shall
+appreciate its value the better the more we know what that whole really
+is.
+
+
+GENERAL CHARACTER OF THE ORGANIC FORM
+
+Our programme of this year, it was said, is to be devoted wholly
+to organic forms, though one of its appendixes, dealing with some
+characteristics of the physiology of metabolism, will lead us on to a
+few other phenomena. What then are the essentials of a living form, as
+commonly understood even without a special study of biology?
+
+Living bodies are not simple geometrical forms, not, like crystals,
+merely a typical arrangement of surfaces in space, to be reduced
+theoretically, perhaps, to an arrangement of molecules. Living bodies
+are typically combined forms; that is to say, they consist of simpler
+parts of different characters, which have a special arrangement with
+regard to one another; these parts have a typical form of their own and
+may again be combinations of more simple different parts. But besides
+that, living bodies have not always the same typically combined form
+during the whole of their life: they become more complicated as they
+grow older; they all begin from one starting point, which has little
+form at all, viz., the egg. So the living form may be called a “genetic
+form,” or a form considered as a process, and therefore *morphogenesis*
+is the proper and adequate term for the science which deals with the
+laws of organic forms in general; or, if you prefer not to use the
+same word both for a science and for the subjects of that science, the
+*physiology of morphogenesis*.
+
+Now there are different branches of the physiology of morphogenesis or
+physiology of form. We may study, and indeed we at first shall study,
+what are the laws of the morphogenetic processes leading from the egg
+to the adult: that may be properly called physiology of development.
+But living forms are not only able to originate in one unchangeable
+way: they may restore themselves, if disturbed, and thus we get the
+physiology of restoration or restitution as a second branch of the
+science of morphogenesis. We shall draw very important data, some of the
+foundations indeed of our philosophical discussions, from the study of
+such restitutions. Besides that, it is to them that our survey of the
+problems of the physiology of metabolism is to be appended.
+
+Living forms not only originate from the egg and are able to restore
+themselves, they also may give origin to other forms, guaranteeing in
+this way the continuity of life. The physiology of heredity therefore
+appears as the counterpart to those branches of the physiology of form
+which deal with individual form and its restitutions. And our discussion
+on heredity may be followed by our second appendix to this chief section
+on form, an appendix regarding the outlines of systematics, evolution
+and history.
+
+Theoretical considerations on biology generally start, or at least,
+used to start, from the evolution theory, discussing all other problems
+of the physiology of form by the way only, as things of secondary
+importance. You see from our programme, that we shall go just the
+opposite way: evolution will come last of all, and will be treated
+shortly; but the morphogenesis of the individual will be treated very
+fully, and very carefully indeed.
+
+Why then this deviation from what is the common practice? Because we do
+not know very much about evolution at all, because in this field we are
+just at the very beginning of what deserves the name of exact knowledge.
+But concerning individual morphogenesis we really know, even at present,
+if not very much, at least something, and that we know in a fairly exact
+form, aided by the results of experiments.
+
+And it will not be without its reward, if we restrict our aims in such a
+manner, if we prefer to deal more fully with a series of problems, which
+may seem at the first glance to be of less interest than others. After a
+few lectures we shall find already that we may decide one very important
+question about life merely by an analysis of individual form production,
+and without any regard to problematic and doubtful parts of biology:
+that we may decide the question, whether “life” is only a combination
+of chemical and physical events, or whether it has its elemental laws,
+laws of its own.
+
+But to prepare the road that is to lead to such results we first have
+to restrict our aims once more, and therefore the next lecture of this
+course, which eventually is to touch almost every concept of philosophy
+proper, will begin with the pure description of the individual
+development of the common sea-urchin.
+
+
+
+
+SECTION A
+
+THE CHIEF RESULTS OF ANALYTICAL BIOLOGY
+
+
+
+
+PART I
+
+THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM
+
+*A.* ELEMENTARY MORPHOGENESIS
+
+
+EVOLUTIO AND EPIGENESIS IN THE OLD SENSE
+
+The organism is a specific body, built up by a typical combination
+of specific and different parts. It is implied in the words of this
+definition, that the organism is different, not only from crystals, as
+was mentioned in the last lecture, but also from all combinations of
+crystals, such as those called dendrites and others, which consist of a
+typical arrangement of identical units, the nature of their combination
+depending on the forces of every single one of their parts. For this
+reason dendrites, in spite of the typical features in their combination,
+must be called aggregates; but the organism is not an aggregate even
+from the most superficial point of view.
+
+We have said before, what must have been familiar to you already, that
+the organism is not always the same in its individual life, that it
+has its development, leading from simpler to more complicated forms of
+combination of parts; there is a “production of visible manifoldness”
+carried out during development, to describe the chief character of that
+process in the words of Wilhelm Roux. We leave it an open question in
+our present merely descriptive analysis, whether there was already a
+“manifoldness,” in an invisible state, before development, or whether
+the phrase “production of manifoldness” is to be understood in an
+absolute sense.
+
+It has not always been granted in the history of biology, and of
+embryology especially, that production of visible manifoldness is the
+chief feature of what is called an organism’s embryology or ontogeny:
+the eighteenth century is full of determined scientific battles over the
+question. One school, with Albert von Haller and Bonnet as its leading
+men, maintained the view that there was no production of different parts
+at all in development, this process being a mere “evolutio,” that is,
+a growth of parts already existing from the beginning, yes, from the
+very beginning of life; whilst the other school, with C. F. Wolff and
+Blumenbach at its head, supported the opposite doctrine of so-called
+“epigenesis,” which has been proved to be the right one.
+
+To some extent these differences of opinion were only the outcome of the
+rather imperfect state of the optical instruments of that period. But
+there were also deeper reasons beyond mere difficulties of description;
+there were theoretical convictions underlying them. It is *impossible*,
+said the one party, that there is any real production of new parts;
+there *must* be such a production, said the other.
+
+We ourselves shall have to deal with these questions of the theory of
+organic development; but at present our object is narrower, and merely
+descriptive. It certainly is of great importance to understand most
+clearly that there actually *is* a “production of visible manifoldness”
+during ontogenesis in the descriptive sense; the knowledge of the fact
+of this process must be the very foundation of all studies on the theory
+of development in any case, and therefore we shall devote this whole
+lecture to studies in merely descriptive embryology.
+
+But descriptive embryology, even if it is to serve merely as an
+instance of the universality of the fact of epigenesis, can only be
+studied successfully with reference to a concrete case. We select the
+development of the common sea-urchin (*Echinus microtuberculatus*) as
+such a case, and we are the more entitled to select this organism rather
+than another, because most of the analytical experimental work, carried
+out in the interests of a real theory of development, has been done
+on the germs of this animal. Therefore, to know at least the outlines
+of the individual embryology of the Echinus may indeed be called the
+*conditio sine qua non* for a real understanding of what is to follow.
+
+
+THE CELL[3]
+
+[3] E. B. Wilson, *The Cell in Development and Inheritance*, New York,
+Macmillan, 1896.
+
+You are aware that all organisms consist of organs and that each of
+their organs has a different function: the brain, the liver, the eyes,
+the hands are types of organs in animals, as are the leaves and the
+pistils in plants.
+
+You are also aware that, except in the lowest organisms, the so-called
+Protista, all organs are built up of cells. That is a simple fact of
+observation, and I therefore cannot agree with the common habit of
+giving to this plain fact the title of cell-“theory.” There is nothing
+theoretical in it; and, on the other hand, all attempts to conceive
+the organism as a mere aggregate of cells have proved to be wrong. It
+is *the whole* that uses the cells, as we shall see later on, or that
+may not use them: thus there is nothing like a “cell-theory,” even in a
+deeper meaning of the word.
+
+The cell may have the most different forms: take a cell of the skin, of
+a muscle, of a gland, of the wood in plants as typical examples. But in
+every case two parts may be distinguished in a cell: an outside part,
+the protoplasm, and an inside part, the nucleus, to leave out of special
+account several others, which, by the way, may only be protoplasmatic
+modifications.
+
+Protoplasm is a mere name for what is not the nucleus; in any case it is
+not a homogeneous chemical compound; it consists of many such compounds
+and has a sort of architecture; all organic functions are based upon
+its metabolism. The nucleus has a very typical structure, which stands
+in a close relation to its behaviour during the most characteristic
+morphological period of the cell: during its division. Let us devote a
+few words to a consideration of this division and the part the nucleus
+plays in it; it will directly bear on future theoretical considerations
+about development.
+
+There is a certain substance in every nucleus of a cell which stains
+most markedly, whenever cells are treated with pigments: the name
+of “chromatin” has been given to it. The chromatin always gives the
+reaction of an acid, while protoplasm is basic; besides that it seems to
+be a centre of oxidation. Now, when a division of a cell is to occur,
+the chromatin, which had been diffusely distributed before, in the form
+of small grains, arranges itself into a long and very much twisted
+thread. This thread breaks, as it were by sections, into almost equal
+parts, typical in number for each species, and each of these parts is
+split at full length. A certain number of pairs of small threads, the
+so-called “chromosomes,” are the ultimate result of this process, which
+intentionally has been described a little schematically, the breaking
+and the splitting in fact going on simultaneously or occasionally even
+in reverse order. While what we have described is performing in the
+nucleus, there have happened some typical modifications in protoplasm,
+and then, by an interaction of protoplasmatic and nuclear factors, the
+first step in the actual division of the cell begins. Of each pair of
+the small threads of chromatin one constituent is moved to one side of
+the cell, one to the other; two daughter-nuclei are formed in this way;
+the protoplasm itself at the same time forms a circular furrow between
+them; the furrow gets deeper and deeper; at last it cuts the cell in
+two, and the division of the cell is accomplished.
+
+Not only is the growth of the already typically formed organism carried
+out by a series of cell-divisions, but also development proper in our
+sense, as a “production of visible manifoldness,” is realised to a great
+extent by the aid of such divisions, which therefore may indeed be said
+to be of very fundamental importance (Fig. 1).
+
+[Illustration: Fig. 1.--Diagram of Cell-Division (*after* Boveri).
+
+*a.* Resting cell; the chromatin distributed in the form of small
+granules inside the nucleus. Outside the nucleus is the “centrosome,”
+not mentioned in the text.
+
+*b.* Beginning of division; the chromatin arranged in the form of a long
+thread. Centrosome divided in two.
+
+*c.* The thread of chromatin cut into four parts, the “chromosomes.”
+
+*d.* The four parts of the chromatin arranged symmetrically between the
+centrosomes and the star-like “spheres.”
+
+*e.* Each of the chromosomes split at full length.
+
+*f.* Beginning of division of protoplasm; the two parts of each
+chromosome separated.
+
+*g.* End of cell-division.]
+
+Each cell-division which promotes growth is followed by the
+enlargement of the two daughter-cells which result from it; these two
+daughter-elements attain the exact size of the mother-cell before
+division, and as soon as this size is reached a new division begins:
+so the growth of the whole is in the main the result of the growth of
+the elements. Cell-divisions during real organ-formation may behave
+differently, as will be described at a proper occasion.
+
+
+THE EGG: ITS MATURATION AND FERTILISATION
+
+We know that all the organs of an animal or plant consist of cells, and
+we know what acts a cell can perform. Now there is one very important
+organ in all living beings, which is devoted to reproduction. This
+organ, the so-called ovary in animals, is also built up of cells,
+and its single cells are called the eggs; the eggs originated by
+cell-division, and cell-division is to lead from them to the new adult.
+
+But, with a very few exceptions, the egg in the ovary is not able to
+accomplish its functions, unless certain typical events have occurred,
+some of which are of a merely preparatory kind, whilst the others are
+the actual stimulus for development.
+
+The preparatory ones are generally known under the name of “maturation.”
+The egg must be “mature,” in order that it may begin development, or
+even that it may be stimulated to it. Maturation consists of a rather
+complicated series of phenomena: later on we shall have occasion to
+mention, at least shortly, what happens in the protoplasm during its
+course; as to the nuclear changes during maturation it may be enough
+for our purposes to say, that there occur certain processes among the
+chromosomes, which lead to an extension of half of them in the form
+of two very small cells, the “directive cells” or “directive or polar
+bodies,” as they have been somewhat cautiously called.
+
+The ripe or mature egg is capable of being fertilised.
+
+Before turning to this important fact, which, by the way, will bring us
+to our specially chosen type, the Echinus, a few words may be devoted to
+the phenomenon of “parthenogenesis,” that is to say, the possibility
+of development without fertilisation, since owing to the brilliant
+discoveries of the American physiologist, Jacques Loeb, this topic forms
+one of the centres of biological interest at present. It has long been
+known that the eggs of certain bees, lice, crayfishes, and other animals
+and also plants, are capable of development without fertilisation at
+all. Now Richard Hertwig and T. H. Morgan already had shown, that at
+least nuclear division may occur in the eggs of other forms--in the egg
+of the sea-urchin for instance--when these eggs are exposed to some
+chemical injuries. But Loeb[4] succeeded in obtaining a full development
+by treating the eggs of echinoderms with chloride of magnesium; thus
+artificial parthenogenesis had been discovered. Later researches have
+shown that artificial parthenogenesis may occur in all classes of the
+animal kingdom and may be provoked by all sorts of chemical or physical
+means. We do not know at present in what the proper stimulus consists
+that must be supposed here to take the place of fertilisation; it seems,
+of course, highly probable that it is always the same in the last
+resort.[5]
+
+[4] *Amer. Journ. Physiol.* vols. iii. and iv. 1900.
+
+[5] According to Delage (*Arch. Zool. exp.*, 3 sér. 10, 1902), it is
+indifferent for the realisation of artificial parthenogenesis, whether
+but one, or both, or neither of the “polar bodies” has been formed. But
+the egg must be in the first stages of maturation to the extent that the
+“nuclear membrane” must be already dissolved.
+
+But enough about processes, which at present are of a highly scientific,
+but hardly of any philosophic interest.
+
+By fertilisation proper we understand the joining of the male element,
+the spermatozoon or the spermia, with the female element, the egg. Like
+the egg, the spermatozoon is but a cell, though the two differ very much
+from one another in the relation between their protoplasm and nucleus:
+in all eggs it is the protoplasm which is comparatively very large, if
+held together with somatic cells, in the spermatozoon it is the nucleus.
+A large amount of reserve material, destined for the growth of the
+future being, is the chief cause of the size of the egg-protoplasm. The
+egg is quite or almost devoid of the faculty of movement, while on the
+contrary, movement is the most typical feature of the spermia. Its whole
+organisation is adapted to movement in the most characteristic manner:
+indeed, most spermatozoa resemble a swimming infusorium, of the type
+of Flagellata, a so-called head and a moving tail are their two chief
+constituents; the head is formed almost entirely of nuclear substance.
+
+It seems that in most cases the spermatozoa swim around at random and
+that their union with the eggs is assured only by their enormous number;
+only in a few cases in plants have there been discovered special stimuli
+of a chemical nature, which attract the spermia to the egg.
+
+But we cannot enter here more fully into the physiology of
+fertilisation, and shall only remark that its real significance is by no
+means clear.[6]
+
+[6] The older theories, attributing to fertilisation (or to
+“conjugation,” *i.e.* its equivalent in Protozoa), some sort of
+“renovation” or “rejuvenescence” of the race, have been almost
+completely given up. (See Calkins, *Arch. für Entwickelungsmechanik*,
+xv. 1902). R. Hertwig recently has advocated the view, that abnormal
+relations between the amounts of nuclear and of protoplasmatic material
+are rectified in some way by those processes. Teleologically, sexual
+reproduction has been considered as a means of variability (Weismann),
+but also as a means of preserving the type!
+
+
+THE FIRST DEVELOPMENT PROCESS OF ECHINUS
+
+Turning now definitively to the special kind of organism, chosen of our
+type, the common sea-urchin, we properly begin with a few words about
+the absolute size of its eggs and spermatozoa. All of you are familiar
+with the eggs of birds and possibly of frogs; these are abnormally
+large eggs, on account of the very high amount of reserve material they
+contain. The almost spherical egg of our Echinus only measures about a
+tenth of a millimetre in diameter; and the head of the spermatozoon has
+a volume which is only the four-hundred-thousandth part of the volume
+of the egg! The egg is about on the extreme limit of what can be seen
+without optical instruments; it is visible as a small white point. But
+the number of eggs produced by a single female is enormous and may
+amount to hundreds of thousands; this is one of the properties which
+render the eggs of Echinus so very suitable for experimental research;
+you can obtain them whenever and in any quantity you like; and,
+moreover, they happen to be very clear and transparent, even in later
+stages, and to bear all kinds of operations well.
+
+The spermia enters the egg, and it does so in the open water--another
+of the experimental advantages of our type. Only one spermia enters
+the egg in normal cases, and only its head goes in, the tail is left
+outside. The moment that the head has penetrated the protoplasm of the
+egg a thin membrane is formed by the latter. This membrane is very soft
+at first, becoming much stronger later on; it is very important for all
+experimental work, that by shaking the egg in the first minutes of its
+existence the membrane can easily be destroyed without any damage to the
+egg itself.
+
+And now occurs the chief phenomenon of fertilisation: the nucleus of
+the spermatozoon unites with the nucleus of the egg. When speaking of
+maturation, we mentioned that half of the chromatin was thrown out of
+the egg by that process: now this half is brought in again, but comes
+from another individual.
+
+It is from this phenomenon of nuclear union as the main character of
+fertilisation that almost all theories of heredity assume their right to
+regard the nuclei of the sexual cells as the true “seat” of inheritance.
+Later on we shall have occasion to discuss this hypothesis from the
+point of view of logic and fact.
+
+After the complete union of what are called the male and the female
+“pronuclei,” the egg begins its development; and this development, in
+its first steps, is simply pure cell-division. We know already the chief
+points of this process, and need only add to what has been described,
+that in the whole first series of the cell-divisions of the egg, or,
+to use the technical term, in the whole process of the “cleavage” or
+“segmentation” of it, there is never any growth of the daughter-elements
+after each division, such as we know to occur after all cell-divisions
+of later embryological stages. So it happens, that during cleavage the
+embryonic cells become smaller and smaller, until a certain limit is
+reached; the sum of the volumes of all the cleavage cells together is
+equal to the volume of the egg.
+
+But our future studies will require a more thorough knowledge of the
+cleavage of our Echinus; the experimental data we shall have to describe
+later on could hardly be properly understood without such knowledge.
+The first division plane, or, as we shall say, the first cleavage
+plane, divides the eggs into equal parts; the second lies at right
+angles to the first and again divides equally: we now have a ring of
+four cells. The third cleavage plane stands at right angles to the
+first two; it may be called an equatorial plane, if we compare the egg
+with a globe; it also divides equally, and so we now find two rings,
+each consisting of four cells, and one above the other. But now the
+cell-divisions cease to be equal, at least in one part of the egg: the
+next division, which leads from the eight- to the sixteen-cell stage of
+cleavage, forms four rings, of four cells each, out of the two rings of
+the eight-cell stage. Only in one half of the germ, in which we shall
+call the upper one, or which we might call, in comparison with a globe,
+the northern hemisphere, are cells of equal size to be found; in the
+lower half of the egg four very small cells have been formed at one
+“pole” of the whole germ. We call these cells the “micromeres,” that
+is, the “small parts,” on the analogy of the term “blastomeres,” that
+is, parts of the germ, which is applied to all the cleavage cells in
+general. The place occupied by the micromeres is of great importance
+to the germ as a whole: the first formation of real organs will start
+from this point later on. It is sufficient thus fully to have studied
+the cleavage of our Echinus up to this stage: the later cleavage stages
+may be mentioned more shortly. All the following divisions are into
+equal parts; there are no other micromeres formed, though, of course,
+the cells derived from the micromeres of the sixteen-cell stage always
+remain smaller than the rest. All the divisions are tangential; radial
+cleavages never occur, and therefore the process of cleavage ends at
+last in the formation of one layer of cells, which forms the surface
+of a sphere; it is especially by the rounding-up of each blastomere,
+after its individual appearance, that this real surface layer of cells
+is formed, but, of course, the condition, that no radial divisions
+occur, is the most important one in its formation. When 808 blastomeres
+have come into existence the process of cleavage is finished; a sphere
+with a wall of cells and an empty interior is the result. That only 808
+cells are formed, and not, as might be expected, 1024, is due to the
+fact that the micromeres divide less often than the other elements; but
+speaking roughly, of course, we may say that there are ten steps of
+cleavage-divisions in our form; 1024 being equal to 2^{10}.
+
+We have learned that the first process of development, the cleavage, is
+carried out by simple cell-division. A few cases are known, in which
+cell-division during cleavage is accompanied by a specific migration of
+parts of the protoplasm in the interior of the blastomeres, especially
+in the first two or first four; but in almost all instances cleavage
+is as simple a process of mere division as it is in our sea-urchin.
+Now the second step in development, at least in our form, is a typical
+histological performance: it gives a new histological feature to all
+of the blastomeres: they acquire small cilia on their outer side and
+with these cilia the young germ is able to swim about after it has left
+its membrane. The germ may be called a “blastula” at this stage, as it
+was first called by Haeckel, whose useful denominations of the first
+embryonic stages may conveniently be applied, even if one does not agree
+with most, or perhaps almost all, of his speculations (Fig. 2).
+
+[Illustration: Fig. 2.--Early Development of Echinus, the Common
+Sea-urchin.
+
+*a.* Two cells.
+
+*b.* Four cells.
+
+*c.* Eight cells, arranged in two rings of four, above one another.
+
+*d.* Sixteen cells, four “micromeres” formed at the “vegetative” pole.
+
+*e.* Optical section of the “blastula,” a hollow sphere consisting of
+about one thousand cells, each of them with a small cilium.]
+
+It is important to notice that the formation of the “blastula” from the
+last cleavage stage is certainly a process of organisation, and may also
+be called a differentiation with regard to that stage. But there is in
+the blastula no trace of one *part* of the germ becoming different with
+respect to others of its parts. If development were to go on in this
+direction alone, high organisatory complications might occur: but there
+would always be only one sort of cells, arranged in a sphere; there
+would be only one kind of what is called “tissue.”
+
+But in fact development very soon loads to true differences of the
+parts of the germ with respect to one another, and the next step of the
+process will enable us to apply different denominations to the different
+parts of the embryo.
+
+At one pole of the swimming blastula, exactly at the point where the
+descendants of the micromeres are situated, about fifty cells lose
+contact with their neighbours and leave the surface of the globe, being
+driven into the interior space of it. Not very much is known about the
+exact manner in which these changes of cellular arrangement are carried
+out, whether the cells are passively pressed by their neighbours, or
+whether, perhaps, in a more active manner, they change their surface
+conditions; therefore, as in most ontogenetic processes, the description
+had best be made cautiously in fairly neutral or figurative words.
+
+The cells which in the above manner have entered the interior of the
+blastula are to be the foundation of important parts of the future
+organism; they are to form its connective tissue, many of its muscles,
+and the skeleton. “Mesenchyme,” *i.e.* “what has been infused into the
+other parts,” is the technical name usually applied to these cells.
+We now have to learn their definite arrangement. At first they lie
+as a sort of heap inside the cell wall of the blastula, inside the
+“blastoderm,” *i.e.* skin of the germ. But soon they move from one
+another, to form a ring round the pole at which they entered, and on
+this ring a process takes place which has a very important bearing upon
+the whole type of the organisation of the germ. You will have noticed
+that hitherto the germ with regard to its symmetry has been a monaxial
+or radial formation; the cleavage stages and the blastula with its
+mesenchyme were forms with two different poles, lying at the ends of one
+single line, and round this line everything was arranged concentrically.
+But now what is called “bilateral symmetry” is established; the
+mesenchyme ring assumes a structure which can be symmetrically divided
+only by one plane, but divided in such a way, that one-half of it is the
+mirror image of the other. A figure shows best what has occurred, and
+you will notice (Fig. 3) two masses of cells in this figure, which have
+the forms of spherical triangles: it is in the midst of these triangles
+that the skeleton of the larva *originates*. The germ had an upper and
+a lower side before: it now has got an upper and lower, front and back,
+*right and left* half; it now has acquired that symmetry of organisation
+which our own body has; at least it has got it as far as its mesenchyme
+is concerned.
+
+[Illustration: Fig. 3.--Formation of Mesenchyme in Echinus.
+
+*a.* Outlines of blastula, side-view; mesenchyme forms a heap of cells
+at the “vegetative” pole.
+
+*a*_1. Heap of mesenchyme-cells from above.
+
+*b.* Mesenchyme-cells arranged in a ring round the vegetative pole.
+
+*c.* Mesenchyme-cells arranged in a bilateral-symmetrical figure;
+primordia of skeleton in the midst of two spherical triangles.]
+
+We leave the mesenchyme for a while and study another kind of
+organogenesis. At the very same pole of the germ where the mesenchyme
+cells originated there is a long and narrow tube of cell growing in,
+and this tube, getting longer and longer, after a few hours of growth
+touches the opposite pole of the larva. The growth of this cellular tube
+marks the beginning of the formation of the intestine, with all that
+is to be derived from it. The larva now is no longer a blastula, but
+receives the name of “gastrula” in Haeckel’s terminology; it is built
+up of the three “germ-layers” in this stage. The remaining part of the
+blastoderm is called “ectoderm,” or outer layer; the newly-formed tube,
+“endoderm,” or inner layer; while the third layer is the “mesenchyme”
+already known to us.
+
+The endoderm itself is a radial structure at first, as was the whole
+germ in a former stage, but soon its free end bends and moves against
+one of the sides of the ectoderm, against that side of it where the two
+triangles of the mesenchyme are to be found also. Thus the endoderm
+has acquired bilateral symmetry just as the mesenchyme before, and
+as in this stage the ectoderm also assumes a bilateral symmetry
+in its form, corresponding with the symmetrical relations in the
+endoderm and the mesenchyme, we now may call the whole of our larva a
+bilateral-symmetrical organisation.
+
+It cannot be our task to follow all the points of organogenesis of
+Echinus in detail. It must suffice to state briefly that ere long a
+second portion of the mesenchyme is formed in the larva, starting from
+the free end of its intestine tube; that the formation of the so-called
+“coelum” occurs by a sort of splitting off from this same original
+organ; and that the intestine itself is divided into three parts of
+different size and aspect by two circular sections.
+
+But we must not, I think, dismiss the formation of the skeleton so
+quickly. I told you already that the skeleton has its first origin in
+the midst of the two triangular cell-masses of the mesenchyme; but what
+are the steps before it attains its typical and complicated structure?
+At the beginning a very small tetrahedron, consisting of carbonate of
+calcium, is formed in each of the triangles; the four edges of the
+tetrahedron are produced into thin rods, and by means of a different
+organogenesis along each of these rods the typical formation of the
+skeleton proceeds. But the manner in which it is carried out is very
+strange and peculiar. About thirty of the mesenchyme cells are occupied
+in the formation of skeleton substance on each side of the larva. They
+wander through the interior space of the gastrula--which at this stage
+is not filled with sea water but with a sort of gelatinous material--and
+wander in such a manner that they always come to the right places, where
+a part of the skeleton is to be formed; they form it by a process of
+secretion, quite unknown in detail; one of them forms one part, one the
+other, but what they form altogether, is one whole.
+
+When the formation of the skeleton is accomplished, the typical larva
+of our Echinus is built up; it is called the “pluteus” (Fig. 4). Though
+it is far from being the perfect adult animal, it has an independent
+life of its own; it feeds and moves about and does not go through any
+important changes of form for weeks. But after a certain period of
+this species of independent life as a “larva,” the changes of form it
+undergoes again are most fundamental: it must be transformed into the
+adult sea-urchin, as all of you know. There are hundreds and hundreds
+of single operations of organogenesis to be accomplished before that
+end is reached; and perhaps the strangest of all these operations is a
+certain sort of growth, by which the symmetry of the animal, at least
+in certain of its parts--not in all of them--is changed again from
+bilateral to radial, just the opposite of what happened in the very
+early stages.
+
+[Illustration: Fig. 4.--Larval Development of Echinus.
+
+*A.* The gastrula.
+
+*B.* Later stage, bilateral-symmetrical. Intestine begins to divide
+into three parts.
+
+*C.* Pluteus larva. S = Skeleton. I = Intestine.]
+
+But we cannot follow the embryology of our Echinus further here; and
+indeed we are the less obliged to do so, since in all our experimental
+work we shall have to deal with it only as far as to the pluteus larva.
+It is impossible under ordinary conditions to rear the germs up to the
+adult stages in captivity.
+
+You now, I hope, will have a general idea at least of the processes
+of which the individual development of an animal consists. Of course
+the specific features leading from the egg to the adult are different
+in each specific case, and, in order to make this point as clear as
+possible, I shall now add to our description a few words about what may
+be called a comparative descriptive embryology.
+
+
+COMPARATIVE EMBRYOLOGY
+
+Even the cleavage may present rather different aspects. There may be a
+compact blastula, not one surrounded by only one layer of cells as in
+Echinus; or bilaterality may be established as early as the cleavage
+stage--as in many worms and in ascidians--and not so late as in Echinus.
+The formation of the germ layers may go on in a different order and
+under very different conditions: a rather close relative of our Echinus,
+for instance, the starfish, forms first the endoderm and afterwards
+the mesenchyme. In many cases there is no tube of cells forming the
+“endoderm,” but a flat layer of cells is the first foundation of all the
+intestinal organs: so it is in all birds and in the cuttlefish. And,
+as all of you know, of course, there are very many animal forms which
+have no proper “larval” stage: there is one in the frog, the well-known
+“tadpole,” but the birds and mammals have no larvae; that is to say,
+there is no special stage in the ontogeny of these forms which leads an
+independent life for a certain time, as if it were a species by itself,
+but all the ontogenetical stages are properly “embryonic”--the germ is
+always an “embryo” until it becomes the perfect young organism. And you
+also know that not all skeletons consist of carbonate of calcium, but,
+that there are skeletons of silicates, as in Radiolaria, and of horny
+substance, as in many sponges. And, indeed, if we were to glance at the
+development of plants also, the differences would seem to us probably
+so great that all the similarities would seem to disappear.
+
+But there are similarities, nevertheless, in all development, and we
+shall now proceed to examine what they are. As a matter of fact, it was
+especially for their sake that we studied the ontogeny of a special
+form in such detail; one always sees generalities better if one knows
+the specific features of at least one case. What then are the features
+of most general and far-reaching importance, which may be abstracted
+from the individual history of our sea-urchin, checked always by the
+teachings of other ontogenies, including those of plants?
+
+
+THE FIRST STEPS OF ANALYTICAL MORPHOGENESIS
+
+If we look back upon the long fight of the schools of embryologists in
+the eighteenth century about the question whether individual development
+was to be regarded as a real production of visible manifoldness or as
+a simple growth of visibly pre-existing manifoldness, whether it was
+“epigenesis” or “evolutio,” there can be no doubt, if we rely on all
+the investigations of the last hundred and fifty years, that, taken in
+the descriptive sense, the theory of epigenesis is right. Descriptively
+speaking there *is* a production of visible manifoldness in the course
+of embryology: that is our first and main result. Any one possessed of
+an average microscope may any day convince himself personally that it is
+true.
+
+In fact, true epigenesis, in the descriptive sense of the term, does
+exist. One thing is formed “after” the other; there is not a mere
+“unfolding” of what existed already, though in a smaller form; there is
+no “evolutio” in the old meaning of the word.
+
+The word “evolution” in English usually serves to denote the theory of
+descent, that is of a real relationship of all organisms. Of course we
+are not thinking here of this modern and specifically English meaning of
+the Latin word *evolutio*. In its ancient sense it means to a certain
+degree just the opposite; it says that there is no formation of anything
+new, no transformation, but simply growth, and this is promoted not for
+the race but for the individual. Keeping well in mind these historical
+differences in the meaning of the word “evolutio,” no mistakes, it seems
+to me, can occur from its use. We now shall try to obtain a few more
+particular results from our descriptive study of morphogenesis, which
+are nevertheless of a general bearing, being real characteristics of
+organic individual development, and which, though not calculated of
+themselves to further the problem, will in any case serve to prepare for
+a more profound study of it.
+
+The totality of the line of morphogenetic facts can easily be resolved
+into a great number of distinct processes. We propose to call these
+“elementary morphogenetic processes”; the turning in of the endoderm
+and its division into three typical parts are examples of them. If we
+give the name “elementary organs” to the distinct parts of every stage
+of ontogeny which are uniform in themselves and are each the result of
+one elementary process in our sense, we are entitled to say that each
+embryological stage consists of a certain number of elementary organs.
+The mesenchyme ring, the coelum, the middle-intestine, are instances of
+such organs. It is important to notice well that the word elementary is
+always understood here with regard to visible morphogenesis proper and
+does not apply to what may be called elementary in the physiological
+sense. An elementary process in our sense is a very distinct act of
+form-building, and an elementary organ is the result of every one of
+such acts.
+
+The elementary organs are typical with regard to their position and with
+regard to their histological properties. In many cases they are of a
+very clearly different histological type, as for instance, the cells of
+the three so-called germ-layers; and in other cases, though apparently
+almost identical histologically, they can be proved to be different
+by their different power of resisting injuries or by other means. But
+there are not as many different types of histological structure as there
+are typically placed organs: on the contrary there are many elementary
+organs of the same type in different typical parts of the organism, as
+all of you know to be the case with nerves and muscles. It will not be
+without importance for our future theory of development, carefully to
+notice this fact, that specialisation in the *position* of embryonic
+parts is more strict than in their histology.
+
+But elementary organs are not only typical in position and histology,
+they are typical also with regard to their form and their relative size.
+It agrees with what has been said about histology being independent of
+typical position, that there may be a number of organs in an embryonic
+stage, all in their most typical positions, which though all possessing
+the same histology, may have different forms or different sizes or
+both: the single bones of the skeleton of vertebrates or of adult
+echinoderms are the very best instances of this most important feature
+of organogenesis. If we look back from elementary organs to elementary
+processes, the specialisation of the size of those organs may also be
+said to be the consequence of a typical duration of the elementary
+morphogenetic process leading to them.[7]
+
+[7] The phrase “*ceteris paribus*” has to be added of course, as the
+duration of each single elementary morphogenetic process is liable to
+vary with the temperature and many other conditions of the medium.
+
+I hardly need to say, that the histology, form, and size of elementary
+organs are equally an expression of their present or future
+physiological function. At least they prepare for this function by a
+specific sort of metabolism which sets in very early.
+
+The whole sequence of individual morphogenesis has been divided by some
+embryologists into two different periods; there is a first period,
+during which the foundations of the organisation of the “type” are
+laid down, and a second period, during which the histo-physiological
+specifications are modelled out (von Baer, Götte, Roux). Such a
+discrimination is certainly justified, if not taken too strictly; but
+its practical application would encounter certain difficulties in many
+larval forms, and also, of course, in all plants.
+
+Our mention of plants leads us to the last of our analytical results. If
+an animal germ proceeds in its development from a stage *d* to the stage
+*g*, passing through *e* and *f*, we may say that the whole of *d* has
+become the whole of *f*, but we cannot say that there is a certain part
+of *f* which is *d*, we cannot say that *f* is *d* + *a*. But in plants
+we can: the stage *f* is indeed equal to *a* + *b* + *c* + *d* + *e* +
+*a* [Transcriber’s note: probable typo for *f*] in vegetable organisms;
+all earlier stages are actually visible as parts of the last one. The
+great embryologist, Carl Ernst von Baer, most clearly appreciated these
+analytical differences between animal and vegetable morphogenesis. They
+become a little less marked if we remember that plants, in a certain
+respect, are not simple individuals but colonies, and that among the
+corals, hydroids, bryozoa, and ascidia, we find analogies to plants in
+the animal kingdom; but nevertheless the differences we have stated are
+not extinguished by such reasoning. It seems almost wholly due to the
+occurrence of so many foldings and bendings and migrations of cells and
+complexes of cells in animal morphogenesis, that an earlier stage of
+their development seems *lost* in the later one; those processes are
+almost entirely wanting in plants, even if we study their very first
+ontogenetic stages. If we say that almost all production of surfaces
+goes on outside in plants, inside in animals, we shall have adequately
+described the difference. And this feature again leads to the further
+diversity between animals and plants which is best expressed by calling
+the former “closed,” the latter “open” forms: animals reach a point
+where they are finished, plants never are finished, at least in most
+cases.
+
+I hope you will allow that I have tried to draw from descriptive and
+comparative embryology as many general analytical results as are
+possibly to be obtained. It is not my fault if there are not any
+more, nor is it my fault if the results reached are not of the most
+satisfactory character. You may say that these results perhaps enable
+you to see a little more clearly and markedly than before a few of the
+characters of development, but that you have not really learnt anything
+new. Your disappointment--my own disappointment--in our analysis is due
+to the use of pure description and comparison as scientific methods.
+
+
+THE LIMITS OF PURE DESCRIPTION IN SCIENCE
+
+We have analysed our descriptions as far as we could, and now we must
+confess that what we have found cannot be the last thing knowable
+about individual morphogenesis. There must be something deeper to be
+discovered: we only have been on the surface of the phenomena, we
+now want to get to the very bottom of them. Why then occurs all that
+folding, and bending, and histogenesis, and all the other processes we
+have described? There must be something that drives them out, so to say.
+
+There is a very famous dictum in the *Treatise on Mechanics* by the
+late Gustav Kirchhoff, that it is the task of mechanics to describe
+completely and in the most simple manner all the motions that occur in
+nature. These words, which may appear problematic even in mechanics,
+have had a really pernicious influence on biology. People were extremely
+pleased with them. “‘Describing’--that is just what we always have
+done,” they said; “now we see that we have done just what was right;
+a famous physicist has told us so.” They did not see that Kirchhoff
+had added the words “completely and in the most simple manner”; and
+moreover, they did not consider that Kirchhoff never regarded it as the
+ultimate aim of physics to describe thunderstorms or volcanic eruptions
+or denudations; yet it only is with such “descriptions” that biological
+descriptions of *given* bodies and processes are to be compared!
+
+Physicists always have used both experiment and hypothetical
+construction--Kirchhoff himself did so in the most gifted manner. With
+these aids they have gone through the whole of the phenomena, and what
+they found to be ultimate and truly elemental, that alone may they
+be said to have “described”; but they have “explained” by the aid of
+elementalities what proved to be not elemental in itself.[8]
+
+[8] We shall not avoid in these lectures the word “explain”--so much
+out of fashion nowadays. To “explain” means to subsume under known
+concepts, or rules, or laws, or principles, whether the laws or concepts
+themselves be “explained” or not. Explaining, therefore, is always
+relative: what is elemental, of course, is only to be described, or
+rather to be stated.
+
+It is the *method* of the physicists--not their results--that
+morphogenesis has to apply in order to make progress; and this method
+we shall begin to apply in our next lectures. Physiology proper has
+never been so short-sighted and self-satisfied as not to learn from
+other sciences, from which indeed there was very much to be learned; but
+morphology has: the bare describing and comparing of descriptions has
+been its only aim for about forty years or more, and lines of descent of
+a very problematic character were its only general results. It was not
+seen that science had to begin, not with problematic events of the past,
+but with what actually happens before our eyes.
+
+But before saying any more about the exact rational and experimental
+method in morphology, which indeed may be regarded as a new method,
+since its prevalence in the eighteenth century had been really
+forgotten, we first shall have to analyse shortly some general attempts
+to understand morphogenesis by means of hypothetic construction
+exclusively. Such attempts have become very important as points of
+issue for really exact research, and, moreover, they deserve attention,
+because they prove that their authors at least had not quite forgotten
+that there were still other problems to be solved in morphology than
+only phylogenetical ones.
+
+
+
+
+*B.* EXPERIMENTAL AND THEORETICAL MORPHOGENESIS
+
+1. THE FOUNDATIONS OF THE PHYSIOLOGY OF DEVELOPMENT. “EVOLUTIO” AND
+“EPIGENESIS”
+
+
+THE THEORY OF WEISMANN
+
+Of all the purely hypothetic theories on morphogenesis that of August
+Weismann[9] can claim to have had the greatest influence, and to
+be at the same time the most logical and the most elaborated. The
+“germ-plasma” theory of the German author is generally considered as
+being a theory of heredity, and that is true inasmuch as problems of
+inheritance proper have been the starting-point of all his hypothetic
+speculations, and also form in some respect the most valuable part
+of them. But, rightly understood, Weismann’s theory consists of two
+independent parts, which relate to morphogenesis and to heredity
+separately, and it is only the first which we shall have to take into
+consideration at present; what is generally known as the doctrine of the
+“continuity of the germ-plasm” will be discussed in a later chapter.
+
+[9] *Das Keimplasma*, Jena, 1892.
+
+Weismann assumes that a very complicated organised structure, below
+the limits of visibility even with the highest optical powers, is the
+foundation of all morphogenetic processes, in such a way that, whilst
+part of this structure is handed over from generation to generation as
+the basis of heredity, another part of it is disintegrated during the
+individual development, and directs development by being disintegrated.
+The expression, “part” of the structure, first calls for some
+explanation. Weismann supposes several examples, several copies, as it
+were, of his structure to be present in the germ cells, and it is to
+these copies that the word “part” has been applied by us: at least one
+copy has to be disintegrated during ontogeny.
+
+The morphogenetic structure is assumed to be present in the nucleus
+of the germ cells, and Weismann supposes the disintegration of his
+hypothetic structure to be accomplished by nuclear division. By the
+cleavage of the egg, the most *fundamental* parts of it are separated
+one from the other. The word “fundamental” must be understood as
+applying not to proper elements or complexes of elements of the
+organisation, but to the chief relations of symmetry; the first
+cleavage, for instance, may separate the right and the left part of
+the structure, the second one its upper and lower parts, and after the
+third or equatorial cleavage all the principal eighths of our minute
+organisation are divided off: for the minute organisation, it must now
+be added, had been supposed to be built up differently in the three
+directions of space, just as the adult organism is. Weismann concedes it
+to be absolutely unknown in what manner the proper relation between the
+parts of the disintegrated fundamental morphogenetic structure and the
+real processes of morphogenesis is realised; enough that there may be
+imagined such a relation.
+
+At the end of organogenesis the structure is assumed to have been
+broken up into its elements, and these elements, which may be chemical
+compounds, determine the fate of the single cells of the adult organism.
+
+Here let us pause for a moment. There cannot be any doubt that
+Weismann’s theory resembles to a very high degree the old “evolutio”
+doctrines of the eighteenth century, except that it is a little less
+crude. The chick itself is not supposed to be present in the hen’s egg
+before development, and ontogeny is not regarded as a mere growth of
+that chick in miniature, but what really is supposed to be present in
+the egg is nevertheless a something that in all its parts corresponds
+to all the parts of the chick, only under a somewhat different
+aspect, while all the relations of the parts of the one correspond
+to the relations of the parts of the other. Indeed, only on such an
+hypothesis of a fairly fixed and rigid relation between the parts of
+the morphogenetic structure could it be possible for the disintegration
+of the structure to go on, not by parts of organisation, but by parts
+of symmetry; which, indeed, is a very strange, but not an illogical,
+feature of Weismann’s doctrine.
+
+Weismann is absolutely convinced that there must be a theory of
+“evolutio,” in the old sense of the word, to account for the ontogenetic
+facts; that “epigenesis” has its place only in descriptive embryology,
+where, indeed, as we know, manifoldness in the *visible* sense is
+produced, but that epigenesis can never form the foundation of a real
+morphogenetic *theory*: theoretically one pre-existing manifoldness is
+transformed into the other. An epigenetic theory would lead right beyond
+natural science, Weismann thinks, as in fact, all such theories, if
+fully worked out, have carried their authors to vitalistic views. But
+vitalism is regarded by him as dethroned for ever.
+
+Under these circumstances we have a good right, it seems to me, to speak
+of a *dogmatic* basis of Weismann’s theory of development.
+
+But to complete the outlines of the theory itself: Weismann was
+well aware that there were some grave difficulties attaching to his
+statements: all the facts of so-called adventitious morphogenesis in
+plants, of regeneration in animals, proved that the morphogenetic
+organisation could not be fully disintegrated during ontogeny. But these
+difficulties were not absolute: they could be overcome: indeed, Weismann
+assumes, that in certain specific cases--and he regarded all cases of
+restoration of a destroyed organisation as due to specific properties
+of the subjects, originated by roundabout variations and natural
+selection--that in specific cases, specific arrangements of minute parts
+were formed during the process of disintegration, and were surrendered
+to specific cells during development, from which regeneration or
+adventitious budding could originate if required. “Plasma of reserve”
+was the name bestowed on these hypothetic arrangements.
+
+Almost independently another German author, Wilhelm Roux,[10] has
+advocated a theoretical view of morphogenesis which very closely
+resembles the hypothesis of Weismann. According to Roux a minute
+ultimate structure is present in the nucleus of the germ and directs
+development by being divided into its parts during the series of nuclear
+divisions.
+
+[10] *Die Bedeutung der Kernteilungsfiguren*, Leipzig, 1883.
+
+But in spite of this similarity of the outset, we enter an altogether
+different field of biological investigation on mentioning Roux’s name:
+we are leaving hypothetic construction, at least in its absoluteness,
+and are entering the realms of scientific experiment in morphology.
+
+
+EXPERIMENTAL MORPHOLOGY
+
+I have told you already in the last lecture that, while in the
+eighteenth century individual morphogenesis had formed the centre of
+biological interest and been studied experimentally in a thoroughly
+adequate manner, that interest gradually diminished, until at last
+the physiology of form as an exact separate science was almost wholly
+forgotten. At least that was the state of affairs as regards zoological
+biology; botanists, it must be granted, have never lost the historical
+continuity to such a degree; botany has never ceased to be regarded
+as one science and never was broken up into parts as zoology was.
+Zoological physiology and zoological morphology indeed were for many
+years in a relationship to one another not very much closer than the
+relation between philology and chemistry.
+
+There were always a few men, of course, who strove against the current.
+The late Wilhelm His,[11] instance, described the embryology of the
+chick in an original manner, in order to find out the mechanical
+relations of embryonic parts, by which passive deformation, as an
+integrating part of morphogenesis, might be induced. He also most
+clearly stated the ultimate aim of embryology to be the mathematical
+derivation of the adult form from the distribution of growth in the
+germ. To Alexander Goette[12] we owe another set of analytical
+considerations about ontogeny. Newport, as early as 1850, and in
+later years Pflüger and Rauber, carried out experiments on the eggs
+of the frog, which may truly be called anticipatory of what was to
+follow. But it was Wilhelm Roux,[13] now professor of anatomy at
+Halle, who entered the field with a thoroughly elaborated programme,
+who knew not only how to state the problem analytically, but also
+how to attack it, fully convinced of the importance of what he did.
+“Entwickelungsmechanik,”--mechanics of development--he called the “new
+branch of anatomical science” of which he tried to lay the foundations.
+
+[11] *Unsere Körperform*, Leipzig, 1875.
+
+[12] *Die Entwickelungsgeschichte der Unke*, Leipzig, 1875.
+
+[13] *Gesammelte Abhandlungen*, Leipzig, 1895. Most important
+theoretical papers:--*Zeitschr. Biolog.* 21, 1885; *Die
+Entwickelungsmechanik der Organismen*, Wien, 1890; *Vorträge und
+Aufsätze über Entwickelungsmechanik*, Heft i., Leipzig, 1905.
+
+I cannot let this occasion pass without emphasising in the most decided
+manner how highly in my opinion Roux’s services to the systematic
+exploration of morphogenesis must be esteemed. I feel the more obliged
+to do so, because later on I shall have to contradict not only many
+of his positive statements but also most of his theoretical views. He
+himself has lately given up much of what he most strongly advocated only
+ten years ago. But Roux’s place in the history of biological science can
+never be altered, let science take what path it will.
+
+It is not the place here to develop the logic of experiment; least of
+all is it necessary in the country of John Stuart Mill. All of you know
+that experiment, by its method of isolating the single constituents
+of complicated phenomena, is the principal aid in the discovery of
+so-called causal relations. Let us try then to see what causal
+relations Wilhelm Roux established with the aid of morphogenetic
+experiment.
+
+
+THE WORK OF WILHELM ROUX
+
+We know already that an hypothesis about the foundation of individual
+development was his starting-point. Like Weismann he supposed that
+there exists a very complicated structure in the germ, and that nuclear
+division leads to the disintegration of that structure. He next tried to
+bring forward what might be called a number of indicia supporting his
+view.
+
+A close relation had been found to exist in many cases between the
+direction of the first cleavage furrows of the germ and the direction
+of the chief planes of symmetry in the adult: the first cleavage, for
+instance, very often corresponds to the median plane, or stands at right
+angles to it. And in other instances, such as have been worked out into
+the doctrine of so-called “cell-lineages,” typical cleavage cells were
+found to correspond to typical organs. Was not that a strong support
+for a theory which regarded cellular division as the principal means
+of differentiation? It is true, the close relations between cleavage
+and symmetry did not exist in every case, but then there had always
+happened some specific experimental disturbances, *e.g.* influences of
+an abnormal direction of gravity on account of a turning over of the
+egg, and it was easy to reconcile such cases with the generally accepted
+theory on the assumption of what was called “anachronism” of cleavage.
+
+But Roux was not satisfied with mere indicia, he wanted a proof, and
+with this intention he carried out an experiment which has become
+very celebrated.[14] With a hot needle he killed one of the first two
+blastomeres of the frog’s egg after the full accomplishment of its first
+cleavage, and then watched the development of the surviving cell. A
+typical half-embryo was seen to emerge--an organism indeed, which was as
+much a half as if a fully formed embryo of a certain stage had been cut
+in two by a razor. It was especially in the anterior part of the embryo
+that its “halfness” could most clearly be demonstrated.
+
+[14] *Virchow’s Archiv.* 114, 1888.
+
+That seemed to be a proof of Weismann’s and Roux’s theory of
+development, a proof of the hypothesis that there is a very complicated
+structure which promotes ontogeny by its disintegration, carried out
+during the cell divisions of embryology by the aid of the process of
+nuclear division, the so-called “karyokinesis.”
+
+To the dispassionate observer it will appear, I suppose, that the
+conclusions drawn by Roux from his experiment go a little beyond their
+legitimate length. Certainly some sort of “evolutio” is proved by
+rearing half the frog from half the egg. But is anything proved, is
+there anything discovered at all about the nucleus? It was only on
+account of the common opinion about the part it played in morphogenesis
+that the nucleus had been taken into consideration.
+
+Things soon became still more ambiguous.
+
+
+THE EXPERIMENTS ON THE EGG OF THE SEA-URCHIN
+
+Roux’s results were published for the first time in 1888; three years
+later I tried to repeat his fundamental experiment on another subject
+and by a somewhat different method. It was known from the cytological
+researches of the brothers Hertwig and Boveri that the eggs of the
+common sea-urchin (*Echinus microtuberculatus*) are able to stand well
+all sorts of rough treatment, and that, in particular, when broken into
+pieces by shaking, their fragments will survive and continue to segment.
+I took advantage of these facts for my purposes. I shook the germs
+rather violently during their two-cell stage, and in several instances I
+succeeded in killing one of the blastomeres, while the other one was not
+damaged, or in separating the two blastomeres from one another.[15]
+
+[15] *Zeitschr. wiss. Zool.* 53, 1891.
+
+Let us now follow the development of the isolated surviving cell. It
+went through cleavage just as it would have done in contact with its
+sister-cell, and there occurred cleavage stages which were just half
+of the normal ones. The stage, for instance, which corresponded to the
+normal sixteen-cell stage, and which, of course, in my subjects was
+built up of eight elements only, showed two micromeres, two macromeres
+and four cells of medium size, exactly as if a normal sixteen-cell stage
+had been cut in two; and the form of the whole was that of a hemisphere.
+So far there was no divergence from Roux’s results.
+
+The development of our Echinus proceeds rather rapidly, the cleavage
+being accomplished in about fifteen hours. I now noticed on the evening
+of the first day of the experiment, when the half-germ was composed of
+about two hundred elements, that the margin of the hemispherical germ
+bent together a little, as if it were about to form a whole sphere
+of smaller size, and, indeed, the next morning a *whole* diminutive
+blastula was swimming about. I was so much convinced that I should get
+Roux’s morphogenetical result in all its features that, even in spite of
+this whole blastula, I now expected that the next morning would reveal
+to me the half-organisation of my subject once more; the intestine, I
+supposed, might come out quite on one side of it, as a half-tube, and
+the mesenchyme ring might be a half one also.
+
+But things turned out as they were bound to do and not as I had
+expected; there was a typically *whole* gastrula on my dish the next
+morning, differing only by its small size from a normal one; and this
+*small but whole* gastrula was followed by a whole and typical small
+pluteus-larva (Fig. 5).
+
+[Illustration: Fig. 5.--Illustration of Experiments on Echinus.
+
+*a*_1 and *b*_1. Normal gastrula and normal pluteus.
+
+*a*_2 and *b*_2. “Half”-gastrula and “half”-pluteus, that *ought* to result
+from one of the first two blastomeres, when isolated, according to the
+theory of “evolutio.”
+
+*a*_3 and *b*_3. The small *but whole* gastrula and pluteus that actually
+*do* result.]
+
+That was just the opposite of Roux’s result: one of the first two
+blastomeres had undergone a half-cleavage as in his case, but then it
+had become a whole organism by a simple process of rearrangement of its
+material, without anything that resembled regeneration, in the sense of
+a completion by budding from a wound.
+
+If one blastomere of the two-cell stage was thus capable of performing
+the morphogenetical process in its totality, it became, of course,
+*impossible* to allow that nuclear division had separated any sort of
+“germ-plasm” into two different halves, and not even the protoplasm of
+the egg could be said to have been divided by the first cleavage furrow
+into unequal parts, as the postulate of the strict theory of so-called
+“evolutio” had been. This was a very important result, sufficient
+alone to overthrow at once the theory of ontogenetical “evolutio,”
+the “Mosaiktheorie” as it had been called--not by Roux himself, but
+according to his views--in its exclusiveness.
+
+After first widening the circle of my observations by showing that
+one of the first four blastomeres is capable of performing a whole
+organogenesis, and that three of the first four blastomeres together
+result in an absolutely perfect organism, I went on to follow up
+separately one of the two fundamental problems which had been suggested
+by my first experiment: was there anything more to find out about
+the importance or unimportance of the single *nuclear* divisions in
+morphogenesis?[16]
+
+[16] *Zeitschr. wiss. Zool.* 55, 1892.
+
+By raising the temperature of the medium or by diluting the sea-water to
+a certain degree it proved at first to be possible to alter in a rather
+fundamental way the type of the cleavage-stages without any damage to
+the resulting organism. There may be no micromeres at the sixteen-cell
+stage, or they may appear as early as in the stage of eight cells;
+no matter, the larva is bound to be typical. So it certainly is not
+necessary for all the cleavages to occur just in their normal order.
+
+But of greater importance for our purposes was what followed. I
+succeeded in pressing the eggs of Echinus between two glass plates,
+rather tightly, but without killing them; the eggs became deformed to
+comparatively flat plates of a large diameter. Now in these eggs all
+nuclear division occurred at right angles to the direction of pressure,
+that is to say, in the direction of the plates, as long as the pressure
+lasted; but the divisions began to occur at right angles to their former
+direction, as soon as the pressure ceased. By letting the pressure be
+at work for different times I therefore, of course, had it quite in my
+power to obtain cleavage types just as I wanted to get them. If, for
+instance, I kept the eggs under pressure until the eight-cell stage was
+complete, I got a plate of eight cells one beside the other, instead of
+two rings, of four cells each, one above the other, as in the normal
+case; but the next cell division occurred at right angles to the former
+ones, and a sixteen-cell stage, of two plates of eight cells each, one
+above the other, was the result. If the pressure continued until the
+sixteen-cell stage was reached, sixteen cells lay together in one plate,
+and two plates of sixteen cells each, one above the other, were the
+result of the next cleavage.
+
+We are not, however, studying these things for cytological, but for
+morphogenetical purposes, and for these the cleavage phenomenon itself
+is less important than the organogenetic result of it: all our subjects
+resulted in *absolutely normal* organisms. Now, it is clear, that the
+spatial relations of the different nuclear divisions to each other are
+anything but normal, in the eggs subjected to the pressure experiments;
+that, so to say, every nucleus has got quite different neighbours if
+compared with the “normal” case. If that makes no difference, then
+there *cannot* exist any close relation between the single nuclear
+divisions and organogenesis at all, and the conclusion we have drawn
+more provisionally from the whole development of isolated blastomeres
+has been extended and proved in the most perfect manner. There ought to
+result a morphogenetic chaos according to the theory of real “evolutio”
+carried out by nuclear division, if the positions of the single nuclei
+were fundamentally changed with regard to one another (Fig. 6). But now
+there resulted not chaos, but the normal organisation: therefore it was
+disproved in the strictest way that nuclear divisions have any bearing
+on the origin of organisation; at least as far as the divisions during
+cleavage come into account.
+
+[Illustration: Fig. 6.--Pressure-experiments on Echinus.
+
+*a*_1 and *b*_1. Two normal cleavage stages, consisting of eight and
+sixteen cells.
+
+*a*_2 and *b*_2. Corresponding stages modified by exerting pressure
+until the eight-cell stage was finished. See text.]
+
+On the egg of the frog (O. Hertwig), and on the egg of annelids (E. B.
+Wilson), my pressure experiments have been carried out with the same
+result.[17]
+
+[17] In the pressure experiments I had altered the relative position of
+the nuclei *in origine*. In later years I succeeded in disturbing the
+arrangement of the fully formed cells of the eight-cell stage, and in
+getting normal larvæ in spite of that in many cases. But as this series
+of experiments is not free from certain complications--which in part
+will be understood later on (see page 73)--it must suffice here to have
+mentioned them. (For further information see my paper in *Archiv. f.
+Entwickelungsmechanik*, xiv., 1902, page 500.)
+
+
+ON THE INTIMATE STRUCTURE OF THE PROTOPLASM OF THE GERM
+
+Nuclear division, as we have seen, cannot be the basis of organogenesis,
+and all we know about the whole development of isolated blastomeres
+seems to show that there exists nothing responsible for differentiation
+in the protoplasm either.
+
+But would that be possible? It cannot appear possible on a more profound
+consideration of the nature of morphogenesis, it seems to me: as the
+untypical agents of the medium cannot be responsible in any way for
+the origin of a form combination which is most typical and specific,
+there must be somewhere in the egg itself a certain factor which is
+responsible at least for the general orientation and symmetry of it.
+Considerations of this kind led me, as early as 1893,[18] to urge the
+hypothesis that there existed, that there *must* exist, a sort of
+intimate structure in the egg, including polarity and bilaterality as
+the chief features of its symmetry, a structure which belongs to every
+smallest element of the egg, and which might be imagined by analogy
+under the form of elementary magnets.[19] This hypothetic structure
+could have its seat in the protoplasm only. In the egg of echinoderms it
+would be capable of such a quick rearrangement after being disturbed,
+that it could not be observed but only inferred logically; there might,
+however, be cases in which its real discovery would be possible. Indeed
+Roux’s frog-experiment seems to be a case where it is found to be at
+work: at least it seems very probable to assume that Roux obtained half
+of a frog’s embryo because the protoplasm of the isolated blastomere had
+preserved the “halfness” of its intimate structure, and had not been
+able to form a small whole out of it.
+
+[18] *Mitteil. Neapel. 11, 1893.*
+
+[19] But the elementary magnets would have to be bilateral!
+
+Of course it was my principal object to verify this hypothesis, and
+such verification became possible in a set of experiments which my
+friend T. H. Morgan and myself carried out together,[20] in 1895, on
+the eggs of ctenophores, a sort of pelagic animals, somewhat resembling
+the jelly-fish, but of a rather different inner organisation. The
+zoologist Chun had found even before Roux’s analytical studies, that
+isolated blastomeres of the ctenophore egg behave like parts of the
+whole and result in a half-organisation like the frog’s germ does. Chun
+had not laid much stress on his discovery, which now, of course, from
+the new points of view, became a very important one. We first repeated
+Chun’s experiment and obtained his results, with the sole exception
+that there was a tendency of the endoderm of the half-larva of Beroë
+to become more than “half.” But that was not what we chiefly wanted to
+study. We succeeded in cutting away a certain mass of the protoplasm
+of the ctenophore egg just before it began to cleave, without damaging
+its nuclear material in any way: in all cases, where the cut was
+performed at the side, there resulted a certain type of larvae from
+our experiments which showed exactly the same sort of defects as were
+present in larvae developed from one of the first two blastomeres alone.
+
+[20] *Arch. Entw. Mech.* 2, 1895.
+
+The hypothesis of the morphogenetic importance of *protoplasm* had thus
+been proved. In our experiments there was all of the nuclear material,
+but there were defects on one side of the protoplasm of the egg; and the
+defects in the adult were found to correspond to these defects in the
+protoplasm.
+
+And now O. Schultze and Morgan succeeded in performing some experiments
+which directly proved the hypothesis of the part played by protoplasm
+in the subject employed by Roux, *viz.*, the frog’s egg. The first of
+these investigators managed to rear two whole frog embryos of small
+size, if he slightly pressed the two-cell stage of that form between
+two plates of glass and turned it over; and Morgan,[21] after having
+killed one of the first two blastomeres, as was done in the original
+experiment of Roux, was able to bring the surviving one to a half or
+to a whole development according as it was undisturbed or turned.
+There cannot be any doubt that in both of these cases, it is the
+possibility of a rearrangement of protoplasm, offered by the turning
+over, which allows the isolated blastomere to develop as a whole. The
+regulation of the frog’s egg, with regard to its becoming whole, may be
+called facultative, whilst the same regulation of the egg of Echinus
+is obligatory. It is not without interest to note that the first two
+blastomeres of the common newt, *i.e.* of a form which belongs to the
+other class of Amphibia, after a separation of *any* kind, *always*
+develop as wholes, their faculty of regulation being obligatory, like
+that of Echinus.
+
+[21] *Anat. Anz.* 10, 1895.
+
+Whole or partial development may thus be dependent on the power of
+regulation contained in the intimate polar-bilateral structure of the
+protoplasm. Where this is so, the regulation and the differences in
+development are both connected with the chief relations of symmetry.
+The development becomes a half or a quarter of the normal because
+there is only one-half or one-quarter of a certain structure present,
+one-half or one-quarter with regard to the very wholeness of this
+structure; the development is whole, in spite of disturbances, if
+the intimate structure became whole first. We may describe the
+“wholeness,” “halfness,” or “quarterness” of our hypothetic structure
+in a mathematical way, by using three axes, at right angles to one
+another, as the base of orientation. To each of these, *x*, *y*, and
+*z*, a certain specific state with regard to the symmetrical relations
+corresponds; thence it follows that, if there are wanting all those
+parts of the intimate structure which are determined, say, by a negative
+value of *y*, by minus *y*, then there is wanting half of the intimate
+structure; and this halfness of the intimate structure is followed by
+the halfness of organogenesis, the dependence of the latter on the
+intimate structure being established. But if regulation has restored,
+on a smaller scale, the whole of the arrangement according to all values
+of *x*, *y* and *z*, development also can take place completely (Fig. 7).
+
+[Illustration: Fig. 7.--Diagram illustrating the intimate Regulation of
+Protoplasm from “Half” to “Whole.”
+
+The large circle represents the original structure of the egg. In all
+cases where cleavage-cells of the two-cell stage are isolated this
+original structure is only present as “half” in the beginning, say
+only on the right (+*y*) side. Development then becomes “half,” if the
+intimate structure remains half; but it becomes “whole” (on a smaller
+scale) if a new whole-structure (small circle!) is formed by regulatory
+processes.]
+
+I am quite aware that such a discussion is rather empty and purely
+formal, nevertheless it is by no means without value, for it shows
+most clearly the differences between what we have called the intimate
+structure of germs, responsible only for the general symmetry of
+themselves and of their isolated parts, and another sort of possible
+structure of the egg-protoplasm which we now shall have to consider, and
+which, at the first glance, seems to form a serious difficulty to our
+statements, as far at least as they claim to be of general importance.
+The study of this other sort of germinal structure at the same time will
+lead us a step farther in our historical sketch of the first years of
+“Entwickelungsmechanik” and will bring this sketch to its end.
+
+
+ON SOME SPECIFICITIES OF ORGANISATION IN CERTAIN GERMS
+
+It was known already about 1890, from the careful study of what has
+been called “cell-lineage,” that in the eggs of several families of
+the animal kingdom the origin of certain organs may be traced back to
+individual cells of cleavage, having a typical histological character
+of their own. In America especially such researches have been carried
+out with the utmost minuteness, E. B. Wilson’s study of the cell-lineage
+of the Annelid *Nereis* being the first of them. If it were true that
+nuclear division is of no determining influence upon the ontogenetic
+fate of the blastomeres, only peculiarities of the different parts of
+the protoplasm could account for such relations of special cleavage
+cells to special organs. I advocated this view as early as in 1894,
+and it was proved two years later by Crampton, a pupil of Wilson’s,
+in some very fine experiments performed on the germ of a certain
+mollusc.[22] The egg of this form contains a special sort of protoplasm
+near its vegetative pole, and this part of it is separated at each
+of the first two segmentations by a sort of pseudo-cleavage, leading
+to stages of three and five separated masses instead of two and four,
+the supernumerary mass being the so-called “yolk-sac” and possessing
+no nuclear elements (Fig. 8). Crampton removed this yolk-sac at the
+two-cell stage, and he found that the cleavage of the germs thus
+operated upon was normal except with regard to the size and histological
+appearance of one cell, and that the larvae originating from these
+germs were complete in every respect except in their mesenchyme, which
+was wanting. A special part of the protoplasm of the egg had thus been
+brought into relation with quite a special part of organisation, *and
+that special part of the protoplasm contained no nucleus*.
+
+[22] *Arch. Entw. Mech.* 3, 1896.
+
+[Illustration: Fig. 8.--The Mollusc Dentalium (*after* E. B. Wilson).
+
+*a.* The egg, consisting of three different kinds of protoplasmatic
+material.
+
+*b.* First cleavage-stage. There are two cells and one “pseudo-cell,”
+the yolk-sac, which contains no nucleus. This was removed in Crampton’s
+experiment.]
+
+
+GENERAL RESULTS OF THE FIRST PERIOD OF “ENTWICKELUNGSMECHANIK”
+
+This experiment of Crampton’s, afterwards confirmed by Wilson himself,
+may be said to have closed the first period of the new science of
+physiology of form, a period devoted almost exclusively to the problem
+whether the theory of nuclear division or, in a wider sense, whether the
+theory of a strict “evolutio” as the basis of organogenesis was true or
+not.
+
+It was shown, as we have seen, that the theory of the “qualitatively
+unequal nuclear division” (“qualitativ-ungleiche Kernteilung” in German)
+certainly was not true, and that there also was no strict “evolutio”
+in protoplasm. Hence Weismann’s theory was clearly disproved. There
+certainly is a good deal of real “epigenesis” in ontogeny, a good deal
+of “production of manifoldness,” not only with regard to visibility but
+in a more profound meaning. But some sort of pre-formation had also
+been proved to exist, and this pre-formation, or, if you like, this
+restricted evolution, was found to be of two different kinds. First an
+intimate organisation of the protoplasm, spoken of as its polarity and
+bilaterality, was discovered, and this had to be postulated for every
+kind of germs, even when it was overshadowed by immediate obligatory
+regulation after disturbances. Besides that there were cases in which
+a real specificity of special parts of the germ existed, a relation of
+these special parts to special organs: but this sort of specification
+also was shown to belong to the protoplasm.
+
+It follows from all we have mentioned about the organisation of
+protoplasm and its bearing on morphogenesis, that the eggs of different
+animals may behave rather differently, in this respect, and that
+the eggs indeed may be classified according to the degree of their
+organisation. Though we must leave a detailed discussion of these
+topics to morphology proper, we yet shall try shortly to summarise
+what has been ascertained about them in the different classes of the
+animal kingdom. A full regulation of the *intimate* structure of
+isolated blastomeres to a new whole, has been proved to exist in the
+highest degree in the eggs of all echinoderms, medusae, nemertines,
+Amphioxus, fishes, and in one class of the Amphibia (the *Urodela*);
+it is facultative only among the other class of Amphibia, the *Anura*,
+and seems to be only partly developed or to be wanting altogether among
+ctenophora, ascidia, annelids, and mollusca. Peculiarities in the
+organisation of *specific parts* of protoplasm have been proved to occur
+in more cases than at first had been assumed; they exist even in the
+echinoderm egg, as experiments of the last few years have shown; even
+here a sort of specification exists at the vegetative pole of the egg,
+though it is liable to a certain kind of regulation; the same is true in
+medusae, nemertines, etc.; but among molluscs, ascidians, and annelids
+no regulation about the specific organisation of the germ in cleavage
+has been found in any case.
+
+The differences in the degree of regulability of the intimate germinal
+structure may easily be reduced to simple differences in the physical
+consistency of their protoplasm.[23] But all differences in specific
+organisation must remain as they are for the present; it will be one of
+the aims of the future theory of development to trace these differences
+also to a common source.
+
+[23] It deserves notice in this connection, that in some cases the
+protoplasm of parts of a germ has been found to be more regulable in
+the earliest stages, when it is very fluid, than later, when it is more
+stiff.
+
+That such an endeavour will probably be not without success, is clear,
+I should think, from the mere fact that differences with regard to
+germinal specific pre-formation do not agree in any way with the
+systematic position of the animals exhibiting them; for, strange as it
+would be if there were two utterly different kinds of morphogenesis, it
+would be still more strange if there were differences in morphogenesis
+which were totally unconnected with systematic relationship: the
+ctenophores behaving differently from the medusae, and Amphioxus
+differently from ascidians.
+
+
+SOME NEW RESULTS CONCERNING RESTITUTIONS
+
+We now might close this chapter, which has chiefly dealt with the
+disproof of a certain sort of ontogenetic theories, and therefore
+has been almost negative in its character, did it not seem desirable
+to add at least a few words about the later discoveries relating to
+morphogenetic restorations of the adult. We have learnt that Weismann
+created his concept of “reserve plasma” to account for what little
+he knew about “restitutions”: that is, about the restoration of lost
+parts: he only knew regeneration proper in animals and the formation of
+adventitious buds in plants. It is common to both of these phenomena
+that they take their origin from typically localised points of the body
+in every case; each time they occur a certain well-defined part of the
+body is charged with the restoration of the lost parts. To explain
+such cases Weismann’s hypothesis was quite adequate, at least in a
+logical sense. But at present, as we shall discuss more fully in another
+chapter, we know of some very widespread forms of restitution, in which
+what is to be done for a replacement of the lost is not entrusted to
+*one* typical part of the body in every case, but in which the whole
+of the morphogenetic action to be performed is transferred in its
+*single* parts to the *single* parts of the body which is accomplishing
+restoration: each of its parts has to take an individual share in the
+process of restoration, effecting what is properly called a certain kind
+of “re-differentiation” (“Umdifferenzierung”), and this share varies
+according to the relative position of the part in each case. Later on
+these statements will appear in more correct form than at present, and
+then it will become clear that we are fully entitled to emphasise at the
+end of our criticism of Weismann’s theory, that his hypothesis relating
+to restorations can be no more true than his theory of development
+proper was found to be.
+
+And now we shall pass on to our positive work.
+
+We shall try to sketch the outlines of what might properly be called an
+*analytical theory of morphogenesis*; that is, to explain the sum of our
+knowledge about organic form-production, gained by experiment and by
+logical analysis, in the form of a real system, in which each part will
+be, or at least will try to be, in its proper place and in relation with
+every other part. Our analytical work will give us ample opportunity of
+mentioning many important topics of so-called general physiology also,
+irrespective of morphogenesis as such. But morphogenesis is always to
+be the centre and starting-point of our analysis. As I myself approach
+the subject as a zoologist, animal morphogenesis, as before, will be the
+principal subject of what is to follow.
+
+
+2. ANALYTICAL THEORY OF MORPHOGENESIS[24]
+
+[24] Compare my *Analytische Theorie der organischen Entwickelung*,
+Leipzig, 1894, and my reviews in *Ergebnisse der Anatomie und
+Entwickelungsgeschichte*, vols. viii. xi. xiv., 1899-1905. A shorter
+review is given in *Ergebnisse der Physiologie*, vol. v., 1906. The full
+literature will be found in these reviews.
+
+α. THE DISTRIBUTION OF MORPHOGENETIC POTENCIES
+
+*Prospective Value and Prospective Potency*
+
+Wilhelm Roux did not fail to see that the questions of the locality and
+the time of all morphogenetic differentiations had to be solved first,
+before any problem of causality proper could be attacked. From this
+point of view he carried out his fundamental experiments.
+
+It is only in terminology that we differ from his views, if we prefer
+to call our introductory chapter an analysis of the distribution of
+morphogenetic potencies. The result will be of course rather different
+from what Roux expected it would be.
+
+Let us begin by laying down two fundamental concepts. Suppose we have
+here a definite embryo in a definite state of development, say a
+blastula, or a gastrula, or some sort of larva, then we are entitled
+to study any special element of any special elementary organ of this
+germ with respect to what is actually to develop out of this very
+element in the future actual course of this development, whether it be
+undisturbed or disturbed in any way; it is, so to say, the actual, *the
+real fate* of our element, that we take in account. I have proposed to
+call this real fate of each embryonic part in this very definite line
+of morphogenesis its *prospective value* (“prospective Bedeutung” in
+German). The fundamental question of the first chapter of our analytical
+theory of development may now be stated as follows: Is the prospective
+value of each part of any state of the morphogenetic line constant,
+*i.e.* is it unchangeable, can it be nothing but one; or is it variable,
+may it change according to different circumstances?
+
+We first introduce a second concept: the term *prospective potency*
+(“prospective Potenz” in German) of each embryonic element. The term
+“prospective morphogenetic potency” is to signify the *possible
+fate* of each of those elements. With the aid of our two artificial
+concepts we are now able to formulate our introductory question thus:
+Is the prospective potency of each embryonic part fully given by
+its prospective value in a certain definite case; is it, so to say,
+identical with it, or does the prospective potency contain more than the
+prospective value of an element in a certain case reveals?
+
+We know already from our historical sketch that the latter is true: that
+the actual fate of a part need not be identical with its possible fate,
+at least in many cases; that the potency of the first four blastomeres
+of the egg of the sea-urchin, for instance, has a far wider range than
+is shown by what each of them actually performs in even this ontogeny.
+There are more morphogenetic possibilities contained in each embryonic
+part than are actually realised in a special morphogenetic case.
+
+As the most important special morphogenetic case is, of course, the
+so-called “normal” one, we can also express our formula in terms of
+special reference to it: there are more morphogenetic possibilities in
+each part than the observation of the normal development can reveal.
+Thus we have at once justified the application of analytical experiment
+to morphogenesis, and have stated its most important results.
+
+As the introductory experiments about “Entwickelungsmechanik” have shown
+already that the prospective potency of embryonic parts, at least in
+certain cases, *can* exceed their prospective value--that, at least in
+certain cases, it can be different from it--the concept of prospective
+potency at the very beginning of our studies puts itself in the centre
+of analytical interest, leaving to the concept of prospective value the
+second place only. For that each embryonic part actually has a certain
+prospective value, a specified actual fate in every single case of
+ontogeny, is clear from itself and does not affirm more than the reality
+of morphogenetic cases in general; but that the prospective value of the
+elements may change, that there is a morphogenetic power in them, which
+contains more than actuality; in other words, that the term “prospective
+potency” has not only a logical but a factual interest: all these points
+amount to a statement not only of the most fundamental introductory
+results but also of the actual *problems* of the physiology of form.
+
+If at each point of the germ something else *can* be formed than
+actually is formed, why then does there happen in each case just what
+happens and nothing else? In these words indeed we may state the chief
+problem of our science, at least after the fundamental relation of
+the superiority of prospective potency to prospective value has been
+generally shown.
+
+We consequently may shortly formulate our first problem as the question
+of the distribution of the prospective morphogenetic potencies in the
+germ. Now this general question involves a number of particular ones.
+Up to what stage, if at all, is there an absolutely equal distribution
+of the potencies over all the elements of the germ? When such an equal
+distribution has ceased to exist at a certain stage, what are then the
+relations between the parts of different potency? How, on the other
+hand, does a newly arisen, more specialised sort of potency behave with
+regard to the original general potency, and what about the distribution
+of the more restricted potency?
+
+I know very well that all such questions will seem to you a little
+formal, and, so to say, academical at the outset. We shall not fail to
+attach to them very concrete meanings.
+
+*The Potencies of the Blastomeres*
+
+At first we turn back to our experiments on the egg of the sea-urchin
+as a type of the germ in the very earliest stages. We know already that
+each of the first two, or each of the first four, or three of the first
+four blastomeres together may produce a whole organism. We may add that
+the swimming blastula, consisting of about one thousand cells, when cut
+in two quite at random, in a plane coincident with, or at least passing
+near, its polar axis, may form two fully developed organisms out of its
+halves.[25] We may formulate this result in the words: the prospective
+potency of the single cells of a blastula of Echinus is the same for
+all of them; their prospective value is as far as possible from being
+constant.
+
+[25] If the plane of section passes near the equator of the germ, two
+whole larvae may be formed also, but in the majority of cases the
+“animal” half does not go beyond the blastula. The specific features of
+the organisation of the protoplasm come into account here. See also page
+65, note 1.
+
+But we may say even a little more: what actually will happen in each of
+the blastula cells in any special case of development experimentally
+determined depends on the position of that cell in the whole, if the
+“whole” is put into relation with any fixed system of co-ordinates; or
+more shortly, “the prospective value of any blastula cell is a function
+of its position in the whole.”
+
+I know from former experience that this statement wants a few words of
+explanation. The word “function” is employed here in the most general,
+mathematical sense, simply to express that the prospective value,
+the actual fate of a cell, will change, whenever its position in the
+whole is different.[26] The “whole” may be related to any three axes
+drawn through the normal undisturbed egg, on the hypothesis that there
+exists a primary polarity and bilaterality of the germ; the axes which
+determine this sort of symmetry may, of course, conveniently be taken as
+co-ordinates; but that is not necessary.
+
+[26] A change of the position of the cell is of course effected by each
+variation of the direction of the cut, which is purely a matter of
+chance.
+
+*The Potencies of Elementary Organs in General*
+
+Before dealing with other very young germs, I think it advisable to
+describe first an experiment which is carried out at a later stage of
+our well-known form. This experiment will easily lead to a few new
+concepts, which we shall want later on, and will serve, on the other
+hand, as a basis of explanation for some results, obtained from the
+youngest germs of some other animal species, which otherwise would seem
+to be rather irreconcilable with what our Echinus teaches us.
+
+You know, from the second lecture, what a gastrula of our sea-urchin
+is. If you bisect this gastrula, when it is completely formed, or
+still better, if you bisect the gastrula of the starfish, either along
+the axis or at right angles to it, you get complete little organisms
+developed from the parts: the ectoderm is formed in the typical manner
+in the parts, and so is the endoderm; everything is proportionate and
+only smaller than in the normal case. So we have at once the important
+results, that, as in the blastula, so in the ectoderm and in the
+endoderm of our Echinus or of the starfish, the prospective potencies
+are the same for every single element: both in the ectoderm and in
+the endoderm the prospective value of each cell is a “function of its
+position” (Fig. 9).
+
+[Illustration: Fig. 9.--The Starfish, *Asterias*.
+
+*a*^1. Normal gastrula; may be bisected along the main axis or at right
+angles to it (see dotted lines).
+
+*a*^2. Normal larva, “*Bipinnaria*.”
+
+*b*^1. Small but whole gastrula that results by a process of regulation
+from the parts of a bisected gastrula.
+
+*b*^2. Small *but whole* “*Bipinnaria*,” developed out of *b*^1.]
+
+But a further experiment has been made on our gastrula. If at the moment
+when the material of the future intestine is most distinctly marked in
+the blastoderm, but not yet grown into a tube, if at this moment the
+upper half of the larva is separated from the lower by an equatorial
+section, you will get a complete larva only from that part which bears
+the “Anlage” of the endoderm, while the other half will proceed in
+morphogenesis very well but will form only ectodermal organs. By another
+sort of experiment, which we cannot fully explain here, it has been
+shown that the endoderm if isolated is also only able to form such
+organs as are normally derived from it.
+
+And so we may summarise both our last results by saying: though
+ectoderm and endoderm have their potencies equally distributed amongst
+their respective cells, they possess different potencies compared one
+with the other. And the same relation is found to hold for all cases of
+what we call elementary organs: they are “equipotential,” as we may say,
+in themselves, but of different potencies compared with each other.
+
+*Explicit and Implicit Potencies: Primary and Secondary Potencies*
+
+We shall first give to our concept of “prospective potency” a few words
+of further analytical explanation with the help of our newly obtained
+knowledge.
+
+It is clear from what we have stated that the prospective potencies of
+the ectoderm and of the endoderm, and we may add, of every elementary
+organ in relation to every other, differ between themselves and also in
+comparison with the blastoderm, from which they have originated. But the
+diversity of the endoderm with respect to the ectoderm is not of the
+same kind as its diversity in respect to the blastoderm. The potency
+of the endoderm and that of the ectoderm are both specialised in their
+typical manner, but compared with the potency of the blastoderm they
+may be said not only to be specialised but also to be *restricted*: the
+potency of the blastoderm embraces the whole, that of the so-called
+germ-layer embraces only part of the whole; and this species of
+restriction becomes clearer and clearer the further ontogeny advances:
+at the end of it in the “ultimate elementary organs” there is no
+prospective potency whatever.
+
+A few new terms will serve to state a little more accurately what
+happens. Of course, with regard to all morphogenesis which goes on
+*immediately* from the blastoderm, the potency of the blastoderm is
+restricted as much as are the potencies of the germ layers. We shall
+call this sort of immediate potency *explicit*, and then we see at
+once that, with regard to their explicit potencies, there are only
+differences among the prospective potencies of the elementary organs;
+but with respect to the *implicit* potency of any of these organs, that
+is with respect to their potency as embracing the faculties of all their
+derivations, there are also not only differences but true morphogenetic
+restrictions lying at the very foundations of all embryology.
+
+But now those of you who are familiar with morphogenetic facts will
+object to me, that what we have stated about all sorts of restrictions
+in ontogeny is not true, and you will censure me for having overlooked
+regeneration, adventitious budding, and so on. To some extent the
+criticism would be right, but I am not going to recant; I shall only
+introduce another new concept. We are dealing only with *primary*
+potencies in our present considerations, *i.e.* with potencies which
+lie at the root of true embryology, not with those serving to regulate
+disturbances of the organisation. It is true, we have in some way
+disturbed the development of our sea-urchin’s egg in order to study
+it; more than that, it would have been impossible to study it at all
+without some sort of disturbance, without some sort of operation.
+But, nevertheless, no potencies of what may properly be called the
+*secondary* or restitutive type have been aroused by our operations;
+nothing happened except on the usual lines of organogenesis. It is
+true, some sort of regulation occurred, but that is included among the
+factors of ontogeny proper.
+
+We shall afterwards study more fully and from a more general point of
+view this very important feature of “primary regulation” in its contrast
+to “secondary regulation” phenomena. At present it must be enough to
+say that in speaking of the restriction of the implicit potencies in
+form-building we refer only to potencies of the primary type, which
+contain within themselves some properties of a (primary) regulative
+character.
+
+*The Morphogenetic Function of Maturation in the Light of Recent
+Discoveries*
+
+Turning again to more concrete matters, we shall first try, with the
+knowledge acquired of the potencies of the blastoderm and the so-called
+germ layers of Echinus, to understand certain rather complicated
+results which the experimental morphogenetic study of other animal
+forms has taught us. We know from our historical sketch that there are
+some very important aberrations from the type, to which the Echinus
+germ belongs,[27] *i.e.* the type with an equal distribution of the
+potencies over all the blastomeres. We know not only that in cases where
+a regulation of the intimate structure of the protoplasm fails to occur
+a partial development of isolated cells will take place, but that there
+may even be a typical disposition of typical cells for the formation of
+typical organs only, without any regulability.
+
+[27] The reader will remember (see page 65, note 1), that even the germ
+of Echinus is not quite equipotential along its main axis, but it is
+equipotential in the strictest sense around this axis. The germs of
+certain medusae seem to be equipotential in every respect, even in their
+cleavage stages.
+
+Let us first consider the last case, of which the egg of mollusca is a
+good type: here there is no equal distribution of potencies whatever,
+the cleavage-cells of this germ are a sort of real “mosaic” with regard
+to their morphogenetic potentialities. Is this difference between the
+germ of the echinoderms and the molluscs to remain where it is, and
+not to be elucidated any further? Then there would be rather important
+differences among the germs of different animals, at least with regard
+to the degree of the specification of their cleavage cells, or if we
+ascribe differences among the blastomeres to the organisation of the
+fertilised egg ready for cleavage, there would be differences in the
+morphogenetic organisation of the egg-protoplasm: some eggs would be
+more typically specialised at the very beginning of morphogenesis than
+others.
+
+In the first years of the study of “Entwickelungsmechanik” I pointed out
+that it must never be forgotten that the egg itself is the result of
+organogenesis. If, therefore, there are real mosaic-like specifications
+in some eggs at the beginning of cleavage, or during it, there may
+perhaps have been an *earlier* stage in the individual history of
+the egg which did not show such specifications of the morphogenetic
+structure. Two American authors share the merit of having proved
+this hypothesis. Conklin showed, several years ago, that certain
+intracellular migrations and rearrangements of material do happen in
+the first stages of ovogenesis in certain cases, but it is to E. B.
+Wilson[28] that science owes a proper and definitive elucidation of the
+whole subject. Wilson’s researches, pursued not only by descriptive
+methods,[29] but also by means of analytical experiment, led him to the
+highly important discovery that the eggs of several forms (nemertines,
+molluscs), which after maturation show the mosaic type of specification
+in their protoplasm to a more or less high degree, fail to show any
+kind of specification in the distribution of their potencies before
+maturation has occurred. In the mollusc egg a certain degree of
+specification is shown already before maturation, but nothing to be
+compared with what happens afterwards; in the egg of nemertines there is
+no specification at all in the unripe egg.
+
+[28] *Journ. Exp. Zool.* 1, 1904.
+
+[29] Great caution must be taken in attributing any specific
+morphogenetic part to differently coloured or constructed materials,
+which may be observed in the egg-protoplasm in certain cases. They may
+play such a part, but in other cases they certainly do not (see Lyon,
+*Arch. Entw. Mech.* 23, 1907). The final decision always depends on
+experiment.
+
+Maturation thus becomes a part of ontogeny itself; it is not with
+fertilisation that morphogenesis begins, there is a sort of ontogeny
+anterior to fertilisation.
+
+These words constitute a summary of Wilson’s researches. Taken together
+with the general results obtained about the potencies of the blastula
+and the gastrula of Echinus, they reduce what appeared to be differences
+of degree or even of kind in the specification of the egg-protoplasm *to
+mere differences in the time of the beginning of real morphogenesis*.
+What occurs in some eggs, as in those of Echinus, at the time of the
+definite formation of the germ layers, leading to a specification and
+restriction of their prospective potencies, may happen very much earlier
+in other eggs. But there exists in *every* sort of egg an *earliest*
+stage, in which all parts of its protoplasm are equal as to their
+prospectivity, and in which there are no potential diversities or
+restrictions of any kind.
+
+So much for differences in the *real material* organisation of the germ
+and their bearing on inequipotentialities of the cleavage cells.
+
+*The Intimate Structure of Protoplasm: Further Remarks*
+
+Where a typical half- or quarter-development from isolated blastomeres
+happens to occur, we know already that the impossibility of a regulation
+of the *intimate polar-bilateral* structure may account for it. As this
+impossibility of regulation probably rests on rather simple physical
+conditions[30] it may properly be stated that equal distribution of
+potencies is not wanting but is only overshadowed here. In this respect
+there exists a logical difference of fundamental importance between
+those cases of so-called “partial” or better, “fragmental” development
+of isolated blastomeres in which a certain embryonic organ is wanting
+on account of its specific morphogenetic material being absent, and
+those cases in which the “fragmental” embryo lacks complete “halves” or
+“quarters” with regard to general symmetry on account of the symmetry
+of its intimate structure being irregularly disturbed. This logical
+difference has not always received the attention which it undoubtedly
+deserves. Our hypothetical intimate structure in itself is, of course,
+also a result of factors concerned in ovogenesis. Only in one case do
+we actually know anything about its origin: Roux has shown that in the
+frog it is the accidental path of the fertilising spermatozoon in the
+egg which, together with the polar axis, normally determines the plane
+of bilateral symmetry; but this symmetry may be overcome and replaced
+by another, if gravity is forced to act in an abnormal manner upon the
+protoplasm; the latter showing parts of different specific gravity in
+the eggs of all Amphibia.
+
+[30] It seems that these physical conditions also--besides the real
+specifications in the organisation of the egg--may be different before
+and after maturation or (in other cases) fertilisation. (See Driesch,
+*Archiv f. Entwickelungsmechanik*, 7, p. 98; and Brachet, *ibid.* 22, p.
+325.)
+
+*The Neutrality of the Concept of “Potency”*
+
+Now we may close our rather long chapter on the distribution of
+potencies in the germ; it has been made long, because it will prove to
+be very important for further analytical discussion; and its importance,
+in great measure, is due to its freedom from prepossessions. Indeed,
+the concept of prospective potency does not prejudice anything; we
+have said, it is true, that limitations of potencies may be due to
+the presence of specific parts of organisation in some cases; that,
+at least, they may be connected therewith; but we have not determined
+at all what a prospective potency really is, what the term really is
+to signify. It may seem that such a state of things gives an air of
+emptiness to our discussions, that it leaves uncertain what is the most
+important. But, I think, our way of argument, which tries to reach the
+problems of greatest importance by degrees, though it may be slow, could
+hardly be called wrong and misleading.
+
+
+β. THE “MEANS” OF MORPHOGENESIS
+
+We now proceed to an analysis of what may properly be called the *means*
+of morphogenesis, the word “means” being preferable to the more usual
+one “conditions” in this connection, as the latter would not cover the
+whole field. It is in quite an unpretentious and merely descriptive
+sense that the expression “means” should be understood at present; what
+is usually called “conditions” is part of the morphogenetic means in our
+sense.
+
+β′. *The Internal Elementary Means of Morphogenesis*
+
+We know that all morphogenesis, typical or atypical, primary or
+secondary, goes on by one morphogenetic elementary process following the
+other. Now the very foundation of these elementary processes themselves
+lies in the elementary functions of the organism as far as they result
+in the formation of stable visible products. Therefore the elementary
+functions of the organism may properly be called the internal “means” of
+morphogenesis.
+
+Secretion and migration are among such functions; the former happening
+by the aid of chemical change or by physical separation, the latter by
+the aid of changes in surface tension. But hardly anything more concrete
+has been made out about these or similar points at present.
+
+We therefore make no claim to offer a complete system of the internal
+elementary means of morphogenesis. We shall only select from the whole
+a few topics of remarkable morphogenetic interest, and say a few words
+about each.
+
+But, first of all, let us observe that the elementary means of
+morphogenesis are far from being morphogenesis themselves. The word
+“means” itself implies as much. It would be possible to understand each
+of these single acts in morphogenesis as well as anything, and yet to be
+as far from understanding the whole as ever. All means of morphogenesis
+are only to be considered as the most general frame of events within
+which morphogenesis occurs.
+
+*Some Remarks on the Importance of Surface Tension in
+Morphogenesis.*--There are a few purely physical phenomena which have
+a special importance in organic morphology, all of them connected
+with capillarity or surface tension. Soap-lather is a very familiar
+thing to all of you: you know that the soap-solution is arranged here
+in very thin planes separated by spaces containing air: it was first
+proved by Berthold[31] that the arrangement of cells in organic tissues
+follows the same type as does the arrangement of the single bubbles of
+a soap-lather, and Bütschli[32] added to this the discovery that the
+minute structure of the protoplasm itself is that of a foam also. Of
+course it is not one fluid and one gas which make up the constituents
+of the structure in the organisms, as is the case in the well-known
+inorganic foams, but two fluids, which do not mix with one another. One
+general law holds for all arrangements of this kind: the so-called law
+of least surfaces, expressed by the words that the sum of all surfaces
+existing is a minimum; and it again is a consequence of this law, if
+discussed mathematically, that four lines will always meet in one point
+and three planes in one line. This feature, together with a certain law
+about the relation of the angles meeting in one line to the size of the
+bubbles, is realised most clearly in many structures of organic tissues,
+and makes it highly probable, at least in some cases, that capillarity
+is at work here. In other cases, as for instance in many plants, a kind
+of outside pressure, the so-called tissue tension, may account for the
+arrangement in surfaces *minimae areae*. Cleavage stages are perhaps
+the very best type in which our physical law is expressed: and here
+it may be said to have quite a simple application whenever all of the
+blastomeres are of the same physical kind, whilst some complications
+appear in germs with a specialised organisation and, therefore,
+with differences in the protoplasm of their single blastomeres. In
+such instances we may say that the physical law holds as far as the
+conditions of the system permit, these conditions ordinarily consisting
+in a sort of non-homogeneity of the surfaces.
+
+[31] *Studien über Protoplasmamechanik*, Leipzig, 1886.
+
+[32] *Unters. üb. mikroskopische Schäume und das Protoplasma*, Leipzig,
+1892.
+
+It seems, from the researches of Dreyer,[33] that the formation of
+organic skeletons may also be governed by the physically conditioned
+arrangement of protoplasmatic or cellular elements, and some phenomena
+of migration and rearrangement among cleavage cells, as described by
+Roux, probably also belong here.
+
+[33] *Jena. Zeitschr.* 26, 1892.
+
+But let us never forget that the laws of surface tension only give
+us the most general type of an arrangement of elements in all these
+cases, nothing else. A physical law never accounts for the Specific!
+Capillarity gives us not the least clue to it. As the organic substance,
+at least in many cases, is a fluid, it must of course follow the general
+laws of hydrostatics and hydrodynamics, but life itself is as little
+touched by its fluid-like or foam-like properties as it is by the fact
+that living bodies have a certain weight and mass.
+
+All indeed that has been described may be said to belong, in the
+broadest meaning of the word, to what is called by Roux “correlation of
+masses,” though this author originally intended to express by this term
+only some sorts of passive pressure and deformation amongst embryonic
+parts as discovered especially by His.
+
+We must be cautious in admitting that any organic feature has been
+explained, even in the most general way, by the action of physical
+forces. What at first seems to be the result of mechanical pressure may
+afterwards be found to be an active process of growth, and what at first
+seems to be a full effect of capillarity among homogeneous elements may
+afterwards be shown to depend on specialised metabolic conditions of the
+surfaces as its principal cause.[34]
+
+[34] According to Zur Strassen’s results the early embryology of
+*Ascaris* proceeds almost exclusively by cellular surface-changes: the
+most typical morphogenetic processes are carried out by the aid of this
+“means.” As a whole, the embryology of *Ascaris* stands quite apart and
+presents a great number of unsolved problems; unfortunately, the germ of
+this form has not been accessible to experiment hitherto.
+
+There are other physical phenomena too, which assist morphogenesis;
+osmotic pressure for instance, which is also well known to operate in
+many purely physiological processes. But all these processes are only
+means of the organism, and can never do more than furnish the general
+type of events. They do not constitute life; they are *used* by life;
+let it remain an open question, for the present, how the phenomenon of
+“life” is to be regarded in general.[35]
+
+[35] Rhumbler has recently published a general survey of all attempts to
+“explain” life, and morphogenesis in particular, in a physico-chemical
+way (“Aus dem Lückengebiet zwischen organismischer und anorganismischer
+Natur,” *Ergeb. Anat. u. Entw.-gesch.* 15, 1906). This *very
+pessimistic* survey is the more valuable as it is written by a convinced
+“mechanist.”
+
+*On Growth*.--Among the internal morphogenetical means which are of
+a so-called physiological character, that is, which nobody claims to
+understand physically at present, there is in the first place *growth*,
+which must be regarded as a very essential one.
+
+Analytically we must carefully discriminate between the increase in the
+size of the cavities of an organism by a passive extension of their
+surfaces and the proper growth of the individual cells, which again
+may be due either to mere extension or to real assimilation. Osmotic
+pressure, of course, plays an important part both in the growth of the
+body-cavities and in simple cellular extension. We repeat the caution
+against believing too much to be explained by this phenomenon: it is the
+organism which by the secretion of osmotic substances in the cavities or
+the protoplasm of the cells prepares the ground for growth even of this
+osmotic sort. The real cellular growth which proceeds on the basis of
+assimilation cannot, of course, be accounted for by osmotic events, not
+even in its most general type.
+
+Ontogenetical growth generally sets in, both in animals and in plants,
+after the chief lines of organisation are laid out; it is only the
+formation of the definite histological structures which usually runs
+parallel to it.
+
+*On Cell-division.*--We have already said a good deal about the
+importance of cell-division in ontogeny: it accompanies very many of the
+processes of organisation in all living beings. But even then, there are
+the Protozoa, in the morphogenesis of which it does not occur at all,
+and there have also become known many cases of morphogenesis in higher
+animals, mostly of the type of regulation, in which cellular division
+is almost or wholly wanting. Therefore, cellular division cannot be
+the true reason of differentiation, but is only a process, which
+though necessary in some cases, cannot be essential to it. It must be
+conceded, I believe, that the same conclusion can be drawn from all our
+experiments on very young stages of the germ.
+
+The investigations of the last few years have made it quite clear that
+even in organisms with a high power of morphogenetic regulation it is
+always the form of the whole, but not the individual cell, which is
+subjected to the regulation processes. Starting from certain results
+obtained by T. H. Morgan, I was able to show that in all the small but
+whole larvae, reared from isolated blastomeres, the size of the cells
+remains normal, only their number being reduced; and Boveri has shown
+most clearly that it is always the size of the nucleus--more correctly,
+the mass of the chromatin--which determines how large a cell of a
+certain histological kind is to be. In this view, the cell appears even
+more as a sort of material used by the organism as supplied, just as
+workmen can build the most different buildings with stones of a given
+size.
+
+
+β″. *The External Means of Morphogenesis*
+
+We now know what internal means of morphogenesis are, and so we may
+glance at some of the most important “outer means” or “conditions” of
+organisation.
+
+Like the adult, the germ also requires a certain amount of heat, oxygen,
+and, when it grows up in the sea, salinity in the medium. For the germ,
+as for the adult, there exists not only a minimum but also a maximum
+limit of all the necessary factors of the medium; the same factor which
+at a certain intensity promotes development, disturbs it from a certain
+other intensity upwards.
+
+Within the limits of this minimum and this maximum of every outside
+agent there generally is an increase in the rate of development
+corresponding to the increase of intensity of the agent. The
+acceleration of development by heat has been shown to follow the law of
+the acceleration of chemical processes by a rise of temperature; that
+seems to prove that certain chemical processes go on during the course
+of morphogenesis.
+
+Almost all that has been investigated of the part played by the external
+conditions of development has little bearing on specific morphogenesis
+proper, and therefore may be left out of account here: we must, however,
+lay great stress on the general fact that there *is* a very close
+dependence of morphogenesis on the outside factors, lest we should be
+accused afterwards of having overlooked it.
+
+Of course all “external” means or conditions of morphogenesis can
+actually relate to morphogenetic processes only by becoming in some way
+“internal,” but we unfortunately have no knowledge whatever how this
+happens. We at present are only able to ascertain what must necessarily
+be accomplished in the medium, in order that normal morphogenesis may go
+on, and we can only suppose that there exist certain specific internal
+general states, indispensable for organogenesis but inaccessible to
+present modes of investigation.[36]
+
+[36] Compare the analytical discussions of Klebs, to whom we owe a great
+series of important discoveries in the field of morphogenetic “means”
+in botany. (*Willkürliche Entwickelungsänderungen bei Pflanzen*, Jena,
+1903; see also *Biol. Centralblatt*, vol. xxiv., 1904, and my reply to
+Klebs, *ibid.* 23, 1903.)
+
+*The Discoveries of Herbst.*--There are but few points in the doctrine
+of the external means or conditions of organogenesis which have a
+more special bearing on the specification of proper form, and which
+therefore require to be described here a little more fully. All
+these researches, which have been carried out almost exclusively by
+Herbst,[37] relate to the effect of the chemical components of sea-water
+upon the development of the sea-urchin. If we select the most important
+of Herbst’s results, we must in the first place say a few words on
+the part taken by lime or calcium, not only in establishing specific
+features of form, but in rendering individual morphogenesis possible at
+all. Herbst has found that in sea-water which is deprived of calcium the
+cleavage cells and many tissue cells also completely lose contact with
+each other: cleavage goes on quite well, but after each single division
+the elements are separated; at the end of the process you find the 808
+cells of the germ together at the bottom of the dish, all swimming about
+like infusoria. There seems to be some influence of the calcium salts
+upon the physical state of the surfaces of the blastomeres.
+
+[37] *Arch. Entw. Mech.* 17, 1904.
+
+It is not without interest to note that this discovery has an important
+bearing on the technical side of all experiments dealing with the
+isolation of blastomeres. Since the separation of the single cleavage
+elements ceases as soon as the germs are brought back from the mixture
+without lime into normal sea-water, it of course is possible to separate
+them up to any stage which it is desired to study, and to keep them
+together afterwards. Thus, if for instance you want to study the
+development of isolated cells of the eight-cell stage, you will leave
+the egg in the artificial mixture containing no calcium until the
+third cleavage, which leads from the four- to the eight-cell stage, is
+finished. The single eight cells brought back to normal sea-water at
+this point will give you the eight embryos you want. All researches
+upon the development of isolated blastomeres since the time of Herbst’s
+discovery have been carried out by this method, and it would have been
+quite impossible by the old method of shaking to pursue the study into
+such minute detail as actually has been done. It may be added that
+calcium, besides its cell-uniting action, is also of primary importance
+in the formation of the skeleton.
+
+Among all the other very numerous studies of Herbst we need only mention
+that potassium is necessary for the typical growth of the intestine,
+just as this element has been found necessary for normal growth in
+plants, and that there must be the ion SO_4, or in other terms,
+sulphur salts present in the water, in order that the germs may acquire
+their pigments and their bilateral symmetry. This is indeed a very
+important result, though it cannot be said to be properly understood. It
+is a fact that in water without sulphates the larvae of Echinus retain
+the radial symmetry they have had in the very earliest stages, and may
+even preserve that symmetry on being brought back to normal sea-water if
+they have spent about twenty-four hours in the artificial mixture.
+
+We may now leave the subject of Herbst’s attempts to discover the
+morphogenetic function of the single constituents of normal sea-water,
+and may devote a few words to the other branch of his investigations,
+those dealing with the morphogenetic effects of substances which are not
+present in the water of the sea, but have been added to it artificially.
+Here, among many other achievements, Herbst has made the most
+important discovery that all salts of lithium effect radical changes
+in development.[38] I cannot describe fully here how the so-called
+“lithium larva” originates; let me only mention that its endoderm is
+formed outside instead of inside, that it is far too large, that there
+is a spherical mass between the ectodermal and the endodermal part of
+the germ, that a radial symmetry is established in place of the normal
+bilateralism, that no skeleton exists, and that the mesenchyme cells
+are placed in a quite abnormal position. All these features, though
+abnormal, are typical of the development in lithium. The larvae present
+no really pathological appearance at all, and, therefore, it may indeed
+be said that lithium salts are able to change fundamentally the whole
+course of morphogenesis. It detracts nothing from the importance of
+these discoveries that, at present, they stand quite isolated: only with
+lithium salts has Herbst obtained such strange results, and only upon
+the eggs of echinids, not even upon those of asterids, do lithium salts
+act in this way.
+
+[38] *Zeitschr. wiss. Zool.* 55, 1902; and *Mitt. Neapel.* 11, 1903.
+
+
+γ. THE FORMATIVE CAUSES OR STIMULI
+
+*The Definition of Cause*
+
+We cannot begin the study of the “causes” of the differentiation of
+form without a few words of explanation about the terminology which we
+shall apply. Causality is the most disputed of all categories; many
+modern scientists, particularly in physics, try to avoid the concept of
+cause altogether, and to replace it by mere functional dependence in
+the mathematical meaning of the term. They claim to express completely
+by an equation all that is discoverable about any sort of phenomena
+constantly connected.
+
+I cannot convince myself that such a very restricted view is the right
+one: it is very cautious, no doubt, but it is incomplete, for we *have*
+the concept of the acting “cause” in our Ego and are *forced* to search
+for applications of it in Nature. On the other hand, it does not at all
+escape me that there are many difficulties, or rather ambiguities, in
+applying it.
+
+We may call the “cause” of any event, the sum total of all the
+constellations of facts which must be completed in order that the event
+may occur; it is in this meaning, for instance, that the first principle
+of energetics applies the term in the words *causa aequat effectum*.
+But, by using the word only in this very general sense, we deprive
+ourselves of many conveniences in the further and more particular study
+of Nature. Would it be better to say that the “cause” of any event is
+the very last change which, after all the constellations necessary for
+its start are accomplished, must still take place in order that the
+event may actually occur? Let us see what would follow from such a use
+of the word causality. We here have an animal germ in a certain stage,
+say a larva of Echinus, which is just about to form the intestine; all
+the internal conditions are fulfilled, and there is also a certain
+temperature, a certain salinity, and so on, but there is no oxygen in
+the water: the intestine; of course, will not grow in such a state of
+things, but it soon will when oxygen is allowed to enter the dish.
+Is, therefore, oxygen the cause of the formation of the intestine of
+echinus? Nobody, I think, would care to say so. By such reasoning,
+indeed, the temperature, or sodium, might be called the “cause” of
+any special process of morphogenesis. It, therefore, seems to be of
+little use to give the name of cause to that factor of any necessary
+constellation of events which accidentally happens to be the last that
+is realised. But what is to be done then?
+
+Might we not say that the cause of any morphogenetic process is that
+typical property, or quality, or change, on which its specific character
+depends, on which depends for example, the fact that now it is the
+intestine which appears, while at another time it is the lens of the
+eye? We might very well, but we already have our term for this sort
+of cause, which is nothing else than our prospective potency applied
+to that elementary organ from which the new process takes its origin.
+The prospective potency indeed is the truly immanent cause of every
+specification affecting single organogenetic processes. But we want
+something more than this.
+
+We may find what we want by considering that each single elementary
+process or development not only has its specification, but also has
+its specific and typical place in the whole--its locality. Therefore
+we shall call the “cause” of a single morphogenetic process, that
+occurrence on which depends its *localisation*, whether its specific
+character also partly depends on this “cause” or not.[39]
+
+[39] In certain cases part of the specific feature of the process in
+question may also depend on the “cause” which is localising it, *e.g.*
+in the galls of plants.
+
+This definition of “cause” in morphology may be artificial; in any
+case it is clear. And at the same time the concepts of the prospective
+potency and of the “means” of organogenesis now acquire a clear and
+definite meaning: potency is the real basis of the specific character
+of every act in morphogenesis, and “means,” including conditions, are
+the sum of all external and internal general circumstances which must be
+present in order that morphogenetic processes may go on, without being
+responsible for their specificity or localisation.
+
+It is implied in these definitions of cause and potency, that the former
+almost always will be of that general type which usually is called a
+stimulus or “Auslösung,” to use the untranslatable German word. There is
+no quantitative correspondence between our “cause” and the morphogenetic
+effect.
+
+*Some Instances of Formative and Directive Stimuli*
+
+Again it is to Herbst that we owe not only a very thorough logical
+analysis of what he calls “formative and directive stimuli”[40] but also
+some important discoveries on this subject. We cannot do more here than
+barely mention some of the most characteristic facts.
+
+[40] Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale
+Auffassung von Vorgängen in der tierischen Ontogenese” (*Biol.
+Centralblatt*, vols. xiv., 1894, and xv., 1895); *Formative Reize in der
+tierischen Ontogenese*, Leipzig, 1901. These important papers must be
+studied by every one who wishes to become familiar with the subject. The
+present state of science is reviewed in my articles in the *Ergebnisse
+der Anatomie und Entwickelungsgeschichte*, vols. xi. and xiv., 1902 and
+1905.
+
+Amongst plants it has long been known that the direction of light or of
+gravity may determine where roots or branches or other morphogenetic
+formations are to arise; in hydroids also we know that these factors
+of the medium may be at work[41] as morphogenetic causes, though most
+of the typical architecture of hydroid colonies certainly is due to
+internal causes, as is also much of the organisation in plants.
+
+[41] Compare the important papers by J. Loeb, *Untersuchungen zur
+physiologischen Morphologie der Tiere*, Würzburg, 1891-2.
+
+Light and gravity are external formative causes; beside that they are
+merely “localisers.” But there also are some external formative stimuli,
+on which depends not only the place of the effect, but also part of its
+specification. The galls of plants are the most typical organogenetic
+results of such stimuli. The potencies of the plant and the specific
+kind of the stimulus equally contribute to their specification; for
+several kinds of galls may originate on one sort of leaves.
+
+Scarcely any exterior formative stimuli are responsible for animal
+organisation; and one would hardly be wrong in saying that this
+morphogenetic independence in animals is due to their comparatively
+far-reaching functional independence of those external agents which
+have any sort of direction. But many organogenetic relations are known
+to exist between the single parts of animal germs, each of these parts
+being in some respect external to every other; and, indeed, it might
+have been expected already *a priori*, that such formative relations
+between the parts of an animal embryo must exist, after all we have
+learned about the chief lines of early embryology. If differentiation
+does not go on after the scheme of Weismann, that is, if it is not
+carried out by true “evolutio” from within, how could it be effected
+except from without? Indeed, every embryonic part may in some respect be
+a possible cause for morphogenetic events, which are to occur on every
+other part: it is here that the very roots of epigenesis are to be found.
+
+Heliotropism and geotropism are among the well-known physiological
+functions of plants: the roots are seen to bend away from the light and
+towards the ground; the branches behave just in the opposite way. It now
+has been supposed by Herbst that such “directive stimuli” may also be
+at work among the growing or wandering parts of the embryo, that their
+growth or their migration may be determined by the typical character of
+other parts, and that real morphogenetic characters can be the result of
+some such relation; a sort of “chemotropism” or “chemotaxis” may be at
+work here. Herbst himself has discussed theoretically several cases of
+organogenesis in which the action of directive stimuli is very probable.
+What has become actually known by experiment is not very much at
+present: the mesenchyme cells of Echinus are directed in their migration
+by specified places in the ectoderm, the pigment cells of the yolk-sac
+of the fish fundulus are attracted by its blood vessels, and nerves
+may be forced to turn into little tubes containing brain substance;
+but of course only the first two instances have any bearing on typical
+morphogenesis.
+
+The first case of an “internal formative stimulus” in the proper sense,
+that is, of one embryonic part causing another to appear, was discovered
+by Herbst himself. The arms of the so-called pluteus of the sea-urchin
+are in formative dependence on the skeleton--no skeleton, no arms; so
+many skeleton primordia,[42] in abnormal cases, so many arms; abnormal
+position of the skeleton, abnormal position of the arms: these three
+experimental observations form the proof of this morphogenetic relation.
+
+[42] I use the word “primordia” for the German “Anlage”; it is better
+than the word “rudiment,” as the latter may also serve to signify
+the very last stage of a certain formation that is disappearing
+(phylogenetically).
+
+It may be simple mechanical contact, or it may be some chemical
+influence that really constitutes the “stimulus” in this case;
+certainly, there exists a close and very specific relation of the
+localisation of one part of the embryo to another. Things are much the
+same in another case, which, after having been hypothetically stated
+by Herbst on the basis of pathological data, was proved experimentally
+by Spemann. The lens of the eye of certain Amphibia is formed of their
+skin in response to a formative stimulus proceeding from the so-called
+primary optic vesicle. If this vesicle fails to touch the skin, no lens
+appears; and, on the other hand, the lens may appear in quite abnormal
+parts of the skin if they come into contact with the optic vesicle after
+transplantation.
+
+But formative dependence of parts may also be of different types.
+
+We owe to Herbst the important discovery that the eyes of crayfishes,
+after being cut off, will be regenerated in the proper way, if the optic
+ganglion is present, but that an antenna will arise in their place
+if this ganglion has also been removed. There must in this case be
+some unknown influence of the formative kind on which depends, if not
+regeneration itself, at least its special character.
+
+In other cases there seems to be an influence of the central nervous
+system on the regenerative power in general. Amphibia, for instance,
+are said to regenerate neither their legs (Wolff), nor their tail
+(Godlewski), if the nervous communications have been disturbed. But
+in other animals there is no such influence; and in yet others, as
+for instance, in Planarians, it must seem doubtful at present whether
+the morphogenetic influence of the nervous system upon processes of
+restoration is more than indirect; the movements of the animal, which
+become very much reduced by the extirpation of the ganglia, being one of
+the main conditions of a good regeneration.
+
+Of course, all we have said about the importance of special materials
+in the ripe germ, as bearing on specifically localised organisations,
+might be discussed again in our present chapter, and our intimate
+polar-bilateral structure of germs may also be regarded as embracing
+formative stimuli, at any rate as far as the actual poles of this
+structure are concerned. This again would bring us to the problem of
+so-called “polarity” in general, and to the “inversion” of polarity,
+that is to a phenomenon well known in plants and in many hydroids and
+worms, viz., that morphogenetic processes, especially of the type of
+restitutions, occur differently, according as their point of origin
+represents, so to speak, the positive or the negative, the terminal or
+the basal end of an axis, but that under certain conditions the reverse
+may also be the case. But a fuller discussion of these important facts
+would lead us deeper and deeper into the science of morphogenesis
+proper, without being of much use for our future considerations.
+
+And so we may close this section[43] on formative stimuli or “causes”
+of morphogenesis by shortly adding, more on account of its factual
+than of its logical interest, that the phenomenon of the determination
+of sex,[44] according to the latest researches, seems to depend on
+cytological events occurring in the very earliest embryonic stages,
+say even before ontogeny, and not on formative stimuli proper[45]: it
+seems, indeed, as if the sexual products themselves would account for
+the sex of the individual produced by them, particularly if there were
+differences in their chromatin.[46]
+
+[43] A full analysis of the subject would not only have to deal with
+formative stimuli as inaugurating morphogenetic processes, but also with
+those stimuli which terminate or stop the single acts of morphogenesis.
+But little is actually known about this topic, and therefore the reader
+must refer to my other publications. I will only say here, that the end
+of each single morphogenetic act may either be determined at the very
+beginning or occur as an actual stopping of a process which otherwise
+would go on for ever and ever; in the first case some terminating
+factors are included in the very nature of the morphogenetic act itself.
+
+[44] A full account of the present state of the subject will be found in
+Morgan’s *Experimental Zoology*, New York, 1907.
+
+[45] But there certainly exist many formative relations between the real
+sexual organs and the so-called secondary sexual characters. Herbst has
+given a full analytical discussion of all that is known on this subject;
+but the facts are much more complicated than is generally supposed, and
+do not lend themselves therefore to short description. See also Foges,
+*Pflüger’s Arch.* 93, 1902.
+
+[46] It seems that in some cases (*Dinophilus*, certain Arthropods)
+the sexual products are invariably determined as “arrenogennetic”
+or as “thelygennetic” (Wilson, *Journ. Exp. Zool.* ii. and iii.
+1905-6), whilst in others (Amphibia) the state of maturation or
+“super”-maturation determines the sex of the future organism (R.
+Hertwig, *Verh. D. Zool. Ges.* 1905-7).
+
+
+δ. THE MORPHOGENETIC HARMONIES
+
+Let us now turn again to considerations of a more abstract kind: we have
+become acquainted with some morphogenetic interactions among the parts
+of a developing embryo; and, indeed, we can be sure that there exist far
+more of such interactions than we know at present.
+
+But it is far from being true that the development of each embryonic
+part depends on the existence or development of every other one.
+
+On the contrary, it is a very important and fundamental feature
+of organogenesis that it occurs in separate lines, that is to
+say, in lines of processes which may start from a common root, but
+which are absolutely independent of one another in their manner of
+differentiation. Roux has coined the term “self-differentiation” to
+denote this phenomenon, and we admit that this term may be conveniently
+used for the purpose, if only it can be kept in mind that its sense is
+always relative, and that it is also negative. Suppose a part, *A*,
+shows the phenomenon of self-differentiation: this means that the
+further development of *A* is not dependent on certain other parts,
+*B*, *C*, and *D*; it does *not* mean at all that *A* has not been
+formatively dependent on some other parts, *E* or *F* at the time of
+its first appearance, nor does it imply that there might not be many
+formative actions among the constituents of *A* itself.
+
+We indeed are entitled to say that the ectoderm of Echinus shows
+“self-differentiation” with regard to the endoderm; it acquires its
+mouth, for instance, as has been shown by experiment, even in cases
+where no intestine is present at all (Fig. 10); but ectoderm and
+endoderm both are formatively dependent on the intimate and the material
+organisation of the blastoderm. It further seems from the most recent
+experiments that the nerves and the muscles of the vertebrates are
+independent of each other in their differentiation, but that their fate
+is probably determined by formative processes in the very earliest
+stages of ontogeny.
+
+[Illustration: Fig. 10.--Pluteus-larva of Sphaerechinus.
+
+The Intestine (i) is developed outside instead of inside (by means of
+raising the temperature); but the mouth (r) is formed in its normal
+place. S = Skeleton.]
+
+The phenomenon of self-differentiation, properly understood, now may
+help to the discovery of one most general character of all development.
+If the phenomenon of self-differentiation really occurs in ontogeny
+in its most different aspects, and if, on the other hand, in spite
+of this relative morphogenetic independence of embryonic parts, the
+resulting organism is one whole in organisation and in function, some
+sort of *harmony of constellation*, as it may properly be styled, must
+be said to be one of the most fundamental characters of all production
+of individual form. In establishing this harmony we do nothing more
+than describe exactly what happens: the harmony is shown by the fact
+that there is a whole organism at the end, in spite of the relative
+independence of the single events leading to it.
+
+But still another sort of harmony is revealed in morphogenesis, by an
+analysis of the general conditions of the formative actions themselves.
+In order that these actions may go on properly the possibility must be
+guaranteed that the formative causes may always find something upon
+which to act, and that those parts which contain the potencies for the
+next ontogenetic stage may properly receive the stimuli awaking these
+potencies: otherwise there would be no typical production of form at
+all. This, the second species of harmonious relations to be described in
+ontogeny, may be called *causal harmony*; the term simply expresses the
+unfailing relative condition of formative causes and cause-recipients.
+
+Finally, in *functional harmony* we have an expression descriptive
+of the unity of organic function, and so we may state, as the latest
+result of our analytical theory of development up to this point, that
+individual morphogenesis is marked by a *threefold harmony* among its
+parts.
+
+
+ε. ON RESTITUTIONS[47]
+
+[47] Driesch, *Die organischen Regulationen*, Leipzig, 1901; Morgan,
+*Regeneration*, New York, 1901.
+
+At this stage we leave for a while our analytical studies of ontogeny
+proper. We must not forget that typical ontogenesis is not the only form
+in which morphogenesis can occur: the organic form is able to restore
+disturbances of its organisation, and it certainly is to be regarded as
+one of the chief problems of analytical morphogenesis to discover the
+specific and real stimulus which calls forth the restoring processes.
+For simply to say that the disturbance is the cause of the restoration
+would be to evade the problem instead of attacking it. But there are
+still some other problems peculiar to the doctrine of restitutions.
+
+*A few Remarks on Secondary Potencies and on Secondary Morphogenetic
+Regulations in General*
+
+We have only briefly mentioned in a previous chapter that there
+exist many kinds of potencies of what we call the secondary or truly
+restitutive type, and that their distribution may be most various and
+quite independent of all the potencies for the primary processes
+of ontogeny proper. Let us first add a few words about the concept
+of “secondary restitution” and about the distribution of secondary
+potencies in general.
+
+Primary ontogenetic processes founded upon primary potencies may *imply*
+regulation, or more correctly, restitution in many cases: so it is,
+when fragments of the blastula form the whole organism, or when the
+mesenchyme cells of Echinus reach their normal final position by an
+attraction on the part of specific localities of the ectoderm in spite
+of a very abnormal original position enforced upon them by experiment.
+In these cases we speak of primary regulations or restitutions;
+disturbances are neutralised by the very nature of the process in
+question. We speak of secondary restitution whenever a disturbance
+of organisation is rectified by processes foreign to the realm of
+normality; and these abnormal lines of events are revealed to us in the
+first place by the activity of potencies which remain latent in ontogeny
+proper.
+
+We know already that a certain kind of secondary restitution has
+been discovered lately, very contradictory to the theoretical views
+of Weismann; the process of restoration being carried out not by any
+definite part of the disturbed organisation, but by all the single
+elements of it. The problem of the distribution of secondary potencies
+in these cases of so-called “re-differentiation” is to form our special
+study in the next chapter. In all other cases restoration processes
+start from specific localities; if they occur on the site of the
+wound which caused the disturbance, we speak of regeneration; if they
+occur at some distance from the wound, we call them adventitious
+processes. Besides these three types of processes of restitution there
+may be mentioned a fourth one, consisting in what is generally called
+compensatory hypertrophy; the most simple case of such a compensatory
+process is when one of a pair of organs, say a kidney, becomes larger
+after the other has been removed.[48] Finally, at least in plants, a
+change of the directive irritability, of so-called “geotropism” for
+instance, in certain parts may serve to restore other more important
+parts.
+
+[48] But real compensatory differentiation occurs in the cases of
+so-called “hypertypy” as first discovered by Przibram and afterwards
+studied by Zeleny: here the two organs of a pair show a different degree
+of differentiation. Whenever the more specialised organ is removed the
+less developed one assumes its form. Similar cases, which might simply
+be called “compensatory heterotypy,” are known in plants, though only
+relating to the actual fate of undifferentiated “Anlagen” in these
+organisms. A leaf may be formed out of the Anlage of a scale, if all the
+leaves are cut off, and so on.
+
+In two of these general types of restitution, in regeneration proper and
+in the production of adventitious organs, the potencies which underlie
+these processes may be said to be “complex.” It is a complicated series
+of events, a proper morphogenesis in itself, for which the potency
+has to account, if, for instance, a worm newly forms its head by
+regeneration, or if a plant restores a whole branch in the form of an
+adventitious bud.
+
+Such generalisations as are possible about the distribution of complex
+potencies are reserved for a special part of our future discussion.
+
+Secondary restitution is always, like ontogeny, a process of
+morphogenesis, and therefore all the questions about single formative
+stimuli, and about internal and external conditions or means, occur
+again. But of course we cannot enter into these problems a second time,
+and may only say that, especially in regeneration proper, the specific
+type of the regenerative formation of any part may differ very much from
+the ontogenetic type of its origin: the end of both is the same, but the
+way can be even fundamentally different in every respect.
+
+*The Stimuli of Restitutions*[49]
+
+[49] For a fuller analysis compare my opening address delivered before
+the section of “Experimental Zoology” at the Seventh Zoological
+Congress, Boston, 1907: “The Stimuli of Restitutions” (see Proceedings
+of that Congress).
+
+But now we turn to the important question: what is the precise
+stimulus[50] that calls forth processes of restitution; or, in other
+words, what must have happened in order that restitution may occur?
+
+[50] The problem of the stimulus of a secondary restitution as a
+whole must not be confused with the very different question, what the
+single “formative stimuli” concerned in the performance of a certain
+restitutive act may be. With regard to restitution as a *whole* these
+single “formative stimuli” might properly be said to belong to its
+“internal means”--in the widest sense of the word.
+
+That the operation in itself, by its removing of mechanical obstacles,
+cannot be the true stimulus of any restitutions, is simply shown by all
+those restitutions that do not happen at the place of the wound. If we
+took a narrower point of view, and if we only considered regeneration
+proper from the wound itself, we might probably at first be inclined to
+advocate the doctrine that the removing of some obstacles might in fact
+be the stimulus to the process of restoration; but, even then, why is
+it that just what is wanted grows out? Why is there not only growth,
+but specific growth, growth followed by specification? The removing
+of an obstacle could hardly account for that. But, of course, taking
+account of all the adventitious restitutions--that is, all restorations
+not beginning at the wound itself--the theory that the removing of
+obstacles is the stimulus to restoration becomes, as we have said, quite
+impossible.[51]
+
+[51] T. H. Morgan is very right in stating that, in regeneration, the
+“obstacle” itself is newly formed by the mere process of healing,
+previous to all restitution, and that true restitution happens all the
+same.
+
+But where then is the stimulus to be found? There is another rather
+simple theory of the “Auslösung” of restitutions,[52] which starts
+from the phenomena of compensatory hypertrophy and some occurrences
+among plants. The removal of some parts of the organism, it is said,
+will bring its other parts into better conditions of nutrition, and
+therefore these parts, particularly if they are of the same kind, will
+become larger. Granted for the moment that such a view may hold in cases
+when one of a pair of glands becomes larger after the other has been
+removed, or when pruning of almost all the leaves of a tree leads to the
+rest becoming larger, it certainly must fail to explain the fact that
+in other cases true *new* formations may arise in order to restore a
+damaged part, or that the latter may be regenerated in its proper way.
+For *merely quantitative* differences in the mixture of the blood or of
+the nourishing sap in plants can never be a sufficient reason for the
+highly typical and *qualitative* structure of newly-formed restitutions.
+And even in the most simple cases of a mere increase in the size of
+some parts, that is, in the simplest cases of so-called compensatory
+hypertrophy,[53] it is at least doubtful, if not very improbable, that
+the compensation is accomplished in such a purely passive way, because
+we know that in other cases it is usually the growth of the young parts
+that actively attracts the nourishment: there is first differentiation
+and growth, and *afterwards* there is a change in the direction of the
+nourishing fluids.
+
+[52] I merely mention here the still “simpler” one--applicable of course
+to regeneration proper exclusively--that for the simple reason of being
+“wounded,” *i.e.* being a surface open to the medium, the “wound” brings
+forth all that is necessary to complete the organism.
+
+[53] That compensatory hypertrophy cannot be due to “functional
+adaptation”--to be analysed later on--was proved by an experiment of
+Ribbert’s. Compensation may occur before the function has made its
+appearance, as was shown to be the case in the testicles and mammae of
+rabbits. (*Arch. Entw. Mech.* 1, 1894, p. 69.)
+
+The process of true regeneration, beginning at the locality of the wound
+itself, has been shown by Morgan, even as regards its rate, to occur
+quite irrespectively of the animal being fed or not.[54] There could
+hardly be a better demonstration of the fundamental fact that food
+assists restitution, but does not “cause” it in any way.
+
+[54] At any given time only the absolute size of the regenerated part is
+greater in animals which are well fed; the degree of differentiation is
+the same in all. Zeleny has found that, if all five arms of a starfish
+are removed, each one of them will regenerate more material in a given
+time than it would have done if it alone had been removed. But these
+differences also only relate to absolute size and not to the degree
+of differentiation. They possibly may be due in fact to conditions of
+nourishment, but even here other explanations seems possible (Zeleny,
+*Journ. exp. Zool.* 2, 1905).
+
+But in spite of all we have said, there seems to be some truth in
+regarding the nutritive juices of animals and plants as somehow
+connected with the stimulus of restitutions: only in this very cautious
+form, however, may we make the hypothesis. It has been shown for both
+animals and plants, that morphogenesis of the restitutive type may be
+called forth even if the parts, now to be “regenerated” have not been
+actually removed; *e.g.* in the so-called super-regeneration of legs
+and tails in Amphibia, of the head in Planarians, of the root-tip in
+plants and in some other cases. Here it has always been a disturbance
+of the normal connection of some parts with the rest of the organism
+which proved to be the reason of the new formation. This shows that
+something to do with the communication among parts is at least connected
+with restitution, and this communication may go on either by the unknown
+action of specific tissues or by the aid of the blood or sap.[55] But
+in what this change or break of specific communication consists, is
+absolutely unknown. One might suppose that each part of the organisation
+constantly adds some sort of ferment to the body fluids outside or
+inside the cells, that the removing of any part will change the
+composition of these fluids in this particular respect, and that this
+change acts as a sort of communication to summon the restituting parts
+of the whole to do their duty.[56]
+
+[55] For a good discussion of “super-regeneration” in the roots of
+plants see Němec, *Studien über die Regeneration*, Berlin, 1905. Goebel
+and Winkler have succeeded in provoking the “restitution” of parts which
+were not removed at all by simply stopping their functions (leaves of
+certain plants were covered with plaster, etc.). (*Biol. Centralbl.* 22,
+1902, p. 385; *Ber. Bot. Ges.* 20, 1902, p. 81.) A fine experiment is
+due to Miehe. The alga *Cladophora* was subjected to “plasmolysis,” each
+cell then formed a new membrane of its own around the smaller volume of
+its protoplasm; after that the plants were brought back to a medium of
+normal osmotic pressure, and then each single cell grew up into a little
+plant (all of them being of the same polarity!). Two questions seem
+to be answered by this fact: loss of communication is of fundamental
+importance to restitution, and the removal of mechanical obstacles plays
+no part in it, for the mechanical resistances were the same at the end
+of the experiment as they had been at the beginning. (*Ber. Bot. Ges.*
+23, 1905, p. 257.) For fuller analysis of all the problems of this
+chapter see my Organische Regulationen, my reviews in the *Ergebnisse
+der Anatomie und Entwickelungsgeschichte*, vols. viii. xi. xiv., and
+my Boston address mentioned above. Compare also Fitting, *Ergebn. d.
+Physiol.* vols. iv. and v.
+
+[56] The so-called “inner secretion” in physiology proper would offer a
+certain analogy to the facts assumed by such an hypothesis. Compare the
+excellent summary given by E. Starling at the seventy-eighth meeting of
+the German “Naturforscherversammlung,” Stuttgart, 1906.
+
+But I see quite well that such a theory is very little satisfactory;
+for what has to be done in restitution in each case is not a simple
+homogeneous act, for which one special material might account, but is
+a very complicated work in itself. It was the defect of the theory of
+“organ-forming substances” as advocated by Sachs, that it overlooked
+this point.
+
+So all we know about the proper stimuli of restitutions is far from
+resting on any valid grounds at all; let us not forget that we are
+here on the uncertain ground of what may be called the newest and
+most up-to-date branch of the physiology of form. No doubt, there
+will be something discovered some day, and the idea of the “whole” in
+organisation will probably play some part in it. But in what manner that
+will happen we are quite unable to predict.
+
+This is the first time that, hypothetically at least, the idea of the
+whole has entered into our discussion. The same idea may be said to
+have entered it already in a more implicit form in the statement of the
+threefold harmony in ontogeny.
+
+Let us now see whether we can find the same problem of the “whole”
+elsewhere, and perhaps in more explicit and less hypothetical form.
+Let us see whether our analytical theory of development is in fact as
+complete as it seemed to be, whether there are no gaps left in it which
+will have to be filled up.
+
+
+3. THE PROBLEM OF MORPHOGENETIC LOCALISATION
+
+α. THE THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM
+
+FIRST PROOF OF THE AUTONOMY OF LIFE
+
+We have come to the central point of the first part of these lectures;
+we shall try in this chapter to decide a question which is to give life
+its place in Nature, and biology its place in the system of sciences.
+One of the foundation stones is to be laid upon which our future
+philosophy of the organism will rest.
+
+
+*The General Problem*
+
+Our analytical theory of morphogenesis has been founded upon three
+elementary concepts: the prospective potency, the means, and the
+formative stimulus. Its principal object has been to show that all
+morphogenesis may be resolved into the three phenomena expressed by
+those concepts; in other terms, that morphogenesis may be proved to
+consist simply and solely of what is expressed by them. Have we indeed
+succeeded in attaining this object? Has nothing been left out? Is it
+really possible to explain every morphogenetic event, at least in the
+most general way, by the aid of the terms potency, means, and stimulus?
+
+All of these questions are apt to lead us to further considerations.
+Perhaps these considerations will give us a very clear and simple result
+by convincing us that it is indeed possible to analyse morphogenesis in
+our schematic way.
+
+But if the answer were a negative one? What would that suggest?
+
+The full analysis of morphogenesis into a series of single formative
+occurrences, brought about by the use of given means and on the basis of
+given potencies, might assure us, perhaps, that, though not yet, still
+at some future time, a further sort of analysis will be possible: the
+analysis into the elemental facts studied by the sciences of inorganic
+nature. The organism might prove to be a machine, not only in its
+functions but also in its very origin.
+
+But what are we to say if even the preliminary analysis, which possibly
+might lead to such an ultimate result, fails?
+
+Let us then set to work. Let us try to consider most carefully the topic
+in which our concept of the formative cause or stimulus may be said
+to be centred, the *localisation* of all morphogenetic effects. Is it
+always possible in fact to account for the typical localisation of every
+morphogenetic effect by the discovery of a single specific formative
+stimulus? You will answer me, that such an analysis certainly is not
+possible at present. But I ask you again, are there any criteria that it
+is possible, at least in principle; or are there any criteria which will
+render such an aim of science impossible for all future time?
+
+
+*The Morphogenetic “System”*
+
+We know from our experimental work that many, if not all, of the
+elementary organs in ontogeny show one and the same prospective
+potency distributed equally over their elements. If we now borrow a
+very convenient term from mechanics, and call any part of the organism
+which is considered as a unit from any morphogenetic point of view, a
+morphogenetic “*system*,” we may sum up what we have learnt by saying
+that both the blastoderm of the echinoderms, at least around its
+polar axis, and also the germ-layers of these animals, are “systems”
+possessing an equal potentiality in all of their elements, or, in short,
+that they are *equipotential systems*.
+
+But such a term would not altogether indicate the real character of
+these systems.
+
+Later on we shall analyse more carefully than before the distribution
+of potencies which are the foundation both of regeneration proper and
+of adventitious growth, and then we shall see that, in higher plants
+for instance, there is a certain “system” which may be called the
+organ proper of restitutions, and which also in each of its elements
+possesses the same restoring potency; I refer to the well-known cambium.
+This cambium, therefore, also deserves the name of an “equipotential
+system.” But we know already that its potencies are of the complex
+type, that they consist in the faculty of producing the *whole*, of
+such a complicated organisation as a branch or a root, that the term
+“equipotential system” is here only to signify that such a complicated
+unit may arise out of each of the cells of the cambium.
+
+The potencies we have been studying in the blastula or gastrula of
+echinoderms are not of the complex type: our systems are equipotential
+to the extent that each of their elements may play every *single* part
+in the totality of what will occur in the whole system; it is to
+this *single* part that the term “function of the position” relates.
+We therefore might call our systems equipotential systems with single
+potencies; or, more shortly, singular-equipotential systems.
+
+But even this terminology would fail to touch precisely the very
+centre of facts: it is not only the simplicity or singularity of
+their potencies which characterises the rôle of our systems in
+morphogenesis,[57] but far more important with respect to the production
+of form are two other leading results of the experimental researches.
+The proper act to be performed by every element in each actual case is
+in fact a single one, but the potency of any element as such consists
+in the possibility of many, nay of indefinitely many, single acts:
+that then might justify us in speaking of our systems as “indefinite
+equipotential,” were it not that another reason makes another title seem
+still more preferable. There are indeed indefinite singular potencies at
+work in all of our systems during ontogeny: but the sum of what happens
+to arise in every case out of the sum of the single acts performed by
+all of the single equipotential cells is not merely a sum but a unit;
+that is to say, there exists a sort of harmony in every case among the
+*real products* of our systems. The term *harmonious-equipotential
+system* therefore seems to be the right one to denote them.
+
+[57] The name of singular-equipotential systems might also be applied
+to elementary organs, the single potencies of which are awaked to
+organogenesis by specific formative stimuli from without; but that is
+not the case in the systems studied in this chapter.
+
+We now shall try first to analyse to its very extremes the meaning of
+the statement that a morphogenetic system is harmonious-equipotential.
+
+
+*The “Harmonious-Equipotential System”*
+
+We have an ectoderm of the gastrula of a starfish here before us; we
+know that we may cut off any part of it in any direction, and that
+nevertheless the differentiation of the ectoderm may go on perfectly
+well and result in a typical little embryo, which is only smaller in
+its size than it would normally be. It is by studying the formation of
+the highly complicated ciliary band, that these phenomena can be most
+clearly understood.
+
+Now let us imagine our ectoderm to be a cylinder instead of being
+approximately a sphere, and let us imagine the surface of this cylinder
+unrolled. It will give us a plane of two definite dimensions, *a* and
+*b*. And now we have all the means necessary for the analytical study of
+the differentiation of an harmonious-equipotential system.
+
+Our plane of the dimensions *a* and *b* is the basis of the normal,
+undisturbed development; taking the sides of the plane as fixed
+localities for orientation, we can say that the actual fate, the
+“prospective value” of every element of the plane stands in a fixed and
+definite correlation to the length of two lines, drawn at right angles
+to the bordering lines of the plane; or, to speak analytically, there
+is a definite actual fate corresponding to each possible value of *x*
+and of *y*. Now, we have been able to state by our experimental work,
+that the prospective value of the elements of our embryonic organ is not
+identical with their “prospective potency,” or their possible fate, this
+potency being very much richer in content than is shown by a single case
+of ontogeny. What will be the analytical expression of such a relation?
+
+Let us put the question in the following way: on what factors does
+the fate of any element of our system depend in all possible cases
+of development obtainable by means of operations? We may express our
+results in the form of an equation:--
+
+    *p.v. (X) = f( ... )*
+
+*i.e.* “the prospective value of the element *X* is a function of
+...”--of what?
+
+We know that we may take off any part of the whole, as to quantity, and
+that a proportionate embryo will result, unless the part removed is of
+a very large size. This means that the prospective value of any element
+certainly depends on, certainly is a function of, the *absolute size*
+of the actually existing part of our system in the particular case. Let
+*s* be the absolute size of the system in any actual experimental case
+of morphogenesis: then we may write *p.v. (X) = f(s ... )*. But we
+shall have to add still some other letter to this *s*.
+
+The operation of section was without restriction either as to the
+amount of the material removed from the germ, or as to the direction of
+the cut. Of course, in almost every actual case there will be both a
+definite size of the actual system and a definite direction of the cut
+going hand-in-hand. But in order to study independently the importance
+of the variable direction alone, let us imagine that we have isolated
+at one time that part of our system which is bounded by the lines *a_1
+b_1*, and at another time an equal amount of it which has the lines
+*a_2 b_2* as its boundaries. Now since in both cases a typical small
+organism may result on development, we see that, in spite of their equal
+size the prospective value of every element of the two pieces cut
+out of the germ may vary even in relation to the direction of the cut
+itself. Our element, *X*, may belong to both of these pieces of the same
+size: its actual fate nevertheless will be different. Analytically, it
+may be said to change in correspondence to the actual position of the
+actual boundary lines of the piece itself with regard to the fundamental
+lines of orientation, *a* and *b*; let this actual position be expressed
+by the letter *l*, *l* marking the distance of one[58] of the actual
+boundary lines of our piece from *a* or *b*: then we are entitled to
+improve our formula by writing *p.v. (X) = f(s, l ... )* (Fig.
+11).
+
+[58] The distance of the other boundary line from *a* or *b* would be
+given by the value of *s*.
+
+[Illustration: Fig. 11.--Diagram to show the Characteristics of an
+“Harmonious-equipotential System.”
+
+The element *X* forms part of the systems *a b* or *a_1 b_1* or
+*a_2 b_2*; its prospective value is different in each case.]
+
+But the formula is not yet complete: *s* and *l* are what the
+mathematicians call variables: they may have any actual value and there
+will always be a definite value of *p.v.*, *i.e.* of the actual fate
+which is being considered; to every value of *s* and *l*, which as
+we know are independent of each other, there corresponds a definite
+value of the actual prospectivity. Now, of course, there is also a
+certain factor at work in every actual case of experimental or normal
+development, which is *not* a variable, but which is the same in all
+cases. This factor is a something embraced in the prospective potency
+of our system, though not properly identical with it.
+
+The prospective potency of our system, that is to say of each of its
+elements, is the sum total of what can be done by all; but the fact
+that a typically proportionate development occurs in every possible
+case, proves that this sum comes into account, not merely as a sum,
+but as a sort of order: we may call this order the “relation of
+localities in the absolutely normal case.” If we keep in mind that the
+term “prospective potency” is always to contain this order, or, as we
+may also call it, this “relative proportionality,” which, indeed, was
+the reason for calling our systems “harmonious,” then we may apply it
+without further explanation in order to signify the *non-variable*
+factor on which the prospective value of any element of our systems
+depends, and, if we denote the prospective potency, embracing order,
+by the letter *E*, we are now able to complete our formula by saying
+*p.v. (X) = f(s, l, E)*. So far the merely analytical study of the
+differentiation of harmonious-equipotential systems.[59]
+
+[59] A far more thorough analysis of this differentiation has been
+attempted in my paper, “Die Localisation morphogenetischer Vorgänge. Ein
+Beweis vitalistischen Geschehens,” Leipzig, 1899.
+
+
+*Instances of “Harmonious-Equipotential Systems”*
+
+We must try at first to learn a few more positive facts about our
+systems, in order that we may know how important is the part which they
+play in the whole animal kingdom, and in order that our rather abstract
+analysis may become a little more familiar to us. We know already that
+many of the elementary morphogenetic organs have been really proved to
+be harmonious-equipotential systems, and that the same probably is true
+of many others; we also know that the immature egg of almost all animals
+belongs to this type, even if a fixed determination of its parts may
+be established just after maturation. Moreover, we said, when speaking
+about some new discoveries on form-restitution, that there are many
+cases in which the processes of restitution do not proceed from single
+localities, the seat of complex potencies in the organism, but in which
+each *single* part of the truncated organism left by the operation has
+to perform one *single* act of restoration, the full restitution being
+the result of the totality of all. These cases must now be submitted to
+a full analysis.
+
+All of you have seen common sea-anemones or sea-roses, and many of you
+will also be familiar with the so-called hydroid polyps. *Tubularia*
+is one genus of them: it looks like a sea-anemone in miniature placed
+on the top of a stem like a flower. It was known already to Allman
+that *Tubularia* is able to restore its flower-like head when that
+is lost, but this process was taken to be an ordinary regeneration,
+until an American zoologist, Miss Bickford, succeeded in showing that
+there was no regeneration process at all, in the proper sense of the
+word, no budding of the missing part from the wound, but that the new
+tubularian head was restored by the combined work of many parts of the
+stem. Further analysis then taught us that *Tubularia* indeed is to be
+regarded as the perfect type of an harmonious-equipotential system: you
+may cut the stem at whatever level you like: a certain length of the
+stem will always restore the new head by the co-operation of its parts.
+As the point of section is of course absolutely at our choice, it is
+clear, without any further discussion, that the prospective value of
+each part of the restoring stem is a “function of its position,” that
+it varies with its distance from the end of the stem; and so at once
+we discover one of the chief characteristics of our systems. But also
+the second point which enters into our formula can be demonstrated in
+*Tubularia*: the dependence of the fate of every element on the actual
+size of the system. You would not be able to demonstrate this on very
+long stems, but if you cut out of a *Tubularia* stem pieces which are
+less than ten millimetres in length, you will find the absolute size
+of the head restored to be in close relation to the length of the stem
+piece, and this dependence, of course, includes the second sort of
+dependence expressed in our formula.
+
+The figures will serve to show you a little more concretely what has
+been described. The head of *Tubularia* consists of a sort of broad base
+with a thin proboscis upon it, both bearing a large number of tentacles;
+these tentacles are the first things to be seen as primordia (“Anlagen”)
+in the process of restitution. You notice two rings of longitudinal
+lines inside the stem; the lines will become walls and then will
+separate from the stem until they are only connected with it at their
+basal ends; the new tentacles are ready as soon as that has happened,
+and a process of growth at the end will serve to drive the new head out
+of the so-called perisarc or horny skeleton, which surrounds the stem.
+By comparing the two figures, 12 *e*, and *g*, you easily find out that
+the absolute lengths of the two tentacle rings are very different, and
+that both are in proportion[60] to the actual size of the stem (Fig. 12).
+
+[60] This statement is *not strictly* correct for *Tubularia*. I found
+(*Archiv f. Entwickelungsmechanik*, ix. 1899), that a reduction of the
+length of the stem is always followed by a reduction of the size of the
+hydranth-primordium, but there is no real proportionality between them.
+It is only for theoretical simplification that a strict proportionality
+is assumed here, both in the text and the diagram. But there is an
+almost strict proportionality in all cases of “closed forms.”
+
+[Illustration: Fig. 12.--Tubularia.
+
+*a.* Diagram of the “Hydranth,” with its short and long tentacles.
+
+*b.* Restitution of a new hydranth inside the perisarc (*p*).
+
+*c.* The same--later stage; the tentacles are complete; the whole
+hydranth will be driven out of the perisarc by a process of growth that
+occurs at the locality marked ⬆.
+
+*d.* A stem of *Tubularia* cut either at *a_1 b_1* or at *a_2 b_2*,
+or at *a_1 c*.
+
+*e.* Position of tentacles in the piece cut at *a_1 b_1*.
+
+*f.* Position of tentacles in the piece cut at *a_2 b_2*,
+which is equal in length to *a_1 b_1*.
+
+*g.* Position of tentacles in the piece cut at *a_1 c*,
+which is half as long as *a_1 b_1*.]
+
+So we find our formula *p.v. (X) = f(s, l, E)* very well
+illustrated in *Tubularia*. The formula indeed may help us to predict,
+in any case, where a certain part of the polyp’s organisation is
+to originate, at least if we know all that is included under our
+letter *E*, *i.e.* the normal proportion of our form. Of course such
+prediction would not have much practical importance in all our cases of
+morphogenesis, but nevertheless I should like to state here that it is
+possible; for many scientific authors of recent times have urged the
+opinion that prediction of, and domination over, what will happen, can
+be the only true aims of sciences at all. I myself judge these aims to
+be of second or third-rate importance only, but, if they may be reached
+by what our purely theoretical study teaches, so much the better.
+
+Another very typical case of a morphogenetic system of the harmonious
+type is supplied by the phenomena of restoration in the ascidian
+*Clavellina*. I cannot fully describe the organisation of this form
+(Fig. 13a), and it must suffice to say that it is very complicated,
+consisting of two very different chief parts, the branchial apparatus
+and the so-called intestinal sac; if these two parts of the body of
+*Clavellina* are separated one from the other, each may regenerate the
+other in the typical way, by budding processes from the wound. But, as
+to the branchial apparatus, there may happen something very different:
+it may lose almost all of its organisation and become a small white
+sphere, consisting only of epithelia corresponding to the germ-layers,
+and of mesenchyme between them, and then, after a certain period of
+rest, a new organisation will appear. Now this new organisation is
+not that of a branchial apparatus but represents a very small but
+complete ascidian (Fig. 13). Such a fact certainly seems to be very
+important, not to say very surprising; but still another phenomena may
+be demonstrated on the animal which seems to be even more important. You
+first isolate the branchial apparatus from the other part of the body,
+and then you cut it in two, in whatever direction you please. Provided
+they survive and do not die, as indeed many of them do, the pieces
+obtained by this operation will each lose their organisation, as did the
+whole branchial apparatus, and then will each acquire another one, and
+this new organisation is also that of a *complete* little *Clavellina*.
+So we see that not only is the branchial apparatus of our animal capable
+of being transformed into a whole animal by the co-operative work of
+all its parts, but even each part of it may be transformed into a small
+*whole*, and it is quite at our disposal how large this part shall be,
+and what sort of a fragment of the original branchial apparatus it shall
+represent.
+
+[Illustration: Fig. 13.--Clavellina.
+
+*a.* Diagram of the normal animal: *E* and *J* = openings; *K* =
+branchial apparatus; *D* = intestine; *M* = stomach; *H* = heart.
+
+*b.* The isolated branchial apparatus.
+
+*c-e.* Different stages of reduction of the branchial apparatus.
+
+*f.* The new *whole* little ascidian.]
+
+We could hardly imagine a better instance of an harmonious-equipotential
+system.
+
+I cannot give you a description of all the other types of our systems
+subservient to restitution, and I can only mention here that the common
+hydra and the flatworm *Planaria* are very fine examples of them. But
+to one special case of harmonious equipotentiality you must allow me to
+direct your further attention.
+
+It has been known for many years that the Protozoa are also capable of
+a restoration of their form and organisation after disturbances, if at
+least they contain a certain amount of their nuclear substance. This
+process of restoration used to be regarded as belonging to the common
+type of regeneration proper, until T. H. Morgan succeeded in showing
+that in the genus *Stentor* it follows just the very lines which we know
+already from our study of embryonic organs or from *Tubularia*; that
+an harmonious-equipotential system is at the basis of what goes on.
+Now, you know that all Protozoa are but one highly organised cell: we
+have therefore here an instance where the so-called “elements” of our
+harmonious-morphogenetic system are not cells, but something inside of
+cells; and this feature must appear to be of very great moment, for it
+first shows, as we have already pointed out on another occasion, that
+morphogenesis is not dependent on cell-division, and it states at the
+same time that our concept of the harmonious-equipotential system may
+cover a very great area--that, in fact, it is a scheme of a very wide
+extent.
+
+
+*The Problem of the Factor* E
+
+We turn back again to considerations of a more abstract form. We left
+our analysis of the differentiation of the harmonious-equipotential
+systems, and particularly of the phenomena of localisation during this
+differentiation, at the point where we had succeeded in obtaining an
+equation as the expression of all those factors on which the prospective
+value, the actual fate, of any element of our systems depends, *p.v. (X)
+= f(s, l, E)* was the short expression of all the relations involved;
+*s* and *l*, the absolute size of the system and the relative position
+of the element with respect to some fixed points, were independent
+variables; *E* was a constant, namely, the prospective potency, with
+special regard to the proportions embraced by it.
+
+We shall now study the significance of the factor *E*.
+
+What does this *E* mean? Is it a short expression merely for an actual
+sum of elemental agents having a common resultant? And, if so, of what
+kind are these agents? Or what may *E* mean, if it can be shown *not* to
+be a short sign for a mere sum?
+
+
+*No Explanation Offered by “Means” or “Formative Stimuli”*
+
+For practical purposes it seems better if we modify the statement of our
+question. Let us put it thus: *E* is one of the factors responsible,
+among variables, for the localisation of organic differentiation;
+what then do we actually know about the causal factors which play a
+localising part in organogenesis? We, of course, have to look back to
+our well-studied “formative stimuli.” These stimuli, be they “external”
+or “internal,” come from without with respect to the elementary organ
+in which any sort of differentiation, and therefore of localisation,
+occurs: but in our harmonious systems no localising stimulus comes from
+without, as was the case, for instance, in the formation of the lens of
+the eye in response to the optical vesicle touching the skin. We know
+absolutely that it is so, not to speak of the self-evident fact that the
+general “means” of organogenesis have no localising value at all.[61]
+
+[61] One might object here that in a piece of a *Tubularia* stem, for
+instance, the tissues are in direct contact with the sea-water at
+the two points of the wounds only, and that at these very points a
+stimulus might be set up--say by a process of diffusion--which gradually
+decreases in intensity on its way inward. And a similar argument might
+apply to the small but whole blastula of Echinus, and to all other
+cases. But, in the first place, stimuli which only differ in intensity
+could hardly call forth the typical and typically localised single
+features realised in differentiation. On the other hand--and this will
+overthrow such an hypothesis completely--the dependence of the single
+localised effects in every case on the *absolute size* of the fragment
+or piece chosen for restoration renders quite impossible the assumption
+that all the singularities in the differentiation of the harmonious
+systems might be called forth by single stimuli originating in two
+fixed places in an *independent* way. These would never result in any
+“harmonious,” any proportionate structure, but a structure of the
+“normal” proportionality *and size* at its two ends and non-existent in
+the middle!
+
+So we see there is nothing to be done, either with the means or with the
+formative stimuli; both are entirely unable to account for those kinds
+of localisation during differentiation which appear in our harmonious
+systems.
+
+But is there no possibility of explaining the phenomena of organogenetic
+localisation by any other sort of interaction of parts? Two such
+possibilities may at the first glance seem to exist.
+
+
+*No Explanation Offered by a Chemical Theory of Morphogenesis*
+
+Though never set forth, in the form of a properly worked-out theory,
+the view has sometimes been advocated by biologists, that a chemical
+compound of a very high degree of complication might be the very basis
+of both development and inheritance, and that such a chemical compound
+by its disintegration might direct morphogenesis.
+
+Let us first examine if such a view may hold for the most general
+features of organic morphogenesis. It seems to me that from the very
+beginning there exists one very serious objection to every chemical
+theory of form-building, in the mere fact of the possibility of the
+restoration of form starting from atypical localities. The mere fact,
+indeed, that there is such a thing as the regeneration of a leg of a
+newt--to say nothing about restitution of the harmonious type--simply
+contradicts,[62] it seems to me, the hypothesis, that chemical
+disintegration of one compound may govern the course of morphogenetic
+events: for whence comes the re-existence of the hypothetical compound,
+newly to be disintegrated, after disintegration *has* been completed
+once already? And we even know that regeneration may go on several times
+running from the same locality!
+
+[62] See my article in *Biolog. Centralblatt*, 27, 1907, p. 69. The
+question is rendered still more complicated by the fact that in the case
+of the regeneration, say, of a leg it is not the original “morphogenetic
+compound” which is again required for disintegration, after it has
+become disintegrated once already, but only a specific part of it: just
+that part of it which is necessary for producing the leg! On the other
+hand, it would be impossible to understand, on the basis of physical
+chemistry, how the isolated branchial apparatus of *Clavellina* could
+be transformed, by chemical processes exclusively, into a system of
+which only a certain *part* consists of that substance of which the
+starting-point had been composed in its *completeness*.
+
+But, if we intentionally disregard this difficulty, in spite of
+its fundamental character, how could the hypothesis of chemical
+disintegration give the reason for the differentiation of our
+harmonious-equipotential systems, with special regard to the
+localisation of it; how could it account, in other words, for the
+appearance of typically localised specifications in an organ for which
+no external localising causes can be predicated?
+
+Let us remember that a few original intimate differences exist in our
+harmonious systems: the main directions of the intimate protoplasmic
+structure including polarity and bilaterality. There are therefore
+three times two specified poles in each of these systems, at least in
+bilateral organisms, but no other differences are present in them.
+A few very simple cases of harmonious differentiation might indeed
+be understood on the theory of a disintegrating chemical compound
+in connection with these few differences. Imagine that the original
+compound, of the quantity *a*, is disintegrated to the amount of
+*a*_1; from *a*_1 are formed the two more simple compounds, *b*
+and *c*, both of them in definite quantities; then we have the three
+chemical individuals, *a-a*_1, *b* and *c*, as the constituents of
+our harmonious system; and it now might be assumed, without any serious
+difficulty, though with the introduction of some new hypotheses, that
+the two poles of one of the fundamental axes of symmetry attract *b* and
+*c* respectively, *a-a*_1 remaining unattracted between them. We thus
+should have the three elementary constituents of the system separated
+into three parts, and as they all three are of a definite quantity,
+their separation would mean that the system had been divided into three
+parts, *a-a*_1, *b* and *c*, also with regard to its proper form.
+It is clear, that by taking away any part of the original system, by
+means of operations, there would be taken away a certain amount of the
+original compound; say that *a/n* is left; then, of course, the three
+constituents after the partial disintegration would be *a-a_1/n*,
+*b/n* and *c/n*, and so it follows that the proportionality of
+localisation would really be preserved in any case.
+
+But these considerations, evident as they seem to be in the most
+simple case, fail to satisfy in a really general sense: for two
+different reasons. First, they could never account for the fact that
+the differentiated organism by no means consists of so many different
+compounds as it shows single parts of its differentiation, but that,
+on the contrary, it only consists, as we know, of a certain rather
+limited number of true different morphogenetic elements, these
+elements occurring again and again--as for instance, nervous or
+muscular elements--but typical each time in locality, quantity, and
+form. And in the second place, the very *form* of elementary organs,
+their form as such, does not at all go hand-in-hand with chemical
+differences; this feature alone would absolutely overthrow any sort
+of a chemical morphogenetic theory to account for the problem of
+localisation. Take the typically arranged ring of the mesenchyme
+cells in our Echinus-gastrula, with its two spherical triangles, so
+typically localised; look at any sort of skeleton, in Radiolaria, or in
+starfishes, or in vertebrates: here you have form, real form, but form
+consisting of only one material. Not only is the arrangement of the
+elements of form typical here, *e.g.* the arrangement of the single
+parts of the skeleton of the hand or foot, but also the special form
+of each element is typical, *e.g.* the form of each single bone of the
+foot; and, on a purely chemical theory of morphogenesis the sufficient
+reason for the production of typical form in such a sense would be
+wanting. For atoms or molecules by themselves can only account for form
+which is arranged, so to speak, according to spatial geometry--as in
+fact they do in crystallography; but they can never account for form
+such as the skeleton of the nose, or hand, or foot. You will answer
+me perhaps, that there may be non-chemical agents in the germ,[63]
+responsible for typical form-localisation, but by such reasoning you
+would be departing from a purely chemical theory. Our next paragraph
+will be devoted to this side of the question.
+
+[63] Besides the specified poles determined by the polar-bilateral
+structure of the protoplasm.
+
+That is the principal reason for rejecting all sorts of chemical
+morphogenetic theories put forward to explain the problem of
+localisation; it is more explicit, and therefore, I suppose, still
+more convincing than the more general consideration that the very
+fact of restitutions in itself must contradict the hypothesis that
+a disintegration of compounds might be the directive agency in
+morphogenesis. To sum up: Specificity of organic form does not go
+hand-in-hand with specificity of chemical composition, and therefore
+cannot depend on it; and besides that, specific organic form is such
+that it can never be explained by atomic or molecular arrangement in
+the chemical sense; for, to state it in a short but expressive manner,
+the “form” of an atom or molecule can never be that of a lion or a
+monkey. To assume that would be to go beyond the limits of chemistry in
+chemistry itself.
+
+
+*No Machine Possible Inside the Harmonious Systems*
+
+And now we turn to the last possibility which is left to us in our
+endeavour to “understand” the localisation of the differentiation in our
+harmonious-equipotential systems by the means of physics and chemistry.
+Outside causes have failed to account for it, chemical disintegration
+of a compound has failed too. But could there not exist some sort of
+complicated interactions amongst the parts of the harmonious system
+themselves? Could there not exist some kind of a real machine in the
+system, which, if once set going, would result in the differentiations
+that are to take place? Then we might say that the “prospective
+potency” of the system is in fact that machine; we should know what the
+letter *E* of our equation stood for: viz., a resultant action of many
+complicated elemental interactions, and nothing more.
+
+Weismann, we know already, had assumed that a sort of machine was the
+prime mover of morphogenesis. We have seen that his theory cannot be
+true; the results of experiments most strongly contradict it. But, of
+course, the experiments only showed us that *such* a machine as *he*
+had imagined to exist could not be there, that development could not be
+governed by the disintegration of a given complicated structure into its
+simplest parts. But might not some other machine be imaginable?
+
+We shall understand the word “machine” in a most general sense. A
+machine is a typical configuration of physical and of chemical
+constituents, by the acting of which a typical effect is attained.
+We, in fact, lay much stress upon embracing in our definition of a
+machine the existence of chemical constituents also; we therefore
+understand by the word “machine” a configuration of a much higher
+degree of complication than for instance a steam-engine is. Of course
+a machine, whose acting is to be typical with regard to the three
+dimensions in space, has to be typically constructed with regard to
+these three dimensions itself; a machine that was an arrangement of
+elements in a strict plane could never have typical effects at right
+angles to that plane. This is a point which must well be kept in mind
+in all hypothetical considerations about machines that claim to explain
+morphogenesis.
+
+It must be granted that a machine, as we understand the word, might very
+well be the motive force of organogenesis in general, if only normal,
+that is to say, if only undisturbed development existed, and if a taking
+away of parts of our systems led to fragmental development.
+
+But we know that, at least in our harmonious-equipotential systems,
+quite another process occurs after parts have been taken away: the
+development that occurs is not fragmental but whole, only on a smaller
+scale.
+
+And we know, further, that this truly whole development sets in
+irrespective of the amount and direction of the separation. Let us first
+consider the second of these points. There may be a whole development
+out of each portion of the system--above certain limits--which is, say,
+of the volume *V*. Good! Then there ought to exist a machine, like
+that which exists in the whole undisturbed system, in this portion *V*
+also, only of smaller dimensions; but it also ought to exist in the
+portion *V*_1 which is equal to *V* in amount, and also in *V*_2, in
+*V*_3, *V*_4 and so on. Indeed, there do exist almost indefinitely
+many *V*_n all of which can perform the whole morphogenesis, and all
+of which therefore ought to possess the machine. But these different
+portions *V*_n are only partly different from each other in spatial
+relation. Many parts of *V*_2 are also parts of *V*_1 and of *V*_3
+and of *V*_4 and so on; that is to say, the different volumes *V*_n
+overlap each other successively and in such a manner that each following
+one exceeds the preceding one in the line by a very small amount only.
+But what then about our machines? Every volume which may perform
+morphogenesis completely must possess the machine in its totality. As
+now every element of one volume may play any possible elemental rôle in
+every other, it follows that each part of the whole harmonious system
+possesses any possible elemental part of the machine equally well, all
+parts of the system at the same time being constituents of different
+machines.
+
+A very strange sort of machine indeed, which is the same in all its
+parts (Fig. 14)!
+
+[Illustration: Fig. 14.--An “Harmonious-equipotential System” of
+whatever kind.
+
+According to the “machine-theory” of life this system ought to possess
+a certain unknown very complicated machine *in its completeness*:
+
+      (*a*) in its total length,
+  and (*b*) in each of the equal volumes *v*, *v*_1, *v*_2, *v*_3 and
+    so on,
+  and (*c*) in each of the unequal volumes *w*, *x*, *y*, and so on,
+  and (*d*) in every imaginable volume, no matter of what size.
+
+Therefore the “machine-theory” of life is absurd.]
+
+But we have forgotten, I see, that in our operation the absolute amount
+of substance taken away from the system was also left to our choice.
+From this feature it follows that not only all the different *V*_n,
+all of the same size, must possess the hypothetic machine in its
+completeness, but that all amounts of the values *V*_n-*n*, *n* being
+variable, must possess the totality of the machine also: and all values
+*V*_n-*n*, with their variable *n*, may again overlap each other.
+
+Here we are led to real absurdities!
+
+But what is the conclusion of our rather wild considerations?
+
+It seems to me that there is only one conclusion possible. If we
+are going to explain what happens in our harmonious-equipotential
+systems by the aid of causality based upon the constellation of single
+physical or chemical factors and events, there *must* be some such
+thing as a machine. Now the assumption of the existence of a machine
+proves to be absolutely absurd in the light of the experimental facts.
+*Therefore there can be neither any sort of a machine nor any sort of
+causality based upon constellation underlying the differentiation of
+harmonious-equipotential systems.*
+
+For a machine, typical with regard to the three chief dimensions
+of space, cannot remain itself if you remove parts of it or if you
+rearrange[64] its parts at will.
+
+[64] The pressure experiments and the dislocation experiments come into
+account here; for the sake of simplicity they have not been alluded to
+in the main line of our argument.
+
+Here we see that our long and careful study of morphogenesis has been
+worth while: it has afforded us a result of the very first importance.
+
+
+*The Autonomy of Morphogenesis Proved*
+
+No kind of causality based upon the constellations of single physical
+and chemical acts can account for organic individual development; this
+development is not to be explained by any hypothesis about configuration
+of physical and chemical agents. Therefore there must be something
+else which is to be regarded as the sufficient reason of individual
+form-production. We now have got the answer to our question, what
+our constant *E* consists in. It is not the resulting action of a
+constellation. It is not only a short expression for a more complicated
+state of affairs, it expresses *a true element of nature*. Life, at
+least morphogenesis, is not a specialised arrangement of inorganic
+events; biology, therefore, is not applied physics and chemistry: life
+is something apart, and biology is an independent science.
+
+All our results at present, indeed, are negative in their form; our
+evidence was throughout what is called *per exclusionem*, or indirect
+or apagogic. There were excluded from a certain number of possibilities
+all except one; a disjunctive proposition was stated in the form: *E*
+is either this, or that, or the other, and it was shown that it could
+not be any of all these except one, therefore it was proved to be that
+one. Indeed, I do not see how natural science could argue otherwise;
+no science dealing with inorganic phenomena does; something new and
+elemental must always be introduced whenever what is known of other
+elemental facts is proved to be unable to explain the facts in a new
+field of investigation.
+
+We shall not hesitate to call by its proper name what we believe we have
+proved about morphogenetic phenomena. What we have proved to be true
+has always been called *vitalism*, and so it may be called in our days
+again. But if you think a new and less ambitious term to be better for
+it, let us style it the doctrine of the *autonomy of life*, as proved
+at least in the field of morphogenesis. I know very well that the word
+“autonomy” usually means the faculty of *giving* laws to oneself, and
+that in this sense it is applied with regard to a community of men;
+but in our phrase autonomy is to signify the *being subjected* to laws
+peculiar to the phenomena in question. This meaning is etymologically
+defensible, and besides that I perhaps may remind you of a certain
+chapter of Professor Ward’s Gifford Lectures, in which he holds the view
+that, psychologically and epistemologically, there is more than a mere
+verbal relation between the civil and the natural “law.”
+
+Vitalism then, or the autonomy of life, has been proved by us
+indirectly, and cannot be proved otherwise so long as we follow the
+lines of ordinary scientific reasoning. There can indeed be a sort of
+direct proof of vitalism, but now is not the time to develop this proof,
+for it is not of the purely scientific character, not so naïve as our
+present arguments are, if you choose to say so. An important part of our
+lectures next summer will be devoted to this direct proof.
+
+
+“*Entelechy*”
+
+But shall we not give a name to our vitalistic or autonomous factor
+*E*, concerned in morphogenesis? Indeed we will, and it was not without
+design that we chose the letter *E* to represent it provisionally. The
+great father of systematic philosophy, Aristotle, as many of you will
+know, is also to be regarded as the founder of theoretical biology.
+Moreover, he is the first vitalist in history, for his theoretical
+biology is throughout vitalism; and a very conscious vitalism indeed,
+for it grew up in permanent opposition to the dogmatic mechanism
+maintained by the school of Democritus.
+
+Let us then borrow our terminology from Aristotle, and let that factor
+in life phenomena which we have shown to be a factor of true autonomy be
+called *Entelechy*, though without identifying our doctrine with what
+Aristotle meant by the word έντελέχεια. We shall use this word only as a
+sign of our admiration for his great genius; his word is to be a mould
+which we have filled and shall fill with new contents. The etymology of
+the word ἐντελέχεια allows us such liberties, for indeed we have shown
+that there is at work a something in life phenomena “which bears the end
+in itself,” ὃ ἔχει ἐν ἑαυτᾣ τὸ τέλος.
+
+Our concept of entelechy marks the end of our analysis of individual
+morphogenesis. Morphogenesis, we have learned, is “epigenesis” not only
+in the descriptive but also in the theoretical sense: manifoldness
+in space is produced where no manifoldness was, real “evolutio” is
+limited to rather insignificant topics. But was there nothing “manifold”
+previous to morphogenesis? Nothing certainly of an *extensive*
+character, but there was something else: there was entelechy, and thus
+we may provisionally call entelechy an “*intensive manifoldness*.”
+That then is our result: not evolutio, but epigenesis--“epigenesis
+vitalistica.”
+
+
+*Some General Remarks on Vitalism*
+
+We now shall leave entelechy where it stands: next summer we shall turn
+back to it and shall make its full logical and ontological analysis
+our chief study. At present we are satisfied with having proved its
+existence in nature, with having laid some of the foundations of a
+doctrine to be based upon it. I hope that these foundations will evince
+themselves strong: that is all-important.[65] It indeed has been the
+fault of all vitalism in the past that it rested on weak foundations.
+Therefore the discussion of the basis underlying our doctrine of the
+autonomy of life is to occupy us still a considerable time. We shall
+devote to it two more of this year’s lectures and three of the next; we
+shall examine all sorts of phenomena of life in order to find out if
+there are any further proofs of vitalism, independent perhaps, of what
+we way call our *first proof*, which is based upon the analysis of the
+*differentiation of harmonious-equipotential systems*. We shall find
+some more independent proofs; and besides that we shall find many kinds
+of phenomena upon which future times perhaps may erect more of such
+independent proofs.
+
+[65] My “first proof of vitalism” was first developed in the paper, “Die
+Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional
+remarks in *Organische Regulationem*, Leipzig, 1901, and in *Archiv
+für Entwickelungsmechanik*, 14, 1902.) I cannot admit that any really
+serious objection has been brought forward against it. (See my articles
+in *Biologisches Centralblatt*, 22, 23, 27, and in *Ergebnisse d. Anat.
+u. Entwickelungsgesch*. 11, 14.) An historical sketch of vitalism will
+be found in my book, *Der Vitalismus als Geschichte und als Lehre*,
+Leipzig, 1905.
+
+For we shall be chary of bestowing the name “proof” except on what is a
+proof indeed, of course according to our critical conviction. Vitalistic
+views in biology have arisen in rather numerous forms during the last
+fifteen years, especially in Germany--though in very strong contrast to
+the so-called official German biology--but I can only admit that one of
+all the arguments of “neo-vitalism” has proved its statements. I refer
+to the theory of “morphaesthesia” as developed by Noll, which we shall
+study briefly in the next lecture. I cannot concede that Reinke or
+Schneider or Pauly have really proved what they believe, and I cannot
+even allow to the most original thinker in this field, Gustav Wolff,
+that he has given a real demonstration of his views. He states that the
+existence of so-called “primary purposefulness,” that is, the existence
+of adaptive processes, which cannot be imagined to have arisen on
+Darwinian principles, is able to prove vitalism; but I say that it only
+proves teleology, which is a broader concept than vitalism.
+
+The possibility of a machine at the root of the phenomena in question
+always has to be excluded in order that vitalism may be proved, and I
+cannot grant that the necessity of such an exclusion has been actually
+shown by any of my fellow-combatants against so-called mechanism, except
+Noll.[66]
+
+[66] We are dealing here with morphogenesis and so-called vegetative
+physiology only; to certain psychologists, who have refuted the theory
+of psycho-physical parallelism, I must grant that they also have proved
+vitalism. (See Volume II.)
+
+
+*The Logic of our First Proof of Vitalism*
+
+Let us devote the end of our present lecture to an account of the
+logical means by which it has been possible to develop what we hope will
+be regarded as a true *proof* of life autonomy.
+
+Firstly, we have looked upon the phenomena of morphogenesis without
+any prepossessions; we may say that we have fully surrendered ourselves
+to them; we have not attacked them with any sort of dogmatism except
+the inherent dogmatism of all reasoning. But this dogmatism, if it may
+be called so, does not postulate that the results of the inorganic
+doctrines must hold for the organic world, but only that both the
+inorganic and the organic must be subject to certain most general
+principles.
+
+By studying life as a given phenomenon, by fully devoting ourselves to
+our problem, we not only have analysed into its last elements what was
+given to us as our subject, but we also, more actively, have created new
+combinations out of those elements: and it was from the discussion of
+these positive constructions that our argument for vitalism was derived.
+
+We have analysed morphogenesis into elementary processes, means,
+potency, formative stimulus, just as the physicist analyses mechanics
+into time, velocity, mass, and force; we have then rearranged
+our elements into “systems”--the equipotential systems, the
+harmonious-equipotential system in particular, just as the physicist
+composes his elements into the concepts of momentum or of kinetic energy
+or of work. And finally, we have discussed our compositions and have
+obtained our result, just as the physicist gets his ultimate results by
+discussing work and kinetic energy and momentum.
+
+Of course the comparison is by no means intended to show that mechanics
+and biology are sciences of the same kind. In my opinion, they are not
+so at all; but nevertheless there do exist similarities of a logical
+kind between them.
+
+And it is not the formal, logical character alone which allows us to
+compare biology with other natural sciences: there is still something
+more, there is one kind of assumption or postulate, or whatever you
+may choose to call it, without which all science whatever would be
+altogether *impossible*. I refer to the concept of *universality*. All
+concepts about nature which are gained by positive construction out of
+elements resulting from analysis, claim to be of *universal validity*;
+without that claim there could indeed be no science.
+
+Of course this is no place for a lecture on methodology, and it
+therefore must suffice to make one remark with special regard to
+our purpose, which we should like to emphasise. Our concept of the
+harmonious-equipotential system--say rather, our concept of the
+prospective potency itself--presumes the understanding that indeed *all*
+blastomeres and *all* stems of *Tubularia*, including those upon which
+we have *not* carried out our experiments, will behave like those we
+have experimented with; and those concepts also presume that a certain
+germ of Echinus, *A*, the blastomeres of which were not separated,
+would have given two whole larvae, if separation had taken place, while
+another germ, *B*, which actually gave us two larvae after separation,
+would only have given one without it. Without this presumption the
+concept of “potency” is meaningless, and, indeed, every assumption of a
+“faculty” or a “possibility” would be meaningless in the whole area of
+science.
+
+But this presumption can never be proved; it can only be postulated. It
+therefore is only with this postulate that our first proof of vitalism
+holds; but this restriction applies to *every* law of nature.
+
+I cannot force you to agree with this postulate: but if you decline
+you are practically saying that there exists a sort of pre-established
+harmony between the scientific object and the scientist, the scientist
+always getting into his hands such objects only as have been
+predestinated from the very beginning to develop two larvae instead of
+one, and so on.
+
+Of course, if that is so, no proof of natural laws is possible at all;
+but nature under such views would seem to be really dæmonic.
+
+And so, I hope, you will grant me the postulate of the universality
+of scientific concepts--the only “hypothesis” which we need for our
+argument.
+
+
+4. ON CERTAIN OTHER FEATURES OF MORPHOGENESIS ADVOCATING ITS AUTONOMY
+
+Our next studies on the physiology of form will be devoted in the first
+place to some additional remarks about our harmonious-equipotential
+systems themselves, and about some other kinds of morphogenetic
+“systems” which show a certain sort of relationship with them. For it is
+of the greatest importance that we should become as familiar as possible
+with all those facts in the physiology of form upon the analysis of
+which are to be based almost all of the future theories that we shall
+have to develop in biology proper and philosophical. Our discussions, so
+far as they relate to questions of actual fact, will contain only one
+other topic of the same importance.
+
+But though it is designed to complete and to deepen our analysis,
+the present considerations may yet be said to mark a point of rest
+in the whole of our discussions: we have followed one single line of
+argumentation from the beginning until now; this line or this stream of
+thought, as you might call it, is now to break into different branches
+for a while, as if it had entered from a rocky defile into a plain.
+It seems to me that such a short rest will be not unconducive to a
+right understanding of all we have made out; and such a full and real
+conceiving again, such a realising of our problems of morphogenesis and
+their solutions, will be the best preparation for the philosophical part
+of these lectures.
+
+
+HARMONIOUS-EQUIPOTENTIAL SYSTEMS FORMED BY WANDERING CELLS
+
+All of the harmonious-equipotential systems which we have studied so
+far were the bases of histological differentiation; that is to say, the
+processes of their differentiation consisted in specifically localised
+elements of theirs becoming different *in situ*. Now we know at least
+one type of systems which also may be called harmonious-equipotential,
+but the differentiation of which does not simply relate to elements at
+a fixed place. An additional phenomenon enters here into the sphere of
+the others. The elements not only become different where they are, but
+a specific changing of locality, a specific kind of wandering, goes
+hand-in-hand with differences relating to the prospective value to be
+attained. I am speaking of the formation of the larval skeleton of
+our well-known Echinus. We know that the mesenchyme cells, which have
+left the blastoderm and are arranged in a sort of ring of bilateral
+structure, are the starting-point of this skeleton: it indeed originates
+in a sort of secretive process on the part of the cells; the cells
+are moving about and are secreting carbonate of lime during their
+wandering. The experiments now have shown, as we know, that a whole,
+though smaller, skeleton may also be formed, if only a half or a quarter
+of the mesenchyme cells are present, as happens to be the case in all
+experiments with isolated blastomeres of the two or four-cell stage of
+cleavage. It is clear that in these cases the performance of each single
+cell must be different from what it is in the normal case, and that
+the same sort of differences in the morphogenetic performances appears
+again, if the two- and the four-cell stage are compared with each other.
+And there are still some other phenomena showing the possibility of
+different performances being carried out by the individual cells. Peter
+has shown that the number of mesenchyme cells may vary enormously under
+certain conditions; but, in spite of that, the skeleton always will
+be complete. It may be said that this line of research is only of a
+relative value to our own questions, as, of course, variability relates
+to different individuals: but it seems to me that it adds a very good
+supplementary instance to what the experiment on the individual itself
+has established.
+
+We should only be repeating ourselves if we were to analyse again what
+happens here as the expression of the harmonious-equipotentiality
+itself. But indeed there occurs something new in this instance: the
+single mesenchyme cell not only has to perform in each case that single
+act of specific secretion which the case requires, but it also has to
+wander to the right place in order to perform it; there must be some
+order, not only about the acts of secretion after wandering, but also in
+the migrations themselves. If undisturbed ontogeny alone were possible,
+and if therefore a theory like that of Weismann were in place, we might
+say perhaps that each mesenchyme-cell is specified not only as to its
+performance in secretion, but also with regard to its chemotactical
+irritability, the latter being typically localised, so that its effect
+becomes typical, thanks to the typical arrangement of all the cells
+with respect to each other. But that is certainly not the case. Now, you
+may ask yourselves if you could imagine any sort of a machine, which
+consists of many parts, but not even of an absolutely fixed number, all
+of which are equal in their faculties, but all of which in each single
+case, in spite of their potential equality, not only produce together
+a certain typical totality, but also arrange themselves typically in
+*order* to produce this totality. We *are* indeed familiar with certain
+occurrences in nature where such curious facts are observed, but I doubt
+if you would speak of “machines” in these cases. The mesenchyme-cells,
+in fact, behave just as a number of workmen would do who are to
+construct, say, a bridge. All of them *can* do every single act, all of
+them also *can* assume every single position: the result always is to
+be a perfect bridge; and it is to be a perfect bridge even if some of
+the workmen become sick or are killed by an accident. The “prospective
+values” of the single workman change in such a case.
+
+I well know that it is only an analogy which I am offering to you.
+The mesenchyme-cells have not “learned,” have no “experience.” All
+that is to occupy us next summer. But in spite of it, there is truth
+in the analogy; and perhaps you will prefer it to the merely abstract
+consideration.
+
+
+ON CERTAIN COMBINED TYPES OF MORPHOGENETIC SYSTEMS
+
+For the sake of completeness it may be remarked, only by the way, that
+the type of the proper harmonious-equipotential system may go hand in
+hand with another type of “systems” which play a part in morphogenesis;
+a type which we have shortly mentioned already and which will be studied
+fully a few chapters later. We know that there are equipotential systems
+with complex potencies: that is to say, systems which may produce a
+whole organism equally well from any one of their elements; we know the
+cambium of Phanerogams to be such a system. Now it is easily understood
+that the germ of our Echinus, say in the stage of two or four or eight
+cleavage cells, is not only an harmonious-equipotential system, but
+a complex-equipotential system too. Not only may there arise a whole
+organism out of 2/4 or 3/4 or 3/8, 4/8, 5/8, 6/8, 7/8 of its elements,
+in which cases the harmonious rôle of the single element with regard to
+its single performance in a totality is variable, but there may also
+arise four whole single larvae out of the four cells of the four-cell
+stage, or eight single whole larvae out of the eight-cell stage.[67]
+In these cases, of course, each of the four or eight elements has
+performed not a part of the totality, changing with its “position,” but
+the totality itself. With respect to these possible performances the
+“systems” present in the four or eight-cell stages of cleavage must be
+called complex-equipotential ones.
+
+[67] The eight larvae would be incomplete in some respect, but not with
+regard to symmetry. They would be “whole” ones, only showing certain
+defects in their organisation. See page 65 note 1, and page 73.
+
+We propose to give the name of *mixed-equipotential systems* to all
+those equipotential systems which, at the same time, may be regarded
+as belonging to the harmonious or to the complex type. It is not only
+among cleavage-stages that they are to be found; you may also find them
+very clearly exhibited in our ascidian *Clavellina* for instance. We
+know already that the branchial apparatus of this form is typically
+harmonious-equipotential, but it is complex-equipotential too, for it
+also may regenerate what is wanting in the proper way, by a budding
+from the wound; and the same is true of many other cases, the flatworm
+*Planaria* for instance.
+
+Another type of systems, which might be said to be of a higher degree,
+is exhibited in some very strange phenomena of regeneration. It was
+first shown most clearly by some experiments of Godlewski’s that a
+whole tail may be regenerated from a wound inflicted on the body of
+a newt, even if this wound involves section of only a portion of the
+body-diameter. Section of the whole of the body-diameter of course
+would cause the formation of the whole tail also; but it was found that
+even an incomplete cross-section of the body is capable of performing
+the whole on a smaller scale. The series of possible cross-sections
+which are all capable of regeneration would have to be called a
+system of the complex type in this case; but, now we learn that every
+*single* cross-section is of the harmonious type, we must speak of
+*complex-harmonious systems*. What we have described is not the only
+instance of our new type of morphogenetic systems. Some other instances
+had been discovered a few years earlier, though nobody had pointed
+out their true significance. In the flatworm *Planaria* a partial
+cross-section is also capable of forming a whole structure, say a head,
+and all cases of so-called “super-regeneration” after the infliction of
+a complicated wound probably belong here also.
+
+You may say that our two additions to the theory of systems are merely
+formal, and indeed I am prepared to concede that we shall not learn
+anything altogether new from their discussion: their analysis would lead
+either to what was our “first proof” of the autonomy of life-phenomena
+or to what will be our “second” one. But the mere descriptions of the
+facts discovered here will interest you, I think, and will fill your
+minds with more vivid pictures of the various aspects of form-autonomy.
+
+While dealing with our harmonious-equipotential systems as the
+starting-points of processes of restitution, *e.g.* in *Tubularia*,
+*Clavellina*, the flatworms, and other instances, we always have
+regarded cross-sections of the body as constituting the elements of
+equipotentiality. Now cross-sections, of course, are by no means simple
+in themselves, but are made up of very different tissues, which are
+derivates of all three of the original germ layers--ectoderm, mesoderm,
+and endoderm. Owing to this composite character of the cross-sections,
+taken as elements of harmonious systems, a special phenomenon of
+morphogenesis is presented to us, which teaches somewhat more than the
+mere concept of harmonious-equipotentiality can express. If composite
+elements concerned in morphogenesis result in one whole organisation
+in spite of the development of the single tissues of these elements
+going on independently, then there must be a sort of correspondence
+or reciprocity of the harmonious development among these tissue
+constituents themselves; otherwise a proportionate form could not be the
+final result. We may conveniently speak of a *reciprocity of harmony* as
+existing between the single tissues or germ layers which constitute many
+harmonious-equipotential systems, and there can be little doubt that we
+have here an important feature with regard to general morphogenesis.[68]
+
+[68] Reciprocal harmony may be reduced in some cases to the given
+proportions of one original harmonious system, from which the single
+constituents of the complicated system, showing reciprocal harmony, are
+derived. Then we have only an instance of “harmony of constellation”
+(see p. 109). But reciprocal harmony seems to become a problem itself,
+if it occurs in restitutions starting from quite a typical point,
+selected by the experimenter. It will be a problem of future research
+to give an exact formula of what happens here. Reciprocal harmony also
+occurs in regeneration proper. It is known that the formation of the
+regenerative bud and the differentiation of this bud follow each other.
+As the bud is composed of different elementary systems, it follows that
+these different systems, of which every single one is harmonious, also
+have to work in reciprocity to each other, in order that one whole
+proportionate formation may result.
+
+A few other groups of morphogenetic facts may find their proper place
+here, though they are not properly to be regarded as additions to the
+theory of harmonious systems but as forming a sort of appendix to it.
+
+
+THE “MORPHAESTHESIA” OF NOLL[69]
+
+[69] *Biol. Centralblatt.* 23, 1903.
+
+We may briefly mention that group of botanical phenomena, by which
+the botanist Noll has been led to the concept of what he calls
+“morphaesthesia,” or the “feeling” for form; a concept, the full
+discussion of which would lead to almost the same conclusions as our
+analysis of the harmonious systems has done. In the Siphoneae, a
+well-known order of marine algae with a very complicated organisation
+as to their exterior form, the protoplasm which contains the nuclei is
+in a constant state of circulation round the whole body, the latter
+not being divided by proper cell-walls. On account of this constant
+movement it is certainly impossible to refer morphogenetic localisation
+to definite performances of the nuclei. Nor can any sort of structure
+in the outer protoplasmic layer, which is fixed, be responsible for
+it, for there is no such structure there: hence there must be a sort
+of feeling on the part of the plant for its relative body localities,
+and on account of this feeling morphogenesis occurs. This “feeling” is
+styled “morphaesthesia” by Noll, and to it he tries to refer all sorts
+of different botanical form-phenomena,[70] for instance what is called
+“autotropism,” that is, the fact that branches of plants always try to
+reassume their proper angle with regard to their orientation on the main
+axis, if this orientation has been disturbed. It may be an open question
+if this particular application of the theory is right: certainly
+there seems to be much truth in the establishment of the concept of
+morphaesthesia, and we only have to object to its psychological name.
+But that may be done in a more general form on a later occasion.
+
+[70] Certain phenomena of the physiology of growth of *Geranium
+Robertianum*, recently discussed by Francé from a vitalistic point of
+view (*Zeitschr. Entw. lehre*. 1, 1907, Heft iv.), might also belong
+here. I cannot see an independent proof of vitalism in these facts if
+taken by themselves; a pre-existing “machine” cannot be absolutely
+excluded here.
+
+
+RESTITUTIONS OF THE SECOND ORDER
+
+In the hydroid polyp *Tubularia*, already familiar to us as being a most
+typical representative of the harmonious-equipotential systems, a very
+interesting phenomenon has been discovered[71], almost unparalleled at
+present but nevertheless of a general importance, a phenomenon that
+we may call a restitution of a restitution, or a restitution of the
+second order. You know that the first appearance of the new head of
+*Tubularia*, after an operation, consists in the formation of two rings
+of red lines, inside the stem, these rings being the primordia of the
+new tentacles. I removed the terminal ring by a second operation soon
+after it had arisen, disturbing in this way the process of restitution
+itself: and then the process of restitution itself became regulated. The
+organism indeed changed its course of morphogenesis, which was serving
+the purposes of a restitution, in order to attain its purpose in spite
+of the new disturbance which had occurred. For instance, it sometimes
+formed two rings out of the one that was left to it, or it behaved
+in a different way. As this difference of morphogenetic procedure is
+a problem by itself, to be discussed farther on, we shall postpone a
+fuller description of this case of a restitution of the second degree.
+
+[71] Driesch, *Arch. Entw. Mech.* 5, 1897.
+
+At present I do not see any way of proving independently the autonomy of
+life by a discussion of these phenomena; their analysis, I think, would
+again lead us to our problem of localisation and to nothing else; at
+least in such an exact form of reasoning as we demand.
+
+
+ON THE “EQUIFINALITY” OF RESTITUTIONS[72]
+
+[72] Driesch, *Arch. Entw. Mech.* 14, 1902.
+
+I have told you already that *Tubularia* in the phenomena of the
+regulation of restitutions offers us a second problem of a great general
+importance, the problem of the *Equifinality of Restitutions*. There
+indeed may occur restitutions, starting from one and the same initial
+state and leading to one and the same end, but using very different
+means, following very different ways in the different individuals of one
+and the same species, taken from the same locality, or even colony.
+
+Imagine that you have a piece of paper before you and wish to sketch
+a landscape. After drawing for some time you notice that you have
+miscalculated the scale with regard to the size of the paper, and
+that it will not be possible to bring upon the paper the whole of the
+landscape you want. What then can you do? You either may finish what you
+have begun to draw, and may afterwards carefully join a new piece of
+paper to the original one and use that for the rest of the drawing; or
+you may rub out all you have drawn and begin drawing to a new scale; or
+lastly, instead of continuing as you began, or erasing altogether, you
+may compromise as best you can by drawing here, and erasing there, and
+so you may complete the sketch by changing a little, according to your
+fancy, the proportions as they exist in nature.
+
+This is precisely analogous to the behaviour of our *Tubularia*.
+*Tubularia* also may behave in three different ways, if, as I described
+to you, the terminal one of its two newly arisen rings of tentacle
+primordia is removed again. It may complete what is left, say the basal
+tentacle ring, then put forth from the horny skeleton (the “perisarc”)
+the new head as far as it is ready, and finally complete this head
+by a regular process of budding regeneration. But it also may behave
+differently. It may “erase” by a process of retro-differentiation all
+that has been left of what had already been formed, and then may form
+*de novo* the totality of the primordia of a new head. Or, lastly, it
+may remove a part of the middle of the one ring of tentacle rudiments
+which was left, and may use this one ring for the formation of two,
+which, of course, will not be quite in the normal relations of place
+with regard to each other and to the whole, but will be regulated
+afterwards by processes of growth. Thus, indeed, there is a sort of
+equifinality of restitution: one starting-point, one end, but three
+different means and ways.
+
+It would, of course, contradict the principle of univocality, as we
+shall see more fully later on, to assume that there actually are
+different ways of regulation whilst all the conditions and stimuli are
+the same. We are obliged to assume, on the contrary, that this is not
+the case, that there are certain differences in the constellation, say
+of the general conditions of age or of metabolism, which are responsible
+for any given individual choosing one process of restitution instead
+of another; but even then the phenomenon of equifinality remains very
+striking.
+
+It has long been known that restitution in general does not always
+follow the same lines of morphogenesis as are taken by ontogeny, and it
+was this feature that once led Roux to point out that the adult forms
+of organisms seem to be more constant than their modes of origin. But,
+comparing ontogeny with restitution in general, we see that only the
+ends are the same, not the points of starting; the latter are normal or
+non-typical in ontogeny, atypical in restitution. In the new discoveries
+of an equifinality of restitutions we have the *same* starting-point,
+which is decidedly non-typical but atypical, *i.e.* dependent on our
+arbitrary choice, leading by *different* ways always to the *same* end.
+
+There may be many who will regard the fact of equifinality as a proof of
+vitalism. I should not like to argue in this easy way; I indeed prefer
+to include part of the phenomena of equifinality in our first proof of
+autonomy, and part in the second one, which is to follow.
+
+Another important phenomenon of the equifinality of regulation was
+discovered by Morgan. A species of the flatworm *Planaria* was found to
+restore its totality out of small pieces either by regeneration proper,
+if the pieces were fed, or by a sort of rearrangement of material,
+on the basis of its harmonious-equipotentiality, if they were kept
+fasting. It is important to note that here we see one of the conditions
+determining the choice of the way to restoration, as we also do in the
+well-known equifinal restitutions of the root in plants, where the
+behaviour of the organism depends on the distance of the operation-wound
+from the tip.[73] In *Tubularia* the actual stage of restitution that
+has been already reached by the stem when the second operation takes
+place, may account for the specification of its future organogenesis,
+but this is not at all clearly ascertained at present.
+
+[73] The root may be restored by regeneration proper, or by the
+production of adventitious roots, or by one of the side-roots changing
+its geotropism from horizontal to positive, according to the smaller or
+greater distance of the wound from the tip.
+
+*Clavellina* also shows equifinality in its restitution, as has already
+been shortly mentioned. The isolated branchial apparatus may restitute
+itself by retro-differentiation to an indifferent stage followed by
+renovation; or it may regenerate the intestine-sac in the proper way.
+Nothing is known here about the conditions, except perhaps that young
+individuals seem more apt to follow the first of these two ways, older
+ones the second; but there are exceptions to this rule.
+
+The discussion of other instances of equifinality, though important in
+themselves, would not disclose anything fundamentally new, and so we may
+close the subject with the remark that nothing can show better than the
+fact of the equifinality of restitutions how absolutely inadequate all
+our scientific conceptions are when confronted with the actual phenomena
+of life itself. By analysis we have found differences of potencies,
+according as they are simple or complex; by analysis we have found
+differences of “systems,” differences of means, and indeed we were glad
+to be able to formulate these differences as strictly as possible: but
+now we see how, in defiance of our discriminations, one and the same
+species of animals behaves now like one sort of our “systems,” and now
+like the other; how it uses now one sort of “potencies,” now another.
+
+But even if it is granted that, in the presence of such phenomena of
+life, our endeavour seems to be like a child’s play on the shores of the
+ocean, I do not see any other way for us to go, so long, at least, as
+our goal is human science--that is, a study of facts as demanded by our
+mental organisation.
+
+
+REMARKS ON “RETRO-DIFFERENTIATION”
+
+We shall finish this part of our studies by mentioning a little more
+explicitly one fundamental fact which has already entered incidentally
+into our considerations, viz. *retro-* or *back-differentiation*.[74]
+We know that it occurs in *Clavellina* and in *Tubularia*; we may add
+that it also happens in *Hydra*, and that in the flatworm *Planaria*
+the pharynx, if it is too large for a piece that is cut out, may be
+differentiated back and be replaced by a new pharynx, which is smaller.
+
+[74] “Retro”-differentiation, of course, is not “Re”-differentiation
+(“Umdifferenzierung,” see p. 111), though it may help it to occur.
+
+It is not death and sloughing of parts that occurs in these cases,[75]
+but a real process of active morphogenesis; not, however, a process
+consisting in the production of visible manifoldness, but the opposite.
+Loeb was the first to lay much stress upon this topic, and indeed, there
+may appear a very strange problem in its wake: the problem, whether
+*all* morphogenesis might be capable perhaps of going backwards under
+certain conditions.
+
+[75] Of course such a real decay of parts may happen in other cases.
+
+It is important to note that in most[76] cases retro-differentiation
+occurs in the service of restitution: it goes on wherever restitution
+requires it. This fact alone would show that not very much could be
+explained here by the discovery of modern chemistry, important as
+it is, that one and the same “ferment” or “enzyme” may affect both
+the composition and the decomposition of the same compound. We could
+regard what is called “catalysis” solely as an agent in the service of
+entelechy. But this point also will become clearer in another part of
+the work.
+
+[76] Certain cases of retro-differentiation occurring under conditions
+of strict fasting will be described in a later chapter.
+
+
+
+
+*C.* ADAPTATION
+
+INTRODUCTORY REMARKS ON REGULATIONS IN GENERAL
+
+
+We have finished our long account of individual morphogenesis proper.
+If we look back upon the way we have traversed, and upon those topics
+in particular which have yielded us the most important general results,
+the material for the higher analysis which is to follow, it must
+strike us, I think, that all these results relate to regulations.
+In fact, it is “secondary” form-regulations, according to our
+terminology, that we have been studying under the names of equifinality,
+back-differentiation, restitution of the second order, and so on, and
+our harmonious-equipotential systems have figured most largely in
+processes of secondary form-regulations also. But even where that has
+not been the case, as in the analysis of the potencies of the germ in
+development proper, form-regulations of the other type have been our
+subject, regulations of the primary or immanent kind, the connection
+of normal morphogenetic events being regulatory in itself. It was not
+the phenomenon of organic regulation as such that afforded us the
+possibility of establishing our proof of the autonomy of morphogenesis:
+that possibility was afforded us by the analysis of the distribution of
+potencies; but upon this distribution regulation is based, and thus
+we may be said to have studied some types of regulation more or less
+indirectly when analysing potencies.
+
+It therefore seems to me that we shall have hopes of a successful issue
+to our inquiries, if we now, on passing to what is called the physiology
+of the vegetative functions, proceed to focus our attention on the
+concept of regulation as such. And that is what we shall do: on our
+way through the whole field of physiology, we shall always stop at any
+occurrence that has any sort of regulatory aspect, and shall always ask
+ourselves what this feature has to teach us.
+
+But let us first try to give a proper definition of our concept. We
+shall understand by “regulation” any occurrence or group of occurrences
+on a living organism which takes place after any disturbance of
+its organisation or normal functional state, and which leads to a
+reappearance of this organisation or this state, or at least to a
+certain approach thereto. Organisation is disturbed by any actual
+removal of parts; the functional state may be altered by any change
+among the parts of the organism on the one hand, by any change of the
+conditions of the medium on the other; for physiological functioning
+is in permanent interaction with the medium. It is a consequence of
+what we have said that any removal of parts also changes the functional
+state of the organism, but nevertheless organisation is more than a mere
+sum of reactions in functional life. All regulations of disturbances
+of organisation may be called *restitutions*, while to regulations of
+functional disturbances we shall apply the name *adaptations*. It is
+with *adaptations* that we have to deal in the following.
+
+Let us begin our studies of adaptations in a field which may justly
+be called a connecting link between morphogenesis and physiology
+proper, not yet wholly separated from the science of the organic form,
+morphology.
+
+
+1. MORPHOLOGICAL ADAPTATION
+
+*Morphological adaptation* is a well-established fact, and I need only
+mention the striking differences between the land and water form of
+amphibious plants, or the differences between the same species of plants
+in the Alps and in the plains, or the very different aspect of the arms
+of an athlete and of an ascetic, to recall to your memory what is meant
+by this term.
+
+Morphological adaptation is no part of individual morphogenesis proper,
+but occurs at the end of it; at least it never occurs previous to the
+full individual life of an organism, previous to its true functional
+life; for it relates to the functions of the complete organism.
+
+
+THE LIMITS OF THE CONCEPT OF ADAPTATION
+
+It is especially, though by no means exclusively, among plants that
+morphological adaptation assumes its most marked forms; and this topic,
+indeed, may very easily be understood if we remember that plant-life
+is in the very closest permanent dependence on the medium, and that
+this medium is liable to many changes and variations of all kinds.
+In order to elucidate our problem, it therefore seems convenient to
+restrict our considerations for a while to the study of plants. There
+exist very many external formative stimuli in the morphogenesis of
+vegetation: would it then be possible to regard every effect of such
+an external formative stimulus as a real morphological adaptation?
+No; for that would not meet the point. The general *harmony* of form
+is indeed concerned if gravity forces roots to shoot forth below at a
+spot where they can enter the ground, or if light induces branches and
+leaves to originate at places where they can obtain it for assimilation;
+but gravity and light themselves are mere formative stimuli--of the
+localising type--in these instances, for they relate only to the
+individual production of form, not to the functioning of already
+existing form. We therefore are warned not to confuse the effects of
+formative stimuli from without with real adaptive effects until we have
+fully analysed the particular case.
+
+We have drawn a sharp line between causes and means of morphogenesis,
+applying the term “means” to those conditions of the morphogenetic
+process which relate neither to the specificity nor to the localisation
+of its constituents, though they are necessary for the accomplishment
+of the process in the most thorough manner. Would it be possible to
+connect our new concept of an adaptation with our well-established
+concept of a means of morphogenesis in such a way that we might speak
+of a morphological “adaptation” whenever any specific feature about
+morphogenesis proves to be immediately dependent for its success on some
+specific means, though it does not owe its localisation to that means
+as its “cause”? It seems to me that such a view would also fall wide
+of the mark. It is well known, for instance, that the flowers of many
+plants never fully develop in the dark; light is necessary for their
+morphogenesis. Is, therefore, their growth in the presence of light to
+be called a morphological “adaptation” to light? Certainly not: they
+simply *cannot* originate without light, because they require it for
+some reason. It is precisely here that our conception of light as a
+“means” of morphogenesis is most fully justified. There are many[77]
+such cases; and there are still others of an apparently different
+type, but proving the same. All pathological forms produced in plants
+by animal parasites or by parasitic fungi could hardly be called
+adaptations, but must be attributed to some abnormality of means or of
+stimuli. It may be that the organism reacts as well as possible in these
+cases, and that if it reacted otherwise it would die--we know absolutely
+nothing about this question. But even then there would only be some sort
+of regulation *in* the process of pathological morphogenesis, but *the
+process* itself could hardly be called adaptive.
+
+[77] Klebs has suppressed the reproductive phase of organisation
+altogether, in fungi as well as in flowering plants, or has made it
+occur abnormally early, merely by changing the “external conditions”
+and by altering the “internal” ones correspondingly. There is hardly
+anything like an adaptation in these cases, which, by the way, offer
+certain difficulties to analysis, as the boundaries between “cause” and
+“means” are not very sharp here.
+
+So far we have only learned what is not to be regarded as morphological
+adaptation. No response to external formative stimuli is in itself an
+example of adaptation, nor are processes dependent for their existence
+on any kind of condition or means to be called, simply because they are
+dependent on them, adaptations to those agents. What then, after all, is
+a morphological adaptation?
+
+Let us remember what the word adaptation is really to mean in our
+discussions: a state of functioning is adapted--a state of functioning
+must therefore have been disturbed; but as functioning itself, at least
+in plants, certainly stands in close relations to the medium, it follows
+that all adaptations are in the last resort connected with those factors
+of the medium which affect functioning. In being correctives to the
+disturbances of functioning they become correctives to the disturbing
+factors themselves.
+
+But again, the question seems to arise whether these factors of the
+medium, when they provoke an adaptation by some change that is followed
+by functional disturbance, do so in the capacity of “causes” or of
+“means,” and so it might seem that we have not gained very much so far
+by our analysis. The reproach, however, would not be quite justified,
+it seems to me: we indeed have gained a new sort of analytical concept,
+in the realm of causal concepts in general, by clearly stating the
+point that adaptations are related directly to functionality, and only
+indirectly, through functionality, to external changes. By the aid of
+this logical formulation we now are entitled to apply the term “cause,”
+in our restricted sense of the word, to every change of the medium
+which is followed by any sort of adaptation in regard *to itself*. Our
+definition stated that a “cause” is any one of the sum of necessary
+factors from without that accounts either for the localisation *or* for
+*the specification* of the effect, and the definition holds very well in
+this case. Indeed, the specification of the effect is determined *by*
+the outside factor in every case of an adaptation *to* it, by the mere
+*fact* of its being a specific adaptation to this specific factor.
+
+We must not forget that in this chapter we are not studying real
+individual morphogenesis as the realisation of what has been inherited,
+but that at present we regard morphogenesis proper as an accomplished
+fact. Morphogenesis proper has laid the general lines of organisation;
+and now adaptation during the functional life, so to speak, imposes a
+second kind of organisation upon the first. It is for that reason that
+the meaning of the word “cause” is now becoming a little different from
+what it was before.
+
+In order to study a little more in detail what has been discovered
+about morphological adaptation in animals and plants, let us separate
+our materials into two groups, one of them embracing adaptations with
+regard to functional changes from without, the other adaptations to
+those functional changes which come from the very nature of functioning.
+Almost all of our previous general considerations have applied to the
+former group, with which we shall now proceed to deal.
+
+
+ADAPTATIONS TO FUNCTIONAL CHANGES FROM WITHOUT[78]
+
+[78] Compare Herbst, *Biol. Centralbl.* 15, 1895; and Detto, *Die
+Theorie der direkten Anpassung*, Jena, 1904. A full account of the
+literature will be found in these papers.
+
+The differences between plants grown in very dry air, very moist air,
+and water, respectively, are most distinctly seen in all the tissues
+that assist in what is called transpiration, that is, the exchange of
+water-vapour between the plant and the medium, but especially in the
+epidermis and the conductive fibres, both of which are much stronger
+in plants grown in the dry. Indeed, it seems from experiments that
+transpiration is the most essential factor to which “adaptation” occurs
+in amphibious plants, though the changes of the mechanical conditions
+according to the medium also seem to have some sort of structural
+effect. If plants stand very deeply in water, the conditions of
+illumination, so important for assimilation in plants, may have been
+altered, and therefore much of the structural change can be attributed
+also to them. It is unimportant in our general question what is due to
+one of these factors and what to the other. That there is a real sort
+of adaptation cannot be doubtful; and the same is true, as experimental
+observations of the last few years have shown, with regard to the
+structural differences between so-called sun-leaves and shade-leaves
+of plants grown in the air: it has been actually shown here that the
+functional life of the former goes on better in the sun, of the latter
+better in the shade.
+
+It is very important to emphasise this point, as the adaptive character
+of all sorts of structural differences in plants dependent on light
+and on moisture has lately been denied, on the supposition that there
+is only a stopping of organogenesis in the case of the more simple,
+a continuance in the case of the more complicated modification, but
+nothing else. Indeed, all morphological adaptation has been conceived
+as only consisting in differences dependent upon the absence or the
+presence of necessary means or causes of development, and as offering
+no problem of its own. We have gained the right position from which
+to oppose this argument, it seems to me, in our formula that all
+adaptations do relate *not* directly *to* the agents of the medium,
+but to changes of functional states induced *by* those agents; that
+adaptations only *are* “adaptations” by being correctives to the
+functional state.
+
+There simply *is* an “adaptation” of structure in *such* a sense in all
+the cases we have mentioned. We can say neither more nor less. Granted
+that one of the outside factors which comes into account is merely a
+necessary “means”: then why is the histological consequence of the
+presence of the means an actual adaptation to it as far as its relation
+to functioning is concerned--why is the consequence of its absence also
+an adaptation to this absence in its relation to functioning? Why, to
+complete the series, is the degree of the consequence of its presence an
+adaptation to the degree of its presence?
+
+All these relationships, which are so many facts, have been absolutely
+overlooked by those who have been pleased to deny morphological
+adaptation to functional changes from without.
+
+To do full justice to them we may speak of “primary” regulative
+adaptations in all the cases mentioned above, applying the word
+“primary,” just as was done with regard to restitutions, to the fact
+that there is some sort of regulation *in* the normal connection of
+processes. We reserve the title of “secondary adaptations” for cases
+such as those described, for instance, by Vöchting,[79] where not
+merely one and the same tissue originates adaptively with regard to the
+degree of its normal functioning, but where a profound disturbance
+of all functioning connections, due to the removal of portions of the
+organisation, is followed by histological changes at absolutely abnormal
+localities; that is, where a real change of the *kind* of functioning
+is the consequence of the adaptation. It, of course, will be found very
+difficult to discriminate such phenomena from real restitutions, though
+logically there exists a very sharp line between them.
+
+[79] Vöchting (*Jahrb. wiss. Bot.* 34, 1899) forced the bulbs of
+plants to become parts of the stem, and parts of the stem to form
+bulbs; in both cases the most characteristic changes in histology
+could be observed, being in part adaptations, but in part restitutions
+of the proper type. (See also my *Organische Regulationen*, 1901, p.
+84.) A true and simple instance of a “secondary adaptation” seems to
+be furnished in a case described by Boirivant. In *Robinia* all the
+leaflets of a leaf-stalk were cut off: the leaf-stalk itself then
+changed its structure in order to assist assimilation, and also formed
+real stomata.
+
+A few more concrete instances may now close this account of adaptation
+to functional changes coming from without. Though almost all the
+adaptive characters in the aquatic forms of amphibious plants represent
+a less complicated state of organisation than the corresponding
+structures in their terrestrial forms, and therefore have wrongly
+been regarded as simply due to a stopping of morphogenesis for want
+of necessary means, yet there are a few of them that are positive
+complications in comparison with the land-forms: the so-called
+aërenchyme, especially well developed in the water-form of *Jussiaea*
+is such an instance. This tissue stands in the direct service of
+respiration, which is more difficult to be accomplished under water than
+ordinarily, and represents a true adaptation to the altered function.
+
+Among animals there is only one well-studied instance of our first type
+of adaptive morphological characters. *Salamandra atra*, the black
+salamander, a species which only inhabits regions at least two thousand
+feet above sea-level, does not bring forth its young until metamorphosis
+has taken place. The larvae, however, may be removed from the mother’s
+body at an earlier stage and forced to complete their development in
+water. Under these circumstances, as was shown in an excellent memoir
+by Kammerer,[80] they will change the whole histological type of their
+gills and skin in order to meet the new functional conditions. The
+change of the conditions of functioning is very severe here, for whereas
+the gills had served for nutrition and respiration in the uterus--by
+a process of endosmosis--they now serve for respiration only, and, of
+course, are surrounded by quite an abnormal chemical medium.
+
+[80] *Arch. Entw. Mech.* 17, 1904.
+
+
+TRUE FUNCTIONAL ADAPTATION[81]
+
+[81] Roux, *Gesammelte Abhandlungen*, vol. i. 1895; in particular, *Der
+Kampf der Teile im Organismus*, Leipzig, 1881.
+
+But all other cases of morphological adaptation among animals, and
+several in the vegetable kingdom too, belong to our second group of
+these phenomena, which in our analytical discussion we have called
+adaptations to functional changes that result from the very nature
+of functioning, and which we shall now call by their ordinary name,
+“functional adaptation.”
+
+It was Roux who first saw the importance of this kind of organic
+regulation and thought it well to give it a distinguishing name. *By
+functioning the organisation of organic tissues becomes better adapted
+for functioning.* These words describe better than any others what
+happens. It is well known that the muscles get stronger and stronger the
+more they are used, and that the same holds for glands, for connective
+tissue, etc. But in these cases only quantitative changes come into
+account. We meet with functional adaptations of a much more complicated
+and important kind, when for instance, as shown by Babák,[82] the
+intestine of tadpoles changes enormously in length and thickness
+according as they receive animal or vegetable food, being nearly twice
+as long in the second case. Besides this the so-called mechanical
+adaptations are of the greatest interest.
+
+[82] *Arch. Entw. Mech.* 21, 1906. By a very detailed comparative study
+Babák was able to prove that it is the plant proteids to which the
+effect of vegetable food is chiefly due; thus we have an adaptation
+to digestibility. Mechanical circumstances are only of secondary
+importance. (See also Yung.)
+
+It has long been known, especially from the discoveries of Schwendener,
+Julius Wolff, and Roux, that all tissues whose function it is to resist
+mechanical pressure or mechanical tension possess a minute histological
+structure specially suitable to their requirements. This is most
+markedly exhibited in the stem of plants, in the tail of the dolphin, in
+the arrangements of the lime lamellae in all bones of vertebrates. All
+these structures, indeed, are such as an engineer would have made them
+who knew the sort of mechanical conditions they would be called upon to
+encounter. Of course all these sorts of mechanically adapted structures
+are far from being “mechanically explained,” as the verbal expression
+might perhaps be taken to indicate, and as indeed has sometimes been the
+opinion of uncritical authors. The structures exist *for* mechanics,
+not *by* it. And, on the other hand, all these structures, which we
+have called mechanically “adapted” ones, are far from being mechanical
+“adaptations,” in our meaning of the word, simply because they are
+“adapted.” Many of them indeed exist previous to any functioning, they
+are for the most part truly inherited, if for once we may make use of
+that ambiguous word.
+
+But, the merely descriptive facts of mechanical adaptedness having been
+ascertained, there have now been discovered real mechanical processes
+of adaptations also. They occur among the statical tissues of plants,
+though not in that very high degree which sometimes has been assumed
+to exist; they also occur in a very high perfection in the connective
+tissue, in the muscles and in the bone tissue of vertebrates. Here
+indeed it has proved possible to change the specific structure of the
+tissue by changing the mechanical conditions which were to be withstood,
+and it is in cases of healing of broken bones that these phenomena have
+acquired a very great importance, both theoretically and practically:
+the new joints also, which may arise by force of circumstances,
+correspond mechanically to their newly created mechanical function.
+
+So far a short review of the facts of “functionelle Anpassung.” They
+seem to prove that there does exist a morphological adaptation to
+functional changes which result from the very nature of functioning. In
+fact, the actual state of all functioning tissue, the intensity of its
+state of existence, if you care to say so, may be said to be due to the
+functioning itself: the so-called atrophy by inactivity being only one
+extreme of a very long line of correspondences.[83]
+
+[83] Atrophy of muscles by inactivity is not to be confused with atrophy
+by cutting the motor nerve; the latter is very much more complete.
+
+We now, of course, have to ask ourselves if any more intimate analysis
+of these facts is possible, and indeed we easily discover that here
+also, as in the first of our groups of morphological adaptations,
+there are always single definite agents of the medium, which might be
+called “causes” or “means” of the adaptive effects, the word “medium”
+being taken as embracing everything that is external to the reacting
+cells. But of course also here the demonstration of single formative
+agents does not detract in the least from the adaptive character of
+the reaction itself. So we may say, perhaps, that localised pressure
+is the formative stimulus for the secretion of skeleton substance at a
+particular point of the bone tissue, or of the fibres of the connective
+tissue; the merely quantitative adaptations of muscles might even
+allow of a still more simple explanation.[84] But adaptations remain
+adaptations in spite of that; even if they only deserve the name of
+“primary” regulations.
+
+[84] Loeb has advocated the view that the “adaptive” growth of working
+muscles is simply due to the presence of a greater number of molecules
+in their protoplasm, muscular activity being generated by a process of
+chemical decomposition.
+
+
+THEORETICAL CONCLUSIONS
+
+We have stated in the analytical introduction to this chapter and
+elsewhere, that functional changes, which lead to morphological
+adaptations of both of our groups, may arise not only from changes of
+factors in the medium, but also from a removal of parts. As such removal
+is generally followed by restitution also, it is clear that restitutions
+and adaptations very often may go hand in hand, as is most strikingly
+shown in a fine series of experiments carried out by Vöchting, which we
+have already alluded to. Here again I should like to lay the greatest
+stress upon the fact that, in spite of such actual connections,
+restitutions and adaptations always have been separated from another
+theoretically, and that the forms are never to be resolved into sums
+of the latter. Such a view has been advocated by some recent authors,
+especially by Klebs, Holmes, and Child:[85] it is refuted I think by the
+simple fact that the first phase of every process of restitution, be it
+regeneration proper or be it a sort of harmonious differentiation, goes
+on without functioning at all, and only *for* future functioning.[86]
+
+[85] What has been really *proved* to exist by the very careful studies
+carried out by Child, is only certain cases of functional adaptation
+to mechanical conditions of the strictest kind, and relating to the
+general mobility only, but nothing more; such adaptations can be said to
+accompany restitution. See, for instance, *Journ. exp. Zool.* 3, 1906,
+where Child has given a summary of his theory.
+
+[86] Even in Vöchting’s experiments (see page 174, note 1), in which
+adaptations are mixed with true restitutions in the closest possible
+manner, a few phenomena of the latter type could most clearly be
+separated. The stimulus which called them forth must have been one of
+the hypothetic sort alluded to in a former chapter (see page 113). The
+best instances of true restitutions were offered in those cases, where,
+after the removal of all the bulbs, typical starch-storing cells were
+formed without the presence of any starch.
+
+And there has been advocated still another view in order to amplify
+the sphere of adaptation: all individual morphogenesis, not only
+restitution, is adaptation, it has been said. In its strictest form
+such an opinion of course would simply be nonsense: even specific
+adaptive structures, such as those of bones, we have seen to originate
+in ontogeny previous to all specific functions, though for the help
+of them, to say nothing of the processes of the mere outlining of
+organisation during cleavage and gastrulation. But they are “inherited”
+adaptations, it has been answered to such objections. To this remark we
+shall reply in another chapter. It is enough to state at present that
+there *is* a certain kind of, so to speak, architectonic morphogenesis,
+both typical and restitutive, previous to specific functioning
+altogether.
+
+If now we try to resume the most general results from the whole field
+of morphological adaptations, with the special purpose of obtaining new
+material for our further philosophical analysis, we have reluctantly to
+confess that, at present at least, it does not seem possible to gather
+any new real proof of life-autonomy, of “vitalism,” from these facts,
+though of course also no proof against it.
+
+We have stated that there is in every case of both our types of
+adaptive events a correspondence between the degree of the factor
+to which adaptation occurs, and the degree of the adaptive effect.
+We here may speak of an *answering* between cause and effect with
+regard to adaptation, and so perhaps it may seem as if the concept of
+an “answering reaction” (“Antwortsreaktion”), which was introduced
+into science by Goltz[87] and which is to play a great part in our
+discussions of next summer, may come into account: but in our present
+cases “answering” only exists between a simple cause and a simple effect
+and relates almost only to quantity and locality. There is therefore
+lacking the most important feature, which, as will be seen, would have
+made the new concept of value.
+
+[87] *Beiträge zur Lehre von den Functionen der Nervencentren des
+Frosches*, Berlin, 1869.
+
+We only, I believe, can state the fact that there *are* relations
+between morphogenetic causes and effects which *are* adaptations, that
+functional disturbances or changes are followed by single histogenetic
+reactions from the organism, which are compensations of its disturbed or
+changed functional state. We are speaking of facts here, of very strange
+ones indeed. But I feel unable to formulate a real proof against all
+sorts of mechanism out of these facts: there *might* be a machine, to
+which all is due in a pre-established way. Of course we should hardly
+regard such a machine as very probable, after we have seen that it
+*cannot* exist in other fields of morphogenesis. But we are searching
+for a new and independent proof; and that is indeed not to be found
+here.[88]
+
+[88] The “secondary adaptations” observed by Vöchting are too
+complicated and too much mingled with restitutions to allow any definite
+analysis of the fact of the “secondary adaptation” as such.
+
+At present it must be taken as one of the fundamental *facts* of the
+organogenetic harmony, that the cells of functioning tissues do possess
+the faculty of reacting to factors which have changed the state of
+functioning, in a way which normalises this state histologically. And
+it is a fact also that even cells, which are not yet functioning but
+are in the so-called embryonic or indifferent condition contributing to
+the physiological completion of the tissue, react to factors embracing
+new functional conditions of the whole in a manner which leads to an
+adaptation of that whole to those conditions.
+
+This is a very important point in almost all morphological adaptation,
+whether corresponding to functional changes from without or resulting
+from the very nature of functioning. In fact, such cells as have already
+finished their histogenesis are, as a rule, only capable of changing
+their size adaptively, but are not able to divide into daughter-cells
+or to change their histological qualities fundamentally; in technical
+terms, they can only assist “hypertrophy” but not “hyperplasia.” Any
+adaptive change of a tissue therefore, that implies an increase in the
+number of cellular elements or a real process of histogenesis, has to
+start from “indifferent” cells, that is to say, cells that are *not yet*
+functioning in the form that is typical of the tissue in question; and,
+strange to say, these “embryonic” cells--*i.e.* the “cambium” in higher
+plants and many kinds of cells in animals--*can* do what the functional
+state requires. It is to be hoped that future investigations will lay a
+greater stress upon this very important feature of all adaptation.
+
+
+2. PHYSIOLOGICAL ADAPTATION[89]
+
+[89] General literature: Fröhlich, *Das natürliche
+Zweckmüssigkeitsprincip in seiner Bedeutung für Krankheit und Heilung*,
+1894. Driesch, *Die organischen Regulationen*, 1901. A. Tschermak, “Das
+Anpassungsproblem in der Physiologie der Gegenwart,” in a collection
+of papers in honour of J. P. Pawlow, St. Petersburg, 1904. Bieganski,
+“Ueber die Zweckmässigkeit in den pathologischen Erscheinungen,” *Annal.
+d. Naturphil.* 5, 1906. Among the general text-books of physiology those
+by Pfeffer (*Pflanzenphysiologie*, 1897-1904) and von Bunge (*Lehrbuch
+d. Phys. d. Menschen*, 1901) are the fullest on the subject of
+“regulations.” See also different papers on general pathology by Ribbert.
+
+It is but a step from morphological adaptations to adaptations in
+physiology proper. The only difference between regulations of the
+first type and those which occur in mere functioning is, that the
+resulting products of the regulation are of definite shape and therefore
+distinctly visible in the first case, while they are not distinctly
+visible as formed materials but are merely marked by changes in chemical
+or physical composition in the latter.
+
+Metabolism, it must never be forgotten, is the general scheme within
+which all the processes of life in a given living organism go on; but
+metabolism means nothing else, at least if we use the word in its
+descriptive and unpretentious meaning, than change in the physical
+or chemical characteristics of the single constituents of that
+organism. In saying this, we affirm nothing about the physical or
+chemical nature of the actual processes leading to those physical or
+chemical characteristics, and by no means are these “processes” *a
+priori* regarded as being physical or chemical *themselves*: indeed,
+we have learned that in one large field, in the differentiation of
+our harmonious systems they certainly are not. Now, if the metabolism
+does not end in any change of visible form, then true physiological
+processes, or more particularly physiological regulations, are going on
+before us. But we are dealing with morphogenetic events or regulations,
+if the result of metabolism is marked by any change in the constituents
+of form. This however may depend on rather secondary differences as to
+the nature of regulation itself, and any kind of metabolism may really
+be of the regulatory type, whether we actually see its result as a
+constituent of form, *e.g.* owing to the production of some insoluble
+compound, or whether we do not.
+
+I do not mean to say that these are the only differences between mere
+physiological activities or regulations and organogenesis proper, as an
+originating of typical form-combination; but if we regard, as we do in
+this chapter, the given organisation of a living being as a substratum
+of its functional life, morphological and physiological adaptations are
+indeed of almost the same logical order.
+
+We had best therefore begin our discussions with a recapitulation of
+our problem. We are studying adaptations in functioning--that means we
+want to know how the organism behaves with regard to any change which
+may take place in its functional state. We apply the term regulation,
+or in particular adaptation, to any kind of reaction on the part of the
+organism which re-establishes the normal state of functioning, and we
+now want to learn to what degree such adaptations exist in the field of
+physiology.
+
+
+SPECIFIC ADAPTEDNESS *NOT* “ADAPTATION”
+
+It is important to keep well in mind our strictly formulated theme, as
+by doing so we shall be able to exclude at once from our materials a
+large group of phenomena which occasionally have been called regulations
+by physiological authors, but which, in fact, are not of the adaptation
+type and therefore cannot be said to afford those problems which
+possibly might have been expected. Typical peculiarities in functional
+life cannot be called “regulations” for this very reason. If, for
+instance, the organism selects specific amounts of specific kinds of
+organic food or of salts out of the combinations of salts or organic
+food normally offered to it in the medium, as indeed is most typically
+shown for instance by the roots of plants, there cannot be said to occur
+a “regulation” or “adaptation” with regard to the permeability of the
+cell, nor is it strictly a case of “regulation,” if so-called selective
+qualities are discovered in the processes of secretion, say of the
+epithelium of the kidney.
+
+All these facts are typical and specific peculiarities in functioning
+which are duly to be expected, where a very typical and specific
+organisation of the most elaborated kind exists. Indeed, after studying
+such an organisation we must not be astonished that functions in
+organisms follow lines which certainly they would not have taken without
+it. Take the fact which is quoted very often, that the migration of
+compounds or of ions in the organisms can happen quite contrary to all
+the laws of osmosis, from the less concentrated to the more concentrated
+side of a so-called “membrane.” There *is* no simple “membrane” in the
+organism, but a complicated organisation of an almost unknown character
+takes its place, and nothing, indeed, is against the assumption that
+this organisation may include factors which actually drive ions or
+compounds to the side of higher concentration, which indeed drive them
+by “doing work,” if we like to speak in terms of energy; and these
+factors included in organisation may very well be of a true physical or
+chemical nature.[90]
+
+[90] According to investigations of the last two years, the physics of
+colloids seems to play as important a part in physiology as osmosis
+does; we here meet “means” of functioning just as we have already had
+“means” of organogenesis.
+
+I lay great stress upon these statements, as I should like to be as
+careful as possible in the admission of anything like a “proof” of
+vitalism. It was want of scientific criticism and rigid logic that
+discredited the old vitalism; we must render our work as difficult as
+possible to ourselves, we must hold the so-called “machine theory” of
+life as long as possible, we must hold it until we are really forced to
+give it up.
+
+In a more general form we now can sum up our discussion by saying: There
+never are adaptations in physiology, requiring any special analysis,
+where there are only complications or even apparent deviations from the
+purely physico-chemical type of events which are, so to say, statical,
+*i.e.* fixed in quantity or quality, however peculiar or typically
+complicated they may be; all such peculiarities indeed, may properly
+be called “adapted,” that is to say, very well fitted to perform a
+specific part in the service of normal general functioning, and they
+are “adapted” to their part by virtue of a certain “adaptedness” of the
+organisation; but they are not “adaptations” in any sense of the word.
+
+
+PRIMARY AND SECONDARY ADAPTATIONS IN PHYSIOLOGY
+
+We approach the subject of true adaptations, that is, of adapting
+processes, as soon as any kind of variation in functioning occurs which
+corresponds to a variation of any factor of the medium in the widest
+sense. But even here our work is by no means done by simply showing
+such a correspondence of outer and inner variations. We know very well
+already, from our former studies, that now we are faced by a further
+problem, that we are faced by the question whether we have to deal with
+simple primary kinds of adaptations or with the far more important
+secondary ones.
+
+As the discrimination between primary and secondary regulations proves
+indeed to be of first-rate importance, you will allow me, I hope, to
+summarise our chief analytical statements regarding them in a most
+general form. We call primary regulatory any kind of morphogenetic or
+functional performance, which, by its very intimate nature, always
+serves to keep the whole of organisation or of functions in its normal
+state. We call secondary regulations all features in the whole of
+morphogenesis or of functioning which serve to re-establish the normal
+state after disturbances along lines which are outside the realm of
+so-called normality. This analytical discrimination will help us very
+much to a proper understanding of physiology. But before we turn to
+apply our definitions to actual facts, another preliminary problem has
+to be solved.
+
+
+ON CERTAIN PRE-REQUISITES OF ADAPTATIONS IN GENERAL
+
+We are thinking of the general and important question, what types of
+adaptations may be expected in the field of physiology and whether
+there may be certain classes of regulatory events which possibly might
+be expected to occur in the organism on *a priori* grounds, but which,
+nevertheless, are to be regarded as impossible after a more intimate
+analysis of its nature, even at the very beginning? Or, in other words,
+to what kinds of changes of the medium will an organism be found able or
+unable to adapt itself?
+
+We know that the *state of functioning* must be altered in order to call
+forth any sort of adaptation at all. Now, there can be no doubt that *a
+priori* it would seem to be very useful for the organism, if it never
+would let enter into its blood, lymph, etc., be it through the skin or
+through the intestine, any chemical compound that would prove to be
+a poison afterwards. In fact, a man, judging on the principle of the
+general usefulness of all the phenomena of the living, might suppose
+that there would exist a sort of adaptation against all poisons to the
+extent that they would never be allowed to enter the real interior of
+the body. We know that such reasoning would be incorrect. But we also
+can understand, I suppose, that an *a priori* analysis of a more careful
+kind would have reasoned differently. How could the functional state
+of the organism be changed, and how, therefore, could adaptation be
+called forth by any factor of the medium which had not yet entered the
+organism, but was only about to enter it? Not at all therefore is such
+a regulation to be expected as we have sketched; if there is to be any
+adaptation to poisons, it only can occur after the poison has really
+acted in some way, and in this case we shall indeed find regulations.
+
+You may perhaps regard this discussion as a little too academical
+and hair-splitting, but here again it was for the sake of ensuring a
+perfectly sound foundation of our chief principles that I undertook it.
+Very often, indeed, the question has been raised by the defenders of a
+mechanistic theory of life, Why then did the organisms not reject all
+poisons from the very beginning? We now may reply to that only--how
+*could* they do so? How could they “know” what is a poison and what is
+not, unless they had experienced it?--if we are allowed for a moment to
+use very anthropomorphistic language.
+
+We repeat, therefore, that the functional conditions of the organism
+must have been actually changed in order that an adaptation may occur.
+Nothing is more essential to a clear understanding of our problems than
+to keep fully in mind the exact sense of this definition.
+
+
+ON CERTAIN GROUPS OF PRIMARY PHYSIOLOGICAL ADAPTATIONS
+
+*General Remarks on Irritability.*--Turning now to more special groups
+of problems concerning physiological adaptations, let us begin with the
+primary class of them, and let us first say a few words on a subject
+which occasionally has been regarded as the basis of physiological
+regulation in general. I refer to a most important fact in the general
+physiology of irritability. Irritability of any kind is known to be
+re-established, after it has been disturbed by the process of reacting
+to the stimulus, and in certain cases, in which two different--or rather
+two opposite--kinds of reactions are possible on the same substratum,
+which increase with regard to one process whilst decreasing at the same
+time with regard to the other. The irritability of the muscle or of the
+leaves of *Mimosa* is a very good instance of the first case, whilst the
+second more complicated one cannot be illustrated better than by what
+all experience has taught us about the irritability of the retina. The
+retina is more irritable by green rays and less by red ones the more
+it has been stimulated by the latter, and more sensitive to light in
+general the more it has been exposed to darkness; and something very
+similar is true, for instance, as regards phototactic irritability in
+plants, all these phenomena being in relation to the so-called law of
+Weber.[91]
+
+[91] I only mention here that certain modern psychologists have assigned
+the true law of Weber to the sphere of judgment and not of sensation. If
+applied to objective reactions only, in their dependence on objective
+stimuli, it, of course, becomes less ambiguous, and may, in a certain
+sense, be said to measure “acclimatisation” with regard to the stimulus
+in question. The mathematical analogy of the law of Weber to the most
+fundamental law of chemical dynamics seems very important.
+
+As to “acclimatisation” in the more usual meaning of the word, with
+regard to a change of the general faculty of resisting certain agents
+of the medium, “immunity” proper is to form a special paragraph of what
+follows, and to “acclimatisation” towards different degrees of salinity
+(in algae or fishes) some special remarks will also be devoted on a
+proper occasion. There remains only “acclimatisation” to different
+temperatures; but on this topic not much more than the fact is known
+(see Davenport, *Arch. f. Entw. Mech.* 2, p. 227). “Acclimatisation”
+does not allow of a sharp general definition; it may be the result of
+very *different* kinds of adaptations in our sense of the word.
+
+It seems to me that there would be little difficulty in harmonising the
+phenomenon of the inversion of irritability with the so-called principle
+of the “action of masses” and with the laws of certain “reversible”
+processes well known in chemistry. As to the simple fact of the
+re-establishment of irritability after stimulation has occurred, or,
+in certain other cases, the fact that in spite of permanent stimulation
+irritability seems to exist permanently also, physical analogies or even
+explanations might very well be found.[92]
+
+[92] I should think that the problem of the re-establishment of
+irritability, in principle at least, arises even when there is not a
+trace of so-called “fatigue” or of a “refractory period.” The process
+of restoring may be so rapid as not to be noticeable, nevertheless some
+sort of restoring is to be postulated. We may say the “irritability” of
+an elastic ball is re-established by its elasticity. A certain analogy
+to this case may perhaps be found in the muscle. But the irritability
+of nerves with respect to nervous conduction, and of glands with
+respect to secretion, or of the articulations of *Mimosa* may be well
+understood, hypothetically at least, if we assume that the ordinary
+course of metabolic events is apt in itself to lead to a certain state
+or condition of the organs in question upon which their irritability
+is based. Certain general conditions of functioning, as for instance
+the presence of oxygen for the contraction of the muscle, would better
+be looked upon as necessary “means” of functioning than as being part
+of irritability as such. “Fatigue,” of course, may also be due to
+the absence of such “means” or to abnormal conditions originated by
+functioning itself.
+
+If now we ask whether there is anything like an adaptation appearing in
+the general characteristics of irritation and irritability, it seems to
+me that we may answer the question in an affirmative manner, as far as
+primary regulation comes into account. We, certainly, have not studied
+any abnormal regulatory lines of general functioning, we only have
+studied general functioning itself; but, indeed, there was a certain
+sort of regulation *in* functioning. Of course, by showing that one
+of the most general features of all functioning is primary-regulatory
+in itself, we do not deny the possibility of many specific functions
+in which real secondary regulations actually do exist. Nothing indeed
+is asserted about the *specific* character of functioning in its
+different types, by proving that one of the *general* features of *all*
+functioning may comparatively easily be understood. It seems to me that
+this important logical point has not always received the attention it
+deserved.
+
+*The Regulation of Heat Production.*[93]--Having finished our
+introductory remarks we now turn to the proper study of special
+physiological functioning with regard to its adaptive side, and begin
+with the most simple cases.
+
+[93] Rubner, *Die Gesetze des Energieverbrauches bei der Ernährung*,
+Leipzig u. Wein, 1902.
+
+The so-called “regulation of heat” in warm-blooded vertebrates is an
+instance of a special function which can be said to be regulatory in
+itself. There exists a normal blood heat for each species, which is
+maintained no matter whether the temperature of the medium rise or fall.
+It might seem at first as if in this case there were a little more
+of an adaptive regulation than only its well-known primary type; no
+reversion, one might say, of the direction of one and the same process
+occurs in the regulation of heat production, but one kind of process
+is called into action if it is necessary to raise the temperature, and
+another whenever it is necessary to lower it. Even in the dilatation
+and constriction of capillary vessels there are different nerves
+serving for each operation respectively, and far more important are the
+increasing of transpiration for cooling, the increasing of combustion
+for heating--two radically different processes. But, nevertheless, there
+is a certain unity in these processes, in so far as a specific locality
+of the brain has been proved to be the “centre” of them all; it is to
+this centre of course that the analysis of heat production considered as
+a kind of regulation or adaptation must be directed. Such an ultimate
+analysis, it seems to me, would have to classify heat regulation under
+the primary type of adaptations in physiology without any restriction.
+The centre acts in one sense or in the other, if stimulated by any
+temperature beyond a very limited range, and it is in the action of the
+centre that the “regulation” of heat consists.[94]
+
+[94] The phenomenon of fever we leave out of account here; it is
+regarded by some as regulation, by others as a disturbance of heat
+regulation. Of course, if the first view should ever prove to be the
+right one, fever might be classified among the real regulations of the
+secondary type.
+
+*Primary Regulations in the Transport of Materials and Certain Phenomena
+of Osmotic Pressure.*--Very similar phenomena of regulation are present
+in many processes concerned in the whole of metabolism. Let us consider
+for a moment the migration of materials in plants. Whenever any compound
+is used at a certain place, a permanent afflux of this compound to
+that place sets in from all possible directions. No doubt this is a
+“regulation,” but it is also the function itself, and besides that,
+a very simple function based almost entirely on well-known laws of
+physical chemistry. And in other cases, as in the ascent of water to
+the highest tops of our trees, which purely physical forces are said to
+be insufficient to explain, we can appeal to the unknown organisation
+of many cells, and there is nothing to prevent our attributing to these
+cells certain functions which are, if you like to say so, regulatory
+in themselves. Among other facts of so-called regulations there is the
+stopping of metabolic processes by an accumulation of their products:
+as, for instance, the transformation of starch into sugar is stopped,
+if the sugar is not carried away. Of course that is a regulation, but
+it again is an intrinsic one, and it is one of the characteristics of
+reversible chemical processes to be stopped in that way. I know very
+well that in this particular case a certain complication is added by
+the fact that it is a so-called ferment, the diastase, which promotes
+the transformation of starch into cane-sugar, and that this ferment is
+actively produced by the organism: but even its production would not
+prove that any real kind of secondary regulation exists here, if nothing
+more were known about such an active production than this single case.
+
+In a special series of experiments almost all carried out in Wilhelm
+Pfeffer’s botanical laboratory at Leipzig, an attempt has been made
+to discover in what manner the cells of plants are able to withstand
+very high abnormalities of the osmotic pressure of the medium--that is
+to say, very great changes in the amount of its salinity. That many,
+particularly the lower plants, are able to stand such changes had been
+ascertained already by the careful examinations of Eschenhagen; but
+recent years have given us a more profound insight into what happens.
+Von Mayenburg[95] has found that sundry of the species of *Aspergillus*,
+the common mould, are able to live in very highly concentrated solutions
+of several salts (KNO_3 and Na_2SO_4). They were found to regulate
+their osmotic pressure not by taking in the salts themselves, but by
+raising the osmotic pressure of their own cell sap, producing a certain
+amount of osmotically active substances, probably carbohydrates. If
+in this case it were possible to assume that the osmotic pressure of
+the medium were the real stimulus for the production of the osmotic
+substances in the cell, stimulus and production both corresponding
+in their degree, we should be entitled to speak of a primary though
+physiological[96] regulation only; and it seems to me that despite the
+discoveries of Nathansohn that certain algae and cells of higher plants
+are able to change the permeability of their surfaces in a way which
+regulates the distribution of single salts or ions in the sap of their
+cells without any regard to pure osmotic equilibrium, such a simple
+explanation might be possible.[97]
+
+[95] *Jahrb. wiss. Bot.* 36, 1901.
+
+[96] Carbohydrates cannot be ionised, and therefore there is no doubt
+that in von Mayenburg’s experiments the organism itself is actively
+at work. As to compounds liable to ionisation, it has been noticed by
+Maillard that a certain regulatory character is contained simply in the
+physical fact that the degree of ionisation changes with concentration:
+decrease of concentration for instance would be followed by an increase
+of ionisation, and so the osmotic pressure may be preserved (*C. rend.
+Soc. Biol.* 53, 1901, p. 880).
+
+[97] In the different experiments of Nathansohn (*Jahrb. wiss. Bot.*
+38, 1902, and 39, 1903) the salinity of the medium was changed in such
+a way that there was in each case either an abnormal increase or an
+abnormal decrease in the concentration of one single ion necessary
+for metabolism. The cell was found to stand these abnormal changes in
+such a way that in the case of the increase of the concentration of
+the medium it did not allow more than a certain amount of the ion in
+question to come in, and that in the case of the decrease it did not
+allow more than a certain quantity of the ion to go out. It thus seems
+as if the permeability of the surface were adjusted to a certain minimum
+and to a certain maximum of every single ion or salt, the permeability
+being stopped from within to without, whenever the minimum, and from
+without to within, whenever the maximum is reached in the cell sap; both
+irrespective of proper physical osmotic equilibrium (“Physiologisches
+Gleichgewicht”). Thus, in fact, there only would be a case of primary
+regulation, nothing more. It would all appear rather similar to what
+occurs in the kidney. Of course we do not assert that our explanation is
+right, but it is possible and is at the same time the most simple, and
+it is our general practice always to prefer the most simple hypotheses.
+
+There are many regulation phenomena connected with osmotic pressure
+and permeability in animal physiology also, though at present they are
+not worked out as fully as possible. The works of Frédéricq, J. Loeb,
+Overton and Sumner[98] would have to be taken into account by any
+one who wished to enter more deeply into these problems. We can only
+mention here that permeability to water itself also plays its part, and
+that, according to Overton’s experiments, it is a kind of solubility
+of the media in the very substance of the cell surface on which all
+permeability and its regulation depend.
+
+[98] Many fishes are able to withstand great changes in the osmotic
+pressure of sea-water; the osmotic pressure of their body fluids, though
+never in a real physical equilibrium with the pressure of the medium,
+nevertheless may vary whenever the abnormal conditions of the latter
+exceed certain limits.
+
+*Chromatic Regulations in Algae.*--The phenomena of osmotic pressure and
+its regulation may be said to be the preliminaries of metabolism proper,
+conditions necessary for it to take place. Now there is another branch
+of such preliminaries to metabolism, in which the most interesting
+regulation phenomena have been lately discovered. It is well known that
+what is called assimilation in plants, that is, the formation of organic
+compounds out of carbon dioxide (CO_2) and water, occurs only in
+the light by means of certain pigments. This pigment is in all higher
+plants and in many others the green chlorophyll, but it may be different
+in certain species of algae, and can generally be said[99] to be of
+the colour complementary to the colour of those rays which especially
+are to be absorbed and to be used for assimilation. But here we have
+“adaptedness,” not adaptation. It was in some species of primitive
+algae, the *Oscillariae*, that Gaidukow[100] found a very interesting
+instance of an active regulation in the formation of pigments. These
+algae always assume a colour which corresponds to the accidental colour
+of the rays of the medium and is complementary to it; they become green
+in red light, yellow in blue light, and so on--that is, they always
+actively take that sort of colouring which is the most suitable to
+the actual case.[101] There indeed occurs a sort of complementary
+photography in these algae; but, though adaptive, it could hardly be
+said to exceed the limits of “primary phenomena.”
+
+[99] See Stahl, *Naturw. Wochenschrift*, N. F. 5, 1906, No. 19.
+
+[100] *Arch. Anat. Phys.*, Phys. Abt. Suppl., 1902.
+
+[101] The adaptive phenomena discovered by Gaidukow depend upon a real
+alteration in the formation of pigments. In the (primary) chromatic
+adaptation of pupae of Lepidoptera with respect to the colour of
+the ground they live upon, we only have the variable effects of
+pre-established chromatophores (Poulton, *Phil. Trans. London*, 178 B,
+1888; Merrifield, *Trans. Ent. Soc. London*, 1898). The same holds for
+chromatic adaptations in crabs (Gamble and Keeble, *Quart. Journ. Micr.
+Sci.* 43, 1900; Minkiewicz, *Arch. Zool. exp. et gén.* sér. 4, 7, notes,
+1907).
+
+*Metabolic Regulations.*--And now we enter the field of regulations in
+metabolism itself. There are two kinds of outside factors of fundamental
+importance for all metabolic processes: food is one, and oxygen is the
+other. And metabolism as a whole is of two different aspects also:
+it both serves for assimilation proper--that is, building up--and it
+supplies the energy for driving the functional machine. It is clear
+that food alone--together of course with the assimilating means of the
+organism, can account for the first type of metabolism, while both food
+and oxygen, or some sort of substitute for the latter, as in certain
+bacteria, supply functional energy. Of course we are not entitled to say
+that the importance of so-called oxidation or respiration is exhausted
+by its energetic rôle: it certainly is not, for if it were, the organism
+would only be stopped in its functions if deprived of oxygen but
+would not die. It seems that certain substances always arise in the
+metabolism, in the processes of decomposition, which have to be burnt up
+in order not to become poisonous. But we shall return to the phenomena
+of organic oxidation in another chapter of the book, and shall deal with
+them from a more general point of view.[102]
+
+[102] The theory of oxidation we have shortly sketched here was
+developed in chapter B. 5, of my *Organische Regulationen*. Recent
+discoveries of Winterstein’s (*Zeitschr. allg. Physiol.* 6, 1907)
+have given the strongest support to my hypothetic statements, and, in
+fact, can be said to have brought the doctrine of organic oxidation
+to a critical point. There can be no doubt that oxygen not only plays
+the “antipoisonous” rôle I had assigned to it, but that it is not
+even of such great importance for the supply of functional energy as
+former times had assumed. No doubt it serves to drive the functional
+machine, but decomposition of certain chemical constituents of the
+organism serves this purpose even more. The latter does so in the most
+fundamental and original manner, so to speak, whilst oxidation only
+burns up its products. Almost all elemental functions, in nerve-tissue
+at least, go on very well in the absence of oxygen, provided that
+certain “poisonous” substances, resulting from this anaërobic
+metabolism, are constantly removed. In normal conditions that is
+done by oxygen, and in doing so oxygen certainly assists the supply
+of energy, but it does not furnish the whole of it. The difference
+between so-called “aërobic” and “anaërobic” life almost completely
+disappears under such a view, and many so-called “regulations,” of
+course, disappear at the same time; there is no more “intramolecular
+respiration.”
+
+Let us now try to take a short survey of all the regulations discovered
+relating to the substitution of one kind of food for another. We have
+said that food serves in the first place as building material, in the
+second place as fuel. It only deserves brief mention that, as all recent
+investigations have shown, fats, carbohydrates, and albumen are equally
+well able to serve as fuel.[103]
+
+[103] But nevertheless albumen is not to be replaced altogether in
+vertebrates by fat or carbohydrate; it probably serves some special
+function besides combustion, even in the adult.
+
+It is in the state of fasting, *i.e.* in the case of a real absence of
+*all* nourishing materials, that the organism has proved to be capable
+of regulations of the most marked nature, with regard to the combustion
+of its own materials. Respiration, we know, must go on if death is to
+be avoided, and now indeed it has been found that this process attacks
+the different tissues of the organism subjected to fasting in such an
+order that, after the combustion of the reserves, the most unimportant
+tissues with regard to life in general are destroyed first, the most
+important ones last. Thus in vertebrates the nerve cells and the heart
+are preserved as long as possible; in infusoria it is the nucleus; in
+flatworms, as the very careful studies of E. Schultz[104] have lately
+shown, it is the nerve cells and the sexual cells which longest resist
+destruction, whilst almost all the rest of the organisation of these
+animals may disappear. I should not say that we can do very much with
+these facts at present in our theoretical discussion, but they are
+certainly witness of very astonishing adaptive powers.[105]
+
+[104] *Arch. Entw. Mech.* 18, 1904.
+
+[105] To a physiological friend of mine I owe the suggestion that it is
+the permanently functioning tissues which stand hunger better than the
+others, at least if the sexual cells might be regarded as capable of
+a *sécrétion interne* in all cases. Then the adaptations in the state
+of hunger might be said to be reduced in some degree to “functional
+adaptation.” But it must remain an open question, it seems to me,
+whether such a view may indeed hold in the face of the facts observed in
+*Planaria* and infusorians.
+
+We now turn to study the cases of a compensation of nourishments
+serving for the real building up of the organism. Albumen, we know, is
+absolutely indispensable for animals, even for adults, though nothing is
+known about the purpose it serves in the latter; its place can be taken
+of course by those less complicated compounds which result from its
+first decomposition, effected by pepsin and trypsin, but nothing else
+will do. The salts of sea-water, according to Herbst’s experiments, may
+only vary to a very small degree if the development of marine animals
+is to go on well; potassium may be replaced by caesium or rubidium,
+and that is all. Much the same is true of the salts necessary to
+plants. It will not surprise us very much to hear that algae can also
+be successfully fed with the potassium salts of organic compounds, and
+higher plants with acid amides or glucoses instead of carbonic acid, as
+those products are normal steps in their assimilation; and it may also
+be fairly easily understood that nitrogen can be offered in organic form
+instead of as a nitrate.
+
+It was in the group of fungi that really important adaptations with
+regard to the proper form-producing alimentation were first discovered,
+and these are of a very complicated kind indeed. Fungi are known to
+be satisfied with one single organic compound instead of the group of
+three--fat, carbohydrate and albumen--necessary for animals. Now Pfeffer
+showed that the most different and indeed very abnormal compounds were
+able to bring his subjects to a perfect growth and morphogenesis; and,
+moreover, he found that, if several kinds of such food were offered
+together, they were consumed quite indifferently as to their chemical
+constitution, but only with regard to their nutritive value: that sort
+of food which had produced a better growth than another when both
+were offered separately was found to save the latter from consumption
+whenever both were offered together.
+
+Here we are faced by one of the most typical cases of regulations in
+metabolic physiology: the organism is able to decompose compounds of
+the most different constitution, which have never been offered to it
+before; but nevertheless, it must remain an open question whether real
+“secondary” regulation has occurred, as nothing is known in detail about
+the single steps of metabolism in these fungi. There *might* be some
+ferments equally able to destroy different classes of compounds,[106]
+and that the most nutritive compound is used up first *may* be a
+question of physico-chemical equilibrium.
+
+[106] In all cases where fungi of the same species are able to live on
+different hosts, that is, to penetrate membranes of a different chemical
+character, a similar objection as to the “secondary” type of such a
+regulation may be made.
+
+That is almost all[107] that is actually known of adaptation with regard
+to the use of an abnormal food supply. Though important, it cannot be
+said to be very much. But could we expect very numerous regulations
+here at all after what we laid down in a former paragraph about the
+possibilities of adaptive regulation in general? The functional state
+must have been altered in order that such regulations may occur. Now
+there is no doubt that this state may be really altered only if an
+abnormal food has first been taken in altogether by the cell-protoplasm
+of the body-surfaces, but never if it has only entered the cavity of the
+intestine, which, strictly speaking, is a part of the exterior medium.
+Fungi indeed not only take in the abnormal food, but also know what
+to do with it, but all animals are obliged to treat first with their
+chemical secretions what happens to be present in their intestine, in
+order that it may be taken up by their living cells, and one hardly
+can wonder that these secretions are only formed in correspondence to
+a limited number of outside stimuli. In fact, as soon as we look upon
+what adaptive or regulatory work happens in metabolism *inside* the body
+interior, we meet, even in animals, regulations of a far more developed
+type.
+
+[107] The discovery of Weinland that adult dogs are able to produce
+“lactase” in their pancreas, whenever they are fed, quite abnormally,
+with milk-sugar, has recently been said to be vitiated by an analytical
+mistake.
+
+Discoveries of the last few years have taught us that almost all
+metabolic processes in the organism, including oxidation, are carried
+out by the aid of special materials, the so-called enzymes or
+ferments. These are known to exist in the most different forms even in
+the inorganic world. They are simply chemical compounds, of specific
+types, that bring about chemical reactions between two other chemical
+materials, which in their absence would either not go on at all or would
+go on very slowly. We cannot enter here into the much disputed chemical
+theory of what is called “catalysis”: we can only say that there is no
+objection to our regarding almost all metabolic processes inside the
+organism as due to the intervention of ferments or catalytic materials,
+and that the only difference between inorganic and organic ferments is
+the very complicated character of the latter and the very high degree of
+their specification.
+
+Such a statement, of course, does not say that all metabolism has proved
+to be of a chemical nature: the *action* of the ferment when produced
+is chemical, but we do not know at all *how* the ferment is produced;
+we only know that a high degree of active regulation is shown in this
+production. In fact, it has been proved in some cases, and probably will
+be proved in a great many more in the near future, that all metabolic
+ferments, whether they promote oxidation or assimilation proper or
+chemical decomposition, are produced in a regulatory manner with regard
+to the specific compound to be dissociated or to be built up. In this
+way the whole field of metabolism is really covered by “regulations.”
+Are they real “secondary” ones? Of course the regulatory correspondence
+applies to the process of *secretion* in the *first* place, not to the
+actual formation of the ferment inside the cell. The correspondence as
+to secretion, no doubt, is of the primary type; is there any secondary
+regulation with regard to the real *production* of the ferment? I am
+sorry that I cannot answer this question affirmatively. Nothing is
+*known* at present, even here, that really proves the existence of
+adaptation of the secondary type: there *might* be a sort of statical
+“harmony” at the base of it all, established before all functioning
+*for* functioning.[108]
+
+[108] Compare the excellent review of the subject by Bayliss and
+Starling in the *Ergebnisse der Physiologie*, 5, 1906, p. 664. The
+reader who misses here an analysis of the brilliant discoveries
+of Pawlow and his followers, relating to so-called “psychical and
+associative secretion,” will find these facts dealt with in another
+section of the book. These facts, indeed, would prove vitalism, it seems
+to me.
+
+The only facts of secondary metabolic regulations which are known at
+present have been found in combination with phenomena of restitution
+after real disturbances of organisation, where, indeed, numbers and
+numbers of regulatory changes of metabolism, both in animals and plants,
+have also been recorded. But there is not one case of a secondary
+regulation really known to affect pure metabolism alone.[109] This is a
+new indicium of the primacy of *form* in the organism.
+
+[109] It would be a true secondary metabolic regulation, if after the
+extirpation of one gland another different one were to assume its
+function. Nothing is known in this respect except a few rather doubtful
+observations about the interchange of functions between thymus and
+thyroid, except also the fact that the so-called lymph-glands increase
+in size after the extirpation of the spleen. Even here, of course, a
+sort of “restitution” would be included in adaptation proper.
+
+
+IMMUNITY THE ONLY TYPE OF A SECONDARY PHYSIOLOGICAL ADAPTATION
+
+There is only one class of physiological processes in which the type
+of the real secondary regulation occurs. The discoveries of the last
+twenty years have proved beyond all doubt, and future discoveries will
+probably prove even more conclusively, that the so-called *immunity*
+against diseases is but one case out of numerous biological phenomena
+in which there is an adaptive correspondence between abnormal chemical
+stimuli and active chemical reactions on the part of the organism and in
+its interior, exceeding by far everything that was formerly supposed to
+be possible in organic regulation.
+
+The adaptive faculty of the organism against inorganic poisonous
+substances[110] is but small comparatively, and is almost always due not
+to a real process of active regulation but to the action of substances
+pre-existing in the organism--that is, to a sort of adaptiveness but
+not adaptation. Metallic poisons, for instance, may be transformed into
+harmless compounds by being combined with albumen or sulphuric acid
+and thus becoming insoluble, or free acids may be neutralised, and so
+on; but all these processes go on to a certain extent only, and, as
+was mentioned already, are almost always the result of reactions with
+pre-existing materials. Only in a few cases is there any sort of true
+adaptation to metallic substances, such as sublimate and, in a very
+small degree, arsenic, comparable in some respects with the adaptation
+to abnormally high temperatures. The organism which has been accustomed
+to receive at first very small amounts, say, of sublimate, and then
+receives greater and greater amounts of this substance by degrees, will
+at the end of this treatment be able to stand a quantity of the poison
+that would have been instantly fatal if administered at the first
+dose.[111] But the explanation of this adaptation is not known in any
+case; there seems to be some similarity between it and the so-called
+histogenetic immunity against organic poisons.
+
+[110] A good review is given by E. Fromm, *Die chemischen Schutzmittel
+des Tierkörpers bei Vergiftungen*, Strassburg, 1903.
+
+[111] Davenport, *Arch. Entw. Mech.* 2, 1895-1896, and Hausmann,
+*Pflüger’s Arch.* 113, 1906.
+
+It is in the fight against animal and vegetable poisons, such as those
+produced by bacteria, by some plants and by poisonous snakes, that the
+true adaptation of the organism reaches its most astonishing degree.
+The production of so-called “anti-bodies” in the body fluids is not the
+only means applied against noxious chemical substances of this kind: the
+existence of so-called histogenetic immunity is beyond all doubt, and
+Metschnikoff[112] certainly was also right in stating that the cells
+of the organism themselves repel the attack of living bacteria. Cells
+of the connective tissue and the white blood cells, being attracted by
+them as well as by many other foreign bodies, take them in and kill
+them. This process, called “phagocytosis” is of special frequency among
+lower animals, but it also contributes to what is called inflammation
+in higher ones.[113] And there are still other kinds of defence against
+parasites, as for instance the horny or calcareous membranes, employed
+to isolate trichinae and some kinds of bacteria. But all this is of
+almost secondary importance as compared with the adaptive faculties of
+the warm-blooded vertebrates, which produce anti-poisonous substances in
+their lymph and blood.
+
+[112] *Leçons sur la pathologie comparée de l’inflammation*, Paris, 1902.
+
+[113] The other steps or phases in the process of inflammation have also
+been regarded as adaptive: the increased quantity of body fluid for
+instance is said to serve to dilute poisonous substances.
+
+It is impossible to say here[114] more than a few words about the
+phenomena and the theory of immunity proper, which have attained the
+dimensions of a separate science. Let me only mark those general points
+which are of the greatest theoretical interest. Discoveries of the most
+recent years have shown not only that against the “toxins” of bacteria,
+snakes, and some plants, the organism is able actively to produce
+so-called “anti-toxins”--that is, soluble substances which react with
+the toxins and destroy their poisonous character--whenever required,
+but that against any foreign body of the albumen group a specific
+reaction may occur, resulting in the coagulation of that body. But the
+destruction of the noxious substance or foreign albumen actually present
+is not all that is accomplished by the organism. “Acquired immunity”
+proper, that is, security against the noxious material for a more or
+less extensive period of the *future*, depends on something more. Not
+only is there produced as much of the so-called “anti-body” as is
+necessary to combine with the noxious, or at least foreign substances
+which are present, but *more* is produced than is necessary in the
+actual case. On this over-production depends all active immunity,
+whether natural or, as in some kinds of vaccination, artificial; and
+so-called “passive” immunity, obtained by the transfusion of the serum
+of an actively immune organism into another also depends upon this
+feature.[115]
+
+[114] See Jacoby, *Immunität und Disposition*, Wiesbaden, 1906.
+
+[115] *Collected Studies on Immunity by Ehrlich and his Collaborators*,
+translated by Ch. Bolduan, New York and London, 1906.
+
+This phenomenon in particular--the production of *more* of the
+antitoxin or the “precipitin” than is actually necessary--seems to
+render almost impossible any merely chemical theory of these facts. The
+reaction between toxin and antitoxin, albumen and precipitin is indeed
+chemical; it may in fact be carried out in a test-tube; but whether the
+production of the anti-body itself is also chemical or not could hardly
+be ascertained without a careful and unbiassed analysis. There can be
+no doubt that the well-known theory of Ehrlich,[116] the so-called
+theory of side-chains (“Seitenkettentheorie”) has given a great impulse
+to the progress of science; but even this theory, irrespective of its
+admissibility in general, is not a real chemical one: the concept of a
+regeneration of its so-called haptophore groups is a strictly biological
+concept.[117]
+
+[116] So-called genuine or innate immunity, in contrast to the immunity
+which is acquired, is of course a case of adaptedness only and not of
+adaptation. There also exists a high degree of specific adaptedness in
+some animals with regard to their faculty of coagulating blood. (See Leo
+Loeb, *Biol. Bull.* 9, 1905.)
+
+[117] We cannot do more than barely mention here the problem of the
+localisation of anti-body production. In general it seems to be true
+that anti-bodies are produced by those cells which require to be
+protected against toxins; that would agree with the general rule, that
+all compensation of the change of any functional state proceeds from the
+part changed in its function.
+
+And, indeed, here if anywhere we have the biological phenomenon of
+adaptation in its clearest form. There are very abnormal changes of the
+functional state of the organism, and the organism is able to compensate
+these changes in their minutest detail in almost any case. The problem
+of the specification of the reactions leading to immunity seems to me,
+as far as I can judge as an outsider, to stand at present in the very
+forefront of the science. There cannot be the slightest doubt that
+especially against all sorts of foreign albumens the reaction is as
+strictly specific as possible; but there are some typical cases of
+specificity in the production of antitoxins also. It is, of course,
+the *fact* of specific correspondence between stimulus and reaction,
+that gives to immunity its central position among all adaptations,
+no matter whether the old hypothesis of the production of specific
+anti-bodies proves tenable, or whether, as has been urged more recently
+by some authors, the anti-body is always the same but reacts differently
+according to the medium. In the latter case it would be the medium that
+is regulated in some way by the organism in order to attain a specific
+adaptedness.
+
+
+NO GENERAL POSITIVE RESULT FROM THIS CHAPTER
+
+But now let us look back to the sum of all the physiological reactions
+studied, and let us see if we have gained a new proof of the autonomy of
+life from our long chapter.
+
+We freely admit we have not gained any really new *proof*, but we may
+claim, I think, to have gained many indicia for the statement that
+the organism is not of the type of a machine, in which every single
+regulation is to be regarded as properly prepared and outlined.
+
+It is precisely in the field of immunity that such a machine-like
+preparation of the adaptive effects seems almost impossible to be
+imagined. How indeed could there be a machine, the chemical constituents
+of which were such as to correspond adaptively to almost every
+requirement?--to say nothing of the fact that the production of *more*
+of the protecting substance than is actually necessary could hardly be
+said to be “chemical.”
+
+In fact, we are well entitled to say that we have reached here the very
+heart of life and of biology. If nevertheless we do not call the sum of
+our facts a real proof of vitalism, it is only because we feel unable
+to formulate the analysis of what happens in such a manner as to make
+a machine as the basis of all reactions absolutely unimaginable and
+unthinkable. There *might* be a true machine in the organism producing
+immunity with all its adaptations. We cannot disprove such a doctrine by
+demonstrating that it would lead to a real *absurdity*, as we did in our
+analysis of differentiation of form; there is only a very high degree of
+improbability in our present case. But an indirect *proof* must reduce
+to *absurdity* all the possibilities except one, in order to be a proof.
+
+Mechanistic explanations in all branches of functional physiology
+proper, so much in vogue twenty years ago, can indeed be said to
+have failed all along the line: the only advantage they have brought
+to science is the clearer statement of problems to which we are now
+accustomed. But we are not fully entitled to say[118] that there never
+will be any mechanistic explanation of physiological functions in the
+future. It may seem as improbable as anything can be; but we wish to
+know not what is improbable but what is not possible.
+
+[118] Here again I should like to except from this statement the
+discoveries of Pawlow. See page 204, note 1.
+
+Now of course you might answer me that after we have indeed
+shown that the production of form, as occurring on the basis of
+harmonious-equipotential systems, is a fact that proves vitalism,
+the acts taking place on the basis of that form after its production
+would have been proved to be vitalistic also, or at least to be in
+some connection with vitalistic phenomena. Certainly they would, and
+I myself personally should not hesitate to say so. But that is not
+the question. We have to ask: Is any new proof, *independent of every
+other*, to be obtained from the facts of physiological adaptation in
+themselves? And there is really none. Mere regulatory correspondence
+between stimuli and reactions, even if it be of the adaptive type and
+occur in almost indefinite forms, never really disproves a machine as
+its basis so long as the stimuli and reactions are *simple* and uniform.
+Next summer, however, we shall see that vitalism may be proved by such a
+correspondence if the two corresponding factors are not simple and not
+uniform.
+
+We most clearly see at this point what it really was in our analysis of
+differentiation that allowed us to extract a real proof of vitalism from
+it. Not the mere fact of regulability, but certain specific relations
+of space, of locality, lay at the very foundation of our proof. These
+relations, indeed, and only these relations, made it possible to
+reduce *ad absurdum* any possible existence of a machine as the actual
+basis of what we had studied. In our next chapter again it will be
+space-relations, though analysed in a different manner, that will enable
+us to add a second real proof of vitalism to our first one.
+
+With this chapter we conclude the study of organic regulation in all its
+forms, as far as morphogenesis and metabolism are in question.
+
+But our analysis of these regulations would be incomplete and indeed
+would be open to objections, if we did not devote at least a few words
+to two merely negative topics, which will be taken more fully into
+consideration later on.
+
+
+A FEW REMARKS ON THE LIMITS OF REGULABILITY
+
+There has never been found any sort of “experience” in regulations
+about morphogenesis or in adaptations of the proper physiological
+type. Nothing goes on “better” the second time than it did the first
+time;[119] everything is either complete, whenever it occurs, or it does
+not occur at all.
+
+[119] The few cases of an “improvement” of morphogenetic acts in
+hydroids described by myself are too isolated at present to be more
+than mere problems (*Arch. Entw. Mech.* 5, 1897). The same is true, it
+seems to me, with regard to certain recent discoveries made by R. Pearl
+on *Ceratophyllum* (*Carnegie Inst. Wash. Publ.* No. 58, 1907); and by
+Zeleny on a medusa (*Journ. exp. Zool.* 5, 1907). Pawlow’s discovery,
+that the enzymotic composition of the pancreatic fluid in dogs becomes
+more and more adapted to a specific composition of the food (either meat
+or bread and milk) the longer such a specific composition is offered
+to the individual animal, may probably be understood as a case of mere
+functional adaptation of the cells of the digestive glands, if it stands
+criticism at all (see Bayliss and Starling, *Ergeb. Physiol.* 5, 1906,
+p. 682).
+
+That is the first of our important negative statements about
+regulations; the second relates to the phrase just used, “or it does
+not occur at all.” There are indeed limits of regulability; adaptations
+are not possible to every sort of change of the physiological state:
+sickness and death could not exist if they were; nor is restitution
+possible in all cases where it might be useful. It is a well-known fact,
+that man is only able to heal wounds but is altogether destitute of the
+faculty of regeneration proper. But even lower animals may be without
+this faculty, as are the ctenophores and the nematodes for instance, and
+there is no sort of correspondence between the faculty of restitution
+and the place in the animal kingdom. It is not altogether impossible
+that there may be found, some day, certain conditions under which every
+organism is capable of restoring any missing part; but at present we
+know absolutely nothing about such conditions.[120]
+
+[120] Experiments carried out in the “Biologische Versuchsanstalt” at
+Vienna indeed have shown that many animal types are capable of at least
+a certain degree of restitution, although they had previously been
+denied this faculty by zoologists.
+
+But no amount of negative instances can disprove an existing
+positive--which is what we have been studying. Our analysis based upon
+the existence of regulations is as little disparaged by cases where no
+regulability exists as optical studies are by the fact that they cannot
+be undertaken in absolute darkness.
+
+
+
+
+*D.* INHERITANCE: SECOND PROOF OF THE AUTONOMY OF LIFE
+
+
+All organisms are endowed with the faculty of re-creating their own
+initial form of existence.
+
+In words similar to these Alexander Goette, it seems to me, has given
+the shortest and the best expression of the fact of inheritance. Indeed,
+if the initial form in all its essentials is re-created, it follows from
+the principle of univocality, that, *ceteris paribus*, it will behave
+again as it did when last it existed.
+
+By the fact of inheritance life becomes a rhythmic phenomenon, that is
+to say, a phenomenon, or better, a chain of phenomena, whose single
+links reappear at constant intervals, if the outer conditions are not
+changed.
+
+
+THE MATERIAL CONTINUITY IN INHERITANCE
+
+It was first stated by Gustav Jaeger and afterwards worked out into
+a regular theory by Weismann, that there is a continuity of material
+underlying inheritance. Taken in its literal meaning this statement is
+obviously self-evident, though none the less important on that account.
+For as all life is manifested on bodies, that is on matter, and as the
+development of all offspring starts from parts of the parent bodies,
+that is from the matter or material of the parents, it follows that in
+some sense there is a sort of continuity of material as long as there is
+life--at least in the forms we know of. The theory of the continuity of
+“germ-plasm” therefore would be true, even if germ-cells were produced
+by any and every part of the organism. That, as we know, is not actually
+the case: germ-cells, at least in the higher animals and in plants, are
+produced at certain specific localities of the organism only, and it is
+with regard to this fact that the so-called theory of the “continuity of
+germ-plasm” acquires its narrower and proper sense. There are distinct
+and specific lines of cell-lineage in ontogenesis, so the theory states,
+along which the continuity of germ-protoplasm is kept up, which, in
+other words, lead from one egg to the other, whilst almost all other
+lines of cell-lineage end in “somatic” cells, which are doomed to
+death. What has been stated here is a fact in many cases of descriptive
+embryology, though it can hardly be said to be more than that. We know
+already, from our analytical and experimental study of morphogenesis,
+that Weismann himself had to add a number of subsidiary hypotheses to
+his original theory to account for the mere facts of regeneration proper
+and the so-called vegetative reproduction in plants and in some animals,
+and we have learned that newly discovered facts necessitate still more
+appendixes to the original theory. In spite of that, I regard it as
+very important that the fact of the continuity of some material as one
+of the foundations of inheritance has clearly been stated, even if the
+specialised form of the theory, as advocated by Weismann in the doctrine
+of the “germ-lineages” (“Keimbahnen”) should prove unable to stand
+against the facts.
+
+The important problem now presents itself: What is the material, the
+matter, which is handed down from generation to generation as the
+basis of inheritance? Weismann, as we know, regarded it as a very
+complicated structure, part of which by its disintegration became the
+foundation of individual embryology. We have disproved, on the authority
+of many facts, the latter part of this assumption; but of course the
+first part of it may turn out to be true in spite of this. We have no
+means at present to enable us to say *a priori* anything positive or
+negative about the important question of the nature of that matter, the
+continuity of which in inheritance is in some sense a self-evident fact,
+and we therefore shall postpone the answer until a later point of our
+analytical discussion.
+
+
+ON CERTAIN THEORIES WHICH SEEK TO COMPARE INHERITANCE TO MEMORY
+
+It will be advisable first to study some other theoretical views which
+have been put forward with regard to inheritance. The physiologist
+Hering, as early as 1876, compared all heredity to the well-known fact
+of memory, assuming, so to say, a sort of remembrance of all that
+has happened to the species in the continuity of its generations;
+and several German authors, especially Semon, have lately made this
+hypothesis the basis of more detailed speculation.
+
+It is not clear, either from Hering’s paper[121] or from Semon’s
+book,[122] what is really to be understood here by the word “memory,”
+and, of course, there might be understood by it very different things,
+according to the author’s psychological point of view. If he is a
+“parallelist” with regard to so-called psychical phenomena, he would use
+the word memory only as a sort of collective term to signify a resultant
+effect of many single mechanical events, as far as the material world of
+his parallel system comes into account, with which of course the problem
+of inheritance alone deals; but if he maintains the theory of so-called
+psycho-physical interaction, the psychical would be to him a primary
+factor in nature, and so also would memory. As we have said, it is by no
+means clear in what sense the word “memory” is used by our authors, and
+therefore the *most* important point about the matter in question must
+remain *in dubio*.
+
+[121] *Ueber das Gedächtnis als eine allgemeine Function der organischen
+Materie*, Wien, 1870. New edition in *Klassiker d. exakt. Wiss.*,
+Leipzig, Engelmann.
+
+[122] *Die Mneme*, Leipzig, 1904.
+
+But another topic is even more clear in the theory of inheritance, as
+stated in Hering’s and Semon’s writings. The hypothetical fact that
+so-called “acquired characters” are inherited is undoubtedly the chief
+assumption of that theory. Indeed, it would be difficult to understand
+the advantage of the ambiguous word memory, had it not to call attention
+to the hypothetic fact that the organism possesses the faculty of
+“remembering” what once has happened to it or what it once has “done,”
+so to speak, and profiting by this remembering in the next generation.
+The zoologist Pauly indeed has stated this view of the matter in very
+distinct and clear terms.
+
+As we soon shall have another occasion to deal with the much-discussed
+problem of the “inheritance of acquired characters,” we at present
+need only say a few words about the “memory-theory” as a supposed
+“explanation” of heredity. Undoubtedly this theory postulates, either
+avowedly or by half-unconscious implication, that all the single
+processes in individual morphogenesis are the outcome either of
+adaptations of the morphological type, which happened to be necessary
+in some former generation, or of so-called contingent “variations,” of
+some sort or other, which also happened once in the ancestral line.
+Such a postulate, of course, is identical with what is generally called
+the theory of descent in any of its different forms. This theory is
+to occupy us in the next lectures; at present we only analyse the
+“memory-theory” as a theory of heredity in itself. In any case, to
+regard memory as the leading point in inheritance, at least if it is to
+signify what is called memory in any system of psychology, would be to
+postulate that either adaptation or contingent “variation” has been the
+origin of every morphogenetic process. Indeed, the American physiologist
+Jennings did not hesitate to defend such a view most strongly, and many
+others seem to be inclined to do the same.
+
+But such an assumption most certainly cannot be true.
+
+It cannot be true, because there are many phenomena in morphogenesis,
+notably all the phenomena akin to restitution of form, which occur
+in absolute perfection even the very first time they happen. These
+processes, for the simple reason of their *primary perfection*, cannot
+be due either to “learning” from a single adaptation, or to accidental
+variation. We shall afterwards employ a similar kind of argument to
+refute certain theories of evolution. It therefore may be of a certain
+logical interest to notice that at present, combating the memory-theory
+of inheritance, and hereafter, combating certain theories of descent,
+we select not “adaptation” or “variation” as the central points to be
+refuted, but the assumed *contingency* of both of them.
+
+The word “memory,” therefore, may be applied to the phenomena of
+inheritance only in a very figurative meaning, if at all. We do not
+wholly deny the possibility of an inheritance of acquired characters, as
+will be seen later on, and to such a fact there might perhaps be applied
+such a term as “memory” in its real sense, but we simply *know* that
+there *is* something in inheritance which has no similarity whatever
+to what is called “memory” in any species of psychology. A primary
+perfection of processes occurring quite abnormally proves that there is
+a “knowing” of something--if we may say so--but does not prove at all
+that there is a “remembering.”
+
+
+THE COMPLEX-EQUIPOTENTIAL SYSTEM AND ITS RÔLE IN INHERITANCE[123]
+
+[123] Driesch, *Organ. Regul.* 1901.
+
+But we thus far have reached only negative results. Is the question
+necessarily to remain at this point, which could hardly be said to be
+very satisfying; or could we perhaps get better, that is, positive
+results about inheritance by a change of our analytic methods? Let us
+try to analyse the facts that occur in inheritance instead of beginning
+with hypotheses which claim to be complete explanations. Perhaps we
+shall gain, if but small, yet certainly fixed results by an analysis
+which goes from the facts to the theory and not from the theory to the
+facts.
+
+Let the discussions that are to follow be placed upon a basis as broad
+as possible.
+
+Our studies of morphogenetic restitution have shown us that besides the
+harmonious-equipotential systems another and widely different type of
+morphogenetic “systems” (*i.e.* unities consisting of elements equal in
+morphogenetic faculty) may also be the basis of restitution processes.
+Whilst in the harmonious system the morphogenetic acts performed by
+every single element in any actual case are single acts, the totality
+of all the single acts together forming the harmonious whole, in the
+other type of systems now to be examined, complex acts, that is, acts
+which consist of a manifoldness in space and in time, can be performed
+by each single element, and actually are performed by one or the other
+of them. We therefore have given the title of “complex-equipotential
+systems” to the systems in question, as all our denominations are based
+on the concept of the prospective morphogenetic potency, that is of the
+possible fate of the elements.
+
+The cambium of the Phanerogams may be regarded as the very type of a
+complex-equipotential system, promoting restitution of form. It runs
+through the whole stem of our trees, in the form of a hollow tube,
+placed between the inner and the outer cell-layers of the stem, and
+either branch or root may originate from any single one of its cells,
+just as circumstances require. We might call the cambium a system of the
+“complex” type of course, even if every one of its constituents were
+able to form only a root or only a branch by way of restitution. But in
+fact one and the same element can form both of these complex-structures;
+it depends only on its relative position in the actual part of the stem
+isolated for the purposes of experiment, what will be accomplished in
+every case. Here we have a state of affairs, which we shall encounter
+again when studying regeneration in animals: every element of the system
+may be said to contain potencies for the “ideal whole,” though this
+ideal whole will never be realised in its proper wholeness.[124]
+
+[124] The “ideal whole” is also proved to exist, if any *given*
+“Anlage,” say of a branch, is forced to give origin to a root, as has
+really been observed in certain plants. This case, like many other
+less extreme cases of what might be called “compensatory heterotypy,”
+are best to be understood by the aid of the concept of “prospective
+potency.” It is very misleading to speak of a metamorphosis here. I
+fully agree with Krašan about this question. See also page 112, note 1,
+and my *Organ. Regul.* pp. 77, 78.
+
+But there is no need to recur to the “ideal whole” in many other cases
+of adventitious restitution in plants. On isolated leaves of the
+well-known begonia, a whole plant, containing all the essential parts,
+may arise from any single cell[125] of the epidermis, at least along the
+veins, and in some liverworts it has been shown by Vöchting, that almost
+every cell of the whole is able to reproduce the plant, as is also the
+case in many algae.
+
+[125] Winkler has discovered the important fact, that the adventitious
+buds formed upon leaves may originate either from one single cell of
+the epidermis or from several cells together; a result that is very
+important with respect to the problem of the distribution of “potencies.”
+
+In the animal kingdom it is chiefly and almost solely the phenomena
+of regeneration proper which offer typical instances of our systems,
+since adventitious restitution, though occurring for instance in the
+restitution of the lens of vertebrates from the iris, and though
+connected also with the events in regeneration proper,[126] is of but
+secondary importance in animal restitution, at least, if compared with
+restitution in plants. If we study the regeneration of a leg in the
+common newt, we find that it may take place from every section, the
+point of amputation being quite at our choice. Without regarding here
+the exact order of the regeneration phenomena, which is almost unknown
+at present, we in any case can say without any doubt that the line
+of consecutive possible cross-sections forms a complex-morphogenetic
+system, as every one of them is able to give rise to a complex organ,
+viz. the foot and part of the leg. It is an open question whether this
+complex system is to be called “equipotential” or not. It indeed seems
+to be inequipotential at the first glance, for each single section has
+to form a different organogenetic totality, namely, always that specific
+totality which had been cut off; but if we assume hypothetically that
+the real “Anlage” which is produced immediately by the cells of the
+wounded surface is the very same for all of them, and that it is the
+actual state of organisation which determines to what result this
+Anlage is to lead,[127] we may say that the series of consecutive
+cross-sections of a newt’s leg does form a morphogenetic system of the
+complex-equipotential type, promoting secondary regulations of form.
+
+[126] The “regeneration” of the brain of annelids for instance is far
+better regarded as an adventitious formation than as regeneration
+proper: nothing indeed goes on here at the locality of the wound; a new
+brain is formed out of the ectoderm at a certain distance from it.
+
+[127] A full “analytical theory of regeneration” has been developed
+elsewhere (*Organ. Regul.* p. 44, etc.). I can only mention here that
+many different problems have to be studied by such a theory. The
+formation of the “Anlage” out of the body and the differentiation of
+it into the completely formed results of regeneration are two of them.
+The former embraces the question about the potencies not only of the
+regenerating body but of the elements of the Anlage also; the latter
+has to deal with the specific order of the single acts of regenerative
+processes.
+
+Now all these difficulties vanish, if we consider the regeneration of
+animals, such for instance as many worms of the annelid class or our
+familiar ascidian *Clavellina*, in which regeneration in both directions
+is possible. The wound at the posterior end of the one half which
+results from the operation forms a posterior body half, the wound at
+the anterior end of the other half forms an anterior one. Again, it is
+the ideal whole which we meet here: each section of the body indeed may
+be said to contain the potencies for the production of the totality,
+though actually this totality is always realised by the addition of two
+partial organisations. The title of complex-equipotential systems thus
+seems to be fully justified as applied to the systems which are the
+basis of regeneration: each section of the regenerating body may in fact
+produce the same complex whole, or may, if we prefer to say so, at least
+prepare the ground for that complex Anlage, out of which the complex
+totality is actually to arise, in the same manner.
+
+It often occurs in science, that in rather strange and abnormal
+conditions something becomes apparent which might have been found
+everywhere, which is lying before our eyes quite obviously. Are
+we not in just such a condition at present? In order to study the
+complex-equipotential systems, we turn to the phenomena of regeneration
+and of restitution in general; we occasionally even introduce hypotheses
+to render our materials more convenient for our purposes; and all the
+time there is one sort of complex-equipotential system in the body of
+every living being, which only needs to be mentioned in order to be
+understood as such, and which indeed requires no kind of preliminary
+discussion. The system of the propagation cells, in other words the
+sexual organ, is the clearest type of a complex-equipotential system
+which exists. Take the ovary of our sea-urchin for instance, and there
+you have a morphogenetic system every element of which is equally
+capable of performing the same complex morphogenetic course--the
+production of the whole individual.
+
+Further on we shall deal exclusively with this variety of our systems,
+and in doing so we shall be brought back to our problem of heredity. But
+it had its uses to place our concept of the complex-equipotential system
+upon such a broad basis: we at once gave a large range of validity to
+all that is to follow--which, indeed, does not apply to inheritance
+alone, though its significance in a theory of heredity may be called its
+most important consequence.
+
+
+THE SECOND PROOF OF LIFE-AUTONOMY. ENTELECHY AT THE BOTTOM OF INHERITANCE
+
+After we had established the concept of the harmonious-equipotential
+system in a former chapter, we went on to study the phenomena of the
+differentiation of it, and in particular the problem of the localisation
+of all differentiations. Our new concept of the complex-equipotential
+system is to lead us to an analysis of a different kind: we shall pay
+special attention to the origin, to the *genesis* of our complex systems
+that show equipotentiality.
+
+If we review the process of ontogenesis, we are able to trace back every
+complex system to a very small group of cells, and this small group of
+cells again to one single cell. So in plants the cambium may be shown
+to have originated in a sort of tissue-rudiment, established at a very
+early period, and the ovary may be demonstrated to be the outcome of a
+group of but a few cells, constituting the first visible “Anlage” of the
+reproductive organs. At the end then, or from another point of view at
+the beginning, a single cellular element represents the very primordial
+egg-cell.
+
+The whole cambium, there can be no doubt, must be regarded as the result
+of a consecutive number of cell-divisions of the one cell from which it
+originates. So must it be with the ovary. The primordial egg-cell has
+undergone a long line of consecutive divisions; the single eggs are the
+last result of them.
+
+We now proceed to some considerations which have a certain
+logical similarity to those which inaugurated our analysis of the
+differentiation of the harmonious-equipotential systems, though the
+facts in question are very different.
+
+Viewed by itself without any kind of prepossessions, as it might
+be by any one who faces a new problem with the single postulate of
+introducing new natural entities--to use the scholastic phrase--as
+little as possible, the development of the single egg might be regarded
+as proceeding on the foundation of a very complicated sort of machine,
+exhibiting a different kind of construction in the three chief
+dimensions of space, as does also the organism which is to be its result.
+
+But could such a theory--irrespective of all the experimental facts
+which contradict it--could such a theory stand before the *one* fact,
+that there occurs a *genesis* of that complex-equipotential system,
+of which our one single egg forms a part? Can you imagine a very
+complicated machine, differing in the three dimensions of space, to
+be divided hundreds and hundreds of times and in spite of that to
+remain always the same whole? You may reply that during the period
+of cell-divisions there is still no machine, that the machine is
+established only after all the divisions are complete. Good; but what
+then constructs this machine in the definitive cells of our systems, say
+in the eggs? Another sort of machine perhaps? That could hardly be said
+to be of much use. Or that entelechy of which we have spoken? Then you
+would recur to our first proof of vitalism and would burden entelechy
+with a specific performance, that is with the construction of the
+hypothetic machine which you are postulating in every single egg. But of
+course you would break the bounds of physics and chemistry even then.
+
+It seems to me that it is more simple, and so to say more natural, not
+to recur to our first proof of life-autonomy in order to keep to the
+“machine theory” in this new branch of inquiry, but to consider facts as
+they offer themselves to analysis.
+
+But then indeed we are entitled to draw an independent second proof of
+the autonomy of life from our analysis of the genesis of systems of the
+complex-equipotential type. We say it is a mere absurdity to assume that
+a complicated machine, typically different in the three dimensions of
+space, could be divided many many times, and in spite of that always
+be the whole: therefore there cannot exist any sort of machine as the
+starting-point and basis of development.
+
+Let us again apply the name entelechy to that which lies at the very
+beginning of all individual morphogenesis.
+
+Entelechy thus proves to be also that which may be said to lie at
+the very root of inheritance,[128] or at least of the outcome of
+inheritance; the individual formation of the next generation is shown
+not to be performed by a machine but by a natural agent *per se*.
+
+[128] And, of course, at the root of every new starting of certain
+parts of morphogenesis also, as in regeneration and in adventitious
+budding; these processes, as we know, being also founded upon
+“complex-equipotential systems,” which have had their “genesis.”
+
+
+THE SIGNIFICANCE OF THE MATERIAL CONTINUITY IN INHERITANCE
+
+But what about the material continuity appearing in inheritance, which
+we have said to be almost self-evident, as life is only known to exist
+on material bodies? Is there not, in fact, a serious contradiction
+in admitting at the same time entelechy on the one side and a sort
+of material condition on the other as the basis of all that leads to
+and from inheritance? Next summer the relation between matter and our
+autonomous agent of life will be studied more fully; at present it must
+be enough to state in a more simple and realistic way, what we hold
+this relation to be. There is no contradiction at all in stating that
+material continuity is the basis of inheritance on the one side, and
+entelechy on the other. It would be very inconvenient for us if there
+were any: for the material continuity is a mere fact and our entelechy
+we hope we have proved to exist also; if now there were any sort of
+contradiction in assuming the existence of both of them, of course it
+would be fatal to our proof.
+
+Let us try to comprehend what is meant by the statement that entelechy
+and something material are at work in inheritance at the same time.
+Entelechy has ruled the individual morphogenesis of the generation which
+is regarded as being the starting-point for inheritance, and will rule
+also the morphogenesis of the generation which is to follow; entelechy
+determines the egg to be what it is, and the morphogenesis starting from
+this egg to be what it is also. Entelechy, at present, is not much more
+for us than a mere word, to signify the autonomous, the irreducible of
+all that happens in morphogenesis with respect to *order*, in the one
+generation and in the next. But may not the material continuity which
+exists in inheritance account perhaps for the material elements *which
+are to be ordered*? In such a way, indeed, I hope we shall be able to
+reconcile entelechy and the material basis of heredity. May it not be
+that there exist some “means” for morphogenesis, which are handed down
+from generation to generation, always controlled by entelechy, and which
+constitute the real significance of the continuity of matter during
+inheritance?
+
+
+THE EXPERIMENTAL FACTS ABOUT INHERITANCE
+
+Discoveries of the last few years do seem to show that such means
+of a material character, though not the foundation of that order of
+processes which is inherited, are nevertheless among the most necessary
+conditions for the accomplishment of inheritance in general. It is
+scarcely necessary to remind you that for very many years all concrete
+research on heredity proper--that is, the actual comparison of the
+various specific characters in the generations of the grandfather, the
+father, and the child--was due to Galton. You may also be aware that in
+spite of Galton’s inestimable services it was not till 1900 that one of
+the active principles concerned in inheritance was found independently
+by de Vries, Correns, and Tschermak, and that this principle happened
+to be one that *had* been discovered already, stated with the utmost
+clearness and precision by the Augustinian monk, Gregor Mendel,[129] as
+early as 1865, though it had been completely forgotten ever since.
+
+[129] New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann;
+see also Bateson, *Mendel’s Principles of Heredity*, Cambridge, 1902.
+
+The so-called “rule of Mendel” is based upon experiments with hybrids,
+that is, with the offspring of parents belonging to different species,
+or, at least, varieties, but it relates not to the characters of the
+generation resulting immediately from hybridisation, the “first”
+generation of hybrids, as we shall call it, but to the characters of
+that generation which is the result of crossing the hybrids with each
+other, provided that this leads to any offspring at all. There are many
+cases indeed, both amongst animals and plants, where the offspring of
+the hybrids, or in other terms the “second” generation, is found to
+consist of individuals of three different types--the mixed[130] type
+of the hybrids themselves, and the two pure types of the grandparents.
+Whenever the individuals of the “second” generation are separated into
+these three different types, hybrids are said to “split.” It is the
+fact of this splitting on the one hand, and on the other hand a certain
+statement about the numbers of individuals in the three different types
+of the “second” generation, that gives its real importance to Mendel’s
+rule.
+
+[130] For the sake of simplicity I shall not deal here with those
+cases of hybridisation in which one quality is “recessive,” the other
+“dominant,” but only allude to the cases, less numerous though they be,
+where a real mixture of maternal and paternal qualities occurs.
+
+Before discussing what may follow from Mendel’s discovery for the
+theory of heredity, we must lay stress on the fact that there are many
+exceptions to his rule. In quite a number of cases the hybrids are of
+one or more types, which remain constant: there is no splitting at all
+in the second generation. But that does not affect the rule of Mendel in
+those cases where it is true. Where there is a “splitting” in the second
+generation, there also are the numerical proportions stated by Mendel;
+there never are other relations among the numbers of individuals of the
+mixed and of the two pure types than those given by his rule. I regard
+it as very important that this real meaning of Mendel’s principle should
+be most clearly understood.
+
+From the fact of the splitting of hybrids in the second generation most
+important consequences may be drawn for the theory of inheritance; the
+split individuals, if crossed with each other, always give an offspring
+which remains pure; there is no further splitting and no other change
+whatever. The germ-cells produced by the split individuals of the second
+generation may therefore be said to be “pure,” as pure as were those of
+the grandparents. But that is as much as to say that the pureness of
+the germ-cells has been preserved in spite of their passing through the
+“impure” generation of the hybrids, and from this fact it follows again
+that the union of characters in the hybrids must have been such as to
+permit pure separation: in fact, the germ-cells produced by Mendelian
+hybrids may hypothetically be regarded as being pure themselves.[131]
+
+[131] This hypothesis was first suggested by Sutton and is at present
+held by orthodox Mendelians; but probably things are a little more
+complicated in reality, as seems to be shown by some facts in the
+behaviour of so-called “extracted recessives.” In Morgan’s *Experimental
+Zoology*, New York, 1907, a full account of the whole matter is given.
+
+We have not yet considered one feature of all experiments in
+hybridisation, which indeed seems to be the most important of all for
+the theory of inheritance, if taken together with the fact of the
+pureness of the germs. The rule of Mendel always relates to one single
+character of the species or varieties concerned in hybridisation, and
+if it deals with more than one character, it regards every one of them
+separately; indeed, the rule holds for every one of them irrespective
+of the others. We cannot study here how this most important fact of
+the independence of the single characters of a species with regard to
+inheritance leads to the production of new races, by an abnormal mixture
+of those characters. We only take advantage of the fact theoretically,
+and in doing so, I believe, we can hardly escape the conclusion that
+the independence of the single characters in inheritance, taken
+together with the pureness of the germ-cells in the most simple form
+of hybrids, proves that there occurs in inheritance a sort of handing
+over of single and separate morphogenetic agents which relate to the
+single morphogenetic characters of the adult. We may use Bateson’s
+word “allelomorphs” for these agents, or units, as they may be called,
+thereby giving expression to the fact that the single and separate
+units, which are handed over in inheritance, correspond to each other in
+nearly related species without being the same.
+
+And so we have at least an inkling of what the material continuity of
+inheritance is to mean, though, of course, our “single and separate
+morphogenetic agents,” or “units” or “allelomorphs” are in themselves
+not much more than unknown somethings described by a word; but even then
+they are “somethings.”
+
+Besides the researches relating to the rule of Mendel and its
+exceptions, founded, that is, upon a study of the “second” generation of
+hybrids, there is another important line of research lately inaugurated
+by Herbst, which investigates the first generation in hybridisation.
+The hybrids themselves are studied with the special purpose of finding
+out whether the type of the single hybrid may change according to the
+conditions of its development, both outer and inner. The discoveries
+thus made may lead some day to a better understanding of the intimate
+nature of the “units” concerned in heredity, and perhaps to some
+knowledge of the arranging and ruling factor in morphogenesis also.
+
+Starting from the discovery of Vernon, that the hybrids of sea-urchins
+are of different types according to the season, Herbst[132] was able
+to show that differences among the hybrids with regard to their being
+more of the paternal or more of the maternal type, are in part certainly
+due to differences in temperature. But there proved to be still another
+factor at work, and Herbst has succeeded in discovering this factor by
+changing the internal conditions of morphogenesis. Whenever he forced
+the eggs of *Sphaerechinus* to enter into the first[133] phase of
+artificial parthenogenesis and then fertilised them with the sperm of
+*Echinus*, he was able to approximate the offspring almost completely
+to the maternal type, whilst under ordinary conditions the hybrids in
+question follow the paternal far more than the maternal organisation.
+
+[132] *Arch. Entw. Mech.* 21, 22, and 24, 1906-7; see also Doncaster,
+*Phil. Trans. Royal Soc.* London, B. 196, 1903. The influence of
+different temperature upon the organisation of the hybrids is not
+always quite pure, inasmuch as the paternal and the maternal forms may
+themselves be changed by this agent. In spite of that there exists an
+influence of the temperature upon the hybrid *as such*, at least with
+regard to certain features of its organisation.
+
+[133] Only the nucleus of the egg had entered its first stages of
+activity.
+
+What is shown, in the first place, by these discoveries is the
+importance of an arranging and ruling factor in spite of all units. The
+organism is always one *whole* whether the paternal properties prevail
+or the more complicated maternal ones; in other words, all so-called
+properties that consist in the *spatial relations of parts* have nothing
+to do with “units” or “allelomorphs,” which indeed cannot be more
+than necessary means or materials, requiring to be ordered. As to the
+character of the morphogenetic single and separate units themselves
+Herbst is inclined to regard them as specific chemical substances which
+unite correspondingly during nuclear conjugation, forming a sort of
+loose chemical compound. It would depend on the constitution of this
+compound whether germ-cells of hybrids could become pure or not.
+
+
+THE RÔLE OF THE NUCLEUS IN INHERITANCE
+
+At the end of our studies on heredity we hardly can avoid saying a
+few words about the problem of the localisation of the morphogenetic
+units in the germ-cells themselves. Is it in the protoplasm or in the
+nucleus that they are placed? You all know that this question was for
+a long time regarded as more important than any other, and perhaps
+you have already blamed me for not raising it until now. But in my
+opinion results gained by the purely analytical method and carefully
+established, are always superior to those which are of a merely
+descriptive nature and doubtful besides. The famous problem of the part
+played by the nucleus in inheritance is both descriptive and doubtful:
+it is only, so to say, of factual, not of analytical importance, and
+quite insoluble at present.
+
+As for our second proof of vitalism, stating that no kind of machine
+inside the germ-cells can possibly be the foundation of their
+morphogenesis, it is clear that the protoplasm and the nucleus may both
+come into account here on equal terms. If you prefer to say so, it is to
+the nucleus and to its division in particular that the second proof of
+autonomy relates, while the first, though not over-looking the presence
+of nuclei,[134] deals “especially” with the protoplasmic nature of its
+“systems.”
+
+[134] The first proof of vitalism, indeed, rests upon the analysis of
+the differentiation of an harmonious-equipotential system as a *whole*:
+this *whole* cannot be a machine that would relate to differentiation as
+a *whole*; the question whether there might be any machines distributed
+*in* the whole, in the form of the nuclei is of no importance at all in
+this argument. Moreover the pressure experiments (see page 63) prove the
+unimportance of such “machines” for the specificity of differentiation,
+and the second proof of vitalism shows that the nuclei cannot be
+regarded as machines accounting for differentiation in *any* way.
+
+What then can we say, on the basis of actual facts, about the part taken
+by the protoplasm and by the nucleus in inheritance, now that we have
+learnt from our analytical discussion that both of them cannot be any
+kind of morphogenetic machine, but can only be means of morphogenesis?
+Let us state our question in the following way: whereabouts in the
+germ-cells are those “means” of morphogenesis localised, the existence
+of which we infer from the material continuity in the course of
+generations in general and from the facts discovered about hybridisation
+in particular?
+
+The first of the facts generally said to support the view that the
+nucleus of the germ-cells exerts a specified influence upon the
+processes of development and inheritance, relates to the proportion
+between protoplasm and nuclear material in the egg and in the spermiae.
+This proportion is very different in the two sexual products, as we
+know, there being an enormous preponderance of the protoplasm in the
+egg, of the nucleus in the spermatozoon. This seems to indicate that
+the proportion between protoplasm and nucleus is fairly indifferent
+for inheritance, as all the facts go to show that inheritance from
+the father is as common as inheritance from the mother. It is in the
+nucleus, and in the nucleus alone, that any similarity of organisation
+exists between the two sexual products, so very different in all other
+respects: therefore the nucleus should be the organ of inheritance. The
+phenomena of nuclear division, of karyokinesis, which are quite equal in
+both sexual cells, are certainly well fitted to support this hypothesis.
+
+There seems indeed to be some truth in this reasoning, but nevertheless
+it must remain hypothetical; and it must never be forgotten that
+there may be very probably some sort of morphogenetic importance in
+protoplasm also. Rauber and afterwards Boveri[135] have tried to prove
+experimentally that it is on the nuclear chromatic substance only that
+inheritance depends, but the first of these authors failed to get any
+results at all, and the latter obtained only ambiguous ones. Godlewski,
+on the contrary, has fertilised purely protoplasmic egg-fragments of
+the sea-urchin with the sperm of quite another group of Echinoderms,
+and obtained in spite of that a few stages of development of the
+pure maternal type. This experiment seems to place the morphogenetic
+importance of protoplasm beyond all doubt.
+
+[135] Boveri tried to fertilise enucleated fragments of the egg of
+*Sphaerechinus* with the sperm of *Echinus*. He failed to get any
+results in isolated experiments, but found a few small larvae of the
+pure *Echinus* type in large cultures consisting of shaken eggs. But
+later experiments on hybridisation in sea-urchins have shown that a full
+hybrid of *Echinus* and *Sphaerechinus* may be purely paternal also.
+
+I should prefer not to make any definite statement about our problem at
+present. Our actual knowledge of the organisation and metabolism of both
+nucleus and protoplasm is so extremely small and may relate to such very
+insignificant topics, that any definite decision is impossible. I myself
+believe that the nucleus plays an important part in heredity, perhaps
+even a greater one than protoplasm, but this is only my belief.[136]
+
+[136] Surely the new results of Herbst, mentioned above, are another
+indication of the importance of something in the nucleus. The first
+stage in parthenogenesis, which he used in his experiments, is a nuclear
+phenomenon.
+
+The discovery of Gruber and others, that Protozoa are only capable of
+restitution if they contain at least a fragment of the nucleus, has
+also been used occasionally as a proof of the morphogenetic importance
+of the nucleus. But might not this absence of restitution where nuclear
+material is lacking be understood equally well on the hypothesis of Loeb
+and R. S. Lillie that the nucleus is a centre of oxidation in the cell?
+Remove the heart from a vertebrate and the animal will not digest any
+more; but in spite of that the heart is not the organ of digestion.
+
+And so we lay stress once more upon this point: that the experimental
+results of hybridisation and the analytical results obtained by the
+discussion of the complex-equipotential systems are of greater value
+to the theory of heredity than all speculation about the importance or
+unimportance of special constituents of the cell, of whose organisation,
+chemistry, and physics, scarcely anything is known at present.[137]
+
+[137] Boveri (*Ergebn. üb. d. Konstitution etc. des Zellkerns*, Jena,
+1904; and “Zellen-Studien VI.” *Jen. Zeitschr.* 43, 1907) has made it
+highly probable by experiments that the different chromosomes of the
+nucleus of the sexual products play a different part in morphogenesis,
+though not in the sense of different single representatives of
+different single organs. This doctrine, of course, would not alter
+the whole problem very much: the chromosomes would only be *means* of
+morphogenesis and nothing else, no matter whether they were of equal or
+of different formative value. It only is with regard to the problem of
+the determination of sex (see page 107, note 3), that the morphogenetic
+singularity of *one* certain specific chromosome can be said to be
+proved.
+
+
+VARIATION AND MUTATION
+
+Heredity, it has been said, may be understood as resting upon the fact
+that each organism forms its own initial stage again, and that this
+initial stage always encounters conditions of the same kind.
+
+If this statement were quite correct, all the individuals of a given
+species would be absolutely alike everywhere and for ever. But they
+are not alike; and that they are not alike everywhere and for ever is
+not merely the only real foundation of the so-called theory of descent
+we possess, but also forces us to change a little our definition of
+heredity, which now proves to have been only a sort of approximation to
+the truth, convenient for analytical discussion.
+
+In the first place, the conditions which surround the initial stages
+of morphogenesis are not quite equal in every respect: and indeed
+the offspring of a given pair of parents, or better, to exclude all
+complications resulting from sexual reproduction, or amphimixis, as
+Weismann called it--the offspring of one given parthenogenetic female
+are not all equal among themselves. The individuals of each generation
+are well known to vary, and it is especially in this country that the
+so-called individual or fluctuating variation has been most carefully
+studied by statistical methods, Galton and Weldon being the well-known
+pioneers in this field.[138] In fact, if we are allowed to assume that
+this sort of variation is the outcome of a variation of conditions--in
+the most general meaning of the word--we only follow the opinion
+which has almost universally been adopted by the biologists[139] that
+are working at this branch of the subject. Variation proper is now
+generally allowed to be the consequence of variations in nutrition;
+the contingencies of the latter result in contingencies of the former,
+and the law of contingencies is the same for both, being the most
+general law of probability. Of course under such an aspect fluctuating
+variation could hardly be called an exception, but rather an addition to
+inheritance.
+
+[138] H. M. Vernon, *Variations in Animals and Plants*, London, 1903.
+
+[139] De Vries, *Die Mutationstheorie*, i., 1901; and Klebs, *Jahrb.
+wiss. Bot.* 42, 1905.
+
+But there are other restrictions of our definition of heredity. The
+initial stage which is formed again by an organism is not always quite
+identical in itself with the initial stage of its own parent: Bateson
+and de Vries were the first to study in a systematic way these real
+exceptions[140] to true inheritance. As you know, de Vries has given
+them the name of “mutations.” What is actually known on this subject is
+not much at present, but nevertheless is of great theoretical value,
+being the only real foundation of all theories of descent, as we shall
+see in the next lectures. “Mutations” are known to exist at present only
+among some domesticated animals and plants. Nothing of a more general
+character can be said about their law or meaning.[141]
+
+[140] They would not be “real exceptions” if Klebs (*Arch. Entw. Mech.*
+24, 1907) were right in saying that both variations and mutations owe
+their existence to external agents. What is really *proved* by Klebs
+is the possibility of changing the *type* of a curve of variation and
+of provoking certain discontinuous varieties by external means. See
+also Blaringhem (*Comptes rend.* 1905-6, and *Soc. de Biol.* 59, 1905),
+and MacDougal (*Rep. Depart. Bot. Res., 5th Year-book Carnegie Inst.*,
+Washington, 129).
+
+[141] H. de Vries, *Species and Varieties: their Origin by Mutation*,
+London, 1905. A short review of the “mutation-theory” is given by Francé
+in *Zeitschrift f. d. Ausbau d. Entwickelungslehre*, i. 1907. It is well
+known that Gautier, and, in the first place, Korshinsky, advocated a
+similar view previous to the authors named in the text.
+
+
+
+
+CONCLUSIONS FROM THE FIRST MAIN PART OF THESE LECTURES
+
+
+In finishing our chapter on inheritance, we at the same time have
+finished the first main part of our lectures; that part of them which
+has been devoted exclusively to the study of the morphogenesis of the
+*individual*, including the functioning of the adult individual form.
+We now turn to our second part, which is to deal with the problems of
+the diversities of individual forms, with morphological systematics. The
+end of our chapter on inheritance has already led us to the threshold of
+this branch of biological science.
+
+The chief result of the first main part of our lectures has been to
+prove that an autonomy of life phenomena exists at least in some
+departments of individual morphogenesis, and probably in all of them;
+the real starting-point of all morphogenesis cannot be regarded as a
+machine, nor can the real process of differentiation, in all cases where
+it is based upon systems of the harmonious equipotential type. There
+cannot be any sort of machine in the cell from which the individual
+originates, because this cell, including both its protoplasm and its
+nucleus, has undergone a long series of divisions, all resulting in
+equal products, and because a machine cannot be divided and in spite of
+that remain what it was. There cannot be, on the other hand, any sort
+of machine as the real foundation of the whole of an harmonious system,
+including many cells and many nuclei, because the development of this
+system goes on normally, even if its parts are rearranged or partly
+removed, and because a machine would never remain what it had been in
+such cases.
+
+If our analytical discussions have thus led us to establish a typical
+kind of vitalism, it follows that we can by no means agree with Wilhelm
+Roux in his denomination of the analytical science of the individual
+form and form-production as “Entwickelungsmechanik,” “developmental
+mechanics,” a title, which, of course, might easily be transformed
+into that of “morphogenetic mechanics,” to embrace not only normal
+development, but restitution and adaptation too. We feel unable to speak
+of “mechanics” where just the contrary of mechanics, in the proper
+meaning of the word, has been proved to exist.
+
+Names of course are of comparatively small importance, but they
+should never be allowed to be directly misleading, as indeed the term
+“Entwickelungsmechanik” has already proved to be. Let us rather say,
+therefore, that we have finished with this lecture that part of our
+studies in biology which has had to deal with morphogenetic physiology
+or physiological morphogenesis.
+
+Once more we repeat, at this resting-point in our discussions, that both
+of our proofs of life-autonomy have been based upon a careful analysis
+of certain facts about the distribution of morphogenetic potencies in
+two classes of morphogenetic systems, and upon nothing else. To recall
+only one point, we have not said that regeneration, merely because it
+is a kind of restitution of the disturbed whole, compels us to admit
+that biological events happen in a specific and elemental manner, but,
+indeed, regeneration *does* prove vitalism, because it is founded upon
+the existence of certain complex-equipotential systems, the analysis of
+the genesis of which leads to the understanding of life-autonomy. This
+distinction, in fact, is of the greatest logical importance.
+
+
+
+
+PART II
+
+SYSTEMATICS AND HISTORY
+
+*A.* THE PRINCIPLES OF SYSTEMATICS
+
+
+RATIONAL SYSTEMATICS
+
+All systematics which deserves the predicate “rational” is founded
+upon a concept or upon a proposition, by the aid of which a totality
+of specific diversities may be understood. That is to say: every
+system claiming to be rational gives us a clue by which we are able to
+apprehend either that there cannot exist more than a certain number of
+diversities of a certain nature, or that there can be an indefinite
+number of them which follow a certain law with regard to the character
+of their differences.
+
+Solid geometry, which states that only five regular bodies are possible,
+and points out the geometrical nature of these bodies, is a model
+of what a rational system should be. The theory of conic sections
+is another. Take the general equation of the second degree with two
+unknowns, and study all the possible forms it can assume by a variation
+of its constants, and you will understand that only four different types
+of conic sections are possible--the circle, the ellipse, the hyperbola,
+and the parabola.
+
+In physics and chemistry no perfect rational systems have been
+established hitherto, but there are many systems approaching the ideal
+type in different departments of these sciences. The chemical type of
+the monohydric saturated alcohols, for instance, is given by the formula
+C_nH_{2n+1}OH, and in this formula we not only have an expression of
+the law of composition which all possible alcohols are to follow,--but,
+since we know empirically the law of quantitative relation between
+*n* and various physical properties, we also possess in our formula a
+general statement with respect to the totality of the properties of any
+primary alcohol that may be discovered or prepared in the future. But
+chemistry has still higher aims with regard to its systematics: all of
+you know that the so-called “periodic law of the elements” was the first
+step towards a principle that may some day give account of the relation
+of all the physical and chemical properties of any so-called element
+with its most important constant, the atomic weight, and it seems to be
+reserved for the present time to form a real fundamental system of the
+“elements” on the basis of the periodic law by the aid of the theory
+of electrons. Such a fundamental system of the elements would teach us
+that there can only be so many elements and no more, and only of such a
+kind. In crystallography a similar end has been reached already by means
+of certain hypothetic assumptions, and systematics has here accounted
+for the limited number and fixed character of the possible forms of
+crystalline symmetry.
+
+It is not difficult to understand the general logical type of all
+rational systems, and logic indeed can discover it without appealing
+to concrete sciences or to geometry. Rational systematics is always
+possible whenever there exists any fundamental concept or proposition
+which carries with it a principle of division; or to express it somewhat
+differently, which would lead to contradictions, if division were to
+be tried in any but one particular manner. The so-called “genus,” as
+will easily be perceived, then embraces all its “species” in such a
+manner that all peculiarities of the species are represented already in
+properties of the genus, only in a more general form, in a form which
+is still unspecified. The genus is both richer in content and richer in
+extent than are the species, though it must be added that its richness
+in content is, as it were, only latent: but it may come into actuality
+by itself and without any help from without.
+
+We are dealing here with some of the most remarkable properties of the
+so-called synthetic judgments *a priori* in the sense of Kant, and,
+indeed, it seems that rational systematics will only be possible where
+some concept of the categorical class or some proposition based upon
+such concept lies at the root of the matter or at least is connected
+with it in some way. In fact, all rational systems with regard to the
+relations of symmetry in natural bodies deal ultimately with space; or
+better, all systems in such fields are able to become rational only if
+they happen to turn into questions of spatial symmetry.
+
+All other genera and species, whether of natural bodies or of facts,
+can be related only on the basis of empirical abstraction, *i.e.* can
+never attain rationality: here, indeed, the genus is richer in extent
+and poorer in content than are the species. The genus is transformed
+into the species, not by any inherent development of latent properties,
+but by a mere process of addition of characteristic points. It is
+impossible to deduce the number or law or specifications of the species
+from the genus. Mere “classification,” if we may reserve the honorable
+name of systematics for the rational type, is possible here, a mere
+statement in the form of a catalogue, useful for orientation but for
+nothing more. We may classify all varieties of hats or of tables in the
+same way.
+
+
+BIOLOGICAL SYSTEMATICS
+
+At this point we return from our logical excursion to our proper subject
+of biology; for I am sorry to say biological systematics is at present
+of our second type of systematics throughout: it is classification pure
+and simple. We have a catalogue in our hands, but nothing more.
+
+Such a statement of fact conveys not a particle of censure, casts not
+the least reflection on the gifted men who created the classification of
+animals or plants. It is absolutely necessary to have such a catalogue,
+and indeed the catalogue of the organisms can be said to have been
+improved enormously during the advance of empirical and descriptive
+biological science. Any classification improves as it becomes more
+“natural,” as the different possible schemes of arrangement, the
+different reasons of division, agree better and better in their results;
+and, in fact, there has been a great advance of organic classification
+in this direction. The “natural” system has reached such perfection,
+that what is related from one point of view seems nearly related also
+from almost all points of view which are applicable, at least from those
+which touch the most important characteristics. There has been a real
+weighing of all the possible reasons of division, and that has led to a
+result which seems to be to some extent final.
+
+But, nevertheless, we do not understand the *raison d’être* of the
+system of organisms; we are not at all able to say that there must be
+these classes or orders or families and no others, and that they must be
+such as they are.
+
+Shall we ever be able to understand that? Or will organic systematics
+always remain empirical classification? We cannot answer this question.
+If we could, indeed, we should have what we desire! As simple relations
+of space are certainly not the central point of any problematic rational
+organic systematics even of the future, the question arises, whether
+there could be found any principle of another type in the realm of
+synthetic *a priori* judgments which could allow an inherent sort of
+evolution of latent diversities, as do all judgments about spatial
+symmetry. At the end of the second course of these lectures, which is to
+be delivered next summer, we shall be able to say a few more words about
+this important point.
+
+The concept of what is called “a type,” due almost wholly to Cuvier and
+Goethe, is the most important of all that classification has given to
+us. Hardly second in importance is the discovery of the “correlation of
+parts,” as a sort of connection which has the character of necessity
+without being immediately based upon causality. Rádl seems to be
+the only modern author who has laid some stress on this topic. The
+harmony which we have discovered in development is also part of this
+correlation. When, later on, we come to discuss analytically our well
+established entelechy as the ultimate basis of individual organisation,
+we shall be able to gain more satisfactory ideas with respect to the
+meaning of the non-causal but necessary connection, embraced in the
+concepts of type and of correlation of parts.
+
+The type is a sort of irreducible arrangement of different parts; the
+correlation deals with the degree and the quality of what may be called
+the actual make of the parts, in relation to one another: all ruminants,
+for instance, are cloven-footed, the so-called dental formulae are
+characteristic of whole groups of mammals. Of course all such statements
+are empirical and have their limits: but it is important that they are
+possible.[142]
+
+[142] Recent years have created the beginnings of a systematics based on
+chemical differences of metabolism and its products: such differences in
+fact have been found to go hand in hand with diversities of the type in
+some cases (v. Bunge, Przibram, etc.).
+
+It has been the chief result of comparative embryology to show that the
+type as such is more clearly expressed in developmental stages than
+it is in the adults, and that therefore the embryological stages of
+different groups may be very much more similar to each other than are
+the adults: that is the truth contained in the so-called “biogenetisches
+Grundgesetz.” But the specific differences of the species are not
+wanting in any case of ontogeny, in spite of such similarities in
+different groups during development.
+
+We have applied the name “systematics” or, if rationality is excluded,
+“classification” to all that part of a science which deals with
+diversities instead of generalities: in such a wide meaning systematics,
+of course, is not to be confused with that which is commonly called so
+in biology, and which describes only the exterior differences of form.
+Our systematics is one of the two chief parts of biology; what are
+called comparative anatomy and comparative embryology are its methods.
+For it must be well understood that these branches of research are only
+methods and are not sciences by themselves.
+
+
+
+
+*B.* THE THEORY OF DESCENT
+
+
+1. GENERALITIES
+
+It is most generally conceded at the present time that the actually
+existing state of all organisms whatsoever is the result of their
+history. What does that mean? What are the foundations upon which the
+assumption rests? What is the relation of systematics to history? In
+raising such questions and considerations we are treading the ground
+sacred to the theory of descent.
+
+I well know that you prefer the name “theory of evolution” for what
+I am speaking of: but it may be misleading in various respects. We
+already know that quite a determinate meaning has been given to the word
+“evolutio” as applied to individual morphogenesis, “evolutio” being
+here opposed to “epigenesis.” Now there would be nothing against the
+use of the word evolution in a wider sense--indeed it is often applied
+nowadays to denote the fact that a something is actually “evolved” in
+embryology--if only our entelechy had taken the place of the machine
+of the mechanists. But that is the very point: there must be a real
+“evolving” of a something, in order that the word evolution may be
+justified verbally: and that is not the case in so-called phylogeny. At
+least we know nothing of an evolutionary character in the problematic
+pedigree of the organisms, as we shall see more fully hereafter. The
+term “theory of descent” is therefore less open to objection than is the
+usual English term. The word transformism, as used by the French, would
+also be a very good title.
+
+The theory of descent is the hypothetic statement that the organisms
+are really allied by blood among each other, in spite of their
+diversities.[143] The question about their so-called monophyletic
+or polyphyletic origin is of secondary importance compared with the
+statement of relationship in general.
+
+[143] We prefer this unpretending definition of the theory of descent
+to every other. As soon as one introduces into the definition the
+concept of the “transmutability of species,” the term “species” would
+require a special definition, and that would lead to difficulties which
+it is unnecessary to deal with for our main purposes. It has been
+remarked by Krašan, (*Ausichten und Gespräche über die individuelle und
+specifische Gestaltung in der Natur*) and by several other writers,
+that the problem of mutability or immutability of course relates to the
+individuals in the first place. I should like to add to this remark that
+the possibility must be admitted of the individuals being transmutable,
+whilst the “species” are not transmutable at the same time, the line
+of the “species” being a fixed order, through which the “individuals”
+have to pass in the course of their generations. What is meant here
+will become clearer, when we study the different possible aspects of
+“phylogeny.”
+
+There are two different groups of facts which have suggested the idea
+of transformism: none of these facts can be said to be conclusive, but
+there certainly is a great amount of probability in the whole if taken
+together.
+
+The first group of evidences which lead to the hypothesis of the real
+relationship of organisms consists of facts relating to the geographical
+distribution of animals and plants and to palæontology. As to geography,
+it seems to me that the results of the floral and faunal study of groups
+of islands are to be mentioned in the first place. If, indeed, on
+each of the different islands, *A* *B* *C* and *D*, forming a group,
+the species of a certain genus of animals or plants are different in a
+certain respect, and show differences also compared with the species
+living on the neighbouring continent, of which there is geological
+evidence that the islands once formed a part, whilst there is no change
+in the species on the continent itself for very wide areas, then, no
+doubt, the hypothesis that all these differing species once had a common
+origin, the hypothesis that there is a certain community among them all,
+will serve to elucidate in some way what would seem to be very abstruse
+without it. And the same is true of the facts of palaeontology. In
+the geological strata, forming a continuous series, you find a set of
+animals, always typical and specific for every single stratigraphical
+horizon, but forming a series just as do those horizons. Would not the
+whole aspect of these facts lose very much of its peculiarity if you
+were to introduce the hypothesis that the animals changed with the
+strata? The continuity of life, at least, would be guaranteed by such an
+assumption.
+
+The geographical and geological evidences in favour of the theory of
+descent are facts taken from sciences which are not biology proper; they
+are not facts of the living but only facts about the living. That is not
+quite without logical importance, for it shows that not biology alone
+has led to the transformism hypothesis. Were it otherwise, transformism
+might be said to be a mere hypothesis *ad hoc*; but now this proves to
+be not the case, though we are far from pretending that transformism
+might be regarded as resting upon a real *causa vera*.
+
+But let us study the second group of facts which support the theory of
+descent. It is a group of evidences supplied by biology itself that we
+meet here, there being indeed some features in biology which can be
+said to gain some light, some sort of elucidation, if the theory of
+descent is accepted. Of course, these facts can only be such as relate
+to specific diversities, and indeed are facts of systematics; in other
+words, there exists something in the very nature of the system of
+organisms that renders transformism probable. The system of animals and
+plants is based upon a principle which might be called the principle
+of *similarities and diversities by gradation*; its categories are not
+uniform but different in degree and importance, and there are different
+kinds of such differences. No doubt, some light would be shed upon this
+character of the system, if we were allowed to assume that the relation
+between similarities and diversities, which is gradual, corresponded to
+a blood-relationship, which is gradual also.
+
+
+THE COVERT PRESUMPTION OF ALL THEORIES OF DESCENT
+
+We have used very neutral and somewhat figurative words, in order to
+show what might be called the logical value of the theory of descent,
+in order to signify its value with respect to so-called “explanation.”
+We have spoken of the “light” or the “elucidation” which it brings, of
+the “peculiarity of aspect” which is destroyed by it. We have used this
+terminology intentionally, for it is very important to understand that
+a specific though hidden addition is made almost unconsciously to the
+mere statement of the hypothesis of descent as such, whenever this
+hypothesis is advocated in order to bring light or elucidation into any
+field of systematic facts. And this additional hypothesis indeed must be
+made from the very beginning, quite irrespective of the more detailed
+problems of the law of transformism, in order that *any* sort of
+so-called explanation by means of the theory of descent may be possible
+at all. Whenever the theory that, in spite of their diversities, the
+organisms are related by blood, is to be really useful for explanation,
+it must necessarily be assumed in every case that the steps of change,
+which have led the specific form *A* to become the specific form *B*,
+have been such as only to change *in part* that original form *A*. That
+is to say: the similarities between *A* and *B* must never have become
+overshadowed by their diversities.
+
+Only on this assumption, which indeed is a newly formed additional
+subsidiary hypothesis, joined to the original hypothesis of descent in
+general--a hypothesis regarding the very nature of transformism--only
+on this almost hidden assumption is it possible to speak of any sort of
+“explanation” which might be offered by the theory of transformism to
+the facts of geography, geology, and biological systematics. Later on
+we shall study more deeply the logical nature of this “explanation”; at
+present it must be enough to understand this term in its quasi-popular
+meaning.
+
+What is explained by the hypothesis of descent--including the additional
+hypothesis, that there always is a prevalence of the similarities
+during transformism--is the fact that in palaeontology, in the groups
+of island and continent faunae and florae taken as a whole, as well as
+in the single categories of the system, the similarities exceed the
+diversities. The *similarities* now are “explained”; that is to say,
+they are understood as resting on but one principle: the similarities
+are understood as being due to inheritance;[144] and now we have but one
+problem instead of an indefinite number. For this reason Wigand granted
+that the theory of descent affords what he calls a numerical reduction
+of problems.
+
+[144] It seems to me that my argument gives a broader logical basis
+to the theory of descent than does that of G. Wolff (*Die Begründung
+der Abstammungslehre*, München, 1907). Wolff starts from the concept
+of organic teleology, and thus finds the only reason for accepting
+the theory of transformism in the existence of so-called “rudimentary
+organs”; these organs would form an obstacle to teleology if they could
+not be regarded as inherited.
+
+Understanding then what is explained by the theory of descent with its
+necessary appendix, we also understand at once what is *not* elucidated
+by it: the diversities of the organism remain as unintelligible as they
+always were, even if we know that inheritance is responsible for what
+is similar or equal. Now there can be no doubt that the diversities are
+the more important point in systematics; if there were only similarities
+there would be no problem of systematics, for there would be no system.
+Let us be glad that there are similarities in the diversities, and that
+these similarities have been explained in some way; but let us never
+forget what is still awaiting its explanation. Unfortunately it has been
+forgotten far too often.
+
+
+THE SMALL VALUE OF PURE PHYLOGENY
+
+And so we are led to the negative side of the theory of transformism,
+after having discussed its positive half. The theory of descent as
+such, without a real knowledge of the factors which are concerned in
+transformism, or of the law of transformism, in other terms, leaves the
+problem of systematics practically where it was, and adds really nothing
+to its solution. That may seem very deplorable, but it is true.
+
+Imagine so-called historical geology, without any knowledge of the
+physical and chemical factors which are concerned in it: what would
+you have except a series of facts absolutely unintelligible to you? Or
+suppose that some one stated the cosmogenetic theory of Kant and Laplace
+without there being any science of mechanics: what would the theory mean
+to you? Or suppose that the whole history of mankind was revealed to
+you, but that you had absolutely no knowledge of psychology: what would
+you have but facts and facts and facts again, with not a morsel of real
+explanation?
+
+But such is the condition in which so-called phylogeny stands. If it
+is based only on the pure theory of transformism, there is nothing
+explained at all. It was for this reason that the philosopher Liebmann
+complained of phylogeny that it furnishes nothing but a “gallery of
+ancestors.” And this gallery of ancestors set up in phylogeny is not
+even certain; on the contrary, it is absolutely uncertain, and very
+far from being a fact. For there is no sound and rational principle
+underlying phylogeny; there is mere fantastic speculation. How could it
+be otherwise where all is based upon suppositions which themselves have
+no leading principle at present? I should not like to be misunderstood
+in my polemics against phylogeny. I fully grant you that it may be
+possible in a few cases to find out the phylogenetic history of smaller
+groups with some probability, if there is some palaeontological
+evidence in support of pure comparative anatomy; and I also do not
+hesitate to allow that such a statement would be of a certain value with
+regard to a future discovery of the “laws” of descent, especially if
+taken together with the few facts known about mutations. But it is quite
+another thing with phylogeny on the larger scale. Far more eloquent than
+any amount of polemics is the fact that vertebrates, for instance, have
+already been “proved” to be descended from, firstly, the amphioxus;
+secondly, the annelids; thirdly, the *Sagitta* type of worms; fourthly,
+from spiders; fifthly, from *Limulus*, a group of crayfishes; and
+sixthly, from echinoderm larvae. That is the extent of my acquaintance
+with the literature, with which I do not pretend to be specially
+familiar. Emil du Bois-Reymond said once that phylogeny of this sort is
+of about as much scientific value as are the pedigrees of the heroes of
+Homer, and I think we may fully endorse his opinion on this point.
+
+
+HISTORY AND SYSTEMATICS
+
+A few words should be devoted to the relations between history and
+systematics in biology. Is there no contradiction between historical
+development and a true and rational system which, we conceded, might
+exist some day in biological sciences, even though it does not at
+present? By no means. A totality of diversities is regarded from quite
+different points of view if taken as the material of a system, and if
+considered as realised in time. We have said that chemistry has come
+very near to proper rational systematics, at least in some of its
+special fields; but the compounds it deals with at the same time may
+be said to have originated historically also, though not, of course,
+by a process of propagation. It is evident at once that the geological
+conditions of very early times prohibited the existence of certain
+chemical compounds, both organic and inorganic, which are known at
+present. None the less these compounds occupy their proper place in
+the system. And there may be many substances theoretically known to
+chemical systematics which have never yet been produced, on account
+of the impossibility of arranging for their proper conditions of
+appearance, and nevertheless they must be said to “exist.” “Existence,”
+as understood in systematics, is independent of special space and of
+special time, as is the existence of the laws of nature: we may speak of
+a Platonic kind of existence here. Of course it does not contradict this
+sort of ideal existence if reality proper is added to it.
+
+Thus the problem of systematics remains, no matter whether the theory
+of descent be right or wrong. There always remains the question about
+the totality of diversities in life: whether it may be understood by
+a general principle, and of what kind that principle would be. As,
+in fact, it is most probably by history, by descent, that organic
+systematics is brought about, it of course most probably will happen
+some day that the analysis of the causal factors concerned in the
+history will serve to discover the principle of systematics also.
+
+Let us now glance at the different kinds of hypotheses which have been
+established in order to explain how the descent of the organisms might
+have been possible. We have seen that the theory of transformism alone
+is not worth very much as a whole, unless at least a hypothetical
+picture can be formed of the nature of the transforming factors: it is
+by some such reasoning that almost every author who has defended the
+theory of descent in its universality tries to account for the manner in
+which organisms have acquired their present diversities.
+
+
+2. THE PRINCIPLES OF DARWINISM
+
+There is no need in our times and particularly in this country, to
+explain in a full manner the theory known under the name of Darwinism.
+All of you know this theory, at least in its outlines, and so we may
+enter at once upon its analytic discussion. A few words only I beg
+you to allow me as to the name of “Darwinism” itself. Strange to say,
+Darwinism, and the opinion of Charles Darwin about the descent of
+organisms, are two different things. Darwin, the very type of a man
+devoted to science alone and not to personal interests,--Darwin was
+anything but dogmatic, and yet Darwinism is dogmatism in one of its
+purest forms. Darwin, for instance, gave the greatest latitude to the
+nature of the variations which form the battleground of the struggle
+for existence and natural selection; and he made great allowances for
+other causal combinations also, which may come into account besides
+the indirect factors of transformism. He was Lamarckian to a very
+far-reaching extent. And he had no definite opinion about the origin
+and the most intimate nature of life in general. These may seem to
+be defects but really are advantages of his theory. He left open the
+question which he could not answer, and, in fact, he may be said to be a
+good illustration of what Lessing says, that it is not the possession
+of truth but the searching after it, that gives happiness to man. It was
+but an outcome of this mental condition that Darwin’s polemics never
+left the path of true scientific discussions, that he never in all his
+life abused any one who found reason to combat his hypotheses, and that
+he never turned a logical problem into a question of morality.
+
+How different is this from what many of Darwin’s followers have made out
+of his doctrines, especially in Germany; how far is “Darwinism” removed
+from Darwin’s own teaching and character!
+
+It is to Darwinism of the *dogmatic* kind, however, that our next
+discussions are to relate, for, thanks to its dogmatism, it has the
+advantage of allowing the very sharp formulation of a few causal
+factors, which *a priori* might be thought to be concerned in organic
+transformism, though we are bound to say that a really searching
+analysis of these factors ought to have led to their rejection from the
+very beginning.
+
+The logical structure of dogmatic Darwinism reveals two different parts,
+which have nothing at all to do with one another.
+
+
+NATURAL SELECTION
+
+We shall first study that part of it which is known under the title
+of natural selection, irrespective of the nature of the causes of
+primary differences, or, in other words, the nature of variability.
+This part may be said to belong to Darwin’s personal teachings and not
+only to “Darwinism.” The offspring of a certain number of adults show
+differences compared with each other; there are more individuals in the
+offspring than can grow up under the given conditions, therefore there
+will be a struggle for existence amongst them, which only the fittest
+will survive; these survivors may be said to have been “selected” by
+natural means.
+
+It must be certain from the very beginning of analysis that natural
+selection, as defined here, can only eliminate what cannot survive, what
+cannot stand the environment in the broadest sense, but that natural
+selection never is able to create diversities. It always acts negatively
+only, never positively. And therefore it can “explain”--if you will
+allow me to make use of this ambiguous word--it can “explain” only why
+certain types of organic specifications, imaginable *a priori*, do
+*not* actually exist, but it never explains at all the existence of the
+specifications of animal and vegetable forms that are actually found. In
+speaking of an “explanation” of the origin of the living specific forms
+by natural selection one therefore confuses the sufficient reason for
+the non-existence of what there is not, with the sufficient reason for
+the existence of what there is. To say that a man has explained some
+organic character by natural selection is, in the words of Nägeli, the
+same as if some one who is asked the question, “Why is this tree covered
+with these leaves,” were to answer “Because the gardener did not cut
+them away.” Of course that would explain why there are no more leaves
+than those actually there, but it never would account for the existence
+and nature of the existing leaves as such. Or do we understand in the
+least why there are white bears in the Polar Regions if we are told that
+bears of other colours could not survive?
+
+In denying any real explanatory value to the concept of natural
+selection I am far from denying the action of natural selection. On
+the contrary, natural selection, to some degree, is *self-evident*;
+at least as far as it simply states that what is incompatible with
+permanent existence cannot exist permanently, it being granted that
+the originating of organic individuals is not in itself a guarantee of
+permanency. Chemical compounds, indeed, which decompose very rapidly
+under the conditions existing at the time when they originated may also
+be said to have been eliminated by “natural selection.” It is another
+question, of course, whether in fact all eliminations among organic
+diversities are exclusively due to the action of natural selection in
+the proper Darwinian sense. It has been pointed out already by several
+critics of Darwinism and most clearly by Gustav Wolff, that there are
+many cases in which an advantage with regard to situation will greatly
+outweigh any advantage in organisation or physiology. In a railway
+accident, for instance, the passengers that survive are not those who
+have the strongest bones, but those who occupied the best seats; and
+the eliminating effect of epidemics is determined at least as much by
+localities, *e.g.* special houses or special streets, as by the degree
+of immunity. But, certainly, natural selection is a *causa vera* in many
+other cases.
+
+We now may sum up our discussion of the first half of Darwinism.
+Natural selection is a negative, an eliminating factor in transformism;
+its action is self-evident to a very large degree, for it simply
+states that things do not exist if their continuance under the given
+conditions is impossible. To consider natural selection as a positive
+factor in descent would be to confound the sufficient reason for the
+non-existence of what is not, with the sufficient reason of what is.
+
+Natural selection has a certain important logical bearing on
+systematics, as a science of the future, which has scarcely ever been
+alluded to. Systematics of course has to deal with the totality of the
+possible, not only of the actual diversities; it therefore must remember
+that more forms may be possible than are actual, the word “possible”
+having reference in this connection to originating, not to surviving.
+Moreover, systematics is concerned not only with what has been
+eliminated by selection, but also with all that might have originated
+from the eliminated types. By such reasoning natural selection gains a
+very important aspect--but a logical aspect only.
+
+
+FLUCTUATING VARIATION THE ALLEGED CAUSE OF ORGANIC DIVERSITY
+
+The second doctrine of dogmatic Darwinism states that all the given
+diversities among the organisms that natural selection has to work
+upon are offered to natural selection by so-called fluctuating
+variation; that is, by variation as studied by means of statistics.
+This sort of variation, indeed, is maintained to be indefinite in
+direction and amount, at least by the most conservative Darwinians; it
+has occasionally been called a real differential; in any case it is
+looked upon as being throughout contingent with regard to some unity
+or totality; which, of course, is not to mean that it has not had a
+sufficient reason for occurring.
+
+It could hardly be said to be beyond the realm of possibility that such
+differences among organic species as only relate to degree or quantity
+and perhaps to numerical conditions also, might have been “selected” out
+of given contingent variations, if but one postulate could be regarded
+as fulfilled. This postulate may appropriately be stated as the fixation
+of new averages of variation by inheritance. Let the average value of
+a variation, with regard to a given property of a given species be *n*
+and let the value *n* + *m*--*m* being variable--which is represented in
+fewer individuals of course than is *n*, be such as to offer advantages
+in the struggle for existence; then the individuals marked by *n* + *m*
+will have the greater chance of surviving. Our postulate now states
+that, in order that a permanent increase of the average value of the
+variation in question may be reached, *n* + *m* in any of its variable
+forms must be able to become the average value of the second generation,
+as *n* was the average value of the first. Out of the second generation
+again it would be the few individuals marked by *n* + *m* + *o*, which
+would be selected; *n* + *m* + *o* would be the new average; afterwards
+*n* + *m* + *o* + *p* would be selected, would become the new average,
+and so on. A black variety for instance might be selected by such a
+series of processes out of a grey-coloured one without difficulty.
+
+But our postulate is not beyond all doubt: certain experiments, at
+least, which have been carried out about the summation of variations
+of the true fluctuating type by any kind of selection seem to show
+that there may be a real progress for a few generations, but that this
+progress is always followed by a reversion. Of course our experience
+is by no means complete on this subject, and, indeed, it may be shown
+in the future that positive transforming effects of fluctuating
+variability, in connection with selective principles, are possible in
+the case of new quantitative differences (in the widest sense), but we
+are not entitled to say so at present.
+
+And this is the only condition on which we can give credit to the second
+doctrine of dogmatic Darwinism. Its second principle, indeed, proves
+to be absolutely inadequate to explain the origin of any other kind of
+specific properties whatever.
+
+I cannot enter here into the whole subject of Darwinian criticism.[145]
+Our aims are of a positive character, they desiderate construction
+and only use destruction where it is not to be avoided. So I shall
+only mention that dogmatic Darwinism has been found to be unable to
+explain every kind of mutual adaptations, *e.g.* those existing between
+plants and insects; that it can never account for the origin of those
+properties that are indifferent to the life of their bearer, being mere
+features of organisation as an arrangement of parts; that it fails in
+the face of all portions of organisation which are composed of many
+different parts--like the eye--and nevertheless are functional units
+in any passive or active way; and that, last not least, it has been
+found to be quite inadequate to explain the first origin of all newly
+formed constituents of organisation even if they are not indifferent:
+for how could any rudiment of an organ, which is not functioning at all,
+not only be useful to its bearer, but be useful in such a degree as to
+decide about life or death?
+
+[145] See Wigand, *Der Darwinismus und die Naturforschung Newton’s und
+Cuvier’s*, Braunschweig, 1874-7; Nägeli, *Mechanisch-physiologische
+Theorie der Abstammungslehre*, München, 1884; G. Wolff, *Beiträge zur
+Kritik der Darwin’schen Lehre*, 2nd ed. Leipzig, 1898; etc.
+
+It is only for one special feature that I should like to show, by
+a more full analysis, that dogmatic Darwinism does not satisfy the
+requirements of the case. The special strength of Darwinism is said to
+lie in its explaining everything that is useful in and for organisms;
+the competitive factor it introduces does indeed seem to secure at least
+a relative sort of adaptedness between the organism and its needs. But
+in spite of that, we shall now see that Darwinism fails absolutely to
+explain those most intimate organic phenomena which may be said to be
+the most useful of all.
+
+Darwinism in its dogmatic form is not able to explain the origin of any
+sort of organic restitution; it is altogether impossible to account for
+the restitutive power of organisms by the simple means of fluctuating
+variation and natural selection in the struggle for existence. Here we
+have the logical *experimentum crucis* of Darwinism.
+
+Let us try to study in the Darwinian style the origin of the
+regenerative faculty, as shown in the restitution of the leg of a
+newt. All individuals of a given species of the newt, say *Triton
+taeniatus*, are endowed with this faculty; all of them therefore must
+have originated from ancestors which acquired it at some time or other.
+But this necessary supposition implies that all of these ancestors must
+have lost their legs in some way, and not only one, but all four of
+them, as they could not have acquired the restitutive faculty otherwise.
+We are thus met at the very beginning of our argument by what must be
+called a real absurdity, which is hardly lessened by the assumption that
+regeneration was acquired not by all four legs together, but by one
+after the other. But it is absolutely inevitable to assume that *all*
+the ancestors of our *Triton* must have lost one leg, or more correctly,
+that only those of them survived which had lost one! Otherwise not all
+newts at the present day could possess the faculty of regeneration! But
+a second absurdity follows the first one; out of the ancestors of our
+newt, which survived the others by reason of having lost one of their
+legs, there were selected only those which showed at least a very small
+amount of healing of their wound. It must be granted that such a step
+in the process of selection, taken by itself, would not at all seem to
+be impossible; since healing of wounds protects the animals against
+infection. But the process continues. In every succeeding stage of it
+there must have survived only those individuals which formed just a
+little more of granulative tissue than did the rest: though *neither*
+they themselves *nor* the rest could use the leg, which indeed was
+not present! That is the second absurdity we meet in our attempt at a
+Darwinian explanation of the faculty of regeneration; but I believe the
+first one alone was sufficient.
+
+If we were to study the “selection” of the faculty of one of the
+isolated blastomeres of the egg of the sea-urchin to form a whole larva
+only of smaller size, the absurdities would increase. At the very
+beginning we should encounter the absurdity, that of all the individuals
+there survived only those which were not whole but half; for *all*
+sea-urchins are capable of the ontogenetical restitution in question,
+*all* of their ancestors therefore must have acquired it, and they
+could do that only *if* they became halved at first by some accident
+during early embryology. But we shall not insist any further on this
+instance, for it would not be fair to turn into ridicule a theory which
+bears the name of a man who is not at all responsible for its dogmatic
+form. Indeed, we are speaking against Darwinism of the most dogmatic
+form only, not against Darwin himself. He never analysed the phenomena
+of regeneration or of embryonic restitution--they lay in a field very
+unfamiliar to him and to his time. I venture to say that if he had taken
+them into consideration, he would have agreed with us in stating that
+his theory was not at all able to cover them; for he was prepared to
+make great concessions, to Lamarckism for instance, in other branches of
+biology, and he did not pretend, to know what life itself is.
+
+Darwin was not a decided materialist, though materialism has made
+great capital out of his doctrines, especially in Germany. His book,
+as is well known, is entitled “The Origin of *Species*,” that is of
+organic *diversities*, and he himself possibly might have regarded all
+restitution as belonging to the original properties of life, anterior to
+the originating of diversities. Personally he might possibly be called
+even a vitalist. Thus dogmatic “Darwinism” in fact is driven into all
+the absurdities mentioned above, whilst the “doctrine of Darwin” can
+only be said to be wrong on account of its failing to explain mutual
+adaptation, the origin of new organs, and some other features in organic
+diversities; the original properties of life were left unexplained by it
+intentionally.
+
+
+DARWINISM FAILS ALL ALONG THE LINE
+
+The result of our discussion then must be this: selection has proved to
+be a negative factor only, and fluctuating variation as the only way
+in which new properties of the organisms might have arisen has proved
+to fail in the most marked manner, except perhaps for a few merely
+quantitative instances. Such a result betokens the complete collapse
+of dogmatic Darwinism as a general theory of descent: the most typical
+features of all organisms remain as unexplained as ever.
+
+What then shall we put in the place of pure Darwinism? Let us first try
+a method of explanation which was also adopted occasionally by Darwin
+himself: let us study that form of transformation theories which is
+commonly known under the title of Lamarckism.
+
+
+3. THE PRINCIPLES OF LAMARCKISM.
+
+As the word “Darwinism” does not signify the proper theoretical system
+of Charles Darwin, so Lamarckism as commonly understood nowadays is a
+good deal removed from the original views of Jean Baptiste Lamarck.
+Lamarckism is generally regarded as reducing all organic diversities to
+differences in the needs of individual life, but Lamarck himself, as
+must be emphasised from the very beginning, did not at all maintain the
+opinion that the great characteristics of the types were only due to
+such accidental factors. He supposed a sort of law of organisation to
+be at the root of systematics, as developed in history, and the needs
+of life were only responsible, according to him, for splitting the
+given types of organisation into their ultimate branches. Thus Lamarck,
+to a great extent at any rate, belongs to a group of authors that we
+shall have to study afterwards: authors who regard an unknown law of
+phylogenetic development as the real basis of transformism. Modern
+so-called Neo-Lamarckism, on the other hand, has indeed conceded the
+principle of needs to be the sole principle of transformism. Let us then
+study Lamarckism in its dogmatic modern form.
+
+
+ADAPTATION AS THE STARTING-POINT
+
+All facts of morphological adaptations--facts which we have analysed
+already from a different point of view, as being among the most typical
+phenomena of organic regulation--form the starting-point of this
+theory, and it must be granted that they form a very solid foundation,
+for they are facts. The theory only has to enlarge hypothetically the
+realm of these facts, or rather the realm of the law that governs them.
+Indeed, it is assumed by Lamarckism that the organism is endowed with
+the faculty of responding to *any* change of the environment which may
+change its function by a morphologically expressed alteration of its
+functional state and form, which is adapted to the state of conditions
+imposed from without. Of course, as stated in this most general form,
+the assumption is not true, but it is true within certain limits, as
+we know; and there seems to be no reason why we should not believe
+that there are many more cases of adaptation than we actually know at
+present, or that, in former phylogenetic times, the organisms were more
+capable of active adaptation than they are now. So to a certain extent,
+at least, Lamarckism can be said to rest upon a *causa vera*.
+
+It is important to notice that this *causa vera* would imply vitalistic
+causality when taken in the wide meaning which Lamarckism allows to
+it: indeed, the power of active adaptation to indefinite changes would
+imply a sort of causal connection that is nowhere known except in the
+organism. Lamarck himself is not very clear about this point, he seems
+to be afraid of certain types of uncritical vitalism in vogue in his
+days; but modern writers have most clearly seen what the logical
+assumptions of pure Lamarckism are. Next to Cope, August Pauly[146] may
+be said to be the most conscious representative of a sort of so-called
+psychological vitalism, which indeed Lamarckism as a general and
+all-embracing theory must have as its basis.
+
+[146] *Darwinismus und Lamarckismus*, München, 1905.
+
+
+THE ACTIVE STORING OF CONTINGENT VARIATIONS AS A HYPOTHETIC PRINCIPLE
+
+This point will come out more fully, if now we turn to study a certain
+group of principles, upon which dogmatic Lamarckism rests: I say
+principles and not facts, for there are no facts but only hypothetic
+assumptions in this group of statements. We do know a little about
+adaptations, at least to a certain extent, and it was only about the
+sphere of the validity of a law, which was known to be at work in
+certain cases, that hypothetical additions were made. In the second
+group of the foundations of Lamarckism we know absolutely nothing;
+accidental variations of form are supposed to occur, and the organism is
+said to possess the faculty of keeping and storing these variations and
+of handing them down to the next generation, if they happen to satisfy
+any of its needs.
+
+But these needs are not of the actual type, brought forth by a change of
+the functional state of the individual, as in the case of adaptations:
+they are of a somewhat mysterious nature. A glance at the theory of the
+origin of the movements which are called acts of volition in the human
+child may serve to elucidate what is meant.
+
+Acts of volition are said thus to originate in random movements of the
+new-born infant: certain of these accidental motions which happen to
+relieve some pain or to afford some pleasure are “remembered,” and are
+used another time quite consciously to bring forth what is liked or to
+remove what is disliked. So much for the present on a very difficult
+subject, which will occupy us next year at much greater length. It is
+clear that at least three fundamental phenomena are concerned in this
+theory of the origin of acts of volition: the liking and disliking, the
+keeping in mind, and the volition itself. The real act of volition,
+indeed, is always based upon a connection of all these factors, these
+factors now being connected in such a way that even their kind of
+connection may be said to be a fourth fundamental principle. In order
+that the particular effect may be obtained which is wanted because it is
+liked, the possible ways leading to it, which appeared among the random
+movements in the very beginning, are now regarded as “means” and may now
+be said to be “used.” But that is as much as to say that the “means”
+are judged with respect to their usefulness for the actual purpose, and
+therefore *judgment* is the fourth foundation of the act of volition.
+
+In fact, Pauly does not hesitate to attribute judgment, along with the
+other psychological elements, to the organisms whilst undergoing their
+transformation. There has been formed, for instance, by accidental
+variation some pigment which by its chemical nature brings the organism
+into a closer connection with the light of the medium; the individual
+likes that, keeps the pigment for itself and produces it again in the
+next generation; and indeed it will safeguard any sort of improvement
+which chance may effect in this primitive “eye.” Such a view is said
+to hold well with respect to the origin of every new organ. And this
+psychological argument is also said to afford the real explanation of
+adaptation proper. Adaptation also is regarded not as a truly primary
+faculty of the organism, but as a retention or provoking of metabolic
+states which occurred by accident originally and were then found to
+be useful; now they are reproduced either in every single case of
+individual morphogenesis, without regard to actual requirements, or
+else only in response to such: in the first case they are “inherited,”
+in the second they only occur as regulations. Thus the process of
+judgment, together with all the other elemental factors of psychical
+life concerned in it, has been made to account for adaptation proper.
+The whole theory has accordingly become very uniform and simple.
+
+
+CRITICISM OF THE “INHERITANCE OF ACQUIRED CHARACTERS” ASSUMED BY
+LAMARCKISM
+
+In addressing ourselves to the criticism of Neo-Lamarckism we shall
+neglect as far as possible all the different psychological principles
+concerned in it--which in any case would need rather a great amount of
+epistemological sifting--and shall keep to those hypothetic facts which
+are supposed to be such as may be actually observed in nature.
+
+All of you know that the so-called inheritance of acquired characters
+lies at the root of Lamarckism; and from this hypothesis our critical
+analysis is to start, disregarding a larger or smaller number of
+psychological principles that are brought into the field.
+
+The name of “acquired characters” may *a priori* be given to three
+different types of phenomena: firstly, variations including mutations;
+secondly, disease or injuries; and thirdly, the results of the actual
+process of adaptation of every kind.
+
+In the first of these groups, the true problem of the inheritance of
+“acquired” characters appears only with certain restrictions. All
+variations and mutations are indeed “acquired” by one generation so
+far as the earlier generation did not possess them, but mutations, at
+least, cannot be said to be acquired by the actual adult personality:
+they are innate in it from its very beginning, and therefore may better
+be called congenital.[147] Congenital properties of the mutation type
+are, in fact, known to be inherited: their inheritance does not present
+any problem of its own, but is included in the changes of the hereditary
+condition to which they are due altogether.[148] All properties of the
+variation type, on the other hand, having been studied statistically,
+are known to be inherited, to a certain small extent, as we have seen
+already whilst studying Darwinism, though they are possibly always
+liable to reversion. Modern science, as we know,[149] regards them as
+due to changes of nutrition, in the most general meaning of the word.
+Under such a view variations might indeed be said to belong to the
+acquired group of organic specifications; their inheritance, as will
+be seen later on, would hardly be quite a pure instance of what we are
+searching for. In no case can true variations claim to be of great
+importance in problems of transformism.
+
+[147] This would not be true, if the varieties of plants produced by
+Blaringhem, Klebs, and MacDougal by means of *external* agents were
+really “mutations” (comp. page 238, note 3).
+
+[148] Of course, the inheritance of mutations would imply a certain sort
+of “inheritance of acquired characters,” on the condition stated in the
+preceding note. But, probably, the germs of the next generation might
+be regarded here as being directly affected by the external agent, in a
+manner that will briefly be mentioned later on in the text.
+
+[149] Comp. page 238, note 2.
+
+But what is known about the inheritance of those properties which
+beyond any doubt may be said to have originated in the adult individual
+as such, and of which lesions and adaptations proper, as shown for
+instance among amphibious plants, are instances of the two most
+typical groups?[150] Weismann did good service by putting an end to
+the scientific credulity which prevailed with regard to this subject.
+Weismann was led by his theory of the germ plasm to deny the inheritance
+of acquired characters of the typical kinds. He could not imagine how
+the effect of any agent upon the adult, be it of the merely passive or
+of the adaptive kind, could have such an influence upon the germ as to
+force it to produce the same effect in spite of the absence of that
+agent. In fact, that is what the inheritance of acquired characters
+would render necessary, and a very strange phenomenon it would be,
+no doubt. But, of course, taken alone, it could never be a decisive
+argument against such inheritance. I fully agree, that science is
+obliged to explain new facts by what is known already, as long as it is
+possible; but if it is no longer possible, the theory of course has to
+be changed, and not the facts. On this principle one would not neglect
+the fact of an inheritance of acquired properties, but on the contrary
+one perhaps might use it as a new evidence of vitalism.
+
+[150] Certain English authors have applied the term “modification” to
+all kinds of organic properties acquired from without, whether they are
+adapted or not.
+
+But are there any facts?
+
+At this point we come to speak about the second group of Weismann’s
+reasonings. He not only saw the difficulty of understanding inheritance
+of acquired characters on the principles of the science of his time,
+but he also criticised the supposed facts; and scarcely any of them
+stood the test of his criticism. Indeed, it must fairly be granted that
+not one case is known which really proves the inheritance of acquired
+characters, and that injuries certainly are never found to be inherited.
+In spite of that, I do not believe that we are entitled to deny the
+possibility of the inheritance of a certain group of acquired characters
+in an absolute and dogmatic manner, for there are a few facts which seem
+at least to tend in the direction of such an inheritance, and which seem
+to show that it might be discovered perhaps one day, if the experimental
+conditions were changed.
+
+I am not referring here to the few cases in which bacteria were made
+colourless or non-virulent by outside factors, or in which certain
+fungi were forced to permanent agamic reproduction by abnormal external
+conditions and were shown to retain their “acquired properties”
+after the external conditions had been restored. In these cases only
+reproduction by simple division occurred, and that does not imply the
+true problem of inheritance. Nor am I referring to the few cases of
+non-adaptive “modifications” found by Standfuss and Fischer, in which
+butterflies that had assumed an abnormal kind of pigmentation under
+the influence of abnormal temperature acting upon the pupa, were seen
+to form this same kind of pigmentation in the next generation under
+normal conditions of temperature. These cases, though important in
+themselves, are capable perhaps of a rather simple explanation, as in
+fact has been suggested. Some necessary means both of inheritance and of
+morphogenesis, the former being present in the propagation cells, may
+be said to have been changed or destroyed by heat, and therefore, what
+seems to be inherited after the change of the body only, would actually
+be the effect of a direct influence of the temperature upon the germ
+itself.[151] Let me be clearly understood: I do not say that it is so,
+but it may be so. What seems to me to be more important than everything
+and to have a direct bearing on the real discovery of the inheritance
+of acquired characters in the future, is this. In some instances
+plants which had been forced from without to undergo certain typical
+morphological adaptations, or at least changes through many generations,
+though they did not keep the acquired characters permanently in spite
+of the conditions being changed to another type, were yet found to lose
+the acquired adaptations not suddenly but only in the course of three
+or more generations. A certain fern, *Adiantum*, is known to assume a
+very typical modification of form and structure, if grown on serpentine;
+now Sadebeck,[152] while cultivating this serpentine modification of
+*Adiantum* on ordinary ground, found that the first generation grown in
+the ordinary conditions loses only a little of its typical serpentine
+character, and that the next generation loses a little more, so that
+it is not before the fifth generation that all the characters of the
+serpentine modification have disappeared. There are a few more cases
+of a similar type relating to plants grown in the plains or on the
+mountains. There also it was found to take time, or rather to take the
+course of *several* generations, until what was required by the new
+conditions was reached. Of course these cases are very very few compared
+with those in which a *sudden* change of the adaptive character,
+corresponding to the actual conditions, sets in; but it is enough that
+they do exist.
+
+[151] Of course the inheritance of specific values from the results of
+fluctuating variations, leading to new averages of variability (see
+p. 265), may also be understood in this manner, the conditions of
+nourishment acting upon the adult and upon its germs equally well.
+
+[152] *Berichte üb. d. Sitzung. d. Ges. f. Bot.*, Hamburg, 1887, 3 Heft.
+
+Would it not be possible at least that adaptations which last
+for thousands of generations or more might in fact change the
+adaptive character into a congenital one? Then we not only should
+have inheritance of acquired characters, but should have a sort
+of explanation at the same time for the remarkable fact that
+certain histological structures of a very adapted kind are formed
+ontogenetically before any function exists, as is known to be the
+case with the structures in the bones of vertebrates, for instance.
+Experiments are going on at Paris, and perhaps in other places of
+scientific research also, which, it is hoped, will show that animals
+reared in absolute darkness for many generations will lose their
+perfectly formed eyes, and that animals from the dark with very
+rudimentary eyes will be endowed with properly functioning ones, after
+they have been reared in the light for generations. Such a result indeed
+would account for the many animals, of the most different groups, which
+live in dark caves and possess only rudiments of eyes: functional
+adaptation is no longer necessary, so-called atrophy by inactivity sets
+in, and the results “acquired” by it are inherited.[153]
+
+[153] Quite recently Kammerer (*Arch. Entw. Mech.* 25, 1907, p. 7) has
+published very important experiments on the inheritance of “acquired”
+modifications with regard to the peculiarities of reproduction in
+*Salamandra atra* and *S. maculosa*. It seems rather improbable--though
+not absolutely impossible--that the germ cells were directly affected by
+the external modifying agent in this case.
+
+But enough of possibilities. Let us be content at present to know at
+least a few real instances with regard to the slowness of the process of
+what might be said to be “re-adaptation” in some plants. This process
+shows us a way by which our problem may some day be solved; it allows
+us to introduce inheritance of acquired characters as a legitimate
+hypothesis at least, which not only will explain many of the diversities
+in systematics historically, but also can be called, though not a *causa
+vera*, yet certainly more than a mere fiction.
+
+
+OTHER PRINCIPLES WANTED
+
+We have only dealt with the probability of the inheritance of
+morphological or physiological[154] adaptation. If that could really be
+considered as one of the factors concerned in the theory of descent,
+many, if not all of those congenital diversities among organic species
+which are of the type of a true structural correspondence to their
+future functional life, might be regarded as explained, that is,
+as reduced to one and the same principle. But nothing more than an
+explanation of *this* kind of diversities is effected by our principle,
+and very much more remains to be done, for organic diversities not only
+consist in specifications and differences as to histology, but are to a
+much more important degree, differences of organisation proper, that is,
+of the arrangement of parts, in the widest sense of the word.[155]
+
+[154] We have not spoken about the hypothetic inheritance of pure
+physiological adaptations, for it is clear without further discussion
+that innate specific immunity, for instance, being a specific
+“adaptedness” (*see* p. 186) *might* be due to the inheritance of the
+results of active immunity as an adaptation, just as adaptive congenital
+structures *might* be due to such an inheritance.
+
+[155] C. E. v. Baer clearly discriminated between the type, the degree
+of organisation, and the histological structure. All these three topics
+indeed have to be taken into account separately; the third alone is of
+the adaptive type. All of them may be independent of each other: the
+Amoeba may be as adapted histologically as is a high vertebrate, but it
+is of much lower type; and in its own type it is of a lower degree of
+organisation than Radiolaria are.
+
+Would it be possible to interpret the origin of this sort of systematic
+diversities by a reasoning similar to that by which we have understood,
+at least hypothetically, congenital adaptedness?
+
+Dogmatic Lamarckism, we know, uses two principles as its foundations;
+one of them, adaptation and its inheritance, we have studied with what
+may be called a partly positive result. The other is the supposed
+faculty of the organism to keep, to store, and to transfer those
+variations or mutations of a not properly adaptive sort which, though
+originating by chance, happen to satisfy some needs of the organism.
+
+
+CRITICISM OF THE HYPOTHESIS OF STORING AND HANDING DOWN CONTINGENT
+VARIATIONS
+
+Strange to say, this second hypothesis of dogmatic Lamarckism, invented
+with the express purpose of defeating Darwinism and taking the place of
+its fluctuating variability, which was found not to do justice to the
+facts--this second hypothesis of dogmatic Lamarckism is liable to just
+the same objections as dogmatic Darwinism itself.
+
+As it is important to understand well the real logical nature of
+our objections to both of the great transformistic theories, we
+think it well to interrupt our argument for a moment, in order to
+consider a certain point which, though very important in itself,
+seems of only secondary importance to us in our present discussion.
+Dogmatic Darwinism--I do not say the doctrine of Charles Darwin--is
+materialistic at bottom, and indeed has been used by many to complete
+their materialistic view of the universe on its organic side. The word
+“materialism” must not necessarily be taken here in its metaphysical
+sense, though most materialists are dogmatic metaphysicians. It also
+can be understood as forming part of a phenomenological point of view.
+Materialism as a doctrine of science means simply this: that whether
+“nature” be reality or phenomenon, in any case there is but one ultimate
+principle at its base, a principle relating to the movements of
+particles of matter. It is this point of view which dogmatic Darwinism
+strengthens; on the theory of natural selection and fluctuating
+variations, due to accidental differences of nutrition, organisms are
+merely arrangements of particles of matter, nothing else; and moreover,
+their kinds of arrangement are understood, at least in principle.
+Lamarckism, on the other hand, is not materialistic, but most markedly
+vitalistic--psychistic even; it takes life for granted when it begins
+its explanations.
+
+You may tell me that Darwin did the same, that he expressly states that
+his theory has nothing to do with the origin of life; that the title
+of his work is “The Origin of *Species*.” It would certainly be right
+to say so, at least with reference to Darwin personally; but in spite
+of that, it must be granted that Darwin’s doctrine contains a certain
+germ of materialism which has been fully developed by the Darwinian
+dogmatists, while Lamarckism is antimaterialistic by its very nature.
+
+Now it is very important, I think, to notice that this difference
+between the two theories is unable to disguise one main point which is
+common to both: and it is to this point, and to this point only, that
+our chief objections against both these theories converge at present.
+
+The *contingency* of the typical organic form is maintained by Darwinism
+as well as by Lamarckism: both theories, therefore, break down for
+almost the same reasons. The term “contingency” can signify very
+different relations, having but little in common; but it is sufficient
+for our present purpose to observe that there may be distinguished
+roughly two main classes of contingencies, which may provisionally be
+called the “contingency of being,” and the “contingency of occurring.”
+It is with the contingency of being that criticism of Darwinism and
+Lamarckism of the dogmatic type has to deal. Darwinism dealt with
+variations occurring at random; the organic form was the result of
+a fixation of only one kind of such variations, all others being
+extinguished by selection. In other terms, the specific organised
+form, as understood by Darwinism, was a unit only to the extent that
+all its properties related to one and the same body, but for the rest
+it was a mere aggregation or summation. It may be objected to this
+statement, that by being inherited in its specificity the Darwinian
+form proved to be a unit in a higher sense of the word, even in the
+opinion of dogmatic Darwinians; and this objection, perhaps, holds good
+as far as inheritance is concerned. But on the other hand, it must
+never be forgotten that the word “unit” had quite a vague and empty
+meaning even then, as indeed everything the organism is made up of
+is regarded as being in itself due to a contingent primary process,
+which has no relation to its fellow-processes. “Unit,” indeed, in spite
+of inheritance--which, by the way, is alleged also to be a merely
+materialistic event--means to Darwinians no more when applied to the
+organism than it does when applied to mountains or islands, where of
+course a sort of “unit” also exists in some sense, as far as one and the
+same body comes into account, but where every single character of this
+unit, in every single feature of form or of quality, is the result of
+factors or agents each of which is independent of every other.
+
+To this sort of contingency of being, as maintained by Darwinians,
+criticism has objected, as we know, that it is quite an impossible
+basis of a theory of descent, since it would explain neither the first
+origin of an organ, nor any sort of harmony among parts or among whole
+individuals, nor any sort of restitution processes.
+
+Now Lamarckism of the dogmatic kind, as will easily be seen, only
+differs from Darwinism in this respect, that what according to the
+latter happens to the organism passively by means of selection, is
+according to the former performed actively by the organism, by means of
+a “judgment”--by the retention and handing down of chance variations.
+The specificity of the form as a whole is contingent also according
+to Lamarckism. And, indeed, criticism must reject this contingency of
+being in exactly the same way as it rejected the contingency of form
+maintained by Darwinians.
+
+As far as the inheritance of truly adaptive characters comes into
+account--that is, the inheritance of characters which are due to the
+active faculty of adaptation possessed by the organism, bearing a
+vitalistic aspect throughout--hardly anything could be said against
+Lamarckism, except that inheritance of acquired characters is still
+an hypothesis of small and doubtful value at present. But that
+*specific organisation proper* is due to *contingent* variations, which
+accidentally have been found to satisfy some needs of the individual and
+therefore have been maintained and handed down, this reasoning is quite
+an impossibility of exactly the same kind as the argument of Darwinism.
+
+The process of restitution, perfect the very first time it occurs, if it
+occurs at all, is again the classical instance against this new sort of
+contingency, which is assumed to be the basis of transformism. Here we
+see with our eyes that the organism can do more than simply perpetuate
+variations that have occurred at random and bear in themselves no
+relation whatever to any sort of unit or totality. There *exists* a
+faculty of a certain higher degree in the organism, and this faculty
+cannot possibly have originated by the process which Lamarckians[156]
+assume. But if their principle fails in one instance, it fails as a
+*general* theory altogether. And now, on the other hand, as we actually
+see the individual organism endowed with a morphogenetic power,
+inexplicable by Lamarckism, but far exceeding the organogenetic faculty
+assumed by that theory, would it not be most reasonable to conclude from
+such facts, that there exists a certain organising power at the root of
+the transformism of species also, a power which we do not understand,
+which we see only partially manifested in the work of restitutions,
+but which certainly is not even touched by any of the Lamarckian
+arguments? There does indeed exist what Gustav Wolff has called primary
+purposefulness (“primäre Zweckmässigkeit”), at least in restitutions,
+and this is equally unexplainable by Darwinism and by the dogmatism of
+the Lamarckians.
+
+[156] I repeat once more that we are dealing here with dogmatic
+“Neo-”Lamarckism exclusively. This theory indeed claims to explain *all*
+features and properties of organic bodies on the basis of the feeling
+of needs and storing of contingent fulfilments and on this basis alone,
+just as dogmatic “Neo”-Darwinism claims to account for *all* those
+phenomena on the ground of contingent variations and natural selection.
+Darwin himself, as we have seen, intentionally left unexplained certain
+primary features of life and therefore cannot be blamed for having
+failed to explain them, though even then his theory remains wrong.
+Lamarck personally considered a real primary organisatory law of
+phylogeny as being of fundamental importance, and therefore he is not in
+the least responsible if “Neo-Lamarckism” fails as a universal theory.
+
+But before entering into this area of hypothesis, let us mention a few
+more objections to be made to the theory of the contingency of form as
+put forward by Lamarckians. In the first place, let us say a few words
+about the appropriateness of the term “contingency” as used in this
+connection. The forms are regarded as contingent by Lamarckians inasmuch
+as the variations which afterwards serve as “means” to the “needs” of
+the organism occur quite accidentally with regard to the whole organism.
+It might be said that these “needs” are not contingent but subject
+to an inherent destiny, but this plea is excluded by the Lamarckians
+themselves, when they say that the organism experiences no need until it
+has enjoyed the accidental fulfilment of the same. So the only thing in
+Lamarckian transformism which is not of a contingent character would be
+the psychological agent concerned in it, as being an agent endowed with
+the primary power of feeling needs after it has felt fulfilment, and of
+judging about what the means of future fulfilment are, in order to keep
+them whenever they offer. But these are characteristics of life itself,
+irrespective of all its specific forms, which alone are concerned in
+transformism. Now indeed, I think, we see as clearly as possible that
+Darwinism and Lamarckism, in spite of the great contrast of materialism
+and psychologism, shake hands on the common ground of the contingency of
+organic forms.
+
+The whole anti-Darwinistic criticism therefore of Gustav Wolff for
+instance, may also be applied to Lamarckism with only a few changes
+of words. How could the origin of so complete an organ as the eye of
+vertebrates be due to contingent variations? How could that account for
+the harmony of the different kinds of cells in this very complicated
+organ with each other and with parts of the brain? And how is it to be
+understood, on the assumption of contingency, that there are two eyes of
+almost equal perfection, and that there are two feet, two ears? Islands
+and mountains do not show such symmetry in *their* structures.
+
+We shall not repeat our deduction of the origin of restitutions, of
+regeneration for instance, on the dogmatic Lamarckian theory. As we
+have said already, it would lead to absurdities as great as in the
+case of dogmatic Darwinism, and indeed we already have mentioned that
+Lamarckians would hardly even attempt to explain these phenomena.
+It follows that dogmatic Lamarckism fails as a general theory about
+form.[157]
+
+[157] Compare also the excellent criticism of Lamarckism lately given by
+G. Wolff, *Die Begründung der Abstammungslehre*, München, 1907.
+
+There is finally one group of facts often brought forward against
+Lamarckism by Darwinian authors[158] which may be called the logical
+*experimentum crucis* of this doctrine, an *experimentum* destined
+to prove fatal. You know that among the polymorphic groups of bees,
+termites, and ants, there exists one type of individuals, or even
+several types, endowed with some very typical features of organisation,
+but at the same time absolutely excluded from reproduction: how could
+those morphological types have originated on the plan allowed by the
+Lamarckians? Of what use would “judgment” about means that are offered
+by chance and happen to satisfy needs, be to individuals which die
+without offspring? Here Lamarckism becomes a simple absurdity, just as
+Darwinism resulted in absurdities elsewhere.
+
+[158] It has also very often been said by Darwinians that Lamarckism is
+only able to explain those cases of adaptedness which relate to active
+functioning but not mere passive adapted characters, like “mimicry” for
+example. But this argument *taken by itself*, it seems to me, would not
+be fatal to Neo-Lamarckism in the special form August Pauly gave to this
+doctrine.
+
+We were speaking about dogmatic Darwinism then, and it is about dogmatic
+Lamarckism that we are reasoning at present; both theories must fall in
+their dogmatic form, though a small part of both can be said to stand
+criticism. But these two parts which survive criticism, one offered by
+Lamarck, the other by Darwin, are far from being a complete theory of
+transformism, even if taken together: they only cover a small area of
+the field concerned in the theory of descent. Almost everything is still
+to be done, and we may here formulate, briefly at least, what we expect
+to be accomplished by the science of the future.
+
+
+4. THE REAL RESULTS AND THE UNSOLVED PROBLEMS OF TRANSFORMISM
+
+What has been explained to a certain extent by the two great theories
+now current is only this. Systematic diversities consisting in mere
+differences as to intensity or number may perhaps owe their origin to
+ordinary variation. They may at least, if we are entitled to assume
+that heredity in some cases is able to hand on such variations without
+reversion, which, it must be again remarked, is by no means proved by
+the facts at present. Natural selection may share in this process by
+eliminating all those individuals that do not show the character which
+happens to be useful. That is the Darwinian part of an explanation of
+transformism which may be conceded as an hypothesis. On the other side,
+congenital histological adaptedness may be regarded hypothetically as
+due to an inheritance of adaptive characters which had been acquired by
+the organism’s activity, exerted during a great number of generations.
+That is the Lamarckian part in the theory of descent.
+
+But nothing more is contributed to this theory either by the doctrine
+of Darwin or by that of Lamarck. So it follows that almost everything
+has still to be done; for no hypothesis at present accounts for
+the foundation of all systematics, viz., for the differences in
+organisation, in all that relates to the so-called types as such and
+the degree of complication in these types, both of which (types and
+degree of complication) are independent of histological adaptation and
+adaptedness.
+
+What then do we know about any facts that might be said to bear on
+this problem? We have stated already at the end of our chapter devoted
+to the analysis of heredity that what we actually know about any
+deviation of inheritance proper, that is, about congenital differences
+between the parents and the offspring, relating to mere tectonics,
+is practically nothing: indeed, there are at our disposal only the
+few facts observed by de Vries or derived from the experience of
+horticulturalists and breeders. We may admit that these facts at
+least prove the possibility[159] of a discontinuous variation, that
+is of “mutation,” following certain lines of tectonics and leading to
+*constant* results; but everything else, that is everything about a real
+theory of phylogeny, must be left to the taste of each author who writes
+on the theory of the Living. You may call that a very unscientific state
+of affairs, but no other is possible.
+
+[159] But nothing more. All “mutations” hitherto observed in nature
+or (comp. page 238, note 3) experimentally produced relate only to
+“varieties” and not to “species.” One could hardly say that the
+recent investigations about the production of mutations by *external*
+means have strengthened their importance for the general theory of
+transformism.
+
+And, in fact, it has been admitted by almost all who have dealt with
+transformism without prepossessions that such is the state of affairs.
+Lamarck himself, as we have mentioned already, was not blind to the fact
+that a sort of organisatory law must be at the base of all transformism,
+and it is well known that hypothetical statements about an original law
+of phylogeny have been attempted by Nägeli, Kölliker, Wigand, Eimer,
+and many others. But a full discussion of all these “laws” would hardly
+help us much in our theoretical endeavour, as all of them, it must be
+confessed, do little more than state the mere fact that some unknown
+principle of organisation must have been at work in phylogeny, if we are
+to accept the theory of descent at all.
+
+It is important to notice that even such a convinced Darwinian as
+Wallace, who is well known to have been an independent discoverer of the
+elimination principle, admitted an exception to this principle in at
+least one case--with regard to the origin of man. But one exception of
+course destroys the generality of a principle.
+
+As we ourselves feel absolutely incapable of adding anything specific
+to the general statement that there *must* be an unknown principle of
+transformism, if the hypothesis of descent is justified at all, we may
+here close our discussion of the subject.
+
+
+5. THE LOGICAL VALUE OF THE ORGANIC FORM ACCORDING TO THE DIFFERENT
+TRANSFORMISTIC THEORIES
+
+A few words only must be added about two topics: on the character of
+organic forms as regarded by the different transformistic theories, and
+on the relation of transformism in general to our concept of entelechy.
+
+We have learnt that both Darwinism and Lamarckism, in their dogmatic
+shape, regard the specific forms of animals and plants as being
+contingent; in fact, it was to this contingency that criticism was
+mainly directed. We therefore are entitled to say that to Darwinism and
+Lamarckism organic forms are accidental in the very sense of the *forma
+accidentalis* of the old logicians. There are indefinite forms possible,
+according to these theories, and there is no law relating to these
+forms. Systematics, under such a view, must lose, of course, any really
+fundamental importance. “There is no rational system about organisms”:
+that is the ultimate statement of Darwinism and of Lamarckism on this
+doubtful question. Systematics is a mere catalogue, not at present
+only, but for ever, by the very nature of the organisms. It is not
+owing to the indefinite number of possible forms that both our theories
+came to deny the importance of systematics, but to the want of a *law*
+relating to this indefinite number: among chemical compounds indefinite
+possibilities also exist in some cases, but they obey the law of the
+general formula. It is very strange that Darwinians of all people are
+in the forefront of systematic research in all countries: do they not
+see that what they are trying to build up can only relate to accidental
+phenomena? Or have they some doubts about the foundations of their own
+theoretical views, in spite of the dogmatic air with which they defend
+them? Or is it the so-called historical interest which attracts them?
+
+A new question seems to arise at this point: Have not we ourselves
+neglected history in favour of systematics and laws? Our next lecture,
+the last of this year, will give the answer to this question.
+
+At present we continue our study of the possible aspects of systematics.
+It is not difficult to find out what meaning organic forms would assume
+under any phylogenetic theory opposed to the theories of contingency.
+It was their defence of contingency, that is, their lack of any law
+of forms, that caused these theories to be overthrown--reduced to
+absurdities even--and therefore, it follows that to assume any kind of
+transformistic law is at the same time to deny the accidental character
+of the forms of living beings.
+
+There is no *forma accidentalis*. Does that mean that the *forma
+essentialis* is introduced by this mere statement? And what would *that*
+assert about the character of systematics?
+
+
+THE ORGANIC FORM AND ENTELECHY
+
+This problem is not as simple as it might seem to be at the first
+glance, and, in fact, it is insoluble at present. It is here that the
+relation of the hypothetic transformistic principle to our concept of
+entelechy is concerned.
+
+We know that entelechy, though not material in itself, uses material
+means in each individual morphogenesis, handed down by the material
+continuity in inheritance. What then undergoes change in phylogeny,
+the means or the entelechy? And what would be the logical aspect of
+systematics in either case?
+
+Of course there would be a law in systematics in any case; and therefore
+systematics in any case would be rational in principle. But if the
+transformistic factor were connected with the means of morphogenesis,
+one could hardly say that specific form as such was a primary essence.
+Entelechy would be that essence, but entelechy in its generality and
+always remaining the same in its most intimate character, as the
+specific diversities would only be due to a something, which is not
+form, but simply means to form. But the *harmony* revealed to us in
+every typical morphogenesis, be it normal or be it regulatory, seems
+to forbid us to connect transformism with the means of morphogenesis.
+And therefore we shall close this discussion about the most problematic
+phenomena of biology with the declaration, that we regard it as more
+congruent to the general aspect of life to correlate the unknown
+principle concerned in descent with entelechy itself, and not with
+its means. Systematics of organisms therefore would be in fact
+systematics of entelechies, and therefore organic forms would be
+*formae essentiales*, entelechy being the very essence of form in its
+specificity. Of course systematics would then be able to assume a truly
+rational character at some future date: there might one day be found
+a principle to account for the totality of possible[160] forms, a
+principle based upon the analysis of entelechy.[161] As we have allowed
+that Lamarckism hypothetically explains congenital adaptedness in
+histology, and that Darwinism explains a few differences in quantity,
+and as such properties, of course, would both be of a contingent
+character, it follows that our future rational system would be combined
+with certain accidental diversities. And so it might be said to be
+one of the principal tasks of systematic biological science in the
+future to discover the really rational system among a given totality of
+diversities which cannot appear rational at the first glance, one sort
+of differences, so to speak, being superimposed upon the other.
+
+[160] The word “possible” relating to originating, of course, not to
+surviving. It is here that natural selection may acquire its logical
+importance alluded to above (see page 264).
+
+[161] The discussions in the second volume of this book will show the
+possible significance of such an analysis. We at present are dealing
+with entelechy in a quasi-popular manner.
+
+
+
+
+*C.* THE LOGIC OF HISTORY
+
+
+History, in the strictest sense of the word, is the enumeration of the
+things which have followed one another in order of time. History deals
+with the single, with regard both to time and space. Even if its facts
+are complex in themselves and proper to certain other kinds of human
+study, they are nevertheless regarded by history as single. Facts, we
+had better say, so far as they are regarded as single, are regarded
+historically, for what relates to specific time and space is called
+history.
+
+Taken as a simple enumeration or registration, history, of course,
+cannot claim to be a “science” unless we are prepared to denude that
+word of all specific meaning. But that would hardly be useful. As a
+matter of fact, what has actually claimed to be history, has always
+been more than a mere enumeration, even in biology proper. So-called
+phylogeny implies, as we have shown, that every one of its actual
+forms contains some rational elements. Phylogeny always rests on
+the assumption that only some of the characters of the organisms
+were changed in transformism and that what remained unchanged may be
+explained by the fact of inheritance.
+
+But this, remember, was the utmost we were able to say for phylogeny.
+It remains fantastic and for the most part unscientific in spite of
+this small degree of rationality, as to which it is generally not very
+clear itself. For nothing is known with regard to the positive factors
+of transformism, and we were only able to offer the discussion of a few
+possibilities in place of a real theory of the factors of descent.
+
+In spite of that it will not be without a certain logical value to begin
+our analysis of history in general by the discussion of possibilities
+again. Biology proper would hardly allow us to do more: for the
+simple “fact” of history is not even a “fact” in this science, but an
+hypothesis, albeit one of some probability.
+
+As discussions of mere possibilities should always rest on as broad a
+basis as possible, we shall begin our analysis by raising two general
+questions. To what kinds of realities may the concept of history
+reasonably be applied? And what different types of “history” would be
+possible *a priori*, if the word history is to signify more than a mere
+enumeration?
+
+
+1. THE POSSIBLE ASPECTS OF HISTORY
+
+Of course, we could select one definite volume in space and call all the
+consecutive stages which it goes through, its history: it then would be
+part of its history that a cloud was formed in it, or that a bird passed
+through it on the wing. But it would hardly be found very suggestive to
+write the history of space-volumes. In fact, it is to *bodies* in space
+that all history actually relates, at least indirectly, for even the
+history of sciences is in some respect the history of men or of books.
+It may suffice for our analysis to understand here the word body in its
+popular sense.
+
+Now in its relation to bodies history may have the three following
+aspects, as far as anything more than a simple enumeration comes into
+account. Firstly, it may relate to one and the same body, the term
+body again to be understood popularly. So it is when the individual
+history of the organism is traced from the egg to the adult, or when the
+history of a cloud or of an island or of a volcano is written. Secondly,
+the subject-matter of history may be formed by the single units of a
+consecutive series of bodies following each other periodically. To this
+variety of history the discoveries of Mendel and his followers would
+belong in the strictest sense, but so does our hypothetical phylogeny
+and a great part of the history of mankind. And lastly, there is a
+rather complicated kind of sequence of which the “history” has actually
+been written. History can refer to bodies which are in no direct
+relation with one another, but which are each the effect of another body
+that belongs to a consecutive series of body-units showing periodicity.
+This sounds rather complicated; but it is only the strict expression
+of what is perfectly familiar to you all. Our sentence indeed is
+simply part of the definition of a history of art or of literature for
+instance--or, say, of a phylogenetic history of the nests of birds. The
+single pictures are the subjects of the history of art, and nobody would
+deny that these pictures are the effects of their painters, and that
+the painters are individuals of mankind--that is, that they are bodies
+belonging to a consecutive series of body-units showing periodicity. Of
+course, it is only improperly that we speak of a history of pictures or
+of books or of nests. In fact, we are dealing with painters, and with
+men of letters or of science, and with certain birds, and therefore
+the third type of history may be reduced to the second. But it was not
+without value to pursue our logical discrimination as far as possible.
+
+So far we have always spoken of history as being more than a mere
+enumeration, but we have not ascertained what this “more” signifies. It
+is not very difficult to do so: in fact, there are three different types
+of history, each of a different degree of importance with respect to the
+understanding of reality.
+
+In the first place, history may start as a mere enumeration at the
+beginning, and at the end, in spite of all further endeavour, may
+*remain* that and nothing more. That may occur in the first as well
+as in the second group of our division of history with regard to
+its relation to bodies. Take a cloud and describe its history from
+the beginning to the end: there would never be much more than pure
+description. Or take one pair of dogs and describe them and their
+offspring for four generations or more: I doubt if you will get beyond
+mere descriptions in this case either. The only step beyond a mere
+enumeration which we can be said to have advanced in these instances,
+consists in the conviction, gained at the end of the analysis, that
+nothing more than such an enumeration is in any way *possible*.
+
+Quite the opposite happens when “history” deals with the individual
+from the egg to the adult: here the whole series of historical facts is
+seen to form one whole. This case therefore we shall call not history,
+but *evolution*, an evolving of something; the word “evolution” being
+understood here in a much wider sense than on former occasions,[162] and
+*including*, for instance, the embryological alternative “evolutio” or
+“epigenesis.”
+
+[162] See pp. 26, 45, 54, etc.
+
+And half-way between enumeration and evolution there now stands a type
+of history which is more than the one and less than the other: there is
+a kind of intelligible connection between the consecutive historical
+stages and yet the concept of a whole does not come in. The geological
+history of a mountain or of an island is a very clear instance of this
+class. It is easy to see here, how what *has been* always becomes the
+foundation of what *will be* in the *next* phase of the historical
+process. There is a sort of *cumulation* of consecutive phases, the
+later ones being impossible without the earlier. So we shall speak
+of the type of “historical cumulation” as standing between evolution
+and bare temporal sequence. By means of historical cumulations history
+may fairly claim to “explain” things. We “understand” a mountain or an
+island in all its actual characteristics, if we know its history. This
+“historical understanding” rests on the fact that what first appeared
+as an inconceivable complex has been resolved into a sequence of single
+events, each of which may claim to have been explained by actually
+existing sciences. The complex has been explained as being, though not
+a real “whole,” yet a sum of singularities, every element of which is
+familiar.
+
+But you may tell me that my discussion of evolution and of cumulation,
+as the higher aspects of history, is by no means complete; nay,
+more--that it is altogether wrong. You would certainly not be mistaken
+in calling my analysis incomplete. We have called one type of history
+evolution, the other cumulation; but how have these higher types been
+reached? Has historical enumeration itself, which was supposed to
+stand at the beginning of all analysis, or has “history” itself in its
+strictest sense, as relating to the single as such, risen unaided into
+something more than “history”? By no means: history has grown beyond
+its bounds by the aid of something from without. It is unhistorical
+elements that have brought us from mere history to more than history.
+We have created the concept of evolution, not from our knowledge of the
+single line of events attendant on a single egg of a frog, but from our
+knowledge that there are billions or more of frogs’ eggs, all destined
+to the same “history,” which therefore is not history at all. We have
+created the concept of cumulation not from the historical study of
+a single mountain, but from our knowledge of physics and chemistry
+and so-called dynamical geology: by the aid of these sciences we
+“understood” historically, and thus our understanding came from another
+source than history itself.
+
+
+2. PHYLOGENETIC POSSIBILITIES
+
+Does history always gain its importance from what it is not? Must
+history always lose its “historical” aspect, in order to become of
+importance to human knowledge? And can it *always* become “science” by
+such a transformation? We afterwards shall resume this discussion on
+a larger scale, but at present we shall apply what we have learned to
+hypothetic phylogeny. What then are the possibilities of phylogeny, to
+what class of history would it belong if it were complete? Of course, we
+shall not be able to answer this question fully; for phylogeny is *not*
+complete, and scarcely anything is known about the factors which act
+in it. But in spite of that, so much, it seems to me, is gained by our
+analysis of the possible aspects of history and of the factors possibly
+concerned in transformism, that we are at least able to formulate the
+possibilities of a phylogeny of the future in their strict logical
+outlines.
+
+Darwinism and Lamarckism, regarding organic forms as contingent, must
+at the same time regard organic history as a cumulation; they indeed
+*might* claim to furnish an historical explanation in the realm of
+biology--if only their statements were unimpeachable, which as we have
+seen, they are not.
+
+But any transformistic theory, which locates the very principle of
+phylogeny in the organism itself, and to which therefore even organic
+forms would be not accidental but essential, might be forced to regard
+the descent of organisms as a true evolution. The singularities in
+phylogenetic history would thus become links in one whole: history
+proper would become more than history. But I only say that phylogeny
+*might* be evolution, and in fact I cannot admit more than this *a
+priori*, even on the basis of an internal transformistic principle,
+as has been assumed. Such a principle also might lead always from one
+typical state of organisation to the next: but *ad infinitum*.[163]
+Then phylogeny, though containing what might in some sense be called
+“progress,” would not be “evolution”; it might even be called cumulation
+in such a case, in spite of the internal transforming principle, though,
+of course, cumulation from within would always mean something very
+different from cumulation from without.[164]
+
+[163] An immanent vitalistic phylogeny *without* a pre-established end
+has recently been advocated by H. Bergson (*L’évolution créatrice*,
+Paris, 1907).
+
+[164] In this connection the problem may be raised, whether there can be
+such a thing as unchangeable “species” in spite of the mutability of the
+individuals. Compare page 251, note 1.
+
+But we must leave this problem an open question, as long as our actual
+knowledge about transformism remains as poor as it is. We need only add,
+for the sake of logical interest, that phylogeny, as a true evolution,
+would necessarily be characterised by the possibility of being repeated.
+
+
+3. THE HISTORY OF MANKIND
+
+We only assume hypothetically that phylogeny has happened, and we know
+scarcely anything about the factors concerned in it. Now, it certainly
+would be of great importance, if at least in a small and definite field
+of biology we were able to state a little more, if the *mere fact* of
+phylogeny, of “history,” were at least beyond any doubt within a certain
+range of our biological experience. And indeed there is one department
+of knowledge, where history, as we know, *has happened*, and where we
+also know at least some of the factors concerned in it.
+
+I refer to the history of mankind; and I use the expression not at all
+in its anthropological or ethnographical sense, as you might expect
+from a biologist, but in its proper and common sense as the history of
+politics and of laws and of arts, of literature and of sciences: in a
+word, the history of civilisation. Here is the only field, where we know
+that there actually *are* historical facts: let us try to find out what
+these facts can teach us about their succession.
+
+The theory of history in this narrower meaning of the word has been
+the subject of very numerous controversies in the last twenty years,
+especially in Germany, and these controversies have led very deeply into
+the whole philosophical view of the universe. We shall try to treat our
+subject as impartially as possible.
+
+Hegel says, in the introduction to his *Phänomenologie des Geistes*:
+“*Die Philosophie muss sich hüten erbaulich sein zu wollen*”
+(“Philosophy must beware of trying to be edifying”). These words,
+indeed, ought to be inscribed on the lintel of the door that leads
+into historical methodology, for they have been sadly neglected by
+certain theoretical writers. Instead of analysing history in order to
+see what it would yield to philosophy, they have often made philosophy,
+especially moral philosophy, the starting-point of research, and history
+then has had to obey certain doctrines from the very beginning.
+
+We shall try as far as we can not to become “erbaulich” in our
+discussions. We want to learn from history for the purposes of
+philosophy, and we want to learn from history as from a phenomenon in
+time and in space, just as we have learnt from all the other phenomena
+regarding life in nature. Every class of phenomena of course may
+be studied with respect to generalities as well as with respect to
+particulars. The particular, it is true, has not taught us much in our
+studies so far. Perhaps it may be successful in the domain of history
+proper.
+
+If I take into consideration what the best authors of the last century
+have written about human history with respect to its general value, I
+cannot help feeling that none of them has succeeded in assigning to
+history a position where it would really prove to be of great importance
+for the aims of philosophical inquiry. Is that the fault of the authors
+or of human history? And what then would explain the general interest
+which almost every one takes, and which I myself take in history in
+spite of this unsatisfactory state of things?
+
+
+CUMULATIONS IN HUMAN HISTORY
+
+Let us begin our analytical studies of the value and the meaning of
+human history, by considering some opinions which deserve the foremost
+place in our discussion, not as being the first in time, but as being
+the first in simplicity. I refer to the views of men like Buckle, Taine,
+and Lamprecht, and especially Lamprecht, for he has tried the hardest to
+justify theoretically what he regards the only scientific aim of history
+to be. If we may make use of our logical scheme of the three possible
+aspects of history, it is clear from the beginning that the history of
+mankind, as understood by the three authors we have named, but most
+particularly by Lamprecht, is neither a mere enumeration nor a true
+evolution, but that it has to do with *cumulations*, in the clearest
+of their possible forms. The processes of civilisation among the
+different peoples are in fact to be compared logically with the origin
+of volcanoes or mountain-ranges in Japan, or in Italy, or in America,
+and show us a typical series of consecutive phases, as do these. There
+exists, for instance, in the sphere of any single civilisation an
+economic system, founded first on the exchange of natural products,
+and then on money. There are, or better, perhaps, there are said to
+be, characteristic phases succeeding one another in the arts, such as
+the “typical,” the “individualistic,” and the “subjective” phases. Any
+civilisation may be said to have its “middle ages,” and so on. All these
+are “laws” of course in the meaning of “rules” only, for they are far
+from being elemental, they are not “principles” in any sense. And there
+are other sorts of “rules” at work for exceptional cases: revolutions
+have their rules, and imperialism, for instance, has its rules also.
+
+Now, as the consecutive phases of history have been shown to be
+true cumulations, it follows that the rules which are revealed by
+our analysis, are rules relating to the very origin of cumulations
+also. The real *element* upon which the cumulation-phases, and the
+cumulation-rules together rest, is the human individual as the bearer
+of its psychology. Nobody, it seems to me, has shown more clearly than
+Simmel that it is the human individual, *qua* individual, which is
+concerned in *every* kind of history.
+
+History, viewed as a series of cumulations, may in fact claim to
+satisfy the intellect by “explaining” a good deal of historical facts.
+It explains by means of the elemental factor of individual psychology,
+which every one knows from himself, and by the simple concept that there
+is a cumulation, supported by language and by writing as its principal
+factors, which both of course rest on psychology again. Psychology,
+so we may say, is capable of leading to cumulation phenomena; the
+cumulations in history are such that we are able to understand them by
+our everyday psychology; and history, so far as it is of scientific
+value, consists exclusively of cumulations.
+
+No doubt there is much truth in such a conception of history; but
+no doubt also, it puts history in the second rank as compared with
+psychology; just as geology stands in the second rank as compared with
+chemistry or physics. Geology and human history may lead to generalities
+in the form of rules, but these rules are *known* to be not elemental
+but only cumulative; and moreover, we know the elements concerned in
+them. The elements, therefore, are the real subjects for further studies
+in the realm of philosophy, but not the cumulations, not the rules,
+which are known to be due to accidental constellations. Of course, the
+“single” is the immediate subject of this sort of history, but the
+single as such is emphatically pronounced to be insignificant, and the
+cumulations and the cumulative rules, though “singles” in a higher sense
+of the word, are shown to be anything but elementalities.
+
+Therefore, on a conception of human history such as that of Buckle,
+Taine, Lamprecht, and others, we, of course, ought to take an interest
+in history, because what is “explained” by historical research touches
+all of us most personally every day and every year. But our philosophy,
+our view of the world, would remain the same without history as it is
+with it. We only study history, and especially the history of our own
+civilisation, because it is a field of actuality which directly relates
+to ourselves, just as we study for practical purposes the railway
+time-tables of our own country, but not of Australia; just as we study
+the local time-table in particular.
+
+If the mere *rerum cognoscere causas* is regarded as the criterium of
+science, history of Lamprecht’s type of course is a science, for its
+explanations rest upon the demonstration of the typical constellations
+and of the elemental factor or law from which together the next
+constellations are known necessarily to follow. But history of this kind
+is not a science in the sense of discovering *den ruhenden Pol in der
+Erscheinungen Flucht*.
+
+
+HUMAN HISTORY NOT AN “EVOLUTION”
+
+Quite another view of history has been maintained by Hegel, if his
+explanations about the *Entwicklung des objectiven Geistes* (“the
+development of the objective mind”) may be co-ordinated with our
+strictly logical categories of the possible aspects of history. But I
+believe we are entitled to say that it was a real *evolution* of mankind
+that Hegel was thinking of; an evolution regarding mankind as spiritual
+beings and having an end, at least ideally. One psychical state was
+considered by Hegel to generate the next, not as a mere cumulation
+of elemental stages, but in such a way that each of the states would
+represent an elementality and an irreducibility in itself; and he
+assumed that there was a continuous series of such stages of the mind
+through the course of generations. Is there any sufficient reason in
+historical facts for such an assumption?
+
+The mind “evolves” itself from error to truth by what might be called
+a system of contradictions, according to Hegel, with respect to logic
+as well as to morality; the sum of such contradictions becoming smaller
+and less complicated with every single step of this evolution. No doubt
+there really occurs a process of logical and moral refining, so to say,
+in the individual, and no doubt also, the results of this process,
+as far as attained, can be handed down to the next generation by the
+spoken word or by books. But it is by no means clear, I think, that this
+process is of the type of a real evolution towards an end, so far as it
+relates to the actual series of generations as such. On the contrary,
+it seems to me that we have here simply what we meet everywhere in
+history--a sort of cumulation resting upon a psychological basis.
+
+The dissatisfaction that exists at any actual stage of contradiction,
+both moral and logical, is one of the psychical factors concerned;
+the faculty of reasoning is the other. Now it is a consequence of the
+reasoning faculty that the dissatisfaction continually decreases, or
+at least changes in such a way that each partial result of the logical
+process brings with it the statement of new problems. The number of
+such problems may become less, as the logical process advances, and,
+indeed, there is an ideal state, both logical and moral, in which there
+are no more problems, but only results, though this ideal could hardly
+be regarded as attainable by the *human* mind. In the history of those
+sciences which are wholly or chiefly of the *a priori* type, this
+process of deliverance from contradictions is most advantageously to
+be seen. It is obvious in mechanics and thermodynamics, and the theory
+of matter is another very good instance. A certain result is reached;
+much seems to be gained, but suddenly another group of facts presents
+itself, which had been previously unknown or neglected. The first result
+has to be changed or enlarged; many problems of the second order arise;
+there are contradictions among them, which disappear after a certain
+alteration of what was the first fundamental result, and so on. And the
+same is true about morality, though the difficulties are much greater
+here, as a clear and well-marked standard of measurement of what is good
+and what is bad, is wanting, or at least, is not conceded unanimously.
+But even here there is a consensus on some matters: one would hardly go
+back to slavery again, for instance, and there are still other points
+in morality which are claimed as ideals at least by a great majority of
+moral thinkers.
+
+But all this is not true “evolution,” and indeed, I doubt if such an
+evolution of mankind could be proved at present in the sense in which
+Hegel thought it possible. The process of logical and moral deliverance
+from contradictions *might* come to an end in *one* individual; at least
+that is a logical possibility, or it might come to an end in, say,
+six or ten generations. And there is, unfortunately for mankind, no
+guarantee that the result will not be lost again and have to be acquired
+a second time. All this proves that what Hegel regarded as an evolution
+of the race is only a cumulation. There is nothing evolutionary relating
+to the generations of mankind as such. At least, nothing is proved about
+such an evolution.[165]
+
+[165] On account of the limited size of the earth a certain final stage
+of human civilisation might be expected in a future time; but it would
+be the size of the earth which determined this end, and not the process
+of civilisation itself.
+
+You may call my view pessimistic, and indeed you may be right so far
+as the sum total of human beings as such is in question. But, be it
+pessimistic or not, we are here moving on scientific ground only, and
+have merely to study the probability or improbability of problematic
+facts, and with such a view in our mind, we are bound to say that a
+true logical and moral evolution of mankind is not at all supported
+by known facts. There is a process of logical and moral perfection,
+but this process is *not one*, is not “single” in its actuality; it is
+not connected with the one and single line of history, but only with a
+few generations each time it occurs, or even with one individual, at
+least ideally. And this process is not less a process of cumulation
+than any other sort of development or so-called “progress” in history
+is. Philosophers of the Middle Ages, in fact, sometimes regarded human
+history as *one* evolutionary unity, beginning with the Creation and
+ending with the Day of Judgment; but every one must agree, I think,
+that even under the dogmatic assumptions of orthodoxy history would by
+no means *necessarily* be an “evolution.” Even then the paths taken by
+different individuals or different branches of the human race on their
+way to redemption *can* be regarded as independent lines.
+
+Thus Hegel’s conception of an evolution of mankind, it seems to me,
+fails to stand criticism. By emphasising that there are certain lines of
+development in history which bring with them a stimulus to perfection,
+and that these lines relate to all that is highest in culture, Hegel
+certainly rendered the most important service to the theory of history;
+but in spite of that he has revealed to us only a special and typical
+kind of cumulation process, and nothing like an evolution. We may say
+that the very essence of history lies in this sort of cumulation, in
+this “pseudo-evolution” as we might say; and if we like to become moral
+metaphysicians we might add, that it is for the sake of the possibility
+of this sort of cumulation that man lives his earthly life; the Hindoos
+say so, indeed, and so do many Christians. But even if we were to depart
+from our scientific basis in this way we should not get beyond the realm
+of cumulations.
+
+All this, of course, is not to be understood to affirm that there never
+*will* be discovered any real evolutionary element in human history--in
+the so-called “subconscious” sphere perhaps--but at present we
+certainly are ignorant of such an element.
+
+
+THE PROBLEM OF THE “SINGLE” AS SUCH
+
+If history has failed to appear as a true evolution, and if, on the
+other hand, it reveals to us a great sum of different cumulations, some
+of very great importance, others of minor importance, what then remains
+of the importance of the single historical event in its very singleness?
+What importance can the description of this event have with regard to
+our scientific aims? We could hardly say at present that it appears to
+be of very much importance at all. The historical process as a whole
+has proved to be not a real elemental unit, as far as we know, and such
+elemental units as there are in it have proved to be of importance only
+*for* individual psychology but not *as* history. History has offered
+us only instances of what every psychologist knew already from his own
+experience, or at least might have known if he had conceived his task in
+the widest possible spirit.
+
+But is no other way left by which true history might show its real
+importance in spite of all our former analysis? Can history be saved
+perhaps to philosophical science by any new sort of reasoning which we
+have not yet applied to it here.
+
+As a matter of fact, such new reasoning has been tried, and
+Rickert,[166] in particular, has laid much stress upon the point
+that natural sciences have to do with generalities, while historical
+sciences have to do with the single in its singleness only, and, in
+spite of that, are of the highest philosophical importance. He does not
+think very highly of so-called “historical laws,” which must be mere
+borrowings from psychology or biology, applied to history proper, and
+not touching its character as “history.” We agree with these statements
+to a considerable extent. But what then about “history proper,” what
+about “the single in its very singleness”?
+
+[166] *Die Grenzen der naturwissenschaftlichen Begriffsbildung*,
+Tübingen and Leipzig, 1902.
+
+Let us say at first a few words about this term “single” so very often
+applied by us. In the ultimate meaning of the word, of course, the
+series of actual sensations or “presentations” is the “single” which is
+given “historically” to each individual, and therefore to the writer of
+history also, and in fact, history as understood by Rickert is based
+to a great extent upon this primordial meaning of single “givenness.”
+The word “single,” in his opinion, relates to the *actual and true
+specification* of any event, or group of events, at a given time and
+at a given locality in space, these events possessing an identity of
+their own and never being repeated without change of identity. If the
+subject-matter of history is defined like this, then there are, indeed,
+“Grenzen der naturwissenschaftlichen Begriffsbildung” with regard to
+history, for natural sciences have nothing to do with the single in such
+an understanding of the word.
+
+Rickert says somewhere that history as a real evolution, as one
+totality of a higher order, would cease to be proper history: and he
+is right. History, in fact, would soon lose the character of specific
+attachment to a given space and to a given time, and would lose its
+“non-repeatability,” in the logical sense at least, if it were one
+*unit* in reality: as soon as it was that, it would have become a
+logical generality, an element in nature, so to say, in spite of its
+factual singularity. But history is not obliged to become that, Rickert
+states; and we may add that history in fact cannot become that, because
+it simply proves not to be an evolution as far as we know at present.
+
+But what importance does Rickert attach to his history specified and
+non-repeatably single?
+
+History has a logic of its own, he says; the scheme of its logic is not
+the syllogism, but the *relation to “values.”* So far as the single
+historical facts can be related to values, they are of historical
+importance, and in such a way only does history in its proper sense
+become important in itself and through itself at the same time. Must
+history always lose its historical aspect to become of importance to
+human knowledge? That is the question we asked whilst considering the
+general logical types of the “evolution” and “cumulation” that arose out
+of the analysis of the historical facts of problematic phylogeny. It
+now might seem that this question may be answered, and that it may be
+answered by a clear and simple “No.” The history of mankind, according
+to Rickert, seems to be important in itself, and without borrowing from
+any other branch of study. But is his reasoning altogether cogent and
+convincing?
+
+Has it really been able to attribute to history in the strictest sense
+such an importance for philosophy, for the theory of the universe, “für
+die Weltanschauung,” that history proper may in fact be allowed to take
+its place beside science proper?
+
+The relation to values is not to include any kind of “Bewertung” of
+judgment, Rickert allows. In fact, history of any kind would hardly
+satisfy the reader, if moral judgment were its basis. Every reader, of
+course, has a moral judgment of his own, but, unfortunately, almost
+every reader’s judgment is different from his neighbour’s, and there
+is no uniformity of moral principles as there is of geometrical ones.
+We shall come back to this point. At present we only state the fact
+that indeed moral judgment can never be the foundation of history, and
+that Rickert was very right to say so: it is enough to put the names
+of Tolstoy and Nietzsche together to understand how devoid of even
+the smallest general validity would be a history resting upon moral
+principles.
+
+But what then are the “values” of Rickert to which history has to
+relate, if moral values in their proper sense have to be excluded? It is
+here that his discussions begin to become obscure and unsatisfactory,
+and the reason is fairly intelligible. He is trying to prove the
+impossible; he wants to put history beside science in its real
+philosophical importance, in spite of the fact that all evidence to
+establish this is wanting.
+
+These “values,” to which every historical act in its singularity has to
+be related in order to become an element of real history, are they after
+all nothing but those groups of the products of civilisation which in
+fact absorb the interest of men? Is it to groups of cultural phenomena,
+such as arts, science, the State, religion, war, economics, and so on,
+that “historical” facts have to be related? Yes, as far as I understand
+our author, it is simply to these or other even less important groups
+of cultural effects--cultural “cumulations,” to apply our term--that a
+single action of a man or a group of men must bear some relation in
+order to become important historically.
+
+But what does that mean? Is the relation to such “values” to be
+regarded as really rendering history equal to the sciences of nature in
+philosophical importance?
+
+In the first place, there is no more agreement about such “values” than
+there is in the field of morals. Imagine, for instance, a religious
+enthusiast or recluse writing history! I fancy there would be very
+little mention of warriors and politicians: war and politics would
+not be “values” in *any* sense to such a man. And we know that there
+are others to whom those products of civilised life rank amongst the
+first. Rickert well notes that there is one great objection to his
+doctrine--the character of universality[167] is wanting to his history,
+or rather to the values forming its basis; for there cannot be, or at
+least there actually is not at present, a *consensus omnium* with regard
+to these “values.”
+
+[167] The word “universality” to be understood here in quite an
+unpretentious quasi-popular meaning, not strictly epistemologically.
+
+I am convinced that Rickert is right in his conception of real “history”
+as the knowledge of the single acts of mankind. But this conception
+proves just the contrary of what Rickert hoped to prove; for history in
+this sense is moulded by the actual products of culture, that is, by
+the effects which actually exist as groups of cultural processes, and
+it cannot be moulded by anything else; the historian correlates history
+with what *interests* him personally.
+
+Here now we have met definitively the ambiguous word: history indeed
+is to end in “interest” and in being “interesting.” There is nothing
+like a real “value” in any sense underlying history; the word *value*
+therefore would better give place to the term “centre of interest”--a
+collection of stamps may be such a “centre.” History, then, as the
+knowledge of cultural singularities, is “interesting,” and its aspects
+change with the interests of the person who writes history: there is no
+commonly accepted foundation of history.[168]
+
+[168] To avoid mistakes I wish to say here most emphatically that,
+according to Rickert, the method of history is regarded as completely
+*free* from subjectivity as soon as its “values” are once *established*.
+But this cannot avail to save the theory.
+
+And it follows that history as regarded by Rickert cannot serve as
+the preliminary to philosophy. It *may* be[169] of use for personal
+edification or for practical life: granting that the “centres of
+interest” as referred to are of any real ethical or at least factual
+importance. But you may take away from history even the greatest
+personalities, and your view of the universe, your philosophy, would
+remain the same, except of course so far as these personalities
+themselves have contributed to philosophy in any way.
+
+[169] This is a rather optimistic conception of “history.” Personally, I
+must confess that even its emotional and practical importance seems to
+me to be at least diminished by the retarding effects which all sorts
+of “historical” considerations--in science as well as in arts and in
+public life--carry with them. All real progress is non-historical--and
+its champions almost always have become martyrs: this fact seems not to
+recommend history as a means of education, except for persons of a very
+strong character.
+
+Now, on the other hand, it is worth noticing that, even if there were
+generally accepted “values,” history as the doctrine of singularities
+would be deprived of philosophical importance. Its single cases would
+then be merely *instances* of certain types of actions and occurrences
+which have been proved to be “valuable,” *i.e.* to be centres of
+interest, before-hand. Rickert has observed that the relation to
+any judgments about moral values would render history unhistorical,
+for the generalities to which it is related would be the main thing
+in such a case. But he did not notice, as far as I can see, that
+history, if related to *any* “values” whatever--if there were any
+generally conceded--would become “non-historical” just as well: for the
+*generalities* as expressed in the “values” would be the main thing in
+this case also. In fact, there is no escape from the dilemma:--either no
+general centres of interest, and therefore a mere subjective “history”;
+or general “values,” and therefore history a mere collection of
+instances.
+
+The “limits of concepts in natural sciences” then are the same as the
+limits of *intellectual* concepts in general. For intellectual, *i.e.*
+logical, “values” are the only centres of interest that can lay claim
+to universality. There are indeed other groups of important concepts,
+the ethical ones, but they are outside intellectuality and may enter
+philosophy only as problems, not as solutions. Therefore, history in
+its true sense, even if related to the ethical group of concepts,
+has no bearing on philosophy. Philosophically it remains a sum of
+contingencies, in which certain laws of cumulation and certain series of
+cumulation may be discovered. But these series and these laws, if taken
+scientifically, only offer us instances of psychological elementalities.
+They also might be instances of primary ethical states and relations, if
+there were such relations of more than a mere subjective and personal
+validity, which at present at least seems not to be the case.
+
+
+
+
+CONCLUSIONS ABOUT SYSTEMATICS AND HISTORY IN GENERAL
+
+
+We have finished our analysis of the history of mankind as the only
+instance of an historical biological process that is actually known to
+exist and is not only assumed hypothetically.
+
+What we have learnt from this analysis, though certainly important in
+itself, has not afforded us any new result for theoretical biology.
+
+The history of mankind is proved to be of philosophical importance,
+at present, so far only as it offers instances to the science of
+psychology; besides that it may be of value and importance to many
+conditions of practical and emotional life.
+
+There is only one science, and only one kind of logic too. “In one sense
+the only science”--that was the predicate attached to natural sciences
+by Lord Gifford, as you will remember from our first lecture. It is not
+without interest to note that at the end of our course of this year,
+we find occasion to realise on what a deep insight into logical and
+philosophical relations that sentence was grounded.
+
+We now leave the theory of human history, which has been to us nothing
+more than a branch of biological phylogeny in general. We have dealt
+with it from quite a simple realistic point of view, not burdened by any
+epistemology. We have taken psychical states as realities, just as we
+have taken as realities all parts of the animal body; and it seems to
+me that we were entitled to do so, as it was only history *about* the
+actions of men we were dealing with, not their actions themselves. Next
+summer we shall begin with studying action as action, and then, in fact,
+a well-founded epistemology will be among our first requirements. And
+history also will come on the scene once more.
+
+It is the main result of our last chapters, devoted to systematics,
+transformism, and human history in particular, that no conclusions
+really useful for further philosophical discussion can at present be
+gained from these topics; there either is too little actual knowledge,
+or there are only combinations of natural elementalities, but no
+elementalities of any new kind.
+
+To sum up: we expected that a rational system might be a biological
+result of the future, but we could not claim at all to possess such a
+system. We said that transformism might be proved one day to be a true
+evolution, governed by one immanent principle, which then would have to
+be regarded as a new primary factor in nature, but we did not know the
+least about that principle.
+
+Human history, on the other hand--that is, the only historical process
+concerned with life that is actually known to have occurred--could not
+teach us anything of an elemental character, since human history, at
+present at least, did not appear to us as a true evolution, but only as
+a sum of cumulations, and the singularities of this history, taken by
+themselves, could only be of practical or emotional interest.
+
+Thus it is from the study of the living *individual* only, that we
+have so far gained elemental principles in biology. The analysis of
+individual morphogenesis and of individual inheritance has yielded
+us the concept of entelechy as the chief result of the first part of
+our lectures. We shall be able to get more proofs of the autonomy of
+the individual life in the beginning of the second part; indeed, the
+beginning of that part will bring us to a full understanding of what the
+living individual is, and what it is not. And then the real philosophy
+of life, that is, the philosophy of the individual, will occupy us for
+the greater half of our lectures of next summer.
+
+
+
+
+INDEX
+
+
+  Absolute, 5
+
+  Acclimatisation, 191
+
+  Acquired characters, 217, 276 f.
+
+  Adaptation (definition), 166, 171, 185
+    to changes from without, 172 ff.
+    functional, 114, 176 ff.
+    and Lamarckism, 272, 280
+    mechanical, 177 f.
+    morphological, 168 ff.
+    physiological, 184 ff.
+    primary and secondary, 188 f.
+
+  Adaptedness, 186 f.
+
+  *Adiantum*, 279
+
+  Adventitious, 55, 74, 111, 221
+
+  Albumen, 200
+
+  Allelomorphs, 231
+
+  Amphibious plants, 172 ff.
+
+  Annelids, 65, 70, 221
+
+  Answering reaction, 181
+
+  Anti-bodies, 206 f.
+
+  Antitoxins, 207 f.
+
+  *A priori*, 6
+
+  Aristotle, 144
+
+  *Ascaris*, 93
+
+  *Aspergillus*, 195
+
+  Assimilation, 17
+
+  Atrophy, 178
+
+  Autonomy of life, 143, 224 f., 324
+
+
+  Babák, 177
+
+  Baer, C. E. v., 48 f. 282
+
+  Bateson, 229 ff., 238
+
+  Bayliss, 204, 212
+
+  *Begonia*, 221
+
+  Bergson, 305
+
+  Berkeley, 6
+
+  Berthold, 91
+
+  Biogenetisches Grundgesetz, 248
+
+  Biology, 8 ff., 15 f.
+
+  Blaringhem, 238, 276
+
+  Blastoderm, 39
+
+  Blastomeres, 36, 59, 61 f., 79
+
+  Blastula, 37, 61, 79
+
+  Blumenbach, 26
+
+  Boirivant, 174
+
+  Bonnet, 26
+
+  Boveri, 29, 60, 95, 235 f.
+
+  Buckle, 308, 310
+
+  Bunge, v., 248
+
+  Bütschli, 91
+
+
+  Calcium, 97
+
+  Calkins, 33
+
+  Cambium, 120, 183, 220
+
+  Catalysis, 164, 203
+
+  Categories, 6 f.
+
+  Cause, 99 ff.
+
+  Cell, 27 f.
+    -division, 28 ff., 53, 94
+    -lineage, 58, 70
+    -theory, 27 f.
+
+  Chemical theory (of morphogenesis), 134 ff.
+
+  Chemistry, systematics of, 244.
+
+  Child, C. M., 180
+
+  Chromatic regulations, 197
+
+  Chromatin, 28 f.
+
+  Chromosomes, 30, 237
+
+  Chun, 66
+
+  Classification, 246 f.
+
+  *Clavellina*, 129, 154, 162 f.
+
+  Cleavage, 35 ff., 53, 58, 60, 63, 71, 92
+
+  Colloids, 187
+
+  Compensatory process, 112
+
+  Complex potencies, 112, 120
+
+  Conic sections, 243
+
+  Conjugation, 33
+
+  Conklin, 86
+
+  Contingency, 218, 284 ff. 304
+
+  Continuity of germ-plasm, 215, 227
+
+  Cope, 273
+
+  Correlation (of masses), 93
+    (of parts), 247
+
+  Correns, 228
+
+  Crampton, 70 f.
+
+  Crayfish, 105
+
+  Ctenophores, 66
+
+  Cumulation, 301 ff., 308 ff., 314, 317
+
+  Cuvier, 247
+
+
+  Darwin, Ch., 260 ff., 271, 283
+
+  Darwinism, 260 ff., 271, 283 ff., 293 ff., 304
+
+  Davenport, 191, 206
+
+  Delage, 32
+
+  Descent, theory of, 250 ff.
+
+  Description, 12, 50
+
+  Detto, 172
+
+  Directive stimuli, 102 ff.
+
+  Doncaster, 232
+
+  Dreyer, 92
+
+
+  *Echinus*, 27, 33 ff., 60 ff., 68, 81, 85, 87,
+    98, 104, 108, 111, 154, 232, 235
+
+  Ectoderm, 41, 81, 122
+
+  Egg, 31, 33 f.
+
+  Ehrlich, 207 f.
+
+  Eimer, 292
+
+  Elementary organs, 46 ff.
+    processes, 46 ff.
+
+  Elements of nature, 9
+
+  Embryo, 44
+    frog’s, 59, 65, 67
+    half, 59, 61, 66 ff.
+    whole, 61, 67 f.
+
+  Endoderm, 41, 81
+
+  Entelechy, 143 f., 224 f., 295
+
+  Entwickelungsmechanik, 57, 70, 78, 241
+
+  Enumeration, 297, 300
+
+  Enzymes, 164, 203
+
+  Epigenesis, 26, 45, 54, 72, 144, 301
+
+  Equifinality (of restitutions), 159 f.
+
+  Equipotential, 83
+
+  Eschenhagen, 195
+
+  Evolutio, 26, 45 f., 54, 59, 61, 64, 72, 144, 205, 301
+
+  Evolution, 8, 21, 46, 250, 301, 305, 311 ff., 317
+
+  Experience, 7 f., 12, 212
+
+  Experiment, 51, 56 f.
+
+  “Explaining,” 51, 309
+
+  Explicit potency, 84
+
+
+  Fasting, 199 f.
+
+  Ferments, 164, 203 f.
+
+  Fertilisation, 32 ff.
+
+  Fischer, 278
+
+  Foges, 107
+
+  Form, closed or open, 49
+
+  Form, organic, specific, 16 ff., 25, 92, 293 ff.
+
+  Forma accidentalis, 293
+    essentialis, 294 f.
+
+  Formative stimuli, 102 ff., 113, 118, 133
+
+  Francé, 158, 239
+
+  Frédéricq, 196
+
+  Frog, embryo of, 59, 65, 67
+
+  Fromm, 205
+
+  Function (mathematical), 80
+
+  Fungi, metabolism of, 201
+
+
+  Gaidukow, 197 f.
+
+  Galls, 101
+
+  Galton, 228, 238
+
+  Gamble and Keeble, 198
+
+  Gastrula, 41, 61, 81
+
+  Gautier, 239
+
+  Geographical distribution, 251 f.
+
+  Geometry, solid, 243
+
+  Germ-layers, 41, 44, 61
+    -lineage, 215
+    -plasm, 52, 215
+
+  Gifford, Lord, 1 ff., 322
+
+  Godlewski, 105, 155, 235
+
+  Goebel, 116
+
+  Goethe, 247
+
+  Goette, 48, 56, 214
+
+  Goltz, 181
+
+  Growth, 30, 93 f.
+
+  Gruber, 236
+
+
+  Haeckel, 37, 41
+
+  Half-embryo, 59, 61, 66 ff.
+
+  Haller, A. v., 26
+
+  Harmony, 107 ff., 117, 295
+
+  Hausmann, 206
+
+  Heat production, 193
+
+  Hegel, 307, 311 ff.
+
+  Herbst, 96 ff., 102, 104 ff., 172, 177, 200, 232, 236
+
+  Heredity, 21, 52
+
+  Hering, 216 f.
+
+  Hertwig, O., 60, 65
+
+  Hertwig, R., 32 f., 60, 107
+
+  His, 56, 93
+
+  History, 2, 14, 21, 250, 257, 297 ff.
+    of mankind, 306 ff.
+
+  Holmes, 180
+
+  Hume, 6
+
+  Hypertrophy, 112, 114
+
+  Hypertypy, 112
+
+
+  Idealism, 5, 7
+
+  Immunity, 204 ff.
+
+  Implicit potency, 84
+
+  Improvement (of morphogenesis), 212
+
+  Indifferent cells, 182
+
+  Inflammation, 206
+
+  Inheritance, 35, 214 ff.
+    of acquired characters, 217, 275 ff., 290
+
+  Irritability, 190 ff.
+
+
+  Jacoby, 207
+
+  Jaeger, 214
+
+  Jennings, 218
+
+
+  Kammerer, 176, 280
+
+  Kant, 6 f.
+
+  Kirchhoff, 50
+
+  Klebs, 96, 170, 180, 238, 276
+
+  Kölliker, 292
+
+  Korshinsky, 239
+
+  Krašan, 221, 251
+
+
+  Lamarck, 271 f., 291
+
+  Lamarckism, 271 f., 284 ff., 293 ff., 304
+
+  Lamprecht, 308, 310
+
+  Larva, 41 f., 44
+
+  Law of nature, 13, 16
+
+  Leibniz, 6
+
+  Lens (of eye), 105, 221
+
+  Liebmann, 256
+
+  Life, 9 f., 16, 21
+
+  Lillie, R. S., 236
+
+  Limits of regulability, 212
+
+  Lithium, 99
+
+  “Living,” 9, 16
+
+  Localisation, 101, 103, 118 ff.
+
+  Locke, 6
+
+  Loeb, J., 32, 102, 164, 179, 196, 236
+
+  Loeb, L., 208
+
+  Lyon, 87
+
+
+  MacDougal, 238 f., 276
+
+  Machine (definition), 139
+
+  Machine-theory of life, 138 ff., 187, 210
+
+  Maillard, 196
+
+  Manifoldness, 25 f., 30, 45
+    intensive, 144
+
+  Materialism, 283
+
+  Materials, transport of, 194
+
+  Matter, theory of, 8
+
+  Maturation, 31, 87
+
+  Mayenburg, v., 195
+
+  Means, of morphogenesis, 89 ff., 101, 113, 118, 228, 234
+
+  Memory, 216 f.
+
+  Mendel, 229 f.
+
+  Merrifield, 198
+
+  Mesenchyme, 39, 41, 104, 111, 151 f.
+
+  Metabolic regulations, 198 f.
+
+  Metabolism, 16, 184
+    of fungi, 201
+
+  Metschnikoff, 206
+
+  Micromeres, 36, 60
+
+  Miehe, 116
+
+  Mill, J. S., 57
+
+  *Mimosa*, 191
+
+  Minkiewicz, 198
+
+  Modification, 277
+
+  Molluscs, 70 f., 86
+
+  Morgan, T. H., 32, 66 f., 95, 107, 114 f., 162, 230
+
+  Morphaesthesia, 157
+
+  Morphogenesis, 20, 52, 76, 112, 118 f.
+
+  Morphology, 12
+
+  Movements, organic, 17
+
+  Mutations, 237 f., 276, 291
+
+
+  Nägeli, 266, 292
+
+  Nathansohn, 196
+
+  Natural selection, 261 f., 290
+
+  Nature, 5 ff.
+
+  Němec, 116
+
+  Newport, 57
+
+  Newt (regeneration of), 155, 221 f.
+
+  Noll, 146, 157 f.
+
+  Nomothetic, 14 f.
+
+  Normal, 78
+
+  Nuclear division, 28 f., 62, 64 f., 72, 235
+
+  Nucleus, 28, 35
+    rôle of nucleus in inheritance, 233 f.
+
+
+  Organ-forming substances, 117
+
+  *Oscillariae*, 197
+
+  Osmotic pressure, 93, 187, 194 f.
+
+  Overton, 196 f.
+
+  Oxidation, rôle of, 198 f.
+
+
+  Palaeontology, 252
+
+  Parallelism (psycho-physical), 146
+
+  Parthenogenesis, 32
+
+  Pauly, 146, 217, 273 f.
+
+  Pawlow, 204, 210, 212
+
+  Pearl, R., 212
+
+  Pfeffer, 195, 201
+
+  Phagocytosis, 206
+
+  Phenomenon, 5 f.
+
+  Philosophy, natural, 4
+    of nature, 4, 7, 9
+    of the organism, 9, 15
+
+  Phylogeny, 255, 291, 297, 304 ff.
+
+  Physiology, 12
+    of development (morphogenesis), 20
+
+  *Planaria*, 130, 155, 162 f., 200
+
+  Plants, 48 f.
+
+  Plato, 2
+
+  Pluteus, 42
+
+  Poisons, 205 ff.
+
+  Pole, 36
+
+  Polarity, 106
+
+  Potencies, complex, 112, 120
+    explicit, 84
+    implicit, 84
+    primary, 84, 111
+    prospective, 77 ff., 83, 89, 118, 125, 241
+    secondary, 84, 110
+
+  Poulton, 198
+
+  Precipitin, 207 f.
+
+  Pressure experiments, 63, 141
+
+  Primary potency, 84, 111
+    purposefulness, 146, 287
+    regulation, 85, 174, 188
+
+  Progress, 305
+
+  Pronuclei, 55
+
+  Prospective potency, 77 ff., 83, 89, 118, 125, 241
+    value, 77 f., 80, 122
+
+  Protista (Protozoa), 27, 130, 236
+
+  Protoplasm, 28, 30
+    morphogenetic rôle of, 67
+
+  Przibram, 112, 248
+
+
+  Rádl, 247
+
+  Rauber, 235
+
+  Reaction, answering, 181
+
+  Reciprocity of harmony, 156 f.
+
+  Re-differentiation, 75, 111, 163
+
+  Regeneration, 55, 74, 105, 111, 221
+    super-, 115 f.
+
+  Regulation, 68, 73, 85, 111, 165
+    defined, 166
+    metabolic, 198 f.
+    secondary, 85, 165, 188
+
+  Reinke, 146
+
+  Restitution, 21, 74, 110, 112 ff.
+    defined, 166
+    and Darwinism, 267
+    and Lamarckism, 286
+    of second order, 158
+
+  Retina, 191
+
+  Retro-differentiation, 163 f.
+
+  Rhumbler, 93
+
+  Ribbert, 114
+
+  Rickert, 315 ff.
+
+  Roux, 26, 48, 55 ff., 66 f., 76, 89, 92 f., 108, 161, 176 f., 241
+
+  Rubner, 193
+
+
+  Sachs, 117
+
+  Sadebeck, 279
+
+  *Salamandra*, 175, 281
+
+  Schneider, 146
+
+  Schultz, E., 200
+
+  Schultze, O., 67
+
+  Schwendener, 177
+
+  Science, 14, 297
+    natural, 1 ff.
+    rational, 12
+
+  Sea-urchin, *see* Echinus
+
+  Secondary potency, 84, 110
+    regulation, 85, 165, 188
+
+  Secretion, internal, 116, 200
+
+  Segmentation, 35
+
+  Selective qualities (of tissues), 186
+
+  Self-differentiation, 108
+
+  Semon, 216 f.
+
+  Sex, 107
+
+  Single, the, 315 ff.
+
+  Skeleton, 40 ff., 44, 47, 92
+
+  Spemann, 105
+
+  Spermatozoon (spermia), 32 ff.
+
+  Splitting (of hybrids), 229 f.
+
+  Stahl, 197
+
+  Standfuss, 278
+
+  Starfish, 44, 81, 122
+
+  Starling, E., 116, 204, 212
+
+  *Stentor*, 131
+
+  Stimuli, directive, 102 ff.
+    formative, 102 ff., 113, 118, 133
+    of restitutions, 113 f.
+
+  Structure of protoplasm, 66, 69, 72 f. 85, 88
+
+  Substance, living, 17
+
+  Sumner, 196
+
+  Super-regeneration, 115 f.
+
+  Surface-tension, 91
+
+  Sutton, 230
+
+  Symmetry, 39, 68, 70, 72, 89, 98
+
+  System, combined types of, 153 ff.
+    complex, 219 f.
+    complex-harmonious, 155
+    equipotential, 120
+    harmonious-equipotential, 121 ff., 151 f.
+    mixed-equipotential, 154
+    morphogenetic, 119 f., 163, 241
+
+  Systematics, 14 ff., 21, 243 f., 253, 264, 293, 296
+
+
+  Taine, 308, 310
+
+  Theology, natural, 1 ff.
+
+  Thomson, J. A., 16
+
+  Thymus, 204
+
+  Thyroid, 204
+
+  Tissue, 38
+
+  Toxins, 207 f.
+
+  Transformism, 251
+
+  Truth, 7
+
+  Tschermak, 228
+
+  *Tubularia*, 126 ff., 133, 158 ff.
+
+  Type, 48, 247 f., 282, 291
+
+
+  “Understanding” (historically), 302
+
+  Universality, postulate of, 148 f.
+
+  Universe, 5
+
+  Univocality, principle of, 161
+
+
+  “Values,” 317 ff.
+    prospective, 77 f., 80, 122
+
+  Variation, 218, 237 f., 276
+
+  Variation, fluctuating, contingent, 264 f., 273 f., 282, 290
+
+  Vernon, 232, 238
+
+  Vitalism, 143, 145 f., 210 f., 224 f., 234, 240 f., 272, 277
+
+  Vöchting, 174, 179 f., 182, 221
+
+  Volition, acts of, 274
+
+  Vries, de, 228, 238 f.
+
+
+  Wallace, 292
+
+  Ward, J., 8, 143
+
+  Weber, law of, 191
+
+  Weinland, 202
+
+  Weismann, 33, 52 ff., 58 f., 72, 74 f., 103,
+    111, 138, 214 f., 237, 277 f.
+
+  Weldon, 238
+
+  Whole, the, 28, 80, 117
+    -embryo, 61, 67 f.
+
+  Wigand, 255, 266, 292
+
+  Wilson, E. B., 27, 65, 70 f., 86 f., 107
+
+  Windelband, 13 f.
+
+  Winkler, 116, 221
+
+  Winterstein, 199
+
+  Wolff, C. F., 26
+
+  Wolff, G., 105, 146, 255, 266, 287 f.
+
+  Wolff, J., 177
+
+
+  Yung, 177
+
+
+  Zeleny, 112, 115, 212
+
+  Zur Strassen, 93
+
+
+                                THE END
+
+           *Printed by* R. & R. CLARK, LIMITED, *Edinburgh*.
+
+
+
+
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+End of the Project Gutenberg EBook of The Science and Philosophy of the
+Organism, by Hans Driesch
+
+*** END OF THE PROJECT GUTENBERG EBOOK 44388 ***
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+<div>*** START OF THE PROJECT GUTENBERG EBOOK 44388 ***</div>
+
+<div class="transnote"><p><b>Transcriber&rsquo;s notes</b>:</p>
+
+<p>In this transcription, page numbers are shown in the right
+margin, and page footnotes (renumbered in consecutive order) are
+grouped together at the end of the book. Hyperlinks to footnotes
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+aqua highlighting when the mouse pointer hovers over them. The
+footnotes are themselves hyperlinked back to the originating marker
+to facilitate easy return to the text. A red dashed underline as
+shown <ins title="Comment">here</ins> indicates the presence of a
+transcriber&rsquo;s comment; scrolling the mouse pointer over such text
+will reveal the comment.</p>
+
+<p>The rare spelling typos noted in the original text have
+been corrected silently (e.g. invividual-->individual,
+hyberbola-->hyperbola) but inconsistent use of the ligature æ/ae (e.g.
+palæontology/palaeontology), inconsistent use of alternative spellings
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+have been left as in the original. Minor punctuation typos have been
+corrected silently (e.g. index entries with missing commas). The
+abbreviation viz. appears in both roman and italic font.</p>
+
+<p>Formatting of entries in the Table of Contents does not accurately
+match that of the corresponding headings in the text, particularly the
+heading Pt.I-B-3 which contains an extraneous α.</p>
+
+<p>In Figure 12 caption, multiple ditto marks have been replaced by the
+relevant text for greater clarity.</p>
+
+</div>
+
+
+<p><span class="pagenum hide" title="i"><a name="Page_i" id="Page_i"></a></span></p>
+
+<p class="tac fs160 mt15em mb2em">THE SCIENCE AND PHILOSOPHY<br />
+OF THE ORGANISM</p>
+<p><span class="pagenum hide" title="ii"><a name="Page_ii" id="Page_ii"></a></span></p>
+
+<table class="fs65 mb2em" border="0" cellpadding="4" cellspacing="0" summary="International addresses of publisher">
+<col width="30%" /><col width="70%" />
+<tr><td class="tac" colspan="2">AGENTS</td></tr>
+<tr class="vat"><td><span class="smcap">America</span></td><td><span class="smcap">The Macmillan Company<br />64 &amp; 66 Fifth Avenue, New York</span></td></tr>
+<tr class="vat"><td><span class="smcap">Australasia</span></td><td><span class="smcap">The Oxford University Press, Melbourne</span></td></tr>
+<tr class="vat"><td><span class="smcap">Canada</span></td><td><span class="smcap">The Macmillan Company of Canada, Ltd.<br />27 Richmond Street West, Toronto</span></td></tr>
+<tr class="vat"><td><span class="smcap">India</span></td><td><span class="smcap">Macmillan &amp; Company, Ltd.<br />Macmillan Building, Bombay<br />309 Bow Bazaar Street, Calcutta</span></td></tr>
+</table>
+<p><span class="pagenum hide" title="iii"><a name="Page_iii" id="Page_iii"></a></span></p>
+
+
+<h1 class="lh150 mt15em"><span class="fs65">THE</span><br />
+SCIENCE AND PHILOSOPHY<br />
+OF THE ORGANISM</h1>
+
+<p class="tac ls01em mb2em lh150">THE GIFFORD LECTURES DELIVERED BEFORE<br />
+THE UNIVERSITY OF ABERDEEN<br />
+IN THE YEAR 1907<br /><br /></p>
+
+<p class="tac"><span class="fs85 lh300">BY</span><br />
+<span class="fs120">HANS DRIESCH, <span class="smcap">Ph.D.</span></span><br />
+<span class="fs50">HEIDELBERG</span><br /><br /><br /><br />
+<span class="figcenter" style="width: 321px;">
+<img id="logo" src="images/logo.png" width="53" height="52" alt="" /></span>
+<br /><br /><br /></p>
+
+
+<p class="tac ls01em mb2em lh150">LONDON<br />
+ADAM AND CHARLES BLACK<br />
+1908</p>
+
+<p class="tac fs65"><em>All rights reserved</em></p>
+<hr class="short" />
+<p><span class="pagenum hide" title="iv"><a name="Page_iv" id="Page_iv"></a></span><br /><span class="pagenum" title="v"><a name="Page_v" id="Page_v"></a></span></p>
+
+
+
+
+<h2>PREFACE</h2>
+
+
+<p>This work is not a text-book of theoretical biology; it is a
+systematic presentment of those biological topics which bear
+upon the true philosophy of nature. The book is written
+in a decidedly subjective manner, and it seems to me that
+this is just what “Gifford Lectures” ought to be. They
+ought never to lose, or even try to lose, their decidedly
+personal character.</p>
+
+<p>My appointment as Gifford Lecturer, the news of which
+reached me in February 1906, came just at the right
+moment in the progress of my theoretical studies. I had
+always tried to improve my previous books by adding notes
+or altering the arrangement; I also had left a good deal
+of things unpublished, and thus I often hoped that I might
+have occasion to arrange for a new, improved, and enlarged
+edition of those books. This work then is the realisation
+of my hopes; it is, in its way, a definitive statement of all
+that I have to say about the Organic.</p>
+
+<p>The first volume of this work, containing the lectures
+for 1907&mdash;though the division into “lectures” has not been
+preserved&mdash;consists of Parts I. and II. of Section A, “The
+Chief Results of Analytical Biology.” It gives in Part I. a<span class="pagenum" title="vi"><a name="Page_vi" id="Page_vi"></a></span>
+shortened, revised, and, as I hope, improved account of what
+was published in my <cite lang="de" xml:lang="de">Analytische Theorie der organischen
+Entwickelung</cite> (1894), <cite lang="de" xml:lang="de">Die Localisation morphogenetischer
+Vorgänge; ein Beweis Vitalistischen Geschehens</cite> (1899), and
+<cite lang="de" xml:lang="de">Die organischen Regulationen</cite> (1901), though for the professed
+biologist the two last-named books are by no means
+superseded by the new work. Part II. has never been
+published in any systematic form before, though there are
+many remarks on Systematics, Darwinism, etc., in my
+previous papers.</p>
+
+<p>The second volume&mdash;to be published in the autumn,
+after the delivery of the 1908 lectures&mdash;will begin with
+the third and concluding part of the scientific section, which
+is a very carefully revised and rearranged second edition of
+my book, <cite lang="de" xml:lang="de">Die “Seele” als elementarer Naturfactor</cite> (1903).
+The greater part of this volume, however, will be devoted
+to the “Philosophy of the Organism,” <i>i.e.</i> Section B, which, in
+my opinion, includes the most important parts of the work.</p>
+
+<p>Some apology is needed for my presuming to write in
+English. I was led to do so by the conviction, mistaken
+perhaps, that the process of translation would rob the
+lectures of that individual and personal character which, as
+I said before, seems to me so much to be desired. I wished
+nothing to come between me and my audience. I accordingly
+wrote my manuscript in English, and then submitted
+it to linguistic revision by such skilled aid as I was able to
+procure at Heidelberg. My reviser tells me that if the
+result of his labours leaves much to be desired, it is not to
+be wondered at, but that, being neither a biologist nor a<span class="pagenum" title="vii"><a name="Page_vii" id="Page_vii"></a></span>
+philosopher, he has done his best to make me presentable
+to the English reader. If he has failed in his troublesome
+task, I know that it is not for want of care and attention,
+and I desire here to record my sense of indebtedness to him.
+He wishes to remain anonymous, but I am permitted to say
+that, though resident in a foreign university, he is of
+Scottish name and English birth.</p>
+
+<p>My gratitude to my friends at Aberdeen, in particular
+to Professor and Mrs. J. A. Thomson, for their hospitality
+and great kindness towards me cannot be expressed here;
+they all know that they succeeded in making me feel quite
+at home with them.</p>
+
+<p>I am very much obliged to my publishers, Messrs.
+A. and C. Black, for their readiness to fulfil all my wishes
+with respect to publication.</p>
+
+
+<p>The lectures contained in this book were written in
+English by a German and delivered at a Scottish university.
+Almost all of the ideas discussed in it were first conceived
+during the author’s long residence in Southern Italy. Thus
+this book may be witness to the truth which, I hope, will
+be universally recognised in the near future&mdash;that all
+culture, moral and intellectual and aesthetic, is not limited
+by the bounds of nationality.</p>
+
+<p class="tar mr2em">HANS DRIESCH.<br /><br /></p>
+
+<p><span class="smcap fs85">Heidelberg</span>, <i>2nd January 1908</i>.<br /></p>
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="viii"><a name="Page_viii" id="Page_viii"></a></span><br /><span class="pagenum" title="ix"><a name="Page_ix" id="Page_ix"></a></span></p>
+
+
+
+<h2>CONTENTS OF THE FIRST VOLUME</h2>
+
+<p class="tac">THE PROGRAMME</p>
+
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal"></td><td class="tar"><span class="fs85">PAGE</span></td></tr>
+<tr><td class="tal">On Lord Gifford’s Conception of “Science”</td><td class="tar"><a href="#Page_1">1</a></td></tr>
+<tr><td class="tal">Natural Sciences and “Natural Theology”</td><td class="tar"><a href="#Page_3">3</a></td></tr>
+<tr><td class="tal">Our Philosophical Basis</td><td class="tar"><a href="#Page_5">5</a></td></tr>
+<tr><td class="tal">On Certain Characteristics of Biology as a Science</td><td class="tar"><a href="#Page_9">9</a></td></tr>
+<tr><td class="tal">The Three Different Types of Knowledge about Nature</td><td class="tar"><a href="#Page_13">13</a></td></tr>
+<tr><td class="tal">General Plan of these Lectures</td><td class="tar"><a href="#Page_15">15</a></td></tr>
+<tr><td class="tal">General Character of the Organic Form</td><td class="tar"><a href="#Page_19">19</a></td></tr>
+</table></div>
+
+
+<p class="tac">SECTION A.&mdash;THE CHIEF RESULTS OF ANALYTICAL BIOLOGY</p>
+
+<p class="tac">PART I.&mdash;THE INDIVIDUAL ORGANISM WITH REGARD TO<br />FORM AND METABOLISM</p>
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal pb05em"><i>A.</i> ELEMENTARY MORPHOGENESIS&mdash;</td><td></td></tr>
+<tr><td class="tal pl2em">Evolutio and Epigenesis in the old Sense</td><td class="tar"><a href="#Page_25">25</a></td></tr>
+<tr><td class="tal pl2em">The Cell</td><td class="tar"><a href="#Page_27">27</a></td></tr>
+<tr><td class="tal pl2em">The Egg: its Maturation and Fertilisation</td><td class="tar"><a href="#Page_31">31</a></td></tr>
+<tr><td class="tal pl2em">The First Developmental Processes of Echinus</td><td class="tar"><a href="#Page_33">33</a></td></tr>
+<tr><td class="tal pl2em">Comparative Embryology</td><td class="tar"><a href="#Page_44">44</a></td></tr>
+<tr><td class="tal pl2em">The First Steps of Analytical Morphogenesis</td><td class="tar"><a href="#Page_45">45</a></td></tr>
+<tr><td class="tal pl2em pb15em">The Limits of Pure Description in Science</td><td class="tar pb15em"><a href="#Page_50">50</a></td></tr>
+<tr><td class="tal pb05em"><i>B.</i> EXPERIMENTAL AND THEORETICAL MORPHOGENESIS&mdash;</td></tr>
+<tr><td class="tal pl2em pr4em">1. <span class="smcap">The Foundations of the Physiology of Development. “Evolutio” and “Epigenesis”</span></td><td class="tar vab"><a href="#Page_52">52</a></td></tr>
+<tr><td class="tal pl4em">The Theory of Weismann</td><td class="tar vab"><a href="#Page_52">52</a></td></tr>
+<tr><td class="tal pl4em">Experimental Morphology</td><td class="tar vab"><a href="#Page_56">56</a></td></tr>
+<tr><td class="tal pl4em"><span class="pagenum" title="x"><a name="Page_x" id="Page_x"></a></span>The Work of Wilhelm Roux</td><td class="tar vab"><a href="#Page_58">58</a></td></tr>
+<tr><td class="tal pl4em">The Experiments on the Egg of the Sea-urchin</td><td class="tar vab"><a href="#Page_59">59</a></td></tr>
+<tr><td class="tal pl4em">On the Intimate Structure of the Protoplasm of the Germ</td><td class="tar vab"><a href="#Page_65">65</a></td></tr>
+<tr><td class="tal pl4em">On some Specificities of Organisation in Certain Germs</td><td class="tar vab"><a href="#Page_70">70</a></td></tr>
+<tr><td class="tal pl4em">General Results of the First Period of “Entwickelungsmechanik”</td><td class="tar vab"><a href="#Page_71">71</a></td></tr>
+<tr><td class="tal pl4em">Some New Results concerning Restitutions</td><td class="tar vab"><a href="#Page_74">74</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">Analytical Theory of Morphogenesis</span></td><td class="tar"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl4em">α. <span class="lowercase smcap">THE DISTRIBUTION OF MORPHOGENIC POTENCIES</span></td><td class="tar vab"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl6em">Prospective Value and Prospective Potency</td><td class="tar vab"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl6em">The Potencies of the Blastomeres</td><td class="tar vab"><a href="#Page_79">79</a></td></tr>
+<tr><td class="tal pl6em">The Potencies of Elementary Organs in General</td><td class="tar vab"><a href="#Page_80">80</a></td></tr>
+<tr><td class="tal pl6em">Explicit and Implicit Potencies: Primary and Secondary Potencies</td><td class="tar vab"><a href="#Page_83">83</a></td></tr>
+<tr><td class="tal pl6em pr4em">The Morphogenetic Function of Maturation in the Light of Recent Discoveries</td><td class="tar vab"><a href="#Page_85">85</a></td></tr>
+<tr><td class="tal pl6em">The Intimate Structure of Protoplasm: Further Remarks</td><td class="tar vab"><a href="#Page_88">88</a></td></tr>
+<tr><td class="tal pl6em">The Neutrality of the Concept of “Potency”</td><td class="tar vab"><a href="#Page_89">89</a></td></tr>
+<tr><td class="tal pl4em pt05em">β. <span class="lowercase smcap">THE “MEANS” OF MORPHOGENESIS</span></td><td class="tar vab"><a href="#Page_89">89</a></td></tr>
+<tr><td class="tal pl6em">β′. The Internal Elementary Means of Morphogenesis</td><td class="tar vab"><a href="#Page_90">90</a></td></tr>
+<tr><td class="tal pl8em pr4em">Some Remarks on the Importance of Surface Tension in Morphogenesis</td><td class="tar vab"><a href="#Page_91">91</a></td></tr>
+<tr><td class="tal pl8em">On Growth</td><td class="tar vab"><a href="#Page_93">93</a></td></tr>
+<tr><td class="tal pl8em">On Cell-division</td><td class="tar vab"><a href="#Page_94">94</a></td></tr>
+<tr><td class="tal pl6em">β″. The External Means of Morphogenesis</td><td class="tar vab"><a href="#Page_95">95</a></td></tr>
+<tr><td class="tal pl8em">The Discoveries of Herbst</td><td class="tar vab"><a href="#Page_96">96</a></td></tr>
+<tr><td class="tal pl4em pt05em">γ. <span class="lowercase smcap">THE FORMATIVE CAUSES OR STIMULI</span></td><td class="tar vab"><a href="#Page_99">99</a></td></tr>
+<tr><td class="tal pl6em">The Definition of Cause</td><td class="tar vab"><a href="#Page_99">99</a></td></tr>
+<tr><td class="tal pl6em">Some Instances of Formative and Directive Stimuli</td><td class="tar vab"><a href="#Page_102">102</a></td></tr>
+<tr><td class="tal pl4em pt05em">δ. <span class="lowercase smcap">THE MORPHOGENETIC HARMONIES</span></td><td class="tar vab"><a href="#Page_107">107</a></td></tr>
+<tr><td class="tal pl4em pt05em">ε. <span class="lowercase smcap">ON RESTITUTIONS</span></td><td class="tar vab"><a href="#Page_110">110</a></td></tr>
+<tr><td class="tal pl6em pr4em">A few Remarks on Secondary Potencies and on Secondary Morphogenetic Regulations in General</td><td class="tar vab"><a href="#Page_110">110</a></td></tr>
+<tr><td class="tal pl6em">The Stimuli of Restitutions</td><td class="tar vab"><a href="#Page_113">113</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">3. <span class="smcap">The Problem of Morphogenetic Localisation: The Theory of the Harmonious-Equipotential system&mdash;First Proof of the Autonomy of Life</span></td><td class="tar vab ptb05em"><a href="#Page_118">118</a></td></tr>
+<tr><td class="tal pl4em">The General Problem</td><td class="tar vab"><a href="#Page_118">118</a></td></tr>
+<tr><td class="tal pl4em">The Morphogenetic “System”</td><td class="tar vab"><a href="#Page_119">119</a></td></tr>
+<tr><td class="tal pl4em">The “Harmonious-equipotential System”</td><td class="tar vab"><a href="#Page_122">122</a></td></tr>
+<tr><td class="tal pl4em"><span class="pagenum" title="xi"><a name="Page_xi" id="Page_xi"></a></span>Instances of “Harmonious-equipotential Systems”</td><td class="tar vab"><a href="#Page_126">126</a></td></tr>
+<tr><td class="tal pl4em">The Problem of the Factor <i>E</i></td><td class="tar vab"><a href="#Page_132">132</a></td></tr>
+<tr><td class="tal pl4em">No Explanation offered by “Means” or “Formative Stimuli”</td><td class="tar vab"><a href="#Page_132">132</a></td></tr>
+<tr><td class="tal pl4em">No Explanation offered by a Chemical Theory of Morphogenesis</td><td class="tar vab"><a href="#Page_134">134</a></td></tr>
+<tr><td class="tal pl4em">No Machine Possible Inside the Harmonious Systems</td><td class="tar vab"><a href="#Page_138">138</a></td></tr>
+<tr><td class="tal pl4em">The Autonomy of Morphogenesis proved</td><td class="tar vab"><a href="#Page_142">142</a></td></tr>
+<tr><td class="tal pl4em">“Entelechy”</td><td class="tar vab"><a href="#Page_143">143</a></td></tr>
+<tr><td class="tal pl4em">Some General Remarks on Vitalism</td><td class="tar vab"><a href="#Page_145">145</a></td></tr>
+<tr><td class="tal pl4em">The Logic of our First Proof of Vitalism</td><td class="tar vab"><a href="#Page_146">146</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">4. <span class="smcap">On Certain other Features of Morphogenesis Advocating its Autonomy</span></td><td class="tar vab ptb05em"><a href="#Page_150">150</a></td></tr>
+<tr><td class="tal pl4em">Harmonious-equipotential Systems formed by Wandering Cells</td><td class="tar vab"><a href="#Page_151">151</a></td></tr>
+<tr><td class="tal pl4em">On Certain Combined Types of Morphogenetic Systems</td><td class="tar vab"><a href="#Page_153">153</a></td></tr>
+<tr><td class="tal pl4em">The “Morphaesthesia” of Noll</td><td class="tar vab"><a href="#Page_157">157</a></td></tr>
+<tr><td class="tal pl4em">Restitutions of the Second Order</td><td class="tar vab"><a href="#Page_158">158</a></td></tr>
+<tr><td class="tal pl4em">On the “Equifinality” of Restitutions</td><td class="tar vab"><a href="#Page_159">159</a></td></tr>
+<tr><td class="tal pl4em pb15em">Remarks on “Retro-Differentiation”</td><td class="tar pb15em"><a href="#Page_163">163</a></td></tr>
+<tr><td class="tal pb05em"><i>C.</i> ADAPTATION&mdash;</td></tr>
+<tr><td class="tal pl2em"><span class="smcap">Introductory Remarks on Regulations in General</span></td><td class="tar vab"><a href="#Page_165">165</a></td></tr>
+<tr><td class="tal pl2em ptb05em">1. <span class="smcap">Morphological Adaptation</span></td><td class="tar"><a href="#Page_168">168</a></td></tr>
+<tr><td class="tal pl4em">The Limits of the Concept of Adaptation</td><td class="tar vab"><a href="#Page_168">168</a></td></tr>
+<tr><td class="tal pl4em">Adaptations to Functional Changes from Without</td><td class="tar vab"><a href="#Page_172">172</a></td></tr>
+<tr><td class="tal pl4em">True Functional Adaptation</td><td class="tar vab"><a href="#Page_176">176</a></td></tr>
+<tr><td class="tal pl4em">Theoretical Conclusions</td><td class="tar vab"><a href="#Page_179">179</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">Physiological Adaptation</span></td><td class="tar"><a href="#Page_184">184</a></td></tr>
+<tr><td class="tal pl4em">Specific Adaptedness <em>not</em> “Adaptation”</td><td class="tar vab"><a href="#Page_186">186</a></td></tr>
+<tr><td class="tal pl4em">Primary and Secondary Adaptations in Physiology</td><td class="tar vab"><a href="#Page_188">188</a></td></tr>
+<tr><td class="tal pl4em">On Certain Pre-requisites of Adaptations in General</td><td class="tar vab"><a href="#Page_189">189</a></td></tr>
+<tr><td class="tal pl4em">On Certain Groups of Primary Physiological Adaptations</td><td class="tar vab"><a href="#Page_190">190</a></td></tr>
+<tr><td class="tal pl6em">General Remarks on Irritability</td><td class="tar vab"><a href="#Page_190">190</a></td></tr>
+<tr><td class="tal pl6em">The Regulation of Heat Production</td><td class="tar vab"><a href="#Page_193">193</a></td></tr>
+<tr><td class="tal pl6em pr4em">Primary Regulations in the Transport of Materials and Certain Phenomena of Osmotic Pressure</td><td class="tar vab"><a href="#Page_194">194</a></td></tr>
+<tr><td class="tal pl6em">Chromatic Regulations in Algae</td><td class="tar vab"><a href="#Page_197">197</a></td></tr>
+<tr><td class="tal pl6em">Metabolic Regulations</td><td class="tar vab"><a href="#Page_198">198</a></td></tr>
+<tr><td class="tal pl4em">Immunity the only Type of a Secondary Physiological Adaptation</td><td class="tar vab"><a href="#Page_204">204</a></td></tr>
+<tr><td class="tal pl4em">No General Positive Result from this Chapter</td><td class="tar vab"><a href="#Page_209">209</a></td></tr>
+<tr><td class="tal pl4em pb15em">A few Remarks on the Limits of Regulability</td><td class="tar pb15em"><a href="#Page_212">212</a></td></tr>
+<tr><td class="tal pb05em"><span class="pagenum" title="xii"><a name="Page_xii" id="Page_xii"></a></span><i>D.</i> INHERITANCE. SECOND PROOF OF THE AUTONOMY OF LIFE&mdash;</td></tr>
+<tr><td class="tal pl2em">The Material Continuity in Inheritance</td><td class="tar vab"><a href="#Page_214">214</a></td></tr>
+<tr><td class="tal pl2em">On Certain Theories which Seek to Compare Inheritance to Memory</td><td class="tar vab"><a href="#Page_216">216</a></td></tr>
+<tr><td class="tal pl2em">The Complex-Equipotential System and its Rôle in Inheritance</td><td class="tar vab"><a href="#Page_219">219</a></td></tr>
+<tr><td class="tal pl2em pr4em">The Second Proof of Life-Autonomy. Entelechy at the Bottom of Inheritance</td><td class="tar vab"><a href="#Page_224">224</a></td></tr>
+<tr><td class="tal pl2em">The Significance of the Material Continuity in Inheritance</td><td class="tar vab"><a href="#Page_227">227</a></td></tr>
+<tr><td class="tal pl2em">The Experimental Facts about Inheritance</td><td class="tar vab"><a href="#Page_228">228</a></td></tr>
+<tr><td class="tal pl2em">The Rôle of the Nucleus in Inheritance</td><td class="tar vab"><a href="#Page_233">233</a></td></tr>
+<tr><td class="tal pl2em pb15em">Variation and Mutation</td><td class="tar pb15em"><a href="#Page_237">237</a></td></tr>
+<tr><td class="tal"><i><span class="smcap">Conclusions from the First Main Part of these Lectures</span></i></td><td class="tar vab"><a href="#Page_240">240</a></td></tr>
+</table></div>
+
+<p class="tac">PART II.&mdash;SYSTEMATICS AND HISTORY</p>
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal pb05em"><i>A.</i> THE PRINCIPLES OF SYSTEMATICS&mdash;</td></tr>
+<tr><td class="tal pl2em">Rational Systematics</td><td class="tar vab"><a href="#Page_243">243</a></td></tr>
+<tr><td class="tal pl2em pb15em">Biological Systematics</td><td class="tar pb15em"><a href="#Page_246">246</a></td></tr>
+<tr><td class="tal pb05em"><i>B.</i> THE THEORY OF DESCENT&mdash;</td></tr>
+<tr><td class="tal pl2em ptb05em">1. <span class="smcap">Generalities</span></td><td class="tar"><a href="#Page_250">250</a></td></tr>
+<tr><td class="tal pl4em">The Covert Presumption of all Theories of Descent</td><td class="tar vab"><a href="#Page_253">253</a></td></tr>
+<tr><td class="tal pl4em">The Small Value of Pure Phylogeny</td><td class="tar vab"><a href="#Page_255">255</a></td></tr>
+<tr><td class="tal pl4em">History and Systematics</td><td class="tar vab"><a href="#Page_257">257</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">The Principles of Darwinism</span></td><td class="tar"><a href="#Page_260">260</a></td></tr>
+<tr><td class="tal pl4em">Natural Selection</td><td class="tar vab"><a href="#Page_261">261</a></td></tr>
+<tr><td class="tal pl4em">Fluctuating Variation the Alleged Cause of Organic Diversity</td><td class="tar vab"><a href="#Page_264">264</a></td></tr>
+<tr><td class="tal pl4em">Darwinism Fails all along the Line</td><td class="tar vab"><a href="#Page_269">269</a></td></tr>
+<tr><td class="tal pl2em ptb05em">3. <span class="smcap">The Principles of Lamarckism</span></td><td class="tar"><a href="#Page_271">271</a></td></tr>
+<tr><td class="tal pl4em">Adaptation as the Starting-Point</td><td class="tar vab"><a href="#Page_272">272</a></td></tr>
+<tr><td class="tal pl4em">The Active Storing of Contingent Variations as a Hypothetic Principle</td><td class="tar vab"><a href="#Page_273">273</a></td></tr>
+<tr><td class="tal pl4em pr4em">Criticism of the “Inheritance of Acquired Characters” assumed by Lamarckism</td><td class="tar vab"><a href="#Page_275">275</a></td></tr>
+<tr><td class="tal pl4em">Other Principles Wanted</td><td class="tar vab"><a href="#Page_281">281</a></td></tr>
+<tr><td class="tal pl4em pr4em">Criticism of the Hypothesis of Storing and Handing Down Contingent Variations</td><td class="tar vab"><a href="#Page_282">282</a></td></tr>
+<tr><td class="tal pl2em ptb05em">4. <span class="smcap">The Real Results and the Unsolved Problems of Transformism</span></td><td class="tar ptb05em"><a href="#Page_290">290</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">5. <span class="smcap">The Logical Value of the Organic Form according to the different Transformistic Theories</span></td><td class="tar ptb05em vab"><a href="#Page_293">293</a></td></tr>
+<tr><td class="tal pl4em pb15em">The Organic Form and Entelechy</td><td class="tar pb15em"><a href="#Page_294">294</a></td></tr>
+<tr><td class="tal pb05em"><i>C.</i> THE LOGIC OF HISTORY</td><td class="tar pb05em"><a href="#Page_297">297</a><span class="pagenum" title="xiii"><a name="Page_xiii" id="Page_xiii"></a></span></td></tr>
+<tr><td class="tal pl2em pb05em">1. <span class="smcap">The Possible Aspects of History</span></td><td class="tar pb05em"><a href="#Page_299">299</a></td></tr>
+<tr><td class="tal pl2em pb05em">2. <span class="smcap">Phylogenetic Possibilities</span></td><td class="tar pb05em"><a href="#Page_304">304</a></td></tr>
+<tr><td class="tal pl2em pb05em">3. <span class="smcap">The History of Mankind</span></td><td class="tar pb05em"><a href="#Page_306">306</a></td></tr>
+<tr><td class="tal pl4em">Cumulations in Human History</td><td class="tar vab"><a href="#Page_308">308</a></td></tr>
+<tr><td class="tal pl4em">Human History not an “Evolution”</td><td class="tar vab"><a href="#Page_311">311</a></td></tr>
+<tr><td class="tal pl4em pb15em">The Problem of the “Single” as such</td><td class="tar pb15em"><a href="#Page_315">315</a></td></tr>
+<tr><td class="tal pb05em"><i><span class="smcap">Conclusions about Systematics and History in General</span></i></td><td class="tar pb05em"><a href="#Page_322">322</a></td></tr>
+</table></div>
+
+<p><span class="pagenum hide" title="xiv"><a name="Page_xiv" id="Page_xiv"></a></span></p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="1"><a name="Page_1" id="Page_1"></a></span></p>
+
+
+
+<h2>THE PROGRAMME</h2>
+
+
+<p class="tac ptb05em"><span class="smcap">On Lord Gifford’s Conception of “Science”</span></p>
+
+<p>This is the first time that a biologist has occupied this
+place; the first time that a biologist is to try to carry out the
+intentions of the noble and high-minded man to whom this
+lectureship owes its foundation.</p>
+
+<p>On such an occasion it seems to be not undesirable to
+inquire what Lord Gifford’s own opinions about natural
+science may have been, what place in the whole scheme of
+human knowledge he may have attributed to those branches
+of it which have become almost the centre of men’s
+intellectual interest.</p>
+
+<p>And, indeed, on studying Lord Gifford’s bequest with
+the object of finding in it some reference to the natural
+sciences, one easily notes that he has assigned to them a
+very high place compared with the other sciences, at least
+in one respect: with regard to their methods.</p>
+
+<p>There is a highly interesting passage in his will which
+leaves no doubt about our question. After having formally
+declared the foundation of this lectureship “for Promoting,
+Advancing, Teaching and Diffusing the study of Natural
+Theology in the widest sense of that term,” and after<span class="pagenum" title="2"><a name="Page_2" id="Page_2"></a></span>
+having arranged about the special features of the lectures,
+he continues: “I wish the lecturers to treat their subject
+as a strictly natural science, the greatest of all possible
+sciences, indeed, in one sense, the only science, that of
+Infinite Being.&nbsp;.&nbsp;.&nbsp;. I wish it considered just as astronomy
+or chemistry is.”</p>
+
+<p>Of course, it is not possible to understand these words
+of Lord Gifford’s will in a quite literal sense. If, provisionally,
+we call “natural theology” the ultimate conclusions
+which may be drawn from a study of nature in connection
+with all other results of human sciences, there cannot be
+any doubt that these conclusions will be of a rather different
+character from the results obtained in, say, the special field
+of scientific chemistry. But, nevertheless, there are, I
+think, two points of contact between the wider and the
+narrower field of knowledge, and both of them relate to
+method. Lord Gifford’s own phrase, “Infinite Being,”
+shows us one of these meeting-points. In opposition to
+history of any form, natural sciences aim at discovering
+such truths as are independent of special time and of
+special space, such truths as are “ideas” in the sense of
+Plato; and such eternal results, indeed, always stand in
+close relation to the ultimate results of human knowledge
+in general. But besides that there is still another feature
+which may be common both to “natural theology” and to
+the special natural sciences, and which is most fully developed
+in the latter: freedom from prepossessions. This, at least,
+is an ideal of all natural sciences; I may say it is <em>the</em>
+ideal of them. That it was this feature which Lord Gifford
+had in view in his comparison becomes clear when we read
+in his will that the lectures on natural theology are<span class="pagenum" title="3"><a name="Page_3" id="Page_3"></a></span>
+to be delivered “without reference to or reliance upon
+any supposed special exceptional or so-called miraculous
+revelation.”</p>
+
+<p>So we might say that both in their logical and their
+moral methods, natural sciences are to be the prototype of
+“Natural Theology” in Lord Gifford’s sense.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Natural Sciences and “Natural Theology”</span></p>
+
+<p>But now let us study in a more systematic manner the
+possible relations of the natural sciences to natural theology
+as a science.</p>
+
+<p>How is it possible for a natural scientist to contribute
+to the science of the highest and ultimate subject of human
+knowledge?</p>
+
+<p>Almost all natural sciences have a sort of naïveté in
+their own spheres; they all stand on the ground of what
+has been called a naïve realism, as long as they are, so
+to say, at home. That in no way prejudices their own
+progress, but it seems to stand in the way of establishing
+contact with any higher form of human knowledge than
+themselves. One may be a first-rate organic chemist even
+when looking upon the atoms as small billiard balls, and
+one may make brilliant discoveries about the behaviour of
+animals even when regarding them in the most anthropomorphic
+manner&mdash;granted that one is a good observer;
+but it can hardly be admitted that our chemist would do
+much to advance the theory of matter, or our biologist to
+solve the problem of the relations between body and mind.</p>
+
+<p>It is only by the aid of philosophy, or I would rather
+say by keeping in constant touch with it, that natural<span class="pagenum" title="4"><a name="Page_4" id="Page_4"></a></span>
+sciences are able to acquire any significance for what might
+be called <em>the</em> science of nature in the most simple form.
+Unhappily the term “natural philosophy” is restricted in
+English to theoretical physics. This is not without a high
+degree of justification, for theoretical physics has indeed lost
+its naïveté and become a philosophy of nature; but it nevertheless
+is very unfortunate that this use of the term “natural
+philosophy” is established in this country, as we now have
+no proper general term descriptive of a natural science that
+is in permanent relation to philosophy, a natural science
+which does not use a single concept without justifying it
+epistemologically, <i>i.e.</i> what in German, for instance, would
+simply be called “Naturphilosophie.”</p>
+
+<p>Let us call it philosophy of nature; then we may say
+that only by becoming a true philosophy of nature are
+natural sciences of all sorts able to contribute to the highest
+questions which man’s spirit of inquiry can suggest.</p>
+
+<p>These highest questions themselves are the outcome of
+the combination of the highest results of all branches of
+philosophy, just as our philosophy of nature originated in the
+discussion of the results of all the separate natural sciences.
+Are those highest questions not only to be asked, are they
+to be also solved? To be solved in a way which does not
+exceed the limits of philosophy as the domain of actual
+understanding?</p>
+
+<p>The beginning of a long series of studies is not the right
+place to decide this important question; and so, for the
+present certainly, “natural theology” must remain a problem.
+In other words: it must remain an open question
+at the beginning of our studies, whether after all there
+can be any final general answer, free from contradictions,<span class="pagenum" title="5"><a name="Page_5" id="Page_5"></a></span>
+applicable to the totality of questions asked by all the
+branches of philosophy.</p>
+
+<p>But let us not be disturbed by this problematic entrance
+to our studies. Let us follow biology on its own path;
+let us study its transition from a “naïve” science to a real
+branch of the philosophy of nature. In this way we perhaps
+shall be able to understand what its part may be in solving
+what can be solved.</p>
+
+<p>That is to be our subject.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Our Philosophical Basis</span></p>
+
+<p>We call <em>nature</em> what is given to us in space.</p>
+
+<p>Of course we are not obliged in these lectures to
+discuss the psychological and epistemological problems of
+space with its three dimensions, nor are we obliged to
+develop a general theory of reality and its different
+aspects. A few epistemological points will be considered
+later at proper times, and always in connection with results
+of theoretical biology.</p>
+
+<p>At present it must suffice to say that our general
+philosophical point of view will be idealistic, in the critical
+meaning of the word. The universe, and within the
+universe nature, in the sense just defined, is my
+phenomenon. That is what I know. I know nothing
+more, either positively or negatively; that is to say, I
+do not know that the world is <em>only my</em> phenomenon, but,
+on the other hand, I know nothing about its “absolute
+reality.” And more, I am not even able to describe in
+intelligible words what “absolute reality” might mean. I
+am fully entitled to state: the universe <em>is</em> as truly as I<span class="pagenum" title="6"><a name="Page_6" id="Page_6"></a></span>
+am&mdash;though in a somewhat different sense of “being”&mdash;and
+I <em>am</em> as truly as the universe is; but I am not
+entitled to state anything beyond these two corresponding
+phrases. You know that, in the history of European
+philosophy at least, Bishop Berkeley was the first clearly
+to outline the field of idealism.</p>
+
+<p>But my phenomenon&mdash;the world, especially nature&mdash;consists
+of elements of two different kinds: some of them
+are merely passive, some of them contain a peculiar sort
+of activity in themselves. The first are generally called
+sensations, but perhaps would be better called elements
+or presentations; the others are forms of construction, and,
+indeed, there is an active element embraced in them in
+this sense, that they allow, by their free combination, the
+discovery of principles which are not to be denied, which
+must be affirmed, whenever their meaning is understood.
+You know that I am speaking here of what are generally
+called categories and synthetic judgments <i lang="la" xml:lang="la">a priori</i>, and
+that it was Kant who, on the foundations laid by Locke,
+Hume, and Leibnitz, first gave the outlines of what may
+be called the real system of critical philosophy. Indeed,
+our method will be to a great extent Kantian, though
+with certain exceptions; it is to be strictly idealistic, and
+will not in the Kantian way operate with things in
+themselves; and it regards the so-called “synthetic judgment
+<i lang="la" xml:lang="la">a priori</i>” and the problem of the relation between
+categorical principles and experience in a somewhat
+different manner. We think it best to define the much
+disputed concept “<i lang="la" xml:lang="la">a priori</i>” as “independent of the <em>amount</em>
+of experience”; that is to say, all categories and categorical
+principles are brought to my consciousness by that<span class="pagenum" title="7"><a name="Page_7" id="Page_7"></a></span>
+fundamental event which is called experience, and therefore
+are not independent of it, but they are not inferences from
+experience, as are so-called empirical laws. We almost
+might say that we only have to be reminded of those
+principles by experience, and, indeed, we should not, I
+think, go very far wrong in saying that the Socratic
+doctrine, that all knowledge is recollection, holds good as
+far as categories and categorical principles are in question.</p>
+
+<p>But enough at present about our general philosophy.</p>
+
+<p>As to the philosophy of nature, there can be no doubt
+that, on the basis of principles like those we have shortly
+sketched, its ultimate aim must be to co-ordinate everything
+in nature with terms and principles of the categorical
+style. The philosophy of nature thus becomes a system;
+a system of which the general type is afforded by the
+innate constructive power of the Ego. In this sense
+the Kantian dictum remains true, that the Ego prescribes
+its own laws to nature, though, of course, “nature,” that
+is, what is given in space, must be such as to permit that
+sort of “prescription.”</p>
+
+<p>One often hears that all sciences, including the science
+of sciences, philosophy, have to find out what is true.
+What, then, may be called “true” by an idealistic
+philosopher, for whom the old realistic formula of the
+conformity between knowledge and the object cannot
+have any meaning? Besides its ordinary application to
+simple facts or to simple judgments, where the word truth
+only means absence of illusion or no false statement, truth
+can be claimed for a philosophical doctrine or for a system
+of such doctrines only in the sense that there are no
+contradictions amongst the parts of the doctrine or of the<span class="pagenum" title="8"><a name="Page_8" id="Page_8"></a></span>
+system themselves, and that there are no features in them
+which impel our categorical Ego to further analysis.</p>
+
+<p>Those of you who attended Professor Ward’s lectures
+on “Naturalism and Agnosticism,” or who have read his
+excellent book on that subject, will know what the aims of
+a theory of matter are. You will also be aware that, at
+present, there does not exist any theory of matter which
+can claim to be “true”; there are contradictions in every
+theory of matter, and, moreover, there are always some
+points where we are obliged to ask for further information
+and receive no answer. Experience here has not yet
+aroused all the categorical functions which are needed in
+order to form one unity out of what seem to be incompatibilities
+at the present day. Why is that? Maybe
+because experience is not yet complete in this field, but
+maybe also because the whole subject is so complicated
+that it takes much time to attach categorical functions to
+what is experienced.</p>
+
+<p>But it is not our object here to deal either with
+epistemology proper or with ontology: a full analysis of
+biological facts is our problem. Why, then, all these
+introductions? why all these philosophical sketches in
+fields of knowledge which have quite another relation to
+philosophy than biology has? Biology, I hear some one
+say, is simply and solely an empirical science; in some
+sense it is nothing but applied physics and chemistry,
+perhaps applied mechanics. There are no fundamental
+principles in biology which could bring it in any close
+contact with philosophy. Even the one and only principle
+which might seem to be an innate principle of our
+experience about life, the principle of evolution, is only a<span class="pagenum" title="9"><a name="Page_9" id="Page_9"></a></span>
+combination of more simple factors of the physical and
+chemical type.</p>
+
+<p>It will be my essential endeavour to convince you, in
+the course of these lectures, that such an aspect of the
+science of biology is wrong; that biology is an elemental
+natural science in the true sense of the word.</p>
+
+<p>But if biology is an elemental science, then, and only
+then, it stands in close relations to epistemology and
+ontology&mdash;in the same relations to them, indeed, as every
+natural science does which deals with true elements of nature,
+and which is willing to abandon naïve realism and contribute
+its share to the whole of human knowledge.</p>
+
+<p>And, therefore, a philosophical sketch is not out of
+place at the beginning of lectures on the Philosophy of
+the Organism. We may be forced, we, indeed, shall be
+forced, to remain for some time on the ground of realistic
+empiricism, for biology has to deal with very complicated
+experiences; but there will be a moment in our progress
+when we shall enter the realm of the elemental ontological
+concepts, and in that very moment our study of life will
+have become a part of real philosophy. It was not without
+good reasons, therefore, that I shortly sketched, as a sort
+of introduction to my lectures, the general point of view
+which we shall take with regard to philosophical questions,
+and to questions of the philosophy of nature in particular.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">On Certain Characteristics of Biology as a Science</span></p>
+
+<p>Biology is the science of life. Practically, all of you
+know what a living being is, and therefore it is not
+necessary to formulate a definition of life, which, at the<span class="pagenum" title="10"><a name="Page_10" id="Page_10"></a></span>
+beginning of our studies, would be either provisional and
+incomplete, or else dogmatic. In some respects, indeed, a
+definition should rather be the end of a science than its
+opening.</p>
+
+<p>We shall study the phenomena of living organisms
+analytically, by the aid of experiment; our principal object
+will be to find out laws in these phenomena; such laws
+will then be further analysed, and precisely at that point
+we shall leave the realm of natural science proper.</p>
+
+<p>Our science is the highest of all natural sciences, for
+it embraces as its final object the actions of man, at least
+in so far as actions also are phenomena observable on living
+bodies.</p>
+
+<p>But biology is also the most difficult of all natural
+sciences, not only from the complexity of the phenomena,
+which it studies, but in particular for another reason which
+is seldom properly emphasised, and therefore will well repay
+us for a few words devoted to it.</p>
+
+<p>Except so far as the “elements” of chemistry come
+into account, the experimenter in the inorganic fields of
+nature is not hampered by the specificity of composite
+objects: he makes all the combinations he wants. He is
+always able to have at his disposal red rays of a desired
+wave length when and where he wants, or to have, at a
+given time and place, the precise amount of any organic
+compound which he wishes to examine. And he forces
+electricity and electromagnetism to obey his will, at least
+with regard to space, time, and intensity of their appearance.</p>
+
+<p>The biologist is not able to “make” life, as the physicist
+has made red rays or electromagnetism, or as the chemist
+has made a certain compound of carbon. The biologist is<span class="pagenum" title="11"><a name="Page_11" id="Page_11"></a></span>
+almost always in that strange plight in which the physicist
+would be if he always had to go to volcanoes in order to
+study the conductivity of heat, or if he had to wait for
+thunderstorms in order to study electricity. The biologist
+is dependent on the specificity of living objects as they occur
+in nature.</p>
+
+<p>A few instances may show you what great inconveniences
+may hence arise to impede practical biological
+research. We later on shall have to deal with experiments
+on very young embryos: parts of the germ will have to be
+destroyed in order to study what will happen with the rest.
+Now almost all germs are surrounded by a membrane; this
+membrane has to be detached before any operation is
+possible. But what are we to do if it is not possible to
+remove the membrane without killing the embryo? Or what
+if, as for instance in many marine animals, the membrane
+may be removed but the germs are killed by contact with
+sea-water? In both cases no experiments at all will be
+possible on a sort of germ which otherwise, for some special
+circumstances of its organisation, might have given results
+of importance. These results become impossible for only a
+practical, for a very secondary reason; but enough: they
+are impossible, and they might have thrown light on
+problems which now must remain problems. Quite the
+same thing may occur in experiments on physiology proper
+or functional physiology: one kind of animals survives the
+operation, the other kind does not, and therefore, for merely
+extrinsic reasons, the investigations have to be restricted to
+the first, though the second might have given more important
+results. And thus the biological experimenter
+always finds himself in a sort of dependence on his subjects,<span class="pagenum" title="12"><a name="Page_12" id="Page_12"></a></span>
+which can hardly be called pleasant. To a great extent
+the comparatively slow advance of biological sciences is due
+to this very fact: the unalterable specific nature of biological
+material.</p>
+
+<p>But there is still another feature of biology dependent
+on the same fact. If a science is tied down to specific
+objects in every path it takes, it first, of course, has to
+know all about those objects, and that requires nothing
+else but plain description. We now understand why pure
+description, in the most simple sense of the word, takes up
+such an enormous part of every text-book of biological
+science. It is not only morphology, the science of form,
+that is most actively concerned with description; physiology
+also, in its present state, is pure description of what the
+functions of the different parts of the body of animals and
+plants actually <em>are</em>, at least for about nine-tenths of its
+range. It seems to me important to press this point very
+emphatically, since we often hear that physiology is from
+the very beginning a much higher sort of knowledge than
+morphology, inasmuch as it is rational. That is not at
+all true of the beginning of physiology: what the functions
+of the liver or of the root are has simply to be described
+just as the organisation of the brain or of the leaf, and it
+makes no difference logically that one species of description
+has to use the experimental method, while the other has
+not. The experiment which only discovers what happens
+here or what happens there, possesses no kind of logical
+superiority over pure description at all.</p>
+
+<p>But there will be another occasion in our lectures to
+deal more fully with the logic of experiment and with the
+differences of descriptive knowledge and real rational science.</p>
+
+<p><span class="pagenum" title="13"><a name="Page_13" id="Page_13"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The three Different Types of Knowledge about Nature</span></p>
+
+<p>Natural sciences cannot originate before the given
+phenomena of nature have been investigated in at least a
+superficial and provisional manner, by and for the practical
+needs of man. But as soon as true science begins in any
+limited field, dealing, let us say, with animals or with
+minerals, or with the properties of bodies, it at once finds
+itself confronted by two very different kinds of problems,
+both of them&mdash;like all “problems”&mdash;created in the last
+resort by the logical organisation of the human mind, or, to
+speak still more correctly, of the Ego.</p>
+
+<p>In any branch of knowledge which practical necessities
+have separated from others, and which science now tries
+to study methodically, there occur general sequences in
+phenomena, general orders of events. This uniformity is
+revealed only gradually, but as soon as it has shown itself,
+even in the least degree, the investigator seizes upon it.
+He now devotes himself chiefly, or even exclusively, to the
+generalities in the sequences of all changes. He is convinced
+that there must be a sort of most general and at the
+same time of most universal connection about all occurrences.
+This most universal connection has to be found out; at least
+it will be the ideal that always will accompany the inquiring
+mind during its researches. The “law of nature” is
+the ideal I am speaking about, an ideal which is nothing
+less than one of the postulates of the possibility of science
+at all.</p>
+
+<p>Using for our purposes a word which has been already
+introduced into terminology by the philosopher Windelband,<span class="pagenum" title="14"><a name="Page_14" id="Page_14"></a></span>
+though in a somewhat different sense, we shall call that
+part of every branch of natural sciences which regards the
+establishment of a law of nature as its ideal, “nomothetic,”
+<i>i.e.</i> “law-giving.”</p>
+
+<p>But while every natural science has its nomothetic side,
+it also has another half of a very different kind. This second
+half of every natural science does not care for the same
+general, the same universal, which is shown to us in every
+event in a different and specified kind: it is diversity, it is
+specification, that constitutes the subject of its interest.
+Its aim is to find a sufficient reason for the types of
+diversities, for the types of specifications. So in chemistry
+there has been found a systematic order in the long series
+of the compounds and of the elements; crystallography also
+has its different systems of crystals, and so on.</p>
+
+<p>We have already employed the word by which we shall
+designate this second half of every natural science: it is
+the “systematic” side of science.</p>
+
+<p>Nomothetic work on the one side and systematics on
+the other do, in fact, appear in every natural science, and
+besides them there are no other main parts. But “science”
+as a whole stands apart from another aspect of reality
+which is called “history.” History deals with particulars,
+with particular events at such and such a place, whilst
+science always abstracts from the particular, even in its
+systematic <span class="nowrap">half.<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">1</a></span></p>
+<p><span class="pagenum" title="15"><a name="Page_15" id="Page_15"></a></span></p>
+
+<p class="tac pt12b02em"><span class="smcap">General Plan of these Lectures</span></p>
+
+<p>Turning now to a sort of short outline of what is to be
+discussed in the whole of our future lectures, this summer
+and next, it seems clear, without further analysis, that
+biology as a science has its nomothetic and its systematic
+part also; respiration and assimilation, for instance, have
+proved to be types of natural laws among living phenomena,
+and that there is a “system” of animals and plants is
+too commonly known to require further explanation here.
+Therefore we might study first biological laws, and after
+that biological systematics, and in the third place perhaps
+biological history. But that would hardly correspond to
+the philosophical aims of our lectures: our chief object is
+not biology as a regular science, as treated in text-books
+and in ordinary university lectures; our chief object is the
+Philosophy of the Organism, as aided and supported by
+scientific biology. Therefore a general acquaintance with
+biology must be assumed in these lectures, and the biological
+materials must be arranged according to their bearing on
+further, that is on philosophical, analysis.</p>
+
+<p>That will be done, not, of course, to the extent of my
+regarding every one of my audience as a competent biologist;
+on the contrary, I shall explain most fully all points of
+biology proper, and even of the most simple and descriptive
+kind of biology, which serve as bases for philosophical
+analysis. But I shall do so only if they indeed do serve
+as such bases. All our biology will be not for its own
+sake, but for the sake of philosophy.</p>
+
+<p>Whilst regarding the whole of the biological material<span class="pagenum" title="16"><a name="Page_16" id="Page_16"></a></span>
+with such aims, it seems to me best to arrange the properly
+scientific material which is to be the basis of my discussions,
+not along the lines which biology as an independent science
+would <span class="nowrap">select,<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">2</a></span> but to start from the three different kinds of
+fundamental phenomena which living bodies offer to investigation,
+and to attach all systematics exclusively to one
+of them. For there will not be very much for philosophy
+to learn from biological systematics at present.</p>
+
+<p>Life is unknown to us except in association with bodies:
+we only know living bodies and call them organisms. It
+is the final object of all biology to tell us what it ultimately
+means to say that a body is “living,” and in what sorts of
+relation body and life stand one to the other.</p>
+
+<p>But at present it is enough to understand the terms
+“body” and “living” in the ordinary and popular sense.</p>
+
+<p>Regarding living bodies in this unpretentious manner,
+and recollecting what the principal characters are of all
+bodies we know as living ones, we easily find that there
+are three features which are never wanting wherever life in
+bodies occurs. All living bodies are specific as to form&mdash;they
+“have” a specific form, as we are accustomed to say.
+All living bodies also exhibit metabolism; that is to say,
+they stand in a relation of interchange of materials with
+the surrounding medium, they take in and give out materials,
+but their form can remain unchanged during these processes.
+And, in the last place, we can say that all living bodies
+move; though this faculty is more commonly known
+among animals only, even elementary science teaches the
+student that it also belongs to plants.</p>
+
+<p>Therefore we may ask for “laws of nature” in biology<span class="pagenum" title="17"><a name="Page_17" id="Page_17"></a></span>
+about form, about metabolism, and about movements. In
+fact, it is according to this scheme that we shall arrange
+the materials of the biological part of our lectures, though,
+as we cannot regard the three divisions as equally important
+in their bearing on our ultimate purposes, we shall
+not treat them quite on equal terms. It will appear that,
+at least in the present state of science, the problems of
+organic form and of organic movement have come into
+much closer relation to philosophical analysis than have
+most of the empirical data on metabolism.</p>
+
+<p>It is <em>form</em> particularly which can be said to occupy the
+very centre of biological interest; at least it furnishes the
+foundation of all biology. Therefore we shall begin our
+scientific studies with a full and thorough analysis of form.
+The science of living forms, later on, will afford us a key to
+study metabolism proper with the greatest advantage for
+our philosophical aims, and therefore the physiology of
+what is usually called the vegetative functions will be to us
+a sort of appendix to our chapters on form; only the theory
+of a problematic “living substance” and of assimilation in
+the most general meaning of the word will be reserved for
+the philosophical part; for very good reasons, as I hope to
+show. But our chapters on the living forms will have yet
+another appendix besides the survey of the physiology of
+metabolism. Biological systematics almost wholly rests on
+form, on “morphology”; and what hitherto has been done
+on the metabolical side of their problems, consists of a few
+fragments, which are far from being an equivalent to the
+morphological system; though, of course it must be granted
+that, logically, systematics, in our general meaning of the
+word, as the sum of problems about the typically different<span class="pagenum" title="18"><a name="Page_18" id="Page_18"></a></span>
+and the specific, may be studied on the basis of each one of
+the principal characteristics of living bodies, not only on
+that of their forms. Therefore, systematics is to be the
+second appendix to the chief part of our studies in morphology,
+and systematics, in its turn, will later on lead us to a
+short sketch of the historical side of biology, to the theory
+of evolution in its different forms, and to the logic of history
+in general.</p>
+
+<p>So far will our programme be carried out during this
+summer. Next year the theory of movements will conclude
+our merely scientific analysis, and the remaining
+part of the course next summer will be devoted to the
+philosophy of living nature. I hope that nobody will be
+able to accuse our philosophy of resting on unsound foundations.
+But those of you, on the other hand, who would be
+apt to regard our scientific chapters as a little too long
+compared with their philosophical results, may be asked to
+consider that a small clock-tower of a village church is
+generally less pretentious but more durable than the
+campanile of San Marco has been.</p>
+
+<p>Indeed, these lectures will afford more “facts” to my
+hearers, than Gifford Lectures probably have done, as a rule.
+But how could that be otherwise on the part of a naturalist?
+Scientific facts are the material that the philosophy of
+nature has to work with, but these facts, unfortunately, are
+not as commonly known as historical facts, for instance,
+generally are; and they must be known, in order that a
+philosophy of the organism may be of any value at all, that
+it may be more than a mere entertainment.</p>
+
+<p>Goethe once said, that even in so-called facts there is
+more “theory” than is usually granted; he apparently was<span class="pagenum" title="19"><a name="Page_19" id="Page_19"></a></span>
+thinking of what might be called the ultimate or the typical
+facts in science. It is with such typical or ultimate facts,
+of course, that we must become acquainted if our future
+philosophy is to be of profit to us.</p>
+
+<p>Certainly, there would be nothing to prevent us from
+arranging our materials in a manner exactly the reverse of
+that which we shall adopt; we could begin with a general
+principle about the organic, and could try to deduce all its
+special features from that principle, and such a way perhaps
+would seem to be the more fascinating method of argument.
+But though logical it would not be psychological, and
+therefore would be rather unnatural. And thus our
+<em>most</em> general principle about the organic will not come on
+the scene before the eighteenth of these twenty lectures,
+although it is not a mere inference or deduction from the
+former lectures: it will be a culmination of the whole, and
+we shall appreciate its value the better the more we know
+what that whole really is.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">General Character of the Organic Form</span></p>
+
+<p>Our programme of this year, it was said, is to be
+devoted wholly to organic forms, though one of its appendixes,
+dealing with some characteristics of the physiology of
+metabolism, will lead us on to a few other phenomena.
+What then are the essentials of a living form, as commonly
+understood even without a special study of biology?</p>
+
+<p>Living bodies are not simple geometrical forms, not,
+like crystals, merely a typical arrangement of surfaces in
+space, to be reduced theoretically, perhaps, to an arrangement
+of molecules. Living bodies are typically combined<span class="pagenum" title="20"><a name="Page_20" id="Page_20"></a></span>
+forms; that is to say, they consist of simpler parts
+of different characters, which have a special arrangement
+with regard to one another; these parts have a
+typical form of their own and may again be combinations
+of more simple different parts. But besides that,
+living bodies have not always the same typically combined
+form during the whole of their life: they become
+more complicated as they grow older; they all begin from
+one starting point, which has little form at all, viz., the
+egg. So the living form may be called a “genetic form,” or
+a form considered as a process, and therefore <em>morphogenesis</em>
+is the proper and adequate term for the science which deals
+with the laws of organic forms in general; or, if you prefer
+not to use the same word both for a science and for the
+subjects of that science, the <em>physiology of morphogenesis</em>.</p>
+
+<p>Now there are different branches of the physiology of
+morphogenesis or physiology of form. We may study, and
+indeed we at first shall study, what are the laws of the
+morphogenetic processes leading from the egg to the adult:
+that may be properly called physiology of development. But
+living forms are not only able to originate in one unchangeable
+way: they may restore themselves, if disturbed, and
+thus we get the physiology of restoration or restitution as a
+second branch of the science of morphogenesis. We shall
+draw very important data, some of the foundations indeed
+of our philosophical discussions, from the study of such
+restitutions. Besides that, it is to them that our survey of the
+problems of the physiology of metabolism is to be appended.</p>
+
+<p>Living forms not only originate from the egg and are
+able to restore themselves, they also may give origin to
+other forms, guaranteeing in this way the continuity of life.<span class="pagenum" title="21"><a name="Page_21" id="Page_21"></a></span>
+The physiology of heredity therefore appears as the counterpart
+to those branches of the physiology of form which deal
+with individual form and its restitutions. And our discussion
+on heredity may be followed by our second appendix
+to this chief section on form, an appendix regarding the
+outlines of systematics, evolution and history.</p>
+
+<p>Theoretical considerations on biology generally start, or
+at least, used to start, from the evolution theory, discussing
+all other problems of the physiology of form by the way
+only, as things of secondary importance. You see from
+our programme, that we shall go just the opposite way:
+evolution will come last of all, and will be treated shortly;
+but the morphogenesis of the individual will be treated
+very fully, and very carefully indeed.</p>
+
+<p>Why then this deviation from what is the common
+practice? Because we do not know very much about
+evolution at all, because in this field we are just at the very
+beginning of what deserves the name of exact knowledge.
+But concerning individual morphogenesis we really know,
+even at present, if not very much, at least something, and
+that we know in a fairly exact form, aided by the results
+of experiments.</p>
+
+<p>And it will not be without its reward, if we restrict our
+aims in such a manner, if we prefer to deal more fully with
+a series of problems, which may seem at the first glance
+to be of less interest than others. After a few lectures we
+shall find already that we may decide one very important
+question about life merely by an analysis of individual
+form production, and without any regard to problematic
+and doubtful parts of biology: that we may decide the
+question, whether “life” is only a combination of chemical<span class="pagenum" title="22"><a name="Page_22" id="Page_22"></a></span>
+and physical events, or whether it has its elemental laws,
+laws of its own.</p>
+
+<p>But to prepare the road that is to lead to such results
+we first have to restrict our aims once more, and therefore
+the next lecture of this course, which eventually is to
+touch almost every concept of philosophy proper, will begin
+with the pure description of the individual development of
+the common sea-urchin.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="23"><a name="Page_23" id="Page_23"></a></span></p>
+
+
+
+
+<h2>SECTION A</h2>
+
+<h3>THE CHIEF RESULTS OF ANALYTICAL
+BIOLOGY</h3>
+
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="24"><a name="Page_24" id="Page_24"></a></span><br /><span class="pagenum" title="25"><a name="Page_25" id="Page_25"></a></span></p>
+
+
+
+<h2>PART I</h2>
+
+<h2>THE INDIVIDUAL ORGANISM WITH REGARD TO<br />
+FORM AND METABOLISM</h2>
+
+<h3><i>A.</i> ELEMENTARY MORPHOGENESIS</h3>
+
+<p class="tac ptb05em"><span class="smcap">Evolutio and Epigenesis in the old Sense</span></p>
+
+<p>The organism is a specific body, built up by a typical combination
+of specific and different parts. It is implied in
+the words of this definition, that the organism is different,
+not only from crystals, as was mentioned in the last lecture,
+but also from all combinations of crystals, such as those
+called dendrites and others, which consist of a typical arrangement
+of identical units, the nature of their combination
+depending on the forces of every single one of their parts.
+For this reason dendrites, in spite of the typical features
+in their combination, must be called aggregates; but the
+organism is not an aggregate even from the most superficial
+point of view.</p>
+
+<p>We have said before, what must have been familiar to
+you already, that the organism is not always the same in
+its individual life, that it has its development, leading from
+simpler to more complicated forms of combination of parts;
+there is a “production of visible manifoldness” carried out
+during development, to describe the chief character of that<span class="pagenum" title="26"><a name="Page_26" id="Page_26"></a></span>
+process in the words of Wilhelm Roux. We leave it an
+open question in our present merely descriptive analysis,
+whether there was already a “manifoldness,” in an invisible
+state, before development, or whether the phrase “production
+of manifoldness” is to be understood in an absolute
+sense.</p>
+
+<p>It has not always been granted in the history of biology,
+and of embryology especially, that production of visible
+manifoldness is the chief feature of what is called an
+organism’s embryology or ontogeny: the eighteenth century
+is full of determined scientific battles over the question.
+One school, with Albert von Haller and Bonnet as its leading
+men, maintained the view that there was no production of
+different parts at all in development, this process being a
+mere “evolutio,” that is, a growth of parts already existing
+from the beginning, yes, from the very beginning of life;
+whilst the other school, with C. F. Wolff and Blumenbach
+at its head, supported the opposite doctrine of so-called
+“epigenesis,” which has been proved to be the right one.</p>
+
+<p>To some extent these differences of opinion were only
+the outcome of the rather imperfect state of the optical
+instruments of that period. But there were also deeper
+reasons beyond mere difficulties of description; there were
+theoretical convictions underlying them. It is <em>impossible</em>,
+said the one party, that there is any real production of new
+parts; there <em>must</em> be such a production, said the other.</p>
+
+<p>We ourselves shall have to deal with these questions of
+the theory of organic development; but at present our
+object is narrower, and merely descriptive. It certainly is
+of great importance to understand most clearly that there
+actually <em>is</em> a “production of visible manifoldness” during<span class="pagenum" title="27"><a name="Page_27" id="Page_27"></a></span>
+ontogenesis in the descriptive sense; the knowledge of the
+fact of this process must be the very foundation of all
+studies on the theory of development in any case, and
+therefore we shall devote this whole lecture to studies in
+merely descriptive embryology.</p>
+
+<p>But descriptive embryology, even if it is to serve merely
+as an instance of the universality of the fact of epigenesis,
+can only be studied successfully with reference to a concrete
+case. We select the development of the common sea-urchin
+(<i class="biological-name">Echinus microtuberculatus</i>) as such a case, and we are
+the more entitled to select this organism rather than another,
+because most of the analytical experimental work, carried
+out in the interests of a real theory of development, has
+been done on the germs of this animal. Therefore, to know
+at least the outlines of the individual embryology of the
+Echinus may indeed be called the <i lang="la" xml:lang="la">conditio sine qua non</i>
+for a real understanding of what is to follow.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Cell</span><a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">3</a></p>
+
+<p>You are aware that all organisms consist of organs and
+that each of their organs has a different function: the brain,
+the liver, the eyes, the hands are types of organs in animals,
+as are the leaves and the pistils in plants.</p>
+
+<p>You are also aware that, except in the lowest organisms,
+the so-called Protista, all organs are built up of cells. That
+is a simple fact of observation, and I therefore cannot agree
+with the common habit of giving to this plain fact the title
+of cell-“theory.” There is nothing theoretical in it; and,<span class="pagenum" title="28"><a name="Page_28" id="Page_28"></a></span>
+on the other hand, all attempts to conceive the organism as
+a mere aggregate of cells have proved to be wrong. It is
+<em>the whole</em> that uses the cells, as we shall see later on, or
+that may not use them: thus there is nothing like a “cell-theory,”
+even in a deeper meaning of the word.</p>
+
+<p>The cell may have the most different forms: take a cell
+of the skin, of a muscle, of a gland, of the wood in plants
+as typical examples. But in every case two parts may be
+distinguished in a cell: an outside part, the protoplasm, and
+an inside part, the nucleus, to leave out of special account
+several others, which, by the way, may only be protoplasmatic
+modifications.</p>
+
+<p>Protoplasm is a mere name for what is not the nucleus;
+in any case it is not a homogeneous chemical compound;
+it consists of many such compounds and has a sort of
+architecture; all organic functions are based upon its
+metabolism. The nucleus has a very typical structure,
+which stands in a close relation to its behaviour during the
+most characteristic morphological period of the cell: during
+its division. Let us devote a few words to a consideration
+of this division and the part the nucleus plays in it; it
+will directly bear on future theoretical considerations about
+development.</p>
+
+<p>There is a certain substance in every nucleus of a cell
+which stains most markedly, whenever cells are treated with
+pigments: the name of “chromatin” has been given to it.
+The chromatin always gives the reaction of an acid, while
+protoplasm is basic; besides that it seems to be a centre of
+oxidation. Now, when a division of a cell is to occur, the
+chromatin, which had been diffusely distributed before, in
+the form of small grains, arranges itself into a long and<span class="pagenum" title="29"><a name="Page_29" id="Page_29"></a></span>
+very much twisted thread. This thread breaks, as it were
+by sections, into almost equal parts, typical in number for
+each species, and each of these parts is split at full length.<span class="pagenum" title="30"><a name="Page_30" id="Page_30"></a></span>
+A certain number of pairs of small threads, the so-called
+“chromosomes,” are the ultimate result of this process,
+which intentionally has been described a little schematically,
+the breaking and the splitting in fact going on simultaneously
+or occasionally even in reverse order. While
+what we have described is performing in the nucleus, there
+have happened some typical modifications in protoplasm, and
+then, by an interaction of protoplasmatic and nuclear factors,
+the first step in the actual division of the cell begins. Of
+each pair of the small threads of chromatin one constituent
+is moved to one side of the cell, one to the other; two
+daughter-nuclei are formed in this way; the protoplasm
+itself at the same time forms a circular furrow between them;
+the furrow gets deeper and deeper; at last it cuts the cell
+in two, and the division of the cell is accomplished.</p>
+
+<p>Not only is the growth of the already typically formed
+organism carried out by a series of cell-divisions, but also
+development proper in our sense, as a “production of visible
+manifoldness,” is realised to a great extent by the aid of
+such divisions, which therefore may indeed be said to be of
+very fundamental importance (Fig. 1).</p>
+
+<div class="figcenter" style="width: 420px;">
+<img src="images/fig01.jpg" width="420" height="460" alt="" />
+<p><span class="smcap">Fig. 1.&mdash;Diagram of Cell-Division</span> (<em>after</em> Boveri).</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Resting cell; the chromatin distributed in the form of small granules inside the nucleus. Outside the nucleus is the “centrosome,” not mentioned in the text.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Beginning of division; the chromatin arranged in the form of a long thread. Centrosome divided in two.</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td class="tal ti">The thread of chromatin cut into four parts, the “chromosomes.”</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">The four parts of the chromatin arranged symmetrically between the centrosomes and the star-like “spheres.”</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Each of the chromosomes split at full length.</td></tr>
+<tr><td class="tar vat"><i>f.</i></td><td class="tal ti">Beginning of division of protoplasm; the two parts of each chromosome separated.</td></tr>
+<tr><td class="tar vat"><i>g.</i></td><td class="tal ti">End of cell-division.</td></tr>
+</table>
+</div>
+
+<p>Each cell-division which promotes growth is followed by
+the enlargement of the two daughter-cells which result from
+it; these two daughter-elements attain the exact size of the
+mother-cell before division, and as soon as this size is reached
+a new division begins: so the growth of the whole is in
+the main the result of the growth of the elements. Cell-divisions
+during real organ-formation may behave differently,
+as will be described at a proper occasion.</p>
+
+<p><span class="pagenum" title="31"><a name="Page_31" id="Page_31"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Egg: its Maturation and Fertilisation</span></p>
+
+<p>We know that all the organs of an animal or plant consist
+of cells, and we know what acts a cell can perform.
+Now there is one very important organ in all living beings,
+which is devoted to reproduction. This organ, the so-called
+ovary in animals, is also built up of cells, and its single cells
+are called the eggs; the eggs originated by cell-division, and
+cell-division is to lead from them to the new adult.</p>
+
+<p>But, with a very few exceptions, the egg in the ovary is
+not able to accomplish its functions, unless certain typical
+events have occurred, some of which are of a merely preparatory
+kind, whilst the others are the actual stimulus
+for development.</p>
+
+<p>The preparatory ones are generally known under the
+name of “maturation.” The egg must be “mature,” in
+order that it may begin development, or even that it may
+be stimulated to it. Maturation consists of a rather complicated
+series of phenomena: later on we shall have
+occasion to mention, at least shortly, what happens in the
+protoplasm during its course; as to the nuclear changes
+during maturation it may be enough for our purposes to say,
+that there occur certain processes among the chromosomes,
+which lead to an extension of half of them in the form of
+two very small cells, the “directive cells” or “directive
+or polar bodies,” as they have been somewhat cautiously
+called.</p>
+
+<p>The ripe or mature egg is capable of being fertilised.</p>
+
+<p>Before turning to this important fact, which, by the way,
+will bring us to our specially chosen type, the Echinus, a
+few words may be devoted to the phenomenon of <span class="pagenum" title="32"><a name="Page_32" id="Page_32"></a></span>“parthenogenesis,”
+that is to say, the possibility of development without
+fertilisation, since owing to the brilliant discoveries of the
+American physiologist, Jacques Loeb, this topic forms one
+of the centres of biological interest at present. It has long
+been known that the eggs of certain bees, lice, crayfishes,
+and other animals and also plants, are capable of development
+without fertilisation at all. Now Richard Hertwig
+and T. H. Morgan already had shown, that at least nuclear
+division may occur in the eggs of other forms&mdash;in the egg of
+the sea-urchin for instance&mdash;when these eggs are exposed to
+some chemical injuries. But <span class="nowrap">Loeb<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">4</a></span> succeeded in obtaining
+a full development by treating the eggs of echinoderms with
+chloride of magnesium; thus artificial parthenogenesis had
+been discovered. Later researches have shown that artificial
+parthenogenesis may occur in all classes of the animal
+kingdom and may be provoked by all sorts of chemical or
+physical means. We do not know at present in what the
+proper stimulus consists that must be supposed here to
+take the place of fertilisation; it seems, of course, highly
+probable that it is always the same in the last <span class="nowrap">resort.<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">5</a></span></p>
+
+<p>But enough about processes, which at present are of a
+highly scientific, but hardly of any philosophic interest.</p>
+
+<p>By fertilisation proper we understand the joining of the
+male element, the spermatozoon or the spermia, with the
+female element, the egg. Like the egg, the spermatozoon is
+but a cell, though the two differ very much from one another<span class="pagenum" title="33"><a name="Page_33" id="Page_33"></a></span>
+in the relation between their protoplasm and nucleus: in all
+eggs it is the protoplasm which is comparatively very large,
+if held together with somatic cells, in the spermatozoon it
+is the nucleus. A large amount of reserve material, destined
+for the growth of the future being, is the chief cause of
+the size of the egg-protoplasm. The egg is quite or almost
+devoid of the faculty of movement, while on the contrary,
+movement is the most typical feature of the spermia. Its
+whole organisation is adapted to movement in the most
+characteristic manner: indeed, most spermatozoa resemble
+a swimming infusorium, of the type of Flagellata, a so-called
+head and a moving tail are their two chief constituents;
+the head is formed almost entirely of nuclear substance.</p>
+
+<p>It seems that in most cases the spermatozoa swim
+around at random and that their union with the eggs is
+assured only by their enormous number; only in a few
+cases in plants have there been discovered special stimuli of
+a chemical nature, which attract the spermia to the egg.</p>
+
+<p>But we cannot enter here more fully into the physiology
+of fertilisation, and shall only remark that its real significance
+is by no means <span class="nowrap">clear.<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">6</a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The First Development Process of Echinus</span></p>
+
+<p>Turning now definitively to the special kind of organism,
+chosen of our type, the common sea-urchin, we properly<span class="pagenum" title="34"><a name="Page_34" id="Page_34"></a></span>
+begin with a few words about the absolute size of its eggs
+and spermatozoa. All of you are familiar with the eggs of
+birds and possibly of frogs; these are abnormally large
+eggs, on account of the very high amount of reserve
+material they contain. The almost spherical egg of our
+Echinus only measures about a tenth of a millimetre in
+diameter; and the head of the spermatozoon has a volume
+which is only the four-hundred-thousandth part of the
+volume of the egg! The egg is about on the extreme limit
+of what can be seen without optical instruments; it is
+visible as a small white point. But the number of eggs
+produced by a single female is enormous and may amount
+to hundreds of thousands; this is one of the properties
+which render the eggs of Echinus so very suitable for
+experimental research; you can obtain them whenever and
+in any quantity you like; and, moreover, they happen to
+be very clear and transparent, even in later stages, and to
+bear all kinds of operations well.</p>
+
+<p>The spermia enters the egg, and it does so in the open
+water&mdash;another of the experimental advantages of our type.
+Only one spermia enters the egg in normal cases, and only
+its head goes in, the tail is left outside. The moment
+that the head has penetrated the protoplasm of the egg a
+thin membrane is formed by the latter. This membrane is
+very soft at first, becoming much stronger later on; it is
+very important for all experimental work, that by shaking
+the egg in the first minutes of its existence the membrane
+can easily be destroyed without any damage to the egg itself.</p>
+
+<p>And now occurs the chief phenomenon of fertilisation:
+the nucleus of the spermatozoon unites with the nucleus of
+the egg. When speaking of maturation, we mentioned that<span class="pagenum" title="35"><a name="Page_35" id="Page_35"></a></span>
+half of the chromatin was thrown out of the egg by that
+process: now this half is brought in again, but comes from
+another individual.</p>
+
+<p>It is from this phenomenon of nuclear union as the
+main character of fertilisation that almost all theories of
+heredity assume their right to regard the nuclei of the
+sexual cells as the true “seat” of inheritance. Later on
+we shall have occasion to discuss this hypothesis from the
+point of view of logic and fact.</p>
+
+<p>After the complete union of what are called the male
+and the female “pronuclei,” the egg begins its development;
+and this development, in its first steps, is simply pure cell-division.
+We know already the chief points of this process,
+and need only add to what has been described, that in the
+whole first series of the cell-divisions of the egg, or, to use
+the technical term, in the whole process of the “cleavage”
+or “segmentation” of it, there is never any growth of the
+daughter-elements after each division, such as we know to
+occur after all cell-divisions of later embryological stages.
+So it happens, that during cleavage the embryonic cells
+become smaller and smaller, until a certain limit is reached;
+the sum of the volumes of all the cleavage cells together
+is equal to the volume of the egg.</p>
+
+<p>But our future studies will require a more thorough
+knowledge of the cleavage of our Echinus; the experimental
+data we shall have to describe later on could hardly be
+properly understood without such knowledge. The first
+division plane, or, as we shall say, the first cleavage plane,
+divides the eggs into equal parts; the second lies at right
+angles to the first and again divides equally: we now have
+a ring of four cells. The third cleavage plane stands at<span class="pagenum" title="36"><a name="Page_36" id="Page_36"></a></span>
+right angles to the first two; it may be called an equatorial
+plane, if we compare the egg with a globe; it also divides
+equally, and so we now find two rings, each consisting of
+four cells, and one above the other. But now the cell-divisions
+cease to be equal, at least in one part of the egg:
+the next division, which leads from the eight- to the
+sixteen-cell stage of cleavage, forms four rings, of four
+cells each, out of the two rings of the eight-cell stage.
+Only in one half of the germ, in which we shall call the upper
+one, or which we might call, in comparison with a globe,
+the northern hemisphere, are cells of equal size to be found;
+in the lower half of the egg four very small cells have been
+formed at one “pole” of the whole germ. We call these
+cells the “micromeres,” that is, the “small parts,” on the
+analogy of the term “blastomeres,” that is, parts of the germ,
+which is applied to all the cleavage cells in general. The
+place occupied by the micromeres is of great importance
+to the germ as a whole: the first formation of real organs
+will start from this point later on. It is sufficient thus
+fully to have studied the cleavage of our Echinus up to
+this stage: the later cleavage stages may be mentioned
+more shortly. All the following divisions are into equal
+parts; there are no other micromeres formed, though, of
+course, the cells derived from the micromeres of the sixteen-cell
+stage always remain smaller than the rest. All the
+divisions are tangential; radial cleavages never occur, and
+therefore the process of cleavage ends at last in the formation
+of one layer of cells, which forms the surface of a
+sphere; it is especially by the rounding-up of each blastomere,
+after its individual appearance, that this real surface
+layer of cells is formed, but, of course, the condition, that<span class="pagenum" title="37"><a name="Page_37" id="Page_37"></a></span>
+no radial divisions occur, is the most important one in its
+formation. When 808 blastomeres have come into existence
+the process of cleavage is finished; a sphere with a wall
+of cells and an empty interior is the result. That only
+808 cells are formed, and not, as might be expected, 1024,
+is due to the fact that the micromeres divide less often
+than the other elements; but speaking roughly, of course,
+we may say that there are ten steps of cleavage-divisions
+in our form; 1024 being equal to 2<sup>10</sup>.</p>
+
+<p>We have learned that the first process of development,
+the cleavage, is carried out by simple cell-division. A few
+cases are known, in which cell-division during cleavage is
+accompanied by a specific migration of parts of the
+protoplasm in the interior of the blastomeres, especially in
+the first two or first four; but in almost all instances
+cleavage is as simple a process of mere division as it is in
+our sea-urchin. Now the second step in development, at
+least in our form, is a typical histological performance: it
+gives a new histological feature to all of the blastomeres:
+they acquire small cilia on their outer side and with these
+cilia the young germ is able to swim about after it has
+left its membrane. The germ may be called a “blastula”
+at this stage, as it was first called by Haeckel, whose
+useful denominations of the first embryonic stages may
+conveniently be applied, even if one does not agree with
+most, or perhaps almost all, of his speculations (Fig. 2).</p>
+
+<div class="figcenter" style="width: 428px;">
+<img src="images/fig02.jpg" width="428" height="337" alt="" />
+<p><span class="smcap">Fig. 2.&mdash;Early Development of Echinus, the Common Sea-urchin.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Two cells.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Four cells.</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td  class="tal ti">Eight cells, arranged in two rings of four, above one another.</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">Sixteen cells, four “micromeres” formed at the “vegetative” pole.</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Optical section of the “blastula,” a hollow sphere consisting of about one thousand cells, each of them with a small cilium.</td></tr>
+</table>
+</div>
+
+<p>It is important to notice that the formation of the
+“blastula” from the last cleavage stage is certainly a
+process of organisation, and may also be called a
+differentiation with regard to that stage. But there is in
+the blastula no trace of one <em>part</em> of the germ becoming<span class="pagenum" title="38"><a name="Page_38" id="Page_38"></a></span>
+different with respect to others of its parts. If development
+were to go on in this direction alone, high organisatory
+complications might occur: but there would always be
+only one sort of cells, arranged in a sphere; there would
+be only one kind of what is called “tissue.”</p>
+
+<p>But in fact development very soon loads to true
+differences of the parts of the germ with respect to one
+another, and the next step of the process will enable us
+to apply different denominations to the different parts of
+the embryo.</p>
+
+<p>At one pole of the swimming blastula, exactly at the
+point where the descendants of the micromeres are situated,<span class="pagenum" title="39"><a name="Page_39" id="Page_39"></a></span>
+about fifty cells lose contact with their neighbours and
+leave the surface of the globe, being driven into the interior
+space of it. Not very much is known about the exact
+manner in which these changes of cellular arrangement
+are carried out, whether the cells are passively pressed by
+their neighbours, or whether, perhaps, in a more active
+manner, they change their surface conditions; therefore,
+as in most ontogenetic processes, the description had best
+be made cautiously in fairly neutral or figurative words.</p>
+
+<p>The cells which in the above manner have entered the
+interior of the blastula are to be the foundation of important
+parts of the future organism; they are to form its connective
+tissue, many of its muscles, and the skeleton. “Mesenchyme,”
+<i>i.e.</i> “what has been infused into the other parts,” is the
+technical name usually applied to these cells. We now
+have to learn their definite arrangement. At first they lie
+as a sort of heap inside the cell wall of the blastula, inside
+the “blastoderm,” <i>i.e.</i> skin of the germ. But soon they
+move from one another, to form a ring round the pole at
+which they entered, and on this ring a process takes place
+which has a very important bearing upon the whole type of
+the organisation of the germ. You will have noticed that
+hitherto the germ with regard to its symmetry has been a
+monaxial or radial formation; the cleavage stages and the
+blastula with its mesenchyme were forms with two different
+poles, lying at the ends of one single line, and round this
+line everything was arranged concentrically. But now
+what is called “bilateral symmetry” is established; the
+mesenchyme ring assumes a structure which can be
+symmetrically divided only by one plane, but divided in
+such a way, that one-half of it is the mirror image of the<span class="pagenum" title="40"><a name="Page_40" id="Page_40"></a></span>
+other. A figure shows best what has occurred, and you will
+notice (Fig. 3) two masses of cells in this figure, which
+have the forms of spherical triangles: it is in the midst of
+these triangles that the skeleton of the larva <em>originates</em>.
+The germ had an upper and a lower side before: it now
+has got an upper and lower, front and back, <em>right and left</em>
+half; it now has acquired that symmetry of organisation
+which our own body has; at least it has got it as far as
+its mesenchyme is concerned.</p>
+
+<div class="figcenter" style="width: 424px;">
+<img src="images/fig03.jpg" width="424" height="250" alt="" />
+<p><span class="smcap">Fig. 3.&mdash;Formation of Mesenchyme in Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i>&nbsp;&nbsp;</td><td class="tal ti">Outlines of blastula, side-view; mesenchyme forms a heap of cells at the “vegetative” pole.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>1</sub>.</td><td class="tal ti">Heap of mesenchyme-cells from above.</td></tr>
+<tr><td class="tar vat"><i>b.</i>&nbsp;&nbsp;</td><td class="tal ti">Mesenchyme-cells arranged in a ring round the vegetative pole.</td></tr>
+<tr><td class="tar vat"><i>c.</i>&nbsp;&nbsp;</td><td class="tal ti">Mesenchyme-cells arranged in a bilateral-symmetrical figure; primordia of skeleton in the midst of two spherical triangles.</td></tr>
+</table>
+</div>
+
+<p>We leave the mesenchyme for a while and study another
+kind of organogenesis. At the very same pole of the germ
+where the mesenchyme cells originated there is a long and
+narrow tube of cell growing in, and this tube, getting longer
+and longer, after a few hours of growth touches the opposite
+pole of the larva. The growth of this cellular tube marks<span class="pagenum" title="41"><a name="Page_41" id="Page_41"></a></span>
+the beginning of the formation of the intestine, with all
+that is to be derived from it. The larva now is no longer
+a blastula, but receives the name of “gastrula” in Haeckel’s
+terminology; it is built up of the three “germ-layers” in
+this stage. The remaining part of the blastoderm is called
+“ectoderm,” or outer layer; the newly-formed tube,
+“endoderm,” or inner layer; while the third layer is the
+“mesenchyme” already known to us.</p>
+
+<p>The endoderm itself is a radial structure at first, as
+was the whole germ in a former stage, but soon its free
+end bends and moves against one of the sides of the
+ectoderm, against that side of it where the two triangles
+of the mesenchyme are to be found also. Thus the endoderm
+has acquired bilateral symmetry just as the mesenchyme
+before, and as in this stage the ectoderm also
+assumes a bilateral symmetry in its form, corresponding
+with the symmetrical relations in the endoderm and the
+mesenchyme, we now may call the whole of our larva a
+bilateral-symmetrical organisation.</p>
+
+<p>It cannot be our task to follow all the points of organogenesis
+of Echinus in detail. It must suffice to state
+briefly that ere long a second portion of the mesenchyme
+is formed in the larva, starting from the free end of
+its intestine tube; that the formation of the so-called
+“coelum” occurs by a sort of splitting off from this same
+original organ; and that the intestine itself is divided
+into three parts of different size and aspect by two circular
+sections.</p>
+
+<p>But we must not, I think, dismiss the formation of the
+skeleton so quickly. I told you already that the skeleton
+has its first origin in the midst of the two triangular<span class="pagenum" title="42"><a name="Page_42" id="Page_42"></a></span>
+cell-masses of the mesenchyme; but what are the steps before
+it attains its typical and complicated structure? At the
+beginning a very small tetrahedron, consisting of carbonate
+of calcium, is formed in each of the triangles; the four edges
+of the tetrahedron are produced into thin rods, and by
+means of a different organogenesis along each of these
+rods the typical formation of the skeleton proceeds. But
+the manner in which it is carried out is very strange
+and peculiar. About thirty of the mesenchyme cells are
+occupied in the formation of skeleton substance on each
+side of the larva. They wander through the interior space of
+the gastrula&mdash;which at this stage is not filled with sea
+water but with a sort of gelatinous material&mdash;and wander
+in such a manner that they always come to the right places,
+where a part of the skeleton is to be formed; they form it
+by a process of secretion, quite unknown in detail; one of
+them forms one part, one the other, but what they form
+altogether, is one whole.</p>
+
+<p>When the formation of the skeleton is accomplished, the
+typical larva of our Echinus is built up; it is called the
+“pluteus” (Fig. 4). Though it is far from being the
+perfect adult animal, it has an independent life of its own;
+it feeds and moves about and does not go through any
+important changes of form for weeks. But after a certain
+period of this species of independent life as a “larva,” the
+changes of form it undergoes again are most fundamental:
+it must be transformed into the adult sea-urchin, as all of
+you know. There are hundreds and hundreds of single
+operations of organogenesis to be accomplished before that
+end is reached; and perhaps the strangest of all these
+operations is a certain sort of growth, by which the symmetry<span class="pagenum" title="43"><a name="Page_43" id="Page_43"></a></span>
+of the animal, at least in certain of its parts&mdash;not in all of
+them&mdash;is changed again from bilateral to radial, just the
+opposite of what happened in the very early stages.</p>
+
+<div class="figcenter" style="width: 392px;">
+<img src="images/fig04.jpg" width="392" height="317" alt="" />
+<p><span class="smcap">Fig. 4.&mdash;Larval Development of Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>A.</i></td><td class="tal ti">The gastrula.</td></tr>
+<tr><td class="tar vat"><i>B.</i></td><td class="tal ti">Later stage, bilateral-symmetrical. Intestine begins to divide into three parts.</td></tr>
+<tr><td class="tar vat"><i>C.</i></td><td class="tal ti">Pluteus larva. S = Skeleton. I = Intestine.</td></tr>
+</table>
+</div>
+
+<p>But we cannot follow the embryology of our Echinus
+further here; and indeed we are the less obliged to do so,
+since in all our experimental work we shall have to deal
+with it only as far as to the pluteus larva. It is impossible
+under ordinary conditions to rear the germs up to the adult
+stages in captivity.</p>
+
+<p>You now, I hope, will have a general idea at least of the
+processes of which the individual development of an animal
+consists. Of course the specific features leading from the
+egg to the adult are different in each specific case, and, in<span class="pagenum" title="44"><a name="Page_44" id="Page_44"></a></span>
+order to make this point as clear as possible, I shall now
+add to our description a few words about what may be
+called a comparative descriptive embryology.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Comparative Embryology</span></p>
+
+<p>Even the cleavage may present rather different aspects.
+There may be a compact blastula, not one surrounded by
+only one layer of cells as in Echinus; or bilaterality may be
+established as early as the cleavage stage&mdash;as in many
+worms and in ascidians&mdash;and not so late as in Echinus.
+The formation of the germ layers may go on in a different
+order and under very different conditions: a rather close
+relative of our Echinus, for instance, the starfish, forms
+first the endoderm and afterwards the mesenchyme. In
+many cases there is no tube of cells forming the “endoderm,”
+but a flat layer of cells is the first foundation of all the
+intestinal organs: so it is in all birds and in the cuttlefish.
+And, as all of you know, of course, there are very many
+animal forms which have no proper “larval” stage: there
+is one in the frog, the well-known “tadpole,” but the birds
+and mammals have no larvae; that is to say, there is no
+special stage in the ontogeny of these forms which leads an
+independent life for a certain time, as if it were a species
+by itself, but all the ontogenetical stages are properly “embryonic”&mdash;the
+germ is always an “embryo” until it becomes
+the perfect young organism. And you also know that not
+all skeletons consist of carbonate of calcium, but, that there
+are skeletons of silicates, as in Radiolaria, and of horny
+substance, as in many sponges. And, indeed, if we were to
+glance at the development of plants also, the differences<span class="pagenum" title="45"><a name="Page_45" id="Page_45"></a></span>
+would seem to us probably so great that all the similarities
+would seem to disappear.</p>
+
+<p>But there are similarities, nevertheless, in all development,
+and we shall now proceed to examine what they are. As
+a matter of fact, it was especially for their sake that we
+studied the ontogeny of a special form in such detail; one
+always sees generalities better if one knows the specific
+features of at least one case. What then are the features
+of most general and far-reaching importance, which may be
+abstracted from the individual history of our sea-urchin,
+checked always by the teachings of other ontogenies, including
+those of plants?</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The First Steps of Analytical Morphogenesis</span></p>
+
+<p>If we look back upon the long fight of the schools of
+embryologists in the eighteenth century about the question
+whether individual development was to be regarded as a real
+production of visible manifoldness or as a simple growth of
+visibly pre-existing manifoldness, whether it was “epigenesis”
+or “evolutio,” there can be no doubt, if we rely
+on all the investigations of the last hundred and fifty years,
+that, taken in the descriptive sense, the theory of epigenesis
+is right. Descriptively speaking there <em>is</em> a production of
+visible manifoldness in the course of embryology: that is
+our first and main result. Any one possessed of an average
+microscope may any day convince himself personally that
+it is true.</p>
+
+<p>In fact, true epigenesis, in the descriptive sense of the
+term, does exist. One thing is formed “after” the other;
+there is not a mere “unfolding” of what existed already,<span class="pagenum" title="46"><a name="Page_46" id="Page_46"></a></span>
+though in a smaller form; there is no “evolutio” in the old
+meaning of the word.</p>
+
+<p>The word “evolution” in English usually serves to denote
+the theory of descent, that is of a real relationship of all
+organisms. Of course we are not thinking here of this
+modern and specifically English meaning of the Latin word
+<i lang="la" xml:lang="la">evolutio</i>. In its ancient sense it means to a certain degree
+just the opposite; it says that there is no formation of anything
+new, no transformation, but simply growth, and this is
+promoted not for the race but for the individual. Keeping
+well in mind these historical differences in the meaning of
+the word “evolutio,” no mistakes, it seems to me, can occur
+from its use. We now shall try to obtain a few more
+particular results from our descriptive study of morphogenesis,
+which are nevertheless of a general bearing, being
+real characteristics of organic individual development, and
+which, though not calculated of themselves to further the
+problem, will in any case serve to prepare for a more
+profound study of it.</p>
+
+<p>The totality of the line of morphogenetic facts can easily
+be resolved into a great number of distinct processes. We
+propose to call these “elementary morphogenetic processes”;
+the turning in of the endoderm and its division into three
+typical parts are examples of them. If we give the name
+“elementary organs” to the distinct parts of every stage of
+ontogeny which are uniform in themselves and are each
+the result of one elementary process in our sense, we are
+entitled to say that each embryological stage consists of a
+certain number of elementary organs. The mesenchyme ring,
+the coelum, the middle-intestine, are instances of such organs.
+It is important to notice well that the word elementary is<span class="pagenum" title="47"><a name="Page_47" id="Page_47"></a></span>
+always understood here with regard to visible morphogenesis
+proper and does not apply to what may be called elementary
+in the physiological sense. An elementary process in our
+sense is a very distinct act of form-building, and an elementary
+organ is the result of every one of such acts.</p>
+
+<p>The elementary organs are typical with regard to their
+position and with regard to their histological properties.
+In many cases they are of a very clearly different histological
+type, as for instance, the cells of the three so-called
+germ-layers; and in other cases, though apparently almost
+identical histologically, they can be proved to be different
+by their different power of resisting injuries or by other
+means. But there are not as many different types of
+histological structure as there are typically placed organs:
+on the contrary there are many elementary organs of the
+same type in different typical parts of the organism, as all
+of you know to be the case with nerves and muscles. It
+will not be without importance for our future theory of
+development, carefully to notice this fact, that specialisation
+in the <em>position</em> of embryonic parts is more strict than
+in their histology.</p>
+
+<p>But elementary organs are not only typical in position
+and histology, they are typical also with regard to their
+form and their relative size. It agrees with what has been
+said about histology being independent of typical position,
+that there may be a number of organs in an embryonic
+stage, all in their most typical positions, which though all
+possessing the same histology, may have different forms or
+different sizes or both: the single bones of the skeleton of
+vertebrates or of adult echinoderms are the very best instances
+of this most important feature of organogenesis. If we look<span class="pagenum" title="48"><a name="Page_48" id="Page_48"></a></span>
+back from elementary organs to elementary processes, the
+specialisation of the size of those organs may also be said to
+be the consequence of a typical duration of the elementary
+morphogenetic process leading to <span class="nowrap">them.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">7</a></span></p>
+
+<p>I hardly need to say, that the histology, form, and size
+of elementary organs are equally an expression of their
+present or future physiological function. At least they
+prepare for this function by a specific sort of metabolism
+which sets in very early.</p>
+
+<p>The whole sequence of individual morphogenesis has
+been divided by some embryologists into two different
+periods; there is a first period, during which the foundations
+of the organisation of the “type” are laid down, and a
+second period, during which the histo-physiological specifications
+are modelled out (von Baer, Götte, Roux). Such a
+discrimination is certainly justified, if not taken too strictly;
+but its practical application would encounter certain
+difficulties in many larval forms, and also, of course, in
+all plants.</p>
+
+<p>Our mention of plants leads us to the last of our
+analytical results. If an animal germ proceeds in its
+development from a stage <i>d</i> to the stage <i>g</i>, passing through
+<i>e</i> and <i>f</i>, we may say that the whole of <i>d</i> has become the
+whole of <i>f</i>, but we cannot say that there is a certain part of
+<i>f</i> which is <i>d</i>, we cannot say that <i>f</i> is <i>d</i> + <i>a</i>. But in plants
+we can: the stage <i>f</i> is indeed equal to <i>a</i> + <i>b</i> + <i>c</i> + <i>d</i> + <i>e</i> + <ins title="Transcriber's Note: ? typo for f "><i>a</i></ins> in vegetable organisms; all earlier stages are actually visible
+as parts of the last one. The great embryologist, Carl Ernst<span class="pagenum" title="49"><a name="Page_49" id="Page_49"></a></span>
+von Baer, most clearly appreciated these analytical differences
+between animal and vegetable morphogenesis. They become
+a little less marked if we remember that plants, in a
+certain respect, are not simple individuals but colonies, and
+that among the corals, hydroids, bryozoa, and ascidia, we
+find analogies to plants in the animal kingdom; but nevertheless
+the differences we have stated are not extinguished
+by such reasoning. It seems almost wholly due to the
+occurrence of so many foldings and bendings and migrations
+of cells and complexes of cells in animal morphogenesis, that
+an earlier stage of their development seems <em>lost</em> in the later
+one; those processes are almost entirely wanting in plants,
+even if we study their very first ontogenetic stages. If we
+say that almost all production of surfaces goes on outside
+in plants, inside in animals, we shall have adequately
+described the difference. And this feature again leads to
+the further diversity between animals and plants which is
+best expressed by calling the former “closed,” the latter
+“open” forms: animals reach a point where they are
+finished, plants never are finished, at least in most cases.</p>
+
+<p>I hope you will allow that I have tried to draw from
+descriptive and comparative embryology as many general
+analytical results as are possibly to be obtained. It is not
+my fault if there are not any more, nor is it my fault if the
+results reached are not of the most satisfactory character.
+You may say that these results perhaps enable you to see a
+little more clearly and markedly than before a few of the
+characters of development, but that you have not really
+learnt anything new. Your disappointment&mdash;my own
+disappointment&mdash;in our analysis is due to the use of pure
+description and comparison as scientific methods.</p>
+
+<p><span class="pagenum" title="50"><a name="Page_50" id="Page_50"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Limits of Pure Description in Science</span></p>
+
+<p>We have analysed our descriptions as far as we could,
+and now we must confess that what we have found cannot
+be the last thing knowable about individual morphogenesis.
+There must be something deeper to be discovered: we only
+have been on the surface of the phenomena, we now want
+to get to the very bottom of them. Why then occurs all
+that folding, and bending, and histogenesis, and all the other
+processes we have described? There must be something
+that drives them out, so to say.</p>
+
+<p>There is a very famous dictum in the <cite>Treatise on
+Mechanics</cite> by the late Gustav Kirchhoff, that it is the task
+of mechanics to describe completely and in the most simple
+manner all the motions that occur in nature. These words,
+which may appear problematic even in mechanics, have
+had a really pernicious influence on biology. People were
+extremely pleased with them. “‘Describing’&mdash;that is just
+what we always have done,” they said; “now we see that we
+have done just what was right; a famous physicist has told
+us so.” They did not see that Kirchhoff had added the
+words “completely and in the most simple manner”; and
+moreover, they did not consider that Kirchhoff never regarded
+it as the ultimate aim of physics to describe thunderstorms
+or volcanic eruptions or denudations; yet it only is with
+such “descriptions” that biological descriptions of <em>given</em>
+bodies and processes are to be compared!</p>
+
+<p>Physicists always have used both experiment and hypothetical
+construction&mdash;Kirchhoff himself did so in the most
+gifted manner. With these aids they have gone through the
+whole of the phenomena, and what they found to be ultimate<span class="pagenum" title="51"><a name="Page_51" id="Page_51"></a></span>
+and truly elemental, that alone may they be said to have
+“described”; but they have “explained” by the aid of
+elementalities what proved to be not elemental in <span class="nowrap">itself.<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">8</a></span></p>
+
+<p>It is the <em>method</em> of the physicists&mdash;not their results&mdash;that
+morphogenesis has to apply in order to make progress;
+and this method we shall begin to apply in our next lectures.
+Physiology proper has never been so short-sighted and self-satisfied
+as not to learn from other sciences, from which
+indeed there was very much to be learned; but morphology
+has: the bare describing and comparing of descriptions has
+been its only aim for about forty years or more, and lines
+of descent of a very problematic character were its only
+general results. It was not seen that science had to begin,
+not with problematic events of the past, but with what
+actually happens before our eyes.</p>
+
+<p>But before saying any more about the exact rational
+and experimental method in morphology, which indeed may
+be regarded as a new method, since its prevalence in the
+eighteenth century had been really forgotten, we first shall
+have to analyse shortly some general attempts to understand
+morphogenesis by means of hypothetic construction exclusively.
+Such attempts have become very important
+as points of issue for really exact research, and, moreover,
+they deserve attention, because they prove that their authors
+at least had not quite forgotten that there were still other
+problems to be solved in morphology than only phylogenetical
+ones.</p>
+
+<hr />
+
+<p><span class="pagenum" title="52"><a name="Page_52" id="Page_52"></a></span></p>
+
+
+
+
+<h3><i>B.</i> EXPERIMENTAL AND THEORETICAL MORPHOGENESIS</h3>
+
+<h4 class="fs120">1. <span class="smcap">The Foundations of the Physiology of Development.<br />
+“Evolutio” and “Epigenesis”</span></h4>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE THEORY OF WEISMANN</span></p>
+
+<p>Of all the purely hypothetic theories on morphogenesis
+that of August <span class="nowrap">Weismann<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">9</a></span> can claim to have had the
+greatest influence, and to be at the same time the most
+logical and the most elaborated. The “germ-plasma”
+theory of the German author is generally considered as
+being a theory of heredity, and that is true inasmuch as
+problems of inheritance proper have been the starting-point
+of all his hypothetic speculations, and also form in some
+respect the most valuable part of them. But, rightly understood,
+Weismann’s theory consists of two independent parts,
+which relate to morphogenesis and to heredity separately,
+and it is only the first which we shall have to take into
+consideration at present; what is generally known as the
+doctrine of the “continuity of the germ-plasm” will be
+discussed in a later chapter.</p>
+
+<p>Weismann assumes that a very complicated organised
+structure, below the limits of visibility even with the<span class="pagenum" title="53"><a name="Page_53" id="Page_53"></a></span>
+highest optical powers, is the foundation of all morphogenetic
+processes, in such a way that, whilst part of this
+structure is handed over from generation to generation as
+the basis of heredity, another part of it is disintegrated
+during the individual development, and directs development
+by being disintegrated. The expression, “part” of the
+structure, first calls for some explanation. Weismann
+supposes several examples, several copies, as it were, of his
+structure to be present in the germ cells, and it is to these
+copies that the word “part” has been applied by us: at least
+one copy has to be disintegrated during ontogeny.</p>
+
+<p>The morphogenetic structure is assumed to be present in
+the nucleus of the germ cells, and Weismann supposes
+the disintegration of his hypothetic structure to be accomplished
+by nuclear division. By the cleavage of the egg,
+the most <em>fundamental</em> parts of it are separated one from
+the other. The word “fundamental” must be understood
+as applying not to proper elements or complexes of
+elements of the organisation, but to the chief relations
+of symmetry; the first cleavage, for instance, may separate
+the right and the left part of the structure, the second one
+its upper and lower parts, and after the third or equatorial
+cleavage all the principal eighths of our minute organisation
+are divided off: for the minute organisation, it must
+now be added, had been supposed to be built up differently
+in the three directions of space, just as the adult organism
+is. Weismann concedes it to be absolutely unknown in
+what manner the proper relation between the parts of the
+disintegrated fundamental morphogenetic structure and the
+real processes of morphogenesis is realised; enough that there
+may be imagined such a relation.</p>
+
+<p><span class="pagenum" title="54"><a name="Page_54" id="Page_54"></a></span></p>
+
+<p>At the end of organogenesis the structure is assumed to
+have been broken up into its elements, and these elements,
+which may be chemical compounds, determine the fate of
+the single cells of the adult organism.</p>
+
+<p>Here let us pause for a moment. There cannot be any
+doubt that Weismann’s theory resembles to a very high
+degree the old “evolutio” doctrines of the eighteenth
+century, except that it is a little less crude. The chick itself
+is not supposed to be present in the hen’s egg before development,
+and ontogeny is not regarded as a mere growth of
+that chick in miniature, but what really is supposed to be
+present in the egg is nevertheless a something that in all its
+parts corresponds to all the parts of the chick, only under
+a somewhat different aspect, while all the relations of the
+parts of the one correspond to the relations of the parts
+of the other. Indeed, only on such an hypothesis of a
+fairly fixed and rigid relation between the parts of the
+morphogenetic structure could it be possible for the
+disintegration of the structure to go on, not by parts of
+organisation, but by parts of symmetry; which, indeed, is
+a very strange, but not an illogical, feature of Weismann’s
+doctrine.</p>
+
+<p>Weismann is absolutely convinced that there must be
+a theory of “evolutio,” in the old sense of the word, to
+account for the ontogenetic facts; that “epigenesis” has its
+place only in descriptive embryology, where, indeed, as we
+know, manifoldness in the <em>visible</em> sense is produced, but
+that epigenesis can never form the foundation of a real
+morphogenetic <em>theory</em>: theoretically one pre-existing manifoldness
+is transformed into the other. An epigenetic
+theory would lead right beyond natural science, Weismann<span class="pagenum" title="55"><a name="Page_55" id="Page_55"></a></span>
+thinks, as in fact, all such theories, if fully worked out,
+have carried their authors to vitalistic views. But vitalism
+is regarded by him as dethroned for ever.</p>
+
+<p>Under these circumstances we have a good right, it
+seems to me, to speak of a <em>dogmatic</em> basis of Weismann’s
+theory of development.</p>
+
+<p>But to complete the outlines of the theory itself:
+Weismann was well aware that there were some grave
+difficulties attaching to his statements: all the facts of
+so-called adventitious morphogenesis in plants, of regeneration
+in animals, proved that the morphogenetic organisation could
+not be fully disintegrated during ontogeny. But these
+difficulties were not absolute: they could be overcome:
+indeed, Weismann assumes, that in certain specific cases&mdash;and
+he regarded all cases of restoration of a destroyed
+organisation as due to specific properties of the subjects,
+originated by roundabout variations and natural selection&mdash;that
+in specific cases, specific arrangements of minute
+parts were formed during the process of disintegration, and
+were surrendered to specific cells during development, from
+which regeneration or adventitious budding could originate
+if required. “Plasma of reserve” was the name bestowed
+on these hypothetic arrangements.</p>
+
+<p>Almost independently another German author, Wilhelm
+<span class="nowrap">Roux,<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">10</a></span> has advocated a theoretical view of morphogenesis
+which very closely resembles the hypothesis of Weismann.
+According to Roux a minute ultimate structure is present
+in the nucleus of the germ and directs development by being
+divided into its parts during the series of nuclear divisions.</p>
+
+<p>But in spite of this similarity of the outset, we enter an<span class="pagenum" title="56"><a name="Page_56" id="Page_56"></a></span>
+altogether different field of biological investigation on
+mentioning Roux’s name: we are leaving hypothetic construction,
+at least in its absoluteness, and are entering the
+realms of scientific experiment in morphology.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">EXPERIMENTAL MORPHOLOGY</span></p>
+
+<p>I have told you already in the last lecture that, while
+in the eighteenth century individual morphogenesis had
+formed the centre of biological interest and been studied
+experimentally in a thoroughly adequate manner, that
+interest gradually diminished, until at last the physiology
+of form as an exact separate science was almost wholly
+forgotten. At least that was the state of affairs as regards
+zoological biology; botanists, it must be granted, have never
+lost the historical continuity to such a degree; botany has
+never ceased to be regarded as one science and never was
+broken up into parts as zoology was. Zoological physiology
+and zoological morphology indeed were for many years in a
+relationship to one another not very much closer than the
+relation between philology and chemistry.</p>
+
+<p>There were always a few men, of course, who strove
+against the current. The late Wilhelm <span class="nowrap">His,<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">11</a></span> for instance,
+described the embryology of the chick in an original
+manner, in order to find out the mechanical relations of
+embryonic parts, by which passive deformation, as an
+integrating part of morphogenesis, might be induced. He
+also most clearly stated the ultimate aim of embryology to
+be the mathematical derivation of the adult form from the
+distribution of growth in the germ. To Alexander <span class="nowrap">Goette<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">12</a></span><span class="pagenum" title="57"><a name="Page_57" id="Page_57"></a></span>
+we owe another set of analytical considerations about
+ontogeny. Newport, as early as 1850, and in later years
+Pflüger and Rauber, carried out experiments on the eggs of
+the frog, which may truly be called anticipatory of what
+was to follow. But it was Wilhelm <span class="nowrap">Roux,<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">13</a></span> now professor
+of anatomy at Halle, who entered the field with a thoroughly
+elaborated programme, who knew not only how to state the
+problem analytically, but also how to attack it, fully
+convinced of the importance of what he did. “Entwickelungsmechanik,”&mdash;mechanics
+of development&mdash;he called the “new
+branch of anatomical science” of which he tried to lay the
+foundations.</p>
+
+<p>I cannot let this occasion pass without emphasising in
+the most decided manner how highly in my opinion
+Roux’s services to the systematic exploration of morphogenesis
+must be esteemed. I feel the more obliged to do
+so, because later on I shall have to contradict not only
+many of his positive statements but also most of his
+theoretical views. He himself has lately given up much of
+what he most strongly advocated only ten years ago. But
+Roux’s place in the history of biological science can never
+be altered, let science take what path it will.</p>
+
+<p>It is not the place here to develop the logic of
+experiment; least of all is it necessary in the country
+of John Stuart Mill. All of you know that experiment, by
+its method of isolating the single constituents of complicated
+phenomena, is the principal aid in the discovery of so-called
+causal relations. Let us try then to see what causal<span class="pagenum" title="58"><a name="Page_58" id="Page_58"></a></span>
+relations Wilhelm Roux established with the aid of
+morphogenetic experiment.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE WORK OF WILHELM ROUX</span></p>
+
+<p>We know already that an hypothesis about the foundation
+of individual development was his starting-point. Like
+Weismann he supposed that there exists a very complicated
+structure in the germ, and that nuclear division leads to
+the disintegration of that structure. He next tried to
+bring forward what might be called a number of indicia
+supporting his view.</p>
+
+<p>A close relation had been found to exist in many cases
+between the direction of the first cleavage furrows of the
+germ and the direction of the chief planes of symmetry
+in the adult: the first cleavage, for instance, very often
+corresponds to the median plane, or stands at right
+angles to it. And in other instances, such as have been
+worked out into the doctrine of so-called “cell-lineages,”
+typical cleavage cells were found to correspond to typical
+organs. Was not that a strong support for a theory which
+regarded cellular division as the principal means of
+differentiation? It is true, the close relations between
+cleavage and symmetry did not exist in every case, but
+then there had always happened some specific experimental
+disturbances, <i>e.g.</i> influences of an abnormal direction of
+gravity on account of a turning over of the egg, and it
+was easy to reconcile such cases with the generally accepted
+theory on the assumption of what was called “anachronism”
+of cleavage.</p>
+
+<p>But Roux was not satisfied with mere indicia, he<span class="pagenum" title="59"><a name="Page_59" id="Page_59"></a></span>
+wanted a proof, and with this intention he carried out
+an experiment which has become very <span class="nowrap">celebrated.<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">14</a></span> With a
+hot needle he killed one of the first two blastomeres of
+the frog’s egg after the full accomplishment of its first
+cleavage, and then watched the development of the surviving
+cell. A typical half-embryo was seen to emerge&mdash;an organism
+indeed, which was as much a half as if a fully formed
+embryo of a certain stage had been cut in two by a razor.
+It was especially in the anterior part of the embryo that
+its “halfness” could most clearly be demonstrated.</p>
+
+<p>That seemed to be a proof of Weismann’s and Roux’s
+theory of development, a proof of the hypothesis that there
+is a very complicated structure which promotes ontogeny
+by its disintegration, carried out during the cell divisions
+of embryology by the aid of the process of nuclear division,
+the so-called “karyokinesis.”</p>
+
+<p>To the dispassionate observer it will appear, I suppose,
+that the conclusions drawn by Roux from his experiment
+go a little beyond their legitimate length. Certainly some
+sort of “evolutio” is proved by rearing half the frog from
+half the egg. But is anything proved, is there anything
+discovered at all about the nucleus? It was only on
+account of the common opinion about the part it played
+in morphogenesis that the nucleus had been taken into
+consideration.</p>
+
+<p>Things soon became still more ambiguous.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE EXPERIMENTS ON THE EGG OF THE SEA-URCHIN</span></p>
+
+<p>Roux’s results were published for the first time in
+1888; three years later I tried to repeat his fundamental<span class="pagenum" title="60"><a name="Page_60" id="Page_60"></a></span>
+experiment on another subject and by a somewhat different
+method. It was known from the cytological researches
+of the brothers Hertwig and Boveri that the eggs of the
+common sea-urchin (<i class="biological-name">Echinus microtuberculatus</i>) are able to
+stand well all sorts of rough treatment, and that, in
+particular, when broken into pieces by shaking, their fragments
+will survive and continue to segment. I took
+advantage of these facts for my purposes. I shook the
+germs rather violently during their two-cell stage, and in
+several instances I succeeded in killing one of the blastomeres,
+while the other one was not damaged, or in separating
+the two blastomeres from one <span class="nowrap">another.<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">15</a></span></p>
+
+<p>Let us now follow the development of the isolated
+surviving cell. It went through cleavage just as it would
+have done in contact with its sister-cell, and there occurred
+cleavage stages which were just half of the normal ones.
+The stage, for instance, which corresponded to the normal
+sixteen-cell stage, and which, of course, in my subjects was
+built up of eight elements only, showed two micromeres, two
+macromeres and four cells of medium size, exactly as if a
+normal sixteen-cell stage had been cut in two; and the form
+of the whole was that of a hemisphere. So far there was
+no divergence from Roux’s results.</p>
+
+<p>The development of our Echinus proceeds rather rapidly,
+the cleavage being accomplished in about fifteen hours. I
+now noticed on the evening of the first day of the experiment,
+when the half-germ was composed of about two hundred elements,
+that the margin of the hemispherical germ bent together
+a little, as if it were about to form a whole sphere of smaller
+size, and, indeed, the next morning a <em>whole</em> diminutive<span class="pagenum" title="61"><a name="Page_61" id="Page_61"></a></span>
+blastula was swimming about. I was so much convinced
+that I should get Roux’s morphogenetical result in all its
+features that, even in spite of this whole blastula, I now
+expected that the next morning would reveal to me the
+half-organisation of my subject once more; the intestine, I
+supposed, might come out quite on one side of it, as a half-tube,
+and the mesenchyme ring might be a half one also.</p>
+
+<p>But things turned out as they were bound to do and
+not as I had expected; there was a typically <em>whole</em> gastrula
+on my dish the next morning, differing only by its small
+size from a normal one; and this <em>small but whole</em> gastrula
+was followed by a whole and typical small pluteus-larva
+(Fig. 5).</p>
+
+<div class="figcenter" style="width: 460px;">
+<img src="images/fig05.jpg" width="460" height="320" alt="" />
+<p><span class="smcap">Fig. 5.&mdash;Illustration of Experiments on Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sub>1</sub>&nbsp;and&nbsp;<i>b</i><sub>1</sub>.</td><td class="tal ti">Normal gastrula and normal pluteus.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>2</sub>&nbsp;and&nbsp;<i>b</i><sub>2</sub>.</td><td class="tal ti">“Half”-gastrula and “half”-pluteus, that <em>ought</em> to result from one of the first two blastomeres, when isolated, according to the theory of “evolutio.”</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>3</sub>&nbsp;and&nbsp;<i>b</i><sub>3</sub>.</td><td class="tal ti">The small <em>but whole</em> gastrula and pluteus that actually <em>do</em> result.</td></tr>
+</table>
+</div>
+
+<p>That was just the opposite of Roux’s result: one of the
+first two blastomeres had undergone a half-cleavage as in
+his case, but then it had become a whole organism by a
+simple process of rearrangement of its material, without
+anything that resembled regeneration, in the sense of a
+completion by budding from a wound.</p>
+
+<p>If one blastomere of the two-cell stage was thus capable
+of performing the morphogenetical process in its totality,
+it became, of course, <em>impossible</em> to allow that nuclear
+division had separated any sort of “germ-plasm” into two
+different halves, and not even the protoplasm of the egg
+could be said to have been divided by the first cleavage
+furrow into unequal parts, as the postulate of the strict
+theory of so-called “evolutio” had been. This was a very
+important result, sufficient alone to overthrow at once the
+theory of ontogenetical “evolutio,” the “Mosaiktheorie” as
+it had been called&mdash;not by Roux himself, but according to
+his views&mdash;in its exclusiveness.</p>
+
+<p><span class="pagenum" title="62"><a name="Page_62" id="Page_62"></a></span></p>
+
+<p>After first widening the circle of my observations by
+showing that one of the first four blastomeres is capable
+of performing a whole organogenesis, and that three of
+the first four blastomeres together result in an absolutely
+perfect organism, I went on to follow up separately one of
+the two fundamental problems which had been suggested
+by my first experiment: was there anything more to find
+out about the importance or unimportance of the single
+<em>nuclear</em> divisions in <span class="nowrap">morphogenesis?<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">16</a></span></p>
+
+<p>By raising the temperature of the medium or by diluting
+the sea-water to a certain degree it proved at first to be
+possible to alter in a rather fundamental way the type of<span class="pagenum" title="63"><a name="Page_63" id="Page_63"></a></span>
+the cleavage-stages without any damage to the resulting
+organism. There may be no micromeres at the sixteen-cell
+stage, or they may appear as early as in the stage of eight
+cells; no matter, the larva is bound to be typical. So it
+certainly is not necessary for all the cleavages to occur
+just in their normal order.</p>
+
+<p>But of greater importance for our purposes was what
+followed. I succeeded in pressing the eggs of Echinus
+between two glass plates, rather tightly, but without killing
+them; the eggs became deformed to comparatively flat
+plates of a large diameter. Now in these eggs all nuclear
+division occurred at right angles to the direction of pressure,
+that is to say, in the direction of the plates, as long as
+the pressure lasted; but the divisions began to occur at
+right angles to their former direction, as soon as the
+pressure ceased. By letting the pressure be at work for
+different times I therefore, of course, had it quite in my
+power to obtain cleavage types just as I wanted to get
+them. If, for instance, I kept the eggs under pressure
+until the eight-cell stage was complete, I got a plate of eight
+cells one beside the other, instead of two rings, of four
+cells each, one above the other, as in the normal case; but
+the next cell division occurred at right angles to the former
+ones, and a sixteen-cell stage, of two plates of eight cells
+each, one above the other, was the result. If the pressure
+continued until the sixteen-cell stage was reached, sixteen
+cells lay together in one plate, and two plates of sixteen
+cells each, one above the other, were the result of the next
+cleavage.</p>
+
+<p>We are not, however, studying these things for
+cytological, but for morphogenetical purposes, and for these<span class="pagenum" title="64"><a name="Page_64" id="Page_64"></a></span>
+the cleavage phenomenon itself is less important than the
+organogenetic result of it: all our subjects resulted in
+<em>absolutely normal</em> organisms. Now, it is clear, that the
+spatial relations of the different nuclear divisions to each
+other are anything but normal, in the eggs subjected to the
+pressure experiments; that, so to say, every nucleus has got
+quite different neighbours if compared with the “normal”
+case. If that makes no difference, then there <em>cannot</em>
+exist any close relation between the single nuclear divisions
+and organogenesis at all, and the conclusion we have drawn
+more provisionally from the whole development of isolated
+blastomeres has been extended and proved in the most
+perfect manner. There ought to result a morphogenetic
+chaos according to the theory of real “evolutio” carried
+out by nuclear division, if the positions of the single nuclei
+were fundamentally changed with regard to one another<span class="pagenum" title="65"><a name="Page_65" id="Page_65"></a></span>
+(Fig. 6). But now there resulted not chaos, but the normal
+organisation: therefore it was disproved in the strictest way
+that nuclear divisions have any bearing on the origin
+of organisation; at least as far as the divisions during
+cleavage come into account.</p>
+
+<div class="figcenter" style="width: 444px;">
+<img src="images/fig06.jpg" width="444" height="250" alt="" />
+<p><span class="smcap">Fig. 6.&mdash;Pressure-experiments on Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sub>1</sub>&nbsp;and&nbsp;<i>b</i><sub>1</sub>.</td><td class="tal ti">Two normal cleavage stages, consisting of eight and sixteen cells.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>2</sub>&nbsp;and&nbsp;<i>b</i><sub>2</sub>.</td><td class="tal ti">Corresponding stages modified by exerting pressure until the eight-cell stage was finished. See text.</td></tr>
+</table>
+</div>
+
+<p>On the egg of the frog (O. Hertwig), and on the egg of
+annelids (E. B. Wilson), my pressure experiments have been
+carried out with the same <span class="nowrap">result.<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">17</a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON THE INTIMATE STRUCTURE OF THE PROTOPLASM OF THE
+GERM</span></p>
+
+<p>Nuclear division, as we have seen, cannot be the basis
+of organogenesis, and all we know about the whole development
+of isolated blastomeres seems to show that there
+exists nothing responsible for differentiation in the protoplasm
+either.</p>
+
+<p>But would that be possible? It cannot appear possible
+on a more profound consideration of the nature of morphogenesis,
+it seems to me: as the untypical agents of the
+medium cannot be responsible in any way for the origin
+of a form combination which is most typical and specific,
+there must be somewhere in the egg itself a certain factor
+which is responsible at least for the general orientation
+and symmetry of it. Considerations of this kind led me,
+as early as <span class="nowrap">1893,<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">18</a></span> to urge the hypothesis that there<span class="pagenum" title="66"><a name="Page_66" id="Page_66"></a></span>
+existed, that there <em>must</em> exist, a sort of intimate structure
+in the egg, including polarity and bilaterality as the chief
+features of its symmetry, a structure which belongs to
+every smallest element of the egg, and which might be
+imagined by analogy under the form of elementary <span class="nowrap">magnets.<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">19</a></span>
+This hypothetic structure could have its seat in the protoplasm
+only. In the egg of echinoderms it would be capable
+of such a quick rearrangement after being disturbed, that
+it could not be observed but only inferred logically; there
+might, however, be cases in which its real discovery would
+be possible. Indeed Roux’s frog-experiment seems to be
+a case where it is found to be at work: at least it seems
+very probable to assume that Roux obtained half of a
+frog’s embryo because the protoplasm of the isolated blastomere
+had preserved the “halfness” of its intimate structure,
+and had not been able to form a small whole out of it.</p>
+
+<p>Of course it was my principal object to verify this
+hypothesis, and such verification became possible in a set
+of experiments which my friend T. H. Morgan and myself
+carried out <span class="nowrap">together,<a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">20</a></span> in 1895, on the eggs of ctenophores,
+a sort of pelagic animals, somewhat resembling the jelly-fish,
+but of a rather different inner organisation. The
+zoologist Chun had found even before Roux’s analytical
+studies, that isolated blastomeres of the ctenophore egg
+behave like parts of the whole and result in a half-organisation
+like the frog’s germ does. Chun had not laid much
+stress on his discovery, which now, of course, from the new
+points of view, became a very important one. We first
+repeated Chun’s experiment and obtained his results, with<span class="pagenum" title="67"><a name="Page_67" id="Page_67"></a></span>
+the sole exception that there was a tendency of the
+endoderm of the half-larva of Beroë to become more than
+“half.” But that was not what we chiefly wanted to
+study. We succeeded in cutting away a certain mass of
+the protoplasm of the ctenophore egg just before it began to
+cleave, without damaging its nuclear material in any way:
+in all cases, where the cut was performed at the side, there
+resulted a certain type of larvae from our experiments which
+showed exactly the same sort of defects as were present in
+larvae developed from one of the first two blastomeres
+alone.</p>
+
+<p>The hypothesis of the morphogenetic importance of
+<em>protoplasm</em> had thus been proved. In our experiments
+there was all of the nuclear material, but there were
+defects on one side of the protoplasm of the egg; and the
+defects in the adult were found to correspond to these
+defects in the protoplasm.</p>
+
+<p>And now O. Schultze and Morgan succeeded in performing
+some experiments which directly proved the
+hypothesis of the part played by protoplasm in the subject
+employed by Roux, <i>viz.</i>, the frog’s egg. The first of these
+investigators managed to rear two whole frog embryos of
+small size, if he slightly pressed the two-cell stage of that
+form between two plates of glass and turned it over; and
+<span class="nowrap">Morgan,<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">21</a></span> after having killed one of the first two blastomeres,
+as was done in the original experiment of Roux, was able
+to bring the surviving one to a half or to a whole development
+according as it was undisturbed or turned. There
+cannot be any doubt that in both of these cases, it is the
+possibility of a rearrangement of protoplasm, offered by<span class="pagenum" title="68"><a name="Page_68" id="Page_68"></a></span>
+the turning over, which allows the isolated blastomere to
+develop as a whole. The regulation of the frog’s egg, with
+regard to its becoming whole, may be called facultative,
+whilst the same regulation of the egg of Echinus is
+obligatory. It is not without interest to note that the
+first two blastomeres of the common newt, <i>i.e.</i> of a form
+which belongs to the other class of Amphibia, after a
+separation of <em>any</em> kind, <em>always</em> develop as wholes, their
+faculty of regulation being obligatory, like that of Echinus.</p>
+
+<p>Whole or partial development may thus be dependent
+on the power of regulation contained in the intimate polar-bilateral
+structure of the protoplasm. Where this is so,
+the regulation and the differences in development are both
+connected with the chief relations of symmetry. The
+development becomes a half or a quarter of the normal
+because there is only one-half or one-quarter of a certain
+structure present, one-half or one-quarter with regard
+to the very wholeness of this structure; the development
+is whole, in spite of disturbances, if the intimate
+structure became whole first. We may describe the
+“wholeness,” “halfness,” or “quarterness” of our hypothetic
+structure in a mathematical way, by using three axes, at
+right angles to one another, as the base of orientation. To
+each of these, <i>x</i>, <i>y</i>, and <i>z</i>, a certain specific state with
+regard to the symmetrical relations corresponds; thence
+it follows that, if there are wanting all those parts of the
+intimate structure which are determined, say, by a negative
+value of <i>y</i>, by minus <i>y</i>, then there is wanting half of the intimate
+structure; and this halfness of the intimate structure
+is followed by the halfness of organogenesis, the dependence
+of the latter on the intimate structure being established.<span class="pagenum" title="69"><a name="Page_69" id="Page_69"></a></span>
+But if regulation has restored, on a smaller scale, the whole
+of the arrangement according to all values of <i>x</i>, <i>y</i> and <i>z</i>,
+development also can take place completely (Fig. 7).</p>
+
+<div class="figcenter" style="width: 368px;">
+<img src="images/fig07.jpg" width="368" height="383" alt="" />
+<p><span class="smcap">Fig. 7.&mdash;Diagram illustrating the intimate Regulation of Protoplasm from
+“Half” to “Whole.”</span></p>
+
+<p>The large circle represents the original structure of the egg. In all cases where cleavage-cells
+of the two-cell stage are isolated this original structure is only present as
+“half” in the beginning, say only on the right (+<i>y</i>) side. Development then
+becomes “half,” if the intimate structure remains half; but it becomes “whole”
+(on a smaller scale) if a new whole-structure (small circle!) is formed by regulatory
+processes.</p>
+</div>
+
+<p>I am quite aware that such a discussion is rather empty
+and purely formal, nevertheless it is by no means without
+value, for it shows most clearly the differences between what
+we have called the intimate structure of germs, responsible<span class="pagenum" title="70"><a name="Page_70" id="Page_70"></a></span>
+only for the general symmetry of themselves and of their
+isolated parts, and another sort of possible structure of
+the egg-protoplasm which we now shall have to consider,
+and which, at the first glance, seems to form a serious
+difficulty to our statements, as far at least as they claim
+to be of general importance. The study of this other sort
+of germinal structure at the same time will lead us a
+step farther in our historical sketch of the first years of
+“Entwickelungsmechanik” and will bring this sketch to
+its end.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON SOME SPECIFICITIES OF ORGANISATION IN CERTAIN GERMS</span></p>
+
+<p>It was known already about 1890, from the careful
+study of what has been called “cell-lineage,” that in the
+eggs of several families of the animal kingdom the origin
+of certain organs may be traced back to individual cells of
+cleavage, having a typical histological character of their own.
+In America especially such researches have been carried
+out with the utmost minuteness, E. B. Wilson’s study of
+the cell-lineage of the Annelid <i class="biological-name">Nereis</i> being the first of
+them. If it were true that nuclear division is of no
+determining influence upon the ontogenetic fate of the
+blastomeres, only peculiarities of the different parts of
+the protoplasm could account for such relations of special
+cleavage cells to special organs. I advocated this view
+as early as in 1894, and it was proved two years later by
+Crampton, a pupil of Wilson’s, in some very fine experiments
+performed on the germ of a certain <span class="nowrap">mollusc.<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">22</a></span> The
+egg of this form contains a special sort of protoplasm near<span class="pagenum" title="71"><a name="Page_71" id="Page_71"></a></span>
+its vegetative pole, and this part of it is separated at each
+of the first two segmentations by a sort of pseudo-cleavage,
+leading to stages of three and five separated masses instead
+of two and four, the supernumerary mass being the so-called
+“yolk-sac” and possessing no nuclear elements
+(Fig. 8). Crampton removed this yolk-sac at the two-cell
+stage, and he found that the cleavage of the germs thus
+operated upon was normal except with regard to the size
+and histological appearance of one cell, and that the larvae
+originating from these germs were complete in every respect
+except in their mesenchyme, which was wanting. A special
+part of the protoplasm of the egg had thus been brought
+into relation with quite a special part of organisation, <em>and
+that special part of the protoplasm contained no nucleus</em>.</p>
+
+<div class="figcenter" style="width: 376px;">
+<img src="images/fig08.jpg" width="376" height="185" alt="" />
+<p><span class="smcap">Fig. 8.&mdash;The Mollusc Dentalium</span> (<em>after</em> E. B. Wilson).</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">The egg, consisting of three different kinds of protoplasmatic material.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">First cleavage-stage. There are two cells and one “pseudo-cell,” the yolk-sac, which contains no nucleus. This was removed in Crampton’s experiment.</td></tr>
+</table>
+</div>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">GENERAL RESULTS OF THE FIRST PERIOD OF
+“ENTWICKELUNGSMECHANIK”</span></p>
+
+<p>This experiment of Crampton’s, afterwards confirmed by
+Wilson himself, may be said to have closed the first period<span class="pagenum" title="72"><a name="Page_72" id="Page_72"></a></span>
+of the new science of physiology of form, a period devoted
+almost exclusively to the problem whether the theory of
+nuclear division or, in a wider sense, whether the theory of
+a strict “evolutio” as the basis of organogenesis was true
+or not.</p>
+
+<p>It was shown, as we have seen, that the theory of the
+“qualitatively unequal nuclear division” (“qualitativ-ungleiche
+Kernteilung” in German) certainly was not true,
+and that there also was no strict “evolutio” in protoplasm.
+Hence Weismann’s theory was clearly disproved. There
+certainly is a good deal of real “epigenesis” in ontogeny,
+a good deal of “production of manifoldness,” not only with
+regard to visibility but in a more profound meaning. But
+some sort of pre-formation had also been proved to exist,
+and this pre-formation, or, if you like, this restricted
+evolution, was found to be of two different kinds. First
+an intimate organisation of the protoplasm, spoken of as
+its polarity and bilaterality, was discovered, and this had
+to be postulated for every kind of germs, even when it
+was overshadowed by immediate obligatory regulation after
+disturbances. Besides that there were cases in which a
+real specificity of special parts of the germ existed, a relation
+of these special parts to special organs: but this sort of
+specification also was shown to belong to the protoplasm.</p>
+
+<p>It follows from all we have mentioned about the
+organisation of protoplasm and its bearing on morphogenesis,
+that the eggs of different animals may behave rather
+differently, in this respect, and that the eggs indeed may
+be classified according to the degree of their organisation.
+Though we must leave a detailed discussion of these topics
+to morphology proper, we yet shall try shortly to summarise<span class="pagenum" title="73"><a name="Page_73" id="Page_73"></a></span>
+what has been ascertained about them in the different
+classes of the animal kingdom. A full regulation of the
+<em>intimate</em> structure of isolated blastomeres to a new whole,
+has been proved to exist in the highest degree in the
+eggs of all echinoderms, medusae, nemertines, Amphioxus,
+fishes, and in one class of the Amphibia (the <i class="biological-name">Urodela</i>); it
+is facultative only among the other class of Amphibia, the
+<i class="biological-name">Anura</i>, and seems to be only partly developed or to be
+wanting altogether among ctenophora, ascidia, annelids,
+and mollusca. Peculiarities in the organisation of <em>specific
+parts</em> of protoplasm have been proved to occur in more cases
+than at first had been assumed; they exist even in the
+echinoderm egg, as experiments of the last few years have
+shown; even here a sort of specification exists at the
+vegetative pole of the egg, though it is liable to a certain
+kind of regulation; the same is true in medusae,
+nemertines, etc.; but among molluscs, ascidians, and
+annelids no regulation about the specific organisation of
+the germ in cleavage has been found in any case.</p>
+
+<p>The differences in the degree of regulability of the
+intimate germinal structure may easily be reduced to
+simple differences in the physical consistency of their
+<span class="nowrap">protoplasm.<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">23</a></span> But all differences in specific organisation
+must remain as they are for the present; it will be one
+of the aims of the future theory of development to trace
+these differences also to a common source.</p>
+
+<p>That such an endeavour will probably be not without
+success, is clear, I should think, from the mere fact that<span class="pagenum" title="74"><a name="Page_74" id="Page_74"></a></span>
+differences with regard to germinal specific pre-formation
+do not agree in any way with the systematic position of
+the animals exhibiting them; for, strange as it would be
+if there were two utterly different kinds of morphogenesis,
+it would be still more strange if there were differences
+in morphogenesis which were totally unconnected with
+systematic relationship: the ctenophores behaving differently
+from the medusae, and Amphioxus differently from ascidians.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">SOME NEW RESULTS CONCERNING RESTITUTIONS</span></p>
+
+<p>We now might close this chapter, which has chiefly
+dealt with the disproof of a certain sort of ontogenetic
+theories, and therefore has been almost negative in its
+character, did it not seem desirable to add at least a few
+words about the later discoveries relating to morphogenetic
+restorations of the adult. We have learnt that Weismann
+created his concept of “reserve plasma” to account for
+what little he knew about “restitutions”: that is, about the
+restoration of lost parts: he only knew regeneration proper
+in animals and the formation of adventitious buds in plants.
+It is common to both of these phenomena that they take
+their origin from typically localised points of the body in
+every case; each time they occur a certain well-defined
+part of the body is charged with the restoration of the lost
+parts. To explain such cases Weismann’s hypothesis was
+quite adequate, at least in a logical sense. But at present,
+as we shall discuss more fully in another chapter, we know
+of some very widespread forms of restitution, in which
+what is to be done for a replacement of the lost is not
+entrusted to <em>one</em> typical part of the body in every case,<span class="pagenum" title="75"><a name="Page_75" id="Page_75"></a></span>
+but in which the whole of the morphogenetic action to be
+performed is transferred in its <em>single</em> parts to the <em>single</em>
+parts of the body which is accomplishing restoration: each
+of its parts has to take an individual share in the process
+of restoration, effecting what is properly called a certain
+kind of “re-differentiation” (“Umdifferenzierung”), and this
+share varies according to the relative position of the part
+in each case. Later on these statements will appear in
+more correct form than at present, and then it will become
+clear that we are fully entitled to emphasise at the end of
+our criticism of Weismann’s theory, that his hypothesis
+relating to restorations can be no more true than his theory
+of development proper was found to be.</p>
+
+<p>And now we shall pass on to our positive work.</p>
+
+<p>We shall try to sketch the outlines of what might
+properly be called an <em>analytical theory of morphogenesis</em>;
+that is, to explain the sum of our knowledge about organic
+form-production, gained by experiment and by logical
+analysis, in the form of a real system, in which each part
+will be, or at least will try to be, in its proper place and
+in relation with every other part. Our analytical work
+will give us ample opportunity of mentioning many important
+topics of so-called general physiology also, irrespective
+of morphogenesis as such. But morphogenesis is always to
+be the centre and starting-point of our analysis. As I
+myself approach the subject as a zoologist, animal morphogenesis,
+as before, will be the principal subject of what is to
+follow.</p>
+
+<p><span class="pagenum" title="76"><a name="Page_76" id="Page_76"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Analytical Theory of Morphogenesis</span><a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">24</a></h4>
+
+<h5 class="fs120 mb05em">α. <span class="lowercase smcap">THE DISTRIBUTION OF MORPHOGENETIC POTENCIES</span></h5>
+
+<p class="tac pt12b02em"><i>Prospective Value and Prospective Potency</i></p>
+
+<p>Wilhelm Roux did not fail to see that the questions of
+the locality and the time of all morphogenetic differentiations
+had to be solved first, before any problem of causality
+proper could be attacked. From this point of view he
+carried out his fundamental experiments.</p>
+
+<p>It is only in terminology that we differ from his views, if
+we prefer to call our introductory chapter an analysis of
+the distribution of morphogenetic potencies. The result
+will be of course rather different from what Roux expected
+it would be.</p>
+
+<p>Let us begin by laying down two fundamental concepts.
+Suppose we have here a definite embryo in a definite state
+of development, say a blastula, or a gastrula, or some sort of
+larva, then we are entitled to study any special element of
+any special elementary organ of this germ with respect to
+what is actually to develop out of this very element in the<span class="pagenum" title="77"><a name="Page_77" id="Page_77"></a></span>
+future actual course of this development, whether it be
+undisturbed or disturbed in any way; it is, so to say, the
+actual, <em>the real fate</em> of our element, that we take in account.
+I have proposed to call this real fate of each embryonic
+part in this very definite line of morphogenesis its <em>prospective
+value</em> (“prospective Bedeutung” in German). The
+fundamental question of the first chapter of our analytical
+theory of development may now be stated as follows: Is the
+prospective value of each part of any state of the morphogenetic
+line constant, <i>i.e.</i> is it unchangeable, can it be nothing
+but one; or is it variable, may it change according to
+different circumstances?</p>
+
+<p>We first introduce a second concept: the term <em>prospective
+potency</em> (“prospective Potenz” in German) of each embryonic
+element. The term “prospective morphogenetic potency” is
+to signify the <em>possible fate</em> of each of those elements. With
+the aid of our two artificial concepts we are now able to
+formulate our introductory question thus: Is the prospective
+potency of each embryonic part fully given by its prospective
+value in a certain definite case; is it, so to say, identical
+with it, or does the prospective potency contain more than
+the prospective value of an element in a certain case reveals?</p>
+
+<p>We know already from our historical sketch that the
+latter is true: that the actual fate of a part need not be
+identical with its possible fate, at least in many cases; that
+the potency of the first four blastomeres of the egg of the
+sea-urchin, for instance, has a far wider range than is shown
+by what each of them actually performs in even this
+ontogeny. There are more morphogenetic possibilities contained
+in each embryonic part than are actually realised in
+a special morphogenetic case.</p>
+
+<p><span class="pagenum" title="78"><a name="Page_78" id="Page_78"></a></span></p>
+
+<p>As the most important special morphogenetic case is, of
+course, the so-called “normal” one, we can also express our
+formula in terms of special reference to it: there are more
+morphogenetic possibilities in each part than the observation
+of the normal development can reveal. Thus we have at
+once justified the application of analytical experiment to
+morphogenesis, and have stated its most important results.</p>
+
+<p>As the introductory experiments about “Entwickelungsmechanik”
+have shown already that the prospective potency
+of embryonic parts, at least in certain cases, <em>can</em> exceed
+their prospective value&mdash;that, at least in certain cases, it can
+be different from it&mdash;the concept of prospective potency at
+the very beginning of our studies puts itself in the centre of
+analytical interest, leaving to the concept of prospective
+value the second place only. For that each embryonic part
+actually has a certain prospective value, a specified actual
+fate in every single case of ontogeny, is clear from itself and
+does not affirm more than the reality of morphogenetic cases
+in general; but that the prospective value of the elements
+may change, that there is a morphogenetic power in them,
+which contains more than actuality; in other words, that
+the term “prospective potency” has not only a logical but a
+factual interest: all these points amount to a statement not
+only of the most fundamental introductory results but also
+of the actual <em>problems</em> of the physiology of form.</p>
+
+<p>If at each point of the germ something else <em>can</em> be formed
+than actually is formed, why then does there happen in each
+case just what happens and nothing else? In these words
+indeed we may state the chief problem of our science, at least
+after the fundamental relation of the superiority of prospective
+potency to prospective value has been generally shown.</p>
+
+<p><span class="pagenum" title="79"><a name="Page_79" id="Page_79"></a></span></p>
+
+<p>We consequently may shortly formulate our first problem
+as the question of the distribution of the prospective
+morphogenetic potencies in the germ. Now this general
+question involves a number of particular ones. Up to what
+stage, if at all, is there an absolutely equal distribution of
+the potencies over all the elements of the germ? When
+such an equal distribution has ceased to exist at a certain
+stage, what are then the relations between the parts of
+different potency? How, on the other hand, does a newly
+arisen, more specialised sort of potency behave with regard
+to the original general potency, and what about the distribution
+of the more restricted potency?</p>
+
+<p>I know very well that all such questions will seem to
+you a little formal, and, so to say, academical at the outset.
+We shall not fail to attach to them very concrete meanings.</p>
+
+<p class="tac pt12b02em"><i>The Potencies of the Blastomeres</i></p>
+
+<p>At first we turn back to our experiments on the egg of
+the sea-urchin as a type of the germ in the very earliest
+stages. We know already that each of the first two, or each
+of the first four, or three of the first four blastomeres together
+may produce a whole organism. We may add that the
+swimming blastula, consisting of about one thousand cells,
+when cut in two quite at random, in a plane coincident with,
+or at least passing near, its polar axis, may form two fully
+developed organisms out of its <span class="nowrap">halves.<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">25</a></span> We may formulate
+this result in the words: the prospective potency of the<span class="pagenum" title="80"><a name="Page_80" id="Page_80"></a></span>
+single cells of a blastula of Echinus is the same for all of
+them; their prospective value is as far as possible from
+being constant.</p>
+
+<p>But we may say even a little more: what actually will
+happen in each of the blastula cells in any special case of
+development experimentally determined depends on the
+position of that cell in the whole, if the “whole” is put
+into relation with any fixed system of co-ordinates; or more
+shortly, “the prospective value of any blastula cell is a
+function of its position in the whole.”</p>
+
+<p>I know from former experience that this statement wants
+a few words of explanation. The word “function” is employed
+here in the most general, mathematical sense, simply
+to express that the prospective value, the actual fate of a
+cell, will change, whenever its position in the whole is
+<span class="nowrap">different.<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">26</a></span> The “whole” may be related to any three
+axes drawn through the normal undisturbed egg, on the
+hypothesis that there exists a primary polarity and
+bilaterality of the germ; the axes which determine this sort
+of symmetry may, of course, conveniently be taken as
+co-ordinates; but that is not necessary.</p>
+
+<p class="tac pt12b02em"><i>The Potencies of Elementary Organs in General</i></p>
+
+<p>Before dealing with other very young germs, I think it
+advisable to describe first an experiment which is carried
+out at a later stage of our well-known form. This experiment
+will easily lead to a few new concepts, which we
+shall want later on, and will serve, on the other hand, as a<span class="pagenum" title="81"><a name="Page_81" id="Page_81"></a></span>
+basis of explanation for some results, obtained from the
+youngest germs of some other animal species, which otherwise
+would seem to be rather irreconcilable with what our
+Echinus teaches us.</p>
+
+<p>You know, from the second lecture, what a gastrula of
+our sea-urchin is. If you bisect this gastrula, when it is
+completely formed, or still better, if you bisect the gastrula
+of the starfish, either along the axis or at right angles
+to it, you get complete little organisms developed from the
+parts: the ectoderm is formed in the typical manner in the
+parts, and so is the endoderm; everything is proportionate
+and only smaller than in the normal case. So we have at
+once the important results, that, as in the blastula, so in the
+ectoderm and in the endoderm of our Echinus or of the
+starfish, the prospective potencies are the same for every
+single element: both in the ectoderm and in the endoderm the
+prospective value of each cell is a “function of its position”
+(Fig. 9).</p>
+
+<div class="figcenter" style="width: 340px;">
+<img src="images/fig09.jpg" width="340" height="583" alt="" />
+<p><span class="smcap">Fig. 9.&mdash;The Starfish</span>, <i class="biological-name">Asterias</i>.</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sup>1</sup>.</td><td class="tal ti pt02em">Normal gastrula; may be bisected along the main axis or at right angles to it (see dotted lines).</td></tr>
+<tr><td class="tar vat"><i>a</i><sup>2</sup>.</td><td class="tal ti pt02em">Normal larva, “<i class="biological-name">Bipinnaria</i>.”</td></tr>
+<tr><td class="tar vat"><i>b</i><sup>1</sup>.</td><td class="tal ti pt02em">Small but whole gastrula that results by a process of regulation from the parts of a bisected gastrula.</td></tr>
+<tr><td class="tar vat"><i>b</i><sup>2</sup>.</td><td class="tal ti">Small <em>but whole</em> “<i class="biological-name">Bipinnaria</i>,” developed out of <i>b</i><sup>1</sup>.</td></tr>
+</table>
+</div>
+
+<p>But a further experiment has been made on our gastrula.
+If at the moment when the material of the future intestine
+is most distinctly marked in the blastoderm, but not yet
+grown into a tube, if at this moment the upper half of the
+larva is separated from the lower by an equatorial section,
+you will get a complete larva only from that part which
+bears the “Anlage” of the endoderm, while the other half
+will proceed in morphogenesis very well but will form only
+ectodermal organs. By another sort of experiment, which
+we cannot fully explain here, it has been shown that the
+endoderm if isolated is also only able to form such organs
+as are normally derived from it.</p>
+
+<p>And so we may summarise both our last results by<span class="pagenum hide" title="82"><a name="Page_82" id="Page_82"></a></span><br /><span class="pagenum" title="83"><a name="Page_83" id="Page_83"></a></span>
+saying: though ectoderm and endoderm have their potencies
+equally distributed amongst their respective cells, they possess
+different potencies compared one with the other. And the
+same relation is found to hold for all cases of what we call
+elementary organs: they are “equipotential,” as we may say,
+in themselves, but of different potencies compared with each
+other.</p>
+
+<p class="tac pt12b02em"><i>Explicit and Implicit Potencies: Primary and Secondary
+Potencies</i></p>
+
+<p>We shall first give to our concept of “prospective
+potency” a few words of further analytical explanation with
+the help of our newly obtained knowledge.</p>
+
+<p>It is clear from what we have stated that the prospective
+potencies of the ectoderm and of the endoderm, and we may
+add, of every elementary organ in relation to every other,
+differ between themselves and also in comparison with the
+blastoderm, from which they have originated. But the
+diversity of the endoderm with respect to the ectoderm is
+not of the same kind as its diversity in respect to the
+blastoderm. The potency of the endoderm and that of
+the ectoderm are both specialised in their typical manner,
+but compared with the potency of the blastoderm they
+may be said not only to be specialised but also to be <em>restricted</em>:
+the potency of the blastoderm embraces the whole,
+that of the so-called germ-layer embraces only part of the
+whole; and this species of restriction becomes clearer and
+clearer the further ontogeny advances: at the end of it in
+the “ultimate elementary organs” there is no prospective
+potency whatever.</p>
+
+<p><span class="pagenum" title="84"><a name="Page_84" id="Page_84"></a></span></p>
+
+<p>A few new terms will serve to state a little more
+accurately what happens. Of course, with regard to all
+morphogenesis which goes on <em>immediately</em> from the blastoderm,
+the potency of the blastoderm is restricted as much
+as are the potencies of the germ layers. We shall call this
+sort of immediate potency <em>explicit</em>, and then we see at once
+that, with regard to their explicit potencies, there are only
+differences among the prospective potencies of the elementary
+organs; but with respect to the <em>implicit</em> potency of any of
+these organs, that is with respect to their potency as embracing
+the faculties of all their derivations, there are also
+not only differences but true morphogenetic restrictions
+lying at the very foundations of all embryology.</p>
+
+<p>But now those of you who are familiar with morphogenetic
+facts will object to me, that what we have stated
+about all sorts of restrictions in ontogeny is not true, and
+you will censure me for having overlooked regeneration,
+adventitious budding, and so on. To some extent the
+criticism would be right, but I am not going to recant;
+I shall only introduce another new concept. We are
+dealing only with <em>primary</em> potencies in our present considerations,
+<i>i.e.</i> with potencies which lie at the root of true
+embryology, not with those serving to regulate disturbances
+of the organisation. It is true, we have in some way
+disturbed the development of our sea-urchin’s egg in
+order to study it; more than that, it would have been
+impossible to study it at all without some sort of disturbance,
+without some sort of operation. But, nevertheless,
+no potencies of what may properly be called the <em>secondary</em>
+or restitutive type have been aroused by our operations;
+nothing happened except on the usual lines of organogenesis.<span class="pagenum" title="85"><a name="Page_85" id="Page_85"></a></span>
+It is true, some sort of regulation occurred, but that is
+included among the factors of ontogeny proper.</p>
+
+<p>We shall afterwards study more fully and from a more
+general point of view this very important feature of
+“primary regulation” in its contrast to “secondary regulation”
+phenomena. At present it must be enough to say
+that in speaking of the restriction of the implicit potencies
+in form-building we refer only to potencies of the primary
+type, which contain within themselves some properties of
+a (primary) regulative character.</p>
+
+<p class="tac pt12b02em"><i>The Morphogenetic Function of Maturation in the Light of
+Recent Discoveries</i></p>
+
+<p>Turning again to more concrete matters, we shall first
+try, with the knowledge acquired of the potencies of the
+blastoderm and the so-called germ layers of Echinus, to
+understand certain rather complicated results which the
+experimental morphogenetic study of other animal forms
+has taught us. We know from our historical sketch that
+there are some very important aberrations from the type,
+to which the Echinus germ <span class="nowrap">belongs,<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">27</a></span> <i>i.e.</i> the type with
+an equal distribution of the potencies over all the blastomeres.
+We know not only that in cases where a regulation
+of the intimate structure of the protoplasm fails to occur
+a partial development of isolated cells will take place, but
+that there may even be a typical disposition of typical cells<span class="pagenum" title="86"><a name="Page_86" id="Page_86"></a></span>
+for the formation of typical organs only, without any
+regulability.</p>
+
+<p>Let us first consider the last case, of which the egg of
+mollusca is a good type: here there is no equal distribution
+of potencies whatever, the cleavage-cells of this germ are
+a sort of real “mosaic” with regard to their morphogenetic
+potentialities. Is this difference between the germ of the
+echinoderms and the molluscs to remain where it is, and
+not to be elucidated any further? Then there would be
+rather important differences among the germs of different
+animals, at least with regard to the degree of the specification
+of their cleavage cells, or if we ascribe differences
+among the blastomeres to the organisation of the fertilised
+egg ready for cleavage, there would be differences in the
+morphogenetic organisation of the egg-protoplasm: some
+eggs would be more typically specialised at the very
+beginning of morphogenesis than others.</p>
+
+<p>In the first years of the study of “Entwickelungsmechanik”
+I pointed out that it must never be forgotten
+that the egg itself is the result of organogenesis. If, therefore,
+there are real mosaic-like specifications in some eggs at
+the beginning of cleavage, or during it, there may perhaps
+have been an <em>earlier</em> stage in the individual history of the
+egg which did not show such specifications of the morphogenetic
+structure. Two American authors share the merit
+of having proved this hypothesis. Conklin showed, several
+years ago, that certain intracellular migrations and rearrangements
+of material do happen in the first stages of
+ovogenesis in certain cases, but it is to E. B. <span class="nowrap">Wilson<a name="FNanchor_28_28" id="FNanchor_28_28"></a><a href="#Footnote_28_28" class="fnanchor">28</a></span> that
+science owes a proper and definitive elucidation of the<span class="pagenum" title="87"><a name="Page_87" id="Page_87"></a></span>
+whole subject. Wilson’s researches, pursued not only by
+descriptive <span class="nowrap">methods,<a name="FNanchor_29_29" id="FNanchor_29_29"></a><a href="#Footnote_29_29" class="fnanchor">29</a></span> but also by means of analytical experiment,
+led him to the highly important discovery that
+the eggs of several forms (nemertines, molluscs), which
+after maturation show the mosaic type of specification in
+their protoplasm to a more or less high degree, fail to
+show any kind of specification in the distribution of their
+potencies before maturation has occurred. In the mollusc
+egg a certain degree of specification is shown already
+before maturation, but nothing to be compared with what
+happens afterwards; in the egg of nemertines there is no
+specification at all in the unripe egg.</p>
+
+<p>Maturation thus becomes a part of ontogeny itself; it
+is not with fertilisation that morphogenesis begins, there
+is a sort of ontogeny anterior to fertilisation.</p>
+
+<p>These words constitute a summary of Wilson’s researches.
+Taken together with the general results obtained about
+the potencies of the blastula and the gastrula of Echinus,
+they reduce what appeared to be differences of degree
+or even of kind in the specification of the egg-protoplasm
+<em>to mere differences in the time of the beginning of real
+morphogenesis</em>. What occurs in some eggs, as in those of
+Echinus, at the time of the definite formation of the germ
+layers, leading to a specification and restriction of their
+prospective potencies, may happen very much earlier in
+other eggs. But there exists in <em>every</em> sort of egg an
+<em>earliest</em> stage, in which all parts of its protoplasm are<span class="pagenum" title="88"><a name="Page_88" id="Page_88"></a></span>
+equal as to their prospectivity, and in which there are no
+potential diversities or restrictions of any kind.</p>
+
+<p>So much for differences in the <em>real material</em> organisation
+of the germ and their bearing on inequipotentialities of the
+cleavage cells.</p>
+
+<p class="tac pt12b02em"><i>The Intimate Structure of Protoplasm: Further Remarks</i></p>
+
+<p>Where a typical half- or quarter-development from
+isolated blastomeres happens to occur, we know already
+that the impossibility of a regulation of the <em>intimate polar-bilateral</em>
+structure may account for it. As this impossibility
+of regulation probably rests on rather simple physical <span class="nowrap">conditions<a name="FNanchor_30_30" id="FNanchor_30_30"></a><a href="#Footnote_30_30" class="fnanchor">30</a></span>
+it may properly be stated that equal distribution
+of potencies is not wanting but is only overshadowed here.
+In this respect there exists a logical difference of fundamental
+importance between those cases of so-called “partial”
+or better, “fragmental” development of isolated blastomeres
+in which a certain embryonic organ is wanting on account
+of its specific morphogenetic material being absent, and
+those cases in which the “fragmental” embryo lacks
+complete “halves” or “quarters” with regard to general
+symmetry on account of the symmetry of its intimate
+structure being irregularly disturbed. This logical difference
+has not always received the attention which it undoubtedly
+deserves. Our hypothetical intimate structure in itself is,
+of course, also a result of factors concerned in ovogenesis.
+Only in one case do we actually know anything about its<span class="pagenum" title="89"><a name="Page_89" id="Page_89"></a></span>
+origin: Roux has shown that in the frog it is the accidental
+path of the fertilising spermatozoon in the egg which,
+together with the polar axis, normally determines the plane
+of bilateral symmetry; but this symmetry may be overcome
+and replaced by another, if gravity is forced to act in an
+abnormal manner upon the protoplasm; the latter showing
+parts of different specific gravity in the eggs of all Amphibia.</p>
+
+<p class="tac pt12b02em"><i>The Neutrality of the Concept of “Potency”</i></p>
+
+<p>Now we may close our rather long chapter on the
+distribution of potencies in the germ; it has been made
+long, because it will prove to be very important for further
+analytical discussion; and its importance, in great measure,
+is due to its freedom from prepossessions. Indeed, the
+concept of prospective potency does not prejudice anything;
+we have said, it is true, that limitations of potencies may
+be due to the presence of specific parts of organisation in
+some cases; that, at least, they may be connected therewith;
+but we have not determined at all what a prospective
+potency really is, what the term really is to signify. It
+may seem that such a state of things gives an air of
+emptiness to our discussions, that it leaves uncertain
+what is the most important. But, I think, our way of
+argument, which tries to reach the problems of greatest
+importance by degrees, though it may be slow, could hardly
+be called wrong and misleading.</p>
+
+
+<h5 class="fs120 mb05em">β. <span class="lowercase smcap">THE “MEANS” OF MORPHOGENESIS</span></h5>
+
+<p>We now proceed to an analysis of what may properly
+be called the <em>means</em> of morphogenesis, the word <span class="pagenum" title="90"><a name="Page_90" id="Page_90"></a></span>“means”
+being preferable to the more usual one “conditions” in this
+connection, as the latter would not cover the whole field.
+It is in quite an unpretentious and merely descriptive
+sense that the expression “means” should be understood at
+present; what is usually called “conditions” is part of the
+morphogenetic means in our sense.</p>
+
+<h6 class="fs110 mb05em">β′. <i>The Internal Elementary Means of Morphogenesis</i></h6>
+
+<p>We know that all morphogenesis, typical or atypical,
+primary or secondary, goes on by one morphogenetic
+elementary process following the other. Now the very
+foundation of these elementary processes themselves lies in
+the elementary functions of the organism as far as they
+result in the formation of stable visible products. Therefore
+the elementary functions of the organism may properly be
+called the internal “means” of morphogenesis.</p>
+
+<p>Secretion and migration are among such functions; the
+former happening by the aid of chemical change or by
+physical separation, the latter by the aid of changes in
+surface tension. But hardly anything more concrete has
+been made out about these or similar points at present.</p>
+
+<p>We therefore make no claim to offer a complete system
+of the internal elementary means of morphogenesis. We
+shall only select from the whole a few topics of remarkable
+morphogenetic interest, and say a few words about each.</p>
+
+<p>But, first of all, let us observe that the elementary means
+of morphogenesis are far from being morphogenesis themselves.
+The word “means” itself implies as much. It
+would be possible to understand each of these single acts in
+morphogenesis as well as anything, and yet to be as far<span class="pagenum" title="91"><a name="Page_91" id="Page_91"></a></span>
+from understanding the whole as ever. All means of
+morphogenesis are only to be considered as the most general
+frame of events within which morphogenesis occurs.</p>
+
+<p><i>Some Remarks on the Importance of Surface Tension in
+Morphogenesis.</i>&mdash;There are a few purely physical phenomena
+which have a special importance in organic morphology, all
+of them connected with capillarity or surface tension. Soap-lather
+is a very familiar thing to all of you: you know that
+the soap-solution is arranged here in very thin planes separated
+by spaces containing air: it was first proved by <span class="nowrap">Berthold<a name="FNanchor_31_31" id="FNanchor_31_31"></a><a href="#Footnote_31_31" class="fnanchor">31</a></span>
+that the arrangement of cells in organic tissues follows the
+same type as does the arrangement of the single bubbles of
+a soap-lather, and <span class="nowrap">Bütschli<a name="FNanchor_32_32" id="FNanchor_32_32"></a><a href="#Footnote_32_32" class="fnanchor">32</a></span> added to this the discovery that
+the minute structure of the protoplasm itself is that of a
+foam also. Of course it is not one fluid and one gas which
+make up the constituents of the structure in the organisms,
+as is the case in the well-known inorganic foams, but two
+fluids, which do not mix with one another. One general
+law holds for all arrangements of this kind: the so-called
+law of least surfaces, expressed by the words that the
+sum of all surfaces existing is a minimum; and it again
+is a consequence of this law, if discussed mathematically,
+that four lines will always meet in one point and three
+planes in one line. This feature, together with a certain
+law about the relation of the angles meeting in one line
+to the size of the bubbles, is realised most clearly in
+many structures of organic tissues, and makes it highly
+probable, at least in some cases, that capillarity is at work
+here. In other cases, as for instance in many plants, a<span class="pagenum" title="92"><a name="Page_92" id="Page_92"></a></span>
+kind of outside pressure, the so-called tissue tension, may
+account for the arrangement in surfaces <em>minimae areae</em>.
+Cleavage stages are perhaps the very best type in which
+our physical law is expressed: and here it may be said
+to have quite a simple application whenever all of the
+blastomeres are of the same physical kind, whilst some
+complications appear in germs with a specialised organisation
+and, therefore, with differences in the protoplasm of
+their single blastomeres. In such instances we may say
+that the physical law holds as far as the conditions of the
+system permit, these conditions ordinarily consisting in a
+sort of non-homogeneity of the surfaces.</p>
+
+<p>It seems, from the researches of <span class="nowrap">Dreyer,<a name="FNanchor_33_33" id="FNanchor_33_33"></a><a href="#Footnote_33_33" class="fnanchor">33</a></span> that the formation
+of organic skeletons may also be governed by the
+physically conditioned arrangement of protoplasmatic or
+cellular elements, and some phenomena of migration and
+rearrangement among cleavage cells, as described by Roux,
+probably also belong here.</p>
+
+<p>But let us never forget that the laws of surface tension
+only give us the most general type of an arrangement of
+elements in all these cases, nothing else. A physical law
+never accounts for the Specific! Capillarity gives us not
+the least clue to it. As the organic substance, at least in
+many cases, is a fluid, it must of course follow the general
+laws of hydrostatics and hydrodynamics, but life itself is as
+little touched by its fluid-like or foam-like properties as it
+is by the fact that living bodies have a certain weight and
+mass.</p>
+
+<p>All indeed that has been described may be said to
+belong, in the broadest meaning of the word, to what is<span class="pagenum" title="93"><a name="Page_93" id="Page_93"></a></span>
+called by Roux “correlation of masses,” though this author
+originally intended to express by this term only some sorts
+of passive pressure and deformation amongst embryonic
+parts as discovered especially by His.</p>
+
+<p>We must be cautious in admitting that any organic
+feature has been explained, even in the most general way,
+by the action of physical forces. What at first seems to be
+the result of mechanical pressure may afterwards be found
+to be an active process of growth, and what at first seems
+to be a full effect of capillarity among homogeneous elements
+may afterwards be shown to depend on specialised metabolic
+conditions of the surfaces as its principal <span class="nowrap">cause.<a name="FNanchor_34_34" id="FNanchor_34_34"></a><a href="#Footnote_34_34" class="fnanchor">34</a></span></p>
+
+<p>There are other physical phenomena too, which assist
+morphogenesis; osmotic pressure for instance, which is also
+well known to operate in many purely physiological processes.
+But all these processes are only means of the organism, and
+can never do more than furnish the general type of events.
+They do not constitute life; they are <em>used</em> by life; let it
+remain an open question, for the present, how the phenomenon
+of “life” is to be regarded in <span class="nowrap">general.<a name="FNanchor_35_35" id="FNanchor_35_35"></a><a href="#Footnote_35_35" class="fnanchor">35</a></span></p>
+
+<p><i>On Growth</i>.&mdash;Among the internal morphogenetical means
+which are of a so-called physiological character, that is,
+which nobody claims to understand physically at present,<span class="pagenum" title="94"><a name="Page_94" id="Page_94"></a></span>
+there is in the first place <em>growth</em>, which must be regarded
+as a very essential one.</p>
+
+<p>Analytically we must carefully discriminate between the
+increase in the size of the cavities of an organism by a
+passive extension of their surfaces and the proper growth of
+the individual cells, which again may be due either to mere
+extension or to real assimilation. Osmotic pressure, of
+course, plays an important part both in the growth of the
+body-cavities and in simple cellular extension. We repeat
+the caution against believing too much to be explained by
+this phenomenon: it is the organism which by the secretion
+of osmotic substances in the cavities or the protoplasm of
+the cells prepares the ground for growth even of this
+osmotic sort. The real cellular growth which proceeds on
+the basis of assimilation cannot, of course, be accounted for
+by osmotic events, not even in its most general type.</p>
+
+<p>Ontogenetical growth generally sets in, both in animals
+and in plants, after the chief lines of organisation are laid
+out; it is only the formation of the definite histological
+structures which usually runs parallel to it.</p>
+
+<p><i>On Cell-division.</i>&mdash;We have already said a good deal
+about the importance of cell-division in ontogeny: it
+accompanies very many of the processes of organisation in
+all living beings. But even then, there are the Protozoa,
+in the morphogenesis of which it does not occur at all, and
+there have also become known many cases of morphogenesis
+in higher animals, mostly of the type of regulation, in which
+cellular division is almost or wholly wanting. Therefore,
+cellular division cannot be the true reason of differentiation,
+but is only a process, which though necessary in some cases,
+cannot be essential to it. It must be conceded, I believe,<span class="pagenum" title="95"><a name="Page_95" id="Page_95"></a></span>
+that the same conclusion can be drawn from all our
+experiments on very young stages of the germ.</p>
+
+<p>The investigations of the last few years have made it
+quite clear that even in organisms with a high power of
+morphogenetic regulation it is always the form of the whole,
+but not the individual cell, which is subjected to the regulation
+processes. Starting from certain results obtained by
+T. H. Morgan, I was able to show that in all the small but
+whole larvae, reared from isolated blastomeres, the size of
+the cells remains normal, only their number being reduced;
+and Boveri has shown most clearly that it is always the
+size of the nucleus&mdash;more correctly, the mass of the
+chromatin&mdash;which determines how large a cell of a certain
+histological kind is to be. In this view, the cell appears
+even more as a sort of material used by the organism as
+supplied, just as workmen can build the most different
+buildings with stones of a given size.</p>
+
+
+<h6 class="fs110 mb05em">β″. <i>The External Means of Morphogenesis</i></h6>
+
+<p>We now know what internal means of morphogenesis are,
+and so we may glance at some of the most important
+“outer means” or “conditions” of organisation.</p>
+
+<p>Like the adult, the germ also requires a certain amount
+of heat, oxygen, and, when it grows up in the sea, salinity
+in the medium. For the germ, as for the adult, there
+exists not only a minimum but also a maximum limit
+of all the necessary factors of the medium; the same factor
+which at a certain intensity promotes development, disturbs
+it from a certain other intensity upwards.</p>
+
+<p>Within the limits of this minimum and this maximum<span class="pagenum" title="96"><a name="Page_96" id="Page_96"></a></span>
+of every outside agent there generally is an increase in
+the rate of development corresponding to the increase of
+intensity of the agent. The acceleration of development by
+heat has been shown to follow the law of the acceleration of
+chemical processes by a rise of temperature; that seems to
+prove that certain chemical processes go on during the
+course of morphogenesis.</p>
+
+<p>Almost all that has been investigated of the part played
+by the external conditions of development has little bearing
+on specific morphogenesis proper, and therefore may be left
+out of account here: we must, however, lay great stress
+on the general fact that there <em>is</em> a very close dependence
+of morphogenesis on the outside factors, lest we should be
+accused afterwards of having overlooked it.</p>
+
+<p>Of course all “external” means or conditions of morphogenesis
+can actually relate to morphogenetic processes only by
+becoming in some way “internal,” but we unfortunately have
+no knowledge whatever how this happens. We at present
+are only able to ascertain what must necessarily be
+accomplished in the medium, in order that normal morphogenesis
+may go on, and we can only suppose that there
+exist certain specific internal general states, indispensable
+for organogenesis but inaccessible to present modes of
+<span class="nowrap">investigation.<a name="FNanchor_36_36" id="FNanchor_36_36"></a><a href="#Footnote_36_36" class="fnanchor">36</a></span></p>
+
+<p><i>The Discoveries of Herbst.</i>&mdash;There are but few points
+in the doctrine of the external means or conditions of
+organogenesis which have a more special bearing on
+the specification of proper form, and which therefore<span class="pagenum" title="97"><a name="Page_97" id="Page_97"></a></span>
+require to be described here a little more fully. All these
+researches, which have been carried out almost exclusively
+by <span class="nowrap">Herbst,<a name="FNanchor_37_37" id="FNanchor_37_37"></a><a href="#Footnote_37_37" class="fnanchor">37</a></span> relate to the effect of the chemical components
+of sea-water upon the development of the sea-urchin. If
+we select the most important of Herbst’s results, we must
+in the first place say a few words on the part taken by
+lime or calcium, not only in establishing specific features of
+form, but in rendering individual morphogenesis possible at
+all. Herbst has found that in sea-water which is deprived
+of calcium the cleavage cells and many tissue cells also
+completely lose contact with each other: cleavage goes on
+quite well, but after each single division the elements are
+separated; at the end of the process you find the 808 cells
+of the germ together at the bottom of the dish, all swimming
+about like infusoria. There seems to be some
+influence of the calcium salts upon the physical state of
+the surfaces of the blastomeres.</p>
+
+<p>It is not without interest to note that this discovery
+has an important bearing on the technical side of all experiments
+dealing with the isolation of blastomeres. Since the
+separation of the single cleavage elements ceases as soon
+as the germs are brought back from the mixture without
+lime into normal sea-water, it of course is possible to
+separate them up to any stage which it is desired to study,
+and to keep them together afterwards. Thus, if for instance
+you want to study the development of isolated cells of the
+eight-cell stage, you will leave the egg in the artificial
+mixture containing no calcium until the third cleavage,
+which leads from the four- to the eight-cell stage, is finished.
+The single eight cells brought back to normal sea-water at<span class="pagenum" title="98"><a name="Page_98" id="Page_98"></a></span>
+this point will give you the eight embryos you want. All
+researches upon the development of isolated blastomeres
+since the time of Herbst’s discovery have been carried out
+by this method, and it would have been quite impossible
+by the old method of shaking to pursue the study into
+such minute detail as actually has been done. It may
+be added that calcium, besides its cell-uniting action,
+is also of primary importance in the formation of the
+skeleton.</p>
+
+<p>Among all the other very numerous studies of Herbst
+we need only mention that potassium is necessary for the
+typical growth of the intestine, just as this element has
+been found necessary for normal growth in plants, and that
+there must be the ion SO<sub>4</sub>, or in other terms, sulphur salts
+present in the water, in order that the germs may acquire
+their pigments and their bilateral symmetry. This is indeed
+a very important result, though it cannot be said to be
+properly understood. It is a fact that in water without
+sulphates the larvae of Echinus retain the radial symmetry
+they have had in the very earliest stages, and may even
+preserve that symmetry on being brought back to normal
+sea-water if they have spent about twenty-four hours in
+the artificial mixture.</p>
+
+<p>We may now leave the subject of Herbst’s attempts to
+discover the morphogenetic function of the single constituents
+of normal sea-water, and may devote a few
+words to the other branch of his investigations, those
+dealing with the morphogenetic effects of substances which
+are not present in the water of the sea, but have been added
+to it artificially. Here, among many other achievements,
+Herbst has made the most important discovery that all<span class="pagenum" title="99"><a name="Page_99" id="Page_99"></a></span>
+salts of lithium effect radical changes in <span class="nowrap">development.<a name="FNanchor_38_38" id="FNanchor_38_38"></a><a href="#Footnote_38_38" class="fnanchor">38</a></span> I
+cannot describe fully here how the so-called “lithium
+larva” originates; let me only mention that its endoderm
+is formed outside instead of inside, that it is far
+too large, that there is a spherical mass between the
+ectodermal and the endodermal part of the germ, that
+a radial symmetry is established in place of the normal
+bilateralism, that no skeleton exists, and that the mesenchyme
+cells are placed in a quite abnormal position. All these
+features, though abnormal, are typical of the development
+in lithium. The larvae present no really pathological
+appearance at all, and, therefore, it may indeed be said that
+lithium salts are able to change fundamentally the whole
+course of morphogenesis. It detracts nothing from the
+importance of these discoveries that, at present, they stand
+quite isolated: only with lithium salts has Herbst obtained
+such strange results, and only upon the eggs of echinids,
+not even upon those of asterids, do lithium salts act in this
+way.</p>
+
+
+<h5 class="fs120 mb05em">γ. <span class="lowercase smcap">THE FORMATIVE CAUSES OR STIMULI</span></h5>
+
+<p class="tac pt12b02em"><i>The Definition of Cause</i></p>
+
+<p>We cannot begin the study of the “causes” of the
+differentiation of form without a few words of explanation
+about the terminology which we shall apply. Causality
+is the most disputed of all categories; many modern
+scientists, particularly in physics, try to avoid the concept
+of cause altogether, and to replace it by mere functional
+dependence in the mathematical meaning of the term.<span class="pagenum" title="100"><a name="Page_100" id="Page_100"></a></span>
+They claim to express completely by an equation all that
+is discoverable about any sort of phenomena constantly
+connected.</p>
+
+<p>I cannot convince myself that such a very restricted
+view is the right one: it is very cautious, no doubt, but it
+is incomplete, for we <em>have</em> the concept of the acting “cause”
+in our Ego and are <em>forced</em> to search for applications of it
+in Nature. On the other hand, it does not at all escape
+me that there are many difficulties, or rather ambiguities,
+in applying it.</p>
+
+<p>We may call the “cause” of any event, the sum total
+of all the constellations of facts which must be completed
+in order that the event may occur; it is in this meaning,
+for instance, that the first principle of energetics applies
+the term in the words <i lang="la" xml:lang="la">causa aequat effectum</i>. But, by
+using the word only in this very general sense, we deprive
+ourselves of many conveniences in the further and more
+particular study of Nature. Would it be better to say that
+the “cause” of any event is the very last change which,
+after all the constellations necessary for its start are
+accomplished, must still take place in order that the event
+may actually occur? Let us see what would follow from
+such a use of the word causality. We here have an animal
+germ in a certain stage, say a larva of Echinus, which is just
+about to form the intestine; all the internal conditions are
+fulfilled, and there is also a certain temperature, a certain
+salinity, and so on, but there is no oxygen in the water: the
+intestine; of course, will not grow in such a state of things,
+but it soon will when oxygen is allowed to enter the dish.
+Is, therefore, oxygen the cause of the formation of the
+intestine of echinus? Nobody, I think, would care to say<span class="pagenum" title="101"><a name="Page_101" id="Page_101"></a></span>
+so. By such reasoning, indeed, the temperature, or sodium,
+might be called the “cause” of any special process of
+morphogenesis. It, therefore, seems to be of little use to
+give the name of cause to that factor of any necessary
+constellation of events which accidentally happens to be
+the last that is realised. But what is to be done then?</p>
+
+<p>Might we not say that the cause of any morphogenetic
+process is that typical property, or quality, or change, on
+which its specific character depends, on which depends for
+example, the fact that now it is the intestine which appears,
+while at another time it is the lens of the eye? We might
+very well, but we already have our term for this sort of
+cause, which is nothing else than our prospective potency
+applied to that elementary organ from which the new
+process takes its origin. The prospective potency indeed
+is the truly immanent cause of every specification affecting
+single organogenetic processes. But we want something
+more than this.</p>
+
+<p>We may find what we want by considering that each
+single elementary process or development not only has its
+specification, but also has its specific and typical place in
+the whole&mdash;its locality. Therefore we shall call the “cause”
+of a single morphogenetic process, that occurrence on which
+depends its <em>localisation</em>, whether its specific character also
+partly depends on this “cause” or <span class="nowrap">not.<a name="FNanchor_39_39" id="FNanchor_39_39"></a><a href="#Footnote_39_39" class="fnanchor">39</a></span></p>
+
+<p>This definition of “cause” in morphology may be
+artificial; in any case it is clear. And at the same time
+the concepts of the prospective potency and of the “means”
+of organogenesis now acquire a clear and definite meaning:<span class="pagenum" title="102"><a name="Page_102" id="Page_102"></a></span>
+potency is the real basis of the specific character of every
+act in morphogenesis, and “means,” including conditions, are
+the sum of all external and internal general circumstances
+which must be present in order that morphogenetic processes
+may go on, without being responsible for their specificity
+or localisation.</p>
+
+<p>It is implied in these definitions of cause and potency,
+that the former almost always will be of that general
+type which usually is called a stimulus or “Auslösung,”
+to use the untranslatable German word. There is no
+quantitative correspondence between our “cause” and the
+morphogenetic effect.</p>
+
+<p class="tac pt12b02em"><i>Some Instances of Formative and Directive Stimuli</i></p>
+
+<p>Again it is to Herbst that we owe not only a very
+thorough logical analysis of what he calls “formative and
+directive <span class="nowrap">stimuli”<a name="FNanchor_40_40" id="FNanchor_40_40"></a><a href="#Footnote_40_40" class="fnanchor">40</a></span> but also some important discoveries
+on this subject. We cannot do more here than barely
+mention some of the most characteristic facts.</p>
+
+<p>Amongst plants it has long been known that the
+direction of light or of gravity may determine where
+roots or branches or other morphogenetic formations are to
+arise; in hydroids also we know that these factors of the
+medium may be at <span class="nowrap">work<a name="FNanchor_41_41" id="FNanchor_41_41"></a><a href="#Footnote_41_41" class="fnanchor">41</a></span> as morphogenetic causes, though<span class="pagenum" title="103"><a name="Page_103" id="Page_103"></a></span>
+most of the typical architecture of hydroid colonies certainly
+is due to internal causes, as is also much of the organisation
+in plants.</p>
+
+<p>Light and gravity are external formative causes; beside
+that they are merely “localisers.” But there also are some
+external formative stimuli, on which depends not only
+the place of the effect, but also part of its specification.
+The galls of plants are the most typical organogenetic
+results of such stimuli. The potencies of the plant and the
+specific kind of the stimulus equally contribute to their
+specification; for several kinds of galls may originate on
+one sort of leaves.</p>
+
+<p>Scarcely any exterior formative stimuli are responsible
+for animal organisation; and one would hardly be wrong
+in saying that this morphogenetic independence in animals
+is due to their comparatively far-reaching functional independence
+of those external agents which have any sort
+of direction. But many organogenetic relations are known
+to exist between the single parts of animal germs, each
+of these parts being in some respect external to every
+other; and, indeed, it might have been expected already
+<i lang="la" xml:lang="la">a priori</i>, that such formative relations between the parts of an
+animal embryo must exist, after all we have learned about
+the chief lines of early embryology. If differentiation does
+not go on after the scheme of Weismann, that is, if it is not
+carried out by true “evolutio” from within, how could it be
+effected except from without? Indeed, every embryonic
+part may in some respect be a possible cause for morphogenetic
+events, which are to occur on every other part: it is
+here that the very roots of epigenesis are to be found.</p>
+
+<p>Heliotropism and geotropism are among the well-known<span class="pagenum" title="104"><a name="Page_104" id="Page_104"></a></span>
+physiological functions of plants: the roots are seen to bend
+away from the light and towards the ground; the branches
+behave just in the opposite way. It now has been supposed
+by Herbst that such “directive stimuli” may also be at
+work among the growing or wandering parts of the embryo,
+that their growth or their migration may be determined by
+the typical character of other parts, and that real morphogenetic
+characters can be the result of some such relation;
+a sort of “chemotropism” or “chemotaxis” may be at work
+here. Herbst himself has discussed theoretically several
+cases of organogenesis in which the action of directive
+stimuli is very probable. What has become actually
+known by experiment is not very much at present: the
+mesenchyme cells of Echinus are directed in their migration
+by specified places in the ectoderm, the pigment cells of the
+yolk-sac of the fish fundulus are attracted by its blood
+vessels, and nerves may be forced to turn into little tubes
+containing brain substance; but of course only the first two
+instances have any bearing on typical morphogenesis.</p>
+
+<p>The first case of an “internal formative stimulus” in
+the proper sense, that is, of one embryonic part causing
+another to appear, was discovered by Herbst himself. The
+arms of the so-called pluteus of the sea-urchin are in
+formative dependence on the skeleton&mdash;no skeleton, no
+arms; so many skeleton <span class="nowrap">primordia,<a name="FNanchor_42_42" id="FNanchor_42_42"></a><a href="#Footnote_42_42" class="fnanchor">42</a></span> in abnormal cases, so
+many arms; abnormal position of the skeleton, abnormal
+position of the arms: these three experimental observations
+form the proof of this morphogenetic relation.</p>
+<p><span class="pagenum" title="105"><a name="Page_105" id="Page_105"></a></span></p>
+<p>It may be simple mechanical contact, or it may be some
+chemical influence that really constitutes the “stimulus” in
+this case; certainly, there exists a close and very specific
+relation of the localisation of one part of the embryo to
+another. Things are much the same in another case,
+which, after having been hypothetically stated by Herbst
+on the basis of pathological data, was proved experimentally
+by Spemann. The lens of the eye of certain Amphibia is
+formed of their skin in response to a formative stimulus
+proceeding from the so-called primary optic vesicle. If this
+vesicle fails to touch the skin, no lens appears; and, on the
+other hand, the lens may appear in quite abnormal parts of
+the skin if they come into contact with the optic vesicle
+after transplantation.</p>
+
+<p>But formative dependence of parts may also be of
+different types.</p>
+
+<p>We owe to Herbst the important discovery that the
+eyes of crayfishes, after being cut off, will be regenerated in
+the proper way, if the optic ganglion is present, but that
+an antenna will arise in their place if this ganglion has
+also been removed. There must in this case be some
+unknown influence of the formative kind on which
+depends, if not regeneration itself, at least its special
+character.</p>
+
+<p>In other cases there seems to be an influence of the
+central nervous system on the regenerative power in general.
+Amphibia, for instance, are said to regenerate neither their
+legs (Wolff), nor their tail (Godlewski), if the nervous communications
+have been disturbed. But in other animals
+there is no such influence; and in yet others, as for instance,
+in Planarians, it must seem doubtful at present whether the<span class="pagenum" title="106"><a name="Page_106" id="Page_106"></a></span>
+morphogenetic influence of the nervous system upon processes
+of restoration is more than indirect; the movements of the
+animal, which become very much reduced by the extirpation
+of the ganglia, being one of the main conditions of a good
+regeneration.</p>
+
+<p>Of course, all we have said about the importance of
+special materials in the ripe germ, as bearing on specifically
+localised organisations, might be discussed again in our
+present chapter, and our intimate polar-bilateral structure
+of germs may also be regarded as embracing formative
+stimuli, at any rate as far as the actual poles of this
+structure are concerned. This again would bring us to the
+problem of so-called “polarity” in general, and to the
+“inversion” of polarity, that is to a phenomenon well
+known in plants and in many hydroids and worms, viz.,
+that morphogenetic processes, especially of the type of
+restitutions, occur differently, according as their point of
+origin represents, so to speak, the positive or the negative,
+the terminal or the basal end of an axis, but that under
+certain conditions the reverse may also be the case. But a
+fuller discussion of these important facts would lead us
+deeper and deeper into the science of morphogenesis proper,
+without being of much use for our future considerations.</p>
+
+<p>And so we may close this <span class="nowrap">section<a name="FNanchor_43_43" id="FNanchor_43_43"></a><a href="#Footnote_43_43" class="fnanchor">43</a></span> on formative stimuli<span class="pagenum" title="107"><a name="Page_107" id="Page_107"></a></span>
+or “causes” of morphogenesis by shortly adding, more on
+account of its factual than of its logical interest, that the
+phenomenon of the determination of <span class="nowrap">sex,<a name="FNanchor_44_44" id="FNanchor_44_44"></a><a href="#Footnote_44_44" class="fnanchor">44</a></span> according to the
+latest researches, seems to depend on cytological events
+occurring in the very earliest embryonic stages, say even
+before ontogeny, and not on formative stimuli <span class="nowrap">proper<a name="FNanchor_45_45" id="FNanchor_45_45"></a><a href="#Footnote_45_45" class="fnanchor">45</a></span>: it
+seems, indeed, as if the sexual products themselves would
+account for the sex of the individual produced by them,
+particularly if there were differences in their <span class="nowrap">chromatin.<a name="FNanchor_46_46" id="FNanchor_46_46"></a><a href="#Footnote_46_46" class="fnanchor">46</a></span></p>
+
+
+<h5 class="fs120 mb05em">δ. <span class="lowercase smcap">THE MORPHOGENETIC HARMONIES</span></h5>
+
+<p>Let us now turn again to considerations of a more
+abstract kind: we have become acquainted with some
+morphogenetic interactions among the parts of a developing
+embryo; and, indeed, we can be sure that there exist far
+more of such interactions than we know at present.</p>
+
+<p>But it is far from being true that the development of
+each embryonic part depends on the existence or development
+of every other one.</p>
+
+<p>On the contrary, it is a very important and fundamental
+feature of organogenesis that it occurs in separate lines,<span class="pagenum" title="108"><a name="Page_108" id="Page_108"></a></span>
+that is to say, in lines of processes which may start from a
+common root, but which are absolutely independent of
+one another in their manner of differentiation. Roux has
+coined the term “self-differentiation” to denote this phenomenon,
+and we admit that this term may be conveniently
+used for the purpose, if only it can be kept in mind that
+its sense is always relative, and that it is also negative.
+Suppose a part, <i>A</i>, shows the phenomenon of self-differentiation:
+this means that the further development of <i>A</i>
+is not dependent on certain other parts, <i>B</i>, <i>C</i>, and <i>D</i>; it does
+<em>not</em> mean at all that <i>A</i> has not been formatively dependent
+on some other parts, <i>E</i> or <i>F</i> at the time of its first appearance,
+nor does it imply that there might not be many
+formative actions among the constituents of <i>A</i> itself.</p>
+
+<p>We indeed are entitled to say that the ectoderm of
+Echinus shows “self-differentiation” with regard to the
+endoderm; it acquires its mouth, for instance, as has been
+shown by experiment, even in cases where no intestine is
+present at all (Fig. 10); but ectoderm and endoderm both
+are formatively dependent on the intimate and the material
+organisation of the blastoderm. It further seems from the
+most recent experiments that the nerves and the muscles of
+the vertebrates are independent of each other in their
+differentiation, but that their fate is probably determined
+by formative processes in the very earliest stages of ontogeny.</p>
+
+<div class="figcenter" style="width: 225px;">
+<img src="images/fig10.jpg" width="225" height="208" alt="" /></div>
+<div class="figcenter" style="width: 250px;">
+<p><span class="smcap">Fig. 10.&mdash;Pluteus-larva of Sphaerechinus.</span></p>
+<p>The Intestine (i) is developed outside instead of inside (by means of raising the temperature);
+but the mouth (r) is formed in its normal place. S = Skeleton.</p>
+</div>
+
+<p>The phenomenon of self-differentiation, properly understood,
+now may help to the discovery of one most general
+character of all development. If the phenomenon of self-differentiation
+really occurs in ontogeny in its most different
+aspects, and if, on the other hand, in spite of this relative
+morphogenetic independence of embryonic parts, the result<span class="pagenum" title="109"><a name="Page_109" id="Page_109"></a></span>ing
+organism is one whole in organisation and in function,
+some sort of <em>harmony of constellation</em>, as it may properly be
+styled, must be said to be one of the most fundamental
+characters of all production of individual form. In establishing
+this harmony we do nothing more than describe exactly
+what happens: the harmony is shown by the fact that
+there is a whole organism at the end, in spite of the relative
+independence of the single events leading to it.</p>
+
+<p>But still another sort of harmony is revealed in morphogenesis,
+by an analysis of the general conditions of the
+formative actions themselves. In order that these actions
+may go on properly the possibility must be guaranteed that
+the formative causes may always find something upon which
+to act, and that those parts which contain the potencies for
+the next ontogenetic stage may properly receive the stimuli
+awaking these potencies: otherwise there would be no
+typical production of form at all. This, the second species
+of harmonious relations to be described in ontogeny, may
+be called <em>causal harmony</em>; the term simply expresses the<span class="pagenum" title="110"><a name="Page_110" id="Page_110"></a></span>
+unfailing relative condition of formative causes and cause-recipients.</p>
+
+<p>Finally, in <em>functional harmony</em> we have an expression
+descriptive of the unity of organic function, and so we
+may state, as the latest result of our analytical theory of
+development up to this point, that individual morphogenesis
+is marked by a <em>threefold harmony</em> among its parts.</p>
+
+
+<h5 class="fs120 mb05em">ε. <span class="lowercase smcap">ON RESTITUTIONS</span><a name="FNanchor_47_47" id="FNanchor_47_47"></a><a href="#Footnote_47_47" class="fnanchor">47</a></h5>
+
+<p>At this stage we leave for a while our analytical
+studies of ontogeny proper. We must not forget that
+typical ontogenesis is not the only form in which morphogenesis
+can occur: the organic form is able to restore
+disturbances of its organisation, and it certainly is to be
+regarded as one of the chief problems of analytical morphogenesis
+to discover the specific and real stimulus which
+calls forth the restoring processes. For simply to say that
+the disturbance is the cause of the restoration would be to
+evade the problem instead of attacking it. But there are
+still some other problems peculiar to the doctrine of
+restitutions.</p>
+
+<p class="tac pt12b02em"><i>A few Remarks on Secondary Potencies and on Secondary
+Morphogenetic Regulations in General</i></p>
+
+<p>We have only briefly mentioned in a previous chapter
+that there exist many kinds of potencies of what we call
+the secondary or truly restitutive type, and that their
+distribution may be most various and quite independent<span class="pagenum" title="111"><a name="Page_111" id="Page_111"></a></span>
+of all the potencies for the primary processes of ontogeny
+proper. Let us first add a few words about the concept
+of “secondary restitution” and about the distribution
+of secondary potencies in general.</p>
+
+<p>Primary ontogenetic processes founded upon primary
+potencies may <em>imply</em> regulation, or more correctly, restitution
+in many cases: so it is, when fragments of the blastula
+form the whole organism, or when the mesenchyme cells
+of Echinus reach their normal final position by an attraction
+on the part of specific localities of the ectoderm in spite
+of a very abnormal original position enforced upon them
+by experiment. In these cases we speak of primary
+regulations or restitutions; disturbances are neutralised by
+the very nature of the process in question. We speak
+of secondary restitution whenever a disturbance of organisation
+is rectified by processes foreign to the realm of
+normality; and these abnormal lines of events are revealed
+to us in the first place by the activity of potencies which
+remain latent in ontogeny proper.</p>
+
+<p>We know already that a certain kind of secondary
+restitution has been discovered lately, very contradictory
+to the theoretical views of Weismann; the process of
+restoration being carried out not by any definite part of
+the disturbed organisation, but by all the single elements
+of it. The problem of the distribution of secondary
+potencies in these cases of so-called “re-differentiation” is
+to form our special study in the next chapter. In all
+other cases restoration processes start from specific localities;
+if they occur on the site of the wound which caused the
+disturbance, we speak of regeneration; if they occur at
+some distance from the wound, we call them adventitious<span class="pagenum" title="112"><a name="Page_112" id="Page_112"></a></span>
+processes. Besides these three types of processes of restitution
+there may be mentioned a fourth one, consisting in
+what is generally called compensatory hypertrophy; the
+most simple case of such a compensatory process is when
+one of a pair of organs, say a kidney, becomes larger after
+the other has been <span class="nowrap">removed.<a name="FNanchor_48_48" id="FNanchor_48_48"></a><a href="#Footnote_48_48" class="fnanchor">48</a></span> Finally, at least in plants, a
+change of the directive irritability, of so-called “geotropism”
+for instance, in certain parts may serve to restore other
+more important parts.</p>
+
+<p>In two of these general types of restitution, in regeneration
+proper and in the production of adventitious organs,
+the potencies which underlie these processes may be said
+to be “complex.” It is a complicated series of events, a
+proper morphogenesis in itself, for which the potency has
+to account, if, for instance, a worm newly forms its head
+by regeneration, or if a plant restores a whole branch in
+the form of an adventitious bud.</p>
+
+<p>Such generalisations as are possible about the distribution
+of complex potencies are reserved for a special part
+of our future discussion.</p>
+
+<p>Secondary restitution is always, like ontogeny, a process
+of morphogenesis, and therefore all the questions about
+single formative stimuli, and about internal and external
+conditions or means, occur again. But of course we cannot
+enter into these problems a second time, and may only<span class="pagenum" title="113"><a name="Page_113" id="Page_113"></a></span>
+say that, especially in regeneration proper, the specific type
+of the regenerative formation of any part may differ very
+much from the ontogenetic type of its origin: the end of
+both is the same, but the way can be even fundamentally
+different in every respect.</p>
+
+<p class="tac pt12b02em"><i>The Stimuli of Restitutions</i><a name="FNanchor_49_49" id="FNanchor_49_49"></a><a href="#Footnote_49_49" class="fnanchor">49</a></p>
+
+<p>But now we turn to the important question: what is
+the precise <span class="nowrap">stimulus<a name="FNanchor_50_50" id="FNanchor_50_50"></a><a href="#Footnote_50_50" class="fnanchor">50</a></span> that calls forth processes of restitution;
+or, in other words, what must have happened in order
+that restitution may occur?</p>
+
+<p>That the operation in itself, by its removing of mechanical
+obstacles, cannot be the true stimulus of any restitutions,
+is simply shown by all those restitutions that do not
+happen at the place of the wound. If we took a narrower
+point of view, and if we only considered regeneration proper
+from the wound itself, we might probably at first be
+inclined to advocate the doctrine that the removing of
+some obstacles might in fact be the stimulus to the process
+of restoration; but, even then, why is it that just what is
+wanted grows out? Why is there not only growth, but
+specific growth, growth followed by specification? The
+removing of an obstacle could hardly account for that.
+But, of course, taking account of all the adventitious<span class="pagenum" title="114"><a name="Page_114" id="Page_114"></a></span>
+restitutions&mdash;that is, all restorations not beginning at the
+wound itself&mdash;the theory that the removing of obstacles
+is the stimulus to restoration becomes, as we have said,
+quite <span class="nowrap">impossible.<a name="FNanchor_51_51" id="FNanchor_51_51"></a><a href="#Footnote_51_51" class="fnanchor">51</a></span></p>
+
+<p>But where then is the stimulus to be found? There
+is another rather simple theory of the “Auslösung” of
+<span class="nowrap">restitutions,<a name="FNanchor_52_52" id="FNanchor_52_52"></a><a href="#Footnote_52_52" class="fnanchor">52</a></span> which starts from the phenomena of compensatory
+hypertrophy and some occurrences among plants.
+The removal of some parts of the organism, it is said,
+will bring its other parts into better conditions of nutrition,
+and therefore these parts, particularly if they are of the
+same kind, will become larger. Granted for the moment
+that such a view may hold in cases when one of a pair
+of glands becomes larger after the other has been removed,
+or when pruning of almost all the leaves of a tree leads to
+the rest becoming larger, it certainly must fail to explain
+the fact that in other cases true <em>new</em> formations may arise
+in order to restore a damaged part, or that the latter may
+be regenerated in its proper way. For <em>merely quantitative</em>
+differences in the mixture of the blood or of the nourishing
+sap in plants can never be a sufficient reason for the highly
+typical and <em>qualitative</em> structure of newly-formed restitutions.
+And even in the most simple cases of a mere increase in
+the size of some parts, that is, in the simplest cases of
+so-called compensatory <span class="nowrap">hypertrophy,<a name="FNanchor_53_53" id="FNanchor_53_53"></a><a href="#Footnote_53_53" class="fnanchor">53</a></span> it is at least doubtful,<span class="pagenum" title="115"><a name="Page_115" id="Page_115"></a></span>
+if not very improbable, that the compensation is accomplished
+in such a purely passive way, because we know that in
+other cases it is usually the growth of the young parts
+that actively attracts the nourishment: there is first
+differentiation and growth, and <em>afterwards</em> there is a change
+in the direction of the nourishing fluids.</p>
+
+<p>The process of true regeneration, beginning at the
+locality of the wound itself, has been shown by Morgan,
+even as regards its rate, to occur quite irrespectively of the
+animal being fed or <span class="nowrap">not.<a name="FNanchor_54_54" id="FNanchor_54_54"></a><a href="#Footnote_54_54" class="fnanchor">54</a></span> There could hardly be a better
+demonstration of the fundamental fact that food assists
+restitution, but does not “cause” it in any way.</p>
+
+<p>But in spite of all we have said, there seems to be some
+truth in regarding the nutritive juices of animals and plants
+as somehow connected with the stimulus of restitutions:
+only in this very cautious form, however, may we make
+the hypothesis. It has been shown for both animals and
+plants, that morphogenesis of the restitutive type may be
+called forth even if the parts, now to be “regenerated”
+have not been actually removed; <i>e.g.</i> in the so-called
+super-regeneration of legs and tails in Amphibia, of the
+head in Planarians, of the root-tip in plants and in some
+other cases. Here it has always been a disturbance of the<span class="pagenum" title="116"><a name="Page_116" id="Page_116"></a></span>
+normal connection of some parts with the rest of the
+organism which proved to be the reason of the new formation.
+This shows that something to do with the communication
+among parts is at least connected with restitution, and
+this communication may go on either by the unknown
+action of specific tissues or by the aid of the blood or <span class="nowrap">sap.<a name="FNanchor_55_55" id="FNanchor_55_55"></a><a href="#Footnote_55_55" class="fnanchor">55</a></span>
+But in what this change or break of specific communication
+consists, is absolutely unknown. One might suppose that
+each part of the organisation constantly adds some sort of
+ferment to the body fluids outside or inside the cells, that
+the removing of any part will change the composition of
+these fluids in this particular respect, and that this change
+acts as a sort of communication to summon the restituting
+parts of the whole to do their <span class="nowrap">duty.<a name="FNanchor_56_56" id="FNanchor_56_56"></a><a href="#Footnote_56_56" class="fnanchor">56</a></span></p>
+
+<p>But I see quite well that such a theory is very little<span class="pagenum" title="117"><a name="Page_117" id="Page_117"></a></span>
+satisfactory; for what has to be done in restitution in
+each case is not a simple homogeneous act, for which one
+special material might account, but is a very complicated
+work in itself. It was the defect of the theory of “organ-forming
+substances” as advocated by Sachs, that it overlooked
+this point.</p>
+
+<p>So all we know about the proper stimuli of restitutions
+is far from resting on any valid grounds at all; let us not
+forget that we are here on the uncertain ground of what
+may be called the newest and most up-to-date branch of
+the physiology of form. No doubt, there will be something
+discovered some day, and the idea of the “whole” in
+organisation will probably play some part in it. But in
+what manner that will happen we are quite unable to
+predict.</p>
+
+<p>This is the first time that, hypothetically at least, the
+idea of the whole has entered into our discussion. The
+same idea may be said to have entered it already in a
+more implicit form in the statement of the threefold
+harmony in ontogeny.</p>
+
+<p>Let us now see whether we can find the same problem
+of the “whole” elsewhere, and perhaps in more explicit
+and less hypothetical form. Let us see whether our
+analytical theory of development is in fact as complete as
+it seemed to be, whether there are no gaps left in it which
+will have to be filled up.</p>
+
+<p><span class="pagenum" title="118"><a name="Page_118" id="Page_118"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The Problem of Morphogenetic Localisation</span></h4>
+
+<h5 class="fs120 mb05em">α. <span class="lowercase smcap">THE THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM<br />
+FIRST PROOF OF THE AUTONOMY OF LIFE</span></h5>
+
+<p>We have come to the central point of the first part of
+these lectures; we shall try in this chapter to decide a
+question which is to give life its place in Nature, and
+biology its place in the system of sciences. One of the
+foundation stones is to be laid upon which our future
+philosophy of the organism will rest.</p>
+
+
+<p class="tac pt12b02em"><i>The General Problem</i></p>
+
+<p>Our analytical theory of morphogenesis has been founded
+upon three elementary concepts: the prospective potency,
+the means, and the formative stimulus. Its principal object
+has been to show that all morphogenesis may be resolved
+into the three phenomena expressed by those concepts;
+in other terms, that morphogenesis may be proved to
+consist simply and solely of what is expressed by them.
+Have we indeed succeeded in attaining this object? Has
+nothing been left out? Is it really possible to explain
+every morphogenetic event, at least in the most general
+way, by the aid of the terms potency, means, and stimulus?</p>
+
+<p>All of these questions are apt to lead us to further<span class="pagenum" title="119"><a name="Page_119" id="Page_119"></a></span>
+considerations. Perhaps these considerations will give us
+a very clear and simple result by convincing us that it is
+indeed possible to analyse morphogenesis in our schematic way.</p>
+
+<p>But if the answer were a negative one? What would
+that suggest?</p>
+
+<p>The full analysis of morphogenesis into a series of single
+formative occurrences, brought about by the use of given
+means and on the basis of given potencies, might assure
+us, perhaps, that, though not yet, still at some future time,
+a further sort of analysis will be possible: the analysis into
+the elemental facts studied by the sciences of inorganic
+nature. The organism might prove to be a machine, not
+only in its functions but also in its very origin.</p>
+
+<p>But what are we to say if even the preliminary analysis,
+which possibly might lead to such an ultimate result, fails?</p>
+
+<p>Let us then set to work. Let us try to consider most
+carefully the topic in which our concept of the formative
+cause or stimulus may be said to be centred, the <em>localisation</em>
+of all morphogenetic effects. Is it always possible in
+fact to account for the typical localisation of every
+morphogenetic effect by the discovery of a single specific
+formative stimulus? You will answer me, that such an
+analysis certainly is not possible at present. But I ask
+you again, are there any criteria that it is possible, at least
+in principle; or are there any criteria which will render
+such an aim of science impossible for all future time?</p>
+
+
+<p class="tac pt12b02em"><i>The Morphogenetic “System”</i></p>
+
+<p>We know from our experimental work that many, if
+not all, of the elementary organs in ontogeny show one<span class="pagenum" title="120"><a name="Page_120" id="Page_120"></a></span>
+and the same prospective potency distributed equally over
+their elements. If we now borrow a very convenient term
+from mechanics, and call any part of the organism which
+is considered as a unit from any morphogenetic point of
+view, a morphogenetic “<em>system</em>,” we may sum up what
+we have learnt by saying that both the blastoderm of the
+echinoderms, at least around its polar axis, and also the
+germ-layers of these animals, are “systems” possessing an
+equal potentiality in all of their elements, or, in short, that
+they are <em>equipotential systems</em>.</p>
+
+<p>But such a term would not altogether indicate the real
+character of these systems.</p>
+
+<p>Later on we shall analyse more carefully than before
+the distribution of potencies which are the foundation both
+of regeneration proper and of adventitious growth, and
+then we shall see that, in higher plants for instance, there
+is a certain “system” which may be called the organ
+proper of restitutions, and which also in each of its elements
+possesses the same restoring potency; I refer to the well-known
+cambium. This cambium, therefore, also deserves
+the name of an “equipotential system.” But we know
+already that its potencies are of the complex type, that they
+consist in the faculty of producing the <em>whole</em>, of such a
+complicated organisation as a branch or a root, that the
+term “equipotential system” is here only to signify that
+such a complicated unit may arise out of each of the cells
+of the cambium.</p>
+
+<p>The potencies we have been studying in the blastula or
+gastrula of echinoderms are not of the complex type: our
+systems are equipotential to the extent that each of their
+elements may play every <em>single</em> part in the totality of what<span class="pagenum" title="121"><a name="Page_121" id="Page_121"></a></span>
+will occur in the whole system; it is to this <em>single</em> part
+that the term “function of the position” relates. We
+therefore might call our systems equipotential systems with
+single potencies; or, more shortly, singular-equipotential
+systems.</p>
+
+<p>But even this terminology would fail to touch precisely
+the very centre of facts: it is not only the simplicity
+or singularity of their potencies which characterises the
+rôle of our systems in <span class="nowrap">morphogenesis,<a name="FNanchor_57_57" id="FNanchor_57_57"></a><a href="#Footnote_57_57" class="fnanchor">57</a></span> but far more important
+with respect to the production of form are two
+other leading results of the experimental researches. The
+proper act to be performed by every element in each actual
+case is in fact a single one, but the potency of any element
+as such consists in the possibility of many, nay of indefinitely
+many, single acts: that then might justify us in speaking of
+our systems as “indefinite equipotential,” were it not that
+another reason makes another title seem still more preferable.
+There are indeed indefinite singular potencies at
+work in all of our systems during ontogeny: but the sum
+of what happens to arise in every case out of the sum of
+the single acts performed by all of the single equipotential
+cells is not merely a sum but a unit; that is to say, there
+exists a sort of harmony in every case among the <em>real
+products</em> of our systems. The term <em>harmonious-equipotential
+system</em> therefore seems to be the right one to denote them.</p>
+
+<p>We now shall try first to analyse to its very extremes
+the meaning of the statement that a morphogenetic system
+is harmonious-equipotential.</p>
+
+<p><span class="pagenum" title="122"><a name="Page_122" id="Page_122"></a></span></p>
+
+
+<p class="tac pt12b02em"><i>The “Harmonious-Equipotential System”</i></p>
+
+<p>We have an ectoderm of the gastrula of a starfish here
+before us; we know that we may cut off any part of it in
+any direction, and that nevertheless the differentiation of
+the ectoderm may go on perfectly well and result in a
+typical little embryo, which is only smaller in its size than
+it would normally be. It is by studying the formation of
+the highly complicated ciliary band, that these phenomena
+can be most clearly understood.</p>
+
+<p>Now let us imagine our ectoderm to be a cylinder instead
+of being approximately a sphere, and let us imagine the
+surface of this cylinder unrolled. It will give us a plane
+of two definite dimensions, <i>a</i> and <i>b</i>. And now we have all
+the means necessary for the analytical study of the differentiation
+of an harmonious-equipotential system.</p>
+
+<p>Our plane of the dimensions <i>a</i> and <i>b</i> is the basis of the
+normal, undisturbed development; taking the sides of the
+plane as fixed localities for orientation, we can say that the
+actual fate, the “prospective value” of every element of the
+plane stands in a fixed and definite correlation to the
+length of two lines, drawn at right angles to the bordering
+lines of the plane; or, to speak analytically, there is a
+definite actual fate corresponding to each possible value of
+<i>x</i> and of <i>y</i>. Now, we have been able to state by our experimental
+work, that the prospective value of the elements of
+our embryonic organ is not identical with their “prospective
+potency,” or their possible fate, this potency being very
+much richer in content than is shown by a single case of
+ontogeny. What will be the analytical expression of such
+a relation?</p>
+
+<p><span class="pagenum" title="123"><a name="Page_123" id="Page_123"></a></span></p>
+
+<p>Let us put the question in the following way: on what
+factors does the fate of any element of our system depend
+in all possible cases of development obtainable by means of
+operations? We may express our results in the form of
+an equation:&mdash;</p>
+
+<p class="tac nowrap">
+<i>p.v. (X) = f(&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i><br />
+</p>
+
+<p><i>i.e.</i> “the prospective value of the element <i>X</i> is a function
+of&nbsp;.&nbsp;.&nbsp;.”&mdash;of what?</p>
+
+<p>We know that we may take off any part of the whole,
+as to quantity, and that a proportionate embryo will
+result, unless the part removed is of a very large size.
+This means that the prospective value of any element
+certainly depends on, certainly is a function of, the <em>absolute
+size</em> of the actually existing part of our system in the
+particular case. Let <i>s</i> be the absolute size of the system
+in any actual experimental case of morphogenesis: then we
+may write <span class="nowrap"><i>p.v. (X) = f(s&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i></span>. But we shall have to add
+still some other letter to this <i>s</i>.</p>
+
+<p>The operation of section was without restriction either
+as to the amount of the material removed from the germ, or
+as to the direction of the cut. Of course, in almost every
+actual case there will be both a definite size of the actual
+system and a definite direction of the cut going hand-in-hand.
+But in order to study independently the importance
+of the variable direction alone, let us imagine that we have
+isolated at one time that part of our system which is
+bounded by the lines <i>a<sub>1</sub> b<sub>1</sub></i>, and at another time an equal
+amount of it which has the lines <i>a<sub>2</sub> b<sub>2</sub></i> as its boundaries.
+Now since in both cases a typical small organism may result
+on development, we see that, in spite of their equal size<span class="pagenum" title="124"><a name="Page_124" id="Page_124"></a></span>
+the prospective value of every element of the two pieces cut
+out of the germ may vary even in relation to the direction
+of the cut itself. Our element, <i>X</i>, may belong to both of
+these pieces of the same size: its actual fate nevertheless
+will be different. Analytically, it may be said to change in
+correspondence to the actual position of the actual boundary
+lines of the piece itself with regard to the fundamental lines
+of orientation, <i>a</i> and <i>b</i>; let this actual position be expressed
+by the letter <i>l</i>, <i>l</i> marking the distance of <span class="nowrap">one<a name="FNanchor_58_58" id="FNanchor_58_58"></a><a href="#Footnote_58_58" class="fnanchor">58</a></span> of the actual
+boundary lines of our piece from <i>a</i> or <i>b</i>: then we are entitled
+to improve our formula by writing <span class="nowrap"><i>p.v. (X) = f(s, l&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i></span>
+(Fig. 11).</p>
+
+<div class="figcenter" style="width: 440px;">
+<img src="images/fig11.jpg" width="440" height="276" alt="" />
+<p><span class="smcap">Fig. 11.&mdash;Diagram to show the Characteristics of an
+“Harmonious-equipotential System</span>.”</p>
+
+<p class="ml0em">The element <i>X</i> forms part of the systems <i>a b</i> or <i>a<sub>1</sub> b<sub>1</sub></i> or <i>a<sub>2</sub> b<sub>2</sub></i>; its prospective value is
+different in each case.</p>
+</div>
+
+<p>But the formula is not yet complete: <i>s</i> and <i>l</i> are what
+the mathematicians call variables: they may have any
+actual value and there will always be a definite value of <i>p.v.</i>,
+<i>i.e.</i> of the actual fate which is being considered; to every
+value of <i>s</i> and <i>l</i>, which as we know are independent of
+each other, there corresponds a definite value of the actual
+prospectivity. Now, of course, there is also a certain factor
+at work in every actual case of experimental or normal
+development, which is <em>not</em> a variable, but which is the same
+in all cases. This factor is a something embraced in the
+prospective potency of our system, though not properly
+identical with it.</p>
+
+<p>The prospective potency of our system, that is to say of
+each of its elements, is the sum total of what can be done
+by all; but the fact that a typically proportionate development
+occurs in every possible case, proves that this sum
+comes into account, not merely as a sum, but as a sort of<span class="pagenum" title="125"><a name="Page_125" id="Page_125"></a></span>
+order: we may call this order the “relation of localities in
+the absolutely normal case.” If we keep in mind that the
+term “prospective potency” is always to contain this order,
+or, as we may also call it, this “relative proportionality,”
+which, indeed, was the reason for calling our systems
+“harmonious,” then we may apply it without further explanation
+in order to signify the <em>non-variable</em> factor on
+which the prospective value of any element of our systems
+depends, and, if we denote the prospective potency, embracing
+order, by the letter <i>E</i>, we are now able to complete our
+formula by saying <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span>.</p>
+
+<p>So far the merely analytical study of the differentiation
+of harmonious-equipotential <span class="nowrap">systems.<a name="FNanchor_59_59" id="FNanchor_59_59"></a><a href="#Footnote_59_59" class="fnanchor">59</a></span></p>
+<p><span class="pagenum" title="126"><a name="Page_126" id="Page_126"></a></span></p>
+
+<p class="tac pt12b02em"><i>Instances of “Harmonious-Equipotential Systems”</i></p>
+
+<p>We must try at first to learn a few more positive facts
+about our systems, in order that we may know how important
+is the part which they play in the whole animal
+kingdom, and in order that our rather abstract analysis may
+become a little more familiar to us. We know already that
+many of the elementary morphogenetic organs have been really
+proved to be harmonious-equipotential systems, and that the
+same probably is true of many others; we also know that
+the immature egg of almost all animals belongs to this type,
+even if a fixed determination of its parts may be established
+just after maturation. Moreover, we said, when speaking
+about some new discoveries on form-restitution, that there
+are many cases in which the processes of restitution do not
+proceed from single localities, the seat of complex potencies
+in the organism, but in which each <em>single</em> part of the
+truncated organism left by the operation has to perform
+one <em>single</em> act of restoration, the full restitution being the
+result of the totality of all. These cases must now be
+submitted to a full analysis.</p>
+
+<p>All of you have seen common sea-anemones or sea-roses,
+and many of you will also be familiar with the so-called
+hydroid polyps. <i class="biological-name">Tubularia</i> is one genus of them: it looks
+like a sea-anemone in miniature placed on the top of a stem
+like a flower. It was known already to Allman that
+<i class="biological-name">Tubularia</i> is able to restore its flower-like head when that
+is lost, but this process was taken to be an ordinary regeneration,
+until an American zoologist, Miss Bickford,
+succeeded in showing that there was no regeneration process
+at all, in the proper sense of the word, no budding of the<span class="pagenum" title="127"><a name="Page_127" id="Page_127"></a></span>
+missing part from the wound, but that the new tubularian
+head was restored by the combined work of many parts of
+the stem. Further analysis then taught us that <i class="biological-name">Tubularia</i>
+indeed is to be regarded as the perfect type of an
+harmonious-equipotential system: you may cut the stem at
+whatever level you like: a certain length of the stem will
+always restore the new head by the co-operation of its parts.
+As the point of section is of course absolutely at our choice,
+it is clear, without any further discussion, that the prospective
+value of each part of the restoring stem is a
+“function of its position,” that it varies with its distance
+from the end of the stem; and so at once we discover one
+of the chief characteristics of our systems. But also the
+second point which enters into our formula can be
+demonstrated in <i class="biological-name">Tubularia</i>: the dependence of the fate of
+every element on the actual size of the system. You would
+not be able to demonstrate this on very long stems, but if
+you cut out of a <i class="biological-name">Tubularia</i> stem pieces which are less than
+ten millimetres in length, you will find the absolute size of
+the head restored to be in close relation to the length of
+the stem piece, and this dependence, of course, includes the
+second sort of dependence expressed in our formula.</p>
+
+<p>The figures will serve to show you a little more concretely
+what has been described. The head of <i class="biological-name">Tubularia</i>
+consists of a sort of broad base with a thin proboscis upon
+it, both bearing a large number of tentacles; these tentacles
+are the first things to be seen as primordia (“Anlagen”) in
+the process of restitution. You notice two rings of longitudinal
+lines inside the stem; the lines will become walls and then
+will separate from the stem until they are only connected
+with it at their basal ends; the new tentacles are ready as<span class="pagenum" title="128"><a name="Page_128" id="Page_128"></a></span>
+soon as that has happened, and a process of growth at the
+end will serve to drive the new head out of the so-called
+perisarc or horny skeleton, which surrounds the stem. By
+comparing the two figures, 12 <i>e</i>, and <i>g</i>, you easily find out
+that the absolute lengths of the two tentacle rings are very
+different, and that both are in <span class="nowrap">proportion<a name="FNanchor_60_60" id="FNanchor_60_60"></a><a href="#Footnote_60_60" class="fnanchor">60</a></span> to the actual size
+of the stem (Fig. 12).</p>
+
+<div class="figcenter" style="width: 495px;">
+<img src="images/fig12.jpg" width="495" height="311" alt="" />
+<p><span class="smcap">Fig. 12.&mdash;Tubularia.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Diagram of the “Hydranth,” with its short and long tentacles.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Restitution of a new hydranth inside the perisarc (<i>p</i>).</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td class="tal ti">The same&mdash;later stage; the tentacles are complete; the whole hydranth will be driven out of the perisarc by a process of growth that occurs at the locality marked ↑.</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">A stem of <i class="biological-name">Tubularia</i> cut either at <i>a<sub>1</sub>b<sub>1</sub></i> or at <i>a<sub>2</sub>b<sub>2</sub></i> or at <i>a<sub>1</sub>c</i>.</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+<tr><td class="tar vat"><i>f.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>2</sub>b<sub>2</sub></i> which is equal in length to <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+<tr><td class="tar vat"><i>g.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>1</sub>c</i>, which is half as long as <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+</table>
+</div>
+
+<p><span class="pagenum" title="129"><a name="Page_129" id="Page_129"></a></span></p>
+<p>So we find our formula <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span> very well
+illustrated in <i class="biological-name">Tubularia</i>. The formula indeed may help us
+to predict, in any case, where a certain part of the polyp’s
+organisation is to originate, at least if we know all that is
+included under our letter <i>E</i>, <i>i.e.</i> the normal proportion of
+our form. Of course such prediction would not have much
+practical importance in all our cases of morphogenesis, but
+nevertheless I should like to state here that it is possible;
+for many scientific authors of recent times have urged the
+opinion that prediction of, and domination over, what will
+happen, can be the only true aims of sciences at all. I
+myself judge these aims to be of second or third-rate importance
+only, but, if they may be reached by what our
+purely theoretical study teaches, so much the better.</p>
+
+<div class="figcenter" style="width: 424px;">
+<img src="images/fig13.jpg" width="424" height="286" alt="" />
+<p><span class="smcap">Fig. 13.&mdash;Clavellina.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">Diagram of the normal animal: <i>E</i> and <i>J</i> = openings; <i>K</i> = branchial apparatus; <i>D</i> = intestine; <i>M</i> = stomach; <i>H</i> = heart.</td></tr>
+<tr><td class="tar vat"><i>b.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">The isolated branchial apparatus.</td></tr>
+<tr><td class="tar vat"><i>c-e.</i></td><td class="tal ti">Different stages of reduction of the branchial apparatus.</td></tr>
+<tr><td class="tar vat"><i>f.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">The new <em>whole</em> little ascidian.</td></tr>
+</table>
+</div>
+
+<p>Another very typical case of a morphogenetic system
+of the harmonious type is supplied by the phenomena of
+restoration in the ascidian <i class="biological-name">Clavellina</i>. I cannot fully
+describe the organisation of this form (Fig. 13a), and it
+must suffice to say that it is very complicated, consisting
+of two very different chief parts, the branchial apparatus
+and the so-called intestinal sac; if these two parts of the
+body of <i class="biological-name">Clavellina</i> are separated one from the other, each
+may regenerate the other in the typical way, by budding
+processes from the wound. But, as to the branchial
+apparatus, there may happen something very different:
+it may lose almost all of its organisation and become a
+small white sphere, consisting only of epithelia corresponding
+to the germ-layers, and of mesenchyme between them,
+and then, after a certain period of rest, a new organisation
+will appear. Now this new organisation is not that of a
+branchial apparatus but represents a very small but com<span class="pagenum" title="130"><a name="Page_130" id="Page_130"></a></span>plete
+ascidian (Fig. 13). Such a fact certainly seems to
+be very important, not to say very surprising; but still
+another phenomena may be demonstrated on the animal
+which seems to be even more important. You first isolate
+the branchial apparatus from the other part of the body,
+and then you cut it in two, in whatever direction you
+please. Provided they survive and do not die, as indeed
+many of them do, the pieces obtained by this operation
+will each lose their organisation, as did the whole branchial
+apparatus, and then will each acquire another one, and
+this new organisation is also that of a <em>complete</em> little
+<i class="biological-name">Clavellina</i>. So we see that not only is the branchial
+apparatus of our animal capable of being transformed into
+a whole animal by the co-operative work of all its parts,
+but even each part of it may be transformed into a small
+<em>whole</em>, and it is quite at our disposal how large this part
+shall be, and what sort of a fragment of the original
+branchial apparatus it shall represent.</p>
+
+<p>We could hardly imagine a better instance of an
+harmonious-equipotential system.</p>
+
+<p>I cannot give you a description of all the other types
+of our systems subservient to restitution, and I can only
+mention here that the common hydra and the flatworm
+<i class="biological-name">Planaria</i> are very fine examples of them. But to one
+special case of harmonious equipotentiality you must allow
+me to direct your further attention.</p>
+
+<p>It has been known for many years that the Protozoa
+are also capable of a restoration of their form and organisation
+after disturbances, if at least they contain a certain
+amount of their nuclear substance. This process of restoration
+used to be regarded as belonging to the common type<span class="pagenum" title="131"><a name="Page_131" id="Page_131"></a></span>
+of regeneration proper, until T. H. Morgan succeeded in
+showing that in the genus <i class="biological-name">Stentor</i> it follows just the very
+lines which we know already from our study of embryonic
+organs or from <i class="biological-name">Tubularia</i>; that an harmonious-equipotential
+system is at the basis of what goes on. Now, you know
+that all Protozoa are but one highly organised cell: we
+have therefore here an instance where the so-called
+“elements” of our harmonious-morphogenetic system are
+not cells, but something inside of cells; and this feature
+must appear to be of very great moment, for it first shows,
+as we have already pointed out on another occasion, that
+morphogenesis is not dependent on cell-division, and it
+states at the same time that our concept of the harmonious-<span class="pagenum" title="132"><a name="Page_132" id="Page_132"></a></span>equipotential
+system may cover a very great area&mdash;that, in
+fact, it is a scheme of a very wide extent.</p>
+
+
+<p class="tac pt12b02em"><i>The Problem of the Factor</i> E</p>
+
+<p>We turn back again to considerations of a more abstract
+form. We left our analysis of the differentiation of the
+harmonious-equipotential systems, and particularly of the
+phenomena of localisation during this differentiation, at the
+point where we had succeeded in obtaining an equation
+as the expression of all those factors on which the prospective
+value, the actual fate, of any element of our
+systems depends, <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span> was the short expression
+of all the relations involved; <i>s</i> and <i>l</i>, the absolute
+size of the system and the relative position of the element
+with respect to some fixed points, were independent variables;
+<i>E</i> was a constant, namely, the prospective potency, with
+special regard to the proportions embraced by it.</p>
+
+<p>We shall now study the significance of the factor <i>E</i>.</p>
+
+<p>What does this <i>E</i> mean? Is it a short expression
+merely for an actual sum of elemental agents having a
+common resultant? And, if so, of what kind are these
+agents? Or what may <i>E</i> mean, if it can be shown <em>not</em> to
+be a short sign for a mere sum?</p>
+
+
+<p class="tac pt12b02em"><i>No Explanation Offered by “Means” or “Formative Stimuli”</i></p>
+
+<p>For practical purposes it seems better if we modify the
+statement of our question. Let us put it thus: <i>E</i> is one
+of the factors responsible, among variables, for the localisation
+of organic differentiation; what then do we actually
+know about the causal factors which play a localising part<span class="pagenum" title="133"><a name="Page_133" id="Page_133"></a></span>
+in organogenesis? We, of course, have to look back to our
+well-studied “formative stimuli.” These stimuli, be they
+“external” or “internal,” come from without with respect to
+the elementary organ in which any sort of differentiation,
+and therefore of localisation, occurs: but in our harmonious
+systems no localising stimulus comes from without, as was
+the case, for instance, in the formation of the lens of the
+eye in response to the optical vesicle touching the skin.
+We know absolutely that it is so, not to speak of the self-evident
+fact that the general “means” of organogenesis
+have no localising value at <span class="nowrap">all.<a name="FNanchor_61_61" id="FNanchor_61_61"></a><a href="#Footnote_61_61" class="fnanchor">61</a></span></p>
+
+<p>So we see there is nothing to be done, either with
+the means or with the formative stimuli; both are entirely
+unable to account for those kinds of localisation during
+differentiation which appear in our harmonious systems.</p>
+
+<p>But is there no possibility of explaining the phenomena
+of organogenetic localisation by any other sort of interaction
+of parts? Two such possibilities may at the first glance
+seem to exist.</p>
+
+<p><span class="pagenum" title="134"><a name="Page_134" id="Page_134"></a></span></p>
+
+
+<p class="tac pt12b02em"><i>No Explanation Offered by a Chemical Theory
+of Morphogenesis</i></p>
+
+<p>Though never set forth, in the form of a properly worked-out
+theory, the view has sometimes been advocated by
+biologists, that a chemical compound of a very high degree
+of complication might be the very basis of both development
+and inheritance, and that such a chemical compound by its
+disintegration might direct morphogenesis.</p>
+
+<p>Let us first examine if such a view may hold for the
+most general features of organic morphogenesis. It seems
+to me that from the very beginning there exists one very
+serious objection to every chemical theory of form-building,
+in the mere fact of the possibility of the restoration of form
+starting from atypical localities. The mere fact, indeed,
+that there is such a thing as the regeneration of a leg of a
+newt&mdash;to say nothing about restitution of the harmonious
+type&mdash;simply <span class="nowrap">contradicts,<a name="FNanchor_62_62" id="FNanchor_62_62"></a><a href="#Footnote_62_62" class="fnanchor">62</a></span> it seems to me, the hypothesis,
+that chemical disintegration of one compound may govern
+the course of morphogenetic events: for whence comes
+the re-existence of the hypothetical compound, newly to
+be disintegrated, after disintegration <em>has</em> been completed
+once already? And we even know that regeneration may
+go on several times running from the same locality!</p>
+<p><span class="pagenum" title="135"><a name="Page_135" id="Page_135"></a></span></p>
+<p>But, if we intentionally disregard this difficulty, in spite
+of its fundamental character, how could the hypothesis of
+chemical disintegration give the reason for the differentiation
+of our harmonious-equipotential systems, with special
+regard to the localisation of it; how could it account, in
+other words, for the appearance of typically localised specifications
+in an organ for which no external localising causes
+can be predicated?</p>
+
+<p>Let us remember that a few original intimate differences
+exist in our harmonious systems: the main directions of
+the intimate protoplasmic structure including polarity and
+bilaterality. There are therefore three times two specified
+poles in each of these systems, at least in bilateral organisms,
+but no other differences are present in them. A few very
+simple cases of harmonious differentiation might indeed be
+understood on the theory of a disintegrating chemical compound
+in connection with these few differences. Imagine
+that the original compound, of the quantity <i>a</i>, is disintegrated
+to the amount of <i>a</i><sub>1</sub>; from <i>a</i><sub>1</sub> are formed the two more
+simple compounds, <i>b</i> and <i>c</i>, both of them in definite
+quantities; then we have the three chemical individuals,
+<i>a-a</i><sub>1</sub>, <i>b</i> and <i>c</i>, as the constituents of our harmonious system;
+and it now might be assumed, without any serious difficulty,
+though with the introduction of some new hypotheses, that
+the two poles of one of the fundamental axes of symmetry
+attract <i>b</i> and <i>c</i> respectively, <i>a-a</i><sub>1</sub> remaining unattracted
+between them. We thus should have the three elementary
+constituents of the system separated into three parts, and
+as they all three are of a definite quantity, their separation
+would mean that the system had been divided into three
+<span class="pagenum" title="136"><a name="Page_136" id="Page_136"></a></span>parts, <i>a-a</i><sub>1</sub>, <i>b</i> and <i>c</i>, also with regard to its proper form.
+It is clear, that by taking away any part of the original
+system, by means of operations, there would be taken away
+a certain amount of the original compound; say that <i>a/n</i>
+is left; then, of course, the three constituents after the
+partial disintegration would be <i>a-a<sub>1</sub>/n</i>, <i>b/n</i> and <i>c/n</i>, and so it
+follows that the proportionality of localisation would really
+be preserved in any case.</p>
+
+<p>But these considerations, evident as they seem to be in
+the most simple case, fail to satisfy in a really general
+sense: for two different reasons. First, they could never
+account for the fact that the differentiated organism by no
+means consists of so many different compounds as it shows
+single parts of its differentiation, but that, on the contrary,
+it only consists, as we know, of a certain rather limited
+number of true different morphogenetic elements, these
+elements occurring again and again&mdash;as for instance, nervous
+or muscular elements&mdash;but typical each time in locality,
+quantity, and form. And in the second place, the very
+<em>form</em> of elementary organs, their form as such, does not at
+all go hand-in-hand with chemical differences; this feature
+alone would absolutely overthrow any sort of a chemical
+morphogenetic theory to account for the problem of
+localisation. Take the typically arranged ring of the
+mesenchyme cells in our Echinus-gastrula, with its two
+spherical triangles, so typically localised; look at any sort
+of skeleton, in Radiolaria, or in starfishes, or in vertebrates:
+here you have form, real form, but form consisting of only
+one material. Not only is the arrangement of the elements
+of form typical here, <i>e.g.</i> the arrangement of the single<span class="pagenum" title="137"><a name="Page_137" id="Page_137"></a></span>
+parts of the skeleton of the hand or foot, but also the
+special form of each element is typical, <i>e.g.</i> the form of
+each single bone of the foot; and, on a purely chemical
+theory of morphogenesis the sufficient reason for the
+production of typical form in such a sense would be wanting.
+For atoms or molecules by themselves can only
+account for form which is arranged, so to speak, according
+to spatial geometry&mdash;as in fact they do in crystallography;
+but they can never account for form such as the skeleton
+of the nose, or hand, or foot. You will answer me perhaps,
+that there may be non-chemical agents in the <span class="nowrap">germ,<a name="FNanchor_63_63" id="FNanchor_63_63"></a><a href="#Footnote_63_63" class="fnanchor">63</a></span> responsible
+for typical form-localisation, but by such reasoning
+you would be departing from a purely chemical theory.
+Our next paragraph will be devoted to this side of the
+question.</p>
+
+<p>That is the principal reason for rejecting all sorts of
+chemical morphogenetic theories put forward to explain the
+problem of localisation; it is more explicit, and therefore,
+I suppose, still more convincing than the more general consideration
+that the very fact of restitutions in itself must
+contradict the hypothesis that a disintegration of compounds
+might be the directive agency in morphogenesis. To sum
+up: Specificity of organic form does not go hand-in-hand
+with specificity of chemical composition, and therefore cannot
+depend on it; and besides that, specific organic form is
+such that it can never be explained by atomic or molecular
+arrangement in the chemical sense; for, to state it in a
+short but expressive manner, the “form” of an atom or
+molecule can never be that of a lion or a monkey. To<span class="pagenum" title="138"><a name="Page_138" id="Page_138"></a></span>
+assume that would be to go beyond the limits of chemistry
+in chemistry itself.</p>
+
+
+<p class="tac pt12b02em"><i>No Machine Possible Inside the Harmonious Systems</i></p>
+
+<p>And now we turn to the last possibility which is left
+to us in our endeavour to “understand” the localisation of
+the differentiation in our harmonious-equipotential systems
+by the means of physics and chemistry. Outside causes
+have failed to account for it, chemical disintegration of a
+compound has failed too. But could there not exist some
+sort of complicated interactions amongst the parts of the
+harmonious system themselves? Could there not exist
+some kind of a real machine in the system, which, if once
+set going, would result in the differentiations that are to
+take place? Then we might say that the “prospective
+potency” of the system is in fact that machine; we should
+know what the letter <i>E</i> of our equation stood for: viz.,
+a resultant action of many complicated elemental interactions,
+and nothing more.</p>
+
+<p>Weismann, we know already, had assumed that a sort
+of machine was the prime mover of morphogenesis. We
+have seen that his theory cannot be true; the results of
+experiments most strongly contradict it. But, of course,
+the experiments only showed us that <em>such</em> a machine as <em>he</em>
+had imagined to exist could not be there, that development
+could not be governed by the disintegration of a given
+complicated structure into its simplest parts. But might
+not some other machine be imaginable?</p>
+
+<p>We shall understand the word “machine” in a most
+general sense. A machine is a typical configuration of<span class="pagenum" title="139"><a name="Page_139" id="Page_139"></a></span>
+physical and of chemical constituents, by the acting of which
+a typical effect is attained. We, in fact, lay much stress
+upon embracing in our definition of a machine the existence
+of chemical constituents also; we therefore understand by
+the word “machine” a configuration of a much higher degree
+of complication than for instance a steam-engine is. Of
+course a machine, whose acting is to be typical with regard
+to the three dimensions in space, has to be typically constructed
+with regard to these three dimensions itself; a
+machine that was an arrangement of elements in a strict
+plane could never have typical effects at right angles
+to that plane. This is a point which must well be kept
+in mind in all hypothetical considerations about machines
+that claim to explain morphogenesis.</p>
+
+<p>It must be granted that a machine, as we understand
+the word, might very well be the motive force of organogenesis
+in general, if only normal, that is to say, if only
+undisturbed development existed, and if a taking away of
+parts of our systems led to fragmental development.</p>
+
+<p>But we know that, at least in our harmonious-equipotential
+systems, quite another process occurs after parts
+have been taken away: the development that occurs is not
+fragmental but whole, only on a smaller scale.</p>
+
+<p>And we know, further, that this truly whole development
+sets in irrespective of the amount and direction of the
+separation. Let us first consider the second of these points.
+There may be a whole development out of each portion of
+the system&mdash;above certain limits&mdash;which is, say, of the
+volume <i>V</i>. Good! Then there ought to exist a machine, like
+that which exists in the whole undisturbed system, in this
+portion <i>V</i> also, only of smaller dimensions; but it also<span class="pagenum" title="140"><a name="Page_140" id="Page_140"></a></span>
+ought to exist in the portion <i>V</i><sub>1</sub> which is equal to <i>V</i> in
+amount, and also in <i>V</i><sub>2</sub>, in <i>V</i><sub>3</sub>, <i>V</i><sub>4</sub> and so on. Indeed,
+there do exist almost indefinitely many <i>V</i><sub>n</sub> all of which
+can perform the whole morphogenesis, and all of which
+therefore ought to possess the machine. But these different
+portions <i>V</i><sub>n</sub> are only partly different from each other in
+spatial relation. Many parts of <i>V</i><sub>2</sub> are also parts of <i>V</i><sub>1</sub> and
+of <i>V</i><sub>3</sub> and of <i>V</i><sub>4</sub> and so on; that is to say, the different
+volumes <i>V</i><sub>n</sub> overlap each other successively and in such a
+manner that each following one exceeds the preceding one
+in the line by a very small amount only. But what then
+about our machines? Every volume which may perform
+morphogenesis completely must possess the machine in its
+totality. As now every element of one volume may play
+any possible elemental rôle in every other, it follows that
+each part of the whole harmonious system possesses any
+possible elemental part of the machine equally well, all
+parts of the system at the same time being constituents of
+different machines.</p>
+
+<p>A very strange sort of machine indeed, which is the
+same in all its parts (Fig. 14)!</p>
+
+<div class="figcenter" style="width: 448px;">
+<img src="images/fig14.jpg" width="448" height="111" alt="" />
+<p><span class="smcap">Fig. 14.&mdash;An “Harmonious-equipotential System” of whatever kind.</span></p>
+<p>
+According to the “machine-theory” of life this system ought to possess a certain unknown very complicated machine <em>in its completeness</em>:<br />
+<span class="ml27em">(<i>a</i>) in its total length,</span><br />
+<span class="ml1em">and (<i>b</i>) in each of the equal volumes <i>v</i>, <i>v</i><sub>1</sub>, <i>v</i><sub>2</sub>, <i>v</i><sub>3</sub> and so on,</span><br />
+<span class="ml1em">and (<i>c</i>) in each of the unequal volumes <i>w</i>, <i>x</i>, <i>y</i>, and so on,</span><br />
+<span class="ml1em">and (<i>d</i>) in every imaginable volume, no matter of what size.</span><br />
+Therefore the “machine-theory” of life is absurd.
+</p>
+</div>
+
+<p>But we have forgotten, I see, that in our operation
+the absolute amount of substance taken away from the
+system was also left to our choice. From this feature
+it follows that not only all the different <i>V</i><sub>n</sub>, all of the
+same size, must possess the hypothetic machine in its
+completeness, but that all amounts of the values <i>V</i><sub>n</sub>-<i>n</i>,
+<i>n</i> being variable, must possess the totality of the machine
+also: and all values <i>V</i><sub>n</sub>-<i>n</i>, with their variable <i>n</i>, may again
+overlap each other.</p>
+
+<p>Here we are led to real absurdities!</p>
+
+<p><span class="pagenum" title="141"><a name="Page_141" id="Page_141"></a></span></p>
+
+<p>But what is the conclusion of our rather wild considerations?</p>
+
+<p>It seems to me that there is only one conclusion
+possible. If we are going to explain what happens in our
+harmonious-equipotential systems by the aid of causality
+based upon the constellation of single physical or chemical
+factors and events, there <em>must</em> be some such thing as a
+machine. Now the assumption of the existence of a machine
+proves to be absolutely absurd in the light of the experimental
+facts. <em>Therefore there can be neither any sort of a machine
+nor any sort of causality based upon constellation underlying
+the differentiation of harmonious-equipotential systems.</em></p>
+
+<p>For a machine, typical with regard to the three chief
+dimensions of space, cannot remain itself if you remove
+parts of it or if you <span class="nowrap">rearrange<a name="FNanchor_64_64" id="FNanchor_64_64"></a><a href="#Footnote_64_64" class="fnanchor">64</a></span> its parts at will.</p>
+
+<p>Here we see that our long and careful study of morphogenesis
+has been worth while: it has afforded us a result
+of the very first importance.</p>
+<p><span class="pagenum" title="142"><a name="Page_142" id="Page_142"></a></span></p>
+
+<p class="tac pt12b02em"><i>The Autonomy of Morphogenesis Proved</i></p>
+
+<p>No kind of causality based upon the constellations of
+single physical and chemical acts can account for organic
+individual development; this development is not to be
+explained by any hypothesis about configuration of physical
+and chemical agents. Therefore there must be something
+else which is to be regarded as the sufficient reason of
+individual form-production. We now have got the answer
+to our question, what our constant <i>E</i> consists in. It is not
+the resulting action of a constellation. It is not only a
+short expression for a more complicated state of affairs,
+it expresses <em>a true element of nature</em>. Life, at least morphogenesis,
+is not a specialised arrangement of inorganic events;
+biology, therefore, is not applied physics and chemistry: life
+is something apart, and biology is an independent science.</p>
+
+<p>All our results at present, indeed, are negative in their
+form; our evidence was throughout what is called <i lang="la" xml:lang="la">per
+exclusionem</i>, or indirect or apagogic. There were excluded
+from a certain number of possibilities all except one; a
+disjunctive proposition was stated in the form: <i>E</i> is either
+this, or that, or the other, and it was shown that it could
+not be any of all these except one, therefore it was proved
+to be that one. Indeed, I do not see how natural science
+could argue otherwise; no science dealing with inorganic
+phenomena does; something new and elemental must
+always be introduced whenever what is known of other
+elemental facts is proved to be unable to explain the facts
+in a new field of investigation.</p>
+
+<p>We shall not hesitate to call by its proper name what
+we believe we have proved about morphogenetic phenomena.<span class="pagenum" title="143"><a name="Page_143" id="Page_143"></a></span>
+What we have proved to be true has always been called
+<em>vitalism</em>, and so it may be called in our days again. But
+if you think a new and less ambitious term to be better
+for it, let us style it the doctrine of the <em>autonomy of life</em>,
+as proved at least in the field of morphogenesis. I know
+very well that the word “autonomy” usually means the
+faculty of <em>giving</em> laws to oneself, and that in this sense it
+is applied with regard to a community of men; but in our
+phrase autonomy is to signify the <em>being subjected</em> to laws
+peculiar to the phenomena in question. This meaning is
+etymologically defensible, and besides that I perhaps may
+remind you of a certain chapter of Professor Ward’s Gifford
+Lectures, in which he holds the view that, psychologically
+and epistemologically, there is more than a mere verbal
+relation between the civil and the natural “law.”</p>
+
+<p>Vitalism then, or the autonomy of life, has been proved
+by us indirectly, and cannot be proved otherwise so long as
+we follow the lines of ordinary scientific reasoning. There
+can indeed be a sort of direct proof of vitalism, but now is
+not the time to develop this proof, for it is not of the purely
+scientific character, not so naïve as our present arguments
+are, if you choose to say so. An important part of our
+lectures next summer will be devoted to this direct proof.</p>
+
+
+<p class="tac pt12b02em">“<i>Entelechy</i>”</p>
+
+<p>But shall we not give a name to our vitalistic or
+autonomous factor <i>E</i>, concerned in morphogenesis? Indeed
+we will, and it was not without design that we chose the
+letter <i>E</i> to represent it provisionally. The great father
+of systematic philosophy, Aristotle, as many of you will<span class="pagenum" title="144"><a name="Page_144" id="Page_144"></a></span>
+know, is also to be regarded as the founder of theoretical
+biology. Moreover, he is the first vitalist in history, for
+his theoretical biology is throughout vitalism; and a very
+conscious vitalism indeed, for it grew up in permanent
+opposition to the dogmatic mechanism maintained by the
+school of Democritus.</p>
+
+<p>Let us then borrow our terminology from Aristotle, and
+let that factor in life phenomena which we have shown to
+be a factor of true autonomy be called <em>Entelechy</em>, though
+without identifying our doctrine with what Aristotle meant
+by the word <ins title="entelecheia">έντελέχεια</ins>. We shall use this word only as a
+sign of our admiration for his great genius; his word is
+to be a mould which we have filled and shall fill with new
+contents. The etymology of the word <ins title="entelecheia">ἐντελέχεια</ins> allows us
+such liberties, for indeed we have shown that there is at
+work a something in life phenomena “which bears the end
+in itself,” <ins title="ho echei en eautô to telos">ὃ ἔχει ἐν ἑαυτᾣ τὸ τέλος</ins>.</p>
+
+<p>Our concept of entelechy marks the end of our analysis of
+individual morphogenesis. Morphogenesis, we have learned,
+is “epigenesis” not only in the descriptive but also in the
+theoretical sense: manifoldness in space is produced where
+no manifoldness was, real “evolutio” is limited to rather
+insignificant topics. But was there nothing “manifold”
+previous to morphogenesis? Nothing certainly of an
+<em>extensive</em> character, but there was something else: there was
+entelechy, and thus we may provisionally call entelechy an
+“<em>intensive manifoldness</em>.” That then is our result: not
+evolutio, but epigenesis&mdash;<span class="pagenum" title="145"><a name="Page_145" id="Page_145"></a></span>“epigenesis vitalistica.”</p>
+
+
+<p class="tac pt12b02em"><i>Some General Remarks on Vitalism</i></p>
+
+<p>We now shall leave entelechy where it stands: next
+summer we shall turn back to it and shall make its full
+logical and ontological analysis our chief study. At present
+we are satisfied with having proved its existence in nature,
+with having laid some of the foundations of a doctrine to be
+based upon it. I hope that these foundations will evince
+themselves strong: that is <span class="nowrap">all-important.<a name="FNanchor_65_65" id="FNanchor_65_65"></a><a href="#Footnote_65_65" class="fnanchor">65</a></span> It indeed has
+been the fault of all vitalism in the past that it rested on
+weak foundations. Therefore the discussion of the basis
+underlying our doctrine of the autonomy of life is to occupy
+us still a considerable time. We shall devote to it two
+more of this year’s lectures and three of the next; we shall
+examine all sorts of phenomena of life in order to find out
+if there are any further proofs of vitalism, independent
+perhaps, of what we way call our <em>first proof</em>, which is based
+upon the analysis of the <em>differentiation of harmonious-equipotential
+systems</em>. We shall find some more independent
+proofs; and besides that we shall find many kinds of
+phenomena upon which future times perhaps may erect
+more of such independent proofs.</p>
+
+<p>For we shall be chary of bestowing the name “proof”
+except on what is a proof indeed, of course according to our
+critical conviction. Vitalistic views in biology have arisen<span class="pagenum" title="146"><a name="Page_146" id="Page_146"></a></span>
+in rather numerous forms during the last fifteen years,
+especially in Germany&mdash;though in very strong contrast to
+the so-called official German biology&mdash;but I can only admit
+that one of all the arguments of “neo-vitalism” has proved
+its statements. I refer to the theory of “morphaesthesia” as
+developed by Noll, which we shall study briefly in the next
+lecture. I cannot concede that Reinke or Schneider or
+Pauly have really proved what they believe, and I cannot
+even allow to the most original thinker in this field,
+Gustav Wolff, that he has given a real demonstration of his
+views. He states that the existence of so-called “primary
+purposefulness,” that is, the existence of adaptive processes,
+which cannot be imagined to have arisen on Darwinian
+principles, is able to prove vitalism; but I say that it only
+proves teleology, which is a broader concept than vitalism.</p>
+
+<p>The possibility of a machine at the root of the phenomena
+in question always has to be excluded in order that vitalism
+may be proved, and I cannot grant that the necessity of
+such an exclusion has been actually shown by any of my
+fellow-combatants against so-called mechanism, except <span class="nowrap">Noll.<a name="FNanchor_66_66" id="FNanchor_66_66"></a><a href="#Footnote_66_66" class="fnanchor">66</a></span></p>
+
+
+<p class="tac pt12b02em"><i>The Logic of our First Proof of Vitalism</i></p>
+
+<p>Let us devote the end of our present lecture to an
+account of the logical means by which it has been possible
+to develop what we hope will be regarded as a true <em>proof</em>
+of life autonomy.</p>
+
+<p>Firstly, we have looked upon the phenomena of<span class="pagenum" title="147"><a name="Page_147" id="Page_147"></a></span>
+morphogenesis without any prepossessions; we may say
+that we have fully surrendered ourselves to them; we have
+not attacked them with any sort of dogmatism except the
+inherent dogmatism of all reasoning. But this dogmatism,
+if it may be called so, does not postulate that the results of
+the inorganic doctrines must hold for the organic world, but
+only that both the inorganic and the organic must be
+subject to certain most general principles.</p>
+
+<p>By studying life as a given phenomenon, by fully
+devoting ourselves to our problem, we not only have
+analysed into its last elements what was given to us as
+our subject, but we also, more actively, have created new
+combinations out of those elements: and it was from the
+discussion of these positive constructions that our argument
+for vitalism was derived.</p>
+
+<p>We have analysed morphogenesis into elementary processes,
+means, potency, formative stimulus, just as the
+physicist analyses mechanics into time, velocity, mass, and
+force; we have then rearranged our elements into “systems”&mdash;the
+equipotential systems, the harmonious-equipotential
+system in particular, just as the physicist composes
+his elements into the concepts of momentum or of kinetic
+energy or of work. And finally, we have discussed our
+compositions and have obtained our result, just as the
+physicist gets his ultimate results by discussing work and
+kinetic energy and momentum.</p>
+
+<p>Of course the comparison is by no means intended to
+show that mechanics and biology are sciences of the same
+kind. In my opinion, they are not so at all; but nevertheless
+there do exist similarities of a logical kind between them.</p>
+
+<p>And it is not the formal, logical character alone which<span class="pagenum" title="148"><a name="Page_148" id="Page_148"></a></span>
+allows us to compare biology with other natural sciences:
+there is still something more, there is one kind of assumption
+or postulate, or whatever you may choose to call it,
+without which all science whatever would be altogether
+<em>impossible</em>. I refer to the concept of <em>universality</em>. All
+concepts about nature which are gained by positive construction
+out of elements resulting from analysis, claim to
+be of <em>universal validity</em>; without that claim there could
+indeed be no science.</p>
+
+<p>Of course this is no place for a lecture on methodology,
+and it therefore must suffice to make one remark with
+special regard to our purpose, which we should like to
+emphasise. Our concept of the harmonious-equipotential
+system&mdash;say rather, our concept of the prospective
+potency itself&mdash;presumes the understanding that indeed
+<em>all</em> blastomeres and <em>all</em> stems of <i class="biological-name">Tubularia</i>, including those
+upon which we have <em>not</em> carried out our experiments,
+will behave like those we have experimented with; and
+those concepts also presume that a certain germ of Echinus,
+<i>A</i>, the blastomeres of which were not separated, would have
+given two whole larvae, if separation had taken place, while
+another germ, <i>B</i>, which actually gave us two larvae after
+separation, would only have given one without it. Without
+this presumption the concept of “potency” is meaningless,
+and, indeed, every assumption of a “faculty” or a
+“possibility” would be meaningless in the whole area of
+science.</p>
+
+<p>But this presumption can never be proved; it can only
+be postulated. It therefore is only with this postulate that
+our first proof of vitalism holds; but this restriction applies
+to <em>every</em> law of nature.</p>
+
+<p><span class="pagenum" title="149"><a name="Page_149" id="Page_149"></a></span></p>
+
+<p>I cannot force you to agree with this postulate: but if
+you decline you are practically saying that there exists a
+sort of pre-established harmony between the scientific object
+and the scientist, the scientist always getting into his hands
+such objects only as have been predestinated from the very
+beginning to develop two larvae instead of one, and so on.</p>
+
+<p>Of course, if that is so, no proof of natural laws is
+possible at all; but nature under such views would seem to
+be really dæmonic.</p>
+
+<p>And so, I hope, you will grant me the postulate of the
+universality of scientific concepts&mdash;the only “hypothesis”
+which we need for our argument.</p>
+
+<p><span class="pagenum" title="150"><a name="Page_150" id="Page_150"></a></span></p>
+
+
+<h4 class="fs120">4. <span class="smcap">On Certain other Features of Morphogenesis
+Advocating its Autonomy</span></h4>
+
+<p>Our next studies on the physiology of form will be
+devoted in the first place to some additional remarks about
+our harmonious-equipotential systems themselves, and about
+some other kinds of morphogenetic “systems” which show
+a certain sort of relationship with them. For it is of the
+greatest importance that we should become as familiar as
+possible with all those facts in the physiology of form upon
+the analysis of which are to be based almost all of the
+future theories that we shall have to develop in biology
+proper and philosophical. Our discussions, so far as they
+relate to questions of actual fact, will contain only one
+other topic of the same importance.</p>
+
+<p>But though it is designed to complete and to deepen
+our analysis, the present considerations may yet be said to
+mark a point of rest in the whole of our discussions: we have
+followed one single line of argumentation from the beginning
+until now; this line or this stream of thought, as you
+might call it, is now to break into different branches for a
+while, as if it had entered from a rocky defile into a plain.
+It seems to me that such a short rest will be not unconducive
+to a right understanding of all we have made out;
+and such a full and real conceiving again, such a realising<span class="pagenum" title="151"><a name="Page_151" id="Page_151"></a></span>
+of our problems of morphogenesis and their solutions, will
+be the best preparation for the philosophical part of these
+lectures.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HARMONIOUS-EQUIPOTENTIAL SYSTEMS FORMED BY
+WANDERING CELLS</span></p>
+
+<p>All of the harmonious-equipotential systems which we
+have studied so far were the bases of histological
+differentiation; that is to say, the processes of their
+differentiation consisted in specifically localised elements
+of theirs becoming different <i lang="la" xml:lang="la">in situ</i>. Now we know at
+least one type of systems which also may be called
+harmonious-equipotential, but the differentiation of which
+does not simply relate to elements at a fixed place. An
+additional phenomenon enters here into the sphere of the
+others. The elements not only become different where
+they are, but a specific changing of locality, a specific kind
+of wandering, goes hand-in-hand with differences relating
+to the prospective value to be attained. I am speaking of
+the formation of the larval skeleton of our well-known
+Echinus. We know that the mesenchyme cells, which have
+left the blastoderm and are arranged in a sort of ring of
+bilateral structure, are the starting-point of this skeleton:
+it indeed originates in a sort of secretive process on the
+part of the cells; the cells are moving about and are
+secreting carbonate of lime during their wandering. The
+experiments now have shown, as we know, that a whole,
+though smaller, skeleton may also be formed, if only
+a half or a quarter of the mesenchyme cells are present, as
+happens to be the case in all experiments with isolated<span class="pagenum" title="152"><a name="Page_152" id="Page_152"></a></span>
+blastomeres of the two or four-cell stage of cleavage. It
+is clear that in these cases the performance of each single
+cell must be different from what it is in the normal case, and
+that the same sort of differences in the morphogenetic
+performances appears again, if the two- and the four-cell
+stage are compared with each other. And there are still
+some other phenomena showing the possibility of different
+performances being carried out by the individual cells.
+Peter has shown that the number of mesenchyme cells
+may vary enormously under certain conditions; but, in
+spite of that, the skeleton always will be complete. It
+may be said that this line of research is only of a relative
+value to our own questions, as, of course, variability relates
+to different individuals: but it seems to me that it adds a
+very good supplementary instance to what the experiment
+on the individual itself has established.</p>
+
+<p>We should only be repeating ourselves if we were to
+analyse again what happens here as the expression of
+the harmonious-equipotentiality itself. But indeed there
+occurs something new in this instance: the single mesenchyme
+cell not only has to perform in each case that single
+act of specific secretion which the case requires, but it also
+has to wander to the right place in order to perform it;
+there must be some order, not only about the acts of
+secretion after wandering, but also in the migrations themselves.
+If undisturbed ontogeny alone were possible, and
+if therefore a theory like that of Weismann were in place,
+we might say perhaps that each mesenchyme-cell is specified
+not only as to its performance in secretion, but also with
+regard to its chemotactical irritability, the latter being
+typically localised, so that its effect becomes typical, thanks<span class="pagenum" title="153"><a name="Page_153" id="Page_153"></a></span>
+to the typical arrangement of all the cells with respect to
+each other. But that is certainly not the case. Now, you
+may ask yourselves if you could imagine any sort of a
+machine, which consists of many parts, but not even of an
+absolutely fixed number, all of which are equal in their
+faculties, but all of which in each single case, in spite of
+their potential equality, not only produce together a certain
+typical totality, but also arrange themselves typically in
+<em>order</em> to produce this totality. We <em>are</em> indeed familiar
+with certain occurrences in nature where such curious
+facts are observed, but I doubt if you would speak of
+“machines” in these cases. The mesenchyme-cells, in
+fact, behave just as a number of workmen would do who
+are to construct, say, a bridge. All of them <em>can</em> do every
+single act, all of them also <em>can</em> assume every single position:
+the result always is to be a perfect bridge; and it is to
+be a perfect bridge even if some of the workmen become
+sick or are killed by an accident. The “prospective values”
+of the single workman change in such a case.</p>
+
+<p>I well know that it is only an analogy which I am
+offering to you. The mesenchyme-cells have not “learned,”
+have no “experience.” All that is to occupy us next
+summer. But in spite of it, there is truth in the analogy;
+and perhaps you will prefer it to the merely abstract
+consideration.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN COMBINED TYPES OF MORPHOGENETIC SYSTEMS</span></p>
+
+<p>For the sake of completeness it may be remarked, only
+by the way, that the type of the proper harmonious-equipotential
+system may go hand in hand with another<span class="pagenum" title="154"><a name="Page_154" id="Page_154"></a></span>
+type of “systems” which play a part in morphogenesis; a
+type which we have shortly mentioned already and which
+will be studied fully a few chapters later. We know that
+there are equipotential systems with complex potencies: that
+is to say, systems which may produce a whole organism
+equally well from any one of their elements; we know the
+cambium of Phanerogams to be such a system. Now it is
+easily understood that the germ of our Echinus, say in the
+stage of two or four or eight cleavage cells, is not only an
+harmonious-equipotential system, but a complex-equipotential
+system too. Not only may there arise a whole organism
+out of 2/4 or 3/4; or 3/8, 4/8, 5/8, 6/8, 7/8 of its elements, in which cases
+the harmonious rôle of the single element with regard to
+its single performance in a totality is variable, but there
+may also arise four whole single larvae out of the four cells
+of the four-cell stage, or eight single whole larvae out of the
+eight-cell <span class="nowrap">stage.<a name="FNanchor_67_67" id="FNanchor_67_67"></a><a href="#Footnote_67_67" class="fnanchor">67</a></span> In these cases, of course, each of the
+four or eight elements has performed not a part of the
+totality, changing with its “position,” but the totality
+itself. With respect to these possible performances the
+“systems” present in the four or eight-cell stages of cleavage
+must be called complex-equipotential ones.</p>
+
+<p>We propose to give the name of <em>mixed-equipotential
+systems</em> to all those equipotential systems which, at the
+same time, may be regarded as belonging to the harmonious
+or to the complex type. It is not only among cleavage-stages
+that they are to be found; you may also find them
+very clearly exhibited in our ascidian <i class="biological-name">Clavellina</i> for instance.<span class="pagenum" title="155"><a name="Page_155" id="Page_155"></a></span>
+We know already that the branchial apparatus of this form
+is typically harmonious-equipotential, but it is complex-equipotential
+too, for it also may regenerate what is wanting
+in the proper way, by a budding from the wound; and the
+same is true of many other cases, the flatworm <i class="biological-name">Planaria</i> for
+instance.</p>
+
+<p>Another type of systems, which might be said to be of
+a higher degree, is exhibited in some very strange phenomena
+of regeneration. It was first shown most clearly by some
+experiments of Godlewski’s that a whole tail may be
+regenerated from a wound inflicted on the body of a
+newt, even if this wound involves section of only a
+portion of the body-diameter. Section of the whole of the
+body-diameter of course would cause the formation of the
+whole tail also; but it was found that even an incomplete
+cross-section of the body is capable of performing the whole
+on a smaller scale. The series of possible cross-sections
+which are all capable of regeneration would have to be
+called a system of the complex type in this case; but,
+now we learn that every <em>single</em> cross-section is of the
+harmonious type, we must speak of <em>complex-harmonious
+systems</em>. What we have described is not the only instance
+of our new type of morphogenetic systems. Some
+other instances had been discovered a few years earlier,
+though nobody had pointed out their true significance.
+In the flatworm <i class="biological-name">Planaria</i> a partial cross-section is also
+capable of forming a whole structure, say a head, and
+all cases of so-called “super-regeneration” after the
+infliction of a complicated wound probably belong here
+also.</p>
+
+<p>You may say that our two additions to the theory of<span class="pagenum" title="156"><a name="Page_156" id="Page_156"></a></span>
+systems are merely formal, and indeed I am prepared to
+concede that we shall not learn anything altogether new
+from their discussion: their analysis would lead either to
+what was our “first proof” of the autonomy of life-phenomena
+or to what will be our “second” one. But the
+mere descriptions of the facts discovered here will interest
+you, I think, and will fill your minds with more vivid
+pictures of the various aspects of form-autonomy.</p>
+
+<p>While dealing with our harmonious-equipotential systems
+as the starting-points of processes of restitution, <i>e.g.</i> in
+<i class="biological-name">Tubularia</i>, <i class="biological-name">Clavellina</i>, the flatworms, and other instances,
+we always have regarded cross-sections of the body as
+constituting the elements of equipotentiality. Now cross-sections,
+of course, are by no means simple in themselves,
+but are made up of very different tissues, which are
+derivates of all three of the original germ layers&mdash;ectoderm,
+mesoderm, and endoderm. Owing to this composite
+character of the cross-sections, taken as elements of
+harmonious systems, a special phenomenon of morphogenesis
+is presented to us, which teaches somewhat more
+than the mere concept of harmonious-equipotentiality can
+express. If composite elements concerned in morphogenesis
+result in one whole organisation in spite of the
+development of the single tissues of these elements going
+on independently, then there must be a sort of correspondence
+or reciprocity of the harmonious development
+among these tissue constituents themselves; otherwise a
+proportionate form could not be the final result. We may
+conveniently speak of a <em>reciprocity of harmony</em> as existing
+between the single tissues or germ layers which constitute
+many harmonious-equipotential systems, and there can be<span class="pagenum" title="157"><a name="Page_157" id="Page_157"></a></span>
+little doubt that we have here an important feature with
+regard to general <span class="nowrap">morphogenesis.<a name="FNanchor_68_68" id="FNanchor_68_68"></a><a href="#Footnote_68_68" class="fnanchor">68</a></span></p>
+
+<p>A few other groups of morphogenetic facts may find
+their proper place here, though they are not properly to be
+regarded as additions to the theory of harmonious systems
+but as forming a sort of appendix to it.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE “MORPHAESTHESIA” OF NOLL</span><a name="FNanchor_69_69" id="FNanchor_69_69"></a><a href="#Footnote_69_69" class="fnanchor">69</a></p>
+
+<p>We may briefly mention that group of botanical
+phenomena, by which the botanist Noll has been led to
+the concept of what he calls “morphaesthesia,” or the
+“feeling” for form; a concept, the full discussion of which
+would lead to almost the same conclusions as our analysis
+of the harmonious systems has done. In the Siphoneae, a
+well-known order of marine algae with a very complicated
+organisation as to their exterior form, the protoplasm which
+contains the nuclei is in a constant state of circulation
+round the whole body, the latter not being divided by
+proper cell-walls. On account of this constant movement
+it is certainly impossible to refer morphogenetic localisation
+to definite performances of the nuclei. Nor can any sort<span class="pagenum" title="158"><a name="Page_158" id="Page_158"></a></span>
+of structure in the outer protoplasmic layer, which is fixed,
+be responsible for it, for there is no such structure there:
+hence there must be a sort of feeling on the part of the
+plant for its relative body localities, and on account of
+this feeling morphogenesis occurs. This “feeling” is styled
+“morphaesthesia” by Noll, and to it he tries to refer all
+sorts of different botanical <span class="nowrap">form-phenomena,<a name="FNanchor_70_70" id="FNanchor_70_70"></a><a href="#Footnote_70_70" class="fnanchor">70</a></span> for instance
+what is called “autotropism,” that is, the fact that branches
+of plants always try to reassume their proper angle with
+regard to their orientation on the main axis, if this orientation
+has been disturbed. It may be an open question if
+this particular application of the theory is right: certainly
+there seems to be much truth in the establishment of the
+concept of morphaesthesia, and we only have to object to
+its psychological name. But that may be done in a more
+general form on a later occasion.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">RESTITUTIONS OF THE SECOND ORDER</span></p>
+
+<p>In the hydroid polyp <i class="biological-name">Tubularia</i>, already familiar to us
+as being a most typical representative of the harmonious-equipotential
+systems, a very interesting phenomenon has
+been <span class="nowrap">discovered<a name="FNanchor_71_71" id="FNanchor_71_71"></a><a href="#Footnote_71_71" class="fnanchor">71</a></span>, almost unparalleled at present but nevertheless
+of a general importance, a phenomenon that we may
+call a restitution of a restitution, or a restitution of the
+second order. You know that the first appearance of the
+new head of <i class="biological-name">Tubularia</i>, after an operation, consists in the<span class="pagenum" title="159"><a name="Page_159" id="Page_159"></a></span>
+formation of two rings of red lines, inside the stem, these
+rings being the primordia of the new tentacles. I removed
+the terminal ring by a second operation soon after it had
+arisen, disturbing in this way the process of restitution
+itself: and then the process of restitution itself became
+regulated. The organism indeed changed its course of
+morphogenesis, which was serving the purposes of a
+restitution, in order to attain its purpose in spite of the
+new disturbance which had occurred. For instance, it sometimes
+formed two rings out of the one that was left to it,
+or it behaved in a different way. As this difference of
+morphogenetic procedure is a problem by itself, to be
+discussed farther on, we shall postpone a fuller description
+of this case of a restitution of the second degree.</p>
+
+<p>At present I do not see any way of proving independently
+the autonomy of life by a discussion of these phenomena;
+their analysis, I think, would again lead us to our problem
+of localisation and to nothing else; at least in such an
+exact form of reasoning as we demand.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON THE “EQUIFINALITY” OF RESTITUTIONS</span><a name="FNanchor_72_72" id="FNanchor_72_72"></a><a href="#Footnote_72_72" class="fnanchor">72</a></p>
+
+<p>I have told you already that <i class="biological-name">Tubularia</i> in the phenomena
+of the regulation of restitutions offers us a second
+problem of a great general importance, the problem of
+the <em>Equifinality of Restitutions</em>. There indeed may occur
+restitutions, starting from one and the same initial state and
+leading to one and the same end, but using very different
+means, following very different ways in the different
+individuals of one and the same species, taken from the
+same locality, or even colony.</p>
+
+<p><span class="pagenum" title="160"><a name="Page_160" id="Page_160"></a></span></p>
+
+<p>Imagine that you have a piece of paper before you and
+wish to sketch a landscape. After drawing for some time
+you notice that you have miscalculated the scale with
+regard to the size of the paper, and that it will not be
+possible to bring upon the paper the whole of the landscape
+you want. What then can you do? You either may
+finish what you have begun to draw, and may afterwards
+carefully join a new piece of paper to the original one and
+use that for the rest of the drawing; or you may rub out
+all you have drawn and begin drawing to a new scale; or
+lastly, instead of continuing as you began, or erasing
+altogether, you may compromise as best you can by drawing
+here, and erasing there, and so you may complete the
+sketch by changing a little, according to your fancy, the
+proportions as they exist in nature.</p>
+
+<p>This is precisely analogous to the behaviour of our
+<i class="biological-name">Tubularia</i>. <i class="biological-name">Tubularia</i> also may behave in three different
+ways, if, as I described to you, the terminal one of its two
+newly arisen rings of tentacle primordia is removed again.
+It may complete what is left, say the basal tentacle ring,
+then put forth from the horny skeleton (the “perisarc”) the
+new head as far as it is ready, and finally complete this
+head by a regular process of budding regeneration. But it
+also may behave differently. It may “erase” by a process
+of retro-differentiation all that has been left of what had
+already been formed, and then may form <i lang="la" xml:lang="la">de novo</i> the
+totality of the primordia of a new head. Or, lastly, it
+may remove a part of the middle of the one ring of tentacle
+rudiments which was left, and may use this one ring for
+the formation of two, which, of course, will not be quite in
+the normal relations of place with regard to each other and<span class="pagenum" title="161"><a name="Page_161" id="Page_161"></a></span>
+to the whole, but will be regulated afterwards by processes
+of growth. Thus, indeed, there is a sort of equifinality of
+restitution: one starting-point, one end, but three different
+means and ways.</p>
+
+<p>It would, of course, contradict the principle of univocality,
+as we shall see more fully later on, to assume
+that there actually are different ways of regulation whilst
+all the conditions and stimuli are the same. We are
+obliged to assume, on the contrary, that this is not the
+case, that there are certain differences in the constellation,
+say of the general conditions of age or of metabolism,
+which are responsible for any given individual choosing
+one process of restitution instead of another; but even then
+the phenomenon of equifinality remains very striking.</p>
+
+<p>It has long been known that restitution in general does
+not always follow the same lines of morphogenesis as
+are taken by ontogeny, and it was this feature that once
+led Roux to point out that the adult forms of organisms
+seem to be more constant than their modes of origin. But,
+comparing ontogeny with restitution in general, we see that
+only the ends are the same, not the points of starting;
+the latter are normal or non-typical in ontogeny, atypical in
+restitution. In the new discoveries of an equifinality of
+restitutions we have the <em>same</em> starting-point, which is
+decidedly non-typical but atypical, <i>i.e.</i> dependent on our
+arbitrary choice, leading by <em>different</em> ways always to the
+<em>same</em> end.</p>
+
+<p>There may be many who will regard the fact of
+equifinality as a proof of vitalism. I should not like
+to argue in this easy way; I indeed prefer to include
+part of the phenomena of equifinality in our first proof<span class="pagenum" title="162"><a name="Page_162" id="Page_162"></a></span>
+of autonomy, and part in the second one, which is to
+follow.</p>
+
+<p>Another important phenomenon of the equifinality of
+regulation was discovered by Morgan. A species of the
+flatworm <i class="biological-name">Planaria</i> was found to restore its totality out of
+small pieces either by regeneration proper, if the pieces
+were fed, or by a sort of rearrangement of material, on the
+basis of its harmonious-equipotentiality, if they were kept
+fasting. It is important to note that here we see one of
+the conditions determining the choice of the way to
+restoration, as we also do in the well-known equifinal
+restitutions of the root in plants, where the behaviour of
+the organism depends on the distance of the operation-wound
+from the <span class="nowrap">tip.<a name="FNanchor_73_73" id="FNanchor_73_73"></a><a href="#Footnote_73_73" class="fnanchor">73</a></span> In <i class="biological-name">Tubularia</i> the actual stage of restitution
+that has been already reached by the stem when the second
+operation takes place, may account for the specification of
+its future organogenesis, but this is not at all clearly
+ascertained at present.</p>
+
+<p><i class="biological-name">Clavellina</i> also shows equifinality in its restitution, as
+has already been shortly mentioned. The isolated branchial
+apparatus may restitute itself by retro-differentiation to an
+indifferent stage followed by renovation; or it may regenerate
+the intestine-sac in the proper way. Nothing is known
+here about the conditions, except perhaps that young individuals
+seem more apt to follow the first of these two
+ways, older ones the second; but there are exceptions to
+this rule.</p>
+
+<p>The discussion of other instances of equifinality, though<span class="pagenum" title="163"><a name="Page_163" id="Page_163"></a></span>
+important in themselves, would not disclose anything
+fundamentally new, and so we may close the subject with
+the remark that nothing can show better than the fact
+of the equifinality of restitutions how absolutely inadequate
+all our scientific conceptions are when confronted with the
+actual phenomena of life itself. By analysis we have found
+differences of potencies, according as they are simple or
+complex; by analysis we have found differences of “systems,”
+differences of means, and indeed we were glad to be able to
+formulate these differences as strictly as possible: but now
+we see how, in defiance of our discriminations, one and the
+same species of animals behaves now like one sort of our
+“systems,” and now like the other; how it uses now one
+sort of “potencies,” now another.</p>
+
+<p>But even if it is granted that, in the presence of such
+phenomena of life, our endeavour seems to be like a child’s
+play on the shores of the ocean, I do not see any other
+way for us to go, so long, at least, as our goal is human
+science&mdash;that is, a study of facts as demanded by our mental
+organisation.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">REMARKS ON “RETRO-DIFFERENTIATION”</span></p>
+
+<p>We shall finish this part of our studies by mentioning
+a little more explicitly one fundamental fact which has
+already entered incidentally into our considerations, viz.
+<em>retro-</em> or <em>back-differentiation</em>.<a name="FNanchor_74_74" id="FNanchor_74_74"></a><a href="#Footnote_74_74" class="fnanchor">74</a> We know that it occurs in
+<i class="biological-name">Clavellina</i> and in <i class="biological-name">Tubularia</i>; we may add that it also
+happens in <i class="biological-name">Hydra</i>, and that in the flatworm <i class="biological-name">Planaria</i> the
+pharynx, if it is too large for a piece that is cut out,<span class="pagenum" title="164"><a name="Page_164" id="Page_164"></a></span>
+may be differentiated back and be replaced by a new
+pharynx, which is smaller.</p>
+
+<p>It is not death and sloughing of parts that occurs in
+these <span class="nowrap">cases,<a name="FNanchor_75_75" id="FNanchor_75_75"></a><a href="#Footnote_75_75" class="fnanchor">75</a></span> but a real process of active morphogenesis; not,
+however, a process consisting in the production of visible
+manifoldness, but the opposite. Loeb was the first to lay
+much stress upon this topic, and indeed, there may appear a
+very strange problem in its wake: the problem, whether
+<em>all</em> morphogenesis might be capable perhaps of going
+backwards under certain conditions.</p>
+
+<p>It is important to note that in <span class="nowrap">most<a name="FNanchor_76_76" id="FNanchor_76_76"></a><a href="#Footnote_76_76" class="fnanchor">76</a></span> cases retro-differentiation
+occurs in the service of restitution: it goes
+on wherever restitution requires it. This fact alone would
+show that not very much could be explained here by the
+discovery of modern chemistry, important as it is, that one
+and the same “ferment” or “enzyme” may affect both the
+composition and the decomposition of the same compound.
+We could regard what is called “catalysis” solely as an
+agent in the service of entelechy. But this point also will
+become clearer in another part of the work.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="165"><a name="Page_165" id="Page_165"></a></span></p>
+
+
+
+<h3><i>C.</i> ADAPTATION</h3>
+
+<h4 class="fs120"><span class="smcap">Introductory Remarks on Regulations in General</span></h4>
+
+
+<p>We have finished our long account of individual morphogenesis
+proper. If we look back upon the way we have
+traversed, and upon those topics in particular which have
+yielded us the most important general results, the
+material for the higher analysis which is to follow, it
+must strike us, I think, that all these results relate to
+regulations. In fact, it is “secondary” form-regulations,
+according to our terminology, that we have been studying
+under the names of equifinality, back-differentiation,
+restitution of the second order, and so on, and our harmonious-equipotential
+systems have figured most largely in processes
+of secondary form-regulations also. But even where that
+has not been the case, as in the analysis of the potencies of
+the germ in development proper, form-regulations of the
+other type have been our subject, regulations of the primary
+or immanent kind, the connection of normal morphogenetic
+events being regulatory in itself. It was not the phenomenon
+of organic regulation as such that afforded us the
+possibility of establishing our proof of the autonomy of
+morphogenesis: that possibility was afforded us by the
+analysis of the distribution of potencies; but upon this<span class="pagenum" title="166"><a name="Page_166" id="Page_166"></a></span>
+distribution regulation is based, and thus we may be said
+to have studied some types of regulation more or less
+indirectly when analysing potencies.</p>
+
+<p>It therefore seems to me that we shall have hopes of a
+successful issue to our inquiries, if we now, on passing to
+what is called the physiology of the vegetative functions,
+proceed to focus our attention on the concept of regulation
+as such. And that is what we shall do: on our way
+through the whole field of physiology, we shall always stop
+at any occurrence that has any sort of regulatory aspect,
+and shall always ask ourselves what this feature has to
+teach us.</p>
+
+<p>But let us first try to give a proper definition of our
+concept. We shall understand by “regulation” any occurrence
+or group of occurrences on a living organism which takes
+place after any disturbance of its organisation or normal
+functional state, and which leads to a reappearance of this
+organisation or this state, or at least to a certain approach
+thereto. Organisation is disturbed by any actual removal
+of parts; the functional state may be altered by any change
+among the parts of the organism on the one hand, by any
+change of the conditions of the medium on the other; for
+physiological functioning is in permanent interaction with
+the medium. It is a consequence of what we have said
+that any removal of parts also changes the functional state
+of the organism, but nevertheless organisation is more than
+a mere sum of reactions in functional life. All regulations
+of disturbances of organisation may be called <em>restitutions</em>,
+while to regulations of functional disturbances we shall
+apply the name <em>adaptations</em>. It is with <em>adaptations</em> that we
+have to deal in the following.</p>
+
+<p><span class="pagenum" title="167"><a name="Page_167" id="Page_167"></a></span></p>
+
+<p>Let us begin our studies of adaptations in a field which
+may justly be called a connecting link between morphogenesis
+and physiology proper, not yet wholly separated from the
+science of the organic form, morphology.</p>
+
+<p><span class="pagenum" title="168"><a name="Page_168" id="Page_168"></a></span></p>
+
+
+<h4 class="fs120">1. <span class="smcap">Morphological Adaptation</span></h4>
+
+<p><i>Morphological adaptation</i> is a well-established fact, and
+I need only mention the striking differences between the
+land and water form of amphibious plants, or the differences
+between the same species of plants in the Alps and in the
+plains, or the very different aspect of the arms of an athlete
+and of an ascetic, to recall to your memory what is meant
+by this term.</p>
+
+<p>Morphological adaptation is no part of individual
+morphogenesis proper, but occurs at the end of it; at least
+it never occurs previous to the full individual life of an
+organism, previous to its true functional life; for it relates
+to the functions of the complete organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE LIMITS OF THE CONCEPT OF ADAPTATION</span></p>
+
+<p>It is especially, though by no means exclusively, among
+plants that morphological adaptation assumes its most
+marked forms; and this topic, indeed, may very easily be
+understood if we remember that plant-life is in the very
+closest permanent dependence on the medium, and that
+this medium is liable to many changes and variations of
+all kinds. In order to elucidate our problem, it therefore
+seems convenient to restrict our considerations for a while<span class="pagenum" title="169"><a name="Page_169" id="Page_169"></a></span>
+to the study of plants. There exist very many external
+formative stimuli in the morphogenesis of vegetation:
+would it then be possible to regard every effect of such
+an external formative stimulus as a real morphological
+adaptation? No; for that would not meet the point.
+The general <em>harmony</em> of form is indeed concerned if gravity
+forces roots to shoot forth below at a spot where they can
+enter the ground, or if light induces branches and leaves
+to originate at places where they can obtain it for assimilation;
+but gravity and light themselves are mere formative
+stimuli&mdash;of the localising type&mdash;in these instances, for
+they relate only to the individual production of form, not
+to the functioning of already existing form. We therefore
+are warned not to confuse the effects of formative stimuli
+from without with real adaptive effects until we have fully
+analysed the particular case.</p>
+
+<p>We have drawn a sharp line between causes and means
+of morphogenesis, applying the term “means” to those conditions
+of the morphogenetic process which relate neither to
+the specificity nor to the localisation of its constituents,
+though they are necessary for the accomplishment of the process
+in the most thorough manner. Would it be possible to
+connect our new concept of an adaptation with our well-established
+concept of a means of morphogenesis in such a
+way that we might speak of a morphological “adaptation”
+whenever any specific feature about morphogenesis proves
+to be immediately dependent for its success on some specific
+means, though it does not owe its localisation to that means
+as its “cause”? It seems to me that such a view would
+also fall wide of the mark. It is well known, for instance,
+that the flowers of many plants never fully develop in the<span class="pagenum" title="170"><a name="Page_170" id="Page_170"></a></span>
+dark; light is necessary for their morphogenesis. Is, therefore,
+their growth in the presence of light to be called a
+morphological “adaptation” to light? Certainly not: they
+simply <em>cannot</em> originate without light, because they require
+it for some reason. It is precisely here that our conception
+of light as a “means” of morphogenesis is most fully justified.
+There are <span class="nowrap">many<a name="FNanchor_77_77" id="FNanchor_77_77"></a><a href="#Footnote_77_77" class="fnanchor">77</a></span> such cases; and there are still
+others of an apparently different type, but proving the
+same. All pathological forms produced in plants by animal
+parasites or by parasitic fungi could hardly be called adaptations,
+but must be attributed to some abnormality of means
+or of stimuli. It may be that the organism reacts as well
+as possible in these cases, and that if it reacted otherwise
+it would die&mdash;we know absolutely nothing about this question.
+But even then there would only be some sort of
+regulation <em>in</em> the process of pathological morphogenesis, but
+<em>the process</em> itself could hardly be called adaptive.</p>
+
+<p>So far we have only learned what is not to be regarded as
+morphological adaptation. No response to external formative
+stimuli is in itself an example of adaptation, nor are
+processes dependent for their existence on any kind of
+condition or means to be called, simply because they are
+dependent on them, adaptations to those agents. What then,
+after all, is a morphological adaptation?</p>
+
+<p>Let us remember what the word adaptation is really to
+mean in our discussions: a state of functioning is adapted&mdash;<span class="pagenum" title="171"><a name="Page_171" id="Page_171"></a></span>a
+state of functioning must therefore have been disturbed;
+but as functioning itself, at least in plants, certainly stands
+in close relations to the medium, it follows that all adaptations
+are in the last resort connected with those factors of
+the medium which affect functioning. In being correctives
+to the disturbances of functioning they become correctives
+to the disturbing factors themselves.</p>
+
+<p>But again, the question seems to arise whether these
+factors of the medium, when they provoke an adaptation
+by some change that is followed by functional disturbance,
+do so in the capacity of “causes” or of “means,” and so
+it might seem that we have not gained very much so far
+by our analysis. The reproach, however, would not be quite
+justified, it seems to me: we indeed have gained a new
+sort of analytical concept, in the realm of causal concepts
+in general, by clearly stating the point that adaptations are
+related directly to functionality, and only indirectly, through
+functionality, to external changes. By the aid of this logical
+formulation we now are entitled to apply the term “cause,”
+in our restricted sense of the word, to every change of the
+medium which is followed by any sort of adaptation in
+regard <em>to itself</em>. Our definition stated that a “cause” is
+any one of the sum of necessary factors from without that
+accounts either for the localisation <em>or</em> for <em>the specification</em>
+of the effect, and the definition holds very well in this
+case. Indeed, the specification of the effect is determined
+<em>by</em> the outside factor in every case of an adaptation <em>to</em> it,
+by the mere <em>fact</em> of its being a specific adaptation to this
+specific factor.</p>
+
+<p>We must not forget that in this chapter we are not
+studying real individual morphogenesis as the realisation<span class="pagenum" title="172"><a name="Page_172" id="Page_172"></a></span>
+of what has been inherited, but that at present we regard
+morphogenesis proper as an accomplished fact. Morphogenesis
+proper has laid the general lines of organisation;
+and now adaptation during the functional life, so to speak,
+imposes a second kind of organisation upon the first. It
+is for that reason that the meaning of the word “cause”
+is now becoming a little different from what it was
+before.</p>
+
+<p>In order to study a little more in detail what has been
+discovered about morphological adaptation in animals and
+plants, let us separate our materials into two groups, one
+of them embracing adaptations with regard to functional
+changes from without, the other adaptations to those
+functional changes which come from the very nature of
+functioning. Almost all of our previous general considerations
+have applied to the former group, with which
+we shall now proceed to deal.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ADAPTATIONS TO FUNCTIONAL CHANGES FROM WITHOUT</span><a name="FNanchor_78_78" id="FNanchor_78_78"></a><a href="#Footnote_78_78" class="fnanchor">78</a></p>
+
+<p>The differences between plants grown in very dry air,
+very moist air, and water, respectively, are most distinctly
+seen in all the tissues that assist in what is called
+transpiration, that is, the exchange of water-vapour between
+the plant and the medium, but especially in the epidermis
+and the conductive fibres, both of which are much stronger
+in plants grown in the dry. Indeed, it seems from experiments
+that transpiration is the most essential factor
+to which “adaptation” occurs in amphibious plants, though<span class="pagenum" title="173"><a name="Page_173" id="Page_173"></a></span>
+the changes of the mechanical conditions according to the
+medium also seem to have some sort of structural effect.
+If plants stand very deeply in water, the conditions of
+illumination, so important for assimilation in plants, may
+have been altered, and therefore much of the structural
+change can be attributed also to them. It is unimportant
+in our general question what is due to one of these factors
+and what to the other. That there is a real sort of
+adaptation cannot be doubtful; and the same is true, as
+experimental observations of the last few years have shown,
+with regard to the structural differences between so-called
+sun-leaves and shade-leaves of plants grown in the air:
+it has been actually shown here that the functional life
+of the former goes on better in the sun, of the latter better
+in the shade.</p>
+
+<p>It is very important to emphasise this point, as the
+adaptive character of all sorts of structural differences in
+plants dependent on light and on moisture has lately been
+denied, on the supposition that there is only a stopping of
+organogenesis in the case of the more simple, a continuance
+in the case of the more complicated modification, but
+nothing else. Indeed, all morphological adaptation has
+been conceived as only consisting in differences dependent
+upon the absence or the presence of necessary means or
+causes of development, and as offering no problem of its
+own. We have gained the right position from which to
+oppose this argument, it seems to me, in our formula that
+all adaptations do relate <em>not</em> directly <em>to</em> the agents of the
+medium, but to changes of functional states induced <em>by</em>
+those agents; that adaptations only <em>are</em> “adaptations” by
+being correctives to the functional state.</p>
+
+<p><span class="pagenum" title="174"><a name="Page_174" id="Page_174"></a></span></p>
+
+<p>There simply <em>is</em> an “adaptation” of structure in <em>such</em>
+a sense in all the cases we have mentioned. We can say
+neither more nor less. Granted that one of the outside
+factors which comes into account is merely a necessary
+“means”: then why is the histological consequence of the
+presence of the means an actual adaptation to it as far
+as its relation to functioning is concerned&mdash;why is the
+consequence of its absence also an adaptation to this absence
+in its relation to functioning? Why, to complete the series,
+is the degree of the consequence of its presence an adaptation
+to the degree of its presence?</p>
+
+<p>All these relationships, which are so many facts, have
+been absolutely overlooked by those who have been pleased
+to deny morphological adaptation to functional changes
+from without.</p>
+
+<p>To do full justice to them we may speak of “primary”
+regulative adaptations in all the cases mentioned above,
+applying the word “primary,” just as was done with regard
+to restitutions, to the fact that there is some sort of
+regulation <em>in</em> the normal connection of processes. We
+reserve the title of “secondary adaptations” for cases such
+as those described, for instance, by <span class="nowrap">Vöchting,<a name="FNanchor_79_79" id="FNanchor_79_79"></a><a href="#Footnote_79_79" class="fnanchor">79</a></span> where not
+merely one and the same tissue originates adaptively with
+regard to the degree of its normal functioning, but where<span class="pagenum" title="175"><a name="Page_175" id="Page_175"></a></span>
+a profound disturbance of all functioning connections, due
+to the removal of portions of the organisation, is followed
+by histological changes at absolutely abnormal localities;
+that is, where a real change of the <em>kind</em> of functioning is
+the consequence of the adaptation. It, of course, will be
+found very difficult to discriminate such phenomena from
+real restitutions, though logically there exists a very sharp
+line between them.</p>
+
+<p>A few more concrete instances may now close this
+account of adaptation to functional changes coming from
+without. Though almost all the adaptive characters in
+the aquatic forms of amphibious plants represent a less
+complicated state of organisation than the corresponding
+structures in their terrestrial forms, and therefore have
+wrongly been regarded as simply due to a stopping of
+morphogenesis for want of necessary means, yet there are
+a few of them that are positive complications in comparison
+with the land-forms: the so-called aërenchyme, especially
+well developed in the water-form of <i class="biological-name">Jussiaea</i> is such an
+instance. This tissue stands in the direct service of
+respiration, which is more difficult to be accomplished under
+water than ordinarily, and represents a true adaptation to
+the altered function.</p>
+
+<p>Among animals there is only one well-studied instance
+of our first type of adaptive morphological characters.
+<i class="biological-name">Salamandra atra</i>, the black salamander, a species which only
+inhabits regions at least two thousand feet above sea-level,
+does not bring forth its young until metamorphosis has
+taken place. The larvae, however, may be removed from
+the mother’s body at an earlier stage and forced to complete
+their development in water. Under these circumstances,<span class="pagenum" title="176"><a name="Page_176" id="Page_176"></a></span>
+as was shown in an excellent memoir by <span class="nowrap">Kammerer,<a name="FNanchor_80_80" id="FNanchor_80_80"></a><a href="#Footnote_80_80" class="fnanchor">80</a></span> they
+will change the whole histological type of their gills and
+skin in order to meet the new functional conditions.
+The change of the conditions of functioning is very severe
+here, for whereas the gills had served for nutrition and
+respiration in the uterus&mdash;by a process of endosmosis&mdash;they
+now serve for respiration only, and, of course, are
+surrounded by quite an abnormal chemical medium.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">TRUE FUNCTIONAL ADAPTATION</span><a name="FNanchor_81_81" id="FNanchor_81_81"></a><a href="#Footnote_81_81" class="fnanchor">81</a></p>
+
+<p>But all other cases of morphological adaptation among
+animals, and several in the vegetable kingdom too, belong
+to our second group of these phenomena, which in our
+analytical discussion we have called adaptations to functional
+changes that result from the very nature of functioning,
+and which we shall now call by their ordinary name,
+“functional adaptation.”</p>
+
+<p>It was Roux who first saw the importance of this kind
+of organic regulation and thought it well to give it a distinguishing
+name. <em>By functioning the organisation of organic
+tissues becomes better adapted for functioning.</em> These words
+describe better than any others what happens. It is well
+known that the muscles get stronger and stronger the more
+they are used, and that the same holds for glands, for
+connective tissue, etc. But in these cases only quantitative
+changes come into account. We meet with functional
+adaptations of a much more complicated and important<span class="pagenum" title="177"><a name="Page_177" id="Page_177"></a></span>
+kind, when for instance, as shown by <span class="nowrap">Babák,<a name="FNanchor_82_82" id="FNanchor_82_82"></a><a href="#Footnote_82_82" class="fnanchor">82</a></span> the intestine
+of tadpoles changes enormously in length and thickness
+according as they receive animal or vegetable food, being
+nearly twice as long in the second case. Besides this the
+so-called mechanical adaptations are of the greatest interest.</p>
+
+<p>It has long been known, especially from the discoveries
+of Schwendener, Julius Wolff, and Roux, that all tissues
+whose function it is to resist mechanical pressure or
+mechanical tension possess a minute histological structure
+specially suitable to their requirements. This is most
+markedly exhibited in the stem of plants, in the tail of the
+dolphin, in the arrangements of the lime lamellae in all
+bones of vertebrates. All these structures, indeed, are such
+as an engineer would have made them who knew the sort
+of mechanical conditions they would be called upon to
+encounter. Of course all these sorts of mechanically
+adapted structures are far from being “mechanically explained,”
+as the verbal expression might perhaps be taken
+to indicate, and as indeed has sometimes been the opinion
+of uncritical authors. The structures exist <em>for</em> mechanics,
+not <em>by</em> it. And, on the other hand, all these structures,
+which we have called mechanically “adapted” ones, are far
+from being mechanical “adaptations,” in our meaning of the
+word, simply because they are “adapted.” Many of them
+indeed exist previous to any functioning, they are for the
+most part truly inherited, if for once we may make use of
+that ambiguous word.</p>
+
+<p>But, the merely descriptive facts of mechanical adapted<span class="pagenum" title="178"><a name="Page_178" id="Page_178"></a></span>ness
+having been ascertained, there have now been discovered
+real mechanical processes of adaptations also. They occur
+among the statical tissues of plants, though not in that very
+high degree which sometimes has been assumed to exist;
+they also occur in a very high perfection in the connective
+tissue, in the muscles and in the bone tissue of vertebrates.
+Here indeed it has proved possible to change the specific
+structure of the tissue by changing the mechanical conditions
+which were to be withstood, and it is in cases of healing
+of broken bones that these phenomena have acquired
+a very great importance, both theoretically and practically:
+the new joints also, which may arise by force of circumstances,
+correspond mechanically to their newly created mechanical
+function.</p>
+
+<p>So far a short review of the facts of “functionelle
+Anpassung.” They seem to prove that there does exist a
+morphological adaptation to functional changes which result
+from the very nature of functioning. In fact, the actual
+state of all functioning tissue, the intensity of its state of
+existence, if you care to say so, may be said to be due
+to the functioning itself: the so-called atrophy by inactivity
+being only one extreme of a very long line of
+<span class="nowrap">correspondences.<a name="FNanchor_83_83" id="FNanchor_83_83"></a><a href="#Footnote_83_83" class="fnanchor">83</a></span></p>
+
+<p>We now, of course, have to ask ourselves if any more
+intimate analysis of these facts is possible, and indeed we
+easily discover that here also, as in the first of our groups of
+morphological adaptations, there are always single definite
+agents of the medium, which might be called “causes” or
+“means” of the adaptive effects, the word “medium” being<span class="pagenum" title="179"><a name="Page_179" id="Page_179"></a></span>
+taken as embracing everything that is external to the
+reacting cells. But of course also here the demonstration
+of single formative agents does not detract in the least from
+the adaptive character of the reaction itself. So we may
+say, perhaps, that localised pressure is the formative stimulus
+for the secretion of skeleton substance at a particular point
+of the bone tissue, or of the fibres of the connective tissue;
+the merely quantitative adaptations of muscles might even
+allow of a still more simple <span class="nowrap">explanation.<a name="FNanchor_84_84" id="FNanchor_84_84"></a><a href="#Footnote_84_84" class="fnanchor">84</a></span> But adaptations
+remain adaptations in spite of that; even if they only
+deserve the name of “primary” regulations.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THEORETICAL CONCLUSIONS</span></p>
+
+<p>We have stated in the analytical introduction to this
+chapter and elsewhere, that functional changes, which lead
+to morphological adaptations of both of our groups, may
+arise not only from changes of factors in the medium, but
+also from a removal of parts. As such removal is generally
+followed by restitution also, it is clear that restitutions and
+adaptations very often may go hand in hand, as is most
+strikingly shown in a fine series of experiments carried out
+by Vöchting, which we have already alluded to. Here again
+I should like to lay the greatest stress upon the fact that,
+in spite of such actual connections, restitutions and adaptations
+always have been separated from another theoretically,
+and that the forms are never to be resolved into sums of
+the latter. Such a view has been advocated by some recent<span class="pagenum" title="180"><a name="Page_180" id="Page_180"></a></span>
+authors, especially by Klebs, Holmes, and <span class="nowrap">Child:<a name="FNanchor_85_85" id="FNanchor_85_85"></a><a href="#Footnote_85_85" class="fnanchor">85</a></span> it is
+refuted I think by the simple fact that the first phase of
+every process of restitution, be it regeneration proper or
+be it a sort of harmonious differentiation, goes on without
+functioning at all, and only <em>for</em> future <span class="nowrap">functioning.<a name="FNanchor_86_86" id="FNanchor_86_86"></a><a href="#Footnote_86_86" class="fnanchor">86</a></span></p>
+
+<p>And there has been advocated still another view in
+order to amplify the sphere of adaptation: all individual
+morphogenesis, not only restitution, is adaptation, it has
+been said. In its strictest form such an opinion of course
+would simply be nonsense: even specific adaptive structures,
+such as those of bones, we have seen to originate in ontogeny
+previous to all specific functions, though for the help of
+them, to say nothing of the processes of the mere outlining
+of organisation during cleavage and gastrulation. But they
+are “inherited” adaptations, it has been answered to such
+objections. To this remark we shall reply in another chapter.
+It is enough to state at present that there <em>is</em> a certain kind
+of, so to speak, architectonic morphogenesis, both typical and
+restitutive, previous to specific functioning altogether.</p>
+
+<p>If now we try to resume the most general results from
+the whole field of morphological adaptations, with the
+special purpose of obtaining new material for our further<span class="pagenum" title="181"><a name="Page_181" id="Page_181"></a></span>
+philosophical analysis, we have reluctantly to confess that,
+at present at least, it does not seem possible to gather any
+new real proof of life-autonomy, of “vitalism,” from these
+facts, though of course also no proof against it.</p>
+
+<p>We have stated that there is in every case of both our
+types of adaptive events a correspondence between the
+degree of the factor to which adaptation occurs, and the
+degree of the adaptive effect. We here may speak of an
+<em>answering</em> between cause and effect with regard to adaptation,
+and so perhaps it may seem as if the concept of an
+“answering reaction” (“Antwortsreaktion”), which was
+introduced into science by <span class="nowrap">Goltz<a name="FNanchor_87_87" id="FNanchor_87_87"></a><a href="#Footnote_87_87" class="fnanchor">87</a></span> and which is to play
+a great part in our discussions of next summer, may come
+into account: but in our present cases “answering” only
+exists between a simple cause and a simple effect and relates
+almost only to quantity and locality. There is therefore
+lacking the most important feature, which, as will be seen,
+would have made the new concept of value.</p>
+
+<p>We only, I believe, can state the fact that there <em>are</em>
+relations between morphogenetic causes and effects which
+<em>are</em> adaptations, that functional disturbances or changes are
+followed by single histogenetic reactions from the organism,
+which are compensations of its disturbed or changed
+functional state. We are speaking of facts here, of very
+strange ones indeed. But I feel unable to formulate a real
+proof against all sorts of mechanism out of these facts:
+there <em>might</em> be a machine, to which all is due in a pre-established
+way. Of course we should hardly regard such
+a machine as very probable, after we have seen that it<span class="pagenum" title="182"><a name="Page_182" id="Page_182"></a></span>
+<em>cannot</em> exist in other fields of morphogenesis. But we are
+searching for a new and independent proof; and that is
+indeed not to be found <span class="nowrap">here.<a name="FNanchor_88_88" id="FNanchor_88_88"></a><a href="#Footnote_88_88" class="fnanchor">88</a></span></p>
+
+<p>At present it must be taken as one of the fundamental
+<em>facts</em> of the organogenetic harmony, that the cells
+of functioning tissues do possess the faculty of reacting to
+factors which have changed the state of functioning, in a
+way which normalises this state histologically. And it is
+a fact also that even cells, which are not yet functioning
+but are in the so-called embryonic or indifferent condition
+contributing to the physiological completion of the tissue,
+react to factors embracing new functional conditions of the
+whole in a manner which leads to an adaptation of that
+whole to those conditions.</p>
+
+<p>This is a very important point in almost all morphological
+adaptation, whether corresponding to functional changes
+from without or resulting from the very nature of functioning.
+In fact, such cells as have already finished their
+histogenesis are, as a rule, only capable of changing their
+size adaptively, but are not able to divide into daughter-cells
+or to change their histological qualities fundamentally;
+in technical terms, they can only assist “hypertrophy” but
+not “hyperplasia.” Any adaptive change of a tissue therefore,
+that implies an increase in the number of cellular
+elements or a real process of histogenesis, has to start from
+“indifferent” cells, that is to say, cells that are <em>not yet</em>
+functioning in the form that is typical of the tissue in
+question; and, strange to say, these “embryonic” cells&mdash;<span class="pagenum" title="183"><a name="Page_183" id="Page_183"></a></span><i>i.e.</i>
+the “cambium” in higher plants and many kinds of
+cells in animals&mdash;<em>can</em> do what the functional state requires.
+It is to be hoped that future investigations will lay a
+greater stress upon this very important feature of all
+adaptation.</p>
+
+<p><span class="pagenum" title="184"><a name="Page_184" id="Page_184"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Physiological Adaptation</span><a name="FNanchor_89_89" id="FNanchor_89_89"></a><a href="#Footnote_89_89" class="fnanchor">89</a></h4>
+
+<p>It is but a step from morphological adaptations to
+adaptations in physiology proper. The only difference
+between regulations of the first type and those which occur
+in mere functioning is, that the resulting products of the
+regulation are of definite shape and therefore distinctly
+visible in the first case, while they are not distinctly visible
+as formed materials but are merely marked by changes in
+chemical or physical composition in the latter.</p>
+
+<p>Metabolism, it must never be forgotten, is the general
+scheme within which all the processes of life in a given
+living organism go on; but metabolism means nothing
+else, at least if we use the word in its descriptive and
+unpretentious meaning, than change in the physical or
+chemical characteristics of the single constituents of that
+organism. In saying this, we affirm nothing about the
+physical or chemical nature of the actual processes leading to
+those physical or chemical characteristics, and by no means<span class="pagenum" title="185"><a name="Page_185" id="Page_185"></a></span>
+are these “processes” <i lang="la" xml:lang="la">a priori</i> regarded as being physical
+or chemical <em>themselves</em>: indeed, we have learned that in one
+large field, in the differentiation of our harmonious systems
+they certainly are not. Now, if the metabolism does not
+end in any change of visible form, then true physiological
+processes, or more particularly physiological regulations, are
+going on before us. But we are dealing with morphogenetic
+events or regulations, if the result of metabolism is marked
+by any change in the constituents of form. This however
+may depend on rather secondary differences as to the nature
+of regulation itself, and any kind of metabolism may really
+be of the regulatory type, whether we actually see its result
+as a constituent of form, <i>e.g.</i> owing to the production of
+some insoluble compound, or whether we do not.</p>
+
+<p>I do not mean to say that these are the only differences
+between mere physiological activities or regulations and
+organogenesis proper, as an originating of typical form-combination;
+but if we regard, as we do in this chapter,
+the given organisation of a living being as a substratum
+of its functional life, morphological and physiological
+adaptations are indeed of almost the same logical order.</p>
+
+<p>We had best therefore begin our discussions with a
+recapitulation of our problem. We are studying adaptations
+in functioning&mdash;that means we want to know how the
+organism behaves with regard to any change which may
+take place in its functional state. We apply the term
+regulation, or in particular adaptation, to any kind of
+reaction on the part of the organism which re-establishes
+the normal state of functioning, and we now want to learn
+to what degree such adaptations exist in the field of
+physiology.</p>
+
+<p><span class="pagenum" title="186"><a name="Page_186" id="Page_186"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">SPECIFIC ADAPTEDNESS <em>NOT</em> “ADAPTATION”</span></p>
+
+<p>It is important to keep well in mind our strictly
+formulated theme, as by doing so we shall be able to
+exclude at once from our materials a large group of
+phenomena which occasionally have been called regulations
+by physiological authors, but which, in fact, are not of the
+adaptation type and therefore cannot be said to afford those
+problems which possibly might have been expected. Typical
+peculiarities in functional life cannot be called “regulations”
+for this very reason. If, for instance, the organism selects
+specific amounts of specific kinds of organic food or of salts
+out of the combinations of salts or organic food normally
+offered to it in the medium, as indeed is most typically
+shown for instance by the roots of plants, there cannot be
+said to occur a “regulation” or “adaptation” with regard
+to the permeability of the cell, nor is it strictly a case of
+“regulation,” if so-called selective qualities are discovered in
+the processes of secretion, say of the epithelium of the kidney.</p>
+
+<p>All these facts are typical and specific peculiarities in
+functioning which are duly to be expected, where a very
+typical and specific organisation of the most elaborated kind
+exists. Indeed, after studying such an organisation we
+must not be astonished that functions in organisms follow
+lines which certainly they would not have taken without it.
+Take the fact which is quoted very often, that the migration
+of compounds or of ions in the organisms can happen
+quite contrary to all the laws of osmosis, from the less
+concentrated to the more concentrated side of a so-called
+“membrane.” There <em>is</em> no simple “membrane” in the
+organism, but a complicated organisation of an almost<span class="pagenum" title="187"><a name="Page_187" id="Page_187"></a></span>
+unknown character takes its place, and nothing, indeed, is
+against the assumption that this organisation may include
+factors which actually drive ions or compounds to the side
+of higher concentration, which indeed drive them by “doing
+work,” if we like to speak in terms of energy; and these
+factors included in organisation may very well be of a true
+physical or chemical <span class="nowrap">nature.<a name="FNanchor_90_90" id="FNanchor_90_90"></a><a href="#Footnote_90_90" class="fnanchor">90</a></span></p>
+
+<p>I lay great stress upon these statements, as I should like
+to be as careful as possible in the admission of anything
+like a “proof” of vitalism. It was want of scientific
+criticism and rigid logic that discredited the old vitalism;
+we must render our work as difficult as possible to ourselves,
+we must hold the so-called “machine theory” of life
+as long as possible, we must hold it until we are really
+forced to give it up.</p>
+
+<p>In a more general form we now can sum up our
+discussion by saying: There never are adaptations in
+physiology, requiring any special analysis, where there are
+only complications or even apparent deviations from the
+purely physico-chemical type of events which are, so to
+say, statical, <i>i.e.</i> fixed in quantity or quality, however
+peculiar or typically complicated they may be; all such
+peculiarities indeed, may properly be called “adapted,” that
+is to say, very well fitted to perform a specific part in
+the service of normal general functioning, and they are
+“adapted” to their part by virtue of a certain “adaptedness”
+of the organisation; but they are not “adaptations”
+in any sense of the word.</p>
+
+<p><span class="pagenum" title="188"><a name="Page_188" id="Page_188"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">PRIMARY AND SECONDARY ADAPTATIONS IN PHYSIOLOGY</span></p>
+
+<p>We approach the subject of true adaptations, that is, of
+adapting processes, as soon as any kind of variation in
+functioning occurs which corresponds to a variation of any
+factor of the medium in the widest sense. But even here
+our work is by no means done by simply showing such a
+correspondence of outer and inner variations. We know
+very well already, from our former studies, that now we are
+faced by a further problem, that we are faced by the
+question whether we have to deal with simple primary
+kinds of adaptations or with the far more important
+secondary ones.</p>
+
+<p>As the discrimination between primary and secondary
+regulations proves indeed to be of first-rate importance, you
+will allow me, I hope, to summarise our chief analytical
+statements regarding them in a most general form. We call
+primary regulatory any kind of morphogenetic or functional
+performance, which, by its very intimate nature, always
+serves to keep the whole of organisation or of functions in
+its normal state. We call secondary regulations all features
+in the whole of morphogenesis or of functioning which serve
+to re-establish the normal state after disturbances along lines
+which are outside the realm of so-called normality. This
+analytical discrimination will help us very much to a proper
+understanding of physiology. But before we turn to apply
+our definitions to actual facts, another preliminary problem
+has to be solved.</p>
+
+<p><span class="pagenum" title="189"><a name="Page_189" id="Page_189"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN PRE-REQUISITES OF ADAPTATIONS IN GENERAL</span></p>
+
+<p>We are thinking of the general and important question,
+what types of adaptations may be expected in the field of
+physiology and whether there may be certain classes of
+regulatory events which possibly might be expected to occur
+in the organism on <i lang="la" xml:lang="la">a priori</i> grounds, but which, nevertheless,
+are to be regarded as impossible after a more
+intimate analysis of its nature, even at the very beginning?
+Or, in other words, to what kinds of changes of the medium
+will an organism be found able or unable to adapt itself?</p>
+
+<p>We know that the <em>state of functioning</em> must be altered
+in order to call forth any sort of adaptation at all. Now,
+there can be no doubt that <i lang="la" xml:lang="la">a priori</i> it would seem to be
+very useful for the organism, if it never would let enter into
+its blood, lymph, etc., be it through the skin or through the
+intestine, any chemical compound that would prove to be a
+poison afterwards. In fact, a man, judging on the principle
+of the general usefulness of all the phenomena of the living,
+might suppose that there would exist a sort of adaptation
+against all poisons to the extent that they would never be
+allowed to enter the real interior of the body. We know
+that such reasoning would be incorrect. But we also can
+understand, I suppose, that an <i lang="la" xml:lang="la">a priori</i> analysis of a more
+careful kind would have reasoned differently. How could
+the functional state of the organism be changed, and how,
+therefore, could adaptation be called forth by any factor of
+the medium which had not yet entered the organism, but
+was only about to enter it? Not at all therefore is such a
+regulation to be expected as we have sketched; if there is
+to be any adaptation to poisons, it only can occur after the<span class="pagenum" title="190"><a name="Page_190" id="Page_190"></a></span>
+poison has really acted in some way, and in this case we
+shall indeed find regulations.</p>
+
+<p>You may perhaps regard this discussion as a little
+too academical and hair-splitting, but here again it was
+for the sake of ensuring a perfectly sound foundation of
+our chief principles that I undertook it. Very often, indeed,
+the question has been raised by the defenders of a mechanistic
+theory of life, Why then did the organisms not reject all
+poisons from the very beginning? We now may reply to
+that only&mdash;how <em>could</em> they do so? How could they “know”
+what is a poison and what is not, unless they had experienced
+it?&mdash;if we are allowed for a moment to use very anthropomorphistic
+language.</p>
+
+<p>We repeat, therefore, that the functional conditions of
+the organism must have been actually changed in order
+that an adaptation may occur. Nothing is more essential
+to a clear understanding of our problems than to keep
+fully in mind the exact sense of this definition.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN GROUPS OF PRIMARY PHYSIOLOGICAL ADAPTATIONS</span></p>
+
+<p><i>General Remarks on Irritability.</i>&mdash;Turning now to more
+special groups of problems concerning physiological adaptations,
+let us begin with the primary class of them, and let
+us first say a few words on a subject which occasionally
+has been regarded as the basis of physiological regulation
+in general. I refer to a most important fact in the general
+physiology of irritability. Irritability of any kind is known
+to be re-established, after it has been disturbed by the
+process of reacting to the stimulus, and in certain cases,
+in which two different&mdash;or rather two opposite&mdash;kinds<span class="pagenum" title="191"><a name="Page_191" id="Page_191"></a></span>
+of reactions are possible on the same substratum, which
+increase with regard to one process whilst decreasing at
+the same time with regard to the other. The irritability
+of the muscle or of the leaves of <i class="biological-name">Mimosa</i> is a very
+good instance of the first case, whilst the second more
+complicated one cannot be illustrated better than by what
+all experience has taught us about the irritability of the
+retina. The retina is more irritable by green rays and less
+by red ones the more it has been stimulated by the latter,
+and more sensitive to light in general the more it has been
+exposed to darkness; and something very similar is true,
+for instance, as regards phototactic irritability in plants, all
+these phenomena being in relation to the so-called law of
+<span class="nowrap">Weber.<a name="FNanchor_91_91" id="FNanchor_91_91"></a><a href="#Footnote_91_91" class="fnanchor">91</a></span></p>
+
+<p>It seems to me that there would be little difficulty in
+harmonising the phenomenon of the inversion of irritability
+with the so-called principle of the “action of masses”
+and with the laws of certain “reversible” processes well
+known in chemistry. As to the simple fact of the re-<span class="pagenum" title="192"><a name="Page_192" id="Page_192"></a></span>establishment
+of irritability after stimulation has occurred,
+or, in certain other cases, the fact that in spite of permanent
+stimulation irritability seems to exist permanently also,
+physical analogies or even explanations might very well
+be <span class="nowrap">found.<a name="FNanchor_92_92" id="FNanchor_92_92"></a><a href="#Footnote_92_92" class="fnanchor">92</a></span></p>
+
+<p>If now we ask whether there is anything like an adaptation
+appearing in the general characteristics of irritation
+and irritability, it seems to me that we may answer the
+question in an affirmative manner, as far as primary regulation
+comes into account. We, certainly, have not studied
+any abnormal regulatory lines of general functioning, we
+only have studied general functioning itself; but, indeed,
+there was a certain sort of regulation <em>in</em> functioning. Of
+course, by showing that one of the most general features of
+all functioning is primary-regulatory in itself, we do not
+deny the possibility of many specific functions in which
+real secondary regulations actually do exist. Nothing
+indeed is asserted about the <em>specific</em> character of functioning
+in its different types, by proving that one of the <em>general</em>
+features of <em>all</em> functioning may comparatively easily be<span class="pagenum" title="193"><a name="Page_193" id="Page_193"></a></span>
+understood. It seems to me that this important logical
+point has not always received the attention it deserved.</p>
+
+<p><i>The Regulation of Heat Production.</i><a name="FNanchor_93_93" id="FNanchor_93_93"></a><a href="#Footnote_93_93" class="fnanchor">93</a>&mdash;Having finished
+our introductory remarks we now turn to the proper
+study of special physiological functioning with regard to
+its adaptive side, and begin with the most simple cases.</p>
+
+<p>The so-called “regulation of heat” in warm-blooded
+vertebrates is an instance of a special function which can
+be said to be regulatory in itself. There exists a normal
+blood heat for each species, which is maintained no matter
+whether the temperature of the medium rise or fall. It
+might seem at first as if in this case there were a little
+more of an adaptive regulation than only its well-known
+primary type; no reversion, one might say, of the direction
+of one and the same process occurs in the regulation of heat
+production, but one kind of process is called into action
+if it is necessary to raise the temperature, and another
+whenever it is necessary to lower it. Even in the dilatation
+and constriction of capillary vessels there are different
+nerves serving for each operation respectively, and far more
+important are the increasing of transpiration for cooling, the
+increasing of combustion for heating&mdash;two radically different
+processes. But, nevertheless, there is a certain unity in
+these processes, in so far as a specific locality of the brain
+has been proved to be the “centre” of them all; it is to
+this centre of course that the analysis of heat production
+considered as a kind of regulation or adaptation must be
+directed. Such an ultimate analysis, it seems to me, would
+have to classify heat regulation under the primary type of<span class="pagenum" title="194"><a name="Page_194" id="Page_194"></a></span>
+adaptations in physiology without any restriction. The
+centre acts in one sense or in the other, if stimulated by any
+temperature beyond a very limited range, and it is in the
+action of the centre that the “regulation” of heat <span class="nowrap">consists.<a name="FNanchor_94_94" id="FNanchor_94_94"></a><a href="#Footnote_94_94" class="fnanchor">94</a></span></p>
+
+<p><i>Primary Regulations in the Transport of Materials and
+Certain Phenomena of Osmotic Pressure.</i>&mdash;Very similar
+phenomena of regulation are present in many processes
+concerned in the whole of metabolism. Let us consider
+for a moment the migration of materials in plants. Whenever
+any compound is used at a certain place, a permanent
+afflux of this compound to that place sets in from
+all possible directions. No doubt this is a “regulation,”
+but it is also the function itself, and besides that, a very
+simple function based almost entirely on well-known laws
+of physical chemistry. And in other cases, as in the ascent
+of water to the highest tops of our trees, which purely
+physical forces are said to be insufficient to explain, we can
+appeal to the unknown organisation of many cells, and there
+is nothing to prevent our attributing to these cells certain
+functions which are, if you like to say so, regulatory in
+themselves. Among other facts of so-called regulations
+there is the stopping of metabolic processes by an accumulation
+of their products: as, for instance, the transformation of
+starch into sugar is stopped, if the sugar is not carried
+away. Of course that is a regulation, but it again is an
+intrinsic one, and it is one of the characteristics of reversible
+chemical processes to be stopped in that way. I know very
+well that in this particular case a certain complication is<span class="pagenum" title="195"><a name="Page_195" id="Page_195"></a></span>
+added by the fact that it is a so-called ferment, the diastase,
+which promotes the transformation of starch into cane-sugar,
+and that this ferment is actively produced by the organism:
+but even its production would not prove that any real kind
+of secondary regulation exists here, if nothing more were
+known about such an active production than this single
+case.</p>
+
+<p>In a special series of experiments almost all carried out
+in Wilhelm Pfeffer’s botanical laboratory at Leipzig, an
+attempt has been made to discover in what manner the cells
+of plants are able to withstand very high abnormalities of
+the osmotic pressure of the medium&mdash;that is to say, very
+great changes in the amount of its salinity. That many,
+particularly the lower plants, are able to stand such changes
+had been ascertained already by the careful examinations of
+Eschenhagen; but recent years have given us a more profound
+insight into what happens. Von <span class="nowrap">Mayenburg<a name="FNanchor_95_95" id="FNanchor_95_95"></a><a href="#Footnote_95_95" class="fnanchor">95</a></span> has
+found that sundry of the species of <i class="biological-name">Aspergillus</i>, the common
+mould, are able to live in very highly concentrated solutions
+of several salts (KNO<sub>3</sub> and Na<sub>2</sub>SO<sub>4</sub>). They were found to
+regulate their osmotic pressure not by taking in the salts
+themselves, but by raising the osmotic pressure of their own
+cell sap, producing a certain amount of osmotically active
+substances, probably carbohydrates. If in this case it were
+possible to assume that the osmotic pressure of the medium
+were the real stimulus for the production of the osmotic
+substances in the cell, stimulus and production both
+corresponding in their degree, we should be entitled to
+speak of a primary though <span class="nowrap">physiological<a name="FNanchor_96_96" id="FNanchor_96_96"></a><a href="#Footnote_96_96" class="fnanchor">96</a></span> regulation only;<span class="pagenum" title="196"><a name="Page_196" id="Page_196"></a></span>
+and it seems to me that despite the discoveries of Nathansohn
+that certain algae and cells of higher plants are
+able to change the permeability of their surfaces in a
+way which regulates the distribution of single salts or
+ions in the sap of their cells without any regard to pure
+osmotic equilibrium, such a simple explanation might be
+<span class="nowrap">possible.<a name="FNanchor_97_97" id="FNanchor_97_97"></a><a href="#Footnote_97_97" class="fnanchor">97</a></span></p>
+
+<p>There are many regulation phenomena connected with
+osmotic pressure and permeability in animal physiology
+also, though at present they are not worked out as fully as
+possible. The works of Frédéricq, J. Loeb, Overton and
+<span class="nowrap">Sumner<a name="FNanchor_98_98" id="FNanchor_98_98"></a><a href="#Footnote_98_98" class="fnanchor">98</a></span> would have to be taken into account by any one<span class="pagenum" title="197"><a name="Page_197" id="Page_197"></a></span>
+who wished to enter more deeply into these problems. We
+can only mention here that permeability to water itself
+also plays its part, and that, according to Overton’s experiments,
+it is a kind of solubility of the media in the very
+substance of the cell surface on which all permeability and
+its regulation depend.</p>
+
+<p><i>Chromatic Regulations in Algae.</i>&mdash;The phenomena of
+osmotic pressure and its regulation may be said to be the
+preliminaries of metabolism proper, conditions necessary for
+it to take place. Now there is another branch of such
+preliminaries to metabolism, in which the most interesting
+regulation phenomena have been lately discovered. It is
+well known that what is called assimilation in plants, that
+is, the formation of organic compounds out of carbon dioxide
+(CO<sub>2</sub>) and water, occurs only in the light by means of
+certain pigments. This pigment is in all higher plants and
+in many others the green chlorophyll, but it may be different
+in certain species of algae, and can generally be <span class="nowrap">said<a name="FNanchor_99_99" id="FNanchor_99_99"></a><a href="#Footnote_99_99" class="fnanchor">99</a></span> to be
+of the colour complementary to the colour of those rays
+which especially are to be absorbed and to be used for
+assimilation. But here we have “adaptedness,” not
+adaptation. It was in some species of primitive algae, the
+<i class="biological-name">Oscillariae</i>, that <span class="nowrap">Gaidukow<a name="FNanchor_100_100" id="FNanchor_100_100"></a><a href="#Footnote_100_100" class="fnanchor">100</a></span> found a very interesting instance
+of an active regulation in the formation of pigments. These
+algae always assume a colour which corresponds to the
+accidental colour of the rays of the medium and is complementary
+to it; they become green in red light, yellow in
+blue light, and so on&mdash;that is, they always actively take that
+sort of colouring which is the most suitable to the actual<span class="pagenum" title="198"><a name="Page_198" id="Page_198"></a></span>
+<span class="nowrap">case.<a name="FNanchor_101_101" id="FNanchor_101_101"></a><a href="#Footnote_101_101" class="fnanchor">101</a></span> There indeed occurs a sort of complementary photography
+in these algae; but, though adaptive, it could hardly
+be said to exceed the limits of “primary phenomena.”</p>
+
+<p><i>Metabolic Regulations.</i>&mdash;And now we enter the field of
+regulations in metabolism itself. There are two kinds of
+outside factors of fundamental importance for all metabolic
+processes: food is one, and oxygen is the other. And
+metabolism as a whole is of two different aspects also: it
+both serves for assimilation proper&mdash;that is, building up&mdash;and
+it supplies the energy for driving the functional machine.
+It is clear that food alone&mdash;together of course with the
+assimilating means of the organism, can account for the
+first type of metabolism, while both food and oxygen, or
+some sort of substitute for the latter, as in certain
+bacteria, supply functional energy. Of course we are not
+entitled to say that the importance of so-called oxidation
+or respiration is exhausted by its energetic rôle: it certainly
+is not, for if it were, the organism would only be stopped
+in its functions if deprived of oxygen but would not die.
+It seems that certain substances always arise in the
+metabolism, in the processes of decomposition, which have
+to be burnt up in order not to become poisonous. But
+we shall return to the phenomena of organic oxidation in
+another chapter of the book, and shall deal with them from
+a more general point of <span class="nowrap">view.<a name="FNanchor_102_102" id="FNanchor_102_102"></a><a href="#Footnote_102_102" class="fnanchor">102</a></span></p>
+<p><span class="pagenum" title="199"><a name="Page_199" id="Page_199"></a></span></p>
+<p>Let us now try to take a short survey of all the regulations
+discovered relating to the substitution of one kind of
+food for another. We have said that food serves in the
+first place as building material, in the second place as
+fuel. It only deserves brief mention that, as all recent
+investigations have shown, fats, carbohydrates, and albumen
+are equally well able to serve as <span class="nowrap">fuel.<a name="FNanchor_103_103" id="FNanchor_103_103"></a><a href="#Footnote_103_103" class="fnanchor">103</a></span></p>
+
+<p>It is in the state of fasting, <i>i.e.</i> in the case of a real
+absence of <em>all</em> nourishing materials, that the organism has
+proved to be capable of regulations of the most marked
+nature, with regard to the combustion of its own materials.
+Respiration, we know, must go on if death is to be avoided,
+and now indeed it has been found that this process attacks
+the different tissues of the organism subjected to fasting in
+such an order that, after the combustion of the reserves,
+the most unimportant tissues with regard to life in general<span class="pagenum" title="200"><a name="Page_200" id="Page_200"></a></span>
+are destroyed first, the most important ones last. Thus in
+vertebrates the nerve cells and the heart are preserved as
+long as possible; in infusoria it is the nucleus; in flatworms,
+as the very careful studies of E. <span class="nowrap">Schultz<a name="FNanchor_104_104" id="FNanchor_104_104"></a><a href="#Footnote_104_104" class="fnanchor">104</a></span> have lately shown,
+it is the nerve cells and the sexual cells which longest
+resist destruction, whilst almost all the rest of the organisation
+of these animals may disappear. I should not say
+that we can do very much with these facts at present in
+our theoretical discussion, but they are certainly witness of
+very astonishing adaptive <span class="nowrap">powers.<a name="FNanchor_105_105" id="FNanchor_105_105"></a><a href="#Footnote_105_105" class="fnanchor">105</a></span></p>
+
+<p>We now turn to study the cases of a compensation of
+nourishments serving for the real building up of the organism.
+Albumen, we know, is absolutely indispensable for animals,
+even for adults, though nothing is known about the purpose
+it serves in the latter; its place can be taken of course by
+those less complicated compounds which result from its
+first decomposition, effected by pepsin and trypsin, but
+nothing else will do. The salts of sea-water, according to
+Herbst’s experiments, may only vary to a very small degree
+if the development of marine animals is to go on well;
+potassium may be replaced by caesium or rubidium, and
+that is all. Much the same is true of the salts necessary
+to plants. It will not surprise us very much to hear that
+algae can also be successfully fed with the potassium salts
+of organic compounds, and higher plants with acid amides or<span class="pagenum" title="201"><a name="Page_201" id="Page_201"></a></span>
+glucoses instead of carbonic acid, as those products are
+normal steps in their assimilation; and it may also be fairly
+easily understood that nitrogen can be offered in organic
+form instead of as a nitrate.</p>
+
+<p>It was in the group of fungi that really important
+adaptations with regard to the proper form-producing
+alimentation were first discovered, and these are of a very
+complicated kind indeed. Fungi are known to be satisfied
+with one single organic compound instead of the group of
+three&mdash;fat, carbohydrate and albumen&mdash;necessary for animals.
+Now Pfeffer showed that the most different and indeed very
+abnormal compounds were able to bring his subjects to
+a perfect growth and morphogenesis; and, moreover, he
+found that, if several kinds of such food were offered
+together, they were consumed quite indifferently as to their
+chemical constitution, but only with regard to their nutritive
+value: that sort of food which had produced a better
+growth than another when both were offered separately was
+found to save the latter from consumption whenever both
+were offered together.</p>
+
+<p>Here we are faced by one of the most typical cases of
+regulations in metabolic physiology: the organism is able
+to decompose compounds of the most different constitution,
+which have never been offered to it before; but nevertheless,
+it must remain an open question whether real
+“secondary” regulation has occurred, as nothing is known
+in detail about the single steps of metabolism in these fungi.
+There <em>might</em> be some ferments equally able to destroy different
+classes of <span class="nowrap">compounds,<a name="FNanchor_106_106" id="FNanchor_106_106"></a><a href="#Footnote_106_106" class="fnanchor">106</a></span> and that the most nutritive compound<span class="pagenum" title="202"><a name="Page_202" id="Page_202"></a></span>
+is used up first <em>may</em> be a question of physico-chemical
+equilibrium.</p>
+
+<p>That is almost <span class="nowrap">all<a name="FNanchor_107_107" id="FNanchor_107_107"></a><a href="#Footnote_107_107" class="fnanchor">107</a></span> that is actually known of adaptation
+with regard to the use of an abnormal food supply. Though
+important, it cannot be said to be very much. But could we
+expect very numerous regulations here at all after what we
+laid down in a former paragraph about the possibilities of
+adaptive regulation in general? The functional state must
+have been altered in order that such regulations may occur.
+Now there is no doubt that this state may be really altered
+only if an abnormal food has first been taken in altogether
+by the cell-protoplasm of the body-surfaces, but never if it
+has only entered the cavity of the intestine, which, strictly
+speaking, is a part of the exterior medium. Fungi indeed
+not only take in the abnormal food, but also know what to
+do with it, but all animals are obliged to treat first with
+their chemical secretions what happens to be present in
+their intestine, in order that it may be taken up by their
+living cells, and one hardly can wonder that these secretions
+are only formed in correspondence to a limited number of
+outside stimuli. In fact, as soon as we look upon what
+adaptive or regulatory work happens in metabolism <em>inside</em>
+the body interior, we meet, even in animals, regulations of a
+far more developed type.</p>
+
+<p>Discoveries of the last few years have taught us that
+almost all metabolic processes in the organism, including
+oxidation, are carried out by the aid of special materials, the<span class="pagenum" title="203"><a name="Page_203" id="Page_203"></a></span>
+so-called enzymes or ferments. These are known to exist in
+the most different forms even in the inorganic world. They
+are simply chemical compounds, of specific types, that
+bring about chemical reactions between two other chemical
+materials, which in their absence would either not go on
+at all or would go on very slowly. We cannot enter here
+into the much disputed chemical theory of what is called
+“catalysis”: we can only say that there is no objection to
+our regarding almost all metabolic processes inside the
+organism as due to the intervention of ferments or catalytic
+materials, and that the only difference between
+inorganic and organic ferments is the very complicated
+character of the latter and the very high degree of their
+specification.</p>
+
+<p>Such a statement, of course, does not say that all
+metabolism has proved to be of a chemical nature: the
+<em>action</em> of the ferment when produced is chemical, but we
+do not know at all <em>how</em> the ferment is produced; we only
+know that a high degree of active regulation is shown in
+this production. In fact, it has been proved in some cases,
+and probably will be proved in a great many more in the
+near future, that all metabolic ferments, whether they
+promote oxidation or assimilation proper or chemical decomposition,
+are produced in a regulatory manner with regard
+to the specific compound to be dissociated or to be built
+up. In this way the whole field of metabolism is really
+covered by “regulations.” Are they real “secondary”
+ones? Of course the regulatory correspondence applies to
+the process of <em>secretion</em> in the <em>first</em> place, not to the actual
+formation of the ferment inside the cell. The correspondence
+as to secretion, no doubt, is of the primary type; is there<span class="pagenum" title="204"><a name="Page_204" id="Page_204"></a></span>
+any secondary regulation with regard to the real <em>production</em>
+of the ferment? I am sorry that I cannot answer this
+question affirmatively. Nothing is <em>known</em> at present, even
+here, that really proves the existence of adaptation of the
+secondary type: there <em>might</em> be a sort of statical “harmony”
+at the base of it all, established before all functioning <em>for</em>
+<span class="nowrap">functioning.<a name="FNanchor_108_108" id="FNanchor_108_108"></a><a href="#Footnote_108_108" class="fnanchor">108</a></span></p>
+
+<p>The only facts of secondary metabolic regulations which
+are known at present have been found in combination with
+phenomena of restitution after real disturbances of organisation,
+where, indeed, numbers and numbers of regulatory
+changes of metabolism, both in animals and plants, have
+also been recorded. But there is not one case of a secondary
+regulation really known to affect pure metabolism <span class="nowrap">alone.<a name="FNanchor_109_109" id="FNanchor_109_109"></a><a href="#Footnote_109_109" class="fnanchor">109</a></span>
+This is a new indicium of the primacy of <em>form</em> in the
+organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">IMMUNITY THE ONLY TYPE OF A SECONDARY PHYSIOLOGICAL
+ADAPTATION</span></p>
+
+<p>There is only one class of physiological processes in
+which the type of the real secondary regulation occurs.<span class="pagenum" title="205"><a name="Page_205" id="Page_205"></a></span>
+The discoveries of the last twenty years have proved
+beyond all doubt, and future discoveries will probably prove
+even more conclusively, that the so-called <em>immunity</em> against
+diseases is but one case out of numerous biological phenomena
+in which there is an adaptive correspondence between
+abnormal chemical stimuli and active chemical reactions on
+the part of the organism and in its interior, exceeding by
+far everything that was formerly supposed to be possible
+in organic regulation.</p>
+
+<p>The adaptive faculty of the organism against inorganic
+poisonous <span class="nowrap">substances<a name="FNanchor_110_110" id="FNanchor_110_110"></a><a href="#Footnote_110_110" class="fnanchor">110</a></span> is but small comparatively, and is
+almost always due not to a real process of active regulation
+but to the action of substances pre-existing in the organism&mdash;that
+is, to a sort of adaptiveness but not adaptation.
+Metallic poisons, for instance, may be transformed into
+harmless compounds by being combined with albumen or
+sulphuric acid and thus becoming insoluble, or free acids
+may be neutralised, and so on; but all these processes
+go on to a certain extent only, and, as was mentioned
+already, are almost always the result of reactions with
+pre-existing materials. Only in a few cases is there any
+sort of true adaptation to metallic substances, such as
+sublimate and, in a very small degree, arsenic, comparable
+in some respects with the adaptation to abnormally high
+temperatures. The organism which has been accustomed
+to receive at first very small amounts, say, of sublimate, and
+then receives greater and greater amounts of this substance
+by degrees, will at the end of this treatment be able to
+stand a quantity of the poison that would have been<span class="pagenum" title="206"><a name="Page_206" id="Page_206"></a></span>
+instantly fatal if administered at the first <span class="nowrap">dose.<a name="FNanchor_111_111" id="FNanchor_111_111"></a><a href="#Footnote_111_111" class="fnanchor">111</a></span> But the
+explanation of this adaptation is not known in any case;
+there seems to be some similarity between it and the so-called
+histogenetic immunity against organic poisons.</p>
+
+<p>It is in the fight against animal and vegetable poisons,
+such as those produced by bacteria, by some plants and
+by poisonous snakes, that the true adaptation of the
+organism reaches its most astonishing degree. The production
+of so-called “anti-bodies” in the body fluids is
+not the only means applied against noxious chemical
+substances of this kind: the existence of so-called histogenetic
+immunity is beyond all doubt, and <span class="nowrap">Metschnikoff<a name="FNanchor_112_112" id="FNanchor_112_112"></a><a href="#Footnote_112_112" class="fnanchor">112</a></span>
+certainly was also right in stating that the cells of the
+organism themselves repel the attack of living bacteria.
+Cells of the connective tissue and the white blood cells,
+being attracted by them as well as by many other foreign
+bodies, take them in and kill them. This process, called
+“phagocytosis” is of special frequency among lower animals,
+but it also contributes to what is called inflammation in
+higher <span class="nowrap">ones.<a name="FNanchor_113_113" id="FNanchor_113_113"></a><a href="#Footnote_113_113" class="fnanchor">113</a></span> And there are still other kinds of defence
+against parasites, as for instance the horny or calcareous
+membranes, employed to isolate trichinae and some kinds
+of bacteria. But all this is of almost secondary importance
+as compared with the adaptive faculties of the warm-blooded
+vertebrates, which produce anti-poisonous substances
+in their lymph and blood.</p>
+
+<p><span class="pagenum" title="207"><a name="Page_207" id="Page_207"></a></span></p>
+
+<p>It is impossible to say <span class="nowrap">here<a name="FNanchor_114_114" id="FNanchor_114_114"></a><a href="#Footnote_114_114" class="fnanchor">114</a></span> more than a few words
+about the phenomena and the theory of immunity proper,
+which have attained the dimensions of a separate science.
+Let me only mark those general points which are of
+the greatest theoretical interest. Discoveries of the most
+recent years have shown not only that against the “toxins”
+of bacteria, snakes, and some plants, the organism is able
+actively to produce so-called “anti-toxins”&mdash;that is, soluble
+substances which react with the toxins and destroy their
+poisonous character&mdash;whenever required, but that against
+any foreign body of the albumen group a specific reaction
+may occur, resulting in the coagulation of that body. But
+the destruction of the noxious substance or foreign albumen
+actually present is not all that is accomplished by the
+organism. “Acquired immunity” proper, that is, security
+against the noxious material for a more or less extensive
+period of the <em>future</em>, depends on something more. Not
+only is there produced as much of the so-called “anti-body”
+as is necessary to combine with the noxious, or at least
+foreign substances which are present, but <em>more</em> is produced
+than is necessary in the actual case. On this over-production
+depends all active immunity, whether natural or,
+as in some kinds of vaccination, artificial; and so-called
+“passive” immunity, obtained by the transfusion of the
+serum of an actively immune organism into another also
+depends upon this <span class="nowrap">feature.<a name="FNanchor_115_115" id="FNanchor_115_115"></a><a href="#Footnote_115_115" class="fnanchor">115</a></span></p>
+
+<p>This phenomenon in particular&mdash;the production of <em>more</em>
+of the antitoxin or the “precipitin” than is actually<span class="pagenum" title="208"><a name="Page_208" id="Page_208"></a></span>
+necessary&mdash;seems to render almost impossible any merely
+chemical theory of these facts. The reaction between
+toxin and antitoxin, albumen and precipitin is indeed
+chemical; it may in fact be carried out in a test-tube;
+but whether the production of the anti-body itself is
+also chemical or not could hardly be ascertained without
+a careful and unbiassed analysis. There can be no doubt
+that the well-known theory of <span class="nowrap">Ehrlich,<a name="FNanchor_116_116" id="FNanchor_116_116"></a><a href="#Footnote_116_116" class="fnanchor">116</a></span> the so-called theory
+of side-chains (“Seitenkettentheorie”) has given a great
+impulse to the progress of science; but even this theory,
+irrespective of its admissibility in general, is not a real
+chemical one: the concept of a regeneration of its so-called
+haptophore groups is a strictly biological <span class="nowrap">concept.<a name="FNanchor_117_117" id="FNanchor_117_117"></a><a href="#Footnote_117_117" class="fnanchor">117</a></span></p>
+
+<p>And, indeed, here if anywhere we have the biological
+phenomenon of adaptation in its clearest form. There are
+very abnormal changes of the functional state of the
+organism, and the organism is able to compensate these
+changes in their minutest detail in almost any case. The
+problem of the specification of the reactions leading to
+immunity seems to me, as far as I can judge as an outsider,
+to stand at present in the very forefront of the science.
+There cannot be the slightest doubt that especially against
+all sorts of foreign albumens the reaction is as strictly
+specific as possible; but there are some typical cases of<span class="pagenum" title="209"><a name="Page_209" id="Page_209"></a></span>
+specificity in the production of antitoxins also. It is, of
+course, the <em>fact</em> of specific correspondence between stimulus
+and reaction, that gives to immunity its central position
+among all adaptations, no matter whether the old hypothesis
+of the production of specific anti-bodies proves tenable, or
+whether, as has been urged more recently by some authors,
+the anti-body is always the same but reacts differently
+according to the medium. In the latter case it would be
+the medium that is regulated in some way by the organism
+in order to attain a specific adaptedness.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">NO GENERAL POSITIVE RESULT FROM THIS CHAPTER</span></p>
+
+<p>But now let us look back to the sum of all the physiological
+reactions studied, and let us see if we have gained
+a new proof of the autonomy of life from our long chapter.</p>
+
+<p>We freely admit we have not gained any really new
+<em>proof</em>, but we may claim, I think, to have gained many
+indicia for the statement that the organism is not of the
+type of a machine, in which every single regulation is to
+be regarded as properly prepared and outlined.</p>
+
+<p>It is precisely in the field of immunity that such a
+machine-like preparation of the adaptive effects seems
+almost impossible to be imagined. How indeed could there
+be a machine, the chemical constituents of which were such
+as to correspond adaptively to almost every requirement?&mdash;to
+say nothing of the fact that the production of <em>more</em> of
+the protecting substance than is actually necessary could
+hardly be said to be “chemical.”</p>
+
+<p>In fact, we are well entitled to say that we have reached
+here the very heart of life and of biology. If nevertheless<span class="pagenum" title="210"><a name="Page_210" id="Page_210"></a></span>
+we do not call the sum of our facts a real proof of vitalism,
+it is only because we feel unable to formulate the analysis
+of what happens in such a manner as to make a machine
+as the basis of all reactions absolutely unimaginable and
+unthinkable. There <em>might</em> be a true machine in the organism
+producing immunity with all its adaptations. We cannot
+disprove such a doctrine by demonstrating that it would
+lead to a real <em>absurdity</em>, as we did in our analysis of
+differentiation of form; there is only a very high degree
+of improbability in our present case. But an indirect
+<em>proof</em> must reduce to <em>absurdity</em> all the possibilities except
+one, in order to be a proof.</p>
+
+<p>Mechanistic explanations in all branches of functional
+physiology proper, so much in vogue twenty years ago, can
+indeed be said to have failed all along the line: the only
+advantage they have brought to science is the clearer
+statement of problems to which we are now accustomed.
+But we are not fully entitled to <span class="nowrap">say<a name="FNanchor_118_118" id="FNanchor_118_118"></a><a href="#Footnote_118_118" class="fnanchor">118</a></span> that there never will
+be any mechanistic explanation of physiological functions
+in the future. It may seem as improbable as anything
+can be; but we wish to know not what is improbable but
+what is not possible.</p>
+
+<p>Now of course you might answer me that after we have
+indeed shown that the production of form, as occurring on
+the basis of harmonious-equipotential systems, is a fact that
+proves vitalism, the acts taking place on the basis of that
+form after its production would have been proved to be
+vitalistic also, or at least to be in some connection with
+vitalistic phenomena. Certainly they would, and I myself<span class="pagenum" title="211"><a name="Page_211" id="Page_211"></a></span>
+personally should not hesitate to say so. But that is not
+the question. We have to ask: Is any new proof, <em>independent
+of every other</em>, to be obtained from the facts of
+physiological adaptation in themselves? And there is really
+none. Mere regulatory correspondence between stimuli and
+reactions, even if it be of the adaptive type and occur in
+almost indefinite forms, never really disproves a machine
+as its basis so long as the stimuli and reactions are <em>simple</em>
+and uniform. Next summer, however, we shall see that
+vitalism may be proved by such a correspondence if the
+two corresponding factors are not simple and not uniform.</p>
+
+<p>We most clearly see at this point what it really was
+in our analysis of differentiation that allowed us to extract
+a real proof of vitalism from it. Not the mere fact of
+regulability, but certain specific relations of space, of locality,
+lay at the very foundation of our proof. These relations,
+indeed, and only these relations, made it possible to reduce
+<i lang="la" xml:lang="la">ad absurdum</i> any possible existence of a machine as the
+actual basis of what we had studied. In our next chapter
+again it will be space-relations, though analysed in a different
+manner, that will enable us to add a second real proof
+of vitalism to our first one.</p>
+
+<p>With this chapter we conclude the study of organic
+regulation in all its forms, as far as morphogenesis and
+metabolism are in question.</p>
+
+<p>But our analysis of these regulations would be incomplete
+and indeed would be open to objections, if we did not
+devote at least a few words to two merely negative
+topics, which will be taken more fully into consideration
+later on.</p>
+
+<p><span class="pagenum" title="212"><a name="Page_212" id="Page_212"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">A FEW REMARKS ON THE LIMITS OF REGULABILITY</span></p>
+
+<p>There has never been found any sort of “experience” in
+regulations about morphogenesis or in adaptations of the
+proper physiological type. Nothing goes on “better” the
+second time than it did the first <span class="nowrap">time;<a name="FNanchor_119_119" id="FNanchor_119_119"></a><a href="#Footnote_119_119" class="fnanchor">119</a></span> everything is either
+complete, whenever it occurs, or it does not occur at all.</p>
+
+<p>That is the first of our important negative statements
+about regulations; the second relates to the phrase just
+used, “or it does not occur at all.” There are indeed limits
+of regulability; adaptations are not possible to every sort
+of change of the physiological state: sickness and death
+could not exist if they were; nor is restitution possible in
+all cases where it might be useful. It is a well-known fact,
+that man is only able to heal wounds but is altogether
+destitute of the faculty of regeneration proper. But even
+lower animals may be without this faculty, as are the
+ctenophores and the nematodes for instance, and there is no
+sort of correspondence between the faculty of restitution
+and the place in the animal kingdom. It is not altogether
+impossible that there may be found, some day, certain conditions
+under which every organism is capable of restoring<span class="pagenum" title="213"><a name="Page_213" id="Page_213"></a></span>
+any missing part; but at present we know absolutely
+nothing about such <span class="nowrap">conditions.<a name="FNanchor_120_120" id="FNanchor_120_120"></a><a href="#Footnote_120_120" class="fnanchor">120</a></span></p>
+
+<p>But no amount of negative instances can disprove an
+existing positive&mdash;which is what we have been studying.
+Our analysis based upon the existence of regulations is
+as little disparaged by cases where no regulability exists
+as optical studies are by the fact that they cannot be
+undertaken in absolute darkness.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="214"><a name="Page_214" id="Page_214"></a></span></p>
+
+
+
+
+<h3><i>D.</i> INHERITANCE: SECOND PROOF OF THE AUTONOMY OF LIFE</h3>
+
+
+<p>All organisms are endowed with the faculty of re-creating
+their own initial form of existence.</p>
+
+<p>In words similar to these Alexander Goette, it seems to
+me, has given the shortest and the best expression of the
+fact of inheritance. Indeed, if the initial form in all its
+essentials is re-created, it follows from the principle of
+univocality, that, <i lang="la" xml:lang="la">ceteris paribus</i>, it will behave again as
+it did when last it existed.</p>
+
+<p>By the fact of inheritance life becomes a rhythmic
+phenomenon, that is to say, a phenomenon, or better, a chain
+of phenomena, whose single links reappear at constant
+intervals, if the outer conditions are not changed.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Material Continuity in Inheritance</span></p>
+
+<p>It was first stated by Gustav Jaeger and afterwards
+worked out into a regular theory by Weismann, that there
+is a continuity of material underlying inheritance. Taken
+in its literal meaning this statement is obviously self-evident,
+though none the less important on that account.
+For as all life is manifested on bodies, that is on matter,
+and as the development of all offspring starts from parts of
+the parent bodies, that is from the matter or material of the<span class="pagenum" title="215"><a name="Page_215" id="Page_215"></a></span>
+parents, it follows that in some sense there is a sort of
+continuity of material as long as there is life&mdash;at least in
+the forms we know of. The theory of the continuity of
+“germ-plasm” therefore would be true, even if germ-cells
+were produced by any and every part of the organism. That,
+as we know, is not actually the case: germ-cells, at least
+in the higher animals and in plants, are produced at certain
+specific localities of the organism only, and it is with regard
+to this fact that the so-called theory of the “continuity of
+germ-plasm” acquires its narrower and proper sense. There
+are distinct and specific lines of cell-lineage in ontogenesis,
+so the theory states, along which the continuity of germ-protoplasm
+is kept up, which, in other words, lead from one
+egg to the other, whilst almost all other lines of cell-lineage
+end in “somatic” cells, which are doomed to death. What
+has been stated here is a fact in many cases of descriptive
+embryology, though it can hardly be said to be more than
+that. We know already, from our analytical and experimental
+study of morphogenesis, that Weismann himself had
+to add a number of subsidiary hypotheses to his original
+theory to account for the mere facts of regeneration proper
+and the so-called vegetative reproduction in plants and in
+some animals, and we have learned that newly discovered
+facts necessitate still more appendixes to the original theory.
+In spite of that, I regard it as very important that the fact
+of the continuity of some material as one of the foundations
+of inheritance has clearly been stated, even if the specialised
+form of the theory, as advocated by Weismann in the
+doctrine of the “germ-lineages” (“Keimbahnen”) should
+prove unable to stand against the facts.</p>
+
+<p>The important problem now presents itself: What is the<span class="pagenum" title="216"><a name="Page_216" id="Page_216"></a></span>
+material, the matter, which is handed down from generation
+to generation as the basis of inheritance? Weismann, as
+we know, regarded it as a very complicated structure, part
+of which by its disintegration became the foundation of
+individual embryology. We have disproved, on the authority
+of many facts, the latter part of this assumption; but of
+course the first part of it may turn out to be true in spite
+of this. We have no means at present to enable us to say
+<i lang="la" xml:lang="la">a priori</i> anything positive or negative about the important
+question of the nature of that matter, the continuity of which
+in inheritance is in some sense a self-evident fact, and we
+therefore shall postpone the answer until a later point of
+our analytical discussion.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">On Certain Theories which Seek to Compare
+Inheritance to Memory</span></p>
+
+<p>It will be advisable first to study some other theoretical
+views which have been put forward with regard to inheritance.
+The physiologist Hering, as early as 1876,
+compared all heredity to the well-known fact of memory,
+assuming, so to say, a sort of remembrance of all that has
+happened to the species in the continuity of its generations;
+and several German authors, especially Semon, have lately
+made this hypothesis the basis of more detailed speculation.</p>
+
+<p>It is not clear, either from Hering’s <span class="nowrap">paper<a name="FNanchor_121_121" id="FNanchor_121_121"></a><a href="#Footnote_121_121" class="fnanchor">121</a></span> or from
+Semon’s <span class="nowrap">book,<a name="FNanchor_122_122" id="FNanchor_122_122"></a><a href="#Footnote_122_122" class="fnanchor">122</a></span> what is really to be understood here by
+the word “memory,” and, of course, there might be understood
+by it very different things, according to the autho<span class="pagenum" title="217"><a name="Page_217" id="Page_217"></a></span>r’s
+psychological point of view. If he is a “parallelist” with
+regard to so-called psychical phenomena, he would use the
+word memory only as a sort of collective term to signify
+a resultant effect of many single mechanical events, as far as
+the material world of his parallel system comes into account,
+with which of course the problem of inheritance alone deals;
+but if he maintains the theory of so-called psycho-physical
+interaction, the psychical would be to him a primary factor
+in nature, and so also would memory. As we have said, it
+is by no means clear in what sense the word “memory”
+is used by our authors, and therefore the <em>most</em> important
+point about the matter in question must remain <i lang="la" xml:lang="la">in dubio</i>.</p>
+
+<p>But another topic is even more clear in the theory of
+inheritance, as stated in Hering’s and Semon’s writings.
+The hypothetical fact that so-called “acquired characters”
+are inherited is undoubtedly the chief assumption of that
+theory. Indeed, it would be difficult to understand the
+advantage of the ambiguous word memory, had it not to
+call attention to the hypothetic fact that the organism
+possesses the faculty of “remembering” what once has
+happened to it or what it once has “done,” so to speak, and
+profiting by this remembering in the next generation. The
+zoologist Pauly indeed has stated this view of the matter
+in very distinct and clear terms.</p>
+
+<p>As we soon shall have another occasion to deal with the
+much-discussed problem of the “inheritance of acquired
+characters,” we at present need only say a few words
+about the “memory-theory” as a supposed “explanation”
+of heredity. Undoubtedly this theory postulates, either
+avowedly or by half-unconscious implication, that all the
+single processes in individual morphogenesis are the outcome<span class="pagenum" title="218"><a name="Page_218" id="Page_218"></a></span>
+either of adaptations of the morphological type, which
+happened to be necessary in some former generation, or of
+so-called contingent “variations,” of some sort or other,
+which also happened once in the ancestral line. Such a
+postulate, of course, is identical with what is generally called
+the theory of descent in any of its different forms. This
+theory is to occupy us in the next lectures; at present we
+only analyse the “memory-theory” as a theory of heredity
+in itself. In any case, to regard memory as the leading
+point in inheritance, at least if it is to signify what is
+called memory in any system of psychology, would be to
+postulate that either adaptation or contingent “variation”
+has been the origin of every morphogenetic process. Indeed,
+the American physiologist Jennings did not hesitate to
+defend such a view most strongly, and many others seem to
+be inclined to do the same.</p>
+
+<p>But such an assumption most certainly cannot be true.</p>
+
+<p>It cannot be true, because there are many phenomena
+in morphogenesis, notably all the phenomena akin to
+restitution of form, which occur in absolute perfection even
+the very first time they happen. These processes, for the
+simple reason of their <em>primary perfection</em>, cannot be due
+either to “learning” from a single adaptation, or to accidental
+variation. We shall afterwards employ a similar kind of
+argument to refute certain theories of evolution. It therefore
+may be of a certain logical interest to notice that at
+present, combating the memory-theory of inheritance, and
+hereafter, combating certain theories of descent, we select
+not “adaptation” or “variation” as the central points to
+be refuted, but the assumed <em>contingency</em> of both of them.</p>
+
+<p>The word “memory,” therefore, may be applied to the<span class="pagenum" title="219"><a name="Page_219" id="Page_219"></a></span>
+phenomena of inheritance only in a very figurative meaning,
+if at all. We do not wholly deny the possibility of an
+inheritance of acquired characters, as will be seen later on,
+and to such a fact there might perhaps be applied such a
+term as “memory” in its real sense, but we simply <em>know</em>
+that there <em>is</em> something in inheritance which has no
+similarity whatever to what is called “memory” in any
+species of psychology. A primary perfection of processes
+occurring quite abnormally proves that there is a “knowing”
+of something&mdash;if we may say so&mdash;but does not prove
+at all that there is a “remembering.”</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Complex-Equipotential System and its Rôle in
+Inheritance</span><a name="FNanchor_123_123" id="FNanchor_123_123"></a><a href="#Footnote_123_123" class="fnanchor">123</a></p>
+
+<p>But we thus far have reached only negative results. Is
+the question necessarily to remain at this point, which
+could hardly be said to be very satisfying; or could we
+perhaps get better, that is, positive results about inheritance
+by a change of our analytic methods? Let us try to
+analyse the facts that occur in inheritance instead of
+beginning with hypotheses which claim to be complete
+explanations. Perhaps we shall gain, if but small, yet
+certainly fixed results by an analysis which goes from the
+facts to the theory and not from the theory to the facts.</p>
+
+<p>Let the discussions that are to follow be placed upon
+a basis as broad as possible.</p>
+
+<p>Our studies of morphogenetic restitution have shown us
+that besides the harmonious-equipotential systems another
+and widely different type of morphogenetic “systems” (<i>i.e.</i><span class="pagenum" title="220"><a name="Page_220" id="Page_220"></a></span>
+unities consisting of elements equal in morphogenetic
+faculty) may also be the basis of restitution processes.
+Whilst in the harmonious system the morphogenetic acts
+performed by every single element in any actual case are
+single acts, the totality of all the single acts together forming
+the harmonious whole, in the other type of systems now to
+be examined, complex acts, that is, acts which consist of a
+manifoldness in space and in time, can be performed by
+each single element, and actually are performed by one or
+the other of them. We therefore have given the title of
+“complex-equipotential systems” to the systems in question,
+as all our denominations are based on the concept of the
+prospective morphogenetic potency, that is of the possible
+fate of the elements.</p>
+
+<p>The cambium of the Phanerogams may be regarded as
+the very type of a complex-equipotential system, promoting
+restitution of form. It runs through the whole stem of
+our trees, in the form of a hollow tube, placed between
+the inner and the outer cell-layers of the stem, and either
+branch or root may originate from any single one of its
+cells, just as circumstances require. We might call the
+cambium a system of the “complex” type of course, even
+if every one of its constituents were able to form only a root
+or only a branch by way of restitution. But in fact one
+and the same element can form both of these complex-structures;
+it depends only on its relative position in the
+actual part of the stem isolated for the purposes of experiment,
+what will be accomplished in every case. Here we
+have a state of affairs, which we shall encounter again
+when studying regeneration in animals: every element of
+the system may be said to contain potencies for the <span class="pagenum" title="221"><a name="Page_221" id="Page_221"></a></span>“ideal
+whole,” though this ideal whole will never be realised in
+its proper <span class="nowrap">wholeness.<a name="FNanchor_124_124" id="FNanchor_124_124"></a><a href="#Footnote_124_124" class="fnanchor">124</a></span></p>
+
+<p>But there is no need to recur to the “ideal whole” in
+many other cases of adventitious restitution in plants.
+On isolated leaves of the well-known begonia, a whole plant,
+containing all the essential parts, may arise from any single
+<span class="nowrap">cell<a name="FNanchor_125_125" id="FNanchor_125_125"></a><a href="#Footnote_125_125" class="fnanchor">125</a></span> of the epidermis, at least along the veins, and in some
+liverworts it has been shown by Vöchting, that almost
+every cell of the whole is able to reproduce the plant, as
+is also the case in many algae.</p>
+
+<p>In the animal kingdom it is chiefly and almost solely
+the phenomena of regeneration proper which offer typical
+instances of our systems, since adventitious restitution,
+though occurring for instance in the restitution of the lens
+of vertebrates from the iris, and though connected also with
+the events in regeneration <span class="nowrap">proper,<a name="FNanchor_126_126" id="FNanchor_126_126"></a><a href="#Footnote_126_126" class="fnanchor">126</a></span> is of but secondary
+importance in animal restitution, at least, if compared with
+restitution in plants. If we study the regeneration of a
+leg in the common newt, we find that it may take place
+from every section, the point of amputation being quite at<span class="pagenum" title="222"><a name="Page_222" id="Page_222"></a></span>
+our choice. Without regarding here the exact order of
+the regeneration phenomena, which is almost unknown at
+present, we in any case can say without any doubt that
+the line of consecutive possible cross-sections forms a
+complex-morphogenetic system, as every one of them is
+able to give rise to a complex organ, viz. the foot and part
+of the leg. It is an open question whether this complex
+system is to be called “equipotential” or not. It indeed
+seems to be inequipotential at the first glance, for each
+single section has to form a different organogenetic totality,
+namely, always that specific totality which had been cut
+off; but if we assume hypothetically that the real “Anlage”
+which is produced immediately by the cells of the wounded
+surface is the very same for all of them, and that it is the
+actual state of organisation which determines to what result
+this Anlage is to <span class="nowrap">lead,<a name="FNanchor_127_127" id="FNanchor_127_127"></a><a href="#Footnote_127_127" class="fnanchor">127</a></span> we may say that the series of consecutive
+cross-sections of a newt’s leg does form a morphogenetic
+system of the complex-equipotential type, promoting
+secondary regulations of form.</p>
+
+<p>Now all these difficulties vanish, if we consider the
+regeneration of animals, such for instance as many worms
+of the annelid class or our familiar ascidian <i class="biological-name">Clavellina</i>, in
+which regeneration in both directions is possible. The
+wound at the posterior end of the one half which results
+from the operation forms a posterior body half, the wound<span class="pagenum" title="223"><a name="Page_223" id="Page_223"></a></span>
+at the anterior end of the other half forms an anterior one.
+Again, it is the ideal whole which we meet here: each
+section of the body indeed may be said to contain the
+potencies for the production of the totality, though actually
+this totality is always realised by the addition of two
+partial organisations. The title of complex-equipotential
+systems thus seems to be fully justified as applied to the
+systems which are the basis of regeneration: each section
+of the regenerating body may in fact produce the same
+complex whole, or may, if we prefer to say so, at least
+prepare the ground for that complex Anlage, out of which
+the complex totality is actually to arise, in the same
+manner.</p>
+
+<p>It often occurs in science, that in rather strange and
+abnormal conditions something becomes apparent which
+might have been found everywhere, which is lying before
+our eyes quite obviously. Are we not in just such a
+condition at present? In order to study the complex-equipotential
+systems, we turn to the phenomena of
+regeneration and of restitution in general; we occasionally
+even introduce hypotheses to render our materials more
+convenient for our purposes; and all the time there is
+one sort of complex-equipotential system in the body of
+every living being, which only needs to be mentioned in
+order to be understood as such, and which indeed requires
+no kind of preliminary discussion. The system of the
+propagation cells, in other words the sexual organ, is the
+clearest type of a complex-equipotential system which
+exists. Take the ovary of our sea-urchin for instance, and
+there you have a morphogenetic system every element of
+which is equally capable of performing the same complex<span class="pagenum" title="224"><a name="Page_224" id="Page_224"></a></span>
+morphogenetic course&mdash;the production of the whole
+individual.</p>
+
+<p>Further on we shall deal exclusively with this variety
+of our systems, and in doing so we shall be brought back
+to our problem of heredity. But it had its uses to place
+our concept of the complex-equipotential system upon such
+a broad basis: we at once gave a large range of validity to
+all that is to follow&mdash;which, indeed, does not apply to inheritance
+alone, though its significance in a theory of
+heredity may be called its most important consequence.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Second Proof of Life-Autonomy. Entelechy at
+the Bottom of Inheritance</span></p>
+
+<p>After we had established the concept of the harmonious-equipotential
+system in a former chapter, we went on
+to study the phenomena of the differentiation of it,
+and in particular the problem of the localisation of all
+differentiations. Our new concept of the complex-equipotential
+system is to lead us to an analysis of a
+different kind: we shall pay special attention to the origin,
+to the <em>genesis</em> of our complex systems that show equipotentiality.</p>
+
+<p>If we review the process of ontogenesis, we are able to
+trace back every complex system to a very small group of
+cells, and this small group of cells again to one single cell.
+So in plants the cambium may be shown to have originated
+in a sort of tissue-rudiment, established at a very early
+period, and the ovary may be demonstrated to be the outcome
+of a group of but a few cells, constituting the first
+visible “Anlage” of the reproductive organs. At the end<span class="pagenum" title="225"><a name="Page_225" id="Page_225"></a></span>
+then, or from another point of view at the beginning,
+a single cellular element represents the very primordial
+egg-cell.</p>
+
+<p>The whole cambium, there can be no doubt, must be
+regarded as the result of a consecutive number of cell-divisions
+of the one cell from which it originates. So
+must it be with the ovary. The primordial egg-cell has
+undergone a long line of consecutive divisions; the single
+eggs are the last result of them.</p>
+
+<p>We now proceed to some considerations which have a
+certain logical similarity to those which inaugurated our
+analysis of the differentiation of the harmonious-equipotential
+systems, though the facts in question are very different.</p>
+
+<p>Viewed by itself without any kind of prepossessions, as
+it might be by any one who faces a new problem with the
+single postulate of introducing new natural entities&mdash;to
+use the scholastic phrase&mdash;as little as possible, the development
+of the single egg might be regarded as proceeding
+on the foundation of a very complicated sort of machine,
+exhibiting a different kind of construction in the three
+chief dimensions of space, as does also the organism which
+is to be its result.</p>
+
+<p>But could such a theory&mdash;irrespective of all the experimental
+facts which contradict it&mdash;could such a theory
+stand before the <em>one</em> fact, that there occurs a <em>genesis</em> of that
+complex-equipotential system, of which our one single egg
+forms a part? Can you imagine a very complicated
+machine, differing in the three dimensions of space, to be
+divided hundreds and hundreds of times and in spite of
+that to remain always the same whole? You may reply that
+during the period of cell-divisions there is still no machine,<span class="pagenum" title="226"><a name="Page_226" id="Page_226"></a></span>
+that the machine is established only after all the divisions
+are complete. Good; but what then constructs this
+machine in the definitive cells of our systems, say in the
+eggs? Another sort of machine perhaps? That could
+hardly be said to be of much use. Or that entelechy of
+which we have spoken? Then you would recur to our
+first proof of vitalism and would burden entelechy with a
+specific performance, that is with the construction of the
+hypothetic machine which you are postulating in every
+single egg. But of course you would break the bounds of
+physics and chemistry even then.</p>
+
+<p>It seems to me that it is more simple, and so to say
+more natural, not to recur to our first proof of life-autonomy
+in order to keep to the “machine theory” in
+this new branch of inquiry, but to consider facts as they
+offer themselves to analysis.</p>
+
+<p>But then indeed we are entitled to draw an independent
+second proof of the autonomy of life from our analysis of
+the genesis of systems of the complex-equipotential type.
+We say it is a mere absurdity to assume that a complicated
+machine, typically different in the three dimensions of space,
+could be divided many many times, and in spite of that
+always be the whole: therefore there cannot exist any sort
+of machine as the starting-point and basis of development.</p>
+
+<p>Let us again apply the name entelechy to that which
+lies at the very beginning of all individual morphogenesis.</p>
+
+<p>Entelechy thus proves to be also that which may be
+said to lie at the very root of <span class="nowrap">inheritance,<a name="FNanchor_128_128" id="FNanchor_128_128"></a><a href="#Footnote_128_128" class="fnanchor">128</a></span> or at least of<span class="pagenum" title="227"><a name="Page_227" id="Page_227"></a></span>
+the outcome of inheritance; the individual formation of the
+next generation is shown not to be performed by a machine
+but by a natural agent <i lang="la" xml:lang="la">per se</i>.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Significance of the Material Continuity in
+Inheritance</span></p>
+
+<p>But what about the material continuity appearing in
+inheritance, which we have said to be almost self-evident,
+as life is only known to exist on material bodies? Is
+there not, in fact, a serious contradiction in admitting at
+the same time entelechy on the one side and a sort
+of material condition on the other as the basis of all
+that leads to and from inheritance? Next summer the
+relation between matter and our autonomous agent of life
+will be studied more fully; at present it must be enough
+to state in a more simple and realistic way, what we hold
+this relation to be. There is no contradiction at all in
+stating that material continuity is the basis of inheritance
+on the one side, and entelechy on the other. It would
+be very inconvenient for us if there were any: for the
+material continuity is a mere fact and our entelechy we
+hope we have proved to exist also; if now there were any
+sort of contradiction in assuming the existence of both of
+them, of course it would be fatal to our proof.</p>
+
+<p>Let us try to comprehend what is meant by the
+statement that entelechy and something material are at
+work in inheritance at the same time. Entelechy has ruled
+the individual morphogenesis of the generation which is
+regarded as being the starting-point for inheritance, and
+will rule also the morphogenesis of the generation which<span class="pagenum" title="228"><a name="Page_228" id="Page_228"></a></span>
+is to follow; entelechy determines the egg to be what it is,
+and the morphogenesis starting from this egg to be what
+it is also. Entelechy, at present, is not much more for us
+than a mere word, to signify the autonomous, the irreducible
+of all that happens in morphogenesis with respect to <em>order</em>,
+in the one generation and in the next. But may not the
+material continuity which exists in inheritance account
+perhaps for the material elements <em>which are to be ordered</em>?
+In such a way, indeed, I hope we shall be able to reconcile
+entelechy and the material basis of heredity. May it not
+be that there exist some “means” for morphogenesis,
+which are handed down from generation to generation,
+always controlled by entelechy, and which constitute the real
+significance of the continuity of matter during inheritance?</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Experimental Facts about Inheritance</span></p>
+
+<p>Discoveries of the last few years do seem to show that
+such means of a material character, though not the foundation
+of that order of processes which is inherited, are
+nevertheless among the most necessary conditions for the
+accomplishment of inheritance in general. It is scarcely
+necessary to remind you that for very many years all
+concrete research on heredity proper&mdash;that is, the actual
+comparison of the various specific characters in the generations
+of the grandfather, the father, and the child&mdash;was
+due to Galton. You may also be aware that in spite of
+Galton’s inestimable services it was not till 1900 that one
+of the active principles concerned in inheritance was found
+independently by de Vries, Correns, and Tschermak, and
+that this principle happened to be one that <em>had</em> been<span class="pagenum" title="229"><a name="Page_229" id="Page_229"></a></span>
+discovered already, stated with the utmost clearness and
+precision by the Augustinian monk, Gregor <span class="nowrap">Mendel,<a name="FNanchor_129_129" id="FNanchor_129_129"></a><a href="#Footnote_129_129" class="fnanchor">129</a></span> as
+early as 1865, though it had been completely forgotten
+ever since.</p>
+
+<p>The so-called “rule of Mendel” is based upon experiments
+with hybrids, that is, with the offspring of parents
+belonging to different species, or, at least, varieties, but it
+relates not to the characters of the generation resulting
+immediately from hybridisation, the “first” generation of
+hybrids, as we shall call it, but to the characters of that
+generation which is the result of crossing the hybrids with
+each other, provided that this leads to any offspring at all.
+There are many cases indeed, both amongst animals and
+plants, where the offspring of the hybrids, or in other
+terms the “second” generation, is found to consist of
+individuals of three different types&mdash;the <span class="nowrap">mixed<a name="FNanchor_130_130" id="FNanchor_130_130"></a><a href="#Footnote_130_130" class="fnanchor">130</a></span> type of
+the hybrids themselves, and the two pure types of the
+grandparents. Whenever the individuals of the “second”
+generation are separated into these three different types,
+hybrids are said to “split.” It is the fact of this splitting
+on the one hand, and on the other hand a certain statement
+about the numbers of individuals in the three different
+types of the “second” generation, that gives its real
+importance to Mendel’s rule.</p>
+
+<p>Before discussing what may follow from Mendel’s
+discovery for the theory of heredity, we must lay stress<span class="pagenum" title="230"><a name="Page_230" id="Page_230"></a></span>
+on the fact that there are many exceptions to his rule.
+In quite a number of cases the hybrids are of one or more
+types, which remain constant: there is no splitting at all
+in the second generation. But that does not affect the rule
+of Mendel in those cases where it is true. Where there
+is a “splitting” in the second generation, there also are the
+numerical proportions stated by Mendel; there never are
+other relations among the numbers of individuals of the
+mixed and of the two pure types than those given by his
+rule. I regard it as very important that this real meaning
+of Mendel’s principle should be most clearly understood.</p>
+
+<p>From the fact of the splitting of hybrids in the second
+generation most important consequences may be drawn for
+the theory of inheritance; the split individuals, if crossed
+with each other, always give an offspring which remains
+pure; there is no further splitting and no other change
+whatever. The germ-cells produced by the split individuals
+of the second generation may therefore be said to be
+“pure,” as pure as were those of the grandparents. But
+that is as much as to say that the pureness of the germ-cells
+has been preserved in spite of their passing through
+the “impure” generation of the hybrids, and from this fact
+it follows again that the union of characters in the hybrids
+must have been such as to permit pure separation: in
+fact, the germ-cells produced by Mendelian hybrids may
+hypothetically be regarded as being pure <span class="nowrap">themselves.<a name="FNanchor_131_131" id="FNanchor_131_131"></a><a href="#Footnote_131_131" class="fnanchor">131</a></span></p>
+
+<p>We have not yet considered one feature of all experi<span class="pagenum" title="231"><a name="Page_231" id="Page_231"></a></span>ments
+in hybridisation, which indeed seems to be the most
+important of all for the theory of inheritance, if taken
+together with the fact of the pureness of the germs. The
+rule of Mendel always relates to one single character of
+the species or varieties concerned in hybridisation, and if
+it deals with more than one character, it regards every one
+of them separately; indeed, the rule holds for every one
+of them irrespective of the others. We cannot study here
+how this most important fact of the independence of the
+single characters of a species with regard to inheritance
+leads to the production of new races, by an abnormal
+mixture of those characters. We only take advantage of
+the fact theoretically, and in doing so, I believe, we can
+hardly escape the conclusion that the independence of
+the single characters in inheritance, taken together with
+the pureness of the germ-cells in the most simple form
+of hybrids, proves that there occurs in inheritance a sort
+of handing over of single and separate morphogenetic
+agents which relate to the single morphogenetic characters
+of the adult. We may use Bateson’s word “allelomorphs”
+for these agents, or units, as they may be called, thereby
+giving expression to the fact that the single and separate
+units, which are handed over in inheritance, correspond to
+each other in nearly related species without being the same.</p>
+
+<p>And so we have at least an inkling of what the material
+continuity of inheritance is to mean, though, of course, our
+“single and separate morphogenetic agents,” or “units” or
+“allelomorphs” are in themselves not much more than
+unknown somethings described by a word; but even then
+they are “somethings.”</p>
+
+<p>Besides the researches relating to the rule of Mendel<span class="pagenum" title="232"><a name="Page_232" id="Page_232"></a></span>
+and its exceptions, founded, that is, upon a study of the
+“second” generation of hybrids, there is another important
+line of research lately inaugurated by Herbst, which investigates
+the first generation in hybridisation. The hybrids
+themselves are studied with the special purpose of finding
+out whether the type of the single hybrid may change
+according to the conditions of its development, both outer
+and inner. The discoveries thus made may lead some day to
+a better understanding of the intimate nature of the “units”
+concerned in heredity, and perhaps to some knowledge of
+the arranging and ruling factor in morphogenesis also.</p>
+
+<p>Starting from the discovery of Vernon, that the hybrids
+of sea-urchins are of different types according to the
+season, <span class="nowrap">Herbst<a name="FNanchor_132_132" id="FNanchor_132_132"></a><a href="#Footnote_132_132" class="fnanchor">132</a></span> was able to show that differences among
+the hybrids with regard to their being more of the paternal
+or more of the maternal type, are in part certainly due to
+differences in temperature. But there proved to be still another
+factor at work, and Herbst has succeeded in discovering this
+factor by changing the internal conditions of morphogenesis.
+Whenever he forced the eggs of <i class="biological-name">Sphaerechinus</i> to enter into
+the <span class="nowrap">first<a name="FNanchor_133_133" id="FNanchor_133_133"></a><a href="#Footnote_133_133" class="fnanchor">133</a></span> phase of artificial parthenogenesis and then fertilised
+them with the sperm of <i class="biological-name">Echinus</i>, he was able to approximate
+the offspring almost completely to the maternal type, whilst
+under ordinary conditions the hybrids in question follow
+the paternal far more than the maternal organisation.</p>
+
+<p>What is shown, in the first place, by these discoveries<span class="pagenum" title="233"><a name="Page_233" id="Page_233"></a></span>
+is the importance of an arranging and ruling factor in spite
+of all units. The organism is always one <em>whole</em> whether the
+paternal properties prevail or the more complicated maternal
+ones; in other words, all so-called properties that consist in the
+<em>spatial relations of parts</em> have nothing to do with “units” or
+“allelomorphs,” which indeed cannot be more than necessary
+means or materials, requiring to be ordered. As to the
+character of the morphogenetic single and separate units
+themselves Herbst is inclined to regard them as specific
+chemical substances which unite correspondingly during
+nuclear conjugation, forming a sort of loose chemical
+compound. It would depend on the constitution of this
+compound whether germ-cells of hybrids could become
+pure or not.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Rôle of the Nucleus in Inheritance</span></p>
+
+<p>At the end of our studies on heredity we hardly can
+avoid saying a few words about the problem of the localisation
+of the morphogenetic units in the germ-cells themselves.
+Is it in the protoplasm or in the nucleus that they are
+placed? You all know that this question was for a long
+time regarded as more important than any other, and
+perhaps you have already blamed me for not raising it
+until now. But in my opinion results gained by the
+purely analytical method and carefully established, are
+always superior to those which are of a merely descriptive
+nature and doubtful besides. The famous problem of
+the part played by the nucleus in inheritance is both
+descriptive and doubtful: it is only, so to say, of factual,
+not of analytical importance, and quite insoluble at present.</p>
+
+<p><span class="pagenum" title="234"><a name="Page_234" id="Page_234"></a></span></p>
+
+<p>As for our second proof of vitalism, stating that no kind
+of machine inside the germ-cells can possibly be the
+foundation of their morphogenesis, it is clear that the
+protoplasm and the nucleus may both come into account
+here on equal terms. If you prefer to say so, it is to the
+nucleus and to its division in particular that the second
+proof of autonomy relates, while the first, though not over-looking
+the presence of <span class="nowrap">nuclei,<a name="FNanchor_134_134" id="FNanchor_134_134"></a><a href="#Footnote_134_134" class="fnanchor">134</a></span> deals “especially” with the
+protoplasmic nature of its “systems.”</p>
+
+<p>What then can we say, on the basis of actual facts, about
+the part taken by the protoplasm and by the nucleus in
+inheritance, now that we have learnt from our analytical
+discussion that both of them cannot be any kind of
+morphogenetic machine, but can only be means of morphogenesis?
+Let us state our question in the following way:
+whereabouts in the germ-cells are those “means” of
+morphogenesis localised, the existence of which we infer
+from the material continuity in the course of generations
+in general and from the facts discovered about hybridisation
+in particular?</p>
+
+<p>The first of the facts generally said to support the
+view that the nucleus of the germ-cells exerts a specified
+influence upon the processes of development and inheritance,
+relates to the proportion between protoplasm and nuclear<span class="pagenum" title="235"><a name="Page_235" id="Page_235"></a></span>
+material in the egg and in the spermiae. This proportion
+is very different in the two sexual products, as we know,
+there being an enormous preponderance of the protoplasm
+in the egg, of the nucleus in the spermatozoon. This seems
+to indicate that the proportion between protoplasm and
+nucleus is fairly indifferent for inheritance, as all the facts
+go to show that inheritance from the father is as common
+as inheritance from the mother. It is in the nucleus, and
+in the nucleus alone, that any similarity of organisation
+exists between the two sexual products, so very different
+in all other respects: therefore the nucleus should be the
+organ of inheritance. The phenomena of nuclear division,
+of karyokinesis, which are quite equal in both sexual cells,
+are certainly well fitted to support this hypothesis.</p>
+
+<p>There seems indeed to be some truth in this reasoning,
+but nevertheless it must remain hypothetical; and it must
+never be forgotten that there may be very probably some
+sort of morphogenetic importance in protoplasm also. Rauber
+and afterwards <span class="nowrap">Boveri<a name="FNanchor_135_135" id="FNanchor_135_135"></a><a href="#Footnote_135_135" class="fnanchor">135</a></span> have tried to prove experimentally
+that it is on the nuclear chromatic substance only that
+inheritance depends, but the first of these authors failed
+to get any results at all, and the latter obtained only ambiguous
+ones. Godlewski, on the contrary, has fertilised
+purely protoplasmic egg-fragments of the sea-urchin with
+the sperm of quite another group of Echinoderms, and
+obtained in spite of that a few stages of development of the<span class="pagenum" title="236"><a name="Page_236" id="Page_236"></a></span>
+pure maternal type. This experiment seems to place the
+morphogenetic importance of protoplasm beyond all doubt.</p>
+
+<p>I should prefer not to make any definite statement
+about our problem at present. Our actual knowledge
+of the organisation and metabolism of both nucleus and
+protoplasm is so extremely small and may relate to such
+very insignificant topics, that any definite decision is impossible.
+I myself believe that the nucleus plays an
+important part in heredity, perhaps even a greater one
+than protoplasm, but this is only my <span class="nowrap">belief.<a name="FNanchor_136_136" id="FNanchor_136_136"></a><a href="#Footnote_136_136" class="fnanchor">136</a></span></p>
+
+<p>The discovery of Gruber and others, that Protozoa are
+only capable of restitution if they contain at least a fragment
+of the nucleus, has also been used occasionally as a
+proof of the morphogenetic importance of the nucleus. But
+might not this absence of restitution where nuclear
+material is lacking be understood equally well on the
+hypothesis of Loeb and R. S. Lillie that the nucleus is a
+centre of oxidation in the cell? Remove the heart from
+a vertebrate and the animal will not digest any more; but
+in spite of that the heart is not the organ of digestion.</p>
+
+<p>And so we lay stress once more upon this point: that
+the experimental results of hybridisation and the analytical
+results obtained by the discussion of the complex-equipotential
+systems are of greater value to the theory
+of heredity than all speculation about the importance or
+unimportance of special constituents of the cell, of whose
+organisation, chemistry, and physics, scarcely anything is
+known at <span class="nowrap">present.<a name="FNanchor_137_137" id="FNanchor_137_137"></a><a href="#Footnote_137_137" class="fnanchor">137</a></span></p>
+<p><span class="pagenum" title="237"><a name="Page_237" id="Page_237"></a></span></p>
+
+<p class="tac pt12b02em"><span class="smcap">Variation and Mutation</span></p>
+
+<p>Heredity, it has been said, may be understood as resting
+upon the fact that each organism forms its own initial
+stage again, and that this initial stage always encounters
+conditions of the same kind.</p>
+
+<p>If this statement were quite correct, all the individuals
+of a given species would be absolutely alike everywhere
+and for ever. But they are not alike; and that they are
+not alike everywhere and for ever is not merely the only
+real foundation of the so-called theory of descent we
+possess, but also forces us to change a little our definition
+of heredity, which now proves to have been only a sort of
+approximation to the truth, convenient for analytical
+discussion.</p>
+
+<p>In the first place, the conditions which surround the
+initial stages of morphogenesis are not quite equal in every
+respect: and indeed the offspring of a given pair of parents,
+or better, to exclude all complications resulting from
+sexual reproduction, or amphimixis, as Weismann called
+it&mdash;the offspring of one given parthenogenetic female are
+not all equal among themselves. The individuals of each
+generation are well known to vary, and it is especially in
+this country that the so-called individual or fluctuating<span class="pagenum" title="238"><a name="Page_238" id="Page_238"></a></span>
+variation has been most carefully studied by statistical
+methods, Galton and Weldon being the well-known
+pioneers in this <span class="nowrap">field.<a name="FNanchor_138_138" id="FNanchor_138_138"></a><a href="#Footnote_138_138" class="fnanchor">138</a></span> In fact, if we are allowed to assume
+that this sort of variation is the outcome of a variation of
+conditions&mdash;in the most general meaning of the word&mdash;we
+only follow the opinion which has almost universally
+been adopted by the <span class="nowrap">biologists<a name="FNanchor_139_139" id="FNanchor_139_139"></a><a href="#Footnote_139_139" class="fnanchor">139</a></span> that are working at this
+branch of the subject. Variation proper is now generally
+allowed to be the consequence of variations in nutrition;
+the contingencies of the latter result in contingencies
+of the former, and the law of contingencies is the same
+for both, being the most general law of probability. Of
+course under such an aspect fluctuating variation could
+hardly be called an exception, but rather an addition to
+inheritance.</p>
+
+<p>But there are other restrictions of our definition of
+heredity. The initial stage which is formed again by an
+organism is not always quite identical in itself with the
+initial stage of its own parent: Bateson and de Vries
+were the first to study in a systematic way these real <span class="nowrap">exceptions<a name="FNanchor_140_140" id="FNanchor_140_140"></a><a href="#Footnote_140_140" class="fnanchor">140</a></span>
+to true inheritance. As you know, de Vries has
+given them the name of “mutations.” What is actually
+known on this subject is not much at present, but nevertheless
+is of great theoretical value, being the only real<span class="pagenum" title="239"><a name="Page_239" id="Page_239"></a></span>
+foundation of all theories of descent, as we shall see in the
+next lectures. “Mutations” are known to exist at present
+only among some domesticated animals and plants. Nothing
+of a more general character can be said about their law or
+<span class="nowrap">meaning.<a name="FNanchor_141_141" id="FNanchor_141_141"></a><a href="#Footnote_141_141" class="fnanchor">141</a></span></p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="240"><a name="Page_240" id="Page_240"></a></span></p>
+
+
+<h3><span class="smcap">Conclusions from the First Main Part of these
+Lectures</span></h3>
+
+
+<p>In finishing our chapter on inheritance, we at the same
+time have finished the first main part of our lectures; that
+part of them which has been devoted exclusively to the
+study of the morphogenesis of the <em>individual</em>, including
+the functioning of the adult individual form. We now
+turn to our second part, which is to deal with the problems
+of the diversities of individual forms, with morphological
+systematics. The end of our chapter on inheritance has
+already led us to the threshold of this branch of biological
+science.</p>
+
+<p>The chief result of the first main part of our lectures
+has been to prove that an autonomy of life phenomena
+exists at least in some departments of individual morphogenesis,
+and probably in all of them; the real starting-point
+of all morphogenesis cannot be regarded as a machine,
+nor can the real process of differentiation, in all cases
+where it is based upon systems of the harmonious equipotential
+type. There cannot be any sort of machine in
+the cell from which the individual originates, because this
+cell, including both its protoplasm and its nucleus, has
+undergone a long series of divisions, all resulting in equal
+products, and because a machine cannot be divided and in<span class="pagenum" title="241"><a name="Page_241" id="Page_241"></a></span>
+spite of that remain what it was. There cannot be, on the
+other hand, any sort of machine as the real foundation of
+the whole of an harmonious system, including many cells
+and many nuclei, because the development of this system
+goes on normally, even if its parts are rearranged or partly
+removed, and because a machine would never remain what
+it had been in such cases.</p>
+
+<p>If our analytical discussions have thus led us to establish
+a typical kind of vitalism, it follows that we can by no
+means agree with Wilhelm Roux in his denomination of
+the analytical science of the individual form and form-production
+as “Entwickelungsmechanik,” “developmental
+mechanics,” a title, which, of course, might easily be
+transformed into that of “morphogenetic mechanics,” to
+embrace not only normal development, but restitution and
+adaptation too. We feel unable to speak of “mechanics”
+where just the contrary of mechanics, in the proper meaning
+of the word, has been proved to exist.</p>
+
+<p>Names of course are of comparatively small importance,
+but they should never be allowed to be directly misleading,
+as indeed the term “Entwickelungsmechanik” has already
+proved to be. Let us rather say, therefore, that we have
+finished with this lecture that part of our studies in biology
+which has had to deal with morphogenetic physiology or
+physiological morphogenesis.</p>
+
+<p>Once more we repeat, at this resting-point in our
+discussions, that both of our proofs of life-autonomy have
+been based upon a careful analysis of certain facts about
+the distribution of morphogenetic potencies in two classes
+of morphogenetic systems, and upon nothing else. To
+recall only one point, we have not said that regeneration,<span class="pagenum" title="242"><a name="Page_242" id="Page_242"></a></span>
+merely because it is a kind of restitution of the disturbed
+whole, compels us to admit that biological events happen
+in a specific and elemental manner, but, indeed, regeneration
+<em>does</em> prove vitalism, because it is founded upon the existence
+of certain complex-equipotential systems, the analysis of
+the genesis of which leads to the understanding of life-autonomy.
+This distinction, in fact, is of the greatest
+logical importance.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="243"><a name="Page_243" id="Page_243"></a></span></p>
+
+
+
+
+<h2>PART II</h2>
+
+<h2>SYSTEMATICS AND HISTORY</h2>
+
+<h3><i>A.</i> THE PRINCIPLES OF SYSTEMATICS</h3>
+
+
+<p class="tac pt12b02em"><span class="smcap">Rational Systematics</span></p>
+
+<p>All systematics which deserves the predicate “rational” is
+founded upon a concept or upon a proposition, by the aid of
+which a totality of specific diversities may be understood.
+That is to say: every system claiming to be rational gives
+us a clue by which we are able to apprehend either
+that there cannot exist more than a certain number of
+diversities of a certain nature, or that there can be an
+indefinite number of them which follow a certain law with
+regard to the character of their differences.</p>
+
+<p>Solid geometry, which states that only five regular
+bodies are possible, and points out the geometrical nature of
+these bodies, is a model of what a rational system should be.
+The theory of conic sections is another. Take the general
+equation of the second degree with two unknowns, and
+study all the possible forms it can assume by a variation
+of its constants, and you will understand that only four
+different types of conic sections are possible&mdash;the circle, the
+ellipse, the hyperbola, and the parabola.</p>
+
+<p><span class="pagenum" title="244"><a name="Page_244" id="Page_244"></a></span></p>
+
+<p>In physics and chemistry no perfect rational systems
+have been established hitherto, but there are many systems
+approaching the ideal type in different departments of these
+sciences. The chemical type of the monohydric saturated
+alcohols, for instance, is given by the formula C<sub>n</sub>H<sub>2n+1</sub>OH,
+and in this formula we not only have an expression of the
+law of composition which all possible alcohols are to follow,&mdash;but,
+since we know empirically the law of quantitative
+relation between <i>n</i> and various physical properties, we also
+possess in our formula a general statement with respect to
+the totality of the properties of any primary alcohol that
+may be discovered or prepared in the future. But chemistry
+has still higher aims with regard to its systematics: all of
+you know that the so-called “periodic law of the elements”
+was the first step towards a principle that may some day
+give account of the relation of all the physical and chemical
+properties of any so-called element with its most important
+constant, the atomic weight, and it seems to be reserved for
+the present time to form a real fundamental system of the
+“elements” on the basis of the periodic law by the aid of
+the theory of electrons. Such a fundamental system of the
+elements would teach us that there can only be so many
+elements and no more, and only of such a kind. In
+crystallography a similar end has been reached already by
+means of certain hypothetic assumptions, and systematics
+has here accounted for the limited number and fixed character
+of the possible forms of crystalline symmetry.</p>
+
+<p>It is not difficult to understand the general logical type
+of all rational systems, and logic indeed can discover it without
+appealing to concrete sciences or to geometry. Rational
+systematics is always possible whenever there exists any<span class="pagenum" title="245"><a name="Page_245" id="Page_245"></a></span>
+fundamental concept or proposition which carries with it a
+principle of division; or to express it somewhat differently,
+which would lead to contradictions, if division were to be
+tried in any but one particular manner. The so-called
+“genus,” as will easily be perceived, then embraces all its
+“species” in such a manner that all peculiarities of the
+species are represented already in properties of the genus,
+only in a more general form, in a form which is still unspecified.
+The genus is both richer in content and richer in
+extent than are the species, though it must be added that
+its richness in content is, as it were, only latent: but it
+may come into actuality by itself and without any help
+from without.</p>
+
+<p>We are dealing here with some of the most remarkable
+properties of the so-called synthetic judgments <i lang="la" xml:lang="la">a priori</i> in
+the sense of Kant, and, indeed, it seems that rational
+systematics will only be possible where some concept of the
+categorical class or some proposition based upon such
+concept lies at the root of the matter or at least is connected
+with it in some way. In fact, all rational systems with
+regard to the relations of symmetry in natural bodies deal
+ultimately with space; or better, all systems in such fields
+are able to become rational only if they happen to turn into
+questions of spatial symmetry.</p>
+
+<p>All other genera and species, whether of natural bodies
+or of facts, can be related only on the basis of empirical
+abstraction, <i>i.e.</i> can never attain rationality: here, indeed,
+the genus is richer in extent and poorer in content than
+are the species. The genus is transformed into the species,
+not by any inherent development of latent properties, but
+by a mere process of addition of characteristic points. It is<span class="pagenum" title="246"><a name="Page_246" id="Page_246"></a></span>
+impossible to deduce the number or law or specifications of
+the species from the genus. Mere “classification,” if we
+may reserve the honorable name of systematics for the
+rational type, is possible here, a mere statement in the form
+of a catalogue, useful for orientation but for nothing more.
+We may classify all varieties of hats or of tables in the
+same way.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Biological Systematics</span></p>
+
+<p>At this point we return from our logical excursion
+to our proper subject of biology; for I am sorry to
+say biological systematics is at present of our second
+type of systematics throughout: it is classification pure
+and simple. We have a catalogue in our hands, but
+nothing more.</p>
+
+<p>Such a statement of fact conveys not a particle of
+censure, casts not the least reflection on the gifted men
+who created the classification of animals or plants. It is
+absolutely necessary to have such a catalogue, and indeed the
+catalogue of the organisms can be said to have been
+improved enormously during the advance of empirical and
+descriptive biological science. Any classification improves
+as it becomes more “natural,” as the different possible
+schemes of arrangement, the different reasons of division,
+agree better and better in their results; and, in fact, there
+has been a great advance of organic classification in this
+direction. The “natural” system has reached such perfection,
+that what is related from one point of view seems
+nearly related also from almost all points of view which are
+applicable, at least from those which touch the most<span class="pagenum" title="247"><a name="Page_247" id="Page_247"></a></span>
+important characteristics. There has been a real weighing
+of all the possible reasons of division, and that has led to a
+result which seems to be to some extent final.</p>
+
+<p>But, nevertheless, we do not understand the <i lang="fr" xml:lang="fr">raison
+d’être</i> of the system of organisms; we are not at all able
+to say that there must be these classes or orders or
+families and no others, and that they must be such as
+they are.</p>
+
+<p>Shall we ever be able to understand that? Or will
+organic systematics always remain empirical classification?
+We cannot answer this question. If we could, indeed, we
+should have what we desire! As simple relations of space
+are certainly not the central point of any problematic
+rational organic systematics even of the future, the question
+arises, whether there could be found any principle of
+another type in the realm of synthetic <i lang="la" xml:lang="la">a priori</i> judgments
+which could allow an inherent sort of evolution of latent
+diversities, as do all judgments about spatial symmetry. At
+the end of the second course of these lectures, which is to be
+delivered next summer, we shall be able to say a few more
+words about this important point.</p>
+
+<p>The concept of what is called “a type,” due almost
+wholly to Cuvier and Goethe, is the most important of
+all that classification has given to us. Hardly second in
+importance is the discovery of the “correlation of parts,” as
+a sort of connection which has the character of necessity
+without being immediately based upon causality. Rádl
+seems to be the only modern author who has laid some
+stress on this topic. The harmony which we have discovered
+in development is also part of this correlation.
+When, later on, we come to discuss analytically our well<span class="pagenum" title="248"><a name="Page_248" id="Page_248"></a></span>
+established entelechy as the ultimate basis of individual
+organisation, we shall be able to gain more satisfactory
+ideas with respect to the meaning of the non-causal but
+necessary connection, embraced in the concepts of type and
+of correlation of parts.</p>
+
+<p>The type is a sort of irreducible arrangement of
+different parts; the correlation deals with the degree and
+the quality of what may be called the actual make of the
+parts, in relation to one another: all ruminants, for
+instance, are cloven-footed, the so-called dental formulae
+are characteristic of whole groups of mammals. Of course
+all such statements are empirical and have their limits:
+but it is important that they are <span class="nowrap">possible.<a name="FNanchor_142_142" id="FNanchor_142_142"></a><a href="#Footnote_142_142" class="fnanchor">142</a></span></p>
+
+<p>It has been the chief result of comparative embryology
+to show that the type as such is more clearly expressed in
+developmental stages than it is in the adults, and that therefore
+the embryological stages of different groups may be very
+much more similar to each other than are the adults:
+that is the truth contained in the so-called “biogenetisches
+Grundgesetz.” But the specific differences of the species
+are not wanting in any case of ontogeny, in spite of such
+similarities in different groups during development.</p>
+
+<p>We have applied the name “systematics” or, if rationality
+is excluded, “classification” to all that part of a science
+which deals with diversities instead of generalities: in such
+a wide meaning systematics, of course, is not to be confused
+with that which is commonly called so in biology, and
+which describes only the exterior differences of form.<span class="pagenum" title="249"><a name="Page_249" id="Page_249"></a></span>
+Our systematics is one of the two chief parts of biology;
+what are called comparative anatomy and comparative
+embryology are its methods. For it must be well understood
+that these branches of research are only methods
+and are not sciences by themselves.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="250"><a name="Page_250" id="Page_250"></a></span></p>
+
+
+
+
+<h3><i>B.</i> THE THEORY OF DESCENT</h3>
+
+
+<h4 class="fs120">1. <span class="smcap">Generalities</span></h4>
+
+<p>It is most generally conceded at the present time that
+the actually existing state of all organisms whatsoever is
+the result of their history. What does that mean? What
+are the foundations upon which the assumption rests?
+What is the relation of systematics to history? In raising
+such questions and considerations we are treading the
+ground sacred to the theory of descent.</p>
+
+<p>I well know that you prefer the name “theory of
+evolution” for what I am speaking of: but it may be
+misleading in various respects. We already know that quite
+a determinate meaning has been given to the word “evolutio”
+as applied to individual morphogenesis, “evolutio”
+being here opposed to “epigenesis.” Now there would be
+nothing against the use of the word evolution in a wider
+sense&mdash;indeed it is often applied nowadays to denote
+the fact that a something is actually “evolved” in
+embryology&mdash;if only our entelechy had taken the place of
+the machine of the mechanists. But that is the very
+point: there must be a real “evolving” of a something,
+in order that the word evolution may be justified verbally:
+and that is not the case in so-called phylogeny. At least<span class="pagenum" title="251"><a name="Page_251" id="Page_251"></a></span>
+we know nothing of an evolutionary character in the
+problematic pedigree of the organisms, as we shall see more
+fully hereafter. The term “theory of descent” is therefore
+less open to objection than is the usual English term.
+The word transformism, as used by the French, would also
+be a very good title.</p>
+
+<p>The theory of descent is the hypothetic statement that
+the organisms are really allied by blood among each other,
+in spite of their <span class="nowrap">diversities.<a name="FNanchor_143_143" id="FNanchor_143_143"></a><a href="#Footnote_143_143" class="fnanchor">143</a></span> The question about their
+so-called monophyletic or polyphyletic origin is of secondary
+importance compared with the statement of relationship in
+general.</p>
+
+<p>There are two different groups of facts which have
+suggested the idea of transformism: none of these facts can
+be said to be conclusive, but there certainly is a great
+amount of probability in the whole if taken together.</p>
+
+<p>The first group of evidences which lead to the hypothesis
+of the real relationship of organisms consists of facts relating
+to the geographical distribution of animals and plants and
+to palæontology. As to geography, it seems to me that the
+results of the floral and faunal study of groups of islands<span class="pagenum" title="252"><a name="Page_252" id="Page_252"></a></span>
+are to be mentioned in the first place. If, indeed, on each
+of the different islands, <i>A</i> <i>B</i> <i>C</i> and <i>D</i>, forming a group,
+the species of a certain genus of animals or plants are
+different in a certain respect, and show differences also
+compared with the species living on the neighbouring
+continent, of which there is geological evidence that the
+islands once formed a part, whilst there is no change in
+the species on the continent itself for very wide areas, then,
+no doubt, the hypothesis that all these differing species
+once had a common origin, the hypothesis that there is a
+certain community among them all, will serve to elucidate
+in some way what would seem to be very abstruse without
+it. And the same is true of the facts of palaeontology.
+In the geological strata, forming a continuous series, you
+find a set of animals, always typical and specific for every
+single stratigraphical horizon, but forming a series just as
+do those horizons. Would not the whole aspect of these
+facts lose very much of its peculiarity if you were to
+introduce the hypothesis that the animals changed with
+the strata? The continuity of life, at least, would be
+guaranteed by such an assumption.</p>
+
+<p>The geographical and geological evidences in favour of
+the theory of descent are facts taken from sciences
+which are not biology proper; they are not facts of the
+living but only facts about the living. That is not quite
+without logical importance, for it shows that not biology
+alone has led to the transformism hypothesis. Were it otherwise,
+transformism might be said to be a mere hypothesis
+<i lang="la" xml:lang="la">ad hoc</i>; but now this proves to be not the case, though
+we are far from pretending that transformism might be
+regarded as resting upon a real <i lang="la" xml:lang="la">causa vera</i>.</p>
+
+<p><span class="pagenum" title="253"><a name="Page_253" id="Page_253"></a></span></p>
+
+<p>But let us study the second group of facts which
+support the theory of descent. It is a group of evidences
+supplied by biology itself that we meet here, there being
+indeed some features in biology which can be said to gain
+some light, some sort of elucidation, if the theory of descent
+is accepted. Of course, these facts can only be such as
+relate to specific diversities, and indeed are facts of
+systematics; in other words, there exists something in
+the very nature of the system of organisms that renders
+transformism probable. The system of animals and plants
+is based upon a principle which might be called the
+principle of <em>similarities and diversities by gradation</em>; its
+categories are not uniform but different in degree and
+importance, and there are different kinds of such differences.
+No doubt, some light would be shed upon this character
+of the system, if we were allowed to assume that the relation
+between similarities and diversities, which is gradual,
+corresponded to a blood-relationship, which is gradual also.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE COVERT PRESUMPTION OF ALL THEORIES OF DESCENT</span></p>
+
+<p>We have used very neutral and somewhat figurative
+words, in order to show what might be called the logical
+value of the theory of descent, in order to signify its
+value with respect to so-called “explanation.” We have
+spoken of the “light” or the “elucidation” which it brings,
+of the “peculiarity of aspect” which is destroyed by it.
+We have used this terminology intentionally, for it is very
+important to understand that a specific though hidden
+addition is made almost unconsciously to the mere statement
+of the hypothesis of descent as such, whenever this<span class="pagenum" title="254"><a name="Page_254" id="Page_254"></a></span>
+hypothesis is advocated in order to bring light or elucidation
+into any field of systematic facts. And this additional
+hypothesis indeed must be made from the very beginning,
+quite irrespective of the more detailed problems of the law
+of transformism, in order that <em>any</em> sort of so-called explanation
+by means of the theory of descent may be possible
+at all. Whenever the theory that, in spite of their
+diversities, the organisms are related by blood, is to be really
+useful for explanation, it must necessarily be assumed in
+every case that the steps of change, which have led the
+specific form <i>A</i> to become the specific form <i>B</i>, have been
+such as only to change <em>in part</em> that original form <i>A</i>.
+That is to say: the similarities between <i>A</i> and <i>B</i> must
+never have become overshadowed by their diversities.</p>
+
+<p>Only on this assumption, which indeed is a newly
+formed additional subsidiary hypothesis, joined to the
+original hypothesis of descent in general&mdash;a hypothesis
+regarding the very nature of transformism&mdash;only on this
+almost hidden assumption is it possible to speak of any
+sort of “explanation” which might be offered by the
+theory of transformism to the facts of geography, geology,
+and biological systematics. Later on we shall study more
+deeply the logical nature of this “explanation”; at present
+it must be enough to understand this term in its quasi-popular
+meaning.</p>
+
+<p>What is explained by the hypothesis of descent&mdash;including
+the additional hypothesis, that there always is a
+prevalence of the similarities during transformism&mdash;is the
+fact that in palaeontology, in the groups of island and
+continent faunae and florae taken as a whole, as well as in
+the single categories of the system, the similarities exceed<span class="pagenum" title="255"><a name="Page_255" id="Page_255"></a></span>
+the diversities. The <em>similarities</em> now are “explained”;
+that is to say, they are understood as resting on but one
+principle: the similarities are understood as being due to
+<span class="nowrap">inheritance;<a name="FNanchor_144_144" id="FNanchor_144_144"></a><a href="#Footnote_144_144" class="fnanchor">144</a></span> and now we have but one problem instead
+of an indefinite number. For this reason Wigand granted
+that the theory of descent affords what he calls a numerical
+reduction of problems.</p>
+
+<p>Understanding then what is explained by the theory
+of descent with its necessary appendix, we also understand
+at once what is <em>not</em> elucidated by it: the diversities of the
+organism remain as unintelligible as they always were,
+even if we know that inheritance is responsible for
+what is similar or equal. Now there can be no doubt
+that the diversities are the more important point in
+systematics; if there were only similarities there would
+be no problem of systematics, for there would be no system.
+Let us be glad that there are similarities in the diversities,
+and that these similarities have been explained in some
+way; but let us never forget what is still awaiting its
+explanation. Unfortunately it has been forgotten far too
+often.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE SMALL VALUE OF PURE PHYLOGENY</span></p>
+
+<p>And so we are led to the negative side of the theory
+of transformism, after having discussed its positive half.
+The theory of descent as such, without a real knowledge<span class="pagenum" title="256"><a name="Page_256" id="Page_256"></a></span>
+of the factors which are concerned in transformism, or of
+the law of transformism, in other terms, leaves the problem
+of systematics practically where it was, and adds really
+nothing to its solution. That may seem very deplorable,
+but it is true.</p>
+
+<p>Imagine so-called historical geology, without any knowledge
+of the physical and chemical factors which are
+concerned in it: what would you have except a series of
+facts absolutely unintelligible to you? Or suppose that
+some one stated the cosmogenetic theory of Kant and Laplace
+without there being any science of mechanics: what would
+the theory mean to you? Or suppose that the whole
+history of mankind was revealed to you, but that you
+had absolutely no knowledge of psychology: what would
+you have but facts and facts and facts again, with not a
+morsel of real explanation?</p>
+
+<p>But such is the condition in which so-called phylogeny
+stands. If it is based only on the pure theory of transformism,
+there is nothing explained at all. It was for this
+reason that the philosopher Liebmann complained of phylogeny
+that it furnishes nothing but a “gallery of ancestors.”
+And this gallery of ancestors set up in phylogeny is not
+even certain; on the contrary, it is absolutely uncertain,
+and very far from being a fact. For there is no sound
+and rational principle underlying phylogeny; there is
+mere fantastic speculation. How could it be otherwise
+where all is based upon suppositions which themselves
+have no leading principle at present? I should not like
+to be misunderstood in my polemics against phylogeny.
+I fully grant you that it may be possible in a few cases
+to find out the phylogenetic history of smaller groups with<span class="pagenum" title="257"><a name="Page_257" id="Page_257"></a></span>
+some probability, if there is some palaeontological evidence
+in support of pure comparative anatomy; and I also do
+not hesitate to allow that such a statement would be of
+a certain value with regard to a future discovery of the
+“laws” of descent, especially if taken together with the
+few facts known about mutations. But it is quite another
+thing with phylogeny on the larger scale. Far more
+eloquent than any amount of polemics is the fact that
+vertebrates, for instance, have already been “proved” to
+be descended from, firstly, the amphioxus; secondly, the
+annelids; thirdly, the <i class="biological-name">Sagitta</i> type of worms; fourthly,
+from spiders; fifthly, from <i class="biological-name">Limulus</i>, a group of crayfishes;
+and sixthly, from echinoderm larvae. That is the extent
+of my acquaintance with the literature, with which I do not
+pretend to be specially familiar. Emil du Bois-Reymond
+said once that phylogeny of this sort is of about as much
+scientific value as are the pedigrees of the heroes of Homer,
+and I think we may fully endorse his opinion on this
+point.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HISTORY AND SYSTEMATICS</span></p>
+
+<p>A few words should be devoted to the relations between
+history and systematics in biology. Is there no contradiction
+between historical development and a true and
+rational system which, we conceded, might exist some
+day in biological sciences, even though it does not at
+present? By no means. A totality of diversities is
+regarded from quite different points of view if taken as
+the material of a system, and if considered as realised in
+time. We have said that chemistry has come very near
+to proper rational systematics, at least in some of its<span class="pagenum" title="258"><a name="Page_258" id="Page_258"></a></span>
+special fields; but the compounds it deals with at the
+same time may be said to have originated historically also,
+though not, of course, by a process of propagation. It is
+evident at once that the geological conditions of very early
+times prohibited the existence of certain chemical compounds,
+both organic and inorganic, which are known at
+present. None the less these compounds occupy their
+proper place in the system. And there may be many
+substances theoretically known to chemical systematics
+which have never yet been produced, on account of the
+impossibility of arranging for their proper conditions of
+appearance, and nevertheless they must be said to “exist.”
+“Existence,” as understood in systematics, is independent
+of special space and of special time, as is the existence of
+the laws of nature: we may speak of a Platonic kind of
+existence here. Of course it does not contradict this sort
+of ideal existence if reality proper is added to it.</p>
+
+<p>Thus the problem of systematics remains, no matter
+whether the theory of descent be right or wrong. There
+always remains the question about the totality of diversities
+in life: whether it may be understood by a general principle,
+and of what kind that principle would be. As, in
+fact, it is most probably by history, by descent, that
+organic systematics is brought about, it of course most probably
+will happen some day that the analysis of the causal
+factors concerned in the history will serve to discover the
+principle of systematics also.</p>
+
+<p>Let us now glance at the different kinds of hypotheses
+which have been established in order to explain how the
+descent of the organisms might have been possible. We
+have seen that the theory of transformism alone is not<span class="pagenum" title="259"><a name="Page_259" id="Page_259"></a></span>
+worth very much as a whole, unless at least a hypothetical
+picture can be formed of the nature of the transforming
+factors: it is by some such reasoning that almost every
+author who has defended the theory of descent in its
+universality tries to account for the manner in which
+organisms have acquired their present diversities.</p>
+
+<p><span class="pagenum" title="260"><a name="Page_260" id="Page_260"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">The Principles of Darwinism</span></h4>
+
+<p>There is no need in our times and particularly in this
+country, to explain in a full manner the theory known
+under the name of Darwinism. All of you know this
+theory, at least in its outlines, and so we may enter at once
+upon its analytic discussion. A few words only I beg you
+to allow me as to the name of “Darwinism” itself.
+Strange to say, Darwinism, and the opinion of Charles
+Darwin about the descent of organisms, are two different
+things. Darwin, the very type of a man devoted to science
+alone and not to personal interests,&mdash;Darwin was anything
+but dogmatic, and yet Darwinism is dogmatism in one of
+its purest forms. Darwin, for instance, gave the greatest
+latitude to the nature of the variations which form the
+battleground of the struggle for existence and natural
+selection; and he made great allowances for other causal
+combinations also, which may come into account besides
+the indirect factors of transformism. He was Lamarckian
+to a very far-reaching extent. And he had no definite
+opinion about the origin and the most intimate nature of
+life in general. These may seem to be defects but really
+are advantages of his theory. He left open the question
+which he could not answer, and, in fact, he may be said
+to be a good illustration of what Lessing says, that it is<span class="pagenum" title="261"><a name="Page_261" id="Page_261"></a></span>
+not the possession of truth but the searching after it, that
+gives happiness to man. It was but an outcome of this
+mental condition that Darwin’s polemics never left the
+path of true scientific discussions, that he never in all
+his life abused any one who found reason to combat his
+hypotheses, and that he never turned a logical problem
+into a question of morality.</p>
+
+<p>How different is this from what many of Darwin’s
+followers have made out of his doctrines, especially in
+Germany; how far is “Darwinism” removed from Darwin’s
+own teaching and character!</p>
+
+<p>It is to Darwinism of the <em>dogmatic</em> kind, however, that
+our next discussions are to relate, for, thanks to its
+dogmatism, it has the advantage of allowing the very sharp
+formulation of a few causal factors, which <i lang="la" xml:lang="la">a priori</i> might
+be thought to be concerned in organic transformism, though
+we are bound to say that a really searching analysis of
+these factors ought to have led to their rejection from the
+very beginning.</p>
+
+<p>The logical structure of dogmatic Darwinism reveals
+two different parts, which have nothing at all to do with
+one another.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">NATURAL SELECTION</span></p>
+
+<p>We shall first study that part of it which is known
+under the title of natural selection, irrespective of the
+nature of the causes of primary differences, or, in other
+words, the nature of variability. This part may be said
+to belong to Darwin’s personal teachings and not only to
+“Darwinism.” The offspring of a certain number of adults
+show differences compared with each other; there are more<span class="pagenum" title="262"><a name="Page_262" id="Page_262"></a></span>
+individuals in the offspring than can grow up under the
+given conditions, therefore there will be a struggle for
+existence amongst them, which only the fittest will survive;
+these survivors may be said to have been “selected” by
+natural means.</p>
+
+<p>It must be certain from the very beginning of analysis
+that natural selection, as defined here, can only eliminate
+what cannot survive, what cannot stand the environment
+in the broadest sense, but that natural selection never
+is able to create diversities. It always acts negatively
+only, never positively. And therefore it can “explain”&mdash;if
+you will allow me to make use of this ambiguous word&mdash;it
+can “explain” only why certain types of organic specifications,
+imaginable <i lang="la" xml:lang="la">a priori</i>, do <em>not</em> actually exist, but it never
+explains at all the existence of the specifications of animal
+and vegetable forms that are actually found. In speaking
+of an “explanation” of the origin of the living specific forms
+by natural selection one therefore confuses the sufficient
+reason for the non-existence of what there is not, with the
+sufficient reason for the existence of what there is. To say
+that a man has explained some organic character by
+natural selection is, in the words of Nägeli, the same as if
+some one who is asked the question, “Why is this tree
+covered with these leaves,” were to answer “Because the
+gardener did not cut them away.” Of course that would
+explain why there are no more leaves than those actually
+there, but it never would account for the existence and
+nature of the existing leaves as such. Or do we understand
+in the least why there are white bears in the Polar Regions
+if we are told that bears of other colours could not survive?</p>
+
+<p>In denying any real explanatory value to the concept<span class="pagenum" title="263"><a name="Page_263" id="Page_263"></a></span>
+of natural selection I am far from denying the action of
+natural selection. On the contrary, natural selection, to
+some degree, is <em>self-evident</em>; at least as far as it simply
+states that what is incompatible with permanent existence
+cannot exist permanently, it being granted that the
+originating of organic individuals is not in itself a
+guarantee of permanency. Chemical compounds, indeed,
+which decompose very rapidly under the conditions existing
+at the time when they originated may also be said
+to have been eliminated by “natural selection.” It is
+another question, of course, whether in fact all eliminations
+among organic diversities are exclusively due to the action
+of natural selection in the proper Darwinian sense. It
+has been pointed out already by several critics of
+Darwinism and most clearly by Gustav Wolff, that there
+are many cases in which an advantage with regard to
+situation will greatly outweigh any advantage in organisation
+or physiology. In a railway accident, for instance, the
+passengers that survive are not those who have the strongest
+bones, but those who occupied the best seats; and the
+eliminating effect of epidemics is determined at least as
+much by localities, <i>e.g.</i> special houses or special streets, as
+by the degree of immunity. But, certainly, natural selection
+is a <i lang="la" xml:lang="la">causa vera</i> in many other cases.</p>
+
+<p>We now may sum up our discussion of the first half
+of Darwinism. Natural selection is a negative, an eliminating
+factor in transformism; its action is self-evident to
+a very large degree, for it simply states that things do
+not exist if their continuance under the given conditions
+is impossible. To consider natural selection as a positive
+factor in descent would be to confound the sufficient reason<span class="pagenum" title="264"><a name="Page_264" id="Page_264"></a></span>
+for the non-existence of what is not, with the sufficient
+reason of what is.</p>
+
+<p>Natural selection has a certain important logical bearing
+on systematics, as a science of the future, which has scarcely
+ever been alluded to. Systematics of course has to deal
+with the totality of the possible, not only of the actual
+diversities; it therefore must remember that more forms
+may be possible than are actual, the word “possible”
+having reference in this connection to originating, not to
+surviving. Moreover, systematics is concerned not only
+with what has been eliminated by selection, but also with
+all that might have originated from the eliminated types.
+By such reasoning natural selection gains a very important
+aspect&mdash;but a logical aspect only.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">FLUCTUATING VARIATION THE ALLEGED CAUSE OF ORGANIC
+DIVERSITY</span></p>
+
+<p>The second doctrine of dogmatic Darwinism states that
+all the given diversities among the organisms that natural
+selection has to work upon are offered to natural selection
+by so-called fluctuating variation; that is, by variation as
+studied by means of statistics. This sort of variation,
+indeed, is maintained to be indefinite in direction and
+amount, at least by the most conservative Darwinians; it
+has occasionally been called a real differential; in any case
+it is looked upon as being throughout contingent with
+regard to some unity or totality; which, of course, is not to
+mean that it has not had a sufficient reason for occurring.</p>
+
+<p>It could hardly be said to be beyond the realm of
+possibility that such differences among organic species as<span class="pagenum" title="265"><a name="Page_265" id="Page_265"></a></span>
+only relate to degree or quantity and perhaps to numerical
+conditions also, might have been “selected” out of given
+contingent variations, if but one postulate could be regarded
+as fulfilled. This postulate may appropriately be stated
+as the fixation of new averages of variation by inheritance.
+Let the average value of a variation, with regard to a
+given property of a given species be <i>n</i> and let the value
+<i>n</i> + <i>m</i>&mdash;<i>m</i> being variable&mdash;which is represented in fewer
+individuals of course than is <i>n</i>, be such as to offer
+advantages in the struggle for existence; then the
+individuals marked by <i>n</i> + <i>m</i> will have the greater chance
+of surviving. Our postulate now states that, in order that
+a permanent increase of the average value of the variation
+in question may be reached, <i>n</i> + <i>m</i> in any of its variable
+forms must be able to become the average value of the
+second generation, as <i>n</i> was the average value of the first.
+Out of the second generation again it would be the few
+individuals marked by <i>n</i> + <i>m</i> + <i>o</i>, which would be selected;
+<i>n</i> + <i>m</i> + <i>o</i> would be the new average; afterwards <i>n</i> + <i>m</i> + <i>o</i> + <i>p</i>
+would be selected, would become the new average, and
+so on. A black variety for instance might be selected by
+such a series of processes out of a grey-coloured one without
+difficulty.</p>
+
+<p>But our postulate is not beyond all doubt: certain
+experiments, at least, which have been carried out about
+the summation of variations of the true fluctuating
+type by any kind of selection seem to show that there
+may be a real progress for a few generations, but that
+this progress is always followed by a reversion. Of course
+our experience is by no means complete on this subject,
+and, indeed, it may be shown in the future that positive<span class="pagenum" title="266"><a name="Page_266" id="Page_266"></a></span>
+transforming effects of fluctuating variability, in connection
+with selective principles, are possible in the case of new
+quantitative differences (in the widest sense), but we are
+not entitled to say so at present.</p>
+
+<p>And this is the only condition on which we can give
+credit to the second doctrine of dogmatic Darwinism. Its
+second principle, indeed, proves to be absolutely inadequate
+to explain the origin of any other kind of specific properties
+whatever.</p>
+
+<p>I cannot enter here into the whole subject of Darwinian
+<span class="nowrap">criticism.<a name="FNanchor_145_145" id="FNanchor_145_145"></a><a href="#Footnote_145_145" class="fnanchor">145</a></span> Our aims are of a positive character, they
+desiderate construction and only use destruction where it
+is not to be avoided. So I shall only mention that
+dogmatic Darwinism has been found to be unable to
+explain every kind of mutual adaptations, <i>e.g.</i> those existing
+between plants and insects; that it can never account
+for the origin of those properties that are indifferent to the
+life of their bearer, being mere features of organisation as
+an arrangement of parts; that it fails in the face of all
+portions of organisation which are composed of many
+different parts&mdash;like the eye&mdash;and nevertheless are
+functional units in any passive or active way; and that, last
+not least, it has been found to be quite inadequate to
+explain the first origin of all newly formed constituents of
+organisation even if they are not indifferent: for how
+could any rudiment of an organ, which is not functioning
+at all, not only be useful to its bearer, but be useful in
+such a degree as to decide about life or death?</p>
+<p><span class="pagenum" title="267"><a name="Page_267" id="Page_267"></a></span></p>
+<p>It is only for one special feature that I should like to
+show, by a more full analysis, that dogmatic Darwinism
+does not satisfy the requirements of the case. The special
+strength of Darwinism is said to lie in its explaining everything
+that is useful in and for organisms; the competitive
+factor it introduces does indeed seem to secure at least a
+relative sort of adaptedness between the organism and its
+needs. But in spite of that, we shall now see that
+Darwinism fails absolutely to explain those most intimate
+organic phenomena which may be said to be the most
+useful of all.</p>
+
+<p>Darwinism in its dogmatic form is not able to explain
+the origin of any sort of organic restitution; it is altogether
+impossible to account for the restitutive power of organisms
+by the simple means of fluctuating variation and natural
+selection in the struggle for existence. Here we have the
+logical <i lang="la" xml:lang="la">experimentum crucis</i> of Darwinism.</p>
+
+<p>Let us try to study in the Darwinian style the origin
+of the regenerative faculty, as shown in the restitution of
+the leg of a newt. All individuals of a given species of the
+newt, say <i class="biological-name">Triton taeniatus</i>, are endowed with this faculty;
+all of them therefore must have originated from ancestors
+which acquired it at some time or other. But this
+necessary supposition implies that all of these ancestors
+must have lost their legs in some way, and not only one,
+but all four of them, as they could not have acquired the
+restitutive faculty otherwise. We are thus met at the very
+beginning of our argument by what must be called a
+real absurdity, which is hardly lessened by the assumption
+that regeneration was acquired not by all four legs together,
+but by one after the other. But it is absolutely inevit<span class="pagenum" title="268"><a name="Page_268" id="Page_268"></a></span>able
+to assume that <em>all</em> the ancestors of our <i class="biological-name">Triton</i> must
+have lost one leg, or more correctly, that only those of
+them survived which had lost one! Otherwise not all
+newts at the present day could possess the faculty of
+regeneration! But a second absurdity follows the first
+one; out of the ancestors of our newt, which survived the
+others by reason of having lost one of their legs, there were
+selected only those which showed at least a very small amount
+of healing of their wound. It must be granted that such a
+step in the process of selection, taken by itself, would not
+at all seem to be impossible; since healing of wounds
+protects the animals against infection. But the process
+continues. In every succeeding stage of it there must have
+survived only those individuals which formed just a little
+more of granulative tissue than did the rest: though
+<em>neither</em> they themselves <em>nor</em> the rest could use the leg,
+which indeed was not present! That is the second absurdity
+we meet in our attempt at a Darwinian explanation of the
+faculty of regeneration; but I believe the first one alone
+was sufficient.</p>
+
+<p>If we were to study the “selection” of the faculty of
+one of the isolated blastomeres of the egg of the sea-urchin
+to form a whole larva only of smaller size, the absurdities
+would increase. At the very beginning we should encounter
+the absurdity, that of all the individuals there survived
+only those which were not whole but half; for <em>all</em> sea-urchins
+are capable of the ontogenetical restitution in
+question, <em>all</em> of their ancestors therefore must have acquired
+it, and they could do that only <em>if</em> they became halved at
+first by some accident during early embryology. But we
+shall not insist any further on this instance, for it would<span class="pagenum" title="269"><a name="Page_269" id="Page_269"></a></span>
+not be fair to turn into ridicule a theory which bears the
+name of a man who is not at all responsible for its dogmatic
+form. Indeed, we are speaking against Darwinism of the
+most dogmatic form only, not against Darwin himself. He
+never analysed the phenomena of regeneration or of
+embryonic restitution&mdash;they lay in a field very unfamiliar
+to him and to his time. I venture to say that if he had
+taken them into consideration, he would have agreed with
+us in stating that his theory was not at all able to cover
+them; for he was prepared to make great concessions, to
+Lamarckism for instance, in other branches of biology, and
+he did not pretend, to know what life itself is.</p>
+
+<p>Darwin was not a decided materialist, though materialism
+has made great capital out of his doctrines, especially in
+Germany. His book, as is well known, is entitled “The
+Origin of <em>Species</em>,” that is of organic <em>diversities</em>, and he himself
+possibly might have regarded all restitution as belonging to
+the original properties of life, anterior to the originating of
+diversities. Personally he might possibly be called even a
+vitalist. Thus dogmatic “Darwinism” in fact is driven into
+all the absurdities mentioned above, whilst the “doctrine of
+Darwin” can only be said to be wrong on account of its
+failing to explain mutual adaptation, the origin of new
+organs, and some other features in organic diversities; the
+original properties of life were left unexplained by it
+intentionally.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">DARWINISM FAILS ALL ALONG THE LINE</span></p>
+
+<p>The result of our discussion then must be this: selection
+has proved to be a negative factor only, and fluctuating<span class="pagenum" title="270"><a name="Page_270" id="Page_270"></a></span>
+variation as the only way in which new properties of the
+organisms might have arisen has proved to fail in the most
+marked manner, except perhaps for a few merely quantitative
+instances. Such a result betokens the complete collapse of
+dogmatic Darwinism as a general theory of descent: the
+most typical features of all organisms remain as unexplained
+as ever.</p>
+
+<p>What then shall we put in the place of pure Darwinism?
+Let us first try a method of explanation which was also
+adopted occasionally by Darwin himself: let us study that
+form of transformation theories which is commonly known
+under the title of Lamarckism.</p>
+
+<p><span class="pagenum" title="271"><a name="Page_271" id="Page_271"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The Principles of Lamarckism.</span></h4>
+
+<p>As the word “Darwinism” does not signify the proper
+theoretical system of Charles Darwin, so Lamarckism as
+commonly understood nowadays is a good deal removed
+from the original views of Jean Baptiste Lamarck.
+Lamarckism is generally regarded as reducing all organic
+diversities to differences in the needs of individual life, but
+Lamarck himself, as must be emphasised from the very
+beginning, did not at all maintain the opinion that the
+great characteristics of the types were only due to such
+accidental factors. He supposed a sort of law of organisation
+to be at the root of systematics, as developed in history,
+and the needs of life were only responsible, according to
+him, for splitting the given types of organisation into
+their ultimate branches. Thus Lamarck, to a great extent
+at any rate, belongs to a group of authors that we shall
+have to study afterwards: authors who regard an unknown
+law of phylogenetic development as the real basis of
+transformism. Modern so-called Neo-Lamarckism, on the
+other hand, has indeed conceded the principle of needs to
+be the sole principle of transformism. Let us then study
+Lamarckism in its dogmatic modern form.</p>
+
+<p><span class="pagenum" title="272"><a name="Page_272" id="Page_272"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ADAPTATION AS THE STARTING-POINT</span></p>
+
+<p>All facts of morphological adaptations&mdash;facts which we
+have analysed already from a different point of view, as being
+among the most typical phenomena of organic regulation&mdash;form
+the starting-point of this theory, and it must be
+granted that they form a very solid foundation, for they
+are facts. The theory only has to enlarge hypothetically
+the realm of these facts, or rather the realm of the law
+that governs them. Indeed, it is assumed by Lamarckism
+that the organism is endowed with the faculty of responding
+to <em>any</em> change of the environment which may change its
+function by a morphologically expressed alteration of its
+functional state and form, which is adapted to the state of
+conditions imposed from without. Of course, as stated in
+this most general form, the assumption is not true, but it is
+true within certain limits, as we know; and there seems to
+be no reason why we should not believe that there are many
+more cases of adaptation than we actually know at present,
+or that, in former phylogenetic times, the organisms were
+more capable of active adaptation than they are now. So
+to a certain extent, at least, Lamarckism can be said to
+rest upon a <i lang="la" xml:lang="la">causa vera</i>.</p>
+
+<p>It is important to notice that this <i lang="la" xml:lang="la">causa vera</i> would
+imply vitalistic causality when taken in the wide meaning
+which Lamarckism allows to it: indeed, the power of active
+adaptation to indefinite changes would imply a sort of
+causal connection that is nowhere known except in the
+organism. Lamarck himself is not very clear about this
+point, he seems to be afraid of certain types of uncritical
+vitalism in vogue in his days; but modern writers have<span class="pagenum" title="273"><a name="Page_273" id="Page_273"></a></span>
+most clearly seen what the logical assumptions of pure
+Lamarckism are. Next to Cope, August <span class="nowrap">Pauly<a name="FNanchor_146_146" id="FNanchor_146_146"></a><a href="#Footnote_146_146" class="fnanchor">146</a></span> may be
+said to be the most conscious representative of a sort of
+so-called psychological vitalism, which indeed Lamarckism
+as a general and all-embracing theory must have as its
+basis.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE ACTIVE STORING OF CONTINGENT VARIATIONS AS A
+HYPOTHETIC PRINCIPLE</span></p>
+
+<p>This point will come out more fully, if now we turn
+to study a certain group of principles, upon which dogmatic
+Lamarckism rests: I say principles and not facts, for there
+are no facts but only hypothetic assumptions in this group
+of statements. We do know a little about adaptations, at
+least to a certain extent, and it was only about the sphere
+of the validity of a law, which was known to be at work
+in certain cases, that hypothetical additions were made.
+In the second group of the foundations of Lamarckism we
+know absolutely nothing; accidental variations of form
+are supposed to occur, and the organism is said to possess
+the faculty of keeping and storing these variations and of
+handing them down to the next generation, if they happen
+to satisfy any of its needs.</p>
+
+<p>But these needs are not of the actual type, brought
+forth by a change of the functional state of the individual,
+as in the case of adaptations: they are of a somewhat
+mysterious nature. A glance at the theory of the origin
+of the movements which are called acts of volition in the
+human child may serve to elucidate what is meant.</p>
+
+<p><span class="pagenum" title="274"><a name="Page_274" id="Page_274"></a></span></p>
+
+<p>Acts of volition are said thus to originate in random
+movements of the new-born infant: certain of these
+accidental motions which happen to relieve some pain or
+to afford some pleasure are “remembered,” and are used
+another time quite consciously to bring forth what is liked
+or to remove what is disliked. So much for the present
+on a very difficult subject, which will occupy us next year
+at much greater length. It is clear that at least three
+fundamental phenomena are concerned in this theory of
+the origin of acts of volition: the liking and disliking, the
+keeping in mind, and the volition itself. The real act of
+volition, indeed, is always based upon a connection of all
+these factors, these factors now being connected in such a
+way that even their kind of connection may be said to be
+a fourth fundamental principle. In order that the particular
+effect may be obtained which is wanted because it is liked,
+the possible ways leading to it, which appeared among
+the random movements in the very beginning, are now
+regarded as “means” and may now be said to be “used.”
+But that is as much as to say that the “means” are judged
+with respect to their usefulness for the actual purpose, and
+therefore <em>judgment</em> is the fourth foundation of the act of
+volition.</p>
+
+<p>In fact, Pauly does not hesitate to attribute judgment,
+along with the other psychological elements, to the organisms
+whilst undergoing their transformation. There has been
+formed, for instance, by accidental variation some pigment
+which by its chemical nature brings the organism into a
+closer connection with the light of the medium; the
+individual likes that, keeps the pigment for itself and produces
+it again in the next generation; and indeed it will<span class="pagenum" title="275"><a name="Page_275" id="Page_275"></a></span>
+safeguard any sort of improvement which chance may
+effect in this primitive “eye.” Such a view is said to hold
+well with respect to the origin of every new organ. And
+this psychological argument is also said to afford the real
+explanation of adaptation proper. Adaptation also is
+regarded not as a truly primary faculty of the organism,
+but as a retention or provoking of metabolic states which
+occurred by accident originally and were then found to be
+useful; now they are reproduced either in every single
+case of individual morphogenesis, without regard to actual
+requirements, or else only in response to such: in the first
+case they are “inherited,” in the second they only occur as
+regulations. Thus the process of judgment, together with
+all the other elemental factors of psychical life concerned in
+it, has been made to account for adaptation proper. The
+whole theory has accordingly become very uniform and simple.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CRITICISM OF THE “INHERITANCE OF ACQUIRED CHARACTERS”
+ASSUMED BY LAMARCKISM</span></p>
+
+<p>In addressing ourselves to the criticism of Neo-Lamarckism
+we shall neglect as far as possible all the different psychological
+principles concerned in it&mdash;which in any case would
+need rather a great amount of epistemological sifting&mdash;and
+shall keep to those hypothetic facts which are supposed to
+be such as may be actually observed in nature.</p>
+
+<p>All of you know that the so-called inheritance of
+acquired characters lies at the root of Lamarckism; and
+from this hypothesis our critical analysis is to start,
+disregarding a larger or smaller number of psychological
+principles that are brought into the field.</p>
+
+<p><span class="pagenum" title="276"><a name="Page_276" id="Page_276"></a></span></p>
+
+<p>The name of “acquired characters” may <i lang="la" xml:lang="la">a priori</i> be
+given to three different types of phenomena: firstly, variations
+including mutations; secondly, disease or injuries;
+and thirdly, the results of the actual process of adaptation
+of every kind.</p>
+
+<p>In the first of these groups, the true problem of the
+inheritance of “acquired” characters appears only with
+certain restrictions. All variations and mutations are indeed
+“acquired” by one generation so far as the earlier generation
+did not possess them, but mutations, at least, cannot
+be said to be acquired by the actual adult personality:
+they are innate in it from its very beginning, and therefore
+may better be called <span class="nowrap">congenital.<a name="FNanchor_147_147" id="FNanchor_147_147"></a><a href="#Footnote_147_147" class="fnanchor">147</a></span> Congenital properties of
+the mutation type are, in fact, known to be inherited: their
+inheritance does not present any problem of its own, but is
+included in the changes of the hereditary condition to
+which they are due <span class="nowrap">altogether.<a name="FNanchor_148_148" id="FNanchor_148_148"></a><a href="#Footnote_148_148" class="fnanchor">148</a></span> All properties of the
+variation type, on the other hand, having been studied
+statistically, are known to be inherited, to a certain small
+extent, as we have seen already whilst studying Darwinism,
+though they are possibly always liable to reversion.
+Modern science, as we <span class="nowrap">know,<a name="FNanchor_149_149" id="FNanchor_149_149"></a><a href="#Footnote_149_149" class="fnanchor">149</a></span> regards them as due to
+changes of nutrition, in the most general meaning of the
+word. Under such a view variations might indeed be said<span class="pagenum" title="277"><a name="Page_277" id="Page_277"></a></span>
+to belong to the acquired group of organic specifications;
+their inheritance, as will be seen later on, would hardly be
+quite a pure instance of what we are searching for. In no
+case can true variations claim to be of great importance in
+problems of transformism.</p>
+
+<p>But what is known about the inheritance of those
+properties which beyond any doubt may be said to have
+originated in the adult individual as such, and of which
+lesions and adaptations proper, as shown for instance among
+amphibious plants, are instances of the two most typical
+<span class="nowrap">groups?<a name="FNanchor_150_150" id="FNanchor_150_150"></a><a href="#Footnote_150_150" class="fnanchor">150</a></span> Weismann did good service by putting an end
+to the scientific credulity which prevailed with regard to
+this subject. Weismann was led by his theory of the germ
+plasm to deny the inheritance of acquired characters of the
+typical kinds. He could not imagine how the effect of any
+agent upon the adult, be it of the merely passive or of the
+adaptive kind, could have such an influence upon the germ
+as to force it to produce the same effect in spite of the
+absence of that agent. In fact, that is what the inheritance
+of acquired characters would render necessary, and a very
+strange phenomenon it would be, no doubt. But, of course,
+taken alone, it could never be a decisive argument against
+such inheritance. I fully agree, that science is obliged to
+explain new facts by what is known already, as long as it is
+possible; but if it is no longer possible, the theory of course
+has to be changed, and not the facts. On this principle one
+would not neglect the fact of an inheritance of acquired
+properties, but on the contrary one perhaps might use it
+as a new evidence of vitalism.</p>
+<p><span class="pagenum" title="278"><a name="Page_278" id="Page_278"></a></span></p>
+<p>But are there any facts?</p>
+
+<p>At this point we come to speak about the second group
+of Weismann’s reasonings. He not only saw the difficulty
+of understanding inheritance of acquired characters on the
+principles of the science of his time, but he also criticised
+the supposed facts; and scarcely any of them stood the
+test of his criticism. Indeed, it must fairly be granted that
+not one case is known which really proves the inheritance
+of acquired characters, and that injuries certainly are never
+found to be inherited. In spite of that, I do not believe
+that we are entitled to deny the possibility of the inheritance
+of a certain group of acquired characters in an absolute
+and dogmatic manner, for there are a few facts which seem
+at least to tend in the direction of such an inheritance,
+and which seem to show that it might be discovered perhaps
+one day, if the experimental conditions were changed.</p>
+
+<p>I am not referring here to the few cases in which
+bacteria were made colourless or non-virulent by outside
+factors, or in which certain fungi were forced to permanent
+agamic reproduction by abnormal external conditions and
+were shown to retain their “acquired properties” after
+the external conditions had been restored. In these cases
+only reproduction by simple division occurred, and that
+does not imply the true problem of inheritance. Nor am I
+referring to the few cases of non-adaptive “modifications”
+found by Standfuss and Fischer, in which butterflies that
+had assumed an abnormal kind of pigmentation under the
+influence of abnormal temperature acting upon the pupa,
+were seen to form this same kind of pigmentation in the
+next generation under normal conditions of temperature.
+These cases, though important in themselves, are capable<span class="pagenum" title="279"><a name="Page_279" id="Page_279"></a></span>
+perhaps of a rather simple explanation, as in fact has been
+suggested. Some necessary means both of inheritance and
+of morphogenesis, the former being present in the propagation
+cells, may be said to have been changed or destroyed
+by heat, and therefore, what seems to be inherited after
+the change of the body only, would actually be the effect
+of a direct influence of the temperature upon the germ
+<span class="nowrap">itself.<a name="FNanchor_151_151" id="FNanchor_151_151"></a><a href="#Footnote_151_151" class="fnanchor">151</a></span> Let me be clearly understood: I do not say that
+it is so, but it may be so. What seems to me to be more
+important than everything and to have a direct bearing on
+the real discovery of the inheritance of acquired characters
+in the future, is this. In some instances plants which
+had been forced from without to undergo certain typical
+morphological adaptations, or at least changes through
+many generations, though they did not keep the acquired
+characters permanently in spite of the conditions being
+changed to another type, were yet found to lose the acquired
+adaptations not suddenly but only in the course of three or
+more generations. A certain fern, <i class="biological-name">Adiantum</i>, is known to
+assume a very typical modification of form and structure, if
+grown on serpentine; now <span class="nowrap">Sadebeck,<a name="FNanchor_152_152" id="FNanchor_152_152"></a><a href="#Footnote_152_152" class="fnanchor">152</a></span> while cultivating this
+serpentine modification of <i class="biological-name">Adiantum</i> on ordinary ground,
+found that the first generation grown in the ordinary
+conditions loses only a little of its typical serpentine
+character, and that the next generation loses a little more, so
+that it is not before the fifth generation that all the characters
+of the serpentine modification have disappeared. There are<span class="pagenum" title="280"><a name="Page_280" id="Page_280"></a></span>
+a few more cases of a similar type relating to plants grown
+in the plains or on the mountains. There also it was found
+to take time, or rather to take the course of <em>several</em> generations,
+until what was required by the new conditions was
+reached. Of course these cases are very very few compared
+with those in which a <em>sudden</em> change of the adaptive character,
+corresponding to the actual conditions, sets in; but it is
+enough that they do exist.</p>
+
+<p>Would it not be possible at least that adaptations
+which last for thousands of generations or more might
+in fact change the adaptive character into a congenital
+one? Then we not only should have inheritance of
+acquired characters, but should have a sort of explanation
+at the same time for the remarkable fact that certain
+histological structures of a very adapted kind are formed
+ontogenetically before any function exists, as is known
+to be the case with the structures in the bones of
+vertebrates, for instance. Experiments are going on at
+Paris, and perhaps in other places of scientific research
+also, which, it is hoped, will show that animals reared in
+absolute darkness for many generations will lose their
+perfectly formed eyes, and that animals from the dark with
+very rudimentary eyes will be endowed with properly
+functioning ones, after they have been reared in the light
+for generations. Such a result indeed would account for
+the many animals, of the most different groups, which live
+in dark caves and possess only rudiments of eyes: functional
+adaptation is no longer necessary, so-called atrophy by
+inactivity sets in, and the results “acquired” by it are
+<span class="nowrap">inherited.<a name="FNanchor_153_153" id="FNanchor_153_153"></a><a href="#Footnote_153_153" class="fnanchor">153</a></span></p>
+<p><span class="pagenum" title="281"><a name="Page_281" id="Page_281"></a></span></p>
+<p>But enough of possibilities. Let us be content at
+present to know at least a few real instances with regard
+to the slowness of the process of what might be said to be
+“re-adaptation” in some plants. This process shows us a
+way by which our problem may some day be solved; it
+allows us to introduce inheritance of acquired characters as
+a legitimate hypothesis at least, which not only will explain
+many of the diversities in systematics historically, but also
+can be called, though not a <i lang="la" xml:lang="la">causa vera</i>, yet certainly more
+than a mere fiction.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">OTHER PRINCIPLES WANTED</span></p>
+
+<p>We have only dealt with the probability of the
+inheritance of morphological or <span class="nowrap">physiological<a name="FNanchor_154_154" id="FNanchor_154_154"></a><a href="#Footnote_154_154" class="fnanchor">154</a></span> adaptation.
+If that could really be considered as one of the factors
+concerned in the theory of descent, many, if not all of those
+congenital diversities among organic species which are of
+the type of a true structural correspondence to their future
+functional life, might be regarded as explained, that is, as
+reduced to one and the same principle. But nothing more
+than an explanation of <em>this</em> kind of diversities is effected
+by our principle, and very much more remains to be done,
+for organic diversities not only consist in specifications and<span class="pagenum" title="282"><a name="Page_282" id="Page_282"></a></span>
+differences as to histology, but are to a much more important
+degree, differences of organisation proper, that is, of the
+arrangement of parts, in the widest sense of the <span class="nowrap">word.<a name="FNanchor_155_155" id="FNanchor_155_155"></a><a href="#Footnote_155_155" class="fnanchor">155</a></span></p>
+
+<p>Would it be possible to interpret the origin of this
+sort of systematic diversities by a reasoning similar to that
+by which we have understood, at least hypothetically,
+congenital adaptedness?</p>
+
+<p>Dogmatic Lamarckism, we know, uses two principles as
+its foundations; one of them, adaptation and its inheritance,
+we have studied with what may be called a partly positive
+result. The other is the supposed faculty of the organism
+to keep, to store, and to transfer those variations or mutations
+of a not properly adaptive sort which, though originating
+by chance, happen to satisfy some needs of the organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CRITICISM OF THE HYPOTHESIS OF STORING AND HANDING
+DOWN CONTINGENT VARIATIONS</span></p>
+
+<p>Strange to say, this second hypothesis of dogmatic
+Lamarckism, invented with the express purpose of defeating
+Darwinism and taking the place of its fluctuating variability,
+which was found not to do justice to the facts&mdash;this second
+hypothesis of dogmatic Lamarckism is liable to just the
+same objections as dogmatic Darwinism itself.</p>
+
+<p>As it is important to understand well the real logical
+nature of our objections to both of the great transformistic<span class="pagenum" title="283"><a name="Page_283" id="Page_283"></a></span>
+theories, we think it well to interrupt our argument for a
+moment, in order to consider a certain point which, though
+very important in itself, seems of only secondary importance
+to us in our present discussion. Dogmatic Darwinism&mdash;I
+do not say the doctrine of Charles Darwin&mdash;is materialistic
+at bottom, and indeed has been used by many to complete
+their materialistic view of the universe on its organic side.
+The word “materialism” must not necessarily be taken
+here in its metaphysical sense, though most materialists
+are dogmatic metaphysicians. It also can be understood
+as forming part of a phenomenological point of view.
+Materialism as a doctrine of science means simply this:
+that whether “nature” be reality or phenomenon, in any
+case there is but one ultimate principle at its base, a
+principle relating to the movements of particles of matter.
+It is this point of view which dogmatic Darwinism
+strengthens; on the theory of natural selection and fluctuating
+variations, due to accidental differences of nutrition,
+organisms are merely arrangements of particles of
+matter, nothing else; and moreover, their kinds of arrangement
+are understood, at least in principle. Lamarckism,
+on the other hand, is not materialistic, but most markedly
+vitalistic&mdash;psychistic even; it takes life for granted when
+it begins its explanations.</p>
+
+<p>You may tell me that Darwin did the same, that
+he expressly states that his theory has nothing to do with
+the origin of life; that the title of his work is “The Origin
+of <em>Species</em>.” It would certainly be right to say so, at least
+with reference to Darwin personally; but in spite of that,
+it must be granted that Darwin’s doctrine contains a certain
+germ of materialism which has been fully developed by the<span class="pagenum" title="284"><a name="Page_284" id="Page_284"></a></span>
+Darwinian dogmatists, while Lamarckism is antimaterialistic
+by its very nature.</p>
+
+<p>Now it is very important, I think, to notice that this
+difference between the two theories is unable to disguise
+one main point which is common to both: and it is to
+this point, and to this point only, that our chief objections
+against both these theories converge at present.</p>
+
+<p>The <em>contingency</em> of the typical organic form is maintained
+by Darwinism as well as by Lamarckism: both theories,
+therefore, break down for almost the same reasons. The term
+“contingency” can signify very different relations, having
+but little in common; but it is sufficient for our present
+purpose to observe that there may be distinguished roughly
+two main classes of contingencies, which may provisionally
+be called the “contingency of being,” and the “contingency
+of occurring.” It is with the contingency of being that
+criticism of Darwinism and Lamarckism of the dogmatic
+type has to deal. Darwinism dealt with variations occurring
+at random; the organic form was the result of a
+fixation of only one kind of such variations, all others
+being extinguished by selection. In other terms, the specific
+organised form, as understood by Darwinism, was a unit
+only to the extent that all its properties related to one and
+the same body, but for the rest it was a mere aggregation
+or summation. It may be objected to this statement, that
+by being inherited in its specificity the Darwinian form
+proved to be a unit in a higher sense of the word, even
+in the opinion of dogmatic Darwinians; and this objection,
+perhaps, holds good as far as inheritance is concerned. But
+on the other hand, it must never be forgotten that the
+word “unit” had quite a vague and empty meaning even<span class="pagenum" title="285"><a name="Page_285" id="Page_285"></a></span>
+then, as indeed everything the organism is made up of is
+regarded as being in itself due to a contingent primary
+process, which has no relation to its fellow-processes.
+“Unit,” indeed, in spite of inheritance&mdash;which, by the way,
+is alleged also to be a merely materialistic event&mdash;means
+to Darwinians no more when applied to the organism than
+it does when applied to mountains or islands, where of
+course a sort of “unit” also exists in some sense, as far as
+one and the same body comes into account, but where
+every single character of this unit, in every single feature
+of form or of quality, is the result of factors or agents each
+of which is independent of every other.</p>
+
+<p>To this sort of contingency of being, as maintained by
+Darwinians, criticism has objected, as we know, that it is
+quite an impossible basis of a theory of descent, since it
+would explain neither the first origin of an organ, nor any
+sort of harmony among parts or among whole individuals,
+nor any sort of restitution processes.</p>
+
+<p>Now Lamarckism of the dogmatic kind, as will easily
+be seen, only differs from Darwinism in this respect, that
+what according to the latter happens to the organism
+passively by means of selection, is according to the former
+performed actively by the organism, by means of a
+“judgment”&mdash;by the retention and handing down of chance
+variations. The specificity of the form as a whole is
+contingent also according to Lamarckism. And, indeed,
+criticism must reject this contingency of being in exactly
+the same way as it rejected the contingency of form
+maintained by Darwinians.</p>
+
+<p>As far as the inheritance of truly adaptive characters
+comes into account&mdash;that is, the inheritance of characters<span class="pagenum" title="286"><a name="Page_286" id="Page_286"></a></span>
+which are due to the active faculty of adaptation possessed
+by the organism, bearing a vitalistic aspect throughout&mdash;hardly
+anything could be said against Lamarckism, except
+that inheritance of acquired characters is still an hypothesis
+of small and doubtful value at present. But that <em>specific
+organisation proper</em> is due to <em>contingent</em> variations, which
+accidentally have been found to satisfy some needs of the
+individual and therefore have been maintained and handed
+down, this reasoning is quite an impossibility of exactly
+the same kind as the argument of Darwinism.</p>
+
+<p>The process of restitution, perfect the very first time
+it occurs, if it occurs at all, is again the classical instance
+against this new sort of contingency, which is assumed to
+be the basis of transformism. Here we see with our eyes
+that the organism can do more than simply perpetuate
+variations that have occurred at random and bear in themselves
+no relation whatever to any sort of unit or totality.
+There <em>exists</em> a faculty of a certain higher degree in the
+organism, and this faculty cannot possibly have originated
+by the process which <span class="nowrap">Lamarckians<a name="FNanchor_156_156" id="FNanchor_156_156"></a><a href="#Footnote_156_156" class="fnanchor">156</a></span> assume. But if their
+principle fails in one instance, it fails as a <em>general</em> theory
+altogether. And now, on the other hand, as we actually<span class="pagenum" title="287"><a name="Page_287" id="Page_287"></a></span>
+see the individual organism endowed with a morphogenetic
+power, inexplicable by Lamarckism, but far exceeding the
+organogenetic faculty assumed by that theory, would it
+not be most reasonable to conclude from such facts, that
+there exists a certain organising power at the root of the
+transformism of species also, a power which we do not
+understand, which we see only partially manifested in the
+work of restitutions, but which certainly is not even touched
+by any of the Lamarckian arguments? There does indeed
+exist what Gustav Wolff has called primary purposefulness
+(“primäre Zweckmässigkeit”), at least in restitutions, and
+this is equally unexplainable by Darwinism and by the
+dogmatism of the Lamarckians.</p>
+
+<p>But before entering into this area of hypothesis, let us
+mention a few more objections to be made to the theory
+of the contingency of form as put forward by Lamarckians.
+In the first place, let us say a few words about the
+appropriateness of the term “contingency” as used in this
+connection. The forms are regarded as contingent by
+Lamarckians inasmuch as the variations which afterwards
+serve as “means” to the “needs” of the organism occur
+quite accidentally with regard to the whole organism.
+It might be said that these “needs” are not contingent
+but subject to an inherent destiny, but this plea is excluded
+by the Lamarckians themselves, when they say that the
+organism experiences no need until it has enjoyed the
+accidental fulfilment of the same. So the only thing in
+Lamarckian transformism which is not of a contingent
+character would be the psychological agent concerned in it,
+as being an agent endowed with the primary power of
+feeling needs after it has felt fulfilment, and of judging<span class="pagenum" title="288"><a name="Page_288" id="Page_288"></a></span>
+about what the means of future fulfilment are, in order to
+keep them whenever they offer. But these are characteristics
+of life itself, irrespective of all its specific forms, which alone
+are concerned in transformism. Now indeed, I think, we
+see as clearly as possible that Darwinism and Lamarckism,
+in spite of the great contrast of materialism and psychologism,
+shake hands on the common ground of the contingency
+of organic forms.</p>
+
+<p>The whole anti-Darwinistic criticism therefore of Gustav
+Wolff for instance, may also be applied to Lamarckism
+with only a few changes of words. How could the origin
+of so complete an organ as the eye of vertebrates be due to
+contingent variations? How could that account for the
+harmony of the different kinds of cells in this very complicated
+organ with each other and with parts of the
+brain? And how is it to be understood, on the assumption
+of contingency, that there are two eyes of almost equal
+perfection, and that there are two feet, two ears? Islands
+and mountains do not show such symmetry in <em>their</em>
+structures.</p>
+
+<p>We shall not repeat our deduction of the origin of
+restitutions, of regeneration for instance, on the dogmatic
+Lamarckian theory. As we have said already, it would lead
+to absurdities as great as in the case of dogmatic Darwinism,
+and indeed we already have mentioned that Lamarckians
+would hardly even attempt to explain these phenomena.
+It follows that dogmatic Lamarckism fails as a general
+theory about <span class="nowrap">form.<a name="FNanchor_157_157" id="FNanchor_157_157"></a><a href="#Footnote_157_157" class="fnanchor">157</a></span></p>
+
+<p>There is finally one group of facts often brought forward<span class="pagenum" title="289"><a name="Page_289" id="Page_289"></a></span>
+against Lamarckism by Darwinian <span class="nowrap">authors<a name="FNanchor_158_158" id="FNanchor_158_158"></a><a href="#Footnote_158_158" class="fnanchor">158</a></span> which may be
+called the logical <i lang="la" xml:lang="la">experimentum crucis</i> of this doctrine, an
+<i lang="la" xml:lang="la">experimentum</i> destined to prove fatal. You know that
+among the polymorphic groups of bees, termites, and ants,
+there exists one type of individuals, or even several types,
+endowed with some very typical features of organisation,
+but at the same time absolutely excluded from reproduction:
+how could those morphological types have originated on
+the plan allowed by the Lamarckians? Of what use
+would “judgment” about means that are offered by chance
+and happen to satisfy needs, be to individuals which die
+without offspring? Here Lamarckism becomes a simple
+absurdity, just as Darwinism resulted in absurdities
+elsewhere.</p>
+
+<p>We were speaking about dogmatic Darwinism then, and
+it is about dogmatic Lamarckism that we are reasoning at
+present; both theories must fall in their dogmatic form,
+though a small part of both can be said to stand criticism.
+But these two parts which survive criticism, one offered by
+Lamarck, the other by Darwin, are far from being a
+complete theory of transformism, even if taken together:
+they only cover a small area of the field concerned in the
+theory of descent. Almost everything is still to be done,
+and we may here formulate, briefly at least, what we expect
+to be accomplished by the science of the future.</p>
+
+<p><span class="pagenum" title="290"><a name="Page_290" id="Page_290"></a></span></p>
+
+
+<h4 class="fs120">4. <span class="smcap">The Real Results and the Unsolved Problems of
+Transformism</span></h4>
+
+<p>What has been explained to a certain extent by the two
+great theories now current is only this. Systematic diversities
+consisting in mere differences as to intensity or
+number may perhaps owe their origin to ordinary variation.
+They may at least, if we are entitled to assume that heredity
+in some cases is able to hand on such variations without
+reversion, which, it must be again remarked, is by no means
+proved by the facts at present. Natural selection may share
+in this process by eliminating all those individuals that do
+not show the character which happens to be useful. That
+is the Darwinian part of an explanation of transformism
+which may be conceded as an hypothesis. On the other
+side, congenital histological adaptedness may be regarded
+hypothetically as due to an inheritance of adaptive
+characters which had been acquired by the organism’s
+activity, exerted during a great number of generations.
+That is the Lamarckian part in the theory of descent.</p>
+
+<p>But nothing more is contributed to this theory either
+by the doctrine of Darwin or by that of Lamarck. So it
+follows that almost everything has still to be done; for no
+hypothesis at present accounts for the foundation of all
+systematics, viz., for the differences in organisation, in all<span class="pagenum" title="291"><a name="Page_291" id="Page_291"></a></span>
+that relates to the so-called types as such and the degree of
+complication in these types, both of which (types and degree
+of complication) are independent of histological adaptation
+and adaptedness.</p>
+
+<p>What then do we know about any facts that might be
+said to bear on this problem? We have stated already
+at the end of our chapter devoted to the analysis of heredity
+that what we actually know about any deviation of inheritance
+proper, that is, about congenital differences between
+the parents and the offspring, relating to mere tectonics,
+is practically nothing: indeed, there are at our disposal
+only the few facts observed by de Vries or derived from
+the experience of horticulturalists and breeders. We may
+admit that these facts at least prove the <span class="nowrap">possibility<a name="FNanchor_159_159" id="FNanchor_159_159"></a><a href="#Footnote_159_159" class="fnanchor">159</a></span> of
+a discontinuous variation, that is of “mutation,” following
+certain lines of tectonics and leading to <em>constant</em> results;
+but everything else, that is everything about a real theory
+of phylogeny, must be left to the taste of each author who
+writes on the theory of the Living. You may call that a
+very unscientific state of affairs, but no other is possible.</p>
+
+<p>And, in fact, it has been admitted by almost all who
+have dealt with transformism without prepossessions that
+such is the state of affairs. Lamarck himself, as we have
+mentioned already, was not blind to the fact that a sort of
+organisatory law must be at the base of all transformism,
+and it is well known that hypothetical statements about
+an original law of phylogeny have been attempted by<span class="pagenum" title="292"><a name="Page_292" id="Page_292"></a></span>
+Nägeli, Kölliker, Wigand, Eimer, and many others. But a
+full discussion of all these “laws” would hardly help us
+much in our theoretical endeavour, as all of them, it must be
+confessed, do little more than state the mere fact that some
+unknown principle of organisation must have been at work
+in phylogeny, if we are to accept the theory of descent
+at all.</p>
+
+<p>It is important to notice that even such a convinced
+Darwinian as Wallace, who is well known to have been an
+independent discoverer of the elimination principle, admitted
+an exception to this principle in at least one case&mdash;with
+regard to the origin of man. But one exception of course
+destroys the generality of a principle.</p>
+
+<p>As we ourselves feel absolutely incapable of adding
+anything specific to the general statement that there <em>must</em>
+be an unknown principle of transformism, if the hypothesis
+of descent is justified at all, we may here close our discussion
+of the subject.</p>
+
+<p><span class="pagenum" title="293"><a name="Page_293" id="Page_293"></a></span></p>
+
+
+<h4 class="fs120">5. <span class="smcap">The Logical Value of the Organic Form According to the<br />Different Transformistic Theories</span></h4>
+
+<p>A few words only must be added about two topics: on
+the character of organic forms as regarded by the
+different transformistic theories, and on the relation of
+transformism in general to our concept of entelechy.</p>
+
+<p>We have learnt that both Darwinism and Lamarckism,
+in their dogmatic shape, regard the specific forms of animals
+and plants as being contingent; in fact, it was to this
+contingency that criticism was mainly directed. We
+therefore are entitled to say that to Darwinism and
+Lamarckism organic forms are accidental in the very sense
+of the <i lang="la" xml:lang="la">forma accidentalis</i> of the old logicians. There
+are indefinite forms possible, according to these theories,
+and there is no law relating to these forms. Systematics,
+under such a view, must lose, of course, any really
+fundamental importance. “There is no rational system
+about organisms”: that is the ultimate statement of
+Darwinism and of Lamarckism on this doubtful question.
+Systematics is a mere catalogue, not at present only, but for
+ever, by the very nature of the organisms. It is not owing
+to the indefinite number of possible forms that both our
+theories came to deny the importance of systematics, but to
+the want of a <em>law</em> relating to this indefinite number: among<span class="pagenum" title="294"><a name="Page_294" id="Page_294"></a></span>
+chemical compounds indefinite possibilities also exist in
+some cases, but they obey the law of the general formula.
+It is very strange that Darwinians of all people are in the
+forefront of systematic research in all countries: do they
+not see that what they are trying to build up can only
+relate to accidental phenomena? Or have they some doubts
+about the foundations of their own theoretical views, in spite
+of the dogmatic air with which they defend them? Or is
+it the so-called historical interest which attracts them?</p>
+
+<p>A new question seems to arise at this point: Have not
+we ourselves neglected history in favour of systematics and
+laws? Our next lecture, the last of this year, will give
+the answer to this question.</p>
+
+<p>At present we continue our study of the possible aspects
+of systematics. It is not difficult to find out what meaning
+organic forms would assume under any phylogenetic theory
+opposed to the theories of contingency. It was their
+defence of contingency, that is, their lack of any law of
+forms, that caused these theories to be overthrown&mdash;reduced
+to absurdities even&mdash;and therefore, it follows that to assume
+any kind of transformistic law is at the same time to deny
+the accidental character of the forms of living beings.</p>
+
+<p>There is no <i lang="la" xml:lang="la">forma accidentalis</i>. Does that mean that
+the <i lang="la" xml:lang="la">forma essentialis</i> is introduced by this mere statement?
+And what would <em>that</em> assert about the character of
+systematics?</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE ORGANIC FORM AND ENTELECHY</span></p>
+
+<p>This problem is not as simple as it might seem to be
+at the first glance, and, in fact, it is insoluble at present.<span class="pagenum" title="295"><a name="Page_295" id="Page_295"></a></span>
+It is here that the relation of the hypothetic transformistic
+principle to our concept of entelechy is concerned.</p>
+
+<p>We know that entelechy, though not material in itself,
+uses material means in each individual morphogenesis,
+handed down by the material continuity in inheritance.
+What then undergoes change in phylogeny, the means or
+the entelechy? And what would be the logical aspect of
+systematics in either case?</p>
+
+<p>Of course there would be a law in systematics in any
+case; and therefore systematics in any case would be
+rational in principle. But if the transformistic factor
+were connected with the means of morphogenesis, one
+could hardly say that specific form as such was a primary
+essence. Entelechy would be that essence, but entelechy
+in its generality and always remaining the same in its
+most intimate character, as the specific diversities would
+only be due to a something, which is not form, but simply
+means to form. But the <em>harmony</em> revealed to us in every
+typical morphogenesis, be it normal or be it regulatory,
+seems to forbid us to connect transformism with the means
+of morphogenesis. And therefore we shall close this
+discussion about the most problematic phenomena of
+biology with the declaration, that we regard it as more
+congruent to the general aspect of life to correlate the
+unknown principle concerned in descent with entelechy
+itself, and not with its means. Systematics of organisms
+therefore would be in fact systematics of entelechies, and
+therefore organic forms would be <i lang="la" xml:lang="la">formae essentiales</i>,
+entelechy being the very essence of form in its
+specificity. Of course systematics would then be able to
+assume a truly rational character at some future date:<span class="pagenum" title="296"><a name="Page_296" id="Page_296"></a></span>
+there might one day be found a principle to account
+for the totality of <span class="nowrap">possible<a name="FNanchor_160_160" id="FNanchor_160_160"></a><a href="#Footnote_160_160" class="fnanchor">160</a></span> forms, a principle based upon
+the analysis of <span class="nowrap">entelechy.<a name="FNanchor_161_161" id="FNanchor_161_161"></a><a href="#Footnote_161_161" class="fnanchor">161</a></span> As we have allowed that
+Lamarckism hypothetically explains congenital adaptedness
+in histology, and that Darwinism explains a few differences
+in quantity, and as such properties, of course, would both
+be of a contingent character, it follows that our future
+rational system would be combined with certain accidental
+diversities. And so it might be said to be one of the
+principal tasks of systematic biological science in the
+future to discover the really rational system among a given
+totality of diversities which cannot appear rational at the first
+glance, one sort of differences, so to speak, being superimposed
+upon the other.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="297"><a name="Page_297" id="Page_297"></a></span></p>
+
+
+<h3><i>C.</i> THE LOGIC OF HISTORY</h3>
+
+
+<p>History, in the strictest sense of the word, is the
+enumeration of the things which have followed one
+another in order of time. History deals with the single,
+with regard both to time and space. Even if its facts
+are complex in themselves and proper to certain other
+kinds of human study, they are nevertheless regarded by
+history as single. Facts, we had better say, so far as they
+are regarded as single, are regarded historically, for what
+relates to specific time and space is called history.</p>
+
+<p>Taken as a simple enumeration or registration, history,
+of course, cannot claim to be a “science” unless we are
+prepared to denude that word of all specific meaning. But
+that would hardly be useful. As a matter of fact, what
+has actually claimed to be history, has always been more
+than a mere enumeration, even in biology proper. So-called
+phylogeny implies, as we have shown, that every
+one of its actual forms contains some rational elements.
+Phylogeny always rests on the assumption that only some
+of the characters of the organisms were changed in transformism
+and that what remained unchanged may be
+explained by the fact of inheritance.</p>
+
+<p>But this, remember, was the utmost we were able to say
+for phylogeny. It remains fantastic and for the most part<span class="pagenum" title="298"><a name="Page_298" id="Page_298"></a></span>
+unscientific in spite of this small degree of rationality,
+as to which it is generally not very clear itself. For
+nothing is known with regard to the positive factors of
+transformism, and we were only able to offer the discussion
+of a few possibilities in place of a real theory of the
+factors of descent.</p>
+
+<p>In spite of that it will not be without a certain logical
+value to begin our analysis of history in general by the
+discussion of possibilities again. Biology proper would
+hardly allow us to do more: for the simple “fact” of
+history is not even a “fact” in this science, but an
+hypothesis, albeit one of some probability.</p>
+
+<p>As discussions of mere possibilities should always rest
+on as broad a basis as possible, we shall begin our analysis
+by raising two general questions. To what kinds of realities
+may the concept of history reasonably be applied? And
+what different types of “history” would be possible <i lang="la" xml:lang="la">a
+priori</i>, if the word history is to signify more than a mere
+enumeration?</p>
+
+<p><span class="pagenum" title="299"><a name="Page_299" id="Page_299"></a></span></p>
+
+
+<h4 class="fs120">1. <span class="smcap">The Possible Aspects of History</span></h4>
+
+<p>Of course, we could select one definite volume in space
+and call all the consecutive stages which it goes through,
+its history: it then would be part of its history that a
+cloud was formed in it, or that a bird passed through it
+on the wing. But it would hardly be found very
+suggestive to write the history of space-volumes. In fact,
+it is to <em>bodies</em> in space that all history actually relates, at
+least indirectly, for even the history of sciences is in some
+respect the history of men or of books. It may suffice for
+our analysis to understand here the word body in its
+popular sense.</p>
+
+<p>Now in its relation to bodies history may have the
+three following aspects, as far as anything more than a
+simple enumeration comes into account. Firstly, it may
+relate to one and the same body, the term body again to be
+understood popularly. So it is when the individual history
+of the organism is traced from the egg to the adult, or
+when the history of a cloud or of an island or of a volcano
+is written. Secondly, the subject-matter of history may be
+formed by the single units of a consecutive series of bodies
+following each other periodically. To this variety of history
+the discoveries of Mendel and his followers would belong in
+the strictest sense, but so does our hypothetical phylogeny<span class="pagenum" title="300"><a name="Page_300" id="Page_300"></a></span>
+and a great part of the history of mankind. And lastly,
+there is a rather complicated kind of sequence of which the
+“history” has actually been written. History can refer to
+bodies which are in no direct relation with one another,
+but which are each the effect of another body that belongs
+to a consecutive series of body-units showing periodicity.
+This sounds rather complicated; but it is only the strict
+expression of what is perfectly familiar to you all. Our
+sentence indeed is simply part of the definition of a
+history of art or of literature for instance&mdash;or, say, of
+a phylogenetic history of the nests of birds. The
+single pictures are the subjects of the history of art, and
+nobody would deny that these pictures are the effects of
+their painters, and that the painters are individuals of
+mankind&mdash;that is, that they are bodies belonging to a
+consecutive series of body-units showing periodicity. Of
+course, it is only improperly that we speak of a history
+of pictures or of books or of nests. In fact, we are dealing
+with painters, and with men of letters or of science, and
+with certain birds, and therefore the third type of history
+may be reduced to the second. But it was not without
+value to pursue our logical discrimination as far as
+possible.</p>
+
+<p>So far we have always spoken of history as being more
+than a mere enumeration, but we have not ascertained
+what this “more” signifies. It is not very difficult to do
+so: in fact, there are three different types of history,
+each of a different degree of importance with respect to
+the understanding of reality.</p>
+
+<p>In the first place, history may start as a mere enumeration
+at the beginning, and at the end, in spite of all further<span class="pagenum" title="301"><a name="Page_301" id="Page_301"></a></span>
+endeavour, may <em>remain</em> that and nothing more. That
+may occur in the first as well as in the second group of our
+division of history with regard to its relation to bodies.
+Take a cloud and describe its history from the beginning
+to the end: there would never be much more than pure
+description. Or take one pair of dogs and describe them
+and their offspring for four generations or more: I doubt
+if you will get beyond mere descriptions in this case either.
+The only step beyond a mere enumeration which we can be
+said to have advanced in these instances, consists in the
+conviction, gained at the end of the analysis, that nothing
+more than such an enumeration is in any way <em>possible</em>.</p>
+
+<p>Quite the opposite happens when “history” deals with the
+individual from the egg to the adult: here the whole series
+of historical facts is seen to form one whole. This case
+therefore we shall call not history, but <em>evolution</em>, an evolving
+of something; the word “evolution” being understood here
+in a much wider sense than on former <span class="nowrap">occasions,<a name="FNanchor_162_162" id="FNanchor_162_162"></a><a href="#Footnote_162_162" class="fnanchor">162</a></span> and <em>including</em>,
+for instance, the embryological alternative “evolutio”
+or “epigenesis.”</p>
+
+<p>And half-way between enumeration and evolution there
+now stands a type of history which is more than the one
+and less than the other: there is a kind of intelligible
+connection between the consecutive historical stages and
+yet the concept of a whole does not come in. The geological
+history of a mountain or of an island is a very clear instance
+of this class. It is easy to see here, how what <em>has been</em> always
+becomes the foundation of what <em>will be</em> in the <em>next</em> phase of
+the historical process. There is a sort of <em>cumulation</em> of consecutive
+phases, the later ones being impossible without the<span class="pagenum" title="302"><a name="Page_302" id="Page_302"></a></span>
+earlier. So we shall speak of the type of “historical
+cumulation” as standing between evolution and bare
+temporal sequence. By means of historical cumulations
+history may fairly claim to “explain” things. We “understand”
+a mountain or an island in all its actual characteristics,
+if we know its history. This “historical understanding”
+rests on the fact that what first appeared as an
+inconceivable complex has been resolved into a sequence of
+single events, each of which may claim to have been explained
+by actually existing sciences. The complex has been
+explained as being, though not a real “whole,” yet a sum
+of singularities, every element of which is familiar.</p>
+
+<p>But you may tell me that my discussion of evolution
+and of cumulation, as the higher aspects of history, is by no
+means complete; nay, more&mdash;that it is altogether wrong.
+You would certainly not be mistaken in calling my analysis
+incomplete. We have called one type of history evolution,
+the other cumulation; but how have these higher types
+been reached? Has historical enumeration itself, which
+was supposed to stand at the beginning of all analysis, or
+has “history” itself in its strictest sense, as relating to
+the single as such, risen unaided into something more than
+“history”? By no means: history has grown beyond its
+bounds by the aid of something from without. It is
+unhistorical elements that have brought us from mere
+history to more than history. We have created the concept
+of evolution, not from our knowledge of the single line of
+events attendant on a single egg of a frog, but from our
+knowledge that there are billions or more of frogs’ eggs, all
+destined to the same “history,” which therefore is not
+history at all. We have created the concept of cumulation<span class="pagenum" title="303"><a name="Page_303" id="Page_303"></a></span>
+not from the historical study of a single mountain, but
+from our knowledge of physics and chemistry and so-called
+dynamical geology: by the aid of these sciences we “understood”
+historically, and thus our understanding came from
+another source than history itself.</p>
+
+<p><span class="pagenum" title="304"><a name="Page_304" id="Page_304"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Phylogenetic Possibilities</span></h4>
+
+<p>Does history always gain its importance from what it
+is not? Must history always lose its “historical” aspect,
+in order to become of importance to human knowledge?
+And can it <em>always</em> become “science” by such a transformation?
+We afterwards shall resume this discussion on a
+larger scale, but at present we shall apply what we have
+learned to hypothetic phylogeny. What then are the
+possibilities of phylogeny, to what class of history would it
+belong if it were complete? Of course, we shall not be able
+to answer this question fully; for phylogeny is <em>not</em> complete,
+and scarcely anything is known about the factors
+which act in it. But in spite of that, so much, it seems to
+me, is gained by our analysis of the possible aspects of history
+and of the factors possibly concerned in transformism, that
+we are at least able to formulate the possibilities of a
+phylogeny of the future in their strict logical outlines.</p>
+
+<p>Darwinism and Lamarckism, regarding organic forms as
+contingent, must at the same time regard organic history
+as a cumulation; they indeed <em>might</em> claim to furnish an
+historical explanation in the realm of biology&mdash;if only their
+statements were unimpeachable, which as we have seen,
+they are not.</p>
+
+<p>But any transformistic theory, which locates the very<span class="pagenum" title="305"><a name="Page_305" id="Page_305"></a></span>
+principle of phylogeny in the organism itself, and to which
+therefore even organic forms would be not accidental but
+essential, might be forced to regard the descent of organisms
+as a true evolution. The singularities in phylogenetic
+history would thus become links in one whole: history proper
+would become more than history. But I only say that
+phylogeny <em>might</em> be evolution, and in fact I cannot admit
+more than this <i lang="la" xml:lang="la">a priori</i>, even on the basis of an internal
+transformistic principle, as has been assumed. Such a
+principle also might lead always from one typical state of
+organisation to the next: but <i lang="la" xml:lang="la">ad infinitum</i>.<a name="FNanchor_163_163" id="FNanchor_163_163"></a><a href="#Footnote_163_163" class="fnanchor">163</a> Then
+phylogeny, though containing what might in some sense
+be called “progress,” would not be “evolution”; it might
+even be called cumulation in such a case, in spite of the
+internal transforming principle, though, of course, cumulation
+from within would always mean something very
+different from cumulation from <span class="nowrap">without.<a name="FNanchor_164_164" id="FNanchor_164_164"></a><a href="#Footnote_164_164" class="fnanchor">164</a></span></p>
+
+<p>But we must leave this problem an open question, as
+long as our actual knowledge about transformism remains
+as poor as it is. We need only add, for the sake of logical
+interest, that phylogeny, as a true evolution, would necessarily
+be characterised by the possibility of being repeated.</p>
+
+<p><span class="pagenum" title="306"><a name="Page_306" id="Page_306"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The History of Mankind</span></h4>
+
+<p>We only assume hypothetically that phylogeny has
+happened, and we know scarcely anything about the factors
+concerned in it. Now, it certainly would be of great importance,
+if at least in a small and definite field of biology we
+were able to state a little more, if the <em>mere fact</em> of phylogeny,
+of “history,” were at least beyond any doubt within a certain
+range of our biological experience. And indeed there is
+one department of knowledge, where history, as we know,
+<em>has happened</em>, and where we also know at least some of the
+factors concerned in it.</p>
+
+<p>I refer to the history of mankind; and I use the
+expression not at all in its anthropological or ethnographical
+sense, as you might expect from a biologist, but in its
+proper and common sense as the history of politics and of
+laws and of arts, of literature and of sciences: in a
+word, the history of civilisation. Here is the only field,
+where we know that there actually <em>are</em> historical facts:
+let us try to find out what these facts can teach us about
+their succession.</p>
+
+<p>The theory of history in this narrower meaning of the
+word has been the subject of very numerous controversies
+in the last twenty years, especially in Germany, and these
+controversies have led very deeply into the whole<span class="pagenum" title="307"><a name="Page_307" id="Page_307"></a></span>
+philosophical view of the universe. We shall try to treat
+our subject as impartially as possible.</p>
+
+<p>Hegel says, in the introduction to his <cite lang="de" xml:lang="de">Phänomenologie
+des Geistes</cite>: “<cite lang="de" xml:lang="de">Die Philosophie muss sich hüten erbaulich
+sein zu wollen</cite>” (“Philosophy must beware of trying to
+be edifying”). These words, indeed, ought to be inscribed
+on the lintel of the door that leads into historical
+methodology, for they have been sadly neglected by
+certain theoretical writers. Instead of analysing history in
+order to see what it would yield to philosophy, they have
+often made philosophy, especially moral philosophy, the
+starting-point of research, and history then has had to obey
+certain doctrines from the very beginning.</p>
+
+<p>We shall try as far as we can not to become “erbaulich”
+in our discussions. We want to learn from history for the
+purposes of philosophy, and we want to learn from history
+as from a phenomenon in time and in space, just as we
+have learnt from all the other phenomena regarding life in
+nature. Every class of phenomena of course may be
+studied with respect to generalities as well as with respect
+to particulars. The particular, it is true, has not taught us
+much in our studies so far. Perhaps it may be successful
+in the domain of history proper.</p>
+
+<p>If I take into consideration what the best authors of
+the last century have written about human history with
+respect to its general value, I cannot help feeling that
+none of them has succeeded in assigning to history a
+position where it would really prove to be of great importance
+for the aims of philosophical inquiry. Is that the
+fault of the authors or of human history? And what then
+would explain the general interest which almost every one<span class="pagenum" title="308"><a name="Page_308" id="Page_308"></a></span>
+takes, and which I myself take in history in spite of this
+unsatisfactory state of things?</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CUMULATIONS IN HUMAN HISTORY</span></p>
+
+<p>Let us begin our analytical studies of the value and the
+meaning of human history, by considering some opinions
+which deserve the foremost place in our discussion,
+not as being the first in time, but as being the first in
+simplicity. I refer to the views of men like Buckle, Taine,
+and Lamprecht, and especially Lamprecht, for he has tried
+the hardest to justify theoretically what he regards the
+only scientific aim of history to be. If we may make use
+of our logical scheme of the three possible aspects of
+history, it is clear from the beginning that the history of
+mankind, as understood by the three authors we have
+named, but most particularly by Lamprecht, is neither a
+mere enumeration nor a true evolution, but that it has to
+do with <em>cumulations</em>, in the clearest of their possible forms.
+The processes of civilisation among the different peoples
+are in fact to be compared logically with the origin of
+volcanoes or mountain-ranges in Japan, or in Italy, or in
+America, and show us a typical series of consecutive
+phases, as do these. There exists, for instance, in the
+sphere of any single civilisation an economic system, founded
+first on the exchange of natural products, and then on
+money. There are, or better, perhaps, there are said to be,
+characteristic phases succeeding one another in the arts, such
+as the “typical,” the “individualistic,” and the “subjective”
+phases. Any civilisation may be said to have its “middle
+ages,” and so on. All these are “laws” of course in the<span class="pagenum" title="309"><a name="Page_309" id="Page_309"></a></span>
+meaning of “rules” only, for they are far from being
+elemental, they are not “principles” in any sense. And
+there are other sorts of “rules” at work for exceptional
+cases: revolutions have their rules, and imperialism, for
+instance, has its rules also.</p>
+
+<p>Now, as the consecutive phases of history have been
+shown to be true cumulations, it follows that the rules
+which are revealed by our analysis, are rules relating to
+the very origin of cumulations also. The real <em>element</em>
+upon which the cumulation-phases, and the cumulation-rules
+together rest, is the human individual as the bearer
+of its psychology. Nobody, it seems to me, has shown
+more clearly than Simmel that it is the human individual,
+<i lang="la" xml:lang="la">qua</i> individual, which is concerned in <em>every</em> kind of history.</p>
+
+<p>History, viewed as a series of cumulations, may in fact
+claim to satisfy the intellect by “explaining” a good deal
+of historical facts. It explains by means of the elemental
+factor of individual psychology, which every one knows
+from himself, and by the simple concept that there is a
+cumulation, supported by language and by writing as its
+principal factors, which both of course rest on psychology
+again. Psychology, so we may say, is capable of leading to
+cumulation phenomena; the cumulations in history are
+such that we are able to understand them by our everyday
+psychology; and history, so far as it is of scientific value,
+consists exclusively of cumulations.</p>
+
+<p>No doubt there is much truth in such a conception of
+history; but no doubt also, it puts history in the second
+rank as compared with psychology; just as geology stands
+in the second rank as compared with chemistry or physics.
+Geology and human history may lead to generalities in the<span class="pagenum" title="310"><a name="Page_310" id="Page_310"></a></span>
+form of rules, but these rules are <em>known</em> to be not elemental
+but only cumulative; and moreover, we know the elements
+concerned in them. The elements, therefore, are the real
+subjects for further studies in the realm of philosophy,
+but not the cumulations, not the rules, which are known
+to be due to accidental constellations. Of course, the
+“single” is the immediate subject of this sort of history,
+but the single as such is emphatically pronounced to be
+insignificant, and the cumulations and the cumulative rules,
+though “singles” in a higher sense of the word, are shown
+to be anything but elementalities.</p>
+
+<p>Therefore, on a conception of human history such as
+that of Buckle, Taine, Lamprecht, and others, we, of course,
+ought to take an interest in history, because what is
+“explained” by historical research touches all of us most
+personally every day and every year. But our philosophy,
+our view of the world, would remain the same without
+history as it is with it. We only study history, and
+especially the history of our own civilisation, because it is a
+field of actuality which directly relates to ourselves, just
+as we study for practical purposes the railway time-tables
+of our own country, but not of Australia; just as we study
+the local time-table in particular.</p>
+
+<p>If the mere <i lang="la" xml:lang="la">rerum cognoscere causas</i> is regarded as
+the criterium of science, history of Lamprecht’s type of
+course is a science, for its explanations rest upon the
+demonstration of the typical constellations and of the
+elemental factor or law from which together the next constellations
+are known necessarily to follow. But history of
+this kind is not a science in the sense of discovering <i lang="de" xml:lang="de">den
+ruhenden Pol in der Erscheinungen Flucht</i>.</p>
+
+<p><span class="pagenum" title="311"><a name="Page_311" id="Page_311"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HUMAN HISTORY NOT AN “EVOLUTION”</span></p>
+
+<p>Quite another view of history has been maintained by
+Hegel, if his explanations about the <i lang="de" xml:lang="de">Entwicklung des
+objectiven Geistes</i> (“the development of the objective mind”)
+may be co-ordinated with our strictly logical categories of
+the possible aspects of history. But I believe we are
+entitled to say that it was a real <em>evolution</em> of mankind
+that Hegel was thinking of; an evolution regarding mankind
+as spiritual beings and having an end, at least ideally.
+One psychical state was considered by Hegel to generate
+the next, not as a mere cumulation of elemental stages,
+but in such a way that each of the states would represent
+an elementality and an irreducibility in itself; and he
+assumed that there was a continuous series of such stages
+of the mind through the course of generations. Is there
+any sufficient reason in historical facts for such an
+assumption?</p>
+
+<p>The mind “evolves” itself from error to truth by what
+might be called a system of contradictions, according to
+Hegel, with respect to logic as well as to morality; the
+sum of such contradictions becoming smaller and less
+complicated with every single step of this evolution. No
+doubt there really occurs a process of logical and moral
+refining, so to say, in the individual, and no doubt also,
+the results of this process, as far as attained, can be
+handed down to the next generation by the spoken word
+or by books. But it is by no means clear, I think, that
+this process is of the type of a real evolution towards an
+end, so far as it relates to the actual series of generations
+as such. On the contrary, it seems to me that we have<span class="pagenum" title="312"><a name="Page_312" id="Page_312"></a></span>
+here simply what we meet everywhere in history&mdash;a sort
+of cumulation resting upon a psychological basis.</p>
+
+<p>The dissatisfaction that exists at any actual stage of
+contradiction, both moral and logical, is one of the psychical
+factors concerned; the faculty of reasoning is the other.
+Now it is a consequence of the reasoning faculty that the
+dissatisfaction continually decreases, or at least changes in
+such a way that each partial result of the logical process
+brings with it the statement of new problems. The
+number of such problems may become less, as the logical
+process advances, and, indeed, there is an ideal state, both
+logical and moral, in which there are no more problems,
+but only results, though this ideal could hardly be regarded
+as attainable by the <em>human</em> mind. In the history of those
+sciences which are wholly or chiefly of the <i lang="la" xml:lang="la">a priori</i> type,
+this process of deliverance from contradictions is most
+advantageously to be seen. It is obvious in mechanics
+and thermodynamics, and the theory of matter is another
+very good instance. A certain result is reached; much
+seems to be gained, but suddenly another group of facts
+presents itself, which had been previously unknown or
+neglected. The first result has to be changed or enlarged;
+many problems of the second order arise; there are contradictions
+among them, which disappear after a certain
+alteration of what was the first fundamental result, and so
+on. And the same is true about morality, though the
+difficulties are much greater here, as a clear and well-marked
+standard of measurement of what is good and
+what is bad, is wanting, or at least, is not conceded unanimously.
+But even here there is a consensus on some
+matters: one would hardly go back to slavery again, for<span class="pagenum" title="313"><a name="Page_313" id="Page_313"></a></span>
+instance, and there are still other points in morality which
+are claimed as ideals at least by a great majority of moral
+thinkers.</p>
+
+<p>But all this is not true “evolution,” and indeed, I doubt
+if such an evolution of mankind could be proved at present
+in the sense in which Hegel thought it possible. The
+process of logical and moral deliverance from contradictions
+<em>might</em> come to an end in <em>one</em> individual; at least that is a
+logical possibility, or it might come to an end in, say, six
+or ten generations. And there is, unfortunately for mankind,
+no guarantee that the result will not be lost again
+and have to be acquired a second time. All this proves
+that what Hegel regarded as an evolution of the race
+is only a cumulation. There is nothing evolutionary
+relating to the generations of mankind as such. At least,
+nothing is proved about such an <span class="nowrap">evolution.<a name="FNanchor_165_165" id="FNanchor_165_165"></a><a href="#Footnote_165_165" class="fnanchor">165</a></span></p>
+
+<p>You may call my view pessimistic, and indeed you may
+be right so far as the sum total of human beings as such
+is in question. But, be it pessimistic or not, we are here
+moving on scientific ground only, and have merely to study
+the probability or improbability of problematic facts, and
+with such a view in our mind, we are bound to say that a
+true logical and moral evolution of mankind is not at all
+supported by known facts. There is a process of logical
+and moral perfection, but this process is <em>not one</em>, is not
+“single” in its actuality; it is not connected with the one
+and single line of history, but only with a few generations
+each time it occurs, or even with one individual, at least<span class="pagenum" title="314"><a name="Page_314" id="Page_314"></a></span>
+ideally. And this process is not less a process of cumulation
+than any other sort of development or so-called
+“progress” in history is. Philosophers of the Middle
+Ages, in fact, sometimes regarded human history as <em>one</em>
+evolutionary unity, beginning with the Creation and ending
+with the Day of Judgment; but every one must agree, I
+think, that even under the dogmatic assumptions of
+orthodoxy history would by no means <em>necessarily</em> be an
+“evolution.” Even then the paths taken by different
+individuals or different branches of the human race on their
+way to redemption <em>can</em> be regarded as independent lines.</p>
+
+<p>Thus Hegel’s conception of an evolution of mankind,
+it seems to me, fails to stand criticism. By emphasising
+that there are certain lines of development in history which
+bring with them a stimulus to perfection, and that these
+lines relate to all that is highest in culture, Hegel certainly
+rendered the most important service to the theory of
+history; but in spite of that he has revealed to us only a
+special and typical kind of cumulation process, and nothing
+like an evolution. We may say that the very essence
+of history lies in this sort of cumulation, in this “pseudo-evolution”
+as we might say; and if we like to become
+moral metaphysicians we might add, that it is for the
+sake of the possibility of this sort of cumulation that
+man lives his earthly life; the Hindoos say so, indeed, and
+so do many Christians. But even if we were to depart
+from our scientific basis in this way we should not get
+beyond the realm of cumulations.</p>
+
+<p>All this, of course, is not to be understood to affirm
+that there never <em>will</em> be discovered any real evolutionary
+element in human history&mdash;in the so-called <span class="pagenum" title="315"><a name="Page_315" id="Page_315"></a></span>“subconscious”
+sphere perhaps&mdash;but at present we certainly are ignorant
+of such an element.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE PROBLEM OF THE “SINGLE” AS SUCH</span></p>
+
+<p>If history has failed to appear as a true evolution, and
+if, on the other hand, it reveals to us a great sum of
+different cumulations, some of very great importance, others
+of minor importance, what then remains of the importance
+of the single historical event in its very singleness?
+What importance can the description of this event have
+with regard to our scientific aims? We could hardly
+say at present that it appears to be of very much importance
+at all. The historical process as a whole has proved
+to be not a real elemental unit, as far as we know, and
+such elemental units as there are in it have proved to be
+of importance only <em>for</em> individual psychology but not <em>as</em>
+history. History has offered us only instances of what
+every psychologist knew already from his own experience,
+or at least might have known if he had conceived his
+task in the widest possible spirit.</p>
+
+<p>But is no other way left by which true history might
+show its real importance in spite of all our former analysis?
+Can history be saved perhaps to philosophical science by
+any new sort of reasoning which we have not yet applied
+to it here.</p>
+
+<p>As a matter of fact, such new reasoning has been tried,
+and <span class="nowrap">Rickert,<a name="FNanchor_166_166" id="FNanchor_166_166"></a><a href="#Footnote_166_166" class="fnanchor">166</a></span> in particular, has laid much stress upon the
+point that natural sciences have to do with generalities,
+while historical sciences have to do with the single in its<span class="pagenum" title="316"><a name="Page_316" id="Page_316"></a></span>
+singleness only, and, in spite of that, are of the highest
+philosophical importance. He does not think very highly
+of so-called “historical laws,” which must be mere
+borrowings from psychology or biology, applied to history
+proper, and not touching its character as “history.” We
+agree with these statements to a considerable extent. But
+what then about “history proper,” what about “the single
+in its very singleness”?</p>
+
+<p>Let us say at first a few words about this term “single”
+so very often applied by us. In the ultimate meaning of
+the word, of course, the series of actual sensations or “presentations”
+is the “single” which is given “historically”
+to each individual, and therefore to the writer of history
+also, and in fact, history as understood by Rickert is based
+to a great extent upon this primordial meaning of single
+“givenness.” The word “single,” in his opinion, relates to
+the <em>actual and true specification</em> of any event, or group of
+events, at a given time and at a given locality in space,
+these events possessing an identity of their own and never
+being repeated without change of identity. If the subject-matter
+of history is defined like this, then there are, indeed,
+“Grenzen der naturwissenschaftlichen Begriffsbildung” with
+regard to history, for natural sciences have nothing to do
+with the single in such an understanding of the word.</p>
+
+<p>Rickert says somewhere that history as a real evolution,
+as one totality of a higher order, would cease to be proper
+history: and he is right. History, in fact, would soon lose
+the character of specific attachment to a given space and to
+a given time, and would lose its “non-repeatability,” in the
+logical sense at least, if it were one <em>unit</em> in reality: as
+soon as it was that, it would have become a logical<span class="pagenum" title="317"><a name="Page_317" id="Page_317"></a></span>
+generality, an element in nature, so to say, in spite of its
+factual singularity. But history is not obliged to become
+that, Rickert states; and we may add that history in fact
+cannot become that, because it simply proves not to be an
+evolution as far as we know at present.</p>
+
+<p>But what importance does Rickert attach to his history
+specified and non-repeatably single?</p>
+
+<p>History has a logic of its own, he says; the scheme
+of its logic is not the syllogism, but the <em>relation to “values.”</em>
+So far as the single historical facts can be related to values,
+they are of historical importance, and in such a way only
+does history in its proper sense become important in itself
+and through itself at the same time. Must history always
+lose its historical aspect to become of importance to human
+knowledge? That is the question we asked whilst considering
+the general logical types of the “evolution” and
+“cumulation” that arose out of the analysis of the
+historical facts of problematic phylogeny. It now might
+seem that this question may be answered, and that it may
+be answered by a clear and simple “No.” The history
+of mankind, according to Rickert, seems to be important
+in itself, and without borrowing from any other branch
+of study. But is his reasoning altogether cogent and
+convincing?</p>
+
+<p>Has it really been able to attribute to history in the
+strictest sense such an importance for philosophy, for the
+theory of the universe, “für die Weltanschauung,” that
+history proper may in fact be allowed to take its place
+beside science proper?</p>
+
+<p>The relation to values is not to include any kind of
+“Bewertung” of judgment, Rickert allows. In fact, history<span class="pagenum" title="318"><a name="Page_318" id="Page_318"></a></span>
+of any kind would hardly satisfy the reader, if moral
+judgment were its basis. Every reader, of course, has a
+moral judgment of his own, but, unfortunately, almost
+every reader’s judgment is different from his neighbour’s,
+and there is no uniformity of moral principles as there
+is of geometrical ones. We shall come back to this point.
+At present we only state the fact that indeed moral
+judgment can never be the foundation of history, and that
+Rickert was very right to say so: it is enough to put the
+names of Tolstoy and Nietzsche together to understand
+how devoid of even the smallest general validity would be
+a history resting upon moral principles.</p>
+
+<p>But what then are the “values” of Rickert to which
+history has to relate, if moral values in their proper sense
+have to be excluded? It is here that his discussions
+begin to become obscure and unsatisfactory, and the
+reason is fairly intelligible. He is trying to prove the
+impossible; he wants to put history beside science in its
+real philosophical importance, in spite of the fact that
+all evidence to establish this is wanting.</p>
+
+<p>These “values,” to which every historical act in its
+singularity has to be related in order to become an
+element of real history, are they after all nothing but those
+groups of the products of civilisation which in fact absorb
+the interest of men? Is it to groups of cultural
+phenomena, such as arts, science, the State, religion, war,
+economics, and so on, that “historical” facts have to be
+related? Yes, as far as I understand our author, it is
+simply to these or other even less important groups of
+cultural effects&mdash;cultural “cumulations,” to apply our term&mdash;that
+a single action of a man or a group of men<span class="pagenum" title="319"><a name="Page_319" id="Page_319"></a></span>
+must bear some relation in order to become important
+historically.</p>
+
+<p>But what does that mean? Is the relation to such
+“values” to be regarded as really rendering history equal
+to the sciences of nature in philosophical importance?</p>
+
+<p>In the first place, there is no more agreement about
+such “values” than there is in the field of morals. Imagine,
+for instance, a religious enthusiast or recluse writing
+history! I fancy there would be very little mention of
+warriors and politicians: war and politics would not be
+“values” in <em>any</em> sense to such a man. And we know that
+there are others to whom those products of civilised life
+rank amongst the first. Rickert well notes that there is
+one great objection to his doctrine&mdash;the character of
+<span class="nowrap">universality<a name="FNanchor_167_167" id="FNanchor_167_167"></a><a href="#Footnote_167_167" class="fnanchor">167</a></span> is wanting to his history, or rather to the
+values forming its basis; for there cannot be, or at least
+there actually is not at present, a <i lang="la" xml:lang="la">consensus omnium</i> with
+regard to these “values.”</p>
+
+<p>I am convinced that Rickert is right in his conception
+of real “history” as the knowledge of the single acts of
+mankind. But this conception proves just the contrary
+of what Rickert hoped to prove; for history in this
+sense is moulded by the actual products of culture, that
+is, by the effects which actually exist as groups of cultural
+processes, and it cannot be moulded by anything else;
+the historian correlates history with what <em>interests</em> him
+personally.</p>
+
+<p>Here now we have met definitively the ambiguous
+word: history indeed is to end in “interest” and in being<span class="pagenum" title="320"><a name="Page_320" id="Page_320"></a></span>
+“interesting.” There is nothing like a real “value” in
+any sense underlying history; the word <em>value</em> therefore
+would better give place to the term “centre of interest”&mdash;a
+collection of stamps may be such a “centre.” History,
+then, as the knowledge of cultural singularities, is “interesting,”
+and its aspects change with the interests of the
+person who writes history: there is no commonly accepted
+foundation of <span class="nowrap">history.<a name="FNanchor_168_168" id="FNanchor_168_168"></a><a href="#Footnote_168_168" class="fnanchor">168</a></span></p>
+
+<p>And it follows that history as regarded by Rickert cannot
+serve as the preliminary to philosophy. It <em>may</em> <span class="nowrap">be<a name="FNanchor_169_169" id="FNanchor_169_169"></a><a href="#Footnote_169_169" class="fnanchor">169</a></span> of
+use for personal edification or for practical life: granting
+that the “centres of interest” as referred to are of any real
+ethical or at least factual importance. But you may take
+away from history even the greatest personalities, and your
+view of the universe, your philosophy, would remain the
+same, except of course so far as these personalities themselves
+have contributed to philosophy in any way.</p>
+
+<p>Now, on the other hand, it is worth noticing that, even
+if there were generally accepted “values,” history as the
+doctrine of singularities would be deprived of philosophical
+importance. Its single cases would then be merely <em>instances</em>
+of certain types of actions and occurrences which have been<span class="pagenum" title="321"><a name="Page_321" id="Page_321"></a></span>
+proved to be “valuable,” <i>i.e.</i> to be centres of interest, before-hand.
+Rickert has observed that the relation to any judgments
+about moral values would render history unhistorical,
+for the generalities to which it is related would be the
+main thing in such a case. But he did not notice, as far as
+I can see, that history, if related to <em>any</em> “values” whatever&mdash;if
+there were any generally conceded&mdash;would become
+“non-historical” just as well: for the <em>generalities</em> as expressed
+in the “values” would be the main thing in this
+case also. In fact, there is no escape from the dilemma:&mdash;either
+no general centres of interest, and therefore a
+mere subjective “history”; or general “values,” and therefore
+history a mere collection of instances.</p>
+
+<p>The “limits of concepts in natural sciences” then are
+the same as the limits of <em>intellectual</em> concepts in general.
+For intellectual, <i>i.e.</i> logical, “values” are the only centres of
+interest that can lay claim to universality. There are
+indeed other groups of important concepts, the ethical ones,
+but they are outside intellectuality and may enter philosophy
+only as problems, not as solutions. Therefore, history in
+its true sense, even if related to the ethical group of
+concepts, has no bearing on philosophy. Philosophically
+it remains a sum of contingencies, in which certain laws
+of cumulation and certain series of cumulation may be
+discovered. But these series and these laws, if taken
+scientifically, only offer us instances of psychological
+elementalities. They also might be instances of primary
+ethical states and relations, if there were such relations of
+more than a mere subjective and personal validity, which
+at present at least seems not to be the case.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="322"><a name="Page_322" id="Page_322"></a></span></p>
+
+
+
+
+<h3><span class="smcap">Conclusions about Systematics and History in
+General</span></h3>
+
+
+<p>We have finished our analysis of the history of mankind
+as the only instance of an historical biological process
+that is actually known to exist and is not only assumed
+hypothetically.</p>
+
+<p>What we have learnt from this analysis, though certainly
+important in itself, has not afforded us any new result for
+theoretical biology.</p>
+
+<p>The history of mankind is proved to be of philosophical
+importance, at present, so far only as it offers instances
+to the science of psychology; besides that it may be of
+value and importance to many conditions of practical and
+emotional life.</p>
+
+<p>There is only one science, and only one kind of logic
+too. “In one sense the only science”&mdash;that was the
+predicate attached to natural sciences by Lord Gifford, as
+you will remember from our first lecture. It is not
+without interest to note that at the end of our course of
+this year, we find occasion to realise on what a deep insight
+into logical and philosophical relations that sentence was
+grounded.</p>
+
+<p>We now leave the theory of human history, which has
+been to us nothing more than a branch of biological<span class="pagenum" title="323"><a name="Page_323" id="Page_323"></a></span>
+phylogeny in general. We have dealt with it from quite
+a simple realistic point of view, not burdened by any
+epistemology. We have taken psychical states as realities,
+just as we have taken as realities all parts of the animal
+body; and it seems to me that we were entitled to do so,
+as it was only history <em>about</em> the actions of men we were
+dealing with, not their actions themselves. Next summer
+we shall begin with studying action as action, and then, in
+fact, a well-founded epistemology will be among our first
+requirements. And history also will come on the scene
+once more.</p>
+
+<p>It is the main result of our last chapters, devoted to
+systematics, transformism, and human history in particular,
+that no conclusions really useful for further philosophical
+discussion can at present be gained from these topics;
+there either is too little actual knowledge, or there are only
+combinations of natural elementalities, but no elementalities
+of any new kind.</p>
+
+<p>To sum up: we expected that a rational system might
+be a biological result of the future, but we could not claim
+at all to possess such a system. We said that transformism
+might be proved one day to be a true evolution, governed
+by one immanent principle, which then would have to be
+regarded as a new primary factor in nature, but we did not
+know the least about that principle.</p>
+
+<p>Human history, on the other hand&mdash;that is, the only
+historical process concerned with life that is actually
+known to have occurred&mdash;could not teach us anything of
+an elemental character, since human history, at present at
+least, did not appear to us as a true evolution, but only as a
+sum of cumulations, and the singularities of this history,<span class="pagenum" title="324"><a name="Page_324" id="Page_324"></a></span>
+taken by themselves, could only be of practical or emotional
+interest.</p>
+
+<p>Thus it is from the study of the living <em>individual</em> only,
+that we have so far gained elemental principles in biology.
+The analysis of individual morphogenesis and of individual
+inheritance has yielded us the concept of entelechy as the
+chief result of the first part of our lectures. We shall be
+able to get more proofs of the autonomy of the individual
+life in the beginning of the second part; indeed, the
+beginning of that part will bring us to a full understanding
+of what the living individual is, and what it is not. And
+then the real philosophy of life, that is, the philosophy of
+the individual, will occupy us for the greater half of our
+lectures of next summer.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="325"><a name="Page_325" id="Page_325"></a></span></p>
+
+
+
+
+<h2>INDEX</h2>
+
+
+<p>
+Absolute, <a href="#Page_5">5</a><br />
+Acclimatisation, <a href="#Page_191">191</a><br />
+Acquired characters, <a href="#Page_217">217</a>, <a href="#Page_276">276</a> f.<br />
+Adaptation (definition), <a href="#Page_166">166</a>, <a href="#Page_171">171</a>, <a href="#Page_185">185</a><br />
+<span class="ml1em">to changes from without, <a href="#Page_172">172</a> ff.</span><br />
+<span class="ml1em">functional, <a href="#Page_114">114</a>, <a href="#Page_176">176</a> ff.</span><br />
+<span class="ml1em">and Lamarckism, <a href="#Page_272">272</a>, <a href="#Page_280">280</a></span><br />
+<span class="ml1em">mechanical, <a href="#Page_177">177</a> f.</span><br />
+<span class="ml1em">morphological, <a href="#Page_168">168</a> ff.</span><br />
+<span class="ml1em">physiological, <a href="#Page_184">184</a> ff.</span><br />
+<span class="ml1em">primary and secondary, <a href="#Page_188">188</a> f.</span><br />
+Adaptedness, <a href="#Page_186">186</a> f.<br />
+<i>Adiantum</i>, <a href="#Page_279">279</a><br />
+Adventitious, <a href="#Page_55">55</a>, <a href="#Page_74">74</a>, <a href="#Page_111">111</a>, <a href="#Page_221">221</a><br />
+Albumen, <a href="#Page_200">200</a><br />
+Allelomorphs, <a href="#Page_231">231</a><br />
+Amphibious plants, <a href="#Page_172">172</a> ff.<br />
+Annelids, <a href="#Page_65">65</a>, <a href="#Page_70">70</a>, <a href="#Page_221">221</a><br />
+Answering reaction, <a href="#Page_181">181</a><br />
+Anti-bodies, <a href="#Page_206">206</a> f.<br />
+Antitoxins, <a href="#Page_207">207</a> f.<br />
+<i>A priori</i>, <a href="#Page_6">6</a><br />
+Aristotle, <a href="#Page_144">144</a><br />
+<i>Ascaris</i>, <a href="#Page_93">93</a><br />
+<i>Aspergillus</i>, <a href="#Page_195">195</a><br />
+Assimilation, <a href="#Page_17">17</a><br />
+Atrophy, <a href="#Page_178">178</a><br />
+Autonomy of life, <a href="#Page_143">143</a>, <a href="#Page_224">224</a> f., <a href="#Page_324">324</a><br />
+<br />
+Babák, <a href="#Page_177">177</a><br />
+Baer, C. E. v., <a href="#Page_48">48</a> f. 282<br />
+Bateson, <a href="#Page_229">229</a> ff., <a href="#Page_238">238</a><br />
+Bayliss, <a href="#Page_204">204</a>, <a href="#Page_212">212</a><br />
+<i>Begonia</i>, <a href="#Page_221">221</a><br />
+Bergson, <a href="#Page_305">305</a><br />
+Berkeley, <a href="#Page_6">6</a><br />
+Berthold, <a href="#Page_91">91</a><br />
+Biogenetisches Grundgesetz, <a href="#Page_248">248</a><br />
+Biology, <a href="#Page_8">8</a> ff., <a href="#Page_15">15</a> f.<br />
+Blaringhem, <a href="#Page_238">238</a>, <a href="#Page_276">276</a><br />
+Blastoderm, <a href="#Page_39">39</a><br />
+Blastomeres, <a href="#Page_36">36</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a> f., <a href="#Page_79">79</a><br />
+Blastula, <a href="#Page_37">37</a>, <a href="#Page_61">61</a>, <a href="#Page_79">79</a><br />
+Blumenbach, <a href="#Page_26">26</a><br />
+Boirivant, <a href="#Page_174">174</a><br />
+Bonnet, <a href="#Page_26">26</a><br />
+Boveri, <a href="#Page_29">29</a>, <a href="#Page_60">60</a>, <a href="#Page_95">95</a>, <a href="#Page_235">235</a> f.<br />
+Buckle, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Bunge, v., <a href="#Page_248">248</a><br />
+Bütschli, <a href="#Page_91">91</a><br />
+<br />
+Calcium, <a href="#Page_97">97</a><br />
+Calkins, <a href="#Page_33">33</a><br />
+Cambium, <a href="#Page_120">120</a>, <a href="#Page_183">183</a>, <a href="#Page_220">220</a><br />
+Catalysis, <a href="#Page_164">164</a>, <a href="#Page_203">203</a><br />
+Categories, <a href="#Page_6">6</a> f.<br />
+Cause, <a href="#Page_99">99</a> ff.<br />
+Cell, <a href="#Page_27">27</a> f.<br />
+<span class="ml1em">-division, <a href="#Page_28">28</a> ff., <a href="#Page_53">53</a>, <a href="#Page_94">94</a></span><br />
+<span class="ml1em">-lineage, <a href="#Page_58">58</a>, <a href="#Page_70">70</a></span><br />
+<span class="ml1em">-theory, <a href="#Page_27">27</a> f.</span><br />
+Chemical theory (of morphogenesis), <a href="#Page_134">134</a> ff.<br />
+Chemistry, systematics of, <a href="#Page_244">244</a>.<br />
+Child, C. M., <a href="#Page_180">180</a><br />
+Chromatic regulations, <a href="#Page_197">197</a><br />
+Chromatin, <a href="#Page_28">28</a> f.<br />
+Chromosomes, <a href="#Page_30">30</a>, <a href="#Page_237">237</a><br />
+Chun, <a href="#Page_66">66</a><br />
+Classification, <a href="#Page_246">246</a> f.<br />
+<i>Clavellina</i>, <a href="#Page_129">129</a>, <a href="#Page_154">154</a>, <a href="#Page_162">162</a> f.<br />
+Cleavage, <a href="#Page_35">35</a> ff., <a href="#Page_53">53</a>, <a href="#Page_58">58</a>, <a href="#Page_60">60</a>, <a href="#Page_63">63</a>, <a href="#Page_71">71</a>, <a href="#Page_92">92</a><br />
+Colloids, <a href="#Page_187">187</a><br />
+Compensatory process, <a href="#Page_112">112</a><br />
+Complex potencies, <a href="#Page_112">112</a>, <a href="#Page_120">120</a><br />
+Conic sections, <a href="#Page_243">243</a><br />
+Conjugation, <a href="#Page_33">33</a><br />
+Conklin, <a href="#Page_86">86</a><br />
+Contingency, <a href="#Page_218">218</a>, <a href="#Page_284">284</a> ff. 304<br />
+Continuity of germ-plasm, <a href="#Page_215">215</a>, <a href="#Page_227">227</a><br />
+<span class="pagenum" title="326"><a name="Page_326" id="Page_326"></a></span><br />
+Cope, <a href="#Page_273">273</a><br />
+Correlation (of masses), <a href="#Page_93">93</a><br />
+<span class="ml1em">(of parts), <a href="#Page_247">247</a></span><br />
+Correns, <a href="#Page_228">228</a><br />
+Crampton, <a href="#Page_70">70</a> f.<br />
+Crayfish, <a href="#Page_105">105</a><br />
+Ctenophores, <a href="#Page_66">66</a><br />
+Cumulation, <a href="#Page_301">301</a> ff., <a href="#Page_308">308</a> ff., <a href="#Page_314">314</a>, <a href="#Page_317">317</a><br />
+Cuvier, <a href="#Page_247">247</a><br />
+<br />
+Darwin, Ch., <a href="#Page_260">260</a> ff., <a href="#Page_271">271</a>, <a href="#Page_283">283</a><br />
+Darwinism, <a href="#Page_260">260</a> ff., <a href="#Page_271">271</a>, <a href="#Page_283">283</a> ff., <a href="#Page_293">293</a> ff., <a href="#Page_304">304</a><br />
+Davenport, <a href="#Page_191">191</a>, <a href="#Page_206">206</a><br />
+Delage, <a href="#Page_32">32</a><br />
+Descent, theory of, <a href="#Page_250">250</a> ff.<br />
+Description, <a href="#Page_12">12</a>, <a href="#Page_50">50</a><br />
+Detto, <a href="#Page_172">172</a><br />
+Directive stimuli, <a href="#Page_102">102</a> ff.<br />
+Doncaster, <a href="#Page_232">232</a><br />
+Dreyer, <a href="#Page_92">92</a><br />
+<br />
+<i><a id="Echinus"></a>Echinus</i>, <a href="#Page_27">27</a>, <a href="#Page_33">33</a> ff., <a href="#Page_60">60</a> ff., <a href="#Page_68">68</a>, <a href="#Page_81">81</a>, <a href="#Page_85">85</a>, <a href="#Page_87">87</a>, <a href="#Page_98">98</a>, <a href="#Page_104">104</a>, <a href="#Page_108">108</a>, <a href="#Page_111">111</a>, <a href="#Page_154">154</a>, <a href="#Page_232">232</a>, <a href="#Page_235">235</a><br />
+Ectoderm, <a href="#Page_41">41</a>, <a href="#Page_81">81</a>, <a href="#Page_122">122</a><br />
+Egg, <a href="#Page_31">31</a>, <a href="#Page_33">33</a> f.<br />
+Ehrlich, <a href="#Page_207">207</a> f.<br />
+Eimer, <a href="#Page_292">292</a><br />
+Elementary organs, <a href="#Page_46">46</a> ff.<br />
+<span class="ml1em">processes, <a href="#Page_46">46</a> ff.</span><br />
+Elements of nature, <a href="#Page_9">9</a><br />
+Embryo, <a href="#Page_44">44</a><br />
+<span class="ml1em">frog’s, <a href="#Page_59">59</a>, <a href="#Page_65">65</a>, <a href="#Page_67">67</a></span><br />
+<span class="ml1em">half, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_66">66</a> ff.</span><br />
+<span class="ml1em">whole, <a href="#Page_61">61</a>, <a href="#Page_67">67</a> f.</span><br />
+Endoderm, <a href="#Page_41">41</a>, <a href="#Page_81">81</a><br />
+Entelechy, <a href="#Page_143">143</a> f., <a href="#Page_224">224</a> f., <a href="#Page_295">295</a><br />
+Entwickelungsmechanik, <a href="#Page_57">57</a>, <a href="#Page_70">70</a>, <a href="#Page_78">78</a>, <a href="#Page_241">241</a><br />
+Enumeration, <a href="#Page_297">297</a>, <a href="#Page_300">300</a><br />
+Enzymes, <a href="#Page_164">164</a>, <a href="#Page_203">203</a><br />
+Epigenesis, <a href="#Page_26">26</a>, <a href="#Page_45">45</a>, <a href="#Page_54">54</a>, <a href="#Page_72">72</a>, <a href="#Page_144">144</a>, <a href="#Page_301">301</a><br />
+Equifinality (of restitutions), <a href="#Page_159">159</a> f.<br />
+Equipotential, <a href="#Page_83">83</a><br />
+Eschenhagen, <a href="#Page_195">195</a><br />
+Evolutio, <a href="#Page_26">26</a>, <a href="#Page_45">45</a> f., <a href="#Page_54">54</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_64">64</a>, <a href="#Page_72">72</a>, <a href="#Page_144">144</a>, <a href="#Page_205">205</a>, <a href="#Page_301">301</a><br />
+Evolution, <a href="#Page_8">8</a>, <a href="#Page_21">21</a>, <a href="#Page_46">46</a>, <a href="#Page_250">250</a>, <a href="#Page_301">301</a>, <a href="#Page_305">305</a>, <a href="#Page_311">311</a> ff., <a href="#Page_317">317</a><br />
+Experience, <a href="#Page_7">7</a> f., <a href="#Page_12">12</a>, <a href="#Page_212">212</a><br />
+Experiment, <a href="#Page_51">51</a>, <a href="#Page_56">56</a> f.<br />
+“Explaining,” 51, <a href="#Page_309">309</a><br />
+Explicit potency, <a href="#Page_84">84</a><br />
+<br />
+Fasting, <a href="#Page_199">199</a> f.<br />
+Ferments, <a href="#Page_164">164</a>, <a href="#Page_203">203</a> f.<br />
+Fertilisation, <a href="#Page_32">32</a> ff.<br />
+Fischer, <a href="#Page_278">278</a><br />
+Foges, <a href="#Page_107">107</a><br />
+Form, closed or open, <a href="#Page_49">49</a><br />
+Form, organic, specific, <a href="#Page_16">16</a> ff., <a href="#Page_25">25</a>, <a href="#Page_92">92</a>, <a href="#Page_293">293</a> ff.<br />
+Forma accidentalis, <a href="#Page_293">293</a><br />
+<span class="ml1em">essentialis, <a href="#Page_294">294</a> f.</span><br />
+Formative stimuli, <a href="#Page_102">102</a> ff., <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_133">133</a><br />
+Francé, <a href="#Page_158">158</a>, <a href="#Page_239">239</a><br />
+Frédéricq, <a href="#Page_196">196</a><br />
+Frog, embryo of, <a href="#Page_59">59</a>, <a href="#Page_65">65</a>, <a href="#Page_67">67</a><br />
+Fromm, <a href="#Page_205">205</a><br />
+Function (mathematical), <a href="#Page_80">80</a><br />
+Fungi, metabolism of, <a href="#Page_201">201</a><br />
+<br />
+Gaidukow, <a href="#Page_197">197</a> f.<br />
+Galls, <a href="#Page_101">101</a><br />
+Galton, <a href="#Page_228">228</a>, <a href="#Page_238">238</a><br />
+Gamble and Keeble, <a href="#Page_198">198</a><br />
+Gastrula, <a href="#Page_41">41</a>, <a href="#Page_61">61</a>, <a href="#Page_81">81</a><br />
+Gautier, <a href="#Page_239">239</a><br />
+Geographical distribution, <a href="#Page_251">251</a> f.<br />
+Geometry, solid, <a href="#Page_243">243</a><br />
+Germ-layers, <a href="#Page_41">41</a>, <a href="#Page_44">44</a>, <a href="#Page_61">61</a><br />
+<span class="ml1em">-lineage, <a href="#Page_215">215</a></span><br />
+<span class="ml1em">-plasm, <a href="#Page_52">52</a>, <a href="#Page_215">215</a></span><br />
+Gifford, Lord, <a href="#Page_1">1</a> ff., <a href="#Page_322">322</a><br />
+Godlewski, <a href="#Page_105">105</a>, <a href="#Page_155">155</a>, <a href="#Page_235">235</a><br />
+Goebel, <a href="#Page_116">116</a><br />
+Goethe, <a href="#Page_247">247</a><br />
+Goette, <a href="#Page_48">48</a>, <a href="#Page_56">56</a>, <a href="#Page_214">214</a><br />
+Goltz, <a href="#Page_181">181</a><br />
+Growth, <a href="#Page_30">30</a>, <a href="#Page_93">93</a> f.<br />
+Gruber, <a href="#Page_236">236</a><br />
+<br />
+Haeckel, <a href="#Page_37">37</a>, <a href="#Page_41">41</a><br />
+Half-embryo, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_66">66</a> ff.<br />
+Haller, A. v., <a href="#Page_26">26</a><br />
+Harmony, <a href="#Page_107">107</a> ff., <a href="#Page_117">117</a>, <a href="#Page_295">295</a><br />
+Hausmann, <a href="#Page_206">206</a><br />
+Heat production, <a href="#Page_193">193</a><br />
+Hegel, <a href="#Page_307">307</a>, <a href="#Page_311">311</a> ff.<br />
+Herbst, <a href="#Page_96">96</a> ff., <a href="#Page_102">102</a>, <a href="#Page_104">104</a> ff., <a href="#Page_172">172</a>, <a href="#Page_177">177</a>, <a href="#Page_200">200</a>, <a href="#Page_232">232</a>, <a href="#Page_236">236</a><br />
+Heredity, <a href="#Page_21">21</a>, <a href="#Page_52">52</a><br />
+Hering, <a href="#Page_216">216</a> f.<br />
+Hertwig, O., <a href="#Page_60">60</a>, <a href="#Page_65">65</a><br />
+Hertwig, R., <a href="#Page_32">32</a> f., <a href="#Page_60">60</a>, <a href="#Page_107">107</a><br />
+His, <a href="#Page_56">56</a>, <a href="#Page_93">93</a><br />
+History, <a href="#Page_2">2</a>, <a href="#Page_14">14</a>, <a href="#Page_21">21</a>, <a href="#Page_250">250</a>, <a href="#Page_257">257</a>, <a href="#Page_297">297</a> ff.<br />
+<span class="ml1em">of mankind, <a href="#Page_306">306</a> ff.</span><br />
+Holmes, <a href="#Page_180">180</a><br />
+Hume, <a href="#Page_6">6</a><br />
+Hypertrophy, <a href="#Page_112">112</a>, <a href="#Page_114">114</a><br />
+Hypertypy, <a href="#Page_112">112</a><br />
+<span class="pagenum" title="327"><a name="Page_327" id="Page_327"></a></span><br />
+Idealism, <a href="#Page_5">5</a>, <a href="#Page_7">7</a><br />
+Immunity, <a href="#Page_204">204</a> ff.<br />
+Implicit potency, <a href="#Page_84">84</a><br />
+Improvement (of morphogenesis), <a href="#Page_212">212</a><br />
+Indifferent cells, <a href="#Page_182">182</a><br />
+Inflammation, <a href="#Page_206">206</a><br />
+Inheritance, <a href="#Page_35">35</a>, <a href="#Page_214">214</a> ff.<br />
+<span class="ml1em">of acquired characters, <a href="#Page_217">217</a>, <a href="#Page_275">275</a> ff., <a href="#Page_290">290</a></span><br />
+Irritability, <a href="#Page_190">190</a> ff.<br />
+<br />
+Jacoby, <a href="#Page_207">207</a><br />
+Jaeger, <a href="#Page_214">214</a><br />
+Jennings, <a href="#Page_218">218</a><br />
+<br />
+Kammerer, <a href="#Page_176">176</a>, <a href="#Page_280">280</a><br />
+Kant, <a href="#Page_6">6</a> f.<br />
+Kirchhoff, <a href="#Page_50">50</a><br />
+Klebs, <a href="#Page_96">96</a>, <a href="#Page_170">170</a>, <a href="#Page_180">180</a>, <a href="#Page_238">238</a>, <a href="#Page_276">276</a><br />
+Kölliker, <a href="#Page_292">292</a><br />
+Korshinsky, <a href="#Page_239">239</a><br />
+Krašan, <a href="#Page_221">221</a>, <a href="#Page_251">251</a><br />
+<br />
+Lamarck, <a href="#Page_271">271</a> f., <a href="#Page_291">291</a><br />
+Lamarckism, <a href="#Page_271">271</a> f., <a href="#Page_284">284</a> ff., <a href="#Page_293">293</a> ff., <a href="#Page_304">304</a><br />
+Lamprecht, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Larva, <a href="#Page_41">41</a> f., <a href="#Page_44">44</a><br />
+Law of nature, <a href="#Page_13">13</a>, <a href="#Page_16">16</a><br />
+Leibniz, <a href="#Page_6">6</a><br />
+Lens (of eye), <a href="#Page_105">105</a>, <a href="#Page_221">221</a><br />
+Liebmann, <a href="#Page_256">256</a><br />
+Life, <a href="#Page_9">9</a> f., <a href="#Page_16">16</a>, <a href="#Page_21">21</a><br />
+Lillie, R. S., <a href="#Page_236">236</a><br />
+Limits of regulability, <a href="#Page_212">212</a><br />
+Lithium, <a href="#Page_99">99</a><br />
+“Living,” 9, <a href="#Page_16">16</a><br />
+Localisation, <a href="#Page_101">101</a>, <a href="#Page_103">103</a>, <a href="#Page_118">118</a> ff.<br />
+Locke, <a href="#Page_6">6</a><br />
+Loeb, J., <a href="#Page_32">32</a>, <a href="#Page_102">102</a>, <a href="#Page_164">164</a>, <a href="#Page_179">179</a>, <a href="#Page_196">196</a>, <a href="#Page_236">236</a><br />
+Loeb, L., <a href="#Page_208">208</a><br />
+Lyon, <a href="#Page_87">87</a><br />
+<br />
+MacDougal, <a href="#Page_238">238</a> f., <a href="#Page_276">276</a><br />
+Machine (definition), <a href="#Page_139">139</a><br />
+Machine-theory of life, <a href="#Page_138">138</a> ff., <a href="#Page_187">187</a>, <a href="#Page_210">210</a><br />
+Maillard, <a href="#Page_196">196</a><br />
+Manifoldness, <a href="#Page_25">25</a> f., <a href="#Page_30">30</a>, <a href="#Page_45">45</a><br />
+<span class="ml1em">intensive, <a href="#Page_144">144</a></span><br />
+Materialism, <a href="#Page_283">283</a><br />
+Materials, transport of, <a href="#Page_194">194</a><br />
+Matter, theory of, <a href="#Page_8">8</a><br />
+Maturation, <a href="#Page_31">31</a>, <a href="#Page_87">87</a><br />
+Mayenburg, v., <a href="#Page_195">195</a><br />
+Means, of morphogenesis, <a href="#Page_89">89</a> ff., <a href="#Page_101">101</a>, <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_228">228</a>, <a href="#Page_234">234</a><br />
+Memory, <a href="#Page_216">216</a> f.<br />
+Mendel, <a href="#Page_229">229</a> f.<br />
+Merrifield, <a href="#Page_198">198</a><br />
+Mesenchyme, <a href="#Page_39">39</a>, <a href="#Page_41">41</a>, <a href="#Page_104">104</a>, <a href="#Page_111">111</a>, <a href="#Page_151">151</a> f.<br />
+Metabolic regulations, <a href="#Page_198">198</a> f.<br />
+Metabolism, <a href="#Page_16">16</a>, <a href="#Page_184">184</a><br />
+<span class="ml1em">of fungi, <a href="#Page_201">201</a></span><br />
+Metschnikoff, <a href="#Page_206">206</a><br />
+Micromeres, <a href="#Page_36">36</a>, <a href="#Page_60">60</a><br />
+Miehe, <a href="#Page_116">116</a><br />
+Mill, J. S., <a href="#Page_57">57</a><br />
+<i>Mimosa</i>, <a href="#Page_191">191</a><br />
+Minkiewicz, <a href="#Page_198">198</a><br />
+Modification, <a href="#Page_277">277</a><br />
+Molluscs, <a href="#Page_70">70</a> f., <a href="#Page_86">86</a><br />
+Morgan, T. H., <a href="#Page_32">32</a>, <a href="#Page_66">66</a> f., <a href="#Page_95">95</a>, <a href="#Page_107">107</a>, <a href="#Page_114">114</a> f., <a href="#Page_162">162</a>, <a href="#Page_230">230</a><br />
+Morphaesthesia, <a href="#Page_157">157</a><br />
+Morphogenesis, <a href="#Page_20">20</a>, <a href="#Page_52">52</a>, <a href="#Page_76">76</a>, <a href="#Page_112">112</a>, <a href="#Page_118">118</a> f.<br />
+Morphology, <a href="#Page_12">12</a><br />
+Movements, organic, <a href="#Page_17">17</a><br />
+Mutations, <a href="#Page_237">237</a> f., <a href="#Page_276">276</a>, <a href="#Page_291">291</a><br />
+<br />
+Nägeli, <a href="#Page_266">266</a>, <a href="#Page_292">292</a><br />
+Nathansohn, <a href="#Page_196">196</a><br />
+Natural selection, <a href="#Page_261">261</a> f., <a href="#Page_290">290</a><br />
+Nature, <a href="#Page_5">5</a> ff.<br />
+Němec, <a href="#Page_116">116</a><br />
+Newport, <a href="#Page_57">57</a><br />
+Newt (regeneration of), <a href="#Page_155">155</a>, <a href="#Page_221">221</a> f.<br />
+Noll, <a href="#Page_146">146</a>, <a href="#Page_157">157</a> f.<br />
+Nomothetic, <a href="#Page_14">14</a> f.<br />
+Normal, <a href="#Page_78">78</a><br />
+Nuclear division, <a href="#Page_28">28</a> f., <a href="#Page_62">62</a>, <a href="#Page_64">64</a> f., <a href="#Page_72">72</a>, <a href="#Page_235">235</a><br />
+Nucleus, <a href="#Page_28">28</a>, <a href="#Page_35">35</a><br />
+<span class="ml1em">rôle of nucleus in inheritance, <a href="#Page_233">233</a> f.</span><br />
+<br />
+Organ-forming substances, <a href="#Page_117">117</a><br />
+<i>Oscillariae</i>, <a href="#Page_197">197</a><br />
+Osmotic pressure, <a href="#Page_93">93</a>, <a href="#Page_187">187</a>, <a href="#Page_194">194</a> f.<br />
+Overton, <a href="#Page_196">196</a> f.<br />
+Oxidation, rôle of, <a href="#Page_198">198</a> f.<br />
+<br />
+Palaeontology, <a href="#Page_252">252</a><br />
+Parallelism (psycho-physical), <a href="#Page_146">146</a><br />
+Parthenogenesis, <a href="#Page_32">32</a><br />
+Pauly, <a href="#Page_146">146</a>, <a href="#Page_217">217</a>, <a href="#Page_273">273</a> f.<br />
+Pawlow, <a href="#Page_204">204</a>, <a href="#Page_210">210</a>, <a href="#Page_212">212</a><br />
+Pearl, R., <a href="#Page_212">212</a><br />
+Pfeffer, <a href="#Page_195">195</a>, <a href="#Page_201">201</a><br />
+Phagocytosis, <a href="#Page_206">206</a><br />
+Phenomenon, <a href="#Page_5">5</a> f.<br />
+Philosophy, natural, <a href="#Page_4">4</a><br />
+<span class="ml1em">of nature, <a href="#Page_4">4</a>, <a href="#Page_7">7</a>, <a href="#Page_9">9</a></span><br />
+<span class="ml1em">of the organism, <a href="#Page_9">9</a>, <a href="#Page_15">15</a></span><br />
+Phylogeny, <a href="#Page_255">255</a>, <a href="#Page_291">291</a>, <a href="#Page_297">297</a>, <a href="#Page_304">304</a> ff.<br />
+<span class="pagenum" title="328"><a name="Page_328" id="Page_328"></a></span><br />
+Physiology, <a href="#Page_12">12</a><br />
+<span class="ml1em">of development (morphogenesis), <a href="#Page_20">20</a></span><br />
+<i>Planaria</i>, <a href="#Page_130">130</a>, <a href="#Page_155">155</a>, <a href="#Page_162">162</a> f., <a href="#Page_200">200</a><br />
+Plants, <a href="#Page_48">48</a> f.<br />
+Plato, <a href="#Page_2">2</a><br />
+Pluteus, <a href="#Page_42">42</a><br />
+Poisons, <a href="#Page_205">205</a> ff.<br />
+Pole, <a href="#Page_36">36</a><br />
+Polarity, <a href="#Page_106">106</a><br />
+Potencies, complex, <a href="#Page_112">112</a>, <a href="#Page_120">120</a><br />
+<span class="ml1em">explicit, <a href="#Page_84">84</a></span><br />
+<span class="ml1em">implicit, <a href="#Page_84">84</a></span><br />
+<span class="ml1em">primary, <a href="#Page_84">84</a>, <a href="#Page_111">111</a></span><br />
+<span class="ml1em">prospective, <a href="#Page_77">77</a> ff., <a href="#Page_83">83</a>, <a href="#Page_89">89</a>, <a href="#Page_118">118</a>, <a href="#Page_125">125</a>, <a href="#Page_241">241</a></span><br />
+<span class="ml1em">secondary, <a href="#Page_84">84</a>, <a href="#Page_110">110</a></span><br />
+Poulton, <a href="#Page_198">198</a><br />
+Precipitin, <a href="#Page_207">207</a> f.<br />
+Pressure experiments, <a href="#Page_63">63</a>, <a href="#Page_141">141</a><br />
+Primary potency, <a href="#Page_84">84</a>, <a href="#Page_111">111</a><br />
+<span class="ml1em">purposefulness, <a href="#Page_146">146</a>, <a href="#Page_287">287</a></span><br />
+<span class="ml1em">regulation, <a href="#Page_85">85</a>, <a href="#Page_174">174</a>, <a href="#Page_188">188</a></span><br />
+Progress, <a href="#Page_305">305</a><br />
+Pronuclei, <a href="#Page_55">55</a><br />
+Prospective potency, <a href="#Page_77">77</a> ff., <a href="#Page_83">83</a>, <a href="#Page_89">89</a>, <a href="#Page_118">118</a>, <a href="#Page_125">125</a>, <a href="#Page_241">241</a><br />
+<span class="ml1em">value, <a href="#Page_77">77</a> f., <a href="#Page_80">80</a>, <a href="#Page_122">122</a></span><br />
+Protista (Protozoa), <a href="#Page_27">27</a>, <a href="#Page_130">130</a>, <a href="#Page_236">236</a><br />
+Protoplasm, <a href="#Page_28">28</a>, <a href="#Page_30">30</a><br />
+<span class="ml1em">morphogenetic rôle of, <a href="#Page_67">67</a></span><br />
+Przibram, <a href="#Page_112">112</a>, <a href="#Page_248">248</a><br />
+<br />
+Rádl, <a href="#Page_247">247</a><br />
+Rauber, <a href="#Page_235">235</a><br />
+Reaction, answering, <a href="#Page_181">181</a><br />
+Reciprocity of harmony, <a href="#Page_156">156</a> f.<br />
+Re-differentiation, <a href="#Page_75">75</a>, <a href="#Page_111">111</a>, <a href="#Page_163">163</a><br />
+Regeneration, <a href="#Page_55">55</a>, <a href="#Page_74">74</a>, <a href="#Page_105">105</a>, <a href="#Page_111">111</a>, <a href="#Page_221">221</a><br />
+<span class="ml1em">super-, <a href="#Page_115">115</a> f.</span><br />
+Regulation, <a href="#Page_68">68</a>, <a href="#Page_73">73</a>, <a href="#Page_85">85</a>, <a href="#Page_111">111</a>, <a href="#Page_165">165</a><br />
+<span class="ml1em">defined, <a href="#Page_166">166</a></span><br />
+<span class="ml1em">metabolic, <a href="#Page_198">198</a> f.</span><br />
+<span class="ml1em">secondary, <a href="#Page_85">85</a>, <a href="#Page_165">165</a>, <a href="#Page_188">188</a></span><br />
+Reinke, <a href="#Page_146">146</a><br />
+Restitution, <a href="#Page_21">21</a>, <a href="#Page_74">74</a>, <a href="#Page_110">110</a>, <a href="#Page_112">112</a> ff.<br />
+<span class="ml1em">defined, <a href="#Page_166">166</a></span><br />
+<span class="ml1em">and Darwinism, <a href="#Page_267">267</a></span><br />
+<span class="ml1em">and Lamarckism, <a href="#Page_286">286</a></span><br />
+<span class="ml1em">of second order, <a href="#Page_158">158</a></span><br />
+Retina, <a href="#Page_191">191</a><br />
+Retro-differentiation, <a href="#Page_163">163</a> f.<br />
+Rhumbler, <a href="#Page_93">93</a><br />
+Ribbert, <a href="#Page_114">114</a><br />
+Rickert, <a href="#Page_315">315</a> ff.<br />
+Roux, <a href="#Page_26">26</a>, <a href="#Page_48">48</a>, <a href="#Page_55">55</a> ff., <a href="#Page_66">66</a> f., <a href="#Page_76">76</a>, <a href="#Page_89">89</a>, <a href="#Page_92">92</a> f., <a href="#Page_108">108</a>, <a href="#Page_161">161</a>, <a href="#Page_176">176</a> f., <a href="#Page_241">241</a><br />
+Rubner, <a href="#Page_193">193</a><br />
+<br />
+Sachs, <a href="#Page_117">117</a><br />
+Sadebeck, <a href="#Page_279">279</a><br />
+<i>Salamandra</i>, <a href="#Page_175">175</a>, <a href="#Page_281">281</a><br />
+Schneider, <a href="#Page_146">146</a><br />
+Schultz, E., <a href="#Page_200">200</a><br />
+Schultze, O., <a href="#Page_67">67</a><br />
+Schwendener, <a href="#Page_177">177</a><br />
+Science, <a href="#Page_14">14</a>, <a href="#Page_297">297</a><br />
+<span class="ml1em">natural, <a href="#Page_1">1</a> ff.</span><br />
+<span class="ml1em">rational, <a href="#Page_12">12</a></span><br />
+Sea-urchin, <i>see</i> <a href="#Echinus">Echinus</a><br />
+Secondary potency, <a href="#Page_84">84</a>, <a href="#Page_110">110</a><br />
+<span class="ml1em">regulation, <a href="#Page_85">85</a>, <a href="#Page_165">165</a>, <a href="#Page_188">188</a></span><br />
+Secretion, internal, <a href="#Page_116">116</a>, <a href="#Page_200">200</a><br />
+Segmentation, <a href="#Page_35">35</a><br />
+Selective qualities (of tissues), <a href="#Page_186">186</a><br />
+Self-differentiation, <a href="#Page_108">108</a><br />
+Semon, <a href="#Page_216">216</a> f.<br />
+Sex, <a href="#Page_107">107</a><br />
+Single, the, <a href="#Page_315">315</a> ff.<br />
+Skeleton, <a href="#Page_40">40</a> ff., <a href="#Page_44">44</a>, <a href="#Page_47">47</a>, <a href="#Page_92">92</a><br />
+Spemann, <a href="#Page_105">105</a><br />
+Spermatozoon (spermia), <a href="#Page_32">32</a> ff.<br />
+Splitting (of hybrids), <a href="#Page_229">229</a> f.<br />
+Stahl, <a href="#Page_197">197</a><br />
+Standfuss, <a href="#Page_278">278</a><br />
+Starfish, <a href="#Page_44">44</a>, <a href="#Page_81">81</a>, <a href="#Page_122">122</a><br />
+Starling, E., <a href="#Page_116">116</a>, <a href="#Page_204">204</a>, <a href="#Page_212">212</a><br />
+<i>Stentor</i>, <a href="#Page_131">131</a><br />
+Stimuli, directive, <a href="#Page_102">102</a> ff.<br />
+<span class="ml1em">formative, <a href="#Page_102">102</a> ff., <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_133">133</a></span><br />
+<span class="ml1em">of restitutions, <a href="#Page_113">113</a> f.</span><br />
+Structure of protoplasm, <a href="#Page_66">66</a>, <a href="#Page_69">69</a>, <a href="#Page_72">72</a> f. 85, <a href="#Page_88">88</a><br />
+Substance, living, <a href="#Page_17">17</a><br />
+Sumner, <a href="#Page_196">196</a><br />
+Super-regeneration, <a href="#Page_115">115</a> f.<br />
+Surface-tension, <a href="#Page_91">91</a><br />
+Sutton, <a href="#Page_230">230</a><br />
+Symmetry, <a href="#Page_39">39</a>, <a href="#Page_68">68</a>, <a href="#Page_70">70</a>, <a href="#Page_72">72</a>, <a href="#Page_89">89</a>, <a href="#Page_98">98</a><br />
+System, combined types of, <a href="#Page_153">153</a> ff.<br />
+<span class="ml1em">complex, <a href="#Page_219">219</a> f.</span><br />
+<span class="ml1em">complex-harmonious, <a href="#Page_155">155</a></span><br />
+<span class="ml1em">equipotential, <a href="#Page_120">120</a></span><br />
+<span class="ml1em">harmonious-equipotential, <a href="#Page_121">121</a> ff., <a href="#Page_151">151</a> f.</span><br />
+<span class="ml1em">mixed-equipotential, <a href="#Page_154">154</a></span><br />
+<span class="ml1em">morphogenetic, <a href="#Page_119">119</a> f., <a href="#Page_163">163</a>, <a href="#Page_241">241</a></span><br />
+Systematics, <a href="#Page_14">14</a> ff., <a href="#Page_21">21</a>, <a href="#Page_243">243</a> f., <a href="#Page_253">253</a>, <a href="#Page_264">264</a>, <a href="#Page_293">293</a>, <a href="#Page_296">296</a><br />
+<br />
+Taine, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Theology, natural, <a href="#Page_1">1</a> ff.<br />
+Thomson, J. A., <a href="#Page_16">16</a><br />
+Thymus, <a href="#Page_204">204</a><br />
+<span class="pagenum" title="329"><a name="Page_329" id="Page_329"></a></span><br />
+Thyroid, <a href="#Page_204">204</a><br />
+Tissue, <a href="#Page_38">38</a><br />
+Toxins, <a href="#Page_207">207</a> f.<br />
+Transformism, <a href="#Page_251">251</a><br />
+Truth, <a href="#Page_7">7</a><br />
+Tschermak, <a href="#Page_228">228</a><br />
+<i>Tubularia</i>, <a href="#Page_126">126</a> ff., <a href="#Page_133">133</a>, <a href="#Page_158">158</a> ff.<br />
+Type, <a href="#Page_48">48</a>, <a href="#Page_247">247</a> f., <a href="#Page_282">282</a>, <a href="#Page_291">291</a><br />
+<br />
+“Understanding” (historically), <a href="#Page_302">302</a><br />
+Universality, postulate of, <a href="#Page_148">148</a> f.<br />
+Universe, <a href="#Page_5">5</a><br />
+Univocality, principle of, <a href="#Page_161">161</a><br />
+<br />
+“Values,” 317 ff.<br />
+<span class="ml1em">prospective, <a href="#Page_77">77</a> f., <a href="#Page_80">80</a>, <a href="#Page_122">122</a></span><br />
+Variation, <a href="#Page_218">218</a>, <a href="#Page_237">237</a> f., <a href="#Page_276">276</a><br />
+Variation, fluctuating, contingent, <a href="#Page_264">264</a> f., <a href="#Page_273">273</a> f., <a href="#Page_282">282</a>, <a href="#Page_290">290</a><br />
+Vernon, <a href="#Page_232">232</a>, <a href="#Page_238">238</a><br />
+Vitalism, <a href="#Page_143">143</a>, <a href="#Page_145">145</a> f., <a href="#Page_210">210</a> f., <a href="#Page_224">224</a> f., <a href="#Page_234">234</a>, <a href="#Page_240">240</a> f., <a href="#Page_272">272</a>, <a href="#Page_277">277</a><br />
+Vöchting, <a href="#Page_174">174</a>, <a href="#Page_179">179</a> f., <a href="#Page_182">182</a>, <a href="#Page_221">221</a><br />
+Volition, acts of, <a href="#Page_274">274</a><br />
+Vries, de, <a href="#Page_228">228</a>, <a href="#Page_238">238</a> f.<br />
+<br />
+Wallace, <a href="#Page_292">292</a><br />
+Ward, J., <a href="#Page_8">8</a>, <a href="#Page_143">143</a><br />
+Weber, law of, <a href="#Page_191">191</a><br />
+Weinland, <a href="#Page_202">202</a><br />
+Weismann, <a href="#Page_33">33</a>, <a href="#Page_52">52</a> ff., <a href="#Page_58">58</a> f., <a href="#Page_72">72</a>, <a href="#Page_74">74</a> f., <a href="#Page_103">103</a>, <a href="#Page_111">111</a>, <a href="#Page_138">138</a>, <a href="#Page_214">214</a> f., <a href="#Page_237">237</a>, <a href="#Page_277">277</a> f.<br />
+Weldon, <a href="#Page_238">238</a><br />
+Whole, the, <a href="#Page_28">28</a>, <a href="#Page_80">80</a>, <a href="#Page_117">117</a><br />
+<span class="ml1em">-embryo, <a href="#Page_61">61</a>, <a href="#Page_67">67</a> f.</span><br />
+Wigand, <a href="#Page_255">255</a>, <a href="#Page_266">266</a>, <a href="#Page_292">292</a><br />
+Wilson, E. B., <a href="#Page_27">27</a>, <a href="#Page_65">65</a>, <a href="#Page_70">70</a> f., <a href="#Page_86">86</a> f., <a href="#Page_107">107</a><br />
+Windelband, <a href="#Page_13">13</a> f.<br />
+Winkler, <a href="#Page_116">116</a>, <a href="#Page_221">221</a><br />
+Winterstein, <a href="#Page_199">199</a><br />
+Wolff, C. F., <a href="#Page_26">26</a><br />
+Wolff, G., <a href="#Page_105">105</a>, <a href="#Page_146">146</a>, <a href="#Page_255">255</a>, <a href="#Page_266">266</a>, <a href="#Page_287">287</a> f.<br />
+Wolff, J., <a href="#Page_177">177</a><br />
+<br />
+Yung, <a href="#Page_177">177</a><br />
+<br />
+Zeleny, <a href="#Page_112">112</a>, <a href="#Page_115">115</a>, <a href="#Page_212">212</a><br />
+Zur Strassen, <a href="#Page_93">93</a>
+</p>
+
+
+<p class="tac fs65"><br /><br /><br /><br />THE END<br /><br /><br /><br />
+
+<i>Printed by</i> <span class="smcap">R. &amp; R. Clark, Limited,</span> <i>Edinburgh</i>.</p>
+
+<p><span class="pagenum hide" title="330"><a name="Page_330" id="Page_330"></a></span><br /><span class="pagenum hide" title="331"><a name="Page_331" id="Page_331"></a></span></p>
+
+
+
+<hr class="chap" />
+
+<h2>HEREDITY AND SELECTION<br />
+IN SOCIOLOGY</h2>
+
+
+<p class="tac fs65 pt12b02em">BY</p>
+
+<p class="tac fs120">G. CHATTERTON HILL</p>
+
+<p class="tac">Demy 8vo, Cloth, 600 pages.</p>
+
+<p class="tac">Price <b><span class="fs120">12s. 6d.</span></b> net.</p>
+
+<p class="tac"><i>Post Free, Price</i> <b><span class="fs120">12s. 11d.</span></b></p>
+
+<p class="tac pt12b02em">SOME PRESS OPINIONS</p>
+
+<div class="fs85 mlr10em">
+<p>“A most praiseworthy and suggestive work&mdash;should certainly be
+studied by every serious thinker.”&mdash;<cite>Morning Post.</cite></p>
+
+<p>“Mr. Hill is decidedly doctrinaire, but his book is packed with
+scientific and sociological facts, and it gives the reader healthy
+intellectual exercise.”&mdash;<cite>Christian World.</cite></p>
+
+<p>“Shows wide reading, is written in a forcible and clear style, and
+contains much that is interesting, fresh, and acute.”&mdash;<cite>Aberdeen
+Free Press.</cite></p>
+
+<p>“It is a book of equal calibre with Mr. Kidd’s and goes even
+deeper than that remarkable production into the springs of life and
+conduct.”&mdash;<cite>Methodist Recorder.</cite></p>
+
+<p>“This most suggestive and valuable work, which contains abundant
+sociological data.”&mdash;<cite>Aberdeen Journal.</cite></p>
+
+<p>“Mr. George Chatterton Hill has written a volume of surpassing
+interest not alone to scientific but to theological students.”&mdash;<cite>Catholic
+Times.</cite></p>
+
+<hr />
+<p class="tac"><span class="smcap">Published by</span> A. &amp; C. BLACK, SOHO SQUARE, LONDON, W.<br /><br /><br /></p></div>
+
+<p><span class="pagenum hide" title="332"><a name="Page_332" id="Page_332"></a></span></p>
+
+
+
+<hr class="chap" />
+
+<h2>RUDOLF EUCKEN’S<br />
+PHILOSOPHY OF LIFE</h2>
+
+<p class="tac fs65 pt12b02em">BY</p>
+
+<p class="tac fs120">W. R. BOYCE GIBSON</p>
+
+<p class="tac fs65">LECTURER IN PHILOSOPHY IN THE UNIVERSITY OF LONDON</p>
+
+<p class="tac fs85 pt12b02em">SECOND EDITION</p>
+
+<p class="tac">Crown 8vo, Cloth, with Frontispiece Portrait of Rudolf Eucken.</p>
+
+<p class="tac">Price <b><span class="fs120">3s. 6d.</span></b> net.</p>
+
+<p class="tac"><i>Post Free, Price</i> <b><span class="fs120">3s. 10d.</span></b></p>
+
+<p class="tac pt12b02em">SOME PRESS OPINIONS</p>
+
+<div class="fs85 mlr10em">
+<p>“Mr. Gibson has given us in small compass a lucid exposition of the
+philosophical system of Eucken, who is Professor of Philosophy in Jena.&nbsp;.&nbsp;.&nbsp;.
+This is a most suggestive and stimulating book. In a very real
+sense it has brought philosophy down to earth and is deserving of
+serious study.”&mdash;<cite>Aberdeen Free Press.</cite></p>
+
+<p>“To it the interested reader will turn with expectation, and his
+expectation is likely to be more than realised. For Dr. Boyce Gibson
+is himself a scholar, as well as an enthusiastic lover of this great
+scholar.”&mdash;<cite>Expository Times.</cite></p>
+
+<p>“No reader should fail to find pleasure in a book so full of fresh
+and stimulating thought, expressed with great felicity of language.”&mdash;<cite>The
+Scottish Review.</cite></p>
+
+<p>“It is done with just the proper combination of sympathy and
+criticism.”&mdash;<cite>British Weekly.</cite></p>
+
+<p>“This little book on Eucken’s Philosophy is of quite exceptional
+interest and importance.”&mdash;<cite>The Inquirer.</cite></p>
+
+<p>“Professor Boyce Gibson&nbsp;.&nbsp;.&nbsp;. has performed a real service in
+promoting the acquaintance of English, and American students with a
+thinker whose distinctive views give him a special claim to their
+attention.&nbsp;.&nbsp;.&nbsp;. Professor Gibson has achieved a notable success,
+writing briefly, lucidly, and sympathetically.”&mdash;<cite>The New Age.</cite></p>
+
+<hr />
+<p class="tac"><span class="smcap">Published by</span> A. &amp; C. BLACK, SOHO SQUARE, LONDON, W.<br /><br /><br /></p></div>
+
+<hr class="chap" />
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">1</span></a> Windelband (<cite lang="de" xml:lang="de">Geschichte und Naturwissenschaft</cite>, 3 Auflage, 1904) gives
+the name “nomothetic” to the whole of our “science” and calls the method
+of history “idiographic.” We thought it better to establish three fundamental
+types of all possible branches of knowledge.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">2</span></a> See J. Arth. Thomson, <cite>The Science of Life</cite>, London, 1899.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">3</span></a> E. B. Wilson, <cite>The Cell in Development and Inheritance</cite>, New York,
+Macmillan, 1896.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">4</span></a> <cite>Amer. Journ. Physiol.</cite> vols. iii. and iv. 1900.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">5</span></a> According to Delage (<cite>Arch. Zool. exp.</cite>, 3 sér. 10, 1902), it is indifferent
+for the realisation of artificial parthenogenesis, whether but one, or both, or
+neither of the “polar bodies” has been formed. But the egg must be in the
+first stages of maturation to the extent that the “nuclear membrane” must
+be already dissolved.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">6</span></a> The older theories, attributing to fertilisation (or to “conjugation,” <i>i.e.</i>
+its equivalent in Protozoa), some sort of “renovation” or “rejuvenescence”
+of the race, have been almost completely given up. (See Calkins, <cite lang="de" xml:lang="de">Arch. für
+Entwickelungsmechanik</cite>, xv. 1902). R. Hertwig recently has advocated the
+view, that abnormal relations between the amounts of nuclear and of protoplasmatic
+material are rectified in some way by those processes. Teleologically,
+sexual reproduction has been considered as a means of variability (Weismann),
+but also as a means of preserving the type!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">7</span></a> The phrase “<i lang="la" xml:lang="la">ceteris paribus</i>” has to be added of course, as the duration
+of each single elementary morphogenetic process is liable to vary with the
+temperature and many other conditions of the medium.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">8</span></a> We shall not avoid in these lectures the word “explain”&mdash;so much out of
+fashion nowadays. To “explain” means to subsume under known concepts,
+or rules, or laws, or principles, whether the laws or concepts themselves be
+“explained” or not. Explaining, therefore, is always relative: what is
+elemental, of course, is only to be described, or rather to be stated.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">9</span></a> <cite lang="de" xml:lang="de">Das Keimplasma</cite>, Jena, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">10</span></a> <cite lang="de" xml:lang="de">Die Bedeutung der Kernteilungsfiguren</cite>, Leipzig, 1883.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">11</span></a> <cite lang="de" xml:lang="de">Unsere Körperform</cite>, Leipzig, 1875.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">12</span></a> <cite lang="de" xml:lang="de">Die Entwickelungsgeschichte der Unke</cite>, Leipzig, 1875.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">13</span></a> <cite lang="de" xml:lang="de">Gesammelte Abhandlungen</cite>, Leipzig, 1895. Most important theoretical
+papers:&mdash;<cite lang="de" xml:lang="de">Zeitschr. Biolog.</cite> 21, 1885; <cite lang="de" xml:lang="de">Die Entwickelungsmechanik der Organismen</cite>,
+Wien, 1890; <cite lang="de" xml:lang="de">Vorträge und Aufsätze über Entwickelungsmechanik</cite>,
+Heft i., Leipzig, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">14</span></a> <i>Virchow’s Archiv.</i> 114, 1888.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">15</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 53, 1891.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">16</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 55, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">17</span></a> In the pressure experiments I had altered the relative position of the
+nuclei <i lang="la" xml:lang="la">in origine</i>. In later years I succeeded in disturbing the arrangement
+of the fully formed cells of the eight-cell stage, and in getting normal larvæ
+in spite of that in many cases. But as this series of experiments is not free
+from certain complications&mdash;which in part will be understood later on (see
+page <a href="#Page_73">73</a>)&mdash;it must suffice here to have mentioned them. (For further information
+see my paper in <cite lang="de" xml:lang="de">Archiv. f. Entwickelungsmechanik</cite>, xiv., 1902, page 500.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">18</span></a> <i>Mitteil. Neapel. 11, 1893.</i></p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">19</span></a> But the elementary magnets would have to be bilateral!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">20</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 2, 1895.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">21</span></a> <cite lang="de" xml:lang="de">Anat. Anz.</cite> 10, 1895.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">22</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 3, 1896.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">23</span></a> It deserves notice in this connection, that in some cases the protoplasm
+of parts of a germ has been found to be more regulable in the earliest stages,
+when it is very fluid, than later, when it is more stiff.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">24</span></a> Compare my <cite lang="de" xml:lang="de">Analytische Theorie der organischen Entwickelung</cite>, Leipzig,
+1894, and my reviews in <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>,
+vols. viii. xi. xiv., 1899–1905. A shorter review is given in
+<cite lang="de" xml:lang="de">Ergebnisse der Physiologie</cite>, vol. v., 1906. The full literature will be found
+in these reviews.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">25</span></a> If the plane of section passes near the equator of the germ, two whole
+larvae may be formed also, but in the majority of cases the “animal” half
+does not go beyond the blastula. The specific features of the organisation
+of the protoplasm come into account here. See also page <a href="#Page_65">65</a>, note <a href="#Footnote_17_17">17</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">26</span></a> A change of the position of the cell is of course effected by each variation
+of the direction of the cut, which is purely a matter of chance.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">27</span></a> The reader will remember (see page <a href="#Page_65">65</a>, note <a href="#Footnote_17_17">17</a>), that even the germ
+of Echinus is not quite equipotential along its main axis, but it is equipotential
+in the strictest sense around this axis. The germs of certain
+medusae seem to be equipotential in every respect, even in their cleavage
+stages.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_28_28" id="Footnote_28_28"></a><a href="#FNanchor_28_28"><span class="label">28</span></a> <cite>Journ. Exp. Zool.</cite> 1, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_29_29" id="Footnote_29_29"></a><a href="#FNanchor_29_29"><span class="label">29</span></a> Great caution must be taken in attributing any specific morphogenetic
+part to differently coloured or constructed materials, which may be observed
+in the egg-protoplasm in certain cases. They may play such a part, but in
+other cases they certainly do not (see Lyon, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 23, 1907).
+The final decision always depends on experiment.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_30_30" id="Footnote_30_30"></a><a href="#FNanchor_30_30"><span class="label">30</span></a> It seems that these physical conditions also&mdash;besides the real specifications
+in the organisation of the egg&mdash;may be different before and after
+maturation or (in other cases) fertilisation. (See Driesch, <cite lang="de" xml:lang="de">Archiv f. Entwickelungsmechanik</cite>,
+7, p. 98; and Brachet, <i lang="la" xml:lang="la">ibid.</i> 22, p. 325.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_31_31" id="Footnote_31_31"></a><a href="#FNanchor_31_31"><span class="label">31</span></a> <cite lang="de" xml:lang="de">Studien über Protoplasmamechanik</cite>, Leipzig, 1886.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_32_32" id="Footnote_32_32"></a><a href="#FNanchor_32_32"><span class="label">32</span></a> <cite lang="de" xml:lang="de">Unters. üb. mikroskopische Schäume und das Protoplasma</cite>, Leipzig, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_33_33" id="Footnote_33_33"></a><a href="#FNanchor_33_33"><span class="label">33</span></a> <cite lang="de" xml:lang="de">Jena. Zeitschr.</cite> 26, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_34_34" id="Footnote_34_34"></a><a href="#FNanchor_34_34"><span class="label">34</span></a> According to Zur Strassen’s results the early embryology of <i class="biological-name">Ascaris</i>
+proceeds almost exclusively by cellular surface-changes: the most typical
+morphogenetic processes are carried out by the aid of this “means.” As a
+whole, the embryology of <i class="biological-name">Ascaris</i> stands quite apart and presents a great
+number of unsolved problems; unfortunately, the germ of this form has not
+been accessible to experiment hitherto.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_35_35" id="Footnote_35_35"></a><a href="#FNanchor_35_35"><span class="label">35</span></a> Rhumbler has recently published a general survey of all attempts to
+“explain” life, and morphogenesis in particular, in a physico-chemical way
+(“Aus dem Lückengebiet zwischen organismischer und anorganismischer
+Natur,” <i>Ergeb. Anat. u. Entw.-gesch.</i> 15, 1906). This <em>very pessimistic</em> survey
+is the more valuable as it is written by a convinced “mechanist.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_36_36" id="Footnote_36_36"></a><a href="#FNanchor_36_36"><span class="label">36</span></a> Compare the analytical discussions of Klebs, to whom we owe a great
+series of important discoveries in the field of morphogenetic “means” in
+botany. (<cite lang="de" xml:lang="de">Willkürliche Entwickelungsänderungen bei Pflanzen</cite>, Jena, 1903;
+see also <cite lang="de" xml:lang="de">Biol. Centralblatt</cite>, vol. xxiv., 1904, and my reply to Klebs, <i lang="la" xml:lang="la">ibid.</i> 23, 1903.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_37_37" id="Footnote_37_37"></a><a href="#FNanchor_37_37"><span class="label">37</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 17, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_38_38" id="Footnote_38_38"></a><a href="#FNanchor_38_38"><span class="label">38</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 55, 1902; and <cite lang="de" xml:lang="de">Mitt. Neapel.</cite> 11, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_39_39" id="Footnote_39_39"></a><a href="#FNanchor_39_39"><span class="label">39</span></a> In certain cases part of the specific feature of the process in question may
+also depend on the “cause” which is localising it, <i>e.g.</i> in the galls of plants.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_40_40" id="Footnote_40_40"></a><a href="#FNanchor_40_40"><span class="label">40</span></a> Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale
+Auffassung von Vorgängen in der tierischen Ontogenese” (<cite lang="de" xml:lang="de">Biol. Centralblatt</cite>,
+vols. xiv., 1894, and xv., 1895); <cite lang="de" xml:lang="de">Formative Reize in der tierischen Ontogenese</cite>,
+Leipzig, 1901. These important papers must be studied by every one who
+wishes to become familiar with the subject. The present state of science is
+reviewed in my articles in the <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>,
+vols. xi. and xiv., 1902 and 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_41_41" id="Footnote_41_41"></a><a href="#FNanchor_41_41"><span class="label">41</span></a> Compare the important papers by J. Loeb, <cite lang="de" xml:lang="de">Untersuchungen zur
+physiologischen Morphologie der Tiere</cite>, Würzburg, 1891–2.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_42_42" id="Footnote_42_42"></a><a href="#FNanchor_42_42"><span class="label">42</span></a> I use the word “primordia” for the German “Anlage”; it is better than the
+word “rudiment,” as the latter may also serve to signify the very last stage
+of a certain formation that is disappearing (phylogenetically).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_43_43" id="Footnote_43_43"></a><a href="#FNanchor_43_43"><span class="label">43</span></a> A full analysis of the subject would not only have to deal with formative
+stimuli as inaugurating morphogenetic processes, but also with those stimuli
+which terminate or stop the single acts of morphogenesis. But little is
+actually known about this topic, and therefore the reader must refer to my
+other publications. I will only say here, that the end of each single morphogenetic
+act may either be determined at the very beginning or occur as an
+actual stopping of a process which otherwise would go on for ever and ever;
+in the first case some terminating factors are included in the very nature of
+the morphogenetic act itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_44_44" id="Footnote_44_44"></a><a href="#FNanchor_44_44"><span class="label">44</span></a> A full account of the present state of the subject will be found in
+Morgan’s <cite>Experimental Zoology</cite>, New York, 1907.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_45_45" id="Footnote_45_45"></a><a href="#FNanchor_45_45"><span class="label">45</span></a> But there certainly exist many formative relations between the real
+sexual organs and the so-called secondary sexual characters. Herbst has
+given a full analytical discussion of all that is known on this subject; but
+the facts are much more complicated than is generally supposed, and do not
+lend themselves therefore to short description. See also Foges, <i>Pflüger’s Arch.</i>
+93, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_46_46" id="Footnote_46_46"></a><a href="#FNanchor_46_46"><span class="label">46</span></a> It seems that in some cases (<i class="biological-name">Dinophilus</i>, certain Arthropods) the sexual
+products are invariably determined as “arrenogennetic” or as “thelygennetic”
+(Wilson, <cite>Journ. Exp. Zool.</cite> ii. and iii. 1905–6), whilst in others
+(Amphibia) the state of maturation or “super”-maturation determines the
+sex of the future organism (R. Hertwig, <cite lang="de" xml:lang="de">Verh. D. Zool. Ges.</cite> 1905–7).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_47_47" id="Footnote_47_47"></a><a href="#FNanchor_47_47"><span class="label">47</span></a> Driesch, <cite lang="de" xml:lang="de">Die organischen Regulationen</cite>, Leipzig, 1901; Morgan, <cite>Regeneration</cite>,
+New York, 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_48_48" id="Footnote_48_48"></a><a href="#FNanchor_48_48"><span class="label">48</span></a> But real compensatory differentiation occurs in the cases of so-called
+“hypertypy” as first discovered by Przibram and afterwards studied by
+Zeleny: here the two organs of a pair show a different degree of differentiation.
+Whenever the more specialised organ is removed the less developed
+one assumes its form. Similar cases, which might simply be called “compensatory
+heterotypy,” are known in plants, though only relating to the
+actual fate of undifferentiated “Anlagen” in these organisms. A leaf may
+be formed out of the Anlage of a scale, if all the leaves are cut off, and so on.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_49_49" id="Footnote_49_49"></a><a href="#FNanchor_49_49"><span class="label">49</span></a> For a fuller analysis compare my opening address delivered before the
+section of “Experimental Zoology” at the Seventh Zoological Congress,
+Boston, 1907: “The Stimuli of Restitutions” (see Proceedings of that
+Congress).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_50_50" id="Footnote_50_50"></a><a href="#FNanchor_50_50"><span class="label">50</span></a> The problem of the stimulus of a secondary restitution as a whole must
+not be confused with the very different question, what the single “formative
+stimuli” concerned in the performance of a certain restitutive act may be.
+With regard to restitution as a <em>whole</em> these single “formative stimuli”
+might properly be said to belong to its “internal means”&mdash;in the widest
+sense of the word.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_51_51" id="Footnote_51_51"></a><a href="#FNanchor_51_51"><span class="label">51</span></a> T. H. Morgan is very right in stating that, in regeneration, the
+“obstacle” itself is newly formed by the mere process of healing, previous
+to all restitution, and that true restitution happens all the same.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_52_52" id="Footnote_52_52"></a><a href="#FNanchor_52_52"><span class="label">52</span></a> I merely mention here the still “simpler” one&mdash;applicable of course
+to regeneration proper exclusively&mdash;that for the simple reason of being
+“wounded,” <i>i.e.</i> being a surface open to the medium, the “wound” brings
+forth all that is necessary to complete the organism.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_53_53" id="Footnote_53_53"></a><a href="#FNanchor_53_53"><span class="label">53</span></a> That compensatory hypertrophy cannot be due to “functional adaptation”&mdash;to
+be analysed later on&mdash;was proved by an experiment of Ribbert’s. Compensation may occur before the function has made its appearance, as was
+shown to be the case in the testicles and mammae of rabbits. (<cite lang="de" xml:lang="de">Arch. Entw.
+Mech.</cite> 1, 1894, p. 69.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_54_54" id="Footnote_54_54"></a><a href="#FNanchor_54_54"><span class="label">54</span></a> At any given time only the absolute size of the regenerated part is
+greater in animals which are well fed; the degree of differentiation is the
+same in all. Zeleny has found that, if all five arms of a starfish are removed,
+each one of them will regenerate more material in a given time than it
+would have done if it alone had been removed. But these differences also
+only relate to absolute size and not to the degree of differentiation. They
+possibly may be due in fact to conditions of nourishment, but even here
+other explanations seems possible (Zeleny, <cite>Journ. exp. Zool.</cite> 2, 1905).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_55_55" id="Footnote_55_55"></a><a href="#FNanchor_55_55"><span class="label">55</span></a> For a good discussion of “super-regeneration” in the roots of plants see
+Němec, <cite lang="de" xml:lang="de">Studien über die Regeneration</cite>, Berlin, 1905. Goebel and Winkler
+have succeeded in provoking the “restitution” of parts which were not
+removed at all by simply stopping their functions (leaves of certain plants
+were covered with plaster, etc.). (<cite lang="de" xml:lang="de">Biol. Centralbl.</cite> 22, 1902, p. 385; <cite lang="de" xml:lang="de">Ber.
+Bot. Ges.</cite> 20, 1902, p. 81.) A fine experiment is due to Miehe. The alga
+<i class="biological-name">Cladophora</i> was subjected to “plasmolysis,” each cell then formed a new
+membrane of its own around the smaller volume of its protoplasm; after
+that the plants were brought back to a medium of normal osmotic pressure,
+and then each single cell grew up into a little plant (all of them being of
+the same polarity!). Two questions seem to be answered by this fact:
+loss of communication is of fundamental importance to restitution, and the
+removal of mechanical obstacles plays no part in it, for the mechanical
+resistances were the same at the end of the experiment as they had been at
+the beginning. (<cite lang="de" xml:lang="de">Ber. Bot. Ges.</cite> 23, 1905, p. 257.) For fuller analysis of all
+the problems of this chapter see my Organische Regulationen, my reviews
+in the <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>, vols. viii. xi.
+xiv., and my Boston address mentioned above. Compare also Fitting,
+<cite lang="de" xml:lang="de">Ergebn. d. Physiol.</cite> vols. iv. and v.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_56_56" id="Footnote_56_56"></a><a href="#FNanchor_56_56"><span class="label">56</span></a> The so-called “inner secretion” in physiology proper would offer a
+certain analogy to the facts assumed by such an hypothesis. Compare the
+excellent summary given by E. Starling at the seventy-eighth meeting of the
+German “Naturforscherversammlung,” Stuttgart, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_57_57" id="Footnote_57_57"></a><a href="#FNanchor_57_57"><span class="label">57</span></a> The name of singular-equipotential systems might also be applied to
+elementary organs, the single potencies of which are awaked to organogenesis
+by specific formative stimuli from without; but that is not the case in the
+systems studied in this chapter.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_58_58" id="Footnote_58_58"></a><a href="#FNanchor_58_58"><span class="label">58</span></a> The distance of the other boundary line from <i>a</i> or <i>b</i> would be given by
+the value of <i>s</i>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_59_59" id="Footnote_59_59"></a><a href="#FNanchor_59_59"><span class="label">59</span></a> A far more thorough analysis of this differentiation has been attempted
+in my paper, “Die Localisation morphogenetischer Vorgänge. Ein Beweis
+vitalistischen Geschehens,” Leipzig, 1899.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_60_60" id="Footnote_60_60"></a><a href="#FNanchor_60_60"><span class="label">60</span></a> This statement is <em>not strictly</em> correct for <i class="biological-name">Tubularia</i>. I found (<cite lang="de" xml:lang="de">Archiv f.
+Entwickelungsmechanik</cite>, ix. 1899), that a reduction of the length of the
+stem is always followed by a reduction of the size of the hydranth-primordium,
+but there is no real proportionality between them. It is only for
+theoretical simplification that a strict proportionality is assumed here, both
+in the text and the diagram. But there is an almost strict proportionality
+in all cases of “closed forms.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_61_61" id="Footnote_61_61"></a><a href="#FNanchor_61_61"><span class="label">61</span></a> One might object here that in a piece of a <i class="biological-name">Tubularia</i> stem, for instance,
+the tissues are in direct contact with the sea-water at the two points of the
+wounds only, and that at these very points a stimulus might be set up&mdash;say
+by a process of diffusion&mdash;which gradually decreases in intensity on its way
+inward. And a similar argument might apply to the small but whole
+blastula of Echinus, and to all other cases. But, in the first place, stimuli
+which only differ in intensity could hardly call forth the typical and typically
+localised single features realised in differentiation. On the other hand&mdash;and
+this will overthrow such an hypothesis completely&mdash;the dependence of
+the single localised effects in every case on the <em>absolute size</em> of the fragment
+or piece chosen for restoration renders quite impossible the assumption
+that all the singularities in the differentiation of the harmonious systems
+might be called forth by single stimuli originating in two fixed places in an
+<em>independent</em> way. These would never result in any “harmonious,” any
+proportionate structure, but a structure of the “normal” proportionality
+<em>and size</em> at its two ends and non-existent in the middle!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_62_62" id="Footnote_62_62"></a><a href="#FNanchor_62_62"><span class="label">62</span></a> See my article in <cite lang="de" xml:lang="de">Biolog. Centralblatt</cite>, 27, 1907, p. 69. The question is
+rendered still more complicated by the fact that in the case of the regeneration,
+say, of a leg it is not the original “morphogenetic compound” which
+is again required for disintegration, after it has become disintegrated once
+already, but only a specific part of it: just that part of it which is necessary
+for producing the leg! On the other hand, it would be impossible to understand,
+on the basis of physical chemistry, how the isolated branchial apparatus
+of <i class="biological-name">Clavellina</i> could be transformed, by chemical processes exclusively, into
+a system of which only a certain <em>part</em> consists of that substance of which
+the starting-point had been composed in its <em>completeness</em>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_63_63" id="Footnote_63_63"></a><a href="#FNanchor_63_63"><span class="label">63</span></a> Besides the specified poles determined by the polar-bilateral structure
+of the protoplasm.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_64_64" id="Footnote_64_64"></a><a href="#FNanchor_64_64"><span class="label">64</span></a> The pressure experiments and the dislocation experiments come into
+account here; for the sake of simplicity they have not been alluded to in the
+main line of our argument.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_65_65" id="Footnote_65_65"></a><a href="#FNanchor_65_65"><span class="label">65</span></a> My “first proof of vitalism” was first developed in the paper, “Die
+Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional
+remarks in <cite lang="de" xml:lang="de">Organische Regulationem</cite>, Leipzig, 1901, and in <cite lang="de" xml:lang="de">Archiv für
+Entwickelungsmechanik</cite>, 14, 1902.) I cannot admit that any really serious
+objection has been brought forward against it. (See my articles in <cite lang="de" xml:lang="de">Biologisches
+Centralblatt</cite>, 22, 23, 27, and in <cite lang="de" xml:lang="de">Ergebnisse d. Anat. u. Entwickelungsgesch</cite>.
+11, 14.) An historical sketch of vitalism will be found in my book, <cite lang="de" xml:lang="de">Der
+Vitalismus als Geschichte und als Lehre</cite>, Leipzig, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_66_66" id="Footnote_66_66"></a><a href="#FNanchor_66_66"><span class="label">66</span></a> We are dealing here with morphogenesis and so-called vegetative
+physiology only; to certain psychologists, who have refuted the theory of
+psycho-physical parallelism, I must grant that they also have proved
+vitalism. (See Volume II.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_67_67" id="Footnote_67_67"></a><a href="#FNanchor_67_67"><span class="label">67</span></a> The eight larvae would be incomplete in some respect, but not with
+regard to symmetry. They would be “whole” ones, only showing certain
+defects in their organisation. See page <a href="#Page_65">65</a> note <a href="#Footnote_17_17">17</a>, and page <a href="#Page_73">73</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_68_68" id="Footnote_68_68"></a><a href="#FNanchor_68_68"><span class="label">68</span></a> Reciprocal harmony may be reduced in some cases to the given proportions
+of one original harmonious system, from which the single constituents
+of the complicated system, showing reciprocal harmony, are derived. Then
+we have only an instance of “harmony of constellation” (see p. <a href="#Page_109">109</a>). But
+reciprocal harmony seems to become a problem itself, if it occurs in
+restitutions starting from quite a typical point, selected by the experimenter.
+It will be a problem of future research to give an exact formula of what
+happens here. Reciprocal harmony also occurs in regeneration proper. It is
+known that the formation of the regenerative bud and the differentiation
+of this bud follow each other. As the bud is composed of different elementary
+systems, it follows that these different systems, of which every single one is
+harmonious, also have to work in reciprocity to each other, in order that
+one whole proportionate formation may result.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_69_69" id="Footnote_69_69"></a><a href="#FNanchor_69_69"><span class="label">69</span></a> <cite lang="de" xml:lang="de">Biol. Centralblatt.</cite> 23, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_70_70" id="Footnote_70_70"></a><a href="#FNanchor_70_70"><span class="label">70</span></a> Certain phenomena of the physiology of growth of <i class="biological-name">Geranium Robertianum</i>,
+recently discussed by Francé from a vitalistic point of view (<cite lang="de" xml:lang="de">Zeitschr. Entw.
+lehre</cite>. 1, 1907, Heft iv.), might also belong here. I cannot see an independent
+proof of vitalism in these facts if taken by themselves; a pre-existing
+“machine” cannot be absolutely excluded here.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_71_71" id="Footnote_71_71"></a><a href="#FNanchor_71_71"><span class="label">71</span></a> Driesch, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 5, 1897.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_72_72" id="Footnote_72_72"></a><a href="#FNanchor_72_72"><span class="label">72</span></a> Driesch, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 14, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_73_73" id="Footnote_73_73"></a><a href="#FNanchor_73_73"><span class="label">73</span></a> The root may be restored by regeneration proper, or by the production
+of adventitious roots, or by one of the side-roots changing its geotropism from
+horizontal to positive, according to the smaller or greater distance of the
+wound from the tip.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_74_74" id="Footnote_74_74"></a><a href="#FNanchor_74_74"><span class="label">74</span></a> “Retro”-differentiation, of course, is not “Re”-differentiation (“Umdifferenzierung,”
+see p. <a href="#Page_111">111</a>), though it may help it to occur.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_75_75" id="Footnote_75_75"></a><a href="#FNanchor_75_75"><span class="label">75</span></a> Of course such a real decay of parts may happen in other cases.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_76_76" id="Footnote_76_76"></a><a href="#FNanchor_76_76"><span class="label">76</span></a> Certain cases of retro-differentiation occurring under conditions of strict
+fasting will be described in a later chapter.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_77_77" id="Footnote_77_77"></a><a href="#FNanchor_77_77"><span class="label">77</span></a> Klebs has suppressed the reproductive phase of organisation altogether,
+in fungi as well as in flowering plants, or has made it occur abnormally early,
+merely by changing the “external conditions” and by altering the “internal”
+ones correspondingly. There is hardly anything like an adaptation in these
+cases, which, by the way, offer certain difficulties to analysis, as the boundaries
+between “cause” and “means” are not very sharp here.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_78_78" id="Footnote_78_78"></a><a href="#FNanchor_78_78"><span class="label">78</span></a> Compare Herbst, <cite lang="de" xml:lang="de">Biol. Centralbl.</cite> 15, 1895; and Detto, <cite lang="de" xml:lang="de">Die Theorie der
+direkten Anpassung</cite>, Jena, 1904. A full account of the literature will be
+found in these papers.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_79_79" id="Footnote_79_79"></a><a href="#FNanchor_79_79"><span class="label">79</span></a> Vöchting (<cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 34, 1899) forced the bulbs of plants to
+become parts of the stem, and parts of the stem to form bulbs; in both cases
+the most characteristic changes in histology could be observed, being in part
+adaptations, but in part restitutions of the proper type. (See also my
+<cite lang="de" xml:lang="de">Organische Regulationen</cite>, 1901, p. 84.) A true and simple instance of a
+“secondary adaptation” seems to be furnished in a case described by
+Boirivant. In <i class="biological-name">Robinia</i> all the leaflets of a leaf-stalk were cut off: the leaf-stalk
+itself then changed its structure in order to assist assimilation, and also
+formed real stomata.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_80_80" id="Footnote_80_80"></a><a href="#FNanchor_80_80"><span class="label">80</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 17, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_81_81" id="Footnote_81_81"></a><a href="#FNanchor_81_81"><span class="label">81</span></a> Roux, <cite lang="de" xml:lang="de">Gesammelte Abhandlungen</cite>, vol. i. 1895; in particular, <cite lang="de" xml:lang="de">Der Kampf
+der Teile im Organismus</cite>, Leipzig, 1881.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_82_82" id="Footnote_82_82"></a><a href="#FNanchor_82_82"><span class="label">82</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 21, 1906. By a very detailed comparative study
+Babák was able to prove that it is the plant proteids to which the effect of
+vegetable food is chiefly due; thus we have an adaptation to digestibility.
+Mechanical circumstances are only of secondary importance. (See also Yung.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_83_83" id="Footnote_83_83"></a><a href="#FNanchor_83_83"><span class="label">83</span></a> Atrophy of muscles by inactivity is not to be confused with atrophy by
+cutting the motor nerve; the latter is very much more complete.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_84_84" id="Footnote_84_84"></a><a href="#FNanchor_84_84"><span class="label">84</span></a> Loeb has advocated the view that the “adaptive” growth of working
+muscles is simply due to the presence of a greater number of molecules in
+their protoplasm, muscular activity being generated by a process of chemical
+decomposition.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_85_85" id="Footnote_85_85"></a><a href="#FNanchor_85_85"><span class="label">85</span></a> What has been really <em>proved</em> to exist by the very careful studies carried
+out by Child, is only certain cases of functional adaptation to mechanical
+conditions of the strictest kind, and relating to the general mobility only, but
+nothing more; such adaptations can be said to accompany restitution. See,
+for instance, <cite>Journ. exp. Zool.</cite> 3, 1906, where Child has given a summary of
+his theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_86_86" id="Footnote_86_86"></a><a href="#FNanchor_86_86"><span class="label">86</span></a> Even in Vöchting’s experiments (see page <a href="#Page_174">174</a>, note <a href="#Footnote_79_79">79</a>), in which adaptations
+are mixed with true restitutions in the closest possible manner, a few
+phenomena of the latter type could most clearly be separated. The stimulus
+which called them forth must have been one of the hypothetic sort alluded
+to in a former chapter (see page <a href="#Page_113">113</a>). The best instances of true restitutions
+were offered in those cases, where, after the removal of all the bulbs, typical
+starch-storing cells were formed without the presence of any starch.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_87_87" id="Footnote_87_87"></a><a href="#FNanchor_87_87"><span class="label">87</span></a> <cite lang="de" xml:lang="de">Beiträge zur Lehre von den Functionen der Nervencentren des Frosches</cite>,
+Berlin, 1869.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_88_88" id="Footnote_88_88"></a><a href="#FNanchor_88_88"><span class="label">88</span></a> The “secondary adaptations” observed by Vöchting are too complicated
+and too much mingled with restitutions to allow any definite analysis of the
+fact of the “secondary adaptation” as such.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_89_89" id="Footnote_89_89"></a><a href="#FNanchor_89_89"><span class="label">89</span></a> General literature: Fröhlich, <cite lang="de" xml:lang="de">Das natürliche Zweckmüssigkeitsprincip
+in seiner Bedeutung für Krankheit und Heilung</cite>, 1894. Driesch, <cite lang="de" xml:lang="de">Die
+organischen Regulationen</cite>, 1901. A. Tschermak, “Das Anpassungsproblem in
+der Physiologie der Gegenwart,” in a collection of papers in honour of J. P.
+Pawlow, St. Petersburg, 1904. Bieganski, “Ueber die Zweckmässigkeit in den
+pathologischen Erscheinungen,” <cite lang="de" xml:lang="de">Annal. d. Naturphil.</cite> 5, 1906. Among the
+general text-books of physiology those by Pfeffer (<cite lang="de" xml:lang="de">Pflanzenphysiologie</cite>, 1897–1904)
+and von Bunge (<cite lang="de" xml:lang="de">Lehrbuch d. Phys. d. Menschen</cite>, 1901) are the fullest on
+the subject of “regulations.” See also different papers on general pathology
+by Ribbert.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_90_90" id="Footnote_90_90"></a><a href="#FNanchor_90_90"><span class="label">90</span></a> According to investigations of the last two years, the physics of colloids
+seems to play as important a part in physiology as osmosis does; we here
+meet “means” of functioning just as we have already had “means” of
+organogenesis.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_91_91" id="Footnote_91_91"></a><a href="#FNanchor_91_91"><span class="label">91</span></a> I only mention here that certain modern psychologists have assigned
+the true law of Weber to the sphere of judgment and not of sensation. If
+applied to objective reactions only, in their dependence on objective stimuli,
+it, of course, becomes less ambiguous, and may, in a certain sense, be said to
+measure “acclimatisation” with regard to the stimulus in question. The
+mathematical analogy of the law of Weber to the most fundamental law of
+chemical dynamics seems very important.
+</p>
+<p>
+As to “acclimatisation” in the more usual meaning of the word, with
+regard to a change of the general faculty of resisting certain agents of the
+medium, “immunity” proper is to form a special paragraph of what follows,
+and to “acclimatisation” towards different degrees of salinity (in algae or
+fishes) some special remarks will also be devoted on a proper occasion.
+There remains only “acclimatisation” to different temperatures; but on this
+topic not much more than the fact is known (see Davenport, <cite lang="de" xml:lang="de">Arch. f. Entw.
+Mech.</cite> 2, p. 227). “Acclimatisation” does not allow of a sharp general definition;
+it may be the result of very <em>different</em> kinds of adaptations in our sense
+of the word.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_92_92" id="Footnote_92_92"></a><a href="#FNanchor_92_92"><span class="label">92</span></a> I should think that the problem of the re-establishment of irritability,
+in principle at least, arises even when there is not a trace of so-called
+“fatigue” or of a “refractory period.” The process of restoring may be so
+rapid as not to be noticeable, nevertheless some sort of restoring is to be
+postulated. We may say the “irritability” of an elastic ball is re-established
+by its elasticity. A certain analogy to this case may perhaps be found in the
+muscle. But the irritability of nerves with respect to nervous conduction,
+and of glands with respect to secretion, or of the articulations of <i class="biological-name">Mimosa</i>
+may be well understood, hypothetically at least, if we assume that the
+ordinary course of metabolic events is apt in itself to lead to a certain state
+or condition of the organs in question upon which their irritability is based.
+Certain general conditions of functioning, as for instance the presence of
+oxygen for the contraction of the muscle, would better be looked upon as
+necessary “means” of functioning than as being part of irritability as such.
+“Fatigue,” of course, may also be due to the absence of such “means” or to
+abnormal conditions originated by functioning itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_93_93" id="Footnote_93_93"></a><a href="#FNanchor_93_93"><span class="label">93</span></a> Rubner, <cite lang="de" xml:lang="de">Die Gesetze des Energieverbrauches bei der Ernährung</cite>, Leipzig
+u. Wein, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_94_94" id="Footnote_94_94"></a><a href="#FNanchor_94_94"><span class="label">94</span></a> The phenomenon of fever we leave out of account here; it is regarded by
+some as regulation, by others as a disturbance of heat regulation. Of course,
+if the first view should ever prove to be the right one, fever might be classified
+among the real regulations of the secondary type.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_95_95" id="Footnote_95_95"></a><a href="#FNanchor_95_95"><span class="label">95</span></a> <cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 36, 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_96_96" id="Footnote_96_96"></a><a href="#FNanchor_96_96"><span class="label">96</span></a> Carbohydrates cannot be ionised, and therefore there is no doubt that in
+von Mayenburg’s experiments the organism itself is actively at work. As to
+compounds liable to ionisation, it has been noticed by Maillard that a certain
+regulatory character is contained simply in the physical fact that the degree
+of ionisation changes with concentration: decrease of concentration for instance
+would be followed by an increase of ionisation, and so the osmotic pressure
+may be preserved (<cite lang="fr" xml:lang="fr">C. rend. Soc. Biol.</cite> 53, 1901, p. 880).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_97_97" id="Footnote_97_97"></a><a href="#FNanchor_97_97"><span class="label">97</span></a> In the different experiments of Nathansohn (<cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 38, 1902,
+and 39, 1903) the salinity of the medium was changed in such a way that
+there was in each case either an abnormal increase or an abnormal decrease in
+the concentration of one single ion necessary for metabolism. The cell was
+found to stand these abnormal changes in such a way that in the case of the
+increase of the concentration of the medium it did not allow more than
+a certain amount of the ion in question to come in, and that in the case of
+the decrease it did not allow more than a certain quantity of the ion to go
+out. It thus seems as if the permeability of the surface were adjusted
+to a certain minimum and to a certain maximum of every single ion or
+salt, the permeability being stopped from within to without, whenever the
+minimum, and from without to within, whenever the maximum is reached
+in the cell sap; both irrespective of proper physical osmotic equilibrium
+(“Physiologisches Gleichgewicht”). Thus, in fact, there only would be a
+case of primary regulation, nothing more. It would all appear rather similar
+to what occurs in the kidney. Of course we do not assert that our explanation
+is right, but it is possible and is at the same time the most simple, and
+it is our general practice always to prefer the most simple hypotheses.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_98_98" id="Footnote_98_98"></a><a href="#FNanchor_98_98"><span class="label">98</span></a> Many fishes are able to withstand great changes in the osmotic pressure
+of sea-water; the osmotic pressure of their body fluids, though never in a
+real physical equilibrium with the pressure of the medium, nevertheless may
+vary whenever the abnormal conditions of the latter exceed certain limits.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_99_99" id="Footnote_99_99"></a><a href="#FNanchor_99_99"><span class="label">99</span></a> See Stahl, <cite lang="de" xml:lang="de">Naturw. Wochenschrift</cite>, N. F. 5, 1906, No. 19.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_100_100" id="Footnote_100_100"></a><a href="#FNanchor_100_100"><span class="label">100</span></a> <cite>Arch. Anat. Phys.</cite>, Phys. Abt. Suppl., 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_101_101" id="Footnote_101_101"></a><a href="#FNanchor_101_101"><span class="label">101</span></a> The adaptive phenomena discovered by Gaidukow depend upon a real
+alteration in the formation of pigments. In the (primary) chromatic adaptation
+of pupae of Lepidoptera with respect to the colour of the ground they
+live upon, we only have the variable effects of pre-established chromatophores
+(Poulton, <cite>Phil. Trans. London</cite>, 178 B, 1888; Merrifield, <cite>Trans. Ent. Soc.
+London</cite>, 1898). The same holds for chromatic adaptations in crabs (Gamble
+and Keeble, <cite>Quart. Journ. Micr. Sci.</cite> 43, 1900; Minkiewicz, <cite>Arch. Zool. exp.
+et gén.</cite> sér. 4, 7, notes, 1907).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_102_102" id="Footnote_102_102"></a><a href="#FNanchor_102_102"><span class="label">102</span></a> The theory of oxidation we have shortly sketched here was developed
+in chapter B. 5, of my <cite lang="de" xml:lang="de">Organische Regulationen</cite>. Recent discoveries of
+Winterstein’s (<cite lang="de" xml:lang="de">Zeitschr. allg. Physiol.</cite> 6, 1907) have given the strongest
+support to my hypothetic statements, and, in fact, can be said to have
+brought the doctrine of organic oxidation to a critical point. There can be
+no doubt that oxygen not only plays the “antipoisonous” rôle I had
+assigned to it, but that it is not even of such great importance for the supply
+of functional energy as former times had assumed. No doubt it serves to
+drive the functional machine, but decomposition of certain chemical constituents
+of the organism serves this purpose even more. The latter does so
+in the most fundamental and original manner, so to speak, whilst oxidation
+only burns up its products. Almost all elemental functions, in nerve-tissue
+at least, go on very well in the absence of oxygen, provided that certain
+“poisonous” substances, resulting from this anaërobic metabolism, are
+constantly removed. In normal conditions that is done by oxygen, and in
+doing so oxygen certainly assists the supply of energy, but it does not furnish
+the whole of it. The difference between so-called “aërobic” and “anaërobic”
+life almost completely disappears under such a view, and many so-called
+“regulations,” of course, disappear at the same time; there is no more
+“intramolecular respiration.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_103_103" id="Footnote_103_103"></a><a href="#FNanchor_103_103"><span class="label">103</span></a> But nevertheless albumen is not to be replaced altogether in vertebrates
+by fat or carbohydrate; it probably serves some special function besides
+combustion, even in the adult.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_104_104" id="Footnote_104_104"></a><a href="#FNanchor_104_104"><span class="label">104</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 18, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_105_105" id="Footnote_105_105"></a><a href="#FNanchor_105_105"><span class="label">105</span></a> To a physiological friend of mine I owe the suggestion that it is the
+permanently functioning tissues which stand hunger better than the others,
+at least if the sexual cells might be regarded as capable of a <i lang="fr" xml:lang="fr">sécrétion interne</i>
+in all cases. Then the adaptations in the state of hunger might be said to be
+reduced in some degree to “functional adaptation.” But it must remain an
+open question, it seems to me, whether such a view may indeed hold in the
+face of the facts observed in <i class="biological-name">Planaria</i> and infusorians.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_106_106" id="Footnote_106_106"></a><a href="#FNanchor_106_106"><span class="label">106</span></a> In all cases where fungi of the same species are able to live on different
+hosts, that is, to penetrate membranes of a different chemical character, a
+similar objection as to the “secondary” type of such a regulation may be
+made.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_107_107" id="Footnote_107_107"></a><a href="#FNanchor_107_107"><span class="label">107</span></a> The discovery of Weinland that adult dogs are able to produce “lactase”
+in their pancreas, whenever they are fed, quite abnormally, with milk-sugar,
+has recently been said to be vitiated by an analytical mistake.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_108_108" id="Footnote_108_108"></a><a href="#FNanchor_108_108"><span class="label">108</span></a> Compare the excellent review of the subject by Bayliss and Starling in
+the <cite lang="de" xml:lang="de">Ergebnisse der Physiologie</cite>, 5, 1906, p. 664. The reader who misses here
+an analysis of the brilliant discoveries of Pawlow and his followers, relating
+to so-called “psychical and associative secretion,” will find these facts dealt
+with in another section of the book. These facts, indeed, would prove
+vitalism, it seems to me.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_109_109" id="Footnote_109_109"></a><a href="#FNanchor_109_109"><span class="label">109</span></a> It would be a true secondary metabolic regulation, if after the extirpation
+of one gland another different one were to assume its function. Nothing is
+known in this respect except a few rather doubtful observations about the
+interchange of functions between thymus and thyroid, except also the fact
+that the so-called lymph-glands increase in size after the extirpation of the
+spleen. Even here, of course, a sort of “restitution” would be included in
+adaptation proper.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_110_110" id="Footnote_110_110"></a><a href="#FNanchor_110_110"><span class="label">110</span></a> A good review is given by E. Fromm, <cite lang="de" xml:lang="de">Die chemischen Schutzmittel des
+Tierkörpers bei Vergiftungen</cite>, Strassburg, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_111_111" id="Footnote_111_111"></a><a href="#FNanchor_111_111"><span class="label">111</span></a> Davenport, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 2, 1895–1896, and Hausmann, <i>Pflüger’s
+Arch.</i> 113, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_112_112" id="Footnote_112_112"></a><a href="#FNanchor_112_112"><span class="label">112</span></a> <i>Leçons sur la pathologie comparée de l’inflammation</i>, Paris, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_113_113" id="Footnote_113_113"></a><a href="#FNanchor_113_113"><span class="label">113</span></a> The other steps or phases in the process of inflammation have also been
+regarded as adaptive: the increased quantity of body fluid for instance is
+said to serve to dilute poisonous substances.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_114_114" id="Footnote_114_114"></a><a href="#FNanchor_114_114"><span class="label">114</span></a> See Jacoby, <cite lang="de" xml:lang="de">Immunität und Disposition</cite>, Wiesbaden, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_115_115" id="Footnote_115_115"></a><a href="#FNanchor_115_115"><span class="label">115</span></a> <cite>Collected Studies on Immunity by Ehrlich and his Collaborators</cite>, translated
+by Ch. Bolduan, New York and London, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_116_116" id="Footnote_116_116"></a><a href="#FNanchor_116_116"><span class="label">116</span></a> So-called genuine or innate immunity, in contrast to the immunity
+which is acquired, is of course a case of adaptedness only and not of adaptation.
+There also exists a high degree of specific adaptedness in some animals
+with regard to their faculty of coagulating blood. (See Leo Loeb, <cite>Biol. Bull.</cite>
+9, 1905.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_117_117" id="Footnote_117_117"></a><a href="#FNanchor_117_117"><span class="label">117</span></a> We cannot do more than barely mention here the problem of the localisation
+of anti-body production. In general it seems to be true that anti-bodies
+are produced by those cells which require to be protected against
+toxins; that would agree with the general rule, that all compensation of the
+change of any functional state proceeds from the part changed in its function.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_118_118" id="Footnote_118_118"></a><a href="#FNanchor_118_118"><span class="label">118</span></a> Here again I should like to except from this statement the discoveries
+of Pawlow. See page <a href="#Page_204">204</a>, note <a href="#Footnote_108_108">108</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_119_119" id="Footnote_119_119"></a><a href="#FNanchor_119_119"><span class="label">119</span></a> The few cases of an “improvement” of morphogenetic acts in hydroids
+described by myself are too isolated at present to be more than mere
+problems (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 5, 1897). The same is true, it seems to me,
+with regard to certain recent discoveries made by R. Pearl on <i class="biological-name">Ceratophyllum</i>
+(<cite>Carnegie Inst. Wash. Publ.</cite> No. 58, 1907); and by Zeleny on a medusa
+(<cite>Journ. exp. Zool.</cite> 5, 1907). Pawlow’s discovery, that the enzymotic composition
+of the pancreatic fluid in dogs becomes more and more adapted to
+a specific composition of the food (either meat or bread and milk) the longer
+such a specific composition is offered to the individual animal, may probably
+be understood as a case of mere functional adaptation of the cells of the
+digestive glands, if it stands criticism at all (see Bayliss and Starling, <cite lang="de" xml:lang="de">Ergeb.
+Physiol.</cite> 5, 1906, p. 682).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_120_120" id="Footnote_120_120"></a><a href="#FNanchor_120_120"><span class="label">120</span></a> Experiments carried out in the “Biologische Versuchsanstalt” at Vienna
+indeed have shown that many animal types are capable of at least a certain
+degree of restitution, although they had previously been denied this faculty
+by zoologists.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_121_121" id="Footnote_121_121"></a><a href="#FNanchor_121_121"><span class="label">121</span></a> <cite lang="de" xml:lang="de">Ueber das Gedächtnis als eine allgemeine Function der organischen
+Materie</cite>, Wien, 1870. New edition in <cite lang="de" xml:lang="de">Klassiker d. exakt. Wiss.</cite>, Leipzig,
+Engelmann.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_122_122" id="Footnote_122_122"></a><a href="#FNanchor_122_122"><span class="label">122</span></a> <cite lang="de" xml:lang="de">Die Mneme</cite>, Leipzig, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_123_123" id="Footnote_123_123"></a><a href="#FNanchor_123_123"><span class="label">123</span></a> Driesch, <cite lang="de" xml:lang="de">Organ. Regul.</cite> 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_124_124" id="Footnote_124_124"></a><a href="#FNanchor_124_124"><span class="label">124</span></a> The “ideal whole” is also proved to exist, if any <em>given</em> “Anlage,” say
+of a branch, is forced to give origin to a root, as has really been observed in
+certain plants. This case, like many other less extreme cases of what might
+be called “compensatory heterotypy,” are best to be understood by the aid
+of the concept of “prospective potency.” It is very misleading to speak of
+a metamorphosis here. I fully agree with Krašan about this question. See
+also page <a href="#Page_112">112</a>, note <a href="#Footnote_48_48">48</a>, and my <cite lang="de" xml:lang="de">Organ. Regul.</cite> pp. 77, 78.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_125_125" id="Footnote_125_125"></a><a href="#FNanchor_125_125"><span class="label">125</span></a> Winkler has discovered the important fact, that the adventitious buds
+formed upon leaves may originate either from one single cell of the epidermis
+or from several cells together; a result that is very important with respect
+to the problem of the distribution of “potencies.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_126_126" id="Footnote_126_126"></a><a href="#FNanchor_126_126"><span class="label">126</span></a> The “regeneration” of the brain of annelids for instance is far better
+regarded as an adventitious formation than as regeneration proper: nothing
+indeed goes on here at the locality of the wound; a new brain is formed out
+of the ectoderm at a certain distance from it.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_127_127" id="Footnote_127_127"></a><a href="#FNanchor_127_127"><span class="label">127</span></a> A full “analytical theory of regeneration” has been developed elsewhere
+(<cite lang="de" xml:lang="de">Organ. Regul.</cite> p. 44, etc.). I can only mention here that many different
+problems have to be studied by such a theory. The formation of the
+“Anlage” out of the body and the differentiation of it into the completely
+formed results of regeneration are two of them. The former embraces the
+question about the potencies not only of the regenerating body but of the
+elements of the Anlage also; the latter has to deal with the specific order
+of the single acts of regenerative processes.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_128_128" id="Footnote_128_128"></a><a href="#FNanchor_128_128"><span class="label">128</span></a> And, of course, at the root of every new starting of certain parts of
+morphogenesis also, as in regeneration and in adventitious budding; these
+processes, as we know, being also founded upon “complex-equipotential
+systems,” which have had their “genesis.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_129_129" id="Footnote_129_129"></a><a href="#FNanchor_129_129"><span class="label">129</span></a> New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann;
+see also Bateson, <i>Mendel’s Principles of Heredity</i>, Cambridge, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_130_130" id="Footnote_130_130"></a><a href="#FNanchor_130_130"><span class="label">130</span></a> For the sake of simplicity I shall not deal here with those cases of
+hybridisation in which one quality is “recessive,” the other “dominant,”
+but only allude to the cases, less numerous though they be, where a real
+mixture of maternal and paternal qualities occurs.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_131_131" id="Footnote_131_131"></a><a href="#FNanchor_131_131"><span class="label">131</span></a> This hypothesis was first suggested by Sutton and is at present held by
+orthodox Mendelians; but probably things are a little more complicated in
+reality, as seems to be shown by some facts in the behaviour of so-called
+“extracted recessives.” In Morgan’s <cite>Experimental Zoology</cite>, New York, 1907,
+a full account of the whole matter is given.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_132_132" id="Footnote_132_132"></a><a href="#FNanchor_132_132"><span class="label">132</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 21, 22, and 24, 1906–7; see also Doncaster, <cite>Phil. Trans.
+Royal Soc.</cite> London, B. 196, 1903. The influence of different temperature
+upon the organisation of the hybrids is not always quite pure, inasmuch as
+the paternal and the maternal forms may themselves be changed by this agent.
+In spite of that there exists an influence of the temperature upon the hybrid
+<em>as such</em>, at least with regard to certain features of its organisation.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_133_133" id="Footnote_133_133"></a><a href="#FNanchor_133_133"><span class="label">133</span></a> Only the nucleus of the egg had entered its first stages of activity.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_134_134" id="Footnote_134_134"></a><a href="#FNanchor_134_134"><span class="label">134</span></a> The first proof of vitalism, indeed, rests upon the analysis of the
+differentiation of an harmonious-equipotential system as a <em>whole</em>: this <em>whole</em>
+cannot be a machine that would relate to differentiation as a <em>whole</em>; the
+question whether there might be any machines distributed <em>in</em> the whole, in
+the form of the nuclei is of no importance at all in this argument. Moreover
+the pressure experiments (see page <a href="#Page_63">63</a>) prove the unimportance of such
+“machines” for the specificity of differentiation, and the second proof of
+vitalism shows that the nuclei cannot be regarded as machines accounting for
+differentiation in <em>any</em> way.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_135_135" id="Footnote_135_135"></a><a href="#FNanchor_135_135"><span class="label">135</span></a> Boveri tried to fertilise enucleated fragments of the egg of <i class="biological-name">Sphaerechinus</i>
+with the sperm of <i class="biological-name">Echinus</i>. He failed to get any results in isolated experiments,
+but found a few small larvae of the pure <i class="biological-name">Echinus</i> type in large
+cultures consisting of shaken eggs. But later experiments on hybridisation
+in sea-urchins have shown that a full hybrid of <i class="biological-name">Echinus</i> and <i class="biological-name">Sphaerechinus</i>
+may be purely paternal also.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_136_136" id="Footnote_136_136"></a><a href="#FNanchor_136_136"><span class="label">136</span></a> Surely the new results of Herbst, mentioned above, are another indication
+of the importance of something in the nucleus. The first stage in parthenogenesis,
+which he used in his experiments, is a nuclear phenomenon.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_137_137" id="Footnote_137_137"></a><a href="#FNanchor_137_137"><span class="label">137</span></a> Boveri (<cite lang="de" xml:lang="de">Ergebn. üb. d. Konstitution etc. des Zellkerns</cite>, Jena, 1904;
+and “Zellen-Studien VI.” <cite lang="de" xml:lang="de">Jen. Zeitschr.</cite> 43, 1907) has made it highly probable
+by experiments that the different chromosomes of the nucleus of the sexual
+products play a different part in morphogenesis, though not in the sense of
+different single representatives of different single organs. This doctrine, of
+course, would not alter the whole problem very much: the chromosomes
+would only be <em>means</em> of morphogenesis and nothing else, no matter whether
+they were of equal or of different formative value. It only is with regard to
+the problem of the determination of sex (see page <a href="#Page_107">107</a>, note <a href="#Footnote_46_46">46</a>), that the
+morphogenetic singularity of <em>one</em> certain specific chromosome can be said to
+be proved.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_138_138" id="Footnote_138_138"></a><a href="#FNanchor_138_138"><span class="label">138</span></a> H. M. Vernon, <cite>Variations in Animals and Plants</cite>, London, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_139_139" id="Footnote_139_139"></a><a href="#FNanchor_139_139"><span class="label">139</span></a> De Vries, <cite lang="de" xml:lang="de">Die Mutationstheorie</cite>, i., 1901; and Klebs, <cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite>
+42, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_140_140" id="Footnote_140_140"></a><a href="#FNanchor_140_140"><span class="label">140</span></a> They would not be “real exceptions” if Klebs (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 24,
+1907) were right in saying that both variations and mutations owe their
+existence to external agents. What is really <em>proved</em> by Klebs is the possibility
+of changing the <em>type</em> of a curve of variation and of provoking certain discontinuous
+varieties by external means. See also Blaringhem (<cite lang="fr" xml:lang="fr">Comptes rend.</cite>
+1905–6, and <cite lang="fr" xml:lang="fr">Soc. de Biol.</cite> 59, 1905), and MacDougal (<i>Rep. Depart. Bot. Res.,
+5th Year-book Carnegie Inst.</i>, Washington, 129).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_141_141" id="Footnote_141_141"></a><a href="#FNanchor_141_141"><span class="label">141</span></a> H. de Vries, <i>Species and Varieties: their Origin by Mutation</i>, London,
+1905. A short review of the “mutation-theory” is given by Francé in
+<cite lang="de" xml:lang="de">Zeitschrift f. d. Ausbau d. Entwickelungslehre</cite>, i. 1907. It is well known
+that Gautier, and, in the first place, Korshinsky, advocated a similar view
+previous to the authors named in the text.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_142_142" id="Footnote_142_142"></a><a href="#FNanchor_142_142"><span class="label">142</span></a> Recent years have created the beginnings of a systematics based on
+chemical differences of metabolism and its products: such differences in
+fact have been found to go hand in hand with diversities of the type in
+some cases (v. Bunge, Przibram, etc.).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_143_143" id="Footnote_143_143"></a><a href="#FNanchor_143_143"><span class="label">143</span></a> We prefer this unpretending definition of the theory of descent to every
+other. As soon as one introduces into the definition the concept of the
+“transmutability of species,” the term “species” would require a special
+definition, and that would lead to difficulties which it is unnecessary
+to deal with for our main purposes. It has been remarked by Krašan,
+(<cite lang="de" xml:lang="de">Ausichten und Gespräche über die individuelle und specifische Gestaltung
+in der Natur</cite>) and by several other writers, that the problem of
+mutability or immutability of course relates to the individuals in the first
+place. I should like to add to this remark that the possibility must be
+admitted of the individuals being transmutable, whilst the “species”
+are not transmutable at the same time, the line of the “species” being a fixed
+order, through which the “individuals” have to pass in the course of their
+generations. What is meant here will become clearer, when we study the
+different possible aspects of “phylogeny.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_144_144" id="Footnote_144_144"></a><a href="#FNanchor_144_144"><span class="label">144</span></a> It seems to me that my argument gives a broader logical basis to the
+theory of descent than does that of G. Wolff (<cite lang="de" xml:lang="de">Die Begründung der
+Abstammungslehre</cite>, München, 1907). Wolff starts from the concept of
+organic teleology, and thus finds the only reason for accepting the theory
+of transformism in the existence of so-called “rudimentary organs”; these
+organs would form an obstacle to teleology if they could not be regarded
+as inherited.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_145_145" id="Footnote_145_145"></a><a href="#FNanchor_145_145"><span class="label">145</span></a> See Wigand, <i>Der Darwinismus und die Naturforschung Newton’s und
+Cuvier’s</i>, Braunschweig, 1874–7; Nägeli, <i>Mechanisch-physiologische Theorie
+der Abstammungslehre</i>, München, 1884; G. Wolff, <i>Beiträge zur Kritik der
+Darwin’schen Lehre</i>, 2nd ed. Leipzig, 1898; etc.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_146_146" id="Footnote_146_146"></a><a href="#FNanchor_146_146"><span class="label">146</span></a> <cite lang="de" xml:lang="de">Darwinismus und Lamarckismus</cite>, München, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_147_147" id="Footnote_147_147"></a><a href="#FNanchor_147_147"><span class="label">147</span></a> This would not be true, if the varieties of plants produced by Blaringhem,
+Klebs, and MacDougal by means of <em>external</em> agents were really
+“mutations” (comp. page 238, note 3).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_148_148" id="Footnote_148_148"></a><a href="#FNanchor_148_148"><span class="label">148</span></a> Of course, the inheritance of mutations would imply a certain sort of
+“inheritance of acquired characters,” on the condition stated in the preceding
+note. But, probably, the germs of the next generation might be
+regarded here as being directly affected by the external agent, in a manner
+that will briefly be mentioned later on in the text.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_149_149" id="Footnote_149_149"></a><a href="#FNanchor_149_149"><span class="label">149</span></a> Comp. page 238, note 2.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_150_150" id="Footnote_150_150"></a><a href="#FNanchor_150_150"><span class="label">150</span></a> Certain English authors have applied the term “modification” to all kinds
+of organic properties acquired from without, whether they are adapted or not.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_151_151" id="Footnote_151_151"></a><a href="#FNanchor_151_151"><span class="label">151</span></a> Of course the inheritance of specific values from the results of fluctuating
+variations, leading to new averages of variability (see p. <a href="#Page_265">265</a>), may also be
+understood in this manner, the conditions of nourishment acting upon the
+adult and upon its germs equally well.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_152_152" id="Footnote_152_152"></a><a href="#FNanchor_152_152"><span class="label">152</span></a> <cite lang="de" xml:lang="de">Berichte üb. d. Sitzung. d. Ges. f. Bot.</cite>, Hamburg, 1887, 3 Heft.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_153_153" id="Footnote_153_153"></a><a href="#FNanchor_153_153"><span class="label">153</span></a> Quite recently Kammerer (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 25, 1907, p. 7) has
+published very important experiments on the inheritance of “acquired”
+modifications with regard to the peculiarities of reproduction in <i class="biological-name">Salamandra
+atra</i> and <i class="biological-name">S. maculosa</i>. It seems rather improbable&mdash;though not absolutely
+impossible&mdash;that the germ cells were directly affected by the external
+modifying agent in this case.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_154_154" id="Footnote_154_154"></a><a href="#FNanchor_154_154"><span class="label">154</span></a> We have not spoken about the hypothetic inheritance of pure physiological
+adaptations, for it is clear without further discussion that innate
+specific immunity, for instance, being a specific “adaptedness” (<i>see</i> p. <a href="#Page_186">186</a>)
+<em>might</em> be due to the inheritance of the results of active immunity as an
+adaptation, just as adaptive congenital structures <em>might</em> be due to such
+an inheritance.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_155_155" id="Footnote_155_155"></a><a href="#FNanchor_155_155"><span class="label">155</span></a> C. E. v. Baer clearly discriminated between the type, the degree of
+organisation, and the histological structure. All these three topics indeed
+have to be taken into account separately; the third alone is of the adaptive
+type. All of them may be independent of each other: the Amoeba may
+be as adapted histologically as is a high vertebrate, but it is of much
+lower type; and in its own type it is of a lower degree of organisation than
+Radiolaria are.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_156_156" id="Footnote_156_156"></a><a href="#FNanchor_156_156"><span class="label">156</span></a> I repeat once more that we are dealing here with dogmatic “Neo-”Lamarckism
+exclusively. This theory indeed claims to explain <em>all</em> features
+and properties of organic bodies on the basis of the feeling of needs and
+storing of contingent fulfilments and on this basis alone, just as dogmatic
+“Neo”-Darwinism claims to account for <em>all</em> those phenomena on the
+ground of contingent variations and natural selection. Darwin himself, as
+we have seen, intentionally left unexplained certain primary features of life
+and therefore cannot be blamed for having failed to explain them, though
+even then his theory remains wrong. Lamarck personally considered a
+real primary organisatory law of phylogeny as being of fundamental importance,
+and therefore he is not in the least responsible if “Neo-Lamarckism”
+fails as a universal theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_157_157" id="Footnote_157_157"></a><a href="#FNanchor_157_157"><span class="label">157</span></a> Compare also the excellent criticism of Lamarckism lately given by
+G. Wolff, <cite lang="de" xml:lang="de">Die Begründung der Abstammungslehre</cite>, München, 1907.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_158_158" id="Footnote_158_158"></a><a href="#FNanchor_158_158"><span class="label">158</span></a> It has also very often been said by Darwinians that Lamarckism is
+only able to explain those cases of adaptedness which relate to active
+functioning but not mere passive adapted characters, like “mimicry” for
+example. But this argument <em>taken by itself</em>, it seems to me, would not be
+fatal to Neo-Lamarckism in the special form August Pauly gave to this
+doctrine.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_159_159" id="Footnote_159_159"></a><a href="#FNanchor_159_159"><span class="label">159</span></a> But nothing more. All “mutations” hitherto observed in nature or
+(comp. page 238, note 3) experimentally produced relate only to “varieties”
+and not to “species.” One could hardly say that the recent investigations
+about the production of mutations by <em>external</em> means have strengthened
+their importance for the general theory of transformism.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_160_160" id="Footnote_160_160"></a><a href="#FNanchor_160_160"><span class="label">160</span></a> The word “possible” relating to originating, of course, not to surviving.
+It is here that natural selection may acquire its logical importance alluded
+to above (see page <a href="#Page_264">264</a>).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_161_161" id="Footnote_161_161"></a><a href="#FNanchor_161_161"><span class="label">161</span></a> The discussions in the second volume of this book will show the possible
+significance of such an analysis. We at present are dealing with entelechy
+in a quasi-popular manner.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_162_162" id="Footnote_162_162"></a><a href="#FNanchor_162_162"><span class="label">162</span></a> See pp. <a href="#Page_26">26</a>, <a href="#Page_45">45</a>, <a href="#Page_54">54</a>, etc.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_163_163" id="Footnote_163_163"></a><a href="#FNanchor_163_163"><span class="label">163</span></a> An immanent vitalistic phylogeny <em>without</em> a pre-established end has
+recently been advocated by H. Bergson (<i>L’évolution créatrice</i>, Paris, 1907).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_164_164" id="Footnote_164_164"></a><a href="#FNanchor_164_164"><span class="label">164</span></a> In this connection the problem may be raised, whether there can be such
+a thing as unchangeable “species” in spite of the mutability of the
+individuals. Compare page 251, note 1.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_165_165" id="Footnote_165_165"></a><a href="#FNanchor_165_165"><span class="label">165</span></a> On account of the limited size of the earth a certain final stage of
+human civilisation might be expected in a future time; but it would be
+the size of the earth which determined this end, and not the process of
+civilisation itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_166_166" id="Footnote_166_166"></a><a href="#FNanchor_166_166"><span class="label">166</span></a> <cite lang="de" xml:lang="de">Die Grenzen der naturwissenschaftlichen Begriffsbildung</cite>, Tübingen and
+Leipzig, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_167_167" id="Footnote_167_167"></a><a href="#FNanchor_167_167"><span class="label">167</span></a> The word “universality” to be understood here in quite an unpretentious
+quasi-popular meaning, not strictly epistemologically.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_168_168" id="Footnote_168_168"></a><a href="#FNanchor_168_168"><span class="label">168</span></a> To avoid mistakes I wish to say here most emphatically that, according
+to Rickert, the method of history is regarded as completely <em>free</em> from subjectivity
+as soon as its “values” are once <em>established</em>. But this cannot
+avail to save the theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_169_169" id="Footnote_169_169"></a><a href="#FNanchor_169_169"><span class="label">169</span></a> This is a rather optimistic conception of “history.” Personally, I
+must confess that even its emotional and practical importance seems to me
+to be at least diminished by the retarding effects which all sorts of
+“historical” considerations&mdash;in science as well as in arts and in public life&mdash;carry
+with them. All real progress is non-historical&mdash;and its champions
+almost always have become martyrs: this fact seems not to recommend
+history as a means of education, except for persons of a very strong
+character.</p></div></div>
+
+<div>*** END OF THE PROJECT GUTENBERG EBOOK 44388 ***</div>
+</body>
+</html>
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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #44388 (https://www.gutenberg.org/ebooks/44388)
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+The Project Gutenberg EBook of The Science and Philosophy of the Organism, by 
+Hans Driesch
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Science and Philosophy of the Organism
+       The Gifford Lectures Delivered Before the University of
+       Aberdeen in the Year 1907
+
+Author: Hans Driesch
+
+Release Date: December 8, 2013 [EBook #44388]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE SCIENCE AND PHILOSOPHY ***
+
+
+
+
+Produced by Marilynda Fraser-Cunliffe, Thiers Halliwell
+and the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+Transcriber’s notes:
+
+In this transcription, italic text is denoted by *asterisks* and bold
+text by =equal signs=. Subscripts are indicated by _underscores_ (e.g.
+*a*_1 and *b*_1 in Fig.5 caption) and superscripts by ^ (e.g. *a*^1. in
+Fig. 9 caption).
+
+Page footnotes (renumbered in consecutive order) are now located
+immediately below the relevant paragraphs.
+
+The rare spelling typos noted in the original text have been corrected
+silently (e.g. invividual-->individual, hyberbola-->hyperbola) but
+inconsistent use of the ligature æ/ae (e.g. palæontology/palaeontology),
+inconsistent use of alternative spellings (e.g. learned/learnt), and
+occasional inconsistencies of hyphenation have been left as in the
+original. Minor punctuation typos have been corrected silently (e.g.
+index entries with missing commas). The abbreviation viz. appears in
+both roman and italic font.
+
+Formatting of entries in the Table of Contents does not accurately
+match that of the corresponding headings in the text, particularly the
+heading Pt.I-B-3 which contains an extraneous α.
+
+In Figure 12 caption, multiple ditto marks have been replaced by the
+relevant text for greater clarity.
+
+
+
+
+
+                       THE SCIENCE AND PHILOSOPHY
+                            OF THE ORGANISM
+
+
+
+
+          AGENTS
+
+            America        The Macmillan Company
+                             64 & 66 Fifth Avenue, New York
+
+            Australasia    The Oxford University Press, Melbourne
+
+            Canada         The Macmillan Company of Canada, Ltd.
+                             27 Richmond Street West, Toronto
+
+            India          Macmillan & Company, Ltd.
+                             Macmillan Building, Bombay
+                             309 Bow Bazaar Street, Calcutta
+
+
+
+
+                                  THE
+                         SCIENCE AND PHILOSOPHY
+                            OF THE ORGANISM
+
+                 THE GIFFORD LECTURES DELIVERED BEFORE
+                       THE UNIVERSITY OF ABERDEEN
+                            IN THE YEAR 1907
+
+                                   BY
+                          HANS DRIESCH, Ph.D.
+                               HEIDELBERG
+
+
+                                 LONDON
+                         ADAM AND CHARLES BLACK
+                                  1908
+
+                         *All rights reserved*
+
+
+
+
+PREFACE
+
+
+This work is not a text-book of theoretical biology; it is a systematic
+presentment of those biological topics which bear upon the true
+philosophy of nature. The book is written in a decidedly subjective
+manner, and it seems to me that this is just what “Gifford Lectures”
+ought to be. They ought never to lose, or even try to lose, their
+decidedly personal character.
+
+My appointment as Gifford Lecturer, the news of which reached me in
+February 1906, came just at the right moment in the progress of my
+theoretical studies. I had always tried to improve my previous books by
+adding notes or altering the arrangement; I also had left a good deal of
+things unpublished, and thus I often hoped that I might have occasion
+to arrange for a new, improved, and enlarged edition of those books.
+This work then is the realisation of my hopes; it is, in its way, a
+definitive statement of all that I have to say about the Organic.
+
+The first volume of this work, containing the lectures for 1907--though
+the division into “lectures” has not been preserved--consists of Parts
+I. and II. of Section A, “The Chief Results of Analytical Biology.”
+It gives in Part I. a shortened, revised, and, as I hope, improved
+account of what was published in my *Analytische Theorie der organischen
+Entwickelung* (1894), *Die Localisation morphogenetischer Vorgänge;
+ein Beweis Vitalistischen Geschehens* (1899), and *Die organischen
+Regulationen* (1901), though for the professed biologist the two
+last-named books are by no means superseded by the new work. Part II.
+has never been published in any systematic form before, though there are
+many remarks on Systematics, Darwinism, etc., in my previous papers.
+
+The second volume--to be published in the autumn, after the delivery of
+the 1908 lectures--will begin with the third and concluding part of the
+scientific section, which is a very carefully revised and rearranged
+second edition of my book, *Die “Seele” als elementarer Naturfactor*
+(1903). The greater part of this volume, however, will be devoted to the
+“Philosophy of the Organism,” *i.e.* Section B, which, in my opinion,
+includes the most important parts of the work.
+
+Some apology is needed for my presuming to write in English. I was
+led to do so by the conviction, mistaken perhaps, that the process of
+translation would rob the lectures of that individual and personal
+character which, as I said before, seems to me so much to be desired. I
+wished nothing to come between me and my audience. I accordingly wrote
+my manuscript in English, and then submitted it to linguistic revision
+by such skilled aid as I was able to procure at Heidelberg. My reviser
+tells me that if the result of his labours leaves much to be desired,
+it is not to be wondered at, but that, being neither a biologist nor a
+philosopher, he has done his best to make me presentable to the English
+reader. If he has failed in his troublesome task, I know that it is not
+for want of care and attention, and I desire here to record my sense of
+indebtedness to him. He wishes to remain anonymous, but I am permitted
+to say that, though resident in a foreign university, he is of Scottish
+name and English birth.
+
+My gratitude to my friends at Aberdeen, in particular to Professor and
+Mrs. J. A. Thomson, for their hospitality and great kindness towards me
+cannot be expressed here; they all know that they succeeded in making me
+feel quite at home with them.
+
+I am very much obliged to my publishers, Messrs. A. and C. Black, for
+their readiness to fulfil all my wishes with respect to publication.
+
+
+The lectures contained in this book were written in English by a
+German and delivered at a Scottish university. Almost all of the ideas
+discussed in it were first conceived during the author’s long residence
+in Southern Italy. Thus this book may be witness to the truth which,
+I hope, will be universally recognised in the near future--that all
+culture, moral and intellectual and aesthetic, is not limited by the
+bounds of nationality.
+
+  HANS DRIESCH.
+
+  Heidelberg, *2nd January 1908*.
+
+
+
+
+CONTENTS OF THE FIRST VOLUME
+
+
+                             THE PROGRAMME
+
+                                                                   PAGE
+  On Lord Gifford’s Conception of “Science”                           1
+  Natural Sciences and “Natural Theology”                             3
+  Our Philosophical Basis                                             5
+  On Certain Characteristics of Biology as a Science                  9
+  The Three Different Types of Knowledge about Nature                13
+  General Plan of these Lectures                                     15
+  General Character of the Organic Form                              19
+
+
+          SECTION A.--THE CHIEF RESULTS OF ANALYTICAL BIOLOGY
+
+  PART I.--THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM
+
+  *A.* ELEMENTARY MORPHOGENESIS--
+
+    Evolutio and Epigenesis in the old Sense                         25
+    The Cell                                                         27
+    The Egg: its Maturation and Fertilisation                        31
+    The First Developmental Processes of Echinus                     33
+    Comparative Embryology                                           44
+    The First Steps of Analytical Morphogenesis                      45
+    The Limits of Pure Description in Science                        50
+
+  *B.* EXPERIMENTAL AND THEORETICAL MORPHOGENESIS--
+
+  1. THE FOUNDATIONS OF THE PHYSIOLOGY OF DEVELOPMENT.
+    “EVOLUTIO” AND “EPIGENESIS”                                      52
+
+    The Theory of Weismann                                           52
+    Experimental Morphology                                          56
+    The Work of Wilhelm Roux                                         58
+    The Experiments on the Egg of the Sea-urchin                     59
+    On the Intimate Structure of the Protoplasm of the Germ          65
+    On some Specificities of Organisation in Certain Germs           70
+    General Results of the First Period of “Entwickelungsmechanik”   71
+    Some New Results concerning Restitutions                         74
+
+  2. ANALYTICAL THEORY OF MORPHOGENESIS                              76
+
+    α. THE DISTRIBUTION OF MORPHOGENIC POTENCIES                     76
+
+      Prospective Value and Prospective Potency                      76
+      The Potencies of the Blastomeres                               79
+      The Potencies of Elementary Organs in General                  80
+      Explicit and Implicit Potencies: Primary and Secondary
+        Potencies                                                    83
+      The Morphogenetic Function of Maturation in the Light of
+        Recent Discoveries                                           85
+      The Intimate Structure of Protoplasm: Further Remarks          88
+      The Neutrality of the Concept of “Potency”                     89
+
+    β. THE “MEANS” OF MORPHOGENESIS                                  89
+
+    β′. The Internal Elementary Means of Morphogenesis                90
+
+      Some Remarks on the Importance of Surface Tension in
+        Morphogenesis                                                91
+      On Growth                                                      93
+      On Cell-division                                               94
+
+    β″. The External Means of Morphogenesis                          95
+
+      The Discoveries of Herbst                                      96
+
+    γ. THE FORMATIVE CAUSES OR STIMULI                               99
+
+      The Definition of Cause                                        99
+      Some Instances of Formative and Directive Stimuli             102
+
+    δ. THE MORPHOGENETIC HARMONIES                                  107
+
+    ε. ON RESTITUTIONS                                              110
+
+      A few Remarks on Secondary Potencies and on Secondary
+        Morphogenetic Regulations in General                        110
+      The Stimuli of Restitutions                                   113
+
+  3. THE PROBLEM OF MORPHOGENETIC LOCALISATION: THE
+     THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM--FIRST
+     PROOF OF THE AUTONOMY OF LIFE                                  118
+
+    The General Problem                                             118
+    The Morphogenetic “System”                                      119
+    The “Harmonious-equipotential System”                           122
+    Instances of “Harmonious-equipotential Systems”                 126
+    The Problem of the Factor *E*                                   132
+    No Explanation offered by “Means” or “Formative Stimuli”        132
+    No Explanation offered by a Chemical Theory of Morphogenesis    134
+    No Machine Possible Inside the Harmonious Systems               138
+    The Autonomy of Morphogenesis proved                            142
+    “Entelechy”                                                     143
+    Some General Remarks on Vitalism                                145
+    The Logic of our First Proof of Vitalism                        146
+
+  4. ON CERTAIN OTHER FEATURES OF MORPHOGENESIS ADVOCATING
+     ITS AUTONOMY                                                   150
+
+    Harmonious-equipotential Systems formed by Wandering Cells      151
+    On Certain Combined Types of Morphogenetic Systems              153
+    The “Morphaesthesia” of Noll                                    157
+    Restitutions of the Second Order                                158
+    On the “Equifinality” of Restitutions                           159
+    Remarks on “Retro-Differentiation”                              163
+
+  *C.* ADAPTATION--
+
+  INTRODUCTORY REMARKS ON REGULATIONS IN GENERAL                    165
+
+  1. MORPHOLOGICAL ADAPTATION                                       168
+
+    The Limits of the Concept of Adaptation                         168
+    Adaptations to Functional Changes from Without                  172
+    True Functional Adaptation                                      176
+    Theoretical Conclusions                                         179
+
+  2. PHYSIOLOGICAL ADAPTATION                                       184
+
+    Specific Adaptedness *not* “Adaptation”                         186
+    Primary and Secondary Adaptations in Physiology                 188
+    On Certain Pre-requisites of Adaptations in General             189
+    On Certain Groups of Primary Physiological Adaptations          190
+
+    General Remarks on Irritability                                 190
+    The Regulation of Heat Production                               193
+    Primary Regulations in the Transport of Materials and
+      Certain Phenomena of Osmotic Pressure                         194
+    Chromatic Regulations in Algae                                  197
+    Metabolic Regulations                                           198
+
+    Immunity the only Type of a Secondary Physiological
+      Adaptation                                                    204
+    No General Positive Result from this Chapter                    209
+    A few Remarks on the Limits of Regulability                     212
+
+  *D.* INHERITANCE. SECOND PROOF OF THE AUTONOMY OF LIFE--
+
+    The Material Continuity in Inheritance                          214
+    On Certain Theories which Seek to Compare Inheritance to Memory 216
+    The Complex-Equipotential System and its Rôle in Inheritance    219
+    The Second Proof of Life-Autonomy. Entelechy at the Bottom
+      of Inheritance                                                224
+    The Significance of the Material Continuity in Inheritance      227
+    The Experimental Facts about Inheritance                        228
+    The Rôle of the Nucleus in Inheritance                          233
+    Variation and Mutation                                          237
+
+  *CONCLUSIONS FROM THE FIRST MAIN PART OF THESE LECTURES*          240
+
+
+                   PART II.--SYSTEMATICS AND HISTORY
+
+  *A.* THE PRINCIPLES OF SYSTEMATICS--
+
+    Rational Systematics                                            243
+    Biological Systematics                                          246
+
+  *B.* THE THEORY OF DESCENT--
+
+  1. GENERALITIES                                                   250
+
+    The Covert Presumption of all Theories of Descent               253
+    The Small Value of Pure Phylogeny                               255
+    History and Systematics                                         257
+
+  2. THE PRINCIPLES OF DARWINISM                                    260
+
+    Natural Selection                                               261
+    Fluctuating Variation the Alleged Cause of Organic Diversity    264
+    Darwinism Fails all along the Line                              269
+
+  3. THE PRINCIPLES OF LAMARCKISM                                   271
+
+    Adaptation as the Starting-Point                                272
+    The Active Storing of Contingent Variations as a
+      Hypothetic Principle                                          273
+    Criticism of the “Inheritance of Acquired Characters”
+      assumed by Lamarckism                                         275
+    Other Principles Wanted                                         281
+    Criticism of the Hypothesis of Storing and Handing Down
+      Contingent Variations                                         282
+
+  4. THE REAL RESULTS AND THE UNSOLVED PROBLEMS OF TRANSFORMISM     290
+
+  5. THE LOGICAL VALUE OF THE ORGANIC FORM ACCORDING TO THE
+     DIFFERENT TRANSFORMISTIC THEORIES                              293
+
+    The Organic Form and Entelechy                                  294
+
+  *C.* THE LOGIC OF HISTORY                                         297
+
+  1. THE POSSIBLE ASPECTS OF HISTORY                                299
+
+  2. PHYLOGENETIC POSSIBILITIES                                     304
+
+  3. THE HISTORY OF MANKIND                                         306
+
+    Cumulations in Human History                                    308
+    Human History not an “Evolution”                                311
+    The Problem of the “Single” as such                             315
+
+  *CONCLUSIONS ABOUT SYSTEMATICS AND HISTORY IN GENERAL*            322
+
+
+
+
+THE PROGRAMME
+
+
+ON LORD GIFFORD’S CONCEPTION OF “SCIENCE”
+
+This is the first time that a biologist has occupied this place; the
+first time that a biologist is to try to carry out the intentions of the
+noble and high-minded man to whom this lectureship owes its foundation.
+
+On such an occasion it seems to be not undesirable to inquire what Lord
+Gifford’s own opinions about natural science may have been, what place
+in the whole scheme of human knowledge he may have attributed to those
+branches of it which have become almost the centre of men’s intellectual
+interest.
+
+And, indeed, on studying Lord Gifford’s bequest with the object of
+finding in it some reference to the natural sciences, one easily notes
+that he has assigned to them a very high place compared with the other
+sciences, at least in one respect: with regard to their methods.
+
+There is a highly interesting passage in his will which leaves no doubt
+about our question. After having formally declared the foundation of
+this lectureship “for Promoting, Advancing, Teaching and Diffusing
+the study of Natural Theology in the widest sense of that term,” and
+after having arranged about the special features of the lectures, he
+continues: “I wish the lecturers to treat their subject as a strictly
+natural science, the greatest of all possible sciences, indeed, in one
+sense, the only science, that of Infinite Being.... I wish it considered
+just as astronomy or chemistry is.”
+
+Of course, it is not possible to understand these words of Lord
+Gifford’s will in a quite literal sense. If, provisionally, we call
+“natural theology” the ultimate conclusions which may be drawn from a
+study of nature in connection with all other results of human sciences,
+there cannot be any doubt that these conclusions will be of a rather
+different character from the results obtained in, say, the special field
+of scientific chemistry. But, nevertheless, there are, I think, two
+points of contact between the wider and the narrower field of knowledge,
+and both of them relate to method. Lord Gifford’s own phrase, “Infinite
+Being,” shows us one of these meeting-points. In opposition to history
+of any form, natural sciences aim at discovering such truths as are
+independent of special time and of special space, such truths as are
+“ideas” in the sense of Plato; and such eternal results, indeed, always
+stand in close relation to the ultimate results of human knowledge
+in general. But besides that there is still another feature which
+may be common both to “natural theology” and to the special natural
+sciences, and which is most fully developed in the latter: freedom from
+prepossessions. This, at least, is an ideal of all natural sciences;
+I may say it is *the* ideal of them. That it was this feature which
+Lord Gifford had in view in his comparison becomes clear when we read
+in his will that the lectures on natural theology are to be delivered
+“without reference to or reliance upon any supposed special exceptional
+or so-called miraculous revelation.”
+
+So we might say that both in their logical and their moral methods,
+natural sciences are to be the prototype of “Natural Theology” in Lord
+Gifford’s sense.
+
+
+NATURAL SCIENCES AND “NATURAL THEOLOGY”
+
+But now let us study in a more systematic manner the possible relations
+of the natural sciences to natural theology as a science.
+
+How is it possible for a natural scientist to contribute to the science
+of the highest and ultimate subject of human knowledge?
+
+Almost all natural sciences have a sort of naïveté in their own spheres;
+they all stand on the ground of what has been called a naïve realism,
+as long as they are, so to say, at home. That in no way prejudices
+their own progress, but it seems to stand in the way of establishing
+contact with any higher form of human knowledge than themselves.
+One may be a first-rate organic chemist even when looking upon the
+atoms as small billiard balls, and one may make brilliant discoveries
+about the behaviour of animals even when regarding them in the most
+anthropomorphic manner--granted that one is a good observer; but it
+can hardly be admitted that our chemist would do much to advance the
+theory of matter, or our biologist to solve the problem of the relations
+between body and mind.
+
+It is only by the aid of philosophy, or I would rather say by keeping
+in constant touch with it, that natural sciences are able to acquire
+any significance for what might be called *the* science of nature in the
+most simple form. Unhappily the term “natural philosophy” is restricted
+in English to theoretical physics. This is not without a high degree of
+justification, for theoretical physics has indeed lost its naïveté and
+become a philosophy of nature; but it nevertheless is very unfortunate
+that this use of the term “natural philosophy” is established in
+this country, as we now have no proper general term descriptive of a
+natural science that is in permanent relation to philosophy, a natural
+science which does not use a single concept without justifying it
+epistemologically, *i.e.* what in German, for instance, would simply be
+called “Naturphilosophie.”
+
+Let us call it philosophy of nature; then we may say that only by
+becoming a true philosophy of nature are natural sciences of all sorts
+able to contribute to the highest questions which man’s spirit of
+inquiry can suggest.
+
+These highest questions themselves are the outcome of the combination
+of the highest results of all branches of philosophy, just as our
+philosophy of nature originated in the discussion of the results of
+all the separate natural sciences. Are those highest questions not
+only to be asked, are they to be also solved? To be solved in a way
+which does not exceed the limits of philosophy as the domain of actual
+understanding?
+
+The beginning of a long series of studies is not the right place to
+decide this important question; and so, for the present certainly,
+“natural theology” must remain a problem. In other words: it must
+remain an open question at the beginning of our studies, whether after
+all there can be any final general answer, free from contradictions,
+applicable to the totality of questions asked by all the branches of
+philosophy.
+
+But let us not be disturbed by this problematic entrance to our studies.
+Let us follow biology on its own path; let us study its transition from
+a “naïve” science to a real branch of the philosophy of nature. In this
+way we perhaps shall be able to understand what its part may be in
+solving what can be solved.
+
+That is to be our subject.
+
+
+OUR PHILOSOPHICAL BASIS
+
+We call *nature* what is given to us in space.
+
+Of course we are not obliged in these lectures to discuss the
+psychological and epistemological problems of space with its three
+dimensions, nor are we obliged to develop a general theory of reality
+and its different aspects. A few epistemological points will be
+considered later at proper times, and always in connection with results
+of theoretical biology.
+
+At present it must suffice to say that our general philosophical point
+of view will be idealistic, in the critical meaning of the word. The
+universe, and within the universe nature, in the sense just defined,
+is my phenomenon. That is what I know. I know nothing more, either
+positively or negatively; that is to say, I do not know that the world
+is *only my* phenomenon, but, on the other hand, I know nothing about
+its “absolute reality.” And more, I am not even able to describe in
+intelligible words what “absolute reality” might mean. I am fully
+entitled to state: the universe *is* as truly as I am--though in
+a somewhat different sense of “being”--and I *am* as truly as the
+universe is; but I am not entitled to state anything beyond these
+two corresponding phrases. You know that, in the history of European
+philosophy at least, Bishop Berkeley was the first clearly to outline
+the field of idealism.
+
+But my phenomenon--the world, especially nature--consists of elements
+of two different kinds: some of them are merely passive, some of them
+contain a peculiar sort of activity in themselves. The first are
+generally called sensations, but perhaps would be better called elements
+or presentations; the others are forms of construction, and, indeed,
+there is an active element embraced in them in this sense, that they
+allow, by their free combination, the discovery of principles which
+are not to be denied, which must be affirmed, whenever their meaning
+is understood. You know that I am speaking here of what are generally
+called categories and synthetic judgments *a priori*, and that it was
+Kant who, on the foundations laid by Locke, Hume, and Leibnitz, first
+gave the outlines of what may be called the real system of critical
+philosophy. Indeed, our method will be to a great extent Kantian, though
+with certain exceptions; it is to be strictly idealistic, and will not
+in the Kantian way operate with things in themselves; and it regards
+the so-called “synthetic judgment *a priori*” and the problem of the
+relation between categorical principles and experience in a somewhat
+different manner. We think it best to define the much disputed concept
+“*a priori*” as “independent of the *amount* of experience”; that is
+to say, all categories and categorical principles are brought to my
+consciousness by that fundamental event which is called experience, and
+therefore are not independent of it, but they are not inferences from
+experience, as are so-called empirical laws. We almost might say that we
+only have to be reminded of those principles by experience, and, indeed,
+we should not, I think, go very far wrong in saying that the Socratic
+doctrine, that all knowledge is recollection, holds good as far as
+categories and categorical principles are in question.
+
+But enough at present about our general philosophy.
+
+As to the philosophy of nature, there can be no doubt that, on the basis
+of principles like those we have shortly sketched, its ultimate aim must
+be to co-ordinate everything in nature with terms and principles of the
+categorical style. The philosophy of nature thus becomes a system; a
+system of which the general type is afforded by the innate constructive
+power of the Ego. In this sense the Kantian dictum remains true, that
+the Ego prescribes its own laws to nature, though, of course, “nature,”
+that is, what is given in space, must be such as to permit that sort of
+“prescription.”
+
+One often hears that all sciences, including the science of sciences,
+philosophy, have to find out what is true. What, then, may be called
+“true” by an idealistic philosopher, for whom the old realistic formula
+of the conformity between knowledge and the object cannot have any
+meaning? Besides its ordinary application to simple facts or to simple
+judgments, where the word truth only means absence of illusion or no
+false statement, truth can be claimed for a philosophical doctrine or
+for a system of such doctrines only in the sense that there are no
+contradictions amongst the parts of the doctrine or of the system
+themselves, and that there are no features in them which impel our
+categorical Ego to further analysis.
+
+Those of you who attended Professor Ward’s lectures on “Naturalism and
+Agnosticism,” or who have read his excellent book on that subject, will
+know what the aims of a theory of matter are. You will also be aware
+that, at present, there does not exist any theory of matter which can
+claim to be “true”; there are contradictions in every theory of matter,
+and, moreover, there are always some points where we are obliged to ask
+for further information and receive no answer. Experience here has not
+yet aroused all the categorical functions which are needed in order to
+form one unity out of what seem to be incompatibilities at the present
+day. Why is that? Maybe because experience is not yet complete in this
+field, but maybe also because the whole subject is so complicated
+that it takes much time to attach categorical functions to what is
+experienced.
+
+But it is not our object here to deal either with epistemology proper
+or with ontology: a full analysis of biological facts is our problem.
+Why, then, all these introductions? why all these philosophical sketches
+in fields of knowledge which have quite another relation to philosophy
+than biology has? Biology, I hear some one say, is simply and solely
+an empirical science; in some sense it is nothing but applied physics
+and chemistry, perhaps applied mechanics. There are no fundamental
+principles in biology which could bring it in any close contact with
+philosophy. Even the one and only principle which might seem to be
+an innate principle of our experience about life, the principle of
+evolution, is only a combination of more simple factors of the physical
+and chemical type.
+
+It will be my essential endeavour to convince you, in the course of
+these lectures, that such an aspect of the science of biology is wrong;
+that biology is an elemental natural science in the true sense of the
+word.
+
+But if biology is an elemental science, then, and only then, it stands
+in close relations to epistemology and ontology--in the same relations
+to them, indeed, as every natural science does which deals with true
+elements of nature, and which is willing to abandon naïve realism and
+contribute its share to the whole of human knowledge.
+
+And, therefore, a philosophical sketch is not out of place at the
+beginning of lectures on the Philosophy of the Organism. We may be
+forced, we, indeed, shall be forced, to remain for some time on the
+ground of realistic empiricism, for biology has to deal with very
+complicated experiences; but there will be a moment in our progress when
+we shall enter the realm of the elemental ontological concepts, and
+in that very moment our study of life will have become a part of real
+philosophy. It was not without good reasons, therefore, that I shortly
+sketched, as a sort of introduction to my lectures, the general point of
+view which we shall take with regard to philosophical questions, and to
+questions of the philosophy of nature in particular.
+
+
+ON CERTAIN CHARACTERISTICS OF BIOLOGY AS A SCIENCE
+
+Biology is the science of life. Practically, all of you know what a
+living being is, and therefore it is not necessary to formulate a
+definition of life, which, at the beginning of our studies, would be
+either provisional and incomplete, or else dogmatic. In some respects,
+indeed, a definition should rather be the end of a science than its
+opening.
+
+We shall study the phenomena of living organisms analytically, by the
+aid of experiment; our principal object will be to find out laws in
+these phenomena; such laws will then be further analysed, and precisely
+at that point we shall leave the realm of natural science proper.
+
+Our science is the highest of all natural sciences, for it embraces as
+its final object the actions of man, at least in so far as actions also
+are phenomena observable on living bodies.
+
+But biology is also the most difficult of all natural sciences, not
+only from the complexity of the phenomena, which it studies, but in
+particular for another reason which is seldom properly emphasised, and
+therefore will well repay us for a few words devoted to it.
+
+Except so far as the “elements” of chemistry come into account, the
+experimenter in the inorganic fields of nature is not hampered by the
+specificity of composite objects: he makes all the combinations he
+wants. He is always able to have at his disposal red rays of a desired
+wave length when and where he wants, or to have, at a given time and
+place, the precise amount of any organic compound which he wishes to
+examine. And he forces electricity and electromagnetism to obey his
+will, at least with regard to space, time, and intensity of their
+appearance.
+
+The biologist is not able to “make” life, as the physicist has made red
+rays or electromagnetism, or as the chemist has made a certain compound
+of carbon. The biologist is almost always in that strange plight in
+which the physicist would be if he always had to go to volcanoes in
+order to study the conductivity of heat, or if he had to wait for
+thunderstorms in order to study electricity. The biologist is dependent
+on the specificity of living objects as they occur in nature.
+
+A few instances may show you what great inconveniences may hence arise
+to impede practical biological research. We later on shall have to deal
+with experiments on very young embryos: parts of the germ will have
+to be destroyed in order to study what will happen with the rest. Now
+almost all germs are surrounded by a membrane; this membrane has to be
+detached before any operation is possible. But what are we to do if it
+is not possible to remove the membrane without killing the embryo? Or
+what if, as for instance in many marine animals, the membrane may be
+removed but the germs are killed by contact with sea-water? In both
+cases no experiments at all will be possible on a sort of germ which
+otherwise, for some special circumstances of its organisation, might
+have given results of importance. These results become impossible for
+only a practical, for a very secondary reason; but enough: they are
+impossible, and they might have thrown light on problems which now
+must remain problems. Quite the same thing may occur in experiments
+on physiology proper or functional physiology: one kind of animals
+survives the operation, the other kind does not, and therefore, for
+merely extrinsic reasons, the investigations have to be restricted to
+the first, though the second might have given more important results.
+And thus the biological experimenter always finds himself in a sort of
+dependence on his subjects, which can hardly be called pleasant. To a
+great extent the comparatively slow advance of biological sciences is
+due to this very fact: the unalterable specific nature of biological
+material.
+
+But there is still another feature of biology dependent on the same
+fact. If a science is tied down to specific objects in every path it
+takes, it first, of course, has to know all about those objects, and
+that requires nothing else but plain description. We now understand why
+pure description, in the most simple sense of the word, takes up such an
+enormous part of every text-book of biological science. It is not only
+morphology, the science of form, that is most actively concerned with
+description; physiology also, in its present state, is pure description
+of what the functions of the different parts of the body of animals and
+plants actually *are*, at least for about nine-tenths of its range. It
+seems to me important to press this point very emphatically, since we
+often hear that physiology is from the very beginning a much higher sort
+of knowledge than morphology, inasmuch as it is rational. That is not at
+all true of the beginning of physiology: what the functions of the liver
+or of the root are has simply to be described just as the organisation
+of the brain or of the leaf, and it makes no difference logically that
+one species of description has to use the experimental method, while the
+other has not. The experiment which only discovers what happens here or
+what happens there, possesses no kind of logical superiority over pure
+description at all.
+
+But there will be another occasion in our lectures to deal more fully
+with the logic of experiment and with the differences of descriptive
+knowledge and real rational science.
+
+
+THE THREE DIFFERENT TYPES OF KNOWLEDGE ABOUT NATURE
+
+Natural sciences cannot originate before the given phenomena of nature
+have been investigated in at least a superficial and provisional manner,
+by and for the practical needs of man. But as soon as true science
+begins in any limited field, dealing, let us say, with animals or with
+minerals, or with the properties of bodies, it at once finds itself
+confronted by two very different kinds of problems, both of them--like
+all “problems”--created in the last resort by the logical organisation
+of the human mind, or, to speak still more correctly, of the Ego.
+
+In any branch of knowledge which practical necessities have separated
+from others, and which science now tries to study methodically, there
+occur general sequences in phenomena, general orders of events. This
+uniformity is revealed only gradually, but as soon as it has shown
+itself, even in the least degree, the investigator seizes upon it. He
+now devotes himself chiefly, or even exclusively, to the generalities in
+the sequences of all changes. He is convinced that there must be a sort
+of most general and at the same time of most universal connection about
+all occurrences. This most universal connection has to be found out; at
+least it will be the ideal that always will accompany the inquiring mind
+during its researches. The “law of nature” is the ideal I am speaking
+about, an ideal which is nothing less than one of the postulates of the
+possibility of science at all.
+
+Using for our purposes a word which has been already introduced into
+terminology by the philosopher Windelband, though in a somewhat
+different sense, we shall call that part of every branch of natural
+sciences which regards the establishment of a law of nature as its
+ideal, “nomothetic,” *i.e.* “law-giving.”
+
+But while every natural science has its nomothetic side, it also has
+another half of a very different kind. This second half of every natural
+science does not care for the same general, the same universal, which
+is shown to us in every event in a different and specified kind: it
+is diversity, it is specification, that constitutes the subject of
+its interest. Its aim is to find a sufficient reason for the types of
+diversities, for the types of specifications. So in chemistry there
+has been found a systematic order in the long series of the compounds
+and of the elements; crystallography also has its different systems of
+crystals, and so on.
+
+We have already employed the word by which we shall designate this
+second half of every natural science: it is the “systematic” side of
+science.
+
+Nomothetic work on the one side and systematics on the other do, in
+fact, appear in every natural science, and besides them there are no
+other main parts. But “science” as a whole stands apart from another
+aspect of reality which is called “history.” History deals with
+particulars, with particular events at such and such a place, whilst
+science always abstracts from the particular, even in its systematic
+half.[1]
+
+[1] Windelband (*Geschichte und Naturwissenschaft*, 3 Auflage, 1904)
+gives the name “nomothetic” to the whole of our “science” and calls the
+method of history “idiographic.” We thought it better to establish three
+fundamental types of all possible branches of knowledge.
+
+
+GENERAL PLAN OF THESE LECTURES
+
+Turning now to a sort of short outline of what is to be discussed
+in the whole of our future lectures, this summer and next, it seems
+clear, without further analysis, that biology as a science has its
+nomothetic and its systematic part also; respiration and assimilation,
+for instance, have proved to be types of natural laws among living
+phenomena, and that there is a “system” of animals and plants is too
+commonly known to require further explanation here. Therefore we might
+study first biological laws, and after that biological systematics, and
+in the third place perhaps biological history. But that would hardly
+correspond to the philosophical aims of our lectures: our chief object
+is not biology as a regular science, as treated in text-books and in
+ordinary university lectures; our chief object is the Philosophy of the
+Organism, as aided and supported by scientific biology. Therefore a
+general acquaintance with biology must be assumed in these lectures, and
+the biological materials must be arranged according to their bearing on
+further, that is on philosophical, analysis.
+
+That will be done, not, of course, to the extent of my regarding every
+one of my audience as a competent biologist; on the contrary, I shall
+explain most fully all points of biology proper, and even of the most
+simple and descriptive kind of biology, which serve as bases for
+philosophical analysis. But I shall do so only if they indeed do serve
+as such bases. All our biology will be not for its own sake, but for the
+sake of philosophy.
+
+Whilst regarding the whole of the biological material with such aims,
+it seems to me best to arrange the properly scientific material which
+is to be the basis of my discussions, not along the lines which biology
+as an independent science would select,[2] but to start from the three
+different kinds of fundamental phenomena which living bodies offer to
+investigation, and to attach all systematics exclusively to one of them.
+For there will not be very much for philosophy to learn from biological
+systematics at present.
+
+[2] See J. Arth. Thomson, *The Science of Life*, London, 1899.
+
+Life is unknown to us except in association with bodies: we only know
+living bodies and call them organisms. It is the final object of all
+biology to tell us what it ultimately means to say that a body is
+“living,” and in what sorts of relation body and life stand one to the
+other.
+
+But at present it is enough to understand the terms “body” and “living”
+in the ordinary and popular sense.
+
+Regarding living bodies in this unpretentious manner, and recollecting
+what the principal characters are of all bodies we know as living ones,
+we easily find that there are three features which are never wanting
+wherever life in bodies occurs. All living bodies are specific as to
+form--they “have” a specific form, as we are accustomed to say. All
+living bodies also exhibit metabolism; that is to say, they stand in a
+relation of interchange of materials with the surrounding medium, they
+take in and give out materials, but their form can remain unchanged
+during these processes. And, in the last place, we can say that all
+living bodies move; though this faculty is more commonly known among
+animals only, even elementary science teaches the student that it also
+belongs to plants.
+
+Therefore we may ask for “laws of nature” in biology about form, about
+metabolism, and about movements. In fact, it is according to this scheme
+that we shall arrange the materials of the biological part of our
+lectures, though, as we cannot regard the three divisions as equally
+important in their bearing on our ultimate purposes, we shall not treat
+them quite on equal terms. It will appear that, at least in the present
+state of science, the problems of organic form and of organic movement
+have come into much closer relation to philosophical analysis than have
+most of the empirical data on metabolism.
+
+It is *form* particularly which can be said to occupy the very centre
+of biological interest; at least it furnishes the foundation of all
+biology. Therefore we shall begin our scientific studies with a full and
+thorough analysis of form. The science of living forms, later on, will
+afford us a key to study metabolism proper with the greatest advantage
+for our philosophical aims, and therefore the physiology of what is
+usually called the vegetative functions will be to us a sort of appendix
+to our chapters on form; only the theory of a problematic “living
+substance” and of assimilation in the most general meaning of the word
+will be reserved for the philosophical part; for very good reasons,
+as I hope to show. But our chapters on the living forms will have yet
+another appendix besides the survey of the physiology of metabolism.
+Biological systematics almost wholly rests on form, on “morphology”; and
+what hitherto has been done on the metabolical side of their problems,
+consists of a few fragments, which are far from being an equivalent to
+the morphological system; though, of course it must be granted that,
+logically, systematics, in our general meaning of the word, as the sum
+of problems about the typically different and the specific, may be
+studied on the basis of each one of the principal characteristics of
+living bodies, not only on that of their forms. Therefore, systematics
+is to be the second appendix to the chief part of our studies in
+morphology, and systematics, in its turn, will later on lead us to
+a short sketch of the historical side of biology, to the theory of
+evolution in its different forms, and to the logic of history in general.
+
+So far will our programme be carried out during this summer. Next year
+the theory of movements will conclude our merely scientific analysis,
+and the remaining part of the course next summer will be devoted to the
+philosophy of living nature. I hope that nobody will be able to accuse
+our philosophy of resting on unsound foundations. But those of you, on
+the other hand, who would be apt to regard our scientific chapters as a
+little too long compared with their philosophical results, may be asked
+to consider that a small clock-tower of a village church is generally
+less pretentious but more durable than the campanile of San Marco has
+been.
+
+Indeed, these lectures will afford more “facts” to my hearers, than
+Gifford Lectures probably have done, as a rule. But how could that
+be otherwise on the part of a naturalist? Scientific facts are the
+material that the philosophy of nature has to work with, but these
+facts, unfortunately, are not as commonly known as historical facts,
+for instance, generally are; and they must be known, in order that a
+philosophy of the organism may be of any value at all, that it may be
+more than a mere entertainment.
+
+Goethe once said, that even in so-called facts there is more “theory”
+than is usually granted; he apparently was thinking of what might be
+called the ultimate or the typical facts in science. It is with such
+typical or ultimate facts, of course, that we must become acquainted if
+our future philosophy is to be of profit to us.
+
+Certainly, there would be nothing to prevent us from arranging our
+materials in a manner exactly the reverse of that which we shall adopt;
+we could begin with a general principle about the organic, and could
+try to deduce all its special features from that principle, and such a
+way perhaps would seem to be the more fascinating method of argument.
+But though logical it would not be psychological, and therefore would
+be rather unnatural. And thus our *most* general principle about the
+organic will not come on the scene before the eighteenth of these twenty
+lectures, although it is not a mere inference or deduction from the
+former lectures: it will be a culmination of the whole, and we shall
+appreciate its value the better the more we know what that whole really
+is.
+
+
+GENERAL CHARACTER OF THE ORGANIC FORM
+
+Our programme of this year, it was said, is to be devoted wholly
+to organic forms, though one of its appendixes, dealing with some
+characteristics of the physiology of metabolism, will lead us on to a
+few other phenomena. What then are the essentials of a living form, as
+commonly understood even without a special study of biology?
+
+Living bodies are not simple geometrical forms, not, like crystals,
+merely a typical arrangement of surfaces in space, to be reduced
+theoretically, perhaps, to an arrangement of molecules. Living bodies
+are typically combined forms; that is to say, they consist of simpler
+parts of different characters, which have a special arrangement with
+regard to one another; these parts have a typical form of their own and
+may again be combinations of more simple different parts. But besides
+that, living bodies have not always the same typically combined form
+during the whole of their life: they become more complicated as they
+grow older; they all begin from one starting point, which has little
+form at all, viz., the egg. So the living form may be called a “genetic
+form,” or a form considered as a process, and therefore *morphogenesis*
+is the proper and adequate term for the science which deals with the
+laws of organic forms in general; or, if you prefer not to use the
+same word both for a science and for the subjects of that science, the
+*physiology of morphogenesis*.
+
+Now there are different branches of the physiology of morphogenesis or
+physiology of form. We may study, and indeed we at first shall study,
+what are the laws of the morphogenetic processes leading from the egg
+to the adult: that may be properly called physiology of development.
+But living forms are not only able to originate in one unchangeable
+way: they may restore themselves, if disturbed, and thus we get the
+physiology of restoration or restitution as a second branch of the
+science of morphogenesis. We shall draw very important data, some of the
+foundations indeed of our philosophical discussions, from the study of
+such restitutions. Besides that, it is to them that our survey of the
+problems of the physiology of metabolism is to be appended.
+
+Living forms not only originate from the egg and are able to restore
+themselves, they also may give origin to other forms, guaranteeing in
+this way the continuity of life. The physiology of heredity therefore
+appears as the counterpart to those branches of the physiology of form
+which deal with individual form and its restitutions. And our discussion
+on heredity may be followed by our second appendix to this chief section
+on form, an appendix regarding the outlines of systematics, evolution
+and history.
+
+Theoretical considerations on biology generally start, or at least,
+used to start, from the evolution theory, discussing all other problems
+of the physiology of form by the way only, as things of secondary
+importance. You see from our programme, that we shall go just the
+opposite way: evolution will come last of all, and will be treated
+shortly; but the morphogenesis of the individual will be treated very
+fully, and very carefully indeed.
+
+Why then this deviation from what is the common practice? Because we do
+not know very much about evolution at all, because in this field we are
+just at the very beginning of what deserves the name of exact knowledge.
+But concerning individual morphogenesis we really know, even at present,
+if not very much, at least something, and that we know in a fairly exact
+form, aided by the results of experiments.
+
+And it will not be without its reward, if we restrict our aims in such a
+manner, if we prefer to deal more fully with a series of problems, which
+may seem at the first glance to be of less interest than others. After a
+few lectures we shall find already that we may decide one very important
+question about life merely by an analysis of individual form production,
+and without any regard to problematic and doubtful parts of biology:
+that we may decide the question, whether “life” is only a combination
+of chemical and physical events, or whether it has its elemental laws,
+laws of its own.
+
+But to prepare the road that is to lead to such results we first have
+to restrict our aims once more, and therefore the next lecture of this
+course, which eventually is to touch almost every concept of philosophy
+proper, will begin with the pure description of the individual
+development of the common sea-urchin.
+
+
+
+
+SECTION A
+
+THE CHIEF RESULTS OF ANALYTICAL BIOLOGY
+
+
+
+
+PART I
+
+THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM
+
+*A.* ELEMENTARY MORPHOGENESIS
+
+
+EVOLUTIO AND EPIGENESIS IN THE OLD SENSE
+
+The organism is a specific body, built up by a typical combination
+of specific and different parts. It is implied in the words of this
+definition, that the organism is different, not only from crystals, as
+was mentioned in the last lecture, but also from all combinations of
+crystals, such as those called dendrites and others, which consist of a
+typical arrangement of identical units, the nature of their combination
+depending on the forces of every single one of their parts. For this
+reason dendrites, in spite of the typical features in their combination,
+must be called aggregates; but the organism is not an aggregate even
+from the most superficial point of view.
+
+We have said before, what must have been familiar to you already, that
+the organism is not always the same in its individual life, that it
+has its development, leading from simpler to more complicated forms of
+combination of parts; there is a “production of visible manifoldness”
+carried out during development, to describe the chief character of that
+process in the words of Wilhelm Roux. We leave it an open question in
+our present merely descriptive analysis, whether there was already a
+“manifoldness,” in an invisible state, before development, or whether
+the phrase “production of manifoldness” is to be understood in an
+absolute sense.
+
+It has not always been granted in the history of biology, and of
+embryology especially, that production of visible manifoldness is the
+chief feature of what is called an organism’s embryology or ontogeny:
+the eighteenth century is full of determined scientific battles over the
+question. One school, with Albert von Haller and Bonnet as its leading
+men, maintained the view that there was no production of different parts
+at all in development, this process being a mere “evolutio,” that is,
+a growth of parts already existing from the beginning, yes, from the
+very beginning of life; whilst the other school, with C. F. Wolff and
+Blumenbach at its head, supported the opposite doctrine of so-called
+“epigenesis,” which has been proved to be the right one.
+
+To some extent these differences of opinion were only the outcome of the
+rather imperfect state of the optical instruments of that period. But
+there were also deeper reasons beyond mere difficulties of description;
+there were theoretical convictions underlying them. It is *impossible*,
+said the one party, that there is any real production of new parts;
+there *must* be such a production, said the other.
+
+We ourselves shall have to deal with these questions of the theory of
+organic development; but at present our object is narrower, and merely
+descriptive. It certainly is of great importance to understand most
+clearly that there actually *is* a “production of visible manifoldness”
+during ontogenesis in the descriptive sense; the knowledge of the fact
+of this process must be the very foundation of all studies on the theory
+of development in any case, and therefore we shall devote this whole
+lecture to studies in merely descriptive embryology.
+
+But descriptive embryology, even if it is to serve merely as an
+instance of the universality of the fact of epigenesis, can only be
+studied successfully with reference to a concrete case. We select the
+development of the common sea-urchin (*Echinus microtuberculatus*) as
+such a case, and we are the more entitled to select this organism rather
+than another, because most of the analytical experimental work, carried
+out in the interests of a real theory of development, has been done
+on the germs of this animal. Therefore, to know at least the outlines
+of the individual embryology of the Echinus may indeed be called the
+*conditio sine qua non* for a real understanding of what is to follow.
+
+
+THE CELL[3]
+
+[3] E. B. Wilson, *The Cell in Development and Inheritance*, New York,
+Macmillan, 1896.
+
+You are aware that all organisms consist of organs and that each of
+their organs has a different function: the brain, the liver, the eyes,
+the hands are types of organs in animals, as are the leaves and the
+pistils in plants.
+
+You are also aware that, except in the lowest organisms, the so-called
+Protista, all organs are built up of cells. That is a simple fact of
+observation, and I therefore cannot agree with the common habit of
+giving to this plain fact the title of cell-“theory.” There is nothing
+theoretical in it; and, on the other hand, all attempts to conceive
+the organism as a mere aggregate of cells have proved to be wrong. It
+is *the whole* that uses the cells, as we shall see later on, or that
+may not use them: thus there is nothing like a “cell-theory,” even in a
+deeper meaning of the word.
+
+The cell may have the most different forms: take a cell of the skin, of
+a muscle, of a gland, of the wood in plants as typical examples. But in
+every case two parts may be distinguished in a cell: an outside part,
+the protoplasm, and an inside part, the nucleus, to leave out of special
+account several others, which, by the way, may only be protoplasmatic
+modifications.
+
+Protoplasm is a mere name for what is not the nucleus; in any case it is
+not a homogeneous chemical compound; it consists of many such compounds
+and has a sort of architecture; all organic functions are based upon
+its metabolism. The nucleus has a very typical structure, which stands
+in a close relation to its behaviour during the most characteristic
+morphological period of the cell: during its division. Let us devote a
+few words to a consideration of this division and the part the nucleus
+plays in it; it will directly bear on future theoretical considerations
+about development.
+
+There is a certain substance in every nucleus of a cell which stains
+most markedly, whenever cells are treated with pigments: the name
+of “chromatin” has been given to it. The chromatin always gives the
+reaction of an acid, while protoplasm is basic; besides that it seems to
+be a centre of oxidation. Now, when a division of a cell is to occur,
+the chromatin, which had been diffusely distributed before, in the form
+of small grains, arranges itself into a long and very much twisted
+thread. This thread breaks, as it were by sections, into almost equal
+parts, typical in number for each species, and each of these parts is
+split at full length. A certain number of pairs of small threads, the
+so-called “chromosomes,” are the ultimate result of this process, which
+intentionally has been described a little schematically, the breaking
+and the splitting in fact going on simultaneously or occasionally even
+in reverse order. While what we have described is performing in the
+nucleus, there have happened some typical modifications in protoplasm,
+and then, by an interaction of protoplasmatic and nuclear factors, the
+first step in the actual division of the cell begins. Of each pair of
+the small threads of chromatin one constituent is moved to one side of
+the cell, one to the other; two daughter-nuclei are formed in this way;
+the protoplasm itself at the same time forms a circular furrow between
+them; the furrow gets deeper and deeper; at last it cuts the cell in
+two, and the division of the cell is accomplished.
+
+Not only is the growth of the already typically formed organism carried
+out by a series of cell-divisions, but also development proper in our
+sense, as a “production of visible manifoldness,” is realised to a great
+extent by the aid of such divisions, which therefore may indeed be said
+to be of very fundamental importance (Fig. 1).
+
+[Illustration: Fig. 1.--Diagram of Cell-Division (*after* Boveri).
+
+*a.* Resting cell; the chromatin distributed in the form of small
+granules inside the nucleus. Outside the nucleus is the “centrosome,”
+not mentioned in the text.
+
+*b.* Beginning of division; the chromatin arranged in the form of a long
+thread. Centrosome divided in two.
+
+*c.* The thread of chromatin cut into four parts, the “chromosomes.”
+
+*d.* The four parts of the chromatin arranged symmetrically between the
+centrosomes and the star-like “spheres.”
+
+*e.* Each of the chromosomes split at full length.
+
+*f.* Beginning of division of protoplasm; the two parts of each
+chromosome separated.
+
+*g.* End of cell-division.]
+
+Each cell-division which promotes growth is followed by the
+enlargement of the two daughter-cells which result from it; these two
+daughter-elements attain the exact size of the mother-cell before
+division, and as soon as this size is reached a new division begins:
+so the growth of the whole is in the main the result of the growth of
+the elements. Cell-divisions during real organ-formation may behave
+differently, as will be described at a proper occasion.
+
+
+THE EGG: ITS MATURATION AND FERTILISATION
+
+We know that all the organs of an animal or plant consist of cells, and
+we know what acts a cell can perform. Now there is one very important
+organ in all living beings, which is devoted to reproduction. This
+organ, the so-called ovary in animals, is also built up of cells,
+and its single cells are called the eggs; the eggs originated by
+cell-division, and cell-division is to lead from them to the new adult.
+
+But, with a very few exceptions, the egg in the ovary is not able to
+accomplish its functions, unless certain typical events have occurred,
+some of which are of a merely preparatory kind, whilst the others are
+the actual stimulus for development.
+
+The preparatory ones are generally known under the name of “maturation.”
+The egg must be “mature,” in order that it may begin development, or
+even that it may be stimulated to it. Maturation consists of a rather
+complicated series of phenomena: later on we shall have occasion to
+mention, at least shortly, what happens in the protoplasm during its
+course; as to the nuclear changes during maturation it may be enough
+for our purposes to say, that there occur certain processes among the
+chromosomes, which lead to an extension of half of them in the form
+of two very small cells, the “directive cells” or “directive or polar
+bodies,” as they have been somewhat cautiously called.
+
+The ripe or mature egg is capable of being fertilised.
+
+Before turning to this important fact, which, by the way, will bring us
+to our specially chosen type, the Echinus, a few words may be devoted to
+the phenomenon of “parthenogenesis,” that is to say, the possibility
+of development without fertilisation, since owing to the brilliant
+discoveries of the American physiologist, Jacques Loeb, this topic forms
+one of the centres of biological interest at present. It has long been
+known that the eggs of certain bees, lice, crayfishes, and other animals
+and also plants, are capable of development without fertilisation at
+all. Now Richard Hertwig and T. H. Morgan already had shown, that at
+least nuclear division may occur in the eggs of other forms--in the egg
+of the sea-urchin for instance--when these eggs are exposed to some
+chemical injuries. But Loeb[4] succeeded in obtaining a full development
+by treating the eggs of echinoderms with chloride of magnesium; thus
+artificial parthenogenesis had been discovered. Later researches have
+shown that artificial parthenogenesis may occur in all classes of the
+animal kingdom and may be provoked by all sorts of chemical or physical
+means. We do not know at present in what the proper stimulus consists
+that must be supposed here to take the place of fertilisation; it seems,
+of course, highly probable that it is always the same in the last
+resort.[5]
+
+[4] *Amer. Journ. Physiol.* vols. iii. and iv. 1900.
+
+[5] According to Delage (*Arch. Zool. exp.*, 3 sér. 10, 1902), it is
+indifferent for the realisation of artificial parthenogenesis, whether
+but one, or both, or neither of the “polar bodies” has been formed. But
+the egg must be in the first stages of maturation to the extent that the
+“nuclear membrane” must be already dissolved.
+
+But enough about processes, which at present are of a highly scientific,
+but hardly of any philosophic interest.
+
+By fertilisation proper we understand the joining of the male element,
+the spermatozoon or the spermia, with the female element, the egg. Like
+the egg, the spermatozoon is but a cell, though the two differ very much
+from one another in the relation between their protoplasm and nucleus:
+in all eggs it is the protoplasm which is comparatively very large, if
+held together with somatic cells, in the spermatozoon it is the nucleus.
+A large amount of reserve material, destined for the growth of the
+future being, is the chief cause of the size of the egg-protoplasm. The
+egg is quite or almost devoid of the faculty of movement, while on the
+contrary, movement is the most typical feature of the spermia. Its whole
+organisation is adapted to movement in the most characteristic manner:
+indeed, most spermatozoa resemble a swimming infusorium, of the type
+of Flagellata, a so-called head and a moving tail are their two chief
+constituents; the head is formed almost entirely of nuclear substance.
+
+It seems that in most cases the spermatozoa swim around at random and
+that their union with the eggs is assured only by their enormous number;
+only in a few cases in plants have there been discovered special stimuli
+of a chemical nature, which attract the spermia to the egg.
+
+But we cannot enter here more fully into the physiology of
+fertilisation, and shall only remark that its real significance is by no
+means clear.[6]
+
+[6] The older theories, attributing to fertilisation (or to
+“conjugation,” *i.e.* its equivalent in Protozoa), some sort of
+“renovation” or “rejuvenescence” of the race, have been almost
+completely given up. (See Calkins, *Arch. für Entwickelungsmechanik*,
+xv. 1902). R. Hertwig recently has advocated the view, that abnormal
+relations between the amounts of nuclear and of protoplasmatic material
+are rectified in some way by those processes. Teleologically, sexual
+reproduction has been considered as a means of variability (Weismann),
+but also as a means of preserving the type!
+
+
+THE FIRST DEVELOPMENT PROCESS OF ECHINUS
+
+Turning now definitively to the special kind of organism, chosen of our
+type, the common sea-urchin, we properly begin with a few words about
+the absolute size of its eggs and spermatozoa. All of you are familiar
+with the eggs of birds and possibly of frogs; these are abnormally
+large eggs, on account of the very high amount of reserve material they
+contain. The almost spherical egg of our Echinus only measures about a
+tenth of a millimetre in diameter; and the head of the spermatozoon has
+a volume which is only the four-hundred-thousandth part of the volume
+of the egg! The egg is about on the extreme limit of what can be seen
+without optical instruments; it is visible as a small white point. But
+the number of eggs produced by a single female is enormous and may
+amount to hundreds of thousands; this is one of the properties which
+render the eggs of Echinus so very suitable for experimental research;
+you can obtain them whenever and in any quantity you like; and,
+moreover, they happen to be very clear and transparent, even in later
+stages, and to bear all kinds of operations well.
+
+The spermia enters the egg, and it does so in the open water--another
+of the experimental advantages of our type. Only one spermia enters
+the egg in normal cases, and only its head goes in, the tail is left
+outside. The moment that the head has penetrated the protoplasm of the
+egg a thin membrane is formed by the latter. This membrane is very soft
+at first, becoming much stronger later on; it is very important for all
+experimental work, that by shaking the egg in the first minutes of its
+existence the membrane can easily be destroyed without any damage to the
+egg itself.
+
+And now occurs the chief phenomenon of fertilisation: the nucleus of
+the spermatozoon unites with the nucleus of the egg. When speaking of
+maturation, we mentioned that half of the chromatin was thrown out of
+the egg by that process: now this half is brought in again, but comes
+from another individual.
+
+It is from this phenomenon of nuclear union as the main character of
+fertilisation that almost all theories of heredity assume their right to
+regard the nuclei of the sexual cells as the true “seat” of inheritance.
+Later on we shall have occasion to discuss this hypothesis from the
+point of view of logic and fact.
+
+After the complete union of what are called the male and the female
+“pronuclei,” the egg begins its development; and this development, in
+its first steps, is simply pure cell-division. We know already the chief
+points of this process, and need only add to what has been described,
+that in the whole first series of the cell-divisions of the egg, or,
+to use the technical term, in the whole process of the “cleavage” or
+“segmentation” of it, there is never any growth of the daughter-elements
+after each division, such as we know to occur after all cell-divisions
+of later embryological stages. So it happens, that during cleavage the
+embryonic cells become smaller and smaller, until a certain limit is
+reached; the sum of the volumes of all the cleavage cells together is
+equal to the volume of the egg.
+
+But our future studies will require a more thorough knowledge of the
+cleavage of our Echinus; the experimental data we shall have to describe
+later on could hardly be properly understood without such knowledge.
+The first division plane, or, as we shall say, the first cleavage
+plane, divides the eggs into equal parts; the second lies at right
+angles to the first and again divides equally: we now have a ring of
+four cells. The third cleavage plane stands at right angles to the
+first two; it may be called an equatorial plane, if we compare the egg
+with a globe; it also divides equally, and so we now find two rings,
+each consisting of four cells, and one above the other. But now the
+cell-divisions cease to be equal, at least in one part of the egg: the
+next division, which leads from the eight- to the sixteen-cell stage of
+cleavage, forms four rings, of four cells each, out of the two rings of
+the eight-cell stage. Only in one half of the germ, in which we shall
+call the upper one, or which we might call, in comparison with a globe,
+the northern hemisphere, are cells of equal size to be found; in the
+lower half of the egg four very small cells have been formed at one
+“pole” of the whole germ. We call these cells the “micromeres,” that
+is, the “small parts,” on the analogy of the term “blastomeres,” that
+is, parts of the germ, which is applied to all the cleavage cells in
+general. The place occupied by the micromeres is of great importance
+to the germ as a whole: the first formation of real organs will start
+from this point later on. It is sufficient thus fully to have studied
+the cleavage of our Echinus up to this stage: the later cleavage stages
+may be mentioned more shortly. All the following divisions are into
+equal parts; there are no other micromeres formed, though, of course,
+the cells derived from the micromeres of the sixteen-cell stage always
+remain smaller than the rest. All the divisions are tangential; radial
+cleavages never occur, and therefore the process of cleavage ends at
+last in the formation of one layer of cells, which forms the surface
+of a sphere; it is especially by the rounding-up of each blastomere,
+after its individual appearance, that this real surface layer of cells
+is formed, but, of course, the condition, that no radial divisions
+occur, is the most important one in its formation. When 808 blastomeres
+have come into existence the process of cleavage is finished; a sphere
+with a wall of cells and an empty interior is the result. That only 808
+cells are formed, and not, as might be expected, 1024, is due to the
+fact that the micromeres divide less often than the other elements; but
+speaking roughly, of course, we may say that there are ten steps of
+cleavage-divisions in our form; 1024 being equal to 2^{10}.
+
+We have learned that the first process of development, the cleavage, is
+carried out by simple cell-division. A few cases are known, in which
+cell-division during cleavage is accompanied by a specific migration of
+parts of the protoplasm in the interior of the blastomeres, especially
+in the first two or first four; but in almost all instances cleavage
+is as simple a process of mere division as it is in our sea-urchin.
+Now the second step in development, at least in our form, is a typical
+histological performance: it gives a new histological feature to all
+of the blastomeres: they acquire small cilia on their outer side and
+with these cilia the young germ is able to swim about after it has left
+its membrane. The germ may be called a “blastula” at this stage, as it
+was first called by Haeckel, whose useful denominations of the first
+embryonic stages may conveniently be applied, even if one does not agree
+with most, or perhaps almost all, of his speculations (Fig. 2).
+
+[Illustration: Fig. 2.--Early Development of Echinus, the Common
+Sea-urchin.
+
+*a.* Two cells.
+
+*b.* Four cells.
+
+*c.* Eight cells, arranged in two rings of four, above one another.
+
+*d.* Sixteen cells, four “micromeres” formed at the “vegetative” pole.
+
+*e.* Optical section of the “blastula,” a hollow sphere consisting of
+about one thousand cells, each of them with a small cilium.]
+
+It is important to notice that the formation of the “blastula” from the
+last cleavage stage is certainly a process of organisation, and may also
+be called a differentiation with regard to that stage. But there is in
+the blastula no trace of one *part* of the germ becoming different with
+respect to others of its parts. If development were to go on in this
+direction alone, high organisatory complications might occur: but there
+would always be only one sort of cells, arranged in a sphere; there
+would be only one kind of what is called “tissue.”
+
+But in fact development very soon loads to true differences of the
+parts of the germ with respect to one another, and the next step of the
+process will enable us to apply different denominations to the different
+parts of the embryo.
+
+At one pole of the swimming blastula, exactly at the point where the
+descendants of the micromeres are situated, about fifty cells lose
+contact with their neighbours and leave the surface of the globe, being
+driven into the interior space of it. Not very much is known about the
+exact manner in which these changes of cellular arrangement are carried
+out, whether the cells are passively pressed by their neighbours, or
+whether, perhaps, in a more active manner, they change their surface
+conditions; therefore, as in most ontogenetic processes, the description
+had best be made cautiously in fairly neutral or figurative words.
+
+The cells which in the above manner have entered the interior of the
+blastula are to be the foundation of important parts of the future
+organism; they are to form its connective tissue, many of its muscles,
+and the skeleton. “Mesenchyme,” *i.e.* “what has been infused into the
+other parts,” is the technical name usually applied to these cells.
+We now have to learn their definite arrangement. At first they lie
+as a sort of heap inside the cell wall of the blastula, inside the
+“blastoderm,” *i.e.* skin of the germ. But soon they move from one
+another, to form a ring round the pole at which they entered, and on
+this ring a process takes place which has a very important bearing upon
+the whole type of the organisation of the germ. You will have noticed
+that hitherto the germ with regard to its symmetry has been a monaxial
+or radial formation; the cleavage stages and the blastula with its
+mesenchyme were forms with two different poles, lying at the ends of one
+single line, and round this line everything was arranged concentrically.
+But now what is called “bilateral symmetry” is established; the
+mesenchyme ring assumes a structure which can be symmetrically divided
+only by one plane, but divided in such a way, that one-half of it is the
+mirror image of the other. A figure shows best what has occurred, and
+you will notice (Fig. 3) two masses of cells in this figure, which have
+the forms of spherical triangles: it is in the midst of these triangles
+that the skeleton of the larva *originates*. The germ had an upper and
+a lower side before: it now has got an upper and lower, front and back,
+*right and left* half; it now has acquired that symmetry of organisation
+which our own body has; at least it has got it as far as its mesenchyme
+is concerned.
+
+[Illustration: Fig. 3.--Formation of Mesenchyme in Echinus.
+
+*a.* Outlines of blastula, side-view; mesenchyme forms a heap of cells
+at the “vegetative” pole.
+
+*a*_1. Heap of mesenchyme-cells from above.
+
+*b.* Mesenchyme-cells arranged in a ring round the vegetative pole.
+
+*c.* Mesenchyme-cells arranged in a bilateral-symmetrical figure;
+primordia of skeleton in the midst of two spherical triangles.]
+
+We leave the mesenchyme for a while and study another kind of
+organogenesis. At the very same pole of the germ where the mesenchyme
+cells originated there is a long and narrow tube of cell growing in,
+and this tube, getting longer and longer, after a few hours of growth
+touches the opposite pole of the larva. The growth of this cellular tube
+marks the beginning of the formation of the intestine, with all that
+is to be derived from it. The larva now is no longer a blastula, but
+receives the name of “gastrula” in Haeckel’s terminology; it is built
+up of the three “germ-layers” in this stage. The remaining part of the
+blastoderm is called “ectoderm,” or outer layer; the newly-formed tube,
+“endoderm,” or inner layer; while the third layer is the “mesenchyme”
+already known to us.
+
+The endoderm itself is a radial structure at first, as was the whole
+germ in a former stage, but soon its free end bends and moves against
+one of the sides of the ectoderm, against that side of it where the two
+triangles of the mesenchyme are to be found also. Thus the endoderm
+has acquired bilateral symmetry just as the mesenchyme before, and
+as in this stage the ectoderm also assumes a bilateral symmetry
+in its form, corresponding with the symmetrical relations in the
+endoderm and the mesenchyme, we now may call the whole of our larva a
+bilateral-symmetrical organisation.
+
+It cannot be our task to follow all the points of organogenesis of
+Echinus in detail. It must suffice to state briefly that ere long a
+second portion of the mesenchyme is formed in the larva, starting from
+the free end of its intestine tube; that the formation of the so-called
+“coelum” occurs by a sort of splitting off from this same original
+organ; and that the intestine itself is divided into three parts of
+different size and aspect by two circular sections.
+
+But we must not, I think, dismiss the formation of the skeleton so
+quickly. I told you already that the skeleton has its first origin in
+the midst of the two triangular cell-masses of the mesenchyme; but what
+are the steps before it attains its typical and complicated structure?
+At the beginning a very small tetrahedron, consisting of carbonate of
+calcium, is formed in each of the triangles; the four edges of the
+tetrahedron are produced into thin rods, and by means of a different
+organogenesis along each of these rods the typical formation of the
+skeleton proceeds. But the manner in which it is carried out is very
+strange and peculiar. About thirty of the mesenchyme cells are occupied
+in the formation of skeleton substance on each side of the larva. They
+wander through the interior space of the gastrula--which at this stage
+is not filled with sea water but with a sort of gelatinous material--and
+wander in such a manner that they always come to the right places, where
+a part of the skeleton is to be formed; they form it by a process of
+secretion, quite unknown in detail; one of them forms one part, one the
+other, but what they form altogether, is one whole.
+
+When the formation of the skeleton is accomplished, the typical larva
+of our Echinus is built up; it is called the “pluteus” (Fig. 4). Though
+it is far from being the perfect adult animal, it has an independent
+life of its own; it feeds and moves about and does not go through any
+important changes of form for weeks. But after a certain period of
+this species of independent life as a “larva,” the changes of form it
+undergoes again are most fundamental: it must be transformed into the
+adult sea-urchin, as all of you know. There are hundreds and hundreds
+of single operations of organogenesis to be accomplished before that
+end is reached; and perhaps the strangest of all these operations is a
+certain sort of growth, by which the symmetry of the animal, at least
+in certain of its parts--not in all of them--is changed again from
+bilateral to radial, just the opposite of what happened in the very
+early stages.
+
+[Illustration: Fig. 4.--Larval Development of Echinus.
+
+*A.* The gastrula.
+
+*B.* Later stage, bilateral-symmetrical. Intestine begins to divide
+into three parts.
+
+*C.* Pluteus larva. S = Skeleton. I = Intestine.]
+
+But we cannot follow the embryology of our Echinus further here; and
+indeed we are the less obliged to do so, since in all our experimental
+work we shall have to deal with it only as far as to the pluteus larva.
+It is impossible under ordinary conditions to rear the germs up to the
+adult stages in captivity.
+
+You now, I hope, will have a general idea at least of the processes
+of which the individual development of an animal consists. Of course
+the specific features leading from the egg to the adult are different
+in each specific case, and, in order to make this point as clear as
+possible, I shall now add to our description a few words about what may
+be called a comparative descriptive embryology.
+
+
+COMPARATIVE EMBRYOLOGY
+
+Even the cleavage may present rather different aspects. There may be a
+compact blastula, not one surrounded by only one layer of cells as in
+Echinus; or bilaterality may be established as early as the cleavage
+stage--as in many worms and in ascidians--and not so late as in Echinus.
+The formation of the germ layers may go on in a different order and
+under very different conditions: a rather close relative of our Echinus,
+for instance, the starfish, forms first the endoderm and afterwards
+the mesenchyme. In many cases there is no tube of cells forming the
+“endoderm,” but a flat layer of cells is the first foundation of all the
+intestinal organs: so it is in all birds and in the cuttlefish. And,
+as all of you know, of course, there are very many animal forms which
+have no proper “larval” stage: there is one in the frog, the well-known
+“tadpole,” but the birds and mammals have no larvae; that is to say,
+there is no special stage in the ontogeny of these forms which leads an
+independent life for a certain time, as if it were a species by itself,
+but all the ontogenetical stages are properly “embryonic”--the germ is
+always an “embryo” until it becomes the perfect young organism. And you
+also know that not all skeletons consist of carbonate of calcium, but,
+that there are skeletons of silicates, as in Radiolaria, and of horny
+substance, as in many sponges. And, indeed, if we were to glance at the
+development of plants also, the differences would seem to us probably
+so great that all the similarities would seem to disappear.
+
+But there are similarities, nevertheless, in all development, and we
+shall now proceed to examine what they are. As a matter of fact, it was
+especially for their sake that we studied the ontogeny of a special
+form in such detail; one always sees generalities better if one knows
+the specific features of at least one case. What then are the features
+of most general and far-reaching importance, which may be abstracted
+from the individual history of our sea-urchin, checked always by the
+teachings of other ontogenies, including those of plants?
+
+
+THE FIRST STEPS OF ANALYTICAL MORPHOGENESIS
+
+If we look back upon the long fight of the schools of embryologists in
+the eighteenth century about the question whether individual development
+was to be regarded as a real production of visible manifoldness or as
+a simple growth of visibly pre-existing manifoldness, whether it was
+“epigenesis” or “evolutio,” there can be no doubt, if we rely on all
+the investigations of the last hundred and fifty years, that, taken in
+the descriptive sense, the theory of epigenesis is right. Descriptively
+speaking there *is* a production of visible manifoldness in the course
+of embryology: that is our first and main result. Any one possessed of
+an average microscope may any day convince himself personally that it is
+true.
+
+In fact, true epigenesis, in the descriptive sense of the term, does
+exist. One thing is formed “after” the other; there is not a mere
+“unfolding” of what existed already, though in a smaller form; there is
+no “evolutio” in the old meaning of the word.
+
+The word “evolution” in English usually serves to denote the theory of
+descent, that is of a real relationship of all organisms. Of course we
+are not thinking here of this modern and specifically English meaning of
+the Latin word *evolutio*. In its ancient sense it means to a certain
+degree just the opposite; it says that there is no formation of anything
+new, no transformation, but simply growth, and this is promoted not for
+the race but for the individual. Keeping well in mind these historical
+differences in the meaning of the word “evolutio,” no mistakes, it seems
+to me, can occur from its use. We now shall try to obtain a few more
+particular results from our descriptive study of morphogenesis, which
+are nevertheless of a general bearing, being real characteristics of
+organic individual development, and which, though not calculated of
+themselves to further the problem, will in any case serve to prepare for
+a more profound study of it.
+
+The totality of the line of morphogenetic facts can easily be resolved
+into a great number of distinct processes. We propose to call these
+“elementary morphogenetic processes”; the turning in of the endoderm
+and its division into three typical parts are examples of them. If we
+give the name “elementary organs” to the distinct parts of every stage
+of ontogeny which are uniform in themselves and are each the result of
+one elementary process in our sense, we are entitled to say that each
+embryological stage consists of a certain number of elementary organs.
+The mesenchyme ring, the coelum, the middle-intestine, are instances of
+such organs. It is important to notice well that the word elementary is
+always understood here with regard to visible morphogenesis proper and
+does not apply to what may be called elementary in the physiological
+sense. An elementary process in our sense is a very distinct act of
+form-building, and an elementary organ is the result of every one of
+such acts.
+
+The elementary organs are typical with regard to their position and with
+regard to their histological properties. In many cases they are of a
+very clearly different histological type, as for instance, the cells of
+the three so-called germ-layers; and in other cases, though apparently
+almost identical histologically, they can be proved to be different
+by their different power of resisting injuries or by other means. But
+there are not as many different types of histological structure as there
+are typically placed organs: on the contrary there are many elementary
+organs of the same type in different typical parts of the organism, as
+all of you know to be the case with nerves and muscles. It will not be
+without importance for our future theory of development, carefully to
+notice this fact, that specialisation in the *position* of embryonic
+parts is more strict than in their histology.
+
+But elementary organs are not only typical in position and histology,
+they are typical also with regard to their form and their relative size.
+It agrees with what has been said about histology being independent of
+typical position, that there may be a number of organs in an embryonic
+stage, all in their most typical positions, which though all possessing
+the same histology, may have different forms or different sizes or
+both: the single bones of the skeleton of vertebrates or of adult
+echinoderms are the very best instances of this most important feature
+of organogenesis. If we look back from elementary organs to elementary
+processes, the specialisation of the size of those organs may also be
+said to be the consequence of a typical duration of the elementary
+morphogenetic process leading to them.[7]
+
+[7] The phrase “*ceteris paribus*” has to be added of course, as the
+duration of each single elementary morphogenetic process is liable to
+vary with the temperature and many other conditions of the medium.
+
+I hardly need to say, that the histology, form, and size of elementary
+organs are equally an expression of their present or future
+physiological function. At least they prepare for this function by a
+specific sort of metabolism which sets in very early.
+
+The whole sequence of individual morphogenesis has been divided by some
+embryologists into two different periods; there is a first period,
+during which the foundations of the organisation of the “type” are
+laid down, and a second period, during which the histo-physiological
+specifications are modelled out (von Baer, Götte, Roux). Such a
+discrimination is certainly justified, if not taken too strictly; but
+its practical application would encounter certain difficulties in many
+larval forms, and also, of course, in all plants.
+
+Our mention of plants leads us to the last of our analytical results. If
+an animal germ proceeds in its development from a stage *d* to the stage
+*g*, passing through *e* and *f*, we may say that the whole of *d* has
+become the whole of *f*, but we cannot say that there is a certain part
+of *f* which is *d*, we cannot say that *f* is *d* + *a*. But in plants
+we can: the stage *f* is indeed equal to *a* + *b* + *c* + *d* + *e* +
+*a* [Transcriber’s note: probable typo for *f*] in vegetable organisms;
+all earlier stages are actually visible as parts of the last one. The
+great embryologist, Carl Ernst von Baer, most clearly appreciated these
+analytical differences between animal and vegetable morphogenesis. They
+become a little less marked if we remember that plants, in a certain
+respect, are not simple individuals but colonies, and that among the
+corals, hydroids, bryozoa, and ascidia, we find analogies to plants in
+the animal kingdom; but nevertheless the differences we have stated are
+not extinguished by such reasoning. It seems almost wholly due to the
+occurrence of so many foldings and bendings and migrations of cells and
+complexes of cells in animal morphogenesis, that an earlier stage of
+their development seems *lost* in the later one; those processes are
+almost entirely wanting in plants, even if we study their very first
+ontogenetic stages. If we say that almost all production of surfaces
+goes on outside in plants, inside in animals, we shall have adequately
+described the difference. And this feature again leads to the further
+diversity between animals and plants which is best expressed by calling
+the former “closed,” the latter “open” forms: animals reach a point
+where they are finished, plants never are finished, at least in most
+cases.
+
+I hope you will allow that I have tried to draw from descriptive and
+comparative embryology as many general analytical results as are
+possibly to be obtained. It is not my fault if there are not any
+more, nor is it my fault if the results reached are not of the most
+satisfactory character. You may say that these results perhaps enable
+you to see a little more clearly and markedly than before a few of the
+characters of development, but that you have not really learnt anything
+new. Your disappointment--my own disappointment--in our analysis is due
+to the use of pure description and comparison as scientific methods.
+
+
+THE LIMITS OF PURE DESCRIPTION IN SCIENCE
+
+We have analysed our descriptions as far as we could, and now we must
+confess that what we have found cannot be the last thing knowable
+about individual morphogenesis. There must be something deeper to be
+discovered: we only have been on the surface of the phenomena, we
+now want to get to the very bottom of them. Why then occurs all that
+folding, and bending, and histogenesis, and all the other processes we
+have described? There must be something that drives them out, so to say.
+
+There is a very famous dictum in the *Treatise on Mechanics* by the
+late Gustav Kirchhoff, that it is the task of mechanics to describe
+completely and in the most simple manner all the motions that occur in
+nature. These words, which may appear problematic even in mechanics,
+have had a really pernicious influence on biology. People were extremely
+pleased with them. “‘Describing’--that is just what we always have
+done,” they said; “now we see that we have done just what was right;
+a famous physicist has told us so.” They did not see that Kirchhoff
+had added the words “completely and in the most simple manner”; and
+moreover, they did not consider that Kirchhoff never regarded it as the
+ultimate aim of physics to describe thunderstorms or volcanic eruptions
+or denudations; yet it only is with such “descriptions” that biological
+descriptions of *given* bodies and processes are to be compared!
+
+Physicists always have used both experiment and hypothetical
+construction--Kirchhoff himself did so in the most gifted manner. With
+these aids they have gone through the whole of the phenomena, and what
+they found to be ultimate and truly elemental, that alone may they
+be said to have “described”; but they have “explained” by the aid of
+elementalities what proved to be not elemental in itself.[8]
+
+[8] We shall not avoid in these lectures the word “explain”--so much
+out of fashion nowadays. To “explain” means to subsume under known
+concepts, or rules, or laws, or principles, whether the laws or concepts
+themselves be “explained” or not. Explaining, therefore, is always
+relative: what is elemental, of course, is only to be described, or
+rather to be stated.
+
+It is the *method* of the physicists--not their results--that
+morphogenesis has to apply in order to make progress; and this method
+we shall begin to apply in our next lectures. Physiology proper has
+never been so short-sighted and self-satisfied as not to learn from
+other sciences, from which indeed there was very much to be learned; but
+morphology has: the bare describing and comparing of descriptions has
+been its only aim for about forty years or more, and lines of descent of
+a very problematic character were its only general results. It was not
+seen that science had to begin, not with problematic events of the past,
+but with what actually happens before our eyes.
+
+But before saying any more about the exact rational and experimental
+method in morphology, which indeed may be regarded as a new method,
+since its prevalence in the eighteenth century had been really
+forgotten, we first shall have to analyse shortly some general attempts
+to understand morphogenesis by means of hypothetic construction
+exclusively. Such attempts have become very important as points of
+issue for really exact research, and, moreover, they deserve attention,
+because they prove that their authors at least had not quite forgotten
+that there were still other problems to be solved in morphology than
+only phylogenetical ones.
+
+
+
+
+*B.* EXPERIMENTAL AND THEORETICAL MORPHOGENESIS
+
+1. THE FOUNDATIONS OF THE PHYSIOLOGY OF DEVELOPMENT. “EVOLUTIO” AND
+“EPIGENESIS”
+
+
+THE THEORY OF WEISMANN
+
+Of all the purely hypothetic theories on morphogenesis that of August
+Weismann[9] can claim to have had the greatest influence, and to
+be at the same time the most logical and the most elaborated. The
+“germ-plasma” theory of the German author is generally considered as
+being a theory of heredity, and that is true inasmuch as problems of
+inheritance proper have been the starting-point of all his hypothetic
+speculations, and also form in some respect the most valuable part
+of them. But, rightly understood, Weismann’s theory consists of two
+independent parts, which relate to morphogenesis and to heredity
+separately, and it is only the first which we shall have to take into
+consideration at present; what is generally known as the doctrine of the
+“continuity of the germ-plasm” will be discussed in a later chapter.
+
+[9] *Das Keimplasma*, Jena, 1892.
+
+Weismann assumes that a very complicated organised structure, below
+the limits of visibility even with the highest optical powers, is the
+foundation of all morphogenetic processes, in such a way that, whilst
+part of this structure is handed over from generation to generation as
+the basis of heredity, another part of it is disintegrated during the
+individual development, and directs development by being disintegrated.
+The expression, “part” of the structure, first calls for some
+explanation. Weismann supposes several examples, several copies, as it
+were, of his structure to be present in the germ cells, and it is to
+these copies that the word “part” has been applied by us: at least one
+copy has to be disintegrated during ontogeny.
+
+The morphogenetic structure is assumed to be present in the nucleus
+of the germ cells, and Weismann supposes the disintegration of his
+hypothetic structure to be accomplished by nuclear division. By the
+cleavage of the egg, the most *fundamental* parts of it are separated
+one from the other. The word “fundamental” must be understood as
+applying not to proper elements or complexes of elements of the
+organisation, but to the chief relations of symmetry; the first
+cleavage, for instance, may separate the right and the left part of
+the structure, the second one its upper and lower parts, and after the
+third or equatorial cleavage all the principal eighths of our minute
+organisation are divided off: for the minute organisation, it must now
+be added, had been supposed to be built up differently in the three
+directions of space, just as the adult organism is. Weismann concedes it
+to be absolutely unknown in what manner the proper relation between the
+parts of the disintegrated fundamental morphogenetic structure and the
+real processes of morphogenesis is realised; enough that there may be
+imagined such a relation.
+
+At the end of organogenesis the structure is assumed to have been
+broken up into its elements, and these elements, which may be chemical
+compounds, determine the fate of the single cells of the adult organism.
+
+Here let us pause for a moment. There cannot be any doubt that
+Weismann’s theory resembles to a very high degree the old “evolutio”
+doctrines of the eighteenth century, except that it is a little less
+crude. The chick itself is not supposed to be present in the hen’s egg
+before development, and ontogeny is not regarded as a mere growth of
+that chick in miniature, but what really is supposed to be present in
+the egg is nevertheless a something that in all its parts corresponds
+to all the parts of the chick, only under a somewhat different
+aspect, while all the relations of the parts of the one correspond
+to the relations of the parts of the other. Indeed, only on such an
+hypothesis of a fairly fixed and rigid relation between the parts of
+the morphogenetic structure could it be possible for the disintegration
+of the structure to go on, not by parts of organisation, but by parts
+of symmetry; which, indeed, is a very strange, but not an illogical,
+feature of Weismann’s doctrine.
+
+Weismann is absolutely convinced that there must be a theory of
+“evolutio,” in the old sense of the word, to account for the ontogenetic
+facts; that “epigenesis” has its place only in descriptive embryology,
+where, indeed, as we know, manifoldness in the *visible* sense is
+produced, but that epigenesis can never form the foundation of a real
+morphogenetic *theory*: theoretically one pre-existing manifoldness is
+transformed into the other. An epigenetic theory would lead right beyond
+natural science, Weismann thinks, as in fact, all such theories, if
+fully worked out, have carried their authors to vitalistic views. But
+vitalism is regarded by him as dethroned for ever.
+
+Under these circumstances we have a good right, it seems to me, to speak
+of a *dogmatic* basis of Weismann’s theory of development.
+
+But to complete the outlines of the theory itself: Weismann was
+well aware that there were some grave difficulties attaching to his
+statements: all the facts of so-called adventitious morphogenesis in
+plants, of regeneration in animals, proved that the morphogenetic
+organisation could not be fully disintegrated during ontogeny. But these
+difficulties were not absolute: they could be overcome: indeed, Weismann
+assumes, that in certain specific cases--and he regarded all cases of
+restoration of a destroyed organisation as due to specific properties
+of the subjects, originated by roundabout variations and natural
+selection--that in specific cases, specific arrangements of minute parts
+were formed during the process of disintegration, and were surrendered
+to specific cells during development, from which regeneration or
+adventitious budding could originate if required. “Plasma of reserve”
+was the name bestowed on these hypothetic arrangements.
+
+Almost independently another German author, Wilhelm Roux,[10] has
+advocated a theoretical view of morphogenesis which very closely
+resembles the hypothesis of Weismann. According to Roux a minute
+ultimate structure is present in the nucleus of the germ and directs
+development by being divided into its parts during the series of nuclear
+divisions.
+
+[10] *Die Bedeutung der Kernteilungsfiguren*, Leipzig, 1883.
+
+But in spite of this similarity of the outset, we enter an altogether
+different field of biological investigation on mentioning Roux’s name:
+we are leaving hypothetic construction, at least in its absoluteness,
+and are entering the realms of scientific experiment in morphology.
+
+
+EXPERIMENTAL MORPHOLOGY
+
+I have told you already in the last lecture that, while in the
+eighteenth century individual morphogenesis had formed the centre of
+biological interest and been studied experimentally in a thoroughly
+adequate manner, that interest gradually diminished, until at last
+the physiology of form as an exact separate science was almost wholly
+forgotten. At least that was the state of affairs as regards zoological
+biology; botanists, it must be granted, have never lost the historical
+continuity to such a degree; botany has never ceased to be regarded
+as one science and never was broken up into parts as zoology was.
+Zoological physiology and zoological morphology indeed were for many
+years in a relationship to one another not very much closer than the
+relation between philology and chemistry.
+
+There were always a few men, of course, who strove against the current.
+The late Wilhelm His,[11] instance, described the embryology of the
+chick in an original manner, in order to find out the mechanical
+relations of embryonic parts, by which passive deformation, as an
+integrating part of morphogenesis, might be induced. He also most
+clearly stated the ultimate aim of embryology to be the mathematical
+derivation of the adult form from the distribution of growth in the
+germ. To Alexander Goette[12] we owe another set of analytical
+considerations about ontogeny. Newport, as early as 1850, and in
+later years Pflüger and Rauber, carried out experiments on the eggs
+of the frog, which may truly be called anticipatory of what was to
+follow. But it was Wilhelm Roux,[13] now professor of anatomy at
+Halle, who entered the field with a thoroughly elaborated programme,
+who knew not only how to state the problem analytically, but also
+how to attack it, fully convinced of the importance of what he did.
+“Entwickelungsmechanik,”--mechanics of development--he called the “new
+branch of anatomical science” of which he tried to lay the foundations.
+
+[11] *Unsere Körperform*, Leipzig, 1875.
+
+[12] *Die Entwickelungsgeschichte der Unke*, Leipzig, 1875.
+
+[13] *Gesammelte Abhandlungen*, Leipzig, 1895. Most important
+theoretical papers:--*Zeitschr. Biolog.* 21, 1885; *Die
+Entwickelungsmechanik der Organismen*, Wien, 1890; *Vorträge und
+Aufsätze über Entwickelungsmechanik*, Heft i., Leipzig, 1905.
+
+I cannot let this occasion pass without emphasising in the most decided
+manner how highly in my opinion Roux’s services to the systematic
+exploration of morphogenesis must be esteemed. I feel the more obliged
+to do so, because later on I shall have to contradict not only many
+of his positive statements but also most of his theoretical views. He
+himself has lately given up much of what he most strongly advocated only
+ten years ago. But Roux’s place in the history of biological science can
+never be altered, let science take what path it will.
+
+It is not the place here to develop the logic of experiment; least of
+all is it necessary in the country of John Stuart Mill. All of you know
+that experiment, by its method of isolating the single constituents
+of complicated phenomena, is the principal aid in the discovery of
+so-called causal relations. Let us try then to see what causal
+relations Wilhelm Roux established with the aid of morphogenetic
+experiment.
+
+
+THE WORK OF WILHELM ROUX
+
+We know already that an hypothesis about the foundation of individual
+development was his starting-point. Like Weismann he supposed that
+there exists a very complicated structure in the germ, and that nuclear
+division leads to the disintegration of that structure. He next tried to
+bring forward what might be called a number of indicia supporting his
+view.
+
+A close relation had been found to exist in many cases between the
+direction of the first cleavage furrows of the germ and the direction
+of the chief planes of symmetry in the adult: the first cleavage, for
+instance, very often corresponds to the median plane, or stands at right
+angles to it. And in other instances, such as have been worked out into
+the doctrine of so-called “cell-lineages,” typical cleavage cells were
+found to correspond to typical organs. Was not that a strong support
+for a theory which regarded cellular division as the principal means
+of differentiation? It is true, the close relations between cleavage
+and symmetry did not exist in every case, but then there had always
+happened some specific experimental disturbances, *e.g.* influences of
+an abnormal direction of gravity on account of a turning over of the
+egg, and it was easy to reconcile such cases with the generally accepted
+theory on the assumption of what was called “anachronism” of cleavage.
+
+But Roux was not satisfied with mere indicia, he wanted a proof, and
+with this intention he carried out an experiment which has become
+very celebrated.[14] With a hot needle he killed one of the first two
+blastomeres of the frog’s egg after the full accomplishment of its first
+cleavage, and then watched the development of the surviving cell. A
+typical half-embryo was seen to emerge--an organism indeed, which was as
+much a half as if a fully formed embryo of a certain stage had been cut
+in two by a razor. It was especially in the anterior part of the embryo
+that its “halfness” could most clearly be demonstrated.
+
+[14] *Virchow’s Archiv.* 114, 1888.
+
+That seemed to be a proof of Weismann’s and Roux’s theory of
+development, a proof of the hypothesis that there is a very complicated
+structure which promotes ontogeny by its disintegration, carried out
+during the cell divisions of embryology by the aid of the process of
+nuclear division, the so-called “karyokinesis.”
+
+To the dispassionate observer it will appear, I suppose, that the
+conclusions drawn by Roux from his experiment go a little beyond their
+legitimate length. Certainly some sort of “evolutio” is proved by
+rearing half the frog from half the egg. But is anything proved, is
+there anything discovered at all about the nucleus? It was only on
+account of the common opinion about the part it played in morphogenesis
+that the nucleus had been taken into consideration.
+
+Things soon became still more ambiguous.
+
+
+THE EXPERIMENTS ON THE EGG OF THE SEA-URCHIN
+
+Roux’s results were published for the first time in 1888; three years
+later I tried to repeat his fundamental experiment on another subject
+and by a somewhat different method. It was known from the cytological
+researches of the brothers Hertwig and Boveri that the eggs of the
+common sea-urchin (*Echinus microtuberculatus*) are able to stand well
+all sorts of rough treatment, and that, in particular, when broken into
+pieces by shaking, their fragments will survive and continue to segment.
+I took advantage of these facts for my purposes. I shook the germs
+rather violently during their two-cell stage, and in several instances I
+succeeded in killing one of the blastomeres, while the other one was not
+damaged, or in separating the two blastomeres from one another.[15]
+
+[15] *Zeitschr. wiss. Zool.* 53, 1891.
+
+Let us now follow the development of the isolated surviving cell. It
+went through cleavage just as it would have done in contact with its
+sister-cell, and there occurred cleavage stages which were just half
+of the normal ones. The stage, for instance, which corresponded to the
+normal sixteen-cell stage, and which, of course, in my subjects was
+built up of eight elements only, showed two micromeres, two macromeres
+and four cells of medium size, exactly as if a normal sixteen-cell stage
+had been cut in two; and the form of the whole was that of a hemisphere.
+So far there was no divergence from Roux’s results.
+
+The development of our Echinus proceeds rather rapidly, the cleavage
+being accomplished in about fifteen hours. I now noticed on the evening
+of the first day of the experiment, when the half-germ was composed of
+about two hundred elements, that the margin of the hemispherical germ
+bent together a little, as if it were about to form a whole sphere
+of smaller size, and, indeed, the next morning a *whole* diminutive
+blastula was swimming about. I was so much convinced that I should get
+Roux’s morphogenetical result in all its features that, even in spite of
+this whole blastula, I now expected that the next morning would reveal
+to me the half-organisation of my subject once more; the intestine, I
+supposed, might come out quite on one side of it, as a half-tube, and
+the mesenchyme ring might be a half one also.
+
+But things turned out as they were bound to do and not as I had
+expected; there was a typically *whole* gastrula on my dish the next
+morning, differing only by its small size from a normal one; and this
+*small but whole* gastrula was followed by a whole and typical small
+pluteus-larva (Fig. 5).
+
+[Illustration: Fig. 5.--Illustration of Experiments on Echinus.
+
+*a*_1 and *b*_1. Normal gastrula and normal pluteus.
+
+*a*_2 and *b*_2. “Half”-gastrula and “half”-pluteus, that *ought* to result
+from one of the first two blastomeres, when isolated, according to the
+theory of “evolutio.”
+
+*a*_3 and *b*_3. The small *but whole* gastrula and pluteus that actually
+*do* result.]
+
+That was just the opposite of Roux’s result: one of the first two
+blastomeres had undergone a half-cleavage as in his case, but then it
+had become a whole organism by a simple process of rearrangement of its
+material, without anything that resembled regeneration, in the sense of
+a completion by budding from a wound.
+
+If one blastomere of the two-cell stage was thus capable of performing
+the morphogenetical process in its totality, it became, of course,
+*impossible* to allow that nuclear division had separated any sort of
+“germ-plasm” into two different halves, and not even the protoplasm of
+the egg could be said to have been divided by the first cleavage furrow
+into unequal parts, as the postulate of the strict theory of so-called
+“evolutio” had been. This was a very important result, sufficient
+alone to overthrow at once the theory of ontogenetical “evolutio,”
+the “Mosaiktheorie” as it had been called--not by Roux himself, but
+according to his views--in its exclusiveness.
+
+After first widening the circle of my observations by showing that
+one of the first four blastomeres is capable of performing a whole
+organogenesis, and that three of the first four blastomeres together
+result in an absolutely perfect organism, I went on to follow up
+separately one of the two fundamental problems which had been suggested
+by my first experiment: was there anything more to find out about
+the importance or unimportance of the single *nuclear* divisions in
+morphogenesis?[16]
+
+[16] *Zeitschr. wiss. Zool.* 55, 1892.
+
+By raising the temperature of the medium or by diluting the sea-water to
+a certain degree it proved at first to be possible to alter in a rather
+fundamental way the type of the cleavage-stages without any damage to
+the resulting organism. There may be no micromeres at the sixteen-cell
+stage, or they may appear as early as in the stage of eight cells;
+no matter, the larva is bound to be typical. So it certainly is not
+necessary for all the cleavages to occur just in their normal order.
+
+But of greater importance for our purposes was what followed. I
+succeeded in pressing the eggs of Echinus between two glass plates,
+rather tightly, but without killing them; the eggs became deformed to
+comparatively flat plates of a large diameter. Now in these eggs all
+nuclear division occurred at right angles to the direction of pressure,
+that is to say, in the direction of the plates, as long as the pressure
+lasted; but the divisions began to occur at right angles to their former
+direction, as soon as the pressure ceased. By letting the pressure be
+at work for different times I therefore, of course, had it quite in my
+power to obtain cleavage types just as I wanted to get them. If, for
+instance, I kept the eggs under pressure until the eight-cell stage was
+complete, I got a plate of eight cells one beside the other, instead of
+two rings, of four cells each, one above the other, as in the normal
+case; but the next cell division occurred at right angles to the former
+ones, and a sixteen-cell stage, of two plates of eight cells each, one
+above the other, was the result. If the pressure continued until the
+sixteen-cell stage was reached, sixteen cells lay together in one plate,
+and two plates of sixteen cells each, one above the other, were the
+result of the next cleavage.
+
+We are not, however, studying these things for cytological, but for
+morphogenetical purposes, and for these the cleavage phenomenon itself
+is less important than the organogenetic result of it: all our subjects
+resulted in *absolutely normal* organisms. Now, it is clear, that the
+spatial relations of the different nuclear divisions to each other are
+anything but normal, in the eggs subjected to the pressure experiments;
+that, so to say, every nucleus has got quite different neighbours if
+compared with the “normal” case. If that makes no difference, then
+there *cannot* exist any close relation between the single nuclear
+divisions and organogenesis at all, and the conclusion we have drawn
+more provisionally from the whole development of isolated blastomeres
+has been extended and proved in the most perfect manner. There ought to
+result a morphogenetic chaos according to the theory of real “evolutio”
+carried out by nuclear division, if the positions of the single nuclei
+were fundamentally changed with regard to one another (Fig. 6). But now
+there resulted not chaos, but the normal organisation: therefore it was
+disproved in the strictest way that nuclear divisions have any bearing
+on the origin of organisation; at least as far as the divisions during
+cleavage come into account.
+
+[Illustration: Fig. 6.--Pressure-experiments on Echinus.
+
+*a*_1 and *b*_1. Two normal cleavage stages, consisting of eight and
+sixteen cells.
+
+*a*_2 and *b*_2. Corresponding stages modified by exerting pressure
+until the eight-cell stage was finished. See text.]
+
+On the egg of the frog (O. Hertwig), and on the egg of annelids (E. B.
+Wilson), my pressure experiments have been carried out with the same
+result.[17]
+
+[17] In the pressure experiments I had altered the relative position of
+the nuclei *in origine*. In later years I succeeded in disturbing the
+arrangement of the fully formed cells of the eight-cell stage, and in
+getting normal larvæ in spite of that in many cases. But as this series
+of experiments is not free from certain complications--which in part
+will be understood later on (see page 73)--it must suffice here to have
+mentioned them. (For further information see my paper in *Archiv. f.
+Entwickelungsmechanik*, xiv., 1902, page 500.)
+
+
+ON THE INTIMATE STRUCTURE OF THE PROTOPLASM OF THE GERM
+
+Nuclear division, as we have seen, cannot be the basis of organogenesis,
+and all we know about the whole development of isolated blastomeres
+seems to show that there exists nothing responsible for differentiation
+in the protoplasm either.
+
+But would that be possible? It cannot appear possible on a more profound
+consideration of the nature of morphogenesis, it seems to me: as the
+untypical agents of the medium cannot be responsible in any way for
+the origin of a form combination which is most typical and specific,
+there must be somewhere in the egg itself a certain factor which is
+responsible at least for the general orientation and symmetry of it.
+Considerations of this kind led me, as early as 1893,[18] to urge the
+hypothesis that there existed, that there *must* exist, a sort of
+intimate structure in the egg, including polarity and bilaterality as
+the chief features of its symmetry, a structure which belongs to every
+smallest element of the egg, and which might be imagined by analogy
+under the form of elementary magnets.[19] This hypothetic structure
+could have its seat in the protoplasm only. In the egg of echinoderms it
+would be capable of such a quick rearrangement after being disturbed,
+that it could not be observed but only inferred logically; there might,
+however, be cases in which its real discovery would be possible. Indeed
+Roux’s frog-experiment seems to be a case where it is found to be at
+work: at least it seems very probable to assume that Roux obtained half
+of a frog’s embryo because the protoplasm of the isolated blastomere had
+preserved the “halfness” of its intimate structure, and had not been
+able to form a small whole out of it.
+
+[18] *Mitteil. Neapel. 11, 1893.*
+
+[19] But the elementary magnets would have to be bilateral!
+
+Of course it was my principal object to verify this hypothesis, and
+such verification became possible in a set of experiments which my
+friend T. H. Morgan and myself carried out together,[20] in 1895, on
+the eggs of ctenophores, a sort of pelagic animals, somewhat resembling
+the jelly-fish, but of a rather different inner organisation. The
+zoologist Chun had found even before Roux’s analytical studies, that
+isolated blastomeres of the ctenophore egg behave like parts of the
+whole and result in a half-organisation like the frog’s germ does. Chun
+had not laid much stress on his discovery, which now, of course, from
+the new points of view, became a very important one. We first repeated
+Chun’s experiment and obtained his results, with the sole exception
+that there was a tendency of the endoderm of the half-larva of Beroë
+to become more than “half.” But that was not what we chiefly wanted to
+study. We succeeded in cutting away a certain mass of the protoplasm
+of the ctenophore egg just before it began to cleave, without damaging
+its nuclear material in any way: in all cases, where the cut was
+performed at the side, there resulted a certain type of larvae from
+our experiments which showed exactly the same sort of defects as were
+present in larvae developed from one of the first two blastomeres alone.
+
+[20] *Arch. Entw. Mech.* 2, 1895.
+
+The hypothesis of the morphogenetic importance of *protoplasm* had thus
+been proved. In our experiments there was all of the nuclear material,
+but there were defects on one side of the protoplasm of the egg; and the
+defects in the adult were found to correspond to these defects in the
+protoplasm.
+
+And now O. Schultze and Morgan succeeded in performing some experiments
+which directly proved the hypothesis of the part played by protoplasm
+in the subject employed by Roux, *viz.*, the frog’s egg. The first of
+these investigators managed to rear two whole frog embryos of small
+size, if he slightly pressed the two-cell stage of that form between
+two plates of glass and turned it over; and Morgan,[21] after having
+killed one of the first two blastomeres, as was done in the original
+experiment of Roux, was able to bring the surviving one to a half or
+to a whole development according as it was undisturbed or turned.
+There cannot be any doubt that in both of these cases, it is the
+possibility of a rearrangement of protoplasm, offered by the turning
+over, which allows the isolated blastomere to develop as a whole. The
+regulation of the frog’s egg, with regard to its becoming whole, may be
+called facultative, whilst the same regulation of the egg of Echinus
+is obligatory. It is not without interest to note that the first two
+blastomeres of the common newt, *i.e.* of a form which belongs to the
+other class of Amphibia, after a separation of *any* kind, *always*
+develop as wholes, their faculty of regulation being obligatory, like
+that of Echinus.
+
+[21] *Anat. Anz.* 10, 1895.
+
+Whole or partial development may thus be dependent on the power of
+regulation contained in the intimate polar-bilateral structure of the
+protoplasm. Where this is so, the regulation and the differences in
+development are both connected with the chief relations of symmetry.
+The development becomes a half or a quarter of the normal because
+there is only one-half or one-quarter of a certain structure present,
+one-half or one-quarter with regard to the very wholeness of this
+structure; the development is whole, in spite of disturbances, if
+the intimate structure became whole first. We may describe the
+“wholeness,” “halfness,” or “quarterness” of our hypothetic structure
+in a mathematical way, by using three axes, at right angles to one
+another, as the base of orientation. To each of these, *x*, *y*, and
+*z*, a certain specific state with regard to the symmetrical relations
+corresponds; thence it follows that, if there are wanting all those
+parts of the intimate structure which are determined, say, by a negative
+value of *y*, by minus *y*, then there is wanting half of the intimate
+structure; and this halfness of the intimate structure is followed by
+the halfness of organogenesis, the dependence of the latter on the
+intimate structure being established. But if regulation has restored,
+on a smaller scale, the whole of the arrangement according to all values
+of *x*, *y* and *z*, development also can take place completely (Fig. 7).
+
+[Illustration: Fig. 7.--Diagram illustrating the intimate Regulation of
+Protoplasm from “Half” to “Whole.”
+
+The large circle represents the original structure of the egg. In all
+cases where cleavage-cells of the two-cell stage are isolated this
+original structure is only present as “half” in the beginning, say
+only on the right (+*y*) side. Development then becomes “half,” if the
+intimate structure remains half; but it becomes “whole” (on a smaller
+scale) if a new whole-structure (small circle!) is formed by regulatory
+processes.]
+
+I am quite aware that such a discussion is rather empty and purely
+formal, nevertheless it is by no means without value, for it shows
+most clearly the differences between what we have called the intimate
+structure of germs, responsible only for the general symmetry of
+themselves and of their isolated parts, and another sort of possible
+structure of the egg-protoplasm which we now shall have to consider, and
+which, at the first glance, seems to form a serious difficulty to our
+statements, as far at least as they claim to be of general importance.
+The study of this other sort of germinal structure at the same time will
+lead us a step farther in our historical sketch of the first years of
+“Entwickelungsmechanik” and will bring this sketch to its end.
+
+
+ON SOME SPECIFICITIES OF ORGANISATION IN CERTAIN GERMS
+
+It was known already about 1890, from the careful study of what has
+been called “cell-lineage,” that in the eggs of several families of
+the animal kingdom the origin of certain organs may be traced back to
+individual cells of cleavage, having a typical histological character
+of their own. In America especially such researches have been carried
+out with the utmost minuteness, E. B. Wilson’s study of the cell-lineage
+of the Annelid *Nereis* being the first of them. If it were true that
+nuclear division is of no determining influence upon the ontogenetic
+fate of the blastomeres, only peculiarities of the different parts of
+the protoplasm could account for such relations of special cleavage
+cells to special organs. I advocated this view as early as in 1894,
+and it was proved two years later by Crampton, a pupil of Wilson’s,
+in some very fine experiments performed on the germ of a certain
+mollusc.[22] The egg of this form contains a special sort of protoplasm
+near its vegetative pole, and this part of it is separated at each
+of the first two segmentations by a sort of pseudo-cleavage, leading
+to stages of three and five separated masses instead of two and four,
+the supernumerary mass being the so-called “yolk-sac” and possessing
+no nuclear elements (Fig. 8). Crampton removed this yolk-sac at the
+two-cell stage, and he found that the cleavage of the germs thus
+operated upon was normal except with regard to the size and histological
+appearance of one cell, and that the larvae originating from these
+germs were complete in every respect except in their mesenchyme, which
+was wanting. A special part of the protoplasm of the egg had thus been
+brought into relation with quite a special part of organisation, *and
+that special part of the protoplasm contained no nucleus*.
+
+[22] *Arch. Entw. Mech.* 3, 1896.
+
+[Illustration: Fig. 8.--The Mollusc Dentalium (*after* E. B. Wilson).
+
+*a.* The egg, consisting of three different kinds of protoplasmatic
+material.
+
+*b.* First cleavage-stage. There are two cells and one “pseudo-cell,”
+the yolk-sac, which contains no nucleus. This was removed in Crampton’s
+experiment.]
+
+
+GENERAL RESULTS OF THE FIRST PERIOD OF “ENTWICKELUNGSMECHANIK”
+
+This experiment of Crampton’s, afterwards confirmed by Wilson himself,
+may be said to have closed the first period of the new science of
+physiology of form, a period devoted almost exclusively to the problem
+whether the theory of nuclear division or, in a wider sense, whether the
+theory of a strict “evolutio” as the basis of organogenesis was true or
+not.
+
+It was shown, as we have seen, that the theory of the “qualitatively
+unequal nuclear division” (“qualitativ-ungleiche Kernteilung” in German)
+certainly was not true, and that there also was no strict “evolutio”
+in protoplasm. Hence Weismann’s theory was clearly disproved. There
+certainly is a good deal of real “epigenesis” in ontogeny, a good deal
+of “production of manifoldness,” not only with regard to visibility but
+in a more profound meaning. But some sort of pre-formation had also
+been proved to exist, and this pre-formation, or, if you like, this
+restricted evolution, was found to be of two different kinds. First an
+intimate organisation of the protoplasm, spoken of as its polarity and
+bilaterality, was discovered, and this had to be postulated for every
+kind of germs, even when it was overshadowed by immediate obligatory
+regulation after disturbances. Besides that there were cases in which
+a real specificity of special parts of the germ existed, a relation of
+these special parts to special organs: but this sort of specification
+also was shown to belong to the protoplasm.
+
+It follows from all we have mentioned about the organisation of
+protoplasm and its bearing on morphogenesis, that the eggs of different
+animals may behave rather differently, in this respect, and that
+the eggs indeed may be classified according to the degree of their
+organisation. Though we must leave a detailed discussion of these
+topics to morphology proper, we yet shall try shortly to summarise
+what has been ascertained about them in the different classes of the
+animal kingdom. A full regulation of the *intimate* structure of
+isolated blastomeres to a new whole, has been proved to exist in the
+highest degree in the eggs of all echinoderms, medusae, nemertines,
+Amphioxus, fishes, and in one class of the Amphibia (the *Urodela*);
+it is facultative only among the other class of Amphibia, the *Anura*,
+and seems to be only partly developed or to be wanting altogether among
+ctenophora, ascidia, annelids, and mollusca. Peculiarities in the
+organisation of *specific parts* of protoplasm have been proved to occur
+in more cases than at first had been assumed; they exist even in the
+echinoderm egg, as experiments of the last few years have shown; even
+here a sort of specification exists at the vegetative pole of the egg,
+though it is liable to a certain kind of regulation; the same is true in
+medusae, nemertines, etc.; but among molluscs, ascidians, and annelids
+no regulation about the specific organisation of the germ in cleavage
+has been found in any case.
+
+The differences in the degree of regulability of the intimate germinal
+structure may easily be reduced to simple differences in the physical
+consistency of their protoplasm.[23] But all differences in specific
+organisation must remain as they are for the present; it will be one of
+the aims of the future theory of development to trace these differences
+also to a common source.
+
+[23] It deserves notice in this connection, that in some cases the
+protoplasm of parts of a germ has been found to be more regulable in
+the earliest stages, when it is very fluid, than later, when it is more
+stiff.
+
+That such an endeavour will probably be not without success, is clear,
+I should think, from the mere fact that differences with regard to
+germinal specific pre-formation do not agree in any way with the
+systematic position of the animals exhibiting them; for, strange as it
+would be if there were two utterly different kinds of morphogenesis, it
+would be still more strange if there were differences in morphogenesis
+which were totally unconnected with systematic relationship: the
+ctenophores behaving differently from the medusae, and Amphioxus
+differently from ascidians.
+
+
+SOME NEW RESULTS CONCERNING RESTITUTIONS
+
+We now might close this chapter, which has chiefly dealt with the
+disproof of a certain sort of ontogenetic theories, and therefore
+has been almost negative in its character, did it not seem desirable
+to add at least a few words about the later discoveries relating to
+morphogenetic restorations of the adult. We have learnt that Weismann
+created his concept of “reserve plasma” to account for what little
+he knew about “restitutions”: that is, about the restoration of lost
+parts: he only knew regeneration proper in animals and the formation of
+adventitious buds in plants. It is common to both of these phenomena
+that they take their origin from typically localised points of the body
+in every case; each time they occur a certain well-defined part of the
+body is charged with the restoration of the lost parts. To explain
+such cases Weismann’s hypothesis was quite adequate, at least in a
+logical sense. But at present, as we shall discuss more fully in another
+chapter, we know of some very widespread forms of restitution, in which
+what is to be done for a replacement of the lost is not entrusted to
+*one* typical part of the body in every case, but in which the whole
+of the morphogenetic action to be performed is transferred in its
+*single* parts to the *single* parts of the body which is accomplishing
+restoration: each of its parts has to take an individual share in the
+process of restoration, effecting what is properly called a certain kind
+of “re-differentiation” (“Umdifferenzierung”), and this share varies
+according to the relative position of the part in each case. Later on
+these statements will appear in more correct form than at present, and
+then it will become clear that we are fully entitled to emphasise at the
+end of our criticism of Weismann’s theory, that his hypothesis relating
+to restorations can be no more true than his theory of development
+proper was found to be.
+
+And now we shall pass on to our positive work.
+
+We shall try to sketch the outlines of what might properly be called an
+*analytical theory of morphogenesis*; that is, to explain the sum of our
+knowledge about organic form-production, gained by experiment and by
+logical analysis, in the form of a real system, in which each part will
+be, or at least will try to be, in its proper place and in relation with
+every other part. Our analytical work will give us ample opportunity of
+mentioning many important topics of so-called general physiology also,
+irrespective of morphogenesis as such. But morphogenesis is always to
+be the centre and starting-point of our analysis. As I myself approach
+the subject as a zoologist, animal morphogenesis, as before, will be the
+principal subject of what is to follow.
+
+
+2. ANALYTICAL THEORY OF MORPHOGENESIS[24]
+
+[24] Compare my *Analytische Theorie der organischen Entwickelung*,
+Leipzig, 1894, and my reviews in *Ergebnisse der Anatomie und
+Entwickelungsgeschichte*, vols. viii. xi. xiv., 1899-1905. A shorter
+review is given in *Ergebnisse der Physiologie*, vol. v., 1906. The full
+literature will be found in these reviews.
+
+α. THE DISTRIBUTION OF MORPHOGENETIC POTENCIES
+
+*Prospective Value and Prospective Potency*
+
+Wilhelm Roux did not fail to see that the questions of the locality and
+the time of all morphogenetic differentiations had to be solved first,
+before any problem of causality proper could be attacked. From this
+point of view he carried out his fundamental experiments.
+
+It is only in terminology that we differ from his views, if we prefer
+to call our introductory chapter an analysis of the distribution of
+morphogenetic potencies. The result will be of course rather different
+from what Roux expected it would be.
+
+Let us begin by laying down two fundamental concepts. Suppose we have
+here a definite embryo in a definite state of development, say a
+blastula, or a gastrula, or some sort of larva, then we are entitled
+to study any special element of any special elementary organ of this
+germ with respect to what is actually to develop out of this very
+element in the future actual course of this development, whether it be
+undisturbed or disturbed in any way; it is, so to say, the actual, *the
+real fate* of our element, that we take in account. I have proposed to
+call this real fate of each embryonic part in this very definite line
+of morphogenesis its *prospective value* (“prospective Bedeutung” in
+German). The fundamental question of the first chapter of our analytical
+theory of development may now be stated as follows: Is the prospective
+value of each part of any state of the morphogenetic line constant,
+*i.e.* is it unchangeable, can it be nothing but one; or is it variable,
+may it change according to different circumstances?
+
+We first introduce a second concept: the term *prospective potency*
+(“prospective Potenz” in German) of each embryonic element. The term
+“prospective morphogenetic potency” is to signify the *possible
+fate* of each of those elements. With the aid of our two artificial
+concepts we are now able to formulate our introductory question thus:
+Is the prospective potency of each embryonic part fully given by
+its prospective value in a certain definite case; is it, so to say,
+identical with it, or does the prospective potency contain more than the
+prospective value of an element in a certain case reveals?
+
+We know already from our historical sketch that the latter is true: that
+the actual fate of a part need not be identical with its possible fate,
+at least in many cases; that the potency of the first four blastomeres
+of the egg of the sea-urchin, for instance, has a far wider range than
+is shown by what each of them actually performs in even this ontogeny.
+There are more morphogenetic possibilities contained in each embryonic
+part than are actually realised in a special morphogenetic case.
+
+As the most important special morphogenetic case is, of course, the
+so-called “normal” one, we can also express our formula in terms of
+special reference to it: there are more morphogenetic possibilities in
+each part than the observation of the normal development can reveal.
+Thus we have at once justified the application of analytical experiment
+to morphogenesis, and have stated its most important results.
+
+As the introductory experiments about “Entwickelungsmechanik” have shown
+already that the prospective potency of embryonic parts, at least in
+certain cases, *can* exceed their prospective value--that, at least in
+certain cases, it can be different from it--the concept of prospective
+potency at the very beginning of our studies puts itself in the centre
+of analytical interest, leaving to the concept of prospective value the
+second place only. For that each embryonic part actually has a certain
+prospective value, a specified actual fate in every single case of
+ontogeny, is clear from itself and does not affirm more than the reality
+of morphogenetic cases in general; but that the prospective value of the
+elements may change, that there is a morphogenetic power in them, which
+contains more than actuality; in other words, that the term “prospective
+potency” has not only a logical but a factual interest: all these points
+amount to a statement not only of the most fundamental introductory
+results but also of the actual *problems* of the physiology of form.
+
+If at each point of the germ something else *can* be formed than
+actually is formed, why then does there happen in each case just what
+happens and nothing else? In these words indeed we may state the chief
+problem of our science, at least after the fundamental relation of
+the superiority of prospective potency to prospective value has been
+generally shown.
+
+We consequently may shortly formulate our first problem as the question
+of the distribution of the prospective morphogenetic potencies in the
+germ. Now this general question involves a number of particular ones.
+Up to what stage, if at all, is there an absolutely equal distribution
+of the potencies over all the elements of the germ? When such an equal
+distribution has ceased to exist at a certain stage, what are then the
+relations between the parts of different potency? How, on the other
+hand, does a newly arisen, more specialised sort of potency behave with
+regard to the original general potency, and what about the distribution
+of the more restricted potency?
+
+I know very well that all such questions will seem to you a little
+formal, and, so to say, academical at the outset. We shall not fail to
+attach to them very concrete meanings.
+
+*The Potencies of the Blastomeres*
+
+At first we turn back to our experiments on the egg of the sea-urchin
+as a type of the germ in the very earliest stages. We know already that
+each of the first two, or each of the first four, or three of the first
+four blastomeres together may produce a whole organism. We may add that
+the swimming blastula, consisting of about one thousand cells, when cut
+in two quite at random, in a plane coincident with, or at least passing
+near, its polar axis, may form two fully developed organisms out of its
+halves.[25] We may formulate this result in the words: the prospective
+potency of the single cells of a blastula of Echinus is the same for
+all of them; their prospective value is as far as possible from being
+constant.
+
+[25] If the plane of section passes near the equator of the germ, two
+whole larvae may be formed also, but in the majority of cases the
+“animal” half does not go beyond the blastula. The specific features of
+the organisation of the protoplasm come into account here. See also page
+65, note 1.
+
+But we may say even a little more: what actually will happen in each of
+the blastula cells in any special case of development experimentally
+determined depends on the position of that cell in the whole, if the
+“whole” is put into relation with any fixed system of co-ordinates; or
+more shortly, “the prospective value of any blastula cell is a function
+of its position in the whole.”
+
+I know from former experience that this statement wants a few words of
+explanation. The word “function” is employed here in the most general,
+mathematical sense, simply to express that the prospective value,
+the actual fate of a cell, will change, whenever its position in the
+whole is different.[26] The “whole” may be related to any three axes
+drawn through the normal undisturbed egg, on the hypothesis that there
+exists a primary polarity and bilaterality of the germ; the axes which
+determine this sort of symmetry may, of course, conveniently be taken as
+co-ordinates; but that is not necessary.
+
+[26] A change of the position of the cell is of course effected by each
+variation of the direction of the cut, which is purely a matter of
+chance.
+
+*The Potencies of Elementary Organs in General*
+
+Before dealing with other very young germs, I think it advisable to
+describe first an experiment which is carried out at a later stage of
+our well-known form. This experiment will easily lead to a few new
+concepts, which we shall want later on, and will serve, on the other
+hand, as a basis of explanation for some results, obtained from the
+youngest germs of some other animal species, which otherwise would seem
+to be rather irreconcilable with what our Echinus teaches us.
+
+You know, from the second lecture, what a gastrula of our sea-urchin
+is. If you bisect this gastrula, when it is completely formed, or
+still better, if you bisect the gastrula of the starfish, either along
+the axis or at right angles to it, you get complete little organisms
+developed from the parts: the ectoderm is formed in the typical manner
+in the parts, and so is the endoderm; everything is proportionate and
+only smaller than in the normal case. So we have at once the important
+results, that, as in the blastula, so in the ectoderm and in the
+endoderm of our Echinus or of the starfish, the prospective potencies
+are the same for every single element: both in the ectoderm and in
+the endoderm the prospective value of each cell is a “function of its
+position” (Fig. 9).
+
+[Illustration: Fig. 9.--The Starfish, *Asterias*.
+
+*a*^1. Normal gastrula; may be bisected along the main axis or at right
+angles to it (see dotted lines).
+
+*a*^2. Normal larva, “*Bipinnaria*.”
+
+*b*^1. Small but whole gastrula that results by a process of regulation
+from the parts of a bisected gastrula.
+
+*b*^2. Small *but whole* “*Bipinnaria*,” developed out of *b*^1.]
+
+But a further experiment has been made on our gastrula. If at the moment
+when the material of the future intestine is most distinctly marked in
+the blastoderm, but not yet grown into a tube, if at this moment the
+upper half of the larva is separated from the lower by an equatorial
+section, you will get a complete larva only from that part which bears
+the “Anlage” of the endoderm, while the other half will proceed in
+morphogenesis very well but will form only ectodermal organs. By another
+sort of experiment, which we cannot fully explain here, it has been
+shown that the endoderm if isolated is also only able to form such
+organs as are normally derived from it.
+
+And so we may summarise both our last results by saying: though
+ectoderm and endoderm have their potencies equally distributed amongst
+their respective cells, they possess different potencies compared one
+with the other. And the same relation is found to hold for all cases of
+what we call elementary organs: they are “equipotential,” as we may say,
+in themselves, but of different potencies compared with each other.
+
+*Explicit and Implicit Potencies: Primary and Secondary Potencies*
+
+We shall first give to our concept of “prospective potency” a few words
+of further analytical explanation with the help of our newly obtained
+knowledge.
+
+It is clear from what we have stated that the prospective potencies of
+the ectoderm and of the endoderm, and we may add, of every elementary
+organ in relation to every other, differ between themselves and also in
+comparison with the blastoderm, from which they have originated. But the
+diversity of the endoderm with respect to the ectoderm is not of the
+same kind as its diversity in respect to the blastoderm. The potency
+of the endoderm and that of the ectoderm are both specialised in their
+typical manner, but compared with the potency of the blastoderm they
+may be said not only to be specialised but also to be *restricted*: the
+potency of the blastoderm embraces the whole, that of the so-called
+germ-layer embraces only part of the whole; and this species of
+restriction becomes clearer and clearer the further ontogeny advances:
+at the end of it in the “ultimate elementary organs” there is no
+prospective potency whatever.
+
+A few new terms will serve to state a little more accurately what
+happens. Of course, with regard to all morphogenesis which goes on
+*immediately* from the blastoderm, the potency of the blastoderm is
+restricted as much as are the potencies of the germ layers. We shall
+call this sort of immediate potency *explicit*, and then we see at
+once that, with regard to their explicit potencies, there are only
+differences among the prospective potencies of the elementary organs;
+but with respect to the *implicit* potency of any of these organs, that
+is with respect to their potency as embracing the faculties of all their
+derivations, there are also not only differences but true morphogenetic
+restrictions lying at the very foundations of all embryology.
+
+But now those of you who are familiar with morphogenetic facts will
+object to me, that what we have stated about all sorts of restrictions
+in ontogeny is not true, and you will censure me for having overlooked
+regeneration, adventitious budding, and so on. To some extent the
+criticism would be right, but I am not going to recant; I shall only
+introduce another new concept. We are dealing only with *primary*
+potencies in our present considerations, *i.e.* with potencies which
+lie at the root of true embryology, not with those serving to regulate
+disturbances of the organisation. It is true, we have in some way
+disturbed the development of our sea-urchin’s egg in order to study
+it; more than that, it would have been impossible to study it at all
+without some sort of disturbance, without some sort of operation.
+But, nevertheless, no potencies of what may properly be called the
+*secondary* or restitutive type have been aroused by our operations;
+nothing happened except on the usual lines of organogenesis. It is
+true, some sort of regulation occurred, but that is included among the
+factors of ontogeny proper.
+
+We shall afterwards study more fully and from a more general point of
+view this very important feature of “primary regulation” in its contrast
+to “secondary regulation” phenomena. At present it must be enough to
+say that in speaking of the restriction of the implicit potencies in
+form-building we refer only to potencies of the primary type, which
+contain within themselves some properties of a (primary) regulative
+character.
+
+*The Morphogenetic Function of Maturation in the Light of Recent
+Discoveries*
+
+Turning again to more concrete matters, we shall first try, with the
+knowledge acquired of the potencies of the blastoderm and the so-called
+germ layers of Echinus, to understand certain rather complicated
+results which the experimental morphogenetic study of other animal
+forms has taught us. We know from our historical sketch that there are
+some very important aberrations from the type, to which the Echinus
+germ belongs,[27] *i.e.* the type with an equal distribution of the
+potencies over all the blastomeres. We know not only that in cases where
+a regulation of the intimate structure of the protoplasm fails to occur
+a partial development of isolated cells will take place, but that there
+may even be a typical disposition of typical cells for the formation of
+typical organs only, without any regulability.
+
+[27] The reader will remember (see page 65, note 1), that even the germ
+of Echinus is not quite equipotential along its main axis, but it is
+equipotential in the strictest sense around this axis. The germs of
+certain medusae seem to be equipotential in every respect, even in their
+cleavage stages.
+
+Let us first consider the last case, of which the egg of mollusca is a
+good type: here there is no equal distribution of potencies whatever,
+the cleavage-cells of this germ are a sort of real “mosaic” with regard
+to their morphogenetic potentialities. Is this difference between the
+germ of the echinoderms and the molluscs to remain where it is, and
+not to be elucidated any further? Then there would be rather important
+differences among the germs of different animals, at least with regard
+to the degree of the specification of their cleavage cells, or if we
+ascribe differences among the blastomeres to the organisation of the
+fertilised egg ready for cleavage, there would be differences in the
+morphogenetic organisation of the egg-protoplasm: some eggs would be
+more typically specialised at the very beginning of morphogenesis than
+others.
+
+In the first years of the study of “Entwickelungsmechanik” I pointed out
+that it must never be forgotten that the egg itself is the result of
+organogenesis. If, therefore, there are real mosaic-like specifications
+in some eggs at the beginning of cleavage, or during it, there may
+perhaps have been an *earlier* stage in the individual history of
+the egg which did not show such specifications of the morphogenetic
+structure. Two American authors share the merit of having proved
+this hypothesis. Conklin showed, several years ago, that certain
+intracellular migrations and rearrangements of material do happen in
+the first stages of ovogenesis in certain cases, but it is to E. B.
+Wilson[28] that science owes a proper and definitive elucidation of the
+whole subject. Wilson’s researches, pursued not only by descriptive
+methods,[29] but also by means of analytical experiment, led him to the
+highly important discovery that the eggs of several forms (nemertines,
+molluscs), which after maturation show the mosaic type of specification
+in their protoplasm to a more or less high degree, fail to show any
+kind of specification in the distribution of their potencies before
+maturation has occurred. In the mollusc egg a certain degree of
+specification is shown already before maturation, but nothing to be
+compared with what happens afterwards; in the egg of nemertines there is
+no specification at all in the unripe egg.
+
+[28] *Journ. Exp. Zool.* 1, 1904.
+
+[29] Great caution must be taken in attributing any specific
+morphogenetic part to differently coloured or constructed materials,
+which may be observed in the egg-protoplasm in certain cases. They may
+play such a part, but in other cases they certainly do not (see Lyon,
+*Arch. Entw. Mech.* 23, 1907). The final decision always depends on
+experiment.
+
+Maturation thus becomes a part of ontogeny itself; it is not with
+fertilisation that morphogenesis begins, there is a sort of ontogeny
+anterior to fertilisation.
+
+These words constitute a summary of Wilson’s researches. Taken together
+with the general results obtained about the potencies of the blastula
+and the gastrula of Echinus, they reduce what appeared to be differences
+of degree or even of kind in the specification of the egg-protoplasm *to
+mere differences in the time of the beginning of real morphogenesis*.
+What occurs in some eggs, as in those of Echinus, at the time of the
+definite formation of the germ layers, leading to a specification and
+restriction of their prospective potencies, may happen very much earlier
+in other eggs. But there exists in *every* sort of egg an *earliest*
+stage, in which all parts of its protoplasm are equal as to their
+prospectivity, and in which there are no potential diversities or
+restrictions of any kind.
+
+So much for differences in the *real material* organisation of the germ
+and their bearing on inequipotentialities of the cleavage cells.
+
+*The Intimate Structure of Protoplasm: Further Remarks*
+
+Where a typical half- or quarter-development from isolated blastomeres
+happens to occur, we know already that the impossibility of a regulation
+of the *intimate polar-bilateral* structure may account for it. As this
+impossibility of regulation probably rests on rather simple physical
+conditions[30] it may properly be stated that equal distribution of
+potencies is not wanting but is only overshadowed here. In this respect
+there exists a logical difference of fundamental importance between
+those cases of so-called “partial” or better, “fragmental” development
+of isolated blastomeres in which a certain embryonic organ is wanting
+on account of its specific morphogenetic material being absent, and
+those cases in which the “fragmental” embryo lacks complete “halves” or
+“quarters” with regard to general symmetry on account of the symmetry
+of its intimate structure being irregularly disturbed. This logical
+difference has not always received the attention which it undoubtedly
+deserves. Our hypothetical intimate structure in itself is, of course,
+also a result of factors concerned in ovogenesis. Only in one case do
+we actually know anything about its origin: Roux has shown that in the
+frog it is the accidental path of the fertilising spermatozoon in the
+egg which, together with the polar axis, normally determines the plane
+of bilateral symmetry; but this symmetry may be overcome and replaced
+by another, if gravity is forced to act in an abnormal manner upon the
+protoplasm; the latter showing parts of different specific gravity in
+the eggs of all Amphibia.
+
+[30] It seems that these physical conditions also--besides the real
+specifications in the organisation of the egg--may be different before
+and after maturation or (in other cases) fertilisation. (See Driesch,
+*Archiv f. Entwickelungsmechanik*, 7, p. 98; and Brachet, *ibid.* 22, p.
+325.)
+
+*The Neutrality of the Concept of “Potency”*
+
+Now we may close our rather long chapter on the distribution of
+potencies in the germ; it has been made long, because it will prove to
+be very important for further analytical discussion; and its importance,
+in great measure, is due to its freedom from prepossessions. Indeed,
+the concept of prospective potency does not prejudice anything; we
+have said, it is true, that limitations of potencies may be due to
+the presence of specific parts of organisation in some cases; that,
+at least, they may be connected therewith; but we have not determined
+at all what a prospective potency really is, what the term really is
+to signify. It may seem that such a state of things gives an air of
+emptiness to our discussions, that it leaves uncertain what is the most
+important. But, I think, our way of argument, which tries to reach the
+problems of greatest importance by degrees, though it may be slow, could
+hardly be called wrong and misleading.
+
+
+β. THE “MEANS” OF MORPHOGENESIS
+
+We now proceed to an analysis of what may properly be called the *means*
+of morphogenesis, the word “means” being preferable to the more usual
+one “conditions” in this connection, as the latter would not cover the
+whole field. It is in quite an unpretentious and merely descriptive
+sense that the expression “means” should be understood at present; what
+is usually called “conditions” is part of the morphogenetic means in our
+sense.
+
+β′. *The Internal Elementary Means of Morphogenesis*
+
+We know that all morphogenesis, typical or atypical, primary or
+secondary, goes on by one morphogenetic elementary process following the
+other. Now the very foundation of these elementary processes themselves
+lies in the elementary functions of the organism as far as they result
+in the formation of stable visible products. Therefore the elementary
+functions of the organism may properly be called the internal “means” of
+morphogenesis.
+
+Secretion and migration are among such functions; the former happening
+by the aid of chemical change or by physical separation, the latter by
+the aid of changes in surface tension. But hardly anything more concrete
+has been made out about these or similar points at present.
+
+We therefore make no claim to offer a complete system of the internal
+elementary means of morphogenesis. We shall only select from the whole
+a few topics of remarkable morphogenetic interest, and say a few words
+about each.
+
+But, first of all, let us observe that the elementary means of
+morphogenesis are far from being morphogenesis themselves. The word
+“means” itself implies as much. It would be possible to understand each
+of these single acts in morphogenesis as well as anything, and yet to be
+as far from understanding the whole as ever. All means of morphogenesis
+are only to be considered as the most general frame of events within
+which morphogenesis occurs.
+
+*Some Remarks on the Importance of Surface Tension in
+Morphogenesis.*--There are a few purely physical phenomena which have
+a special importance in organic morphology, all of them connected
+with capillarity or surface tension. Soap-lather is a very familiar
+thing to all of you: you know that the soap-solution is arranged here
+in very thin planes separated by spaces containing air: it was first
+proved by Berthold[31] that the arrangement of cells in organic tissues
+follows the same type as does the arrangement of the single bubbles of
+a soap-lather, and Bütschli[32] added to this the discovery that the
+minute structure of the protoplasm itself is that of a foam also. Of
+course it is not one fluid and one gas which make up the constituents
+of the structure in the organisms, as is the case in the well-known
+inorganic foams, but two fluids, which do not mix with one another. One
+general law holds for all arrangements of this kind: the so-called law
+of least surfaces, expressed by the words that the sum of all surfaces
+existing is a minimum; and it again is a consequence of this law, if
+discussed mathematically, that four lines will always meet in one point
+and three planes in one line. This feature, together with a certain law
+about the relation of the angles meeting in one line to the size of the
+bubbles, is realised most clearly in many structures of organic tissues,
+and makes it highly probable, at least in some cases, that capillarity
+is at work here. In other cases, as for instance in many plants, a kind
+of outside pressure, the so-called tissue tension, may account for the
+arrangement in surfaces *minimae areae*. Cleavage stages are perhaps
+the very best type in which our physical law is expressed: and here
+it may be said to have quite a simple application whenever all of the
+blastomeres are of the same physical kind, whilst some complications
+appear in germs with a specialised organisation and, therefore,
+with differences in the protoplasm of their single blastomeres. In
+such instances we may say that the physical law holds as far as the
+conditions of the system permit, these conditions ordinarily consisting
+in a sort of non-homogeneity of the surfaces.
+
+[31] *Studien über Protoplasmamechanik*, Leipzig, 1886.
+
+[32] *Unters. üb. mikroskopische Schäume und das Protoplasma*, Leipzig,
+1892.
+
+It seems, from the researches of Dreyer,[33] that the formation of
+organic skeletons may also be governed by the physically conditioned
+arrangement of protoplasmatic or cellular elements, and some phenomena
+of migration and rearrangement among cleavage cells, as described by
+Roux, probably also belong here.
+
+[33] *Jena. Zeitschr.* 26, 1892.
+
+But let us never forget that the laws of surface tension only give
+us the most general type of an arrangement of elements in all these
+cases, nothing else. A physical law never accounts for the Specific!
+Capillarity gives us not the least clue to it. As the organic substance,
+at least in many cases, is a fluid, it must of course follow the general
+laws of hydrostatics and hydrodynamics, but life itself is as little
+touched by its fluid-like or foam-like properties as it is by the fact
+that living bodies have a certain weight and mass.
+
+All indeed that has been described may be said to belong, in the
+broadest meaning of the word, to what is called by Roux “correlation of
+masses,” though this author originally intended to express by this term
+only some sorts of passive pressure and deformation amongst embryonic
+parts as discovered especially by His.
+
+We must be cautious in admitting that any organic feature has been
+explained, even in the most general way, by the action of physical
+forces. What at first seems to be the result of mechanical pressure may
+afterwards be found to be an active process of growth, and what at first
+seems to be a full effect of capillarity among homogeneous elements may
+afterwards be shown to depend on specialised metabolic conditions of the
+surfaces as its principal cause.[34]
+
+[34] According to Zur Strassen’s results the early embryology of
+*Ascaris* proceeds almost exclusively by cellular surface-changes: the
+most typical morphogenetic processes are carried out by the aid of this
+“means.” As a whole, the embryology of *Ascaris* stands quite apart and
+presents a great number of unsolved problems; unfortunately, the germ of
+this form has not been accessible to experiment hitherto.
+
+There are other physical phenomena too, which assist morphogenesis;
+osmotic pressure for instance, which is also well known to operate in
+many purely physiological processes. But all these processes are only
+means of the organism, and can never do more than furnish the general
+type of events. They do not constitute life; they are *used* by life;
+let it remain an open question, for the present, how the phenomenon of
+“life” is to be regarded in general.[35]
+
+[35] Rhumbler has recently published a general survey of all attempts to
+“explain” life, and morphogenesis in particular, in a physico-chemical
+way (“Aus dem Lückengebiet zwischen organismischer und anorganismischer
+Natur,” *Ergeb. Anat. u. Entw.-gesch.* 15, 1906). This *very
+pessimistic* survey is the more valuable as it is written by a convinced
+“mechanist.”
+
+*On Growth*.--Among the internal morphogenetical means which are of
+a so-called physiological character, that is, which nobody claims to
+understand physically at present, there is in the first place *growth*,
+which must be regarded as a very essential one.
+
+Analytically we must carefully discriminate between the increase in the
+size of the cavities of an organism by a passive extension of their
+surfaces and the proper growth of the individual cells, which again
+may be due either to mere extension or to real assimilation. Osmotic
+pressure, of course, plays an important part both in the growth of the
+body-cavities and in simple cellular extension. We repeat the caution
+against believing too much to be explained by this phenomenon: it is the
+organism which by the secretion of osmotic substances in the cavities or
+the protoplasm of the cells prepares the ground for growth even of this
+osmotic sort. The real cellular growth which proceeds on the basis of
+assimilation cannot, of course, be accounted for by osmotic events, not
+even in its most general type.
+
+Ontogenetical growth generally sets in, both in animals and in plants,
+after the chief lines of organisation are laid out; it is only the
+formation of the definite histological structures which usually runs
+parallel to it.
+
+*On Cell-division.*--We have already said a good deal about the
+importance of cell-division in ontogeny: it accompanies very many of the
+processes of organisation in all living beings. But even then, there are
+the Protozoa, in the morphogenesis of which it does not occur at all,
+and there have also become known many cases of morphogenesis in higher
+animals, mostly of the type of regulation, in which cellular division
+is almost or wholly wanting. Therefore, cellular division cannot be
+the true reason of differentiation, but is only a process, which
+though necessary in some cases, cannot be essential to it. It must be
+conceded, I believe, that the same conclusion can be drawn from all our
+experiments on very young stages of the germ.
+
+The investigations of the last few years have made it quite clear that
+even in organisms with a high power of morphogenetic regulation it is
+always the form of the whole, but not the individual cell, which is
+subjected to the regulation processes. Starting from certain results
+obtained by T. H. Morgan, I was able to show that in all the small but
+whole larvae, reared from isolated blastomeres, the size of the cells
+remains normal, only their number being reduced; and Boveri has shown
+most clearly that it is always the size of the nucleus--more correctly,
+the mass of the chromatin--which determines how large a cell of a
+certain histological kind is to be. In this view, the cell appears even
+more as a sort of material used by the organism as supplied, just as
+workmen can build the most different buildings with stones of a given
+size.
+
+
+β″. *The External Means of Morphogenesis*
+
+We now know what internal means of morphogenesis are, and so we may
+glance at some of the most important “outer means” or “conditions” of
+organisation.
+
+Like the adult, the germ also requires a certain amount of heat, oxygen,
+and, when it grows up in the sea, salinity in the medium. For the germ,
+as for the adult, there exists not only a minimum but also a maximum
+limit of all the necessary factors of the medium; the same factor which
+at a certain intensity promotes development, disturbs it from a certain
+other intensity upwards.
+
+Within the limits of this minimum and this maximum of every outside
+agent there generally is an increase in the rate of development
+corresponding to the increase of intensity of the agent. The
+acceleration of development by heat has been shown to follow the law of
+the acceleration of chemical processes by a rise of temperature; that
+seems to prove that certain chemical processes go on during the course
+of morphogenesis.
+
+Almost all that has been investigated of the part played by the external
+conditions of development has little bearing on specific morphogenesis
+proper, and therefore may be left out of account here: we must, however,
+lay great stress on the general fact that there *is* a very close
+dependence of morphogenesis on the outside factors, lest we should be
+accused afterwards of having overlooked it.
+
+Of course all “external” means or conditions of morphogenesis can
+actually relate to morphogenetic processes only by becoming in some way
+“internal,” but we unfortunately have no knowledge whatever how this
+happens. We at present are only able to ascertain what must necessarily
+be accomplished in the medium, in order that normal morphogenesis may go
+on, and we can only suppose that there exist certain specific internal
+general states, indispensable for organogenesis but inaccessible to
+present modes of investigation.[36]
+
+[36] Compare the analytical discussions of Klebs, to whom we owe a great
+series of important discoveries in the field of morphogenetic “means”
+in botany. (*Willkürliche Entwickelungsänderungen bei Pflanzen*, Jena,
+1903; see also *Biol. Centralblatt*, vol. xxiv., 1904, and my reply to
+Klebs, *ibid.* 23, 1903.)
+
+*The Discoveries of Herbst.*--There are but few points in the doctrine
+of the external means or conditions of organogenesis which have a
+more special bearing on the specification of proper form, and which
+therefore require to be described here a little more fully. All
+these researches, which have been carried out almost exclusively by
+Herbst,[37] relate to the effect of the chemical components of sea-water
+upon the development of the sea-urchin. If we select the most important
+of Herbst’s results, we must in the first place say a few words on
+the part taken by lime or calcium, not only in establishing specific
+features of form, but in rendering individual morphogenesis possible at
+all. Herbst has found that in sea-water which is deprived of calcium the
+cleavage cells and many tissue cells also completely lose contact with
+each other: cleavage goes on quite well, but after each single division
+the elements are separated; at the end of the process you find the 808
+cells of the germ together at the bottom of the dish, all swimming about
+like infusoria. There seems to be some influence of the calcium salts
+upon the physical state of the surfaces of the blastomeres.
+
+[37] *Arch. Entw. Mech.* 17, 1904.
+
+It is not without interest to note that this discovery has an important
+bearing on the technical side of all experiments dealing with the
+isolation of blastomeres. Since the separation of the single cleavage
+elements ceases as soon as the germs are brought back from the mixture
+without lime into normal sea-water, it of course is possible to separate
+them up to any stage which it is desired to study, and to keep them
+together afterwards. Thus, if for instance you want to study the
+development of isolated cells of the eight-cell stage, you will leave
+the egg in the artificial mixture containing no calcium until the
+third cleavage, which leads from the four- to the eight-cell stage, is
+finished. The single eight cells brought back to normal sea-water at
+this point will give you the eight embryos you want. All researches
+upon the development of isolated blastomeres since the time of Herbst’s
+discovery have been carried out by this method, and it would have been
+quite impossible by the old method of shaking to pursue the study into
+such minute detail as actually has been done. It may be added that
+calcium, besides its cell-uniting action, is also of primary importance
+in the formation of the skeleton.
+
+Among all the other very numerous studies of Herbst we need only mention
+that potassium is necessary for the typical growth of the intestine,
+just as this element has been found necessary for normal growth in
+plants, and that there must be the ion SO_4, or in other terms,
+sulphur salts present in the water, in order that the germs may acquire
+their pigments and their bilateral symmetry. This is indeed a very
+important result, though it cannot be said to be properly understood. It
+is a fact that in water without sulphates the larvae of Echinus retain
+the radial symmetry they have had in the very earliest stages, and may
+even preserve that symmetry on being brought back to normal sea-water if
+they have spent about twenty-four hours in the artificial mixture.
+
+We may now leave the subject of Herbst’s attempts to discover the
+morphogenetic function of the single constituents of normal sea-water,
+and may devote a few words to the other branch of his investigations,
+those dealing with the morphogenetic effects of substances which are not
+present in the water of the sea, but have been added to it artificially.
+Here, among many other achievements, Herbst has made the most
+important discovery that all salts of lithium effect radical changes
+in development.[38] I cannot describe fully here how the so-called
+“lithium larva” originates; let me only mention that its endoderm is
+formed outside instead of inside, that it is far too large, that there
+is a spherical mass between the ectodermal and the endodermal part of
+the germ, that a radial symmetry is established in place of the normal
+bilateralism, that no skeleton exists, and that the mesenchyme cells
+are placed in a quite abnormal position. All these features, though
+abnormal, are typical of the development in lithium. The larvae present
+no really pathological appearance at all, and, therefore, it may indeed
+be said that lithium salts are able to change fundamentally the whole
+course of morphogenesis. It detracts nothing from the importance of
+these discoveries that, at present, they stand quite isolated: only with
+lithium salts has Herbst obtained such strange results, and only upon
+the eggs of echinids, not even upon those of asterids, do lithium salts
+act in this way.
+
+[38] *Zeitschr. wiss. Zool.* 55, 1902; and *Mitt. Neapel.* 11, 1903.
+
+
+γ. THE FORMATIVE CAUSES OR STIMULI
+
+*The Definition of Cause*
+
+We cannot begin the study of the “causes” of the differentiation of
+form without a few words of explanation about the terminology which we
+shall apply. Causality is the most disputed of all categories; many
+modern scientists, particularly in physics, try to avoid the concept of
+cause altogether, and to replace it by mere functional dependence in
+the mathematical meaning of the term. They claim to express completely
+by an equation all that is discoverable about any sort of phenomena
+constantly connected.
+
+I cannot convince myself that such a very restricted view is the right
+one: it is very cautious, no doubt, but it is incomplete, for we *have*
+the concept of the acting “cause” in our Ego and are *forced* to search
+for applications of it in Nature. On the other hand, it does not at all
+escape me that there are many difficulties, or rather ambiguities, in
+applying it.
+
+We may call the “cause” of any event, the sum total of all the
+constellations of facts which must be completed in order that the event
+may occur; it is in this meaning, for instance, that the first principle
+of energetics applies the term in the words *causa aequat effectum*.
+But, by using the word only in this very general sense, we deprive
+ourselves of many conveniences in the further and more particular study
+of Nature. Would it be better to say that the “cause” of any event is
+the very last change which, after all the constellations necessary for
+its start are accomplished, must still take place in order that the
+event may actually occur? Let us see what would follow from such a use
+of the word causality. We here have an animal germ in a certain stage,
+say a larva of Echinus, which is just about to form the intestine; all
+the internal conditions are fulfilled, and there is also a certain
+temperature, a certain salinity, and so on, but there is no oxygen in
+the water: the intestine; of course, will not grow in such a state of
+things, but it soon will when oxygen is allowed to enter the dish.
+Is, therefore, oxygen the cause of the formation of the intestine of
+echinus? Nobody, I think, would care to say so. By such reasoning,
+indeed, the temperature, or sodium, might be called the “cause” of
+any special process of morphogenesis. It, therefore, seems to be of
+little use to give the name of cause to that factor of any necessary
+constellation of events which accidentally happens to be the last that
+is realised. But what is to be done then?
+
+Might we not say that the cause of any morphogenetic process is that
+typical property, or quality, or change, on which its specific character
+depends, on which depends for example, the fact that now it is the
+intestine which appears, while at another time it is the lens of the
+eye? We might very well, but we already have our term for this sort
+of cause, which is nothing else than our prospective potency applied
+to that elementary organ from which the new process takes its origin.
+The prospective potency indeed is the truly immanent cause of every
+specification affecting single organogenetic processes. But we want
+something more than this.
+
+We may find what we want by considering that each single elementary
+process or development not only has its specification, but also has
+its specific and typical place in the whole--its locality. Therefore
+we shall call the “cause” of a single morphogenetic process, that
+occurrence on which depends its *localisation*, whether its specific
+character also partly depends on this “cause” or not.[39]
+
+[39] In certain cases part of the specific feature of the process in
+question may also depend on the “cause” which is localising it, *e.g.*
+in the galls of plants.
+
+This definition of “cause” in morphology may be artificial; in any
+case it is clear. And at the same time the concepts of the prospective
+potency and of the “means” of organogenesis now acquire a clear and
+definite meaning: potency is the real basis of the specific character
+of every act in morphogenesis, and “means,” including conditions, are
+the sum of all external and internal general circumstances which must be
+present in order that morphogenetic processes may go on, without being
+responsible for their specificity or localisation.
+
+It is implied in these definitions of cause and potency, that the former
+almost always will be of that general type which usually is called a
+stimulus or “Auslösung,” to use the untranslatable German word. There is
+no quantitative correspondence between our “cause” and the morphogenetic
+effect.
+
+*Some Instances of Formative and Directive Stimuli*
+
+Again it is to Herbst that we owe not only a very thorough logical
+analysis of what he calls “formative and directive stimuli”[40] but also
+some important discoveries on this subject. We cannot do more here than
+barely mention some of the most characteristic facts.
+
+[40] Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale
+Auffassung von Vorgängen in der tierischen Ontogenese” (*Biol.
+Centralblatt*, vols. xiv., 1894, and xv., 1895); *Formative Reize in der
+tierischen Ontogenese*, Leipzig, 1901. These important papers must be
+studied by every one who wishes to become familiar with the subject. The
+present state of science is reviewed in my articles in the *Ergebnisse
+der Anatomie und Entwickelungsgeschichte*, vols. xi. and xiv., 1902 and
+1905.
+
+Amongst plants it has long been known that the direction of light or of
+gravity may determine where roots or branches or other morphogenetic
+formations are to arise; in hydroids also we know that these factors
+of the medium may be at work[41] as morphogenetic causes, though most
+of the typical architecture of hydroid colonies certainly is due to
+internal causes, as is also much of the organisation in plants.
+
+[41] Compare the important papers by J. Loeb, *Untersuchungen zur
+physiologischen Morphologie der Tiere*, Würzburg, 1891-2.
+
+Light and gravity are external formative causes; beside that they are
+merely “localisers.” But there also are some external formative stimuli,
+on which depends not only the place of the effect, but also part of its
+specification. The galls of plants are the most typical organogenetic
+results of such stimuli. The potencies of the plant and the specific
+kind of the stimulus equally contribute to their specification; for
+several kinds of galls may originate on one sort of leaves.
+
+Scarcely any exterior formative stimuli are responsible for animal
+organisation; and one would hardly be wrong in saying that this
+morphogenetic independence in animals is due to their comparatively
+far-reaching functional independence of those external agents which
+have any sort of direction. But many organogenetic relations are known
+to exist between the single parts of animal germs, each of these parts
+being in some respect external to every other; and, indeed, it might
+have been expected already *a priori*, that such formative relations
+between the parts of an animal embryo must exist, after all we have
+learned about the chief lines of early embryology. If differentiation
+does not go on after the scheme of Weismann, that is, if it is not
+carried out by true “evolutio” from within, how could it be effected
+except from without? Indeed, every embryonic part may in some respect be
+a possible cause for morphogenetic events, which are to occur on every
+other part: it is here that the very roots of epigenesis are to be found.
+
+Heliotropism and geotropism are among the well-known physiological
+functions of plants: the roots are seen to bend away from the light and
+towards the ground; the branches behave just in the opposite way. It now
+has been supposed by Herbst that such “directive stimuli” may also be
+at work among the growing or wandering parts of the embryo, that their
+growth or their migration may be determined by the typical character of
+other parts, and that real morphogenetic characters can be the result of
+some such relation; a sort of “chemotropism” or “chemotaxis” may be at
+work here. Herbst himself has discussed theoretically several cases of
+organogenesis in which the action of directive stimuli is very probable.
+What has become actually known by experiment is not very much at
+present: the mesenchyme cells of Echinus are directed in their migration
+by specified places in the ectoderm, the pigment cells of the yolk-sac
+of the fish fundulus are attracted by its blood vessels, and nerves
+may be forced to turn into little tubes containing brain substance;
+but of course only the first two instances have any bearing on typical
+morphogenesis.
+
+The first case of an “internal formative stimulus” in the proper sense,
+that is, of one embryonic part causing another to appear, was discovered
+by Herbst himself. The arms of the so-called pluteus of the sea-urchin
+are in formative dependence on the skeleton--no skeleton, no arms; so
+many skeleton primordia,[42] in abnormal cases, so many arms; abnormal
+position of the skeleton, abnormal position of the arms: these three
+experimental observations form the proof of this morphogenetic relation.
+
+[42] I use the word “primordia” for the German “Anlage”; it is better
+than the word “rudiment,” as the latter may also serve to signify
+the very last stage of a certain formation that is disappearing
+(phylogenetically).
+
+It may be simple mechanical contact, or it may be some chemical
+influence that really constitutes the “stimulus” in this case;
+certainly, there exists a close and very specific relation of the
+localisation of one part of the embryo to another. Things are much the
+same in another case, which, after having been hypothetically stated
+by Herbst on the basis of pathological data, was proved experimentally
+by Spemann. The lens of the eye of certain Amphibia is formed of their
+skin in response to a formative stimulus proceeding from the so-called
+primary optic vesicle. If this vesicle fails to touch the skin, no lens
+appears; and, on the other hand, the lens may appear in quite abnormal
+parts of the skin if they come into contact with the optic vesicle after
+transplantation.
+
+But formative dependence of parts may also be of different types.
+
+We owe to Herbst the important discovery that the eyes of crayfishes,
+after being cut off, will be regenerated in the proper way, if the optic
+ganglion is present, but that an antenna will arise in their place
+if this ganglion has also been removed. There must in this case be
+some unknown influence of the formative kind on which depends, if not
+regeneration itself, at least its special character.
+
+In other cases there seems to be an influence of the central nervous
+system on the regenerative power in general. Amphibia, for instance,
+are said to regenerate neither their legs (Wolff), nor their tail
+(Godlewski), if the nervous communications have been disturbed. But
+in other animals there is no such influence; and in yet others, as
+for instance, in Planarians, it must seem doubtful at present whether
+the morphogenetic influence of the nervous system upon processes of
+restoration is more than indirect; the movements of the animal, which
+become very much reduced by the extirpation of the ganglia, being one of
+the main conditions of a good regeneration.
+
+Of course, all we have said about the importance of special materials
+in the ripe germ, as bearing on specifically localised organisations,
+might be discussed again in our present chapter, and our intimate
+polar-bilateral structure of germs may also be regarded as embracing
+formative stimuli, at any rate as far as the actual poles of this
+structure are concerned. This again would bring us to the problem of
+so-called “polarity” in general, and to the “inversion” of polarity,
+that is to a phenomenon well known in plants and in many hydroids and
+worms, viz., that morphogenetic processes, especially of the type of
+restitutions, occur differently, according as their point of origin
+represents, so to speak, the positive or the negative, the terminal or
+the basal end of an axis, but that under certain conditions the reverse
+may also be the case. But a fuller discussion of these important facts
+would lead us deeper and deeper into the science of morphogenesis
+proper, without being of much use for our future considerations.
+
+And so we may close this section[43] on formative stimuli or “causes”
+of morphogenesis by shortly adding, more on account of its factual
+than of its logical interest, that the phenomenon of the determination
+of sex,[44] according to the latest researches, seems to depend on
+cytological events occurring in the very earliest embryonic stages,
+say even before ontogeny, and not on formative stimuli proper[45]: it
+seems, indeed, as if the sexual products themselves would account for
+the sex of the individual produced by them, particularly if there were
+differences in their chromatin.[46]
+
+[43] A full analysis of the subject would not only have to deal with
+formative stimuli as inaugurating morphogenetic processes, but also with
+those stimuli which terminate or stop the single acts of morphogenesis.
+But little is actually known about this topic, and therefore the reader
+must refer to my other publications. I will only say here, that the end
+of each single morphogenetic act may either be determined at the very
+beginning or occur as an actual stopping of a process which otherwise
+would go on for ever and ever; in the first case some terminating
+factors are included in the very nature of the morphogenetic act itself.
+
+[44] A full account of the present state of the subject will be found in
+Morgan’s *Experimental Zoology*, New York, 1907.
+
+[45] But there certainly exist many formative relations between the real
+sexual organs and the so-called secondary sexual characters. Herbst has
+given a full analytical discussion of all that is known on this subject;
+but the facts are much more complicated than is generally supposed, and
+do not lend themselves therefore to short description. See also Foges,
+*Pflüger’s Arch.* 93, 1902.
+
+[46] It seems that in some cases (*Dinophilus*, certain Arthropods)
+the sexual products are invariably determined as “arrenogennetic”
+or as “thelygennetic” (Wilson, *Journ. Exp. Zool.* ii. and iii.
+1905-6), whilst in others (Amphibia) the state of maturation or
+“super”-maturation determines the sex of the future organism (R.
+Hertwig, *Verh. D. Zool. Ges.* 1905-7).
+
+
+δ. THE MORPHOGENETIC HARMONIES
+
+Let us now turn again to considerations of a more abstract kind: we have
+become acquainted with some morphogenetic interactions among the parts
+of a developing embryo; and, indeed, we can be sure that there exist far
+more of such interactions than we know at present.
+
+But it is far from being true that the development of each embryonic
+part depends on the existence or development of every other one.
+
+On the contrary, it is a very important and fundamental feature
+of organogenesis that it occurs in separate lines, that is to
+say, in lines of processes which may start from a common root, but
+which are absolutely independent of one another in their manner of
+differentiation. Roux has coined the term “self-differentiation” to
+denote this phenomenon, and we admit that this term may be conveniently
+used for the purpose, if only it can be kept in mind that its sense is
+always relative, and that it is also negative. Suppose a part, *A*,
+shows the phenomenon of self-differentiation: this means that the
+further development of *A* is not dependent on certain other parts,
+*B*, *C*, and *D*; it does *not* mean at all that *A* has not been
+formatively dependent on some other parts, *E* or *F* at the time of
+its first appearance, nor does it imply that there might not be many
+formative actions among the constituents of *A* itself.
+
+We indeed are entitled to say that the ectoderm of Echinus shows
+“self-differentiation” with regard to the endoderm; it acquires its
+mouth, for instance, as has been shown by experiment, even in cases
+where no intestine is present at all (Fig. 10); but ectoderm and
+endoderm both are formatively dependent on the intimate and the material
+organisation of the blastoderm. It further seems from the most recent
+experiments that the nerves and the muscles of the vertebrates are
+independent of each other in their differentiation, but that their fate
+is probably determined by formative processes in the very earliest
+stages of ontogeny.
+
+[Illustration: Fig. 10.--Pluteus-larva of Sphaerechinus.
+
+The Intestine (i) is developed outside instead of inside (by means of
+raising the temperature); but the mouth (r) is formed in its normal
+place. S = Skeleton.]
+
+The phenomenon of self-differentiation, properly understood, now may
+help to the discovery of one most general character of all development.
+If the phenomenon of self-differentiation really occurs in ontogeny
+in its most different aspects, and if, on the other hand, in spite
+of this relative morphogenetic independence of embryonic parts, the
+resulting organism is one whole in organisation and in function, some
+sort of *harmony of constellation*, as it may properly be styled, must
+be said to be one of the most fundamental characters of all production
+of individual form. In establishing this harmony we do nothing more
+than describe exactly what happens: the harmony is shown by the fact
+that there is a whole organism at the end, in spite of the relative
+independence of the single events leading to it.
+
+But still another sort of harmony is revealed in morphogenesis, by an
+analysis of the general conditions of the formative actions themselves.
+In order that these actions may go on properly the possibility must be
+guaranteed that the formative causes may always find something upon
+which to act, and that those parts which contain the potencies for the
+next ontogenetic stage may properly receive the stimuli awaking these
+potencies: otherwise there would be no typical production of form at
+all. This, the second species of harmonious relations to be described in
+ontogeny, may be called *causal harmony*; the term simply expresses the
+unfailing relative condition of formative causes and cause-recipients.
+
+Finally, in *functional harmony* we have an expression descriptive
+of the unity of organic function, and so we may state, as the latest
+result of our analytical theory of development up to this point, that
+individual morphogenesis is marked by a *threefold harmony* among its
+parts.
+
+
+ε. ON RESTITUTIONS[47]
+
+[47] Driesch, *Die organischen Regulationen*, Leipzig, 1901; Morgan,
+*Regeneration*, New York, 1901.
+
+At this stage we leave for a while our analytical studies of ontogeny
+proper. We must not forget that typical ontogenesis is not the only form
+in which morphogenesis can occur: the organic form is able to restore
+disturbances of its organisation, and it certainly is to be regarded as
+one of the chief problems of analytical morphogenesis to discover the
+specific and real stimulus which calls forth the restoring processes.
+For simply to say that the disturbance is the cause of the restoration
+would be to evade the problem instead of attacking it. But there are
+still some other problems peculiar to the doctrine of restitutions.
+
+*A few Remarks on Secondary Potencies and on Secondary Morphogenetic
+Regulations in General*
+
+We have only briefly mentioned in a previous chapter that there
+exist many kinds of potencies of what we call the secondary or truly
+restitutive type, and that their distribution may be most various and
+quite independent of all the potencies for the primary processes
+of ontogeny proper. Let us first add a few words about the concept
+of “secondary restitution” and about the distribution of secondary
+potencies in general.
+
+Primary ontogenetic processes founded upon primary potencies may *imply*
+regulation, or more correctly, restitution in many cases: so it is,
+when fragments of the blastula form the whole organism, or when the
+mesenchyme cells of Echinus reach their normal final position by an
+attraction on the part of specific localities of the ectoderm in spite
+of a very abnormal original position enforced upon them by experiment.
+In these cases we speak of primary regulations or restitutions;
+disturbances are neutralised by the very nature of the process in
+question. We speak of secondary restitution whenever a disturbance
+of organisation is rectified by processes foreign to the realm of
+normality; and these abnormal lines of events are revealed to us in the
+first place by the activity of potencies which remain latent in ontogeny
+proper.
+
+We know already that a certain kind of secondary restitution has
+been discovered lately, very contradictory to the theoretical views
+of Weismann; the process of restoration being carried out not by any
+definite part of the disturbed organisation, but by all the single
+elements of it. The problem of the distribution of secondary potencies
+in these cases of so-called “re-differentiation” is to form our special
+study in the next chapter. In all other cases restoration processes
+start from specific localities; if they occur on the site of the
+wound which caused the disturbance, we speak of regeneration; if they
+occur at some distance from the wound, we call them adventitious
+processes. Besides these three types of processes of restitution there
+may be mentioned a fourth one, consisting in what is generally called
+compensatory hypertrophy; the most simple case of such a compensatory
+process is when one of a pair of organs, say a kidney, becomes larger
+after the other has been removed.[48] Finally, at least in plants, a
+change of the directive irritability, of so-called “geotropism” for
+instance, in certain parts may serve to restore other more important
+parts.
+
+[48] But real compensatory differentiation occurs in the cases of
+so-called “hypertypy” as first discovered by Przibram and afterwards
+studied by Zeleny: here the two organs of a pair show a different degree
+of differentiation. Whenever the more specialised organ is removed the
+less developed one assumes its form. Similar cases, which might simply
+be called “compensatory heterotypy,” are known in plants, though only
+relating to the actual fate of undifferentiated “Anlagen” in these
+organisms. A leaf may be formed out of the Anlage of a scale, if all the
+leaves are cut off, and so on.
+
+In two of these general types of restitution, in regeneration proper and
+in the production of adventitious organs, the potencies which underlie
+these processes may be said to be “complex.” It is a complicated series
+of events, a proper morphogenesis in itself, for which the potency
+has to account, if, for instance, a worm newly forms its head by
+regeneration, or if a plant restores a whole branch in the form of an
+adventitious bud.
+
+Such generalisations as are possible about the distribution of complex
+potencies are reserved for a special part of our future discussion.
+
+Secondary restitution is always, like ontogeny, a process of
+morphogenesis, and therefore all the questions about single formative
+stimuli, and about internal and external conditions or means, occur
+again. But of course we cannot enter into these problems a second time,
+and may only say that, especially in regeneration proper, the specific
+type of the regenerative formation of any part may differ very much from
+the ontogenetic type of its origin: the end of both is the same, but the
+way can be even fundamentally different in every respect.
+
+*The Stimuli of Restitutions*[49]
+
+[49] For a fuller analysis compare my opening address delivered before
+the section of “Experimental Zoology” at the Seventh Zoological
+Congress, Boston, 1907: “The Stimuli of Restitutions” (see Proceedings
+of that Congress).
+
+But now we turn to the important question: what is the precise
+stimulus[50] that calls forth processes of restitution; or, in other
+words, what must have happened in order that restitution may occur?
+
+[50] The problem of the stimulus of a secondary restitution as a
+whole must not be confused with the very different question, what the
+single “formative stimuli” concerned in the performance of a certain
+restitutive act may be. With regard to restitution as a *whole* these
+single “formative stimuli” might properly be said to belong to its
+“internal means”--in the widest sense of the word.
+
+That the operation in itself, by its removing of mechanical obstacles,
+cannot be the true stimulus of any restitutions, is simply shown by all
+those restitutions that do not happen at the place of the wound. If we
+took a narrower point of view, and if we only considered regeneration
+proper from the wound itself, we might probably at first be inclined to
+advocate the doctrine that the removing of some obstacles might in fact
+be the stimulus to the process of restoration; but, even then, why is
+it that just what is wanted grows out? Why is there not only growth,
+but specific growth, growth followed by specification? The removing
+of an obstacle could hardly account for that. But, of course, taking
+account of all the adventitious restitutions--that is, all restorations
+not beginning at the wound itself--the theory that the removing of
+obstacles is the stimulus to restoration becomes, as we have said, quite
+impossible.[51]
+
+[51] T. H. Morgan is very right in stating that, in regeneration, the
+“obstacle” itself is newly formed by the mere process of healing,
+previous to all restitution, and that true restitution happens all the
+same.
+
+But where then is the stimulus to be found? There is another rather
+simple theory of the “Auslösung” of restitutions,[52] which starts
+from the phenomena of compensatory hypertrophy and some occurrences
+among plants. The removal of some parts of the organism, it is said,
+will bring its other parts into better conditions of nutrition, and
+therefore these parts, particularly if they are of the same kind, will
+become larger. Granted for the moment that such a view may hold in cases
+when one of a pair of glands becomes larger after the other has been
+removed, or when pruning of almost all the leaves of a tree leads to the
+rest becoming larger, it certainly must fail to explain the fact that
+in other cases true *new* formations may arise in order to restore a
+damaged part, or that the latter may be regenerated in its proper way.
+For *merely quantitative* differences in the mixture of the blood or of
+the nourishing sap in plants can never be a sufficient reason for the
+highly typical and *qualitative* structure of newly-formed restitutions.
+And even in the most simple cases of a mere increase in the size of
+some parts, that is, in the simplest cases of so-called compensatory
+hypertrophy,[53] it is at least doubtful, if not very improbable, that
+the compensation is accomplished in such a purely passive way, because
+we know that in other cases it is usually the growth of the young parts
+that actively attracts the nourishment: there is first differentiation
+and growth, and *afterwards* there is a change in the direction of the
+nourishing fluids.
+
+[52] I merely mention here the still “simpler” one--applicable of course
+to regeneration proper exclusively--that for the simple reason of being
+“wounded,” *i.e.* being a surface open to the medium, the “wound” brings
+forth all that is necessary to complete the organism.
+
+[53] That compensatory hypertrophy cannot be due to “functional
+adaptation”--to be analysed later on--was proved by an experiment of
+Ribbert’s. Compensation may occur before the function has made its
+appearance, as was shown to be the case in the testicles and mammae of
+rabbits. (*Arch. Entw. Mech.* 1, 1894, p. 69.)
+
+The process of true regeneration, beginning at the locality of the wound
+itself, has been shown by Morgan, even as regards its rate, to occur
+quite irrespectively of the animal being fed or not.[54] There could
+hardly be a better demonstration of the fundamental fact that food
+assists restitution, but does not “cause” it in any way.
+
+[54] At any given time only the absolute size of the regenerated part is
+greater in animals which are well fed; the degree of differentiation is
+the same in all. Zeleny has found that, if all five arms of a starfish
+are removed, each one of them will regenerate more material in a given
+time than it would have done if it alone had been removed. But these
+differences also only relate to absolute size and not to the degree
+of differentiation. They possibly may be due in fact to conditions of
+nourishment, but even here other explanations seems possible (Zeleny,
+*Journ. exp. Zool.* 2, 1905).
+
+But in spite of all we have said, there seems to be some truth in
+regarding the nutritive juices of animals and plants as somehow
+connected with the stimulus of restitutions: only in this very cautious
+form, however, may we make the hypothesis. It has been shown for both
+animals and plants, that morphogenesis of the restitutive type may be
+called forth even if the parts, now to be “regenerated” have not been
+actually removed; *e.g.* in the so-called super-regeneration of legs
+and tails in Amphibia, of the head in Planarians, of the root-tip in
+plants and in some other cases. Here it has always been a disturbance
+of the normal connection of some parts with the rest of the organism
+which proved to be the reason of the new formation. This shows that
+something to do with the communication among parts is at least connected
+with restitution, and this communication may go on either by the unknown
+action of specific tissues or by the aid of the blood or sap.[55] But
+in what this change or break of specific communication consists, is
+absolutely unknown. One might suppose that each part of the organisation
+constantly adds some sort of ferment to the body fluids outside or
+inside the cells, that the removing of any part will change the
+composition of these fluids in this particular respect, and that this
+change acts as a sort of communication to summon the restituting parts
+of the whole to do their duty.[56]
+
+[55] For a good discussion of “super-regeneration” in the roots of
+plants see Němec, *Studien über die Regeneration*, Berlin, 1905. Goebel
+and Winkler have succeeded in provoking the “restitution” of parts which
+were not removed at all by simply stopping their functions (leaves of
+certain plants were covered with plaster, etc.). (*Biol. Centralbl.* 22,
+1902, p. 385; *Ber. Bot. Ges.* 20, 1902, p. 81.) A fine experiment is
+due to Miehe. The alga *Cladophora* was subjected to “plasmolysis,” each
+cell then formed a new membrane of its own around the smaller volume of
+its protoplasm; after that the plants were brought back to a medium of
+normal osmotic pressure, and then each single cell grew up into a little
+plant (all of them being of the same polarity!). Two questions seem
+to be answered by this fact: loss of communication is of fundamental
+importance to restitution, and the removal of mechanical obstacles plays
+no part in it, for the mechanical resistances were the same at the end
+of the experiment as they had been at the beginning. (*Ber. Bot. Ges.*
+23, 1905, p. 257.) For fuller analysis of all the problems of this
+chapter see my Organische Regulationen, my reviews in the *Ergebnisse
+der Anatomie und Entwickelungsgeschichte*, vols. viii. xi. xiv., and
+my Boston address mentioned above. Compare also Fitting, *Ergebn. d.
+Physiol.* vols. iv. and v.
+
+[56] The so-called “inner secretion” in physiology proper would offer a
+certain analogy to the facts assumed by such an hypothesis. Compare the
+excellent summary given by E. Starling at the seventy-eighth meeting of
+the German “Naturforscherversammlung,” Stuttgart, 1906.
+
+But I see quite well that such a theory is very little satisfactory;
+for what has to be done in restitution in each case is not a simple
+homogeneous act, for which one special material might account, but is
+a very complicated work in itself. It was the defect of the theory of
+“organ-forming substances” as advocated by Sachs, that it overlooked
+this point.
+
+So all we know about the proper stimuli of restitutions is far from
+resting on any valid grounds at all; let us not forget that we are
+here on the uncertain ground of what may be called the newest and
+most up-to-date branch of the physiology of form. No doubt, there
+will be something discovered some day, and the idea of the “whole” in
+organisation will probably play some part in it. But in what manner that
+will happen we are quite unable to predict.
+
+This is the first time that, hypothetically at least, the idea of the
+whole has entered into our discussion. The same idea may be said to
+have entered it already in a more implicit form in the statement of the
+threefold harmony in ontogeny.
+
+Let us now see whether we can find the same problem of the “whole”
+elsewhere, and perhaps in more explicit and less hypothetical form.
+Let us see whether our analytical theory of development is in fact as
+complete as it seemed to be, whether there are no gaps left in it which
+will have to be filled up.
+
+
+3. THE PROBLEM OF MORPHOGENETIC LOCALISATION
+
+α. THE THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM
+
+FIRST PROOF OF THE AUTONOMY OF LIFE
+
+We have come to the central point of the first part of these lectures;
+we shall try in this chapter to decide a question which is to give life
+its place in Nature, and biology its place in the system of sciences.
+One of the foundation stones is to be laid upon which our future
+philosophy of the organism will rest.
+
+
+*The General Problem*
+
+Our analytical theory of morphogenesis has been founded upon three
+elementary concepts: the prospective potency, the means, and the
+formative stimulus. Its principal object has been to show that all
+morphogenesis may be resolved into the three phenomena expressed by
+those concepts; in other terms, that morphogenesis may be proved to
+consist simply and solely of what is expressed by them. Have we indeed
+succeeded in attaining this object? Has nothing been left out? Is it
+really possible to explain every morphogenetic event, at least in the
+most general way, by the aid of the terms potency, means, and stimulus?
+
+All of these questions are apt to lead us to further considerations.
+Perhaps these considerations will give us a very clear and simple result
+by convincing us that it is indeed possible to analyse morphogenesis in
+our schematic way.
+
+But if the answer were a negative one? What would that suggest?
+
+The full analysis of morphogenesis into a series of single formative
+occurrences, brought about by the use of given means and on the basis of
+given potencies, might assure us, perhaps, that, though not yet, still
+at some future time, a further sort of analysis will be possible: the
+analysis into the elemental facts studied by the sciences of inorganic
+nature. The organism might prove to be a machine, not only in its
+functions but also in its very origin.
+
+But what are we to say if even the preliminary analysis, which possibly
+might lead to such an ultimate result, fails?
+
+Let us then set to work. Let us try to consider most carefully the topic
+in which our concept of the formative cause or stimulus may be said
+to be centred, the *localisation* of all morphogenetic effects. Is it
+always possible in fact to account for the typical localisation of every
+morphogenetic effect by the discovery of a single specific formative
+stimulus? You will answer me, that such an analysis certainly is not
+possible at present. But I ask you again, are there any criteria that it
+is possible, at least in principle; or are there any criteria which will
+render such an aim of science impossible for all future time?
+
+
+*The Morphogenetic “System”*
+
+We know from our experimental work that many, if not all, of the
+elementary organs in ontogeny show one and the same prospective
+potency distributed equally over their elements. If we now borrow a
+very convenient term from mechanics, and call any part of the organism
+which is considered as a unit from any morphogenetic point of view, a
+morphogenetic “*system*,” we may sum up what we have learnt by saying
+that both the blastoderm of the echinoderms, at least around its
+polar axis, and also the germ-layers of these animals, are “systems”
+possessing an equal potentiality in all of their elements, or, in short,
+that they are *equipotential systems*.
+
+But such a term would not altogether indicate the real character of
+these systems.
+
+Later on we shall analyse more carefully than before the distribution
+of potencies which are the foundation both of regeneration proper and
+of adventitious growth, and then we shall see that, in higher plants
+for instance, there is a certain “system” which may be called the
+organ proper of restitutions, and which also in each of its elements
+possesses the same restoring potency; I refer to the well-known cambium.
+This cambium, therefore, also deserves the name of an “equipotential
+system.” But we know already that its potencies are of the complex
+type, that they consist in the faculty of producing the *whole*, of
+such a complicated organisation as a branch or a root, that the term
+“equipotential system” is here only to signify that such a complicated
+unit may arise out of each of the cells of the cambium.
+
+The potencies we have been studying in the blastula or gastrula of
+echinoderms are not of the complex type: our systems are equipotential
+to the extent that each of their elements may play every *single* part
+in the totality of what will occur in the whole system; it is to
+this *single* part that the term “function of the position” relates.
+We therefore might call our systems equipotential systems with single
+potencies; or, more shortly, singular-equipotential systems.
+
+But even this terminology would fail to touch precisely the very
+centre of facts: it is not only the simplicity or singularity of
+their potencies which characterises the rôle of our systems in
+morphogenesis,[57] but far more important with respect to the production
+of form are two other leading results of the experimental researches.
+The proper act to be performed by every element in each actual case is
+in fact a single one, but the potency of any element as such consists
+in the possibility of many, nay of indefinitely many, single acts:
+that then might justify us in speaking of our systems as “indefinite
+equipotential,” were it not that another reason makes another title seem
+still more preferable. There are indeed indefinite singular potencies at
+work in all of our systems during ontogeny: but the sum of what happens
+to arise in every case out of the sum of the single acts performed by
+all of the single equipotential cells is not merely a sum but a unit;
+that is to say, there exists a sort of harmony in every case among the
+*real products* of our systems. The term *harmonious-equipotential
+system* therefore seems to be the right one to denote them.
+
+[57] The name of singular-equipotential systems might also be applied
+to elementary organs, the single potencies of which are awaked to
+organogenesis by specific formative stimuli from without; but that is
+not the case in the systems studied in this chapter.
+
+We now shall try first to analyse to its very extremes the meaning of
+the statement that a morphogenetic system is harmonious-equipotential.
+
+
+*The “Harmonious-Equipotential System”*
+
+We have an ectoderm of the gastrula of a starfish here before us; we
+know that we may cut off any part of it in any direction, and that
+nevertheless the differentiation of the ectoderm may go on perfectly
+well and result in a typical little embryo, which is only smaller in
+its size than it would normally be. It is by studying the formation of
+the highly complicated ciliary band, that these phenomena can be most
+clearly understood.
+
+Now let us imagine our ectoderm to be a cylinder instead of being
+approximately a sphere, and let us imagine the surface of this cylinder
+unrolled. It will give us a plane of two definite dimensions, *a* and
+*b*. And now we have all the means necessary for the analytical study of
+the differentiation of an harmonious-equipotential system.
+
+Our plane of the dimensions *a* and *b* is the basis of the normal,
+undisturbed development; taking the sides of the plane as fixed
+localities for orientation, we can say that the actual fate, the
+“prospective value” of every element of the plane stands in a fixed and
+definite correlation to the length of two lines, drawn at right angles
+to the bordering lines of the plane; or, to speak analytically, there
+is a definite actual fate corresponding to each possible value of *x*
+and of *y*. Now, we have been able to state by our experimental work,
+that the prospective value of the elements of our embryonic organ is not
+identical with their “prospective potency,” or their possible fate, this
+potency being very much richer in content than is shown by a single case
+of ontogeny. What will be the analytical expression of such a relation?
+
+Let us put the question in the following way: on what factors does
+the fate of any element of our system depend in all possible cases
+of development obtainable by means of operations? We may express our
+results in the form of an equation:--
+
+    *p.v. (X) = f( ... )*
+
+*i.e.* “the prospective value of the element *X* is a function of
+...”--of what?
+
+We know that we may take off any part of the whole, as to quantity, and
+that a proportionate embryo will result, unless the part removed is of
+a very large size. This means that the prospective value of any element
+certainly depends on, certainly is a function of, the *absolute size*
+of the actually existing part of our system in the particular case. Let
+*s* be the absolute size of the system in any actual experimental case
+of morphogenesis: then we may write *p.v. (X) = f(s ... )*. But we
+shall have to add still some other letter to this *s*.
+
+The operation of section was without restriction either as to the
+amount of the material removed from the germ, or as to the direction of
+the cut. Of course, in almost every actual case there will be both a
+definite size of the actual system and a definite direction of the cut
+going hand-in-hand. But in order to study independently the importance
+of the variable direction alone, let us imagine that we have isolated
+at one time that part of our system which is bounded by the lines *a_1
+b_1*, and at another time an equal amount of it which has the lines
+*a_2 b_2* as its boundaries. Now since in both cases a typical small
+organism may result on development, we see that, in spite of their equal
+size the prospective value of every element of the two pieces cut
+out of the germ may vary even in relation to the direction of the cut
+itself. Our element, *X*, may belong to both of these pieces of the same
+size: its actual fate nevertheless will be different. Analytically, it
+may be said to change in correspondence to the actual position of the
+actual boundary lines of the piece itself with regard to the fundamental
+lines of orientation, *a* and *b*; let this actual position be expressed
+by the letter *l*, *l* marking the distance of one[58] of the actual
+boundary lines of our piece from *a* or *b*: then we are entitled to
+improve our formula by writing *p.v. (X) = f(s, l ... )* (Fig.
+11).
+
+[58] The distance of the other boundary line from *a* or *b* would be
+given by the value of *s*.
+
+[Illustration: Fig. 11.--Diagram to show the Characteristics of an
+“Harmonious-equipotential System.”
+
+The element *X* forms part of the systems *a b* or *a_1 b_1* or
+*a_2 b_2*; its prospective value is different in each case.]
+
+But the formula is not yet complete: *s* and *l* are what the
+mathematicians call variables: they may have any actual value and there
+will always be a definite value of *p.v.*, *i.e.* of the actual fate
+which is being considered; to every value of *s* and *l*, which as
+we know are independent of each other, there corresponds a definite
+value of the actual prospectivity. Now, of course, there is also a
+certain factor at work in every actual case of experimental or normal
+development, which is *not* a variable, but which is the same in all
+cases. This factor is a something embraced in the prospective potency
+of our system, though not properly identical with it.
+
+The prospective potency of our system, that is to say of each of its
+elements, is the sum total of what can be done by all; but the fact
+that a typically proportionate development occurs in every possible
+case, proves that this sum comes into account, not merely as a sum,
+but as a sort of order: we may call this order the “relation of
+localities in the absolutely normal case.” If we keep in mind that the
+term “prospective potency” is always to contain this order, or, as we
+may also call it, this “relative proportionality,” which, indeed, was
+the reason for calling our systems “harmonious,” then we may apply it
+without further explanation in order to signify the *non-variable*
+factor on which the prospective value of any element of our systems
+depends, and, if we denote the prospective potency, embracing order,
+by the letter *E*, we are now able to complete our formula by saying
+*p.v. (X) = f(s, l, E)*. So far the merely analytical study of the
+differentiation of harmonious-equipotential systems.[59]
+
+[59] A far more thorough analysis of this differentiation has been
+attempted in my paper, “Die Localisation morphogenetischer Vorgänge. Ein
+Beweis vitalistischen Geschehens,” Leipzig, 1899.
+
+
+*Instances of “Harmonious-Equipotential Systems”*
+
+We must try at first to learn a few more positive facts about our
+systems, in order that we may know how important is the part which they
+play in the whole animal kingdom, and in order that our rather abstract
+analysis may become a little more familiar to us. We know already that
+many of the elementary morphogenetic organs have been really proved to
+be harmonious-equipotential systems, and that the same probably is true
+of many others; we also know that the immature egg of almost all animals
+belongs to this type, even if a fixed determination of its parts may
+be established just after maturation. Moreover, we said, when speaking
+about some new discoveries on form-restitution, that there are many
+cases in which the processes of restitution do not proceed from single
+localities, the seat of complex potencies in the organism, but in which
+each *single* part of the truncated organism left by the operation has
+to perform one *single* act of restoration, the full restitution being
+the result of the totality of all. These cases must now be submitted to
+a full analysis.
+
+All of you have seen common sea-anemones or sea-roses, and many of you
+will also be familiar with the so-called hydroid polyps. *Tubularia*
+is one genus of them: it looks like a sea-anemone in miniature placed
+on the top of a stem like a flower. It was known already to Allman
+that *Tubularia* is able to restore its flower-like head when that
+is lost, but this process was taken to be an ordinary regeneration,
+until an American zoologist, Miss Bickford, succeeded in showing that
+there was no regeneration process at all, in the proper sense of the
+word, no budding of the missing part from the wound, but that the new
+tubularian head was restored by the combined work of many parts of the
+stem. Further analysis then taught us that *Tubularia* indeed is to be
+regarded as the perfect type of an harmonious-equipotential system: you
+may cut the stem at whatever level you like: a certain length of the
+stem will always restore the new head by the co-operation of its parts.
+As the point of section is of course absolutely at our choice, it is
+clear, without any further discussion, that the prospective value of
+each part of the restoring stem is a “function of its position,” that
+it varies with its distance from the end of the stem; and so at once
+we discover one of the chief characteristics of our systems. But also
+the second point which enters into our formula can be demonstrated in
+*Tubularia*: the dependence of the fate of every element on the actual
+size of the system. You would not be able to demonstrate this on very
+long stems, but if you cut out of a *Tubularia* stem pieces which are
+less than ten millimetres in length, you will find the absolute size
+of the head restored to be in close relation to the length of the stem
+piece, and this dependence, of course, includes the second sort of
+dependence expressed in our formula.
+
+The figures will serve to show you a little more concretely what has
+been described. The head of *Tubularia* consists of a sort of broad base
+with a thin proboscis upon it, both bearing a large number of tentacles;
+these tentacles are the first things to be seen as primordia (“Anlagen”)
+in the process of restitution. You notice two rings of longitudinal
+lines inside the stem; the lines will become walls and then will
+separate from the stem until they are only connected with it at their
+basal ends; the new tentacles are ready as soon as that has happened,
+and a process of growth at the end will serve to drive the new head out
+of the so-called perisarc or horny skeleton, which surrounds the stem.
+By comparing the two figures, 12 *e*, and *g*, you easily find out that
+the absolute lengths of the two tentacle rings are very different, and
+that both are in proportion[60] to the actual size of the stem (Fig. 12).
+
+[60] This statement is *not strictly* correct for *Tubularia*. I found
+(*Archiv f. Entwickelungsmechanik*, ix. 1899), that a reduction of the
+length of the stem is always followed by a reduction of the size of the
+hydranth-primordium, but there is no real proportionality between them.
+It is only for theoretical simplification that a strict proportionality
+is assumed here, both in the text and the diagram. But there is an
+almost strict proportionality in all cases of “closed forms.”
+
+[Illustration: Fig. 12.--Tubularia.
+
+*a.* Diagram of the “Hydranth,” with its short and long tentacles.
+
+*b.* Restitution of a new hydranth inside the perisarc (*p*).
+
+*c.* The same--later stage; the tentacles are complete; the whole
+hydranth will be driven out of the perisarc by a process of growth that
+occurs at the locality marked ⬆.
+
+*d.* A stem of *Tubularia* cut either at *a_1 b_1* or at *a_2 b_2*,
+or at *a_1 c*.
+
+*e.* Position of tentacles in the piece cut at *a_1 b_1*.
+
+*f.* Position of tentacles in the piece cut at *a_2 b_2*,
+which is equal in length to *a_1 b_1*.
+
+*g.* Position of tentacles in the piece cut at *a_1 c*,
+which is half as long as *a_1 b_1*.]
+
+So we find our formula *p.v. (X) = f(s, l, E)* very well
+illustrated in *Tubularia*. The formula indeed may help us to predict,
+in any case, where a certain part of the polyp’s organisation is
+to originate, at least if we know all that is included under our
+letter *E*, *i.e.* the normal proportion of our form. Of course such
+prediction would not have much practical importance in all our cases of
+morphogenesis, but nevertheless I should like to state here that it is
+possible; for many scientific authors of recent times have urged the
+opinion that prediction of, and domination over, what will happen, can
+be the only true aims of sciences at all. I myself judge these aims to
+be of second or third-rate importance only, but, if they may be reached
+by what our purely theoretical study teaches, so much the better.
+
+Another very typical case of a morphogenetic system of the harmonious
+type is supplied by the phenomena of restoration in the ascidian
+*Clavellina*. I cannot fully describe the organisation of this form
+(Fig. 13a), and it must suffice to say that it is very complicated,
+consisting of two very different chief parts, the branchial apparatus
+and the so-called intestinal sac; if these two parts of the body of
+*Clavellina* are separated one from the other, each may regenerate the
+other in the typical way, by budding processes from the wound. But, as
+to the branchial apparatus, there may happen something very different:
+it may lose almost all of its organisation and become a small white
+sphere, consisting only of epithelia corresponding to the germ-layers,
+and of mesenchyme between them, and then, after a certain period of
+rest, a new organisation will appear. Now this new organisation is
+not that of a branchial apparatus but represents a very small but
+complete ascidian (Fig. 13). Such a fact certainly seems to be very
+important, not to say very surprising; but still another phenomena may
+be demonstrated on the animal which seems to be even more important. You
+first isolate the branchial apparatus from the other part of the body,
+and then you cut it in two, in whatever direction you please. Provided
+they survive and do not die, as indeed many of them do, the pieces
+obtained by this operation will each lose their organisation, as did the
+whole branchial apparatus, and then will each acquire another one, and
+this new organisation is also that of a *complete* little *Clavellina*.
+So we see that not only is the branchial apparatus of our animal capable
+of being transformed into a whole animal by the co-operative work of
+all its parts, but even each part of it may be transformed into a small
+*whole*, and it is quite at our disposal how large this part shall be,
+and what sort of a fragment of the original branchial apparatus it shall
+represent.
+
+[Illustration: Fig. 13.--Clavellina.
+
+*a.* Diagram of the normal animal: *E* and *J* = openings; *K* =
+branchial apparatus; *D* = intestine; *M* = stomach; *H* = heart.
+
+*b.* The isolated branchial apparatus.
+
+*c-e.* Different stages of reduction of the branchial apparatus.
+
+*f.* The new *whole* little ascidian.]
+
+We could hardly imagine a better instance of an harmonious-equipotential
+system.
+
+I cannot give you a description of all the other types of our systems
+subservient to restitution, and I can only mention here that the common
+hydra and the flatworm *Planaria* are very fine examples of them. But
+to one special case of harmonious equipotentiality you must allow me to
+direct your further attention.
+
+It has been known for many years that the Protozoa are also capable of
+a restoration of their form and organisation after disturbances, if at
+least they contain a certain amount of their nuclear substance. This
+process of restoration used to be regarded as belonging to the common
+type of regeneration proper, until T. H. Morgan succeeded in showing
+that in the genus *Stentor* it follows just the very lines which we know
+already from our study of embryonic organs or from *Tubularia*; that
+an harmonious-equipotential system is at the basis of what goes on.
+Now, you know that all Protozoa are but one highly organised cell: we
+have therefore here an instance where the so-called “elements” of our
+harmonious-morphogenetic system are not cells, but something inside of
+cells; and this feature must appear to be of very great moment, for it
+first shows, as we have already pointed out on another occasion, that
+morphogenesis is not dependent on cell-division, and it states at the
+same time that our concept of the harmonious-equipotential system may
+cover a very great area--that, in fact, it is a scheme of a very wide
+extent.
+
+
+*The Problem of the Factor* E
+
+We turn back again to considerations of a more abstract form. We left
+our analysis of the differentiation of the harmonious-equipotential
+systems, and particularly of the phenomena of localisation during this
+differentiation, at the point where we had succeeded in obtaining an
+equation as the expression of all those factors on which the prospective
+value, the actual fate, of any element of our systems depends, *p.v. (X)
+= f(s, l, E)* was the short expression of all the relations involved;
+*s* and *l*, the absolute size of the system and the relative position
+of the element with respect to some fixed points, were independent
+variables; *E* was a constant, namely, the prospective potency, with
+special regard to the proportions embraced by it.
+
+We shall now study the significance of the factor *E*.
+
+What does this *E* mean? Is it a short expression merely for an actual
+sum of elemental agents having a common resultant? And, if so, of what
+kind are these agents? Or what may *E* mean, if it can be shown *not* to
+be a short sign for a mere sum?
+
+
+*No Explanation Offered by “Means” or “Formative Stimuli”*
+
+For practical purposes it seems better if we modify the statement of our
+question. Let us put it thus: *E* is one of the factors responsible,
+among variables, for the localisation of organic differentiation;
+what then do we actually know about the causal factors which play a
+localising part in organogenesis? We, of course, have to look back to
+our well-studied “formative stimuli.” These stimuli, be they “external”
+or “internal,” come from without with respect to the elementary organ
+in which any sort of differentiation, and therefore of localisation,
+occurs: but in our harmonious systems no localising stimulus comes from
+without, as was the case, for instance, in the formation of the lens of
+the eye in response to the optical vesicle touching the skin. We know
+absolutely that it is so, not to speak of the self-evident fact that the
+general “means” of organogenesis have no localising value at all.[61]
+
+[61] One might object here that in a piece of a *Tubularia* stem, for
+instance, the tissues are in direct contact with the sea-water at
+the two points of the wounds only, and that at these very points a
+stimulus might be set up--say by a process of diffusion--which gradually
+decreases in intensity on its way inward. And a similar argument might
+apply to the small but whole blastula of Echinus, and to all other
+cases. But, in the first place, stimuli which only differ in intensity
+could hardly call forth the typical and typically localised single
+features realised in differentiation. On the other hand--and this will
+overthrow such an hypothesis completely--the dependence of the single
+localised effects in every case on the *absolute size* of the fragment
+or piece chosen for restoration renders quite impossible the assumption
+that all the singularities in the differentiation of the harmonious
+systems might be called forth by single stimuli originating in two
+fixed places in an *independent* way. These would never result in any
+“harmonious,” any proportionate structure, but a structure of the
+“normal” proportionality *and size* at its two ends and non-existent in
+the middle!
+
+So we see there is nothing to be done, either with the means or with the
+formative stimuli; both are entirely unable to account for those kinds
+of localisation during differentiation which appear in our harmonious
+systems.
+
+But is there no possibility of explaining the phenomena of organogenetic
+localisation by any other sort of interaction of parts? Two such
+possibilities may at the first glance seem to exist.
+
+
+*No Explanation Offered by a Chemical Theory of Morphogenesis*
+
+Though never set forth, in the form of a properly worked-out theory,
+the view has sometimes been advocated by biologists, that a chemical
+compound of a very high degree of complication might be the very basis
+of both development and inheritance, and that such a chemical compound
+by its disintegration might direct morphogenesis.
+
+Let us first examine if such a view may hold for the most general
+features of organic morphogenesis. It seems to me that from the very
+beginning there exists one very serious objection to every chemical
+theory of form-building, in the mere fact of the possibility of the
+restoration of form starting from atypical localities. The mere fact,
+indeed, that there is such a thing as the regeneration of a leg of a
+newt--to say nothing about restitution of the harmonious type--simply
+contradicts,[62] it seems to me, the hypothesis, that chemical
+disintegration of one compound may govern the course of morphogenetic
+events: for whence comes the re-existence of the hypothetical compound,
+newly to be disintegrated, after disintegration *has* been completed
+once already? And we even know that regeneration may go on several times
+running from the same locality!
+
+[62] See my article in *Biolog. Centralblatt*, 27, 1907, p. 69. The
+question is rendered still more complicated by the fact that in the case
+of the regeneration, say, of a leg it is not the original “morphogenetic
+compound” which is again required for disintegration, after it has
+become disintegrated once already, but only a specific part of it: just
+that part of it which is necessary for producing the leg! On the other
+hand, it would be impossible to understand, on the basis of physical
+chemistry, how the isolated branchial apparatus of *Clavellina* could
+be transformed, by chemical processes exclusively, into a system of
+which only a certain *part* consists of that substance of which the
+starting-point had been composed in its *completeness*.
+
+But, if we intentionally disregard this difficulty, in spite of
+its fundamental character, how could the hypothesis of chemical
+disintegration give the reason for the differentiation of our
+harmonious-equipotential systems, with special regard to the
+localisation of it; how could it account, in other words, for the
+appearance of typically localised specifications in an organ for which
+no external localising causes can be predicated?
+
+Let us remember that a few original intimate differences exist in our
+harmonious systems: the main directions of the intimate protoplasmic
+structure including polarity and bilaterality. There are therefore
+three times two specified poles in each of these systems, at least in
+bilateral organisms, but no other differences are present in them.
+A few very simple cases of harmonious differentiation might indeed
+be understood on the theory of a disintegrating chemical compound
+in connection with these few differences. Imagine that the original
+compound, of the quantity *a*, is disintegrated to the amount of
+*a*_1; from *a*_1 are formed the two more simple compounds, *b*
+and *c*, both of them in definite quantities; then we have the three
+chemical individuals, *a-a*_1, *b* and *c*, as the constituents of
+our harmonious system; and it now might be assumed, without any serious
+difficulty, though with the introduction of some new hypotheses, that
+the two poles of one of the fundamental axes of symmetry attract *b* and
+*c* respectively, *a-a*_1 remaining unattracted between them. We thus
+should have the three elementary constituents of the system separated
+into three parts, and as they all three are of a definite quantity,
+their separation would mean that the system had been divided into three
+parts, *a-a*_1, *b* and *c*, also with regard to its proper form.
+It is clear, that by taking away any part of the original system, by
+means of operations, there would be taken away a certain amount of the
+original compound; say that *a/n* is left; then, of course, the three
+constituents after the partial disintegration would be *a-a_1/n*,
+*b/n* and *c/n*, and so it follows that the proportionality of
+localisation would really be preserved in any case.
+
+But these considerations, evident as they seem to be in the most
+simple case, fail to satisfy in a really general sense: for two
+different reasons. First, they could never account for the fact that
+the differentiated organism by no means consists of so many different
+compounds as it shows single parts of its differentiation, but that,
+on the contrary, it only consists, as we know, of a certain rather
+limited number of true different morphogenetic elements, these
+elements occurring again and again--as for instance, nervous or
+muscular elements--but typical each time in locality, quantity, and
+form. And in the second place, the very *form* of elementary organs,
+their form as such, does not at all go hand-in-hand with chemical
+differences; this feature alone would absolutely overthrow any sort
+of a chemical morphogenetic theory to account for the problem of
+localisation. Take the typically arranged ring of the mesenchyme
+cells in our Echinus-gastrula, with its two spherical triangles, so
+typically localised; look at any sort of skeleton, in Radiolaria, or in
+starfishes, or in vertebrates: here you have form, real form, but form
+consisting of only one material. Not only is the arrangement of the
+elements of form typical here, *e.g.* the arrangement of the single
+parts of the skeleton of the hand or foot, but also the special form
+of each element is typical, *e.g.* the form of each single bone of the
+foot; and, on a purely chemical theory of morphogenesis the sufficient
+reason for the production of typical form in such a sense would be
+wanting. For atoms or molecules by themselves can only account for form
+which is arranged, so to speak, according to spatial geometry--as in
+fact they do in crystallography; but they can never account for form
+such as the skeleton of the nose, or hand, or foot. You will answer
+me perhaps, that there may be non-chemical agents in the germ,[63]
+responsible for typical form-localisation, but by such reasoning you
+would be departing from a purely chemical theory. Our next paragraph
+will be devoted to this side of the question.
+
+[63] Besides the specified poles determined by the polar-bilateral
+structure of the protoplasm.
+
+That is the principal reason for rejecting all sorts of chemical
+morphogenetic theories put forward to explain the problem of
+localisation; it is more explicit, and therefore, I suppose, still
+more convincing than the more general consideration that the very
+fact of restitutions in itself must contradict the hypothesis that
+a disintegration of compounds might be the directive agency in
+morphogenesis. To sum up: Specificity of organic form does not go
+hand-in-hand with specificity of chemical composition, and therefore
+cannot depend on it; and besides that, specific organic form is such
+that it can never be explained by atomic or molecular arrangement in
+the chemical sense; for, to state it in a short but expressive manner,
+the “form” of an atom or molecule can never be that of a lion or a
+monkey. To assume that would be to go beyond the limits of chemistry in
+chemistry itself.
+
+
+*No Machine Possible Inside the Harmonious Systems*
+
+And now we turn to the last possibility which is left to us in our
+endeavour to “understand” the localisation of the differentiation in our
+harmonious-equipotential systems by the means of physics and chemistry.
+Outside causes have failed to account for it, chemical disintegration
+of a compound has failed too. But could there not exist some sort of
+complicated interactions amongst the parts of the harmonious system
+themselves? Could there not exist some kind of a real machine in the
+system, which, if once set going, would result in the differentiations
+that are to take place? Then we might say that the “prospective
+potency” of the system is in fact that machine; we should know what the
+letter *E* of our equation stood for: viz., a resultant action of many
+complicated elemental interactions, and nothing more.
+
+Weismann, we know already, had assumed that a sort of machine was the
+prime mover of morphogenesis. We have seen that his theory cannot be
+true; the results of experiments most strongly contradict it. But, of
+course, the experiments only showed us that *such* a machine as *he*
+had imagined to exist could not be there, that development could not be
+governed by the disintegration of a given complicated structure into its
+simplest parts. But might not some other machine be imaginable?
+
+We shall understand the word “machine” in a most general sense. A
+machine is a typical configuration of physical and of chemical
+constituents, by the acting of which a typical effect is attained.
+We, in fact, lay much stress upon embracing in our definition of a
+machine the existence of chemical constituents also; we therefore
+understand by the word “machine” a configuration of a much higher
+degree of complication than for instance a steam-engine is. Of course
+a machine, whose acting is to be typical with regard to the three
+dimensions in space, has to be typically constructed with regard to
+these three dimensions itself; a machine that was an arrangement of
+elements in a strict plane could never have typical effects at right
+angles to that plane. This is a point which must well be kept in mind
+in all hypothetical considerations about machines that claim to explain
+morphogenesis.
+
+It must be granted that a machine, as we understand the word, might very
+well be the motive force of organogenesis in general, if only normal,
+that is to say, if only undisturbed development existed, and if a taking
+away of parts of our systems led to fragmental development.
+
+But we know that, at least in our harmonious-equipotential systems,
+quite another process occurs after parts have been taken away: the
+development that occurs is not fragmental but whole, only on a smaller
+scale.
+
+And we know, further, that this truly whole development sets in
+irrespective of the amount and direction of the separation. Let us first
+consider the second of these points. There may be a whole development
+out of each portion of the system--above certain limits--which is, say,
+of the volume *V*. Good! Then there ought to exist a machine, like
+that which exists in the whole undisturbed system, in this portion *V*
+also, only of smaller dimensions; but it also ought to exist in the
+portion *V*_1 which is equal to *V* in amount, and also in *V*_2, in
+*V*_3, *V*_4 and so on. Indeed, there do exist almost indefinitely
+many *V*_n all of which can perform the whole morphogenesis, and all
+of which therefore ought to possess the machine. But these different
+portions *V*_n are only partly different from each other in spatial
+relation. Many parts of *V*_2 are also parts of *V*_1 and of *V*_3
+and of *V*_4 and so on; that is to say, the different volumes *V*_n
+overlap each other successively and in such a manner that each following
+one exceeds the preceding one in the line by a very small amount only.
+But what then about our machines? Every volume which may perform
+morphogenesis completely must possess the machine in its totality. As
+now every element of one volume may play any possible elemental rôle in
+every other, it follows that each part of the whole harmonious system
+possesses any possible elemental part of the machine equally well, all
+parts of the system at the same time being constituents of different
+machines.
+
+A very strange sort of machine indeed, which is the same in all its
+parts (Fig. 14)!
+
+[Illustration: Fig. 14.--An “Harmonious-equipotential System” of
+whatever kind.
+
+According to the “machine-theory” of life this system ought to possess
+a certain unknown very complicated machine *in its completeness*:
+
+      (*a*) in its total length,
+  and (*b*) in each of the equal volumes *v*, *v*_1, *v*_2, *v*_3 and
+    so on,
+  and (*c*) in each of the unequal volumes *w*, *x*, *y*, and so on,
+  and (*d*) in every imaginable volume, no matter of what size.
+
+Therefore the “machine-theory” of life is absurd.]
+
+But we have forgotten, I see, that in our operation the absolute amount
+of substance taken away from the system was also left to our choice.
+From this feature it follows that not only all the different *V*_n,
+all of the same size, must possess the hypothetic machine in its
+completeness, but that all amounts of the values *V*_n-*n*, *n* being
+variable, must possess the totality of the machine also: and all values
+*V*_n-*n*, with their variable *n*, may again overlap each other.
+
+Here we are led to real absurdities!
+
+But what is the conclusion of our rather wild considerations?
+
+It seems to me that there is only one conclusion possible. If we
+are going to explain what happens in our harmonious-equipotential
+systems by the aid of causality based upon the constellation of single
+physical or chemical factors and events, there *must* be some such
+thing as a machine. Now the assumption of the existence of a machine
+proves to be absolutely absurd in the light of the experimental facts.
+*Therefore there can be neither any sort of a machine nor any sort of
+causality based upon constellation underlying the differentiation of
+harmonious-equipotential systems.*
+
+For a machine, typical with regard to the three chief dimensions
+of space, cannot remain itself if you remove parts of it or if you
+rearrange[64] its parts at will.
+
+[64] The pressure experiments and the dislocation experiments come into
+account here; for the sake of simplicity they have not been alluded to
+in the main line of our argument.
+
+Here we see that our long and careful study of morphogenesis has been
+worth while: it has afforded us a result of the very first importance.
+
+
+*The Autonomy of Morphogenesis Proved*
+
+No kind of causality based upon the constellations of single physical
+and chemical acts can account for organic individual development; this
+development is not to be explained by any hypothesis about configuration
+of physical and chemical agents. Therefore there must be something
+else which is to be regarded as the sufficient reason of individual
+form-production. We now have got the answer to our question, what
+our constant *E* consists in. It is not the resulting action of a
+constellation. It is not only a short expression for a more complicated
+state of affairs, it expresses *a true element of nature*. Life, at
+least morphogenesis, is not a specialised arrangement of inorganic
+events; biology, therefore, is not applied physics and chemistry: life
+is something apart, and biology is an independent science.
+
+All our results at present, indeed, are negative in their form; our
+evidence was throughout what is called *per exclusionem*, or indirect
+or apagogic. There were excluded from a certain number of possibilities
+all except one; a disjunctive proposition was stated in the form: *E*
+is either this, or that, or the other, and it was shown that it could
+not be any of all these except one, therefore it was proved to be that
+one. Indeed, I do not see how natural science could argue otherwise;
+no science dealing with inorganic phenomena does; something new and
+elemental must always be introduced whenever what is known of other
+elemental facts is proved to be unable to explain the facts in a new
+field of investigation.
+
+We shall not hesitate to call by its proper name what we believe we have
+proved about morphogenetic phenomena. What we have proved to be true
+has always been called *vitalism*, and so it may be called in our days
+again. But if you think a new and less ambitious term to be better for
+it, let us style it the doctrine of the *autonomy of life*, as proved
+at least in the field of morphogenesis. I know very well that the word
+“autonomy” usually means the faculty of *giving* laws to oneself, and
+that in this sense it is applied with regard to a community of men;
+but in our phrase autonomy is to signify the *being subjected* to laws
+peculiar to the phenomena in question. This meaning is etymologically
+defensible, and besides that I perhaps may remind you of a certain
+chapter of Professor Ward’s Gifford Lectures, in which he holds the view
+that, psychologically and epistemologically, there is more than a mere
+verbal relation between the civil and the natural “law.”
+
+Vitalism then, or the autonomy of life, has been proved by us
+indirectly, and cannot be proved otherwise so long as we follow the
+lines of ordinary scientific reasoning. There can indeed be a sort of
+direct proof of vitalism, but now is not the time to develop this proof,
+for it is not of the purely scientific character, not so naïve as our
+present arguments are, if you choose to say so. An important part of our
+lectures next summer will be devoted to this direct proof.
+
+
+“*Entelechy*”
+
+But shall we not give a name to our vitalistic or autonomous factor
+*E*, concerned in morphogenesis? Indeed we will, and it was not without
+design that we chose the letter *E* to represent it provisionally. The
+great father of systematic philosophy, Aristotle, as many of you will
+know, is also to be regarded as the founder of theoretical biology.
+Moreover, he is the first vitalist in history, for his theoretical
+biology is throughout vitalism; and a very conscious vitalism indeed,
+for it grew up in permanent opposition to the dogmatic mechanism
+maintained by the school of Democritus.
+
+Let us then borrow our terminology from Aristotle, and let that factor
+in life phenomena which we have shown to be a factor of true autonomy be
+called *Entelechy*, though without identifying our doctrine with what
+Aristotle meant by the word έντελέχεια. We shall use this word only as a
+sign of our admiration for his great genius; his word is to be a mould
+which we have filled and shall fill with new contents. The etymology of
+the word ἐντελέχεια allows us such liberties, for indeed we have shown
+that there is at work a something in life phenomena “which bears the end
+in itself,” ὃ ἔχει ἐν ἑαυτᾣ τὸ τέλος.
+
+Our concept of entelechy marks the end of our analysis of individual
+morphogenesis. Morphogenesis, we have learned, is “epigenesis” not only
+in the descriptive but also in the theoretical sense: manifoldness
+in space is produced where no manifoldness was, real “evolutio” is
+limited to rather insignificant topics. But was there nothing “manifold”
+previous to morphogenesis? Nothing certainly of an *extensive*
+character, but there was something else: there was entelechy, and thus
+we may provisionally call entelechy an “*intensive manifoldness*.”
+That then is our result: not evolutio, but epigenesis--“epigenesis
+vitalistica.”
+
+
+*Some General Remarks on Vitalism*
+
+We now shall leave entelechy where it stands: next summer we shall turn
+back to it and shall make its full logical and ontological analysis
+our chief study. At present we are satisfied with having proved its
+existence in nature, with having laid some of the foundations of a
+doctrine to be based upon it. I hope that these foundations will evince
+themselves strong: that is all-important.[65] It indeed has been the
+fault of all vitalism in the past that it rested on weak foundations.
+Therefore the discussion of the basis underlying our doctrine of the
+autonomy of life is to occupy us still a considerable time. We shall
+devote to it two more of this year’s lectures and three of the next; we
+shall examine all sorts of phenomena of life in order to find out if
+there are any further proofs of vitalism, independent perhaps, of what
+we way call our *first proof*, which is based upon the analysis of the
+*differentiation of harmonious-equipotential systems*. We shall find
+some more independent proofs; and besides that we shall find many kinds
+of phenomena upon which future times perhaps may erect more of such
+independent proofs.
+
+[65] My “first proof of vitalism” was first developed in the paper, “Die
+Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional
+remarks in *Organische Regulationem*, Leipzig, 1901, and in *Archiv
+für Entwickelungsmechanik*, 14, 1902.) I cannot admit that any really
+serious objection has been brought forward against it. (See my articles
+in *Biologisches Centralblatt*, 22, 23, 27, and in *Ergebnisse d. Anat.
+u. Entwickelungsgesch*. 11, 14.) An historical sketch of vitalism will
+be found in my book, *Der Vitalismus als Geschichte und als Lehre*,
+Leipzig, 1905.
+
+For we shall be chary of bestowing the name “proof” except on what is a
+proof indeed, of course according to our critical conviction. Vitalistic
+views in biology have arisen in rather numerous forms during the last
+fifteen years, especially in Germany--though in very strong contrast to
+the so-called official German biology--but I can only admit that one of
+all the arguments of “neo-vitalism” has proved its statements. I refer
+to the theory of “morphaesthesia” as developed by Noll, which we shall
+study briefly in the next lecture. I cannot concede that Reinke or
+Schneider or Pauly have really proved what they believe, and I cannot
+even allow to the most original thinker in this field, Gustav Wolff,
+that he has given a real demonstration of his views. He states that the
+existence of so-called “primary purposefulness,” that is, the existence
+of adaptive processes, which cannot be imagined to have arisen on
+Darwinian principles, is able to prove vitalism; but I say that it only
+proves teleology, which is a broader concept than vitalism.
+
+The possibility of a machine at the root of the phenomena in question
+always has to be excluded in order that vitalism may be proved, and I
+cannot grant that the necessity of such an exclusion has been actually
+shown by any of my fellow-combatants against so-called mechanism, except
+Noll.[66]
+
+[66] We are dealing here with morphogenesis and so-called vegetative
+physiology only; to certain psychologists, who have refuted the theory
+of psycho-physical parallelism, I must grant that they also have proved
+vitalism. (See Volume II.)
+
+
+*The Logic of our First Proof of Vitalism*
+
+Let us devote the end of our present lecture to an account of the
+logical means by which it has been possible to develop what we hope will
+be regarded as a true *proof* of life autonomy.
+
+Firstly, we have looked upon the phenomena of morphogenesis without
+any prepossessions; we may say that we have fully surrendered ourselves
+to them; we have not attacked them with any sort of dogmatism except
+the inherent dogmatism of all reasoning. But this dogmatism, if it may
+be called so, does not postulate that the results of the inorganic
+doctrines must hold for the organic world, but only that both the
+inorganic and the organic must be subject to certain most general
+principles.
+
+By studying life as a given phenomenon, by fully devoting ourselves to
+our problem, we not only have analysed into its last elements what was
+given to us as our subject, but we also, more actively, have created new
+combinations out of those elements: and it was from the discussion of
+these positive constructions that our argument for vitalism was derived.
+
+We have analysed morphogenesis into elementary processes, means,
+potency, formative stimulus, just as the physicist analyses mechanics
+into time, velocity, mass, and force; we have then rearranged
+our elements into “systems”--the equipotential systems, the
+harmonious-equipotential system in particular, just as the physicist
+composes his elements into the concepts of momentum or of kinetic energy
+or of work. And finally, we have discussed our compositions and have
+obtained our result, just as the physicist gets his ultimate results by
+discussing work and kinetic energy and momentum.
+
+Of course the comparison is by no means intended to show that mechanics
+and biology are sciences of the same kind. In my opinion, they are not
+so at all; but nevertheless there do exist similarities of a logical
+kind between them.
+
+And it is not the formal, logical character alone which allows us to
+compare biology with other natural sciences: there is still something
+more, there is one kind of assumption or postulate, or whatever you
+may choose to call it, without which all science whatever would be
+altogether *impossible*. I refer to the concept of *universality*. All
+concepts about nature which are gained by positive construction out of
+elements resulting from analysis, claim to be of *universal validity*;
+without that claim there could indeed be no science.
+
+Of course this is no place for a lecture on methodology, and it
+therefore must suffice to make one remark with special regard to
+our purpose, which we should like to emphasise. Our concept of the
+harmonious-equipotential system--say rather, our concept of the
+prospective potency itself--presumes the understanding that indeed *all*
+blastomeres and *all* stems of *Tubularia*, including those upon which
+we have *not* carried out our experiments, will behave like those we
+have experimented with; and those concepts also presume that a certain
+germ of Echinus, *A*, the blastomeres of which were not separated,
+would have given two whole larvae, if separation had taken place, while
+another germ, *B*, which actually gave us two larvae after separation,
+would only have given one without it. Without this presumption the
+concept of “potency” is meaningless, and, indeed, every assumption of a
+“faculty” or a “possibility” would be meaningless in the whole area of
+science.
+
+But this presumption can never be proved; it can only be postulated. It
+therefore is only with this postulate that our first proof of vitalism
+holds; but this restriction applies to *every* law of nature.
+
+I cannot force you to agree with this postulate: but if you decline
+you are practically saying that there exists a sort of pre-established
+harmony between the scientific object and the scientist, the scientist
+always getting into his hands such objects only as have been
+predestinated from the very beginning to develop two larvae instead of
+one, and so on.
+
+Of course, if that is so, no proof of natural laws is possible at all;
+but nature under such views would seem to be really dæmonic.
+
+And so, I hope, you will grant me the postulate of the universality
+of scientific concepts--the only “hypothesis” which we need for our
+argument.
+
+
+4. ON CERTAIN OTHER FEATURES OF MORPHOGENESIS ADVOCATING ITS AUTONOMY
+
+Our next studies on the physiology of form will be devoted in the first
+place to some additional remarks about our harmonious-equipotential
+systems themselves, and about some other kinds of morphogenetic
+“systems” which show a certain sort of relationship with them. For it is
+of the greatest importance that we should become as familiar as possible
+with all those facts in the physiology of form upon the analysis of
+which are to be based almost all of the future theories that we shall
+have to develop in biology proper and philosophical. Our discussions, so
+far as they relate to questions of actual fact, will contain only one
+other topic of the same importance.
+
+But though it is designed to complete and to deepen our analysis,
+the present considerations may yet be said to mark a point of rest
+in the whole of our discussions: we have followed one single line of
+argumentation from the beginning until now; this line or this stream of
+thought, as you might call it, is now to break into different branches
+for a while, as if it had entered from a rocky defile into a plain.
+It seems to me that such a short rest will be not unconducive to a
+right understanding of all we have made out; and such a full and real
+conceiving again, such a realising of our problems of morphogenesis and
+their solutions, will be the best preparation for the philosophical part
+of these lectures.
+
+
+HARMONIOUS-EQUIPOTENTIAL SYSTEMS FORMED BY WANDERING CELLS
+
+All of the harmonious-equipotential systems which we have studied so
+far were the bases of histological differentiation; that is to say, the
+processes of their differentiation consisted in specifically localised
+elements of theirs becoming different *in situ*. Now we know at least
+one type of systems which also may be called harmonious-equipotential,
+but the differentiation of which does not simply relate to elements at
+a fixed place. An additional phenomenon enters here into the sphere of
+the others. The elements not only become different where they are, but
+a specific changing of locality, a specific kind of wandering, goes
+hand-in-hand with differences relating to the prospective value to be
+attained. I am speaking of the formation of the larval skeleton of
+our well-known Echinus. We know that the mesenchyme cells, which have
+left the blastoderm and are arranged in a sort of ring of bilateral
+structure, are the starting-point of this skeleton: it indeed originates
+in a sort of secretive process on the part of the cells; the cells
+are moving about and are secreting carbonate of lime during their
+wandering. The experiments now have shown, as we know, that a whole,
+though smaller, skeleton may also be formed, if only a half or a quarter
+of the mesenchyme cells are present, as happens to be the case in all
+experiments with isolated blastomeres of the two or four-cell stage of
+cleavage. It is clear that in these cases the performance of each single
+cell must be different from what it is in the normal case, and that
+the same sort of differences in the morphogenetic performances appears
+again, if the two- and the four-cell stage are compared with each other.
+And there are still some other phenomena showing the possibility of
+different performances being carried out by the individual cells. Peter
+has shown that the number of mesenchyme cells may vary enormously under
+certain conditions; but, in spite of that, the skeleton always will
+be complete. It may be said that this line of research is only of a
+relative value to our own questions, as, of course, variability relates
+to different individuals: but it seems to me that it adds a very good
+supplementary instance to what the experiment on the individual itself
+has established.
+
+We should only be repeating ourselves if we were to analyse again what
+happens here as the expression of the harmonious-equipotentiality
+itself. But indeed there occurs something new in this instance: the
+single mesenchyme cell not only has to perform in each case that single
+act of specific secretion which the case requires, but it also has to
+wander to the right place in order to perform it; there must be some
+order, not only about the acts of secretion after wandering, but also in
+the migrations themselves. If undisturbed ontogeny alone were possible,
+and if therefore a theory like that of Weismann were in place, we might
+say perhaps that each mesenchyme-cell is specified not only as to its
+performance in secretion, but also with regard to its chemotactical
+irritability, the latter being typically localised, so that its effect
+becomes typical, thanks to the typical arrangement of all the cells
+with respect to each other. But that is certainly not the case. Now, you
+may ask yourselves if you could imagine any sort of a machine, which
+consists of many parts, but not even of an absolutely fixed number, all
+of which are equal in their faculties, but all of which in each single
+case, in spite of their potential equality, not only produce together
+a certain typical totality, but also arrange themselves typically in
+*order* to produce this totality. We *are* indeed familiar with certain
+occurrences in nature where such curious facts are observed, but I doubt
+if you would speak of “machines” in these cases. The mesenchyme-cells,
+in fact, behave just as a number of workmen would do who are to
+construct, say, a bridge. All of them *can* do every single act, all of
+them also *can* assume every single position: the result always is to
+be a perfect bridge; and it is to be a perfect bridge even if some of
+the workmen become sick or are killed by an accident. The “prospective
+values” of the single workman change in such a case.
+
+I well know that it is only an analogy which I am offering to you.
+The mesenchyme-cells have not “learned,” have no “experience.” All
+that is to occupy us next summer. But in spite of it, there is truth
+in the analogy; and perhaps you will prefer it to the merely abstract
+consideration.
+
+
+ON CERTAIN COMBINED TYPES OF MORPHOGENETIC SYSTEMS
+
+For the sake of completeness it may be remarked, only by the way, that
+the type of the proper harmonious-equipotential system may go hand in
+hand with another type of “systems” which play a part in morphogenesis;
+a type which we have shortly mentioned already and which will be studied
+fully a few chapters later. We know that there are equipotential systems
+with complex potencies: that is to say, systems which may produce a
+whole organism equally well from any one of their elements; we know the
+cambium of Phanerogams to be such a system. Now it is easily understood
+that the germ of our Echinus, say in the stage of two or four or eight
+cleavage cells, is not only an harmonious-equipotential system, but
+a complex-equipotential system too. Not only may there arise a whole
+organism out of 2/4 or 3/4 or 3/8, 4/8, 5/8, 6/8, 7/8 of its elements,
+in which cases the harmonious rôle of the single element with regard to
+its single performance in a totality is variable, but there may also
+arise four whole single larvae out of the four cells of the four-cell
+stage, or eight single whole larvae out of the eight-cell stage.[67]
+In these cases, of course, each of the four or eight elements has
+performed not a part of the totality, changing with its “position,” but
+the totality itself. With respect to these possible performances the
+“systems” present in the four or eight-cell stages of cleavage must be
+called complex-equipotential ones.
+
+[67] The eight larvae would be incomplete in some respect, but not with
+regard to symmetry. They would be “whole” ones, only showing certain
+defects in their organisation. See page 65 note 1, and page 73.
+
+We propose to give the name of *mixed-equipotential systems* to all
+those equipotential systems which, at the same time, may be regarded
+as belonging to the harmonious or to the complex type. It is not only
+among cleavage-stages that they are to be found; you may also find them
+very clearly exhibited in our ascidian *Clavellina* for instance. We
+know already that the branchial apparatus of this form is typically
+harmonious-equipotential, but it is complex-equipotential too, for it
+also may regenerate what is wanting in the proper way, by a budding
+from the wound; and the same is true of many other cases, the flatworm
+*Planaria* for instance.
+
+Another type of systems, which might be said to be of a higher degree,
+is exhibited in some very strange phenomena of regeneration. It was
+first shown most clearly by some experiments of Godlewski’s that a
+whole tail may be regenerated from a wound inflicted on the body of
+a newt, even if this wound involves section of only a portion of the
+body-diameter. Section of the whole of the body-diameter of course
+would cause the formation of the whole tail also; but it was found that
+even an incomplete cross-section of the body is capable of performing
+the whole on a smaller scale. The series of possible cross-sections
+which are all capable of regeneration would have to be called a
+system of the complex type in this case; but, now we learn that every
+*single* cross-section is of the harmonious type, we must speak of
+*complex-harmonious systems*. What we have described is not the only
+instance of our new type of morphogenetic systems. Some other instances
+had been discovered a few years earlier, though nobody had pointed
+out their true significance. In the flatworm *Planaria* a partial
+cross-section is also capable of forming a whole structure, say a head,
+and all cases of so-called “super-regeneration” after the infliction of
+a complicated wound probably belong here also.
+
+You may say that our two additions to the theory of systems are merely
+formal, and indeed I am prepared to concede that we shall not learn
+anything altogether new from their discussion: their analysis would lead
+either to what was our “first proof” of the autonomy of life-phenomena
+or to what will be our “second” one. But the mere descriptions of the
+facts discovered here will interest you, I think, and will fill your
+minds with more vivid pictures of the various aspects of form-autonomy.
+
+While dealing with our harmonious-equipotential systems as the
+starting-points of processes of restitution, *e.g.* in *Tubularia*,
+*Clavellina*, the flatworms, and other instances, we always have
+regarded cross-sections of the body as constituting the elements of
+equipotentiality. Now cross-sections, of course, are by no means simple
+in themselves, but are made up of very different tissues, which are
+derivates of all three of the original germ layers--ectoderm, mesoderm,
+and endoderm. Owing to this composite character of the cross-sections,
+taken as elements of harmonious systems, a special phenomenon of
+morphogenesis is presented to us, which teaches somewhat more than the
+mere concept of harmonious-equipotentiality can express. If composite
+elements concerned in morphogenesis result in one whole organisation
+in spite of the development of the single tissues of these elements
+going on independently, then there must be a sort of correspondence
+or reciprocity of the harmonious development among these tissue
+constituents themselves; otherwise a proportionate form could not be the
+final result. We may conveniently speak of a *reciprocity of harmony* as
+existing between the single tissues or germ layers which constitute many
+harmonious-equipotential systems, and there can be little doubt that we
+have here an important feature with regard to general morphogenesis.[68]
+
+[68] Reciprocal harmony may be reduced in some cases to the given
+proportions of one original harmonious system, from which the single
+constituents of the complicated system, showing reciprocal harmony, are
+derived. Then we have only an instance of “harmony of constellation”
+(see p. 109). But reciprocal harmony seems to become a problem itself,
+if it occurs in restitutions starting from quite a typical point,
+selected by the experimenter. It will be a problem of future research
+to give an exact formula of what happens here. Reciprocal harmony also
+occurs in regeneration proper. It is known that the formation of the
+regenerative bud and the differentiation of this bud follow each other.
+As the bud is composed of different elementary systems, it follows that
+these different systems, of which every single one is harmonious, also
+have to work in reciprocity to each other, in order that one whole
+proportionate formation may result.
+
+A few other groups of morphogenetic facts may find their proper place
+here, though they are not properly to be regarded as additions to the
+theory of harmonious systems but as forming a sort of appendix to it.
+
+
+THE “MORPHAESTHESIA” OF NOLL[69]
+
+[69] *Biol. Centralblatt.* 23, 1903.
+
+We may briefly mention that group of botanical phenomena, by which
+the botanist Noll has been led to the concept of what he calls
+“morphaesthesia,” or the “feeling” for form; a concept, the full
+discussion of which would lead to almost the same conclusions as our
+analysis of the harmonious systems has done. In the Siphoneae, a
+well-known order of marine algae with a very complicated organisation
+as to their exterior form, the protoplasm which contains the nuclei is
+in a constant state of circulation round the whole body, the latter
+not being divided by proper cell-walls. On account of this constant
+movement it is certainly impossible to refer morphogenetic localisation
+to definite performances of the nuclei. Nor can any sort of structure
+in the outer protoplasmic layer, which is fixed, be responsible for
+it, for there is no such structure there: hence there must be a sort
+of feeling on the part of the plant for its relative body localities,
+and on account of this feeling morphogenesis occurs. This “feeling” is
+styled “morphaesthesia” by Noll, and to it he tries to refer all sorts
+of different botanical form-phenomena,[70] for instance what is called
+“autotropism,” that is, the fact that branches of plants always try to
+reassume their proper angle with regard to their orientation on the main
+axis, if this orientation has been disturbed. It may be an open question
+if this particular application of the theory is right: certainly
+there seems to be much truth in the establishment of the concept of
+morphaesthesia, and we only have to object to its psychological name.
+But that may be done in a more general form on a later occasion.
+
+[70] Certain phenomena of the physiology of growth of *Geranium
+Robertianum*, recently discussed by Francé from a vitalistic point of
+view (*Zeitschr. Entw. lehre*. 1, 1907, Heft iv.), might also belong
+here. I cannot see an independent proof of vitalism in these facts if
+taken by themselves; a pre-existing “machine” cannot be absolutely
+excluded here.
+
+
+RESTITUTIONS OF THE SECOND ORDER
+
+In the hydroid polyp *Tubularia*, already familiar to us as being a most
+typical representative of the harmonious-equipotential systems, a very
+interesting phenomenon has been discovered[71], almost unparalleled at
+present but nevertheless of a general importance, a phenomenon that
+we may call a restitution of a restitution, or a restitution of the
+second order. You know that the first appearance of the new head of
+*Tubularia*, after an operation, consists in the formation of two rings
+of red lines, inside the stem, these rings being the primordia of the
+new tentacles. I removed the terminal ring by a second operation soon
+after it had arisen, disturbing in this way the process of restitution
+itself: and then the process of restitution itself became regulated. The
+organism indeed changed its course of morphogenesis, which was serving
+the purposes of a restitution, in order to attain its purpose in spite
+of the new disturbance which had occurred. For instance, it sometimes
+formed two rings out of the one that was left to it, or it behaved
+in a different way. As this difference of morphogenetic procedure is
+a problem by itself, to be discussed farther on, we shall postpone a
+fuller description of this case of a restitution of the second degree.
+
+[71] Driesch, *Arch. Entw. Mech.* 5, 1897.
+
+At present I do not see any way of proving independently the autonomy of
+life by a discussion of these phenomena; their analysis, I think, would
+again lead us to our problem of localisation and to nothing else; at
+least in such an exact form of reasoning as we demand.
+
+
+ON THE “EQUIFINALITY” OF RESTITUTIONS[72]
+
+[72] Driesch, *Arch. Entw. Mech.* 14, 1902.
+
+I have told you already that *Tubularia* in the phenomena of the
+regulation of restitutions offers us a second problem of a great general
+importance, the problem of the *Equifinality of Restitutions*. There
+indeed may occur restitutions, starting from one and the same initial
+state and leading to one and the same end, but using very different
+means, following very different ways in the different individuals of one
+and the same species, taken from the same locality, or even colony.
+
+Imagine that you have a piece of paper before you and wish to sketch
+a landscape. After drawing for some time you notice that you have
+miscalculated the scale with regard to the size of the paper, and
+that it will not be possible to bring upon the paper the whole of the
+landscape you want. What then can you do? You either may finish what you
+have begun to draw, and may afterwards carefully join a new piece of
+paper to the original one and use that for the rest of the drawing; or
+you may rub out all you have drawn and begin drawing to a new scale; or
+lastly, instead of continuing as you began, or erasing altogether, you
+may compromise as best you can by drawing here, and erasing there, and
+so you may complete the sketch by changing a little, according to your
+fancy, the proportions as they exist in nature.
+
+This is precisely analogous to the behaviour of our *Tubularia*.
+*Tubularia* also may behave in three different ways, if, as I described
+to you, the terminal one of its two newly arisen rings of tentacle
+primordia is removed again. It may complete what is left, say the basal
+tentacle ring, then put forth from the horny skeleton (the “perisarc”)
+the new head as far as it is ready, and finally complete this head
+by a regular process of budding regeneration. But it also may behave
+differently. It may “erase” by a process of retro-differentiation all
+that has been left of what had already been formed, and then may form
+*de novo* the totality of the primordia of a new head. Or, lastly, it
+may remove a part of the middle of the one ring of tentacle rudiments
+which was left, and may use this one ring for the formation of two,
+which, of course, will not be quite in the normal relations of place
+with regard to each other and to the whole, but will be regulated
+afterwards by processes of growth. Thus, indeed, there is a sort of
+equifinality of restitution: one starting-point, one end, but three
+different means and ways.
+
+It would, of course, contradict the principle of univocality, as we
+shall see more fully later on, to assume that there actually are
+different ways of regulation whilst all the conditions and stimuli are
+the same. We are obliged to assume, on the contrary, that this is not
+the case, that there are certain differences in the constellation, say
+of the general conditions of age or of metabolism, which are responsible
+for any given individual choosing one process of restitution instead
+of another; but even then the phenomenon of equifinality remains very
+striking.
+
+It has long been known that restitution in general does not always
+follow the same lines of morphogenesis as are taken by ontogeny, and it
+was this feature that once led Roux to point out that the adult forms
+of organisms seem to be more constant than their modes of origin. But,
+comparing ontogeny with restitution in general, we see that only the
+ends are the same, not the points of starting; the latter are normal or
+non-typical in ontogeny, atypical in restitution. In the new discoveries
+of an equifinality of restitutions we have the *same* starting-point,
+which is decidedly non-typical but atypical, *i.e.* dependent on our
+arbitrary choice, leading by *different* ways always to the *same* end.
+
+There may be many who will regard the fact of equifinality as a proof of
+vitalism. I should not like to argue in this easy way; I indeed prefer
+to include part of the phenomena of equifinality in our first proof of
+autonomy, and part in the second one, which is to follow.
+
+Another important phenomenon of the equifinality of regulation was
+discovered by Morgan. A species of the flatworm *Planaria* was found to
+restore its totality out of small pieces either by regeneration proper,
+if the pieces were fed, or by a sort of rearrangement of material,
+on the basis of its harmonious-equipotentiality, if they were kept
+fasting. It is important to note that here we see one of the conditions
+determining the choice of the way to restoration, as we also do in the
+well-known equifinal restitutions of the root in plants, where the
+behaviour of the organism depends on the distance of the operation-wound
+from the tip.[73] In *Tubularia* the actual stage of restitution that
+has been already reached by the stem when the second operation takes
+place, may account for the specification of its future organogenesis,
+but this is not at all clearly ascertained at present.
+
+[73] The root may be restored by regeneration proper, or by the
+production of adventitious roots, or by one of the side-roots changing
+its geotropism from horizontal to positive, according to the smaller or
+greater distance of the wound from the tip.
+
+*Clavellina* also shows equifinality in its restitution, as has already
+been shortly mentioned. The isolated branchial apparatus may restitute
+itself by retro-differentiation to an indifferent stage followed by
+renovation; or it may regenerate the intestine-sac in the proper way.
+Nothing is known here about the conditions, except perhaps that young
+individuals seem more apt to follow the first of these two ways, older
+ones the second; but there are exceptions to this rule.
+
+The discussion of other instances of equifinality, though important in
+themselves, would not disclose anything fundamentally new, and so we may
+close the subject with the remark that nothing can show better than the
+fact of the equifinality of restitutions how absolutely inadequate all
+our scientific conceptions are when confronted with the actual phenomena
+of life itself. By analysis we have found differences of potencies,
+according as they are simple or complex; by analysis we have found
+differences of “systems,” differences of means, and indeed we were glad
+to be able to formulate these differences as strictly as possible: but
+now we see how, in defiance of our discriminations, one and the same
+species of animals behaves now like one sort of our “systems,” and now
+like the other; how it uses now one sort of “potencies,” now another.
+
+But even if it is granted that, in the presence of such phenomena of
+life, our endeavour seems to be like a child’s play on the shores of the
+ocean, I do not see any other way for us to go, so long, at least, as
+our goal is human science--that is, a study of facts as demanded by our
+mental organisation.
+
+
+REMARKS ON “RETRO-DIFFERENTIATION”
+
+We shall finish this part of our studies by mentioning a little more
+explicitly one fundamental fact which has already entered incidentally
+into our considerations, viz. *retro-* or *back-differentiation*.[74]
+We know that it occurs in *Clavellina* and in *Tubularia*; we may add
+that it also happens in *Hydra*, and that in the flatworm *Planaria*
+the pharynx, if it is too large for a piece that is cut out, may be
+differentiated back and be replaced by a new pharynx, which is smaller.
+
+[74] “Retro”-differentiation, of course, is not “Re”-differentiation
+(“Umdifferenzierung,” see p. 111), though it may help it to occur.
+
+It is not death and sloughing of parts that occurs in these cases,[75]
+but a real process of active morphogenesis; not, however, a process
+consisting in the production of visible manifoldness, but the opposite.
+Loeb was the first to lay much stress upon this topic, and indeed, there
+may appear a very strange problem in its wake: the problem, whether
+*all* morphogenesis might be capable perhaps of going backwards under
+certain conditions.
+
+[75] Of course such a real decay of parts may happen in other cases.
+
+It is important to note that in most[76] cases retro-differentiation
+occurs in the service of restitution: it goes on wherever restitution
+requires it. This fact alone would show that not very much could be
+explained here by the discovery of modern chemistry, important as
+it is, that one and the same “ferment” or “enzyme” may affect both
+the composition and the decomposition of the same compound. We could
+regard what is called “catalysis” solely as an agent in the service of
+entelechy. But this point also will become clearer in another part of
+the work.
+
+[76] Certain cases of retro-differentiation occurring under conditions
+of strict fasting will be described in a later chapter.
+
+
+
+
+*C.* ADAPTATION
+
+INTRODUCTORY REMARKS ON REGULATIONS IN GENERAL
+
+
+We have finished our long account of individual morphogenesis proper.
+If we look back upon the way we have traversed, and upon those topics
+in particular which have yielded us the most important general results,
+the material for the higher analysis which is to follow, it must
+strike us, I think, that all these results relate to regulations.
+In fact, it is “secondary” form-regulations, according to our
+terminology, that we have been studying under the names of equifinality,
+back-differentiation, restitution of the second order, and so on, and
+our harmonious-equipotential systems have figured most largely in
+processes of secondary form-regulations also. But even where that has
+not been the case, as in the analysis of the potencies of the germ in
+development proper, form-regulations of the other type have been our
+subject, regulations of the primary or immanent kind, the connection
+of normal morphogenetic events being regulatory in itself. It was not
+the phenomenon of organic regulation as such that afforded us the
+possibility of establishing our proof of the autonomy of morphogenesis:
+that possibility was afforded us by the analysis of the distribution of
+potencies; but upon this distribution regulation is based, and thus
+we may be said to have studied some types of regulation more or less
+indirectly when analysing potencies.
+
+It therefore seems to me that we shall have hopes of a successful issue
+to our inquiries, if we now, on passing to what is called the physiology
+of the vegetative functions, proceed to focus our attention on the
+concept of regulation as such. And that is what we shall do: on our
+way through the whole field of physiology, we shall always stop at any
+occurrence that has any sort of regulatory aspect, and shall always ask
+ourselves what this feature has to teach us.
+
+But let us first try to give a proper definition of our concept. We
+shall understand by “regulation” any occurrence or group of occurrences
+on a living organism which takes place after any disturbance of
+its organisation or normal functional state, and which leads to a
+reappearance of this organisation or this state, or at least to a
+certain approach thereto. Organisation is disturbed by any actual
+removal of parts; the functional state may be altered by any change
+among the parts of the organism on the one hand, by any change of the
+conditions of the medium on the other; for physiological functioning
+is in permanent interaction with the medium. It is a consequence of
+what we have said that any removal of parts also changes the functional
+state of the organism, but nevertheless organisation is more than a mere
+sum of reactions in functional life. All regulations of disturbances
+of organisation may be called *restitutions*, while to regulations of
+functional disturbances we shall apply the name *adaptations*. It is
+with *adaptations* that we have to deal in the following.
+
+Let us begin our studies of adaptations in a field which may justly
+be called a connecting link between morphogenesis and physiology
+proper, not yet wholly separated from the science of the organic form,
+morphology.
+
+
+1. MORPHOLOGICAL ADAPTATION
+
+*Morphological adaptation* is a well-established fact, and I need only
+mention the striking differences between the land and water form of
+amphibious plants, or the differences between the same species of plants
+in the Alps and in the plains, or the very different aspect of the arms
+of an athlete and of an ascetic, to recall to your memory what is meant
+by this term.
+
+Morphological adaptation is no part of individual morphogenesis proper,
+but occurs at the end of it; at least it never occurs previous to the
+full individual life of an organism, previous to its true functional
+life; for it relates to the functions of the complete organism.
+
+
+THE LIMITS OF THE CONCEPT OF ADAPTATION
+
+It is especially, though by no means exclusively, among plants that
+morphological adaptation assumes its most marked forms; and this topic,
+indeed, may very easily be understood if we remember that plant-life
+is in the very closest permanent dependence on the medium, and that
+this medium is liable to many changes and variations of all kinds.
+In order to elucidate our problem, it therefore seems convenient to
+restrict our considerations for a while to the study of plants. There
+exist very many external formative stimuli in the morphogenesis of
+vegetation: would it then be possible to regard every effect of such
+an external formative stimulus as a real morphological adaptation?
+No; for that would not meet the point. The general *harmony* of form
+is indeed concerned if gravity forces roots to shoot forth below at a
+spot where they can enter the ground, or if light induces branches and
+leaves to originate at places where they can obtain it for assimilation;
+but gravity and light themselves are mere formative stimuli--of the
+localising type--in these instances, for they relate only to the
+individual production of form, not to the functioning of already
+existing form. We therefore are warned not to confuse the effects of
+formative stimuli from without with real adaptive effects until we have
+fully analysed the particular case.
+
+We have drawn a sharp line between causes and means of morphogenesis,
+applying the term “means” to those conditions of the morphogenetic
+process which relate neither to the specificity nor to the localisation
+of its constituents, though they are necessary for the accomplishment
+of the process in the most thorough manner. Would it be possible to
+connect our new concept of an adaptation with our well-established
+concept of a means of morphogenesis in such a way that we might speak
+of a morphological “adaptation” whenever any specific feature about
+morphogenesis proves to be immediately dependent for its success on some
+specific means, though it does not owe its localisation to that means
+as its “cause”? It seems to me that such a view would also fall wide
+of the mark. It is well known, for instance, that the flowers of many
+plants never fully develop in the dark; light is necessary for their
+morphogenesis. Is, therefore, their growth in the presence of light to
+be called a morphological “adaptation” to light? Certainly not: they
+simply *cannot* originate without light, because they require it for
+some reason. It is precisely here that our conception of light as a
+“means” of morphogenesis is most fully justified. There are many[77]
+such cases; and there are still others of an apparently different
+type, but proving the same. All pathological forms produced in plants
+by animal parasites or by parasitic fungi could hardly be called
+adaptations, but must be attributed to some abnormality of means or of
+stimuli. It may be that the organism reacts as well as possible in these
+cases, and that if it reacted otherwise it would die--we know absolutely
+nothing about this question. But even then there would only be some sort
+of regulation *in* the process of pathological morphogenesis, but *the
+process* itself could hardly be called adaptive.
+
+[77] Klebs has suppressed the reproductive phase of organisation
+altogether, in fungi as well as in flowering plants, or has made it
+occur abnormally early, merely by changing the “external conditions”
+and by altering the “internal” ones correspondingly. There is hardly
+anything like an adaptation in these cases, which, by the way, offer
+certain difficulties to analysis, as the boundaries between “cause” and
+“means” are not very sharp here.
+
+So far we have only learned what is not to be regarded as morphological
+adaptation. No response to external formative stimuli is in itself an
+example of adaptation, nor are processes dependent for their existence
+on any kind of condition or means to be called, simply because they are
+dependent on them, adaptations to those agents. What then, after all, is
+a morphological adaptation?
+
+Let us remember what the word adaptation is really to mean in our
+discussions: a state of functioning is adapted--a state of functioning
+must therefore have been disturbed; but as functioning itself, at least
+in plants, certainly stands in close relations to the medium, it follows
+that all adaptations are in the last resort connected with those factors
+of the medium which affect functioning. In being correctives to the
+disturbances of functioning they become correctives to the disturbing
+factors themselves.
+
+But again, the question seems to arise whether these factors of the
+medium, when they provoke an adaptation by some change that is followed
+by functional disturbance, do so in the capacity of “causes” or of
+“means,” and so it might seem that we have not gained very much so far
+by our analysis. The reproach, however, would not be quite justified,
+it seems to me: we indeed have gained a new sort of analytical concept,
+in the realm of causal concepts in general, by clearly stating the
+point that adaptations are related directly to functionality, and only
+indirectly, through functionality, to external changes. By the aid of
+this logical formulation we now are entitled to apply the term “cause,”
+in our restricted sense of the word, to every change of the medium
+which is followed by any sort of adaptation in regard *to itself*. Our
+definition stated that a “cause” is any one of the sum of necessary
+factors from without that accounts either for the localisation *or* for
+*the specification* of the effect, and the definition holds very well in
+this case. Indeed, the specification of the effect is determined *by*
+the outside factor in every case of an adaptation *to* it, by the mere
+*fact* of its being a specific adaptation to this specific factor.
+
+We must not forget that in this chapter we are not studying real
+individual morphogenesis as the realisation of what has been inherited,
+but that at present we regard morphogenesis proper as an accomplished
+fact. Morphogenesis proper has laid the general lines of organisation;
+and now adaptation during the functional life, so to speak, imposes a
+second kind of organisation upon the first. It is for that reason that
+the meaning of the word “cause” is now becoming a little different from
+what it was before.
+
+In order to study a little more in detail what has been discovered
+about morphological adaptation in animals and plants, let us separate
+our materials into two groups, one of them embracing adaptations with
+regard to functional changes from without, the other adaptations to
+those functional changes which come from the very nature of functioning.
+Almost all of our previous general considerations have applied to the
+former group, with which we shall now proceed to deal.
+
+
+ADAPTATIONS TO FUNCTIONAL CHANGES FROM WITHOUT[78]
+
+[78] Compare Herbst, *Biol. Centralbl.* 15, 1895; and Detto, *Die
+Theorie der direkten Anpassung*, Jena, 1904. A full account of the
+literature will be found in these papers.
+
+The differences between plants grown in very dry air, very moist air,
+and water, respectively, are most distinctly seen in all the tissues
+that assist in what is called transpiration, that is, the exchange of
+water-vapour between the plant and the medium, but especially in the
+epidermis and the conductive fibres, both of which are much stronger
+in plants grown in the dry. Indeed, it seems from experiments that
+transpiration is the most essential factor to which “adaptation” occurs
+in amphibious plants, though the changes of the mechanical conditions
+according to the medium also seem to have some sort of structural
+effect. If plants stand very deeply in water, the conditions of
+illumination, so important for assimilation in plants, may have been
+altered, and therefore much of the structural change can be attributed
+also to them. It is unimportant in our general question what is due to
+one of these factors and what to the other. That there is a real sort
+of adaptation cannot be doubtful; and the same is true, as experimental
+observations of the last few years have shown, with regard to the
+structural differences between so-called sun-leaves and shade-leaves
+of plants grown in the air: it has been actually shown here that the
+functional life of the former goes on better in the sun, of the latter
+better in the shade.
+
+It is very important to emphasise this point, as the adaptive character
+of all sorts of structural differences in plants dependent on light
+and on moisture has lately been denied, on the supposition that there
+is only a stopping of organogenesis in the case of the more simple,
+a continuance in the case of the more complicated modification, but
+nothing else. Indeed, all morphological adaptation has been conceived
+as only consisting in differences dependent upon the absence or the
+presence of necessary means or causes of development, and as offering
+no problem of its own. We have gained the right position from which
+to oppose this argument, it seems to me, in our formula that all
+adaptations do relate *not* directly *to* the agents of the medium,
+but to changes of functional states induced *by* those agents; that
+adaptations only *are* “adaptations” by being correctives to the
+functional state.
+
+There simply *is* an “adaptation” of structure in *such* a sense in all
+the cases we have mentioned. We can say neither more nor less. Granted
+that one of the outside factors which comes into account is merely a
+necessary “means”: then why is the histological consequence of the
+presence of the means an actual adaptation to it as far as its relation
+to functioning is concerned--why is the consequence of its absence also
+an adaptation to this absence in its relation to functioning? Why, to
+complete the series, is the degree of the consequence of its presence an
+adaptation to the degree of its presence?
+
+All these relationships, which are so many facts, have been absolutely
+overlooked by those who have been pleased to deny morphological
+adaptation to functional changes from without.
+
+To do full justice to them we may speak of “primary” regulative
+adaptations in all the cases mentioned above, applying the word
+“primary,” just as was done with regard to restitutions, to the fact
+that there is some sort of regulation *in* the normal connection of
+processes. We reserve the title of “secondary adaptations” for cases
+such as those described, for instance, by Vöchting,[79] where not
+merely one and the same tissue originates adaptively with regard to the
+degree of its normal functioning, but where a profound disturbance
+of all functioning connections, due to the removal of portions of the
+organisation, is followed by histological changes at absolutely abnormal
+localities; that is, where a real change of the *kind* of functioning
+is the consequence of the adaptation. It, of course, will be found very
+difficult to discriminate such phenomena from real restitutions, though
+logically there exists a very sharp line between them.
+
+[79] Vöchting (*Jahrb. wiss. Bot.* 34, 1899) forced the bulbs of
+plants to become parts of the stem, and parts of the stem to form
+bulbs; in both cases the most characteristic changes in histology
+could be observed, being in part adaptations, but in part restitutions
+of the proper type. (See also my *Organische Regulationen*, 1901, p.
+84.) A true and simple instance of a “secondary adaptation” seems to
+be furnished in a case described by Boirivant. In *Robinia* all the
+leaflets of a leaf-stalk were cut off: the leaf-stalk itself then
+changed its structure in order to assist assimilation, and also formed
+real stomata.
+
+A few more concrete instances may now close this account of adaptation
+to functional changes coming from without. Though almost all the
+adaptive characters in the aquatic forms of amphibious plants represent
+a less complicated state of organisation than the corresponding
+structures in their terrestrial forms, and therefore have wrongly
+been regarded as simply due to a stopping of morphogenesis for want
+of necessary means, yet there are a few of them that are positive
+complications in comparison with the land-forms: the so-called
+aërenchyme, especially well developed in the water-form of *Jussiaea*
+is such an instance. This tissue stands in the direct service of
+respiration, which is more difficult to be accomplished under water than
+ordinarily, and represents a true adaptation to the altered function.
+
+Among animals there is only one well-studied instance of our first type
+of adaptive morphological characters. *Salamandra atra*, the black
+salamander, a species which only inhabits regions at least two thousand
+feet above sea-level, does not bring forth its young until metamorphosis
+has taken place. The larvae, however, may be removed from the mother’s
+body at an earlier stage and forced to complete their development in
+water. Under these circumstances, as was shown in an excellent memoir
+by Kammerer,[80] they will change the whole histological type of their
+gills and skin in order to meet the new functional conditions. The
+change of the conditions of functioning is very severe here, for whereas
+the gills had served for nutrition and respiration in the uterus--by
+a process of endosmosis--they now serve for respiration only, and, of
+course, are surrounded by quite an abnormal chemical medium.
+
+[80] *Arch. Entw. Mech.* 17, 1904.
+
+
+TRUE FUNCTIONAL ADAPTATION[81]
+
+[81] Roux, *Gesammelte Abhandlungen*, vol. i. 1895; in particular, *Der
+Kampf der Teile im Organismus*, Leipzig, 1881.
+
+But all other cases of morphological adaptation among animals, and
+several in the vegetable kingdom too, belong to our second group of
+these phenomena, which in our analytical discussion we have called
+adaptations to functional changes that result from the very nature
+of functioning, and which we shall now call by their ordinary name,
+“functional adaptation.”
+
+It was Roux who first saw the importance of this kind of organic
+regulation and thought it well to give it a distinguishing name. *By
+functioning the organisation of organic tissues becomes better adapted
+for functioning.* These words describe better than any others what
+happens. It is well known that the muscles get stronger and stronger the
+more they are used, and that the same holds for glands, for connective
+tissue, etc. But in these cases only quantitative changes come into
+account. We meet with functional adaptations of a much more complicated
+and important kind, when for instance, as shown by Babák,[82] the
+intestine of tadpoles changes enormously in length and thickness
+according as they receive animal or vegetable food, being nearly twice
+as long in the second case. Besides this the so-called mechanical
+adaptations are of the greatest interest.
+
+[82] *Arch. Entw. Mech.* 21, 1906. By a very detailed comparative study
+Babák was able to prove that it is the plant proteids to which the
+effect of vegetable food is chiefly due; thus we have an adaptation
+to digestibility. Mechanical circumstances are only of secondary
+importance. (See also Yung.)
+
+It has long been known, especially from the discoveries of Schwendener,
+Julius Wolff, and Roux, that all tissues whose function it is to resist
+mechanical pressure or mechanical tension possess a minute histological
+structure specially suitable to their requirements. This is most
+markedly exhibited in the stem of plants, in the tail of the dolphin, in
+the arrangements of the lime lamellae in all bones of vertebrates. All
+these structures, indeed, are such as an engineer would have made them
+who knew the sort of mechanical conditions they would be called upon to
+encounter. Of course all these sorts of mechanically adapted structures
+are far from being “mechanically explained,” as the verbal expression
+might perhaps be taken to indicate, and as indeed has sometimes been the
+opinion of uncritical authors. The structures exist *for* mechanics,
+not *by* it. And, on the other hand, all these structures, which we
+have called mechanically “adapted” ones, are far from being mechanical
+“adaptations,” in our meaning of the word, simply because they are
+“adapted.” Many of them indeed exist previous to any functioning, they
+are for the most part truly inherited, if for once we may make use of
+that ambiguous word.
+
+But, the merely descriptive facts of mechanical adaptedness having been
+ascertained, there have now been discovered real mechanical processes
+of adaptations also. They occur among the statical tissues of plants,
+though not in that very high degree which sometimes has been assumed
+to exist; they also occur in a very high perfection in the connective
+tissue, in the muscles and in the bone tissue of vertebrates. Here
+indeed it has proved possible to change the specific structure of the
+tissue by changing the mechanical conditions which were to be withstood,
+and it is in cases of healing of broken bones that these phenomena have
+acquired a very great importance, both theoretically and practically:
+the new joints also, which may arise by force of circumstances,
+correspond mechanically to their newly created mechanical function.
+
+So far a short review of the facts of “functionelle Anpassung.” They
+seem to prove that there does exist a morphological adaptation to
+functional changes which result from the very nature of functioning. In
+fact, the actual state of all functioning tissue, the intensity of its
+state of existence, if you care to say so, may be said to be due to the
+functioning itself: the so-called atrophy by inactivity being only one
+extreme of a very long line of correspondences.[83]
+
+[83] Atrophy of muscles by inactivity is not to be confused with atrophy
+by cutting the motor nerve; the latter is very much more complete.
+
+We now, of course, have to ask ourselves if any more intimate analysis
+of these facts is possible, and indeed we easily discover that here
+also, as in the first of our groups of morphological adaptations,
+there are always single definite agents of the medium, which might be
+called “causes” or “means” of the adaptive effects, the word “medium”
+being taken as embracing everything that is external to the reacting
+cells. But of course also here the demonstration of single formative
+agents does not detract in the least from the adaptive character of
+the reaction itself. So we may say, perhaps, that localised pressure
+is the formative stimulus for the secretion of skeleton substance at a
+particular point of the bone tissue, or of the fibres of the connective
+tissue; the merely quantitative adaptations of muscles might even
+allow of a still more simple explanation.[84] But adaptations remain
+adaptations in spite of that; even if they only deserve the name of
+“primary” regulations.
+
+[84] Loeb has advocated the view that the “adaptive” growth of working
+muscles is simply due to the presence of a greater number of molecules
+in their protoplasm, muscular activity being generated by a process of
+chemical decomposition.
+
+
+THEORETICAL CONCLUSIONS
+
+We have stated in the analytical introduction to this chapter and
+elsewhere, that functional changes, which lead to morphological
+adaptations of both of our groups, may arise not only from changes of
+factors in the medium, but also from a removal of parts. As such removal
+is generally followed by restitution also, it is clear that restitutions
+and adaptations very often may go hand in hand, as is most strikingly
+shown in a fine series of experiments carried out by Vöchting, which we
+have already alluded to. Here again I should like to lay the greatest
+stress upon the fact that, in spite of such actual connections,
+restitutions and adaptations always have been separated from another
+theoretically, and that the forms are never to be resolved into sums
+of the latter. Such a view has been advocated by some recent authors,
+especially by Klebs, Holmes, and Child:[85] it is refuted I think by the
+simple fact that the first phase of every process of restitution, be it
+regeneration proper or be it a sort of harmonious differentiation, goes
+on without functioning at all, and only *for* future functioning.[86]
+
+[85] What has been really *proved* to exist by the very careful studies
+carried out by Child, is only certain cases of functional adaptation
+to mechanical conditions of the strictest kind, and relating to the
+general mobility only, but nothing more; such adaptations can be said to
+accompany restitution. See, for instance, *Journ. exp. Zool.* 3, 1906,
+where Child has given a summary of his theory.
+
+[86] Even in Vöchting’s experiments (see page 174, note 1), in which
+adaptations are mixed with true restitutions in the closest possible
+manner, a few phenomena of the latter type could most clearly be
+separated. The stimulus which called them forth must have been one of
+the hypothetic sort alluded to in a former chapter (see page 113). The
+best instances of true restitutions were offered in those cases, where,
+after the removal of all the bulbs, typical starch-storing cells were
+formed without the presence of any starch.
+
+And there has been advocated still another view in order to amplify
+the sphere of adaptation: all individual morphogenesis, not only
+restitution, is adaptation, it has been said. In its strictest form
+such an opinion of course would simply be nonsense: even specific
+adaptive structures, such as those of bones, we have seen to originate
+in ontogeny previous to all specific functions, though for the help
+of them, to say nothing of the processes of the mere outlining of
+organisation during cleavage and gastrulation. But they are “inherited”
+adaptations, it has been answered to such objections. To this remark we
+shall reply in another chapter. It is enough to state at present that
+there *is* a certain kind of, so to speak, architectonic morphogenesis,
+both typical and restitutive, previous to specific functioning
+altogether.
+
+If now we try to resume the most general results from the whole field
+of morphological adaptations, with the special purpose of obtaining new
+material for our further philosophical analysis, we have reluctantly to
+confess that, at present at least, it does not seem possible to gather
+any new real proof of life-autonomy, of “vitalism,” from these facts,
+though of course also no proof against it.
+
+We have stated that there is in every case of both our types of
+adaptive events a correspondence between the degree of the factor
+to which adaptation occurs, and the degree of the adaptive effect.
+We here may speak of an *answering* between cause and effect with
+regard to adaptation, and so perhaps it may seem as if the concept of
+an “answering reaction” (“Antwortsreaktion”), which was introduced
+into science by Goltz[87] and which is to play a great part in our
+discussions of next summer, may come into account: but in our present
+cases “answering” only exists between a simple cause and a simple effect
+and relates almost only to quantity and locality. There is therefore
+lacking the most important feature, which, as will be seen, would have
+made the new concept of value.
+
+[87] *Beiträge zur Lehre von den Functionen der Nervencentren des
+Frosches*, Berlin, 1869.
+
+We only, I believe, can state the fact that there *are* relations
+between morphogenetic causes and effects which *are* adaptations, that
+functional disturbances or changes are followed by single histogenetic
+reactions from the organism, which are compensations of its disturbed or
+changed functional state. We are speaking of facts here, of very strange
+ones indeed. But I feel unable to formulate a real proof against all
+sorts of mechanism out of these facts: there *might* be a machine, to
+which all is due in a pre-established way. Of course we should hardly
+regard such a machine as very probable, after we have seen that it
+*cannot* exist in other fields of morphogenesis. But we are searching
+for a new and independent proof; and that is indeed not to be found
+here.[88]
+
+[88] The “secondary adaptations” observed by Vöchting are too
+complicated and too much mingled with restitutions to allow any definite
+analysis of the fact of the “secondary adaptation” as such.
+
+At present it must be taken as one of the fundamental *facts* of the
+organogenetic harmony, that the cells of functioning tissues do possess
+the faculty of reacting to factors which have changed the state of
+functioning, in a way which normalises this state histologically. And
+it is a fact also that even cells, which are not yet functioning but
+are in the so-called embryonic or indifferent condition contributing to
+the physiological completion of the tissue, react to factors embracing
+new functional conditions of the whole in a manner which leads to an
+adaptation of that whole to those conditions.
+
+This is a very important point in almost all morphological adaptation,
+whether corresponding to functional changes from without or resulting
+from the very nature of functioning. In fact, such cells as have already
+finished their histogenesis are, as a rule, only capable of changing
+their size adaptively, but are not able to divide into daughter-cells
+or to change their histological qualities fundamentally; in technical
+terms, they can only assist “hypertrophy” but not “hyperplasia.” Any
+adaptive change of a tissue therefore, that implies an increase in the
+number of cellular elements or a real process of histogenesis, has to
+start from “indifferent” cells, that is to say, cells that are *not yet*
+functioning in the form that is typical of the tissue in question; and,
+strange to say, these “embryonic” cells--*i.e.* the “cambium” in higher
+plants and many kinds of cells in animals--*can* do what the functional
+state requires. It is to be hoped that future investigations will lay a
+greater stress upon this very important feature of all adaptation.
+
+
+2. PHYSIOLOGICAL ADAPTATION[89]
+
+[89] General literature: Fröhlich, *Das natürliche
+Zweckmüssigkeitsprincip in seiner Bedeutung für Krankheit und Heilung*,
+1894. Driesch, *Die organischen Regulationen*, 1901. A. Tschermak, “Das
+Anpassungsproblem in der Physiologie der Gegenwart,” in a collection
+of papers in honour of J. P. Pawlow, St. Petersburg, 1904. Bieganski,
+“Ueber die Zweckmässigkeit in den pathologischen Erscheinungen,” *Annal.
+d. Naturphil.* 5, 1906. Among the general text-books of physiology those
+by Pfeffer (*Pflanzenphysiologie*, 1897-1904) and von Bunge (*Lehrbuch
+d. Phys. d. Menschen*, 1901) are the fullest on the subject of
+“regulations.” See also different papers on general pathology by Ribbert.
+
+It is but a step from morphological adaptations to adaptations in
+physiology proper. The only difference between regulations of the
+first type and those which occur in mere functioning is, that the
+resulting products of the regulation are of definite shape and therefore
+distinctly visible in the first case, while they are not distinctly
+visible as formed materials but are merely marked by changes in chemical
+or physical composition in the latter.
+
+Metabolism, it must never be forgotten, is the general scheme within
+which all the processes of life in a given living organism go on; but
+metabolism means nothing else, at least if we use the word in its
+descriptive and unpretentious meaning, than change in the physical
+or chemical characteristics of the single constituents of that
+organism. In saying this, we affirm nothing about the physical or
+chemical nature of the actual processes leading to those physical or
+chemical characteristics, and by no means are these “processes” *a
+priori* regarded as being physical or chemical *themselves*: indeed,
+we have learned that in one large field, in the differentiation of
+our harmonious systems they certainly are not. Now, if the metabolism
+does not end in any change of visible form, then true physiological
+processes, or more particularly physiological regulations, are going on
+before us. But we are dealing with morphogenetic events or regulations,
+if the result of metabolism is marked by any change in the constituents
+of form. This however may depend on rather secondary differences as to
+the nature of regulation itself, and any kind of metabolism may really
+be of the regulatory type, whether we actually see its result as a
+constituent of form, *e.g.* owing to the production of some insoluble
+compound, or whether we do not.
+
+I do not mean to say that these are the only differences between mere
+physiological activities or regulations and organogenesis proper, as an
+originating of typical form-combination; but if we regard, as we do in
+this chapter, the given organisation of a living being as a substratum
+of its functional life, morphological and physiological adaptations are
+indeed of almost the same logical order.
+
+We had best therefore begin our discussions with a recapitulation of
+our problem. We are studying adaptations in functioning--that means we
+want to know how the organism behaves with regard to any change which
+may take place in its functional state. We apply the term regulation,
+or in particular adaptation, to any kind of reaction on the part of the
+organism which re-establishes the normal state of functioning, and we
+now want to learn to what degree such adaptations exist in the field of
+physiology.
+
+
+SPECIFIC ADAPTEDNESS *NOT* “ADAPTATION”
+
+It is important to keep well in mind our strictly formulated theme, as
+by doing so we shall be able to exclude at once from our materials a
+large group of phenomena which occasionally have been called regulations
+by physiological authors, but which, in fact, are not of the adaptation
+type and therefore cannot be said to afford those problems which
+possibly might have been expected. Typical peculiarities in functional
+life cannot be called “regulations” for this very reason. If, for
+instance, the organism selects specific amounts of specific kinds of
+organic food or of salts out of the combinations of salts or organic
+food normally offered to it in the medium, as indeed is most typically
+shown for instance by the roots of plants, there cannot be said to occur
+a “regulation” or “adaptation” with regard to the permeability of the
+cell, nor is it strictly a case of “regulation,” if so-called selective
+qualities are discovered in the processes of secretion, say of the
+epithelium of the kidney.
+
+All these facts are typical and specific peculiarities in functioning
+which are duly to be expected, where a very typical and specific
+organisation of the most elaborated kind exists. Indeed, after studying
+such an organisation we must not be astonished that functions in
+organisms follow lines which certainly they would not have taken without
+it. Take the fact which is quoted very often, that the migration of
+compounds or of ions in the organisms can happen quite contrary to all
+the laws of osmosis, from the less concentrated to the more concentrated
+side of a so-called “membrane.” There *is* no simple “membrane” in the
+organism, but a complicated organisation of an almost unknown character
+takes its place, and nothing, indeed, is against the assumption that
+this organisation may include factors which actually drive ions or
+compounds to the side of higher concentration, which indeed drive them
+by “doing work,” if we like to speak in terms of energy; and these
+factors included in organisation may very well be of a true physical or
+chemical nature.[90]
+
+[90] According to investigations of the last two years, the physics of
+colloids seems to play as important a part in physiology as osmosis
+does; we here meet “means” of functioning just as we have already had
+“means” of organogenesis.
+
+I lay great stress upon these statements, as I should like to be as
+careful as possible in the admission of anything like a “proof” of
+vitalism. It was want of scientific criticism and rigid logic that
+discredited the old vitalism; we must render our work as difficult as
+possible to ourselves, we must hold the so-called “machine theory” of
+life as long as possible, we must hold it until we are really forced to
+give it up.
+
+In a more general form we now can sum up our discussion by saying: There
+never are adaptations in physiology, requiring any special analysis,
+where there are only complications or even apparent deviations from the
+purely physico-chemical type of events which are, so to say, statical,
+*i.e.* fixed in quantity or quality, however peculiar or typically
+complicated they may be; all such peculiarities indeed, may properly
+be called “adapted,” that is to say, very well fitted to perform a
+specific part in the service of normal general functioning, and they
+are “adapted” to their part by virtue of a certain “adaptedness” of the
+organisation; but they are not “adaptations” in any sense of the word.
+
+
+PRIMARY AND SECONDARY ADAPTATIONS IN PHYSIOLOGY
+
+We approach the subject of true adaptations, that is, of adapting
+processes, as soon as any kind of variation in functioning occurs which
+corresponds to a variation of any factor of the medium in the widest
+sense. But even here our work is by no means done by simply showing
+such a correspondence of outer and inner variations. We know very well
+already, from our former studies, that now we are faced by a further
+problem, that we are faced by the question whether we have to deal with
+simple primary kinds of adaptations or with the far more important
+secondary ones.
+
+As the discrimination between primary and secondary regulations proves
+indeed to be of first-rate importance, you will allow me, I hope, to
+summarise our chief analytical statements regarding them in a most
+general form. We call primary regulatory any kind of morphogenetic or
+functional performance, which, by its very intimate nature, always
+serves to keep the whole of organisation or of functions in its normal
+state. We call secondary regulations all features in the whole of
+morphogenesis or of functioning which serve to re-establish the normal
+state after disturbances along lines which are outside the realm of
+so-called normality. This analytical discrimination will help us very
+much to a proper understanding of physiology. But before we turn to
+apply our definitions to actual facts, another preliminary problem has
+to be solved.
+
+
+ON CERTAIN PRE-REQUISITES OF ADAPTATIONS IN GENERAL
+
+We are thinking of the general and important question, what types of
+adaptations may be expected in the field of physiology and whether
+there may be certain classes of regulatory events which possibly might
+be expected to occur in the organism on *a priori* grounds, but which,
+nevertheless, are to be regarded as impossible after a more intimate
+analysis of its nature, even at the very beginning? Or, in other words,
+to what kinds of changes of the medium will an organism be found able or
+unable to adapt itself?
+
+We know that the *state of functioning* must be altered in order to call
+forth any sort of adaptation at all. Now, there can be no doubt that *a
+priori* it would seem to be very useful for the organism, if it never
+would let enter into its blood, lymph, etc., be it through the skin or
+through the intestine, any chemical compound that would prove to be
+a poison afterwards. In fact, a man, judging on the principle of the
+general usefulness of all the phenomena of the living, might suppose
+that there would exist a sort of adaptation against all poisons to the
+extent that they would never be allowed to enter the real interior of
+the body. We know that such reasoning would be incorrect. But we also
+can understand, I suppose, that an *a priori* analysis of a more careful
+kind would have reasoned differently. How could the functional state
+of the organism be changed, and how, therefore, could adaptation be
+called forth by any factor of the medium which had not yet entered the
+organism, but was only about to enter it? Not at all therefore is such
+a regulation to be expected as we have sketched; if there is to be any
+adaptation to poisons, it only can occur after the poison has really
+acted in some way, and in this case we shall indeed find regulations.
+
+You may perhaps regard this discussion as a little too academical
+and hair-splitting, but here again it was for the sake of ensuring a
+perfectly sound foundation of our chief principles that I undertook it.
+Very often, indeed, the question has been raised by the defenders of a
+mechanistic theory of life, Why then did the organisms not reject all
+poisons from the very beginning? We now may reply to that only--how
+*could* they do so? How could they “know” what is a poison and what is
+not, unless they had experienced it?--if we are allowed for a moment to
+use very anthropomorphistic language.
+
+We repeat, therefore, that the functional conditions of the organism
+must have been actually changed in order that an adaptation may occur.
+Nothing is more essential to a clear understanding of our problems than
+to keep fully in mind the exact sense of this definition.
+
+
+ON CERTAIN GROUPS OF PRIMARY PHYSIOLOGICAL ADAPTATIONS
+
+*General Remarks on Irritability.*--Turning now to more special groups
+of problems concerning physiological adaptations, let us begin with the
+primary class of them, and let us first say a few words on a subject
+which occasionally has been regarded as the basis of physiological
+regulation in general. I refer to a most important fact in the general
+physiology of irritability. Irritability of any kind is known to be
+re-established, after it has been disturbed by the process of reacting
+to the stimulus, and in certain cases, in which two different--or rather
+two opposite--kinds of reactions are possible on the same substratum,
+which increase with regard to one process whilst decreasing at the same
+time with regard to the other. The irritability of the muscle or of the
+leaves of *Mimosa* is a very good instance of the first case, whilst the
+second more complicated one cannot be illustrated better than by what
+all experience has taught us about the irritability of the retina. The
+retina is more irritable by green rays and less by red ones the more
+it has been stimulated by the latter, and more sensitive to light in
+general the more it has been exposed to darkness; and something very
+similar is true, for instance, as regards phototactic irritability in
+plants, all these phenomena being in relation to the so-called law of
+Weber.[91]
+
+[91] I only mention here that certain modern psychologists have assigned
+the true law of Weber to the sphere of judgment and not of sensation. If
+applied to objective reactions only, in their dependence on objective
+stimuli, it, of course, becomes less ambiguous, and may, in a certain
+sense, be said to measure “acclimatisation” with regard to the stimulus
+in question. The mathematical analogy of the law of Weber to the most
+fundamental law of chemical dynamics seems very important.
+
+As to “acclimatisation” in the more usual meaning of the word, with
+regard to a change of the general faculty of resisting certain agents
+of the medium, “immunity” proper is to form a special paragraph of what
+follows, and to “acclimatisation” towards different degrees of salinity
+(in algae or fishes) some special remarks will also be devoted on a
+proper occasion. There remains only “acclimatisation” to different
+temperatures; but on this topic not much more than the fact is known
+(see Davenport, *Arch. f. Entw. Mech.* 2, p. 227). “Acclimatisation”
+does not allow of a sharp general definition; it may be the result of
+very *different* kinds of adaptations in our sense of the word.
+
+It seems to me that there would be little difficulty in harmonising the
+phenomenon of the inversion of irritability with the so-called principle
+of the “action of masses” and with the laws of certain “reversible”
+processes well known in chemistry. As to the simple fact of the
+re-establishment of irritability after stimulation has occurred, or,
+in certain other cases, the fact that in spite of permanent stimulation
+irritability seems to exist permanently also, physical analogies or even
+explanations might very well be found.[92]
+
+[92] I should think that the problem of the re-establishment of
+irritability, in principle at least, arises even when there is not a
+trace of so-called “fatigue” or of a “refractory period.” The process
+of restoring may be so rapid as not to be noticeable, nevertheless some
+sort of restoring is to be postulated. We may say the “irritability” of
+an elastic ball is re-established by its elasticity. A certain analogy
+to this case may perhaps be found in the muscle. But the irritability
+of nerves with respect to nervous conduction, and of glands with
+respect to secretion, or of the articulations of *Mimosa* may be well
+understood, hypothetically at least, if we assume that the ordinary
+course of metabolic events is apt in itself to lead to a certain state
+or condition of the organs in question upon which their irritability
+is based. Certain general conditions of functioning, as for instance
+the presence of oxygen for the contraction of the muscle, would better
+be looked upon as necessary “means” of functioning than as being part
+of irritability as such. “Fatigue,” of course, may also be due to
+the absence of such “means” or to abnormal conditions originated by
+functioning itself.
+
+If now we ask whether there is anything like an adaptation appearing in
+the general characteristics of irritation and irritability, it seems to
+me that we may answer the question in an affirmative manner, as far as
+primary regulation comes into account. We, certainly, have not studied
+any abnormal regulatory lines of general functioning, we only have
+studied general functioning itself; but, indeed, there was a certain
+sort of regulation *in* functioning. Of course, by showing that one
+of the most general features of all functioning is primary-regulatory
+in itself, we do not deny the possibility of many specific functions
+in which real secondary regulations actually do exist. Nothing indeed
+is asserted about the *specific* character of functioning in its
+different types, by proving that one of the *general* features of *all*
+functioning may comparatively easily be understood. It seems to me that
+this important logical point has not always received the attention it
+deserved.
+
+*The Regulation of Heat Production.*[93]--Having finished our
+introductory remarks we now turn to the proper study of special
+physiological functioning with regard to its adaptive side, and begin
+with the most simple cases.
+
+[93] Rubner, *Die Gesetze des Energieverbrauches bei der Ernährung*,
+Leipzig u. Wein, 1902.
+
+The so-called “regulation of heat” in warm-blooded vertebrates is an
+instance of a special function which can be said to be regulatory in
+itself. There exists a normal blood heat for each species, which is
+maintained no matter whether the temperature of the medium rise or fall.
+It might seem at first as if in this case there were a little more
+of an adaptive regulation than only its well-known primary type; no
+reversion, one might say, of the direction of one and the same process
+occurs in the regulation of heat production, but one kind of process
+is called into action if it is necessary to raise the temperature, and
+another whenever it is necessary to lower it. Even in the dilatation
+and constriction of capillary vessels there are different nerves
+serving for each operation respectively, and far more important are the
+increasing of transpiration for cooling, the increasing of combustion
+for heating--two radically different processes. But, nevertheless, there
+is a certain unity in these processes, in so far as a specific locality
+of the brain has been proved to be the “centre” of them all; it is to
+this centre of course that the analysis of heat production considered as
+a kind of regulation or adaptation must be directed. Such an ultimate
+analysis, it seems to me, would have to classify heat regulation under
+the primary type of adaptations in physiology without any restriction.
+The centre acts in one sense or in the other, if stimulated by any
+temperature beyond a very limited range, and it is in the action of the
+centre that the “regulation” of heat consists.[94]
+
+[94] The phenomenon of fever we leave out of account here; it is
+regarded by some as regulation, by others as a disturbance of heat
+regulation. Of course, if the first view should ever prove to be the
+right one, fever might be classified among the real regulations of the
+secondary type.
+
+*Primary Regulations in the Transport of Materials and Certain Phenomena
+of Osmotic Pressure.*--Very similar phenomena of regulation are present
+in many processes concerned in the whole of metabolism. Let us consider
+for a moment the migration of materials in plants. Whenever any compound
+is used at a certain place, a permanent afflux of this compound to
+that place sets in from all possible directions. No doubt this is a
+“regulation,” but it is also the function itself, and besides that,
+a very simple function based almost entirely on well-known laws of
+physical chemistry. And in other cases, as in the ascent of water to
+the highest tops of our trees, which purely physical forces are said to
+be insufficient to explain, we can appeal to the unknown organisation
+of many cells, and there is nothing to prevent our attributing to these
+cells certain functions which are, if you like to say so, regulatory
+in themselves. Among other facts of so-called regulations there is the
+stopping of metabolic processes by an accumulation of their products:
+as, for instance, the transformation of starch into sugar is stopped,
+if the sugar is not carried away. Of course that is a regulation, but
+it again is an intrinsic one, and it is one of the characteristics of
+reversible chemical processes to be stopped in that way. I know very
+well that in this particular case a certain complication is added by
+the fact that it is a so-called ferment, the diastase, which promotes
+the transformation of starch into cane-sugar, and that this ferment is
+actively produced by the organism: but even its production would not
+prove that any real kind of secondary regulation exists here, if nothing
+more were known about such an active production than this single case.
+
+In a special series of experiments almost all carried out in Wilhelm
+Pfeffer’s botanical laboratory at Leipzig, an attempt has been made
+to discover in what manner the cells of plants are able to withstand
+very high abnormalities of the osmotic pressure of the medium--that is
+to say, very great changes in the amount of its salinity. That many,
+particularly the lower plants, are able to stand such changes had been
+ascertained already by the careful examinations of Eschenhagen; but
+recent years have given us a more profound insight into what happens.
+Von Mayenburg[95] has found that sundry of the species of *Aspergillus*,
+the common mould, are able to live in very highly concentrated solutions
+of several salts (KNO_3 and Na_2SO_4). They were found to regulate
+their osmotic pressure not by taking in the salts themselves, but by
+raising the osmotic pressure of their own cell sap, producing a certain
+amount of osmotically active substances, probably carbohydrates. If
+in this case it were possible to assume that the osmotic pressure of
+the medium were the real stimulus for the production of the osmotic
+substances in the cell, stimulus and production both corresponding
+in their degree, we should be entitled to speak of a primary though
+physiological[96] regulation only; and it seems to me that despite the
+discoveries of Nathansohn that certain algae and cells of higher plants
+are able to change the permeability of their surfaces in a way which
+regulates the distribution of single salts or ions in the sap of their
+cells without any regard to pure osmotic equilibrium, such a simple
+explanation might be possible.[97]
+
+[95] *Jahrb. wiss. Bot.* 36, 1901.
+
+[96] Carbohydrates cannot be ionised, and therefore there is no doubt
+that in von Mayenburg’s experiments the organism itself is actively
+at work. As to compounds liable to ionisation, it has been noticed by
+Maillard that a certain regulatory character is contained simply in the
+physical fact that the degree of ionisation changes with concentration:
+decrease of concentration for instance would be followed by an increase
+of ionisation, and so the osmotic pressure may be preserved (*C. rend.
+Soc. Biol.* 53, 1901, p. 880).
+
+[97] In the different experiments of Nathansohn (*Jahrb. wiss. Bot.*
+38, 1902, and 39, 1903) the salinity of the medium was changed in such
+a way that there was in each case either an abnormal increase or an
+abnormal decrease in the concentration of one single ion necessary
+for metabolism. The cell was found to stand these abnormal changes in
+such a way that in the case of the increase of the concentration of
+the medium it did not allow more than a certain amount of the ion in
+question to come in, and that in the case of the decrease it did not
+allow more than a certain quantity of the ion to go out. It thus seems
+as if the permeability of the surface were adjusted to a certain minimum
+and to a certain maximum of every single ion or salt, the permeability
+being stopped from within to without, whenever the minimum, and from
+without to within, whenever the maximum is reached in the cell sap; both
+irrespective of proper physical osmotic equilibrium (“Physiologisches
+Gleichgewicht”). Thus, in fact, there only would be a case of primary
+regulation, nothing more. It would all appear rather similar to what
+occurs in the kidney. Of course we do not assert that our explanation is
+right, but it is possible and is at the same time the most simple, and
+it is our general practice always to prefer the most simple hypotheses.
+
+There are many regulation phenomena connected with osmotic pressure
+and permeability in animal physiology also, though at present they are
+not worked out as fully as possible. The works of Frédéricq, J. Loeb,
+Overton and Sumner[98] would have to be taken into account by any
+one who wished to enter more deeply into these problems. We can only
+mention here that permeability to water itself also plays its part, and
+that, according to Overton’s experiments, it is a kind of solubility
+of the media in the very substance of the cell surface on which all
+permeability and its regulation depend.
+
+[98] Many fishes are able to withstand great changes in the osmotic
+pressure of sea-water; the osmotic pressure of their body fluids, though
+never in a real physical equilibrium with the pressure of the medium,
+nevertheless may vary whenever the abnormal conditions of the latter
+exceed certain limits.
+
+*Chromatic Regulations in Algae.*--The phenomena of osmotic pressure and
+its regulation may be said to be the preliminaries of metabolism proper,
+conditions necessary for it to take place. Now there is another branch
+of such preliminaries to metabolism, in which the most interesting
+regulation phenomena have been lately discovered. It is well known that
+what is called assimilation in plants, that is, the formation of organic
+compounds out of carbon dioxide (CO_2) and water, occurs only in
+the light by means of certain pigments. This pigment is in all higher
+plants and in many others the green chlorophyll, but it may be different
+in certain species of algae, and can generally be said[99] to be of
+the colour complementary to the colour of those rays which especially
+are to be absorbed and to be used for assimilation. But here we have
+“adaptedness,” not adaptation. It was in some species of primitive
+algae, the *Oscillariae*, that Gaidukow[100] found a very interesting
+instance of an active regulation in the formation of pigments. These
+algae always assume a colour which corresponds to the accidental colour
+of the rays of the medium and is complementary to it; they become green
+in red light, yellow in blue light, and so on--that is, they always
+actively take that sort of colouring which is the most suitable to
+the actual case.[101] There indeed occurs a sort of complementary
+photography in these algae; but, though adaptive, it could hardly be
+said to exceed the limits of “primary phenomena.”
+
+[99] See Stahl, *Naturw. Wochenschrift*, N. F. 5, 1906, No. 19.
+
+[100] *Arch. Anat. Phys.*, Phys. Abt. Suppl., 1902.
+
+[101] The adaptive phenomena discovered by Gaidukow depend upon a real
+alteration in the formation of pigments. In the (primary) chromatic
+adaptation of pupae of Lepidoptera with respect to the colour of
+the ground they live upon, we only have the variable effects of
+pre-established chromatophores (Poulton, *Phil. Trans. London*, 178 B,
+1888; Merrifield, *Trans. Ent. Soc. London*, 1898). The same holds for
+chromatic adaptations in crabs (Gamble and Keeble, *Quart. Journ. Micr.
+Sci.* 43, 1900; Minkiewicz, *Arch. Zool. exp. et gén.* sér. 4, 7, notes,
+1907).
+
+*Metabolic Regulations.*--And now we enter the field of regulations in
+metabolism itself. There are two kinds of outside factors of fundamental
+importance for all metabolic processes: food is one, and oxygen is the
+other. And metabolism as a whole is of two different aspects also:
+it both serves for assimilation proper--that is, building up--and it
+supplies the energy for driving the functional machine. It is clear
+that food alone--together of course with the assimilating means of the
+organism, can account for the first type of metabolism, while both food
+and oxygen, or some sort of substitute for the latter, as in certain
+bacteria, supply functional energy. Of course we are not entitled to say
+that the importance of so-called oxidation or respiration is exhausted
+by its energetic rôle: it certainly is not, for if it were, the organism
+would only be stopped in its functions if deprived of oxygen but
+would not die. It seems that certain substances always arise in the
+metabolism, in the processes of decomposition, which have to be burnt up
+in order not to become poisonous. But we shall return to the phenomena
+of organic oxidation in another chapter of the book, and shall deal with
+them from a more general point of view.[102]
+
+[102] The theory of oxidation we have shortly sketched here was
+developed in chapter B. 5, of my *Organische Regulationen*. Recent
+discoveries of Winterstein’s (*Zeitschr. allg. Physiol.* 6, 1907)
+have given the strongest support to my hypothetic statements, and, in
+fact, can be said to have brought the doctrine of organic oxidation
+to a critical point. There can be no doubt that oxygen not only plays
+the “antipoisonous” rôle I had assigned to it, but that it is not
+even of such great importance for the supply of functional energy as
+former times had assumed. No doubt it serves to drive the functional
+machine, but decomposition of certain chemical constituents of the
+organism serves this purpose even more. The latter does so in the most
+fundamental and original manner, so to speak, whilst oxidation only
+burns up its products. Almost all elemental functions, in nerve-tissue
+at least, go on very well in the absence of oxygen, provided that
+certain “poisonous” substances, resulting from this anaërobic
+metabolism, are constantly removed. In normal conditions that is
+done by oxygen, and in doing so oxygen certainly assists the supply
+of energy, but it does not furnish the whole of it. The difference
+between so-called “aërobic” and “anaërobic” life almost completely
+disappears under such a view, and many so-called “regulations,” of
+course, disappear at the same time; there is no more “intramolecular
+respiration.”
+
+Let us now try to take a short survey of all the regulations discovered
+relating to the substitution of one kind of food for another. We have
+said that food serves in the first place as building material, in the
+second place as fuel. It only deserves brief mention that, as all recent
+investigations have shown, fats, carbohydrates, and albumen are equally
+well able to serve as fuel.[103]
+
+[103] But nevertheless albumen is not to be replaced altogether in
+vertebrates by fat or carbohydrate; it probably serves some special
+function besides combustion, even in the adult.
+
+It is in the state of fasting, *i.e.* in the case of a real absence of
+*all* nourishing materials, that the organism has proved to be capable
+of regulations of the most marked nature, with regard to the combustion
+of its own materials. Respiration, we know, must go on if death is to
+be avoided, and now indeed it has been found that this process attacks
+the different tissues of the organism subjected to fasting in such an
+order that, after the combustion of the reserves, the most unimportant
+tissues with regard to life in general are destroyed first, the most
+important ones last. Thus in vertebrates the nerve cells and the heart
+are preserved as long as possible; in infusoria it is the nucleus; in
+flatworms, as the very careful studies of E. Schultz[104] have lately
+shown, it is the nerve cells and the sexual cells which longest resist
+destruction, whilst almost all the rest of the organisation of these
+animals may disappear. I should not say that we can do very much with
+these facts at present in our theoretical discussion, but they are
+certainly witness of very astonishing adaptive powers.[105]
+
+[104] *Arch. Entw. Mech.* 18, 1904.
+
+[105] To a physiological friend of mine I owe the suggestion that it is
+the permanently functioning tissues which stand hunger better than the
+others, at least if the sexual cells might be regarded as capable of
+a *sécrétion interne* in all cases. Then the adaptations in the state
+of hunger might be said to be reduced in some degree to “functional
+adaptation.” But it must remain an open question, it seems to me,
+whether such a view may indeed hold in the face of the facts observed in
+*Planaria* and infusorians.
+
+We now turn to study the cases of a compensation of nourishments
+serving for the real building up of the organism. Albumen, we know, is
+absolutely indispensable for animals, even for adults, though nothing is
+known about the purpose it serves in the latter; its place can be taken
+of course by those less complicated compounds which result from its
+first decomposition, effected by pepsin and trypsin, but nothing else
+will do. The salts of sea-water, according to Herbst’s experiments, may
+only vary to a very small degree if the development of marine animals
+is to go on well; potassium may be replaced by caesium or rubidium,
+and that is all. Much the same is true of the salts necessary to
+plants. It will not surprise us very much to hear that algae can also
+be successfully fed with the potassium salts of organic compounds, and
+higher plants with acid amides or glucoses instead of carbonic acid, as
+those products are normal steps in their assimilation; and it may also
+be fairly easily understood that nitrogen can be offered in organic form
+instead of as a nitrate.
+
+It was in the group of fungi that really important adaptations with
+regard to the proper form-producing alimentation were first discovered,
+and these are of a very complicated kind indeed. Fungi are known to
+be satisfied with one single organic compound instead of the group of
+three--fat, carbohydrate and albumen--necessary for animals. Now Pfeffer
+showed that the most different and indeed very abnormal compounds were
+able to bring his subjects to a perfect growth and morphogenesis; and,
+moreover, he found that, if several kinds of such food were offered
+together, they were consumed quite indifferently as to their chemical
+constitution, but only with regard to their nutritive value: that sort
+of food which had produced a better growth than another when both
+were offered separately was found to save the latter from consumption
+whenever both were offered together.
+
+Here we are faced by one of the most typical cases of regulations in
+metabolic physiology: the organism is able to decompose compounds of
+the most different constitution, which have never been offered to it
+before; but nevertheless, it must remain an open question whether real
+“secondary” regulation has occurred, as nothing is known in detail about
+the single steps of metabolism in these fungi. There *might* be some
+ferments equally able to destroy different classes of compounds,[106]
+and that the most nutritive compound is used up first *may* be a
+question of physico-chemical equilibrium.
+
+[106] In all cases where fungi of the same species are able to live on
+different hosts, that is, to penetrate membranes of a different chemical
+character, a similar objection as to the “secondary” type of such a
+regulation may be made.
+
+That is almost all[107] that is actually known of adaptation with regard
+to the use of an abnormal food supply. Though important, it cannot be
+said to be very much. But could we expect very numerous regulations
+here at all after what we laid down in a former paragraph about the
+possibilities of adaptive regulation in general? The functional state
+must have been altered in order that such regulations may occur. Now
+there is no doubt that this state may be really altered only if an
+abnormal food has first been taken in altogether by the cell-protoplasm
+of the body-surfaces, but never if it has only entered the cavity of the
+intestine, which, strictly speaking, is a part of the exterior medium.
+Fungi indeed not only take in the abnormal food, but also know what
+to do with it, but all animals are obliged to treat first with their
+chemical secretions what happens to be present in their intestine, in
+order that it may be taken up by their living cells, and one hardly
+can wonder that these secretions are only formed in correspondence to
+a limited number of outside stimuli. In fact, as soon as we look upon
+what adaptive or regulatory work happens in metabolism *inside* the body
+interior, we meet, even in animals, regulations of a far more developed
+type.
+
+[107] The discovery of Weinland that adult dogs are able to produce
+“lactase” in their pancreas, whenever they are fed, quite abnormally,
+with milk-sugar, has recently been said to be vitiated by an analytical
+mistake.
+
+Discoveries of the last few years have taught us that almost all
+metabolic processes in the organism, including oxidation, are carried
+out by the aid of special materials, the so-called enzymes or
+ferments. These are known to exist in the most different forms even in
+the inorganic world. They are simply chemical compounds, of specific
+types, that bring about chemical reactions between two other chemical
+materials, which in their absence would either not go on at all or would
+go on very slowly. We cannot enter here into the much disputed chemical
+theory of what is called “catalysis”: we can only say that there is no
+objection to our regarding almost all metabolic processes inside the
+organism as due to the intervention of ferments or catalytic materials,
+and that the only difference between inorganic and organic ferments is
+the very complicated character of the latter and the very high degree of
+their specification.
+
+Such a statement, of course, does not say that all metabolism has proved
+to be of a chemical nature: the *action* of the ferment when produced
+is chemical, but we do not know at all *how* the ferment is produced;
+we only know that a high degree of active regulation is shown in this
+production. In fact, it has been proved in some cases, and probably will
+be proved in a great many more in the near future, that all metabolic
+ferments, whether they promote oxidation or assimilation proper or
+chemical decomposition, are produced in a regulatory manner with regard
+to the specific compound to be dissociated or to be built up. In this
+way the whole field of metabolism is really covered by “regulations.”
+Are they real “secondary” ones? Of course the regulatory correspondence
+applies to the process of *secretion* in the *first* place, not to the
+actual formation of the ferment inside the cell. The correspondence as
+to secretion, no doubt, is of the primary type; is there any secondary
+regulation with regard to the real *production* of the ferment? I am
+sorry that I cannot answer this question affirmatively. Nothing is
+*known* at present, even here, that really proves the existence of
+adaptation of the secondary type: there *might* be a sort of statical
+“harmony” at the base of it all, established before all functioning
+*for* functioning.[108]
+
+[108] Compare the excellent review of the subject by Bayliss and
+Starling in the *Ergebnisse der Physiologie*, 5, 1906, p. 664. The
+reader who misses here an analysis of the brilliant discoveries
+of Pawlow and his followers, relating to so-called “psychical and
+associative secretion,” will find these facts dealt with in another
+section of the book. These facts, indeed, would prove vitalism, it seems
+to me.
+
+The only facts of secondary metabolic regulations which are known at
+present have been found in combination with phenomena of restitution
+after real disturbances of organisation, where, indeed, numbers and
+numbers of regulatory changes of metabolism, both in animals and plants,
+have also been recorded. But there is not one case of a secondary
+regulation really known to affect pure metabolism alone.[109] This is a
+new indicium of the primacy of *form* in the organism.
+
+[109] It would be a true secondary metabolic regulation, if after the
+extirpation of one gland another different one were to assume its
+function. Nothing is known in this respect except a few rather doubtful
+observations about the interchange of functions between thymus and
+thyroid, except also the fact that the so-called lymph-glands increase
+in size after the extirpation of the spleen. Even here, of course, a
+sort of “restitution” would be included in adaptation proper.
+
+
+IMMUNITY THE ONLY TYPE OF A SECONDARY PHYSIOLOGICAL ADAPTATION
+
+There is only one class of physiological processes in which the type
+of the real secondary regulation occurs. The discoveries of the last
+twenty years have proved beyond all doubt, and future discoveries will
+probably prove even more conclusively, that the so-called *immunity*
+against diseases is but one case out of numerous biological phenomena
+in which there is an adaptive correspondence between abnormal chemical
+stimuli and active chemical reactions on the part of the organism and in
+its interior, exceeding by far everything that was formerly supposed to
+be possible in organic regulation.
+
+The adaptive faculty of the organism against inorganic poisonous
+substances[110] is but small comparatively, and is almost always due not
+to a real process of active regulation but to the action of substances
+pre-existing in the organism--that is, to a sort of adaptiveness but
+not adaptation. Metallic poisons, for instance, may be transformed into
+harmless compounds by being combined with albumen or sulphuric acid
+and thus becoming insoluble, or free acids may be neutralised, and so
+on; but all these processes go on to a certain extent only, and, as
+was mentioned already, are almost always the result of reactions with
+pre-existing materials. Only in a few cases is there any sort of true
+adaptation to metallic substances, such as sublimate and, in a very
+small degree, arsenic, comparable in some respects with the adaptation
+to abnormally high temperatures. The organism which has been accustomed
+to receive at first very small amounts, say, of sublimate, and then
+receives greater and greater amounts of this substance by degrees, will
+at the end of this treatment be able to stand a quantity of the poison
+that would have been instantly fatal if administered at the first
+dose.[111] But the explanation of this adaptation is not known in any
+case; there seems to be some similarity between it and the so-called
+histogenetic immunity against organic poisons.
+
+[110] A good review is given by E. Fromm, *Die chemischen Schutzmittel
+des Tierkörpers bei Vergiftungen*, Strassburg, 1903.
+
+[111] Davenport, *Arch. Entw. Mech.* 2, 1895-1896, and Hausmann,
+*Pflüger’s Arch.* 113, 1906.
+
+It is in the fight against animal and vegetable poisons, such as those
+produced by bacteria, by some plants and by poisonous snakes, that the
+true adaptation of the organism reaches its most astonishing degree.
+The production of so-called “anti-bodies” in the body fluids is not the
+only means applied against noxious chemical substances of this kind: the
+existence of so-called histogenetic immunity is beyond all doubt, and
+Metschnikoff[112] certainly was also right in stating that the cells
+of the organism themselves repel the attack of living bacteria. Cells
+of the connective tissue and the white blood cells, being attracted by
+them as well as by many other foreign bodies, take them in and kill
+them. This process, called “phagocytosis” is of special frequency among
+lower animals, but it also contributes to what is called inflammation
+in higher ones.[113] And there are still other kinds of defence against
+parasites, as for instance the horny or calcareous membranes, employed
+to isolate trichinae and some kinds of bacteria. But all this is of
+almost secondary importance as compared with the adaptive faculties of
+the warm-blooded vertebrates, which produce anti-poisonous substances in
+their lymph and blood.
+
+[112] *Leçons sur la pathologie comparée de l’inflammation*, Paris, 1902.
+
+[113] The other steps or phases in the process of inflammation have also
+been regarded as adaptive: the increased quantity of body fluid for
+instance is said to serve to dilute poisonous substances.
+
+It is impossible to say here[114] more than a few words about the
+phenomena and the theory of immunity proper, which have attained the
+dimensions of a separate science. Let me only mark those general points
+which are of the greatest theoretical interest. Discoveries of the most
+recent years have shown not only that against the “toxins” of bacteria,
+snakes, and some plants, the organism is able actively to produce
+so-called “anti-toxins”--that is, soluble substances which react with
+the toxins and destroy their poisonous character--whenever required,
+but that against any foreign body of the albumen group a specific
+reaction may occur, resulting in the coagulation of that body. But the
+destruction of the noxious substance or foreign albumen actually present
+is not all that is accomplished by the organism. “Acquired immunity”
+proper, that is, security against the noxious material for a more or
+less extensive period of the *future*, depends on something more. Not
+only is there produced as much of the so-called “anti-body” as is
+necessary to combine with the noxious, or at least foreign substances
+which are present, but *more* is produced than is necessary in the
+actual case. On this over-production depends all active immunity,
+whether natural or, as in some kinds of vaccination, artificial; and
+so-called “passive” immunity, obtained by the transfusion of the serum
+of an actively immune organism into another also depends upon this
+feature.[115]
+
+[114] See Jacoby, *Immunität und Disposition*, Wiesbaden, 1906.
+
+[115] *Collected Studies on Immunity by Ehrlich and his Collaborators*,
+translated by Ch. Bolduan, New York and London, 1906.
+
+This phenomenon in particular--the production of *more* of the
+antitoxin or the “precipitin” than is actually necessary--seems to
+render almost impossible any merely chemical theory of these facts. The
+reaction between toxin and antitoxin, albumen and precipitin is indeed
+chemical; it may in fact be carried out in a test-tube; but whether the
+production of the anti-body itself is also chemical or not could hardly
+be ascertained without a careful and unbiassed analysis. There can be
+no doubt that the well-known theory of Ehrlich,[116] the so-called
+theory of side-chains (“Seitenkettentheorie”) has given a great impulse
+to the progress of science; but even this theory, irrespective of its
+admissibility in general, is not a real chemical one: the concept of a
+regeneration of its so-called haptophore groups is a strictly biological
+concept.[117]
+
+[116] So-called genuine or innate immunity, in contrast to the immunity
+which is acquired, is of course a case of adaptedness only and not of
+adaptation. There also exists a high degree of specific adaptedness in
+some animals with regard to their faculty of coagulating blood. (See Leo
+Loeb, *Biol. Bull.* 9, 1905.)
+
+[117] We cannot do more than barely mention here the problem of the
+localisation of anti-body production. In general it seems to be true
+that anti-bodies are produced by those cells which require to be
+protected against toxins; that would agree with the general rule, that
+all compensation of the change of any functional state proceeds from the
+part changed in its function.
+
+And, indeed, here if anywhere we have the biological phenomenon of
+adaptation in its clearest form. There are very abnormal changes of the
+functional state of the organism, and the organism is able to compensate
+these changes in their minutest detail in almost any case. The problem
+of the specification of the reactions leading to immunity seems to me,
+as far as I can judge as an outsider, to stand at present in the very
+forefront of the science. There cannot be the slightest doubt that
+especially against all sorts of foreign albumens the reaction is as
+strictly specific as possible; but there are some typical cases of
+specificity in the production of antitoxins also. It is, of course,
+the *fact* of specific correspondence between stimulus and reaction,
+that gives to immunity its central position among all adaptations,
+no matter whether the old hypothesis of the production of specific
+anti-bodies proves tenable, or whether, as has been urged more recently
+by some authors, the anti-body is always the same but reacts differently
+according to the medium. In the latter case it would be the medium that
+is regulated in some way by the organism in order to attain a specific
+adaptedness.
+
+
+NO GENERAL POSITIVE RESULT FROM THIS CHAPTER
+
+But now let us look back to the sum of all the physiological reactions
+studied, and let us see if we have gained a new proof of the autonomy of
+life from our long chapter.
+
+We freely admit we have not gained any really new *proof*, but we may
+claim, I think, to have gained many indicia for the statement that
+the organism is not of the type of a machine, in which every single
+regulation is to be regarded as properly prepared and outlined.
+
+It is precisely in the field of immunity that such a machine-like
+preparation of the adaptive effects seems almost impossible to be
+imagined. How indeed could there be a machine, the chemical constituents
+of which were such as to correspond adaptively to almost every
+requirement?--to say nothing of the fact that the production of *more*
+of the protecting substance than is actually necessary could hardly be
+said to be “chemical.”
+
+In fact, we are well entitled to say that we have reached here the very
+heart of life and of biology. If nevertheless we do not call the sum of
+our facts a real proof of vitalism, it is only because we feel unable
+to formulate the analysis of what happens in such a manner as to make
+a machine as the basis of all reactions absolutely unimaginable and
+unthinkable. There *might* be a true machine in the organism producing
+immunity with all its adaptations. We cannot disprove such a doctrine by
+demonstrating that it would lead to a real *absurdity*, as we did in our
+analysis of differentiation of form; there is only a very high degree of
+improbability in our present case. But an indirect *proof* must reduce
+to *absurdity* all the possibilities except one, in order to be a proof.
+
+Mechanistic explanations in all branches of functional physiology
+proper, so much in vogue twenty years ago, can indeed be said to
+have failed all along the line: the only advantage they have brought
+to science is the clearer statement of problems to which we are now
+accustomed. But we are not fully entitled to say[118] that there never
+will be any mechanistic explanation of physiological functions in the
+future. It may seem as improbable as anything can be; but we wish to
+know not what is improbable but what is not possible.
+
+[118] Here again I should like to except from this statement the
+discoveries of Pawlow. See page 204, note 1.
+
+Now of course you might answer me that after we have indeed
+shown that the production of form, as occurring on the basis of
+harmonious-equipotential systems, is a fact that proves vitalism,
+the acts taking place on the basis of that form after its production
+would have been proved to be vitalistic also, or at least to be in
+some connection with vitalistic phenomena. Certainly they would, and
+I myself personally should not hesitate to say so. But that is not
+the question. We have to ask: Is any new proof, *independent of every
+other*, to be obtained from the facts of physiological adaptation in
+themselves? And there is really none. Mere regulatory correspondence
+between stimuli and reactions, even if it be of the adaptive type and
+occur in almost indefinite forms, never really disproves a machine as
+its basis so long as the stimuli and reactions are *simple* and uniform.
+Next summer, however, we shall see that vitalism may be proved by such a
+correspondence if the two corresponding factors are not simple and not
+uniform.
+
+We most clearly see at this point what it really was in our analysis of
+differentiation that allowed us to extract a real proof of vitalism from
+it. Not the mere fact of regulability, but certain specific relations
+of space, of locality, lay at the very foundation of our proof. These
+relations, indeed, and only these relations, made it possible to
+reduce *ad absurdum* any possible existence of a machine as the actual
+basis of what we had studied. In our next chapter again it will be
+space-relations, though analysed in a different manner, that will enable
+us to add a second real proof of vitalism to our first one.
+
+With this chapter we conclude the study of organic regulation in all its
+forms, as far as morphogenesis and metabolism are in question.
+
+But our analysis of these regulations would be incomplete and indeed
+would be open to objections, if we did not devote at least a few words
+to two merely negative topics, which will be taken more fully into
+consideration later on.
+
+
+A FEW REMARKS ON THE LIMITS OF REGULABILITY
+
+There has never been found any sort of “experience” in regulations
+about morphogenesis or in adaptations of the proper physiological
+type. Nothing goes on “better” the second time than it did the first
+time;[119] everything is either complete, whenever it occurs, or it does
+not occur at all.
+
+[119] The few cases of an “improvement” of morphogenetic acts in
+hydroids described by myself are too isolated at present to be more
+than mere problems (*Arch. Entw. Mech.* 5, 1897). The same is true, it
+seems to me, with regard to certain recent discoveries made by R. Pearl
+on *Ceratophyllum* (*Carnegie Inst. Wash. Publ.* No. 58, 1907); and by
+Zeleny on a medusa (*Journ. exp. Zool.* 5, 1907). Pawlow’s discovery,
+that the enzymotic composition of the pancreatic fluid in dogs becomes
+more and more adapted to a specific composition of the food (either meat
+or bread and milk) the longer such a specific composition is offered
+to the individual animal, may probably be understood as a case of mere
+functional adaptation of the cells of the digestive glands, if it stands
+criticism at all (see Bayliss and Starling, *Ergeb. Physiol.* 5, 1906,
+p. 682).
+
+That is the first of our important negative statements about
+regulations; the second relates to the phrase just used, “or it does
+not occur at all.” There are indeed limits of regulability; adaptations
+are not possible to every sort of change of the physiological state:
+sickness and death could not exist if they were; nor is restitution
+possible in all cases where it might be useful. It is a well-known fact,
+that man is only able to heal wounds but is altogether destitute of the
+faculty of regeneration proper. But even lower animals may be without
+this faculty, as are the ctenophores and the nematodes for instance, and
+there is no sort of correspondence between the faculty of restitution
+and the place in the animal kingdom. It is not altogether impossible
+that there may be found, some day, certain conditions under which every
+organism is capable of restoring any missing part; but at present we
+know absolutely nothing about such conditions.[120]
+
+[120] Experiments carried out in the “Biologische Versuchsanstalt” at
+Vienna indeed have shown that many animal types are capable of at least
+a certain degree of restitution, although they had previously been
+denied this faculty by zoologists.
+
+But no amount of negative instances can disprove an existing
+positive--which is what we have been studying. Our analysis based upon
+the existence of regulations is as little disparaged by cases where no
+regulability exists as optical studies are by the fact that they cannot
+be undertaken in absolute darkness.
+
+
+
+
+*D.* INHERITANCE: SECOND PROOF OF THE AUTONOMY OF LIFE
+
+
+All organisms are endowed with the faculty of re-creating their own
+initial form of existence.
+
+In words similar to these Alexander Goette, it seems to me, has given
+the shortest and the best expression of the fact of inheritance. Indeed,
+if the initial form in all its essentials is re-created, it follows from
+the principle of univocality, that, *ceteris paribus*, it will behave
+again as it did when last it existed.
+
+By the fact of inheritance life becomes a rhythmic phenomenon, that is
+to say, a phenomenon, or better, a chain of phenomena, whose single
+links reappear at constant intervals, if the outer conditions are not
+changed.
+
+
+THE MATERIAL CONTINUITY IN INHERITANCE
+
+It was first stated by Gustav Jaeger and afterwards worked out into
+a regular theory by Weismann, that there is a continuity of material
+underlying inheritance. Taken in its literal meaning this statement is
+obviously self-evident, though none the less important on that account.
+For as all life is manifested on bodies, that is on matter, and as the
+development of all offspring starts from parts of the parent bodies,
+that is from the matter or material of the parents, it follows that in
+some sense there is a sort of continuity of material as long as there is
+life--at least in the forms we know of. The theory of the continuity of
+“germ-plasm” therefore would be true, even if germ-cells were produced
+by any and every part of the organism. That, as we know, is not actually
+the case: germ-cells, at least in the higher animals and in plants, are
+produced at certain specific localities of the organism only, and it is
+with regard to this fact that the so-called theory of the “continuity of
+germ-plasm” acquires its narrower and proper sense. There are distinct
+and specific lines of cell-lineage in ontogenesis, so the theory states,
+along which the continuity of germ-protoplasm is kept up, which, in
+other words, lead from one egg to the other, whilst almost all other
+lines of cell-lineage end in “somatic” cells, which are doomed to
+death. What has been stated here is a fact in many cases of descriptive
+embryology, though it can hardly be said to be more than that. We know
+already, from our analytical and experimental study of morphogenesis,
+that Weismann himself had to add a number of subsidiary hypotheses to
+his original theory to account for the mere facts of regeneration proper
+and the so-called vegetative reproduction in plants and in some animals,
+and we have learned that newly discovered facts necessitate still more
+appendixes to the original theory. In spite of that, I regard it as
+very important that the fact of the continuity of some material as one
+of the foundations of inheritance has clearly been stated, even if the
+specialised form of the theory, as advocated by Weismann in the doctrine
+of the “germ-lineages” (“Keimbahnen”) should prove unable to stand
+against the facts.
+
+The important problem now presents itself: What is the material, the
+matter, which is handed down from generation to generation as the
+basis of inheritance? Weismann, as we know, regarded it as a very
+complicated structure, part of which by its disintegration became the
+foundation of individual embryology. We have disproved, on the authority
+of many facts, the latter part of this assumption; but of course the
+first part of it may turn out to be true in spite of this. We have no
+means at present to enable us to say *a priori* anything positive or
+negative about the important question of the nature of that matter, the
+continuity of which in inheritance is in some sense a self-evident fact,
+and we therefore shall postpone the answer until a later point of our
+analytical discussion.
+
+
+ON CERTAIN THEORIES WHICH SEEK TO COMPARE INHERITANCE TO MEMORY
+
+It will be advisable first to study some other theoretical views which
+have been put forward with regard to inheritance. The physiologist
+Hering, as early as 1876, compared all heredity to the well-known fact
+of memory, assuming, so to say, a sort of remembrance of all that
+has happened to the species in the continuity of its generations;
+and several German authors, especially Semon, have lately made this
+hypothesis the basis of more detailed speculation.
+
+It is not clear, either from Hering’s paper[121] or from Semon’s
+book,[122] what is really to be understood here by the word “memory,”
+and, of course, there might be understood by it very different things,
+according to the author’s psychological point of view. If he is a
+“parallelist” with regard to so-called psychical phenomena, he would use
+the word memory only as a sort of collective term to signify a resultant
+effect of many single mechanical events, as far as the material world of
+his parallel system comes into account, with which of course the problem
+of inheritance alone deals; but if he maintains the theory of so-called
+psycho-physical interaction, the psychical would be to him a primary
+factor in nature, and so also would memory. As we have said, it is by no
+means clear in what sense the word “memory” is used by our authors, and
+therefore the *most* important point about the matter in question must
+remain *in dubio*.
+
+[121] *Ueber das Gedächtnis als eine allgemeine Function der organischen
+Materie*, Wien, 1870. New edition in *Klassiker d. exakt. Wiss.*,
+Leipzig, Engelmann.
+
+[122] *Die Mneme*, Leipzig, 1904.
+
+But another topic is even more clear in the theory of inheritance, as
+stated in Hering’s and Semon’s writings. The hypothetical fact that
+so-called “acquired characters” are inherited is undoubtedly the chief
+assumption of that theory. Indeed, it would be difficult to understand
+the advantage of the ambiguous word memory, had it not to call attention
+to the hypothetic fact that the organism possesses the faculty of
+“remembering” what once has happened to it or what it once has “done,”
+so to speak, and profiting by this remembering in the next generation.
+The zoologist Pauly indeed has stated this view of the matter in very
+distinct and clear terms.
+
+As we soon shall have another occasion to deal with the much-discussed
+problem of the “inheritance of acquired characters,” we at present
+need only say a few words about the “memory-theory” as a supposed
+“explanation” of heredity. Undoubtedly this theory postulates, either
+avowedly or by half-unconscious implication, that all the single
+processes in individual morphogenesis are the outcome either of
+adaptations of the morphological type, which happened to be necessary
+in some former generation, or of so-called contingent “variations,” of
+some sort or other, which also happened once in the ancestral line.
+Such a postulate, of course, is identical with what is generally called
+the theory of descent in any of its different forms. This theory is
+to occupy us in the next lectures; at present we only analyse the
+“memory-theory” as a theory of heredity in itself. In any case, to
+regard memory as the leading point in inheritance, at least if it is to
+signify what is called memory in any system of psychology, would be to
+postulate that either adaptation or contingent “variation” has been the
+origin of every morphogenetic process. Indeed, the American physiologist
+Jennings did not hesitate to defend such a view most strongly, and many
+others seem to be inclined to do the same.
+
+But such an assumption most certainly cannot be true.
+
+It cannot be true, because there are many phenomena in morphogenesis,
+notably all the phenomena akin to restitution of form, which occur
+in absolute perfection even the very first time they happen. These
+processes, for the simple reason of their *primary perfection*, cannot
+be due either to “learning” from a single adaptation, or to accidental
+variation. We shall afterwards employ a similar kind of argument to
+refute certain theories of evolution. It therefore may be of a certain
+logical interest to notice that at present, combating the memory-theory
+of inheritance, and hereafter, combating certain theories of descent,
+we select not “adaptation” or “variation” as the central points to be
+refuted, but the assumed *contingency* of both of them.
+
+The word “memory,” therefore, may be applied to the phenomena of
+inheritance only in a very figurative meaning, if at all. We do not
+wholly deny the possibility of an inheritance of acquired characters, as
+will be seen later on, and to such a fact there might perhaps be applied
+such a term as “memory” in its real sense, but we simply *know* that
+there *is* something in inheritance which has no similarity whatever
+to what is called “memory” in any species of psychology. A primary
+perfection of processes occurring quite abnormally proves that there is
+a “knowing” of something--if we may say so--but does not prove at all
+that there is a “remembering.”
+
+
+THE COMPLEX-EQUIPOTENTIAL SYSTEM AND ITS RÔLE IN INHERITANCE[123]
+
+[123] Driesch, *Organ. Regul.* 1901.
+
+But we thus far have reached only negative results. Is the question
+necessarily to remain at this point, which could hardly be said to be
+very satisfying; or could we perhaps get better, that is, positive
+results about inheritance by a change of our analytic methods? Let us
+try to analyse the facts that occur in inheritance instead of beginning
+with hypotheses which claim to be complete explanations. Perhaps we
+shall gain, if but small, yet certainly fixed results by an analysis
+which goes from the facts to the theory and not from the theory to the
+facts.
+
+Let the discussions that are to follow be placed upon a basis as broad
+as possible.
+
+Our studies of morphogenetic restitution have shown us that besides the
+harmonious-equipotential systems another and widely different type of
+morphogenetic “systems” (*i.e.* unities consisting of elements equal in
+morphogenetic faculty) may also be the basis of restitution processes.
+Whilst in the harmonious system the morphogenetic acts performed by
+every single element in any actual case are single acts, the totality
+of all the single acts together forming the harmonious whole, in the
+other type of systems now to be examined, complex acts, that is, acts
+which consist of a manifoldness in space and in time, can be performed
+by each single element, and actually are performed by one or the other
+of them. We therefore have given the title of “complex-equipotential
+systems” to the systems in question, as all our denominations are based
+on the concept of the prospective morphogenetic potency, that is of the
+possible fate of the elements.
+
+The cambium of the Phanerogams may be regarded as the very type of a
+complex-equipotential system, promoting restitution of form. It runs
+through the whole stem of our trees, in the form of a hollow tube,
+placed between the inner and the outer cell-layers of the stem, and
+either branch or root may originate from any single one of its cells,
+just as circumstances require. We might call the cambium a system of the
+“complex” type of course, even if every one of its constituents were
+able to form only a root or only a branch by way of restitution. But in
+fact one and the same element can form both of these complex-structures;
+it depends only on its relative position in the actual part of the stem
+isolated for the purposes of experiment, what will be accomplished in
+every case. Here we have a state of affairs, which we shall encounter
+again when studying regeneration in animals: every element of the system
+may be said to contain potencies for the “ideal whole,” though this
+ideal whole will never be realised in its proper wholeness.[124]
+
+[124] The “ideal whole” is also proved to exist, if any *given*
+“Anlage,” say of a branch, is forced to give origin to a root, as has
+really been observed in certain plants. This case, like many other
+less extreme cases of what might be called “compensatory heterotypy,”
+are best to be understood by the aid of the concept of “prospective
+potency.” It is very misleading to speak of a metamorphosis here. I
+fully agree with Krašan about this question. See also page 112, note 1,
+and my *Organ. Regul.* pp. 77, 78.
+
+But there is no need to recur to the “ideal whole” in many other cases
+of adventitious restitution in plants. On isolated leaves of the
+well-known begonia, a whole plant, containing all the essential parts,
+may arise from any single cell[125] of the epidermis, at least along the
+veins, and in some liverworts it has been shown by Vöchting, that almost
+every cell of the whole is able to reproduce the plant, as is also the
+case in many algae.
+
+[125] Winkler has discovered the important fact, that the adventitious
+buds formed upon leaves may originate either from one single cell of
+the epidermis or from several cells together; a result that is very
+important with respect to the problem of the distribution of “potencies.”
+
+In the animal kingdom it is chiefly and almost solely the phenomena
+of regeneration proper which offer typical instances of our systems,
+since adventitious restitution, though occurring for instance in the
+restitution of the lens of vertebrates from the iris, and though
+connected also with the events in regeneration proper,[126] is of but
+secondary importance in animal restitution, at least, if compared with
+restitution in plants. If we study the regeneration of a leg in the
+common newt, we find that it may take place from every section, the
+point of amputation being quite at our choice. Without regarding here
+the exact order of the regeneration phenomena, which is almost unknown
+at present, we in any case can say without any doubt that the line
+of consecutive possible cross-sections forms a complex-morphogenetic
+system, as every one of them is able to give rise to a complex organ,
+viz. the foot and part of the leg. It is an open question whether this
+complex system is to be called “equipotential” or not. It indeed seems
+to be inequipotential at the first glance, for each single section has
+to form a different organogenetic totality, namely, always that specific
+totality which had been cut off; but if we assume hypothetically that
+the real “Anlage” which is produced immediately by the cells of the
+wounded surface is the very same for all of them, and that it is the
+actual state of organisation which determines to what result this
+Anlage is to lead,[127] we may say that the series of consecutive
+cross-sections of a newt’s leg does form a morphogenetic system of the
+complex-equipotential type, promoting secondary regulations of form.
+
+[126] The “regeneration” of the brain of annelids for instance is far
+better regarded as an adventitious formation than as regeneration
+proper: nothing indeed goes on here at the locality of the wound; a new
+brain is formed out of the ectoderm at a certain distance from it.
+
+[127] A full “analytical theory of regeneration” has been developed
+elsewhere (*Organ. Regul.* p. 44, etc.). I can only mention here that
+many different problems have to be studied by such a theory. The
+formation of the “Anlage” out of the body and the differentiation of
+it into the completely formed results of regeneration are two of them.
+The former embraces the question about the potencies not only of the
+regenerating body but of the elements of the Anlage also; the latter
+has to deal with the specific order of the single acts of regenerative
+processes.
+
+Now all these difficulties vanish, if we consider the regeneration of
+animals, such for instance as many worms of the annelid class or our
+familiar ascidian *Clavellina*, in which regeneration in both directions
+is possible. The wound at the posterior end of the one half which
+results from the operation forms a posterior body half, the wound at
+the anterior end of the other half forms an anterior one. Again, it is
+the ideal whole which we meet here: each section of the body indeed may
+be said to contain the potencies for the production of the totality,
+though actually this totality is always realised by the addition of two
+partial organisations. The title of complex-equipotential systems thus
+seems to be fully justified as applied to the systems which are the
+basis of regeneration: each section of the regenerating body may in fact
+produce the same complex whole, or may, if we prefer to say so, at least
+prepare the ground for that complex Anlage, out of which the complex
+totality is actually to arise, in the same manner.
+
+It often occurs in science, that in rather strange and abnormal
+conditions something becomes apparent which might have been found
+everywhere, which is lying before our eyes quite obviously. Are
+we not in just such a condition at present? In order to study the
+complex-equipotential systems, we turn to the phenomena of regeneration
+and of restitution in general; we occasionally even introduce hypotheses
+to render our materials more convenient for our purposes; and all the
+time there is one sort of complex-equipotential system in the body of
+every living being, which only needs to be mentioned in order to be
+understood as such, and which indeed requires no kind of preliminary
+discussion. The system of the propagation cells, in other words the
+sexual organ, is the clearest type of a complex-equipotential system
+which exists. Take the ovary of our sea-urchin for instance, and there
+you have a morphogenetic system every element of which is equally
+capable of performing the same complex morphogenetic course--the
+production of the whole individual.
+
+Further on we shall deal exclusively with this variety of our systems,
+and in doing so we shall be brought back to our problem of heredity. But
+it had its uses to place our concept of the complex-equipotential system
+upon such a broad basis: we at once gave a large range of validity to
+all that is to follow--which, indeed, does not apply to inheritance
+alone, though its significance in a theory of heredity may be called its
+most important consequence.
+
+
+THE SECOND PROOF OF LIFE-AUTONOMY. ENTELECHY AT THE BOTTOM OF INHERITANCE
+
+After we had established the concept of the harmonious-equipotential
+system in a former chapter, we went on to study the phenomena of the
+differentiation of it, and in particular the problem of the localisation
+of all differentiations. Our new concept of the complex-equipotential
+system is to lead us to an analysis of a different kind: we shall pay
+special attention to the origin, to the *genesis* of our complex systems
+that show equipotentiality.
+
+If we review the process of ontogenesis, we are able to trace back every
+complex system to a very small group of cells, and this small group of
+cells again to one single cell. So in plants the cambium may be shown
+to have originated in a sort of tissue-rudiment, established at a very
+early period, and the ovary may be demonstrated to be the outcome of a
+group of but a few cells, constituting the first visible “Anlage” of the
+reproductive organs. At the end then, or from another point of view at
+the beginning, a single cellular element represents the very primordial
+egg-cell.
+
+The whole cambium, there can be no doubt, must be regarded as the result
+of a consecutive number of cell-divisions of the one cell from which it
+originates. So must it be with the ovary. The primordial egg-cell has
+undergone a long line of consecutive divisions; the single eggs are the
+last result of them.
+
+We now proceed to some considerations which have a certain
+logical similarity to those which inaugurated our analysis of the
+differentiation of the harmonious-equipotential systems, though the
+facts in question are very different.
+
+Viewed by itself without any kind of prepossessions, as it might
+be by any one who faces a new problem with the single postulate of
+introducing new natural entities--to use the scholastic phrase--as
+little as possible, the development of the single egg might be regarded
+as proceeding on the foundation of a very complicated sort of machine,
+exhibiting a different kind of construction in the three chief
+dimensions of space, as does also the organism which is to be its result.
+
+But could such a theory--irrespective of all the experimental facts
+which contradict it--could such a theory stand before the *one* fact,
+that there occurs a *genesis* of that complex-equipotential system,
+of which our one single egg forms a part? Can you imagine a very
+complicated machine, differing in the three dimensions of space, to
+be divided hundreds and hundreds of times and in spite of that to
+remain always the same whole? You may reply that during the period
+of cell-divisions there is still no machine, that the machine is
+established only after all the divisions are complete. Good; but what
+then constructs this machine in the definitive cells of our systems, say
+in the eggs? Another sort of machine perhaps? That could hardly be said
+to be of much use. Or that entelechy of which we have spoken? Then you
+would recur to our first proof of vitalism and would burden entelechy
+with a specific performance, that is with the construction of the
+hypothetic machine which you are postulating in every single egg. But of
+course you would break the bounds of physics and chemistry even then.
+
+It seems to me that it is more simple, and so to say more natural, not
+to recur to our first proof of life-autonomy in order to keep to the
+“machine theory” in this new branch of inquiry, but to consider facts as
+they offer themselves to analysis.
+
+But then indeed we are entitled to draw an independent second proof of
+the autonomy of life from our analysis of the genesis of systems of the
+complex-equipotential type. We say it is a mere absurdity to assume that
+a complicated machine, typically different in the three dimensions of
+space, could be divided many many times, and in spite of that always
+be the whole: therefore there cannot exist any sort of machine as the
+starting-point and basis of development.
+
+Let us again apply the name entelechy to that which lies at the very
+beginning of all individual morphogenesis.
+
+Entelechy thus proves to be also that which may be said to lie at
+the very root of inheritance,[128] or at least of the outcome of
+inheritance; the individual formation of the next generation is shown
+not to be performed by a machine but by a natural agent *per se*.
+
+[128] And, of course, at the root of every new starting of certain
+parts of morphogenesis also, as in regeneration and in adventitious
+budding; these processes, as we know, being also founded upon
+“complex-equipotential systems,” which have had their “genesis.”
+
+
+THE SIGNIFICANCE OF THE MATERIAL CONTINUITY IN INHERITANCE
+
+But what about the material continuity appearing in inheritance, which
+we have said to be almost self-evident, as life is only known to exist
+on material bodies? Is there not, in fact, a serious contradiction
+in admitting at the same time entelechy on the one side and a sort
+of material condition on the other as the basis of all that leads to
+and from inheritance? Next summer the relation between matter and our
+autonomous agent of life will be studied more fully; at present it must
+be enough to state in a more simple and realistic way, what we hold
+this relation to be. There is no contradiction at all in stating that
+material continuity is the basis of inheritance on the one side, and
+entelechy on the other. It would be very inconvenient for us if there
+were any: for the material continuity is a mere fact and our entelechy
+we hope we have proved to exist also; if now there were any sort of
+contradiction in assuming the existence of both of them, of course it
+would be fatal to our proof.
+
+Let us try to comprehend what is meant by the statement that entelechy
+and something material are at work in inheritance at the same time.
+Entelechy has ruled the individual morphogenesis of the generation which
+is regarded as being the starting-point for inheritance, and will rule
+also the morphogenesis of the generation which is to follow; entelechy
+determines the egg to be what it is, and the morphogenesis starting from
+this egg to be what it is also. Entelechy, at present, is not much more
+for us than a mere word, to signify the autonomous, the irreducible of
+all that happens in morphogenesis with respect to *order*, in the one
+generation and in the next. But may not the material continuity which
+exists in inheritance account perhaps for the material elements *which
+are to be ordered*? In such a way, indeed, I hope we shall be able to
+reconcile entelechy and the material basis of heredity. May it not be
+that there exist some “means” for morphogenesis, which are handed down
+from generation to generation, always controlled by entelechy, and which
+constitute the real significance of the continuity of matter during
+inheritance?
+
+
+THE EXPERIMENTAL FACTS ABOUT INHERITANCE
+
+Discoveries of the last few years do seem to show that such means
+of a material character, though not the foundation of that order of
+processes which is inherited, are nevertheless among the most necessary
+conditions for the accomplishment of inheritance in general. It is
+scarcely necessary to remind you that for very many years all concrete
+research on heredity proper--that is, the actual comparison of the
+various specific characters in the generations of the grandfather, the
+father, and the child--was due to Galton. You may also be aware that in
+spite of Galton’s inestimable services it was not till 1900 that one of
+the active principles concerned in inheritance was found independently
+by de Vries, Correns, and Tschermak, and that this principle happened
+to be one that *had* been discovered already, stated with the utmost
+clearness and precision by the Augustinian monk, Gregor Mendel,[129] as
+early as 1865, though it had been completely forgotten ever since.
+
+[129] New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann;
+see also Bateson, *Mendel’s Principles of Heredity*, Cambridge, 1902.
+
+The so-called “rule of Mendel” is based upon experiments with hybrids,
+that is, with the offspring of parents belonging to different species,
+or, at least, varieties, but it relates not to the characters of the
+generation resulting immediately from hybridisation, the “first”
+generation of hybrids, as we shall call it, but to the characters of
+that generation which is the result of crossing the hybrids with each
+other, provided that this leads to any offspring at all. There are many
+cases indeed, both amongst animals and plants, where the offspring of
+the hybrids, or in other terms the “second” generation, is found to
+consist of individuals of three different types--the mixed[130] type
+of the hybrids themselves, and the two pure types of the grandparents.
+Whenever the individuals of the “second” generation are separated into
+these three different types, hybrids are said to “split.” It is the
+fact of this splitting on the one hand, and on the other hand a certain
+statement about the numbers of individuals in the three different types
+of the “second” generation, that gives its real importance to Mendel’s
+rule.
+
+[130] For the sake of simplicity I shall not deal here with those
+cases of hybridisation in which one quality is “recessive,” the other
+“dominant,” but only allude to the cases, less numerous though they be,
+where a real mixture of maternal and paternal qualities occurs.
+
+Before discussing what may follow from Mendel’s discovery for the
+theory of heredity, we must lay stress on the fact that there are many
+exceptions to his rule. In quite a number of cases the hybrids are of
+one or more types, which remain constant: there is no splitting at all
+in the second generation. But that does not affect the rule of Mendel in
+those cases where it is true. Where there is a “splitting” in the second
+generation, there also are the numerical proportions stated by Mendel;
+there never are other relations among the numbers of individuals of the
+mixed and of the two pure types than those given by his rule. I regard
+it as very important that this real meaning of Mendel’s principle should
+be most clearly understood.
+
+From the fact of the splitting of hybrids in the second generation most
+important consequences may be drawn for the theory of inheritance; the
+split individuals, if crossed with each other, always give an offspring
+which remains pure; there is no further splitting and no other change
+whatever. The germ-cells produced by the split individuals of the second
+generation may therefore be said to be “pure,” as pure as were those of
+the grandparents. But that is as much as to say that the pureness of
+the germ-cells has been preserved in spite of their passing through the
+“impure” generation of the hybrids, and from this fact it follows again
+that the union of characters in the hybrids must have been such as to
+permit pure separation: in fact, the germ-cells produced by Mendelian
+hybrids may hypothetically be regarded as being pure themselves.[131]
+
+[131] This hypothesis was first suggested by Sutton and is at present
+held by orthodox Mendelians; but probably things are a little more
+complicated in reality, as seems to be shown by some facts in the
+behaviour of so-called “extracted recessives.” In Morgan’s *Experimental
+Zoology*, New York, 1907, a full account of the whole matter is given.
+
+We have not yet considered one feature of all experiments in
+hybridisation, which indeed seems to be the most important of all for
+the theory of inheritance, if taken together with the fact of the
+pureness of the germs. The rule of Mendel always relates to one single
+character of the species or varieties concerned in hybridisation, and
+if it deals with more than one character, it regards every one of them
+separately; indeed, the rule holds for every one of them irrespective
+of the others. We cannot study here how this most important fact of
+the independence of the single characters of a species with regard to
+inheritance leads to the production of new races, by an abnormal mixture
+of those characters. We only take advantage of the fact theoretically,
+and in doing so, I believe, we can hardly escape the conclusion that
+the independence of the single characters in inheritance, taken
+together with the pureness of the germ-cells in the most simple form
+of hybrids, proves that there occurs in inheritance a sort of handing
+over of single and separate morphogenetic agents which relate to the
+single morphogenetic characters of the adult. We may use Bateson’s
+word “allelomorphs” for these agents, or units, as they may be called,
+thereby giving expression to the fact that the single and separate
+units, which are handed over in inheritance, correspond to each other in
+nearly related species without being the same.
+
+And so we have at least an inkling of what the material continuity of
+inheritance is to mean, though, of course, our “single and separate
+morphogenetic agents,” or “units” or “allelomorphs” are in themselves
+not much more than unknown somethings described by a word; but even then
+they are “somethings.”
+
+Besides the researches relating to the rule of Mendel and its
+exceptions, founded, that is, upon a study of the “second” generation of
+hybrids, there is another important line of research lately inaugurated
+by Herbst, which investigates the first generation in hybridisation.
+The hybrids themselves are studied with the special purpose of finding
+out whether the type of the single hybrid may change according to the
+conditions of its development, both outer and inner. The discoveries
+thus made may lead some day to a better understanding of the intimate
+nature of the “units” concerned in heredity, and perhaps to some
+knowledge of the arranging and ruling factor in morphogenesis also.
+
+Starting from the discovery of Vernon, that the hybrids of sea-urchins
+are of different types according to the season, Herbst[132] was able
+to show that differences among the hybrids with regard to their being
+more of the paternal or more of the maternal type, are in part certainly
+due to differences in temperature. But there proved to be still another
+factor at work, and Herbst has succeeded in discovering this factor by
+changing the internal conditions of morphogenesis. Whenever he forced
+the eggs of *Sphaerechinus* to enter into the first[133] phase of
+artificial parthenogenesis and then fertilised them with the sperm of
+*Echinus*, he was able to approximate the offspring almost completely
+to the maternal type, whilst under ordinary conditions the hybrids in
+question follow the paternal far more than the maternal organisation.
+
+[132] *Arch. Entw. Mech.* 21, 22, and 24, 1906-7; see also Doncaster,
+*Phil. Trans. Royal Soc.* London, B. 196, 1903. The influence of
+different temperature upon the organisation of the hybrids is not
+always quite pure, inasmuch as the paternal and the maternal forms may
+themselves be changed by this agent. In spite of that there exists an
+influence of the temperature upon the hybrid *as such*, at least with
+regard to certain features of its organisation.
+
+[133] Only the nucleus of the egg had entered its first stages of
+activity.
+
+What is shown, in the first place, by these discoveries is the
+importance of an arranging and ruling factor in spite of all units. The
+organism is always one *whole* whether the paternal properties prevail
+or the more complicated maternal ones; in other words, all so-called
+properties that consist in the *spatial relations of parts* have nothing
+to do with “units” or “allelomorphs,” which indeed cannot be more
+than necessary means or materials, requiring to be ordered. As to the
+character of the morphogenetic single and separate units themselves
+Herbst is inclined to regard them as specific chemical substances which
+unite correspondingly during nuclear conjugation, forming a sort of
+loose chemical compound. It would depend on the constitution of this
+compound whether germ-cells of hybrids could become pure or not.
+
+
+THE RÔLE OF THE NUCLEUS IN INHERITANCE
+
+At the end of our studies on heredity we hardly can avoid saying a
+few words about the problem of the localisation of the morphogenetic
+units in the germ-cells themselves. Is it in the protoplasm or in the
+nucleus that they are placed? You all know that this question was for
+a long time regarded as more important than any other, and perhaps
+you have already blamed me for not raising it until now. But in my
+opinion results gained by the purely analytical method and carefully
+established, are always superior to those which are of a merely
+descriptive nature and doubtful besides. The famous problem of the part
+played by the nucleus in inheritance is both descriptive and doubtful:
+it is only, so to say, of factual, not of analytical importance, and
+quite insoluble at present.
+
+As for our second proof of vitalism, stating that no kind of machine
+inside the germ-cells can possibly be the foundation of their
+morphogenesis, it is clear that the protoplasm and the nucleus may both
+come into account here on equal terms. If you prefer to say so, it is to
+the nucleus and to its division in particular that the second proof of
+autonomy relates, while the first, though not over-looking the presence
+of nuclei,[134] deals “especially” with the protoplasmic nature of its
+“systems.”
+
+[134] The first proof of vitalism, indeed, rests upon the analysis of
+the differentiation of an harmonious-equipotential system as a *whole*:
+this *whole* cannot be a machine that would relate to differentiation as
+a *whole*; the question whether there might be any machines distributed
+*in* the whole, in the form of the nuclei is of no importance at all in
+this argument. Moreover the pressure experiments (see page 63) prove the
+unimportance of such “machines” for the specificity of differentiation,
+and the second proof of vitalism shows that the nuclei cannot be
+regarded as machines accounting for differentiation in *any* way.
+
+What then can we say, on the basis of actual facts, about the part taken
+by the protoplasm and by the nucleus in inheritance, now that we have
+learnt from our analytical discussion that both of them cannot be any
+kind of morphogenetic machine, but can only be means of morphogenesis?
+Let us state our question in the following way: whereabouts in the
+germ-cells are those “means” of morphogenesis localised, the existence
+of which we infer from the material continuity in the course of
+generations in general and from the facts discovered about hybridisation
+in particular?
+
+The first of the facts generally said to support the view that the
+nucleus of the germ-cells exerts a specified influence upon the
+processes of development and inheritance, relates to the proportion
+between protoplasm and nuclear material in the egg and in the spermiae.
+This proportion is very different in the two sexual products, as we
+know, there being an enormous preponderance of the protoplasm in the
+egg, of the nucleus in the spermatozoon. This seems to indicate that
+the proportion between protoplasm and nucleus is fairly indifferent
+for inheritance, as all the facts go to show that inheritance from
+the father is as common as inheritance from the mother. It is in the
+nucleus, and in the nucleus alone, that any similarity of organisation
+exists between the two sexual products, so very different in all other
+respects: therefore the nucleus should be the organ of inheritance. The
+phenomena of nuclear division, of karyokinesis, which are quite equal in
+both sexual cells, are certainly well fitted to support this hypothesis.
+
+There seems indeed to be some truth in this reasoning, but nevertheless
+it must remain hypothetical; and it must never be forgotten that
+there may be very probably some sort of morphogenetic importance in
+protoplasm also. Rauber and afterwards Boveri[135] have tried to prove
+experimentally that it is on the nuclear chromatic substance only that
+inheritance depends, but the first of these authors failed to get any
+results at all, and the latter obtained only ambiguous ones. Godlewski,
+on the contrary, has fertilised purely protoplasmic egg-fragments of
+the sea-urchin with the sperm of quite another group of Echinoderms,
+and obtained in spite of that a few stages of development of the
+pure maternal type. This experiment seems to place the morphogenetic
+importance of protoplasm beyond all doubt.
+
+[135] Boveri tried to fertilise enucleated fragments of the egg of
+*Sphaerechinus* with the sperm of *Echinus*. He failed to get any
+results in isolated experiments, but found a few small larvae of the
+pure *Echinus* type in large cultures consisting of shaken eggs. But
+later experiments on hybridisation in sea-urchins have shown that a full
+hybrid of *Echinus* and *Sphaerechinus* may be purely paternal also.
+
+I should prefer not to make any definite statement about our problem at
+present. Our actual knowledge of the organisation and metabolism of both
+nucleus and protoplasm is so extremely small and may relate to such very
+insignificant topics, that any definite decision is impossible. I myself
+believe that the nucleus plays an important part in heredity, perhaps
+even a greater one than protoplasm, but this is only my belief.[136]
+
+[136] Surely the new results of Herbst, mentioned above, are another
+indication of the importance of something in the nucleus. The first
+stage in parthenogenesis, which he used in his experiments, is a nuclear
+phenomenon.
+
+The discovery of Gruber and others, that Protozoa are only capable of
+restitution if they contain at least a fragment of the nucleus, has
+also been used occasionally as a proof of the morphogenetic importance
+of the nucleus. But might not this absence of restitution where nuclear
+material is lacking be understood equally well on the hypothesis of Loeb
+and R. S. Lillie that the nucleus is a centre of oxidation in the cell?
+Remove the heart from a vertebrate and the animal will not digest any
+more; but in spite of that the heart is not the organ of digestion.
+
+And so we lay stress once more upon this point: that the experimental
+results of hybridisation and the analytical results obtained by the
+discussion of the complex-equipotential systems are of greater value
+to the theory of heredity than all speculation about the importance or
+unimportance of special constituents of the cell, of whose organisation,
+chemistry, and physics, scarcely anything is known at present.[137]
+
+[137] Boveri (*Ergebn. üb. d. Konstitution etc. des Zellkerns*, Jena,
+1904; and “Zellen-Studien VI.” *Jen. Zeitschr.* 43, 1907) has made it
+highly probable by experiments that the different chromosomes of the
+nucleus of the sexual products play a different part in morphogenesis,
+though not in the sense of different single representatives of
+different single organs. This doctrine, of course, would not alter
+the whole problem very much: the chromosomes would only be *means* of
+morphogenesis and nothing else, no matter whether they were of equal or
+of different formative value. It only is with regard to the problem of
+the determination of sex (see page 107, note 3), that the morphogenetic
+singularity of *one* certain specific chromosome can be said to be
+proved.
+
+
+VARIATION AND MUTATION
+
+Heredity, it has been said, may be understood as resting upon the fact
+that each organism forms its own initial stage again, and that this
+initial stage always encounters conditions of the same kind.
+
+If this statement were quite correct, all the individuals of a given
+species would be absolutely alike everywhere and for ever. But they
+are not alike; and that they are not alike everywhere and for ever is
+not merely the only real foundation of the so-called theory of descent
+we possess, but also forces us to change a little our definition of
+heredity, which now proves to have been only a sort of approximation to
+the truth, convenient for analytical discussion.
+
+In the first place, the conditions which surround the initial stages
+of morphogenesis are not quite equal in every respect: and indeed
+the offspring of a given pair of parents, or better, to exclude all
+complications resulting from sexual reproduction, or amphimixis, as
+Weismann called it--the offspring of one given parthenogenetic female
+are not all equal among themselves. The individuals of each generation
+are well known to vary, and it is especially in this country that the
+so-called individual or fluctuating variation has been most carefully
+studied by statistical methods, Galton and Weldon being the well-known
+pioneers in this field.[138] In fact, if we are allowed to assume that
+this sort of variation is the outcome of a variation of conditions--in
+the most general meaning of the word--we only follow the opinion
+which has almost universally been adopted by the biologists[139] that
+are working at this branch of the subject. Variation proper is now
+generally allowed to be the consequence of variations in nutrition;
+the contingencies of the latter result in contingencies of the former,
+and the law of contingencies is the same for both, being the most
+general law of probability. Of course under such an aspect fluctuating
+variation could hardly be called an exception, but rather an addition to
+inheritance.
+
+[138] H. M. Vernon, *Variations in Animals and Plants*, London, 1903.
+
+[139] De Vries, *Die Mutationstheorie*, i., 1901; and Klebs, *Jahrb.
+wiss. Bot.* 42, 1905.
+
+But there are other restrictions of our definition of heredity. The
+initial stage which is formed again by an organism is not always quite
+identical in itself with the initial stage of its own parent: Bateson
+and de Vries were the first to study in a systematic way these real
+exceptions[140] to true inheritance. As you know, de Vries has given
+them the name of “mutations.” What is actually known on this subject is
+not much at present, but nevertheless is of great theoretical value,
+being the only real foundation of all theories of descent, as we shall
+see in the next lectures. “Mutations” are known to exist at present only
+among some domesticated animals and plants. Nothing of a more general
+character can be said about their law or meaning.[141]
+
+[140] They would not be “real exceptions” if Klebs (*Arch. Entw. Mech.*
+24, 1907) were right in saying that both variations and mutations owe
+their existence to external agents. What is really *proved* by Klebs
+is the possibility of changing the *type* of a curve of variation and
+of provoking certain discontinuous varieties by external means. See
+also Blaringhem (*Comptes rend.* 1905-6, and *Soc. de Biol.* 59, 1905),
+and MacDougal (*Rep. Depart. Bot. Res., 5th Year-book Carnegie Inst.*,
+Washington, 129).
+
+[141] H. de Vries, *Species and Varieties: their Origin by Mutation*,
+London, 1905. A short review of the “mutation-theory” is given by Francé
+in *Zeitschrift f. d. Ausbau d. Entwickelungslehre*, i. 1907. It is well
+known that Gautier, and, in the first place, Korshinsky, advocated a
+similar view previous to the authors named in the text.
+
+
+
+
+CONCLUSIONS FROM THE FIRST MAIN PART OF THESE LECTURES
+
+
+In finishing our chapter on inheritance, we at the same time have
+finished the first main part of our lectures; that part of them which
+has been devoted exclusively to the study of the morphogenesis of the
+*individual*, including the functioning of the adult individual form.
+We now turn to our second part, which is to deal with the problems of
+the diversities of individual forms, with morphological systematics. The
+end of our chapter on inheritance has already led us to the threshold of
+this branch of biological science.
+
+The chief result of the first main part of our lectures has been to
+prove that an autonomy of life phenomena exists at least in some
+departments of individual morphogenesis, and probably in all of them;
+the real starting-point of all morphogenesis cannot be regarded as a
+machine, nor can the real process of differentiation, in all cases where
+it is based upon systems of the harmonious equipotential type. There
+cannot be any sort of machine in the cell from which the individual
+originates, because this cell, including both its protoplasm and its
+nucleus, has undergone a long series of divisions, all resulting in
+equal products, and because a machine cannot be divided and in spite of
+that remain what it was. There cannot be, on the other hand, any sort
+of machine as the real foundation of the whole of an harmonious system,
+including many cells and many nuclei, because the development of this
+system goes on normally, even if its parts are rearranged or partly
+removed, and because a machine would never remain what it had been in
+such cases.
+
+If our analytical discussions have thus led us to establish a typical
+kind of vitalism, it follows that we can by no means agree with Wilhelm
+Roux in his denomination of the analytical science of the individual
+form and form-production as “Entwickelungsmechanik,” “developmental
+mechanics,” a title, which, of course, might easily be transformed
+into that of “morphogenetic mechanics,” to embrace not only normal
+development, but restitution and adaptation too. We feel unable to speak
+of “mechanics” where just the contrary of mechanics, in the proper
+meaning of the word, has been proved to exist.
+
+Names of course are of comparatively small importance, but they
+should never be allowed to be directly misleading, as indeed the term
+“Entwickelungsmechanik” has already proved to be. Let us rather say,
+therefore, that we have finished with this lecture that part of our
+studies in biology which has had to deal with morphogenetic physiology
+or physiological morphogenesis.
+
+Once more we repeat, at this resting-point in our discussions, that both
+of our proofs of life-autonomy have been based upon a careful analysis
+of certain facts about the distribution of morphogenetic potencies in
+two classes of morphogenetic systems, and upon nothing else. To recall
+only one point, we have not said that regeneration, merely because it
+is a kind of restitution of the disturbed whole, compels us to admit
+that biological events happen in a specific and elemental manner, but,
+indeed, regeneration *does* prove vitalism, because it is founded upon
+the existence of certain complex-equipotential systems, the analysis of
+the genesis of which leads to the understanding of life-autonomy. This
+distinction, in fact, is of the greatest logical importance.
+
+
+
+
+PART II
+
+SYSTEMATICS AND HISTORY
+
+*A.* THE PRINCIPLES OF SYSTEMATICS
+
+
+RATIONAL SYSTEMATICS
+
+All systematics which deserves the predicate “rational” is founded
+upon a concept or upon a proposition, by the aid of which a totality
+of specific diversities may be understood. That is to say: every
+system claiming to be rational gives us a clue by which we are able to
+apprehend either that there cannot exist more than a certain number of
+diversities of a certain nature, or that there can be an indefinite
+number of them which follow a certain law with regard to the character
+of their differences.
+
+Solid geometry, which states that only five regular bodies are possible,
+and points out the geometrical nature of these bodies, is a model
+of what a rational system should be. The theory of conic sections
+is another. Take the general equation of the second degree with two
+unknowns, and study all the possible forms it can assume by a variation
+of its constants, and you will understand that only four different types
+of conic sections are possible--the circle, the ellipse, the hyperbola,
+and the parabola.
+
+In physics and chemistry no perfect rational systems have been
+established hitherto, but there are many systems approaching the ideal
+type in different departments of these sciences. The chemical type of
+the monohydric saturated alcohols, for instance, is given by the formula
+C_nH_{2n+1}OH, and in this formula we not only have an expression of
+the law of composition which all possible alcohols are to follow,--but,
+since we know empirically the law of quantitative relation between
+*n* and various physical properties, we also possess in our formula a
+general statement with respect to the totality of the properties of any
+primary alcohol that may be discovered or prepared in the future. But
+chemistry has still higher aims with regard to its systematics: all of
+you know that the so-called “periodic law of the elements” was the first
+step towards a principle that may some day give account of the relation
+of all the physical and chemical properties of any so-called element
+with its most important constant, the atomic weight, and it seems to be
+reserved for the present time to form a real fundamental system of the
+“elements” on the basis of the periodic law by the aid of the theory
+of electrons. Such a fundamental system of the elements would teach us
+that there can only be so many elements and no more, and only of such a
+kind. In crystallography a similar end has been reached already by means
+of certain hypothetic assumptions, and systematics has here accounted
+for the limited number and fixed character of the possible forms of
+crystalline symmetry.
+
+It is not difficult to understand the general logical type of all
+rational systems, and logic indeed can discover it without appealing
+to concrete sciences or to geometry. Rational systematics is always
+possible whenever there exists any fundamental concept or proposition
+which carries with it a principle of division; or to express it somewhat
+differently, which would lead to contradictions, if division were to
+be tried in any but one particular manner. The so-called “genus,” as
+will easily be perceived, then embraces all its “species” in such a
+manner that all peculiarities of the species are represented already in
+properties of the genus, only in a more general form, in a form which
+is still unspecified. The genus is both richer in content and richer in
+extent than are the species, though it must be added that its richness
+in content is, as it were, only latent: but it may come into actuality
+by itself and without any help from without.
+
+We are dealing here with some of the most remarkable properties of the
+so-called synthetic judgments *a priori* in the sense of Kant, and,
+indeed, it seems that rational systematics will only be possible where
+some concept of the categorical class or some proposition based upon
+such concept lies at the root of the matter or at least is connected
+with it in some way. In fact, all rational systems with regard to the
+relations of symmetry in natural bodies deal ultimately with space; or
+better, all systems in such fields are able to become rational only if
+they happen to turn into questions of spatial symmetry.
+
+All other genera and species, whether of natural bodies or of facts,
+can be related only on the basis of empirical abstraction, *i.e.* can
+never attain rationality: here, indeed, the genus is richer in extent
+and poorer in content than are the species. The genus is transformed
+into the species, not by any inherent development of latent properties,
+but by a mere process of addition of characteristic points. It is
+impossible to deduce the number or law or specifications of the species
+from the genus. Mere “classification,” if we may reserve the honorable
+name of systematics for the rational type, is possible here, a mere
+statement in the form of a catalogue, useful for orientation but for
+nothing more. We may classify all varieties of hats or of tables in the
+same way.
+
+
+BIOLOGICAL SYSTEMATICS
+
+At this point we return from our logical excursion to our proper subject
+of biology; for I am sorry to say biological systematics is at present
+of our second type of systematics throughout: it is classification pure
+and simple. We have a catalogue in our hands, but nothing more.
+
+Such a statement of fact conveys not a particle of censure, casts not
+the least reflection on the gifted men who created the classification of
+animals or plants. It is absolutely necessary to have such a catalogue,
+and indeed the catalogue of the organisms can be said to have been
+improved enormously during the advance of empirical and descriptive
+biological science. Any classification improves as it becomes more
+“natural,” as the different possible schemes of arrangement, the
+different reasons of division, agree better and better in their results;
+and, in fact, there has been a great advance of organic classification
+in this direction. The “natural” system has reached such perfection,
+that what is related from one point of view seems nearly related also
+from almost all points of view which are applicable, at least from those
+which touch the most important characteristics. There has been a real
+weighing of all the possible reasons of division, and that has led to a
+result which seems to be to some extent final.
+
+But, nevertheless, we do not understand the *raison d’être* of the
+system of organisms; we are not at all able to say that there must be
+these classes or orders or families and no others, and that they must be
+such as they are.
+
+Shall we ever be able to understand that? Or will organic systematics
+always remain empirical classification? We cannot answer this question.
+If we could, indeed, we should have what we desire! As simple relations
+of space are certainly not the central point of any problematic rational
+organic systematics even of the future, the question arises, whether
+there could be found any principle of another type in the realm of
+synthetic *a priori* judgments which could allow an inherent sort of
+evolution of latent diversities, as do all judgments about spatial
+symmetry. At the end of the second course of these lectures, which is to
+be delivered next summer, we shall be able to say a few more words about
+this important point.
+
+The concept of what is called “a type,” due almost wholly to Cuvier and
+Goethe, is the most important of all that classification has given to
+us. Hardly second in importance is the discovery of the “correlation of
+parts,” as a sort of connection which has the character of necessity
+without being immediately based upon causality. Rádl seems to be
+the only modern author who has laid some stress on this topic. The
+harmony which we have discovered in development is also part of this
+correlation. When, later on, we come to discuss analytically our well
+established entelechy as the ultimate basis of individual organisation,
+we shall be able to gain more satisfactory ideas with respect to the
+meaning of the non-causal but necessary connection, embraced in the
+concepts of type and of correlation of parts.
+
+The type is a sort of irreducible arrangement of different parts; the
+correlation deals with the degree and the quality of what may be called
+the actual make of the parts, in relation to one another: all ruminants,
+for instance, are cloven-footed, the so-called dental formulae are
+characteristic of whole groups of mammals. Of course all such statements
+are empirical and have their limits: but it is important that they are
+possible.[142]
+
+[142] Recent years have created the beginnings of a systematics based on
+chemical differences of metabolism and its products: such differences in
+fact have been found to go hand in hand with diversities of the type in
+some cases (v. Bunge, Przibram, etc.).
+
+It has been the chief result of comparative embryology to show that the
+type as such is more clearly expressed in developmental stages than
+it is in the adults, and that therefore the embryological stages of
+different groups may be very much more similar to each other than are
+the adults: that is the truth contained in the so-called “biogenetisches
+Grundgesetz.” But the specific differences of the species are not
+wanting in any case of ontogeny, in spite of such similarities in
+different groups during development.
+
+We have applied the name “systematics” or, if rationality is excluded,
+“classification” to all that part of a science which deals with
+diversities instead of generalities: in such a wide meaning systematics,
+of course, is not to be confused with that which is commonly called so
+in biology, and which describes only the exterior differences of form.
+Our systematics is one of the two chief parts of biology; what are
+called comparative anatomy and comparative embryology are its methods.
+For it must be well understood that these branches of research are only
+methods and are not sciences by themselves.
+
+
+
+
+*B.* THE THEORY OF DESCENT
+
+
+1. GENERALITIES
+
+It is most generally conceded at the present time that the actually
+existing state of all organisms whatsoever is the result of their
+history. What does that mean? What are the foundations upon which the
+assumption rests? What is the relation of systematics to history? In
+raising such questions and considerations we are treading the ground
+sacred to the theory of descent.
+
+I well know that you prefer the name “theory of evolution” for what
+I am speaking of: but it may be misleading in various respects. We
+already know that quite a determinate meaning has been given to the word
+“evolutio” as applied to individual morphogenesis, “evolutio” being
+here opposed to “epigenesis.” Now there would be nothing against the
+use of the word evolution in a wider sense--indeed it is often applied
+nowadays to denote the fact that a something is actually “evolved” in
+embryology--if only our entelechy had taken the place of the machine
+of the mechanists. But that is the very point: there must be a real
+“evolving” of a something, in order that the word evolution may be
+justified verbally: and that is not the case in so-called phylogeny. At
+least we know nothing of an evolutionary character in the problematic
+pedigree of the organisms, as we shall see more fully hereafter. The
+term “theory of descent” is therefore less open to objection than is the
+usual English term. The word transformism, as used by the French, would
+also be a very good title.
+
+The theory of descent is the hypothetic statement that the organisms
+are really allied by blood among each other, in spite of their
+diversities.[143] The question about their so-called monophyletic
+or polyphyletic origin is of secondary importance compared with the
+statement of relationship in general.
+
+[143] We prefer this unpretending definition of the theory of descent
+to every other. As soon as one introduces into the definition the
+concept of the “transmutability of species,” the term “species” would
+require a special definition, and that would lead to difficulties which
+it is unnecessary to deal with for our main purposes. It has been
+remarked by Krašan, (*Ausichten und Gespräche über die individuelle und
+specifische Gestaltung in der Natur*) and by several other writers,
+that the problem of mutability or immutability of course relates to the
+individuals in the first place. I should like to add to this remark that
+the possibility must be admitted of the individuals being transmutable,
+whilst the “species” are not transmutable at the same time, the line
+of the “species” being a fixed order, through which the “individuals”
+have to pass in the course of their generations. What is meant here
+will become clearer, when we study the different possible aspects of
+“phylogeny.”
+
+There are two different groups of facts which have suggested the idea
+of transformism: none of these facts can be said to be conclusive, but
+there certainly is a great amount of probability in the whole if taken
+together.
+
+The first group of evidences which lead to the hypothesis of the real
+relationship of organisms consists of facts relating to the geographical
+distribution of animals and plants and to palæontology. As to geography,
+it seems to me that the results of the floral and faunal study of groups
+of islands are to be mentioned in the first place. If, indeed, on
+each of the different islands, *A* *B* *C* and *D*, forming a group,
+the species of a certain genus of animals or plants are different in a
+certain respect, and show differences also compared with the species
+living on the neighbouring continent, of which there is geological
+evidence that the islands once formed a part, whilst there is no change
+in the species on the continent itself for very wide areas, then, no
+doubt, the hypothesis that all these differing species once had a common
+origin, the hypothesis that there is a certain community among them all,
+will serve to elucidate in some way what would seem to be very abstruse
+without it. And the same is true of the facts of palaeontology. In
+the geological strata, forming a continuous series, you find a set of
+animals, always typical and specific for every single stratigraphical
+horizon, but forming a series just as do those horizons. Would not the
+whole aspect of these facts lose very much of its peculiarity if you
+were to introduce the hypothesis that the animals changed with the
+strata? The continuity of life, at least, would be guaranteed by such an
+assumption.
+
+The geographical and geological evidences in favour of the theory of
+descent are facts taken from sciences which are not biology proper; they
+are not facts of the living but only facts about the living. That is not
+quite without logical importance, for it shows that not biology alone
+has led to the transformism hypothesis. Were it otherwise, transformism
+might be said to be a mere hypothesis *ad hoc*; but now this proves to
+be not the case, though we are far from pretending that transformism
+might be regarded as resting upon a real *causa vera*.
+
+But let us study the second group of facts which support the theory of
+descent. It is a group of evidences supplied by biology itself that we
+meet here, there being indeed some features in biology which can be
+said to gain some light, some sort of elucidation, if the theory of
+descent is accepted. Of course, these facts can only be such as relate
+to specific diversities, and indeed are facts of systematics; in other
+words, there exists something in the very nature of the system of
+organisms that renders transformism probable. The system of animals and
+plants is based upon a principle which might be called the principle
+of *similarities and diversities by gradation*; its categories are not
+uniform but different in degree and importance, and there are different
+kinds of such differences. No doubt, some light would be shed upon this
+character of the system, if we were allowed to assume that the relation
+between similarities and diversities, which is gradual, corresponded to
+a blood-relationship, which is gradual also.
+
+
+THE COVERT PRESUMPTION OF ALL THEORIES OF DESCENT
+
+We have used very neutral and somewhat figurative words, in order to
+show what might be called the logical value of the theory of descent,
+in order to signify its value with respect to so-called “explanation.”
+We have spoken of the “light” or the “elucidation” which it brings, of
+the “peculiarity of aspect” which is destroyed by it. We have used this
+terminology intentionally, for it is very important to understand that
+a specific though hidden addition is made almost unconsciously to the
+mere statement of the hypothesis of descent as such, whenever this
+hypothesis is advocated in order to bring light or elucidation into any
+field of systematic facts. And this additional hypothesis indeed must be
+made from the very beginning, quite irrespective of the more detailed
+problems of the law of transformism, in order that *any* sort of
+so-called explanation by means of the theory of descent may be possible
+at all. Whenever the theory that, in spite of their diversities, the
+organisms are related by blood, is to be really useful for explanation,
+it must necessarily be assumed in every case that the steps of change,
+which have led the specific form *A* to become the specific form *B*,
+have been such as only to change *in part* that original form *A*. That
+is to say: the similarities between *A* and *B* must never have become
+overshadowed by their diversities.
+
+Only on this assumption, which indeed is a newly formed additional
+subsidiary hypothesis, joined to the original hypothesis of descent in
+general--a hypothesis regarding the very nature of transformism--only
+on this almost hidden assumption is it possible to speak of any sort of
+“explanation” which might be offered by the theory of transformism to
+the facts of geography, geology, and biological systematics. Later on
+we shall study more deeply the logical nature of this “explanation”; at
+present it must be enough to understand this term in its quasi-popular
+meaning.
+
+What is explained by the hypothesis of descent--including the additional
+hypothesis, that there always is a prevalence of the similarities
+during transformism--is the fact that in palaeontology, in the groups
+of island and continent faunae and florae taken as a whole, as well as
+in the single categories of the system, the similarities exceed the
+diversities. The *similarities* now are “explained”; that is to say,
+they are understood as resting on but one principle: the similarities
+are understood as being due to inheritance;[144] and now we have but one
+problem instead of an indefinite number. For this reason Wigand granted
+that the theory of descent affords what he calls a numerical reduction
+of problems.
+
+[144] It seems to me that my argument gives a broader logical basis
+to the theory of descent than does that of G. Wolff (*Die Begründung
+der Abstammungslehre*, München, 1907). Wolff starts from the concept
+of organic teleology, and thus finds the only reason for accepting
+the theory of transformism in the existence of so-called “rudimentary
+organs”; these organs would form an obstacle to teleology if they could
+not be regarded as inherited.
+
+Understanding then what is explained by the theory of descent with its
+necessary appendix, we also understand at once what is *not* elucidated
+by it: the diversities of the organism remain as unintelligible as they
+always were, even if we know that inheritance is responsible for what
+is similar or equal. Now there can be no doubt that the diversities are
+the more important point in systematics; if there were only similarities
+there would be no problem of systematics, for there would be no system.
+Let us be glad that there are similarities in the diversities, and that
+these similarities have been explained in some way; but let us never
+forget what is still awaiting its explanation. Unfortunately it has been
+forgotten far too often.
+
+
+THE SMALL VALUE OF PURE PHYLOGENY
+
+And so we are led to the negative side of the theory of transformism,
+after having discussed its positive half. The theory of descent as
+such, without a real knowledge of the factors which are concerned in
+transformism, or of the law of transformism, in other terms, leaves the
+problem of systematics practically where it was, and adds really nothing
+to its solution. That may seem very deplorable, but it is true.
+
+Imagine so-called historical geology, without any knowledge of the
+physical and chemical factors which are concerned in it: what would
+you have except a series of facts absolutely unintelligible to you? Or
+suppose that some one stated the cosmogenetic theory of Kant and Laplace
+without there being any science of mechanics: what would the theory mean
+to you? Or suppose that the whole history of mankind was revealed to
+you, but that you had absolutely no knowledge of psychology: what would
+you have but facts and facts and facts again, with not a morsel of real
+explanation?
+
+But such is the condition in which so-called phylogeny stands. If it
+is based only on the pure theory of transformism, there is nothing
+explained at all. It was for this reason that the philosopher Liebmann
+complained of phylogeny that it furnishes nothing but a “gallery of
+ancestors.” And this gallery of ancestors set up in phylogeny is not
+even certain; on the contrary, it is absolutely uncertain, and very
+far from being a fact. For there is no sound and rational principle
+underlying phylogeny; there is mere fantastic speculation. How could it
+be otherwise where all is based upon suppositions which themselves have
+no leading principle at present? I should not like to be misunderstood
+in my polemics against phylogeny. I fully grant you that it may be
+possible in a few cases to find out the phylogenetic history of smaller
+groups with some probability, if there is some palaeontological
+evidence in support of pure comparative anatomy; and I also do not
+hesitate to allow that such a statement would be of a certain value with
+regard to a future discovery of the “laws” of descent, especially if
+taken together with the few facts known about mutations. But it is quite
+another thing with phylogeny on the larger scale. Far more eloquent than
+any amount of polemics is the fact that vertebrates, for instance, have
+already been “proved” to be descended from, firstly, the amphioxus;
+secondly, the annelids; thirdly, the *Sagitta* type of worms; fourthly,
+from spiders; fifthly, from *Limulus*, a group of crayfishes; and
+sixthly, from echinoderm larvae. That is the extent of my acquaintance
+with the literature, with which I do not pretend to be specially
+familiar. Emil du Bois-Reymond said once that phylogeny of this sort is
+of about as much scientific value as are the pedigrees of the heroes of
+Homer, and I think we may fully endorse his opinion on this point.
+
+
+HISTORY AND SYSTEMATICS
+
+A few words should be devoted to the relations between history and
+systematics in biology. Is there no contradiction between historical
+development and a true and rational system which, we conceded, might
+exist some day in biological sciences, even though it does not at
+present? By no means. A totality of diversities is regarded from quite
+different points of view if taken as the material of a system, and if
+considered as realised in time. We have said that chemistry has come
+very near to proper rational systematics, at least in some of its
+special fields; but the compounds it deals with at the same time may
+be said to have originated historically also, though not, of course,
+by a process of propagation. It is evident at once that the geological
+conditions of very early times prohibited the existence of certain
+chemical compounds, both organic and inorganic, which are known at
+present. None the less these compounds occupy their proper place in
+the system. And there may be many substances theoretically known to
+chemical systematics which have never yet been produced, on account
+of the impossibility of arranging for their proper conditions of
+appearance, and nevertheless they must be said to “exist.” “Existence,”
+as understood in systematics, is independent of special space and of
+special time, as is the existence of the laws of nature: we may speak of
+a Platonic kind of existence here. Of course it does not contradict this
+sort of ideal existence if reality proper is added to it.
+
+Thus the problem of systematics remains, no matter whether the theory
+of descent be right or wrong. There always remains the question about
+the totality of diversities in life: whether it may be understood by
+a general principle, and of what kind that principle would be. As,
+in fact, it is most probably by history, by descent, that organic
+systematics is brought about, it of course most probably will happen
+some day that the analysis of the causal factors concerned in the
+history will serve to discover the principle of systematics also.
+
+Let us now glance at the different kinds of hypotheses which have been
+established in order to explain how the descent of the organisms might
+have been possible. We have seen that the theory of transformism alone
+is not worth very much as a whole, unless at least a hypothetical
+picture can be formed of the nature of the transforming factors: it is
+by some such reasoning that almost every author who has defended the
+theory of descent in its universality tries to account for the manner in
+which organisms have acquired their present diversities.
+
+
+2. THE PRINCIPLES OF DARWINISM
+
+There is no need in our times and particularly in this country, to
+explain in a full manner the theory known under the name of Darwinism.
+All of you know this theory, at least in its outlines, and so we may
+enter at once upon its analytic discussion. A few words only I beg
+you to allow me as to the name of “Darwinism” itself. Strange to say,
+Darwinism, and the opinion of Charles Darwin about the descent of
+organisms, are two different things. Darwin, the very type of a man
+devoted to science alone and not to personal interests,--Darwin was
+anything but dogmatic, and yet Darwinism is dogmatism in one of its
+purest forms. Darwin, for instance, gave the greatest latitude to the
+nature of the variations which form the battleground of the struggle
+for existence and natural selection; and he made great allowances for
+other causal combinations also, which may come into account besides
+the indirect factors of transformism. He was Lamarckian to a very
+far-reaching extent. And he had no definite opinion about the origin
+and the most intimate nature of life in general. These may seem to
+be defects but really are advantages of his theory. He left open the
+question which he could not answer, and, in fact, he may be said to be a
+good illustration of what Lessing says, that it is not the possession
+of truth but the searching after it, that gives happiness to man. It was
+but an outcome of this mental condition that Darwin’s polemics never
+left the path of true scientific discussions, that he never in all his
+life abused any one who found reason to combat his hypotheses, and that
+he never turned a logical problem into a question of morality.
+
+How different is this from what many of Darwin’s followers have made out
+of his doctrines, especially in Germany; how far is “Darwinism” removed
+from Darwin’s own teaching and character!
+
+It is to Darwinism of the *dogmatic* kind, however, that our next
+discussions are to relate, for, thanks to its dogmatism, it has the
+advantage of allowing the very sharp formulation of a few causal
+factors, which *a priori* might be thought to be concerned in organic
+transformism, though we are bound to say that a really searching
+analysis of these factors ought to have led to their rejection from the
+very beginning.
+
+The logical structure of dogmatic Darwinism reveals two different parts,
+which have nothing at all to do with one another.
+
+
+NATURAL SELECTION
+
+We shall first study that part of it which is known under the title
+of natural selection, irrespective of the nature of the causes of
+primary differences, or, in other words, the nature of variability.
+This part may be said to belong to Darwin’s personal teachings and not
+only to “Darwinism.” The offspring of a certain number of adults show
+differences compared with each other; there are more individuals in the
+offspring than can grow up under the given conditions, therefore there
+will be a struggle for existence amongst them, which only the fittest
+will survive; these survivors may be said to have been “selected” by
+natural means.
+
+It must be certain from the very beginning of analysis that natural
+selection, as defined here, can only eliminate what cannot survive, what
+cannot stand the environment in the broadest sense, but that natural
+selection never is able to create diversities. It always acts negatively
+only, never positively. And therefore it can “explain”--if you will
+allow me to make use of this ambiguous word--it can “explain” only why
+certain types of organic specifications, imaginable *a priori*, do
+*not* actually exist, but it never explains at all the existence of the
+specifications of animal and vegetable forms that are actually found. In
+speaking of an “explanation” of the origin of the living specific forms
+by natural selection one therefore confuses the sufficient reason for
+the non-existence of what there is not, with the sufficient reason for
+the existence of what there is. To say that a man has explained some
+organic character by natural selection is, in the words of Nägeli, the
+same as if some one who is asked the question, “Why is this tree covered
+with these leaves,” were to answer “Because the gardener did not cut
+them away.” Of course that would explain why there are no more leaves
+than those actually there, but it never would account for the existence
+and nature of the existing leaves as such. Or do we understand in the
+least why there are white bears in the Polar Regions if we are told that
+bears of other colours could not survive?
+
+In denying any real explanatory value to the concept of natural
+selection I am far from denying the action of natural selection. On
+the contrary, natural selection, to some degree, is *self-evident*;
+at least as far as it simply states that what is incompatible with
+permanent existence cannot exist permanently, it being granted that
+the originating of organic individuals is not in itself a guarantee of
+permanency. Chemical compounds, indeed, which decompose very rapidly
+under the conditions existing at the time when they originated may also
+be said to have been eliminated by “natural selection.” It is another
+question, of course, whether in fact all eliminations among organic
+diversities are exclusively due to the action of natural selection in
+the proper Darwinian sense. It has been pointed out already by several
+critics of Darwinism and most clearly by Gustav Wolff, that there are
+many cases in which an advantage with regard to situation will greatly
+outweigh any advantage in organisation or physiology. In a railway
+accident, for instance, the passengers that survive are not those who
+have the strongest bones, but those who occupied the best seats; and
+the eliminating effect of epidemics is determined at least as much by
+localities, *e.g.* special houses or special streets, as by the degree
+of immunity. But, certainly, natural selection is a *causa vera* in many
+other cases.
+
+We now may sum up our discussion of the first half of Darwinism.
+Natural selection is a negative, an eliminating factor in transformism;
+its action is self-evident to a very large degree, for it simply
+states that things do not exist if their continuance under the given
+conditions is impossible. To consider natural selection as a positive
+factor in descent would be to confound the sufficient reason for the
+non-existence of what is not, with the sufficient reason of what is.
+
+Natural selection has a certain important logical bearing on
+systematics, as a science of the future, which has scarcely ever been
+alluded to. Systematics of course has to deal with the totality of the
+possible, not only of the actual diversities; it therefore must remember
+that more forms may be possible than are actual, the word “possible”
+having reference in this connection to originating, not to surviving.
+Moreover, systematics is concerned not only with what has been
+eliminated by selection, but also with all that might have originated
+from the eliminated types. By such reasoning natural selection gains a
+very important aspect--but a logical aspect only.
+
+
+FLUCTUATING VARIATION THE ALLEGED CAUSE OF ORGANIC DIVERSITY
+
+The second doctrine of dogmatic Darwinism states that all the given
+diversities among the organisms that natural selection has to work
+upon are offered to natural selection by so-called fluctuating
+variation; that is, by variation as studied by means of statistics.
+This sort of variation, indeed, is maintained to be indefinite in
+direction and amount, at least by the most conservative Darwinians; it
+has occasionally been called a real differential; in any case it is
+looked upon as being throughout contingent with regard to some unity
+or totality; which, of course, is not to mean that it has not had a
+sufficient reason for occurring.
+
+It could hardly be said to be beyond the realm of possibility that such
+differences among organic species as only relate to degree or quantity
+and perhaps to numerical conditions also, might have been “selected” out
+of given contingent variations, if but one postulate could be regarded
+as fulfilled. This postulate may appropriately be stated as the fixation
+of new averages of variation by inheritance. Let the average value of
+a variation, with regard to a given property of a given species be *n*
+and let the value *n* + *m*--*m* being variable--which is represented in
+fewer individuals of course than is *n*, be such as to offer advantages
+in the struggle for existence; then the individuals marked by *n* + *m*
+will have the greater chance of surviving. Our postulate now states
+that, in order that a permanent increase of the average value of the
+variation in question may be reached, *n* + *m* in any of its variable
+forms must be able to become the average value of the second generation,
+as *n* was the average value of the first. Out of the second generation
+again it would be the few individuals marked by *n* + *m* + *o*, which
+would be selected; *n* + *m* + *o* would be the new average; afterwards
+*n* + *m* + *o* + *p* would be selected, would become the new average,
+and so on. A black variety for instance might be selected by such a
+series of processes out of a grey-coloured one without difficulty.
+
+But our postulate is not beyond all doubt: certain experiments, at
+least, which have been carried out about the summation of variations
+of the true fluctuating type by any kind of selection seem to show
+that there may be a real progress for a few generations, but that this
+progress is always followed by a reversion. Of course our experience
+is by no means complete on this subject, and, indeed, it may be shown
+in the future that positive transforming effects of fluctuating
+variability, in connection with selective principles, are possible in
+the case of new quantitative differences (in the widest sense), but we
+are not entitled to say so at present.
+
+And this is the only condition on which we can give credit to the second
+doctrine of dogmatic Darwinism. Its second principle, indeed, proves
+to be absolutely inadequate to explain the origin of any other kind of
+specific properties whatever.
+
+I cannot enter here into the whole subject of Darwinian criticism.[145]
+Our aims are of a positive character, they desiderate construction
+and only use destruction where it is not to be avoided. So I shall
+only mention that dogmatic Darwinism has been found to be unable to
+explain every kind of mutual adaptations, *e.g.* those existing between
+plants and insects; that it can never account for the origin of those
+properties that are indifferent to the life of their bearer, being mere
+features of organisation as an arrangement of parts; that it fails in
+the face of all portions of organisation which are composed of many
+different parts--like the eye--and nevertheless are functional units
+in any passive or active way; and that, last not least, it has been
+found to be quite inadequate to explain the first origin of all newly
+formed constituents of organisation even if they are not indifferent:
+for how could any rudiment of an organ, which is not functioning at all,
+not only be useful to its bearer, but be useful in such a degree as to
+decide about life or death?
+
+[145] See Wigand, *Der Darwinismus und die Naturforschung Newton’s und
+Cuvier’s*, Braunschweig, 1874-7; Nägeli, *Mechanisch-physiologische
+Theorie der Abstammungslehre*, München, 1884; G. Wolff, *Beiträge zur
+Kritik der Darwin’schen Lehre*, 2nd ed. Leipzig, 1898; etc.
+
+It is only for one special feature that I should like to show, by
+a more full analysis, that dogmatic Darwinism does not satisfy the
+requirements of the case. The special strength of Darwinism is said to
+lie in its explaining everything that is useful in and for organisms;
+the competitive factor it introduces does indeed seem to secure at least
+a relative sort of adaptedness between the organism and its needs. But
+in spite of that, we shall now see that Darwinism fails absolutely to
+explain those most intimate organic phenomena which may be said to be
+the most useful of all.
+
+Darwinism in its dogmatic form is not able to explain the origin of any
+sort of organic restitution; it is altogether impossible to account for
+the restitutive power of organisms by the simple means of fluctuating
+variation and natural selection in the struggle for existence. Here we
+have the logical *experimentum crucis* of Darwinism.
+
+Let us try to study in the Darwinian style the origin of the
+regenerative faculty, as shown in the restitution of the leg of a
+newt. All individuals of a given species of the newt, say *Triton
+taeniatus*, are endowed with this faculty; all of them therefore must
+have originated from ancestors which acquired it at some time or other.
+But this necessary supposition implies that all of these ancestors must
+have lost their legs in some way, and not only one, but all four of
+them, as they could not have acquired the restitutive faculty otherwise.
+We are thus met at the very beginning of our argument by what must be
+called a real absurdity, which is hardly lessened by the assumption that
+regeneration was acquired not by all four legs together, but by one
+after the other. But it is absolutely inevitable to assume that *all*
+the ancestors of our *Triton* must have lost one leg, or more correctly,
+that only those of them survived which had lost one! Otherwise not all
+newts at the present day could possess the faculty of regeneration! But
+a second absurdity follows the first one; out of the ancestors of our
+newt, which survived the others by reason of having lost one of their
+legs, there were selected only those which showed at least a very small
+amount of healing of their wound. It must be granted that such a step
+in the process of selection, taken by itself, would not at all seem to
+be impossible; since healing of wounds protects the animals against
+infection. But the process continues. In every succeeding stage of it
+there must have survived only those individuals which formed just a
+little more of granulative tissue than did the rest: though *neither*
+they themselves *nor* the rest could use the leg, which indeed was
+not present! That is the second absurdity we meet in our attempt at a
+Darwinian explanation of the faculty of regeneration; but I believe the
+first one alone was sufficient.
+
+If we were to study the “selection” of the faculty of one of the
+isolated blastomeres of the egg of the sea-urchin to form a whole larva
+only of smaller size, the absurdities would increase. At the very
+beginning we should encounter the absurdity, that of all the individuals
+there survived only those which were not whole but half; for *all*
+sea-urchins are capable of the ontogenetical restitution in question,
+*all* of their ancestors therefore must have acquired it, and they
+could do that only *if* they became halved at first by some accident
+during early embryology. But we shall not insist any further on this
+instance, for it would not be fair to turn into ridicule a theory which
+bears the name of a man who is not at all responsible for its dogmatic
+form. Indeed, we are speaking against Darwinism of the most dogmatic
+form only, not against Darwin himself. He never analysed the phenomena
+of regeneration or of embryonic restitution--they lay in a field very
+unfamiliar to him and to his time. I venture to say that if he had taken
+them into consideration, he would have agreed with us in stating that
+his theory was not at all able to cover them; for he was prepared to
+make great concessions, to Lamarckism for instance, in other branches of
+biology, and he did not pretend, to know what life itself is.
+
+Darwin was not a decided materialist, though materialism has made
+great capital out of his doctrines, especially in Germany. His book,
+as is well known, is entitled “The Origin of *Species*,” that is of
+organic *diversities*, and he himself possibly might have regarded all
+restitution as belonging to the original properties of life, anterior to
+the originating of diversities. Personally he might possibly be called
+even a vitalist. Thus dogmatic “Darwinism” in fact is driven into all
+the absurdities mentioned above, whilst the “doctrine of Darwin” can
+only be said to be wrong on account of its failing to explain mutual
+adaptation, the origin of new organs, and some other features in organic
+diversities; the original properties of life were left unexplained by it
+intentionally.
+
+
+DARWINISM FAILS ALL ALONG THE LINE
+
+The result of our discussion then must be this: selection has proved to
+be a negative factor only, and fluctuating variation as the only way
+in which new properties of the organisms might have arisen has proved
+to fail in the most marked manner, except perhaps for a few merely
+quantitative instances. Such a result betokens the complete collapse
+of dogmatic Darwinism as a general theory of descent: the most typical
+features of all organisms remain as unexplained as ever.
+
+What then shall we put in the place of pure Darwinism? Let us first try
+a method of explanation which was also adopted occasionally by Darwin
+himself: let us study that form of transformation theories which is
+commonly known under the title of Lamarckism.
+
+
+3. THE PRINCIPLES OF LAMARCKISM.
+
+As the word “Darwinism” does not signify the proper theoretical system
+of Charles Darwin, so Lamarckism as commonly understood nowadays is a
+good deal removed from the original views of Jean Baptiste Lamarck.
+Lamarckism is generally regarded as reducing all organic diversities to
+differences in the needs of individual life, but Lamarck himself, as
+must be emphasised from the very beginning, did not at all maintain the
+opinion that the great characteristics of the types were only due to
+such accidental factors. He supposed a sort of law of organisation to
+be at the root of systematics, as developed in history, and the needs
+of life were only responsible, according to him, for splitting the
+given types of organisation into their ultimate branches. Thus Lamarck,
+to a great extent at any rate, belongs to a group of authors that we
+shall have to study afterwards: authors who regard an unknown law of
+phylogenetic development as the real basis of transformism. Modern
+so-called Neo-Lamarckism, on the other hand, has indeed conceded the
+principle of needs to be the sole principle of transformism. Let us then
+study Lamarckism in its dogmatic modern form.
+
+
+ADAPTATION AS THE STARTING-POINT
+
+All facts of morphological adaptations--facts which we have analysed
+already from a different point of view, as being among the most typical
+phenomena of organic regulation--form the starting-point of this
+theory, and it must be granted that they form a very solid foundation,
+for they are facts. The theory only has to enlarge hypothetically the
+realm of these facts, or rather the realm of the law that governs them.
+Indeed, it is assumed by Lamarckism that the organism is endowed with
+the faculty of responding to *any* change of the environment which may
+change its function by a morphologically expressed alteration of its
+functional state and form, which is adapted to the state of conditions
+imposed from without. Of course, as stated in this most general form,
+the assumption is not true, but it is true within certain limits, as
+we know; and there seems to be no reason why we should not believe
+that there are many more cases of adaptation than we actually know at
+present, or that, in former phylogenetic times, the organisms were more
+capable of active adaptation than they are now. So to a certain extent,
+at least, Lamarckism can be said to rest upon a *causa vera*.
+
+It is important to notice that this *causa vera* would imply vitalistic
+causality when taken in the wide meaning which Lamarckism allows to
+it: indeed, the power of active adaptation to indefinite changes would
+imply a sort of causal connection that is nowhere known except in the
+organism. Lamarck himself is not very clear about this point, he seems
+to be afraid of certain types of uncritical vitalism in vogue in his
+days; but modern writers have most clearly seen what the logical
+assumptions of pure Lamarckism are. Next to Cope, August Pauly[146] may
+be said to be the most conscious representative of a sort of so-called
+psychological vitalism, which indeed Lamarckism as a general and
+all-embracing theory must have as its basis.
+
+[146] *Darwinismus und Lamarckismus*, München, 1905.
+
+
+THE ACTIVE STORING OF CONTINGENT VARIATIONS AS A HYPOTHETIC PRINCIPLE
+
+This point will come out more fully, if now we turn to study a certain
+group of principles, upon which dogmatic Lamarckism rests: I say
+principles and not facts, for there are no facts but only hypothetic
+assumptions in this group of statements. We do know a little about
+adaptations, at least to a certain extent, and it was only about the
+sphere of the validity of a law, which was known to be at work in
+certain cases, that hypothetical additions were made. In the second
+group of the foundations of Lamarckism we know absolutely nothing;
+accidental variations of form are supposed to occur, and the organism is
+said to possess the faculty of keeping and storing these variations and
+of handing them down to the next generation, if they happen to satisfy
+any of its needs.
+
+But these needs are not of the actual type, brought forth by a change of
+the functional state of the individual, as in the case of adaptations:
+they are of a somewhat mysterious nature. A glance at the theory of the
+origin of the movements which are called acts of volition in the human
+child may serve to elucidate what is meant.
+
+Acts of volition are said thus to originate in random movements of the
+new-born infant: certain of these accidental motions which happen to
+relieve some pain or to afford some pleasure are “remembered,” and are
+used another time quite consciously to bring forth what is liked or to
+remove what is disliked. So much for the present on a very difficult
+subject, which will occupy us next year at much greater length. It is
+clear that at least three fundamental phenomena are concerned in this
+theory of the origin of acts of volition: the liking and disliking, the
+keeping in mind, and the volition itself. The real act of volition,
+indeed, is always based upon a connection of all these factors, these
+factors now being connected in such a way that even their kind of
+connection may be said to be a fourth fundamental principle. In order
+that the particular effect may be obtained which is wanted because it is
+liked, the possible ways leading to it, which appeared among the random
+movements in the very beginning, are now regarded as “means” and may now
+be said to be “used.” But that is as much as to say that the “means”
+are judged with respect to their usefulness for the actual purpose, and
+therefore *judgment* is the fourth foundation of the act of volition.
+
+In fact, Pauly does not hesitate to attribute judgment, along with the
+other psychological elements, to the organisms whilst undergoing their
+transformation. There has been formed, for instance, by accidental
+variation some pigment which by its chemical nature brings the organism
+into a closer connection with the light of the medium; the individual
+likes that, keeps the pigment for itself and produces it again in the
+next generation; and indeed it will safeguard any sort of improvement
+which chance may effect in this primitive “eye.” Such a view is said
+to hold well with respect to the origin of every new organ. And this
+psychological argument is also said to afford the real explanation of
+adaptation proper. Adaptation also is regarded not as a truly primary
+faculty of the organism, but as a retention or provoking of metabolic
+states which occurred by accident originally and were then found to
+be useful; now they are reproduced either in every single case of
+individual morphogenesis, without regard to actual requirements, or
+else only in response to such: in the first case they are “inherited,”
+in the second they only occur as regulations. Thus the process of
+judgment, together with all the other elemental factors of psychical
+life concerned in it, has been made to account for adaptation proper.
+The whole theory has accordingly become very uniform and simple.
+
+
+CRITICISM OF THE “INHERITANCE OF ACQUIRED CHARACTERS” ASSUMED BY
+LAMARCKISM
+
+In addressing ourselves to the criticism of Neo-Lamarckism we shall
+neglect as far as possible all the different psychological principles
+concerned in it--which in any case would need rather a great amount of
+epistemological sifting--and shall keep to those hypothetic facts which
+are supposed to be such as may be actually observed in nature.
+
+All of you know that the so-called inheritance of acquired characters
+lies at the root of Lamarckism; and from this hypothesis our critical
+analysis is to start, disregarding a larger or smaller number of
+psychological principles that are brought into the field.
+
+The name of “acquired characters” may *a priori* be given to three
+different types of phenomena: firstly, variations including mutations;
+secondly, disease or injuries; and thirdly, the results of the actual
+process of adaptation of every kind.
+
+In the first of these groups, the true problem of the inheritance of
+“acquired” characters appears only with certain restrictions. All
+variations and mutations are indeed “acquired” by one generation so
+far as the earlier generation did not possess them, but mutations, at
+least, cannot be said to be acquired by the actual adult personality:
+they are innate in it from its very beginning, and therefore may better
+be called congenital.[147] Congenital properties of the mutation type
+are, in fact, known to be inherited: their inheritance does not present
+any problem of its own, but is included in the changes of the hereditary
+condition to which they are due altogether.[148] All properties of the
+variation type, on the other hand, having been studied statistically,
+are known to be inherited, to a certain small extent, as we have seen
+already whilst studying Darwinism, though they are possibly always
+liable to reversion. Modern science, as we know,[149] regards them as
+due to changes of nutrition, in the most general meaning of the word.
+Under such a view variations might indeed be said to belong to the
+acquired group of organic specifications; their inheritance, as will
+be seen later on, would hardly be quite a pure instance of what we are
+searching for. In no case can true variations claim to be of great
+importance in problems of transformism.
+
+[147] This would not be true, if the varieties of plants produced by
+Blaringhem, Klebs, and MacDougal by means of *external* agents were
+really “mutations” (comp. page 238, note 3).
+
+[148] Of course, the inheritance of mutations would imply a certain sort
+of “inheritance of acquired characters,” on the condition stated in the
+preceding note. But, probably, the germs of the next generation might
+be regarded here as being directly affected by the external agent, in a
+manner that will briefly be mentioned later on in the text.
+
+[149] Comp. page 238, note 2.
+
+But what is known about the inheritance of those properties which
+beyond any doubt may be said to have originated in the adult individual
+as such, and of which lesions and adaptations proper, as shown for
+instance among amphibious plants, are instances of the two most
+typical groups?[150] Weismann did good service by putting an end to
+the scientific credulity which prevailed with regard to this subject.
+Weismann was led by his theory of the germ plasm to deny the inheritance
+of acquired characters of the typical kinds. He could not imagine how
+the effect of any agent upon the adult, be it of the merely passive or
+of the adaptive kind, could have such an influence upon the germ as to
+force it to produce the same effect in spite of the absence of that
+agent. In fact, that is what the inheritance of acquired characters
+would render necessary, and a very strange phenomenon it would be,
+no doubt. But, of course, taken alone, it could never be a decisive
+argument against such inheritance. I fully agree, that science is
+obliged to explain new facts by what is known already, as long as it is
+possible; but if it is no longer possible, the theory of course has to
+be changed, and not the facts. On this principle one would not neglect
+the fact of an inheritance of acquired properties, but on the contrary
+one perhaps might use it as a new evidence of vitalism.
+
+[150] Certain English authors have applied the term “modification” to
+all kinds of organic properties acquired from without, whether they are
+adapted or not.
+
+But are there any facts?
+
+At this point we come to speak about the second group of Weismann’s
+reasonings. He not only saw the difficulty of understanding inheritance
+of acquired characters on the principles of the science of his time,
+but he also criticised the supposed facts; and scarcely any of them
+stood the test of his criticism. Indeed, it must fairly be granted that
+not one case is known which really proves the inheritance of acquired
+characters, and that injuries certainly are never found to be inherited.
+In spite of that, I do not believe that we are entitled to deny the
+possibility of the inheritance of a certain group of acquired characters
+in an absolute and dogmatic manner, for there are a few facts which seem
+at least to tend in the direction of such an inheritance, and which seem
+to show that it might be discovered perhaps one day, if the experimental
+conditions were changed.
+
+I am not referring here to the few cases in which bacteria were made
+colourless or non-virulent by outside factors, or in which certain
+fungi were forced to permanent agamic reproduction by abnormal external
+conditions and were shown to retain their “acquired properties”
+after the external conditions had been restored. In these cases only
+reproduction by simple division occurred, and that does not imply the
+true problem of inheritance. Nor am I referring to the few cases of
+non-adaptive “modifications” found by Standfuss and Fischer, in which
+butterflies that had assumed an abnormal kind of pigmentation under
+the influence of abnormal temperature acting upon the pupa, were seen
+to form this same kind of pigmentation in the next generation under
+normal conditions of temperature. These cases, though important in
+themselves, are capable perhaps of a rather simple explanation, as in
+fact has been suggested. Some necessary means both of inheritance and of
+morphogenesis, the former being present in the propagation cells, may
+be said to have been changed or destroyed by heat, and therefore, what
+seems to be inherited after the change of the body only, would actually
+be the effect of a direct influence of the temperature upon the germ
+itself.[151] Let me be clearly understood: I do not say that it is so,
+but it may be so. What seems to me to be more important than everything
+and to have a direct bearing on the real discovery of the inheritance
+of acquired characters in the future, is this. In some instances
+plants which had been forced from without to undergo certain typical
+morphological adaptations, or at least changes through many generations,
+though they did not keep the acquired characters permanently in spite
+of the conditions being changed to another type, were yet found to lose
+the acquired adaptations not suddenly but only in the course of three
+or more generations. A certain fern, *Adiantum*, is known to assume a
+very typical modification of form and structure, if grown on serpentine;
+now Sadebeck,[152] while cultivating this serpentine modification of
+*Adiantum* on ordinary ground, found that the first generation grown in
+the ordinary conditions loses only a little of its typical serpentine
+character, and that the next generation loses a little more, so that
+it is not before the fifth generation that all the characters of the
+serpentine modification have disappeared. There are a few more cases
+of a similar type relating to plants grown in the plains or on the
+mountains. There also it was found to take time, or rather to take the
+course of *several* generations, until what was required by the new
+conditions was reached. Of course these cases are very very few compared
+with those in which a *sudden* change of the adaptive character,
+corresponding to the actual conditions, sets in; but it is enough that
+they do exist.
+
+[151] Of course the inheritance of specific values from the results of
+fluctuating variations, leading to new averages of variability (see
+p. 265), may also be understood in this manner, the conditions of
+nourishment acting upon the adult and upon its germs equally well.
+
+[152] *Berichte üb. d. Sitzung. d. Ges. f. Bot.*, Hamburg, 1887, 3 Heft.
+
+Would it not be possible at least that adaptations which last
+for thousands of generations or more might in fact change the
+adaptive character into a congenital one? Then we not only should
+have inheritance of acquired characters, but should have a sort
+of explanation at the same time for the remarkable fact that
+certain histological structures of a very adapted kind are formed
+ontogenetically before any function exists, as is known to be the
+case with the structures in the bones of vertebrates, for instance.
+Experiments are going on at Paris, and perhaps in other places of
+scientific research also, which, it is hoped, will show that animals
+reared in absolute darkness for many generations will lose their
+perfectly formed eyes, and that animals from the dark with very
+rudimentary eyes will be endowed with properly functioning ones, after
+they have been reared in the light for generations. Such a result indeed
+would account for the many animals, of the most different groups, which
+live in dark caves and possess only rudiments of eyes: functional
+adaptation is no longer necessary, so-called atrophy by inactivity sets
+in, and the results “acquired” by it are inherited.[153]
+
+[153] Quite recently Kammerer (*Arch. Entw. Mech.* 25, 1907, p. 7) has
+published very important experiments on the inheritance of “acquired”
+modifications with regard to the peculiarities of reproduction in
+*Salamandra atra* and *S. maculosa*. It seems rather improbable--though
+not absolutely impossible--that the germ cells were directly affected by
+the external modifying agent in this case.
+
+But enough of possibilities. Let us be content at present to know at
+least a few real instances with regard to the slowness of the process of
+what might be said to be “re-adaptation” in some plants. This process
+shows us a way by which our problem may some day be solved; it allows
+us to introduce inheritance of acquired characters as a legitimate
+hypothesis at least, which not only will explain many of the diversities
+in systematics historically, but also can be called, though not a *causa
+vera*, yet certainly more than a mere fiction.
+
+
+OTHER PRINCIPLES WANTED
+
+We have only dealt with the probability of the inheritance of
+morphological or physiological[154] adaptation. If that could really be
+considered as one of the factors concerned in the theory of descent,
+many, if not all of those congenital diversities among organic species
+which are of the type of a true structural correspondence to their
+future functional life, might be regarded as explained, that is,
+as reduced to one and the same principle. But nothing more than an
+explanation of *this* kind of diversities is effected by our principle,
+and very much more remains to be done, for organic diversities not only
+consist in specifications and differences as to histology, but are to a
+much more important degree, differences of organisation proper, that is,
+of the arrangement of parts, in the widest sense of the word.[155]
+
+[154] We have not spoken about the hypothetic inheritance of pure
+physiological adaptations, for it is clear without further discussion
+that innate specific immunity, for instance, being a specific
+“adaptedness” (*see* p. 186) *might* be due to the inheritance of the
+results of active immunity as an adaptation, just as adaptive congenital
+structures *might* be due to such an inheritance.
+
+[155] C. E. v. Baer clearly discriminated between the type, the degree
+of organisation, and the histological structure. All these three topics
+indeed have to be taken into account separately; the third alone is of
+the adaptive type. All of them may be independent of each other: the
+Amoeba may be as adapted histologically as is a high vertebrate, but it
+is of much lower type; and in its own type it is of a lower degree of
+organisation than Radiolaria are.
+
+Would it be possible to interpret the origin of this sort of systematic
+diversities by a reasoning similar to that by which we have understood,
+at least hypothetically, congenital adaptedness?
+
+Dogmatic Lamarckism, we know, uses two principles as its foundations;
+one of them, adaptation and its inheritance, we have studied with what
+may be called a partly positive result. The other is the supposed
+faculty of the organism to keep, to store, and to transfer those
+variations or mutations of a not properly adaptive sort which, though
+originating by chance, happen to satisfy some needs of the organism.
+
+
+CRITICISM OF THE HYPOTHESIS OF STORING AND HANDING DOWN CONTINGENT
+VARIATIONS
+
+Strange to say, this second hypothesis of dogmatic Lamarckism, invented
+with the express purpose of defeating Darwinism and taking the place of
+its fluctuating variability, which was found not to do justice to the
+facts--this second hypothesis of dogmatic Lamarckism is liable to just
+the same objections as dogmatic Darwinism itself.
+
+As it is important to understand well the real logical nature of
+our objections to both of the great transformistic theories, we
+think it well to interrupt our argument for a moment, in order to
+consider a certain point which, though very important in itself,
+seems of only secondary importance to us in our present discussion.
+Dogmatic Darwinism--I do not say the doctrine of Charles Darwin--is
+materialistic at bottom, and indeed has been used by many to complete
+their materialistic view of the universe on its organic side. The word
+“materialism” must not necessarily be taken here in its metaphysical
+sense, though most materialists are dogmatic metaphysicians. It also
+can be understood as forming part of a phenomenological point of view.
+Materialism as a doctrine of science means simply this: that whether
+“nature” be reality or phenomenon, in any case there is but one ultimate
+principle at its base, a principle relating to the movements of
+particles of matter. It is this point of view which dogmatic Darwinism
+strengthens; on the theory of natural selection and fluctuating
+variations, due to accidental differences of nutrition, organisms are
+merely arrangements of particles of matter, nothing else; and moreover,
+their kinds of arrangement are understood, at least in principle.
+Lamarckism, on the other hand, is not materialistic, but most markedly
+vitalistic--psychistic even; it takes life for granted when it begins
+its explanations.
+
+You may tell me that Darwin did the same, that he expressly states that
+his theory has nothing to do with the origin of life; that the title
+of his work is “The Origin of *Species*.” It would certainly be right
+to say so, at least with reference to Darwin personally; but in spite
+of that, it must be granted that Darwin’s doctrine contains a certain
+germ of materialism which has been fully developed by the Darwinian
+dogmatists, while Lamarckism is antimaterialistic by its very nature.
+
+Now it is very important, I think, to notice that this difference
+between the two theories is unable to disguise one main point which is
+common to both: and it is to this point, and to this point only, that
+our chief objections against both these theories converge at present.
+
+The *contingency* of the typical organic form is maintained by Darwinism
+as well as by Lamarckism: both theories, therefore, break down for
+almost the same reasons. The term “contingency” can signify very
+different relations, having but little in common; but it is sufficient
+for our present purpose to observe that there may be distinguished
+roughly two main classes of contingencies, which may provisionally be
+called the “contingency of being,” and the “contingency of occurring.”
+It is with the contingency of being that criticism of Darwinism and
+Lamarckism of the dogmatic type has to deal. Darwinism dealt with
+variations occurring at random; the organic form was the result of
+a fixation of only one kind of such variations, all others being
+extinguished by selection. In other terms, the specific organised
+form, as understood by Darwinism, was a unit only to the extent that
+all its properties related to one and the same body, but for the rest
+it was a mere aggregation or summation. It may be objected to this
+statement, that by being inherited in its specificity the Darwinian
+form proved to be a unit in a higher sense of the word, even in the
+opinion of dogmatic Darwinians; and this objection, perhaps, holds good
+as far as inheritance is concerned. But on the other hand, it must
+never be forgotten that the word “unit” had quite a vague and empty
+meaning even then, as indeed everything the organism is made up of
+is regarded as being in itself due to a contingent primary process,
+which has no relation to its fellow-processes. “Unit,” indeed, in spite
+of inheritance--which, by the way, is alleged also to be a merely
+materialistic event--means to Darwinians no more when applied to the
+organism than it does when applied to mountains or islands, where of
+course a sort of “unit” also exists in some sense, as far as one and the
+same body comes into account, but where every single character of this
+unit, in every single feature of form or of quality, is the result of
+factors or agents each of which is independent of every other.
+
+To this sort of contingency of being, as maintained by Darwinians,
+criticism has objected, as we know, that it is quite an impossible
+basis of a theory of descent, since it would explain neither the first
+origin of an organ, nor any sort of harmony among parts or among whole
+individuals, nor any sort of restitution processes.
+
+Now Lamarckism of the dogmatic kind, as will easily be seen, only
+differs from Darwinism in this respect, that what according to the
+latter happens to the organism passively by means of selection, is
+according to the former performed actively by the organism, by means of
+a “judgment”--by the retention and handing down of chance variations.
+The specificity of the form as a whole is contingent also according
+to Lamarckism. And, indeed, criticism must reject this contingency of
+being in exactly the same way as it rejected the contingency of form
+maintained by Darwinians.
+
+As far as the inheritance of truly adaptive characters comes into
+account--that is, the inheritance of characters which are due to the
+active faculty of adaptation possessed by the organism, bearing a
+vitalistic aspect throughout--hardly anything could be said against
+Lamarckism, except that inheritance of acquired characters is still
+an hypothesis of small and doubtful value at present. But that
+*specific organisation proper* is due to *contingent* variations, which
+accidentally have been found to satisfy some needs of the individual and
+therefore have been maintained and handed down, this reasoning is quite
+an impossibility of exactly the same kind as the argument of Darwinism.
+
+The process of restitution, perfect the very first time it occurs, if it
+occurs at all, is again the classical instance against this new sort of
+contingency, which is assumed to be the basis of transformism. Here we
+see with our eyes that the organism can do more than simply perpetuate
+variations that have occurred at random and bear in themselves no
+relation whatever to any sort of unit or totality. There *exists* a
+faculty of a certain higher degree in the organism, and this faculty
+cannot possibly have originated by the process which Lamarckians[156]
+assume. But if their principle fails in one instance, it fails as a
+*general* theory altogether. And now, on the other hand, as we actually
+see the individual organism endowed with a morphogenetic power,
+inexplicable by Lamarckism, but far exceeding the organogenetic faculty
+assumed by that theory, would it not be most reasonable to conclude from
+such facts, that there exists a certain organising power at the root of
+the transformism of species also, a power which we do not understand,
+which we see only partially manifested in the work of restitutions,
+but which certainly is not even touched by any of the Lamarckian
+arguments? There does indeed exist what Gustav Wolff has called primary
+purposefulness (“primäre Zweckmässigkeit”), at least in restitutions,
+and this is equally unexplainable by Darwinism and by the dogmatism of
+the Lamarckians.
+
+[156] I repeat once more that we are dealing here with dogmatic
+“Neo-”Lamarckism exclusively. This theory indeed claims to explain *all*
+features and properties of organic bodies on the basis of the feeling
+of needs and storing of contingent fulfilments and on this basis alone,
+just as dogmatic “Neo”-Darwinism claims to account for *all* those
+phenomena on the ground of contingent variations and natural selection.
+Darwin himself, as we have seen, intentionally left unexplained certain
+primary features of life and therefore cannot be blamed for having
+failed to explain them, though even then his theory remains wrong.
+Lamarck personally considered a real primary organisatory law of
+phylogeny as being of fundamental importance, and therefore he is not in
+the least responsible if “Neo-Lamarckism” fails as a universal theory.
+
+But before entering into this area of hypothesis, let us mention a few
+more objections to be made to the theory of the contingency of form as
+put forward by Lamarckians. In the first place, let us say a few words
+about the appropriateness of the term “contingency” as used in this
+connection. The forms are regarded as contingent by Lamarckians inasmuch
+as the variations which afterwards serve as “means” to the “needs” of
+the organism occur quite accidentally with regard to the whole organism.
+It might be said that these “needs” are not contingent but subject
+to an inherent destiny, but this plea is excluded by the Lamarckians
+themselves, when they say that the organism experiences no need until it
+has enjoyed the accidental fulfilment of the same. So the only thing in
+Lamarckian transformism which is not of a contingent character would be
+the psychological agent concerned in it, as being an agent endowed with
+the primary power of feeling needs after it has felt fulfilment, and of
+judging about what the means of future fulfilment are, in order to keep
+them whenever they offer. But these are characteristics of life itself,
+irrespective of all its specific forms, which alone are concerned in
+transformism. Now indeed, I think, we see as clearly as possible that
+Darwinism and Lamarckism, in spite of the great contrast of materialism
+and psychologism, shake hands on the common ground of the contingency of
+organic forms.
+
+The whole anti-Darwinistic criticism therefore of Gustav Wolff for
+instance, may also be applied to Lamarckism with only a few changes
+of words. How could the origin of so complete an organ as the eye of
+vertebrates be due to contingent variations? How could that account for
+the harmony of the different kinds of cells in this very complicated
+organ with each other and with parts of the brain? And how is it to be
+understood, on the assumption of contingency, that there are two eyes of
+almost equal perfection, and that there are two feet, two ears? Islands
+and mountains do not show such symmetry in *their* structures.
+
+We shall not repeat our deduction of the origin of restitutions, of
+regeneration for instance, on the dogmatic Lamarckian theory. As we
+have said already, it would lead to absurdities as great as in the
+case of dogmatic Darwinism, and indeed we already have mentioned that
+Lamarckians would hardly even attempt to explain these phenomena.
+It follows that dogmatic Lamarckism fails as a general theory about
+form.[157]
+
+[157] Compare also the excellent criticism of Lamarckism lately given by
+G. Wolff, *Die Begründung der Abstammungslehre*, München, 1907.
+
+There is finally one group of facts often brought forward against
+Lamarckism by Darwinian authors[158] which may be called the logical
+*experimentum crucis* of this doctrine, an *experimentum* destined
+to prove fatal. You know that among the polymorphic groups of bees,
+termites, and ants, there exists one type of individuals, or even
+several types, endowed with some very typical features of organisation,
+but at the same time absolutely excluded from reproduction: how could
+those morphological types have originated on the plan allowed by the
+Lamarckians? Of what use would “judgment” about means that are offered
+by chance and happen to satisfy needs, be to individuals which die
+without offspring? Here Lamarckism becomes a simple absurdity, just as
+Darwinism resulted in absurdities elsewhere.
+
+[158] It has also very often been said by Darwinians that Lamarckism is
+only able to explain those cases of adaptedness which relate to active
+functioning but not mere passive adapted characters, like “mimicry” for
+example. But this argument *taken by itself*, it seems to me, would not
+be fatal to Neo-Lamarckism in the special form August Pauly gave to this
+doctrine.
+
+We were speaking about dogmatic Darwinism then, and it is about dogmatic
+Lamarckism that we are reasoning at present; both theories must fall in
+their dogmatic form, though a small part of both can be said to stand
+criticism. But these two parts which survive criticism, one offered by
+Lamarck, the other by Darwin, are far from being a complete theory of
+transformism, even if taken together: they only cover a small area of
+the field concerned in the theory of descent. Almost everything is still
+to be done, and we may here formulate, briefly at least, what we expect
+to be accomplished by the science of the future.
+
+
+4. THE REAL RESULTS AND THE UNSOLVED PROBLEMS OF TRANSFORMISM
+
+What has been explained to a certain extent by the two great theories
+now current is only this. Systematic diversities consisting in mere
+differences as to intensity or number may perhaps owe their origin to
+ordinary variation. They may at least, if we are entitled to assume
+that heredity in some cases is able to hand on such variations without
+reversion, which, it must be again remarked, is by no means proved by
+the facts at present. Natural selection may share in this process by
+eliminating all those individuals that do not show the character which
+happens to be useful. That is the Darwinian part of an explanation of
+transformism which may be conceded as an hypothesis. On the other side,
+congenital histological adaptedness may be regarded hypothetically as
+due to an inheritance of adaptive characters which had been acquired by
+the organism’s activity, exerted during a great number of generations.
+That is the Lamarckian part in the theory of descent.
+
+But nothing more is contributed to this theory either by the doctrine
+of Darwin or by that of Lamarck. So it follows that almost everything
+has still to be done; for no hypothesis at present accounts for
+the foundation of all systematics, viz., for the differences in
+organisation, in all that relates to the so-called types as such and
+the degree of complication in these types, both of which (types and
+degree of complication) are independent of histological adaptation and
+adaptedness.
+
+What then do we know about any facts that might be said to bear on
+this problem? We have stated already at the end of our chapter devoted
+to the analysis of heredity that what we actually know about any
+deviation of inheritance proper, that is, about congenital differences
+between the parents and the offspring, relating to mere tectonics,
+is practically nothing: indeed, there are at our disposal only the
+few facts observed by de Vries or derived from the experience of
+horticulturalists and breeders. We may admit that these facts at
+least prove the possibility[159] of a discontinuous variation, that
+is of “mutation,” following certain lines of tectonics and leading to
+*constant* results; but everything else, that is everything about a real
+theory of phylogeny, must be left to the taste of each author who writes
+on the theory of the Living. You may call that a very unscientific state
+of affairs, but no other is possible.
+
+[159] But nothing more. All “mutations” hitherto observed in nature
+or (comp. page 238, note 3) experimentally produced relate only to
+“varieties” and not to “species.” One could hardly say that the
+recent investigations about the production of mutations by *external*
+means have strengthened their importance for the general theory of
+transformism.
+
+And, in fact, it has been admitted by almost all who have dealt with
+transformism without prepossessions that such is the state of affairs.
+Lamarck himself, as we have mentioned already, was not blind to the fact
+that a sort of organisatory law must be at the base of all transformism,
+and it is well known that hypothetical statements about an original law
+of phylogeny have been attempted by Nägeli, Kölliker, Wigand, Eimer,
+and many others. But a full discussion of all these “laws” would hardly
+help us much in our theoretical endeavour, as all of them, it must be
+confessed, do little more than state the mere fact that some unknown
+principle of organisation must have been at work in phylogeny, if we are
+to accept the theory of descent at all.
+
+It is important to notice that even such a convinced Darwinian as
+Wallace, who is well known to have been an independent discoverer of the
+elimination principle, admitted an exception to this principle in at
+least one case--with regard to the origin of man. But one exception of
+course destroys the generality of a principle.
+
+As we ourselves feel absolutely incapable of adding anything specific
+to the general statement that there *must* be an unknown principle of
+transformism, if the hypothesis of descent is justified at all, we may
+here close our discussion of the subject.
+
+
+5. THE LOGICAL VALUE OF THE ORGANIC FORM ACCORDING TO THE DIFFERENT
+TRANSFORMISTIC THEORIES
+
+A few words only must be added about two topics: on the character of
+organic forms as regarded by the different transformistic theories, and
+on the relation of transformism in general to our concept of entelechy.
+
+We have learnt that both Darwinism and Lamarckism, in their dogmatic
+shape, regard the specific forms of animals and plants as being
+contingent; in fact, it was to this contingency that criticism was
+mainly directed. We therefore are entitled to say that to Darwinism and
+Lamarckism organic forms are accidental in the very sense of the *forma
+accidentalis* of the old logicians. There are indefinite forms possible,
+according to these theories, and there is no law relating to these
+forms. Systematics, under such a view, must lose, of course, any really
+fundamental importance. “There is no rational system about organisms”:
+that is the ultimate statement of Darwinism and of Lamarckism on this
+doubtful question. Systematics is a mere catalogue, not at present
+only, but for ever, by the very nature of the organisms. It is not
+owing to the indefinite number of possible forms that both our theories
+came to deny the importance of systematics, but to the want of a *law*
+relating to this indefinite number: among chemical compounds indefinite
+possibilities also exist in some cases, but they obey the law of the
+general formula. It is very strange that Darwinians of all people are
+in the forefront of systematic research in all countries: do they not
+see that what they are trying to build up can only relate to accidental
+phenomena? Or have they some doubts about the foundations of their own
+theoretical views, in spite of the dogmatic air with which they defend
+them? Or is it the so-called historical interest which attracts them?
+
+A new question seems to arise at this point: Have not we ourselves
+neglected history in favour of systematics and laws? Our next lecture,
+the last of this year, will give the answer to this question.
+
+At present we continue our study of the possible aspects of systematics.
+It is not difficult to find out what meaning organic forms would assume
+under any phylogenetic theory opposed to the theories of contingency.
+It was their defence of contingency, that is, their lack of any law
+of forms, that caused these theories to be overthrown--reduced to
+absurdities even--and therefore, it follows that to assume any kind of
+transformistic law is at the same time to deny the accidental character
+of the forms of living beings.
+
+There is no *forma accidentalis*. Does that mean that the *forma
+essentialis* is introduced by this mere statement? And what would *that*
+assert about the character of systematics?
+
+
+THE ORGANIC FORM AND ENTELECHY
+
+This problem is not as simple as it might seem to be at the first
+glance, and, in fact, it is insoluble at present. It is here that the
+relation of the hypothetic transformistic principle to our concept of
+entelechy is concerned.
+
+We know that entelechy, though not material in itself, uses material
+means in each individual morphogenesis, handed down by the material
+continuity in inheritance. What then undergoes change in phylogeny,
+the means or the entelechy? And what would be the logical aspect of
+systematics in either case?
+
+Of course there would be a law in systematics in any case; and therefore
+systematics in any case would be rational in principle. But if the
+transformistic factor were connected with the means of morphogenesis,
+one could hardly say that specific form as such was a primary essence.
+Entelechy would be that essence, but entelechy in its generality and
+always remaining the same in its most intimate character, as the
+specific diversities would only be due to a something, which is not
+form, but simply means to form. But the *harmony* revealed to us in
+every typical morphogenesis, be it normal or be it regulatory, seems
+to forbid us to connect transformism with the means of morphogenesis.
+And therefore we shall close this discussion about the most problematic
+phenomena of biology with the declaration, that we regard it as more
+congruent to the general aspect of life to correlate the unknown
+principle concerned in descent with entelechy itself, and not with
+its means. Systematics of organisms therefore would be in fact
+systematics of entelechies, and therefore organic forms would be
+*formae essentiales*, entelechy being the very essence of form in its
+specificity. Of course systematics would then be able to assume a truly
+rational character at some future date: there might one day be found
+a principle to account for the totality of possible[160] forms, a
+principle based upon the analysis of entelechy.[161] As we have allowed
+that Lamarckism hypothetically explains congenital adaptedness in
+histology, and that Darwinism explains a few differences in quantity,
+and as such properties, of course, would both be of a contingent
+character, it follows that our future rational system would be combined
+with certain accidental diversities. And so it might be said to be
+one of the principal tasks of systematic biological science in the
+future to discover the really rational system among a given totality of
+diversities which cannot appear rational at the first glance, one sort
+of differences, so to speak, being superimposed upon the other.
+
+[160] The word “possible” relating to originating, of course, not to
+surviving. It is here that natural selection may acquire its logical
+importance alluded to above (see page 264).
+
+[161] The discussions in the second volume of this book will show the
+possible significance of such an analysis. We at present are dealing
+with entelechy in a quasi-popular manner.
+
+
+
+
+*C.* THE LOGIC OF HISTORY
+
+
+History, in the strictest sense of the word, is the enumeration of the
+things which have followed one another in order of time. History deals
+with the single, with regard both to time and space. Even if its facts
+are complex in themselves and proper to certain other kinds of human
+study, they are nevertheless regarded by history as single. Facts, we
+had better say, so far as they are regarded as single, are regarded
+historically, for what relates to specific time and space is called
+history.
+
+Taken as a simple enumeration or registration, history, of course,
+cannot claim to be a “science” unless we are prepared to denude that
+word of all specific meaning. But that would hardly be useful. As a
+matter of fact, what has actually claimed to be history, has always
+been more than a mere enumeration, even in biology proper. So-called
+phylogeny implies, as we have shown, that every one of its actual
+forms contains some rational elements. Phylogeny always rests on
+the assumption that only some of the characters of the organisms
+were changed in transformism and that what remained unchanged may be
+explained by the fact of inheritance.
+
+But this, remember, was the utmost we were able to say for phylogeny.
+It remains fantastic and for the most part unscientific in spite of
+this small degree of rationality, as to which it is generally not very
+clear itself. For nothing is known with regard to the positive factors
+of transformism, and we were only able to offer the discussion of a few
+possibilities in place of a real theory of the factors of descent.
+
+In spite of that it will not be without a certain logical value to begin
+our analysis of history in general by the discussion of possibilities
+again. Biology proper would hardly allow us to do more: for the
+simple “fact” of history is not even a “fact” in this science, but an
+hypothesis, albeit one of some probability.
+
+As discussions of mere possibilities should always rest on as broad a
+basis as possible, we shall begin our analysis by raising two general
+questions. To what kinds of realities may the concept of history
+reasonably be applied? And what different types of “history” would be
+possible *a priori*, if the word history is to signify more than a mere
+enumeration?
+
+
+1. THE POSSIBLE ASPECTS OF HISTORY
+
+Of course, we could select one definite volume in space and call all the
+consecutive stages which it goes through, its history: it then would be
+part of its history that a cloud was formed in it, or that a bird passed
+through it on the wing. But it would hardly be found very suggestive to
+write the history of space-volumes. In fact, it is to *bodies* in space
+that all history actually relates, at least indirectly, for even the
+history of sciences is in some respect the history of men or of books.
+It may suffice for our analysis to understand here the word body in its
+popular sense.
+
+Now in its relation to bodies history may have the three following
+aspects, as far as anything more than a simple enumeration comes into
+account. Firstly, it may relate to one and the same body, the term
+body again to be understood popularly. So it is when the individual
+history of the organism is traced from the egg to the adult, or when the
+history of a cloud or of an island or of a volcano is written. Secondly,
+the subject-matter of history may be formed by the single units of a
+consecutive series of bodies following each other periodically. To this
+variety of history the discoveries of Mendel and his followers would
+belong in the strictest sense, but so does our hypothetical phylogeny
+and a great part of the history of mankind. And lastly, there is a
+rather complicated kind of sequence of which the “history” has actually
+been written. History can refer to bodies which are in no direct
+relation with one another, but which are each the effect of another body
+that belongs to a consecutive series of body-units showing periodicity.
+This sounds rather complicated; but it is only the strict expression
+of what is perfectly familiar to you all. Our sentence indeed is
+simply part of the definition of a history of art or of literature for
+instance--or, say, of a phylogenetic history of the nests of birds. The
+single pictures are the subjects of the history of art, and nobody would
+deny that these pictures are the effects of their painters, and that
+the painters are individuals of mankind--that is, that they are bodies
+belonging to a consecutive series of body-units showing periodicity. Of
+course, it is only improperly that we speak of a history of pictures or
+of books or of nests. In fact, we are dealing with painters, and with
+men of letters or of science, and with certain birds, and therefore
+the third type of history may be reduced to the second. But it was not
+without value to pursue our logical discrimination as far as possible.
+
+So far we have always spoken of history as being more than a mere
+enumeration, but we have not ascertained what this “more” signifies. It
+is not very difficult to do so: in fact, there are three different types
+of history, each of a different degree of importance with respect to the
+understanding of reality.
+
+In the first place, history may start as a mere enumeration at the
+beginning, and at the end, in spite of all further endeavour, may
+*remain* that and nothing more. That may occur in the first as well
+as in the second group of our division of history with regard to
+its relation to bodies. Take a cloud and describe its history from
+the beginning to the end: there would never be much more than pure
+description. Or take one pair of dogs and describe them and their
+offspring for four generations or more: I doubt if you will get beyond
+mere descriptions in this case either. The only step beyond a mere
+enumeration which we can be said to have advanced in these instances,
+consists in the conviction, gained at the end of the analysis, that
+nothing more than such an enumeration is in any way *possible*.
+
+Quite the opposite happens when “history” deals with the individual
+from the egg to the adult: here the whole series of historical facts is
+seen to form one whole. This case therefore we shall call not history,
+but *evolution*, an evolving of something; the word “evolution” being
+understood here in a much wider sense than on former occasions,[162] and
+*including*, for instance, the embryological alternative “evolutio” or
+“epigenesis.”
+
+[162] See pp. 26, 45, 54, etc.
+
+And half-way between enumeration and evolution there now stands a type
+of history which is more than the one and less than the other: there is
+a kind of intelligible connection between the consecutive historical
+stages and yet the concept of a whole does not come in. The geological
+history of a mountain or of an island is a very clear instance of this
+class. It is easy to see here, how what *has been* always becomes the
+foundation of what *will be* in the *next* phase of the historical
+process. There is a sort of *cumulation* of consecutive phases, the
+later ones being impossible without the earlier. So we shall speak
+of the type of “historical cumulation” as standing between evolution
+and bare temporal sequence. By means of historical cumulations history
+may fairly claim to “explain” things. We “understand” a mountain or an
+island in all its actual characteristics, if we know its history. This
+“historical understanding” rests on the fact that what first appeared
+as an inconceivable complex has been resolved into a sequence of single
+events, each of which may claim to have been explained by actually
+existing sciences. The complex has been explained as being, though not
+a real “whole,” yet a sum of singularities, every element of which is
+familiar.
+
+But you may tell me that my discussion of evolution and of cumulation,
+as the higher aspects of history, is by no means complete; nay,
+more--that it is altogether wrong. You would certainly not be mistaken
+in calling my analysis incomplete. We have called one type of history
+evolution, the other cumulation; but how have these higher types been
+reached? Has historical enumeration itself, which was supposed to
+stand at the beginning of all analysis, or has “history” itself in its
+strictest sense, as relating to the single as such, risen unaided into
+something more than “history”? By no means: history has grown beyond
+its bounds by the aid of something from without. It is unhistorical
+elements that have brought us from mere history to more than history.
+We have created the concept of evolution, not from our knowledge of the
+single line of events attendant on a single egg of a frog, but from our
+knowledge that there are billions or more of frogs’ eggs, all destined
+to the same “history,” which therefore is not history at all. We have
+created the concept of cumulation not from the historical study of
+a single mountain, but from our knowledge of physics and chemistry
+and so-called dynamical geology: by the aid of these sciences we
+“understood” historically, and thus our understanding came from another
+source than history itself.
+
+
+2. PHYLOGENETIC POSSIBILITIES
+
+Does history always gain its importance from what it is not? Must
+history always lose its “historical” aspect, in order to become of
+importance to human knowledge? And can it *always* become “science” by
+such a transformation? We afterwards shall resume this discussion on
+a larger scale, but at present we shall apply what we have learned to
+hypothetic phylogeny. What then are the possibilities of phylogeny, to
+what class of history would it belong if it were complete? Of course, we
+shall not be able to answer this question fully; for phylogeny is *not*
+complete, and scarcely anything is known about the factors which act
+in it. But in spite of that, so much, it seems to me, is gained by our
+analysis of the possible aspects of history and of the factors possibly
+concerned in transformism, that we are at least able to formulate the
+possibilities of a phylogeny of the future in their strict logical
+outlines.
+
+Darwinism and Lamarckism, regarding organic forms as contingent, must
+at the same time regard organic history as a cumulation; they indeed
+*might* claim to furnish an historical explanation in the realm of
+biology--if only their statements were unimpeachable, which as we have
+seen, they are not.
+
+But any transformistic theory, which locates the very principle of
+phylogeny in the organism itself, and to which therefore even organic
+forms would be not accidental but essential, might be forced to regard
+the descent of organisms as a true evolution. The singularities in
+phylogenetic history would thus become links in one whole: history
+proper would become more than history. But I only say that phylogeny
+*might* be evolution, and in fact I cannot admit more than this *a
+priori*, even on the basis of an internal transformistic principle,
+as has been assumed. Such a principle also might lead always from one
+typical state of organisation to the next: but *ad infinitum*.[163]
+Then phylogeny, though containing what might in some sense be called
+“progress,” would not be “evolution”; it might even be called cumulation
+in such a case, in spite of the internal transforming principle, though,
+of course, cumulation from within would always mean something very
+different from cumulation from without.[164]
+
+[163] An immanent vitalistic phylogeny *without* a pre-established end
+has recently been advocated by H. Bergson (*L’évolution créatrice*,
+Paris, 1907).
+
+[164] In this connection the problem may be raised, whether there can be
+such a thing as unchangeable “species” in spite of the mutability of the
+individuals. Compare page 251, note 1.
+
+But we must leave this problem an open question, as long as our actual
+knowledge about transformism remains as poor as it is. We need only add,
+for the sake of logical interest, that phylogeny, as a true evolution,
+would necessarily be characterised by the possibility of being repeated.
+
+
+3. THE HISTORY OF MANKIND
+
+We only assume hypothetically that phylogeny has happened, and we know
+scarcely anything about the factors concerned in it. Now, it certainly
+would be of great importance, if at least in a small and definite field
+of biology we were able to state a little more, if the *mere fact* of
+phylogeny, of “history,” were at least beyond any doubt within a certain
+range of our biological experience. And indeed there is one department
+of knowledge, where history, as we know, *has happened*, and where we
+also know at least some of the factors concerned in it.
+
+I refer to the history of mankind; and I use the expression not at all
+in its anthropological or ethnographical sense, as you might expect
+from a biologist, but in its proper and common sense as the history of
+politics and of laws and of arts, of literature and of sciences: in a
+word, the history of civilisation. Here is the only field, where we know
+that there actually *are* historical facts: let us try to find out what
+these facts can teach us about their succession.
+
+The theory of history in this narrower meaning of the word has been
+the subject of very numerous controversies in the last twenty years,
+especially in Germany, and these controversies have led very deeply into
+the whole philosophical view of the universe. We shall try to treat our
+subject as impartially as possible.
+
+Hegel says, in the introduction to his *Phänomenologie des Geistes*:
+“*Die Philosophie muss sich hüten erbaulich sein zu wollen*”
+(“Philosophy must beware of trying to be edifying”). These words,
+indeed, ought to be inscribed on the lintel of the door that leads
+into historical methodology, for they have been sadly neglected by
+certain theoretical writers. Instead of analysing history in order to
+see what it would yield to philosophy, they have often made philosophy,
+especially moral philosophy, the starting-point of research, and history
+then has had to obey certain doctrines from the very beginning.
+
+We shall try as far as we can not to become “erbaulich” in our
+discussions. We want to learn from history for the purposes of
+philosophy, and we want to learn from history as from a phenomenon in
+time and in space, just as we have learnt from all the other phenomena
+regarding life in nature. Every class of phenomena of course may
+be studied with respect to generalities as well as with respect to
+particulars. The particular, it is true, has not taught us much in our
+studies so far. Perhaps it may be successful in the domain of history
+proper.
+
+If I take into consideration what the best authors of the last century
+have written about human history with respect to its general value, I
+cannot help feeling that none of them has succeeded in assigning to
+history a position where it would really prove to be of great importance
+for the aims of philosophical inquiry. Is that the fault of the authors
+or of human history? And what then would explain the general interest
+which almost every one takes, and which I myself take in history in
+spite of this unsatisfactory state of things?
+
+
+CUMULATIONS IN HUMAN HISTORY
+
+Let us begin our analytical studies of the value and the meaning of
+human history, by considering some opinions which deserve the foremost
+place in our discussion, not as being the first in time, but as being
+the first in simplicity. I refer to the views of men like Buckle, Taine,
+and Lamprecht, and especially Lamprecht, for he has tried the hardest to
+justify theoretically what he regards the only scientific aim of history
+to be. If we may make use of our logical scheme of the three possible
+aspects of history, it is clear from the beginning that the history of
+mankind, as understood by the three authors we have named, but most
+particularly by Lamprecht, is neither a mere enumeration nor a true
+evolution, but that it has to do with *cumulations*, in the clearest
+of their possible forms. The processes of civilisation among the
+different peoples are in fact to be compared logically with the origin
+of volcanoes or mountain-ranges in Japan, or in Italy, or in America,
+and show us a typical series of consecutive phases, as do these. There
+exists, for instance, in the sphere of any single civilisation an
+economic system, founded first on the exchange of natural products,
+and then on money. There are, or better, perhaps, there are said to
+be, characteristic phases succeeding one another in the arts, such as
+the “typical,” the “individualistic,” and the “subjective” phases. Any
+civilisation may be said to have its “middle ages,” and so on. All these
+are “laws” of course in the meaning of “rules” only, for they are far
+from being elemental, they are not “principles” in any sense. And there
+are other sorts of “rules” at work for exceptional cases: revolutions
+have their rules, and imperialism, for instance, has its rules also.
+
+Now, as the consecutive phases of history have been shown to be
+true cumulations, it follows that the rules which are revealed by
+our analysis, are rules relating to the very origin of cumulations
+also. The real *element* upon which the cumulation-phases, and the
+cumulation-rules together rest, is the human individual as the bearer
+of its psychology. Nobody, it seems to me, has shown more clearly than
+Simmel that it is the human individual, *qua* individual, which is
+concerned in *every* kind of history.
+
+History, viewed as a series of cumulations, may in fact claim to
+satisfy the intellect by “explaining” a good deal of historical facts.
+It explains by means of the elemental factor of individual psychology,
+which every one knows from himself, and by the simple concept that there
+is a cumulation, supported by language and by writing as its principal
+factors, which both of course rest on psychology again. Psychology,
+so we may say, is capable of leading to cumulation phenomena; the
+cumulations in history are such that we are able to understand them by
+our everyday psychology; and history, so far as it is of scientific
+value, consists exclusively of cumulations.
+
+No doubt there is much truth in such a conception of history; but
+no doubt also, it puts history in the second rank as compared with
+psychology; just as geology stands in the second rank as compared with
+chemistry or physics. Geology and human history may lead to generalities
+in the form of rules, but these rules are *known* to be not elemental
+but only cumulative; and moreover, we know the elements concerned in
+them. The elements, therefore, are the real subjects for further studies
+in the realm of philosophy, but not the cumulations, not the rules,
+which are known to be due to accidental constellations. Of course, the
+“single” is the immediate subject of this sort of history, but the
+single as such is emphatically pronounced to be insignificant, and the
+cumulations and the cumulative rules, though “singles” in a higher sense
+of the word, are shown to be anything but elementalities.
+
+Therefore, on a conception of human history such as that of Buckle,
+Taine, Lamprecht, and others, we, of course, ought to take an interest
+in history, because what is “explained” by historical research touches
+all of us most personally every day and every year. But our philosophy,
+our view of the world, would remain the same without history as it is
+with it. We only study history, and especially the history of our own
+civilisation, because it is a field of actuality which directly relates
+to ourselves, just as we study for practical purposes the railway
+time-tables of our own country, but not of Australia; just as we study
+the local time-table in particular.
+
+If the mere *rerum cognoscere causas* is regarded as the criterium of
+science, history of Lamprecht’s type of course is a science, for its
+explanations rest upon the demonstration of the typical constellations
+and of the elemental factor or law from which together the next
+constellations are known necessarily to follow. But history of this kind
+is not a science in the sense of discovering *den ruhenden Pol in der
+Erscheinungen Flucht*.
+
+
+HUMAN HISTORY NOT AN “EVOLUTION”
+
+Quite another view of history has been maintained by Hegel, if his
+explanations about the *Entwicklung des objectiven Geistes* (“the
+development of the objective mind”) may be co-ordinated with our
+strictly logical categories of the possible aspects of history. But I
+believe we are entitled to say that it was a real *evolution* of mankind
+that Hegel was thinking of; an evolution regarding mankind as spiritual
+beings and having an end, at least ideally. One psychical state was
+considered by Hegel to generate the next, not as a mere cumulation
+of elemental stages, but in such a way that each of the states would
+represent an elementality and an irreducibility in itself; and he
+assumed that there was a continuous series of such stages of the mind
+through the course of generations. Is there any sufficient reason in
+historical facts for such an assumption?
+
+The mind “evolves” itself from error to truth by what might be called
+a system of contradictions, according to Hegel, with respect to logic
+as well as to morality; the sum of such contradictions becoming smaller
+and less complicated with every single step of this evolution. No doubt
+there really occurs a process of logical and moral refining, so to say,
+in the individual, and no doubt also, the results of this process,
+as far as attained, can be handed down to the next generation by the
+spoken word or by books. But it is by no means clear, I think, that this
+process is of the type of a real evolution towards an end, so far as it
+relates to the actual series of generations as such. On the contrary,
+it seems to me that we have here simply what we meet everywhere in
+history--a sort of cumulation resting upon a psychological basis.
+
+The dissatisfaction that exists at any actual stage of contradiction,
+both moral and logical, is one of the psychical factors concerned;
+the faculty of reasoning is the other. Now it is a consequence of the
+reasoning faculty that the dissatisfaction continually decreases, or
+at least changes in such a way that each partial result of the logical
+process brings with it the statement of new problems. The number of
+such problems may become less, as the logical process advances, and,
+indeed, there is an ideal state, both logical and moral, in which there
+are no more problems, but only results, though this ideal could hardly
+be regarded as attainable by the *human* mind. In the history of those
+sciences which are wholly or chiefly of the *a priori* type, this
+process of deliverance from contradictions is most advantageously to
+be seen. It is obvious in mechanics and thermodynamics, and the theory
+of matter is another very good instance. A certain result is reached;
+much seems to be gained, but suddenly another group of facts presents
+itself, which had been previously unknown or neglected. The first result
+has to be changed or enlarged; many problems of the second order arise;
+there are contradictions among them, which disappear after a certain
+alteration of what was the first fundamental result, and so on. And the
+same is true about morality, though the difficulties are much greater
+here, as a clear and well-marked standard of measurement of what is good
+and what is bad, is wanting, or at least, is not conceded unanimously.
+But even here there is a consensus on some matters: one would hardly go
+back to slavery again, for instance, and there are still other points
+in morality which are claimed as ideals at least by a great majority of
+moral thinkers.
+
+But all this is not true “evolution,” and indeed, I doubt if such an
+evolution of mankind could be proved at present in the sense in which
+Hegel thought it possible. The process of logical and moral deliverance
+from contradictions *might* come to an end in *one* individual; at least
+that is a logical possibility, or it might come to an end in, say,
+six or ten generations. And there is, unfortunately for mankind, no
+guarantee that the result will not be lost again and have to be acquired
+a second time. All this proves that what Hegel regarded as an evolution
+of the race is only a cumulation. There is nothing evolutionary relating
+to the generations of mankind as such. At least, nothing is proved about
+such an evolution.[165]
+
+[165] On account of the limited size of the earth a certain final stage
+of human civilisation might be expected in a future time; but it would
+be the size of the earth which determined this end, and not the process
+of civilisation itself.
+
+You may call my view pessimistic, and indeed you may be right so far
+as the sum total of human beings as such is in question. But, be it
+pessimistic or not, we are here moving on scientific ground only, and
+have merely to study the probability or improbability of problematic
+facts, and with such a view in our mind, we are bound to say that a
+true logical and moral evolution of mankind is not at all supported
+by known facts. There is a process of logical and moral perfection,
+but this process is *not one*, is not “single” in its actuality; it is
+not connected with the one and single line of history, but only with a
+few generations each time it occurs, or even with one individual, at
+least ideally. And this process is not less a process of cumulation
+than any other sort of development or so-called “progress” in history
+is. Philosophers of the Middle Ages, in fact, sometimes regarded human
+history as *one* evolutionary unity, beginning with the Creation and
+ending with the Day of Judgment; but every one must agree, I think,
+that even under the dogmatic assumptions of orthodoxy history would by
+no means *necessarily* be an “evolution.” Even then the paths taken by
+different individuals or different branches of the human race on their
+way to redemption *can* be regarded as independent lines.
+
+Thus Hegel’s conception of an evolution of mankind, it seems to me,
+fails to stand criticism. By emphasising that there are certain lines of
+development in history which bring with them a stimulus to perfection,
+and that these lines relate to all that is highest in culture, Hegel
+certainly rendered the most important service to the theory of history;
+but in spite of that he has revealed to us only a special and typical
+kind of cumulation process, and nothing like an evolution. We may say
+that the very essence of history lies in this sort of cumulation, in
+this “pseudo-evolution” as we might say; and if we like to become moral
+metaphysicians we might add, that it is for the sake of the possibility
+of this sort of cumulation that man lives his earthly life; the Hindoos
+say so, indeed, and so do many Christians. But even if we were to depart
+from our scientific basis in this way we should not get beyond the realm
+of cumulations.
+
+All this, of course, is not to be understood to affirm that there never
+*will* be discovered any real evolutionary element in human history--in
+the so-called “subconscious” sphere perhaps--but at present we
+certainly are ignorant of such an element.
+
+
+THE PROBLEM OF THE “SINGLE” AS SUCH
+
+If history has failed to appear as a true evolution, and if, on the
+other hand, it reveals to us a great sum of different cumulations, some
+of very great importance, others of minor importance, what then remains
+of the importance of the single historical event in its very singleness?
+What importance can the description of this event have with regard to
+our scientific aims? We could hardly say at present that it appears to
+be of very much importance at all. The historical process as a whole
+has proved to be not a real elemental unit, as far as we know, and such
+elemental units as there are in it have proved to be of importance only
+*for* individual psychology but not *as* history. History has offered
+us only instances of what every psychologist knew already from his own
+experience, or at least might have known if he had conceived his task in
+the widest possible spirit.
+
+But is no other way left by which true history might show its real
+importance in spite of all our former analysis? Can history be saved
+perhaps to philosophical science by any new sort of reasoning which we
+have not yet applied to it here.
+
+As a matter of fact, such new reasoning has been tried, and
+Rickert,[166] in particular, has laid much stress upon the point
+that natural sciences have to do with generalities, while historical
+sciences have to do with the single in its singleness only, and, in
+spite of that, are of the highest philosophical importance. He does not
+think very highly of so-called “historical laws,” which must be mere
+borrowings from psychology or biology, applied to history proper, and
+not touching its character as “history.” We agree with these statements
+to a considerable extent. But what then about “history proper,” what
+about “the single in its very singleness”?
+
+[166] *Die Grenzen der naturwissenschaftlichen Begriffsbildung*,
+Tübingen and Leipzig, 1902.
+
+Let us say at first a few words about this term “single” so very often
+applied by us. In the ultimate meaning of the word, of course, the
+series of actual sensations or “presentations” is the “single” which is
+given “historically” to each individual, and therefore to the writer of
+history also, and in fact, history as understood by Rickert is based
+to a great extent upon this primordial meaning of single “givenness.”
+The word “single,” in his opinion, relates to the *actual and true
+specification* of any event, or group of events, at a given time and
+at a given locality in space, these events possessing an identity of
+their own and never being repeated without change of identity. If the
+subject-matter of history is defined like this, then there are, indeed,
+“Grenzen der naturwissenschaftlichen Begriffsbildung” with regard to
+history, for natural sciences have nothing to do with the single in such
+an understanding of the word.
+
+Rickert says somewhere that history as a real evolution, as one
+totality of a higher order, would cease to be proper history: and he
+is right. History, in fact, would soon lose the character of specific
+attachment to a given space and to a given time, and would lose its
+“non-repeatability,” in the logical sense at least, if it were one
+*unit* in reality: as soon as it was that, it would have become a
+logical generality, an element in nature, so to say, in spite of its
+factual singularity. But history is not obliged to become that, Rickert
+states; and we may add that history in fact cannot become that, because
+it simply proves not to be an evolution as far as we know at present.
+
+But what importance does Rickert attach to his history specified and
+non-repeatably single?
+
+History has a logic of its own, he says; the scheme of its logic is not
+the syllogism, but the *relation to “values.”* So far as the single
+historical facts can be related to values, they are of historical
+importance, and in such a way only does history in its proper sense
+become important in itself and through itself at the same time. Must
+history always lose its historical aspect to become of importance to
+human knowledge? That is the question we asked whilst considering the
+general logical types of the “evolution” and “cumulation” that arose out
+of the analysis of the historical facts of problematic phylogeny. It
+now might seem that this question may be answered, and that it may be
+answered by a clear and simple “No.” The history of mankind, according
+to Rickert, seems to be important in itself, and without borrowing from
+any other branch of study. But is his reasoning altogether cogent and
+convincing?
+
+Has it really been able to attribute to history in the strictest sense
+such an importance for philosophy, for the theory of the universe, “für
+die Weltanschauung,” that history proper may in fact be allowed to take
+its place beside science proper?
+
+The relation to values is not to include any kind of “Bewertung” of
+judgment, Rickert allows. In fact, history of any kind would hardly
+satisfy the reader, if moral judgment were its basis. Every reader, of
+course, has a moral judgment of his own, but, unfortunately, almost
+every reader’s judgment is different from his neighbour’s, and there
+is no uniformity of moral principles as there is of geometrical ones.
+We shall come back to this point. At present we only state the fact
+that indeed moral judgment can never be the foundation of history, and
+that Rickert was very right to say so: it is enough to put the names
+of Tolstoy and Nietzsche together to understand how devoid of even
+the smallest general validity would be a history resting upon moral
+principles.
+
+But what then are the “values” of Rickert to which history has to
+relate, if moral values in their proper sense have to be excluded? It is
+here that his discussions begin to become obscure and unsatisfactory,
+and the reason is fairly intelligible. He is trying to prove the
+impossible; he wants to put history beside science in its real
+philosophical importance, in spite of the fact that all evidence to
+establish this is wanting.
+
+These “values,” to which every historical act in its singularity has to
+be related in order to become an element of real history, are they after
+all nothing but those groups of the products of civilisation which in
+fact absorb the interest of men? Is it to groups of cultural phenomena,
+such as arts, science, the State, religion, war, economics, and so on,
+that “historical” facts have to be related? Yes, as far as I understand
+our author, it is simply to these or other even less important groups
+of cultural effects--cultural “cumulations,” to apply our term--that a
+single action of a man or a group of men must bear some relation in
+order to become important historically.
+
+But what does that mean? Is the relation to such “values” to be
+regarded as really rendering history equal to the sciences of nature in
+philosophical importance?
+
+In the first place, there is no more agreement about such “values” than
+there is in the field of morals. Imagine, for instance, a religious
+enthusiast or recluse writing history! I fancy there would be very
+little mention of warriors and politicians: war and politics would
+not be “values” in *any* sense to such a man. And we know that there
+are others to whom those products of civilised life rank amongst the
+first. Rickert well notes that there is one great objection to his
+doctrine--the character of universality[167] is wanting to his history,
+or rather to the values forming its basis; for there cannot be, or at
+least there actually is not at present, a *consensus omnium* with regard
+to these “values.”
+
+[167] The word “universality” to be understood here in quite an
+unpretentious quasi-popular meaning, not strictly epistemologically.
+
+I am convinced that Rickert is right in his conception of real “history”
+as the knowledge of the single acts of mankind. But this conception
+proves just the contrary of what Rickert hoped to prove; for history in
+this sense is moulded by the actual products of culture, that is, by
+the effects which actually exist as groups of cultural processes, and
+it cannot be moulded by anything else; the historian correlates history
+with what *interests* him personally.
+
+Here now we have met definitively the ambiguous word: history indeed
+is to end in “interest” and in being “interesting.” There is nothing
+like a real “value” in any sense underlying history; the word *value*
+therefore would better give place to the term “centre of interest”--a
+collection of stamps may be such a “centre.” History, then, as the
+knowledge of cultural singularities, is “interesting,” and its aspects
+change with the interests of the person who writes history: there is no
+commonly accepted foundation of history.[168]
+
+[168] To avoid mistakes I wish to say here most emphatically that,
+according to Rickert, the method of history is regarded as completely
+*free* from subjectivity as soon as its “values” are once *established*.
+But this cannot avail to save the theory.
+
+And it follows that history as regarded by Rickert cannot serve as
+the preliminary to philosophy. It *may* be[169] of use for personal
+edification or for practical life: granting that the “centres of
+interest” as referred to are of any real ethical or at least factual
+importance. But you may take away from history even the greatest
+personalities, and your view of the universe, your philosophy, would
+remain the same, except of course so far as these personalities
+themselves have contributed to philosophy in any way.
+
+[169] This is a rather optimistic conception of “history.” Personally, I
+must confess that even its emotional and practical importance seems to
+me to be at least diminished by the retarding effects which all sorts
+of “historical” considerations--in science as well as in arts and in
+public life--carry with them. All real progress is non-historical--and
+its champions almost always have become martyrs: this fact seems not to
+recommend history as a means of education, except for persons of a very
+strong character.
+
+Now, on the other hand, it is worth noticing that, even if there were
+generally accepted “values,” history as the doctrine of singularities
+would be deprived of philosophical importance. Its single cases would
+then be merely *instances* of certain types of actions and occurrences
+which have been proved to be “valuable,” *i.e.* to be centres of
+interest, before-hand. Rickert has observed that the relation to
+any judgments about moral values would render history unhistorical,
+for the generalities to which it is related would be the main thing
+in such a case. But he did not notice, as far as I can see, that
+history, if related to *any* “values” whatever--if there were any
+generally conceded--would become “non-historical” just as well: for the
+*generalities* as expressed in the “values” would be the main thing in
+this case also. In fact, there is no escape from the dilemma:--either no
+general centres of interest, and therefore a mere subjective “history”;
+or general “values,” and therefore history a mere collection of
+instances.
+
+The “limits of concepts in natural sciences” then are the same as the
+limits of *intellectual* concepts in general. For intellectual, *i.e.*
+logical, “values” are the only centres of interest that can lay claim
+to universality. There are indeed other groups of important concepts,
+the ethical ones, but they are outside intellectuality and may enter
+philosophy only as problems, not as solutions. Therefore, history in
+its true sense, even if related to the ethical group of concepts,
+has no bearing on philosophy. Philosophically it remains a sum of
+contingencies, in which certain laws of cumulation and certain series of
+cumulation may be discovered. But these series and these laws, if taken
+scientifically, only offer us instances of psychological elementalities.
+They also might be instances of primary ethical states and relations, if
+there were such relations of more than a mere subjective and personal
+validity, which at present at least seems not to be the case.
+
+
+
+
+CONCLUSIONS ABOUT SYSTEMATICS AND HISTORY IN GENERAL
+
+
+We have finished our analysis of the history of mankind as the only
+instance of an historical biological process that is actually known to
+exist and is not only assumed hypothetically.
+
+What we have learnt from this analysis, though certainly important in
+itself, has not afforded us any new result for theoretical biology.
+
+The history of mankind is proved to be of philosophical importance,
+at present, so far only as it offers instances to the science of
+psychology; besides that it may be of value and importance to many
+conditions of practical and emotional life.
+
+There is only one science, and only one kind of logic too. “In one sense
+the only science”--that was the predicate attached to natural sciences
+by Lord Gifford, as you will remember from our first lecture. It is not
+without interest to note that at the end of our course of this year,
+we find occasion to realise on what a deep insight into logical and
+philosophical relations that sentence was grounded.
+
+We now leave the theory of human history, which has been to us nothing
+more than a branch of biological phylogeny in general. We have dealt
+with it from quite a simple realistic point of view, not burdened by any
+epistemology. We have taken psychical states as realities, just as we
+have taken as realities all parts of the animal body; and it seems to
+me that we were entitled to do so, as it was only history *about* the
+actions of men we were dealing with, not their actions themselves. Next
+summer we shall begin with studying action as action, and then, in fact,
+a well-founded epistemology will be among our first requirements. And
+history also will come on the scene once more.
+
+It is the main result of our last chapters, devoted to systematics,
+transformism, and human history in particular, that no conclusions
+really useful for further philosophical discussion can at present be
+gained from these topics; there either is too little actual knowledge,
+or there are only combinations of natural elementalities, but no
+elementalities of any new kind.
+
+To sum up: we expected that a rational system might be a biological
+result of the future, but we could not claim at all to possess such a
+system. We said that transformism might be proved one day to be a true
+evolution, governed by one immanent principle, which then would have to
+be regarded as a new primary factor in nature, but we did not know the
+least about that principle.
+
+Human history, on the other hand--that is, the only historical process
+concerned with life that is actually known to have occurred--could not
+teach us anything of an elemental character, since human history, at
+present at least, did not appear to us as a true evolution, but only as
+a sum of cumulations, and the singularities of this history, taken by
+themselves, could only be of practical or emotional interest.
+
+Thus it is from the study of the living *individual* only, that we
+have so far gained elemental principles in biology. The analysis of
+individual morphogenesis and of individual inheritance has yielded
+us the concept of entelechy as the chief result of the first part of
+our lectures. We shall be able to get more proofs of the autonomy of
+the individual life in the beginning of the second part; indeed, the
+beginning of that part will bring us to a full understanding of what the
+living individual is, and what it is not. And then the real philosophy
+of life, that is, the philosophy of the individual, will occupy us for
+the greater half of our lectures of next summer.
+
+
+
+
+INDEX
+
+
+  Absolute, 5
+
+  Acclimatisation, 191
+
+  Acquired characters, 217, 276 f.
+
+  Adaptation (definition), 166, 171, 185
+    to changes from without, 172 ff.
+    functional, 114, 176 ff.
+    and Lamarckism, 272, 280
+    mechanical, 177 f.
+    morphological, 168 ff.
+    physiological, 184 ff.
+    primary and secondary, 188 f.
+
+  Adaptedness, 186 f.
+
+  *Adiantum*, 279
+
+  Adventitious, 55, 74, 111, 221
+
+  Albumen, 200
+
+  Allelomorphs, 231
+
+  Amphibious plants, 172 ff.
+
+  Annelids, 65, 70, 221
+
+  Answering reaction, 181
+
+  Anti-bodies, 206 f.
+
+  Antitoxins, 207 f.
+
+  *A priori*, 6
+
+  Aristotle, 144
+
+  *Ascaris*, 93
+
+  *Aspergillus*, 195
+
+  Assimilation, 17
+
+  Atrophy, 178
+
+  Autonomy of life, 143, 224 f., 324
+
+
+  Babák, 177
+
+  Baer, C. E. v., 48 f. 282
+
+  Bateson, 229 ff., 238
+
+  Bayliss, 204, 212
+
+  *Begonia*, 221
+
+  Bergson, 305
+
+  Berkeley, 6
+
+  Berthold, 91
+
+  Biogenetisches Grundgesetz, 248
+
+  Biology, 8 ff., 15 f.
+
+  Blaringhem, 238, 276
+
+  Blastoderm, 39
+
+  Blastomeres, 36, 59, 61 f., 79
+
+  Blastula, 37, 61, 79
+
+  Blumenbach, 26
+
+  Boirivant, 174
+
+  Bonnet, 26
+
+  Boveri, 29, 60, 95, 235 f.
+
+  Buckle, 308, 310
+
+  Bunge, v., 248
+
+  Bütschli, 91
+
+
+  Calcium, 97
+
+  Calkins, 33
+
+  Cambium, 120, 183, 220
+
+  Catalysis, 164, 203
+
+  Categories, 6 f.
+
+  Cause, 99 ff.
+
+  Cell, 27 f.
+    -division, 28 ff., 53, 94
+    -lineage, 58, 70
+    -theory, 27 f.
+
+  Chemical theory (of morphogenesis), 134 ff.
+
+  Chemistry, systematics of, 244.
+
+  Child, C. M., 180
+
+  Chromatic regulations, 197
+
+  Chromatin, 28 f.
+
+  Chromosomes, 30, 237
+
+  Chun, 66
+
+  Classification, 246 f.
+
+  *Clavellina*, 129, 154, 162 f.
+
+  Cleavage, 35 ff., 53, 58, 60, 63, 71, 92
+
+  Colloids, 187
+
+  Compensatory process, 112
+
+  Complex potencies, 112, 120
+
+  Conic sections, 243
+
+  Conjugation, 33
+
+  Conklin, 86
+
+  Contingency, 218, 284 ff. 304
+
+  Continuity of germ-plasm, 215, 227
+
+  Cope, 273
+
+  Correlation (of masses), 93
+    (of parts), 247
+
+  Correns, 228
+
+  Crampton, 70 f.
+
+  Crayfish, 105
+
+  Ctenophores, 66
+
+  Cumulation, 301 ff., 308 ff., 314, 317
+
+  Cuvier, 247
+
+
+  Darwin, Ch., 260 ff., 271, 283
+
+  Darwinism, 260 ff., 271, 283 ff., 293 ff., 304
+
+  Davenport, 191, 206
+
+  Delage, 32
+
+  Descent, theory of, 250 ff.
+
+  Description, 12, 50
+
+  Detto, 172
+
+  Directive stimuli, 102 ff.
+
+  Doncaster, 232
+
+  Dreyer, 92
+
+
+  *Echinus*, 27, 33 ff., 60 ff., 68, 81, 85, 87,
+    98, 104, 108, 111, 154, 232, 235
+
+  Ectoderm, 41, 81, 122
+
+  Egg, 31, 33 f.
+
+  Ehrlich, 207 f.
+
+  Eimer, 292
+
+  Elementary organs, 46 ff.
+    processes, 46 ff.
+
+  Elements of nature, 9
+
+  Embryo, 44
+    frog’s, 59, 65, 67
+    half, 59, 61, 66 ff.
+    whole, 61, 67 f.
+
+  Endoderm, 41, 81
+
+  Entelechy, 143 f., 224 f., 295
+
+  Entwickelungsmechanik, 57, 70, 78, 241
+
+  Enumeration, 297, 300
+
+  Enzymes, 164, 203
+
+  Epigenesis, 26, 45, 54, 72, 144, 301
+
+  Equifinality (of restitutions), 159 f.
+
+  Equipotential, 83
+
+  Eschenhagen, 195
+
+  Evolutio, 26, 45 f., 54, 59, 61, 64, 72, 144, 205, 301
+
+  Evolution, 8, 21, 46, 250, 301, 305, 311 ff., 317
+
+  Experience, 7 f., 12, 212
+
+  Experiment, 51, 56 f.
+
+  “Explaining,” 51, 309
+
+  Explicit potency, 84
+
+
+  Fasting, 199 f.
+
+  Ferments, 164, 203 f.
+
+  Fertilisation, 32 ff.
+
+  Fischer, 278
+
+  Foges, 107
+
+  Form, closed or open, 49
+
+  Form, organic, specific, 16 ff., 25, 92, 293 ff.
+
+  Forma accidentalis, 293
+    essentialis, 294 f.
+
+  Formative stimuli, 102 ff., 113, 118, 133
+
+  Francé, 158, 239
+
+  Frédéricq, 196
+
+  Frog, embryo of, 59, 65, 67
+
+  Fromm, 205
+
+  Function (mathematical), 80
+
+  Fungi, metabolism of, 201
+
+
+  Gaidukow, 197 f.
+
+  Galls, 101
+
+  Galton, 228, 238
+
+  Gamble and Keeble, 198
+
+  Gastrula, 41, 61, 81
+
+  Gautier, 239
+
+  Geographical distribution, 251 f.
+
+  Geometry, solid, 243
+
+  Germ-layers, 41, 44, 61
+    -lineage, 215
+    -plasm, 52, 215
+
+  Gifford, Lord, 1 ff., 322
+
+  Godlewski, 105, 155, 235
+
+  Goebel, 116
+
+  Goethe, 247
+
+  Goette, 48, 56, 214
+
+  Goltz, 181
+
+  Growth, 30, 93 f.
+
+  Gruber, 236
+
+
+  Haeckel, 37, 41
+
+  Half-embryo, 59, 61, 66 ff.
+
+  Haller, A. v., 26
+
+  Harmony, 107 ff., 117, 295
+
+  Hausmann, 206
+
+  Heat production, 193
+
+  Hegel, 307, 311 ff.
+
+  Herbst, 96 ff., 102, 104 ff., 172, 177, 200, 232, 236
+
+  Heredity, 21, 52
+
+  Hering, 216 f.
+
+  Hertwig, O., 60, 65
+
+  Hertwig, R., 32 f., 60, 107
+
+  His, 56, 93
+
+  History, 2, 14, 21, 250, 257, 297 ff.
+    of mankind, 306 ff.
+
+  Holmes, 180
+
+  Hume, 6
+
+  Hypertrophy, 112, 114
+
+  Hypertypy, 112
+
+
+  Idealism, 5, 7
+
+  Immunity, 204 ff.
+
+  Implicit potency, 84
+
+  Improvement (of morphogenesis), 212
+
+  Indifferent cells, 182
+
+  Inflammation, 206
+
+  Inheritance, 35, 214 ff.
+    of acquired characters, 217, 275 ff., 290
+
+  Irritability, 190 ff.
+
+
+  Jacoby, 207
+
+  Jaeger, 214
+
+  Jennings, 218
+
+
+  Kammerer, 176, 280
+
+  Kant, 6 f.
+
+  Kirchhoff, 50
+
+  Klebs, 96, 170, 180, 238, 276
+
+  Kölliker, 292
+
+  Korshinsky, 239
+
+  Krašan, 221, 251
+
+
+  Lamarck, 271 f., 291
+
+  Lamarckism, 271 f., 284 ff., 293 ff., 304
+
+  Lamprecht, 308, 310
+
+  Larva, 41 f., 44
+
+  Law of nature, 13, 16
+
+  Leibniz, 6
+
+  Lens (of eye), 105, 221
+
+  Liebmann, 256
+
+  Life, 9 f., 16, 21
+
+  Lillie, R. S., 236
+
+  Limits of regulability, 212
+
+  Lithium, 99
+
+  “Living,” 9, 16
+
+  Localisation, 101, 103, 118 ff.
+
+  Locke, 6
+
+  Loeb, J., 32, 102, 164, 179, 196, 236
+
+  Loeb, L., 208
+
+  Lyon, 87
+
+
+  MacDougal, 238 f., 276
+
+  Machine (definition), 139
+
+  Machine-theory of life, 138 ff., 187, 210
+
+  Maillard, 196
+
+  Manifoldness, 25 f., 30, 45
+    intensive, 144
+
+  Materialism, 283
+
+  Materials, transport of, 194
+
+  Matter, theory of, 8
+
+  Maturation, 31, 87
+
+  Mayenburg, v., 195
+
+  Means, of morphogenesis, 89 ff., 101, 113, 118, 228, 234
+
+  Memory, 216 f.
+
+  Mendel, 229 f.
+
+  Merrifield, 198
+
+  Mesenchyme, 39, 41, 104, 111, 151 f.
+
+  Metabolic regulations, 198 f.
+
+  Metabolism, 16, 184
+    of fungi, 201
+
+  Metschnikoff, 206
+
+  Micromeres, 36, 60
+
+  Miehe, 116
+
+  Mill, J. S., 57
+
+  *Mimosa*, 191
+
+  Minkiewicz, 198
+
+  Modification, 277
+
+  Molluscs, 70 f., 86
+
+  Morgan, T. H., 32, 66 f., 95, 107, 114 f., 162, 230
+
+  Morphaesthesia, 157
+
+  Morphogenesis, 20, 52, 76, 112, 118 f.
+
+  Morphology, 12
+
+  Movements, organic, 17
+
+  Mutations, 237 f., 276, 291
+
+
+  Nägeli, 266, 292
+
+  Nathansohn, 196
+
+  Natural selection, 261 f., 290
+
+  Nature, 5 ff.
+
+  Němec, 116
+
+  Newport, 57
+
+  Newt (regeneration of), 155, 221 f.
+
+  Noll, 146, 157 f.
+
+  Nomothetic, 14 f.
+
+  Normal, 78
+
+  Nuclear division, 28 f., 62, 64 f., 72, 235
+
+  Nucleus, 28, 35
+    rôle of nucleus in inheritance, 233 f.
+
+
+  Organ-forming substances, 117
+
+  *Oscillariae*, 197
+
+  Osmotic pressure, 93, 187, 194 f.
+
+  Overton, 196 f.
+
+  Oxidation, rôle of, 198 f.
+
+
+  Palaeontology, 252
+
+  Parallelism (psycho-physical), 146
+
+  Parthenogenesis, 32
+
+  Pauly, 146, 217, 273 f.
+
+  Pawlow, 204, 210, 212
+
+  Pearl, R., 212
+
+  Pfeffer, 195, 201
+
+  Phagocytosis, 206
+
+  Phenomenon, 5 f.
+
+  Philosophy, natural, 4
+    of nature, 4, 7, 9
+    of the organism, 9, 15
+
+  Phylogeny, 255, 291, 297, 304 ff.
+
+  Physiology, 12
+    of development (morphogenesis), 20
+
+  *Planaria*, 130, 155, 162 f., 200
+
+  Plants, 48 f.
+
+  Plato, 2
+
+  Pluteus, 42
+
+  Poisons, 205 ff.
+
+  Pole, 36
+
+  Polarity, 106
+
+  Potencies, complex, 112, 120
+    explicit, 84
+    implicit, 84
+    primary, 84, 111
+    prospective, 77 ff., 83, 89, 118, 125, 241
+    secondary, 84, 110
+
+  Poulton, 198
+
+  Precipitin, 207 f.
+
+  Pressure experiments, 63, 141
+
+  Primary potency, 84, 111
+    purposefulness, 146, 287
+    regulation, 85, 174, 188
+
+  Progress, 305
+
+  Pronuclei, 55
+
+  Prospective potency, 77 ff., 83, 89, 118, 125, 241
+    value, 77 f., 80, 122
+
+  Protista (Protozoa), 27, 130, 236
+
+  Protoplasm, 28, 30
+    morphogenetic rôle of, 67
+
+  Przibram, 112, 248
+
+
+  Rádl, 247
+
+  Rauber, 235
+
+  Reaction, answering, 181
+
+  Reciprocity of harmony, 156 f.
+
+  Re-differentiation, 75, 111, 163
+
+  Regeneration, 55, 74, 105, 111, 221
+    super-, 115 f.
+
+  Regulation, 68, 73, 85, 111, 165
+    defined, 166
+    metabolic, 198 f.
+    secondary, 85, 165, 188
+
+  Reinke, 146
+
+  Restitution, 21, 74, 110, 112 ff.
+    defined, 166
+    and Darwinism, 267
+    and Lamarckism, 286
+    of second order, 158
+
+  Retina, 191
+
+  Retro-differentiation, 163 f.
+
+  Rhumbler, 93
+
+  Ribbert, 114
+
+  Rickert, 315 ff.
+
+  Roux, 26, 48, 55 ff., 66 f., 76, 89, 92 f., 108, 161, 176 f., 241
+
+  Rubner, 193
+
+
+  Sachs, 117
+
+  Sadebeck, 279
+
+  *Salamandra*, 175, 281
+
+  Schneider, 146
+
+  Schultz, E., 200
+
+  Schultze, O., 67
+
+  Schwendener, 177
+
+  Science, 14, 297
+    natural, 1 ff.
+    rational, 12
+
+  Sea-urchin, *see* Echinus
+
+  Secondary potency, 84, 110
+    regulation, 85, 165, 188
+
+  Secretion, internal, 116, 200
+
+  Segmentation, 35
+
+  Selective qualities (of tissues), 186
+
+  Self-differentiation, 108
+
+  Semon, 216 f.
+
+  Sex, 107
+
+  Single, the, 315 ff.
+
+  Skeleton, 40 ff., 44, 47, 92
+
+  Spemann, 105
+
+  Spermatozoon (spermia), 32 ff.
+
+  Splitting (of hybrids), 229 f.
+
+  Stahl, 197
+
+  Standfuss, 278
+
+  Starfish, 44, 81, 122
+
+  Starling, E., 116, 204, 212
+
+  *Stentor*, 131
+
+  Stimuli, directive, 102 ff.
+    formative, 102 ff., 113, 118, 133
+    of restitutions, 113 f.
+
+  Structure of protoplasm, 66, 69, 72 f. 85, 88
+
+  Substance, living, 17
+
+  Sumner, 196
+
+  Super-regeneration, 115 f.
+
+  Surface-tension, 91
+
+  Sutton, 230
+
+  Symmetry, 39, 68, 70, 72, 89, 98
+
+  System, combined types of, 153 ff.
+    complex, 219 f.
+    complex-harmonious, 155
+    equipotential, 120
+    harmonious-equipotential, 121 ff., 151 f.
+    mixed-equipotential, 154
+    morphogenetic, 119 f., 163, 241
+
+  Systematics, 14 ff., 21, 243 f., 253, 264, 293, 296
+
+
+  Taine, 308, 310
+
+  Theology, natural, 1 ff.
+
+  Thomson, J. A., 16
+
+  Thymus, 204
+
+  Thyroid, 204
+
+  Tissue, 38
+
+  Toxins, 207 f.
+
+  Transformism, 251
+
+  Truth, 7
+
+  Tschermak, 228
+
+  *Tubularia*, 126 ff., 133, 158 ff.
+
+  Type, 48, 247 f., 282, 291
+
+
+  “Understanding” (historically), 302
+
+  Universality, postulate of, 148 f.
+
+  Universe, 5
+
+  Univocality, principle of, 161
+
+
+  “Values,” 317 ff.
+    prospective, 77 f., 80, 122
+
+  Variation, 218, 237 f., 276
+
+  Variation, fluctuating, contingent, 264 f., 273 f., 282, 290
+
+  Vernon, 232, 238
+
+  Vitalism, 143, 145 f., 210 f., 224 f., 234, 240 f., 272, 277
+
+  Vöchting, 174, 179 f., 182, 221
+
+  Volition, acts of, 274
+
+  Vries, de, 228, 238 f.
+
+
+  Wallace, 292
+
+  Ward, J., 8, 143
+
+  Weber, law of, 191
+
+  Weinland, 202
+
+  Weismann, 33, 52 ff., 58 f., 72, 74 f., 103,
+    111, 138, 214 f., 237, 277 f.
+
+  Weldon, 238
+
+  Whole, the, 28, 80, 117
+    -embryo, 61, 67 f.
+
+  Wigand, 255, 266, 292
+
+  Wilson, E. B., 27, 65, 70 f., 86 f., 107
+
+  Windelband, 13 f.
+
+  Winkler, 116, 221
+
+  Winterstein, 199
+
+  Wolff, C. F., 26
+
+  Wolff, G., 105, 146, 255, 266, 287 f.
+
+  Wolff, J., 177
+
+
+  Yung, 177
+
+
+  Zeleny, 112, 115, 212
+
+  Zur Strassen, 93
+
+
+                                THE END
+
+           *Printed by* R. & R. CLARK, LIMITED, *Edinburgh*.
+
+
+
+
+                         HEREDITY AND SELECTION
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+<pre>
+
+The Project Gutenberg EBook of The Science and Philosophy of the Organism, by 
+Hans Driesch
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Science and Philosophy of the Organism
+       The Gifford Lectures Delivered Before the University of
+              Aberdeen in the Year 1907
+
+Author: Hans Driesch
+
+Release Date: December 8, 2013 [EBook #44388]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE SCIENCE AND PHILOSOPHY ***
+
+
+
+
+Produced by Marilynda Fraser-Cunliffe, Thiers Halliwell
+and the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+<div class="transnote"><p><b>Transcriber&rsquo;s notes</b>:</p>
+
+<p>In this transcription, page numbers are shown in the right
+margin, and page footnotes (renumbered in consecutive order) are
+grouped together at the end of the book. Hyperlinks to footnotes
+and page references are indicated by black dotted underlines plus
+aqua highlighting when the mouse pointer hovers over them. The
+footnotes are themselves hyperlinked back to the originating marker
+to facilitate easy return to the text. A red dashed underline as
+shown <ins title="Comment">here</ins> indicates the presence of a
+transcriber&rsquo;s comment; scrolling the mouse pointer over such text
+will reveal the comment.</p>
+
+<p>The rare spelling typos noted in the original text have
+been corrected silently (e.g. invividual-->individual,
+hyberbola-->hyperbola) but inconsistent use of the ligature æ/ae (e.g.
+palæontology/palaeontology), inconsistent use of alternative spellings
+(e.g. learned/learnt), and occasional inconsistencies of hyphenation
+have been left as in the original. Minor punctuation typos have been
+corrected silently (e.g. index entries with missing commas). The
+abbreviation viz. appears in both roman and italic font.</p>
+
+<p>Formatting of entries in the Table of Contents does not accurately
+match that of the corresponding headings in the text, particularly the
+heading Pt.I-B-3 which contains an extraneous α.</p>
+
+<p>In Figure 12 caption, multiple ditto marks have been replaced by the
+relevant text for greater clarity.</p>
+
+</div>
+
+
+<p><span class="pagenum hide" title="i"><a name="Page_i" id="Page_i"></a></span></p>
+
+<p class="tac fs160 mt15em mb2em">THE SCIENCE AND PHILOSOPHY<br />
+OF THE ORGANISM</p>
+<p><span class="pagenum hide" title="ii"><a name="Page_ii" id="Page_ii"></a></span></p>
+
+<table class="fs65 mb2em" border="0" cellpadding="4" cellspacing="0" summary="International addresses of publisher">
+<col width="30%" /><col width="70%" />
+<tr><td class="tac" colspan="2">AGENTS</td></tr>
+<tr class="vat"><td><span class="smcap">America</span></td><td><span class="smcap">The Macmillan Company<br />64 &amp; 66 Fifth Avenue, New York</span></td></tr>
+<tr class="vat"><td><span class="smcap">Australasia</span></td><td><span class="smcap">The Oxford University Press, Melbourne</span></td></tr>
+<tr class="vat"><td><span class="smcap">Canada</span></td><td><span class="smcap">The Macmillan Company of Canada, Ltd.<br />27 Richmond Street West, Toronto</span></td></tr>
+<tr class="vat"><td><span class="smcap">India</span></td><td><span class="smcap">Macmillan &amp; Company, Ltd.<br />Macmillan Building, Bombay<br />309 Bow Bazaar Street, Calcutta</span></td></tr>
+</table>
+<p><span class="pagenum hide" title="iii"><a name="Page_iii" id="Page_iii"></a></span></p>
+
+
+<h1 class="lh150 mt15em"><span class="fs65">THE</span><br />
+SCIENCE AND PHILOSOPHY<br />
+OF THE ORGANISM</h1>
+
+<p class="tac ls01em mb2em lh150">THE GIFFORD LECTURES DELIVERED BEFORE<br />
+THE UNIVERSITY OF ABERDEEN<br />
+IN THE YEAR 1907<br /><br /></p>
+
+<p class="tac"><span class="fs85 lh300">BY</span><br />
+<span class="fs120">HANS DRIESCH, <span class="smcap">Ph.D.</span></span><br />
+<span class="fs50">HEIDELBERG</span><br /><br /><br /><br />
+<span class="figcenter" style="width: 321px;">
+<img id="logo" src="images/logo.png" width="53" height="52" alt="" /></span>
+<br /><br /><br /></p>
+
+
+<p class="tac ls01em mb2em lh150">LONDON<br />
+ADAM AND CHARLES BLACK<br />
+1908</p>
+
+<p class="tac fs65"><em>All rights reserved</em></p>
+<hr class="short" />
+<p><span class="pagenum hide" title="iv"><a name="Page_iv" id="Page_iv"></a></span><br /><span class="pagenum" title="v"><a name="Page_v" id="Page_v"></a></span></p>
+
+
+
+
+<h2>PREFACE</h2>
+
+
+<p>This work is not a text-book of theoretical biology; it is a
+systematic presentment of those biological topics which bear
+upon the true philosophy of nature. The book is written
+in a decidedly subjective manner, and it seems to me that
+this is just what “Gifford Lectures” ought to be. They
+ought never to lose, or even try to lose, their decidedly
+personal character.</p>
+
+<p>My appointment as Gifford Lecturer, the news of which
+reached me in February 1906, came just at the right
+moment in the progress of my theoretical studies. I had
+always tried to improve my previous books by adding notes
+or altering the arrangement; I also had left a good deal
+of things unpublished, and thus I often hoped that I might
+have occasion to arrange for a new, improved, and enlarged
+edition of those books. This work then is the realisation
+of my hopes; it is, in its way, a definitive statement of all
+that I have to say about the Organic.</p>
+
+<p>The first volume of this work, containing the lectures
+for 1907&mdash;though the division into “lectures” has not been
+preserved&mdash;consists of Parts I. and II. of Section A, “The
+Chief Results of Analytical Biology.” It gives in Part I. a<span class="pagenum" title="vi"><a name="Page_vi" id="Page_vi"></a></span>
+shortened, revised, and, as I hope, improved account of what
+was published in my <cite lang="de" xml:lang="de">Analytische Theorie der organischen
+Entwickelung</cite> (1894), <cite lang="de" xml:lang="de">Die Localisation morphogenetischer
+Vorgänge; ein Beweis Vitalistischen Geschehens</cite> (1899), and
+<cite lang="de" xml:lang="de">Die organischen Regulationen</cite> (1901), though for the professed
+biologist the two last-named books are by no means
+superseded by the new work. Part II. has never been
+published in any systematic form before, though there are
+many remarks on Systematics, Darwinism, etc., in my
+previous papers.</p>
+
+<p>The second volume&mdash;to be published in the autumn,
+after the delivery of the 1908 lectures&mdash;will begin with
+the third and concluding part of the scientific section, which
+is a very carefully revised and rearranged second edition of
+my book, <cite lang="de" xml:lang="de">Die “Seele” als elementarer Naturfactor</cite> (1903).
+The greater part of this volume, however, will be devoted
+to the “Philosophy of the Organism,” <i>i.e.</i> Section B, which, in
+my opinion, includes the most important parts of the work.</p>
+
+<p>Some apology is needed for my presuming to write in
+English. I was led to do so by the conviction, mistaken
+perhaps, that the process of translation would rob the
+lectures of that individual and personal character which, as
+I said before, seems to me so much to be desired. I wished
+nothing to come between me and my audience. I accordingly
+wrote my manuscript in English, and then submitted
+it to linguistic revision by such skilled aid as I was able to
+procure at Heidelberg. My reviser tells me that if the
+result of his labours leaves much to be desired, it is not to
+be wondered at, but that, being neither a biologist nor a<span class="pagenum" title="vii"><a name="Page_vii" id="Page_vii"></a></span>
+philosopher, he has done his best to make me presentable
+to the English reader. If he has failed in his troublesome
+task, I know that it is not for want of care and attention,
+and I desire here to record my sense of indebtedness to him.
+He wishes to remain anonymous, but I am permitted to say
+that, though resident in a foreign university, he is of
+Scottish name and English birth.</p>
+
+<p>My gratitude to my friends at Aberdeen, in particular
+to Professor and Mrs. J. A. Thomson, for their hospitality
+and great kindness towards me cannot be expressed here;
+they all know that they succeeded in making me feel quite
+at home with them.</p>
+
+<p>I am very much obliged to my publishers, Messrs.
+A. and C. Black, for their readiness to fulfil all my wishes
+with respect to publication.</p>
+
+
+<p>The lectures contained in this book were written in
+English by a German and delivered at a Scottish university.
+Almost all of the ideas discussed in it were first conceived
+during the author’s long residence in Southern Italy. Thus
+this book may be witness to the truth which, I hope, will
+be universally recognised in the near future&mdash;that all
+culture, moral and intellectual and aesthetic, is not limited
+by the bounds of nationality.</p>
+
+<p class="tar mr2em">HANS DRIESCH.<br /><br /></p>
+
+<p><span class="smcap fs85">Heidelberg</span>, <i>2nd January 1908</i>.<br /></p>
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="viii"><a name="Page_viii" id="Page_viii"></a></span><br /><span class="pagenum" title="ix"><a name="Page_ix" id="Page_ix"></a></span></p>
+
+
+
+<h2>CONTENTS OF THE FIRST VOLUME</h2>
+
+<p class="tac">THE PROGRAMME</p>
+
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal"></td><td class="tar"><span class="fs85">PAGE</span></td></tr>
+<tr><td class="tal">On Lord Gifford’s Conception of “Science”</td><td class="tar"><a href="#Page_1">1</a></td></tr>
+<tr><td class="tal">Natural Sciences and “Natural Theology”</td><td class="tar"><a href="#Page_3">3</a></td></tr>
+<tr><td class="tal">Our Philosophical Basis</td><td class="tar"><a href="#Page_5">5</a></td></tr>
+<tr><td class="tal">On Certain Characteristics of Biology as a Science</td><td class="tar"><a href="#Page_9">9</a></td></tr>
+<tr><td class="tal">The Three Different Types of Knowledge about Nature</td><td class="tar"><a href="#Page_13">13</a></td></tr>
+<tr><td class="tal">General Plan of these Lectures</td><td class="tar"><a href="#Page_15">15</a></td></tr>
+<tr><td class="tal">General Character of the Organic Form</td><td class="tar"><a href="#Page_19">19</a></td></tr>
+</table></div>
+
+
+<p class="tac">SECTION A.&mdash;THE CHIEF RESULTS OF ANALYTICAL BIOLOGY</p>
+
+<p class="tac">PART I.&mdash;THE INDIVIDUAL ORGANISM WITH REGARD TO<br />FORM AND METABOLISM</p>
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal pb05em"><i>A.</i> ELEMENTARY MORPHOGENESIS&mdash;</td><td></td></tr>
+<tr><td class="tal pl2em">Evolutio and Epigenesis in the old Sense</td><td class="tar"><a href="#Page_25">25</a></td></tr>
+<tr><td class="tal pl2em">The Cell</td><td class="tar"><a href="#Page_27">27</a></td></tr>
+<tr><td class="tal pl2em">The Egg: its Maturation and Fertilisation</td><td class="tar"><a href="#Page_31">31</a></td></tr>
+<tr><td class="tal pl2em">The First Developmental Processes of Echinus</td><td class="tar"><a href="#Page_33">33</a></td></tr>
+<tr><td class="tal pl2em">Comparative Embryology</td><td class="tar"><a href="#Page_44">44</a></td></tr>
+<tr><td class="tal pl2em">The First Steps of Analytical Morphogenesis</td><td class="tar"><a href="#Page_45">45</a></td></tr>
+<tr><td class="tal pl2em pb15em">The Limits of Pure Description in Science</td><td class="tar pb15em"><a href="#Page_50">50</a></td></tr>
+<tr><td class="tal pb05em"><i>B.</i> EXPERIMENTAL AND THEORETICAL MORPHOGENESIS&mdash;</td></tr>
+<tr><td class="tal pl2em pr4em">1. <span class="smcap">The Foundations of the Physiology of Development. “Evolutio” and “Epigenesis”</span></td><td class="tar vab"><a href="#Page_52">52</a></td></tr>
+<tr><td class="tal pl4em">The Theory of Weismann</td><td class="tar vab"><a href="#Page_52">52</a></td></tr>
+<tr><td class="tal pl4em">Experimental Morphology</td><td class="tar vab"><a href="#Page_56">56</a></td></tr>
+<tr><td class="tal pl4em"><span class="pagenum" title="x"><a name="Page_x" id="Page_x"></a></span>The Work of Wilhelm Roux</td><td class="tar vab"><a href="#Page_58">58</a></td></tr>
+<tr><td class="tal pl4em">The Experiments on the Egg of the Sea-urchin</td><td class="tar vab"><a href="#Page_59">59</a></td></tr>
+<tr><td class="tal pl4em">On the Intimate Structure of the Protoplasm of the Germ</td><td class="tar vab"><a href="#Page_65">65</a></td></tr>
+<tr><td class="tal pl4em">On some Specificities of Organisation in Certain Germs</td><td class="tar vab"><a href="#Page_70">70</a></td></tr>
+<tr><td class="tal pl4em">General Results of the First Period of “Entwickelungsmechanik”</td><td class="tar vab"><a href="#Page_71">71</a></td></tr>
+<tr><td class="tal pl4em">Some New Results concerning Restitutions</td><td class="tar vab"><a href="#Page_74">74</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">Analytical Theory of Morphogenesis</span></td><td class="tar"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl4em">α. <span class="lowercase smcap">THE DISTRIBUTION OF MORPHOGENIC POTENCIES</span></td><td class="tar vab"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl6em">Prospective Value and Prospective Potency</td><td class="tar vab"><a href="#Page_76">76</a></td></tr>
+<tr><td class="tal pl6em">The Potencies of the Blastomeres</td><td class="tar vab"><a href="#Page_79">79</a></td></tr>
+<tr><td class="tal pl6em">The Potencies of Elementary Organs in General</td><td class="tar vab"><a href="#Page_80">80</a></td></tr>
+<tr><td class="tal pl6em">Explicit and Implicit Potencies: Primary and Secondary Potencies</td><td class="tar vab"><a href="#Page_83">83</a></td></tr>
+<tr><td class="tal pl6em pr4em">The Morphogenetic Function of Maturation in the Light of Recent Discoveries</td><td class="tar vab"><a href="#Page_85">85</a></td></tr>
+<tr><td class="tal pl6em">The Intimate Structure of Protoplasm: Further Remarks</td><td class="tar vab"><a href="#Page_88">88</a></td></tr>
+<tr><td class="tal pl6em">The Neutrality of the Concept of “Potency”</td><td class="tar vab"><a href="#Page_89">89</a></td></tr>
+<tr><td class="tal pl4em pt05em">β. <span class="lowercase smcap">THE “MEANS” OF MORPHOGENESIS</span></td><td class="tar vab"><a href="#Page_89">89</a></td></tr>
+<tr><td class="tal pl6em">β′. The Internal Elementary Means of Morphogenesis</td><td class="tar vab"><a href="#Page_90">90</a></td></tr>
+<tr><td class="tal pl8em pr4em">Some Remarks on the Importance of Surface Tension in Morphogenesis</td><td class="tar vab"><a href="#Page_91">91</a></td></tr>
+<tr><td class="tal pl8em">On Growth</td><td class="tar vab"><a href="#Page_93">93</a></td></tr>
+<tr><td class="tal pl8em">On Cell-division</td><td class="tar vab"><a href="#Page_94">94</a></td></tr>
+<tr><td class="tal pl6em">β″. The External Means of Morphogenesis</td><td class="tar vab"><a href="#Page_95">95</a></td></tr>
+<tr><td class="tal pl8em">The Discoveries of Herbst</td><td class="tar vab"><a href="#Page_96">96</a></td></tr>
+<tr><td class="tal pl4em pt05em">γ. <span class="lowercase smcap">THE FORMATIVE CAUSES OR STIMULI</span></td><td class="tar vab"><a href="#Page_99">99</a></td></tr>
+<tr><td class="tal pl6em">The Definition of Cause</td><td class="tar vab"><a href="#Page_99">99</a></td></tr>
+<tr><td class="tal pl6em">Some Instances of Formative and Directive Stimuli</td><td class="tar vab"><a href="#Page_102">102</a></td></tr>
+<tr><td class="tal pl4em pt05em">δ. <span class="lowercase smcap">THE MORPHOGENETIC HARMONIES</span></td><td class="tar vab"><a href="#Page_107">107</a></td></tr>
+<tr><td class="tal pl4em pt05em">ε. <span class="lowercase smcap">ON RESTITUTIONS</span></td><td class="tar vab"><a href="#Page_110">110</a></td></tr>
+<tr><td class="tal pl6em pr4em">A few Remarks on Secondary Potencies and on Secondary Morphogenetic Regulations in General</td><td class="tar vab"><a href="#Page_110">110</a></td></tr>
+<tr><td class="tal pl6em">The Stimuli of Restitutions</td><td class="tar vab"><a href="#Page_113">113</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">3. <span class="smcap">The Problem of Morphogenetic Localisation: The Theory of the Harmonious-Equipotential system&mdash;First Proof of the Autonomy of Life</span></td><td class="tar vab ptb05em"><a href="#Page_118">118</a></td></tr>
+<tr><td class="tal pl4em">The General Problem</td><td class="tar vab"><a href="#Page_118">118</a></td></tr>
+<tr><td class="tal pl4em">The Morphogenetic “System”</td><td class="tar vab"><a href="#Page_119">119</a></td></tr>
+<tr><td class="tal pl4em">The “Harmonious-equipotential System”</td><td class="tar vab"><a href="#Page_122">122</a></td></tr>
+<tr><td class="tal pl4em"><span class="pagenum" title="xi"><a name="Page_xi" id="Page_xi"></a></span>Instances of “Harmonious-equipotential Systems”</td><td class="tar vab"><a href="#Page_126">126</a></td></tr>
+<tr><td class="tal pl4em">The Problem of the Factor <i>E</i></td><td class="tar vab"><a href="#Page_132">132</a></td></tr>
+<tr><td class="tal pl4em">No Explanation offered by “Means” or “Formative Stimuli”</td><td class="tar vab"><a href="#Page_132">132</a></td></tr>
+<tr><td class="tal pl4em">No Explanation offered by a Chemical Theory of Morphogenesis</td><td class="tar vab"><a href="#Page_134">134</a></td></tr>
+<tr><td class="tal pl4em">No Machine Possible Inside the Harmonious Systems</td><td class="tar vab"><a href="#Page_138">138</a></td></tr>
+<tr><td class="tal pl4em">The Autonomy of Morphogenesis proved</td><td class="tar vab"><a href="#Page_142">142</a></td></tr>
+<tr><td class="tal pl4em">“Entelechy”</td><td class="tar vab"><a href="#Page_143">143</a></td></tr>
+<tr><td class="tal pl4em">Some General Remarks on Vitalism</td><td class="tar vab"><a href="#Page_145">145</a></td></tr>
+<tr><td class="tal pl4em">The Logic of our First Proof of Vitalism</td><td class="tar vab"><a href="#Page_146">146</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">4. <span class="smcap">On Certain other Features of Morphogenesis Advocating its Autonomy</span></td><td class="tar vab ptb05em"><a href="#Page_150">150</a></td></tr>
+<tr><td class="tal pl4em">Harmonious-equipotential Systems formed by Wandering Cells</td><td class="tar vab"><a href="#Page_151">151</a></td></tr>
+<tr><td class="tal pl4em">On Certain Combined Types of Morphogenetic Systems</td><td class="tar vab"><a href="#Page_153">153</a></td></tr>
+<tr><td class="tal pl4em">The “Morphaesthesia” of Noll</td><td class="tar vab"><a href="#Page_157">157</a></td></tr>
+<tr><td class="tal pl4em">Restitutions of the Second Order</td><td class="tar vab"><a href="#Page_158">158</a></td></tr>
+<tr><td class="tal pl4em">On the “Equifinality” of Restitutions</td><td class="tar vab"><a href="#Page_159">159</a></td></tr>
+<tr><td class="tal pl4em pb15em">Remarks on “Retro-Differentiation”</td><td class="tar pb15em"><a href="#Page_163">163</a></td></tr>
+<tr><td class="tal pb05em"><i>C.</i> ADAPTATION&mdash;</td></tr>
+<tr><td class="tal pl2em"><span class="smcap">Introductory Remarks on Regulations in General</span></td><td class="tar vab"><a href="#Page_165">165</a></td></tr>
+<tr><td class="tal pl2em ptb05em">1. <span class="smcap">Morphological Adaptation</span></td><td class="tar"><a href="#Page_168">168</a></td></tr>
+<tr><td class="tal pl4em">The Limits of the Concept of Adaptation</td><td class="tar vab"><a href="#Page_168">168</a></td></tr>
+<tr><td class="tal pl4em">Adaptations to Functional Changes from Without</td><td class="tar vab"><a href="#Page_172">172</a></td></tr>
+<tr><td class="tal pl4em">True Functional Adaptation</td><td class="tar vab"><a href="#Page_176">176</a></td></tr>
+<tr><td class="tal pl4em">Theoretical Conclusions</td><td class="tar vab"><a href="#Page_179">179</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">Physiological Adaptation</span></td><td class="tar"><a href="#Page_184">184</a></td></tr>
+<tr><td class="tal pl4em">Specific Adaptedness <em>not</em> “Adaptation”</td><td class="tar vab"><a href="#Page_186">186</a></td></tr>
+<tr><td class="tal pl4em">Primary and Secondary Adaptations in Physiology</td><td class="tar vab"><a href="#Page_188">188</a></td></tr>
+<tr><td class="tal pl4em">On Certain Pre-requisites of Adaptations in General</td><td class="tar vab"><a href="#Page_189">189</a></td></tr>
+<tr><td class="tal pl4em">On Certain Groups of Primary Physiological Adaptations</td><td class="tar vab"><a href="#Page_190">190</a></td></tr>
+<tr><td class="tal pl6em">General Remarks on Irritability</td><td class="tar vab"><a href="#Page_190">190</a></td></tr>
+<tr><td class="tal pl6em">The Regulation of Heat Production</td><td class="tar vab"><a href="#Page_193">193</a></td></tr>
+<tr><td class="tal pl6em pr4em">Primary Regulations in the Transport of Materials and Certain Phenomena of Osmotic Pressure</td><td class="tar vab"><a href="#Page_194">194</a></td></tr>
+<tr><td class="tal pl6em">Chromatic Regulations in Algae</td><td class="tar vab"><a href="#Page_197">197</a></td></tr>
+<tr><td class="tal pl6em">Metabolic Regulations</td><td class="tar vab"><a href="#Page_198">198</a></td></tr>
+<tr><td class="tal pl4em">Immunity the only Type of a Secondary Physiological Adaptation</td><td class="tar vab"><a href="#Page_204">204</a></td></tr>
+<tr><td class="tal pl4em">No General Positive Result from this Chapter</td><td class="tar vab"><a href="#Page_209">209</a></td></tr>
+<tr><td class="tal pl4em pb15em">A few Remarks on the Limits of Regulability</td><td class="tar pb15em"><a href="#Page_212">212</a></td></tr>
+<tr><td class="tal pb05em"><span class="pagenum" title="xii"><a name="Page_xii" id="Page_xii"></a></span><i>D.</i> INHERITANCE. SECOND PROOF OF THE AUTONOMY OF LIFE&mdash;</td></tr>
+<tr><td class="tal pl2em">The Material Continuity in Inheritance</td><td class="tar vab"><a href="#Page_214">214</a></td></tr>
+<tr><td class="tal pl2em">On Certain Theories which Seek to Compare Inheritance to Memory</td><td class="tar vab"><a href="#Page_216">216</a></td></tr>
+<tr><td class="tal pl2em">The Complex-Equipotential System and its Rôle in Inheritance</td><td class="tar vab"><a href="#Page_219">219</a></td></tr>
+<tr><td class="tal pl2em pr4em">The Second Proof of Life-Autonomy. Entelechy at the Bottom of Inheritance</td><td class="tar vab"><a href="#Page_224">224</a></td></tr>
+<tr><td class="tal pl2em">The Significance of the Material Continuity in Inheritance</td><td class="tar vab"><a href="#Page_227">227</a></td></tr>
+<tr><td class="tal pl2em">The Experimental Facts about Inheritance</td><td class="tar vab"><a href="#Page_228">228</a></td></tr>
+<tr><td class="tal pl2em">The Rôle of the Nucleus in Inheritance</td><td class="tar vab"><a href="#Page_233">233</a></td></tr>
+<tr><td class="tal pl2em pb15em">Variation and Mutation</td><td class="tar pb15em"><a href="#Page_237">237</a></td></tr>
+<tr><td class="tal"><i><span class="smcap">Conclusions from the First Main Part of these Lectures</span></i></td><td class="tar vab"><a href="#Page_240">240</a></td></tr>
+</table></div>
+
+<p class="tac">PART II.&mdash;SYSTEMATICS AND HISTORY</p>
+
+<div class="tac mb2em">
+<table width="85%" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tal pb05em"><i>A.</i> THE PRINCIPLES OF SYSTEMATICS&mdash;</td></tr>
+<tr><td class="tal pl2em">Rational Systematics</td><td class="tar vab"><a href="#Page_243">243</a></td></tr>
+<tr><td class="tal pl2em pb15em">Biological Systematics</td><td class="tar pb15em"><a href="#Page_246">246</a></td></tr>
+<tr><td class="tal pb05em"><i>B.</i> THE THEORY OF DESCENT&mdash;</td></tr>
+<tr><td class="tal pl2em ptb05em">1. <span class="smcap">Generalities</span></td><td class="tar"><a href="#Page_250">250</a></td></tr>
+<tr><td class="tal pl4em">The Covert Presumption of all Theories of Descent</td><td class="tar vab"><a href="#Page_253">253</a></td></tr>
+<tr><td class="tal pl4em">The Small Value of Pure Phylogeny</td><td class="tar vab"><a href="#Page_255">255</a></td></tr>
+<tr><td class="tal pl4em">History and Systematics</td><td class="tar vab"><a href="#Page_257">257</a></td></tr>
+<tr><td class="tal pl2em ptb05em">2. <span class="smcap">The Principles of Darwinism</span></td><td class="tar"><a href="#Page_260">260</a></td></tr>
+<tr><td class="tal pl4em">Natural Selection</td><td class="tar vab"><a href="#Page_261">261</a></td></tr>
+<tr><td class="tal pl4em">Fluctuating Variation the Alleged Cause of Organic Diversity</td><td class="tar vab"><a href="#Page_264">264</a></td></tr>
+<tr><td class="tal pl4em">Darwinism Fails all along the Line</td><td class="tar vab"><a href="#Page_269">269</a></td></tr>
+<tr><td class="tal pl2em ptb05em">3. <span class="smcap">The Principles of Lamarckism</span></td><td class="tar"><a href="#Page_271">271</a></td></tr>
+<tr><td class="tal pl4em">Adaptation as the Starting-Point</td><td class="tar vab"><a href="#Page_272">272</a></td></tr>
+<tr><td class="tal pl4em">The Active Storing of Contingent Variations as a Hypothetic Principle</td><td class="tar vab"><a href="#Page_273">273</a></td></tr>
+<tr><td class="tal pl4em pr4em">Criticism of the “Inheritance of Acquired Characters” assumed by Lamarckism</td><td class="tar vab"><a href="#Page_275">275</a></td></tr>
+<tr><td class="tal pl4em">Other Principles Wanted</td><td class="tar vab"><a href="#Page_281">281</a></td></tr>
+<tr><td class="tal pl4em pr4em">Criticism of the Hypothesis of Storing and Handing Down Contingent Variations</td><td class="tar vab"><a href="#Page_282">282</a></td></tr>
+<tr><td class="tal pl2em ptb05em">4. <span class="smcap">The Real Results and the Unsolved Problems of Transformism</span></td><td class="tar ptb05em"><a href="#Page_290">290</a></td></tr>
+<tr><td class="tal pl2em ptb05em pr4em">5. <span class="smcap">The Logical Value of the Organic Form according to the different Transformistic Theories</span></td><td class="tar ptb05em vab"><a href="#Page_293">293</a></td></tr>
+<tr><td class="tal pl4em pb15em">The Organic Form and Entelechy</td><td class="tar pb15em"><a href="#Page_294">294</a></td></tr>
+<tr><td class="tal pb05em"><i>C.</i> THE LOGIC OF HISTORY</td><td class="tar pb05em"><a href="#Page_297">297</a><span class="pagenum" title="xiii"><a name="Page_xiii" id="Page_xiii"></a></span></td></tr>
+<tr><td class="tal pl2em pb05em">1. <span class="smcap">The Possible Aspects of History</span></td><td class="tar pb05em"><a href="#Page_299">299</a></td></tr>
+<tr><td class="tal pl2em pb05em">2. <span class="smcap">Phylogenetic Possibilities</span></td><td class="tar pb05em"><a href="#Page_304">304</a></td></tr>
+<tr><td class="tal pl2em pb05em">3. <span class="smcap">The History of Mankind</span></td><td class="tar pb05em"><a href="#Page_306">306</a></td></tr>
+<tr><td class="tal pl4em">Cumulations in Human History</td><td class="tar vab"><a href="#Page_308">308</a></td></tr>
+<tr><td class="tal pl4em">Human History not an “Evolution”</td><td class="tar vab"><a href="#Page_311">311</a></td></tr>
+<tr><td class="tal pl4em pb15em">The Problem of the “Single” as such</td><td class="tar pb15em"><a href="#Page_315">315</a></td></tr>
+<tr><td class="tal pb05em"><i><span class="smcap">Conclusions about Systematics and History in General</span></i></td><td class="tar pb05em"><a href="#Page_322">322</a></td></tr>
+</table></div>
+
+<p><span class="pagenum hide" title="xiv"><a name="Page_xiv" id="Page_xiv"></a></span></p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="1"><a name="Page_1" id="Page_1"></a></span></p>
+
+
+
+<h2>THE PROGRAMME</h2>
+
+
+<p class="tac ptb05em"><span class="smcap">On Lord Gifford’s Conception of “Science”</span></p>
+
+<p>This is the first time that a biologist has occupied this
+place; the first time that a biologist is to try to carry out the
+intentions of the noble and high-minded man to whom this
+lectureship owes its foundation.</p>
+
+<p>On such an occasion it seems to be not undesirable to
+inquire what Lord Gifford’s own opinions about natural
+science may have been, what place in the whole scheme of
+human knowledge he may have attributed to those branches
+of it which have become almost the centre of men’s
+intellectual interest.</p>
+
+<p>And, indeed, on studying Lord Gifford’s bequest with
+the object of finding in it some reference to the natural
+sciences, one easily notes that he has assigned to them a
+very high place compared with the other sciences, at least
+in one respect: with regard to their methods.</p>
+
+<p>There is a highly interesting passage in his will which
+leaves no doubt about our question. After having formally
+declared the foundation of this lectureship “for Promoting,
+Advancing, Teaching and Diffusing the study of Natural
+Theology in the widest sense of that term,” and after<span class="pagenum" title="2"><a name="Page_2" id="Page_2"></a></span>
+having arranged about the special features of the lectures,
+he continues: “I wish the lecturers to treat their subject
+as a strictly natural science, the greatest of all possible
+sciences, indeed, in one sense, the only science, that of
+Infinite Being.&nbsp;.&nbsp;.&nbsp;. I wish it considered just as astronomy
+or chemistry is.”</p>
+
+<p>Of course, it is not possible to understand these words
+of Lord Gifford’s will in a quite literal sense. If, provisionally,
+we call “natural theology” the ultimate conclusions
+which may be drawn from a study of nature in connection
+with all other results of human sciences, there cannot be
+any doubt that these conclusions will be of a rather different
+character from the results obtained in, say, the special field
+of scientific chemistry. But, nevertheless, there are, I
+think, two points of contact between the wider and the
+narrower field of knowledge, and both of them relate to
+method. Lord Gifford’s own phrase, “Infinite Being,”
+shows us one of these meeting-points. In opposition to
+history of any form, natural sciences aim at discovering
+such truths as are independent of special time and of
+special space, such truths as are “ideas” in the sense of
+Plato; and such eternal results, indeed, always stand in
+close relation to the ultimate results of human knowledge
+in general. But besides that there is still another feature
+which may be common both to “natural theology” and to
+the special natural sciences, and which is most fully developed
+in the latter: freedom from prepossessions. This, at least,
+is an ideal of all natural sciences; I may say it is <em>the</em>
+ideal of them. That it was this feature which Lord Gifford
+had in view in his comparison becomes clear when we read
+in his will that the lectures on natural theology are<span class="pagenum" title="3"><a name="Page_3" id="Page_3"></a></span>
+to be delivered “without reference to or reliance upon
+any supposed special exceptional or so-called miraculous
+revelation.”</p>
+
+<p>So we might say that both in their logical and their
+moral methods, natural sciences are to be the prototype of
+“Natural Theology” in Lord Gifford’s sense.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Natural Sciences and “Natural Theology”</span></p>
+
+<p>But now let us study in a more systematic manner the
+possible relations of the natural sciences to natural theology
+as a science.</p>
+
+<p>How is it possible for a natural scientist to contribute
+to the science of the highest and ultimate subject of human
+knowledge?</p>
+
+<p>Almost all natural sciences have a sort of naïveté in
+their own spheres; they all stand on the ground of what
+has been called a naïve realism, as long as they are, so
+to say, at home. That in no way prejudices their own
+progress, but it seems to stand in the way of establishing
+contact with any higher form of human knowledge than
+themselves. One may be a first-rate organic chemist even
+when looking upon the atoms as small billiard balls, and
+one may make brilliant discoveries about the behaviour of
+animals even when regarding them in the most anthropomorphic
+manner&mdash;granted that one is a good observer;
+but it can hardly be admitted that our chemist would do
+much to advance the theory of matter, or our biologist to
+solve the problem of the relations between body and mind.</p>
+
+<p>It is only by the aid of philosophy, or I would rather
+say by keeping in constant touch with it, that natural<span class="pagenum" title="4"><a name="Page_4" id="Page_4"></a></span>
+sciences are able to acquire any significance for what might
+be called <em>the</em> science of nature in the most simple form.
+Unhappily the term “natural philosophy” is restricted in
+English to theoretical physics. This is not without a high
+degree of justification, for theoretical physics has indeed lost
+its naïveté and become a philosophy of nature; but it nevertheless
+is very unfortunate that this use of the term “natural
+philosophy” is established in this country, as we now have
+no proper general term descriptive of a natural science that
+is in permanent relation to philosophy, a natural science
+which does not use a single concept without justifying it
+epistemologically, <i>i.e.</i> what in German, for instance, would
+simply be called “Naturphilosophie.”</p>
+
+<p>Let us call it philosophy of nature; then we may say
+that only by becoming a true philosophy of nature are
+natural sciences of all sorts able to contribute to the highest
+questions which man’s spirit of inquiry can suggest.</p>
+
+<p>These highest questions themselves are the outcome of
+the combination of the highest results of all branches of
+philosophy, just as our philosophy of nature originated in the
+discussion of the results of all the separate natural sciences.
+Are those highest questions not only to be asked, are they
+to be also solved? To be solved in a way which does not
+exceed the limits of philosophy as the domain of actual
+understanding?</p>
+
+<p>The beginning of a long series of studies is not the right
+place to decide this important question; and so, for the
+present certainly, “natural theology” must remain a problem.
+In other words: it must remain an open question
+at the beginning of our studies, whether after all there
+can be any final general answer, free from contradictions,<span class="pagenum" title="5"><a name="Page_5" id="Page_5"></a></span>
+applicable to the totality of questions asked by all the
+branches of philosophy.</p>
+
+<p>But let us not be disturbed by this problematic entrance
+to our studies. Let us follow biology on its own path;
+let us study its transition from a “naïve” science to a real
+branch of the philosophy of nature. In this way we perhaps
+shall be able to understand what its part may be in solving
+what can be solved.</p>
+
+<p>That is to be our subject.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Our Philosophical Basis</span></p>
+
+<p>We call <em>nature</em> what is given to us in space.</p>
+
+<p>Of course we are not obliged in these lectures to
+discuss the psychological and epistemological problems of
+space with its three dimensions, nor are we obliged to
+develop a general theory of reality and its different
+aspects. A few epistemological points will be considered
+later at proper times, and always in connection with results
+of theoretical biology.</p>
+
+<p>At present it must suffice to say that our general
+philosophical point of view will be idealistic, in the critical
+meaning of the word. The universe, and within the
+universe nature, in the sense just defined, is my
+phenomenon. That is what I know. I know nothing
+more, either positively or negatively; that is to say, I
+do not know that the world is <em>only my</em> phenomenon, but,
+on the other hand, I know nothing about its “absolute
+reality.” And more, I am not even able to describe in
+intelligible words what “absolute reality” might mean. I
+am fully entitled to state: the universe <em>is</em> as truly as I<span class="pagenum" title="6"><a name="Page_6" id="Page_6"></a></span>
+am&mdash;though in a somewhat different sense of “being”&mdash;and
+I <em>am</em> as truly as the universe is; but I am not
+entitled to state anything beyond these two corresponding
+phrases. You know that, in the history of European
+philosophy at least, Bishop Berkeley was the first clearly
+to outline the field of idealism.</p>
+
+<p>But my phenomenon&mdash;the world, especially nature&mdash;consists
+of elements of two different kinds: some of them
+are merely passive, some of them contain a peculiar sort
+of activity in themselves. The first are generally called
+sensations, but perhaps would be better called elements
+or presentations; the others are forms of construction, and,
+indeed, there is an active element embraced in them in
+this sense, that they allow, by their free combination, the
+discovery of principles which are not to be denied, which
+must be affirmed, whenever their meaning is understood.
+You know that I am speaking here of what are generally
+called categories and synthetic judgments <i lang="la" xml:lang="la">a priori</i>, and
+that it was Kant who, on the foundations laid by Locke,
+Hume, and Leibnitz, first gave the outlines of what may
+be called the real system of critical philosophy. Indeed,
+our method will be to a great extent Kantian, though
+with certain exceptions; it is to be strictly idealistic, and
+will not in the Kantian way operate with things in
+themselves; and it regards the so-called “synthetic judgment
+<i lang="la" xml:lang="la">a priori</i>” and the problem of the relation between
+categorical principles and experience in a somewhat
+different manner. We think it best to define the much
+disputed concept “<i lang="la" xml:lang="la">a priori</i>” as “independent of the <em>amount</em>
+of experience”; that is to say, all categories and categorical
+principles are brought to my consciousness by that<span class="pagenum" title="7"><a name="Page_7" id="Page_7"></a></span>
+fundamental event which is called experience, and therefore
+are not independent of it, but they are not inferences from
+experience, as are so-called empirical laws. We almost
+might say that we only have to be reminded of those
+principles by experience, and, indeed, we should not, I
+think, go very far wrong in saying that the Socratic
+doctrine, that all knowledge is recollection, holds good as
+far as categories and categorical principles are in question.</p>
+
+<p>But enough at present about our general philosophy.</p>
+
+<p>As to the philosophy of nature, there can be no doubt
+that, on the basis of principles like those we have shortly
+sketched, its ultimate aim must be to co-ordinate everything
+in nature with terms and principles of the categorical
+style. The philosophy of nature thus becomes a system;
+a system of which the general type is afforded by the
+innate constructive power of the Ego. In this sense
+the Kantian dictum remains true, that the Ego prescribes
+its own laws to nature, though, of course, “nature,” that
+is, what is given in space, must be such as to permit that
+sort of “prescription.”</p>
+
+<p>One often hears that all sciences, including the science
+of sciences, philosophy, have to find out what is true.
+What, then, may be called “true” by an idealistic
+philosopher, for whom the old realistic formula of the
+conformity between knowledge and the object cannot
+have any meaning? Besides its ordinary application to
+simple facts or to simple judgments, where the word truth
+only means absence of illusion or no false statement, truth
+can be claimed for a philosophical doctrine or for a system
+of such doctrines only in the sense that there are no
+contradictions amongst the parts of the doctrine or of the<span class="pagenum" title="8"><a name="Page_8" id="Page_8"></a></span>
+system themselves, and that there are no features in them
+which impel our categorical Ego to further analysis.</p>
+
+<p>Those of you who attended Professor Ward’s lectures
+on “Naturalism and Agnosticism,” or who have read his
+excellent book on that subject, will know what the aims of
+a theory of matter are. You will also be aware that, at
+present, there does not exist any theory of matter which
+can claim to be “true”; there are contradictions in every
+theory of matter, and, moreover, there are always some
+points where we are obliged to ask for further information
+and receive no answer. Experience here has not yet
+aroused all the categorical functions which are needed in
+order to form one unity out of what seem to be incompatibilities
+at the present day. Why is that? Maybe
+because experience is not yet complete in this field, but
+maybe also because the whole subject is so complicated
+that it takes much time to attach categorical functions to
+what is experienced.</p>
+
+<p>But it is not our object here to deal either with
+epistemology proper or with ontology: a full analysis of
+biological facts is our problem. Why, then, all these
+introductions? why all these philosophical sketches in
+fields of knowledge which have quite another relation to
+philosophy than biology has? Biology, I hear some one
+say, is simply and solely an empirical science; in some
+sense it is nothing but applied physics and chemistry,
+perhaps applied mechanics. There are no fundamental
+principles in biology which could bring it in any close
+contact with philosophy. Even the one and only principle
+which might seem to be an innate principle of our
+experience about life, the principle of evolution, is only a<span class="pagenum" title="9"><a name="Page_9" id="Page_9"></a></span>
+combination of more simple factors of the physical and
+chemical type.</p>
+
+<p>It will be my essential endeavour to convince you, in
+the course of these lectures, that such an aspect of the
+science of biology is wrong; that biology is an elemental
+natural science in the true sense of the word.</p>
+
+<p>But if biology is an elemental science, then, and only
+then, it stands in close relations to epistemology and
+ontology&mdash;in the same relations to them, indeed, as every
+natural science does which deals with true elements of nature,
+and which is willing to abandon naïve realism and contribute
+its share to the whole of human knowledge.</p>
+
+<p>And, therefore, a philosophical sketch is not out of
+place at the beginning of lectures on the Philosophy of
+the Organism. We may be forced, we, indeed, shall be
+forced, to remain for some time on the ground of realistic
+empiricism, for biology has to deal with very complicated
+experiences; but there will be a moment in our progress
+when we shall enter the realm of the elemental ontological
+concepts, and in that very moment our study of life will
+have become a part of real philosophy. It was not without
+good reasons, therefore, that I shortly sketched, as a sort
+of introduction to my lectures, the general point of view
+which we shall take with regard to philosophical questions,
+and to questions of the philosophy of nature in particular.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">On Certain Characteristics of Biology as a Science</span></p>
+
+<p>Biology is the science of life. Practically, all of you
+know what a living being is, and therefore it is not
+necessary to formulate a definition of life, which, at the<span class="pagenum" title="10"><a name="Page_10" id="Page_10"></a></span>
+beginning of our studies, would be either provisional and
+incomplete, or else dogmatic. In some respects, indeed, a
+definition should rather be the end of a science than its
+opening.</p>
+
+<p>We shall study the phenomena of living organisms
+analytically, by the aid of experiment; our principal object
+will be to find out laws in these phenomena; such laws
+will then be further analysed, and precisely at that point
+we shall leave the realm of natural science proper.</p>
+
+<p>Our science is the highest of all natural sciences, for
+it embraces as its final object the actions of man, at least
+in so far as actions also are phenomena observable on living
+bodies.</p>
+
+<p>But biology is also the most difficult of all natural
+sciences, not only from the complexity of the phenomena,
+which it studies, but in particular for another reason which
+is seldom properly emphasised, and therefore will well repay
+us for a few words devoted to it.</p>
+
+<p>Except so far as the “elements” of chemistry come
+into account, the experimenter in the inorganic fields of
+nature is not hampered by the specificity of composite
+objects: he makes all the combinations he wants. He is
+always able to have at his disposal red rays of a desired
+wave length when and where he wants, or to have, at a
+given time and place, the precise amount of any organic
+compound which he wishes to examine. And he forces
+electricity and electromagnetism to obey his will, at least
+with regard to space, time, and intensity of their appearance.</p>
+
+<p>The biologist is not able to “make” life, as the physicist
+has made red rays or electromagnetism, or as the chemist
+has made a certain compound of carbon. The biologist is<span class="pagenum" title="11"><a name="Page_11" id="Page_11"></a></span>
+almost always in that strange plight in which the physicist
+would be if he always had to go to volcanoes in order to
+study the conductivity of heat, or if he had to wait for
+thunderstorms in order to study electricity. The biologist
+is dependent on the specificity of living objects as they occur
+in nature.</p>
+
+<p>A few instances may show you what great inconveniences
+may hence arise to impede practical biological
+research. We later on shall have to deal with experiments
+on very young embryos: parts of the germ will have to be
+destroyed in order to study what will happen with the rest.
+Now almost all germs are surrounded by a membrane; this
+membrane has to be detached before any operation is
+possible. But what are we to do if it is not possible to
+remove the membrane without killing the embryo? Or what
+if, as for instance in many marine animals, the membrane
+may be removed but the germs are killed by contact with
+sea-water? In both cases no experiments at all will be
+possible on a sort of germ which otherwise, for some special
+circumstances of its organisation, might have given results
+of importance. These results become impossible for only a
+practical, for a very secondary reason; but enough: they
+are impossible, and they might have thrown light on
+problems which now must remain problems. Quite the
+same thing may occur in experiments on physiology proper
+or functional physiology: one kind of animals survives the
+operation, the other kind does not, and therefore, for merely
+extrinsic reasons, the investigations have to be restricted to
+the first, though the second might have given more important
+results. And thus the biological experimenter
+always finds himself in a sort of dependence on his subjects,<span class="pagenum" title="12"><a name="Page_12" id="Page_12"></a></span>
+which can hardly be called pleasant. To a great extent
+the comparatively slow advance of biological sciences is due
+to this very fact: the unalterable specific nature of biological
+material.</p>
+
+<p>But there is still another feature of biology dependent
+on the same fact. If a science is tied down to specific
+objects in every path it takes, it first, of course, has to
+know all about those objects, and that requires nothing
+else but plain description. We now understand why pure
+description, in the most simple sense of the word, takes up
+such an enormous part of every text-book of biological
+science. It is not only morphology, the science of form,
+that is most actively concerned with description; physiology
+also, in its present state, is pure description of what the
+functions of the different parts of the body of animals and
+plants actually <em>are</em>, at least for about nine-tenths of its
+range. It seems to me important to press this point very
+emphatically, since we often hear that physiology is from
+the very beginning a much higher sort of knowledge than
+morphology, inasmuch as it is rational. That is not at
+all true of the beginning of physiology: what the functions
+of the liver or of the root are has simply to be described
+just as the organisation of the brain or of the leaf, and it
+makes no difference logically that one species of description
+has to use the experimental method, while the other has
+not. The experiment which only discovers what happens
+here or what happens there, possesses no kind of logical
+superiority over pure description at all.</p>
+
+<p>But there will be another occasion in our lectures to
+deal more fully with the logic of experiment and with the
+differences of descriptive knowledge and real rational science.</p>
+
+<p><span class="pagenum" title="13"><a name="Page_13" id="Page_13"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The three Different Types of Knowledge about Nature</span></p>
+
+<p>Natural sciences cannot originate before the given
+phenomena of nature have been investigated in at least a
+superficial and provisional manner, by and for the practical
+needs of man. But as soon as true science begins in any
+limited field, dealing, let us say, with animals or with
+minerals, or with the properties of bodies, it at once finds
+itself confronted by two very different kinds of problems,
+both of them&mdash;like all “problems”&mdash;created in the last
+resort by the logical organisation of the human mind, or, to
+speak still more correctly, of the Ego.</p>
+
+<p>In any branch of knowledge which practical necessities
+have separated from others, and which science now tries
+to study methodically, there occur general sequences in
+phenomena, general orders of events. This uniformity is
+revealed only gradually, but as soon as it has shown itself,
+even in the least degree, the investigator seizes upon it.
+He now devotes himself chiefly, or even exclusively, to the
+generalities in the sequences of all changes. He is convinced
+that there must be a sort of most general and at the
+same time of most universal connection about all occurrences.
+This most universal connection has to be found out; at least
+it will be the ideal that always will accompany the inquiring
+mind during its researches. The “law of nature” is
+the ideal I am speaking about, an ideal which is nothing
+less than one of the postulates of the possibility of science
+at all.</p>
+
+<p>Using for our purposes a word which has been already
+introduced into terminology by the philosopher Windelband,<span class="pagenum" title="14"><a name="Page_14" id="Page_14"></a></span>
+though in a somewhat different sense, we shall call that
+part of every branch of natural sciences which regards the
+establishment of a law of nature as its ideal, “nomothetic,”
+<i>i.e.</i> “law-giving.”</p>
+
+<p>But while every natural science has its nomothetic side,
+it also has another half of a very different kind. This second
+half of every natural science does not care for the same
+general, the same universal, which is shown to us in every
+event in a different and specified kind: it is diversity, it is
+specification, that constitutes the subject of its interest.
+Its aim is to find a sufficient reason for the types of
+diversities, for the types of specifications. So in chemistry
+there has been found a systematic order in the long series
+of the compounds and of the elements; crystallography also
+has its different systems of crystals, and so on.</p>
+
+<p>We have already employed the word by which we shall
+designate this second half of every natural science: it is
+the “systematic” side of science.</p>
+
+<p>Nomothetic work on the one side and systematics on
+the other do, in fact, appear in every natural science, and
+besides them there are no other main parts. But “science”
+as a whole stands apart from another aspect of reality
+which is called “history.” History deals with particulars,
+with particular events at such and such a place, whilst
+science always abstracts from the particular, even in its
+systematic <span class="nowrap">half.<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">1</a></span></p>
+<p><span class="pagenum" title="15"><a name="Page_15" id="Page_15"></a></span></p>
+
+<p class="tac pt12b02em"><span class="smcap">General Plan of these Lectures</span></p>
+
+<p>Turning now to a sort of short outline of what is to be
+discussed in the whole of our future lectures, this summer
+and next, it seems clear, without further analysis, that
+biology as a science has its nomothetic and its systematic
+part also; respiration and assimilation, for instance, have
+proved to be types of natural laws among living phenomena,
+and that there is a “system” of animals and plants is
+too commonly known to require further explanation here.
+Therefore we might study first biological laws, and after
+that biological systematics, and in the third place perhaps
+biological history. But that would hardly correspond to
+the philosophical aims of our lectures: our chief object is
+not biology as a regular science, as treated in text-books
+and in ordinary university lectures; our chief object is the
+Philosophy of the Organism, as aided and supported by
+scientific biology. Therefore a general acquaintance with
+biology must be assumed in these lectures, and the biological
+materials must be arranged according to their bearing on
+further, that is on philosophical, analysis.</p>
+
+<p>That will be done, not, of course, to the extent of my
+regarding every one of my audience as a competent biologist;
+on the contrary, I shall explain most fully all points of
+biology proper, and even of the most simple and descriptive
+kind of biology, which serve as bases for philosophical
+analysis. But I shall do so only if they indeed do serve
+as such bases. All our biology will be not for its own
+sake, but for the sake of philosophy.</p>
+
+<p>Whilst regarding the whole of the biological material<span class="pagenum" title="16"><a name="Page_16" id="Page_16"></a></span>
+with such aims, it seems to me best to arrange the properly
+scientific material which is to be the basis of my discussions,
+not along the lines which biology as an independent science
+would <span class="nowrap">select,<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">2</a></span> but to start from the three different kinds of
+fundamental phenomena which living bodies offer to investigation,
+and to attach all systematics exclusively to one
+of them. For there will not be very much for philosophy
+to learn from biological systematics at present.</p>
+
+<p>Life is unknown to us except in association with bodies:
+we only know living bodies and call them organisms. It
+is the final object of all biology to tell us what it ultimately
+means to say that a body is “living,” and in what sorts of
+relation body and life stand one to the other.</p>
+
+<p>But at present it is enough to understand the terms
+“body” and “living” in the ordinary and popular sense.</p>
+
+<p>Regarding living bodies in this unpretentious manner,
+and recollecting what the principal characters are of all
+bodies we know as living ones, we easily find that there
+are three features which are never wanting wherever life in
+bodies occurs. All living bodies are specific as to form&mdash;they
+“have” a specific form, as we are accustomed to say.
+All living bodies also exhibit metabolism; that is to say,
+they stand in a relation of interchange of materials with
+the surrounding medium, they take in and give out materials,
+but their form can remain unchanged during these processes.
+And, in the last place, we can say that all living bodies
+move; though this faculty is more commonly known
+among animals only, even elementary science teaches the
+student that it also belongs to plants.</p>
+
+<p>Therefore we may ask for “laws of nature” in biology<span class="pagenum" title="17"><a name="Page_17" id="Page_17"></a></span>
+about form, about metabolism, and about movements. In
+fact, it is according to this scheme that we shall arrange
+the materials of the biological part of our lectures, though,
+as we cannot regard the three divisions as equally important
+in their bearing on our ultimate purposes, we shall
+not treat them quite on equal terms. It will appear that,
+at least in the present state of science, the problems of
+organic form and of organic movement have come into
+much closer relation to philosophical analysis than have
+most of the empirical data on metabolism.</p>
+
+<p>It is <em>form</em> particularly which can be said to occupy the
+very centre of biological interest; at least it furnishes the
+foundation of all biology. Therefore we shall begin our
+scientific studies with a full and thorough analysis of form.
+The science of living forms, later on, will afford us a key to
+study metabolism proper with the greatest advantage for
+our philosophical aims, and therefore the physiology of
+what is usually called the vegetative functions will be to us
+a sort of appendix to our chapters on form; only the theory
+of a problematic “living substance” and of assimilation in
+the most general meaning of the word will be reserved for
+the philosophical part; for very good reasons, as I hope to
+show. But our chapters on the living forms will have yet
+another appendix besides the survey of the physiology of
+metabolism. Biological systematics almost wholly rests on
+form, on “morphology”; and what hitherto has been done
+on the metabolical side of their problems, consists of a few
+fragments, which are far from being an equivalent to the
+morphological system; though, of course it must be granted
+that, logically, systematics, in our general meaning of the
+word, as the sum of problems about the typically different<span class="pagenum" title="18"><a name="Page_18" id="Page_18"></a></span>
+and the specific, may be studied on the basis of each one of
+the principal characteristics of living bodies, not only on
+that of their forms. Therefore, systematics is to be the
+second appendix to the chief part of our studies in morphology,
+and systematics, in its turn, will later on lead us to a
+short sketch of the historical side of biology, to the theory
+of evolution in its different forms, and to the logic of history
+in general.</p>
+
+<p>So far will our programme be carried out during this
+summer. Next year the theory of movements will conclude
+our merely scientific analysis, and the remaining
+part of the course next summer will be devoted to the
+philosophy of living nature. I hope that nobody will be
+able to accuse our philosophy of resting on unsound foundations.
+But those of you, on the other hand, who would be
+apt to regard our scientific chapters as a little too long
+compared with their philosophical results, may be asked to
+consider that a small clock-tower of a village church is
+generally less pretentious but more durable than the
+campanile of San Marco has been.</p>
+
+<p>Indeed, these lectures will afford more “facts” to my
+hearers, than Gifford Lectures probably have done, as a rule.
+But how could that be otherwise on the part of a naturalist?
+Scientific facts are the material that the philosophy of
+nature has to work with, but these facts, unfortunately, are
+not as commonly known as historical facts, for instance,
+generally are; and they must be known, in order that a
+philosophy of the organism may be of any value at all, that
+it may be more than a mere entertainment.</p>
+
+<p>Goethe once said, that even in so-called facts there is
+more “theory” than is usually granted; he apparently was<span class="pagenum" title="19"><a name="Page_19" id="Page_19"></a></span>
+thinking of what might be called the ultimate or the typical
+facts in science. It is with such typical or ultimate facts,
+of course, that we must become acquainted if our future
+philosophy is to be of profit to us.</p>
+
+<p>Certainly, there would be nothing to prevent us from
+arranging our materials in a manner exactly the reverse of
+that which we shall adopt; we could begin with a general
+principle about the organic, and could try to deduce all its
+special features from that principle, and such a way perhaps
+would seem to be the more fascinating method of argument.
+But though logical it would not be psychological, and
+therefore would be rather unnatural. And thus our
+<em>most</em> general principle about the organic will not come on
+the scene before the eighteenth of these twenty lectures,
+although it is not a mere inference or deduction from the
+former lectures: it will be a culmination of the whole, and
+we shall appreciate its value the better the more we know
+what that whole really is.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">General Character of the Organic Form</span></p>
+
+<p>Our programme of this year, it was said, is to be
+devoted wholly to organic forms, though one of its appendixes,
+dealing with some characteristics of the physiology of
+metabolism, will lead us on to a few other phenomena.
+What then are the essentials of a living form, as commonly
+understood even without a special study of biology?</p>
+
+<p>Living bodies are not simple geometrical forms, not,
+like crystals, merely a typical arrangement of surfaces in
+space, to be reduced theoretically, perhaps, to an arrangement
+of molecules. Living bodies are typically combined<span class="pagenum" title="20"><a name="Page_20" id="Page_20"></a></span>
+forms; that is to say, they consist of simpler parts
+of different characters, which have a special arrangement
+with regard to one another; these parts have a
+typical form of their own and may again be combinations
+of more simple different parts. But besides that,
+living bodies have not always the same typically combined
+form during the whole of their life: they become
+more complicated as they grow older; they all begin from
+one starting point, which has little form at all, viz., the
+egg. So the living form may be called a “genetic form,” or
+a form considered as a process, and therefore <em>morphogenesis</em>
+is the proper and adequate term for the science which deals
+with the laws of organic forms in general; or, if you prefer
+not to use the same word both for a science and for the
+subjects of that science, the <em>physiology of morphogenesis</em>.</p>
+
+<p>Now there are different branches of the physiology of
+morphogenesis or physiology of form. We may study, and
+indeed we at first shall study, what are the laws of the
+morphogenetic processes leading from the egg to the adult:
+that may be properly called physiology of development. But
+living forms are not only able to originate in one unchangeable
+way: they may restore themselves, if disturbed, and
+thus we get the physiology of restoration or restitution as a
+second branch of the science of morphogenesis. We shall
+draw very important data, some of the foundations indeed
+of our philosophical discussions, from the study of such
+restitutions. Besides that, it is to them that our survey of the
+problems of the physiology of metabolism is to be appended.</p>
+
+<p>Living forms not only originate from the egg and are
+able to restore themselves, they also may give origin to
+other forms, guaranteeing in this way the continuity of life.<span class="pagenum" title="21"><a name="Page_21" id="Page_21"></a></span>
+The physiology of heredity therefore appears as the counterpart
+to those branches of the physiology of form which deal
+with individual form and its restitutions. And our discussion
+on heredity may be followed by our second appendix
+to this chief section on form, an appendix regarding the
+outlines of systematics, evolution and history.</p>
+
+<p>Theoretical considerations on biology generally start, or
+at least, used to start, from the evolution theory, discussing
+all other problems of the physiology of form by the way
+only, as things of secondary importance. You see from
+our programme, that we shall go just the opposite way:
+evolution will come last of all, and will be treated shortly;
+but the morphogenesis of the individual will be treated
+very fully, and very carefully indeed.</p>
+
+<p>Why then this deviation from what is the common
+practice? Because we do not know very much about
+evolution at all, because in this field we are just at the very
+beginning of what deserves the name of exact knowledge.
+But concerning individual morphogenesis we really know,
+even at present, if not very much, at least something, and
+that we know in a fairly exact form, aided by the results
+of experiments.</p>
+
+<p>And it will not be without its reward, if we restrict our
+aims in such a manner, if we prefer to deal more fully with
+a series of problems, which may seem at the first glance
+to be of less interest than others. After a few lectures we
+shall find already that we may decide one very important
+question about life merely by an analysis of individual
+form production, and without any regard to problematic
+and doubtful parts of biology: that we may decide the
+question, whether “life” is only a combination of chemical<span class="pagenum" title="22"><a name="Page_22" id="Page_22"></a></span>
+and physical events, or whether it has its elemental laws,
+laws of its own.</p>
+
+<p>But to prepare the road that is to lead to such results
+we first have to restrict our aims once more, and therefore
+the next lecture of this course, which eventually is to
+touch almost every concept of philosophy proper, will begin
+with the pure description of the individual development of
+the common sea-urchin.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="23"><a name="Page_23" id="Page_23"></a></span></p>
+
+
+
+
+<h2>SECTION A</h2>
+
+<h3>THE CHIEF RESULTS OF ANALYTICAL
+BIOLOGY</h3>
+
+<hr class="chap" />
+
+<p><span class="pagenum hide" title="24"><a name="Page_24" id="Page_24"></a></span><br /><span class="pagenum" title="25"><a name="Page_25" id="Page_25"></a></span></p>
+
+
+
+<h2>PART I</h2>
+
+<h2>THE INDIVIDUAL ORGANISM WITH REGARD TO<br />
+FORM AND METABOLISM</h2>
+
+<h3><i>A.</i> ELEMENTARY MORPHOGENESIS</h3>
+
+<p class="tac ptb05em"><span class="smcap">Evolutio and Epigenesis in the old Sense</span></p>
+
+<p>The organism is a specific body, built up by a typical combination
+of specific and different parts. It is implied in
+the words of this definition, that the organism is different,
+not only from crystals, as was mentioned in the last lecture,
+but also from all combinations of crystals, such as those
+called dendrites and others, which consist of a typical arrangement
+of identical units, the nature of their combination
+depending on the forces of every single one of their parts.
+For this reason dendrites, in spite of the typical features
+in their combination, must be called aggregates; but the
+organism is not an aggregate even from the most superficial
+point of view.</p>
+
+<p>We have said before, what must have been familiar to
+you already, that the organism is not always the same in
+its individual life, that it has its development, leading from
+simpler to more complicated forms of combination of parts;
+there is a “production of visible manifoldness” carried out
+during development, to describe the chief character of that<span class="pagenum" title="26"><a name="Page_26" id="Page_26"></a></span>
+process in the words of Wilhelm Roux. We leave it an
+open question in our present merely descriptive analysis,
+whether there was already a “manifoldness,” in an invisible
+state, before development, or whether the phrase “production
+of manifoldness” is to be understood in an absolute
+sense.</p>
+
+<p>It has not always been granted in the history of biology,
+and of embryology especially, that production of visible
+manifoldness is the chief feature of what is called an
+organism’s embryology or ontogeny: the eighteenth century
+is full of determined scientific battles over the question.
+One school, with Albert von Haller and Bonnet as its leading
+men, maintained the view that there was no production of
+different parts at all in development, this process being a
+mere “evolutio,” that is, a growth of parts already existing
+from the beginning, yes, from the very beginning of life;
+whilst the other school, with C. F. Wolff and Blumenbach
+at its head, supported the opposite doctrine of so-called
+“epigenesis,” which has been proved to be the right one.</p>
+
+<p>To some extent these differences of opinion were only
+the outcome of the rather imperfect state of the optical
+instruments of that period. But there were also deeper
+reasons beyond mere difficulties of description; there were
+theoretical convictions underlying them. It is <em>impossible</em>,
+said the one party, that there is any real production of new
+parts; there <em>must</em> be such a production, said the other.</p>
+
+<p>We ourselves shall have to deal with these questions of
+the theory of organic development; but at present our
+object is narrower, and merely descriptive. It certainly is
+of great importance to understand most clearly that there
+actually <em>is</em> a “production of visible manifoldness” during<span class="pagenum" title="27"><a name="Page_27" id="Page_27"></a></span>
+ontogenesis in the descriptive sense; the knowledge of the
+fact of this process must be the very foundation of all
+studies on the theory of development in any case, and
+therefore we shall devote this whole lecture to studies in
+merely descriptive embryology.</p>
+
+<p>But descriptive embryology, even if it is to serve merely
+as an instance of the universality of the fact of epigenesis,
+can only be studied successfully with reference to a concrete
+case. We select the development of the common sea-urchin
+(<i class="biological-name">Echinus microtuberculatus</i>) as such a case, and we are
+the more entitled to select this organism rather than another,
+because most of the analytical experimental work, carried
+out in the interests of a real theory of development, has
+been done on the germs of this animal. Therefore, to know
+at least the outlines of the individual embryology of the
+Echinus may indeed be called the <i lang="la" xml:lang="la">conditio sine qua non</i>
+for a real understanding of what is to follow.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Cell</span><a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">3</a></p>
+
+<p>You are aware that all organisms consist of organs and
+that each of their organs has a different function: the brain,
+the liver, the eyes, the hands are types of organs in animals,
+as are the leaves and the pistils in plants.</p>
+
+<p>You are also aware that, except in the lowest organisms,
+the so-called Protista, all organs are built up of cells. That
+is a simple fact of observation, and I therefore cannot agree
+with the common habit of giving to this plain fact the title
+of cell-“theory.” There is nothing theoretical in it; and,<span class="pagenum" title="28"><a name="Page_28" id="Page_28"></a></span>
+on the other hand, all attempts to conceive the organism as
+a mere aggregate of cells have proved to be wrong. It is
+<em>the whole</em> that uses the cells, as we shall see later on, or
+that may not use them: thus there is nothing like a “cell-theory,”
+even in a deeper meaning of the word.</p>
+
+<p>The cell may have the most different forms: take a cell
+of the skin, of a muscle, of a gland, of the wood in plants
+as typical examples. But in every case two parts may be
+distinguished in a cell: an outside part, the protoplasm, and
+an inside part, the nucleus, to leave out of special account
+several others, which, by the way, may only be protoplasmatic
+modifications.</p>
+
+<p>Protoplasm is a mere name for what is not the nucleus;
+in any case it is not a homogeneous chemical compound;
+it consists of many such compounds and has a sort of
+architecture; all organic functions are based upon its
+metabolism. The nucleus has a very typical structure,
+which stands in a close relation to its behaviour during the
+most characteristic morphological period of the cell: during
+its division. Let us devote a few words to a consideration
+of this division and the part the nucleus plays in it; it
+will directly bear on future theoretical considerations about
+development.</p>
+
+<p>There is a certain substance in every nucleus of a cell
+which stains most markedly, whenever cells are treated with
+pigments: the name of “chromatin” has been given to it.
+The chromatin always gives the reaction of an acid, while
+protoplasm is basic; besides that it seems to be a centre of
+oxidation. Now, when a division of a cell is to occur, the
+chromatin, which had been diffusely distributed before, in
+the form of small grains, arranges itself into a long and<span class="pagenum" title="29"><a name="Page_29" id="Page_29"></a></span>
+very much twisted thread. This thread breaks, as it were
+by sections, into almost equal parts, typical in number for
+each species, and each of these parts is split at full length.<span class="pagenum" title="30"><a name="Page_30" id="Page_30"></a></span>
+A certain number of pairs of small threads, the so-called
+“chromosomes,” are the ultimate result of this process,
+which intentionally has been described a little schematically,
+the breaking and the splitting in fact going on simultaneously
+or occasionally even in reverse order. While
+what we have described is performing in the nucleus, there
+have happened some typical modifications in protoplasm, and
+then, by an interaction of protoplasmatic and nuclear factors,
+the first step in the actual division of the cell begins. Of
+each pair of the small threads of chromatin one constituent
+is moved to one side of the cell, one to the other; two
+daughter-nuclei are formed in this way; the protoplasm
+itself at the same time forms a circular furrow between them;
+the furrow gets deeper and deeper; at last it cuts the cell
+in two, and the division of the cell is accomplished.</p>
+
+<p>Not only is the growth of the already typically formed
+organism carried out by a series of cell-divisions, but also
+development proper in our sense, as a “production of visible
+manifoldness,” is realised to a great extent by the aid of
+such divisions, which therefore may indeed be said to be of
+very fundamental importance (Fig. 1).</p>
+
+<div class="figcenter" style="width: 420px;">
+<img src="images/fig01.jpg" width="420" height="460" alt="" />
+<p><span class="smcap">Fig. 1.&mdash;Diagram of Cell-Division</span> (<em>after</em> Boveri).</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Resting cell; the chromatin distributed in the form of small granules inside the nucleus. Outside the nucleus is the “centrosome,” not mentioned in the text.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Beginning of division; the chromatin arranged in the form of a long thread. Centrosome divided in two.</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td class="tal ti">The thread of chromatin cut into four parts, the “chromosomes.”</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">The four parts of the chromatin arranged symmetrically between the centrosomes and the star-like “spheres.”</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Each of the chromosomes split at full length.</td></tr>
+<tr><td class="tar vat"><i>f.</i></td><td class="tal ti">Beginning of division of protoplasm; the two parts of each chromosome separated.</td></tr>
+<tr><td class="tar vat"><i>g.</i></td><td class="tal ti">End of cell-division.</td></tr>
+</table>
+</div>
+
+<p>Each cell-division which promotes growth is followed by
+the enlargement of the two daughter-cells which result from
+it; these two daughter-elements attain the exact size of the
+mother-cell before division, and as soon as this size is reached
+a new division begins: so the growth of the whole is in
+the main the result of the growth of the elements. Cell-divisions
+during real organ-formation may behave differently,
+as will be described at a proper occasion.</p>
+
+<p><span class="pagenum" title="31"><a name="Page_31" id="Page_31"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Egg: its Maturation and Fertilisation</span></p>
+
+<p>We know that all the organs of an animal or plant consist
+of cells, and we know what acts a cell can perform.
+Now there is one very important organ in all living beings,
+which is devoted to reproduction. This organ, the so-called
+ovary in animals, is also built up of cells, and its single cells
+are called the eggs; the eggs originated by cell-division, and
+cell-division is to lead from them to the new adult.</p>
+
+<p>But, with a very few exceptions, the egg in the ovary is
+not able to accomplish its functions, unless certain typical
+events have occurred, some of which are of a merely preparatory
+kind, whilst the others are the actual stimulus
+for development.</p>
+
+<p>The preparatory ones are generally known under the
+name of “maturation.” The egg must be “mature,” in
+order that it may begin development, or even that it may
+be stimulated to it. Maturation consists of a rather complicated
+series of phenomena: later on we shall have
+occasion to mention, at least shortly, what happens in the
+protoplasm during its course; as to the nuclear changes
+during maturation it may be enough for our purposes to say,
+that there occur certain processes among the chromosomes,
+which lead to an extension of half of them in the form of
+two very small cells, the “directive cells” or “directive
+or polar bodies,” as they have been somewhat cautiously
+called.</p>
+
+<p>The ripe or mature egg is capable of being fertilised.</p>
+
+<p>Before turning to this important fact, which, by the way,
+will bring us to our specially chosen type, the Echinus, a
+few words may be devoted to the phenomenon of <span class="pagenum" title="32"><a name="Page_32" id="Page_32"></a></span>“parthenogenesis,”
+that is to say, the possibility of development without
+fertilisation, since owing to the brilliant discoveries of the
+American physiologist, Jacques Loeb, this topic forms one
+of the centres of biological interest at present. It has long
+been known that the eggs of certain bees, lice, crayfishes,
+and other animals and also plants, are capable of development
+without fertilisation at all. Now Richard Hertwig
+and T. H. Morgan already had shown, that at least nuclear
+division may occur in the eggs of other forms&mdash;in the egg of
+the sea-urchin for instance&mdash;when these eggs are exposed to
+some chemical injuries. But <span class="nowrap">Loeb<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">4</a></span> succeeded in obtaining
+a full development by treating the eggs of echinoderms with
+chloride of magnesium; thus artificial parthenogenesis had
+been discovered. Later researches have shown that artificial
+parthenogenesis may occur in all classes of the animal
+kingdom and may be provoked by all sorts of chemical or
+physical means. We do not know at present in what the
+proper stimulus consists that must be supposed here to
+take the place of fertilisation; it seems, of course, highly
+probable that it is always the same in the last <span class="nowrap">resort.<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">5</a></span></p>
+
+<p>But enough about processes, which at present are of a
+highly scientific, but hardly of any philosophic interest.</p>
+
+<p>By fertilisation proper we understand the joining of the
+male element, the spermatozoon or the spermia, with the
+female element, the egg. Like the egg, the spermatozoon is
+but a cell, though the two differ very much from one another<span class="pagenum" title="33"><a name="Page_33" id="Page_33"></a></span>
+in the relation between their protoplasm and nucleus: in all
+eggs it is the protoplasm which is comparatively very large,
+if held together with somatic cells, in the spermatozoon it
+is the nucleus. A large amount of reserve material, destined
+for the growth of the future being, is the chief cause of
+the size of the egg-protoplasm. The egg is quite or almost
+devoid of the faculty of movement, while on the contrary,
+movement is the most typical feature of the spermia. Its
+whole organisation is adapted to movement in the most
+characteristic manner: indeed, most spermatozoa resemble
+a swimming infusorium, of the type of Flagellata, a so-called
+head and a moving tail are their two chief constituents;
+the head is formed almost entirely of nuclear substance.</p>
+
+<p>It seems that in most cases the spermatozoa swim
+around at random and that their union with the eggs is
+assured only by their enormous number; only in a few
+cases in plants have there been discovered special stimuli of
+a chemical nature, which attract the spermia to the egg.</p>
+
+<p>But we cannot enter here more fully into the physiology
+of fertilisation, and shall only remark that its real significance
+is by no means <span class="nowrap">clear.<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">6</a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The First Development Process of Echinus</span></p>
+
+<p>Turning now definitively to the special kind of organism,
+chosen of our type, the common sea-urchin, we properly<span class="pagenum" title="34"><a name="Page_34" id="Page_34"></a></span>
+begin with a few words about the absolute size of its eggs
+and spermatozoa. All of you are familiar with the eggs of
+birds and possibly of frogs; these are abnormally large
+eggs, on account of the very high amount of reserve
+material they contain. The almost spherical egg of our
+Echinus only measures about a tenth of a millimetre in
+diameter; and the head of the spermatozoon has a volume
+which is only the four-hundred-thousandth part of the
+volume of the egg! The egg is about on the extreme limit
+of what can be seen without optical instruments; it is
+visible as a small white point. But the number of eggs
+produced by a single female is enormous and may amount
+to hundreds of thousands; this is one of the properties
+which render the eggs of Echinus so very suitable for
+experimental research; you can obtain them whenever and
+in any quantity you like; and, moreover, they happen to
+be very clear and transparent, even in later stages, and to
+bear all kinds of operations well.</p>
+
+<p>The spermia enters the egg, and it does so in the open
+water&mdash;another of the experimental advantages of our type.
+Only one spermia enters the egg in normal cases, and only
+its head goes in, the tail is left outside. The moment
+that the head has penetrated the protoplasm of the egg a
+thin membrane is formed by the latter. This membrane is
+very soft at first, becoming much stronger later on; it is
+very important for all experimental work, that by shaking
+the egg in the first minutes of its existence the membrane
+can easily be destroyed without any damage to the egg itself.</p>
+
+<p>And now occurs the chief phenomenon of fertilisation:
+the nucleus of the spermatozoon unites with the nucleus of
+the egg. When speaking of maturation, we mentioned that<span class="pagenum" title="35"><a name="Page_35" id="Page_35"></a></span>
+half of the chromatin was thrown out of the egg by that
+process: now this half is brought in again, but comes from
+another individual.</p>
+
+<p>It is from this phenomenon of nuclear union as the
+main character of fertilisation that almost all theories of
+heredity assume their right to regard the nuclei of the
+sexual cells as the true “seat” of inheritance. Later on
+we shall have occasion to discuss this hypothesis from the
+point of view of logic and fact.</p>
+
+<p>After the complete union of what are called the male
+and the female “pronuclei,” the egg begins its development;
+and this development, in its first steps, is simply pure cell-division.
+We know already the chief points of this process,
+and need only add to what has been described, that in the
+whole first series of the cell-divisions of the egg, or, to use
+the technical term, in the whole process of the “cleavage”
+or “segmentation” of it, there is never any growth of the
+daughter-elements after each division, such as we know to
+occur after all cell-divisions of later embryological stages.
+So it happens, that during cleavage the embryonic cells
+become smaller and smaller, until a certain limit is reached;
+the sum of the volumes of all the cleavage cells together
+is equal to the volume of the egg.</p>
+
+<p>But our future studies will require a more thorough
+knowledge of the cleavage of our Echinus; the experimental
+data we shall have to describe later on could hardly be
+properly understood without such knowledge. The first
+division plane, or, as we shall say, the first cleavage plane,
+divides the eggs into equal parts; the second lies at right
+angles to the first and again divides equally: we now have
+a ring of four cells. The third cleavage plane stands at<span class="pagenum" title="36"><a name="Page_36" id="Page_36"></a></span>
+right angles to the first two; it may be called an equatorial
+plane, if we compare the egg with a globe; it also divides
+equally, and so we now find two rings, each consisting of
+four cells, and one above the other. But now the cell-divisions
+cease to be equal, at least in one part of the egg:
+the next division, which leads from the eight- to the
+sixteen-cell stage of cleavage, forms four rings, of four
+cells each, out of the two rings of the eight-cell stage.
+Only in one half of the germ, in which we shall call the upper
+one, or which we might call, in comparison with a globe,
+the northern hemisphere, are cells of equal size to be found;
+in the lower half of the egg four very small cells have been
+formed at one “pole” of the whole germ. We call these
+cells the “micromeres,” that is, the “small parts,” on the
+analogy of the term “blastomeres,” that is, parts of the germ,
+which is applied to all the cleavage cells in general. The
+place occupied by the micromeres is of great importance
+to the germ as a whole: the first formation of real organs
+will start from this point later on. It is sufficient thus
+fully to have studied the cleavage of our Echinus up to
+this stage: the later cleavage stages may be mentioned
+more shortly. All the following divisions are into equal
+parts; there are no other micromeres formed, though, of
+course, the cells derived from the micromeres of the sixteen-cell
+stage always remain smaller than the rest. All the
+divisions are tangential; radial cleavages never occur, and
+therefore the process of cleavage ends at last in the formation
+of one layer of cells, which forms the surface of a
+sphere; it is especially by the rounding-up of each blastomere,
+after its individual appearance, that this real surface
+layer of cells is formed, but, of course, the condition, that<span class="pagenum" title="37"><a name="Page_37" id="Page_37"></a></span>
+no radial divisions occur, is the most important one in its
+formation. When 808 blastomeres have come into existence
+the process of cleavage is finished; a sphere with a wall
+of cells and an empty interior is the result. That only
+808 cells are formed, and not, as might be expected, 1024,
+is due to the fact that the micromeres divide less often
+than the other elements; but speaking roughly, of course,
+we may say that there are ten steps of cleavage-divisions
+in our form; 1024 being equal to 2<sup>10</sup>.</p>
+
+<p>We have learned that the first process of development,
+the cleavage, is carried out by simple cell-division. A few
+cases are known, in which cell-division during cleavage is
+accompanied by a specific migration of parts of the
+protoplasm in the interior of the blastomeres, especially in
+the first two or first four; but in almost all instances
+cleavage is as simple a process of mere division as it is in
+our sea-urchin. Now the second step in development, at
+least in our form, is a typical histological performance: it
+gives a new histological feature to all of the blastomeres:
+they acquire small cilia on their outer side and with these
+cilia the young germ is able to swim about after it has
+left its membrane. The germ may be called a “blastula”
+at this stage, as it was first called by Haeckel, whose
+useful denominations of the first embryonic stages may
+conveniently be applied, even if one does not agree with
+most, or perhaps almost all, of his speculations (Fig. 2).</p>
+
+<div class="figcenter" style="width: 428px;">
+<img src="images/fig02.jpg" width="428" height="337" alt="" />
+<p><span class="smcap">Fig. 2.&mdash;Early Development of Echinus, the Common Sea-urchin.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Two cells.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Four cells.</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td  class="tal ti">Eight cells, arranged in two rings of four, above one another.</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">Sixteen cells, four “micromeres” formed at the “vegetative” pole.</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Optical section of the “blastula,” a hollow sphere consisting of about one thousand cells, each of them with a small cilium.</td></tr>
+</table>
+</div>
+
+<p>It is important to notice that the formation of the
+“blastula” from the last cleavage stage is certainly a
+process of organisation, and may also be called a
+differentiation with regard to that stage. But there is in
+the blastula no trace of one <em>part</em> of the germ becoming<span class="pagenum" title="38"><a name="Page_38" id="Page_38"></a></span>
+different with respect to others of its parts. If development
+were to go on in this direction alone, high organisatory
+complications might occur: but there would always be
+only one sort of cells, arranged in a sphere; there would
+be only one kind of what is called “tissue.”</p>
+
+<p>But in fact development very soon loads to true
+differences of the parts of the germ with respect to one
+another, and the next step of the process will enable us
+to apply different denominations to the different parts of
+the embryo.</p>
+
+<p>At one pole of the swimming blastula, exactly at the
+point where the descendants of the micromeres are situated,<span class="pagenum" title="39"><a name="Page_39" id="Page_39"></a></span>
+about fifty cells lose contact with their neighbours and
+leave the surface of the globe, being driven into the interior
+space of it. Not very much is known about the exact
+manner in which these changes of cellular arrangement
+are carried out, whether the cells are passively pressed by
+their neighbours, or whether, perhaps, in a more active
+manner, they change their surface conditions; therefore,
+as in most ontogenetic processes, the description had best
+be made cautiously in fairly neutral or figurative words.</p>
+
+<p>The cells which in the above manner have entered the
+interior of the blastula are to be the foundation of important
+parts of the future organism; they are to form its connective
+tissue, many of its muscles, and the skeleton. “Mesenchyme,”
+<i>i.e.</i> “what has been infused into the other parts,” is the
+technical name usually applied to these cells. We now
+have to learn their definite arrangement. At first they lie
+as a sort of heap inside the cell wall of the blastula, inside
+the “blastoderm,” <i>i.e.</i> skin of the germ. But soon they
+move from one another, to form a ring round the pole at
+which they entered, and on this ring a process takes place
+which has a very important bearing upon the whole type of
+the organisation of the germ. You will have noticed that
+hitherto the germ with regard to its symmetry has been a
+monaxial or radial formation; the cleavage stages and the
+blastula with its mesenchyme were forms with two different
+poles, lying at the ends of one single line, and round this
+line everything was arranged concentrically. But now
+what is called “bilateral symmetry” is established; the
+mesenchyme ring assumes a structure which can be
+symmetrically divided only by one plane, but divided in
+such a way, that one-half of it is the mirror image of the<span class="pagenum" title="40"><a name="Page_40" id="Page_40"></a></span>
+other. A figure shows best what has occurred, and you will
+notice (Fig. 3) two masses of cells in this figure, which
+have the forms of spherical triangles: it is in the midst of
+these triangles that the skeleton of the larva <em>originates</em>.
+The germ had an upper and a lower side before: it now
+has got an upper and lower, front and back, <em>right and left</em>
+half; it now has acquired that symmetry of organisation
+which our own body has; at least it has got it as far as
+its mesenchyme is concerned.</p>
+
+<div class="figcenter" style="width: 424px;">
+<img src="images/fig03.jpg" width="424" height="250" alt="" />
+<p><span class="smcap">Fig. 3.&mdash;Formation of Mesenchyme in Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i>&nbsp;&nbsp;</td><td class="tal ti">Outlines of blastula, side-view; mesenchyme forms a heap of cells at the “vegetative” pole.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>1</sub>.</td><td class="tal ti">Heap of mesenchyme-cells from above.</td></tr>
+<tr><td class="tar vat"><i>b.</i>&nbsp;&nbsp;</td><td class="tal ti">Mesenchyme-cells arranged in a ring round the vegetative pole.</td></tr>
+<tr><td class="tar vat"><i>c.</i>&nbsp;&nbsp;</td><td class="tal ti">Mesenchyme-cells arranged in a bilateral-symmetrical figure; primordia of skeleton in the midst of two spherical triangles.</td></tr>
+</table>
+</div>
+
+<p>We leave the mesenchyme for a while and study another
+kind of organogenesis. At the very same pole of the germ
+where the mesenchyme cells originated there is a long and
+narrow tube of cell growing in, and this tube, getting longer
+and longer, after a few hours of growth touches the opposite
+pole of the larva. The growth of this cellular tube marks<span class="pagenum" title="41"><a name="Page_41" id="Page_41"></a></span>
+the beginning of the formation of the intestine, with all
+that is to be derived from it. The larva now is no longer
+a blastula, but receives the name of “gastrula” in Haeckel’s
+terminology; it is built up of the three “germ-layers” in
+this stage. The remaining part of the blastoderm is called
+“ectoderm,” or outer layer; the newly-formed tube,
+“endoderm,” or inner layer; while the third layer is the
+“mesenchyme” already known to us.</p>
+
+<p>The endoderm itself is a radial structure at first, as
+was the whole germ in a former stage, but soon its free
+end bends and moves against one of the sides of the
+ectoderm, against that side of it where the two triangles
+of the mesenchyme are to be found also. Thus the endoderm
+has acquired bilateral symmetry just as the mesenchyme
+before, and as in this stage the ectoderm also
+assumes a bilateral symmetry in its form, corresponding
+with the symmetrical relations in the endoderm and the
+mesenchyme, we now may call the whole of our larva a
+bilateral-symmetrical organisation.</p>
+
+<p>It cannot be our task to follow all the points of organogenesis
+of Echinus in detail. It must suffice to state
+briefly that ere long a second portion of the mesenchyme
+is formed in the larva, starting from the free end of
+its intestine tube; that the formation of the so-called
+“coelum” occurs by a sort of splitting off from this same
+original organ; and that the intestine itself is divided
+into three parts of different size and aspect by two circular
+sections.</p>
+
+<p>But we must not, I think, dismiss the formation of the
+skeleton so quickly. I told you already that the skeleton
+has its first origin in the midst of the two triangular<span class="pagenum" title="42"><a name="Page_42" id="Page_42"></a></span>
+cell-masses of the mesenchyme; but what are the steps before
+it attains its typical and complicated structure? At the
+beginning a very small tetrahedron, consisting of carbonate
+of calcium, is formed in each of the triangles; the four edges
+of the tetrahedron are produced into thin rods, and by
+means of a different organogenesis along each of these
+rods the typical formation of the skeleton proceeds. But
+the manner in which it is carried out is very strange
+and peculiar. About thirty of the mesenchyme cells are
+occupied in the formation of skeleton substance on each
+side of the larva. They wander through the interior space of
+the gastrula&mdash;which at this stage is not filled with sea
+water but with a sort of gelatinous material&mdash;and wander
+in such a manner that they always come to the right places,
+where a part of the skeleton is to be formed; they form it
+by a process of secretion, quite unknown in detail; one of
+them forms one part, one the other, but what they form
+altogether, is one whole.</p>
+
+<p>When the formation of the skeleton is accomplished, the
+typical larva of our Echinus is built up; it is called the
+“pluteus” (Fig. 4). Though it is far from being the
+perfect adult animal, it has an independent life of its own;
+it feeds and moves about and does not go through any
+important changes of form for weeks. But after a certain
+period of this species of independent life as a “larva,” the
+changes of form it undergoes again are most fundamental:
+it must be transformed into the adult sea-urchin, as all of
+you know. There are hundreds and hundreds of single
+operations of organogenesis to be accomplished before that
+end is reached; and perhaps the strangest of all these
+operations is a certain sort of growth, by which the symmetry<span class="pagenum" title="43"><a name="Page_43" id="Page_43"></a></span>
+of the animal, at least in certain of its parts&mdash;not in all of
+them&mdash;is changed again from bilateral to radial, just the
+opposite of what happened in the very early stages.</p>
+
+<div class="figcenter" style="width: 392px;">
+<img src="images/fig04.jpg" width="392" height="317" alt="" />
+<p><span class="smcap">Fig. 4.&mdash;Larval Development of Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>A.</i></td><td class="tal ti">The gastrula.</td></tr>
+<tr><td class="tar vat"><i>B.</i></td><td class="tal ti">Later stage, bilateral-symmetrical. Intestine begins to divide into three parts.</td></tr>
+<tr><td class="tar vat"><i>C.</i></td><td class="tal ti">Pluteus larva. S = Skeleton. I = Intestine.</td></tr>
+</table>
+</div>
+
+<p>But we cannot follow the embryology of our Echinus
+further here; and indeed we are the less obliged to do so,
+since in all our experimental work we shall have to deal
+with it only as far as to the pluteus larva. It is impossible
+under ordinary conditions to rear the germs up to the adult
+stages in captivity.</p>
+
+<p>You now, I hope, will have a general idea at least of the
+processes of which the individual development of an animal
+consists. Of course the specific features leading from the
+egg to the adult are different in each specific case, and, in<span class="pagenum" title="44"><a name="Page_44" id="Page_44"></a></span>
+order to make this point as clear as possible, I shall now
+add to our description a few words about what may be
+called a comparative descriptive embryology.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Comparative Embryology</span></p>
+
+<p>Even the cleavage may present rather different aspects.
+There may be a compact blastula, not one surrounded by
+only one layer of cells as in Echinus; or bilaterality may be
+established as early as the cleavage stage&mdash;as in many
+worms and in ascidians&mdash;and not so late as in Echinus.
+The formation of the germ layers may go on in a different
+order and under very different conditions: a rather close
+relative of our Echinus, for instance, the starfish, forms
+first the endoderm and afterwards the mesenchyme. In
+many cases there is no tube of cells forming the “endoderm,”
+but a flat layer of cells is the first foundation of all the
+intestinal organs: so it is in all birds and in the cuttlefish.
+And, as all of you know, of course, there are very many
+animal forms which have no proper “larval” stage: there
+is one in the frog, the well-known “tadpole,” but the birds
+and mammals have no larvae; that is to say, there is no
+special stage in the ontogeny of these forms which leads an
+independent life for a certain time, as if it were a species
+by itself, but all the ontogenetical stages are properly “embryonic”&mdash;the
+germ is always an “embryo” until it becomes
+the perfect young organism. And you also know that not
+all skeletons consist of carbonate of calcium, but, that there
+are skeletons of silicates, as in Radiolaria, and of horny
+substance, as in many sponges. And, indeed, if we were to
+glance at the development of plants also, the differences<span class="pagenum" title="45"><a name="Page_45" id="Page_45"></a></span>
+would seem to us probably so great that all the similarities
+would seem to disappear.</p>
+
+<p>But there are similarities, nevertheless, in all development,
+and we shall now proceed to examine what they are. As
+a matter of fact, it was especially for their sake that we
+studied the ontogeny of a special form in such detail; one
+always sees generalities better if one knows the specific
+features of at least one case. What then are the features
+of most general and far-reaching importance, which may be
+abstracted from the individual history of our sea-urchin,
+checked always by the teachings of other ontogenies, including
+those of plants?</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The First Steps of Analytical Morphogenesis</span></p>
+
+<p>If we look back upon the long fight of the schools of
+embryologists in the eighteenth century about the question
+whether individual development was to be regarded as a real
+production of visible manifoldness or as a simple growth of
+visibly pre-existing manifoldness, whether it was “epigenesis”
+or “evolutio,” there can be no doubt, if we rely
+on all the investigations of the last hundred and fifty years,
+that, taken in the descriptive sense, the theory of epigenesis
+is right. Descriptively speaking there <em>is</em> a production of
+visible manifoldness in the course of embryology: that is
+our first and main result. Any one possessed of an average
+microscope may any day convince himself personally that
+it is true.</p>
+
+<p>In fact, true epigenesis, in the descriptive sense of the
+term, does exist. One thing is formed “after” the other;
+there is not a mere “unfolding” of what existed already,<span class="pagenum" title="46"><a name="Page_46" id="Page_46"></a></span>
+though in a smaller form; there is no “evolutio” in the old
+meaning of the word.</p>
+
+<p>The word “evolution” in English usually serves to denote
+the theory of descent, that is of a real relationship of all
+organisms. Of course we are not thinking here of this
+modern and specifically English meaning of the Latin word
+<i lang="la" xml:lang="la">evolutio</i>. In its ancient sense it means to a certain degree
+just the opposite; it says that there is no formation of anything
+new, no transformation, but simply growth, and this is
+promoted not for the race but for the individual. Keeping
+well in mind these historical differences in the meaning of
+the word “evolutio,” no mistakes, it seems to me, can occur
+from its use. We now shall try to obtain a few more
+particular results from our descriptive study of morphogenesis,
+which are nevertheless of a general bearing, being
+real characteristics of organic individual development, and
+which, though not calculated of themselves to further the
+problem, will in any case serve to prepare for a more
+profound study of it.</p>
+
+<p>The totality of the line of morphogenetic facts can easily
+be resolved into a great number of distinct processes. We
+propose to call these “elementary morphogenetic processes”;
+the turning in of the endoderm and its division into three
+typical parts are examples of them. If we give the name
+“elementary organs” to the distinct parts of every stage of
+ontogeny which are uniform in themselves and are each
+the result of one elementary process in our sense, we are
+entitled to say that each embryological stage consists of a
+certain number of elementary organs. The mesenchyme ring,
+the coelum, the middle-intestine, are instances of such organs.
+It is important to notice well that the word elementary is<span class="pagenum" title="47"><a name="Page_47" id="Page_47"></a></span>
+always understood here with regard to visible morphogenesis
+proper and does not apply to what may be called elementary
+in the physiological sense. An elementary process in our
+sense is a very distinct act of form-building, and an elementary
+organ is the result of every one of such acts.</p>
+
+<p>The elementary organs are typical with regard to their
+position and with regard to their histological properties.
+In many cases they are of a very clearly different histological
+type, as for instance, the cells of the three so-called
+germ-layers; and in other cases, though apparently almost
+identical histologically, they can be proved to be different
+by their different power of resisting injuries or by other
+means. But there are not as many different types of
+histological structure as there are typically placed organs:
+on the contrary there are many elementary organs of the
+same type in different typical parts of the organism, as all
+of you know to be the case with nerves and muscles. It
+will not be without importance for our future theory of
+development, carefully to notice this fact, that specialisation
+in the <em>position</em> of embryonic parts is more strict than
+in their histology.</p>
+
+<p>But elementary organs are not only typical in position
+and histology, they are typical also with regard to their
+form and their relative size. It agrees with what has been
+said about histology being independent of typical position,
+that there may be a number of organs in an embryonic
+stage, all in their most typical positions, which though all
+possessing the same histology, may have different forms or
+different sizes or both: the single bones of the skeleton of
+vertebrates or of adult echinoderms are the very best instances
+of this most important feature of organogenesis. If we look<span class="pagenum" title="48"><a name="Page_48" id="Page_48"></a></span>
+back from elementary organs to elementary processes, the
+specialisation of the size of those organs may also be said to
+be the consequence of a typical duration of the elementary
+morphogenetic process leading to <span class="nowrap">them.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">7</a></span></p>
+
+<p>I hardly need to say, that the histology, form, and size
+of elementary organs are equally an expression of their
+present or future physiological function. At least they
+prepare for this function by a specific sort of metabolism
+which sets in very early.</p>
+
+<p>The whole sequence of individual morphogenesis has
+been divided by some embryologists into two different
+periods; there is a first period, during which the foundations
+of the organisation of the “type” are laid down, and a
+second period, during which the histo-physiological specifications
+are modelled out (von Baer, Götte, Roux). Such a
+discrimination is certainly justified, if not taken too strictly;
+but its practical application would encounter certain
+difficulties in many larval forms, and also, of course, in
+all plants.</p>
+
+<p>Our mention of plants leads us to the last of our
+analytical results. If an animal germ proceeds in its
+development from a stage <i>d</i> to the stage <i>g</i>, passing through
+<i>e</i> and <i>f</i>, we may say that the whole of <i>d</i> has become the
+whole of <i>f</i>, but we cannot say that there is a certain part of
+<i>f</i> which is <i>d</i>, we cannot say that <i>f</i> is <i>d</i> + <i>a</i>. But in plants
+we can: the stage <i>f</i> is indeed equal to <i>a</i> + <i>b</i> + <i>c</i> + <i>d</i> + <i>e</i> + <ins title="Transcriber's Note: ? typo for f "><i>a</i></ins> in vegetable organisms; all earlier stages are actually visible
+as parts of the last one. The great embryologist, Carl Ernst<span class="pagenum" title="49"><a name="Page_49" id="Page_49"></a></span>
+von Baer, most clearly appreciated these analytical differences
+between animal and vegetable morphogenesis. They become
+a little less marked if we remember that plants, in a
+certain respect, are not simple individuals but colonies, and
+that among the corals, hydroids, bryozoa, and ascidia, we
+find analogies to plants in the animal kingdom; but nevertheless
+the differences we have stated are not extinguished
+by such reasoning. It seems almost wholly due to the
+occurrence of so many foldings and bendings and migrations
+of cells and complexes of cells in animal morphogenesis, that
+an earlier stage of their development seems <em>lost</em> in the later
+one; those processes are almost entirely wanting in plants,
+even if we study their very first ontogenetic stages. If we
+say that almost all production of surfaces goes on outside
+in plants, inside in animals, we shall have adequately
+described the difference. And this feature again leads to
+the further diversity between animals and plants which is
+best expressed by calling the former “closed,” the latter
+“open” forms: animals reach a point where they are
+finished, plants never are finished, at least in most cases.</p>
+
+<p>I hope you will allow that I have tried to draw from
+descriptive and comparative embryology as many general
+analytical results as are possibly to be obtained. It is not
+my fault if there are not any more, nor is it my fault if the
+results reached are not of the most satisfactory character.
+You may say that these results perhaps enable you to see a
+little more clearly and markedly than before a few of the
+characters of development, but that you have not really
+learnt anything new. Your disappointment&mdash;my own
+disappointment&mdash;in our analysis is due to the use of pure
+description and comparison as scientific methods.</p>
+
+<p><span class="pagenum" title="50"><a name="Page_50" id="Page_50"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Limits of Pure Description in Science</span></p>
+
+<p>We have analysed our descriptions as far as we could,
+and now we must confess that what we have found cannot
+be the last thing knowable about individual morphogenesis.
+There must be something deeper to be discovered: we only
+have been on the surface of the phenomena, we now want
+to get to the very bottom of them. Why then occurs all
+that folding, and bending, and histogenesis, and all the other
+processes we have described? There must be something
+that drives them out, so to say.</p>
+
+<p>There is a very famous dictum in the <cite>Treatise on
+Mechanics</cite> by the late Gustav Kirchhoff, that it is the task
+of mechanics to describe completely and in the most simple
+manner all the motions that occur in nature. These words,
+which may appear problematic even in mechanics, have
+had a really pernicious influence on biology. People were
+extremely pleased with them. “‘Describing’&mdash;that is just
+what we always have done,” they said; “now we see that we
+have done just what was right; a famous physicist has told
+us so.” They did not see that Kirchhoff had added the
+words “completely and in the most simple manner”; and
+moreover, they did not consider that Kirchhoff never regarded
+it as the ultimate aim of physics to describe thunderstorms
+or volcanic eruptions or denudations; yet it only is with
+such “descriptions” that biological descriptions of <em>given</em>
+bodies and processes are to be compared!</p>
+
+<p>Physicists always have used both experiment and hypothetical
+construction&mdash;Kirchhoff himself did so in the most
+gifted manner. With these aids they have gone through the
+whole of the phenomena, and what they found to be ultimate<span class="pagenum" title="51"><a name="Page_51" id="Page_51"></a></span>
+and truly elemental, that alone may they be said to have
+“described”; but they have “explained” by the aid of
+elementalities what proved to be not elemental in <span class="nowrap">itself.<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">8</a></span></p>
+
+<p>It is the <em>method</em> of the physicists&mdash;not their results&mdash;that
+morphogenesis has to apply in order to make progress;
+and this method we shall begin to apply in our next lectures.
+Physiology proper has never been so short-sighted and self-satisfied
+as not to learn from other sciences, from which
+indeed there was very much to be learned; but morphology
+has: the bare describing and comparing of descriptions has
+been its only aim for about forty years or more, and lines
+of descent of a very problematic character were its only
+general results. It was not seen that science had to begin,
+not with problematic events of the past, but with what
+actually happens before our eyes.</p>
+
+<p>But before saying any more about the exact rational
+and experimental method in morphology, which indeed may
+be regarded as a new method, since its prevalence in the
+eighteenth century had been really forgotten, we first shall
+have to analyse shortly some general attempts to understand
+morphogenesis by means of hypothetic construction exclusively.
+Such attempts have become very important
+as points of issue for really exact research, and, moreover,
+they deserve attention, because they prove that their authors
+at least had not quite forgotten that there were still other
+problems to be solved in morphology than only phylogenetical
+ones.</p>
+
+<hr />
+
+<p><span class="pagenum" title="52"><a name="Page_52" id="Page_52"></a></span></p>
+
+
+
+
+<h3><i>B.</i> EXPERIMENTAL AND THEORETICAL MORPHOGENESIS</h3>
+
+<h4 class="fs120">1. <span class="smcap">The Foundations of the Physiology of Development.<br />
+“Evolutio” and “Epigenesis”</span></h4>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE THEORY OF WEISMANN</span></p>
+
+<p>Of all the purely hypothetic theories on morphogenesis
+that of August <span class="nowrap">Weismann<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">9</a></span> can claim to have had the
+greatest influence, and to be at the same time the most
+logical and the most elaborated. The “germ-plasma”
+theory of the German author is generally considered as
+being a theory of heredity, and that is true inasmuch as
+problems of inheritance proper have been the starting-point
+of all his hypothetic speculations, and also form in some
+respect the most valuable part of them. But, rightly understood,
+Weismann’s theory consists of two independent parts,
+which relate to morphogenesis and to heredity separately,
+and it is only the first which we shall have to take into
+consideration at present; what is generally known as the
+doctrine of the “continuity of the germ-plasm” will be
+discussed in a later chapter.</p>
+
+<p>Weismann assumes that a very complicated organised
+structure, below the limits of visibility even with the<span class="pagenum" title="53"><a name="Page_53" id="Page_53"></a></span>
+highest optical powers, is the foundation of all morphogenetic
+processes, in such a way that, whilst part of this
+structure is handed over from generation to generation as
+the basis of heredity, another part of it is disintegrated
+during the individual development, and directs development
+by being disintegrated. The expression, “part” of the
+structure, first calls for some explanation. Weismann
+supposes several examples, several copies, as it were, of his
+structure to be present in the germ cells, and it is to these
+copies that the word “part” has been applied by us: at least
+one copy has to be disintegrated during ontogeny.</p>
+
+<p>The morphogenetic structure is assumed to be present in
+the nucleus of the germ cells, and Weismann supposes
+the disintegration of his hypothetic structure to be accomplished
+by nuclear division. By the cleavage of the egg,
+the most <em>fundamental</em> parts of it are separated one from
+the other. The word “fundamental” must be understood
+as applying not to proper elements or complexes of
+elements of the organisation, but to the chief relations
+of symmetry; the first cleavage, for instance, may separate
+the right and the left part of the structure, the second one
+its upper and lower parts, and after the third or equatorial
+cleavage all the principal eighths of our minute organisation
+are divided off: for the minute organisation, it must
+now be added, had been supposed to be built up differently
+in the three directions of space, just as the adult organism
+is. Weismann concedes it to be absolutely unknown in
+what manner the proper relation between the parts of the
+disintegrated fundamental morphogenetic structure and the
+real processes of morphogenesis is realised; enough that there
+may be imagined such a relation.</p>
+
+<p><span class="pagenum" title="54"><a name="Page_54" id="Page_54"></a></span></p>
+
+<p>At the end of organogenesis the structure is assumed to
+have been broken up into its elements, and these elements,
+which may be chemical compounds, determine the fate of
+the single cells of the adult organism.</p>
+
+<p>Here let us pause for a moment. There cannot be any
+doubt that Weismann’s theory resembles to a very high
+degree the old “evolutio” doctrines of the eighteenth
+century, except that it is a little less crude. The chick itself
+is not supposed to be present in the hen’s egg before development,
+and ontogeny is not regarded as a mere growth of
+that chick in miniature, but what really is supposed to be
+present in the egg is nevertheless a something that in all its
+parts corresponds to all the parts of the chick, only under
+a somewhat different aspect, while all the relations of the
+parts of the one correspond to the relations of the parts
+of the other. Indeed, only on such an hypothesis of a
+fairly fixed and rigid relation between the parts of the
+morphogenetic structure could it be possible for the
+disintegration of the structure to go on, not by parts of
+organisation, but by parts of symmetry; which, indeed, is
+a very strange, but not an illogical, feature of Weismann’s
+doctrine.</p>
+
+<p>Weismann is absolutely convinced that there must be
+a theory of “evolutio,” in the old sense of the word, to
+account for the ontogenetic facts; that “epigenesis” has its
+place only in descriptive embryology, where, indeed, as we
+know, manifoldness in the <em>visible</em> sense is produced, but
+that epigenesis can never form the foundation of a real
+morphogenetic <em>theory</em>: theoretically one pre-existing manifoldness
+is transformed into the other. An epigenetic
+theory would lead right beyond natural science, Weismann<span class="pagenum" title="55"><a name="Page_55" id="Page_55"></a></span>
+thinks, as in fact, all such theories, if fully worked out,
+have carried their authors to vitalistic views. But vitalism
+is regarded by him as dethroned for ever.</p>
+
+<p>Under these circumstances we have a good right, it
+seems to me, to speak of a <em>dogmatic</em> basis of Weismann’s
+theory of development.</p>
+
+<p>But to complete the outlines of the theory itself:
+Weismann was well aware that there were some grave
+difficulties attaching to his statements: all the facts of
+so-called adventitious morphogenesis in plants, of regeneration
+in animals, proved that the morphogenetic organisation could
+not be fully disintegrated during ontogeny. But these
+difficulties were not absolute: they could be overcome:
+indeed, Weismann assumes, that in certain specific cases&mdash;and
+he regarded all cases of restoration of a destroyed
+organisation as due to specific properties of the subjects,
+originated by roundabout variations and natural selection&mdash;that
+in specific cases, specific arrangements of minute
+parts were formed during the process of disintegration, and
+were surrendered to specific cells during development, from
+which regeneration or adventitious budding could originate
+if required. “Plasma of reserve” was the name bestowed
+on these hypothetic arrangements.</p>
+
+<p>Almost independently another German author, Wilhelm
+<span class="nowrap">Roux,<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">10</a></span> has advocated a theoretical view of morphogenesis
+which very closely resembles the hypothesis of Weismann.
+According to Roux a minute ultimate structure is present
+in the nucleus of the germ and directs development by being
+divided into its parts during the series of nuclear divisions.</p>
+
+<p>But in spite of this similarity of the outset, we enter an<span class="pagenum" title="56"><a name="Page_56" id="Page_56"></a></span>
+altogether different field of biological investigation on
+mentioning Roux’s name: we are leaving hypothetic construction,
+at least in its absoluteness, and are entering the
+realms of scientific experiment in morphology.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">EXPERIMENTAL MORPHOLOGY</span></p>
+
+<p>I have told you already in the last lecture that, while
+in the eighteenth century individual morphogenesis had
+formed the centre of biological interest and been studied
+experimentally in a thoroughly adequate manner, that
+interest gradually diminished, until at last the physiology
+of form as an exact separate science was almost wholly
+forgotten. At least that was the state of affairs as regards
+zoological biology; botanists, it must be granted, have never
+lost the historical continuity to such a degree; botany has
+never ceased to be regarded as one science and never was
+broken up into parts as zoology was. Zoological physiology
+and zoological morphology indeed were for many years in a
+relationship to one another not very much closer than the
+relation between philology and chemistry.</p>
+
+<p>There were always a few men, of course, who strove
+against the current. The late Wilhelm <span class="nowrap">His,<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">11</a></span> for instance,
+described the embryology of the chick in an original
+manner, in order to find out the mechanical relations of
+embryonic parts, by which passive deformation, as an
+integrating part of morphogenesis, might be induced. He
+also most clearly stated the ultimate aim of embryology to
+be the mathematical derivation of the adult form from the
+distribution of growth in the germ. To Alexander <span class="nowrap">Goette<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">12</a></span><span class="pagenum" title="57"><a name="Page_57" id="Page_57"></a></span>
+we owe another set of analytical considerations about
+ontogeny. Newport, as early as 1850, and in later years
+Pflüger and Rauber, carried out experiments on the eggs of
+the frog, which may truly be called anticipatory of what
+was to follow. But it was Wilhelm <span class="nowrap">Roux,<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">13</a></span> now professor
+of anatomy at Halle, who entered the field with a thoroughly
+elaborated programme, who knew not only how to state the
+problem analytically, but also how to attack it, fully
+convinced of the importance of what he did. “Entwickelungsmechanik,”&mdash;mechanics
+of development&mdash;he called the “new
+branch of anatomical science” of which he tried to lay the
+foundations.</p>
+
+<p>I cannot let this occasion pass without emphasising in
+the most decided manner how highly in my opinion
+Roux’s services to the systematic exploration of morphogenesis
+must be esteemed. I feel the more obliged to do
+so, because later on I shall have to contradict not only
+many of his positive statements but also most of his
+theoretical views. He himself has lately given up much of
+what he most strongly advocated only ten years ago. But
+Roux’s place in the history of biological science can never
+be altered, let science take what path it will.</p>
+
+<p>It is not the place here to develop the logic of
+experiment; least of all is it necessary in the country
+of John Stuart Mill. All of you know that experiment, by
+its method of isolating the single constituents of complicated
+phenomena, is the principal aid in the discovery of so-called
+causal relations. Let us try then to see what causal<span class="pagenum" title="58"><a name="Page_58" id="Page_58"></a></span>
+relations Wilhelm Roux established with the aid of
+morphogenetic experiment.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE WORK OF WILHELM ROUX</span></p>
+
+<p>We know already that an hypothesis about the foundation
+of individual development was his starting-point. Like
+Weismann he supposed that there exists a very complicated
+structure in the germ, and that nuclear division leads to
+the disintegration of that structure. He next tried to
+bring forward what might be called a number of indicia
+supporting his view.</p>
+
+<p>A close relation had been found to exist in many cases
+between the direction of the first cleavage furrows of the
+germ and the direction of the chief planes of symmetry
+in the adult: the first cleavage, for instance, very often
+corresponds to the median plane, or stands at right
+angles to it. And in other instances, such as have been
+worked out into the doctrine of so-called “cell-lineages,”
+typical cleavage cells were found to correspond to typical
+organs. Was not that a strong support for a theory which
+regarded cellular division as the principal means of
+differentiation? It is true, the close relations between
+cleavage and symmetry did not exist in every case, but
+then there had always happened some specific experimental
+disturbances, <i>e.g.</i> influences of an abnormal direction of
+gravity on account of a turning over of the egg, and it
+was easy to reconcile such cases with the generally accepted
+theory on the assumption of what was called “anachronism”
+of cleavage.</p>
+
+<p>But Roux was not satisfied with mere indicia, he<span class="pagenum" title="59"><a name="Page_59" id="Page_59"></a></span>
+wanted a proof, and with this intention he carried out
+an experiment which has become very <span class="nowrap">celebrated.<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">14</a></span> With a
+hot needle he killed one of the first two blastomeres of
+the frog’s egg after the full accomplishment of its first
+cleavage, and then watched the development of the surviving
+cell. A typical half-embryo was seen to emerge&mdash;an organism
+indeed, which was as much a half as if a fully formed
+embryo of a certain stage had been cut in two by a razor.
+It was especially in the anterior part of the embryo that
+its “halfness” could most clearly be demonstrated.</p>
+
+<p>That seemed to be a proof of Weismann’s and Roux’s
+theory of development, a proof of the hypothesis that there
+is a very complicated structure which promotes ontogeny
+by its disintegration, carried out during the cell divisions
+of embryology by the aid of the process of nuclear division,
+the so-called “karyokinesis.”</p>
+
+<p>To the dispassionate observer it will appear, I suppose,
+that the conclusions drawn by Roux from his experiment
+go a little beyond their legitimate length. Certainly some
+sort of “evolutio” is proved by rearing half the frog from
+half the egg. But is anything proved, is there anything
+discovered at all about the nucleus? It was only on
+account of the common opinion about the part it played
+in morphogenesis that the nucleus had been taken into
+consideration.</p>
+
+<p>Things soon became still more ambiguous.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE EXPERIMENTS ON THE EGG OF THE SEA-URCHIN</span></p>
+
+<p>Roux’s results were published for the first time in
+1888; three years later I tried to repeat his fundamental<span class="pagenum" title="60"><a name="Page_60" id="Page_60"></a></span>
+experiment on another subject and by a somewhat different
+method. It was known from the cytological researches
+of the brothers Hertwig and Boveri that the eggs of the
+common sea-urchin (<i class="biological-name">Echinus microtuberculatus</i>) are able to
+stand well all sorts of rough treatment, and that, in
+particular, when broken into pieces by shaking, their fragments
+will survive and continue to segment. I took
+advantage of these facts for my purposes. I shook the
+germs rather violently during their two-cell stage, and in
+several instances I succeeded in killing one of the blastomeres,
+while the other one was not damaged, or in separating
+the two blastomeres from one <span class="nowrap">another.<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">15</a></span></p>
+
+<p>Let us now follow the development of the isolated
+surviving cell. It went through cleavage just as it would
+have done in contact with its sister-cell, and there occurred
+cleavage stages which were just half of the normal ones.
+The stage, for instance, which corresponded to the normal
+sixteen-cell stage, and which, of course, in my subjects was
+built up of eight elements only, showed two micromeres, two
+macromeres and four cells of medium size, exactly as if a
+normal sixteen-cell stage had been cut in two; and the form
+of the whole was that of a hemisphere. So far there was
+no divergence from Roux’s results.</p>
+
+<p>The development of our Echinus proceeds rather rapidly,
+the cleavage being accomplished in about fifteen hours. I
+now noticed on the evening of the first day of the experiment,
+when the half-germ was composed of about two hundred elements,
+that the margin of the hemispherical germ bent together
+a little, as if it were about to form a whole sphere of smaller
+size, and, indeed, the next morning a <em>whole</em> diminutive<span class="pagenum" title="61"><a name="Page_61" id="Page_61"></a></span>
+blastula was swimming about. I was so much convinced
+that I should get Roux’s morphogenetical result in all its
+features that, even in spite of this whole blastula, I now
+expected that the next morning would reveal to me the
+half-organisation of my subject once more; the intestine, I
+supposed, might come out quite on one side of it, as a half-tube,
+and the mesenchyme ring might be a half one also.</p>
+
+<p>But things turned out as they were bound to do and
+not as I had expected; there was a typically <em>whole</em> gastrula
+on my dish the next morning, differing only by its small
+size from a normal one; and this <em>small but whole</em> gastrula
+was followed by a whole and typical small pluteus-larva
+(Fig. 5).</p>
+
+<div class="figcenter" style="width: 460px;">
+<img src="images/fig05.jpg" width="460" height="320" alt="" />
+<p><span class="smcap">Fig. 5.&mdash;Illustration of Experiments on Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sub>1</sub>&nbsp;and&nbsp;<i>b</i><sub>1</sub>.</td><td class="tal ti">Normal gastrula and normal pluteus.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>2</sub>&nbsp;and&nbsp;<i>b</i><sub>2</sub>.</td><td class="tal ti">“Half”-gastrula and “half”-pluteus, that <em>ought</em> to result from one of the first two blastomeres, when isolated, according to the theory of “evolutio.”</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>3</sub>&nbsp;and&nbsp;<i>b</i><sub>3</sub>.</td><td class="tal ti">The small <em>but whole</em> gastrula and pluteus that actually <em>do</em> result.</td></tr>
+</table>
+</div>
+
+<p>That was just the opposite of Roux’s result: one of the
+first two blastomeres had undergone a half-cleavage as in
+his case, but then it had become a whole organism by a
+simple process of rearrangement of its material, without
+anything that resembled regeneration, in the sense of a
+completion by budding from a wound.</p>
+
+<p>If one blastomere of the two-cell stage was thus capable
+of performing the morphogenetical process in its totality,
+it became, of course, <em>impossible</em> to allow that nuclear
+division had separated any sort of “germ-plasm” into two
+different halves, and not even the protoplasm of the egg
+could be said to have been divided by the first cleavage
+furrow into unequal parts, as the postulate of the strict
+theory of so-called “evolutio” had been. This was a very
+important result, sufficient alone to overthrow at once the
+theory of ontogenetical “evolutio,” the “Mosaiktheorie” as
+it had been called&mdash;not by Roux himself, but according to
+his views&mdash;in its exclusiveness.</p>
+
+<p><span class="pagenum" title="62"><a name="Page_62" id="Page_62"></a></span></p>
+
+<p>After first widening the circle of my observations by
+showing that one of the first four blastomeres is capable
+of performing a whole organogenesis, and that three of
+the first four blastomeres together result in an absolutely
+perfect organism, I went on to follow up separately one of
+the two fundamental problems which had been suggested
+by my first experiment: was there anything more to find
+out about the importance or unimportance of the single
+<em>nuclear</em> divisions in <span class="nowrap">morphogenesis?<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">16</a></span></p>
+
+<p>By raising the temperature of the medium or by diluting
+the sea-water to a certain degree it proved at first to be
+possible to alter in a rather fundamental way the type of<span class="pagenum" title="63"><a name="Page_63" id="Page_63"></a></span>
+the cleavage-stages without any damage to the resulting
+organism. There may be no micromeres at the sixteen-cell
+stage, or they may appear as early as in the stage of eight
+cells; no matter, the larva is bound to be typical. So it
+certainly is not necessary for all the cleavages to occur
+just in their normal order.</p>
+
+<p>But of greater importance for our purposes was what
+followed. I succeeded in pressing the eggs of Echinus
+between two glass plates, rather tightly, but without killing
+them; the eggs became deformed to comparatively flat
+plates of a large diameter. Now in these eggs all nuclear
+division occurred at right angles to the direction of pressure,
+that is to say, in the direction of the plates, as long as
+the pressure lasted; but the divisions began to occur at
+right angles to their former direction, as soon as the
+pressure ceased. By letting the pressure be at work for
+different times I therefore, of course, had it quite in my
+power to obtain cleavage types just as I wanted to get
+them. If, for instance, I kept the eggs under pressure
+until the eight-cell stage was complete, I got a plate of eight
+cells one beside the other, instead of two rings, of four
+cells each, one above the other, as in the normal case; but
+the next cell division occurred at right angles to the former
+ones, and a sixteen-cell stage, of two plates of eight cells
+each, one above the other, was the result. If the pressure
+continued until the sixteen-cell stage was reached, sixteen
+cells lay together in one plate, and two plates of sixteen
+cells each, one above the other, were the result of the next
+cleavage.</p>
+
+<p>We are not, however, studying these things for
+cytological, but for morphogenetical purposes, and for these<span class="pagenum" title="64"><a name="Page_64" id="Page_64"></a></span>
+the cleavage phenomenon itself is less important than the
+organogenetic result of it: all our subjects resulted in
+<em>absolutely normal</em> organisms. Now, it is clear, that the
+spatial relations of the different nuclear divisions to each
+other are anything but normal, in the eggs subjected to the
+pressure experiments; that, so to say, every nucleus has got
+quite different neighbours if compared with the “normal”
+case. If that makes no difference, then there <em>cannot</em>
+exist any close relation between the single nuclear divisions
+and organogenesis at all, and the conclusion we have drawn
+more provisionally from the whole development of isolated
+blastomeres has been extended and proved in the most
+perfect manner. There ought to result a morphogenetic
+chaos according to the theory of real “evolutio” carried
+out by nuclear division, if the positions of the single nuclei
+were fundamentally changed with regard to one another<span class="pagenum" title="65"><a name="Page_65" id="Page_65"></a></span>
+(Fig. 6). But now there resulted not chaos, but the normal
+organisation: therefore it was disproved in the strictest way
+that nuclear divisions have any bearing on the origin
+of organisation; at least as far as the divisions during
+cleavage come into account.</p>
+
+<div class="figcenter" style="width: 444px;">
+<img src="images/fig06.jpg" width="444" height="250" alt="" />
+<p><span class="smcap">Fig. 6.&mdash;Pressure-experiments on Echinus.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sub>1</sub>&nbsp;and&nbsp;<i>b</i><sub>1</sub>.</td><td class="tal ti">Two normal cleavage stages, consisting of eight and sixteen cells.</td></tr>
+<tr><td class="tar vat"><i>a</i><sub>2</sub>&nbsp;and&nbsp;<i>b</i><sub>2</sub>.</td><td class="tal ti">Corresponding stages modified by exerting pressure until the eight-cell stage was finished. See text.</td></tr>
+</table>
+</div>
+
+<p>On the egg of the frog (O. Hertwig), and on the egg of
+annelids (E. B. Wilson), my pressure experiments have been
+carried out with the same <span class="nowrap">result.<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">17</a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON THE INTIMATE STRUCTURE OF THE PROTOPLASM OF THE
+GERM</span></p>
+
+<p>Nuclear division, as we have seen, cannot be the basis
+of organogenesis, and all we know about the whole development
+of isolated blastomeres seems to show that there
+exists nothing responsible for differentiation in the protoplasm
+either.</p>
+
+<p>But would that be possible? It cannot appear possible
+on a more profound consideration of the nature of morphogenesis,
+it seems to me: as the untypical agents of the
+medium cannot be responsible in any way for the origin
+of a form combination which is most typical and specific,
+there must be somewhere in the egg itself a certain factor
+which is responsible at least for the general orientation
+and symmetry of it. Considerations of this kind led me,
+as early as <span class="nowrap">1893,<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">18</a></span> to urge the hypothesis that there<span class="pagenum" title="66"><a name="Page_66" id="Page_66"></a></span>
+existed, that there <em>must</em> exist, a sort of intimate structure
+in the egg, including polarity and bilaterality as the chief
+features of its symmetry, a structure which belongs to
+every smallest element of the egg, and which might be
+imagined by analogy under the form of elementary <span class="nowrap">magnets.<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">19</a></span>
+This hypothetic structure could have its seat in the protoplasm
+only. In the egg of echinoderms it would be capable
+of such a quick rearrangement after being disturbed, that
+it could not be observed but only inferred logically; there
+might, however, be cases in which its real discovery would
+be possible. Indeed Roux’s frog-experiment seems to be
+a case where it is found to be at work: at least it seems
+very probable to assume that Roux obtained half of a
+frog’s embryo because the protoplasm of the isolated blastomere
+had preserved the “halfness” of its intimate structure,
+and had not been able to form a small whole out of it.</p>
+
+<p>Of course it was my principal object to verify this
+hypothesis, and such verification became possible in a set
+of experiments which my friend T. H. Morgan and myself
+carried out <span class="nowrap">together,<a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">20</a></span> in 1895, on the eggs of ctenophores,
+a sort of pelagic animals, somewhat resembling the jelly-fish,
+but of a rather different inner organisation. The
+zoologist Chun had found even before Roux’s analytical
+studies, that isolated blastomeres of the ctenophore egg
+behave like parts of the whole and result in a half-organisation
+like the frog’s germ does. Chun had not laid much
+stress on his discovery, which now, of course, from the new
+points of view, became a very important one. We first
+repeated Chun’s experiment and obtained his results, with<span class="pagenum" title="67"><a name="Page_67" id="Page_67"></a></span>
+the sole exception that there was a tendency of the
+endoderm of the half-larva of Beroë to become more than
+“half.” But that was not what we chiefly wanted to
+study. We succeeded in cutting away a certain mass of
+the protoplasm of the ctenophore egg just before it began to
+cleave, without damaging its nuclear material in any way:
+in all cases, where the cut was performed at the side, there
+resulted a certain type of larvae from our experiments which
+showed exactly the same sort of defects as were present in
+larvae developed from one of the first two blastomeres
+alone.</p>
+
+<p>The hypothesis of the morphogenetic importance of
+<em>protoplasm</em> had thus been proved. In our experiments
+there was all of the nuclear material, but there were
+defects on one side of the protoplasm of the egg; and the
+defects in the adult were found to correspond to these
+defects in the protoplasm.</p>
+
+<p>And now O. Schultze and Morgan succeeded in performing
+some experiments which directly proved the
+hypothesis of the part played by protoplasm in the subject
+employed by Roux, <i>viz.</i>, the frog’s egg. The first of these
+investigators managed to rear two whole frog embryos of
+small size, if he slightly pressed the two-cell stage of that
+form between two plates of glass and turned it over; and
+<span class="nowrap">Morgan,<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">21</a></span> after having killed one of the first two blastomeres,
+as was done in the original experiment of Roux, was able
+to bring the surviving one to a half or to a whole development
+according as it was undisturbed or turned. There
+cannot be any doubt that in both of these cases, it is the
+possibility of a rearrangement of protoplasm, offered by<span class="pagenum" title="68"><a name="Page_68" id="Page_68"></a></span>
+the turning over, which allows the isolated blastomere to
+develop as a whole. The regulation of the frog’s egg, with
+regard to its becoming whole, may be called facultative,
+whilst the same regulation of the egg of Echinus is
+obligatory. It is not without interest to note that the
+first two blastomeres of the common newt, <i>i.e.</i> of a form
+which belongs to the other class of Amphibia, after a
+separation of <em>any</em> kind, <em>always</em> develop as wholes, their
+faculty of regulation being obligatory, like that of Echinus.</p>
+
+<p>Whole or partial development may thus be dependent
+on the power of regulation contained in the intimate polar-bilateral
+structure of the protoplasm. Where this is so,
+the regulation and the differences in development are both
+connected with the chief relations of symmetry. The
+development becomes a half or a quarter of the normal
+because there is only one-half or one-quarter of a certain
+structure present, one-half or one-quarter with regard
+to the very wholeness of this structure; the development
+is whole, in spite of disturbances, if the intimate
+structure became whole first. We may describe the
+“wholeness,” “halfness,” or “quarterness” of our hypothetic
+structure in a mathematical way, by using three axes, at
+right angles to one another, as the base of orientation. To
+each of these, <i>x</i>, <i>y</i>, and <i>z</i>, a certain specific state with
+regard to the symmetrical relations corresponds; thence
+it follows that, if there are wanting all those parts of the
+intimate structure which are determined, say, by a negative
+value of <i>y</i>, by minus <i>y</i>, then there is wanting half of the intimate
+structure; and this halfness of the intimate structure
+is followed by the halfness of organogenesis, the dependence
+of the latter on the intimate structure being established.<span class="pagenum" title="69"><a name="Page_69" id="Page_69"></a></span>
+But if regulation has restored, on a smaller scale, the whole
+of the arrangement according to all values of <i>x</i>, <i>y</i> and <i>z</i>,
+development also can take place completely (Fig. 7).</p>
+
+<div class="figcenter" style="width: 368px;">
+<img src="images/fig07.jpg" width="368" height="383" alt="" />
+<p><span class="smcap">Fig. 7.&mdash;Diagram illustrating the intimate Regulation of Protoplasm from
+“Half” to “Whole.”</span></p>
+
+<p>The large circle represents the original structure of the egg. In all cases where cleavage-cells
+of the two-cell stage are isolated this original structure is only present as
+“half” in the beginning, say only on the right (+<i>y</i>) side. Development then
+becomes “half,” if the intimate structure remains half; but it becomes “whole”
+(on a smaller scale) if a new whole-structure (small circle!) is formed by regulatory
+processes.</p>
+</div>
+
+<p>I am quite aware that such a discussion is rather empty
+and purely formal, nevertheless it is by no means without
+value, for it shows most clearly the differences between what
+we have called the intimate structure of germs, responsible<span class="pagenum" title="70"><a name="Page_70" id="Page_70"></a></span>
+only for the general symmetry of themselves and of their
+isolated parts, and another sort of possible structure of
+the egg-protoplasm which we now shall have to consider,
+and which, at the first glance, seems to form a serious
+difficulty to our statements, as far at least as they claim
+to be of general importance. The study of this other sort
+of germinal structure at the same time will lead us a
+step farther in our historical sketch of the first years of
+“Entwickelungsmechanik” and will bring this sketch to
+its end.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON SOME SPECIFICITIES OF ORGANISATION IN CERTAIN GERMS</span></p>
+
+<p>It was known already about 1890, from the careful
+study of what has been called “cell-lineage,” that in the
+eggs of several families of the animal kingdom the origin
+of certain organs may be traced back to individual cells of
+cleavage, having a typical histological character of their own.
+In America especially such researches have been carried
+out with the utmost minuteness, E. B. Wilson’s study of
+the cell-lineage of the Annelid <i class="biological-name">Nereis</i> being the first of
+them. If it were true that nuclear division is of no
+determining influence upon the ontogenetic fate of the
+blastomeres, only peculiarities of the different parts of
+the protoplasm could account for such relations of special
+cleavage cells to special organs. I advocated this view
+as early as in 1894, and it was proved two years later by
+Crampton, a pupil of Wilson’s, in some very fine experiments
+performed on the germ of a certain <span class="nowrap">mollusc.<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">22</a></span> The
+egg of this form contains a special sort of protoplasm near<span class="pagenum" title="71"><a name="Page_71" id="Page_71"></a></span>
+its vegetative pole, and this part of it is separated at each
+of the first two segmentations by a sort of pseudo-cleavage,
+leading to stages of three and five separated masses instead
+of two and four, the supernumerary mass being the so-called
+“yolk-sac” and possessing no nuclear elements
+(Fig. 8). Crampton removed this yolk-sac at the two-cell
+stage, and he found that the cleavage of the germs thus
+operated upon was normal except with regard to the size
+and histological appearance of one cell, and that the larvae
+originating from these germs were complete in every respect
+except in their mesenchyme, which was wanting. A special
+part of the protoplasm of the egg had thus been brought
+into relation with quite a special part of organisation, <em>and
+that special part of the protoplasm contained no nucleus</em>.</p>
+
+<div class="figcenter" style="width: 376px;">
+<img src="images/fig08.jpg" width="376" height="185" alt="" />
+<p><span class="smcap">Fig. 8.&mdash;The Mollusc Dentalium</span> (<em>after</em> E. B. Wilson).</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">The egg, consisting of three different kinds of protoplasmatic material.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">First cleavage-stage. There are two cells and one “pseudo-cell,” the yolk-sac, which contains no nucleus. This was removed in Crampton’s experiment.</td></tr>
+</table>
+</div>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">GENERAL RESULTS OF THE FIRST PERIOD OF
+“ENTWICKELUNGSMECHANIK”</span></p>
+
+<p>This experiment of Crampton’s, afterwards confirmed by
+Wilson himself, may be said to have closed the first period<span class="pagenum" title="72"><a name="Page_72" id="Page_72"></a></span>
+of the new science of physiology of form, a period devoted
+almost exclusively to the problem whether the theory of
+nuclear division or, in a wider sense, whether the theory of
+a strict “evolutio” as the basis of organogenesis was true
+or not.</p>
+
+<p>It was shown, as we have seen, that the theory of the
+“qualitatively unequal nuclear division” (“qualitativ-ungleiche
+Kernteilung” in German) certainly was not true,
+and that there also was no strict “evolutio” in protoplasm.
+Hence Weismann’s theory was clearly disproved. There
+certainly is a good deal of real “epigenesis” in ontogeny,
+a good deal of “production of manifoldness,” not only with
+regard to visibility but in a more profound meaning. But
+some sort of pre-formation had also been proved to exist,
+and this pre-formation, or, if you like, this restricted
+evolution, was found to be of two different kinds. First
+an intimate organisation of the protoplasm, spoken of as
+its polarity and bilaterality, was discovered, and this had
+to be postulated for every kind of germs, even when it
+was overshadowed by immediate obligatory regulation after
+disturbances. Besides that there were cases in which a
+real specificity of special parts of the germ existed, a relation
+of these special parts to special organs: but this sort of
+specification also was shown to belong to the protoplasm.</p>
+
+<p>It follows from all we have mentioned about the
+organisation of protoplasm and its bearing on morphogenesis,
+that the eggs of different animals may behave rather
+differently, in this respect, and that the eggs indeed may
+be classified according to the degree of their organisation.
+Though we must leave a detailed discussion of these topics
+to morphology proper, we yet shall try shortly to summarise<span class="pagenum" title="73"><a name="Page_73" id="Page_73"></a></span>
+what has been ascertained about them in the different
+classes of the animal kingdom. A full regulation of the
+<em>intimate</em> structure of isolated blastomeres to a new whole,
+has been proved to exist in the highest degree in the
+eggs of all echinoderms, medusae, nemertines, Amphioxus,
+fishes, and in one class of the Amphibia (the <i class="biological-name">Urodela</i>); it
+is facultative only among the other class of Amphibia, the
+<i class="biological-name">Anura</i>, and seems to be only partly developed or to be
+wanting altogether among ctenophora, ascidia, annelids,
+and mollusca. Peculiarities in the organisation of <em>specific
+parts</em> of protoplasm have been proved to occur in more cases
+than at first had been assumed; they exist even in the
+echinoderm egg, as experiments of the last few years have
+shown; even here a sort of specification exists at the
+vegetative pole of the egg, though it is liable to a certain
+kind of regulation; the same is true in medusae,
+nemertines, etc.; but among molluscs, ascidians, and
+annelids no regulation about the specific organisation of
+the germ in cleavage has been found in any case.</p>
+
+<p>The differences in the degree of regulability of the
+intimate germinal structure may easily be reduced to
+simple differences in the physical consistency of their
+<span class="nowrap">protoplasm.<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">23</a></span> But all differences in specific organisation
+must remain as they are for the present; it will be one
+of the aims of the future theory of development to trace
+these differences also to a common source.</p>
+
+<p>That such an endeavour will probably be not without
+success, is clear, I should think, from the mere fact that<span class="pagenum" title="74"><a name="Page_74" id="Page_74"></a></span>
+differences with regard to germinal specific pre-formation
+do not agree in any way with the systematic position of
+the animals exhibiting them; for, strange as it would be
+if there were two utterly different kinds of morphogenesis,
+it would be still more strange if there were differences
+in morphogenesis which were totally unconnected with
+systematic relationship: the ctenophores behaving differently
+from the medusae, and Amphioxus differently from ascidians.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">SOME NEW RESULTS CONCERNING RESTITUTIONS</span></p>
+
+<p>We now might close this chapter, which has chiefly
+dealt with the disproof of a certain sort of ontogenetic
+theories, and therefore has been almost negative in its
+character, did it not seem desirable to add at least a few
+words about the later discoveries relating to morphogenetic
+restorations of the adult. We have learnt that Weismann
+created his concept of “reserve plasma” to account for
+what little he knew about “restitutions”: that is, about the
+restoration of lost parts: he only knew regeneration proper
+in animals and the formation of adventitious buds in plants.
+It is common to both of these phenomena that they take
+their origin from typically localised points of the body in
+every case; each time they occur a certain well-defined
+part of the body is charged with the restoration of the lost
+parts. To explain such cases Weismann’s hypothesis was
+quite adequate, at least in a logical sense. But at present,
+as we shall discuss more fully in another chapter, we know
+of some very widespread forms of restitution, in which
+what is to be done for a replacement of the lost is not
+entrusted to <em>one</em> typical part of the body in every case,<span class="pagenum" title="75"><a name="Page_75" id="Page_75"></a></span>
+but in which the whole of the morphogenetic action to be
+performed is transferred in its <em>single</em> parts to the <em>single</em>
+parts of the body which is accomplishing restoration: each
+of its parts has to take an individual share in the process
+of restoration, effecting what is properly called a certain
+kind of “re-differentiation” (“Umdifferenzierung”), and this
+share varies according to the relative position of the part
+in each case. Later on these statements will appear in
+more correct form than at present, and then it will become
+clear that we are fully entitled to emphasise at the end of
+our criticism of Weismann’s theory, that his hypothesis
+relating to restorations can be no more true than his theory
+of development proper was found to be.</p>
+
+<p>And now we shall pass on to our positive work.</p>
+
+<p>We shall try to sketch the outlines of what might
+properly be called an <em>analytical theory of morphogenesis</em>;
+that is, to explain the sum of our knowledge about organic
+form-production, gained by experiment and by logical
+analysis, in the form of a real system, in which each part
+will be, or at least will try to be, in its proper place and
+in relation with every other part. Our analytical work
+will give us ample opportunity of mentioning many important
+topics of so-called general physiology also, irrespective
+of morphogenesis as such. But morphogenesis is always to
+be the centre and starting-point of our analysis. As I
+myself approach the subject as a zoologist, animal morphogenesis,
+as before, will be the principal subject of what is to
+follow.</p>
+
+<p><span class="pagenum" title="76"><a name="Page_76" id="Page_76"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Analytical Theory of Morphogenesis</span><a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">24</a></h4>
+
+<h5 class="fs120 mb05em">α. <span class="lowercase smcap">THE DISTRIBUTION OF MORPHOGENETIC POTENCIES</span></h5>
+
+<p class="tac pt12b02em"><i>Prospective Value and Prospective Potency</i></p>
+
+<p>Wilhelm Roux did not fail to see that the questions of
+the locality and the time of all morphogenetic differentiations
+had to be solved first, before any problem of causality
+proper could be attacked. From this point of view he
+carried out his fundamental experiments.</p>
+
+<p>It is only in terminology that we differ from his views, if
+we prefer to call our introductory chapter an analysis of
+the distribution of morphogenetic potencies. The result
+will be of course rather different from what Roux expected
+it would be.</p>
+
+<p>Let us begin by laying down two fundamental concepts.
+Suppose we have here a definite embryo in a definite state
+of development, say a blastula, or a gastrula, or some sort of
+larva, then we are entitled to study any special element of
+any special elementary organ of this germ with respect to
+what is actually to develop out of this very element in the<span class="pagenum" title="77"><a name="Page_77" id="Page_77"></a></span>
+future actual course of this development, whether it be
+undisturbed or disturbed in any way; it is, so to say, the
+actual, <em>the real fate</em> of our element, that we take in account.
+I have proposed to call this real fate of each embryonic
+part in this very definite line of morphogenesis its <em>prospective
+value</em> (“prospective Bedeutung” in German). The
+fundamental question of the first chapter of our analytical
+theory of development may now be stated as follows: Is the
+prospective value of each part of any state of the morphogenetic
+line constant, <i>i.e.</i> is it unchangeable, can it be nothing
+but one; or is it variable, may it change according to
+different circumstances?</p>
+
+<p>We first introduce a second concept: the term <em>prospective
+potency</em> (“prospective Potenz” in German) of each embryonic
+element. The term “prospective morphogenetic potency” is
+to signify the <em>possible fate</em> of each of those elements. With
+the aid of our two artificial concepts we are now able to
+formulate our introductory question thus: Is the prospective
+potency of each embryonic part fully given by its prospective
+value in a certain definite case; is it, so to say, identical
+with it, or does the prospective potency contain more than
+the prospective value of an element in a certain case reveals?</p>
+
+<p>We know already from our historical sketch that the
+latter is true: that the actual fate of a part need not be
+identical with its possible fate, at least in many cases; that
+the potency of the first four blastomeres of the egg of the
+sea-urchin, for instance, has a far wider range than is shown
+by what each of them actually performs in even this
+ontogeny. There are more morphogenetic possibilities contained
+in each embryonic part than are actually realised in
+a special morphogenetic case.</p>
+
+<p><span class="pagenum" title="78"><a name="Page_78" id="Page_78"></a></span></p>
+
+<p>As the most important special morphogenetic case is, of
+course, the so-called “normal” one, we can also express our
+formula in terms of special reference to it: there are more
+morphogenetic possibilities in each part than the observation
+of the normal development can reveal. Thus we have at
+once justified the application of analytical experiment to
+morphogenesis, and have stated its most important results.</p>
+
+<p>As the introductory experiments about “Entwickelungsmechanik”
+have shown already that the prospective potency
+of embryonic parts, at least in certain cases, <em>can</em> exceed
+their prospective value&mdash;that, at least in certain cases, it can
+be different from it&mdash;the concept of prospective potency at
+the very beginning of our studies puts itself in the centre of
+analytical interest, leaving to the concept of prospective
+value the second place only. For that each embryonic part
+actually has a certain prospective value, a specified actual
+fate in every single case of ontogeny, is clear from itself and
+does not affirm more than the reality of morphogenetic cases
+in general; but that the prospective value of the elements
+may change, that there is a morphogenetic power in them,
+which contains more than actuality; in other words, that
+the term “prospective potency” has not only a logical but a
+factual interest: all these points amount to a statement not
+only of the most fundamental introductory results but also
+of the actual <em>problems</em> of the physiology of form.</p>
+
+<p>If at each point of the germ something else <em>can</em> be formed
+than actually is formed, why then does there happen in each
+case just what happens and nothing else? In these words
+indeed we may state the chief problem of our science, at least
+after the fundamental relation of the superiority of prospective
+potency to prospective value has been generally shown.</p>
+
+<p><span class="pagenum" title="79"><a name="Page_79" id="Page_79"></a></span></p>
+
+<p>We consequently may shortly formulate our first problem
+as the question of the distribution of the prospective
+morphogenetic potencies in the germ. Now this general
+question involves a number of particular ones. Up to what
+stage, if at all, is there an absolutely equal distribution of
+the potencies over all the elements of the germ? When
+such an equal distribution has ceased to exist at a certain
+stage, what are then the relations between the parts of
+different potency? How, on the other hand, does a newly
+arisen, more specialised sort of potency behave with regard
+to the original general potency, and what about the distribution
+of the more restricted potency?</p>
+
+<p>I know very well that all such questions will seem to
+you a little formal, and, so to say, academical at the outset.
+We shall not fail to attach to them very concrete meanings.</p>
+
+<p class="tac pt12b02em"><i>The Potencies of the Blastomeres</i></p>
+
+<p>At first we turn back to our experiments on the egg of
+the sea-urchin as a type of the germ in the very earliest
+stages. We know already that each of the first two, or each
+of the first four, or three of the first four blastomeres together
+may produce a whole organism. We may add that the
+swimming blastula, consisting of about one thousand cells,
+when cut in two quite at random, in a plane coincident with,
+or at least passing near, its polar axis, may form two fully
+developed organisms out of its <span class="nowrap">halves.<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">25</a></span> We may formulate
+this result in the words: the prospective potency of the<span class="pagenum" title="80"><a name="Page_80" id="Page_80"></a></span>
+single cells of a blastula of Echinus is the same for all of
+them; their prospective value is as far as possible from
+being constant.</p>
+
+<p>But we may say even a little more: what actually will
+happen in each of the blastula cells in any special case of
+development experimentally determined depends on the
+position of that cell in the whole, if the “whole” is put
+into relation with any fixed system of co-ordinates; or more
+shortly, “the prospective value of any blastula cell is a
+function of its position in the whole.”</p>
+
+<p>I know from former experience that this statement wants
+a few words of explanation. The word “function” is employed
+here in the most general, mathematical sense, simply
+to express that the prospective value, the actual fate of a
+cell, will change, whenever its position in the whole is
+<span class="nowrap">different.<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">26</a></span> The “whole” may be related to any three
+axes drawn through the normal undisturbed egg, on the
+hypothesis that there exists a primary polarity and
+bilaterality of the germ; the axes which determine this sort
+of symmetry may, of course, conveniently be taken as
+co-ordinates; but that is not necessary.</p>
+
+<p class="tac pt12b02em"><i>The Potencies of Elementary Organs in General</i></p>
+
+<p>Before dealing with other very young germs, I think it
+advisable to describe first an experiment which is carried
+out at a later stage of our well-known form. This experiment
+will easily lead to a few new concepts, which we
+shall want later on, and will serve, on the other hand, as a<span class="pagenum" title="81"><a name="Page_81" id="Page_81"></a></span>
+basis of explanation for some results, obtained from the
+youngest germs of some other animal species, which otherwise
+would seem to be rather irreconcilable with what our
+Echinus teaches us.</p>
+
+<p>You know, from the second lecture, what a gastrula of
+our sea-urchin is. If you bisect this gastrula, when it is
+completely formed, or still better, if you bisect the gastrula
+of the starfish, either along the axis or at right angles
+to it, you get complete little organisms developed from the
+parts: the ectoderm is formed in the typical manner in the
+parts, and so is the endoderm; everything is proportionate
+and only smaller than in the normal case. So we have at
+once the important results, that, as in the blastula, so in the
+ectoderm and in the endoderm of our Echinus or of the
+starfish, the prospective potencies are the same for every
+single element: both in the ectoderm and in the endoderm the
+prospective value of each cell is a “function of its position”
+(Fig. 9).</p>
+
+<div class="figcenter" style="width: 340px;">
+<img src="images/fig09.jpg" width="340" height="583" alt="" />
+<p><span class="smcap">Fig. 9.&mdash;The Starfish</span>, <i class="biological-name">Asterias</i>.</p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a</i><sup>1</sup>.</td><td class="tal ti pt02em">Normal gastrula; may be bisected along the main axis or at right angles to it (see dotted lines).</td></tr>
+<tr><td class="tar vat"><i>a</i><sup>2</sup>.</td><td class="tal ti pt02em">Normal larva, “<i class="biological-name">Bipinnaria</i>.”</td></tr>
+<tr><td class="tar vat"><i>b</i><sup>1</sup>.</td><td class="tal ti pt02em">Small but whole gastrula that results by a process of regulation from the parts of a bisected gastrula.</td></tr>
+<tr><td class="tar vat"><i>b</i><sup>2</sup>.</td><td class="tal ti">Small <em>but whole</em> “<i class="biological-name">Bipinnaria</i>,” developed out of <i>b</i><sup>1</sup>.</td></tr>
+</table>
+</div>
+
+<p>But a further experiment has been made on our gastrula.
+If at the moment when the material of the future intestine
+is most distinctly marked in the blastoderm, but not yet
+grown into a tube, if at this moment the upper half of the
+larva is separated from the lower by an equatorial section,
+you will get a complete larva only from that part which
+bears the “Anlage” of the endoderm, while the other half
+will proceed in morphogenesis very well but will form only
+ectodermal organs. By another sort of experiment, which
+we cannot fully explain here, it has been shown that the
+endoderm if isolated is also only able to form such organs
+as are normally derived from it.</p>
+
+<p>And so we may summarise both our last results by<span class="pagenum hide" title="82"><a name="Page_82" id="Page_82"></a></span><br /><span class="pagenum" title="83"><a name="Page_83" id="Page_83"></a></span>
+saying: though ectoderm and endoderm have their potencies
+equally distributed amongst their respective cells, they possess
+different potencies compared one with the other. And the
+same relation is found to hold for all cases of what we call
+elementary organs: they are “equipotential,” as we may say,
+in themselves, but of different potencies compared with each
+other.</p>
+
+<p class="tac pt12b02em"><i>Explicit and Implicit Potencies: Primary and Secondary
+Potencies</i></p>
+
+<p>We shall first give to our concept of “prospective
+potency” a few words of further analytical explanation with
+the help of our newly obtained knowledge.</p>
+
+<p>It is clear from what we have stated that the prospective
+potencies of the ectoderm and of the endoderm, and we may
+add, of every elementary organ in relation to every other,
+differ between themselves and also in comparison with the
+blastoderm, from which they have originated. But the
+diversity of the endoderm with respect to the ectoderm is
+not of the same kind as its diversity in respect to the
+blastoderm. The potency of the endoderm and that of
+the ectoderm are both specialised in their typical manner,
+but compared with the potency of the blastoderm they
+may be said not only to be specialised but also to be <em>restricted</em>:
+the potency of the blastoderm embraces the whole,
+that of the so-called germ-layer embraces only part of the
+whole; and this species of restriction becomes clearer and
+clearer the further ontogeny advances: at the end of it in
+the “ultimate elementary organs” there is no prospective
+potency whatever.</p>
+
+<p><span class="pagenum" title="84"><a name="Page_84" id="Page_84"></a></span></p>
+
+<p>A few new terms will serve to state a little more
+accurately what happens. Of course, with regard to all
+morphogenesis which goes on <em>immediately</em> from the blastoderm,
+the potency of the blastoderm is restricted as much
+as are the potencies of the germ layers. We shall call this
+sort of immediate potency <em>explicit</em>, and then we see at once
+that, with regard to their explicit potencies, there are only
+differences among the prospective potencies of the elementary
+organs; but with respect to the <em>implicit</em> potency of any of
+these organs, that is with respect to their potency as embracing
+the faculties of all their derivations, there are also
+not only differences but true morphogenetic restrictions
+lying at the very foundations of all embryology.</p>
+
+<p>But now those of you who are familiar with morphogenetic
+facts will object to me, that what we have stated
+about all sorts of restrictions in ontogeny is not true, and
+you will censure me for having overlooked regeneration,
+adventitious budding, and so on. To some extent the
+criticism would be right, but I am not going to recant;
+I shall only introduce another new concept. We are
+dealing only with <em>primary</em> potencies in our present considerations,
+<i>i.e.</i> with potencies which lie at the root of true
+embryology, not with those serving to regulate disturbances
+of the organisation. It is true, we have in some way
+disturbed the development of our sea-urchin’s egg in
+order to study it; more than that, it would have been
+impossible to study it at all without some sort of disturbance,
+without some sort of operation. But, nevertheless,
+no potencies of what may properly be called the <em>secondary</em>
+or restitutive type have been aroused by our operations;
+nothing happened except on the usual lines of organogenesis.<span class="pagenum" title="85"><a name="Page_85" id="Page_85"></a></span>
+It is true, some sort of regulation occurred, but that is
+included among the factors of ontogeny proper.</p>
+
+<p>We shall afterwards study more fully and from a more
+general point of view this very important feature of
+“primary regulation” in its contrast to “secondary regulation”
+phenomena. At present it must be enough to say
+that in speaking of the restriction of the implicit potencies
+in form-building we refer only to potencies of the primary
+type, which contain within themselves some properties of
+a (primary) regulative character.</p>
+
+<p class="tac pt12b02em"><i>The Morphogenetic Function of Maturation in the Light of
+Recent Discoveries</i></p>
+
+<p>Turning again to more concrete matters, we shall first
+try, with the knowledge acquired of the potencies of the
+blastoderm and the so-called germ layers of Echinus, to
+understand certain rather complicated results which the
+experimental morphogenetic study of other animal forms
+has taught us. We know from our historical sketch that
+there are some very important aberrations from the type,
+to which the Echinus germ <span class="nowrap">belongs,<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">27</a></span> <i>i.e.</i> the type with
+an equal distribution of the potencies over all the blastomeres.
+We know not only that in cases where a regulation
+of the intimate structure of the protoplasm fails to occur
+a partial development of isolated cells will take place, but
+that there may even be a typical disposition of typical cells<span class="pagenum" title="86"><a name="Page_86" id="Page_86"></a></span>
+for the formation of typical organs only, without any
+regulability.</p>
+
+<p>Let us first consider the last case, of which the egg of
+mollusca is a good type: here there is no equal distribution
+of potencies whatever, the cleavage-cells of this germ are
+a sort of real “mosaic” with regard to their morphogenetic
+potentialities. Is this difference between the germ of the
+echinoderms and the molluscs to remain where it is, and
+not to be elucidated any further? Then there would be
+rather important differences among the germs of different
+animals, at least with regard to the degree of the specification
+of their cleavage cells, or if we ascribe differences
+among the blastomeres to the organisation of the fertilised
+egg ready for cleavage, there would be differences in the
+morphogenetic organisation of the egg-protoplasm: some
+eggs would be more typically specialised at the very
+beginning of morphogenesis than others.</p>
+
+<p>In the first years of the study of “Entwickelungsmechanik”
+I pointed out that it must never be forgotten
+that the egg itself is the result of organogenesis. If, therefore,
+there are real mosaic-like specifications in some eggs at
+the beginning of cleavage, or during it, there may perhaps
+have been an <em>earlier</em> stage in the individual history of the
+egg which did not show such specifications of the morphogenetic
+structure. Two American authors share the merit
+of having proved this hypothesis. Conklin showed, several
+years ago, that certain intracellular migrations and rearrangements
+of material do happen in the first stages of
+ovogenesis in certain cases, but it is to E. B. <span class="nowrap">Wilson<a name="FNanchor_28_28" id="FNanchor_28_28"></a><a href="#Footnote_28_28" class="fnanchor">28</a></span> that
+science owes a proper and definitive elucidation of the<span class="pagenum" title="87"><a name="Page_87" id="Page_87"></a></span>
+whole subject. Wilson’s researches, pursued not only by
+descriptive <span class="nowrap">methods,<a name="FNanchor_29_29" id="FNanchor_29_29"></a><a href="#Footnote_29_29" class="fnanchor">29</a></span> but also by means of analytical experiment,
+led him to the highly important discovery that
+the eggs of several forms (nemertines, molluscs), which
+after maturation show the mosaic type of specification in
+their protoplasm to a more or less high degree, fail to
+show any kind of specification in the distribution of their
+potencies before maturation has occurred. In the mollusc
+egg a certain degree of specification is shown already
+before maturation, but nothing to be compared with what
+happens afterwards; in the egg of nemertines there is no
+specification at all in the unripe egg.</p>
+
+<p>Maturation thus becomes a part of ontogeny itself; it
+is not with fertilisation that morphogenesis begins, there
+is a sort of ontogeny anterior to fertilisation.</p>
+
+<p>These words constitute a summary of Wilson’s researches.
+Taken together with the general results obtained about
+the potencies of the blastula and the gastrula of Echinus,
+they reduce what appeared to be differences of degree
+or even of kind in the specification of the egg-protoplasm
+<em>to mere differences in the time of the beginning of real
+morphogenesis</em>. What occurs in some eggs, as in those of
+Echinus, at the time of the definite formation of the germ
+layers, leading to a specification and restriction of their
+prospective potencies, may happen very much earlier in
+other eggs. But there exists in <em>every</em> sort of egg an
+<em>earliest</em> stage, in which all parts of its protoplasm are<span class="pagenum" title="88"><a name="Page_88" id="Page_88"></a></span>
+equal as to their prospectivity, and in which there are no
+potential diversities or restrictions of any kind.</p>
+
+<p>So much for differences in the <em>real material</em> organisation
+of the germ and their bearing on inequipotentialities of the
+cleavage cells.</p>
+
+<p class="tac pt12b02em"><i>The Intimate Structure of Protoplasm: Further Remarks</i></p>
+
+<p>Where a typical half- or quarter-development from
+isolated blastomeres happens to occur, we know already
+that the impossibility of a regulation of the <em>intimate polar-bilateral</em>
+structure may account for it. As this impossibility
+of regulation probably rests on rather simple physical <span class="nowrap">conditions<a name="FNanchor_30_30" id="FNanchor_30_30"></a><a href="#Footnote_30_30" class="fnanchor">30</a></span>
+it may properly be stated that equal distribution
+of potencies is not wanting but is only overshadowed here.
+In this respect there exists a logical difference of fundamental
+importance between those cases of so-called “partial”
+or better, “fragmental” development of isolated blastomeres
+in which a certain embryonic organ is wanting on account
+of its specific morphogenetic material being absent, and
+those cases in which the “fragmental” embryo lacks
+complete “halves” or “quarters” with regard to general
+symmetry on account of the symmetry of its intimate
+structure being irregularly disturbed. This logical difference
+has not always received the attention which it undoubtedly
+deserves. Our hypothetical intimate structure in itself is,
+of course, also a result of factors concerned in ovogenesis.
+Only in one case do we actually know anything about its<span class="pagenum" title="89"><a name="Page_89" id="Page_89"></a></span>
+origin: Roux has shown that in the frog it is the accidental
+path of the fertilising spermatozoon in the egg which,
+together with the polar axis, normally determines the plane
+of bilateral symmetry; but this symmetry may be overcome
+and replaced by another, if gravity is forced to act in an
+abnormal manner upon the protoplasm; the latter showing
+parts of different specific gravity in the eggs of all Amphibia.</p>
+
+<p class="tac pt12b02em"><i>The Neutrality of the Concept of “Potency”</i></p>
+
+<p>Now we may close our rather long chapter on the
+distribution of potencies in the germ; it has been made
+long, because it will prove to be very important for further
+analytical discussion; and its importance, in great measure,
+is due to its freedom from prepossessions. Indeed, the
+concept of prospective potency does not prejudice anything;
+we have said, it is true, that limitations of potencies may
+be due to the presence of specific parts of organisation in
+some cases; that, at least, they may be connected therewith;
+but we have not determined at all what a prospective
+potency really is, what the term really is to signify. It
+may seem that such a state of things gives an air of
+emptiness to our discussions, that it leaves uncertain
+what is the most important. But, I think, our way of
+argument, which tries to reach the problems of greatest
+importance by degrees, though it may be slow, could hardly
+be called wrong and misleading.</p>
+
+
+<h5 class="fs120 mb05em">β. <span class="lowercase smcap">THE “MEANS” OF MORPHOGENESIS</span></h5>
+
+<p>We now proceed to an analysis of what may properly
+be called the <em>means</em> of morphogenesis, the word <span class="pagenum" title="90"><a name="Page_90" id="Page_90"></a></span>“means”
+being preferable to the more usual one “conditions” in this
+connection, as the latter would not cover the whole field.
+It is in quite an unpretentious and merely descriptive
+sense that the expression “means” should be understood at
+present; what is usually called “conditions” is part of the
+morphogenetic means in our sense.</p>
+
+<h6 class="fs110 mb05em">β′. <i>The Internal Elementary Means of Morphogenesis</i></h6>
+
+<p>We know that all morphogenesis, typical or atypical,
+primary or secondary, goes on by one morphogenetic
+elementary process following the other. Now the very
+foundation of these elementary processes themselves lies in
+the elementary functions of the organism as far as they
+result in the formation of stable visible products. Therefore
+the elementary functions of the organism may properly be
+called the internal “means” of morphogenesis.</p>
+
+<p>Secretion and migration are among such functions; the
+former happening by the aid of chemical change or by
+physical separation, the latter by the aid of changes in
+surface tension. But hardly anything more concrete has
+been made out about these or similar points at present.</p>
+
+<p>We therefore make no claim to offer a complete system
+of the internal elementary means of morphogenesis. We
+shall only select from the whole a few topics of remarkable
+morphogenetic interest, and say a few words about each.</p>
+
+<p>But, first of all, let us observe that the elementary means
+of morphogenesis are far from being morphogenesis themselves.
+The word “means” itself implies as much. It
+would be possible to understand each of these single acts in
+morphogenesis as well as anything, and yet to be as far<span class="pagenum" title="91"><a name="Page_91" id="Page_91"></a></span>
+from understanding the whole as ever. All means of
+morphogenesis are only to be considered as the most general
+frame of events within which morphogenesis occurs.</p>
+
+<p><i>Some Remarks on the Importance of Surface Tension in
+Morphogenesis.</i>&mdash;There are a few purely physical phenomena
+which have a special importance in organic morphology, all
+of them connected with capillarity or surface tension. Soap-lather
+is a very familiar thing to all of you: you know that
+the soap-solution is arranged here in very thin planes separated
+by spaces containing air: it was first proved by <span class="nowrap">Berthold<a name="FNanchor_31_31" id="FNanchor_31_31"></a><a href="#Footnote_31_31" class="fnanchor">31</a></span>
+that the arrangement of cells in organic tissues follows the
+same type as does the arrangement of the single bubbles of
+a soap-lather, and <span class="nowrap">Bütschli<a name="FNanchor_32_32" id="FNanchor_32_32"></a><a href="#Footnote_32_32" class="fnanchor">32</a></span> added to this the discovery that
+the minute structure of the protoplasm itself is that of a
+foam also. Of course it is not one fluid and one gas which
+make up the constituents of the structure in the organisms,
+as is the case in the well-known inorganic foams, but two
+fluids, which do not mix with one another. One general
+law holds for all arrangements of this kind: the so-called
+law of least surfaces, expressed by the words that the
+sum of all surfaces existing is a minimum; and it again
+is a consequence of this law, if discussed mathematically,
+that four lines will always meet in one point and three
+planes in one line. This feature, together with a certain
+law about the relation of the angles meeting in one line
+to the size of the bubbles, is realised most clearly in
+many structures of organic tissues, and makes it highly
+probable, at least in some cases, that capillarity is at work
+here. In other cases, as for instance in many plants, a<span class="pagenum" title="92"><a name="Page_92" id="Page_92"></a></span>
+kind of outside pressure, the so-called tissue tension, may
+account for the arrangement in surfaces <em>minimae areae</em>.
+Cleavage stages are perhaps the very best type in which
+our physical law is expressed: and here it may be said
+to have quite a simple application whenever all of the
+blastomeres are of the same physical kind, whilst some
+complications appear in germs with a specialised organisation
+and, therefore, with differences in the protoplasm of
+their single blastomeres. In such instances we may say
+that the physical law holds as far as the conditions of the
+system permit, these conditions ordinarily consisting in a
+sort of non-homogeneity of the surfaces.</p>
+
+<p>It seems, from the researches of <span class="nowrap">Dreyer,<a name="FNanchor_33_33" id="FNanchor_33_33"></a><a href="#Footnote_33_33" class="fnanchor">33</a></span> that the formation
+of organic skeletons may also be governed by the
+physically conditioned arrangement of protoplasmatic or
+cellular elements, and some phenomena of migration and
+rearrangement among cleavage cells, as described by Roux,
+probably also belong here.</p>
+
+<p>But let us never forget that the laws of surface tension
+only give us the most general type of an arrangement of
+elements in all these cases, nothing else. A physical law
+never accounts for the Specific! Capillarity gives us not
+the least clue to it. As the organic substance, at least in
+many cases, is a fluid, it must of course follow the general
+laws of hydrostatics and hydrodynamics, but life itself is as
+little touched by its fluid-like or foam-like properties as it
+is by the fact that living bodies have a certain weight and
+mass.</p>
+
+<p>All indeed that has been described may be said to
+belong, in the broadest meaning of the word, to what is<span class="pagenum" title="93"><a name="Page_93" id="Page_93"></a></span>
+called by Roux “correlation of masses,” though this author
+originally intended to express by this term only some sorts
+of passive pressure and deformation amongst embryonic
+parts as discovered especially by His.</p>
+
+<p>We must be cautious in admitting that any organic
+feature has been explained, even in the most general way,
+by the action of physical forces. What at first seems to be
+the result of mechanical pressure may afterwards be found
+to be an active process of growth, and what at first seems
+to be a full effect of capillarity among homogeneous elements
+may afterwards be shown to depend on specialised metabolic
+conditions of the surfaces as its principal <span class="nowrap">cause.<a name="FNanchor_34_34" id="FNanchor_34_34"></a><a href="#Footnote_34_34" class="fnanchor">34</a></span></p>
+
+<p>There are other physical phenomena too, which assist
+morphogenesis; osmotic pressure for instance, which is also
+well known to operate in many purely physiological processes.
+But all these processes are only means of the organism, and
+can never do more than furnish the general type of events.
+They do not constitute life; they are <em>used</em> by life; let it
+remain an open question, for the present, how the phenomenon
+of “life” is to be regarded in <span class="nowrap">general.<a name="FNanchor_35_35" id="FNanchor_35_35"></a><a href="#Footnote_35_35" class="fnanchor">35</a></span></p>
+
+<p><i>On Growth</i>.&mdash;Among the internal morphogenetical means
+which are of a so-called physiological character, that is,
+which nobody claims to understand physically at present,<span class="pagenum" title="94"><a name="Page_94" id="Page_94"></a></span>
+there is in the first place <em>growth</em>, which must be regarded
+as a very essential one.</p>
+
+<p>Analytically we must carefully discriminate between the
+increase in the size of the cavities of an organism by a
+passive extension of their surfaces and the proper growth of
+the individual cells, which again may be due either to mere
+extension or to real assimilation. Osmotic pressure, of
+course, plays an important part both in the growth of the
+body-cavities and in simple cellular extension. We repeat
+the caution against believing too much to be explained by
+this phenomenon: it is the organism which by the secretion
+of osmotic substances in the cavities or the protoplasm of
+the cells prepares the ground for growth even of this
+osmotic sort. The real cellular growth which proceeds on
+the basis of assimilation cannot, of course, be accounted for
+by osmotic events, not even in its most general type.</p>
+
+<p>Ontogenetical growth generally sets in, both in animals
+and in plants, after the chief lines of organisation are laid
+out; it is only the formation of the definite histological
+structures which usually runs parallel to it.</p>
+
+<p><i>On Cell-division.</i>&mdash;We have already said a good deal
+about the importance of cell-division in ontogeny: it
+accompanies very many of the processes of organisation in
+all living beings. But even then, there are the Protozoa,
+in the morphogenesis of which it does not occur at all, and
+there have also become known many cases of morphogenesis
+in higher animals, mostly of the type of regulation, in which
+cellular division is almost or wholly wanting. Therefore,
+cellular division cannot be the true reason of differentiation,
+but is only a process, which though necessary in some cases,
+cannot be essential to it. It must be conceded, I believe,<span class="pagenum" title="95"><a name="Page_95" id="Page_95"></a></span>
+that the same conclusion can be drawn from all our
+experiments on very young stages of the germ.</p>
+
+<p>The investigations of the last few years have made it
+quite clear that even in organisms with a high power of
+morphogenetic regulation it is always the form of the whole,
+but not the individual cell, which is subjected to the regulation
+processes. Starting from certain results obtained by
+T. H. Morgan, I was able to show that in all the small but
+whole larvae, reared from isolated blastomeres, the size of
+the cells remains normal, only their number being reduced;
+and Boveri has shown most clearly that it is always the
+size of the nucleus&mdash;more correctly, the mass of the
+chromatin&mdash;which determines how large a cell of a certain
+histological kind is to be. In this view, the cell appears
+even more as a sort of material used by the organism as
+supplied, just as workmen can build the most different
+buildings with stones of a given size.</p>
+
+
+<h6 class="fs110 mb05em">β″. <i>The External Means of Morphogenesis</i></h6>
+
+<p>We now know what internal means of morphogenesis are,
+and so we may glance at some of the most important
+“outer means” or “conditions” of organisation.</p>
+
+<p>Like the adult, the germ also requires a certain amount
+of heat, oxygen, and, when it grows up in the sea, salinity
+in the medium. For the germ, as for the adult, there
+exists not only a minimum but also a maximum limit
+of all the necessary factors of the medium; the same factor
+which at a certain intensity promotes development, disturbs
+it from a certain other intensity upwards.</p>
+
+<p>Within the limits of this minimum and this maximum<span class="pagenum" title="96"><a name="Page_96" id="Page_96"></a></span>
+of every outside agent there generally is an increase in
+the rate of development corresponding to the increase of
+intensity of the agent. The acceleration of development by
+heat has been shown to follow the law of the acceleration of
+chemical processes by a rise of temperature; that seems to
+prove that certain chemical processes go on during the
+course of morphogenesis.</p>
+
+<p>Almost all that has been investigated of the part played
+by the external conditions of development has little bearing
+on specific morphogenesis proper, and therefore may be left
+out of account here: we must, however, lay great stress
+on the general fact that there <em>is</em> a very close dependence
+of morphogenesis on the outside factors, lest we should be
+accused afterwards of having overlooked it.</p>
+
+<p>Of course all “external” means or conditions of morphogenesis
+can actually relate to morphogenetic processes only by
+becoming in some way “internal,” but we unfortunately have
+no knowledge whatever how this happens. We at present
+are only able to ascertain what must necessarily be
+accomplished in the medium, in order that normal morphogenesis
+may go on, and we can only suppose that there
+exist certain specific internal general states, indispensable
+for organogenesis but inaccessible to present modes of
+<span class="nowrap">investigation.<a name="FNanchor_36_36" id="FNanchor_36_36"></a><a href="#Footnote_36_36" class="fnanchor">36</a></span></p>
+
+<p><i>The Discoveries of Herbst.</i>&mdash;There are but few points
+in the doctrine of the external means or conditions of
+organogenesis which have a more special bearing on
+the specification of proper form, and which therefore<span class="pagenum" title="97"><a name="Page_97" id="Page_97"></a></span>
+require to be described here a little more fully. All these
+researches, which have been carried out almost exclusively
+by <span class="nowrap">Herbst,<a name="FNanchor_37_37" id="FNanchor_37_37"></a><a href="#Footnote_37_37" class="fnanchor">37</a></span> relate to the effect of the chemical components
+of sea-water upon the development of the sea-urchin. If
+we select the most important of Herbst’s results, we must
+in the first place say a few words on the part taken by
+lime or calcium, not only in establishing specific features of
+form, but in rendering individual morphogenesis possible at
+all. Herbst has found that in sea-water which is deprived
+of calcium the cleavage cells and many tissue cells also
+completely lose contact with each other: cleavage goes on
+quite well, but after each single division the elements are
+separated; at the end of the process you find the 808 cells
+of the germ together at the bottom of the dish, all swimming
+about like infusoria. There seems to be some
+influence of the calcium salts upon the physical state of
+the surfaces of the blastomeres.</p>
+
+<p>It is not without interest to note that this discovery
+has an important bearing on the technical side of all experiments
+dealing with the isolation of blastomeres. Since the
+separation of the single cleavage elements ceases as soon
+as the germs are brought back from the mixture without
+lime into normal sea-water, it of course is possible to
+separate them up to any stage which it is desired to study,
+and to keep them together afterwards. Thus, if for instance
+you want to study the development of isolated cells of the
+eight-cell stage, you will leave the egg in the artificial
+mixture containing no calcium until the third cleavage,
+which leads from the four- to the eight-cell stage, is finished.
+The single eight cells brought back to normal sea-water at<span class="pagenum" title="98"><a name="Page_98" id="Page_98"></a></span>
+this point will give you the eight embryos you want. All
+researches upon the development of isolated blastomeres
+since the time of Herbst’s discovery have been carried out
+by this method, and it would have been quite impossible
+by the old method of shaking to pursue the study into
+such minute detail as actually has been done. It may
+be added that calcium, besides its cell-uniting action,
+is also of primary importance in the formation of the
+skeleton.</p>
+
+<p>Among all the other very numerous studies of Herbst
+we need only mention that potassium is necessary for the
+typical growth of the intestine, just as this element has
+been found necessary for normal growth in plants, and that
+there must be the ion SO<sub>4</sub>, or in other terms, sulphur salts
+present in the water, in order that the germs may acquire
+their pigments and their bilateral symmetry. This is indeed
+a very important result, though it cannot be said to be
+properly understood. It is a fact that in water without
+sulphates the larvae of Echinus retain the radial symmetry
+they have had in the very earliest stages, and may even
+preserve that symmetry on being brought back to normal
+sea-water if they have spent about twenty-four hours in
+the artificial mixture.</p>
+
+<p>We may now leave the subject of Herbst’s attempts to
+discover the morphogenetic function of the single constituents
+of normal sea-water, and may devote a few
+words to the other branch of his investigations, those
+dealing with the morphogenetic effects of substances which
+are not present in the water of the sea, but have been added
+to it artificially. Here, among many other achievements,
+Herbst has made the most important discovery that all<span class="pagenum" title="99"><a name="Page_99" id="Page_99"></a></span>
+salts of lithium effect radical changes in <span class="nowrap">development.<a name="FNanchor_38_38" id="FNanchor_38_38"></a><a href="#Footnote_38_38" class="fnanchor">38</a></span> I
+cannot describe fully here how the so-called “lithium
+larva” originates; let me only mention that its endoderm
+is formed outside instead of inside, that it is far
+too large, that there is a spherical mass between the
+ectodermal and the endodermal part of the germ, that
+a radial symmetry is established in place of the normal
+bilateralism, that no skeleton exists, and that the mesenchyme
+cells are placed in a quite abnormal position. All these
+features, though abnormal, are typical of the development
+in lithium. The larvae present no really pathological
+appearance at all, and, therefore, it may indeed be said that
+lithium salts are able to change fundamentally the whole
+course of morphogenesis. It detracts nothing from the
+importance of these discoveries that, at present, they stand
+quite isolated: only with lithium salts has Herbst obtained
+such strange results, and only upon the eggs of echinids,
+not even upon those of asterids, do lithium salts act in this
+way.</p>
+
+
+<h5 class="fs120 mb05em">γ. <span class="lowercase smcap">THE FORMATIVE CAUSES OR STIMULI</span></h5>
+
+<p class="tac pt12b02em"><i>The Definition of Cause</i></p>
+
+<p>We cannot begin the study of the “causes” of the
+differentiation of form without a few words of explanation
+about the terminology which we shall apply. Causality
+is the most disputed of all categories; many modern
+scientists, particularly in physics, try to avoid the concept
+of cause altogether, and to replace it by mere functional
+dependence in the mathematical meaning of the term.<span class="pagenum" title="100"><a name="Page_100" id="Page_100"></a></span>
+They claim to express completely by an equation all that
+is discoverable about any sort of phenomena constantly
+connected.</p>
+
+<p>I cannot convince myself that such a very restricted
+view is the right one: it is very cautious, no doubt, but it
+is incomplete, for we <em>have</em> the concept of the acting “cause”
+in our Ego and are <em>forced</em> to search for applications of it
+in Nature. On the other hand, it does not at all escape
+me that there are many difficulties, or rather ambiguities,
+in applying it.</p>
+
+<p>We may call the “cause” of any event, the sum total
+of all the constellations of facts which must be completed
+in order that the event may occur; it is in this meaning,
+for instance, that the first principle of energetics applies
+the term in the words <i lang="la" xml:lang="la">causa aequat effectum</i>. But, by
+using the word only in this very general sense, we deprive
+ourselves of many conveniences in the further and more
+particular study of Nature. Would it be better to say that
+the “cause” of any event is the very last change which,
+after all the constellations necessary for its start are
+accomplished, must still take place in order that the event
+may actually occur? Let us see what would follow from
+such a use of the word causality. We here have an animal
+germ in a certain stage, say a larva of Echinus, which is just
+about to form the intestine; all the internal conditions are
+fulfilled, and there is also a certain temperature, a certain
+salinity, and so on, but there is no oxygen in the water: the
+intestine; of course, will not grow in such a state of things,
+but it soon will when oxygen is allowed to enter the dish.
+Is, therefore, oxygen the cause of the formation of the
+intestine of echinus? Nobody, I think, would care to say<span class="pagenum" title="101"><a name="Page_101" id="Page_101"></a></span>
+so. By such reasoning, indeed, the temperature, or sodium,
+might be called the “cause” of any special process of
+morphogenesis. It, therefore, seems to be of little use to
+give the name of cause to that factor of any necessary
+constellation of events which accidentally happens to be
+the last that is realised. But what is to be done then?</p>
+
+<p>Might we not say that the cause of any morphogenetic
+process is that typical property, or quality, or change, on
+which its specific character depends, on which depends for
+example, the fact that now it is the intestine which appears,
+while at another time it is the lens of the eye? We might
+very well, but we already have our term for this sort of
+cause, which is nothing else than our prospective potency
+applied to that elementary organ from which the new
+process takes its origin. The prospective potency indeed
+is the truly immanent cause of every specification affecting
+single organogenetic processes. But we want something
+more than this.</p>
+
+<p>We may find what we want by considering that each
+single elementary process or development not only has its
+specification, but also has its specific and typical place in
+the whole&mdash;its locality. Therefore we shall call the “cause”
+of a single morphogenetic process, that occurrence on which
+depends its <em>localisation</em>, whether its specific character also
+partly depends on this “cause” or <span class="nowrap">not.<a name="FNanchor_39_39" id="FNanchor_39_39"></a><a href="#Footnote_39_39" class="fnanchor">39</a></span></p>
+
+<p>This definition of “cause” in morphology may be
+artificial; in any case it is clear. And at the same time
+the concepts of the prospective potency and of the “means”
+of organogenesis now acquire a clear and definite meaning:<span class="pagenum" title="102"><a name="Page_102" id="Page_102"></a></span>
+potency is the real basis of the specific character of every
+act in morphogenesis, and “means,” including conditions, are
+the sum of all external and internal general circumstances
+which must be present in order that morphogenetic processes
+may go on, without being responsible for their specificity
+or localisation.</p>
+
+<p>It is implied in these definitions of cause and potency,
+that the former almost always will be of that general
+type which usually is called a stimulus or “Auslösung,”
+to use the untranslatable German word. There is no
+quantitative correspondence between our “cause” and the
+morphogenetic effect.</p>
+
+<p class="tac pt12b02em"><i>Some Instances of Formative and Directive Stimuli</i></p>
+
+<p>Again it is to Herbst that we owe not only a very
+thorough logical analysis of what he calls “formative and
+directive <span class="nowrap">stimuli”<a name="FNanchor_40_40" id="FNanchor_40_40"></a><a href="#Footnote_40_40" class="fnanchor">40</a></span> but also some important discoveries
+on this subject. We cannot do more here than barely
+mention some of the most characteristic facts.</p>
+
+<p>Amongst plants it has long been known that the
+direction of light or of gravity may determine where
+roots or branches or other morphogenetic formations are to
+arise; in hydroids also we know that these factors of the
+medium may be at <span class="nowrap">work<a name="FNanchor_41_41" id="FNanchor_41_41"></a><a href="#Footnote_41_41" class="fnanchor">41</a></span> as morphogenetic causes, though<span class="pagenum" title="103"><a name="Page_103" id="Page_103"></a></span>
+most of the typical architecture of hydroid colonies certainly
+is due to internal causes, as is also much of the organisation
+in plants.</p>
+
+<p>Light and gravity are external formative causes; beside
+that they are merely “localisers.” But there also are some
+external formative stimuli, on which depends not only
+the place of the effect, but also part of its specification.
+The galls of plants are the most typical organogenetic
+results of such stimuli. The potencies of the plant and the
+specific kind of the stimulus equally contribute to their
+specification; for several kinds of galls may originate on
+one sort of leaves.</p>
+
+<p>Scarcely any exterior formative stimuli are responsible
+for animal organisation; and one would hardly be wrong
+in saying that this morphogenetic independence in animals
+is due to their comparatively far-reaching functional independence
+of those external agents which have any sort
+of direction. But many organogenetic relations are known
+to exist between the single parts of animal germs, each
+of these parts being in some respect external to every
+other; and, indeed, it might have been expected already
+<i lang="la" xml:lang="la">a priori</i>, that such formative relations between the parts of an
+animal embryo must exist, after all we have learned about
+the chief lines of early embryology. If differentiation does
+not go on after the scheme of Weismann, that is, if it is not
+carried out by true “evolutio” from within, how could it be
+effected except from without? Indeed, every embryonic
+part may in some respect be a possible cause for morphogenetic
+events, which are to occur on every other part: it is
+here that the very roots of epigenesis are to be found.</p>
+
+<p>Heliotropism and geotropism are among the well-known<span class="pagenum" title="104"><a name="Page_104" id="Page_104"></a></span>
+physiological functions of plants: the roots are seen to bend
+away from the light and towards the ground; the branches
+behave just in the opposite way. It now has been supposed
+by Herbst that such “directive stimuli” may also be at
+work among the growing or wandering parts of the embryo,
+that their growth or their migration may be determined by
+the typical character of other parts, and that real morphogenetic
+characters can be the result of some such relation;
+a sort of “chemotropism” or “chemotaxis” may be at work
+here. Herbst himself has discussed theoretically several
+cases of organogenesis in which the action of directive
+stimuli is very probable. What has become actually
+known by experiment is not very much at present: the
+mesenchyme cells of Echinus are directed in their migration
+by specified places in the ectoderm, the pigment cells of the
+yolk-sac of the fish fundulus are attracted by its blood
+vessels, and nerves may be forced to turn into little tubes
+containing brain substance; but of course only the first two
+instances have any bearing on typical morphogenesis.</p>
+
+<p>The first case of an “internal formative stimulus” in
+the proper sense, that is, of one embryonic part causing
+another to appear, was discovered by Herbst himself. The
+arms of the so-called pluteus of the sea-urchin are in
+formative dependence on the skeleton&mdash;no skeleton, no
+arms; so many skeleton <span class="nowrap">primordia,<a name="FNanchor_42_42" id="FNanchor_42_42"></a><a href="#Footnote_42_42" class="fnanchor">42</a></span> in abnormal cases, so
+many arms; abnormal position of the skeleton, abnormal
+position of the arms: these three experimental observations
+form the proof of this morphogenetic relation.</p>
+<p><span class="pagenum" title="105"><a name="Page_105" id="Page_105"></a></span></p>
+<p>It may be simple mechanical contact, or it may be some
+chemical influence that really constitutes the “stimulus” in
+this case; certainly, there exists a close and very specific
+relation of the localisation of one part of the embryo to
+another. Things are much the same in another case,
+which, after having been hypothetically stated by Herbst
+on the basis of pathological data, was proved experimentally
+by Spemann. The lens of the eye of certain Amphibia is
+formed of their skin in response to a formative stimulus
+proceeding from the so-called primary optic vesicle. If this
+vesicle fails to touch the skin, no lens appears; and, on the
+other hand, the lens may appear in quite abnormal parts of
+the skin if they come into contact with the optic vesicle
+after transplantation.</p>
+
+<p>But formative dependence of parts may also be of
+different types.</p>
+
+<p>We owe to Herbst the important discovery that the
+eyes of crayfishes, after being cut off, will be regenerated in
+the proper way, if the optic ganglion is present, but that
+an antenna will arise in their place if this ganglion has
+also been removed. There must in this case be some
+unknown influence of the formative kind on which
+depends, if not regeneration itself, at least its special
+character.</p>
+
+<p>In other cases there seems to be an influence of the
+central nervous system on the regenerative power in general.
+Amphibia, for instance, are said to regenerate neither their
+legs (Wolff), nor their tail (Godlewski), if the nervous communications
+have been disturbed. But in other animals
+there is no such influence; and in yet others, as for instance,
+in Planarians, it must seem doubtful at present whether the<span class="pagenum" title="106"><a name="Page_106" id="Page_106"></a></span>
+morphogenetic influence of the nervous system upon processes
+of restoration is more than indirect; the movements of the
+animal, which become very much reduced by the extirpation
+of the ganglia, being one of the main conditions of a good
+regeneration.</p>
+
+<p>Of course, all we have said about the importance of
+special materials in the ripe germ, as bearing on specifically
+localised organisations, might be discussed again in our
+present chapter, and our intimate polar-bilateral structure
+of germs may also be regarded as embracing formative
+stimuli, at any rate as far as the actual poles of this
+structure are concerned. This again would bring us to the
+problem of so-called “polarity” in general, and to the
+“inversion” of polarity, that is to a phenomenon well
+known in plants and in many hydroids and worms, viz.,
+that morphogenetic processes, especially of the type of
+restitutions, occur differently, according as their point of
+origin represents, so to speak, the positive or the negative,
+the terminal or the basal end of an axis, but that under
+certain conditions the reverse may also be the case. But a
+fuller discussion of these important facts would lead us
+deeper and deeper into the science of morphogenesis proper,
+without being of much use for our future considerations.</p>
+
+<p>And so we may close this <span class="nowrap">section<a name="FNanchor_43_43" id="FNanchor_43_43"></a><a href="#Footnote_43_43" class="fnanchor">43</a></span> on formative stimuli<span class="pagenum" title="107"><a name="Page_107" id="Page_107"></a></span>
+or “causes” of morphogenesis by shortly adding, more on
+account of its factual than of its logical interest, that the
+phenomenon of the determination of <span class="nowrap">sex,<a name="FNanchor_44_44" id="FNanchor_44_44"></a><a href="#Footnote_44_44" class="fnanchor">44</a></span> according to the
+latest researches, seems to depend on cytological events
+occurring in the very earliest embryonic stages, say even
+before ontogeny, and not on formative stimuli <span class="nowrap">proper<a name="FNanchor_45_45" id="FNanchor_45_45"></a><a href="#Footnote_45_45" class="fnanchor">45</a></span>: it
+seems, indeed, as if the sexual products themselves would
+account for the sex of the individual produced by them,
+particularly if there were differences in their <span class="nowrap">chromatin.<a name="FNanchor_46_46" id="FNanchor_46_46"></a><a href="#Footnote_46_46" class="fnanchor">46</a></span></p>
+
+
+<h5 class="fs120 mb05em">δ. <span class="lowercase smcap">THE MORPHOGENETIC HARMONIES</span></h5>
+
+<p>Let us now turn again to considerations of a more
+abstract kind: we have become acquainted with some
+morphogenetic interactions among the parts of a developing
+embryo; and, indeed, we can be sure that there exist far
+more of such interactions than we know at present.</p>
+
+<p>But it is far from being true that the development of
+each embryonic part depends on the existence or development
+of every other one.</p>
+
+<p>On the contrary, it is a very important and fundamental
+feature of organogenesis that it occurs in separate lines,<span class="pagenum" title="108"><a name="Page_108" id="Page_108"></a></span>
+that is to say, in lines of processes which may start from a
+common root, but which are absolutely independent of
+one another in their manner of differentiation. Roux has
+coined the term “self-differentiation” to denote this phenomenon,
+and we admit that this term may be conveniently
+used for the purpose, if only it can be kept in mind that
+its sense is always relative, and that it is also negative.
+Suppose a part, <i>A</i>, shows the phenomenon of self-differentiation:
+this means that the further development of <i>A</i>
+is not dependent on certain other parts, <i>B</i>, <i>C</i>, and <i>D</i>; it does
+<em>not</em> mean at all that <i>A</i> has not been formatively dependent
+on some other parts, <i>E</i> or <i>F</i> at the time of its first appearance,
+nor does it imply that there might not be many
+formative actions among the constituents of <i>A</i> itself.</p>
+
+<p>We indeed are entitled to say that the ectoderm of
+Echinus shows “self-differentiation” with regard to the
+endoderm; it acquires its mouth, for instance, as has been
+shown by experiment, even in cases where no intestine is
+present at all (Fig. 10); but ectoderm and endoderm both
+are formatively dependent on the intimate and the material
+organisation of the blastoderm. It further seems from the
+most recent experiments that the nerves and the muscles of
+the vertebrates are independent of each other in their
+differentiation, but that their fate is probably determined
+by formative processes in the very earliest stages of ontogeny.</p>
+
+<div class="figcenter" style="width: 225px;">
+<img src="images/fig10.jpg" width="225" height="208" alt="" /></div>
+<div class="figcenter" style="width: 250px;">
+<p><span class="smcap">Fig. 10.&mdash;Pluteus-larva of Sphaerechinus.</span></p>
+<p>The Intestine (i) is developed outside instead of inside (by means of raising the temperature);
+but the mouth (r) is formed in its normal place. S = Skeleton.</p>
+</div>
+
+<p>The phenomenon of self-differentiation, properly understood,
+now may help to the discovery of one most general
+character of all development. If the phenomenon of self-differentiation
+really occurs in ontogeny in its most different
+aspects, and if, on the other hand, in spite of this relative
+morphogenetic independence of embryonic parts, the result<span class="pagenum" title="109"><a name="Page_109" id="Page_109"></a></span>ing
+organism is one whole in organisation and in function,
+some sort of <em>harmony of constellation</em>, as it may properly be
+styled, must be said to be one of the most fundamental
+characters of all production of individual form. In establishing
+this harmony we do nothing more than describe exactly
+what happens: the harmony is shown by the fact that
+there is a whole organism at the end, in spite of the relative
+independence of the single events leading to it.</p>
+
+<p>But still another sort of harmony is revealed in morphogenesis,
+by an analysis of the general conditions of the
+formative actions themselves. In order that these actions
+may go on properly the possibility must be guaranteed that
+the formative causes may always find something upon which
+to act, and that those parts which contain the potencies for
+the next ontogenetic stage may properly receive the stimuli
+awaking these potencies: otherwise there would be no
+typical production of form at all. This, the second species
+of harmonious relations to be described in ontogeny, may
+be called <em>causal harmony</em>; the term simply expresses the<span class="pagenum" title="110"><a name="Page_110" id="Page_110"></a></span>
+unfailing relative condition of formative causes and cause-recipients.</p>
+
+<p>Finally, in <em>functional harmony</em> we have an expression
+descriptive of the unity of organic function, and so we
+may state, as the latest result of our analytical theory of
+development up to this point, that individual morphogenesis
+is marked by a <em>threefold harmony</em> among its parts.</p>
+
+
+<h5 class="fs120 mb05em">ε. <span class="lowercase smcap">ON RESTITUTIONS</span><a name="FNanchor_47_47" id="FNanchor_47_47"></a><a href="#Footnote_47_47" class="fnanchor">47</a></h5>
+
+<p>At this stage we leave for a while our analytical
+studies of ontogeny proper. We must not forget that
+typical ontogenesis is not the only form in which morphogenesis
+can occur: the organic form is able to restore
+disturbances of its organisation, and it certainly is to be
+regarded as one of the chief problems of analytical morphogenesis
+to discover the specific and real stimulus which
+calls forth the restoring processes. For simply to say that
+the disturbance is the cause of the restoration would be to
+evade the problem instead of attacking it. But there are
+still some other problems peculiar to the doctrine of
+restitutions.</p>
+
+<p class="tac pt12b02em"><i>A few Remarks on Secondary Potencies and on Secondary
+Morphogenetic Regulations in General</i></p>
+
+<p>We have only briefly mentioned in a previous chapter
+that there exist many kinds of potencies of what we call
+the secondary or truly restitutive type, and that their
+distribution may be most various and quite independent<span class="pagenum" title="111"><a name="Page_111" id="Page_111"></a></span>
+of all the potencies for the primary processes of ontogeny
+proper. Let us first add a few words about the concept
+of “secondary restitution” and about the distribution
+of secondary potencies in general.</p>
+
+<p>Primary ontogenetic processes founded upon primary
+potencies may <em>imply</em> regulation, or more correctly, restitution
+in many cases: so it is, when fragments of the blastula
+form the whole organism, or when the mesenchyme cells
+of Echinus reach their normal final position by an attraction
+on the part of specific localities of the ectoderm in spite
+of a very abnormal original position enforced upon them
+by experiment. In these cases we speak of primary
+regulations or restitutions; disturbances are neutralised by
+the very nature of the process in question. We speak
+of secondary restitution whenever a disturbance of organisation
+is rectified by processes foreign to the realm of
+normality; and these abnormal lines of events are revealed
+to us in the first place by the activity of potencies which
+remain latent in ontogeny proper.</p>
+
+<p>We know already that a certain kind of secondary
+restitution has been discovered lately, very contradictory
+to the theoretical views of Weismann; the process of
+restoration being carried out not by any definite part of
+the disturbed organisation, but by all the single elements
+of it. The problem of the distribution of secondary
+potencies in these cases of so-called “re-differentiation” is
+to form our special study in the next chapter. In all
+other cases restoration processes start from specific localities;
+if they occur on the site of the wound which caused the
+disturbance, we speak of regeneration; if they occur at
+some distance from the wound, we call them adventitious<span class="pagenum" title="112"><a name="Page_112" id="Page_112"></a></span>
+processes. Besides these three types of processes of restitution
+there may be mentioned a fourth one, consisting in
+what is generally called compensatory hypertrophy; the
+most simple case of such a compensatory process is when
+one of a pair of organs, say a kidney, becomes larger after
+the other has been <span class="nowrap">removed.<a name="FNanchor_48_48" id="FNanchor_48_48"></a><a href="#Footnote_48_48" class="fnanchor">48</a></span> Finally, at least in plants, a
+change of the directive irritability, of so-called “geotropism”
+for instance, in certain parts may serve to restore other
+more important parts.</p>
+
+<p>In two of these general types of restitution, in regeneration
+proper and in the production of adventitious organs,
+the potencies which underlie these processes may be said
+to be “complex.” It is a complicated series of events, a
+proper morphogenesis in itself, for which the potency has
+to account, if, for instance, a worm newly forms its head
+by regeneration, or if a plant restores a whole branch in
+the form of an adventitious bud.</p>
+
+<p>Such generalisations as are possible about the distribution
+of complex potencies are reserved for a special part
+of our future discussion.</p>
+
+<p>Secondary restitution is always, like ontogeny, a process
+of morphogenesis, and therefore all the questions about
+single formative stimuli, and about internal and external
+conditions or means, occur again. But of course we cannot
+enter into these problems a second time, and may only<span class="pagenum" title="113"><a name="Page_113" id="Page_113"></a></span>
+say that, especially in regeneration proper, the specific type
+of the regenerative formation of any part may differ very
+much from the ontogenetic type of its origin: the end of
+both is the same, but the way can be even fundamentally
+different in every respect.</p>
+
+<p class="tac pt12b02em"><i>The Stimuli of Restitutions</i><a name="FNanchor_49_49" id="FNanchor_49_49"></a><a href="#Footnote_49_49" class="fnanchor">49</a></p>
+
+<p>But now we turn to the important question: what is
+the precise <span class="nowrap">stimulus<a name="FNanchor_50_50" id="FNanchor_50_50"></a><a href="#Footnote_50_50" class="fnanchor">50</a></span> that calls forth processes of restitution;
+or, in other words, what must have happened in order
+that restitution may occur?</p>
+
+<p>That the operation in itself, by its removing of mechanical
+obstacles, cannot be the true stimulus of any restitutions,
+is simply shown by all those restitutions that do not
+happen at the place of the wound. If we took a narrower
+point of view, and if we only considered regeneration proper
+from the wound itself, we might probably at first be
+inclined to advocate the doctrine that the removing of
+some obstacles might in fact be the stimulus to the process
+of restoration; but, even then, why is it that just what is
+wanted grows out? Why is there not only growth, but
+specific growth, growth followed by specification? The
+removing of an obstacle could hardly account for that.
+But, of course, taking account of all the adventitious<span class="pagenum" title="114"><a name="Page_114" id="Page_114"></a></span>
+restitutions&mdash;that is, all restorations not beginning at the
+wound itself&mdash;the theory that the removing of obstacles
+is the stimulus to restoration becomes, as we have said,
+quite <span class="nowrap">impossible.<a name="FNanchor_51_51" id="FNanchor_51_51"></a><a href="#Footnote_51_51" class="fnanchor">51</a></span></p>
+
+<p>But where then is the stimulus to be found? There
+is another rather simple theory of the “Auslösung” of
+<span class="nowrap">restitutions,<a name="FNanchor_52_52" id="FNanchor_52_52"></a><a href="#Footnote_52_52" class="fnanchor">52</a></span> which starts from the phenomena of compensatory
+hypertrophy and some occurrences among plants.
+The removal of some parts of the organism, it is said,
+will bring its other parts into better conditions of nutrition,
+and therefore these parts, particularly if they are of the
+same kind, will become larger. Granted for the moment
+that such a view may hold in cases when one of a pair
+of glands becomes larger after the other has been removed,
+or when pruning of almost all the leaves of a tree leads to
+the rest becoming larger, it certainly must fail to explain
+the fact that in other cases true <em>new</em> formations may arise
+in order to restore a damaged part, or that the latter may
+be regenerated in its proper way. For <em>merely quantitative</em>
+differences in the mixture of the blood or of the nourishing
+sap in plants can never be a sufficient reason for the highly
+typical and <em>qualitative</em> structure of newly-formed restitutions.
+And even in the most simple cases of a mere increase in
+the size of some parts, that is, in the simplest cases of
+so-called compensatory <span class="nowrap">hypertrophy,<a name="FNanchor_53_53" id="FNanchor_53_53"></a><a href="#Footnote_53_53" class="fnanchor">53</a></span> it is at least doubtful,<span class="pagenum" title="115"><a name="Page_115" id="Page_115"></a></span>
+if not very improbable, that the compensation is accomplished
+in such a purely passive way, because we know that in
+other cases it is usually the growth of the young parts
+that actively attracts the nourishment: there is first
+differentiation and growth, and <em>afterwards</em> there is a change
+in the direction of the nourishing fluids.</p>
+
+<p>The process of true regeneration, beginning at the
+locality of the wound itself, has been shown by Morgan,
+even as regards its rate, to occur quite irrespectively of the
+animal being fed or <span class="nowrap">not.<a name="FNanchor_54_54" id="FNanchor_54_54"></a><a href="#Footnote_54_54" class="fnanchor">54</a></span> There could hardly be a better
+demonstration of the fundamental fact that food assists
+restitution, but does not “cause” it in any way.</p>
+
+<p>But in spite of all we have said, there seems to be some
+truth in regarding the nutritive juices of animals and plants
+as somehow connected with the stimulus of restitutions:
+only in this very cautious form, however, may we make
+the hypothesis. It has been shown for both animals and
+plants, that morphogenesis of the restitutive type may be
+called forth even if the parts, now to be “regenerated”
+have not been actually removed; <i>e.g.</i> in the so-called
+super-regeneration of legs and tails in Amphibia, of the
+head in Planarians, of the root-tip in plants and in some
+other cases. Here it has always been a disturbance of the<span class="pagenum" title="116"><a name="Page_116" id="Page_116"></a></span>
+normal connection of some parts with the rest of the
+organism which proved to be the reason of the new formation.
+This shows that something to do with the communication
+among parts is at least connected with restitution, and
+this communication may go on either by the unknown
+action of specific tissues or by the aid of the blood or <span class="nowrap">sap.<a name="FNanchor_55_55" id="FNanchor_55_55"></a><a href="#Footnote_55_55" class="fnanchor">55</a></span>
+But in what this change or break of specific communication
+consists, is absolutely unknown. One might suppose that
+each part of the organisation constantly adds some sort of
+ferment to the body fluids outside or inside the cells, that
+the removing of any part will change the composition of
+these fluids in this particular respect, and that this change
+acts as a sort of communication to summon the restituting
+parts of the whole to do their <span class="nowrap">duty.<a name="FNanchor_56_56" id="FNanchor_56_56"></a><a href="#Footnote_56_56" class="fnanchor">56</a></span></p>
+
+<p>But I see quite well that such a theory is very little<span class="pagenum" title="117"><a name="Page_117" id="Page_117"></a></span>
+satisfactory; for what has to be done in restitution in
+each case is not a simple homogeneous act, for which one
+special material might account, but is a very complicated
+work in itself. It was the defect of the theory of “organ-forming
+substances” as advocated by Sachs, that it overlooked
+this point.</p>
+
+<p>So all we know about the proper stimuli of restitutions
+is far from resting on any valid grounds at all; let us not
+forget that we are here on the uncertain ground of what
+may be called the newest and most up-to-date branch of
+the physiology of form. No doubt, there will be something
+discovered some day, and the idea of the “whole” in
+organisation will probably play some part in it. But in
+what manner that will happen we are quite unable to
+predict.</p>
+
+<p>This is the first time that, hypothetically at least, the
+idea of the whole has entered into our discussion. The
+same idea may be said to have entered it already in a
+more implicit form in the statement of the threefold
+harmony in ontogeny.</p>
+
+<p>Let us now see whether we can find the same problem
+of the “whole” elsewhere, and perhaps in more explicit
+and less hypothetical form. Let us see whether our
+analytical theory of development is in fact as complete as
+it seemed to be, whether there are no gaps left in it which
+will have to be filled up.</p>
+
+<p><span class="pagenum" title="118"><a name="Page_118" id="Page_118"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The Problem of Morphogenetic Localisation</span></h4>
+
+<h5 class="fs120 mb05em">α. <span class="lowercase smcap">THE THEORY OF THE HARMONIOUS-EQUIPOTENTIAL SYSTEM<br />
+FIRST PROOF OF THE AUTONOMY OF LIFE</span></h5>
+
+<p>We have come to the central point of the first part of
+these lectures; we shall try in this chapter to decide a
+question which is to give life its place in Nature, and
+biology its place in the system of sciences. One of the
+foundation stones is to be laid upon which our future
+philosophy of the organism will rest.</p>
+
+
+<p class="tac pt12b02em"><i>The General Problem</i></p>
+
+<p>Our analytical theory of morphogenesis has been founded
+upon three elementary concepts: the prospective potency,
+the means, and the formative stimulus. Its principal object
+has been to show that all morphogenesis may be resolved
+into the three phenomena expressed by those concepts;
+in other terms, that morphogenesis may be proved to
+consist simply and solely of what is expressed by them.
+Have we indeed succeeded in attaining this object? Has
+nothing been left out? Is it really possible to explain
+every morphogenetic event, at least in the most general
+way, by the aid of the terms potency, means, and stimulus?</p>
+
+<p>All of these questions are apt to lead us to further<span class="pagenum" title="119"><a name="Page_119" id="Page_119"></a></span>
+considerations. Perhaps these considerations will give us
+a very clear and simple result by convincing us that it is
+indeed possible to analyse morphogenesis in our schematic way.</p>
+
+<p>But if the answer were a negative one? What would
+that suggest?</p>
+
+<p>The full analysis of morphogenesis into a series of single
+formative occurrences, brought about by the use of given
+means and on the basis of given potencies, might assure
+us, perhaps, that, though not yet, still at some future time,
+a further sort of analysis will be possible: the analysis into
+the elemental facts studied by the sciences of inorganic
+nature. The organism might prove to be a machine, not
+only in its functions but also in its very origin.</p>
+
+<p>But what are we to say if even the preliminary analysis,
+which possibly might lead to such an ultimate result, fails?</p>
+
+<p>Let us then set to work. Let us try to consider most
+carefully the topic in which our concept of the formative
+cause or stimulus may be said to be centred, the <em>localisation</em>
+of all morphogenetic effects. Is it always possible in
+fact to account for the typical localisation of every
+morphogenetic effect by the discovery of a single specific
+formative stimulus? You will answer me, that such an
+analysis certainly is not possible at present. But I ask
+you again, are there any criteria that it is possible, at least
+in principle; or are there any criteria which will render
+such an aim of science impossible for all future time?</p>
+
+
+<p class="tac pt12b02em"><i>The Morphogenetic “System”</i></p>
+
+<p>We know from our experimental work that many, if
+not all, of the elementary organs in ontogeny show one<span class="pagenum" title="120"><a name="Page_120" id="Page_120"></a></span>
+and the same prospective potency distributed equally over
+their elements. If we now borrow a very convenient term
+from mechanics, and call any part of the organism which
+is considered as a unit from any morphogenetic point of
+view, a morphogenetic “<em>system</em>,” we may sum up what
+we have learnt by saying that both the blastoderm of the
+echinoderms, at least around its polar axis, and also the
+germ-layers of these animals, are “systems” possessing an
+equal potentiality in all of their elements, or, in short, that
+they are <em>equipotential systems</em>.</p>
+
+<p>But such a term would not altogether indicate the real
+character of these systems.</p>
+
+<p>Later on we shall analyse more carefully than before
+the distribution of potencies which are the foundation both
+of regeneration proper and of adventitious growth, and
+then we shall see that, in higher plants for instance, there
+is a certain “system” which may be called the organ
+proper of restitutions, and which also in each of its elements
+possesses the same restoring potency; I refer to the well-known
+cambium. This cambium, therefore, also deserves
+the name of an “equipotential system.” But we know
+already that its potencies are of the complex type, that they
+consist in the faculty of producing the <em>whole</em>, of such a
+complicated organisation as a branch or a root, that the
+term “equipotential system” is here only to signify that
+such a complicated unit may arise out of each of the cells
+of the cambium.</p>
+
+<p>The potencies we have been studying in the blastula or
+gastrula of echinoderms are not of the complex type: our
+systems are equipotential to the extent that each of their
+elements may play every <em>single</em> part in the totality of what<span class="pagenum" title="121"><a name="Page_121" id="Page_121"></a></span>
+will occur in the whole system; it is to this <em>single</em> part
+that the term “function of the position” relates. We
+therefore might call our systems equipotential systems with
+single potencies; or, more shortly, singular-equipotential
+systems.</p>
+
+<p>But even this terminology would fail to touch precisely
+the very centre of facts: it is not only the simplicity
+or singularity of their potencies which characterises the
+rôle of our systems in <span class="nowrap">morphogenesis,<a name="FNanchor_57_57" id="FNanchor_57_57"></a><a href="#Footnote_57_57" class="fnanchor">57</a></span> but far more important
+with respect to the production of form are two
+other leading results of the experimental researches. The
+proper act to be performed by every element in each actual
+case is in fact a single one, but the potency of any element
+as such consists in the possibility of many, nay of indefinitely
+many, single acts: that then might justify us in speaking of
+our systems as “indefinite equipotential,” were it not that
+another reason makes another title seem still more preferable.
+There are indeed indefinite singular potencies at
+work in all of our systems during ontogeny: but the sum
+of what happens to arise in every case out of the sum of
+the single acts performed by all of the single equipotential
+cells is not merely a sum but a unit; that is to say, there
+exists a sort of harmony in every case among the <em>real
+products</em> of our systems. The term <em>harmonious-equipotential
+system</em> therefore seems to be the right one to denote them.</p>
+
+<p>We now shall try first to analyse to its very extremes
+the meaning of the statement that a morphogenetic system
+is harmonious-equipotential.</p>
+
+<p><span class="pagenum" title="122"><a name="Page_122" id="Page_122"></a></span></p>
+
+
+<p class="tac pt12b02em"><i>The “Harmonious-Equipotential System”</i></p>
+
+<p>We have an ectoderm of the gastrula of a starfish here
+before us; we know that we may cut off any part of it in
+any direction, and that nevertheless the differentiation of
+the ectoderm may go on perfectly well and result in a
+typical little embryo, which is only smaller in its size than
+it would normally be. It is by studying the formation of
+the highly complicated ciliary band, that these phenomena
+can be most clearly understood.</p>
+
+<p>Now let us imagine our ectoderm to be a cylinder instead
+of being approximately a sphere, and let us imagine the
+surface of this cylinder unrolled. It will give us a plane
+of two definite dimensions, <i>a</i> and <i>b</i>. And now we have all
+the means necessary for the analytical study of the differentiation
+of an harmonious-equipotential system.</p>
+
+<p>Our plane of the dimensions <i>a</i> and <i>b</i> is the basis of the
+normal, undisturbed development; taking the sides of the
+plane as fixed localities for orientation, we can say that the
+actual fate, the “prospective value” of every element of the
+plane stands in a fixed and definite correlation to the
+length of two lines, drawn at right angles to the bordering
+lines of the plane; or, to speak analytically, there is a
+definite actual fate corresponding to each possible value of
+<i>x</i> and of <i>y</i>. Now, we have been able to state by our experimental
+work, that the prospective value of the elements of
+our embryonic organ is not identical with their “prospective
+potency,” or their possible fate, this potency being very
+much richer in content than is shown by a single case of
+ontogeny. What will be the analytical expression of such
+a relation?</p>
+
+<p><span class="pagenum" title="123"><a name="Page_123" id="Page_123"></a></span></p>
+
+<p>Let us put the question in the following way: on what
+factors does the fate of any element of our system depend
+in all possible cases of development obtainable by means of
+operations? We may express our results in the form of
+an equation:&mdash;</p>
+
+<p class="tac nowrap">
+<i>p.v. (X) = f(&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i><br />
+</p>
+
+<p><i>i.e.</i> “the prospective value of the element <i>X</i> is a function
+of&nbsp;.&nbsp;.&nbsp;.”&mdash;of what?</p>
+
+<p>We know that we may take off any part of the whole,
+as to quantity, and that a proportionate embryo will
+result, unless the part removed is of a very large size.
+This means that the prospective value of any element
+certainly depends on, certainly is a function of, the <em>absolute
+size</em> of the actually existing part of our system in the
+particular case. Let <i>s</i> be the absolute size of the system
+in any actual experimental case of morphogenesis: then we
+may write <span class="nowrap"><i>p.v. (X) = f(s&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i></span>. But we shall have to add
+still some other letter to this <i>s</i>.</p>
+
+<p>The operation of section was without restriction either
+as to the amount of the material removed from the germ, or
+as to the direction of the cut. Of course, in almost every
+actual case there will be both a definite size of the actual
+system and a definite direction of the cut going hand-in-hand.
+But in order to study independently the importance
+of the variable direction alone, let us imagine that we have
+isolated at one time that part of our system which is
+bounded by the lines <i>a<sub>1</sub> b<sub>1</sub></i>, and at another time an equal
+amount of it which has the lines <i>a<sub>2</sub> b<sub>2</sub></i> as its boundaries.
+Now since in both cases a typical small organism may result
+on development, we see that, in spite of their equal size<span class="pagenum" title="124"><a name="Page_124" id="Page_124"></a></span>
+the prospective value of every element of the two pieces cut
+out of the germ may vary even in relation to the direction
+of the cut itself. Our element, <i>X</i>, may belong to both of
+these pieces of the same size: its actual fate nevertheless
+will be different. Analytically, it may be said to change in
+correspondence to the actual position of the actual boundary
+lines of the piece itself with regard to the fundamental lines
+of orientation, <i>a</i> and <i>b</i>; let this actual position be expressed
+by the letter <i>l</i>, <i>l</i> marking the distance of <span class="nowrap">one<a name="FNanchor_58_58" id="FNanchor_58_58"></a><a href="#Footnote_58_58" class="fnanchor">58</a></span> of the actual
+boundary lines of our piece from <i>a</i> or <i>b</i>: then we are entitled
+to improve our formula by writing <span class="nowrap"><i>p.v. (X) = f(s, l&nbsp;.&nbsp;.&nbsp;.&nbsp;)</i></span>
+(Fig. 11).</p>
+
+<div class="figcenter" style="width: 440px;">
+<img src="images/fig11.jpg" width="440" height="276" alt="" />
+<p><span class="smcap">Fig. 11.&mdash;Diagram to show the Characteristics of an
+“Harmonious-equipotential System</span>.”</p>
+
+<p class="ml0em">The element <i>X</i> forms part of the systems <i>a b</i> or <i>a<sub>1</sub> b<sub>1</sub></i> or <i>a<sub>2</sub> b<sub>2</sub></i>; its prospective value is
+different in each case.</p>
+</div>
+
+<p>But the formula is not yet complete: <i>s</i> and <i>l</i> are what
+the mathematicians call variables: they may have any
+actual value and there will always be a definite value of <i>p.v.</i>,
+<i>i.e.</i> of the actual fate which is being considered; to every
+value of <i>s</i> and <i>l</i>, which as we know are independent of
+each other, there corresponds a definite value of the actual
+prospectivity. Now, of course, there is also a certain factor
+at work in every actual case of experimental or normal
+development, which is <em>not</em> a variable, but which is the same
+in all cases. This factor is a something embraced in the
+prospective potency of our system, though not properly
+identical with it.</p>
+
+<p>The prospective potency of our system, that is to say of
+each of its elements, is the sum total of what can be done
+by all; but the fact that a typically proportionate development
+occurs in every possible case, proves that this sum
+comes into account, not merely as a sum, but as a sort of<span class="pagenum" title="125"><a name="Page_125" id="Page_125"></a></span>
+order: we may call this order the “relation of localities in
+the absolutely normal case.” If we keep in mind that the
+term “prospective potency” is always to contain this order,
+or, as we may also call it, this “relative proportionality,”
+which, indeed, was the reason for calling our systems
+“harmonious,” then we may apply it without further explanation
+in order to signify the <em>non-variable</em> factor on
+which the prospective value of any element of our systems
+depends, and, if we denote the prospective potency, embracing
+order, by the letter <i>E</i>, we are now able to complete our
+formula by saying <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span>.</p>
+
+<p>So far the merely analytical study of the differentiation
+of harmonious-equipotential <span class="nowrap">systems.<a name="FNanchor_59_59" id="FNanchor_59_59"></a><a href="#Footnote_59_59" class="fnanchor">59</a></span></p>
+<p><span class="pagenum" title="126"><a name="Page_126" id="Page_126"></a></span></p>
+
+<p class="tac pt12b02em"><i>Instances of “Harmonious-Equipotential Systems”</i></p>
+
+<p>We must try at first to learn a few more positive facts
+about our systems, in order that we may know how important
+is the part which they play in the whole animal
+kingdom, and in order that our rather abstract analysis may
+become a little more familiar to us. We know already that
+many of the elementary morphogenetic organs have been really
+proved to be harmonious-equipotential systems, and that the
+same probably is true of many others; we also know that
+the immature egg of almost all animals belongs to this type,
+even if a fixed determination of its parts may be established
+just after maturation. Moreover, we said, when speaking
+about some new discoveries on form-restitution, that there
+are many cases in which the processes of restitution do not
+proceed from single localities, the seat of complex potencies
+in the organism, but in which each <em>single</em> part of the
+truncated organism left by the operation has to perform
+one <em>single</em> act of restoration, the full restitution being the
+result of the totality of all. These cases must now be
+submitted to a full analysis.</p>
+
+<p>All of you have seen common sea-anemones or sea-roses,
+and many of you will also be familiar with the so-called
+hydroid polyps. <i class="biological-name">Tubularia</i> is one genus of them: it looks
+like a sea-anemone in miniature placed on the top of a stem
+like a flower. It was known already to Allman that
+<i class="biological-name">Tubularia</i> is able to restore its flower-like head when that
+is lost, but this process was taken to be an ordinary regeneration,
+until an American zoologist, Miss Bickford,
+succeeded in showing that there was no regeneration process
+at all, in the proper sense of the word, no budding of the<span class="pagenum" title="127"><a name="Page_127" id="Page_127"></a></span>
+missing part from the wound, but that the new tubularian
+head was restored by the combined work of many parts of
+the stem. Further analysis then taught us that <i class="biological-name">Tubularia</i>
+indeed is to be regarded as the perfect type of an
+harmonious-equipotential system: you may cut the stem at
+whatever level you like: a certain length of the stem will
+always restore the new head by the co-operation of its parts.
+As the point of section is of course absolutely at our choice,
+it is clear, without any further discussion, that the prospective
+value of each part of the restoring stem is a
+“function of its position,” that it varies with its distance
+from the end of the stem; and so at once we discover one
+of the chief characteristics of our systems. But also the
+second point which enters into our formula can be
+demonstrated in <i class="biological-name">Tubularia</i>: the dependence of the fate of
+every element on the actual size of the system. You would
+not be able to demonstrate this on very long stems, but if
+you cut out of a <i class="biological-name">Tubularia</i> stem pieces which are less than
+ten millimetres in length, you will find the absolute size of
+the head restored to be in close relation to the length of
+the stem piece, and this dependence, of course, includes the
+second sort of dependence expressed in our formula.</p>
+
+<p>The figures will serve to show you a little more concretely
+what has been described. The head of <i class="biological-name">Tubularia</i>
+consists of a sort of broad base with a thin proboscis upon
+it, both bearing a large number of tentacles; these tentacles
+are the first things to be seen as primordia (“Anlagen”) in
+the process of restitution. You notice two rings of longitudinal
+lines inside the stem; the lines will become walls and then
+will separate from the stem until they are only connected
+with it at their basal ends; the new tentacles are ready as<span class="pagenum" title="128"><a name="Page_128" id="Page_128"></a></span>
+soon as that has happened, and a process of growth at the
+end will serve to drive the new head out of the so-called
+perisarc or horny skeleton, which surrounds the stem. By
+comparing the two figures, 12 <i>e</i>, and <i>g</i>, you easily find out
+that the absolute lengths of the two tentacle rings are very
+different, and that both are in <span class="nowrap">proportion<a name="FNanchor_60_60" id="FNanchor_60_60"></a><a href="#Footnote_60_60" class="fnanchor">60</a></span> to the actual size
+of the stem (Fig. 12).</p>
+
+<div class="figcenter" style="width: 495px;">
+<img src="images/fig12.jpg" width="495" height="311" alt="" />
+<p><span class="smcap">Fig. 12.&mdash;Tubularia.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.</i></td><td class="tal ti">Diagram of the “Hydranth,” with its short and long tentacles.</td></tr>
+<tr><td class="tar vat"><i>b.</i></td><td class="tal ti">Restitution of a new hydranth inside the perisarc (<i>p</i>).</td></tr>
+<tr><td class="tar vat"><i>c.</i></td><td class="tal ti">The same&mdash;later stage; the tentacles are complete; the whole hydranth will be driven out of the perisarc by a process of growth that occurs at the locality marked ↑.</td></tr>
+<tr><td class="tar vat"><i>d.</i></td><td class="tal ti">A stem of <i class="biological-name">Tubularia</i> cut either at <i>a<sub>1</sub>b<sub>1</sub></i> or at <i>a<sub>2</sub>b<sub>2</sub></i> or at <i>a<sub>1</sub>c</i>.</td></tr>
+<tr><td class="tar vat"><i>e.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+<tr><td class="tar vat"><i>f.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>2</sub>b<sub>2</sub></i> which is equal in length to <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+<tr><td class="tar vat"><i>g.</i></td><td class="tal ti">Position of tentacles in the piece cut at <i>a<sub>1</sub>c</i>, which is half as long as <i>a<sub>1</sub>b<sub>1</sub></i>.</td></tr>
+</table>
+</div>
+
+<p><span class="pagenum" title="129"><a name="Page_129" id="Page_129"></a></span></p>
+<p>So we find our formula <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span> very well
+illustrated in <i class="biological-name">Tubularia</i>. The formula indeed may help us
+to predict, in any case, where a certain part of the polyp’s
+organisation is to originate, at least if we know all that is
+included under our letter <i>E</i>, <i>i.e.</i> the normal proportion of
+our form. Of course such prediction would not have much
+practical importance in all our cases of morphogenesis, but
+nevertheless I should like to state here that it is possible;
+for many scientific authors of recent times have urged the
+opinion that prediction of, and domination over, what will
+happen, can be the only true aims of sciences at all. I
+myself judge these aims to be of second or third-rate importance
+only, but, if they may be reached by what our
+purely theoretical study teaches, so much the better.</p>
+
+<div class="figcenter" style="width: 424px;">
+<img src="images/fig13.jpg" width="424" height="286" alt="" />
+<p><span class="smcap">Fig. 13.&mdash;Clavellina.</span></p>
+<table class="fs100" border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td class="tar vat"><i>a.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">Diagram of the normal animal: <i>E</i> and <i>J</i> = openings; <i>K</i> = branchial apparatus; <i>D</i> = intestine; <i>M</i> = stomach; <i>H</i> = heart.</td></tr>
+<tr><td class="tar vat"><i>b.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">The isolated branchial apparatus.</td></tr>
+<tr><td class="tar vat"><i>c-e.</i></td><td class="tal ti">Different stages of reduction of the branchial apparatus.</td></tr>
+<tr><td class="tar vat"><i>f.&nbsp;&nbsp;&nbsp;</i></td><td class="tal ti">The new <em>whole</em> little ascidian.</td></tr>
+</table>
+</div>
+
+<p>Another very typical case of a morphogenetic system
+of the harmonious type is supplied by the phenomena of
+restoration in the ascidian <i class="biological-name">Clavellina</i>. I cannot fully
+describe the organisation of this form (Fig. 13a), and it
+must suffice to say that it is very complicated, consisting
+of two very different chief parts, the branchial apparatus
+and the so-called intestinal sac; if these two parts of the
+body of <i class="biological-name">Clavellina</i> are separated one from the other, each
+may regenerate the other in the typical way, by budding
+processes from the wound. But, as to the branchial
+apparatus, there may happen something very different:
+it may lose almost all of its organisation and become a
+small white sphere, consisting only of epithelia corresponding
+to the germ-layers, and of mesenchyme between them,
+and then, after a certain period of rest, a new organisation
+will appear. Now this new organisation is not that of a
+branchial apparatus but represents a very small but com<span class="pagenum" title="130"><a name="Page_130" id="Page_130"></a></span>plete
+ascidian (Fig. 13). Such a fact certainly seems to
+be very important, not to say very surprising; but still
+another phenomena may be demonstrated on the animal
+which seems to be even more important. You first isolate
+the branchial apparatus from the other part of the body,
+and then you cut it in two, in whatever direction you
+please. Provided they survive and do not die, as indeed
+many of them do, the pieces obtained by this operation
+will each lose their organisation, as did the whole branchial
+apparatus, and then will each acquire another one, and
+this new organisation is also that of a <em>complete</em> little
+<i class="biological-name">Clavellina</i>. So we see that not only is the branchial
+apparatus of our animal capable of being transformed into
+a whole animal by the co-operative work of all its parts,
+but even each part of it may be transformed into a small
+<em>whole</em>, and it is quite at our disposal how large this part
+shall be, and what sort of a fragment of the original
+branchial apparatus it shall represent.</p>
+
+<p>We could hardly imagine a better instance of an
+harmonious-equipotential system.</p>
+
+<p>I cannot give you a description of all the other types
+of our systems subservient to restitution, and I can only
+mention here that the common hydra and the flatworm
+<i class="biological-name">Planaria</i> are very fine examples of them. But to one
+special case of harmonious equipotentiality you must allow
+me to direct your further attention.</p>
+
+<p>It has been known for many years that the Protozoa
+are also capable of a restoration of their form and organisation
+after disturbances, if at least they contain a certain
+amount of their nuclear substance. This process of restoration
+used to be regarded as belonging to the common type<span class="pagenum" title="131"><a name="Page_131" id="Page_131"></a></span>
+of regeneration proper, until T. H. Morgan succeeded in
+showing that in the genus <i class="biological-name">Stentor</i> it follows just the very
+lines which we know already from our study of embryonic
+organs or from <i class="biological-name">Tubularia</i>; that an harmonious-equipotential
+system is at the basis of what goes on. Now, you know
+that all Protozoa are but one highly organised cell: we
+have therefore here an instance where the so-called
+“elements” of our harmonious-morphogenetic system are
+not cells, but something inside of cells; and this feature
+must appear to be of very great moment, for it first shows,
+as we have already pointed out on another occasion, that
+morphogenesis is not dependent on cell-division, and it
+states at the same time that our concept of the harmonious-<span class="pagenum" title="132"><a name="Page_132" id="Page_132"></a></span>equipotential
+system may cover a very great area&mdash;that, in
+fact, it is a scheme of a very wide extent.</p>
+
+
+<p class="tac pt12b02em"><i>The Problem of the Factor</i> E</p>
+
+<p>We turn back again to considerations of a more abstract
+form. We left our analysis of the differentiation of the
+harmonious-equipotential systems, and particularly of the
+phenomena of localisation during this differentiation, at the
+point where we had succeeded in obtaining an equation
+as the expression of all those factors on which the prospective
+value, the actual fate, of any element of our
+systems depends, <span class="nowrap"><i>p.v. (X) = f(s, l, E)</i></span> was the short expression
+of all the relations involved; <i>s</i> and <i>l</i>, the absolute
+size of the system and the relative position of the element
+with respect to some fixed points, were independent variables;
+<i>E</i> was a constant, namely, the prospective potency, with
+special regard to the proportions embraced by it.</p>
+
+<p>We shall now study the significance of the factor <i>E</i>.</p>
+
+<p>What does this <i>E</i> mean? Is it a short expression
+merely for an actual sum of elemental agents having a
+common resultant? And, if so, of what kind are these
+agents? Or what may <i>E</i> mean, if it can be shown <em>not</em> to
+be a short sign for a mere sum?</p>
+
+
+<p class="tac pt12b02em"><i>No Explanation Offered by “Means” or “Formative Stimuli”</i></p>
+
+<p>For practical purposes it seems better if we modify the
+statement of our question. Let us put it thus: <i>E</i> is one
+of the factors responsible, among variables, for the localisation
+of organic differentiation; what then do we actually
+know about the causal factors which play a localising part<span class="pagenum" title="133"><a name="Page_133" id="Page_133"></a></span>
+in organogenesis? We, of course, have to look back to our
+well-studied “formative stimuli.” These stimuli, be they
+“external” or “internal,” come from without with respect to
+the elementary organ in which any sort of differentiation,
+and therefore of localisation, occurs: but in our harmonious
+systems no localising stimulus comes from without, as was
+the case, for instance, in the formation of the lens of the
+eye in response to the optical vesicle touching the skin.
+We know absolutely that it is so, not to speak of the self-evident
+fact that the general “means” of organogenesis
+have no localising value at <span class="nowrap">all.<a name="FNanchor_61_61" id="FNanchor_61_61"></a><a href="#Footnote_61_61" class="fnanchor">61</a></span></p>
+
+<p>So we see there is nothing to be done, either with
+the means or with the formative stimuli; both are entirely
+unable to account for those kinds of localisation during
+differentiation which appear in our harmonious systems.</p>
+
+<p>But is there no possibility of explaining the phenomena
+of organogenetic localisation by any other sort of interaction
+of parts? Two such possibilities may at the first glance
+seem to exist.</p>
+
+<p><span class="pagenum" title="134"><a name="Page_134" id="Page_134"></a></span></p>
+
+
+<p class="tac pt12b02em"><i>No Explanation Offered by a Chemical Theory
+of Morphogenesis</i></p>
+
+<p>Though never set forth, in the form of a properly worked-out
+theory, the view has sometimes been advocated by
+biologists, that a chemical compound of a very high degree
+of complication might be the very basis of both development
+and inheritance, and that such a chemical compound by its
+disintegration might direct morphogenesis.</p>
+
+<p>Let us first examine if such a view may hold for the
+most general features of organic morphogenesis. It seems
+to me that from the very beginning there exists one very
+serious objection to every chemical theory of form-building,
+in the mere fact of the possibility of the restoration of form
+starting from atypical localities. The mere fact, indeed,
+that there is such a thing as the regeneration of a leg of a
+newt&mdash;to say nothing about restitution of the harmonious
+type&mdash;simply <span class="nowrap">contradicts,<a name="FNanchor_62_62" id="FNanchor_62_62"></a><a href="#Footnote_62_62" class="fnanchor">62</a></span> it seems to me, the hypothesis,
+that chemical disintegration of one compound may govern
+the course of morphogenetic events: for whence comes
+the re-existence of the hypothetical compound, newly to
+be disintegrated, after disintegration <em>has</em> been completed
+once already? And we even know that regeneration may
+go on several times running from the same locality!</p>
+<p><span class="pagenum" title="135"><a name="Page_135" id="Page_135"></a></span></p>
+<p>But, if we intentionally disregard this difficulty, in spite
+of its fundamental character, how could the hypothesis of
+chemical disintegration give the reason for the differentiation
+of our harmonious-equipotential systems, with special
+regard to the localisation of it; how could it account, in
+other words, for the appearance of typically localised specifications
+in an organ for which no external localising causes
+can be predicated?</p>
+
+<p>Let us remember that a few original intimate differences
+exist in our harmonious systems: the main directions of
+the intimate protoplasmic structure including polarity and
+bilaterality. There are therefore three times two specified
+poles in each of these systems, at least in bilateral organisms,
+but no other differences are present in them. A few very
+simple cases of harmonious differentiation might indeed be
+understood on the theory of a disintegrating chemical compound
+in connection with these few differences. Imagine
+that the original compound, of the quantity <i>a</i>, is disintegrated
+to the amount of <i>a</i><sub>1</sub>; from <i>a</i><sub>1</sub> are formed the two more
+simple compounds, <i>b</i> and <i>c</i>, both of them in definite
+quantities; then we have the three chemical individuals,
+<i>a-a</i><sub>1</sub>, <i>b</i> and <i>c</i>, as the constituents of our harmonious system;
+and it now might be assumed, without any serious difficulty,
+though with the introduction of some new hypotheses, that
+the two poles of one of the fundamental axes of symmetry
+attract <i>b</i> and <i>c</i> respectively, <i>a-a</i><sub>1</sub> remaining unattracted
+between them. We thus should have the three elementary
+constituents of the system separated into three parts, and
+as they all three are of a definite quantity, their separation
+would mean that the system had been divided into three
+<span class="pagenum" title="136"><a name="Page_136" id="Page_136"></a></span>parts, <i>a-a</i><sub>1</sub>, <i>b</i> and <i>c</i>, also with regard to its proper form.
+It is clear, that by taking away any part of the original
+system, by means of operations, there would be taken away
+a certain amount of the original compound; say that <i>a/n</i>
+is left; then, of course, the three constituents after the
+partial disintegration would be <i>a-a<sub>1</sub>/n</i>, <i>b/n</i> and <i>c/n</i>, and so it
+follows that the proportionality of localisation would really
+be preserved in any case.</p>
+
+<p>But these considerations, evident as they seem to be in
+the most simple case, fail to satisfy in a really general
+sense: for two different reasons. First, they could never
+account for the fact that the differentiated organism by no
+means consists of so many different compounds as it shows
+single parts of its differentiation, but that, on the contrary,
+it only consists, as we know, of a certain rather limited
+number of true different morphogenetic elements, these
+elements occurring again and again&mdash;as for instance, nervous
+or muscular elements&mdash;but typical each time in locality,
+quantity, and form. And in the second place, the very
+<em>form</em> of elementary organs, their form as such, does not at
+all go hand-in-hand with chemical differences; this feature
+alone would absolutely overthrow any sort of a chemical
+morphogenetic theory to account for the problem of
+localisation. Take the typically arranged ring of the
+mesenchyme cells in our Echinus-gastrula, with its two
+spherical triangles, so typically localised; look at any sort
+of skeleton, in Radiolaria, or in starfishes, or in vertebrates:
+here you have form, real form, but form consisting of only
+one material. Not only is the arrangement of the elements
+of form typical here, <i>e.g.</i> the arrangement of the single<span class="pagenum" title="137"><a name="Page_137" id="Page_137"></a></span>
+parts of the skeleton of the hand or foot, but also the
+special form of each element is typical, <i>e.g.</i> the form of
+each single bone of the foot; and, on a purely chemical
+theory of morphogenesis the sufficient reason for the
+production of typical form in such a sense would be wanting.
+For atoms or molecules by themselves can only
+account for form which is arranged, so to speak, according
+to spatial geometry&mdash;as in fact they do in crystallography;
+but they can never account for form such as the skeleton
+of the nose, or hand, or foot. You will answer me perhaps,
+that there may be non-chemical agents in the <span class="nowrap">germ,<a name="FNanchor_63_63" id="FNanchor_63_63"></a><a href="#Footnote_63_63" class="fnanchor">63</a></span> responsible
+for typical form-localisation, but by such reasoning
+you would be departing from a purely chemical theory.
+Our next paragraph will be devoted to this side of the
+question.</p>
+
+<p>That is the principal reason for rejecting all sorts of
+chemical morphogenetic theories put forward to explain the
+problem of localisation; it is more explicit, and therefore,
+I suppose, still more convincing than the more general consideration
+that the very fact of restitutions in itself must
+contradict the hypothesis that a disintegration of compounds
+might be the directive agency in morphogenesis. To sum
+up: Specificity of organic form does not go hand-in-hand
+with specificity of chemical composition, and therefore cannot
+depend on it; and besides that, specific organic form is
+such that it can never be explained by atomic or molecular
+arrangement in the chemical sense; for, to state it in a
+short but expressive manner, the “form” of an atom or
+molecule can never be that of a lion or a monkey. To<span class="pagenum" title="138"><a name="Page_138" id="Page_138"></a></span>
+assume that would be to go beyond the limits of chemistry
+in chemistry itself.</p>
+
+
+<p class="tac pt12b02em"><i>No Machine Possible Inside the Harmonious Systems</i></p>
+
+<p>And now we turn to the last possibility which is left
+to us in our endeavour to “understand” the localisation of
+the differentiation in our harmonious-equipotential systems
+by the means of physics and chemistry. Outside causes
+have failed to account for it, chemical disintegration of a
+compound has failed too. But could there not exist some
+sort of complicated interactions amongst the parts of the
+harmonious system themselves? Could there not exist
+some kind of a real machine in the system, which, if once
+set going, would result in the differentiations that are to
+take place? Then we might say that the “prospective
+potency” of the system is in fact that machine; we should
+know what the letter <i>E</i> of our equation stood for: viz.,
+a resultant action of many complicated elemental interactions,
+and nothing more.</p>
+
+<p>Weismann, we know already, had assumed that a sort
+of machine was the prime mover of morphogenesis. We
+have seen that his theory cannot be true; the results of
+experiments most strongly contradict it. But, of course,
+the experiments only showed us that <em>such</em> a machine as <em>he</em>
+had imagined to exist could not be there, that development
+could not be governed by the disintegration of a given
+complicated structure into its simplest parts. But might
+not some other machine be imaginable?</p>
+
+<p>We shall understand the word “machine” in a most
+general sense. A machine is a typical configuration of<span class="pagenum" title="139"><a name="Page_139" id="Page_139"></a></span>
+physical and of chemical constituents, by the acting of which
+a typical effect is attained. We, in fact, lay much stress
+upon embracing in our definition of a machine the existence
+of chemical constituents also; we therefore understand by
+the word “machine” a configuration of a much higher degree
+of complication than for instance a steam-engine is. Of
+course a machine, whose acting is to be typical with regard
+to the three dimensions in space, has to be typically constructed
+with regard to these three dimensions itself; a
+machine that was an arrangement of elements in a strict
+plane could never have typical effects at right angles
+to that plane. This is a point which must well be kept
+in mind in all hypothetical considerations about machines
+that claim to explain morphogenesis.</p>
+
+<p>It must be granted that a machine, as we understand
+the word, might very well be the motive force of organogenesis
+in general, if only normal, that is to say, if only
+undisturbed development existed, and if a taking away of
+parts of our systems led to fragmental development.</p>
+
+<p>But we know that, at least in our harmonious-equipotential
+systems, quite another process occurs after parts
+have been taken away: the development that occurs is not
+fragmental but whole, only on a smaller scale.</p>
+
+<p>And we know, further, that this truly whole development
+sets in irrespective of the amount and direction of the
+separation. Let us first consider the second of these points.
+There may be a whole development out of each portion of
+the system&mdash;above certain limits&mdash;which is, say, of the
+volume <i>V</i>. Good! Then there ought to exist a machine, like
+that which exists in the whole undisturbed system, in this
+portion <i>V</i> also, only of smaller dimensions; but it also<span class="pagenum" title="140"><a name="Page_140" id="Page_140"></a></span>
+ought to exist in the portion <i>V</i><sub>1</sub> which is equal to <i>V</i> in
+amount, and also in <i>V</i><sub>2</sub>, in <i>V</i><sub>3</sub>, <i>V</i><sub>4</sub> and so on. Indeed,
+there do exist almost indefinitely many <i>V</i><sub>n</sub> all of which
+can perform the whole morphogenesis, and all of which
+therefore ought to possess the machine. But these different
+portions <i>V</i><sub>n</sub> are only partly different from each other in
+spatial relation. Many parts of <i>V</i><sub>2</sub> are also parts of <i>V</i><sub>1</sub> and
+of <i>V</i><sub>3</sub> and of <i>V</i><sub>4</sub> and so on; that is to say, the different
+volumes <i>V</i><sub>n</sub> overlap each other successively and in such a
+manner that each following one exceeds the preceding one
+in the line by a very small amount only. But what then
+about our machines? Every volume which may perform
+morphogenesis completely must possess the machine in its
+totality. As now every element of one volume may play
+any possible elemental rôle in every other, it follows that
+each part of the whole harmonious system possesses any
+possible elemental part of the machine equally well, all
+parts of the system at the same time being constituents of
+different machines.</p>
+
+<p>A very strange sort of machine indeed, which is the
+same in all its parts (Fig. 14)!</p>
+
+<div class="figcenter" style="width: 448px;">
+<img src="images/fig14.jpg" width="448" height="111" alt="" />
+<p><span class="smcap">Fig. 14.&mdash;An “Harmonious-equipotential System” of whatever kind.</span></p>
+<p>
+According to the “machine-theory” of life this system ought to possess a certain unknown very complicated machine <em>in its completeness</em>:<br />
+<span class="ml27em">(<i>a</i>) in its total length,</span><br />
+<span class="ml1em">and (<i>b</i>) in each of the equal volumes <i>v</i>, <i>v</i><sub>1</sub>, <i>v</i><sub>2</sub>, <i>v</i><sub>3</sub> and so on,</span><br />
+<span class="ml1em">and (<i>c</i>) in each of the unequal volumes <i>w</i>, <i>x</i>, <i>y</i>, and so on,</span><br />
+<span class="ml1em">and (<i>d</i>) in every imaginable volume, no matter of what size.</span><br />
+Therefore the “machine-theory” of life is absurd.
+</p>
+</div>
+
+<p>But we have forgotten, I see, that in our operation
+the absolute amount of substance taken away from the
+system was also left to our choice. From this feature
+it follows that not only all the different <i>V</i><sub>n</sub>, all of the
+same size, must possess the hypothetic machine in its
+completeness, but that all amounts of the values <i>V</i><sub>n</sub>-<i>n</i>,
+<i>n</i> being variable, must possess the totality of the machine
+also: and all values <i>V</i><sub>n</sub>-<i>n</i>, with their variable <i>n</i>, may again
+overlap each other.</p>
+
+<p>Here we are led to real absurdities!</p>
+
+<p><span class="pagenum" title="141"><a name="Page_141" id="Page_141"></a></span></p>
+
+<p>But what is the conclusion of our rather wild considerations?</p>
+
+<p>It seems to me that there is only one conclusion
+possible. If we are going to explain what happens in our
+harmonious-equipotential systems by the aid of causality
+based upon the constellation of single physical or chemical
+factors and events, there <em>must</em> be some such thing as a
+machine. Now the assumption of the existence of a machine
+proves to be absolutely absurd in the light of the experimental
+facts. <em>Therefore there can be neither any sort of a machine
+nor any sort of causality based upon constellation underlying
+the differentiation of harmonious-equipotential systems.</em></p>
+
+<p>For a machine, typical with regard to the three chief
+dimensions of space, cannot remain itself if you remove
+parts of it or if you <span class="nowrap">rearrange<a name="FNanchor_64_64" id="FNanchor_64_64"></a><a href="#Footnote_64_64" class="fnanchor">64</a></span> its parts at will.</p>
+
+<p>Here we see that our long and careful study of morphogenesis
+has been worth while: it has afforded us a result
+of the very first importance.</p>
+<p><span class="pagenum" title="142"><a name="Page_142" id="Page_142"></a></span></p>
+
+<p class="tac pt12b02em"><i>The Autonomy of Morphogenesis Proved</i></p>
+
+<p>No kind of causality based upon the constellations of
+single physical and chemical acts can account for organic
+individual development; this development is not to be
+explained by any hypothesis about configuration of physical
+and chemical agents. Therefore there must be something
+else which is to be regarded as the sufficient reason of
+individual form-production. We now have got the answer
+to our question, what our constant <i>E</i> consists in. It is not
+the resulting action of a constellation. It is not only a
+short expression for a more complicated state of affairs,
+it expresses <em>a true element of nature</em>. Life, at least morphogenesis,
+is not a specialised arrangement of inorganic events;
+biology, therefore, is not applied physics and chemistry: life
+is something apart, and biology is an independent science.</p>
+
+<p>All our results at present, indeed, are negative in their
+form; our evidence was throughout what is called <i lang="la" xml:lang="la">per
+exclusionem</i>, or indirect or apagogic. There were excluded
+from a certain number of possibilities all except one; a
+disjunctive proposition was stated in the form: <i>E</i> is either
+this, or that, or the other, and it was shown that it could
+not be any of all these except one, therefore it was proved
+to be that one. Indeed, I do not see how natural science
+could argue otherwise; no science dealing with inorganic
+phenomena does; something new and elemental must
+always be introduced whenever what is known of other
+elemental facts is proved to be unable to explain the facts
+in a new field of investigation.</p>
+
+<p>We shall not hesitate to call by its proper name what
+we believe we have proved about morphogenetic phenomena.<span class="pagenum" title="143"><a name="Page_143" id="Page_143"></a></span>
+What we have proved to be true has always been called
+<em>vitalism</em>, and so it may be called in our days again. But
+if you think a new and less ambitious term to be better
+for it, let us style it the doctrine of the <em>autonomy of life</em>,
+as proved at least in the field of morphogenesis. I know
+very well that the word “autonomy” usually means the
+faculty of <em>giving</em> laws to oneself, and that in this sense it
+is applied with regard to a community of men; but in our
+phrase autonomy is to signify the <em>being subjected</em> to laws
+peculiar to the phenomena in question. This meaning is
+etymologically defensible, and besides that I perhaps may
+remind you of a certain chapter of Professor Ward’s Gifford
+Lectures, in which he holds the view that, psychologically
+and epistemologically, there is more than a mere verbal
+relation between the civil and the natural “law.”</p>
+
+<p>Vitalism then, or the autonomy of life, has been proved
+by us indirectly, and cannot be proved otherwise so long as
+we follow the lines of ordinary scientific reasoning. There
+can indeed be a sort of direct proof of vitalism, but now is
+not the time to develop this proof, for it is not of the purely
+scientific character, not so naïve as our present arguments
+are, if you choose to say so. An important part of our
+lectures next summer will be devoted to this direct proof.</p>
+
+
+<p class="tac pt12b02em">“<i>Entelechy</i>”</p>
+
+<p>But shall we not give a name to our vitalistic or
+autonomous factor <i>E</i>, concerned in morphogenesis? Indeed
+we will, and it was not without design that we chose the
+letter <i>E</i> to represent it provisionally. The great father
+of systematic philosophy, Aristotle, as many of you will<span class="pagenum" title="144"><a name="Page_144" id="Page_144"></a></span>
+know, is also to be regarded as the founder of theoretical
+biology. Moreover, he is the first vitalist in history, for
+his theoretical biology is throughout vitalism; and a very
+conscious vitalism indeed, for it grew up in permanent
+opposition to the dogmatic mechanism maintained by the
+school of Democritus.</p>
+
+<p>Let us then borrow our terminology from Aristotle, and
+let that factor in life phenomena which we have shown to
+be a factor of true autonomy be called <em>Entelechy</em>, though
+without identifying our doctrine with what Aristotle meant
+by the word <ins title="entelecheia">έντελέχεια</ins>. We shall use this word only as a
+sign of our admiration for his great genius; his word is
+to be a mould which we have filled and shall fill with new
+contents. The etymology of the word <ins title="entelecheia">ἐντελέχεια</ins> allows us
+such liberties, for indeed we have shown that there is at
+work a something in life phenomena “which bears the end
+in itself,” <ins title="ho echei en eautô to telos">ὃ ἔχει ἐν ἑαυτᾣ τὸ τέλος</ins>.</p>
+
+<p>Our concept of entelechy marks the end of our analysis of
+individual morphogenesis. Morphogenesis, we have learned,
+is “epigenesis” not only in the descriptive but also in the
+theoretical sense: manifoldness in space is produced where
+no manifoldness was, real “evolutio” is limited to rather
+insignificant topics. But was there nothing “manifold”
+previous to morphogenesis? Nothing certainly of an
+<em>extensive</em> character, but there was something else: there was
+entelechy, and thus we may provisionally call entelechy an
+“<em>intensive manifoldness</em>.” That then is our result: not
+evolutio, but epigenesis&mdash;<span class="pagenum" title="145"><a name="Page_145" id="Page_145"></a></span>“epigenesis vitalistica.”</p>
+
+
+<p class="tac pt12b02em"><i>Some General Remarks on Vitalism</i></p>
+
+<p>We now shall leave entelechy where it stands: next
+summer we shall turn back to it and shall make its full
+logical and ontological analysis our chief study. At present
+we are satisfied with having proved its existence in nature,
+with having laid some of the foundations of a doctrine to be
+based upon it. I hope that these foundations will evince
+themselves strong: that is <span class="nowrap">all-important.<a name="FNanchor_65_65" id="FNanchor_65_65"></a><a href="#Footnote_65_65" class="fnanchor">65</a></span> It indeed has
+been the fault of all vitalism in the past that it rested on
+weak foundations. Therefore the discussion of the basis
+underlying our doctrine of the autonomy of life is to occupy
+us still a considerable time. We shall devote to it two
+more of this year’s lectures and three of the next; we shall
+examine all sorts of phenomena of life in order to find out
+if there are any further proofs of vitalism, independent
+perhaps, of what we way call our <em>first proof</em>, which is based
+upon the analysis of the <em>differentiation of harmonious-equipotential
+systems</em>. We shall find some more independent
+proofs; and besides that we shall find many kinds of
+phenomena upon which future times perhaps may erect
+more of such independent proofs.</p>
+
+<p>For we shall be chary of bestowing the name “proof”
+except on what is a proof indeed, of course according to our
+critical conviction. Vitalistic views in biology have arisen<span class="pagenum" title="146"><a name="Page_146" id="Page_146"></a></span>
+in rather numerous forms during the last fifteen years,
+especially in Germany&mdash;though in very strong contrast to
+the so-called official German biology&mdash;but I can only admit
+that one of all the arguments of “neo-vitalism” has proved
+its statements. I refer to the theory of “morphaesthesia” as
+developed by Noll, which we shall study briefly in the next
+lecture. I cannot concede that Reinke or Schneider or
+Pauly have really proved what they believe, and I cannot
+even allow to the most original thinker in this field,
+Gustav Wolff, that he has given a real demonstration of his
+views. He states that the existence of so-called “primary
+purposefulness,” that is, the existence of adaptive processes,
+which cannot be imagined to have arisen on Darwinian
+principles, is able to prove vitalism; but I say that it only
+proves teleology, which is a broader concept than vitalism.</p>
+
+<p>The possibility of a machine at the root of the phenomena
+in question always has to be excluded in order that vitalism
+may be proved, and I cannot grant that the necessity of
+such an exclusion has been actually shown by any of my
+fellow-combatants against so-called mechanism, except <span class="nowrap">Noll.<a name="FNanchor_66_66" id="FNanchor_66_66"></a><a href="#Footnote_66_66" class="fnanchor">66</a></span></p>
+
+
+<p class="tac pt12b02em"><i>The Logic of our First Proof of Vitalism</i></p>
+
+<p>Let us devote the end of our present lecture to an
+account of the logical means by which it has been possible
+to develop what we hope will be regarded as a true <em>proof</em>
+of life autonomy.</p>
+
+<p>Firstly, we have looked upon the phenomena of<span class="pagenum" title="147"><a name="Page_147" id="Page_147"></a></span>
+morphogenesis without any prepossessions; we may say
+that we have fully surrendered ourselves to them; we have
+not attacked them with any sort of dogmatism except the
+inherent dogmatism of all reasoning. But this dogmatism,
+if it may be called so, does not postulate that the results of
+the inorganic doctrines must hold for the organic world, but
+only that both the inorganic and the organic must be
+subject to certain most general principles.</p>
+
+<p>By studying life as a given phenomenon, by fully
+devoting ourselves to our problem, we not only have
+analysed into its last elements what was given to us as
+our subject, but we also, more actively, have created new
+combinations out of those elements: and it was from the
+discussion of these positive constructions that our argument
+for vitalism was derived.</p>
+
+<p>We have analysed morphogenesis into elementary processes,
+means, potency, formative stimulus, just as the
+physicist analyses mechanics into time, velocity, mass, and
+force; we have then rearranged our elements into “systems”&mdash;the
+equipotential systems, the harmonious-equipotential
+system in particular, just as the physicist composes
+his elements into the concepts of momentum or of kinetic
+energy or of work. And finally, we have discussed our
+compositions and have obtained our result, just as the
+physicist gets his ultimate results by discussing work and
+kinetic energy and momentum.</p>
+
+<p>Of course the comparison is by no means intended to
+show that mechanics and biology are sciences of the same
+kind. In my opinion, they are not so at all; but nevertheless
+there do exist similarities of a logical kind between them.</p>
+
+<p>And it is not the formal, logical character alone which<span class="pagenum" title="148"><a name="Page_148" id="Page_148"></a></span>
+allows us to compare biology with other natural sciences:
+there is still something more, there is one kind of assumption
+or postulate, or whatever you may choose to call it,
+without which all science whatever would be altogether
+<em>impossible</em>. I refer to the concept of <em>universality</em>. All
+concepts about nature which are gained by positive construction
+out of elements resulting from analysis, claim to
+be of <em>universal validity</em>; without that claim there could
+indeed be no science.</p>
+
+<p>Of course this is no place for a lecture on methodology,
+and it therefore must suffice to make one remark with
+special regard to our purpose, which we should like to
+emphasise. Our concept of the harmonious-equipotential
+system&mdash;say rather, our concept of the prospective
+potency itself&mdash;presumes the understanding that indeed
+<em>all</em> blastomeres and <em>all</em> stems of <i class="biological-name">Tubularia</i>, including those
+upon which we have <em>not</em> carried out our experiments,
+will behave like those we have experimented with; and
+those concepts also presume that a certain germ of Echinus,
+<i>A</i>, the blastomeres of which were not separated, would have
+given two whole larvae, if separation had taken place, while
+another germ, <i>B</i>, which actually gave us two larvae after
+separation, would only have given one without it. Without
+this presumption the concept of “potency” is meaningless,
+and, indeed, every assumption of a “faculty” or a
+“possibility” would be meaningless in the whole area of
+science.</p>
+
+<p>But this presumption can never be proved; it can only
+be postulated. It therefore is only with this postulate that
+our first proof of vitalism holds; but this restriction applies
+to <em>every</em> law of nature.</p>
+
+<p><span class="pagenum" title="149"><a name="Page_149" id="Page_149"></a></span></p>
+
+<p>I cannot force you to agree with this postulate: but if
+you decline you are practically saying that there exists a
+sort of pre-established harmony between the scientific object
+and the scientist, the scientist always getting into his hands
+such objects only as have been predestinated from the very
+beginning to develop two larvae instead of one, and so on.</p>
+
+<p>Of course, if that is so, no proof of natural laws is
+possible at all; but nature under such views would seem to
+be really dæmonic.</p>
+
+<p>And so, I hope, you will grant me the postulate of the
+universality of scientific concepts&mdash;the only “hypothesis”
+which we need for our argument.</p>
+
+<p><span class="pagenum" title="150"><a name="Page_150" id="Page_150"></a></span></p>
+
+
+<h4 class="fs120">4. <span class="smcap">On Certain other Features of Morphogenesis
+Advocating its Autonomy</span></h4>
+
+<p>Our next studies on the physiology of form will be
+devoted in the first place to some additional remarks about
+our harmonious-equipotential systems themselves, and about
+some other kinds of morphogenetic “systems” which show
+a certain sort of relationship with them. For it is of the
+greatest importance that we should become as familiar as
+possible with all those facts in the physiology of form upon
+the analysis of which are to be based almost all of the
+future theories that we shall have to develop in biology
+proper and philosophical. Our discussions, so far as they
+relate to questions of actual fact, will contain only one
+other topic of the same importance.</p>
+
+<p>But though it is designed to complete and to deepen
+our analysis, the present considerations may yet be said to
+mark a point of rest in the whole of our discussions: we have
+followed one single line of argumentation from the beginning
+until now; this line or this stream of thought, as you
+might call it, is now to break into different branches for a
+while, as if it had entered from a rocky defile into a plain.
+It seems to me that such a short rest will be not unconducive
+to a right understanding of all we have made out;
+and such a full and real conceiving again, such a realising<span class="pagenum" title="151"><a name="Page_151" id="Page_151"></a></span>
+of our problems of morphogenesis and their solutions, will
+be the best preparation for the philosophical part of these
+lectures.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HARMONIOUS-EQUIPOTENTIAL SYSTEMS FORMED BY
+WANDERING CELLS</span></p>
+
+<p>All of the harmonious-equipotential systems which we
+have studied so far were the bases of histological
+differentiation; that is to say, the processes of their
+differentiation consisted in specifically localised elements
+of theirs becoming different <i lang="la" xml:lang="la">in situ</i>. Now we know at
+least one type of systems which also may be called
+harmonious-equipotential, but the differentiation of which
+does not simply relate to elements at a fixed place. An
+additional phenomenon enters here into the sphere of the
+others. The elements not only become different where
+they are, but a specific changing of locality, a specific kind
+of wandering, goes hand-in-hand with differences relating
+to the prospective value to be attained. I am speaking of
+the formation of the larval skeleton of our well-known
+Echinus. We know that the mesenchyme cells, which have
+left the blastoderm and are arranged in a sort of ring of
+bilateral structure, are the starting-point of this skeleton:
+it indeed originates in a sort of secretive process on the
+part of the cells; the cells are moving about and are
+secreting carbonate of lime during their wandering. The
+experiments now have shown, as we know, that a whole,
+though smaller, skeleton may also be formed, if only
+a half or a quarter of the mesenchyme cells are present, as
+happens to be the case in all experiments with isolated<span class="pagenum" title="152"><a name="Page_152" id="Page_152"></a></span>
+blastomeres of the two or four-cell stage of cleavage. It
+is clear that in these cases the performance of each single
+cell must be different from what it is in the normal case, and
+that the same sort of differences in the morphogenetic
+performances appears again, if the two- and the four-cell
+stage are compared with each other. And there are still
+some other phenomena showing the possibility of different
+performances being carried out by the individual cells.
+Peter has shown that the number of mesenchyme cells
+may vary enormously under certain conditions; but, in
+spite of that, the skeleton always will be complete. It
+may be said that this line of research is only of a relative
+value to our own questions, as, of course, variability relates
+to different individuals: but it seems to me that it adds a
+very good supplementary instance to what the experiment
+on the individual itself has established.</p>
+
+<p>We should only be repeating ourselves if we were to
+analyse again what happens here as the expression of
+the harmonious-equipotentiality itself. But indeed there
+occurs something new in this instance: the single mesenchyme
+cell not only has to perform in each case that single
+act of specific secretion which the case requires, but it also
+has to wander to the right place in order to perform it;
+there must be some order, not only about the acts of
+secretion after wandering, but also in the migrations themselves.
+If undisturbed ontogeny alone were possible, and
+if therefore a theory like that of Weismann were in place,
+we might say perhaps that each mesenchyme-cell is specified
+not only as to its performance in secretion, but also with
+regard to its chemotactical irritability, the latter being
+typically localised, so that its effect becomes typical, thanks<span class="pagenum" title="153"><a name="Page_153" id="Page_153"></a></span>
+to the typical arrangement of all the cells with respect to
+each other. But that is certainly not the case. Now, you
+may ask yourselves if you could imagine any sort of a
+machine, which consists of many parts, but not even of an
+absolutely fixed number, all of which are equal in their
+faculties, but all of which in each single case, in spite of
+their potential equality, not only produce together a certain
+typical totality, but also arrange themselves typically in
+<em>order</em> to produce this totality. We <em>are</em> indeed familiar
+with certain occurrences in nature where such curious
+facts are observed, but I doubt if you would speak of
+“machines” in these cases. The mesenchyme-cells, in
+fact, behave just as a number of workmen would do who
+are to construct, say, a bridge. All of them <em>can</em> do every
+single act, all of them also <em>can</em> assume every single position:
+the result always is to be a perfect bridge; and it is to
+be a perfect bridge even if some of the workmen become
+sick or are killed by an accident. The “prospective values”
+of the single workman change in such a case.</p>
+
+<p>I well know that it is only an analogy which I am
+offering to you. The mesenchyme-cells have not “learned,”
+have no “experience.” All that is to occupy us next
+summer. But in spite of it, there is truth in the analogy;
+and perhaps you will prefer it to the merely abstract
+consideration.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN COMBINED TYPES OF MORPHOGENETIC SYSTEMS</span></p>
+
+<p>For the sake of completeness it may be remarked, only
+by the way, that the type of the proper harmonious-equipotential
+system may go hand in hand with another<span class="pagenum" title="154"><a name="Page_154" id="Page_154"></a></span>
+type of “systems” which play a part in morphogenesis; a
+type which we have shortly mentioned already and which
+will be studied fully a few chapters later. We know that
+there are equipotential systems with complex potencies: that
+is to say, systems which may produce a whole organism
+equally well from any one of their elements; we know the
+cambium of Phanerogams to be such a system. Now it is
+easily understood that the germ of our Echinus, say in the
+stage of two or four or eight cleavage cells, is not only an
+harmonious-equipotential system, but a complex-equipotential
+system too. Not only may there arise a whole organism
+out of 2/4 or 3/4; or 3/8, 4/8, 5/8, 6/8, 7/8 of its elements, in which cases
+the harmonious rôle of the single element with regard to
+its single performance in a totality is variable, but there
+may also arise four whole single larvae out of the four cells
+of the four-cell stage, or eight single whole larvae out of the
+eight-cell <span class="nowrap">stage.<a name="FNanchor_67_67" id="FNanchor_67_67"></a><a href="#Footnote_67_67" class="fnanchor">67</a></span> In these cases, of course, each of the
+four or eight elements has performed not a part of the
+totality, changing with its “position,” but the totality
+itself. With respect to these possible performances the
+“systems” present in the four or eight-cell stages of cleavage
+must be called complex-equipotential ones.</p>
+
+<p>We propose to give the name of <em>mixed-equipotential
+systems</em> to all those equipotential systems which, at the
+same time, may be regarded as belonging to the harmonious
+or to the complex type. It is not only among cleavage-stages
+that they are to be found; you may also find them
+very clearly exhibited in our ascidian <i class="biological-name">Clavellina</i> for instance.<span class="pagenum" title="155"><a name="Page_155" id="Page_155"></a></span>
+We know already that the branchial apparatus of this form
+is typically harmonious-equipotential, but it is complex-equipotential
+too, for it also may regenerate what is wanting
+in the proper way, by a budding from the wound; and the
+same is true of many other cases, the flatworm <i class="biological-name">Planaria</i> for
+instance.</p>
+
+<p>Another type of systems, which might be said to be of
+a higher degree, is exhibited in some very strange phenomena
+of regeneration. It was first shown most clearly by some
+experiments of Godlewski’s that a whole tail may be
+regenerated from a wound inflicted on the body of a
+newt, even if this wound involves section of only a
+portion of the body-diameter. Section of the whole of the
+body-diameter of course would cause the formation of the
+whole tail also; but it was found that even an incomplete
+cross-section of the body is capable of performing the whole
+on a smaller scale. The series of possible cross-sections
+which are all capable of regeneration would have to be
+called a system of the complex type in this case; but,
+now we learn that every <em>single</em> cross-section is of the
+harmonious type, we must speak of <em>complex-harmonious
+systems</em>. What we have described is not the only instance
+of our new type of morphogenetic systems. Some
+other instances had been discovered a few years earlier,
+though nobody had pointed out their true significance.
+In the flatworm <i class="biological-name">Planaria</i> a partial cross-section is also
+capable of forming a whole structure, say a head, and
+all cases of so-called “super-regeneration” after the
+infliction of a complicated wound probably belong here
+also.</p>
+
+<p>You may say that our two additions to the theory of<span class="pagenum" title="156"><a name="Page_156" id="Page_156"></a></span>
+systems are merely formal, and indeed I am prepared to
+concede that we shall not learn anything altogether new
+from their discussion: their analysis would lead either to
+what was our “first proof” of the autonomy of life-phenomena
+or to what will be our “second” one. But the
+mere descriptions of the facts discovered here will interest
+you, I think, and will fill your minds with more vivid
+pictures of the various aspects of form-autonomy.</p>
+
+<p>While dealing with our harmonious-equipotential systems
+as the starting-points of processes of restitution, <i>e.g.</i> in
+<i class="biological-name">Tubularia</i>, <i class="biological-name">Clavellina</i>, the flatworms, and other instances,
+we always have regarded cross-sections of the body as
+constituting the elements of equipotentiality. Now cross-sections,
+of course, are by no means simple in themselves,
+but are made up of very different tissues, which are
+derivates of all three of the original germ layers&mdash;ectoderm,
+mesoderm, and endoderm. Owing to this composite
+character of the cross-sections, taken as elements of
+harmonious systems, a special phenomenon of morphogenesis
+is presented to us, which teaches somewhat more
+than the mere concept of harmonious-equipotentiality can
+express. If composite elements concerned in morphogenesis
+result in one whole organisation in spite of the
+development of the single tissues of these elements going
+on independently, then there must be a sort of correspondence
+or reciprocity of the harmonious development
+among these tissue constituents themselves; otherwise a
+proportionate form could not be the final result. We may
+conveniently speak of a <em>reciprocity of harmony</em> as existing
+between the single tissues or germ layers which constitute
+many harmonious-equipotential systems, and there can be<span class="pagenum" title="157"><a name="Page_157" id="Page_157"></a></span>
+little doubt that we have here an important feature with
+regard to general <span class="nowrap">morphogenesis.<a name="FNanchor_68_68" id="FNanchor_68_68"></a><a href="#Footnote_68_68" class="fnanchor">68</a></span></p>
+
+<p>A few other groups of morphogenetic facts may find
+their proper place here, though they are not properly to be
+regarded as additions to the theory of harmonious systems
+but as forming a sort of appendix to it.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE “MORPHAESTHESIA” OF NOLL</span><a name="FNanchor_69_69" id="FNanchor_69_69"></a><a href="#Footnote_69_69" class="fnanchor">69</a></p>
+
+<p>We may briefly mention that group of botanical
+phenomena, by which the botanist Noll has been led to
+the concept of what he calls “morphaesthesia,” or the
+“feeling” for form; a concept, the full discussion of which
+would lead to almost the same conclusions as our analysis
+of the harmonious systems has done. In the Siphoneae, a
+well-known order of marine algae with a very complicated
+organisation as to their exterior form, the protoplasm which
+contains the nuclei is in a constant state of circulation
+round the whole body, the latter not being divided by
+proper cell-walls. On account of this constant movement
+it is certainly impossible to refer morphogenetic localisation
+to definite performances of the nuclei. Nor can any sort<span class="pagenum" title="158"><a name="Page_158" id="Page_158"></a></span>
+of structure in the outer protoplasmic layer, which is fixed,
+be responsible for it, for there is no such structure there:
+hence there must be a sort of feeling on the part of the
+plant for its relative body localities, and on account of
+this feeling morphogenesis occurs. This “feeling” is styled
+“morphaesthesia” by Noll, and to it he tries to refer all
+sorts of different botanical <span class="nowrap">form-phenomena,<a name="FNanchor_70_70" id="FNanchor_70_70"></a><a href="#Footnote_70_70" class="fnanchor">70</a></span> for instance
+what is called “autotropism,” that is, the fact that branches
+of plants always try to reassume their proper angle with
+regard to their orientation on the main axis, if this orientation
+has been disturbed. It may be an open question if
+this particular application of the theory is right: certainly
+there seems to be much truth in the establishment of the
+concept of morphaesthesia, and we only have to object to
+its psychological name. But that may be done in a more
+general form on a later occasion.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">RESTITUTIONS OF THE SECOND ORDER</span></p>
+
+<p>In the hydroid polyp <i class="biological-name">Tubularia</i>, already familiar to us
+as being a most typical representative of the harmonious-equipotential
+systems, a very interesting phenomenon has
+been <span class="nowrap">discovered<a name="FNanchor_71_71" id="FNanchor_71_71"></a><a href="#Footnote_71_71" class="fnanchor">71</a></span>, almost unparalleled at present but nevertheless
+of a general importance, a phenomenon that we may
+call a restitution of a restitution, or a restitution of the
+second order. You know that the first appearance of the
+new head of <i class="biological-name">Tubularia</i>, after an operation, consists in the<span class="pagenum" title="159"><a name="Page_159" id="Page_159"></a></span>
+formation of two rings of red lines, inside the stem, these
+rings being the primordia of the new tentacles. I removed
+the terminal ring by a second operation soon after it had
+arisen, disturbing in this way the process of restitution
+itself: and then the process of restitution itself became
+regulated. The organism indeed changed its course of
+morphogenesis, which was serving the purposes of a
+restitution, in order to attain its purpose in spite of the
+new disturbance which had occurred. For instance, it sometimes
+formed two rings out of the one that was left to it,
+or it behaved in a different way. As this difference of
+morphogenetic procedure is a problem by itself, to be
+discussed farther on, we shall postpone a fuller description
+of this case of a restitution of the second degree.</p>
+
+<p>At present I do not see any way of proving independently
+the autonomy of life by a discussion of these phenomena;
+their analysis, I think, would again lead us to our problem
+of localisation and to nothing else; at least in such an
+exact form of reasoning as we demand.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON THE “EQUIFINALITY” OF RESTITUTIONS</span><a name="FNanchor_72_72" id="FNanchor_72_72"></a><a href="#Footnote_72_72" class="fnanchor">72</a></p>
+
+<p>I have told you already that <i class="biological-name">Tubularia</i> in the phenomena
+of the regulation of restitutions offers us a second
+problem of a great general importance, the problem of
+the <em>Equifinality of Restitutions</em>. There indeed may occur
+restitutions, starting from one and the same initial state and
+leading to one and the same end, but using very different
+means, following very different ways in the different
+individuals of one and the same species, taken from the
+same locality, or even colony.</p>
+
+<p><span class="pagenum" title="160"><a name="Page_160" id="Page_160"></a></span></p>
+
+<p>Imagine that you have a piece of paper before you and
+wish to sketch a landscape. After drawing for some time
+you notice that you have miscalculated the scale with
+regard to the size of the paper, and that it will not be
+possible to bring upon the paper the whole of the landscape
+you want. What then can you do? You either may
+finish what you have begun to draw, and may afterwards
+carefully join a new piece of paper to the original one and
+use that for the rest of the drawing; or you may rub out
+all you have drawn and begin drawing to a new scale; or
+lastly, instead of continuing as you began, or erasing
+altogether, you may compromise as best you can by drawing
+here, and erasing there, and so you may complete the
+sketch by changing a little, according to your fancy, the
+proportions as they exist in nature.</p>
+
+<p>This is precisely analogous to the behaviour of our
+<i class="biological-name">Tubularia</i>. <i class="biological-name">Tubularia</i> also may behave in three different
+ways, if, as I described to you, the terminal one of its two
+newly arisen rings of tentacle primordia is removed again.
+It may complete what is left, say the basal tentacle ring,
+then put forth from the horny skeleton (the “perisarc”) the
+new head as far as it is ready, and finally complete this
+head by a regular process of budding regeneration. But it
+also may behave differently. It may “erase” by a process
+of retro-differentiation all that has been left of what had
+already been formed, and then may form <i lang="la" xml:lang="la">de novo</i> the
+totality of the primordia of a new head. Or, lastly, it
+may remove a part of the middle of the one ring of tentacle
+rudiments which was left, and may use this one ring for
+the formation of two, which, of course, will not be quite in
+the normal relations of place with regard to each other and<span class="pagenum" title="161"><a name="Page_161" id="Page_161"></a></span>
+to the whole, but will be regulated afterwards by processes
+of growth. Thus, indeed, there is a sort of equifinality of
+restitution: one starting-point, one end, but three different
+means and ways.</p>
+
+<p>It would, of course, contradict the principle of univocality,
+as we shall see more fully later on, to assume
+that there actually are different ways of regulation whilst
+all the conditions and stimuli are the same. We are
+obliged to assume, on the contrary, that this is not the
+case, that there are certain differences in the constellation,
+say of the general conditions of age or of metabolism,
+which are responsible for any given individual choosing
+one process of restitution instead of another; but even then
+the phenomenon of equifinality remains very striking.</p>
+
+<p>It has long been known that restitution in general does
+not always follow the same lines of morphogenesis as
+are taken by ontogeny, and it was this feature that once
+led Roux to point out that the adult forms of organisms
+seem to be more constant than their modes of origin. But,
+comparing ontogeny with restitution in general, we see that
+only the ends are the same, not the points of starting;
+the latter are normal or non-typical in ontogeny, atypical in
+restitution. In the new discoveries of an equifinality of
+restitutions we have the <em>same</em> starting-point, which is
+decidedly non-typical but atypical, <i>i.e.</i> dependent on our
+arbitrary choice, leading by <em>different</em> ways always to the
+<em>same</em> end.</p>
+
+<p>There may be many who will regard the fact of
+equifinality as a proof of vitalism. I should not like
+to argue in this easy way; I indeed prefer to include
+part of the phenomena of equifinality in our first proof<span class="pagenum" title="162"><a name="Page_162" id="Page_162"></a></span>
+of autonomy, and part in the second one, which is to
+follow.</p>
+
+<p>Another important phenomenon of the equifinality of
+regulation was discovered by Morgan. A species of the
+flatworm <i class="biological-name">Planaria</i> was found to restore its totality out of
+small pieces either by regeneration proper, if the pieces
+were fed, or by a sort of rearrangement of material, on the
+basis of its harmonious-equipotentiality, if they were kept
+fasting. It is important to note that here we see one of
+the conditions determining the choice of the way to
+restoration, as we also do in the well-known equifinal
+restitutions of the root in plants, where the behaviour of
+the organism depends on the distance of the operation-wound
+from the <span class="nowrap">tip.<a name="FNanchor_73_73" id="FNanchor_73_73"></a><a href="#Footnote_73_73" class="fnanchor">73</a></span> In <i class="biological-name">Tubularia</i> the actual stage of restitution
+that has been already reached by the stem when the second
+operation takes place, may account for the specification of
+its future organogenesis, but this is not at all clearly
+ascertained at present.</p>
+
+<p><i class="biological-name">Clavellina</i> also shows equifinality in its restitution, as
+has already been shortly mentioned. The isolated branchial
+apparatus may restitute itself by retro-differentiation to an
+indifferent stage followed by renovation; or it may regenerate
+the intestine-sac in the proper way. Nothing is known
+here about the conditions, except perhaps that young individuals
+seem more apt to follow the first of these two
+ways, older ones the second; but there are exceptions to
+this rule.</p>
+
+<p>The discussion of other instances of equifinality, though<span class="pagenum" title="163"><a name="Page_163" id="Page_163"></a></span>
+important in themselves, would not disclose anything
+fundamentally new, and so we may close the subject with
+the remark that nothing can show better than the fact
+of the equifinality of restitutions how absolutely inadequate
+all our scientific conceptions are when confronted with the
+actual phenomena of life itself. By analysis we have found
+differences of potencies, according as they are simple or
+complex; by analysis we have found differences of “systems,”
+differences of means, and indeed we were glad to be able to
+formulate these differences as strictly as possible: but now
+we see how, in defiance of our discriminations, one and the
+same species of animals behaves now like one sort of our
+“systems,” and now like the other; how it uses now one
+sort of “potencies,” now another.</p>
+
+<p>But even if it is granted that, in the presence of such
+phenomena of life, our endeavour seems to be like a child’s
+play on the shores of the ocean, I do not see any other
+way for us to go, so long, at least, as our goal is human
+science&mdash;that is, a study of facts as demanded by our mental
+organisation.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">REMARKS ON “RETRO-DIFFERENTIATION”</span></p>
+
+<p>We shall finish this part of our studies by mentioning
+a little more explicitly one fundamental fact which has
+already entered incidentally into our considerations, viz.
+<em>retro-</em> or <em>back-differentiation</em>.<a name="FNanchor_74_74" id="FNanchor_74_74"></a><a href="#Footnote_74_74" class="fnanchor">74</a> We know that it occurs in
+<i class="biological-name">Clavellina</i> and in <i class="biological-name">Tubularia</i>; we may add that it also
+happens in <i class="biological-name">Hydra</i>, and that in the flatworm <i class="biological-name">Planaria</i> the
+pharynx, if it is too large for a piece that is cut out,<span class="pagenum" title="164"><a name="Page_164" id="Page_164"></a></span>
+may be differentiated back and be replaced by a new
+pharynx, which is smaller.</p>
+
+<p>It is not death and sloughing of parts that occurs in
+these <span class="nowrap">cases,<a name="FNanchor_75_75" id="FNanchor_75_75"></a><a href="#Footnote_75_75" class="fnanchor">75</a></span> but a real process of active morphogenesis; not,
+however, a process consisting in the production of visible
+manifoldness, but the opposite. Loeb was the first to lay
+much stress upon this topic, and indeed, there may appear a
+very strange problem in its wake: the problem, whether
+<em>all</em> morphogenesis might be capable perhaps of going
+backwards under certain conditions.</p>
+
+<p>It is important to note that in <span class="nowrap">most<a name="FNanchor_76_76" id="FNanchor_76_76"></a><a href="#Footnote_76_76" class="fnanchor">76</a></span> cases retro-differentiation
+occurs in the service of restitution: it goes
+on wherever restitution requires it. This fact alone would
+show that not very much could be explained here by the
+discovery of modern chemistry, important as it is, that one
+and the same “ferment” or “enzyme” may affect both the
+composition and the decomposition of the same compound.
+We could regard what is called “catalysis” solely as an
+agent in the service of entelechy. But this point also will
+become clearer in another part of the work.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="165"><a name="Page_165" id="Page_165"></a></span></p>
+
+
+
+<h3><i>C.</i> ADAPTATION</h3>
+
+<h4 class="fs120"><span class="smcap">Introductory Remarks on Regulations in General</span></h4>
+
+
+<p>We have finished our long account of individual morphogenesis
+proper. If we look back upon the way we have
+traversed, and upon those topics in particular which have
+yielded us the most important general results, the
+material for the higher analysis which is to follow, it
+must strike us, I think, that all these results relate to
+regulations. In fact, it is “secondary” form-regulations,
+according to our terminology, that we have been studying
+under the names of equifinality, back-differentiation,
+restitution of the second order, and so on, and our harmonious-equipotential
+systems have figured most largely in processes
+of secondary form-regulations also. But even where that
+has not been the case, as in the analysis of the potencies of
+the germ in development proper, form-regulations of the
+other type have been our subject, regulations of the primary
+or immanent kind, the connection of normal morphogenetic
+events being regulatory in itself. It was not the phenomenon
+of organic regulation as such that afforded us the
+possibility of establishing our proof of the autonomy of
+morphogenesis: that possibility was afforded us by the
+analysis of the distribution of potencies; but upon this<span class="pagenum" title="166"><a name="Page_166" id="Page_166"></a></span>
+distribution regulation is based, and thus we may be said
+to have studied some types of regulation more or less
+indirectly when analysing potencies.</p>
+
+<p>It therefore seems to me that we shall have hopes of a
+successful issue to our inquiries, if we now, on passing to
+what is called the physiology of the vegetative functions,
+proceed to focus our attention on the concept of regulation
+as such. And that is what we shall do: on our way
+through the whole field of physiology, we shall always stop
+at any occurrence that has any sort of regulatory aspect,
+and shall always ask ourselves what this feature has to
+teach us.</p>
+
+<p>But let us first try to give a proper definition of our
+concept. We shall understand by “regulation” any occurrence
+or group of occurrences on a living organism which takes
+place after any disturbance of its organisation or normal
+functional state, and which leads to a reappearance of this
+organisation or this state, or at least to a certain approach
+thereto. Organisation is disturbed by any actual removal
+of parts; the functional state may be altered by any change
+among the parts of the organism on the one hand, by any
+change of the conditions of the medium on the other; for
+physiological functioning is in permanent interaction with
+the medium. It is a consequence of what we have said
+that any removal of parts also changes the functional state
+of the organism, but nevertheless organisation is more than
+a mere sum of reactions in functional life. All regulations
+of disturbances of organisation may be called <em>restitutions</em>,
+while to regulations of functional disturbances we shall
+apply the name <em>adaptations</em>. It is with <em>adaptations</em> that we
+have to deal in the following.</p>
+
+<p><span class="pagenum" title="167"><a name="Page_167" id="Page_167"></a></span></p>
+
+<p>Let us begin our studies of adaptations in a field which
+may justly be called a connecting link between morphogenesis
+and physiology proper, not yet wholly separated from the
+science of the organic form, morphology.</p>
+
+<p><span class="pagenum" title="168"><a name="Page_168" id="Page_168"></a></span></p>
+
+
+<h4 class="fs120">1. <span class="smcap">Morphological Adaptation</span></h4>
+
+<p><i>Morphological adaptation</i> is a well-established fact, and
+I need only mention the striking differences between the
+land and water form of amphibious plants, or the differences
+between the same species of plants in the Alps and in the
+plains, or the very different aspect of the arms of an athlete
+and of an ascetic, to recall to your memory what is meant
+by this term.</p>
+
+<p>Morphological adaptation is no part of individual
+morphogenesis proper, but occurs at the end of it; at least
+it never occurs previous to the full individual life of an
+organism, previous to its true functional life; for it relates
+to the functions of the complete organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE LIMITS OF THE CONCEPT OF ADAPTATION</span></p>
+
+<p>It is especially, though by no means exclusively, among
+plants that morphological adaptation assumes its most
+marked forms; and this topic, indeed, may very easily be
+understood if we remember that plant-life is in the very
+closest permanent dependence on the medium, and that
+this medium is liable to many changes and variations of
+all kinds. In order to elucidate our problem, it therefore
+seems convenient to restrict our considerations for a while<span class="pagenum" title="169"><a name="Page_169" id="Page_169"></a></span>
+to the study of plants. There exist very many external
+formative stimuli in the morphogenesis of vegetation:
+would it then be possible to regard every effect of such
+an external formative stimulus as a real morphological
+adaptation? No; for that would not meet the point.
+The general <em>harmony</em> of form is indeed concerned if gravity
+forces roots to shoot forth below at a spot where they can
+enter the ground, or if light induces branches and leaves
+to originate at places where they can obtain it for assimilation;
+but gravity and light themselves are mere formative
+stimuli&mdash;of the localising type&mdash;in these instances, for
+they relate only to the individual production of form, not
+to the functioning of already existing form. We therefore
+are warned not to confuse the effects of formative stimuli
+from without with real adaptive effects until we have fully
+analysed the particular case.</p>
+
+<p>We have drawn a sharp line between causes and means
+of morphogenesis, applying the term “means” to those conditions
+of the morphogenetic process which relate neither to
+the specificity nor to the localisation of its constituents,
+though they are necessary for the accomplishment of the process
+in the most thorough manner. Would it be possible to
+connect our new concept of an adaptation with our well-established
+concept of a means of morphogenesis in such a
+way that we might speak of a morphological “adaptation”
+whenever any specific feature about morphogenesis proves
+to be immediately dependent for its success on some specific
+means, though it does not owe its localisation to that means
+as its “cause”? It seems to me that such a view would
+also fall wide of the mark. It is well known, for instance,
+that the flowers of many plants never fully develop in the<span class="pagenum" title="170"><a name="Page_170" id="Page_170"></a></span>
+dark; light is necessary for their morphogenesis. Is, therefore,
+their growth in the presence of light to be called a
+morphological “adaptation” to light? Certainly not: they
+simply <em>cannot</em> originate without light, because they require
+it for some reason. It is precisely here that our conception
+of light as a “means” of morphogenesis is most fully justified.
+There are <span class="nowrap">many<a name="FNanchor_77_77" id="FNanchor_77_77"></a><a href="#Footnote_77_77" class="fnanchor">77</a></span> such cases; and there are still
+others of an apparently different type, but proving the
+same. All pathological forms produced in plants by animal
+parasites or by parasitic fungi could hardly be called adaptations,
+but must be attributed to some abnormality of means
+or of stimuli. It may be that the organism reacts as well
+as possible in these cases, and that if it reacted otherwise
+it would die&mdash;we know absolutely nothing about this question.
+But even then there would only be some sort of
+regulation <em>in</em> the process of pathological morphogenesis, but
+<em>the process</em> itself could hardly be called adaptive.</p>
+
+<p>So far we have only learned what is not to be regarded as
+morphological adaptation. No response to external formative
+stimuli is in itself an example of adaptation, nor are
+processes dependent for their existence on any kind of
+condition or means to be called, simply because they are
+dependent on them, adaptations to those agents. What then,
+after all, is a morphological adaptation?</p>
+
+<p>Let us remember what the word adaptation is really to
+mean in our discussions: a state of functioning is adapted&mdash;<span class="pagenum" title="171"><a name="Page_171" id="Page_171"></a></span>a
+state of functioning must therefore have been disturbed;
+but as functioning itself, at least in plants, certainly stands
+in close relations to the medium, it follows that all adaptations
+are in the last resort connected with those factors of
+the medium which affect functioning. In being correctives
+to the disturbances of functioning they become correctives
+to the disturbing factors themselves.</p>
+
+<p>But again, the question seems to arise whether these
+factors of the medium, when they provoke an adaptation
+by some change that is followed by functional disturbance,
+do so in the capacity of “causes” or of “means,” and so
+it might seem that we have not gained very much so far
+by our analysis. The reproach, however, would not be quite
+justified, it seems to me: we indeed have gained a new
+sort of analytical concept, in the realm of causal concepts
+in general, by clearly stating the point that adaptations are
+related directly to functionality, and only indirectly, through
+functionality, to external changes. By the aid of this logical
+formulation we now are entitled to apply the term “cause,”
+in our restricted sense of the word, to every change of the
+medium which is followed by any sort of adaptation in
+regard <em>to itself</em>. Our definition stated that a “cause” is
+any one of the sum of necessary factors from without that
+accounts either for the localisation <em>or</em> for <em>the specification</em>
+of the effect, and the definition holds very well in this
+case. Indeed, the specification of the effect is determined
+<em>by</em> the outside factor in every case of an adaptation <em>to</em> it,
+by the mere <em>fact</em> of its being a specific adaptation to this
+specific factor.</p>
+
+<p>We must not forget that in this chapter we are not
+studying real individual morphogenesis as the realisation<span class="pagenum" title="172"><a name="Page_172" id="Page_172"></a></span>
+of what has been inherited, but that at present we regard
+morphogenesis proper as an accomplished fact. Morphogenesis
+proper has laid the general lines of organisation;
+and now adaptation during the functional life, so to speak,
+imposes a second kind of organisation upon the first. It
+is for that reason that the meaning of the word “cause”
+is now becoming a little different from what it was
+before.</p>
+
+<p>In order to study a little more in detail what has been
+discovered about morphological adaptation in animals and
+plants, let us separate our materials into two groups, one
+of them embracing adaptations with regard to functional
+changes from without, the other adaptations to those
+functional changes which come from the very nature of
+functioning. Almost all of our previous general considerations
+have applied to the former group, with which
+we shall now proceed to deal.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ADAPTATIONS TO FUNCTIONAL CHANGES FROM WITHOUT</span><a name="FNanchor_78_78" id="FNanchor_78_78"></a><a href="#Footnote_78_78" class="fnanchor">78</a></p>
+
+<p>The differences between plants grown in very dry air,
+very moist air, and water, respectively, are most distinctly
+seen in all the tissues that assist in what is called
+transpiration, that is, the exchange of water-vapour between
+the plant and the medium, but especially in the epidermis
+and the conductive fibres, both of which are much stronger
+in plants grown in the dry. Indeed, it seems from experiments
+that transpiration is the most essential factor
+to which “adaptation” occurs in amphibious plants, though<span class="pagenum" title="173"><a name="Page_173" id="Page_173"></a></span>
+the changes of the mechanical conditions according to the
+medium also seem to have some sort of structural effect.
+If plants stand very deeply in water, the conditions of
+illumination, so important for assimilation in plants, may
+have been altered, and therefore much of the structural
+change can be attributed also to them. It is unimportant
+in our general question what is due to one of these factors
+and what to the other. That there is a real sort of
+adaptation cannot be doubtful; and the same is true, as
+experimental observations of the last few years have shown,
+with regard to the structural differences between so-called
+sun-leaves and shade-leaves of plants grown in the air:
+it has been actually shown here that the functional life
+of the former goes on better in the sun, of the latter better
+in the shade.</p>
+
+<p>It is very important to emphasise this point, as the
+adaptive character of all sorts of structural differences in
+plants dependent on light and on moisture has lately been
+denied, on the supposition that there is only a stopping of
+organogenesis in the case of the more simple, a continuance
+in the case of the more complicated modification, but
+nothing else. Indeed, all morphological adaptation has
+been conceived as only consisting in differences dependent
+upon the absence or the presence of necessary means or
+causes of development, and as offering no problem of its
+own. We have gained the right position from which to
+oppose this argument, it seems to me, in our formula that
+all adaptations do relate <em>not</em> directly <em>to</em> the agents of the
+medium, but to changes of functional states induced <em>by</em>
+those agents; that adaptations only <em>are</em> “adaptations” by
+being correctives to the functional state.</p>
+
+<p><span class="pagenum" title="174"><a name="Page_174" id="Page_174"></a></span></p>
+
+<p>There simply <em>is</em> an “adaptation” of structure in <em>such</em>
+a sense in all the cases we have mentioned. We can say
+neither more nor less. Granted that one of the outside
+factors which comes into account is merely a necessary
+“means”: then why is the histological consequence of the
+presence of the means an actual adaptation to it as far
+as its relation to functioning is concerned&mdash;why is the
+consequence of its absence also an adaptation to this absence
+in its relation to functioning? Why, to complete the series,
+is the degree of the consequence of its presence an adaptation
+to the degree of its presence?</p>
+
+<p>All these relationships, which are so many facts, have
+been absolutely overlooked by those who have been pleased
+to deny morphological adaptation to functional changes
+from without.</p>
+
+<p>To do full justice to them we may speak of “primary”
+regulative adaptations in all the cases mentioned above,
+applying the word “primary,” just as was done with regard
+to restitutions, to the fact that there is some sort of
+regulation <em>in</em> the normal connection of processes. We
+reserve the title of “secondary adaptations” for cases such
+as those described, for instance, by <span class="nowrap">Vöchting,<a name="FNanchor_79_79" id="FNanchor_79_79"></a><a href="#Footnote_79_79" class="fnanchor">79</a></span> where not
+merely one and the same tissue originates adaptively with
+regard to the degree of its normal functioning, but where<span class="pagenum" title="175"><a name="Page_175" id="Page_175"></a></span>
+a profound disturbance of all functioning connections, due
+to the removal of portions of the organisation, is followed
+by histological changes at absolutely abnormal localities;
+that is, where a real change of the <em>kind</em> of functioning is
+the consequence of the adaptation. It, of course, will be
+found very difficult to discriminate such phenomena from
+real restitutions, though logically there exists a very sharp
+line between them.</p>
+
+<p>A few more concrete instances may now close this
+account of adaptation to functional changes coming from
+without. Though almost all the adaptive characters in
+the aquatic forms of amphibious plants represent a less
+complicated state of organisation than the corresponding
+structures in their terrestrial forms, and therefore have
+wrongly been regarded as simply due to a stopping of
+morphogenesis for want of necessary means, yet there are
+a few of them that are positive complications in comparison
+with the land-forms: the so-called aërenchyme, especially
+well developed in the water-form of <i class="biological-name">Jussiaea</i> is such an
+instance. This tissue stands in the direct service of
+respiration, which is more difficult to be accomplished under
+water than ordinarily, and represents a true adaptation to
+the altered function.</p>
+
+<p>Among animals there is only one well-studied instance
+of our first type of adaptive morphological characters.
+<i class="biological-name">Salamandra atra</i>, the black salamander, a species which only
+inhabits regions at least two thousand feet above sea-level,
+does not bring forth its young until metamorphosis has
+taken place. The larvae, however, may be removed from
+the mother’s body at an earlier stage and forced to complete
+their development in water. Under these circumstances,<span class="pagenum" title="176"><a name="Page_176" id="Page_176"></a></span>
+as was shown in an excellent memoir by <span class="nowrap">Kammerer,<a name="FNanchor_80_80" id="FNanchor_80_80"></a><a href="#Footnote_80_80" class="fnanchor">80</a></span> they
+will change the whole histological type of their gills and
+skin in order to meet the new functional conditions.
+The change of the conditions of functioning is very severe
+here, for whereas the gills had served for nutrition and
+respiration in the uterus&mdash;by a process of endosmosis&mdash;they
+now serve for respiration only, and, of course, are
+surrounded by quite an abnormal chemical medium.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">TRUE FUNCTIONAL ADAPTATION</span><a name="FNanchor_81_81" id="FNanchor_81_81"></a><a href="#Footnote_81_81" class="fnanchor">81</a></p>
+
+<p>But all other cases of morphological adaptation among
+animals, and several in the vegetable kingdom too, belong
+to our second group of these phenomena, which in our
+analytical discussion we have called adaptations to functional
+changes that result from the very nature of functioning,
+and which we shall now call by their ordinary name,
+“functional adaptation.”</p>
+
+<p>It was Roux who first saw the importance of this kind
+of organic regulation and thought it well to give it a distinguishing
+name. <em>By functioning the organisation of organic
+tissues becomes better adapted for functioning.</em> These words
+describe better than any others what happens. It is well
+known that the muscles get stronger and stronger the more
+they are used, and that the same holds for glands, for
+connective tissue, etc. But in these cases only quantitative
+changes come into account. We meet with functional
+adaptations of a much more complicated and important<span class="pagenum" title="177"><a name="Page_177" id="Page_177"></a></span>
+kind, when for instance, as shown by <span class="nowrap">Babák,<a name="FNanchor_82_82" id="FNanchor_82_82"></a><a href="#Footnote_82_82" class="fnanchor">82</a></span> the intestine
+of tadpoles changes enormously in length and thickness
+according as they receive animal or vegetable food, being
+nearly twice as long in the second case. Besides this the
+so-called mechanical adaptations are of the greatest interest.</p>
+
+<p>It has long been known, especially from the discoveries
+of Schwendener, Julius Wolff, and Roux, that all tissues
+whose function it is to resist mechanical pressure or
+mechanical tension possess a minute histological structure
+specially suitable to their requirements. This is most
+markedly exhibited in the stem of plants, in the tail of the
+dolphin, in the arrangements of the lime lamellae in all
+bones of vertebrates. All these structures, indeed, are such
+as an engineer would have made them who knew the sort
+of mechanical conditions they would be called upon to
+encounter. Of course all these sorts of mechanically
+adapted structures are far from being “mechanically explained,”
+as the verbal expression might perhaps be taken
+to indicate, and as indeed has sometimes been the opinion
+of uncritical authors. The structures exist <em>for</em> mechanics,
+not <em>by</em> it. And, on the other hand, all these structures,
+which we have called mechanically “adapted” ones, are far
+from being mechanical “adaptations,” in our meaning of the
+word, simply because they are “adapted.” Many of them
+indeed exist previous to any functioning, they are for the
+most part truly inherited, if for once we may make use of
+that ambiguous word.</p>
+
+<p>But, the merely descriptive facts of mechanical adapted<span class="pagenum" title="178"><a name="Page_178" id="Page_178"></a></span>ness
+having been ascertained, there have now been discovered
+real mechanical processes of adaptations also. They occur
+among the statical tissues of plants, though not in that very
+high degree which sometimes has been assumed to exist;
+they also occur in a very high perfection in the connective
+tissue, in the muscles and in the bone tissue of vertebrates.
+Here indeed it has proved possible to change the specific
+structure of the tissue by changing the mechanical conditions
+which were to be withstood, and it is in cases of healing
+of broken bones that these phenomena have acquired
+a very great importance, both theoretically and practically:
+the new joints also, which may arise by force of circumstances,
+correspond mechanically to their newly created mechanical
+function.</p>
+
+<p>So far a short review of the facts of “functionelle
+Anpassung.” They seem to prove that there does exist a
+morphological adaptation to functional changes which result
+from the very nature of functioning. In fact, the actual
+state of all functioning tissue, the intensity of its state of
+existence, if you care to say so, may be said to be due
+to the functioning itself: the so-called atrophy by inactivity
+being only one extreme of a very long line of
+<span class="nowrap">correspondences.<a name="FNanchor_83_83" id="FNanchor_83_83"></a><a href="#Footnote_83_83" class="fnanchor">83</a></span></p>
+
+<p>We now, of course, have to ask ourselves if any more
+intimate analysis of these facts is possible, and indeed we
+easily discover that here also, as in the first of our groups of
+morphological adaptations, there are always single definite
+agents of the medium, which might be called “causes” or
+“means” of the adaptive effects, the word “medium” being<span class="pagenum" title="179"><a name="Page_179" id="Page_179"></a></span>
+taken as embracing everything that is external to the
+reacting cells. But of course also here the demonstration
+of single formative agents does not detract in the least from
+the adaptive character of the reaction itself. So we may
+say, perhaps, that localised pressure is the formative stimulus
+for the secretion of skeleton substance at a particular point
+of the bone tissue, or of the fibres of the connective tissue;
+the merely quantitative adaptations of muscles might even
+allow of a still more simple <span class="nowrap">explanation.<a name="FNanchor_84_84" id="FNanchor_84_84"></a><a href="#Footnote_84_84" class="fnanchor">84</a></span> But adaptations
+remain adaptations in spite of that; even if they only
+deserve the name of “primary” regulations.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THEORETICAL CONCLUSIONS</span></p>
+
+<p>We have stated in the analytical introduction to this
+chapter and elsewhere, that functional changes, which lead
+to morphological adaptations of both of our groups, may
+arise not only from changes of factors in the medium, but
+also from a removal of parts. As such removal is generally
+followed by restitution also, it is clear that restitutions and
+adaptations very often may go hand in hand, as is most
+strikingly shown in a fine series of experiments carried out
+by Vöchting, which we have already alluded to. Here again
+I should like to lay the greatest stress upon the fact that,
+in spite of such actual connections, restitutions and adaptations
+always have been separated from another theoretically,
+and that the forms are never to be resolved into sums of
+the latter. Such a view has been advocated by some recent<span class="pagenum" title="180"><a name="Page_180" id="Page_180"></a></span>
+authors, especially by Klebs, Holmes, and <span class="nowrap">Child:<a name="FNanchor_85_85" id="FNanchor_85_85"></a><a href="#Footnote_85_85" class="fnanchor">85</a></span> it is
+refuted I think by the simple fact that the first phase of
+every process of restitution, be it regeneration proper or
+be it a sort of harmonious differentiation, goes on without
+functioning at all, and only <em>for</em> future <span class="nowrap">functioning.<a name="FNanchor_86_86" id="FNanchor_86_86"></a><a href="#Footnote_86_86" class="fnanchor">86</a></span></p>
+
+<p>And there has been advocated still another view in
+order to amplify the sphere of adaptation: all individual
+morphogenesis, not only restitution, is adaptation, it has
+been said. In its strictest form such an opinion of course
+would simply be nonsense: even specific adaptive structures,
+such as those of bones, we have seen to originate in ontogeny
+previous to all specific functions, though for the help of
+them, to say nothing of the processes of the mere outlining
+of organisation during cleavage and gastrulation. But they
+are “inherited” adaptations, it has been answered to such
+objections. To this remark we shall reply in another chapter.
+It is enough to state at present that there <em>is</em> a certain kind
+of, so to speak, architectonic morphogenesis, both typical and
+restitutive, previous to specific functioning altogether.</p>
+
+<p>If now we try to resume the most general results from
+the whole field of morphological adaptations, with the
+special purpose of obtaining new material for our further<span class="pagenum" title="181"><a name="Page_181" id="Page_181"></a></span>
+philosophical analysis, we have reluctantly to confess that,
+at present at least, it does not seem possible to gather any
+new real proof of life-autonomy, of “vitalism,” from these
+facts, though of course also no proof against it.</p>
+
+<p>We have stated that there is in every case of both our
+types of adaptive events a correspondence between the
+degree of the factor to which adaptation occurs, and the
+degree of the adaptive effect. We here may speak of an
+<em>answering</em> between cause and effect with regard to adaptation,
+and so perhaps it may seem as if the concept of an
+“answering reaction” (“Antwortsreaktion”), which was
+introduced into science by <span class="nowrap">Goltz<a name="FNanchor_87_87" id="FNanchor_87_87"></a><a href="#Footnote_87_87" class="fnanchor">87</a></span> and which is to play
+a great part in our discussions of next summer, may come
+into account: but in our present cases “answering” only
+exists between a simple cause and a simple effect and relates
+almost only to quantity and locality. There is therefore
+lacking the most important feature, which, as will be seen,
+would have made the new concept of value.</p>
+
+<p>We only, I believe, can state the fact that there <em>are</em>
+relations between morphogenetic causes and effects which
+<em>are</em> adaptations, that functional disturbances or changes are
+followed by single histogenetic reactions from the organism,
+which are compensations of its disturbed or changed
+functional state. We are speaking of facts here, of very
+strange ones indeed. But I feel unable to formulate a real
+proof against all sorts of mechanism out of these facts:
+there <em>might</em> be a machine, to which all is due in a pre-established
+way. Of course we should hardly regard such
+a machine as very probable, after we have seen that it<span class="pagenum" title="182"><a name="Page_182" id="Page_182"></a></span>
+<em>cannot</em> exist in other fields of morphogenesis. But we are
+searching for a new and independent proof; and that is
+indeed not to be found <span class="nowrap">here.<a name="FNanchor_88_88" id="FNanchor_88_88"></a><a href="#Footnote_88_88" class="fnanchor">88</a></span></p>
+
+<p>At present it must be taken as one of the fundamental
+<em>facts</em> of the organogenetic harmony, that the cells
+of functioning tissues do possess the faculty of reacting to
+factors which have changed the state of functioning, in a
+way which normalises this state histologically. And it is
+a fact also that even cells, which are not yet functioning
+but are in the so-called embryonic or indifferent condition
+contributing to the physiological completion of the tissue,
+react to factors embracing new functional conditions of the
+whole in a manner which leads to an adaptation of that
+whole to those conditions.</p>
+
+<p>This is a very important point in almost all morphological
+adaptation, whether corresponding to functional changes
+from without or resulting from the very nature of functioning.
+In fact, such cells as have already finished their
+histogenesis are, as a rule, only capable of changing their
+size adaptively, but are not able to divide into daughter-cells
+or to change their histological qualities fundamentally;
+in technical terms, they can only assist “hypertrophy” but
+not “hyperplasia.” Any adaptive change of a tissue therefore,
+that implies an increase in the number of cellular
+elements or a real process of histogenesis, has to start from
+“indifferent” cells, that is to say, cells that are <em>not yet</em>
+functioning in the form that is typical of the tissue in
+question; and, strange to say, these “embryonic” cells&mdash;<span class="pagenum" title="183"><a name="Page_183" id="Page_183"></a></span><i>i.e.</i>
+the “cambium” in higher plants and many kinds of
+cells in animals&mdash;<em>can</em> do what the functional state requires.
+It is to be hoped that future investigations will lay a
+greater stress upon this very important feature of all
+adaptation.</p>
+
+<p><span class="pagenum" title="184"><a name="Page_184" id="Page_184"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Physiological Adaptation</span><a name="FNanchor_89_89" id="FNanchor_89_89"></a><a href="#Footnote_89_89" class="fnanchor">89</a></h4>
+
+<p>It is but a step from morphological adaptations to
+adaptations in physiology proper. The only difference
+between regulations of the first type and those which occur
+in mere functioning is, that the resulting products of the
+regulation are of definite shape and therefore distinctly
+visible in the first case, while they are not distinctly visible
+as formed materials but are merely marked by changes in
+chemical or physical composition in the latter.</p>
+
+<p>Metabolism, it must never be forgotten, is the general
+scheme within which all the processes of life in a given
+living organism go on; but metabolism means nothing
+else, at least if we use the word in its descriptive and
+unpretentious meaning, than change in the physical or
+chemical characteristics of the single constituents of that
+organism. In saying this, we affirm nothing about the
+physical or chemical nature of the actual processes leading to
+those physical or chemical characteristics, and by no means<span class="pagenum" title="185"><a name="Page_185" id="Page_185"></a></span>
+are these “processes” <i lang="la" xml:lang="la">a priori</i> regarded as being physical
+or chemical <em>themselves</em>: indeed, we have learned that in one
+large field, in the differentiation of our harmonious systems
+they certainly are not. Now, if the metabolism does not
+end in any change of visible form, then true physiological
+processes, or more particularly physiological regulations, are
+going on before us. But we are dealing with morphogenetic
+events or regulations, if the result of metabolism is marked
+by any change in the constituents of form. This however
+may depend on rather secondary differences as to the nature
+of regulation itself, and any kind of metabolism may really
+be of the regulatory type, whether we actually see its result
+as a constituent of form, <i>e.g.</i> owing to the production of
+some insoluble compound, or whether we do not.</p>
+
+<p>I do not mean to say that these are the only differences
+between mere physiological activities or regulations and
+organogenesis proper, as an originating of typical form-combination;
+but if we regard, as we do in this chapter,
+the given organisation of a living being as a substratum
+of its functional life, morphological and physiological
+adaptations are indeed of almost the same logical order.</p>
+
+<p>We had best therefore begin our discussions with a
+recapitulation of our problem. We are studying adaptations
+in functioning&mdash;that means we want to know how the
+organism behaves with regard to any change which may
+take place in its functional state. We apply the term
+regulation, or in particular adaptation, to any kind of
+reaction on the part of the organism which re-establishes
+the normal state of functioning, and we now want to learn
+to what degree such adaptations exist in the field of
+physiology.</p>
+
+<p><span class="pagenum" title="186"><a name="Page_186" id="Page_186"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">SPECIFIC ADAPTEDNESS <em>NOT</em> “ADAPTATION”</span></p>
+
+<p>It is important to keep well in mind our strictly
+formulated theme, as by doing so we shall be able to
+exclude at once from our materials a large group of
+phenomena which occasionally have been called regulations
+by physiological authors, but which, in fact, are not of the
+adaptation type and therefore cannot be said to afford those
+problems which possibly might have been expected. Typical
+peculiarities in functional life cannot be called “regulations”
+for this very reason. If, for instance, the organism selects
+specific amounts of specific kinds of organic food or of salts
+out of the combinations of salts or organic food normally
+offered to it in the medium, as indeed is most typically
+shown for instance by the roots of plants, there cannot be
+said to occur a “regulation” or “adaptation” with regard
+to the permeability of the cell, nor is it strictly a case of
+“regulation,” if so-called selective qualities are discovered in
+the processes of secretion, say of the epithelium of the kidney.</p>
+
+<p>All these facts are typical and specific peculiarities in
+functioning which are duly to be expected, where a very
+typical and specific organisation of the most elaborated kind
+exists. Indeed, after studying such an organisation we
+must not be astonished that functions in organisms follow
+lines which certainly they would not have taken without it.
+Take the fact which is quoted very often, that the migration
+of compounds or of ions in the organisms can happen
+quite contrary to all the laws of osmosis, from the less
+concentrated to the more concentrated side of a so-called
+“membrane.” There <em>is</em> no simple “membrane” in the
+organism, but a complicated organisation of an almost<span class="pagenum" title="187"><a name="Page_187" id="Page_187"></a></span>
+unknown character takes its place, and nothing, indeed, is
+against the assumption that this organisation may include
+factors which actually drive ions or compounds to the side
+of higher concentration, which indeed drive them by “doing
+work,” if we like to speak in terms of energy; and these
+factors included in organisation may very well be of a true
+physical or chemical <span class="nowrap">nature.<a name="FNanchor_90_90" id="FNanchor_90_90"></a><a href="#Footnote_90_90" class="fnanchor">90</a></span></p>
+
+<p>I lay great stress upon these statements, as I should like
+to be as careful as possible in the admission of anything
+like a “proof” of vitalism. It was want of scientific
+criticism and rigid logic that discredited the old vitalism;
+we must render our work as difficult as possible to ourselves,
+we must hold the so-called “machine theory” of life
+as long as possible, we must hold it until we are really
+forced to give it up.</p>
+
+<p>In a more general form we now can sum up our
+discussion by saying: There never are adaptations in
+physiology, requiring any special analysis, where there are
+only complications or even apparent deviations from the
+purely physico-chemical type of events which are, so to
+say, statical, <i>i.e.</i> fixed in quantity or quality, however
+peculiar or typically complicated they may be; all such
+peculiarities indeed, may properly be called “adapted,” that
+is to say, very well fitted to perform a specific part in
+the service of normal general functioning, and they are
+“adapted” to their part by virtue of a certain “adaptedness”
+of the organisation; but they are not “adaptations”
+in any sense of the word.</p>
+
+<p><span class="pagenum" title="188"><a name="Page_188" id="Page_188"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">PRIMARY AND SECONDARY ADAPTATIONS IN PHYSIOLOGY</span></p>
+
+<p>We approach the subject of true adaptations, that is, of
+adapting processes, as soon as any kind of variation in
+functioning occurs which corresponds to a variation of any
+factor of the medium in the widest sense. But even here
+our work is by no means done by simply showing such a
+correspondence of outer and inner variations. We know
+very well already, from our former studies, that now we are
+faced by a further problem, that we are faced by the
+question whether we have to deal with simple primary
+kinds of adaptations or with the far more important
+secondary ones.</p>
+
+<p>As the discrimination between primary and secondary
+regulations proves indeed to be of first-rate importance, you
+will allow me, I hope, to summarise our chief analytical
+statements regarding them in a most general form. We call
+primary regulatory any kind of morphogenetic or functional
+performance, which, by its very intimate nature, always
+serves to keep the whole of organisation or of functions in
+its normal state. We call secondary regulations all features
+in the whole of morphogenesis or of functioning which serve
+to re-establish the normal state after disturbances along lines
+which are outside the realm of so-called normality. This
+analytical discrimination will help us very much to a proper
+understanding of physiology. But before we turn to apply
+our definitions to actual facts, another preliminary problem
+has to be solved.</p>
+
+<p><span class="pagenum" title="189"><a name="Page_189" id="Page_189"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN PRE-REQUISITES OF ADAPTATIONS IN GENERAL</span></p>
+
+<p>We are thinking of the general and important question,
+what types of adaptations may be expected in the field of
+physiology and whether there may be certain classes of
+regulatory events which possibly might be expected to occur
+in the organism on <i lang="la" xml:lang="la">a priori</i> grounds, but which, nevertheless,
+are to be regarded as impossible after a more
+intimate analysis of its nature, even at the very beginning?
+Or, in other words, to what kinds of changes of the medium
+will an organism be found able or unable to adapt itself?</p>
+
+<p>We know that the <em>state of functioning</em> must be altered
+in order to call forth any sort of adaptation at all. Now,
+there can be no doubt that <i lang="la" xml:lang="la">a priori</i> it would seem to be
+very useful for the organism, if it never would let enter into
+its blood, lymph, etc., be it through the skin or through the
+intestine, any chemical compound that would prove to be a
+poison afterwards. In fact, a man, judging on the principle
+of the general usefulness of all the phenomena of the living,
+might suppose that there would exist a sort of adaptation
+against all poisons to the extent that they would never be
+allowed to enter the real interior of the body. We know
+that such reasoning would be incorrect. But we also can
+understand, I suppose, that an <i lang="la" xml:lang="la">a priori</i> analysis of a more
+careful kind would have reasoned differently. How could
+the functional state of the organism be changed, and how,
+therefore, could adaptation be called forth by any factor of
+the medium which had not yet entered the organism, but
+was only about to enter it? Not at all therefore is such a
+regulation to be expected as we have sketched; if there is
+to be any adaptation to poisons, it only can occur after the<span class="pagenum" title="190"><a name="Page_190" id="Page_190"></a></span>
+poison has really acted in some way, and in this case we
+shall indeed find regulations.</p>
+
+<p>You may perhaps regard this discussion as a little
+too academical and hair-splitting, but here again it was
+for the sake of ensuring a perfectly sound foundation of
+our chief principles that I undertook it. Very often, indeed,
+the question has been raised by the defenders of a mechanistic
+theory of life, Why then did the organisms not reject all
+poisons from the very beginning? We now may reply to
+that only&mdash;how <em>could</em> they do so? How could they “know”
+what is a poison and what is not, unless they had experienced
+it?&mdash;if we are allowed for a moment to use very anthropomorphistic
+language.</p>
+
+<p>We repeat, therefore, that the functional conditions of
+the organism must have been actually changed in order
+that an adaptation may occur. Nothing is more essential
+to a clear understanding of our problems than to keep
+fully in mind the exact sense of this definition.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ON CERTAIN GROUPS OF PRIMARY PHYSIOLOGICAL ADAPTATIONS</span></p>
+
+<p><i>General Remarks on Irritability.</i>&mdash;Turning now to more
+special groups of problems concerning physiological adaptations,
+let us begin with the primary class of them, and let
+us first say a few words on a subject which occasionally
+has been regarded as the basis of physiological regulation
+in general. I refer to a most important fact in the general
+physiology of irritability. Irritability of any kind is known
+to be re-established, after it has been disturbed by the
+process of reacting to the stimulus, and in certain cases,
+in which two different&mdash;or rather two opposite&mdash;kinds<span class="pagenum" title="191"><a name="Page_191" id="Page_191"></a></span>
+of reactions are possible on the same substratum, which
+increase with regard to one process whilst decreasing at
+the same time with regard to the other. The irritability
+of the muscle or of the leaves of <i class="biological-name">Mimosa</i> is a very
+good instance of the first case, whilst the second more
+complicated one cannot be illustrated better than by what
+all experience has taught us about the irritability of the
+retina. The retina is more irritable by green rays and less
+by red ones the more it has been stimulated by the latter,
+and more sensitive to light in general the more it has been
+exposed to darkness; and something very similar is true,
+for instance, as regards phototactic irritability in plants, all
+these phenomena being in relation to the so-called law of
+<span class="nowrap">Weber.<a name="FNanchor_91_91" id="FNanchor_91_91"></a><a href="#Footnote_91_91" class="fnanchor">91</a></span></p>
+
+<p>It seems to me that there would be little difficulty in
+harmonising the phenomenon of the inversion of irritability
+with the so-called principle of the “action of masses”
+and with the laws of certain “reversible” processes well
+known in chemistry. As to the simple fact of the re-<span class="pagenum" title="192"><a name="Page_192" id="Page_192"></a></span>establishment
+of irritability after stimulation has occurred,
+or, in certain other cases, the fact that in spite of permanent
+stimulation irritability seems to exist permanently also,
+physical analogies or even explanations might very well
+be <span class="nowrap">found.<a name="FNanchor_92_92" id="FNanchor_92_92"></a><a href="#Footnote_92_92" class="fnanchor">92</a></span></p>
+
+<p>If now we ask whether there is anything like an adaptation
+appearing in the general characteristics of irritation
+and irritability, it seems to me that we may answer the
+question in an affirmative manner, as far as primary regulation
+comes into account. We, certainly, have not studied
+any abnormal regulatory lines of general functioning, we
+only have studied general functioning itself; but, indeed,
+there was a certain sort of regulation <em>in</em> functioning. Of
+course, by showing that one of the most general features of
+all functioning is primary-regulatory in itself, we do not
+deny the possibility of many specific functions in which
+real secondary regulations actually do exist. Nothing
+indeed is asserted about the <em>specific</em> character of functioning
+in its different types, by proving that one of the <em>general</em>
+features of <em>all</em> functioning may comparatively easily be<span class="pagenum" title="193"><a name="Page_193" id="Page_193"></a></span>
+understood. It seems to me that this important logical
+point has not always received the attention it deserved.</p>
+
+<p><i>The Regulation of Heat Production.</i><a name="FNanchor_93_93" id="FNanchor_93_93"></a><a href="#Footnote_93_93" class="fnanchor">93</a>&mdash;Having finished
+our introductory remarks we now turn to the proper
+study of special physiological functioning with regard to
+its adaptive side, and begin with the most simple cases.</p>
+
+<p>The so-called “regulation of heat” in warm-blooded
+vertebrates is an instance of a special function which can
+be said to be regulatory in itself. There exists a normal
+blood heat for each species, which is maintained no matter
+whether the temperature of the medium rise or fall. It
+might seem at first as if in this case there were a little
+more of an adaptive regulation than only its well-known
+primary type; no reversion, one might say, of the direction
+of one and the same process occurs in the regulation of heat
+production, but one kind of process is called into action
+if it is necessary to raise the temperature, and another
+whenever it is necessary to lower it. Even in the dilatation
+and constriction of capillary vessels there are different
+nerves serving for each operation respectively, and far more
+important are the increasing of transpiration for cooling, the
+increasing of combustion for heating&mdash;two radically different
+processes. But, nevertheless, there is a certain unity in
+these processes, in so far as a specific locality of the brain
+has been proved to be the “centre” of them all; it is to
+this centre of course that the analysis of heat production
+considered as a kind of regulation or adaptation must be
+directed. Such an ultimate analysis, it seems to me, would
+have to classify heat regulation under the primary type of<span class="pagenum" title="194"><a name="Page_194" id="Page_194"></a></span>
+adaptations in physiology without any restriction. The
+centre acts in one sense or in the other, if stimulated by any
+temperature beyond a very limited range, and it is in the
+action of the centre that the “regulation” of heat <span class="nowrap">consists.<a name="FNanchor_94_94" id="FNanchor_94_94"></a><a href="#Footnote_94_94" class="fnanchor">94</a></span></p>
+
+<p><i>Primary Regulations in the Transport of Materials and
+Certain Phenomena of Osmotic Pressure.</i>&mdash;Very similar
+phenomena of regulation are present in many processes
+concerned in the whole of metabolism. Let us consider
+for a moment the migration of materials in plants. Whenever
+any compound is used at a certain place, a permanent
+afflux of this compound to that place sets in from
+all possible directions. No doubt this is a “regulation,”
+but it is also the function itself, and besides that, a very
+simple function based almost entirely on well-known laws
+of physical chemistry. And in other cases, as in the ascent
+of water to the highest tops of our trees, which purely
+physical forces are said to be insufficient to explain, we can
+appeal to the unknown organisation of many cells, and there
+is nothing to prevent our attributing to these cells certain
+functions which are, if you like to say so, regulatory in
+themselves. Among other facts of so-called regulations
+there is the stopping of metabolic processes by an accumulation
+of their products: as, for instance, the transformation of
+starch into sugar is stopped, if the sugar is not carried
+away. Of course that is a regulation, but it again is an
+intrinsic one, and it is one of the characteristics of reversible
+chemical processes to be stopped in that way. I know very
+well that in this particular case a certain complication is<span class="pagenum" title="195"><a name="Page_195" id="Page_195"></a></span>
+added by the fact that it is a so-called ferment, the diastase,
+which promotes the transformation of starch into cane-sugar,
+and that this ferment is actively produced by the organism:
+but even its production would not prove that any real kind
+of secondary regulation exists here, if nothing more were
+known about such an active production than this single
+case.</p>
+
+<p>In a special series of experiments almost all carried out
+in Wilhelm Pfeffer’s botanical laboratory at Leipzig, an
+attempt has been made to discover in what manner the cells
+of plants are able to withstand very high abnormalities of
+the osmotic pressure of the medium&mdash;that is to say, very
+great changes in the amount of its salinity. That many,
+particularly the lower plants, are able to stand such changes
+had been ascertained already by the careful examinations of
+Eschenhagen; but recent years have given us a more profound
+insight into what happens. Von <span class="nowrap">Mayenburg<a name="FNanchor_95_95" id="FNanchor_95_95"></a><a href="#Footnote_95_95" class="fnanchor">95</a></span> has
+found that sundry of the species of <i class="biological-name">Aspergillus</i>, the common
+mould, are able to live in very highly concentrated solutions
+of several salts (KNO<sub>3</sub> and Na<sub>2</sub>SO<sub>4</sub>). They were found to
+regulate their osmotic pressure not by taking in the salts
+themselves, but by raising the osmotic pressure of their own
+cell sap, producing a certain amount of osmotically active
+substances, probably carbohydrates. If in this case it were
+possible to assume that the osmotic pressure of the medium
+were the real stimulus for the production of the osmotic
+substances in the cell, stimulus and production both
+corresponding in their degree, we should be entitled to
+speak of a primary though <span class="nowrap">physiological<a name="FNanchor_96_96" id="FNanchor_96_96"></a><a href="#Footnote_96_96" class="fnanchor">96</a></span> regulation only;<span class="pagenum" title="196"><a name="Page_196" id="Page_196"></a></span>
+and it seems to me that despite the discoveries of Nathansohn
+that certain algae and cells of higher plants are
+able to change the permeability of their surfaces in a
+way which regulates the distribution of single salts or
+ions in the sap of their cells without any regard to pure
+osmotic equilibrium, such a simple explanation might be
+<span class="nowrap">possible.<a name="FNanchor_97_97" id="FNanchor_97_97"></a><a href="#Footnote_97_97" class="fnanchor">97</a></span></p>
+
+<p>There are many regulation phenomena connected with
+osmotic pressure and permeability in animal physiology
+also, though at present they are not worked out as fully as
+possible. The works of Frédéricq, J. Loeb, Overton and
+<span class="nowrap">Sumner<a name="FNanchor_98_98" id="FNanchor_98_98"></a><a href="#Footnote_98_98" class="fnanchor">98</a></span> would have to be taken into account by any one<span class="pagenum" title="197"><a name="Page_197" id="Page_197"></a></span>
+who wished to enter more deeply into these problems. We
+can only mention here that permeability to water itself
+also plays its part, and that, according to Overton’s experiments,
+it is a kind of solubility of the media in the very
+substance of the cell surface on which all permeability and
+its regulation depend.</p>
+
+<p><i>Chromatic Regulations in Algae.</i>&mdash;The phenomena of
+osmotic pressure and its regulation may be said to be the
+preliminaries of metabolism proper, conditions necessary for
+it to take place. Now there is another branch of such
+preliminaries to metabolism, in which the most interesting
+regulation phenomena have been lately discovered. It is
+well known that what is called assimilation in plants, that
+is, the formation of organic compounds out of carbon dioxide
+(CO<sub>2</sub>) and water, occurs only in the light by means of
+certain pigments. This pigment is in all higher plants and
+in many others the green chlorophyll, but it may be different
+in certain species of algae, and can generally be <span class="nowrap">said<a name="FNanchor_99_99" id="FNanchor_99_99"></a><a href="#Footnote_99_99" class="fnanchor">99</a></span> to be
+of the colour complementary to the colour of those rays
+which especially are to be absorbed and to be used for
+assimilation. But here we have “adaptedness,” not
+adaptation. It was in some species of primitive algae, the
+<i class="biological-name">Oscillariae</i>, that <span class="nowrap">Gaidukow<a name="FNanchor_100_100" id="FNanchor_100_100"></a><a href="#Footnote_100_100" class="fnanchor">100</a></span> found a very interesting instance
+of an active regulation in the formation of pigments. These
+algae always assume a colour which corresponds to the
+accidental colour of the rays of the medium and is complementary
+to it; they become green in red light, yellow in
+blue light, and so on&mdash;that is, they always actively take that
+sort of colouring which is the most suitable to the actual<span class="pagenum" title="198"><a name="Page_198" id="Page_198"></a></span>
+<span class="nowrap">case.<a name="FNanchor_101_101" id="FNanchor_101_101"></a><a href="#Footnote_101_101" class="fnanchor">101</a></span> There indeed occurs a sort of complementary photography
+in these algae; but, though adaptive, it could hardly
+be said to exceed the limits of “primary phenomena.”</p>
+
+<p><i>Metabolic Regulations.</i>&mdash;And now we enter the field of
+regulations in metabolism itself. There are two kinds of
+outside factors of fundamental importance for all metabolic
+processes: food is one, and oxygen is the other. And
+metabolism as a whole is of two different aspects also: it
+both serves for assimilation proper&mdash;that is, building up&mdash;and
+it supplies the energy for driving the functional machine.
+It is clear that food alone&mdash;together of course with the
+assimilating means of the organism, can account for the
+first type of metabolism, while both food and oxygen, or
+some sort of substitute for the latter, as in certain
+bacteria, supply functional energy. Of course we are not
+entitled to say that the importance of so-called oxidation
+or respiration is exhausted by its energetic rôle: it certainly
+is not, for if it were, the organism would only be stopped
+in its functions if deprived of oxygen but would not die.
+It seems that certain substances always arise in the
+metabolism, in the processes of decomposition, which have
+to be burnt up in order not to become poisonous. But
+we shall return to the phenomena of organic oxidation in
+another chapter of the book, and shall deal with them from
+a more general point of <span class="nowrap">view.<a name="FNanchor_102_102" id="FNanchor_102_102"></a><a href="#Footnote_102_102" class="fnanchor">102</a></span></p>
+<p><span class="pagenum" title="199"><a name="Page_199" id="Page_199"></a></span></p>
+<p>Let us now try to take a short survey of all the regulations
+discovered relating to the substitution of one kind of
+food for another. We have said that food serves in the
+first place as building material, in the second place as
+fuel. It only deserves brief mention that, as all recent
+investigations have shown, fats, carbohydrates, and albumen
+are equally well able to serve as <span class="nowrap">fuel.<a name="FNanchor_103_103" id="FNanchor_103_103"></a><a href="#Footnote_103_103" class="fnanchor">103</a></span></p>
+
+<p>It is in the state of fasting, <i>i.e.</i> in the case of a real
+absence of <em>all</em> nourishing materials, that the organism has
+proved to be capable of regulations of the most marked
+nature, with regard to the combustion of its own materials.
+Respiration, we know, must go on if death is to be avoided,
+and now indeed it has been found that this process attacks
+the different tissues of the organism subjected to fasting in
+such an order that, after the combustion of the reserves,
+the most unimportant tissues with regard to life in general<span class="pagenum" title="200"><a name="Page_200" id="Page_200"></a></span>
+are destroyed first, the most important ones last. Thus in
+vertebrates the nerve cells and the heart are preserved as
+long as possible; in infusoria it is the nucleus; in flatworms,
+as the very careful studies of E. <span class="nowrap">Schultz<a name="FNanchor_104_104" id="FNanchor_104_104"></a><a href="#Footnote_104_104" class="fnanchor">104</a></span> have lately shown,
+it is the nerve cells and the sexual cells which longest
+resist destruction, whilst almost all the rest of the organisation
+of these animals may disappear. I should not say
+that we can do very much with these facts at present in
+our theoretical discussion, but they are certainly witness of
+very astonishing adaptive <span class="nowrap">powers.<a name="FNanchor_105_105" id="FNanchor_105_105"></a><a href="#Footnote_105_105" class="fnanchor">105</a></span></p>
+
+<p>We now turn to study the cases of a compensation of
+nourishments serving for the real building up of the organism.
+Albumen, we know, is absolutely indispensable for animals,
+even for adults, though nothing is known about the purpose
+it serves in the latter; its place can be taken of course by
+those less complicated compounds which result from its
+first decomposition, effected by pepsin and trypsin, but
+nothing else will do. The salts of sea-water, according to
+Herbst’s experiments, may only vary to a very small degree
+if the development of marine animals is to go on well;
+potassium may be replaced by caesium or rubidium, and
+that is all. Much the same is true of the salts necessary
+to plants. It will not surprise us very much to hear that
+algae can also be successfully fed with the potassium salts
+of organic compounds, and higher plants with acid amides or<span class="pagenum" title="201"><a name="Page_201" id="Page_201"></a></span>
+glucoses instead of carbonic acid, as those products are
+normal steps in their assimilation; and it may also be fairly
+easily understood that nitrogen can be offered in organic
+form instead of as a nitrate.</p>
+
+<p>It was in the group of fungi that really important
+adaptations with regard to the proper form-producing
+alimentation were first discovered, and these are of a very
+complicated kind indeed. Fungi are known to be satisfied
+with one single organic compound instead of the group of
+three&mdash;fat, carbohydrate and albumen&mdash;necessary for animals.
+Now Pfeffer showed that the most different and indeed very
+abnormal compounds were able to bring his subjects to
+a perfect growth and morphogenesis; and, moreover, he
+found that, if several kinds of such food were offered
+together, they were consumed quite indifferently as to their
+chemical constitution, but only with regard to their nutritive
+value: that sort of food which had produced a better
+growth than another when both were offered separately was
+found to save the latter from consumption whenever both
+were offered together.</p>
+
+<p>Here we are faced by one of the most typical cases of
+regulations in metabolic physiology: the organism is able
+to decompose compounds of the most different constitution,
+which have never been offered to it before; but nevertheless,
+it must remain an open question whether real
+“secondary” regulation has occurred, as nothing is known
+in detail about the single steps of metabolism in these fungi.
+There <em>might</em> be some ferments equally able to destroy different
+classes of <span class="nowrap">compounds,<a name="FNanchor_106_106" id="FNanchor_106_106"></a><a href="#Footnote_106_106" class="fnanchor">106</a></span> and that the most nutritive compound<span class="pagenum" title="202"><a name="Page_202" id="Page_202"></a></span>
+is used up first <em>may</em> be a question of physico-chemical
+equilibrium.</p>
+
+<p>That is almost <span class="nowrap">all<a name="FNanchor_107_107" id="FNanchor_107_107"></a><a href="#Footnote_107_107" class="fnanchor">107</a></span> that is actually known of adaptation
+with regard to the use of an abnormal food supply. Though
+important, it cannot be said to be very much. But could we
+expect very numerous regulations here at all after what we
+laid down in a former paragraph about the possibilities of
+adaptive regulation in general? The functional state must
+have been altered in order that such regulations may occur.
+Now there is no doubt that this state may be really altered
+only if an abnormal food has first been taken in altogether
+by the cell-protoplasm of the body-surfaces, but never if it
+has only entered the cavity of the intestine, which, strictly
+speaking, is a part of the exterior medium. Fungi indeed
+not only take in the abnormal food, but also know what to
+do with it, but all animals are obliged to treat first with
+their chemical secretions what happens to be present in
+their intestine, in order that it may be taken up by their
+living cells, and one hardly can wonder that these secretions
+are only formed in correspondence to a limited number of
+outside stimuli. In fact, as soon as we look upon what
+adaptive or regulatory work happens in metabolism <em>inside</em>
+the body interior, we meet, even in animals, regulations of a
+far more developed type.</p>
+
+<p>Discoveries of the last few years have taught us that
+almost all metabolic processes in the organism, including
+oxidation, are carried out by the aid of special materials, the<span class="pagenum" title="203"><a name="Page_203" id="Page_203"></a></span>
+so-called enzymes or ferments. These are known to exist in
+the most different forms even in the inorganic world. They
+are simply chemical compounds, of specific types, that
+bring about chemical reactions between two other chemical
+materials, which in their absence would either not go on
+at all or would go on very slowly. We cannot enter here
+into the much disputed chemical theory of what is called
+“catalysis”: we can only say that there is no objection to
+our regarding almost all metabolic processes inside the
+organism as due to the intervention of ferments or catalytic
+materials, and that the only difference between
+inorganic and organic ferments is the very complicated
+character of the latter and the very high degree of their
+specification.</p>
+
+<p>Such a statement, of course, does not say that all
+metabolism has proved to be of a chemical nature: the
+<em>action</em> of the ferment when produced is chemical, but we
+do not know at all <em>how</em> the ferment is produced; we only
+know that a high degree of active regulation is shown in
+this production. In fact, it has been proved in some cases,
+and probably will be proved in a great many more in the
+near future, that all metabolic ferments, whether they
+promote oxidation or assimilation proper or chemical decomposition,
+are produced in a regulatory manner with regard
+to the specific compound to be dissociated or to be built
+up. In this way the whole field of metabolism is really
+covered by “regulations.” Are they real “secondary”
+ones? Of course the regulatory correspondence applies to
+the process of <em>secretion</em> in the <em>first</em> place, not to the actual
+formation of the ferment inside the cell. The correspondence
+as to secretion, no doubt, is of the primary type; is there<span class="pagenum" title="204"><a name="Page_204" id="Page_204"></a></span>
+any secondary regulation with regard to the real <em>production</em>
+of the ferment? I am sorry that I cannot answer this
+question affirmatively. Nothing is <em>known</em> at present, even
+here, that really proves the existence of adaptation of the
+secondary type: there <em>might</em> be a sort of statical “harmony”
+at the base of it all, established before all functioning <em>for</em>
+<span class="nowrap">functioning.<a name="FNanchor_108_108" id="FNanchor_108_108"></a><a href="#Footnote_108_108" class="fnanchor">108</a></span></p>
+
+<p>The only facts of secondary metabolic regulations which
+are known at present have been found in combination with
+phenomena of restitution after real disturbances of organisation,
+where, indeed, numbers and numbers of regulatory
+changes of metabolism, both in animals and plants, have
+also been recorded. But there is not one case of a secondary
+regulation really known to affect pure metabolism <span class="nowrap">alone.<a name="FNanchor_109_109" id="FNanchor_109_109"></a><a href="#Footnote_109_109" class="fnanchor">109</a></span>
+This is a new indicium of the primacy of <em>form</em> in the
+organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">IMMUNITY THE ONLY TYPE OF A SECONDARY PHYSIOLOGICAL
+ADAPTATION</span></p>
+
+<p>There is only one class of physiological processes in
+which the type of the real secondary regulation occurs.<span class="pagenum" title="205"><a name="Page_205" id="Page_205"></a></span>
+The discoveries of the last twenty years have proved
+beyond all doubt, and future discoveries will probably prove
+even more conclusively, that the so-called <em>immunity</em> against
+diseases is but one case out of numerous biological phenomena
+in which there is an adaptive correspondence between
+abnormal chemical stimuli and active chemical reactions on
+the part of the organism and in its interior, exceeding by
+far everything that was formerly supposed to be possible
+in organic regulation.</p>
+
+<p>The adaptive faculty of the organism against inorganic
+poisonous <span class="nowrap">substances<a name="FNanchor_110_110" id="FNanchor_110_110"></a><a href="#Footnote_110_110" class="fnanchor">110</a></span> is but small comparatively, and is
+almost always due not to a real process of active regulation
+but to the action of substances pre-existing in the organism&mdash;that
+is, to a sort of adaptiveness but not adaptation.
+Metallic poisons, for instance, may be transformed into
+harmless compounds by being combined with albumen or
+sulphuric acid and thus becoming insoluble, or free acids
+may be neutralised, and so on; but all these processes
+go on to a certain extent only, and, as was mentioned
+already, are almost always the result of reactions with
+pre-existing materials. Only in a few cases is there any
+sort of true adaptation to metallic substances, such as
+sublimate and, in a very small degree, arsenic, comparable
+in some respects with the adaptation to abnormally high
+temperatures. The organism which has been accustomed
+to receive at first very small amounts, say, of sublimate, and
+then receives greater and greater amounts of this substance
+by degrees, will at the end of this treatment be able to
+stand a quantity of the poison that would have been<span class="pagenum" title="206"><a name="Page_206" id="Page_206"></a></span>
+instantly fatal if administered at the first <span class="nowrap">dose.<a name="FNanchor_111_111" id="FNanchor_111_111"></a><a href="#Footnote_111_111" class="fnanchor">111</a></span> But the
+explanation of this adaptation is not known in any case;
+there seems to be some similarity between it and the so-called
+histogenetic immunity against organic poisons.</p>
+
+<p>It is in the fight against animal and vegetable poisons,
+such as those produced by bacteria, by some plants and
+by poisonous snakes, that the true adaptation of the
+organism reaches its most astonishing degree. The production
+of so-called “anti-bodies” in the body fluids is
+not the only means applied against noxious chemical
+substances of this kind: the existence of so-called histogenetic
+immunity is beyond all doubt, and <span class="nowrap">Metschnikoff<a name="FNanchor_112_112" id="FNanchor_112_112"></a><a href="#Footnote_112_112" class="fnanchor">112</a></span>
+certainly was also right in stating that the cells of the
+organism themselves repel the attack of living bacteria.
+Cells of the connective tissue and the white blood cells,
+being attracted by them as well as by many other foreign
+bodies, take them in and kill them. This process, called
+“phagocytosis” is of special frequency among lower animals,
+but it also contributes to what is called inflammation in
+higher <span class="nowrap">ones.<a name="FNanchor_113_113" id="FNanchor_113_113"></a><a href="#Footnote_113_113" class="fnanchor">113</a></span> And there are still other kinds of defence
+against parasites, as for instance the horny or calcareous
+membranes, employed to isolate trichinae and some kinds
+of bacteria. But all this is of almost secondary importance
+as compared with the adaptive faculties of the warm-blooded
+vertebrates, which produce anti-poisonous substances
+in their lymph and blood.</p>
+
+<p><span class="pagenum" title="207"><a name="Page_207" id="Page_207"></a></span></p>
+
+<p>It is impossible to say <span class="nowrap">here<a name="FNanchor_114_114" id="FNanchor_114_114"></a><a href="#Footnote_114_114" class="fnanchor">114</a></span> more than a few words
+about the phenomena and the theory of immunity proper,
+which have attained the dimensions of a separate science.
+Let me only mark those general points which are of
+the greatest theoretical interest. Discoveries of the most
+recent years have shown not only that against the “toxins”
+of bacteria, snakes, and some plants, the organism is able
+actively to produce so-called “anti-toxins”&mdash;that is, soluble
+substances which react with the toxins and destroy their
+poisonous character&mdash;whenever required, but that against
+any foreign body of the albumen group a specific reaction
+may occur, resulting in the coagulation of that body. But
+the destruction of the noxious substance or foreign albumen
+actually present is not all that is accomplished by the
+organism. “Acquired immunity” proper, that is, security
+against the noxious material for a more or less extensive
+period of the <em>future</em>, depends on something more. Not
+only is there produced as much of the so-called “anti-body”
+as is necessary to combine with the noxious, or at least
+foreign substances which are present, but <em>more</em> is produced
+than is necessary in the actual case. On this over-production
+depends all active immunity, whether natural or,
+as in some kinds of vaccination, artificial; and so-called
+“passive” immunity, obtained by the transfusion of the
+serum of an actively immune organism into another also
+depends upon this <span class="nowrap">feature.<a name="FNanchor_115_115" id="FNanchor_115_115"></a><a href="#Footnote_115_115" class="fnanchor">115</a></span></p>
+
+<p>This phenomenon in particular&mdash;the production of <em>more</em>
+of the antitoxin or the “precipitin” than is actually<span class="pagenum" title="208"><a name="Page_208" id="Page_208"></a></span>
+necessary&mdash;seems to render almost impossible any merely
+chemical theory of these facts. The reaction between
+toxin and antitoxin, albumen and precipitin is indeed
+chemical; it may in fact be carried out in a test-tube;
+but whether the production of the anti-body itself is
+also chemical or not could hardly be ascertained without
+a careful and unbiassed analysis. There can be no doubt
+that the well-known theory of <span class="nowrap">Ehrlich,<a name="FNanchor_116_116" id="FNanchor_116_116"></a><a href="#Footnote_116_116" class="fnanchor">116</a></span> the so-called theory
+of side-chains (“Seitenkettentheorie”) has given a great
+impulse to the progress of science; but even this theory,
+irrespective of its admissibility in general, is not a real
+chemical one: the concept of a regeneration of its so-called
+haptophore groups is a strictly biological <span class="nowrap">concept.<a name="FNanchor_117_117" id="FNanchor_117_117"></a><a href="#Footnote_117_117" class="fnanchor">117</a></span></p>
+
+<p>And, indeed, here if anywhere we have the biological
+phenomenon of adaptation in its clearest form. There are
+very abnormal changes of the functional state of the
+organism, and the organism is able to compensate these
+changes in their minutest detail in almost any case. The
+problem of the specification of the reactions leading to
+immunity seems to me, as far as I can judge as an outsider,
+to stand at present in the very forefront of the science.
+There cannot be the slightest doubt that especially against
+all sorts of foreign albumens the reaction is as strictly
+specific as possible; but there are some typical cases of<span class="pagenum" title="209"><a name="Page_209" id="Page_209"></a></span>
+specificity in the production of antitoxins also. It is, of
+course, the <em>fact</em> of specific correspondence between stimulus
+and reaction, that gives to immunity its central position
+among all adaptations, no matter whether the old hypothesis
+of the production of specific anti-bodies proves tenable, or
+whether, as has been urged more recently by some authors,
+the anti-body is always the same but reacts differently
+according to the medium. In the latter case it would be
+the medium that is regulated in some way by the organism
+in order to attain a specific adaptedness.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">NO GENERAL POSITIVE RESULT FROM THIS CHAPTER</span></p>
+
+<p>But now let us look back to the sum of all the physiological
+reactions studied, and let us see if we have gained
+a new proof of the autonomy of life from our long chapter.</p>
+
+<p>We freely admit we have not gained any really new
+<em>proof</em>, but we may claim, I think, to have gained many
+indicia for the statement that the organism is not of the
+type of a machine, in which every single regulation is to
+be regarded as properly prepared and outlined.</p>
+
+<p>It is precisely in the field of immunity that such a
+machine-like preparation of the adaptive effects seems
+almost impossible to be imagined. How indeed could there
+be a machine, the chemical constituents of which were such
+as to correspond adaptively to almost every requirement?&mdash;to
+say nothing of the fact that the production of <em>more</em> of
+the protecting substance than is actually necessary could
+hardly be said to be “chemical.”</p>
+
+<p>In fact, we are well entitled to say that we have reached
+here the very heart of life and of biology. If nevertheless<span class="pagenum" title="210"><a name="Page_210" id="Page_210"></a></span>
+we do not call the sum of our facts a real proof of vitalism,
+it is only because we feel unable to formulate the analysis
+of what happens in such a manner as to make a machine
+as the basis of all reactions absolutely unimaginable and
+unthinkable. There <em>might</em> be a true machine in the organism
+producing immunity with all its adaptations. We cannot
+disprove such a doctrine by demonstrating that it would
+lead to a real <em>absurdity</em>, as we did in our analysis of
+differentiation of form; there is only a very high degree
+of improbability in our present case. But an indirect
+<em>proof</em> must reduce to <em>absurdity</em> all the possibilities except
+one, in order to be a proof.</p>
+
+<p>Mechanistic explanations in all branches of functional
+physiology proper, so much in vogue twenty years ago, can
+indeed be said to have failed all along the line: the only
+advantage they have brought to science is the clearer
+statement of problems to which we are now accustomed.
+But we are not fully entitled to <span class="nowrap">say<a name="FNanchor_118_118" id="FNanchor_118_118"></a><a href="#Footnote_118_118" class="fnanchor">118</a></span> that there never will
+be any mechanistic explanation of physiological functions
+in the future. It may seem as improbable as anything
+can be; but we wish to know not what is improbable but
+what is not possible.</p>
+
+<p>Now of course you might answer me that after we have
+indeed shown that the production of form, as occurring on
+the basis of harmonious-equipotential systems, is a fact that
+proves vitalism, the acts taking place on the basis of that
+form after its production would have been proved to be
+vitalistic also, or at least to be in some connection with
+vitalistic phenomena. Certainly they would, and I myself<span class="pagenum" title="211"><a name="Page_211" id="Page_211"></a></span>
+personally should not hesitate to say so. But that is not
+the question. We have to ask: Is any new proof, <em>independent
+of every other</em>, to be obtained from the facts of
+physiological adaptation in themselves? And there is really
+none. Mere regulatory correspondence between stimuli and
+reactions, even if it be of the adaptive type and occur in
+almost indefinite forms, never really disproves a machine
+as its basis so long as the stimuli and reactions are <em>simple</em>
+and uniform. Next summer, however, we shall see that
+vitalism may be proved by such a correspondence if the
+two corresponding factors are not simple and not uniform.</p>
+
+<p>We most clearly see at this point what it really was
+in our analysis of differentiation that allowed us to extract
+a real proof of vitalism from it. Not the mere fact of
+regulability, but certain specific relations of space, of locality,
+lay at the very foundation of our proof. These relations,
+indeed, and only these relations, made it possible to reduce
+<i lang="la" xml:lang="la">ad absurdum</i> any possible existence of a machine as the
+actual basis of what we had studied. In our next chapter
+again it will be space-relations, though analysed in a different
+manner, that will enable us to add a second real proof
+of vitalism to our first one.</p>
+
+<p>With this chapter we conclude the study of organic
+regulation in all its forms, as far as morphogenesis and
+metabolism are in question.</p>
+
+<p>But our analysis of these regulations would be incomplete
+and indeed would be open to objections, if we did not
+devote at least a few words to two merely negative
+topics, which will be taken more fully into consideration
+later on.</p>
+
+<p><span class="pagenum" title="212"><a name="Page_212" id="Page_212"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">A FEW REMARKS ON THE LIMITS OF REGULABILITY</span></p>
+
+<p>There has never been found any sort of “experience” in
+regulations about morphogenesis or in adaptations of the
+proper physiological type. Nothing goes on “better” the
+second time than it did the first <span class="nowrap">time;<a name="FNanchor_119_119" id="FNanchor_119_119"></a><a href="#Footnote_119_119" class="fnanchor">119</a></span> everything is either
+complete, whenever it occurs, or it does not occur at all.</p>
+
+<p>That is the first of our important negative statements
+about regulations; the second relates to the phrase just
+used, “or it does not occur at all.” There are indeed limits
+of regulability; adaptations are not possible to every sort
+of change of the physiological state: sickness and death
+could not exist if they were; nor is restitution possible in
+all cases where it might be useful. It is a well-known fact,
+that man is only able to heal wounds but is altogether
+destitute of the faculty of regeneration proper. But even
+lower animals may be without this faculty, as are the
+ctenophores and the nematodes for instance, and there is no
+sort of correspondence between the faculty of restitution
+and the place in the animal kingdom. It is not altogether
+impossible that there may be found, some day, certain conditions
+under which every organism is capable of restoring<span class="pagenum" title="213"><a name="Page_213" id="Page_213"></a></span>
+any missing part; but at present we know absolutely
+nothing about such <span class="nowrap">conditions.<a name="FNanchor_120_120" id="FNanchor_120_120"></a><a href="#Footnote_120_120" class="fnanchor">120</a></span></p>
+
+<p>But no amount of negative instances can disprove an
+existing positive&mdash;which is what we have been studying.
+Our analysis based upon the existence of regulations is
+as little disparaged by cases where no regulability exists
+as optical studies are by the fact that they cannot be
+undertaken in absolute darkness.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="214"><a name="Page_214" id="Page_214"></a></span></p>
+
+
+
+
+<h3><i>D.</i> INHERITANCE: SECOND PROOF OF THE AUTONOMY OF LIFE</h3>
+
+
+<p>All organisms are endowed with the faculty of re-creating
+their own initial form of existence.</p>
+
+<p>In words similar to these Alexander Goette, it seems to
+me, has given the shortest and the best expression of the
+fact of inheritance. Indeed, if the initial form in all its
+essentials is re-created, it follows from the principle of
+univocality, that, <i lang="la" xml:lang="la">ceteris paribus</i>, it will behave again as
+it did when last it existed.</p>
+
+<p>By the fact of inheritance life becomes a rhythmic
+phenomenon, that is to say, a phenomenon, or better, a chain
+of phenomena, whose single links reappear at constant
+intervals, if the outer conditions are not changed.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Material Continuity in Inheritance</span></p>
+
+<p>It was first stated by Gustav Jaeger and afterwards
+worked out into a regular theory by Weismann, that there
+is a continuity of material underlying inheritance. Taken
+in its literal meaning this statement is obviously self-evident,
+though none the less important on that account.
+For as all life is manifested on bodies, that is on matter,
+and as the development of all offspring starts from parts of
+the parent bodies, that is from the matter or material of the<span class="pagenum" title="215"><a name="Page_215" id="Page_215"></a></span>
+parents, it follows that in some sense there is a sort of
+continuity of material as long as there is life&mdash;at least in
+the forms we know of. The theory of the continuity of
+“germ-plasm” therefore would be true, even if germ-cells
+were produced by any and every part of the organism. That,
+as we know, is not actually the case: germ-cells, at least
+in the higher animals and in plants, are produced at certain
+specific localities of the organism only, and it is with regard
+to this fact that the so-called theory of the “continuity of
+germ-plasm” acquires its narrower and proper sense. There
+are distinct and specific lines of cell-lineage in ontogenesis,
+so the theory states, along which the continuity of germ-protoplasm
+is kept up, which, in other words, lead from one
+egg to the other, whilst almost all other lines of cell-lineage
+end in “somatic” cells, which are doomed to death. What
+has been stated here is a fact in many cases of descriptive
+embryology, though it can hardly be said to be more than
+that. We know already, from our analytical and experimental
+study of morphogenesis, that Weismann himself had
+to add a number of subsidiary hypotheses to his original
+theory to account for the mere facts of regeneration proper
+and the so-called vegetative reproduction in plants and in
+some animals, and we have learned that newly discovered
+facts necessitate still more appendixes to the original theory.
+In spite of that, I regard it as very important that the fact
+of the continuity of some material as one of the foundations
+of inheritance has clearly been stated, even if the specialised
+form of the theory, as advocated by Weismann in the
+doctrine of the “germ-lineages” (“Keimbahnen”) should
+prove unable to stand against the facts.</p>
+
+<p>The important problem now presents itself: What is the<span class="pagenum" title="216"><a name="Page_216" id="Page_216"></a></span>
+material, the matter, which is handed down from generation
+to generation as the basis of inheritance? Weismann, as
+we know, regarded it as a very complicated structure, part
+of which by its disintegration became the foundation of
+individual embryology. We have disproved, on the authority
+of many facts, the latter part of this assumption; but of
+course the first part of it may turn out to be true in spite
+of this. We have no means at present to enable us to say
+<i lang="la" xml:lang="la">a priori</i> anything positive or negative about the important
+question of the nature of that matter, the continuity of which
+in inheritance is in some sense a self-evident fact, and we
+therefore shall postpone the answer until a later point of
+our analytical discussion.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">On Certain Theories which Seek to Compare
+Inheritance to Memory</span></p>
+
+<p>It will be advisable first to study some other theoretical
+views which have been put forward with regard to inheritance.
+The physiologist Hering, as early as 1876,
+compared all heredity to the well-known fact of memory,
+assuming, so to say, a sort of remembrance of all that has
+happened to the species in the continuity of its generations;
+and several German authors, especially Semon, have lately
+made this hypothesis the basis of more detailed speculation.</p>
+
+<p>It is not clear, either from Hering’s <span class="nowrap">paper<a name="FNanchor_121_121" id="FNanchor_121_121"></a><a href="#Footnote_121_121" class="fnanchor">121</a></span> or from
+Semon’s <span class="nowrap">book,<a name="FNanchor_122_122" id="FNanchor_122_122"></a><a href="#Footnote_122_122" class="fnanchor">122</a></span> what is really to be understood here by
+the word “memory,” and, of course, there might be understood
+by it very different things, according to the autho<span class="pagenum" title="217"><a name="Page_217" id="Page_217"></a></span>r’s
+psychological point of view. If he is a “parallelist” with
+regard to so-called psychical phenomena, he would use the
+word memory only as a sort of collective term to signify
+a resultant effect of many single mechanical events, as far as
+the material world of his parallel system comes into account,
+with which of course the problem of inheritance alone deals;
+but if he maintains the theory of so-called psycho-physical
+interaction, the psychical would be to him a primary factor
+in nature, and so also would memory. As we have said, it
+is by no means clear in what sense the word “memory”
+is used by our authors, and therefore the <em>most</em> important
+point about the matter in question must remain <i lang="la" xml:lang="la">in dubio</i>.</p>
+
+<p>But another topic is even more clear in the theory of
+inheritance, as stated in Hering’s and Semon’s writings.
+The hypothetical fact that so-called “acquired characters”
+are inherited is undoubtedly the chief assumption of that
+theory. Indeed, it would be difficult to understand the
+advantage of the ambiguous word memory, had it not to
+call attention to the hypothetic fact that the organism
+possesses the faculty of “remembering” what once has
+happened to it or what it once has “done,” so to speak, and
+profiting by this remembering in the next generation. The
+zoologist Pauly indeed has stated this view of the matter
+in very distinct and clear terms.</p>
+
+<p>As we soon shall have another occasion to deal with the
+much-discussed problem of the “inheritance of acquired
+characters,” we at present need only say a few words
+about the “memory-theory” as a supposed “explanation”
+of heredity. Undoubtedly this theory postulates, either
+avowedly or by half-unconscious implication, that all the
+single processes in individual morphogenesis are the outcome<span class="pagenum" title="218"><a name="Page_218" id="Page_218"></a></span>
+either of adaptations of the morphological type, which
+happened to be necessary in some former generation, or of
+so-called contingent “variations,” of some sort or other,
+which also happened once in the ancestral line. Such a
+postulate, of course, is identical with what is generally called
+the theory of descent in any of its different forms. This
+theory is to occupy us in the next lectures; at present we
+only analyse the “memory-theory” as a theory of heredity
+in itself. In any case, to regard memory as the leading
+point in inheritance, at least if it is to signify what is
+called memory in any system of psychology, would be to
+postulate that either adaptation or contingent “variation”
+has been the origin of every morphogenetic process. Indeed,
+the American physiologist Jennings did not hesitate to
+defend such a view most strongly, and many others seem to
+be inclined to do the same.</p>
+
+<p>But such an assumption most certainly cannot be true.</p>
+
+<p>It cannot be true, because there are many phenomena
+in morphogenesis, notably all the phenomena akin to
+restitution of form, which occur in absolute perfection even
+the very first time they happen. These processes, for the
+simple reason of their <em>primary perfection</em>, cannot be due
+either to “learning” from a single adaptation, or to accidental
+variation. We shall afterwards employ a similar kind of
+argument to refute certain theories of evolution. It therefore
+may be of a certain logical interest to notice that at
+present, combating the memory-theory of inheritance, and
+hereafter, combating certain theories of descent, we select
+not “adaptation” or “variation” as the central points to
+be refuted, but the assumed <em>contingency</em> of both of them.</p>
+
+<p>The word “memory,” therefore, may be applied to the<span class="pagenum" title="219"><a name="Page_219" id="Page_219"></a></span>
+phenomena of inheritance only in a very figurative meaning,
+if at all. We do not wholly deny the possibility of an
+inheritance of acquired characters, as will be seen later on,
+and to such a fact there might perhaps be applied such a
+term as “memory” in its real sense, but we simply <em>know</em>
+that there <em>is</em> something in inheritance which has no
+similarity whatever to what is called “memory” in any
+species of psychology. A primary perfection of processes
+occurring quite abnormally proves that there is a “knowing”
+of something&mdash;if we may say so&mdash;but does not prove
+at all that there is a “remembering.”</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Complex-Equipotential System and its Rôle in
+Inheritance</span><a name="FNanchor_123_123" id="FNanchor_123_123"></a><a href="#Footnote_123_123" class="fnanchor">123</a></p>
+
+<p>But we thus far have reached only negative results. Is
+the question necessarily to remain at this point, which
+could hardly be said to be very satisfying; or could we
+perhaps get better, that is, positive results about inheritance
+by a change of our analytic methods? Let us try to
+analyse the facts that occur in inheritance instead of
+beginning with hypotheses which claim to be complete
+explanations. Perhaps we shall gain, if but small, yet
+certainly fixed results by an analysis which goes from the
+facts to the theory and not from the theory to the facts.</p>
+
+<p>Let the discussions that are to follow be placed upon
+a basis as broad as possible.</p>
+
+<p>Our studies of morphogenetic restitution have shown us
+that besides the harmonious-equipotential systems another
+and widely different type of morphogenetic “systems” (<i>i.e.</i><span class="pagenum" title="220"><a name="Page_220" id="Page_220"></a></span>
+unities consisting of elements equal in morphogenetic
+faculty) may also be the basis of restitution processes.
+Whilst in the harmonious system the morphogenetic acts
+performed by every single element in any actual case are
+single acts, the totality of all the single acts together forming
+the harmonious whole, in the other type of systems now to
+be examined, complex acts, that is, acts which consist of a
+manifoldness in space and in time, can be performed by
+each single element, and actually are performed by one or
+the other of them. We therefore have given the title of
+“complex-equipotential systems” to the systems in question,
+as all our denominations are based on the concept of the
+prospective morphogenetic potency, that is of the possible
+fate of the elements.</p>
+
+<p>The cambium of the Phanerogams may be regarded as
+the very type of a complex-equipotential system, promoting
+restitution of form. It runs through the whole stem of
+our trees, in the form of a hollow tube, placed between
+the inner and the outer cell-layers of the stem, and either
+branch or root may originate from any single one of its
+cells, just as circumstances require. We might call the
+cambium a system of the “complex” type of course, even
+if every one of its constituents were able to form only a root
+or only a branch by way of restitution. But in fact one
+and the same element can form both of these complex-structures;
+it depends only on its relative position in the
+actual part of the stem isolated for the purposes of experiment,
+what will be accomplished in every case. Here we
+have a state of affairs, which we shall encounter again
+when studying regeneration in animals: every element of
+the system may be said to contain potencies for the <span class="pagenum" title="221"><a name="Page_221" id="Page_221"></a></span>“ideal
+whole,” though this ideal whole will never be realised in
+its proper <span class="nowrap">wholeness.<a name="FNanchor_124_124" id="FNanchor_124_124"></a><a href="#Footnote_124_124" class="fnanchor">124</a></span></p>
+
+<p>But there is no need to recur to the “ideal whole” in
+many other cases of adventitious restitution in plants.
+On isolated leaves of the well-known begonia, a whole plant,
+containing all the essential parts, may arise from any single
+<span class="nowrap">cell<a name="FNanchor_125_125" id="FNanchor_125_125"></a><a href="#Footnote_125_125" class="fnanchor">125</a></span> of the epidermis, at least along the veins, and in some
+liverworts it has been shown by Vöchting, that almost
+every cell of the whole is able to reproduce the plant, as
+is also the case in many algae.</p>
+
+<p>In the animal kingdom it is chiefly and almost solely
+the phenomena of regeneration proper which offer typical
+instances of our systems, since adventitious restitution,
+though occurring for instance in the restitution of the lens
+of vertebrates from the iris, and though connected also with
+the events in regeneration <span class="nowrap">proper,<a name="FNanchor_126_126" id="FNanchor_126_126"></a><a href="#Footnote_126_126" class="fnanchor">126</a></span> is of but secondary
+importance in animal restitution, at least, if compared with
+restitution in plants. If we study the regeneration of a
+leg in the common newt, we find that it may take place
+from every section, the point of amputation being quite at<span class="pagenum" title="222"><a name="Page_222" id="Page_222"></a></span>
+our choice. Without regarding here the exact order of
+the regeneration phenomena, which is almost unknown at
+present, we in any case can say without any doubt that
+the line of consecutive possible cross-sections forms a
+complex-morphogenetic system, as every one of them is
+able to give rise to a complex organ, viz. the foot and part
+of the leg. It is an open question whether this complex
+system is to be called “equipotential” or not. It indeed
+seems to be inequipotential at the first glance, for each
+single section has to form a different organogenetic totality,
+namely, always that specific totality which had been cut
+off; but if we assume hypothetically that the real “Anlage”
+which is produced immediately by the cells of the wounded
+surface is the very same for all of them, and that it is the
+actual state of organisation which determines to what result
+this Anlage is to <span class="nowrap">lead,<a name="FNanchor_127_127" id="FNanchor_127_127"></a><a href="#Footnote_127_127" class="fnanchor">127</a></span> we may say that the series of consecutive
+cross-sections of a newt’s leg does form a morphogenetic
+system of the complex-equipotential type, promoting
+secondary regulations of form.</p>
+
+<p>Now all these difficulties vanish, if we consider the
+regeneration of animals, such for instance as many worms
+of the annelid class or our familiar ascidian <i class="biological-name">Clavellina</i>, in
+which regeneration in both directions is possible. The
+wound at the posterior end of the one half which results
+from the operation forms a posterior body half, the wound<span class="pagenum" title="223"><a name="Page_223" id="Page_223"></a></span>
+at the anterior end of the other half forms an anterior one.
+Again, it is the ideal whole which we meet here: each
+section of the body indeed may be said to contain the
+potencies for the production of the totality, though actually
+this totality is always realised by the addition of two
+partial organisations. The title of complex-equipotential
+systems thus seems to be fully justified as applied to the
+systems which are the basis of regeneration: each section
+of the regenerating body may in fact produce the same
+complex whole, or may, if we prefer to say so, at least
+prepare the ground for that complex Anlage, out of which
+the complex totality is actually to arise, in the same
+manner.</p>
+
+<p>It often occurs in science, that in rather strange and
+abnormal conditions something becomes apparent which
+might have been found everywhere, which is lying before
+our eyes quite obviously. Are we not in just such a
+condition at present? In order to study the complex-equipotential
+systems, we turn to the phenomena of
+regeneration and of restitution in general; we occasionally
+even introduce hypotheses to render our materials more
+convenient for our purposes; and all the time there is
+one sort of complex-equipotential system in the body of
+every living being, which only needs to be mentioned in
+order to be understood as such, and which indeed requires
+no kind of preliminary discussion. The system of the
+propagation cells, in other words the sexual organ, is the
+clearest type of a complex-equipotential system which
+exists. Take the ovary of our sea-urchin for instance, and
+there you have a morphogenetic system every element of
+which is equally capable of performing the same complex<span class="pagenum" title="224"><a name="Page_224" id="Page_224"></a></span>
+morphogenetic course&mdash;the production of the whole
+individual.</p>
+
+<p>Further on we shall deal exclusively with this variety
+of our systems, and in doing so we shall be brought back
+to our problem of heredity. But it had its uses to place
+our concept of the complex-equipotential system upon such
+a broad basis: we at once gave a large range of validity to
+all that is to follow&mdash;which, indeed, does not apply to inheritance
+alone, though its significance in a theory of
+heredity may be called its most important consequence.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Second Proof of Life-Autonomy. Entelechy at
+the Bottom of Inheritance</span></p>
+
+<p>After we had established the concept of the harmonious-equipotential
+system in a former chapter, we went on
+to study the phenomena of the differentiation of it,
+and in particular the problem of the localisation of all
+differentiations. Our new concept of the complex-equipotential
+system is to lead us to an analysis of a
+different kind: we shall pay special attention to the origin,
+to the <em>genesis</em> of our complex systems that show equipotentiality.</p>
+
+<p>If we review the process of ontogenesis, we are able to
+trace back every complex system to a very small group of
+cells, and this small group of cells again to one single cell.
+So in plants the cambium may be shown to have originated
+in a sort of tissue-rudiment, established at a very early
+period, and the ovary may be demonstrated to be the outcome
+of a group of but a few cells, constituting the first
+visible “Anlage” of the reproductive organs. At the end<span class="pagenum" title="225"><a name="Page_225" id="Page_225"></a></span>
+then, or from another point of view at the beginning,
+a single cellular element represents the very primordial
+egg-cell.</p>
+
+<p>The whole cambium, there can be no doubt, must be
+regarded as the result of a consecutive number of cell-divisions
+of the one cell from which it originates. So
+must it be with the ovary. The primordial egg-cell has
+undergone a long line of consecutive divisions; the single
+eggs are the last result of them.</p>
+
+<p>We now proceed to some considerations which have a
+certain logical similarity to those which inaugurated our
+analysis of the differentiation of the harmonious-equipotential
+systems, though the facts in question are very different.</p>
+
+<p>Viewed by itself without any kind of prepossessions, as
+it might be by any one who faces a new problem with the
+single postulate of introducing new natural entities&mdash;to
+use the scholastic phrase&mdash;as little as possible, the development
+of the single egg might be regarded as proceeding
+on the foundation of a very complicated sort of machine,
+exhibiting a different kind of construction in the three
+chief dimensions of space, as does also the organism which
+is to be its result.</p>
+
+<p>But could such a theory&mdash;irrespective of all the experimental
+facts which contradict it&mdash;could such a theory
+stand before the <em>one</em> fact, that there occurs a <em>genesis</em> of that
+complex-equipotential system, of which our one single egg
+forms a part? Can you imagine a very complicated
+machine, differing in the three dimensions of space, to be
+divided hundreds and hundreds of times and in spite of
+that to remain always the same whole? You may reply that
+during the period of cell-divisions there is still no machine,<span class="pagenum" title="226"><a name="Page_226" id="Page_226"></a></span>
+that the machine is established only after all the divisions
+are complete. Good; but what then constructs this
+machine in the definitive cells of our systems, say in the
+eggs? Another sort of machine perhaps? That could
+hardly be said to be of much use. Or that entelechy of
+which we have spoken? Then you would recur to our
+first proof of vitalism and would burden entelechy with a
+specific performance, that is with the construction of the
+hypothetic machine which you are postulating in every
+single egg. But of course you would break the bounds of
+physics and chemistry even then.</p>
+
+<p>It seems to me that it is more simple, and so to say
+more natural, not to recur to our first proof of life-autonomy
+in order to keep to the “machine theory” in
+this new branch of inquiry, but to consider facts as they
+offer themselves to analysis.</p>
+
+<p>But then indeed we are entitled to draw an independent
+second proof of the autonomy of life from our analysis of
+the genesis of systems of the complex-equipotential type.
+We say it is a mere absurdity to assume that a complicated
+machine, typically different in the three dimensions of space,
+could be divided many many times, and in spite of that
+always be the whole: therefore there cannot exist any sort
+of machine as the starting-point and basis of development.</p>
+
+<p>Let us again apply the name entelechy to that which
+lies at the very beginning of all individual morphogenesis.</p>
+
+<p>Entelechy thus proves to be also that which may be
+said to lie at the very root of <span class="nowrap">inheritance,<a name="FNanchor_128_128" id="FNanchor_128_128"></a><a href="#Footnote_128_128" class="fnanchor">128</a></span> or at least of<span class="pagenum" title="227"><a name="Page_227" id="Page_227"></a></span>
+the outcome of inheritance; the individual formation of the
+next generation is shown not to be performed by a machine
+but by a natural agent <i lang="la" xml:lang="la">per se</i>.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Significance of the Material Continuity in
+Inheritance</span></p>
+
+<p>But what about the material continuity appearing in
+inheritance, which we have said to be almost self-evident,
+as life is only known to exist on material bodies? Is
+there not, in fact, a serious contradiction in admitting at
+the same time entelechy on the one side and a sort
+of material condition on the other as the basis of all
+that leads to and from inheritance? Next summer the
+relation between matter and our autonomous agent of life
+will be studied more fully; at present it must be enough
+to state in a more simple and realistic way, what we hold
+this relation to be. There is no contradiction at all in
+stating that material continuity is the basis of inheritance
+on the one side, and entelechy on the other. It would
+be very inconvenient for us if there were any: for the
+material continuity is a mere fact and our entelechy we
+hope we have proved to exist also; if now there were any
+sort of contradiction in assuming the existence of both of
+them, of course it would be fatal to our proof.</p>
+
+<p>Let us try to comprehend what is meant by the
+statement that entelechy and something material are at
+work in inheritance at the same time. Entelechy has ruled
+the individual morphogenesis of the generation which is
+regarded as being the starting-point for inheritance, and
+will rule also the morphogenesis of the generation which<span class="pagenum" title="228"><a name="Page_228" id="Page_228"></a></span>
+is to follow; entelechy determines the egg to be what it is,
+and the morphogenesis starting from this egg to be what
+it is also. Entelechy, at present, is not much more for us
+than a mere word, to signify the autonomous, the irreducible
+of all that happens in morphogenesis with respect to <em>order</em>,
+in the one generation and in the next. But may not the
+material continuity which exists in inheritance account
+perhaps for the material elements <em>which are to be ordered</em>?
+In such a way, indeed, I hope we shall be able to reconcile
+entelechy and the material basis of heredity. May it not
+be that there exist some “means” for morphogenesis,
+which are handed down from generation to generation,
+always controlled by entelechy, and which constitute the real
+significance of the continuity of matter during inheritance?</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Experimental Facts about Inheritance</span></p>
+
+<p>Discoveries of the last few years do seem to show that
+such means of a material character, though not the foundation
+of that order of processes which is inherited, are
+nevertheless among the most necessary conditions for the
+accomplishment of inheritance in general. It is scarcely
+necessary to remind you that for very many years all
+concrete research on heredity proper&mdash;that is, the actual
+comparison of the various specific characters in the generations
+of the grandfather, the father, and the child&mdash;was
+due to Galton. You may also be aware that in spite of
+Galton’s inestimable services it was not till 1900 that one
+of the active principles concerned in inheritance was found
+independently by de Vries, Correns, and Tschermak, and
+that this principle happened to be one that <em>had</em> been<span class="pagenum" title="229"><a name="Page_229" id="Page_229"></a></span>
+discovered already, stated with the utmost clearness and
+precision by the Augustinian monk, Gregor <span class="nowrap">Mendel,<a name="FNanchor_129_129" id="FNanchor_129_129"></a><a href="#Footnote_129_129" class="fnanchor">129</a></span> as
+early as 1865, though it had been completely forgotten
+ever since.</p>
+
+<p>The so-called “rule of Mendel” is based upon experiments
+with hybrids, that is, with the offspring of parents
+belonging to different species, or, at least, varieties, but it
+relates not to the characters of the generation resulting
+immediately from hybridisation, the “first” generation of
+hybrids, as we shall call it, but to the characters of that
+generation which is the result of crossing the hybrids with
+each other, provided that this leads to any offspring at all.
+There are many cases indeed, both amongst animals and
+plants, where the offspring of the hybrids, or in other
+terms the “second” generation, is found to consist of
+individuals of three different types&mdash;the <span class="nowrap">mixed<a name="FNanchor_130_130" id="FNanchor_130_130"></a><a href="#Footnote_130_130" class="fnanchor">130</a></span> type of
+the hybrids themselves, and the two pure types of the
+grandparents. Whenever the individuals of the “second”
+generation are separated into these three different types,
+hybrids are said to “split.” It is the fact of this splitting
+on the one hand, and on the other hand a certain statement
+about the numbers of individuals in the three different
+types of the “second” generation, that gives its real
+importance to Mendel’s rule.</p>
+
+<p>Before discussing what may follow from Mendel’s
+discovery for the theory of heredity, we must lay stress<span class="pagenum" title="230"><a name="Page_230" id="Page_230"></a></span>
+on the fact that there are many exceptions to his rule.
+In quite a number of cases the hybrids are of one or more
+types, which remain constant: there is no splitting at all
+in the second generation. But that does not affect the rule
+of Mendel in those cases where it is true. Where there
+is a “splitting” in the second generation, there also are the
+numerical proportions stated by Mendel; there never are
+other relations among the numbers of individuals of the
+mixed and of the two pure types than those given by his
+rule. I regard it as very important that this real meaning
+of Mendel’s principle should be most clearly understood.</p>
+
+<p>From the fact of the splitting of hybrids in the second
+generation most important consequences may be drawn for
+the theory of inheritance; the split individuals, if crossed
+with each other, always give an offspring which remains
+pure; there is no further splitting and no other change
+whatever. The germ-cells produced by the split individuals
+of the second generation may therefore be said to be
+“pure,” as pure as were those of the grandparents. But
+that is as much as to say that the pureness of the germ-cells
+has been preserved in spite of their passing through
+the “impure” generation of the hybrids, and from this fact
+it follows again that the union of characters in the hybrids
+must have been such as to permit pure separation: in
+fact, the germ-cells produced by Mendelian hybrids may
+hypothetically be regarded as being pure <span class="nowrap">themselves.<a name="FNanchor_131_131" id="FNanchor_131_131"></a><a href="#Footnote_131_131" class="fnanchor">131</a></span></p>
+
+<p>We have not yet considered one feature of all experi<span class="pagenum" title="231"><a name="Page_231" id="Page_231"></a></span>ments
+in hybridisation, which indeed seems to be the most
+important of all for the theory of inheritance, if taken
+together with the fact of the pureness of the germs. The
+rule of Mendel always relates to one single character of
+the species or varieties concerned in hybridisation, and if
+it deals with more than one character, it regards every one
+of them separately; indeed, the rule holds for every one
+of them irrespective of the others. We cannot study here
+how this most important fact of the independence of the
+single characters of a species with regard to inheritance
+leads to the production of new races, by an abnormal
+mixture of those characters. We only take advantage of
+the fact theoretically, and in doing so, I believe, we can
+hardly escape the conclusion that the independence of
+the single characters in inheritance, taken together with
+the pureness of the germ-cells in the most simple form
+of hybrids, proves that there occurs in inheritance a sort
+of handing over of single and separate morphogenetic
+agents which relate to the single morphogenetic characters
+of the adult. We may use Bateson’s word “allelomorphs”
+for these agents, or units, as they may be called, thereby
+giving expression to the fact that the single and separate
+units, which are handed over in inheritance, correspond to
+each other in nearly related species without being the same.</p>
+
+<p>And so we have at least an inkling of what the material
+continuity of inheritance is to mean, though, of course, our
+“single and separate morphogenetic agents,” or “units” or
+“allelomorphs” are in themselves not much more than
+unknown somethings described by a word; but even then
+they are “somethings.”</p>
+
+<p>Besides the researches relating to the rule of Mendel<span class="pagenum" title="232"><a name="Page_232" id="Page_232"></a></span>
+and its exceptions, founded, that is, upon a study of the
+“second” generation of hybrids, there is another important
+line of research lately inaugurated by Herbst, which investigates
+the first generation in hybridisation. The hybrids
+themselves are studied with the special purpose of finding
+out whether the type of the single hybrid may change
+according to the conditions of its development, both outer
+and inner. The discoveries thus made may lead some day to
+a better understanding of the intimate nature of the “units”
+concerned in heredity, and perhaps to some knowledge of
+the arranging and ruling factor in morphogenesis also.</p>
+
+<p>Starting from the discovery of Vernon, that the hybrids
+of sea-urchins are of different types according to the
+season, <span class="nowrap">Herbst<a name="FNanchor_132_132" id="FNanchor_132_132"></a><a href="#Footnote_132_132" class="fnanchor">132</a></span> was able to show that differences among
+the hybrids with regard to their being more of the paternal
+or more of the maternal type, are in part certainly due to
+differences in temperature. But there proved to be still another
+factor at work, and Herbst has succeeded in discovering this
+factor by changing the internal conditions of morphogenesis.
+Whenever he forced the eggs of <i class="biological-name">Sphaerechinus</i> to enter into
+the <span class="nowrap">first<a name="FNanchor_133_133" id="FNanchor_133_133"></a><a href="#Footnote_133_133" class="fnanchor">133</a></span> phase of artificial parthenogenesis and then fertilised
+them with the sperm of <i class="biological-name">Echinus</i>, he was able to approximate
+the offspring almost completely to the maternal type, whilst
+under ordinary conditions the hybrids in question follow
+the paternal far more than the maternal organisation.</p>
+
+<p>What is shown, in the first place, by these discoveries<span class="pagenum" title="233"><a name="Page_233" id="Page_233"></a></span>
+is the importance of an arranging and ruling factor in spite
+of all units. The organism is always one <em>whole</em> whether the
+paternal properties prevail or the more complicated maternal
+ones; in other words, all so-called properties that consist in the
+<em>spatial relations of parts</em> have nothing to do with “units” or
+“allelomorphs,” which indeed cannot be more than necessary
+means or materials, requiring to be ordered. As to the
+character of the morphogenetic single and separate units
+themselves Herbst is inclined to regard them as specific
+chemical substances which unite correspondingly during
+nuclear conjugation, forming a sort of loose chemical
+compound. It would depend on the constitution of this
+compound whether germ-cells of hybrids could become
+pure or not.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">The Rôle of the Nucleus in Inheritance</span></p>
+
+<p>At the end of our studies on heredity we hardly can
+avoid saying a few words about the problem of the localisation
+of the morphogenetic units in the germ-cells themselves.
+Is it in the protoplasm or in the nucleus that they are
+placed? You all know that this question was for a long
+time regarded as more important than any other, and
+perhaps you have already blamed me for not raising it
+until now. But in my opinion results gained by the
+purely analytical method and carefully established, are
+always superior to those which are of a merely descriptive
+nature and doubtful besides. The famous problem of
+the part played by the nucleus in inheritance is both
+descriptive and doubtful: it is only, so to say, of factual,
+not of analytical importance, and quite insoluble at present.</p>
+
+<p><span class="pagenum" title="234"><a name="Page_234" id="Page_234"></a></span></p>
+
+<p>As for our second proof of vitalism, stating that no kind
+of machine inside the germ-cells can possibly be the
+foundation of their morphogenesis, it is clear that the
+protoplasm and the nucleus may both come into account
+here on equal terms. If you prefer to say so, it is to the
+nucleus and to its division in particular that the second
+proof of autonomy relates, while the first, though not over-looking
+the presence of <span class="nowrap">nuclei,<a name="FNanchor_134_134" id="FNanchor_134_134"></a><a href="#Footnote_134_134" class="fnanchor">134</a></span> deals “especially” with the
+protoplasmic nature of its “systems.”</p>
+
+<p>What then can we say, on the basis of actual facts, about
+the part taken by the protoplasm and by the nucleus in
+inheritance, now that we have learnt from our analytical
+discussion that both of them cannot be any kind of
+morphogenetic machine, but can only be means of morphogenesis?
+Let us state our question in the following way:
+whereabouts in the germ-cells are those “means” of
+morphogenesis localised, the existence of which we infer
+from the material continuity in the course of generations
+in general and from the facts discovered about hybridisation
+in particular?</p>
+
+<p>The first of the facts generally said to support the
+view that the nucleus of the germ-cells exerts a specified
+influence upon the processes of development and inheritance,
+relates to the proportion between protoplasm and nuclear<span class="pagenum" title="235"><a name="Page_235" id="Page_235"></a></span>
+material in the egg and in the spermiae. This proportion
+is very different in the two sexual products, as we know,
+there being an enormous preponderance of the protoplasm
+in the egg, of the nucleus in the spermatozoon. This seems
+to indicate that the proportion between protoplasm and
+nucleus is fairly indifferent for inheritance, as all the facts
+go to show that inheritance from the father is as common
+as inheritance from the mother. It is in the nucleus, and
+in the nucleus alone, that any similarity of organisation
+exists between the two sexual products, so very different
+in all other respects: therefore the nucleus should be the
+organ of inheritance. The phenomena of nuclear division,
+of karyokinesis, which are quite equal in both sexual cells,
+are certainly well fitted to support this hypothesis.</p>
+
+<p>There seems indeed to be some truth in this reasoning,
+but nevertheless it must remain hypothetical; and it must
+never be forgotten that there may be very probably some
+sort of morphogenetic importance in protoplasm also. Rauber
+and afterwards <span class="nowrap">Boveri<a name="FNanchor_135_135" id="FNanchor_135_135"></a><a href="#Footnote_135_135" class="fnanchor">135</a></span> have tried to prove experimentally
+that it is on the nuclear chromatic substance only that
+inheritance depends, but the first of these authors failed
+to get any results at all, and the latter obtained only ambiguous
+ones. Godlewski, on the contrary, has fertilised
+purely protoplasmic egg-fragments of the sea-urchin with
+the sperm of quite another group of Echinoderms, and
+obtained in spite of that a few stages of development of the<span class="pagenum" title="236"><a name="Page_236" id="Page_236"></a></span>
+pure maternal type. This experiment seems to place the
+morphogenetic importance of protoplasm beyond all doubt.</p>
+
+<p>I should prefer not to make any definite statement
+about our problem at present. Our actual knowledge
+of the organisation and metabolism of both nucleus and
+protoplasm is so extremely small and may relate to such
+very insignificant topics, that any definite decision is impossible.
+I myself believe that the nucleus plays an
+important part in heredity, perhaps even a greater one
+than protoplasm, but this is only my <span class="nowrap">belief.<a name="FNanchor_136_136" id="FNanchor_136_136"></a><a href="#Footnote_136_136" class="fnanchor">136</a></span></p>
+
+<p>The discovery of Gruber and others, that Protozoa are
+only capable of restitution if they contain at least a fragment
+of the nucleus, has also been used occasionally as a
+proof of the morphogenetic importance of the nucleus. But
+might not this absence of restitution where nuclear
+material is lacking be understood equally well on the
+hypothesis of Loeb and R. S. Lillie that the nucleus is a
+centre of oxidation in the cell? Remove the heart from
+a vertebrate and the animal will not digest any more; but
+in spite of that the heart is not the organ of digestion.</p>
+
+<p>And so we lay stress once more upon this point: that
+the experimental results of hybridisation and the analytical
+results obtained by the discussion of the complex-equipotential
+systems are of greater value to the theory
+of heredity than all speculation about the importance or
+unimportance of special constituents of the cell, of whose
+organisation, chemistry, and physics, scarcely anything is
+known at <span class="nowrap">present.<a name="FNanchor_137_137" id="FNanchor_137_137"></a><a href="#Footnote_137_137" class="fnanchor">137</a></span></p>
+<p><span class="pagenum" title="237"><a name="Page_237" id="Page_237"></a></span></p>
+
+<p class="tac pt12b02em"><span class="smcap">Variation and Mutation</span></p>
+
+<p>Heredity, it has been said, may be understood as resting
+upon the fact that each organism forms its own initial
+stage again, and that this initial stage always encounters
+conditions of the same kind.</p>
+
+<p>If this statement were quite correct, all the individuals
+of a given species would be absolutely alike everywhere
+and for ever. But they are not alike; and that they are
+not alike everywhere and for ever is not merely the only
+real foundation of the so-called theory of descent we
+possess, but also forces us to change a little our definition
+of heredity, which now proves to have been only a sort of
+approximation to the truth, convenient for analytical
+discussion.</p>
+
+<p>In the first place, the conditions which surround the
+initial stages of morphogenesis are not quite equal in every
+respect: and indeed the offspring of a given pair of parents,
+or better, to exclude all complications resulting from
+sexual reproduction, or amphimixis, as Weismann called
+it&mdash;the offspring of one given parthenogenetic female are
+not all equal among themselves. The individuals of each
+generation are well known to vary, and it is especially in
+this country that the so-called individual or fluctuating<span class="pagenum" title="238"><a name="Page_238" id="Page_238"></a></span>
+variation has been most carefully studied by statistical
+methods, Galton and Weldon being the well-known
+pioneers in this <span class="nowrap">field.<a name="FNanchor_138_138" id="FNanchor_138_138"></a><a href="#Footnote_138_138" class="fnanchor">138</a></span> In fact, if we are allowed to assume
+that this sort of variation is the outcome of a variation of
+conditions&mdash;in the most general meaning of the word&mdash;we
+only follow the opinion which has almost universally
+been adopted by the <span class="nowrap">biologists<a name="FNanchor_139_139" id="FNanchor_139_139"></a><a href="#Footnote_139_139" class="fnanchor">139</a></span> that are working at this
+branch of the subject. Variation proper is now generally
+allowed to be the consequence of variations in nutrition;
+the contingencies of the latter result in contingencies
+of the former, and the law of contingencies is the same
+for both, being the most general law of probability. Of
+course under such an aspect fluctuating variation could
+hardly be called an exception, but rather an addition to
+inheritance.</p>
+
+<p>But there are other restrictions of our definition of
+heredity. The initial stage which is formed again by an
+organism is not always quite identical in itself with the
+initial stage of its own parent: Bateson and de Vries
+were the first to study in a systematic way these real <span class="nowrap">exceptions<a name="FNanchor_140_140" id="FNanchor_140_140"></a><a href="#Footnote_140_140" class="fnanchor">140</a></span>
+to true inheritance. As you know, de Vries has
+given them the name of “mutations.” What is actually
+known on this subject is not much at present, but nevertheless
+is of great theoretical value, being the only real<span class="pagenum" title="239"><a name="Page_239" id="Page_239"></a></span>
+foundation of all theories of descent, as we shall see in the
+next lectures. “Mutations” are known to exist at present
+only among some domesticated animals and plants. Nothing
+of a more general character can be said about their law or
+<span class="nowrap">meaning.<a name="FNanchor_141_141" id="FNanchor_141_141"></a><a href="#Footnote_141_141" class="fnanchor">141</a></span></p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="240"><a name="Page_240" id="Page_240"></a></span></p>
+
+
+<h3><span class="smcap">Conclusions from the First Main Part of these
+Lectures</span></h3>
+
+
+<p>In finishing our chapter on inheritance, we at the same
+time have finished the first main part of our lectures; that
+part of them which has been devoted exclusively to the
+study of the morphogenesis of the <em>individual</em>, including
+the functioning of the adult individual form. We now
+turn to our second part, which is to deal with the problems
+of the diversities of individual forms, with morphological
+systematics. The end of our chapter on inheritance has
+already led us to the threshold of this branch of biological
+science.</p>
+
+<p>The chief result of the first main part of our lectures
+has been to prove that an autonomy of life phenomena
+exists at least in some departments of individual morphogenesis,
+and probably in all of them; the real starting-point
+of all morphogenesis cannot be regarded as a machine,
+nor can the real process of differentiation, in all cases
+where it is based upon systems of the harmonious equipotential
+type. There cannot be any sort of machine in
+the cell from which the individual originates, because this
+cell, including both its protoplasm and its nucleus, has
+undergone a long series of divisions, all resulting in equal
+products, and because a machine cannot be divided and in<span class="pagenum" title="241"><a name="Page_241" id="Page_241"></a></span>
+spite of that remain what it was. There cannot be, on the
+other hand, any sort of machine as the real foundation of
+the whole of an harmonious system, including many cells
+and many nuclei, because the development of this system
+goes on normally, even if its parts are rearranged or partly
+removed, and because a machine would never remain what
+it had been in such cases.</p>
+
+<p>If our analytical discussions have thus led us to establish
+a typical kind of vitalism, it follows that we can by no
+means agree with Wilhelm Roux in his denomination of
+the analytical science of the individual form and form-production
+as “Entwickelungsmechanik,” “developmental
+mechanics,” a title, which, of course, might easily be
+transformed into that of “morphogenetic mechanics,” to
+embrace not only normal development, but restitution and
+adaptation too. We feel unable to speak of “mechanics”
+where just the contrary of mechanics, in the proper meaning
+of the word, has been proved to exist.</p>
+
+<p>Names of course are of comparatively small importance,
+but they should never be allowed to be directly misleading,
+as indeed the term “Entwickelungsmechanik” has already
+proved to be. Let us rather say, therefore, that we have
+finished with this lecture that part of our studies in biology
+which has had to deal with morphogenetic physiology or
+physiological morphogenesis.</p>
+
+<p>Once more we repeat, at this resting-point in our
+discussions, that both of our proofs of life-autonomy have
+been based upon a careful analysis of certain facts about
+the distribution of morphogenetic potencies in two classes
+of morphogenetic systems, and upon nothing else. To
+recall only one point, we have not said that regeneration,<span class="pagenum" title="242"><a name="Page_242" id="Page_242"></a></span>
+merely because it is a kind of restitution of the disturbed
+whole, compels us to admit that biological events happen
+in a specific and elemental manner, but, indeed, regeneration
+<em>does</em> prove vitalism, because it is founded upon the existence
+of certain complex-equipotential systems, the analysis of
+the genesis of which leads to the understanding of life-autonomy.
+This distinction, in fact, is of the greatest
+logical importance.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="243"><a name="Page_243" id="Page_243"></a></span></p>
+
+
+
+
+<h2>PART II</h2>
+
+<h2>SYSTEMATICS AND HISTORY</h2>
+
+<h3><i>A.</i> THE PRINCIPLES OF SYSTEMATICS</h3>
+
+
+<p class="tac pt12b02em"><span class="smcap">Rational Systematics</span></p>
+
+<p>All systematics which deserves the predicate “rational” is
+founded upon a concept or upon a proposition, by the aid of
+which a totality of specific diversities may be understood.
+That is to say: every system claiming to be rational gives
+us a clue by which we are able to apprehend either
+that there cannot exist more than a certain number of
+diversities of a certain nature, or that there can be an
+indefinite number of them which follow a certain law with
+regard to the character of their differences.</p>
+
+<p>Solid geometry, which states that only five regular
+bodies are possible, and points out the geometrical nature of
+these bodies, is a model of what a rational system should be.
+The theory of conic sections is another. Take the general
+equation of the second degree with two unknowns, and
+study all the possible forms it can assume by a variation
+of its constants, and you will understand that only four
+different types of conic sections are possible&mdash;the circle, the
+ellipse, the hyperbola, and the parabola.</p>
+
+<p><span class="pagenum" title="244"><a name="Page_244" id="Page_244"></a></span></p>
+
+<p>In physics and chemistry no perfect rational systems
+have been established hitherto, but there are many systems
+approaching the ideal type in different departments of these
+sciences. The chemical type of the monohydric saturated
+alcohols, for instance, is given by the formula C<sub>n</sub>H<sub>2n+1</sub>OH,
+and in this formula we not only have an expression of the
+law of composition which all possible alcohols are to follow,&mdash;but,
+since we know empirically the law of quantitative
+relation between <i>n</i> and various physical properties, we also
+possess in our formula a general statement with respect to
+the totality of the properties of any primary alcohol that
+may be discovered or prepared in the future. But chemistry
+has still higher aims with regard to its systematics: all of
+you know that the so-called “periodic law of the elements”
+was the first step towards a principle that may some day
+give account of the relation of all the physical and chemical
+properties of any so-called element with its most important
+constant, the atomic weight, and it seems to be reserved for
+the present time to form a real fundamental system of the
+“elements” on the basis of the periodic law by the aid of
+the theory of electrons. Such a fundamental system of the
+elements would teach us that there can only be so many
+elements and no more, and only of such a kind. In
+crystallography a similar end has been reached already by
+means of certain hypothetic assumptions, and systematics
+has here accounted for the limited number and fixed character
+of the possible forms of crystalline symmetry.</p>
+
+<p>It is not difficult to understand the general logical type
+of all rational systems, and logic indeed can discover it without
+appealing to concrete sciences or to geometry. Rational
+systematics is always possible whenever there exists any<span class="pagenum" title="245"><a name="Page_245" id="Page_245"></a></span>
+fundamental concept or proposition which carries with it a
+principle of division; or to express it somewhat differently,
+which would lead to contradictions, if division were to be
+tried in any but one particular manner. The so-called
+“genus,” as will easily be perceived, then embraces all its
+“species” in such a manner that all peculiarities of the
+species are represented already in properties of the genus,
+only in a more general form, in a form which is still unspecified.
+The genus is both richer in content and richer in
+extent than are the species, though it must be added that
+its richness in content is, as it were, only latent: but it
+may come into actuality by itself and without any help
+from without.</p>
+
+<p>We are dealing here with some of the most remarkable
+properties of the so-called synthetic judgments <i lang="la" xml:lang="la">a priori</i> in
+the sense of Kant, and, indeed, it seems that rational
+systematics will only be possible where some concept of the
+categorical class or some proposition based upon such
+concept lies at the root of the matter or at least is connected
+with it in some way. In fact, all rational systems with
+regard to the relations of symmetry in natural bodies deal
+ultimately with space; or better, all systems in such fields
+are able to become rational only if they happen to turn into
+questions of spatial symmetry.</p>
+
+<p>All other genera and species, whether of natural bodies
+or of facts, can be related only on the basis of empirical
+abstraction, <i>i.e.</i> can never attain rationality: here, indeed,
+the genus is richer in extent and poorer in content than
+are the species. The genus is transformed into the species,
+not by any inherent development of latent properties, but
+by a mere process of addition of characteristic points. It is<span class="pagenum" title="246"><a name="Page_246" id="Page_246"></a></span>
+impossible to deduce the number or law or specifications of
+the species from the genus. Mere “classification,” if we
+may reserve the honorable name of systematics for the
+rational type, is possible here, a mere statement in the form
+of a catalogue, useful for orientation but for nothing more.
+We may classify all varieties of hats or of tables in the
+same way.</p>
+
+
+<p class="tac pt12b02em"><span class="smcap">Biological Systematics</span></p>
+
+<p>At this point we return from our logical excursion
+to our proper subject of biology; for I am sorry to
+say biological systematics is at present of our second
+type of systematics throughout: it is classification pure
+and simple. We have a catalogue in our hands, but
+nothing more.</p>
+
+<p>Such a statement of fact conveys not a particle of
+censure, casts not the least reflection on the gifted men
+who created the classification of animals or plants. It is
+absolutely necessary to have such a catalogue, and indeed the
+catalogue of the organisms can be said to have been
+improved enormously during the advance of empirical and
+descriptive biological science. Any classification improves
+as it becomes more “natural,” as the different possible
+schemes of arrangement, the different reasons of division,
+agree better and better in their results; and, in fact, there
+has been a great advance of organic classification in this
+direction. The “natural” system has reached such perfection,
+that what is related from one point of view seems
+nearly related also from almost all points of view which are
+applicable, at least from those which touch the most<span class="pagenum" title="247"><a name="Page_247" id="Page_247"></a></span>
+important characteristics. There has been a real weighing
+of all the possible reasons of division, and that has led to a
+result which seems to be to some extent final.</p>
+
+<p>But, nevertheless, we do not understand the <i lang="fr" xml:lang="fr">raison
+d’être</i> of the system of organisms; we are not at all able
+to say that there must be these classes or orders or
+families and no others, and that they must be such as
+they are.</p>
+
+<p>Shall we ever be able to understand that? Or will
+organic systematics always remain empirical classification?
+We cannot answer this question. If we could, indeed, we
+should have what we desire! As simple relations of space
+are certainly not the central point of any problematic
+rational organic systematics even of the future, the question
+arises, whether there could be found any principle of
+another type in the realm of synthetic <i lang="la" xml:lang="la">a priori</i> judgments
+which could allow an inherent sort of evolution of latent
+diversities, as do all judgments about spatial symmetry. At
+the end of the second course of these lectures, which is to be
+delivered next summer, we shall be able to say a few more
+words about this important point.</p>
+
+<p>The concept of what is called “a type,” due almost
+wholly to Cuvier and Goethe, is the most important of
+all that classification has given to us. Hardly second in
+importance is the discovery of the “correlation of parts,” as
+a sort of connection which has the character of necessity
+without being immediately based upon causality. Rádl
+seems to be the only modern author who has laid some
+stress on this topic. The harmony which we have discovered
+in development is also part of this correlation.
+When, later on, we come to discuss analytically our well<span class="pagenum" title="248"><a name="Page_248" id="Page_248"></a></span>
+established entelechy as the ultimate basis of individual
+organisation, we shall be able to gain more satisfactory
+ideas with respect to the meaning of the non-causal but
+necessary connection, embraced in the concepts of type and
+of correlation of parts.</p>
+
+<p>The type is a sort of irreducible arrangement of
+different parts; the correlation deals with the degree and
+the quality of what may be called the actual make of the
+parts, in relation to one another: all ruminants, for
+instance, are cloven-footed, the so-called dental formulae
+are characteristic of whole groups of mammals. Of course
+all such statements are empirical and have their limits:
+but it is important that they are <span class="nowrap">possible.<a name="FNanchor_142_142" id="FNanchor_142_142"></a><a href="#Footnote_142_142" class="fnanchor">142</a></span></p>
+
+<p>It has been the chief result of comparative embryology
+to show that the type as such is more clearly expressed in
+developmental stages than it is in the adults, and that therefore
+the embryological stages of different groups may be very
+much more similar to each other than are the adults:
+that is the truth contained in the so-called “biogenetisches
+Grundgesetz.” But the specific differences of the species
+are not wanting in any case of ontogeny, in spite of such
+similarities in different groups during development.</p>
+
+<p>We have applied the name “systematics” or, if rationality
+is excluded, “classification” to all that part of a science
+which deals with diversities instead of generalities: in such
+a wide meaning systematics, of course, is not to be confused
+with that which is commonly called so in biology, and
+which describes only the exterior differences of form.<span class="pagenum" title="249"><a name="Page_249" id="Page_249"></a></span>
+Our systematics is one of the two chief parts of biology;
+what are called comparative anatomy and comparative
+embryology are its methods. For it must be well understood
+that these branches of research are only methods
+and are not sciences by themselves.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="250"><a name="Page_250" id="Page_250"></a></span></p>
+
+
+
+
+<h3><i>B.</i> THE THEORY OF DESCENT</h3>
+
+
+<h4 class="fs120">1. <span class="smcap">Generalities</span></h4>
+
+<p>It is most generally conceded at the present time that
+the actually existing state of all organisms whatsoever is
+the result of their history. What does that mean? What
+are the foundations upon which the assumption rests?
+What is the relation of systematics to history? In raising
+such questions and considerations we are treading the
+ground sacred to the theory of descent.</p>
+
+<p>I well know that you prefer the name “theory of
+evolution” for what I am speaking of: but it may be
+misleading in various respects. We already know that quite
+a determinate meaning has been given to the word “evolutio”
+as applied to individual morphogenesis, “evolutio”
+being here opposed to “epigenesis.” Now there would be
+nothing against the use of the word evolution in a wider
+sense&mdash;indeed it is often applied nowadays to denote
+the fact that a something is actually “evolved” in
+embryology&mdash;if only our entelechy had taken the place of
+the machine of the mechanists. But that is the very
+point: there must be a real “evolving” of a something,
+in order that the word evolution may be justified verbally:
+and that is not the case in so-called phylogeny. At least<span class="pagenum" title="251"><a name="Page_251" id="Page_251"></a></span>
+we know nothing of an evolutionary character in the
+problematic pedigree of the organisms, as we shall see more
+fully hereafter. The term “theory of descent” is therefore
+less open to objection than is the usual English term.
+The word transformism, as used by the French, would also
+be a very good title.</p>
+
+<p>The theory of descent is the hypothetic statement that
+the organisms are really allied by blood among each other,
+in spite of their <span class="nowrap">diversities.<a name="FNanchor_143_143" id="FNanchor_143_143"></a><a href="#Footnote_143_143" class="fnanchor">143</a></span> The question about their
+so-called monophyletic or polyphyletic origin is of secondary
+importance compared with the statement of relationship in
+general.</p>
+
+<p>There are two different groups of facts which have
+suggested the idea of transformism: none of these facts can
+be said to be conclusive, but there certainly is a great
+amount of probability in the whole if taken together.</p>
+
+<p>The first group of evidences which lead to the hypothesis
+of the real relationship of organisms consists of facts relating
+to the geographical distribution of animals and plants and
+to palæontology. As to geography, it seems to me that the
+results of the floral and faunal study of groups of islands<span class="pagenum" title="252"><a name="Page_252" id="Page_252"></a></span>
+are to be mentioned in the first place. If, indeed, on each
+of the different islands, <i>A</i> <i>B</i> <i>C</i> and <i>D</i>, forming a group,
+the species of a certain genus of animals or plants are
+different in a certain respect, and show differences also
+compared with the species living on the neighbouring
+continent, of which there is geological evidence that the
+islands once formed a part, whilst there is no change in
+the species on the continent itself for very wide areas, then,
+no doubt, the hypothesis that all these differing species
+once had a common origin, the hypothesis that there is a
+certain community among them all, will serve to elucidate
+in some way what would seem to be very abstruse without
+it. And the same is true of the facts of palaeontology.
+In the geological strata, forming a continuous series, you
+find a set of animals, always typical and specific for every
+single stratigraphical horizon, but forming a series just as
+do those horizons. Would not the whole aspect of these
+facts lose very much of its peculiarity if you were to
+introduce the hypothesis that the animals changed with
+the strata? The continuity of life, at least, would be
+guaranteed by such an assumption.</p>
+
+<p>The geographical and geological evidences in favour of
+the theory of descent are facts taken from sciences
+which are not biology proper; they are not facts of the
+living but only facts about the living. That is not quite
+without logical importance, for it shows that not biology
+alone has led to the transformism hypothesis. Were it otherwise,
+transformism might be said to be a mere hypothesis
+<i lang="la" xml:lang="la">ad hoc</i>; but now this proves to be not the case, though
+we are far from pretending that transformism might be
+regarded as resting upon a real <i lang="la" xml:lang="la">causa vera</i>.</p>
+
+<p><span class="pagenum" title="253"><a name="Page_253" id="Page_253"></a></span></p>
+
+<p>But let us study the second group of facts which
+support the theory of descent. It is a group of evidences
+supplied by biology itself that we meet here, there being
+indeed some features in biology which can be said to gain
+some light, some sort of elucidation, if the theory of descent
+is accepted. Of course, these facts can only be such as
+relate to specific diversities, and indeed are facts of
+systematics; in other words, there exists something in
+the very nature of the system of organisms that renders
+transformism probable. The system of animals and plants
+is based upon a principle which might be called the
+principle of <em>similarities and diversities by gradation</em>; its
+categories are not uniform but different in degree and
+importance, and there are different kinds of such differences.
+No doubt, some light would be shed upon this character
+of the system, if we were allowed to assume that the relation
+between similarities and diversities, which is gradual,
+corresponded to a blood-relationship, which is gradual also.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE COVERT PRESUMPTION OF ALL THEORIES OF DESCENT</span></p>
+
+<p>We have used very neutral and somewhat figurative
+words, in order to show what might be called the logical
+value of the theory of descent, in order to signify its
+value with respect to so-called “explanation.” We have
+spoken of the “light” or the “elucidation” which it brings,
+of the “peculiarity of aspect” which is destroyed by it.
+We have used this terminology intentionally, for it is very
+important to understand that a specific though hidden
+addition is made almost unconsciously to the mere statement
+of the hypothesis of descent as such, whenever this<span class="pagenum" title="254"><a name="Page_254" id="Page_254"></a></span>
+hypothesis is advocated in order to bring light or elucidation
+into any field of systematic facts. And this additional
+hypothesis indeed must be made from the very beginning,
+quite irrespective of the more detailed problems of the law
+of transformism, in order that <em>any</em> sort of so-called explanation
+by means of the theory of descent may be possible
+at all. Whenever the theory that, in spite of their
+diversities, the organisms are related by blood, is to be really
+useful for explanation, it must necessarily be assumed in
+every case that the steps of change, which have led the
+specific form <i>A</i> to become the specific form <i>B</i>, have been
+such as only to change <em>in part</em> that original form <i>A</i>.
+That is to say: the similarities between <i>A</i> and <i>B</i> must
+never have become overshadowed by their diversities.</p>
+
+<p>Only on this assumption, which indeed is a newly
+formed additional subsidiary hypothesis, joined to the
+original hypothesis of descent in general&mdash;a hypothesis
+regarding the very nature of transformism&mdash;only on this
+almost hidden assumption is it possible to speak of any
+sort of “explanation” which might be offered by the
+theory of transformism to the facts of geography, geology,
+and biological systematics. Later on we shall study more
+deeply the logical nature of this “explanation”; at present
+it must be enough to understand this term in its quasi-popular
+meaning.</p>
+
+<p>What is explained by the hypothesis of descent&mdash;including
+the additional hypothesis, that there always is a
+prevalence of the similarities during transformism&mdash;is the
+fact that in palaeontology, in the groups of island and
+continent faunae and florae taken as a whole, as well as in
+the single categories of the system, the similarities exceed<span class="pagenum" title="255"><a name="Page_255" id="Page_255"></a></span>
+the diversities. The <em>similarities</em> now are “explained”;
+that is to say, they are understood as resting on but one
+principle: the similarities are understood as being due to
+<span class="nowrap">inheritance;<a name="FNanchor_144_144" id="FNanchor_144_144"></a><a href="#Footnote_144_144" class="fnanchor">144</a></span> and now we have but one problem instead
+of an indefinite number. For this reason Wigand granted
+that the theory of descent affords what he calls a numerical
+reduction of problems.</p>
+
+<p>Understanding then what is explained by the theory
+of descent with its necessary appendix, we also understand
+at once what is <em>not</em> elucidated by it: the diversities of the
+organism remain as unintelligible as they always were,
+even if we know that inheritance is responsible for
+what is similar or equal. Now there can be no doubt
+that the diversities are the more important point in
+systematics; if there were only similarities there would
+be no problem of systematics, for there would be no system.
+Let us be glad that there are similarities in the diversities,
+and that these similarities have been explained in some
+way; but let us never forget what is still awaiting its
+explanation. Unfortunately it has been forgotten far too
+often.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE SMALL VALUE OF PURE PHYLOGENY</span></p>
+
+<p>And so we are led to the negative side of the theory
+of transformism, after having discussed its positive half.
+The theory of descent as such, without a real knowledge<span class="pagenum" title="256"><a name="Page_256" id="Page_256"></a></span>
+of the factors which are concerned in transformism, or of
+the law of transformism, in other terms, leaves the problem
+of systematics practically where it was, and adds really
+nothing to its solution. That may seem very deplorable,
+but it is true.</p>
+
+<p>Imagine so-called historical geology, without any knowledge
+of the physical and chemical factors which are
+concerned in it: what would you have except a series of
+facts absolutely unintelligible to you? Or suppose that
+some one stated the cosmogenetic theory of Kant and Laplace
+without there being any science of mechanics: what would
+the theory mean to you? Or suppose that the whole
+history of mankind was revealed to you, but that you
+had absolutely no knowledge of psychology: what would
+you have but facts and facts and facts again, with not a
+morsel of real explanation?</p>
+
+<p>But such is the condition in which so-called phylogeny
+stands. If it is based only on the pure theory of transformism,
+there is nothing explained at all. It was for this
+reason that the philosopher Liebmann complained of phylogeny
+that it furnishes nothing but a “gallery of ancestors.”
+And this gallery of ancestors set up in phylogeny is not
+even certain; on the contrary, it is absolutely uncertain,
+and very far from being a fact. For there is no sound
+and rational principle underlying phylogeny; there is
+mere fantastic speculation. How could it be otherwise
+where all is based upon suppositions which themselves
+have no leading principle at present? I should not like
+to be misunderstood in my polemics against phylogeny.
+I fully grant you that it may be possible in a few cases
+to find out the phylogenetic history of smaller groups with<span class="pagenum" title="257"><a name="Page_257" id="Page_257"></a></span>
+some probability, if there is some palaeontological evidence
+in support of pure comparative anatomy; and I also do
+not hesitate to allow that such a statement would be of
+a certain value with regard to a future discovery of the
+“laws” of descent, especially if taken together with the
+few facts known about mutations. But it is quite another
+thing with phylogeny on the larger scale. Far more
+eloquent than any amount of polemics is the fact that
+vertebrates, for instance, have already been “proved” to
+be descended from, firstly, the amphioxus; secondly, the
+annelids; thirdly, the <i class="biological-name">Sagitta</i> type of worms; fourthly,
+from spiders; fifthly, from <i class="biological-name">Limulus</i>, a group of crayfishes;
+and sixthly, from echinoderm larvae. That is the extent
+of my acquaintance with the literature, with which I do not
+pretend to be specially familiar. Emil du Bois-Reymond
+said once that phylogeny of this sort is of about as much
+scientific value as are the pedigrees of the heroes of Homer,
+and I think we may fully endorse his opinion on this
+point.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HISTORY AND SYSTEMATICS</span></p>
+
+<p>A few words should be devoted to the relations between
+history and systematics in biology. Is there no contradiction
+between historical development and a true and
+rational system which, we conceded, might exist some
+day in biological sciences, even though it does not at
+present? By no means. A totality of diversities is
+regarded from quite different points of view if taken as
+the material of a system, and if considered as realised in
+time. We have said that chemistry has come very near
+to proper rational systematics, at least in some of its<span class="pagenum" title="258"><a name="Page_258" id="Page_258"></a></span>
+special fields; but the compounds it deals with at the
+same time may be said to have originated historically also,
+though not, of course, by a process of propagation. It is
+evident at once that the geological conditions of very early
+times prohibited the existence of certain chemical compounds,
+both organic and inorganic, which are known at
+present. None the less these compounds occupy their
+proper place in the system. And there may be many
+substances theoretically known to chemical systematics
+which have never yet been produced, on account of the
+impossibility of arranging for their proper conditions of
+appearance, and nevertheless they must be said to “exist.”
+“Existence,” as understood in systematics, is independent
+of special space and of special time, as is the existence of
+the laws of nature: we may speak of a Platonic kind of
+existence here. Of course it does not contradict this sort
+of ideal existence if reality proper is added to it.</p>
+
+<p>Thus the problem of systematics remains, no matter
+whether the theory of descent be right or wrong. There
+always remains the question about the totality of diversities
+in life: whether it may be understood by a general principle,
+and of what kind that principle would be. As, in
+fact, it is most probably by history, by descent, that
+organic systematics is brought about, it of course most probably
+will happen some day that the analysis of the causal
+factors concerned in the history will serve to discover the
+principle of systematics also.</p>
+
+<p>Let us now glance at the different kinds of hypotheses
+which have been established in order to explain how the
+descent of the organisms might have been possible. We
+have seen that the theory of transformism alone is not<span class="pagenum" title="259"><a name="Page_259" id="Page_259"></a></span>
+worth very much as a whole, unless at least a hypothetical
+picture can be formed of the nature of the transforming
+factors: it is by some such reasoning that almost every
+author who has defended the theory of descent in its
+universality tries to account for the manner in which
+organisms have acquired their present diversities.</p>
+
+<p><span class="pagenum" title="260"><a name="Page_260" id="Page_260"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">The Principles of Darwinism</span></h4>
+
+<p>There is no need in our times and particularly in this
+country, to explain in a full manner the theory known
+under the name of Darwinism. All of you know this
+theory, at least in its outlines, and so we may enter at once
+upon its analytic discussion. A few words only I beg you
+to allow me as to the name of “Darwinism” itself.
+Strange to say, Darwinism, and the opinion of Charles
+Darwin about the descent of organisms, are two different
+things. Darwin, the very type of a man devoted to science
+alone and not to personal interests,&mdash;Darwin was anything
+but dogmatic, and yet Darwinism is dogmatism in one of
+its purest forms. Darwin, for instance, gave the greatest
+latitude to the nature of the variations which form the
+battleground of the struggle for existence and natural
+selection; and he made great allowances for other causal
+combinations also, which may come into account besides
+the indirect factors of transformism. He was Lamarckian
+to a very far-reaching extent. And he had no definite
+opinion about the origin and the most intimate nature of
+life in general. These may seem to be defects but really
+are advantages of his theory. He left open the question
+which he could not answer, and, in fact, he may be said
+to be a good illustration of what Lessing says, that it is<span class="pagenum" title="261"><a name="Page_261" id="Page_261"></a></span>
+not the possession of truth but the searching after it, that
+gives happiness to man. It was but an outcome of this
+mental condition that Darwin’s polemics never left the
+path of true scientific discussions, that he never in all
+his life abused any one who found reason to combat his
+hypotheses, and that he never turned a logical problem
+into a question of morality.</p>
+
+<p>How different is this from what many of Darwin’s
+followers have made out of his doctrines, especially in
+Germany; how far is “Darwinism” removed from Darwin’s
+own teaching and character!</p>
+
+<p>It is to Darwinism of the <em>dogmatic</em> kind, however, that
+our next discussions are to relate, for, thanks to its
+dogmatism, it has the advantage of allowing the very sharp
+formulation of a few causal factors, which <i lang="la" xml:lang="la">a priori</i> might
+be thought to be concerned in organic transformism, though
+we are bound to say that a really searching analysis of
+these factors ought to have led to their rejection from the
+very beginning.</p>
+
+<p>The logical structure of dogmatic Darwinism reveals
+two different parts, which have nothing at all to do with
+one another.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">NATURAL SELECTION</span></p>
+
+<p>We shall first study that part of it which is known
+under the title of natural selection, irrespective of the
+nature of the causes of primary differences, or, in other
+words, the nature of variability. This part may be said
+to belong to Darwin’s personal teachings and not only to
+“Darwinism.” The offspring of a certain number of adults
+show differences compared with each other; there are more<span class="pagenum" title="262"><a name="Page_262" id="Page_262"></a></span>
+individuals in the offspring than can grow up under the
+given conditions, therefore there will be a struggle for
+existence amongst them, which only the fittest will survive;
+these survivors may be said to have been “selected” by
+natural means.</p>
+
+<p>It must be certain from the very beginning of analysis
+that natural selection, as defined here, can only eliminate
+what cannot survive, what cannot stand the environment
+in the broadest sense, but that natural selection never
+is able to create diversities. It always acts negatively
+only, never positively. And therefore it can “explain”&mdash;if
+you will allow me to make use of this ambiguous word&mdash;it
+can “explain” only why certain types of organic specifications,
+imaginable <i lang="la" xml:lang="la">a priori</i>, do <em>not</em> actually exist, but it never
+explains at all the existence of the specifications of animal
+and vegetable forms that are actually found. In speaking
+of an “explanation” of the origin of the living specific forms
+by natural selection one therefore confuses the sufficient
+reason for the non-existence of what there is not, with the
+sufficient reason for the existence of what there is. To say
+that a man has explained some organic character by
+natural selection is, in the words of Nägeli, the same as if
+some one who is asked the question, “Why is this tree
+covered with these leaves,” were to answer “Because the
+gardener did not cut them away.” Of course that would
+explain why there are no more leaves than those actually
+there, but it never would account for the existence and
+nature of the existing leaves as such. Or do we understand
+in the least why there are white bears in the Polar Regions
+if we are told that bears of other colours could not survive?</p>
+
+<p>In denying any real explanatory value to the concept<span class="pagenum" title="263"><a name="Page_263" id="Page_263"></a></span>
+of natural selection I am far from denying the action of
+natural selection. On the contrary, natural selection, to
+some degree, is <em>self-evident</em>; at least as far as it simply
+states that what is incompatible with permanent existence
+cannot exist permanently, it being granted that the
+originating of organic individuals is not in itself a
+guarantee of permanency. Chemical compounds, indeed,
+which decompose very rapidly under the conditions existing
+at the time when they originated may also be said
+to have been eliminated by “natural selection.” It is
+another question, of course, whether in fact all eliminations
+among organic diversities are exclusively due to the action
+of natural selection in the proper Darwinian sense. It
+has been pointed out already by several critics of
+Darwinism and most clearly by Gustav Wolff, that there
+are many cases in which an advantage with regard to
+situation will greatly outweigh any advantage in organisation
+or physiology. In a railway accident, for instance, the
+passengers that survive are not those who have the strongest
+bones, but those who occupied the best seats; and the
+eliminating effect of epidemics is determined at least as
+much by localities, <i>e.g.</i> special houses or special streets, as
+by the degree of immunity. But, certainly, natural selection
+is a <i lang="la" xml:lang="la">causa vera</i> in many other cases.</p>
+
+<p>We now may sum up our discussion of the first half
+of Darwinism. Natural selection is a negative, an eliminating
+factor in transformism; its action is self-evident to
+a very large degree, for it simply states that things do
+not exist if their continuance under the given conditions
+is impossible. To consider natural selection as a positive
+factor in descent would be to confound the sufficient reason<span class="pagenum" title="264"><a name="Page_264" id="Page_264"></a></span>
+for the non-existence of what is not, with the sufficient
+reason of what is.</p>
+
+<p>Natural selection has a certain important logical bearing
+on systematics, as a science of the future, which has scarcely
+ever been alluded to. Systematics of course has to deal
+with the totality of the possible, not only of the actual
+diversities; it therefore must remember that more forms
+may be possible than are actual, the word “possible”
+having reference in this connection to originating, not to
+surviving. Moreover, systematics is concerned not only
+with what has been eliminated by selection, but also with
+all that might have originated from the eliminated types.
+By such reasoning natural selection gains a very important
+aspect&mdash;but a logical aspect only.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">FLUCTUATING VARIATION THE ALLEGED CAUSE OF ORGANIC
+DIVERSITY</span></p>
+
+<p>The second doctrine of dogmatic Darwinism states that
+all the given diversities among the organisms that natural
+selection has to work upon are offered to natural selection
+by so-called fluctuating variation; that is, by variation as
+studied by means of statistics. This sort of variation,
+indeed, is maintained to be indefinite in direction and
+amount, at least by the most conservative Darwinians; it
+has occasionally been called a real differential; in any case
+it is looked upon as being throughout contingent with
+regard to some unity or totality; which, of course, is not to
+mean that it has not had a sufficient reason for occurring.</p>
+
+<p>It could hardly be said to be beyond the realm of
+possibility that such differences among organic species as<span class="pagenum" title="265"><a name="Page_265" id="Page_265"></a></span>
+only relate to degree or quantity and perhaps to numerical
+conditions also, might have been “selected” out of given
+contingent variations, if but one postulate could be regarded
+as fulfilled. This postulate may appropriately be stated
+as the fixation of new averages of variation by inheritance.
+Let the average value of a variation, with regard to a
+given property of a given species be <i>n</i> and let the value
+<i>n</i> + <i>m</i>&mdash;<i>m</i> being variable&mdash;which is represented in fewer
+individuals of course than is <i>n</i>, be such as to offer
+advantages in the struggle for existence; then the
+individuals marked by <i>n</i> + <i>m</i> will have the greater chance
+of surviving. Our postulate now states that, in order that
+a permanent increase of the average value of the variation
+in question may be reached, <i>n</i> + <i>m</i> in any of its variable
+forms must be able to become the average value of the
+second generation, as <i>n</i> was the average value of the first.
+Out of the second generation again it would be the few
+individuals marked by <i>n</i> + <i>m</i> + <i>o</i>, which would be selected;
+<i>n</i> + <i>m</i> + <i>o</i> would be the new average; afterwards <i>n</i> + <i>m</i> + <i>o</i> + <i>p</i>
+would be selected, would become the new average, and
+so on. A black variety for instance might be selected by
+such a series of processes out of a grey-coloured one without
+difficulty.</p>
+
+<p>But our postulate is not beyond all doubt: certain
+experiments, at least, which have been carried out about
+the summation of variations of the true fluctuating
+type by any kind of selection seem to show that there
+may be a real progress for a few generations, but that
+this progress is always followed by a reversion. Of course
+our experience is by no means complete on this subject,
+and, indeed, it may be shown in the future that positive<span class="pagenum" title="266"><a name="Page_266" id="Page_266"></a></span>
+transforming effects of fluctuating variability, in connection
+with selective principles, are possible in the case of new
+quantitative differences (in the widest sense), but we are
+not entitled to say so at present.</p>
+
+<p>And this is the only condition on which we can give
+credit to the second doctrine of dogmatic Darwinism. Its
+second principle, indeed, proves to be absolutely inadequate
+to explain the origin of any other kind of specific properties
+whatever.</p>
+
+<p>I cannot enter here into the whole subject of Darwinian
+<span class="nowrap">criticism.<a name="FNanchor_145_145" id="FNanchor_145_145"></a><a href="#Footnote_145_145" class="fnanchor">145</a></span> Our aims are of a positive character, they
+desiderate construction and only use destruction where it
+is not to be avoided. So I shall only mention that
+dogmatic Darwinism has been found to be unable to
+explain every kind of mutual adaptations, <i>e.g.</i> those existing
+between plants and insects; that it can never account
+for the origin of those properties that are indifferent to the
+life of their bearer, being mere features of organisation as
+an arrangement of parts; that it fails in the face of all
+portions of organisation which are composed of many
+different parts&mdash;like the eye&mdash;and nevertheless are
+functional units in any passive or active way; and that, last
+not least, it has been found to be quite inadequate to
+explain the first origin of all newly formed constituents of
+organisation even if they are not indifferent: for how
+could any rudiment of an organ, which is not functioning
+at all, not only be useful to its bearer, but be useful in
+such a degree as to decide about life or death?</p>
+<p><span class="pagenum" title="267"><a name="Page_267" id="Page_267"></a></span></p>
+<p>It is only for one special feature that I should like to
+show, by a more full analysis, that dogmatic Darwinism
+does not satisfy the requirements of the case. The special
+strength of Darwinism is said to lie in its explaining everything
+that is useful in and for organisms; the competitive
+factor it introduces does indeed seem to secure at least a
+relative sort of adaptedness between the organism and its
+needs. But in spite of that, we shall now see that
+Darwinism fails absolutely to explain those most intimate
+organic phenomena which may be said to be the most
+useful of all.</p>
+
+<p>Darwinism in its dogmatic form is not able to explain
+the origin of any sort of organic restitution; it is altogether
+impossible to account for the restitutive power of organisms
+by the simple means of fluctuating variation and natural
+selection in the struggle for existence. Here we have the
+logical <i lang="la" xml:lang="la">experimentum crucis</i> of Darwinism.</p>
+
+<p>Let us try to study in the Darwinian style the origin
+of the regenerative faculty, as shown in the restitution of
+the leg of a newt. All individuals of a given species of the
+newt, say <i class="biological-name">Triton taeniatus</i>, are endowed with this faculty;
+all of them therefore must have originated from ancestors
+which acquired it at some time or other. But this
+necessary supposition implies that all of these ancestors
+must have lost their legs in some way, and not only one,
+but all four of them, as they could not have acquired the
+restitutive faculty otherwise. We are thus met at the very
+beginning of our argument by what must be called a
+real absurdity, which is hardly lessened by the assumption
+that regeneration was acquired not by all four legs together,
+but by one after the other. But it is absolutely inevit<span class="pagenum" title="268"><a name="Page_268" id="Page_268"></a></span>able
+to assume that <em>all</em> the ancestors of our <i class="biological-name">Triton</i> must
+have lost one leg, or more correctly, that only those of
+them survived which had lost one! Otherwise not all
+newts at the present day could possess the faculty of
+regeneration! But a second absurdity follows the first
+one; out of the ancestors of our newt, which survived the
+others by reason of having lost one of their legs, there were
+selected only those which showed at least a very small amount
+of healing of their wound. It must be granted that such a
+step in the process of selection, taken by itself, would not
+at all seem to be impossible; since healing of wounds
+protects the animals against infection. But the process
+continues. In every succeeding stage of it there must have
+survived only those individuals which formed just a little
+more of granulative tissue than did the rest: though
+<em>neither</em> they themselves <em>nor</em> the rest could use the leg,
+which indeed was not present! That is the second absurdity
+we meet in our attempt at a Darwinian explanation of the
+faculty of regeneration; but I believe the first one alone
+was sufficient.</p>
+
+<p>If we were to study the “selection” of the faculty of
+one of the isolated blastomeres of the egg of the sea-urchin
+to form a whole larva only of smaller size, the absurdities
+would increase. At the very beginning we should encounter
+the absurdity, that of all the individuals there survived
+only those which were not whole but half; for <em>all</em> sea-urchins
+are capable of the ontogenetical restitution in
+question, <em>all</em> of their ancestors therefore must have acquired
+it, and they could do that only <em>if</em> they became halved at
+first by some accident during early embryology. But we
+shall not insist any further on this instance, for it would<span class="pagenum" title="269"><a name="Page_269" id="Page_269"></a></span>
+not be fair to turn into ridicule a theory which bears the
+name of a man who is not at all responsible for its dogmatic
+form. Indeed, we are speaking against Darwinism of the
+most dogmatic form only, not against Darwin himself. He
+never analysed the phenomena of regeneration or of
+embryonic restitution&mdash;they lay in a field very unfamiliar
+to him and to his time. I venture to say that if he had
+taken them into consideration, he would have agreed with
+us in stating that his theory was not at all able to cover
+them; for he was prepared to make great concessions, to
+Lamarckism for instance, in other branches of biology, and
+he did not pretend, to know what life itself is.</p>
+
+<p>Darwin was not a decided materialist, though materialism
+has made great capital out of his doctrines, especially in
+Germany. His book, as is well known, is entitled “The
+Origin of <em>Species</em>,” that is of organic <em>diversities</em>, and he himself
+possibly might have regarded all restitution as belonging to
+the original properties of life, anterior to the originating of
+diversities. Personally he might possibly be called even a
+vitalist. Thus dogmatic “Darwinism” in fact is driven into
+all the absurdities mentioned above, whilst the “doctrine of
+Darwin” can only be said to be wrong on account of its
+failing to explain mutual adaptation, the origin of new
+organs, and some other features in organic diversities; the
+original properties of life were left unexplained by it
+intentionally.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">DARWINISM FAILS ALL ALONG THE LINE</span></p>
+
+<p>The result of our discussion then must be this: selection
+has proved to be a negative factor only, and fluctuating<span class="pagenum" title="270"><a name="Page_270" id="Page_270"></a></span>
+variation as the only way in which new properties of the
+organisms might have arisen has proved to fail in the most
+marked manner, except perhaps for a few merely quantitative
+instances. Such a result betokens the complete collapse of
+dogmatic Darwinism as a general theory of descent: the
+most typical features of all organisms remain as unexplained
+as ever.</p>
+
+<p>What then shall we put in the place of pure Darwinism?
+Let us first try a method of explanation which was also
+adopted occasionally by Darwin himself: let us study that
+form of transformation theories which is commonly known
+under the title of Lamarckism.</p>
+
+<p><span class="pagenum" title="271"><a name="Page_271" id="Page_271"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The Principles of Lamarckism.</span></h4>
+
+<p>As the word “Darwinism” does not signify the proper
+theoretical system of Charles Darwin, so Lamarckism as
+commonly understood nowadays is a good deal removed
+from the original views of Jean Baptiste Lamarck.
+Lamarckism is generally regarded as reducing all organic
+diversities to differences in the needs of individual life, but
+Lamarck himself, as must be emphasised from the very
+beginning, did not at all maintain the opinion that the
+great characteristics of the types were only due to such
+accidental factors. He supposed a sort of law of organisation
+to be at the root of systematics, as developed in history,
+and the needs of life were only responsible, according to
+him, for splitting the given types of organisation into
+their ultimate branches. Thus Lamarck, to a great extent
+at any rate, belongs to a group of authors that we shall
+have to study afterwards: authors who regard an unknown
+law of phylogenetic development as the real basis of
+transformism. Modern so-called Neo-Lamarckism, on the
+other hand, has indeed conceded the principle of needs to
+be the sole principle of transformism. Let us then study
+Lamarckism in its dogmatic modern form.</p>
+
+<p><span class="pagenum" title="272"><a name="Page_272" id="Page_272"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">ADAPTATION AS THE STARTING-POINT</span></p>
+
+<p>All facts of morphological adaptations&mdash;facts which we
+have analysed already from a different point of view, as being
+among the most typical phenomena of organic regulation&mdash;form
+the starting-point of this theory, and it must be
+granted that they form a very solid foundation, for they
+are facts. The theory only has to enlarge hypothetically
+the realm of these facts, or rather the realm of the law
+that governs them. Indeed, it is assumed by Lamarckism
+that the organism is endowed with the faculty of responding
+to <em>any</em> change of the environment which may change its
+function by a morphologically expressed alteration of its
+functional state and form, which is adapted to the state of
+conditions imposed from without. Of course, as stated in
+this most general form, the assumption is not true, but it is
+true within certain limits, as we know; and there seems to
+be no reason why we should not believe that there are many
+more cases of adaptation than we actually know at present,
+or that, in former phylogenetic times, the organisms were
+more capable of active adaptation than they are now. So
+to a certain extent, at least, Lamarckism can be said to
+rest upon a <i lang="la" xml:lang="la">causa vera</i>.</p>
+
+<p>It is important to notice that this <i lang="la" xml:lang="la">causa vera</i> would
+imply vitalistic causality when taken in the wide meaning
+which Lamarckism allows to it: indeed, the power of active
+adaptation to indefinite changes would imply a sort of
+causal connection that is nowhere known except in the
+organism. Lamarck himself is not very clear about this
+point, he seems to be afraid of certain types of uncritical
+vitalism in vogue in his days; but modern writers have<span class="pagenum" title="273"><a name="Page_273" id="Page_273"></a></span>
+most clearly seen what the logical assumptions of pure
+Lamarckism are. Next to Cope, August <span class="nowrap">Pauly<a name="FNanchor_146_146" id="FNanchor_146_146"></a><a href="#Footnote_146_146" class="fnanchor">146</a></span> may be
+said to be the most conscious representative of a sort of
+so-called psychological vitalism, which indeed Lamarckism
+as a general and all-embracing theory must have as its
+basis.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE ACTIVE STORING OF CONTINGENT VARIATIONS AS A
+HYPOTHETIC PRINCIPLE</span></p>
+
+<p>This point will come out more fully, if now we turn
+to study a certain group of principles, upon which dogmatic
+Lamarckism rests: I say principles and not facts, for there
+are no facts but only hypothetic assumptions in this group
+of statements. We do know a little about adaptations, at
+least to a certain extent, and it was only about the sphere
+of the validity of a law, which was known to be at work
+in certain cases, that hypothetical additions were made.
+In the second group of the foundations of Lamarckism we
+know absolutely nothing; accidental variations of form
+are supposed to occur, and the organism is said to possess
+the faculty of keeping and storing these variations and of
+handing them down to the next generation, if they happen
+to satisfy any of its needs.</p>
+
+<p>But these needs are not of the actual type, brought
+forth by a change of the functional state of the individual,
+as in the case of adaptations: they are of a somewhat
+mysterious nature. A glance at the theory of the origin
+of the movements which are called acts of volition in the
+human child may serve to elucidate what is meant.</p>
+
+<p><span class="pagenum" title="274"><a name="Page_274" id="Page_274"></a></span></p>
+
+<p>Acts of volition are said thus to originate in random
+movements of the new-born infant: certain of these
+accidental motions which happen to relieve some pain or
+to afford some pleasure are “remembered,” and are used
+another time quite consciously to bring forth what is liked
+or to remove what is disliked. So much for the present
+on a very difficult subject, which will occupy us next year
+at much greater length. It is clear that at least three
+fundamental phenomena are concerned in this theory of
+the origin of acts of volition: the liking and disliking, the
+keeping in mind, and the volition itself. The real act of
+volition, indeed, is always based upon a connection of all
+these factors, these factors now being connected in such a
+way that even their kind of connection may be said to be
+a fourth fundamental principle. In order that the particular
+effect may be obtained which is wanted because it is liked,
+the possible ways leading to it, which appeared among
+the random movements in the very beginning, are now
+regarded as “means” and may now be said to be “used.”
+But that is as much as to say that the “means” are judged
+with respect to their usefulness for the actual purpose, and
+therefore <em>judgment</em> is the fourth foundation of the act of
+volition.</p>
+
+<p>In fact, Pauly does not hesitate to attribute judgment,
+along with the other psychological elements, to the organisms
+whilst undergoing their transformation. There has been
+formed, for instance, by accidental variation some pigment
+which by its chemical nature brings the organism into a
+closer connection with the light of the medium; the
+individual likes that, keeps the pigment for itself and produces
+it again in the next generation; and indeed it will<span class="pagenum" title="275"><a name="Page_275" id="Page_275"></a></span>
+safeguard any sort of improvement which chance may
+effect in this primitive “eye.” Such a view is said to hold
+well with respect to the origin of every new organ. And
+this psychological argument is also said to afford the real
+explanation of adaptation proper. Adaptation also is
+regarded not as a truly primary faculty of the organism,
+but as a retention or provoking of metabolic states which
+occurred by accident originally and were then found to be
+useful; now they are reproduced either in every single
+case of individual morphogenesis, without regard to actual
+requirements, or else only in response to such: in the first
+case they are “inherited,” in the second they only occur as
+regulations. Thus the process of judgment, together with
+all the other elemental factors of psychical life concerned in
+it, has been made to account for adaptation proper. The
+whole theory has accordingly become very uniform and simple.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CRITICISM OF THE “INHERITANCE OF ACQUIRED CHARACTERS”
+ASSUMED BY LAMARCKISM</span></p>
+
+<p>In addressing ourselves to the criticism of Neo-Lamarckism
+we shall neglect as far as possible all the different psychological
+principles concerned in it&mdash;which in any case would
+need rather a great amount of epistemological sifting&mdash;and
+shall keep to those hypothetic facts which are supposed to
+be such as may be actually observed in nature.</p>
+
+<p>All of you know that the so-called inheritance of
+acquired characters lies at the root of Lamarckism; and
+from this hypothesis our critical analysis is to start,
+disregarding a larger or smaller number of psychological
+principles that are brought into the field.</p>
+
+<p><span class="pagenum" title="276"><a name="Page_276" id="Page_276"></a></span></p>
+
+<p>The name of “acquired characters” may <i lang="la" xml:lang="la">a priori</i> be
+given to three different types of phenomena: firstly, variations
+including mutations; secondly, disease or injuries;
+and thirdly, the results of the actual process of adaptation
+of every kind.</p>
+
+<p>In the first of these groups, the true problem of the
+inheritance of “acquired” characters appears only with
+certain restrictions. All variations and mutations are indeed
+“acquired” by one generation so far as the earlier generation
+did not possess them, but mutations, at least, cannot
+be said to be acquired by the actual adult personality:
+they are innate in it from its very beginning, and therefore
+may better be called <span class="nowrap">congenital.<a name="FNanchor_147_147" id="FNanchor_147_147"></a><a href="#Footnote_147_147" class="fnanchor">147</a></span> Congenital properties of
+the mutation type are, in fact, known to be inherited: their
+inheritance does not present any problem of its own, but is
+included in the changes of the hereditary condition to
+which they are due <span class="nowrap">altogether.<a name="FNanchor_148_148" id="FNanchor_148_148"></a><a href="#Footnote_148_148" class="fnanchor">148</a></span> All properties of the
+variation type, on the other hand, having been studied
+statistically, are known to be inherited, to a certain small
+extent, as we have seen already whilst studying Darwinism,
+though they are possibly always liable to reversion.
+Modern science, as we <span class="nowrap">know,<a name="FNanchor_149_149" id="FNanchor_149_149"></a><a href="#Footnote_149_149" class="fnanchor">149</a></span> regards them as due to
+changes of nutrition, in the most general meaning of the
+word. Under such a view variations might indeed be said<span class="pagenum" title="277"><a name="Page_277" id="Page_277"></a></span>
+to belong to the acquired group of organic specifications;
+their inheritance, as will be seen later on, would hardly be
+quite a pure instance of what we are searching for. In no
+case can true variations claim to be of great importance in
+problems of transformism.</p>
+
+<p>But what is known about the inheritance of those
+properties which beyond any doubt may be said to have
+originated in the adult individual as such, and of which
+lesions and adaptations proper, as shown for instance among
+amphibious plants, are instances of the two most typical
+<span class="nowrap">groups?<a name="FNanchor_150_150" id="FNanchor_150_150"></a><a href="#Footnote_150_150" class="fnanchor">150</a></span> Weismann did good service by putting an end
+to the scientific credulity which prevailed with regard to
+this subject. Weismann was led by his theory of the germ
+plasm to deny the inheritance of acquired characters of the
+typical kinds. He could not imagine how the effect of any
+agent upon the adult, be it of the merely passive or of the
+adaptive kind, could have such an influence upon the germ
+as to force it to produce the same effect in spite of the
+absence of that agent. In fact, that is what the inheritance
+of acquired characters would render necessary, and a very
+strange phenomenon it would be, no doubt. But, of course,
+taken alone, it could never be a decisive argument against
+such inheritance. I fully agree, that science is obliged to
+explain new facts by what is known already, as long as it is
+possible; but if it is no longer possible, the theory of course
+has to be changed, and not the facts. On this principle one
+would not neglect the fact of an inheritance of acquired
+properties, but on the contrary one perhaps might use it
+as a new evidence of vitalism.</p>
+<p><span class="pagenum" title="278"><a name="Page_278" id="Page_278"></a></span></p>
+<p>But are there any facts?</p>
+
+<p>At this point we come to speak about the second group
+of Weismann’s reasonings. He not only saw the difficulty
+of understanding inheritance of acquired characters on the
+principles of the science of his time, but he also criticised
+the supposed facts; and scarcely any of them stood the
+test of his criticism. Indeed, it must fairly be granted that
+not one case is known which really proves the inheritance
+of acquired characters, and that injuries certainly are never
+found to be inherited. In spite of that, I do not believe
+that we are entitled to deny the possibility of the inheritance
+of a certain group of acquired characters in an absolute
+and dogmatic manner, for there are a few facts which seem
+at least to tend in the direction of such an inheritance,
+and which seem to show that it might be discovered perhaps
+one day, if the experimental conditions were changed.</p>
+
+<p>I am not referring here to the few cases in which
+bacteria were made colourless or non-virulent by outside
+factors, or in which certain fungi were forced to permanent
+agamic reproduction by abnormal external conditions and
+were shown to retain their “acquired properties” after
+the external conditions had been restored. In these cases
+only reproduction by simple division occurred, and that
+does not imply the true problem of inheritance. Nor am I
+referring to the few cases of non-adaptive “modifications”
+found by Standfuss and Fischer, in which butterflies that
+had assumed an abnormal kind of pigmentation under the
+influence of abnormal temperature acting upon the pupa,
+were seen to form this same kind of pigmentation in the
+next generation under normal conditions of temperature.
+These cases, though important in themselves, are capable<span class="pagenum" title="279"><a name="Page_279" id="Page_279"></a></span>
+perhaps of a rather simple explanation, as in fact has been
+suggested. Some necessary means both of inheritance and
+of morphogenesis, the former being present in the propagation
+cells, may be said to have been changed or destroyed
+by heat, and therefore, what seems to be inherited after
+the change of the body only, would actually be the effect
+of a direct influence of the temperature upon the germ
+<span class="nowrap">itself.<a name="FNanchor_151_151" id="FNanchor_151_151"></a><a href="#Footnote_151_151" class="fnanchor">151</a></span> Let me be clearly understood: I do not say that
+it is so, but it may be so. What seems to me to be more
+important than everything and to have a direct bearing on
+the real discovery of the inheritance of acquired characters
+in the future, is this. In some instances plants which
+had been forced from without to undergo certain typical
+morphological adaptations, or at least changes through
+many generations, though they did not keep the acquired
+characters permanently in spite of the conditions being
+changed to another type, were yet found to lose the acquired
+adaptations not suddenly but only in the course of three or
+more generations. A certain fern, <i class="biological-name">Adiantum</i>, is known to
+assume a very typical modification of form and structure, if
+grown on serpentine; now <span class="nowrap">Sadebeck,<a name="FNanchor_152_152" id="FNanchor_152_152"></a><a href="#Footnote_152_152" class="fnanchor">152</a></span> while cultivating this
+serpentine modification of <i class="biological-name">Adiantum</i> on ordinary ground,
+found that the first generation grown in the ordinary
+conditions loses only a little of its typical serpentine
+character, and that the next generation loses a little more, so
+that it is not before the fifth generation that all the characters
+of the serpentine modification have disappeared. There are<span class="pagenum" title="280"><a name="Page_280" id="Page_280"></a></span>
+a few more cases of a similar type relating to plants grown
+in the plains or on the mountains. There also it was found
+to take time, or rather to take the course of <em>several</em> generations,
+until what was required by the new conditions was
+reached. Of course these cases are very very few compared
+with those in which a <em>sudden</em> change of the adaptive character,
+corresponding to the actual conditions, sets in; but it is
+enough that they do exist.</p>
+
+<p>Would it not be possible at least that adaptations
+which last for thousands of generations or more might
+in fact change the adaptive character into a congenital
+one? Then we not only should have inheritance of
+acquired characters, but should have a sort of explanation
+at the same time for the remarkable fact that certain
+histological structures of a very adapted kind are formed
+ontogenetically before any function exists, as is known
+to be the case with the structures in the bones of
+vertebrates, for instance. Experiments are going on at
+Paris, and perhaps in other places of scientific research
+also, which, it is hoped, will show that animals reared in
+absolute darkness for many generations will lose their
+perfectly formed eyes, and that animals from the dark with
+very rudimentary eyes will be endowed with properly
+functioning ones, after they have been reared in the light
+for generations. Such a result indeed would account for
+the many animals, of the most different groups, which live
+in dark caves and possess only rudiments of eyes: functional
+adaptation is no longer necessary, so-called atrophy by
+inactivity sets in, and the results “acquired” by it are
+<span class="nowrap">inherited.<a name="FNanchor_153_153" id="FNanchor_153_153"></a><a href="#Footnote_153_153" class="fnanchor">153</a></span></p>
+<p><span class="pagenum" title="281"><a name="Page_281" id="Page_281"></a></span></p>
+<p>But enough of possibilities. Let us be content at
+present to know at least a few real instances with regard
+to the slowness of the process of what might be said to be
+“re-adaptation” in some plants. This process shows us a
+way by which our problem may some day be solved; it
+allows us to introduce inheritance of acquired characters as
+a legitimate hypothesis at least, which not only will explain
+many of the diversities in systematics historically, but also
+can be called, though not a <i lang="la" xml:lang="la">causa vera</i>, yet certainly more
+than a mere fiction.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">OTHER PRINCIPLES WANTED</span></p>
+
+<p>We have only dealt with the probability of the
+inheritance of morphological or <span class="nowrap">physiological<a name="FNanchor_154_154" id="FNanchor_154_154"></a><a href="#Footnote_154_154" class="fnanchor">154</a></span> adaptation.
+If that could really be considered as one of the factors
+concerned in the theory of descent, many, if not all of those
+congenital diversities among organic species which are of
+the type of a true structural correspondence to their future
+functional life, might be regarded as explained, that is, as
+reduced to one and the same principle. But nothing more
+than an explanation of <em>this</em> kind of diversities is effected
+by our principle, and very much more remains to be done,
+for organic diversities not only consist in specifications and<span class="pagenum" title="282"><a name="Page_282" id="Page_282"></a></span>
+differences as to histology, but are to a much more important
+degree, differences of organisation proper, that is, of the
+arrangement of parts, in the widest sense of the <span class="nowrap">word.<a name="FNanchor_155_155" id="FNanchor_155_155"></a><a href="#Footnote_155_155" class="fnanchor">155</a></span></p>
+
+<p>Would it be possible to interpret the origin of this
+sort of systematic diversities by a reasoning similar to that
+by which we have understood, at least hypothetically,
+congenital adaptedness?</p>
+
+<p>Dogmatic Lamarckism, we know, uses two principles as
+its foundations; one of them, adaptation and its inheritance,
+we have studied with what may be called a partly positive
+result. The other is the supposed faculty of the organism
+to keep, to store, and to transfer those variations or mutations
+of a not properly adaptive sort which, though originating
+by chance, happen to satisfy some needs of the organism.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CRITICISM OF THE HYPOTHESIS OF STORING AND HANDING
+DOWN CONTINGENT VARIATIONS</span></p>
+
+<p>Strange to say, this second hypothesis of dogmatic
+Lamarckism, invented with the express purpose of defeating
+Darwinism and taking the place of its fluctuating variability,
+which was found not to do justice to the facts&mdash;this second
+hypothesis of dogmatic Lamarckism is liable to just the
+same objections as dogmatic Darwinism itself.</p>
+
+<p>As it is important to understand well the real logical
+nature of our objections to both of the great transformistic<span class="pagenum" title="283"><a name="Page_283" id="Page_283"></a></span>
+theories, we think it well to interrupt our argument for a
+moment, in order to consider a certain point which, though
+very important in itself, seems of only secondary importance
+to us in our present discussion. Dogmatic Darwinism&mdash;I
+do not say the doctrine of Charles Darwin&mdash;is materialistic
+at bottom, and indeed has been used by many to complete
+their materialistic view of the universe on its organic side.
+The word “materialism” must not necessarily be taken
+here in its metaphysical sense, though most materialists
+are dogmatic metaphysicians. It also can be understood
+as forming part of a phenomenological point of view.
+Materialism as a doctrine of science means simply this:
+that whether “nature” be reality or phenomenon, in any
+case there is but one ultimate principle at its base, a
+principle relating to the movements of particles of matter.
+It is this point of view which dogmatic Darwinism
+strengthens; on the theory of natural selection and fluctuating
+variations, due to accidental differences of nutrition,
+organisms are merely arrangements of particles of
+matter, nothing else; and moreover, their kinds of arrangement
+are understood, at least in principle. Lamarckism,
+on the other hand, is not materialistic, but most markedly
+vitalistic&mdash;psychistic even; it takes life for granted when
+it begins its explanations.</p>
+
+<p>You may tell me that Darwin did the same, that
+he expressly states that his theory has nothing to do with
+the origin of life; that the title of his work is “The Origin
+of <em>Species</em>.” It would certainly be right to say so, at least
+with reference to Darwin personally; but in spite of that,
+it must be granted that Darwin’s doctrine contains a certain
+germ of materialism which has been fully developed by the<span class="pagenum" title="284"><a name="Page_284" id="Page_284"></a></span>
+Darwinian dogmatists, while Lamarckism is antimaterialistic
+by its very nature.</p>
+
+<p>Now it is very important, I think, to notice that this
+difference between the two theories is unable to disguise
+one main point which is common to both: and it is to
+this point, and to this point only, that our chief objections
+against both these theories converge at present.</p>
+
+<p>The <em>contingency</em> of the typical organic form is maintained
+by Darwinism as well as by Lamarckism: both theories,
+therefore, break down for almost the same reasons. The term
+“contingency” can signify very different relations, having
+but little in common; but it is sufficient for our present
+purpose to observe that there may be distinguished roughly
+two main classes of contingencies, which may provisionally
+be called the “contingency of being,” and the “contingency
+of occurring.” It is with the contingency of being that
+criticism of Darwinism and Lamarckism of the dogmatic
+type has to deal. Darwinism dealt with variations occurring
+at random; the organic form was the result of a
+fixation of only one kind of such variations, all others
+being extinguished by selection. In other terms, the specific
+organised form, as understood by Darwinism, was a unit
+only to the extent that all its properties related to one and
+the same body, but for the rest it was a mere aggregation
+or summation. It may be objected to this statement, that
+by being inherited in its specificity the Darwinian form
+proved to be a unit in a higher sense of the word, even
+in the opinion of dogmatic Darwinians; and this objection,
+perhaps, holds good as far as inheritance is concerned. But
+on the other hand, it must never be forgotten that the
+word “unit” had quite a vague and empty meaning even<span class="pagenum" title="285"><a name="Page_285" id="Page_285"></a></span>
+then, as indeed everything the organism is made up of is
+regarded as being in itself due to a contingent primary
+process, which has no relation to its fellow-processes.
+“Unit,” indeed, in spite of inheritance&mdash;which, by the way,
+is alleged also to be a merely materialistic event&mdash;means
+to Darwinians no more when applied to the organism than
+it does when applied to mountains or islands, where of
+course a sort of “unit” also exists in some sense, as far as
+one and the same body comes into account, but where
+every single character of this unit, in every single feature
+of form or of quality, is the result of factors or agents each
+of which is independent of every other.</p>
+
+<p>To this sort of contingency of being, as maintained by
+Darwinians, criticism has objected, as we know, that it is
+quite an impossible basis of a theory of descent, since it
+would explain neither the first origin of an organ, nor any
+sort of harmony among parts or among whole individuals,
+nor any sort of restitution processes.</p>
+
+<p>Now Lamarckism of the dogmatic kind, as will easily
+be seen, only differs from Darwinism in this respect, that
+what according to the latter happens to the organism
+passively by means of selection, is according to the former
+performed actively by the organism, by means of a
+“judgment”&mdash;by the retention and handing down of chance
+variations. The specificity of the form as a whole is
+contingent also according to Lamarckism. And, indeed,
+criticism must reject this contingency of being in exactly
+the same way as it rejected the contingency of form
+maintained by Darwinians.</p>
+
+<p>As far as the inheritance of truly adaptive characters
+comes into account&mdash;that is, the inheritance of characters<span class="pagenum" title="286"><a name="Page_286" id="Page_286"></a></span>
+which are due to the active faculty of adaptation possessed
+by the organism, bearing a vitalistic aspect throughout&mdash;hardly
+anything could be said against Lamarckism, except
+that inheritance of acquired characters is still an hypothesis
+of small and doubtful value at present. But that <em>specific
+organisation proper</em> is due to <em>contingent</em> variations, which
+accidentally have been found to satisfy some needs of the
+individual and therefore have been maintained and handed
+down, this reasoning is quite an impossibility of exactly
+the same kind as the argument of Darwinism.</p>
+
+<p>The process of restitution, perfect the very first time
+it occurs, if it occurs at all, is again the classical instance
+against this new sort of contingency, which is assumed to
+be the basis of transformism. Here we see with our eyes
+that the organism can do more than simply perpetuate
+variations that have occurred at random and bear in themselves
+no relation whatever to any sort of unit or totality.
+There <em>exists</em> a faculty of a certain higher degree in the
+organism, and this faculty cannot possibly have originated
+by the process which <span class="nowrap">Lamarckians<a name="FNanchor_156_156" id="FNanchor_156_156"></a><a href="#Footnote_156_156" class="fnanchor">156</a></span> assume. But if their
+principle fails in one instance, it fails as a <em>general</em> theory
+altogether. And now, on the other hand, as we actually<span class="pagenum" title="287"><a name="Page_287" id="Page_287"></a></span>
+see the individual organism endowed with a morphogenetic
+power, inexplicable by Lamarckism, but far exceeding the
+organogenetic faculty assumed by that theory, would it
+not be most reasonable to conclude from such facts, that
+there exists a certain organising power at the root of the
+transformism of species also, a power which we do not
+understand, which we see only partially manifested in the
+work of restitutions, but which certainly is not even touched
+by any of the Lamarckian arguments? There does indeed
+exist what Gustav Wolff has called primary purposefulness
+(“primäre Zweckmässigkeit”), at least in restitutions, and
+this is equally unexplainable by Darwinism and by the
+dogmatism of the Lamarckians.</p>
+
+<p>But before entering into this area of hypothesis, let us
+mention a few more objections to be made to the theory
+of the contingency of form as put forward by Lamarckians.
+In the first place, let us say a few words about the
+appropriateness of the term “contingency” as used in this
+connection. The forms are regarded as contingent by
+Lamarckians inasmuch as the variations which afterwards
+serve as “means” to the “needs” of the organism occur
+quite accidentally with regard to the whole organism.
+It might be said that these “needs” are not contingent
+but subject to an inherent destiny, but this plea is excluded
+by the Lamarckians themselves, when they say that the
+organism experiences no need until it has enjoyed the
+accidental fulfilment of the same. So the only thing in
+Lamarckian transformism which is not of a contingent
+character would be the psychological agent concerned in it,
+as being an agent endowed with the primary power of
+feeling needs after it has felt fulfilment, and of judging<span class="pagenum" title="288"><a name="Page_288" id="Page_288"></a></span>
+about what the means of future fulfilment are, in order to
+keep them whenever they offer. But these are characteristics
+of life itself, irrespective of all its specific forms, which alone
+are concerned in transformism. Now indeed, I think, we
+see as clearly as possible that Darwinism and Lamarckism,
+in spite of the great contrast of materialism and psychologism,
+shake hands on the common ground of the contingency
+of organic forms.</p>
+
+<p>The whole anti-Darwinistic criticism therefore of Gustav
+Wolff for instance, may also be applied to Lamarckism
+with only a few changes of words. How could the origin
+of so complete an organ as the eye of vertebrates be due to
+contingent variations? How could that account for the
+harmony of the different kinds of cells in this very complicated
+organ with each other and with parts of the
+brain? And how is it to be understood, on the assumption
+of contingency, that there are two eyes of almost equal
+perfection, and that there are two feet, two ears? Islands
+and mountains do not show such symmetry in <em>their</em>
+structures.</p>
+
+<p>We shall not repeat our deduction of the origin of
+restitutions, of regeneration for instance, on the dogmatic
+Lamarckian theory. As we have said already, it would lead
+to absurdities as great as in the case of dogmatic Darwinism,
+and indeed we already have mentioned that Lamarckians
+would hardly even attempt to explain these phenomena.
+It follows that dogmatic Lamarckism fails as a general
+theory about <span class="nowrap">form.<a name="FNanchor_157_157" id="FNanchor_157_157"></a><a href="#Footnote_157_157" class="fnanchor">157</a></span></p>
+
+<p>There is finally one group of facts often brought forward<span class="pagenum" title="289"><a name="Page_289" id="Page_289"></a></span>
+against Lamarckism by Darwinian <span class="nowrap">authors<a name="FNanchor_158_158" id="FNanchor_158_158"></a><a href="#Footnote_158_158" class="fnanchor">158</a></span> which may be
+called the logical <i lang="la" xml:lang="la">experimentum crucis</i> of this doctrine, an
+<i lang="la" xml:lang="la">experimentum</i> destined to prove fatal. You know that
+among the polymorphic groups of bees, termites, and ants,
+there exists one type of individuals, or even several types,
+endowed with some very typical features of organisation,
+but at the same time absolutely excluded from reproduction:
+how could those morphological types have originated on
+the plan allowed by the Lamarckians? Of what use
+would “judgment” about means that are offered by chance
+and happen to satisfy needs, be to individuals which die
+without offspring? Here Lamarckism becomes a simple
+absurdity, just as Darwinism resulted in absurdities
+elsewhere.</p>
+
+<p>We were speaking about dogmatic Darwinism then, and
+it is about dogmatic Lamarckism that we are reasoning at
+present; both theories must fall in their dogmatic form,
+though a small part of both can be said to stand criticism.
+But these two parts which survive criticism, one offered by
+Lamarck, the other by Darwin, are far from being a
+complete theory of transformism, even if taken together:
+they only cover a small area of the field concerned in the
+theory of descent. Almost everything is still to be done,
+and we may here formulate, briefly at least, what we expect
+to be accomplished by the science of the future.</p>
+
+<p><span class="pagenum" title="290"><a name="Page_290" id="Page_290"></a></span></p>
+
+
+<h4 class="fs120">4. <span class="smcap">The Real Results and the Unsolved Problems of
+Transformism</span></h4>
+
+<p>What has been explained to a certain extent by the two
+great theories now current is only this. Systematic diversities
+consisting in mere differences as to intensity or
+number may perhaps owe their origin to ordinary variation.
+They may at least, if we are entitled to assume that heredity
+in some cases is able to hand on such variations without
+reversion, which, it must be again remarked, is by no means
+proved by the facts at present. Natural selection may share
+in this process by eliminating all those individuals that do
+not show the character which happens to be useful. That
+is the Darwinian part of an explanation of transformism
+which may be conceded as an hypothesis. On the other
+side, congenital histological adaptedness may be regarded
+hypothetically as due to an inheritance of adaptive
+characters which had been acquired by the organism’s
+activity, exerted during a great number of generations.
+That is the Lamarckian part in the theory of descent.</p>
+
+<p>But nothing more is contributed to this theory either
+by the doctrine of Darwin or by that of Lamarck. So it
+follows that almost everything has still to be done; for no
+hypothesis at present accounts for the foundation of all
+systematics, viz., for the differences in organisation, in all<span class="pagenum" title="291"><a name="Page_291" id="Page_291"></a></span>
+that relates to the so-called types as such and the degree of
+complication in these types, both of which (types and degree
+of complication) are independent of histological adaptation
+and adaptedness.</p>
+
+<p>What then do we know about any facts that might be
+said to bear on this problem? We have stated already
+at the end of our chapter devoted to the analysis of heredity
+that what we actually know about any deviation of inheritance
+proper, that is, about congenital differences between
+the parents and the offspring, relating to mere tectonics,
+is practically nothing: indeed, there are at our disposal
+only the few facts observed by de Vries or derived from
+the experience of horticulturalists and breeders. We may
+admit that these facts at least prove the <span class="nowrap">possibility<a name="FNanchor_159_159" id="FNanchor_159_159"></a><a href="#Footnote_159_159" class="fnanchor">159</a></span> of
+a discontinuous variation, that is of “mutation,” following
+certain lines of tectonics and leading to <em>constant</em> results;
+but everything else, that is everything about a real theory
+of phylogeny, must be left to the taste of each author who
+writes on the theory of the Living. You may call that a
+very unscientific state of affairs, but no other is possible.</p>
+
+<p>And, in fact, it has been admitted by almost all who
+have dealt with transformism without prepossessions that
+such is the state of affairs. Lamarck himself, as we have
+mentioned already, was not blind to the fact that a sort of
+organisatory law must be at the base of all transformism,
+and it is well known that hypothetical statements about
+an original law of phylogeny have been attempted by<span class="pagenum" title="292"><a name="Page_292" id="Page_292"></a></span>
+Nägeli, Kölliker, Wigand, Eimer, and many others. But a
+full discussion of all these “laws” would hardly help us
+much in our theoretical endeavour, as all of them, it must be
+confessed, do little more than state the mere fact that some
+unknown principle of organisation must have been at work
+in phylogeny, if we are to accept the theory of descent
+at all.</p>
+
+<p>It is important to notice that even such a convinced
+Darwinian as Wallace, who is well known to have been an
+independent discoverer of the elimination principle, admitted
+an exception to this principle in at least one case&mdash;with
+regard to the origin of man. But one exception of course
+destroys the generality of a principle.</p>
+
+<p>As we ourselves feel absolutely incapable of adding
+anything specific to the general statement that there <em>must</em>
+be an unknown principle of transformism, if the hypothesis
+of descent is justified at all, we may here close our discussion
+of the subject.</p>
+
+<p><span class="pagenum" title="293"><a name="Page_293" id="Page_293"></a></span></p>
+
+
+<h4 class="fs120">5. <span class="smcap">The Logical Value of the Organic Form According to the<br />Different Transformistic Theories</span></h4>
+
+<p>A few words only must be added about two topics: on
+the character of organic forms as regarded by the
+different transformistic theories, and on the relation of
+transformism in general to our concept of entelechy.</p>
+
+<p>We have learnt that both Darwinism and Lamarckism,
+in their dogmatic shape, regard the specific forms of animals
+and plants as being contingent; in fact, it was to this
+contingency that criticism was mainly directed. We
+therefore are entitled to say that to Darwinism and
+Lamarckism organic forms are accidental in the very sense
+of the <i lang="la" xml:lang="la">forma accidentalis</i> of the old logicians. There
+are indefinite forms possible, according to these theories,
+and there is no law relating to these forms. Systematics,
+under such a view, must lose, of course, any really
+fundamental importance. “There is no rational system
+about organisms”: that is the ultimate statement of
+Darwinism and of Lamarckism on this doubtful question.
+Systematics is a mere catalogue, not at present only, but for
+ever, by the very nature of the organisms. It is not owing
+to the indefinite number of possible forms that both our
+theories came to deny the importance of systematics, but to
+the want of a <em>law</em> relating to this indefinite number: among<span class="pagenum" title="294"><a name="Page_294" id="Page_294"></a></span>
+chemical compounds indefinite possibilities also exist in
+some cases, but they obey the law of the general formula.
+It is very strange that Darwinians of all people are in the
+forefront of systematic research in all countries: do they
+not see that what they are trying to build up can only
+relate to accidental phenomena? Or have they some doubts
+about the foundations of their own theoretical views, in spite
+of the dogmatic air with which they defend them? Or is
+it the so-called historical interest which attracts them?</p>
+
+<p>A new question seems to arise at this point: Have not
+we ourselves neglected history in favour of systematics and
+laws? Our next lecture, the last of this year, will give
+the answer to this question.</p>
+
+<p>At present we continue our study of the possible aspects
+of systematics. It is not difficult to find out what meaning
+organic forms would assume under any phylogenetic theory
+opposed to the theories of contingency. It was their
+defence of contingency, that is, their lack of any law of
+forms, that caused these theories to be overthrown&mdash;reduced
+to absurdities even&mdash;and therefore, it follows that to assume
+any kind of transformistic law is at the same time to deny
+the accidental character of the forms of living beings.</p>
+
+<p>There is no <i lang="la" xml:lang="la">forma accidentalis</i>. Does that mean that
+the <i lang="la" xml:lang="la">forma essentialis</i> is introduced by this mere statement?
+And what would <em>that</em> assert about the character of
+systematics?</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE ORGANIC FORM AND ENTELECHY</span></p>
+
+<p>This problem is not as simple as it might seem to be
+at the first glance, and, in fact, it is insoluble at present.<span class="pagenum" title="295"><a name="Page_295" id="Page_295"></a></span>
+It is here that the relation of the hypothetic transformistic
+principle to our concept of entelechy is concerned.</p>
+
+<p>We know that entelechy, though not material in itself,
+uses material means in each individual morphogenesis,
+handed down by the material continuity in inheritance.
+What then undergoes change in phylogeny, the means or
+the entelechy? And what would be the logical aspect of
+systematics in either case?</p>
+
+<p>Of course there would be a law in systematics in any
+case; and therefore systematics in any case would be
+rational in principle. But if the transformistic factor
+were connected with the means of morphogenesis, one
+could hardly say that specific form as such was a primary
+essence. Entelechy would be that essence, but entelechy
+in its generality and always remaining the same in its
+most intimate character, as the specific diversities would
+only be due to a something, which is not form, but simply
+means to form. But the <em>harmony</em> revealed to us in every
+typical morphogenesis, be it normal or be it regulatory,
+seems to forbid us to connect transformism with the means
+of morphogenesis. And therefore we shall close this
+discussion about the most problematic phenomena of
+biology with the declaration, that we regard it as more
+congruent to the general aspect of life to correlate the
+unknown principle concerned in descent with entelechy
+itself, and not with its means. Systematics of organisms
+therefore would be in fact systematics of entelechies, and
+therefore organic forms would be <i lang="la" xml:lang="la">formae essentiales</i>,
+entelechy being the very essence of form in its
+specificity. Of course systematics would then be able to
+assume a truly rational character at some future date:<span class="pagenum" title="296"><a name="Page_296" id="Page_296"></a></span>
+there might one day be found a principle to account
+for the totality of <span class="nowrap">possible<a name="FNanchor_160_160" id="FNanchor_160_160"></a><a href="#Footnote_160_160" class="fnanchor">160</a></span> forms, a principle based upon
+the analysis of <span class="nowrap">entelechy.<a name="FNanchor_161_161" id="FNanchor_161_161"></a><a href="#Footnote_161_161" class="fnanchor">161</a></span> As we have allowed that
+Lamarckism hypothetically explains congenital adaptedness
+in histology, and that Darwinism explains a few differences
+in quantity, and as such properties, of course, would both
+be of a contingent character, it follows that our future
+rational system would be combined with certain accidental
+diversities. And so it might be said to be one of the
+principal tasks of systematic biological science in the
+future to discover the really rational system among a given
+totality of diversities which cannot appear rational at the first
+glance, one sort of differences, so to speak, being superimposed
+upon the other.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="297"><a name="Page_297" id="Page_297"></a></span></p>
+
+
+<h3><i>C.</i> THE LOGIC OF HISTORY</h3>
+
+
+<p>History, in the strictest sense of the word, is the
+enumeration of the things which have followed one
+another in order of time. History deals with the single,
+with regard both to time and space. Even if its facts
+are complex in themselves and proper to certain other
+kinds of human study, they are nevertheless regarded by
+history as single. Facts, we had better say, so far as they
+are regarded as single, are regarded historically, for what
+relates to specific time and space is called history.</p>
+
+<p>Taken as a simple enumeration or registration, history,
+of course, cannot claim to be a “science” unless we are
+prepared to denude that word of all specific meaning. But
+that would hardly be useful. As a matter of fact, what
+has actually claimed to be history, has always been more
+than a mere enumeration, even in biology proper. So-called
+phylogeny implies, as we have shown, that every
+one of its actual forms contains some rational elements.
+Phylogeny always rests on the assumption that only some
+of the characters of the organisms were changed in transformism
+and that what remained unchanged may be
+explained by the fact of inheritance.</p>
+
+<p>But this, remember, was the utmost we were able to say
+for phylogeny. It remains fantastic and for the most part<span class="pagenum" title="298"><a name="Page_298" id="Page_298"></a></span>
+unscientific in spite of this small degree of rationality,
+as to which it is generally not very clear itself. For
+nothing is known with regard to the positive factors of
+transformism, and we were only able to offer the discussion
+of a few possibilities in place of a real theory of the
+factors of descent.</p>
+
+<p>In spite of that it will not be without a certain logical
+value to begin our analysis of history in general by the
+discussion of possibilities again. Biology proper would
+hardly allow us to do more: for the simple “fact” of
+history is not even a “fact” in this science, but an
+hypothesis, albeit one of some probability.</p>
+
+<p>As discussions of mere possibilities should always rest
+on as broad a basis as possible, we shall begin our analysis
+by raising two general questions. To what kinds of realities
+may the concept of history reasonably be applied? And
+what different types of “history” would be possible <i lang="la" xml:lang="la">a
+priori</i>, if the word history is to signify more than a mere
+enumeration?</p>
+
+<p><span class="pagenum" title="299"><a name="Page_299" id="Page_299"></a></span></p>
+
+
+<h4 class="fs120">1. <span class="smcap">The Possible Aspects of History</span></h4>
+
+<p>Of course, we could select one definite volume in space
+and call all the consecutive stages which it goes through,
+its history: it then would be part of its history that a
+cloud was formed in it, or that a bird passed through it
+on the wing. But it would hardly be found very
+suggestive to write the history of space-volumes. In fact,
+it is to <em>bodies</em> in space that all history actually relates, at
+least indirectly, for even the history of sciences is in some
+respect the history of men or of books. It may suffice for
+our analysis to understand here the word body in its
+popular sense.</p>
+
+<p>Now in its relation to bodies history may have the
+three following aspects, as far as anything more than a
+simple enumeration comes into account. Firstly, it may
+relate to one and the same body, the term body again to be
+understood popularly. So it is when the individual history
+of the organism is traced from the egg to the adult, or
+when the history of a cloud or of an island or of a volcano
+is written. Secondly, the subject-matter of history may be
+formed by the single units of a consecutive series of bodies
+following each other periodically. To this variety of history
+the discoveries of Mendel and his followers would belong in
+the strictest sense, but so does our hypothetical phylogeny<span class="pagenum" title="300"><a name="Page_300" id="Page_300"></a></span>
+and a great part of the history of mankind. And lastly,
+there is a rather complicated kind of sequence of which the
+“history” has actually been written. History can refer to
+bodies which are in no direct relation with one another,
+but which are each the effect of another body that belongs
+to a consecutive series of body-units showing periodicity.
+This sounds rather complicated; but it is only the strict
+expression of what is perfectly familiar to you all. Our
+sentence indeed is simply part of the definition of a
+history of art or of literature for instance&mdash;or, say, of
+a phylogenetic history of the nests of birds. The
+single pictures are the subjects of the history of art, and
+nobody would deny that these pictures are the effects of
+their painters, and that the painters are individuals of
+mankind&mdash;that is, that they are bodies belonging to a
+consecutive series of body-units showing periodicity. Of
+course, it is only improperly that we speak of a history
+of pictures or of books or of nests. In fact, we are dealing
+with painters, and with men of letters or of science, and
+with certain birds, and therefore the third type of history
+may be reduced to the second. But it was not without
+value to pursue our logical discrimination as far as
+possible.</p>
+
+<p>So far we have always spoken of history as being more
+than a mere enumeration, but we have not ascertained
+what this “more” signifies. It is not very difficult to do
+so: in fact, there are three different types of history,
+each of a different degree of importance with respect to
+the understanding of reality.</p>
+
+<p>In the first place, history may start as a mere enumeration
+at the beginning, and at the end, in spite of all further<span class="pagenum" title="301"><a name="Page_301" id="Page_301"></a></span>
+endeavour, may <em>remain</em> that and nothing more. That
+may occur in the first as well as in the second group of our
+division of history with regard to its relation to bodies.
+Take a cloud and describe its history from the beginning
+to the end: there would never be much more than pure
+description. Or take one pair of dogs and describe them
+and their offspring for four generations or more: I doubt
+if you will get beyond mere descriptions in this case either.
+The only step beyond a mere enumeration which we can be
+said to have advanced in these instances, consists in the
+conviction, gained at the end of the analysis, that nothing
+more than such an enumeration is in any way <em>possible</em>.</p>
+
+<p>Quite the opposite happens when “history” deals with the
+individual from the egg to the adult: here the whole series
+of historical facts is seen to form one whole. This case
+therefore we shall call not history, but <em>evolution</em>, an evolving
+of something; the word “evolution” being understood here
+in a much wider sense than on former <span class="nowrap">occasions,<a name="FNanchor_162_162" id="FNanchor_162_162"></a><a href="#Footnote_162_162" class="fnanchor">162</a></span> and <em>including</em>,
+for instance, the embryological alternative “evolutio”
+or “epigenesis.”</p>
+
+<p>And half-way between enumeration and evolution there
+now stands a type of history which is more than the one
+and less than the other: there is a kind of intelligible
+connection between the consecutive historical stages and
+yet the concept of a whole does not come in. The geological
+history of a mountain or of an island is a very clear instance
+of this class. It is easy to see here, how what <em>has been</em> always
+becomes the foundation of what <em>will be</em> in the <em>next</em> phase of
+the historical process. There is a sort of <em>cumulation</em> of consecutive
+phases, the later ones being impossible without the<span class="pagenum" title="302"><a name="Page_302" id="Page_302"></a></span>
+earlier. So we shall speak of the type of “historical
+cumulation” as standing between evolution and bare
+temporal sequence. By means of historical cumulations
+history may fairly claim to “explain” things. We “understand”
+a mountain or an island in all its actual characteristics,
+if we know its history. This “historical understanding”
+rests on the fact that what first appeared as an
+inconceivable complex has been resolved into a sequence of
+single events, each of which may claim to have been explained
+by actually existing sciences. The complex has been
+explained as being, though not a real “whole,” yet a sum
+of singularities, every element of which is familiar.</p>
+
+<p>But you may tell me that my discussion of evolution
+and of cumulation, as the higher aspects of history, is by no
+means complete; nay, more&mdash;that it is altogether wrong.
+You would certainly not be mistaken in calling my analysis
+incomplete. We have called one type of history evolution,
+the other cumulation; but how have these higher types
+been reached? Has historical enumeration itself, which
+was supposed to stand at the beginning of all analysis, or
+has “history” itself in its strictest sense, as relating to
+the single as such, risen unaided into something more than
+“history”? By no means: history has grown beyond its
+bounds by the aid of something from without. It is
+unhistorical elements that have brought us from mere
+history to more than history. We have created the concept
+of evolution, not from our knowledge of the single line of
+events attendant on a single egg of a frog, but from our
+knowledge that there are billions or more of frogs’ eggs, all
+destined to the same “history,” which therefore is not
+history at all. We have created the concept of cumulation<span class="pagenum" title="303"><a name="Page_303" id="Page_303"></a></span>
+not from the historical study of a single mountain, but
+from our knowledge of physics and chemistry and so-called
+dynamical geology: by the aid of these sciences we “understood”
+historically, and thus our understanding came from
+another source than history itself.</p>
+
+<p><span class="pagenum" title="304"><a name="Page_304" id="Page_304"></a></span></p>
+
+
+<h4 class="fs120">2. <span class="smcap">Phylogenetic Possibilities</span></h4>
+
+<p>Does history always gain its importance from what it
+is not? Must history always lose its “historical” aspect,
+in order to become of importance to human knowledge?
+And can it <em>always</em> become “science” by such a transformation?
+We afterwards shall resume this discussion on a
+larger scale, but at present we shall apply what we have
+learned to hypothetic phylogeny. What then are the
+possibilities of phylogeny, to what class of history would it
+belong if it were complete? Of course, we shall not be able
+to answer this question fully; for phylogeny is <em>not</em> complete,
+and scarcely anything is known about the factors
+which act in it. But in spite of that, so much, it seems to
+me, is gained by our analysis of the possible aspects of history
+and of the factors possibly concerned in transformism, that
+we are at least able to formulate the possibilities of a
+phylogeny of the future in their strict logical outlines.</p>
+
+<p>Darwinism and Lamarckism, regarding organic forms as
+contingent, must at the same time regard organic history
+as a cumulation; they indeed <em>might</em> claim to furnish an
+historical explanation in the realm of biology&mdash;if only their
+statements were unimpeachable, which as we have seen,
+they are not.</p>
+
+<p>But any transformistic theory, which locates the very<span class="pagenum" title="305"><a name="Page_305" id="Page_305"></a></span>
+principle of phylogeny in the organism itself, and to which
+therefore even organic forms would be not accidental but
+essential, might be forced to regard the descent of organisms
+as a true evolution. The singularities in phylogenetic
+history would thus become links in one whole: history proper
+would become more than history. But I only say that
+phylogeny <em>might</em> be evolution, and in fact I cannot admit
+more than this <i lang="la" xml:lang="la">a priori</i>, even on the basis of an internal
+transformistic principle, as has been assumed. Such a
+principle also might lead always from one typical state of
+organisation to the next: but <i lang="la" xml:lang="la">ad infinitum</i>.<a name="FNanchor_163_163" id="FNanchor_163_163"></a><a href="#Footnote_163_163" class="fnanchor">163</a> Then
+phylogeny, though containing what might in some sense
+be called “progress,” would not be “evolution”; it might
+even be called cumulation in such a case, in spite of the
+internal transforming principle, though, of course, cumulation
+from within would always mean something very
+different from cumulation from <span class="nowrap">without.<a name="FNanchor_164_164" id="FNanchor_164_164"></a><a href="#Footnote_164_164" class="fnanchor">164</a></span></p>
+
+<p>But we must leave this problem an open question, as
+long as our actual knowledge about transformism remains
+as poor as it is. We need only add, for the sake of logical
+interest, that phylogeny, as a true evolution, would necessarily
+be characterised by the possibility of being repeated.</p>
+
+<p><span class="pagenum" title="306"><a name="Page_306" id="Page_306"></a></span></p>
+
+
+<h4 class="fs120">3. <span class="smcap">The History of Mankind</span></h4>
+
+<p>We only assume hypothetically that phylogeny has
+happened, and we know scarcely anything about the factors
+concerned in it. Now, it certainly would be of great importance,
+if at least in a small and definite field of biology we
+were able to state a little more, if the <em>mere fact</em> of phylogeny,
+of “history,” were at least beyond any doubt within a certain
+range of our biological experience. And indeed there is
+one department of knowledge, where history, as we know,
+<em>has happened</em>, and where we also know at least some of the
+factors concerned in it.</p>
+
+<p>I refer to the history of mankind; and I use the
+expression not at all in its anthropological or ethnographical
+sense, as you might expect from a biologist, but in its
+proper and common sense as the history of politics and of
+laws and of arts, of literature and of sciences: in a
+word, the history of civilisation. Here is the only field,
+where we know that there actually <em>are</em> historical facts:
+let us try to find out what these facts can teach us about
+their succession.</p>
+
+<p>The theory of history in this narrower meaning of the
+word has been the subject of very numerous controversies
+in the last twenty years, especially in Germany, and these
+controversies have led very deeply into the whole<span class="pagenum" title="307"><a name="Page_307" id="Page_307"></a></span>
+philosophical view of the universe. We shall try to treat
+our subject as impartially as possible.</p>
+
+<p>Hegel says, in the introduction to his <cite lang="de" xml:lang="de">Phänomenologie
+des Geistes</cite>: “<cite lang="de" xml:lang="de">Die Philosophie muss sich hüten erbaulich
+sein zu wollen</cite>” (“Philosophy must beware of trying to
+be edifying”). These words, indeed, ought to be inscribed
+on the lintel of the door that leads into historical
+methodology, for they have been sadly neglected by
+certain theoretical writers. Instead of analysing history in
+order to see what it would yield to philosophy, they have
+often made philosophy, especially moral philosophy, the
+starting-point of research, and history then has had to obey
+certain doctrines from the very beginning.</p>
+
+<p>We shall try as far as we can not to become “erbaulich”
+in our discussions. We want to learn from history for the
+purposes of philosophy, and we want to learn from history
+as from a phenomenon in time and in space, just as we
+have learnt from all the other phenomena regarding life in
+nature. Every class of phenomena of course may be
+studied with respect to generalities as well as with respect
+to particulars. The particular, it is true, has not taught us
+much in our studies so far. Perhaps it may be successful
+in the domain of history proper.</p>
+
+<p>If I take into consideration what the best authors of
+the last century have written about human history with
+respect to its general value, I cannot help feeling that
+none of them has succeeded in assigning to history a
+position where it would really prove to be of great importance
+for the aims of philosophical inquiry. Is that the
+fault of the authors or of human history? And what then
+would explain the general interest which almost every one<span class="pagenum" title="308"><a name="Page_308" id="Page_308"></a></span>
+takes, and which I myself take in history in spite of this
+unsatisfactory state of things?</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">CUMULATIONS IN HUMAN HISTORY</span></p>
+
+<p>Let us begin our analytical studies of the value and the
+meaning of human history, by considering some opinions
+which deserve the foremost place in our discussion,
+not as being the first in time, but as being the first in
+simplicity. I refer to the views of men like Buckle, Taine,
+and Lamprecht, and especially Lamprecht, for he has tried
+the hardest to justify theoretically what he regards the
+only scientific aim of history to be. If we may make use
+of our logical scheme of the three possible aspects of
+history, it is clear from the beginning that the history of
+mankind, as understood by the three authors we have
+named, but most particularly by Lamprecht, is neither a
+mere enumeration nor a true evolution, but that it has to
+do with <em>cumulations</em>, in the clearest of their possible forms.
+The processes of civilisation among the different peoples
+are in fact to be compared logically with the origin of
+volcanoes or mountain-ranges in Japan, or in Italy, or in
+America, and show us a typical series of consecutive
+phases, as do these. There exists, for instance, in the
+sphere of any single civilisation an economic system, founded
+first on the exchange of natural products, and then on
+money. There are, or better, perhaps, there are said to be,
+characteristic phases succeeding one another in the arts, such
+as the “typical,” the “individualistic,” and the “subjective”
+phases. Any civilisation may be said to have its “middle
+ages,” and so on. All these are “laws” of course in the<span class="pagenum" title="309"><a name="Page_309" id="Page_309"></a></span>
+meaning of “rules” only, for they are far from being
+elemental, they are not “principles” in any sense. And
+there are other sorts of “rules” at work for exceptional
+cases: revolutions have their rules, and imperialism, for
+instance, has its rules also.</p>
+
+<p>Now, as the consecutive phases of history have been
+shown to be true cumulations, it follows that the rules
+which are revealed by our analysis, are rules relating to
+the very origin of cumulations also. The real <em>element</em>
+upon which the cumulation-phases, and the cumulation-rules
+together rest, is the human individual as the bearer
+of its psychology. Nobody, it seems to me, has shown
+more clearly than Simmel that it is the human individual,
+<i lang="la" xml:lang="la">qua</i> individual, which is concerned in <em>every</em> kind of history.</p>
+
+<p>History, viewed as a series of cumulations, may in fact
+claim to satisfy the intellect by “explaining” a good deal
+of historical facts. It explains by means of the elemental
+factor of individual psychology, which every one knows
+from himself, and by the simple concept that there is a
+cumulation, supported by language and by writing as its
+principal factors, which both of course rest on psychology
+again. Psychology, so we may say, is capable of leading to
+cumulation phenomena; the cumulations in history are
+such that we are able to understand them by our everyday
+psychology; and history, so far as it is of scientific value,
+consists exclusively of cumulations.</p>
+
+<p>No doubt there is much truth in such a conception of
+history; but no doubt also, it puts history in the second
+rank as compared with psychology; just as geology stands
+in the second rank as compared with chemistry or physics.
+Geology and human history may lead to generalities in the<span class="pagenum" title="310"><a name="Page_310" id="Page_310"></a></span>
+form of rules, but these rules are <em>known</em> to be not elemental
+but only cumulative; and moreover, we know the elements
+concerned in them. The elements, therefore, are the real
+subjects for further studies in the realm of philosophy,
+but not the cumulations, not the rules, which are known
+to be due to accidental constellations. Of course, the
+“single” is the immediate subject of this sort of history,
+but the single as such is emphatically pronounced to be
+insignificant, and the cumulations and the cumulative rules,
+though “singles” in a higher sense of the word, are shown
+to be anything but elementalities.</p>
+
+<p>Therefore, on a conception of human history such as
+that of Buckle, Taine, Lamprecht, and others, we, of course,
+ought to take an interest in history, because what is
+“explained” by historical research touches all of us most
+personally every day and every year. But our philosophy,
+our view of the world, would remain the same without
+history as it is with it. We only study history, and
+especially the history of our own civilisation, because it is a
+field of actuality which directly relates to ourselves, just
+as we study for practical purposes the railway time-tables
+of our own country, but not of Australia; just as we study
+the local time-table in particular.</p>
+
+<p>If the mere <i lang="la" xml:lang="la">rerum cognoscere causas</i> is regarded as
+the criterium of science, history of Lamprecht’s type of
+course is a science, for its explanations rest upon the
+demonstration of the typical constellations and of the
+elemental factor or law from which together the next constellations
+are known necessarily to follow. But history of
+this kind is not a science in the sense of discovering <i lang="de" xml:lang="de">den
+ruhenden Pol in der Erscheinungen Flucht</i>.</p>
+
+<p><span class="pagenum" title="311"><a name="Page_311" id="Page_311"></a></span></p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">HUMAN HISTORY NOT AN “EVOLUTION”</span></p>
+
+<p>Quite another view of history has been maintained by
+Hegel, if his explanations about the <i lang="de" xml:lang="de">Entwicklung des
+objectiven Geistes</i> (“the development of the objective mind”)
+may be co-ordinated with our strictly logical categories of
+the possible aspects of history. But I believe we are
+entitled to say that it was a real <em>evolution</em> of mankind
+that Hegel was thinking of; an evolution regarding mankind
+as spiritual beings and having an end, at least ideally.
+One psychical state was considered by Hegel to generate
+the next, not as a mere cumulation of elemental stages,
+but in such a way that each of the states would represent
+an elementality and an irreducibility in itself; and he
+assumed that there was a continuous series of such stages
+of the mind through the course of generations. Is there
+any sufficient reason in historical facts for such an
+assumption?</p>
+
+<p>The mind “evolves” itself from error to truth by what
+might be called a system of contradictions, according to
+Hegel, with respect to logic as well as to morality; the
+sum of such contradictions becoming smaller and less
+complicated with every single step of this evolution. No
+doubt there really occurs a process of logical and moral
+refining, so to say, in the individual, and no doubt also,
+the results of this process, as far as attained, can be
+handed down to the next generation by the spoken word
+or by books. But it is by no means clear, I think, that
+this process is of the type of a real evolution towards an
+end, so far as it relates to the actual series of generations
+as such. On the contrary, it seems to me that we have<span class="pagenum" title="312"><a name="Page_312" id="Page_312"></a></span>
+here simply what we meet everywhere in history&mdash;a sort
+of cumulation resting upon a psychological basis.</p>
+
+<p>The dissatisfaction that exists at any actual stage of
+contradiction, both moral and logical, is one of the psychical
+factors concerned; the faculty of reasoning is the other.
+Now it is a consequence of the reasoning faculty that the
+dissatisfaction continually decreases, or at least changes in
+such a way that each partial result of the logical process
+brings with it the statement of new problems. The
+number of such problems may become less, as the logical
+process advances, and, indeed, there is an ideal state, both
+logical and moral, in which there are no more problems,
+but only results, though this ideal could hardly be regarded
+as attainable by the <em>human</em> mind. In the history of those
+sciences which are wholly or chiefly of the <i lang="la" xml:lang="la">a priori</i> type,
+this process of deliverance from contradictions is most
+advantageously to be seen. It is obvious in mechanics
+and thermodynamics, and the theory of matter is another
+very good instance. A certain result is reached; much
+seems to be gained, but suddenly another group of facts
+presents itself, which had been previously unknown or
+neglected. The first result has to be changed or enlarged;
+many problems of the second order arise; there are contradictions
+among them, which disappear after a certain
+alteration of what was the first fundamental result, and so
+on. And the same is true about morality, though the
+difficulties are much greater here, as a clear and well-marked
+standard of measurement of what is good and
+what is bad, is wanting, or at least, is not conceded unanimously.
+But even here there is a consensus on some
+matters: one would hardly go back to slavery again, for<span class="pagenum" title="313"><a name="Page_313" id="Page_313"></a></span>
+instance, and there are still other points in morality which
+are claimed as ideals at least by a great majority of moral
+thinkers.</p>
+
+<p>But all this is not true “evolution,” and indeed, I doubt
+if such an evolution of mankind could be proved at present
+in the sense in which Hegel thought it possible. The
+process of logical and moral deliverance from contradictions
+<em>might</em> come to an end in <em>one</em> individual; at least that is a
+logical possibility, or it might come to an end in, say, six
+or ten generations. And there is, unfortunately for mankind,
+no guarantee that the result will not be lost again
+and have to be acquired a second time. All this proves
+that what Hegel regarded as an evolution of the race
+is only a cumulation. There is nothing evolutionary
+relating to the generations of mankind as such. At least,
+nothing is proved about such an <span class="nowrap">evolution.<a name="FNanchor_165_165" id="FNanchor_165_165"></a><a href="#Footnote_165_165" class="fnanchor">165</a></span></p>
+
+<p>You may call my view pessimistic, and indeed you may
+be right so far as the sum total of human beings as such
+is in question. But, be it pessimistic or not, we are here
+moving on scientific ground only, and have merely to study
+the probability or improbability of problematic facts, and
+with such a view in our mind, we are bound to say that a
+true logical and moral evolution of mankind is not at all
+supported by known facts. There is a process of logical
+and moral perfection, but this process is <em>not one</em>, is not
+“single” in its actuality; it is not connected with the one
+and single line of history, but only with a few generations
+each time it occurs, or even with one individual, at least<span class="pagenum" title="314"><a name="Page_314" id="Page_314"></a></span>
+ideally. And this process is not less a process of cumulation
+than any other sort of development or so-called
+“progress” in history is. Philosophers of the Middle
+Ages, in fact, sometimes regarded human history as <em>one</em>
+evolutionary unity, beginning with the Creation and ending
+with the Day of Judgment; but every one must agree, I
+think, that even under the dogmatic assumptions of
+orthodoxy history would by no means <em>necessarily</em> be an
+“evolution.” Even then the paths taken by different
+individuals or different branches of the human race on their
+way to redemption <em>can</em> be regarded as independent lines.</p>
+
+<p>Thus Hegel’s conception of an evolution of mankind,
+it seems to me, fails to stand criticism. By emphasising
+that there are certain lines of development in history which
+bring with them a stimulus to perfection, and that these
+lines relate to all that is highest in culture, Hegel certainly
+rendered the most important service to the theory of
+history; but in spite of that he has revealed to us only a
+special and typical kind of cumulation process, and nothing
+like an evolution. We may say that the very essence
+of history lies in this sort of cumulation, in this “pseudo-evolution”
+as we might say; and if we like to become
+moral metaphysicians we might add, that it is for the
+sake of the possibility of this sort of cumulation that
+man lives his earthly life; the Hindoos say so, indeed, and
+so do many Christians. But even if we were to depart
+from our scientific basis in this way we should not get
+beyond the realm of cumulations.</p>
+
+<p>All this, of course, is not to be understood to affirm
+that there never <em>will</em> be discovered any real evolutionary
+element in human history&mdash;in the so-called <span class="pagenum" title="315"><a name="Page_315" id="Page_315"></a></span>“subconscious”
+sphere perhaps&mdash;but at present we certainly are ignorant
+of such an element.</p>
+
+
+<p class="tac pt12b02em"><span class="lowercase smcap">THE PROBLEM OF THE “SINGLE” AS SUCH</span></p>
+
+<p>If history has failed to appear as a true evolution, and
+if, on the other hand, it reveals to us a great sum of
+different cumulations, some of very great importance, others
+of minor importance, what then remains of the importance
+of the single historical event in its very singleness?
+What importance can the description of this event have
+with regard to our scientific aims? We could hardly
+say at present that it appears to be of very much importance
+at all. The historical process as a whole has proved
+to be not a real elemental unit, as far as we know, and
+such elemental units as there are in it have proved to be
+of importance only <em>for</em> individual psychology but not <em>as</em>
+history. History has offered us only instances of what
+every psychologist knew already from his own experience,
+or at least might have known if he had conceived his
+task in the widest possible spirit.</p>
+
+<p>But is no other way left by which true history might
+show its real importance in spite of all our former analysis?
+Can history be saved perhaps to philosophical science by
+any new sort of reasoning which we have not yet applied
+to it here.</p>
+
+<p>As a matter of fact, such new reasoning has been tried,
+and <span class="nowrap">Rickert,<a name="FNanchor_166_166" id="FNanchor_166_166"></a><a href="#Footnote_166_166" class="fnanchor">166</a></span> in particular, has laid much stress upon the
+point that natural sciences have to do with generalities,
+while historical sciences have to do with the single in its<span class="pagenum" title="316"><a name="Page_316" id="Page_316"></a></span>
+singleness only, and, in spite of that, are of the highest
+philosophical importance. He does not think very highly
+of so-called “historical laws,” which must be mere
+borrowings from psychology or biology, applied to history
+proper, and not touching its character as “history.” We
+agree with these statements to a considerable extent. But
+what then about “history proper,” what about “the single
+in its very singleness”?</p>
+
+<p>Let us say at first a few words about this term “single”
+so very often applied by us. In the ultimate meaning of
+the word, of course, the series of actual sensations or “presentations”
+is the “single” which is given “historically”
+to each individual, and therefore to the writer of history
+also, and in fact, history as understood by Rickert is based
+to a great extent upon this primordial meaning of single
+“givenness.” The word “single,” in his opinion, relates to
+the <em>actual and true specification</em> of any event, or group of
+events, at a given time and at a given locality in space,
+these events possessing an identity of their own and never
+being repeated without change of identity. If the subject-matter
+of history is defined like this, then there are, indeed,
+“Grenzen der naturwissenschaftlichen Begriffsbildung” with
+regard to history, for natural sciences have nothing to do
+with the single in such an understanding of the word.</p>
+
+<p>Rickert says somewhere that history as a real evolution,
+as one totality of a higher order, would cease to be proper
+history: and he is right. History, in fact, would soon lose
+the character of specific attachment to a given space and to
+a given time, and would lose its “non-repeatability,” in the
+logical sense at least, if it were one <em>unit</em> in reality: as
+soon as it was that, it would have become a logical<span class="pagenum" title="317"><a name="Page_317" id="Page_317"></a></span>
+generality, an element in nature, so to say, in spite of its
+factual singularity. But history is not obliged to become
+that, Rickert states; and we may add that history in fact
+cannot become that, because it simply proves not to be an
+evolution as far as we know at present.</p>
+
+<p>But what importance does Rickert attach to his history
+specified and non-repeatably single?</p>
+
+<p>History has a logic of its own, he says; the scheme
+of its logic is not the syllogism, but the <em>relation to “values.”</em>
+So far as the single historical facts can be related to values,
+they are of historical importance, and in such a way only
+does history in its proper sense become important in itself
+and through itself at the same time. Must history always
+lose its historical aspect to become of importance to human
+knowledge? That is the question we asked whilst considering
+the general logical types of the “evolution” and
+“cumulation” that arose out of the analysis of the
+historical facts of problematic phylogeny. It now might
+seem that this question may be answered, and that it may
+be answered by a clear and simple “No.” The history
+of mankind, according to Rickert, seems to be important
+in itself, and without borrowing from any other branch
+of study. But is his reasoning altogether cogent and
+convincing?</p>
+
+<p>Has it really been able to attribute to history in the
+strictest sense such an importance for philosophy, for the
+theory of the universe, “für die Weltanschauung,” that
+history proper may in fact be allowed to take its place
+beside science proper?</p>
+
+<p>The relation to values is not to include any kind of
+“Bewertung” of judgment, Rickert allows. In fact, history<span class="pagenum" title="318"><a name="Page_318" id="Page_318"></a></span>
+of any kind would hardly satisfy the reader, if moral
+judgment were its basis. Every reader, of course, has a
+moral judgment of his own, but, unfortunately, almost
+every reader’s judgment is different from his neighbour’s,
+and there is no uniformity of moral principles as there
+is of geometrical ones. We shall come back to this point.
+At present we only state the fact that indeed moral
+judgment can never be the foundation of history, and that
+Rickert was very right to say so: it is enough to put the
+names of Tolstoy and Nietzsche together to understand
+how devoid of even the smallest general validity would be
+a history resting upon moral principles.</p>
+
+<p>But what then are the “values” of Rickert to which
+history has to relate, if moral values in their proper sense
+have to be excluded? It is here that his discussions
+begin to become obscure and unsatisfactory, and the
+reason is fairly intelligible. He is trying to prove the
+impossible; he wants to put history beside science in its
+real philosophical importance, in spite of the fact that
+all evidence to establish this is wanting.</p>
+
+<p>These “values,” to which every historical act in its
+singularity has to be related in order to become an
+element of real history, are they after all nothing but those
+groups of the products of civilisation which in fact absorb
+the interest of men? Is it to groups of cultural
+phenomena, such as arts, science, the State, religion, war,
+economics, and so on, that “historical” facts have to be
+related? Yes, as far as I understand our author, it is
+simply to these or other even less important groups of
+cultural effects&mdash;cultural “cumulations,” to apply our term&mdash;that
+a single action of a man or a group of men<span class="pagenum" title="319"><a name="Page_319" id="Page_319"></a></span>
+must bear some relation in order to become important
+historically.</p>
+
+<p>But what does that mean? Is the relation to such
+“values” to be regarded as really rendering history equal
+to the sciences of nature in philosophical importance?</p>
+
+<p>In the first place, there is no more agreement about
+such “values” than there is in the field of morals. Imagine,
+for instance, a religious enthusiast or recluse writing
+history! I fancy there would be very little mention of
+warriors and politicians: war and politics would not be
+“values” in <em>any</em> sense to such a man. And we know that
+there are others to whom those products of civilised life
+rank amongst the first. Rickert well notes that there is
+one great objection to his doctrine&mdash;the character of
+<span class="nowrap">universality<a name="FNanchor_167_167" id="FNanchor_167_167"></a><a href="#Footnote_167_167" class="fnanchor">167</a></span> is wanting to his history, or rather to the
+values forming its basis; for there cannot be, or at least
+there actually is not at present, a <i lang="la" xml:lang="la">consensus omnium</i> with
+regard to these “values.”</p>
+
+<p>I am convinced that Rickert is right in his conception
+of real “history” as the knowledge of the single acts of
+mankind. But this conception proves just the contrary
+of what Rickert hoped to prove; for history in this
+sense is moulded by the actual products of culture, that
+is, by the effects which actually exist as groups of cultural
+processes, and it cannot be moulded by anything else;
+the historian correlates history with what <em>interests</em> him
+personally.</p>
+
+<p>Here now we have met definitively the ambiguous
+word: history indeed is to end in “interest” and in being<span class="pagenum" title="320"><a name="Page_320" id="Page_320"></a></span>
+“interesting.” There is nothing like a real “value” in
+any sense underlying history; the word <em>value</em> therefore
+would better give place to the term “centre of interest”&mdash;a
+collection of stamps may be such a “centre.” History,
+then, as the knowledge of cultural singularities, is “interesting,”
+and its aspects change with the interests of the
+person who writes history: there is no commonly accepted
+foundation of <span class="nowrap">history.<a name="FNanchor_168_168" id="FNanchor_168_168"></a><a href="#Footnote_168_168" class="fnanchor">168</a></span></p>
+
+<p>And it follows that history as regarded by Rickert cannot
+serve as the preliminary to philosophy. It <em>may</em> <span class="nowrap">be<a name="FNanchor_169_169" id="FNanchor_169_169"></a><a href="#Footnote_169_169" class="fnanchor">169</a></span> of
+use for personal edification or for practical life: granting
+that the “centres of interest” as referred to are of any real
+ethical or at least factual importance. But you may take
+away from history even the greatest personalities, and your
+view of the universe, your philosophy, would remain the
+same, except of course so far as these personalities themselves
+have contributed to philosophy in any way.</p>
+
+<p>Now, on the other hand, it is worth noticing that, even
+if there were generally accepted “values,” history as the
+doctrine of singularities would be deprived of philosophical
+importance. Its single cases would then be merely <em>instances</em>
+of certain types of actions and occurrences which have been<span class="pagenum" title="321"><a name="Page_321" id="Page_321"></a></span>
+proved to be “valuable,” <i>i.e.</i> to be centres of interest, before-hand.
+Rickert has observed that the relation to any judgments
+about moral values would render history unhistorical,
+for the generalities to which it is related would be the
+main thing in such a case. But he did not notice, as far as
+I can see, that history, if related to <em>any</em> “values” whatever&mdash;if
+there were any generally conceded&mdash;would become
+“non-historical” just as well: for the <em>generalities</em> as expressed
+in the “values” would be the main thing in this
+case also. In fact, there is no escape from the dilemma:&mdash;either
+no general centres of interest, and therefore a
+mere subjective “history”; or general “values,” and therefore
+history a mere collection of instances.</p>
+
+<p>The “limits of concepts in natural sciences” then are
+the same as the limits of <em>intellectual</em> concepts in general.
+For intellectual, <i>i.e.</i> logical, “values” are the only centres of
+interest that can lay claim to universality. There are
+indeed other groups of important concepts, the ethical ones,
+but they are outside intellectuality and may enter philosophy
+only as problems, not as solutions. Therefore, history in
+its true sense, even if related to the ethical group of
+concepts, has no bearing on philosophy. Philosophically
+it remains a sum of contingencies, in which certain laws
+of cumulation and certain series of cumulation may be
+discovered. But these series and these laws, if taken
+scientifically, only offer us instances of psychological
+elementalities. They also might be instances of primary
+ethical states and relations, if there were such relations of
+more than a mere subjective and personal validity, which
+at present at least seems not to be the case.</p>
+
+<hr class="short" />
+
+<p><span class="pagenum" title="322"><a name="Page_322" id="Page_322"></a></span></p>
+
+
+
+
+<h3><span class="smcap">Conclusions about Systematics and History in
+General</span></h3>
+
+
+<p>We have finished our analysis of the history of mankind
+as the only instance of an historical biological process
+that is actually known to exist and is not only assumed
+hypothetically.</p>
+
+<p>What we have learnt from this analysis, though certainly
+important in itself, has not afforded us any new result for
+theoretical biology.</p>
+
+<p>The history of mankind is proved to be of philosophical
+importance, at present, so far only as it offers instances
+to the science of psychology; besides that it may be of
+value and importance to many conditions of practical and
+emotional life.</p>
+
+<p>There is only one science, and only one kind of logic
+too. “In one sense the only science”&mdash;that was the
+predicate attached to natural sciences by Lord Gifford, as
+you will remember from our first lecture. It is not
+without interest to note that at the end of our course of
+this year, we find occasion to realise on what a deep insight
+into logical and philosophical relations that sentence was
+grounded.</p>
+
+<p>We now leave the theory of human history, which has
+been to us nothing more than a branch of biological<span class="pagenum" title="323"><a name="Page_323" id="Page_323"></a></span>
+phylogeny in general. We have dealt with it from quite
+a simple realistic point of view, not burdened by any
+epistemology. We have taken psychical states as realities,
+just as we have taken as realities all parts of the animal
+body; and it seems to me that we were entitled to do so,
+as it was only history <em>about</em> the actions of men we were
+dealing with, not their actions themselves. Next summer
+we shall begin with studying action as action, and then, in
+fact, a well-founded epistemology will be among our first
+requirements. And history also will come on the scene
+once more.</p>
+
+<p>It is the main result of our last chapters, devoted to
+systematics, transformism, and human history in particular,
+that no conclusions really useful for further philosophical
+discussion can at present be gained from these topics;
+there either is too little actual knowledge, or there are only
+combinations of natural elementalities, but no elementalities
+of any new kind.</p>
+
+<p>To sum up: we expected that a rational system might
+be a biological result of the future, but we could not claim
+at all to possess such a system. We said that transformism
+might be proved one day to be a true evolution, governed
+by one immanent principle, which then would have to be
+regarded as a new primary factor in nature, but we did not
+know the least about that principle.</p>
+
+<p>Human history, on the other hand&mdash;that is, the only
+historical process concerned with life that is actually
+known to have occurred&mdash;could not teach us anything of
+an elemental character, since human history, at present at
+least, did not appear to us as a true evolution, but only as a
+sum of cumulations, and the singularities of this history,<span class="pagenum" title="324"><a name="Page_324" id="Page_324"></a></span>
+taken by themselves, could only be of practical or emotional
+interest.</p>
+
+<p>Thus it is from the study of the living <em>individual</em> only,
+that we have so far gained elemental principles in biology.
+The analysis of individual morphogenesis and of individual
+inheritance has yielded us the concept of entelechy as the
+chief result of the first part of our lectures. We shall be
+able to get more proofs of the autonomy of the individual
+life in the beginning of the second part; indeed, the
+beginning of that part will bring us to a full understanding
+of what the living individual is, and what it is not. And
+then the real philosophy of life, that is, the philosophy of
+the individual, will occupy us for the greater half of our
+lectures of next summer.</p>
+
+<hr class="chap" />
+
+<p><span class="pagenum" title="325"><a name="Page_325" id="Page_325"></a></span></p>
+
+
+
+
+<h2>INDEX</h2>
+
+
+<p>
+Absolute, <a href="#Page_5">5</a><br />
+Acclimatisation, <a href="#Page_191">191</a><br />
+Acquired characters, <a href="#Page_217">217</a>, <a href="#Page_276">276</a> f.<br />
+Adaptation (definition), <a href="#Page_166">166</a>, <a href="#Page_171">171</a>, <a href="#Page_185">185</a><br />
+<span class="ml1em">to changes from without, <a href="#Page_172">172</a> ff.</span><br />
+<span class="ml1em">functional, <a href="#Page_114">114</a>, <a href="#Page_176">176</a> ff.</span><br />
+<span class="ml1em">and Lamarckism, <a href="#Page_272">272</a>, <a href="#Page_280">280</a></span><br />
+<span class="ml1em">mechanical, <a href="#Page_177">177</a> f.</span><br />
+<span class="ml1em">morphological, <a href="#Page_168">168</a> ff.</span><br />
+<span class="ml1em">physiological, <a href="#Page_184">184</a> ff.</span><br />
+<span class="ml1em">primary and secondary, <a href="#Page_188">188</a> f.</span><br />
+Adaptedness, <a href="#Page_186">186</a> f.<br />
+<i>Adiantum</i>, <a href="#Page_279">279</a><br />
+Adventitious, <a href="#Page_55">55</a>, <a href="#Page_74">74</a>, <a href="#Page_111">111</a>, <a href="#Page_221">221</a><br />
+Albumen, <a href="#Page_200">200</a><br />
+Allelomorphs, <a href="#Page_231">231</a><br />
+Amphibious plants, <a href="#Page_172">172</a> ff.<br />
+Annelids, <a href="#Page_65">65</a>, <a href="#Page_70">70</a>, <a href="#Page_221">221</a><br />
+Answering reaction, <a href="#Page_181">181</a><br />
+Anti-bodies, <a href="#Page_206">206</a> f.<br />
+Antitoxins, <a href="#Page_207">207</a> f.<br />
+<i>A priori</i>, <a href="#Page_6">6</a><br />
+Aristotle, <a href="#Page_144">144</a><br />
+<i>Ascaris</i>, <a href="#Page_93">93</a><br />
+<i>Aspergillus</i>, <a href="#Page_195">195</a><br />
+Assimilation, <a href="#Page_17">17</a><br />
+Atrophy, <a href="#Page_178">178</a><br />
+Autonomy of life, <a href="#Page_143">143</a>, <a href="#Page_224">224</a> f., <a href="#Page_324">324</a><br />
+<br />
+Babák, <a href="#Page_177">177</a><br />
+Baer, C. E. v., <a href="#Page_48">48</a> f. 282<br />
+Bateson, <a href="#Page_229">229</a> ff., <a href="#Page_238">238</a><br />
+Bayliss, <a href="#Page_204">204</a>, <a href="#Page_212">212</a><br />
+<i>Begonia</i>, <a href="#Page_221">221</a><br />
+Bergson, <a href="#Page_305">305</a><br />
+Berkeley, <a href="#Page_6">6</a><br />
+Berthold, <a href="#Page_91">91</a><br />
+Biogenetisches Grundgesetz, <a href="#Page_248">248</a><br />
+Biology, <a href="#Page_8">8</a> ff., <a href="#Page_15">15</a> f.<br />
+Blaringhem, <a href="#Page_238">238</a>, <a href="#Page_276">276</a><br />
+Blastoderm, <a href="#Page_39">39</a><br />
+Blastomeres, <a href="#Page_36">36</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a> f., <a href="#Page_79">79</a><br />
+Blastula, <a href="#Page_37">37</a>, <a href="#Page_61">61</a>, <a href="#Page_79">79</a><br />
+Blumenbach, <a href="#Page_26">26</a><br />
+Boirivant, <a href="#Page_174">174</a><br />
+Bonnet, <a href="#Page_26">26</a><br />
+Boveri, <a href="#Page_29">29</a>, <a href="#Page_60">60</a>, <a href="#Page_95">95</a>, <a href="#Page_235">235</a> f.<br />
+Buckle, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Bunge, v., <a href="#Page_248">248</a><br />
+Bütschli, <a href="#Page_91">91</a><br />
+<br />
+Calcium, <a href="#Page_97">97</a><br />
+Calkins, <a href="#Page_33">33</a><br />
+Cambium, <a href="#Page_120">120</a>, <a href="#Page_183">183</a>, <a href="#Page_220">220</a><br />
+Catalysis, <a href="#Page_164">164</a>, <a href="#Page_203">203</a><br />
+Categories, <a href="#Page_6">6</a> f.<br />
+Cause, <a href="#Page_99">99</a> ff.<br />
+Cell, <a href="#Page_27">27</a> f.<br />
+<span class="ml1em">-division, <a href="#Page_28">28</a> ff., <a href="#Page_53">53</a>, <a href="#Page_94">94</a></span><br />
+<span class="ml1em">-lineage, <a href="#Page_58">58</a>, <a href="#Page_70">70</a></span><br />
+<span class="ml1em">-theory, <a href="#Page_27">27</a> f.</span><br />
+Chemical theory (of morphogenesis), <a href="#Page_134">134</a> ff.<br />
+Chemistry, systematics of, <a href="#Page_244">244</a>.<br />
+Child, C. M., <a href="#Page_180">180</a><br />
+Chromatic regulations, <a href="#Page_197">197</a><br />
+Chromatin, <a href="#Page_28">28</a> f.<br />
+Chromosomes, <a href="#Page_30">30</a>, <a href="#Page_237">237</a><br />
+Chun, <a href="#Page_66">66</a><br />
+Classification, <a href="#Page_246">246</a> f.<br />
+<i>Clavellina</i>, <a href="#Page_129">129</a>, <a href="#Page_154">154</a>, <a href="#Page_162">162</a> f.<br />
+Cleavage, <a href="#Page_35">35</a> ff., <a href="#Page_53">53</a>, <a href="#Page_58">58</a>, <a href="#Page_60">60</a>, <a href="#Page_63">63</a>, <a href="#Page_71">71</a>, <a href="#Page_92">92</a><br />
+Colloids, <a href="#Page_187">187</a><br />
+Compensatory process, <a href="#Page_112">112</a><br />
+Complex potencies, <a href="#Page_112">112</a>, <a href="#Page_120">120</a><br />
+Conic sections, <a href="#Page_243">243</a><br />
+Conjugation, <a href="#Page_33">33</a><br />
+Conklin, <a href="#Page_86">86</a><br />
+Contingency, <a href="#Page_218">218</a>, <a href="#Page_284">284</a> ff. 304<br />
+Continuity of germ-plasm, <a href="#Page_215">215</a>, <a href="#Page_227">227</a><br />
+<span class="pagenum" title="326"><a name="Page_326" id="Page_326"></a></span><br />
+Cope, <a href="#Page_273">273</a><br />
+Correlation (of masses), <a href="#Page_93">93</a><br />
+<span class="ml1em">(of parts), <a href="#Page_247">247</a></span><br />
+Correns, <a href="#Page_228">228</a><br />
+Crampton, <a href="#Page_70">70</a> f.<br />
+Crayfish, <a href="#Page_105">105</a><br />
+Ctenophores, <a href="#Page_66">66</a><br />
+Cumulation, <a href="#Page_301">301</a> ff., <a href="#Page_308">308</a> ff., <a href="#Page_314">314</a>, <a href="#Page_317">317</a><br />
+Cuvier, <a href="#Page_247">247</a><br />
+<br />
+Darwin, Ch., <a href="#Page_260">260</a> ff., <a href="#Page_271">271</a>, <a href="#Page_283">283</a><br />
+Darwinism, <a href="#Page_260">260</a> ff., <a href="#Page_271">271</a>, <a href="#Page_283">283</a> ff., <a href="#Page_293">293</a> ff., <a href="#Page_304">304</a><br />
+Davenport, <a href="#Page_191">191</a>, <a href="#Page_206">206</a><br />
+Delage, <a href="#Page_32">32</a><br />
+Descent, theory of, <a href="#Page_250">250</a> ff.<br />
+Description, <a href="#Page_12">12</a>, <a href="#Page_50">50</a><br />
+Detto, <a href="#Page_172">172</a><br />
+Directive stimuli, <a href="#Page_102">102</a> ff.<br />
+Doncaster, <a href="#Page_232">232</a><br />
+Dreyer, <a href="#Page_92">92</a><br />
+<br />
+<i><a id="Echinus"></a>Echinus</i>, <a href="#Page_27">27</a>, <a href="#Page_33">33</a> ff., <a href="#Page_60">60</a> ff., <a href="#Page_68">68</a>, <a href="#Page_81">81</a>, <a href="#Page_85">85</a>, <a href="#Page_87">87</a>, <a href="#Page_98">98</a>, <a href="#Page_104">104</a>, <a href="#Page_108">108</a>, <a href="#Page_111">111</a>, <a href="#Page_154">154</a>, <a href="#Page_232">232</a>, <a href="#Page_235">235</a><br />
+Ectoderm, <a href="#Page_41">41</a>, <a href="#Page_81">81</a>, <a href="#Page_122">122</a><br />
+Egg, <a href="#Page_31">31</a>, <a href="#Page_33">33</a> f.<br />
+Ehrlich, <a href="#Page_207">207</a> f.<br />
+Eimer, <a href="#Page_292">292</a><br />
+Elementary organs, <a href="#Page_46">46</a> ff.<br />
+<span class="ml1em">processes, <a href="#Page_46">46</a> ff.</span><br />
+Elements of nature, <a href="#Page_9">9</a><br />
+Embryo, <a href="#Page_44">44</a><br />
+<span class="ml1em">frog’s, <a href="#Page_59">59</a>, <a href="#Page_65">65</a>, <a href="#Page_67">67</a></span><br />
+<span class="ml1em">half, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_66">66</a> ff.</span><br />
+<span class="ml1em">whole, <a href="#Page_61">61</a>, <a href="#Page_67">67</a> f.</span><br />
+Endoderm, <a href="#Page_41">41</a>, <a href="#Page_81">81</a><br />
+Entelechy, <a href="#Page_143">143</a> f., <a href="#Page_224">224</a> f., <a href="#Page_295">295</a><br />
+Entwickelungsmechanik, <a href="#Page_57">57</a>, <a href="#Page_70">70</a>, <a href="#Page_78">78</a>, <a href="#Page_241">241</a><br />
+Enumeration, <a href="#Page_297">297</a>, <a href="#Page_300">300</a><br />
+Enzymes, <a href="#Page_164">164</a>, <a href="#Page_203">203</a><br />
+Epigenesis, <a href="#Page_26">26</a>, <a href="#Page_45">45</a>, <a href="#Page_54">54</a>, <a href="#Page_72">72</a>, <a href="#Page_144">144</a>, <a href="#Page_301">301</a><br />
+Equifinality (of restitutions), <a href="#Page_159">159</a> f.<br />
+Equipotential, <a href="#Page_83">83</a><br />
+Eschenhagen, <a href="#Page_195">195</a><br />
+Evolutio, <a href="#Page_26">26</a>, <a href="#Page_45">45</a> f., <a href="#Page_54">54</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_64">64</a>, <a href="#Page_72">72</a>, <a href="#Page_144">144</a>, <a href="#Page_205">205</a>, <a href="#Page_301">301</a><br />
+Evolution, <a href="#Page_8">8</a>, <a href="#Page_21">21</a>, <a href="#Page_46">46</a>, <a href="#Page_250">250</a>, <a href="#Page_301">301</a>, <a href="#Page_305">305</a>, <a href="#Page_311">311</a> ff., <a href="#Page_317">317</a><br />
+Experience, <a href="#Page_7">7</a> f., <a href="#Page_12">12</a>, <a href="#Page_212">212</a><br />
+Experiment, <a href="#Page_51">51</a>, <a href="#Page_56">56</a> f.<br />
+“Explaining,” 51, <a href="#Page_309">309</a><br />
+Explicit potency, <a href="#Page_84">84</a><br />
+<br />
+Fasting, <a href="#Page_199">199</a> f.<br />
+Ferments, <a href="#Page_164">164</a>, <a href="#Page_203">203</a> f.<br />
+Fertilisation, <a href="#Page_32">32</a> ff.<br />
+Fischer, <a href="#Page_278">278</a><br />
+Foges, <a href="#Page_107">107</a><br />
+Form, closed or open, <a href="#Page_49">49</a><br />
+Form, organic, specific, <a href="#Page_16">16</a> ff., <a href="#Page_25">25</a>, <a href="#Page_92">92</a>, <a href="#Page_293">293</a> ff.<br />
+Forma accidentalis, <a href="#Page_293">293</a><br />
+<span class="ml1em">essentialis, <a href="#Page_294">294</a> f.</span><br />
+Formative stimuli, <a href="#Page_102">102</a> ff., <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_133">133</a><br />
+Francé, <a href="#Page_158">158</a>, <a href="#Page_239">239</a><br />
+Frédéricq, <a href="#Page_196">196</a><br />
+Frog, embryo of, <a href="#Page_59">59</a>, <a href="#Page_65">65</a>, <a href="#Page_67">67</a><br />
+Fromm, <a href="#Page_205">205</a><br />
+Function (mathematical), <a href="#Page_80">80</a><br />
+Fungi, metabolism of, <a href="#Page_201">201</a><br />
+<br />
+Gaidukow, <a href="#Page_197">197</a> f.<br />
+Galls, <a href="#Page_101">101</a><br />
+Galton, <a href="#Page_228">228</a>, <a href="#Page_238">238</a><br />
+Gamble and Keeble, <a href="#Page_198">198</a><br />
+Gastrula, <a href="#Page_41">41</a>, <a href="#Page_61">61</a>, <a href="#Page_81">81</a><br />
+Gautier, <a href="#Page_239">239</a><br />
+Geographical distribution, <a href="#Page_251">251</a> f.<br />
+Geometry, solid, <a href="#Page_243">243</a><br />
+Germ-layers, <a href="#Page_41">41</a>, <a href="#Page_44">44</a>, <a href="#Page_61">61</a><br />
+<span class="ml1em">-lineage, <a href="#Page_215">215</a></span><br />
+<span class="ml1em">-plasm, <a href="#Page_52">52</a>, <a href="#Page_215">215</a></span><br />
+Gifford, Lord, <a href="#Page_1">1</a> ff., <a href="#Page_322">322</a><br />
+Godlewski, <a href="#Page_105">105</a>, <a href="#Page_155">155</a>, <a href="#Page_235">235</a><br />
+Goebel, <a href="#Page_116">116</a><br />
+Goethe, <a href="#Page_247">247</a><br />
+Goette, <a href="#Page_48">48</a>, <a href="#Page_56">56</a>, <a href="#Page_214">214</a><br />
+Goltz, <a href="#Page_181">181</a><br />
+Growth, <a href="#Page_30">30</a>, <a href="#Page_93">93</a> f.<br />
+Gruber, <a href="#Page_236">236</a><br />
+<br />
+Haeckel, <a href="#Page_37">37</a>, <a href="#Page_41">41</a><br />
+Half-embryo, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_66">66</a> ff.<br />
+Haller, A. v., <a href="#Page_26">26</a><br />
+Harmony, <a href="#Page_107">107</a> ff., <a href="#Page_117">117</a>, <a href="#Page_295">295</a><br />
+Hausmann, <a href="#Page_206">206</a><br />
+Heat production, <a href="#Page_193">193</a><br />
+Hegel, <a href="#Page_307">307</a>, <a href="#Page_311">311</a> ff.<br />
+Herbst, <a href="#Page_96">96</a> ff., <a href="#Page_102">102</a>, <a href="#Page_104">104</a> ff., <a href="#Page_172">172</a>, <a href="#Page_177">177</a>, <a href="#Page_200">200</a>, <a href="#Page_232">232</a>, <a href="#Page_236">236</a><br />
+Heredity, <a href="#Page_21">21</a>, <a href="#Page_52">52</a><br />
+Hering, <a href="#Page_216">216</a> f.<br />
+Hertwig, O., <a href="#Page_60">60</a>, <a href="#Page_65">65</a><br />
+Hertwig, R., <a href="#Page_32">32</a> f., <a href="#Page_60">60</a>, <a href="#Page_107">107</a><br />
+His, <a href="#Page_56">56</a>, <a href="#Page_93">93</a><br />
+History, <a href="#Page_2">2</a>, <a href="#Page_14">14</a>, <a href="#Page_21">21</a>, <a href="#Page_250">250</a>, <a href="#Page_257">257</a>, <a href="#Page_297">297</a> ff.<br />
+<span class="ml1em">of mankind, <a href="#Page_306">306</a> ff.</span><br />
+Holmes, <a href="#Page_180">180</a><br />
+Hume, <a href="#Page_6">6</a><br />
+Hypertrophy, <a href="#Page_112">112</a>, <a href="#Page_114">114</a><br />
+Hypertypy, <a href="#Page_112">112</a><br />
+<span class="pagenum" title="327"><a name="Page_327" id="Page_327"></a></span><br />
+Idealism, <a href="#Page_5">5</a>, <a href="#Page_7">7</a><br />
+Immunity, <a href="#Page_204">204</a> ff.<br />
+Implicit potency, <a href="#Page_84">84</a><br />
+Improvement (of morphogenesis), <a href="#Page_212">212</a><br />
+Indifferent cells, <a href="#Page_182">182</a><br />
+Inflammation, <a href="#Page_206">206</a><br />
+Inheritance, <a href="#Page_35">35</a>, <a href="#Page_214">214</a> ff.<br />
+<span class="ml1em">of acquired characters, <a href="#Page_217">217</a>, <a href="#Page_275">275</a> ff., <a href="#Page_290">290</a></span><br />
+Irritability, <a href="#Page_190">190</a> ff.<br />
+<br />
+Jacoby, <a href="#Page_207">207</a><br />
+Jaeger, <a href="#Page_214">214</a><br />
+Jennings, <a href="#Page_218">218</a><br />
+<br />
+Kammerer, <a href="#Page_176">176</a>, <a href="#Page_280">280</a><br />
+Kant, <a href="#Page_6">6</a> f.<br />
+Kirchhoff, <a href="#Page_50">50</a><br />
+Klebs, <a href="#Page_96">96</a>, <a href="#Page_170">170</a>, <a href="#Page_180">180</a>, <a href="#Page_238">238</a>, <a href="#Page_276">276</a><br />
+Kölliker, <a href="#Page_292">292</a><br />
+Korshinsky, <a href="#Page_239">239</a><br />
+Krašan, <a href="#Page_221">221</a>, <a href="#Page_251">251</a><br />
+<br />
+Lamarck, <a href="#Page_271">271</a> f., <a href="#Page_291">291</a><br />
+Lamarckism, <a href="#Page_271">271</a> f., <a href="#Page_284">284</a> ff., <a href="#Page_293">293</a> ff., <a href="#Page_304">304</a><br />
+Lamprecht, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Larva, <a href="#Page_41">41</a> f., <a href="#Page_44">44</a><br />
+Law of nature, <a href="#Page_13">13</a>, <a href="#Page_16">16</a><br />
+Leibniz, <a href="#Page_6">6</a><br />
+Lens (of eye), <a href="#Page_105">105</a>, <a href="#Page_221">221</a><br />
+Liebmann, <a href="#Page_256">256</a><br />
+Life, <a href="#Page_9">9</a> f., <a href="#Page_16">16</a>, <a href="#Page_21">21</a><br />
+Lillie, R. S., <a href="#Page_236">236</a><br />
+Limits of regulability, <a href="#Page_212">212</a><br />
+Lithium, <a href="#Page_99">99</a><br />
+“Living,” 9, <a href="#Page_16">16</a><br />
+Localisation, <a href="#Page_101">101</a>, <a href="#Page_103">103</a>, <a href="#Page_118">118</a> ff.<br />
+Locke, <a href="#Page_6">6</a><br />
+Loeb, J., <a href="#Page_32">32</a>, <a href="#Page_102">102</a>, <a href="#Page_164">164</a>, <a href="#Page_179">179</a>, <a href="#Page_196">196</a>, <a href="#Page_236">236</a><br />
+Loeb, L., <a href="#Page_208">208</a><br />
+Lyon, <a href="#Page_87">87</a><br />
+<br />
+MacDougal, <a href="#Page_238">238</a> f., <a href="#Page_276">276</a><br />
+Machine (definition), <a href="#Page_139">139</a><br />
+Machine-theory of life, <a href="#Page_138">138</a> ff., <a href="#Page_187">187</a>, <a href="#Page_210">210</a><br />
+Maillard, <a href="#Page_196">196</a><br />
+Manifoldness, <a href="#Page_25">25</a> f., <a href="#Page_30">30</a>, <a href="#Page_45">45</a><br />
+<span class="ml1em">intensive, <a href="#Page_144">144</a></span><br />
+Materialism, <a href="#Page_283">283</a><br />
+Materials, transport of, <a href="#Page_194">194</a><br />
+Matter, theory of, <a href="#Page_8">8</a><br />
+Maturation, <a href="#Page_31">31</a>, <a href="#Page_87">87</a><br />
+Mayenburg, v., <a href="#Page_195">195</a><br />
+Means, of morphogenesis, <a href="#Page_89">89</a> ff., <a href="#Page_101">101</a>, <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_228">228</a>, <a href="#Page_234">234</a><br />
+Memory, <a href="#Page_216">216</a> f.<br />
+Mendel, <a href="#Page_229">229</a> f.<br />
+Merrifield, <a href="#Page_198">198</a><br />
+Mesenchyme, <a href="#Page_39">39</a>, <a href="#Page_41">41</a>, <a href="#Page_104">104</a>, <a href="#Page_111">111</a>, <a href="#Page_151">151</a> f.<br />
+Metabolic regulations, <a href="#Page_198">198</a> f.<br />
+Metabolism, <a href="#Page_16">16</a>, <a href="#Page_184">184</a><br />
+<span class="ml1em">of fungi, <a href="#Page_201">201</a></span><br />
+Metschnikoff, <a href="#Page_206">206</a><br />
+Micromeres, <a href="#Page_36">36</a>, <a href="#Page_60">60</a><br />
+Miehe, <a href="#Page_116">116</a><br />
+Mill, J. S., <a href="#Page_57">57</a><br />
+<i>Mimosa</i>, <a href="#Page_191">191</a><br />
+Minkiewicz, <a href="#Page_198">198</a><br />
+Modification, <a href="#Page_277">277</a><br />
+Molluscs, <a href="#Page_70">70</a> f., <a href="#Page_86">86</a><br />
+Morgan, T. H., <a href="#Page_32">32</a>, <a href="#Page_66">66</a> f., <a href="#Page_95">95</a>, <a href="#Page_107">107</a>, <a href="#Page_114">114</a> f., <a href="#Page_162">162</a>, <a href="#Page_230">230</a><br />
+Morphaesthesia, <a href="#Page_157">157</a><br />
+Morphogenesis, <a href="#Page_20">20</a>, <a href="#Page_52">52</a>, <a href="#Page_76">76</a>, <a href="#Page_112">112</a>, <a href="#Page_118">118</a> f.<br />
+Morphology, <a href="#Page_12">12</a><br />
+Movements, organic, <a href="#Page_17">17</a><br />
+Mutations, <a href="#Page_237">237</a> f., <a href="#Page_276">276</a>, <a href="#Page_291">291</a><br />
+<br />
+Nägeli, <a href="#Page_266">266</a>, <a href="#Page_292">292</a><br />
+Nathansohn, <a href="#Page_196">196</a><br />
+Natural selection, <a href="#Page_261">261</a> f., <a href="#Page_290">290</a><br />
+Nature, <a href="#Page_5">5</a> ff.<br />
+Němec, <a href="#Page_116">116</a><br />
+Newport, <a href="#Page_57">57</a><br />
+Newt (regeneration of), <a href="#Page_155">155</a>, <a href="#Page_221">221</a> f.<br />
+Noll, <a href="#Page_146">146</a>, <a href="#Page_157">157</a> f.<br />
+Nomothetic, <a href="#Page_14">14</a> f.<br />
+Normal, <a href="#Page_78">78</a><br />
+Nuclear division, <a href="#Page_28">28</a> f., <a href="#Page_62">62</a>, <a href="#Page_64">64</a> f., <a href="#Page_72">72</a>, <a href="#Page_235">235</a><br />
+Nucleus, <a href="#Page_28">28</a>, <a href="#Page_35">35</a><br />
+<span class="ml1em">rôle of nucleus in inheritance, <a href="#Page_233">233</a> f.</span><br />
+<br />
+Organ-forming substances, <a href="#Page_117">117</a><br />
+<i>Oscillariae</i>, <a href="#Page_197">197</a><br />
+Osmotic pressure, <a href="#Page_93">93</a>, <a href="#Page_187">187</a>, <a href="#Page_194">194</a> f.<br />
+Overton, <a href="#Page_196">196</a> f.<br />
+Oxidation, rôle of, <a href="#Page_198">198</a> f.<br />
+<br />
+Palaeontology, <a href="#Page_252">252</a><br />
+Parallelism (psycho-physical), <a href="#Page_146">146</a><br />
+Parthenogenesis, <a href="#Page_32">32</a><br />
+Pauly, <a href="#Page_146">146</a>, <a href="#Page_217">217</a>, <a href="#Page_273">273</a> f.<br />
+Pawlow, <a href="#Page_204">204</a>, <a href="#Page_210">210</a>, <a href="#Page_212">212</a><br />
+Pearl, R., <a href="#Page_212">212</a><br />
+Pfeffer, <a href="#Page_195">195</a>, <a href="#Page_201">201</a><br />
+Phagocytosis, <a href="#Page_206">206</a><br />
+Phenomenon, <a href="#Page_5">5</a> f.<br />
+Philosophy, natural, <a href="#Page_4">4</a><br />
+<span class="ml1em">of nature, <a href="#Page_4">4</a>, <a href="#Page_7">7</a>, <a href="#Page_9">9</a></span><br />
+<span class="ml1em">of the organism, <a href="#Page_9">9</a>, <a href="#Page_15">15</a></span><br />
+Phylogeny, <a href="#Page_255">255</a>, <a href="#Page_291">291</a>, <a href="#Page_297">297</a>, <a href="#Page_304">304</a> ff.<br />
+<span class="pagenum" title="328"><a name="Page_328" id="Page_328"></a></span><br />
+Physiology, <a href="#Page_12">12</a><br />
+<span class="ml1em">of development (morphogenesis), <a href="#Page_20">20</a></span><br />
+<i>Planaria</i>, <a href="#Page_130">130</a>, <a href="#Page_155">155</a>, <a href="#Page_162">162</a> f., <a href="#Page_200">200</a><br />
+Plants, <a href="#Page_48">48</a> f.<br />
+Plato, <a href="#Page_2">2</a><br />
+Pluteus, <a href="#Page_42">42</a><br />
+Poisons, <a href="#Page_205">205</a> ff.<br />
+Pole, <a href="#Page_36">36</a><br />
+Polarity, <a href="#Page_106">106</a><br />
+Potencies, complex, <a href="#Page_112">112</a>, <a href="#Page_120">120</a><br />
+<span class="ml1em">explicit, <a href="#Page_84">84</a></span><br />
+<span class="ml1em">implicit, <a href="#Page_84">84</a></span><br />
+<span class="ml1em">primary, <a href="#Page_84">84</a>, <a href="#Page_111">111</a></span><br />
+<span class="ml1em">prospective, <a href="#Page_77">77</a> ff., <a href="#Page_83">83</a>, <a href="#Page_89">89</a>, <a href="#Page_118">118</a>, <a href="#Page_125">125</a>, <a href="#Page_241">241</a></span><br />
+<span class="ml1em">secondary, <a href="#Page_84">84</a>, <a href="#Page_110">110</a></span><br />
+Poulton, <a href="#Page_198">198</a><br />
+Precipitin, <a href="#Page_207">207</a> f.<br />
+Pressure experiments, <a href="#Page_63">63</a>, <a href="#Page_141">141</a><br />
+Primary potency, <a href="#Page_84">84</a>, <a href="#Page_111">111</a><br />
+<span class="ml1em">purposefulness, <a href="#Page_146">146</a>, <a href="#Page_287">287</a></span><br />
+<span class="ml1em">regulation, <a href="#Page_85">85</a>, <a href="#Page_174">174</a>, <a href="#Page_188">188</a></span><br />
+Progress, <a href="#Page_305">305</a><br />
+Pronuclei, <a href="#Page_55">55</a><br />
+Prospective potency, <a href="#Page_77">77</a> ff., <a href="#Page_83">83</a>, <a href="#Page_89">89</a>, <a href="#Page_118">118</a>, <a href="#Page_125">125</a>, <a href="#Page_241">241</a><br />
+<span class="ml1em">value, <a href="#Page_77">77</a> f., <a href="#Page_80">80</a>, <a href="#Page_122">122</a></span><br />
+Protista (Protozoa), <a href="#Page_27">27</a>, <a href="#Page_130">130</a>, <a href="#Page_236">236</a><br />
+Protoplasm, <a href="#Page_28">28</a>, <a href="#Page_30">30</a><br />
+<span class="ml1em">morphogenetic rôle of, <a href="#Page_67">67</a></span><br />
+Przibram, <a href="#Page_112">112</a>, <a href="#Page_248">248</a><br />
+<br />
+Rádl, <a href="#Page_247">247</a><br />
+Rauber, <a href="#Page_235">235</a><br />
+Reaction, answering, <a href="#Page_181">181</a><br />
+Reciprocity of harmony, <a href="#Page_156">156</a> f.<br />
+Re-differentiation, <a href="#Page_75">75</a>, <a href="#Page_111">111</a>, <a href="#Page_163">163</a><br />
+Regeneration, <a href="#Page_55">55</a>, <a href="#Page_74">74</a>, <a href="#Page_105">105</a>, <a href="#Page_111">111</a>, <a href="#Page_221">221</a><br />
+<span class="ml1em">super-, <a href="#Page_115">115</a> f.</span><br />
+Regulation, <a href="#Page_68">68</a>, <a href="#Page_73">73</a>, <a href="#Page_85">85</a>, <a href="#Page_111">111</a>, <a href="#Page_165">165</a><br />
+<span class="ml1em">defined, <a href="#Page_166">166</a></span><br />
+<span class="ml1em">metabolic, <a href="#Page_198">198</a> f.</span><br />
+<span class="ml1em">secondary, <a href="#Page_85">85</a>, <a href="#Page_165">165</a>, <a href="#Page_188">188</a></span><br />
+Reinke, <a href="#Page_146">146</a><br />
+Restitution, <a href="#Page_21">21</a>, <a href="#Page_74">74</a>, <a href="#Page_110">110</a>, <a href="#Page_112">112</a> ff.<br />
+<span class="ml1em">defined, <a href="#Page_166">166</a></span><br />
+<span class="ml1em">and Darwinism, <a href="#Page_267">267</a></span><br />
+<span class="ml1em">and Lamarckism, <a href="#Page_286">286</a></span><br />
+<span class="ml1em">of second order, <a href="#Page_158">158</a></span><br />
+Retina, <a href="#Page_191">191</a><br />
+Retro-differentiation, <a href="#Page_163">163</a> f.<br />
+Rhumbler, <a href="#Page_93">93</a><br />
+Ribbert, <a href="#Page_114">114</a><br />
+Rickert, <a href="#Page_315">315</a> ff.<br />
+Roux, <a href="#Page_26">26</a>, <a href="#Page_48">48</a>, <a href="#Page_55">55</a> ff., <a href="#Page_66">66</a> f., <a href="#Page_76">76</a>, <a href="#Page_89">89</a>, <a href="#Page_92">92</a> f., <a href="#Page_108">108</a>, <a href="#Page_161">161</a>, <a href="#Page_176">176</a> f., <a href="#Page_241">241</a><br />
+Rubner, <a href="#Page_193">193</a><br />
+<br />
+Sachs, <a href="#Page_117">117</a><br />
+Sadebeck, <a href="#Page_279">279</a><br />
+<i>Salamandra</i>, <a href="#Page_175">175</a>, <a href="#Page_281">281</a><br />
+Schneider, <a href="#Page_146">146</a><br />
+Schultz, E., <a href="#Page_200">200</a><br />
+Schultze, O., <a href="#Page_67">67</a><br />
+Schwendener, <a href="#Page_177">177</a><br />
+Science, <a href="#Page_14">14</a>, <a href="#Page_297">297</a><br />
+<span class="ml1em">natural, <a href="#Page_1">1</a> ff.</span><br />
+<span class="ml1em">rational, <a href="#Page_12">12</a></span><br />
+Sea-urchin, <i>see</i> <a href="#Echinus">Echinus</a><br />
+Secondary potency, <a href="#Page_84">84</a>, <a href="#Page_110">110</a><br />
+<span class="ml1em">regulation, <a href="#Page_85">85</a>, <a href="#Page_165">165</a>, <a href="#Page_188">188</a></span><br />
+Secretion, internal, <a href="#Page_116">116</a>, <a href="#Page_200">200</a><br />
+Segmentation, <a href="#Page_35">35</a><br />
+Selective qualities (of tissues), <a href="#Page_186">186</a><br />
+Self-differentiation, <a href="#Page_108">108</a><br />
+Semon, <a href="#Page_216">216</a> f.<br />
+Sex, <a href="#Page_107">107</a><br />
+Single, the, <a href="#Page_315">315</a> ff.<br />
+Skeleton, <a href="#Page_40">40</a> ff., <a href="#Page_44">44</a>, <a href="#Page_47">47</a>, <a href="#Page_92">92</a><br />
+Spemann, <a href="#Page_105">105</a><br />
+Spermatozoon (spermia), <a href="#Page_32">32</a> ff.<br />
+Splitting (of hybrids), <a href="#Page_229">229</a> f.<br />
+Stahl, <a href="#Page_197">197</a><br />
+Standfuss, <a href="#Page_278">278</a><br />
+Starfish, <a href="#Page_44">44</a>, <a href="#Page_81">81</a>, <a href="#Page_122">122</a><br />
+Starling, E., <a href="#Page_116">116</a>, <a href="#Page_204">204</a>, <a href="#Page_212">212</a><br />
+<i>Stentor</i>, <a href="#Page_131">131</a><br />
+Stimuli, directive, <a href="#Page_102">102</a> ff.<br />
+<span class="ml1em">formative, <a href="#Page_102">102</a> ff., <a href="#Page_113">113</a>, <a href="#Page_118">118</a>, <a href="#Page_133">133</a></span><br />
+<span class="ml1em">of restitutions, <a href="#Page_113">113</a> f.</span><br />
+Structure of protoplasm, <a href="#Page_66">66</a>, <a href="#Page_69">69</a>, <a href="#Page_72">72</a> f. 85, <a href="#Page_88">88</a><br />
+Substance, living, <a href="#Page_17">17</a><br />
+Sumner, <a href="#Page_196">196</a><br />
+Super-regeneration, <a href="#Page_115">115</a> f.<br />
+Surface-tension, <a href="#Page_91">91</a><br />
+Sutton, <a href="#Page_230">230</a><br />
+Symmetry, <a href="#Page_39">39</a>, <a href="#Page_68">68</a>, <a href="#Page_70">70</a>, <a href="#Page_72">72</a>, <a href="#Page_89">89</a>, <a href="#Page_98">98</a><br />
+System, combined types of, <a href="#Page_153">153</a> ff.<br />
+<span class="ml1em">complex, <a href="#Page_219">219</a> f.</span><br />
+<span class="ml1em">complex-harmonious, <a href="#Page_155">155</a></span><br />
+<span class="ml1em">equipotential, <a href="#Page_120">120</a></span><br />
+<span class="ml1em">harmonious-equipotential, <a href="#Page_121">121</a> ff., <a href="#Page_151">151</a> f.</span><br />
+<span class="ml1em">mixed-equipotential, <a href="#Page_154">154</a></span><br />
+<span class="ml1em">morphogenetic, <a href="#Page_119">119</a> f., <a href="#Page_163">163</a>, <a href="#Page_241">241</a></span><br />
+Systematics, <a href="#Page_14">14</a> ff., <a href="#Page_21">21</a>, <a href="#Page_243">243</a> f., <a href="#Page_253">253</a>, <a href="#Page_264">264</a>, <a href="#Page_293">293</a>, <a href="#Page_296">296</a><br />
+<br />
+Taine, <a href="#Page_308">308</a>, <a href="#Page_310">310</a><br />
+Theology, natural, <a href="#Page_1">1</a> ff.<br />
+Thomson, J. A., <a href="#Page_16">16</a><br />
+Thymus, <a href="#Page_204">204</a><br />
+<span class="pagenum" title="329"><a name="Page_329" id="Page_329"></a></span><br />
+Thyroid, <a href="#Page_204">204</a><br />
+Tissue, <a href="#Page_38">38</a><br />
+Toxins, <a href="#Page_207">207</a> f.<br />
+Transformism, <a href="#Page_251">251</a><br />
+Truth, <a href="#Page_7">7</a><br />
+Tschermak, <a href="#Page_228">228</a><br />
+<i>Tubularia</i>, <a href="#Page_126">126</a> ff., <a href="#Page_133">133</a>, <a href="#Page_158">158</a> ff.<br />
+Type, <a href="#Page_48">48</a>, <a href="#Page_247">247</a> f., <a href="#Page_282">282</a>, <a href="#Page_291">291</a><br />
+<br />
+“Understanding” (historically), <a href="#Page_302">302</a><br />
+Universality, postulate of, <a href="#Page_148">148</a> f.<br />
+Universe, <a href="#Page_5">5</a><br />
+Univocality, principle of, <a href="#Page_161">161</a><br />
+<br />
+“Values,” 317 ff.<br />
+<span class="ml1em">prospective, <a href="#Page_77">77</a> f., <a href="#Page_80">80</a>, <a href="#Page_122">122</a></span><br />
+Variation, <a href="#Page_218">218</a>, <a href="#Page_237">237</a> f., <a href="#Page_276">276</a><br />
+Variation, fluctuating, contingent, <a href="#Page_264">264</a> f., <a href="#Page_273">273</a> f., <a href="#Page_282">282</a>, <a href="#Page_290">290</a><br />
+Vernon, <a href="#Page_232">232</a>, <a href="#Page_238">238</a><br />
+Vitalism, <a href="#Page_143">143</a>, <a href="#Page_145">145</a> f., <a href="#Page_210">210</a> f., <a href="#Page_224">224</a> f., <a href="#Page_234">234</a>, <a href="#Page_240">240</a> f., <a href="#Page_272">272</a>, <a href="#Page_277">277</a><br />
+Vöchting, <a href="#Page_174">174</a>, <a href="#Page_179">179</a> f., <a href="#Page_182">182</a>, <a href="#Page_221">221</a><br />
+Volition, acts of, <a href="#Page_274">274</a><br />
+Vries, de, <a href="#Page_228">228</a>, <a href="#Page_238">238</a> f.<br />
+<br />
+Wallace, <a href="#Page_292">292</a><br />
+Ward, J., <a href="#Page_8">8</a>, <a href="#Page_143">143</a><br />
+Weber, law of, <a href="#Page_191">191</a><br />
+Weinland, <a href="#Page_202">202</a><br />
+Weismann, <a href="#Page_33">33</a>, <a href="#Page_52">52</a> ff., <a href="#Page_58">58</a> f., <a href="#Page_72">72</a>, <a href="#Page_74">74</a> f., <a href="#Page_103">103</a>, <a href="#Page_111">111</a>, <a href="#Page_138">138</a>, <a href="#Page_214">214</a> f., <a href="#Page_237">237</a>, <a href="#Page_277">277</a> f.<br />
+Weldon, <a href="#Page_238">238</a><br />
+Whole, the, <a href="#Page_28">28</a>, <a href="#Page_80">80</a>, <a href="#Page_117">117</a><br />
+<span class="ml1em">-embryo, <a href="#Page_61">61</a>, <a href="#Page_67">67</a> f.</span><br />
+Wigand, <a href="#Page_255">255</a>, <a href="#Page_266">266</a>, <a href="#Page_292">292</a><br />
+Wilson, E. B., <a href="#Page_27">27</a>, <a href="#Page_65">65</a>, <a href="#Page_70">70</a> f., <a href="#Page_86">86</a> f., <a href="#Page_107">107</a><br />
+Windelband, <a href="#Page_13">13</a> f.<br />
+Winkler, <a href="#Page_116">116</a>, <a href="#Page_221">221</a><br />
+Winterstein, <a href="#Page_199">199</a><br />
+Wolff, C. F., <a href="#Page_26">26</a><br />
+Wolff, G., <a href="#Page_105">105</a>, <a href="#Page_146">146</a>, <a href="#Page_255">255</a>, <a href="#Page_266">266</a>, <a href="#Page_287">287</a> f.<br />
+Wolff, J., <a href="#Page_177">177</a><br />
+<br />
+Yung, <a href="#Page_177">177</a><br />
+<br />
+Zeleny, <a href="#Page_112">112</a>, <a href="#Page_115">115</a>, <a href="#Page_212">212</a><br />
+Zur Strassen, <a href="#Page_93">93</a>
+</p>
+
+
+<p class="tac fs65"><br /><br /><br /><br />THE END<br /><br /><br /><br />
+
+<i>Printed by</i> <span class="smcap">R. &amp; R. Clark, Limited,</span> <i>Edinburgh</i>.</p>
+
+<p><span class="pagenum hide" title="330"><a name="Page_330" id="Page_330"></a></span><br /><span class="pagenum hide" title="331"><a name="Page_331" id="Page_331"></a></span></p>
+
+
+
+<hr class="chap" />
+
+<h2>HEREDITY AND SELECTION<br />
+IN SOCIOLOGY</h2>
+
+
+<p class="tac fs65 pt12b02em">BY</p>
+
+<p class="tac fs120">G. CHATTERTON HILL</p>
+
+<p class="tac">Demy 8vo, Cloth, 600 pages.</p>
+
+<p class="tac">Price <b><span class="fs120">12s. 6d.</span></b> net.</p>
+
+<p class="tac"><i>Post Free, Price</i> <b><span class="fs120">12s. 11d.</span></b></p>
+
+<p class="tac pt12b02em">SOME PRESS OPINIONS</p>
+
+<div class="fs85 mlr10em">
+<p>“A most praiseworthy and suggestive work&mdash;should certainly be
+studied by every serious thinker.”&mdash;<cite>Morning Post.</cite></p>
+
+<p>“Mr. Hill is decidedly doctrinaire, but his book is packed with
+scientific and sociological facts, and it gives the reader healthy
+intellectual exercise.”&mdash;<cite>Christian World.</cite></p>
+
+<p>“Shows wide reading, is written in a forcible and clear style, and
+contains much that is interesting, fresh, and acute.”&mdash;<cite>Aberdeen
+Free Press.</cite></p>
+
+<p>“It is a book of equal calibre with Mr. Kidd’s and goes even
+deeper than that remarkable production into the springs of life and
+conduct.”&mdash;<cite>Methodist Recorder.</cite></p>
+
+<p>“This most suggestive and valuable work, which contains abundant
+sociological data.”&mdash;<cite>Aberdeen Journal.</cite></p>
+
+<p>“Mr. George Chatterton Hill has written a volume of surpassing
+interest not alone to scientific but to theological students.”&mdash;<cite>Catholic
+Times.</cite></p>
+
+<hr />
+<p class="tac"><span class="smcap">Published by</span> A. &amp; C. BLACK, SOHO SQUARE, LONDON, W.<br /><br /><br /></p></div>
+
+<p><span class="pagenum hide" title="332"><a name="Page_332" id="Page_332"></a></span></p>
+
+
+
+<hr class="chap" />
+
+<h2>RUDOLF EUCKEN’S<br />
+PHILOSOPHY OF LIFE</h2>
+
+<p class="tac fs65 pt12b02em">BY</p>
+
+<p class="tac fs120">W. R. BOYCE GIBSON</p>
+
+<p class="tac fs65">LECTURER IN PHILOSOPHY IN THE UNIVERSITY OF LONDON</p>
+
+<p class="tac fs85 pt12b02em">SECOND EDITION</p>
+
+<p class="tac">Crown 8vo, Cloth, with Frontispiece Portrait of Rudolf Eucken.</p>
+
+<p class="tac">Price <b><span class="fs120">3s. 6d.</span></b> net.</p>
+
+<p class="tac"><i>Post Free, Price</i> <b><span class="fs120">3s. 10d.</span></b></p>
+
+<p class="tac pt12b02em">SOME PRESS OPINIONS</p>
+
+<div class="fs85 mlr10em">
+<p>“Mr. Gibson has given us in small compass a lucid exposition of the
+philosophical system of Eucken, who is Professor of Philosophy in Jena.&nbsp;.&nbsp;.&nbsp;.
+This is a most suggestive and stimulating book. In a very real
+sense it has brought philosophy down to earth and is deserving of
+serious study.”&mdash;<cite>Aberdeen Free Press.</cite></p>
+
+<p>“To it the interested reader will turn with expectation, and his
+expectation is likely to be more than realised. For Dr. Boyce Gibson
+is himself a scholar, as well as an enthusiastic lover of this great
+scholar.”&mdash;<cite>Expository Times.</cite></p>
+
+<p>“No reader should fail to find pleasure in a book so full of fresh
+and stimulating thought, expressed with great felicity of language.”&mdash;<cite>The
+Scottish Review.</cite></p>
+
+<p>“It is done with just the proper combination of sympathy and
+criticism.”&mdash;<cite>British Weekly.</cite></p>
+
+<p>“This little book on Eucken’s Philosophy is of quite exceptional
+interest and importance.”&mdash;<cite>The Inquirer.</cite></p>
+
+<p>“Professor Boyce Gibson&nbsp;.&nbsp;.&nbsp;. has performed a real service in
+promoting the acquaintance of English, and American students with a
+thinker whose distinctive views give him a special claim to their
+attention.&nbsp;.&nbsp;.&nbsp;. Professor Gibson has achieved a notable success,
+writing briefly, lucidly, and sympathetically.”&mdash;<cite>The New Age.</cite></p>
+
+<hr />
+<p class="tac"><span class="smcap">Published by</span> A. &amp; C. BLACK, SOHO SQUARE, LONDON, W.<br /><br /><br /></p></div>
+
+<hr class="chap" />
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote">
+
+<p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">1</span></a> Windelband (<cite lang="de" xml:lang="de">Geschichte und Naturwissenschaft</cite>, 3 Auflage, 1904) gives
+the name “nomothetic” to the whole of our “science” and calls the method
+of history “idiographic.” We thought it better to establish three fundamental
+types of all possible branches of knowledge.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">2</span></a> See J. Arth. Thomson, <cite>The Science of Life</cite>, London, 1899.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">3</span></a> E. B. Wilson, <cite>The Cell in Development and Inheritance</cite>, New York,
+Macmillan, 1896.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">4</span></a> <cite>Amer. Journ. Physiol.</cite> vols. iii. and iv. 1900.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">5</span></a> According to Delage (<cite>Arch. Zool. exp.</cite>, 3 sér. 10, 1902), it is indifferent
+for the realisation of artificial parthenogenesis, whether but one, or both, or
+neither of the “polar bodies” has been formed. But the egg must be in the
+first stages of maturation to the extent that the “nuclear membrane” must
+be already dissolved.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">6</span></a> The older theories, attributing to fertilisation (or to “conjugation,” <i>i.e.</i>
+its equivalent in Protozoa), some sort of “renovation” or “rejuvenescence”
+of the race, have been almost completely given up. (See Calkins, <cite lang="de" xml:lang="de">Arch. für
+Entwickelungsmechanik</cite>, xv. 1902). R. Hertwig recently has advocated the
+view, that abnormal relations between the amounts of nuclear and of protoplasmatic
+material are rectified in some way by those processes. Teleologically,
+sexual reproduction has been considered as a means of variability (Weismann),
+but also as a means of preserving the type!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">7</span></a> The phrase “<i lang="la" xml:lang="la">ceteris paribus</i>” has to be added of course, as the duration
+of each single elementary morphogenetic process is liable to vary with the
+temperature and many other conditions of the medium.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">8</span></a> We shall not avoid in these lectures the word “explain”&mdash;so much out of
+fashion nowadays. To “explain” means to subsume under known concepts,
+or rules, or laws, or principles, whether the laws or concepts themselves be
+“explained” or not. Explaining, therefore, is always relative: what is
+elemental, of course, is only to be described, or rather to be stated.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">9</span></a> <cite lang="de" xml:lang="de">Das Keimplasma</cite>, Jena, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">10</span></a> <cite lang="de" xml:lang="de">Die Bedeutung der Kernteilungsfiguren</cite>, Leipzig, 1883.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">11</span></a> <cite lang="de" xml:lang="de">Unsere Körperform</cite>, Leipzig, 1875.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">12</span></a> <cite lang="de" xml:lang="de">Die Entwickelungsgeschichte der Unke</cite>, Leipzig, 1875.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">13</span></a> <cite lang="de" xml:lang="de">Gesammelte Abhandlungen</cite>, Leipzig, 1895. Most important theoretical
+papers:&mdash;<cite lang="de" xml:lang="de">Zeitschr. Biolog.</cite> 21, 1885; <cite lang="de" xml:lang="de">Die Entwickelungsmechanik der Organismen</cite>,
+Wien, 1890; <cite lang="de" xml:lang="de">Vorträge und Aufsätze über Entwickelungsmechanik</cite>,
+Heft i., Leipzig, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">14</span></a> <i>Virchow’s Archiv.</i> 114, 1888.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">15</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 53, 1891.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">16</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 55, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">17</span></a> In the pressure experiments I had altered the relative position of the
+nuclei <i lang="la" xml:lang="la">in origine</i>. In later years I succeeded in disturbing the arrangement
+of the fully formed cells of the eight-cell stage, and in getting normal larvæ
+in spite of that in many cases. But as this series of experiments is not free
+from certain complications&mdash;which in part will be understood later on (see
+page <a href="#Page_73">73</a>)&mdash;it must suffice here to have mentioned them. (For further information
+see my paper in <cite lang="de" xml:lang="de">Archiv. f. Entwickelungsmechanik</cite>, xiv., 1902, page 500.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">18</span></a> <i>Mitteil. Neapel. 11, 1893.</i></p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">19</span></a> But the elementary magnets would have to be bilateral!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">20</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 2, 1895.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">21</span></a> <cite lang="de" xml:lang="de">Anat. Anz.</cite> 10, 1895.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">22</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 3, 1896.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">23</span></a> It deserves notice in this connection, that in some cases the protoplasm
+of parts of a germ has been found to be more regulable in the earliest stages,
+when it is very fluid, than later, when it is more stiff.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">24</span></a> Compare my <cite lang="de" xml:lang="de">Analytische Theorie der organischen Entwickelung</cite>, Leipzig,
+1894, and my reviews in <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>,
+vols. viii. xi. xiv., 1899–1905. A shorter review is given in
+<cite lang="de" xml:lang="de">Ergebnisse der Physiologie</cite>, vol. v., 1906. The full literature will be found
+in these reviews.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">25</span></a> If the plane of section passes near the equator of the germ, two whole
+larvae may be formed also, but in the majority of cases the “animal” half
+does not go beyond the blastula. The specific features of the organisation
+of the protoplasm come into account here. See also page <a href="#Page_65">65</a>, note <a href="#Footnote_17_17">17</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">26</span></a> A change of the position of the cell is of course effected by each variation
+of the direction of the cut, which is purely a matter of chance.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">27</span></a> The reader will remember (see page <a href="#Page_65">65</a>, note <a href="#Footnote_17_17">17</a>), that even the germ
+of Echinus is not quite equipotential along its main axis, but it is equipotential
+in the strictest sense around this axis. The germs of certain
+medusae seem to be equipotential in every respect, even in their cleavage
+stages.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_28_28" id="Footnote_28_28"></a><a href="#FNanchor_28_28"><span class="label">28</span></a> <cite>Journ. Exp. Zool.</cite> 1, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_29_29" id="Footnote_29_29"></a><a href="#FNanchor_29_29"><span class="label">29</span></a> Great caution must be taken in attributing any specific morphogenetic
+part to differently coloured or constructed materials, which may be observed
+in the egg-protoplasm in certain cases. They may play such a part, but in
+other cases they certainly do not (see Lyon, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 23, 1907).
+The final decision always depends on experiment.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_30_30" id="Footnote_30_30"></a><a href="#FNanchor_30_30"><span class="label">30</span></a> It seems that these physical conditions also&mdash;besides the real specifications
+in the organisation of the egg&mdash;may be different before and after
+maturation or (in other cases) fertilisation. (See Driesch, <cite lang="de" xml:lang="de">Archiv f. Entwickelungsmechanik</cite>,
+7, p. 98; and Brachet, <i lang="la" xml:lang="la">ibid.</i> 22, p. 325.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_31_31" id="Footnote_31_31"></a><a href="#FNanchor_31_31"><span class="label">31</span></a> <cite lang="de" xml:lang="de">Studien über Protoplasmamechanik</cite>, Leipzig, 1886.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_32_32" id="Footnote_32_32"></a><a href="#FNanchor_32_32"><span class="label">32</span></a> <cite lang="de" xml:lang="de">Unters. üb. mikroskopische Schäume und das Protoplasma</cite>, Leipzig, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_33_33" id="Footnote_33_33"></a><a href="#FNanchor_33_33"><span class="label">33</span></a> <cite lang="de" xml:lang="de">Jena. Zeitschr.</cite> 26, 1892.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_34_34" id="Footnote_34_34"></a><a href="#FNanchor_34_34"><span class="label">34</span></a> According to Zur Strassen’s results the early embryology of <i class="biological-name">Ascaris</i>
+proceeds almost exclusively by cellular surface-changes: the most typical
+morphogenetic processes are carried out by the aid of this “means.” As a
+whole, the embryology of <i class="biological-name">Ascaris</i> stands quite apart and presents a great
+number of unsolved problems; unfortunately, the germ of this form has not
+been accessible to experiment hitherto.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_35_35" id="Footnote_35_35"></a><a href="#FNanchor_35_35"><span class="label">35</span></a> Rhumbler has recently published a general survey of all attempts to
+“explain” life, and morphogenesis in particular, in a physico-chemical way
+(“Aus dem Lückengebiet zwischen organismischer und anorganismischer
+Natur,” <i>Ergeb. Anat. u. Entw.-gesch.</i> 15, 1906). This <em>very pessimistic</em> survey
+is the more valuable as it is written by a convinced “mechanist.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_36_36" id="Footnote_36_36"></a><a href="#FNanchor_36_36"><span class="label">36</span></a> Compare the analytical discussions of Klebs, to whom we owe a great
+series of important discoveries in the field of morphogenetic “means” in
+botany. (<cite lang="de" xml:lang="de">Willkürliche Entwickelungsänderungen bei Pflanzen</cite>, Jena, 1903;
+see also <cite lang="de" xml:lang="de">Biol. Centralblatt</cite>, vol. xxiv., 1904, and my reply to Klebs, <i lang="la" xml:lang="la">ibid.</i> 23, 1903.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_37_37" id="Footnote_37_37"></a><a href="#FNanchor_37_37"><span class="label">37</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 17, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_38_38" id="Footnote_38_38"></a><a href="#FNanchor_38_38"><span class="label">38</span></a> <cite lang="de" xml:lang="de">Zeitschr. wiss. Zool.</cite> 55, 1902; and <cite lang="de" xml:lang="de">Mitt. Neapel.</cite> 11, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_39_39" id="Footnote_39_39"></a><a href="#FNanchor_39_39"><span class="label">39</span></a> In certain cases part of the specific feature of the process in question may
+also depend on the “cause” which is localising it, <i>e.g.</i> in the galls of plants.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_40_40" id="Footnote_40_40"></a><a href="#FNanchor_40_40"><span class="label">40</span></a> Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale
+Auffassung von Vorgängen in der tierischen Ontogenese” (<cite lang="de" xml:lang="de">Biol. Centralblatt</cite>,
+vols. xiv., 1894, and xv., 1895); <cite lang="de" xml:lang="de">Formative Reize in der tierischen Ontogenese</cite>,
+Leipzig, 1901. These important papers must be studied by every one who
+wishes to become familiar with the subject. The present state of science is
+reviewed in my articles in the <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>,
+vols. xi. and xiv., 1902 and 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_41_41" id="Footnote_41_41"></a><a href="#FNanchor_41_41"><span class="label">41</span></a> Compare the important papers by J. Loeb, <cite lang="de" xml:lang="de">Untersuchungen zur
+physiologischen Morphologie der Tiere</cite>, Würzburg, 1891–2.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_42_42" id="Footnote_42_42"></a><a href="#FNanchor_42_42"><span class="label">42</span></a> I use the word “primordia” for the German “Anlage”; it is better than the
+word “rudiment,” as the latter may also serve to signify the very last stage
+of a certain formation that is disappearing (phylogenetically).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_43_43" id="Footnote_43_43"></a><a href="#FNanchor_43_43"><span class="label">43</span></a> A full analysis of the subject would not only have to deal with formative
+stimuli as inaugurating morphogenetic processes, but also with those stimuli
+which terminate or stop the single acts of morphogenesis. But little is
+actually known about this topic, and therefore the reader must refer to my
+other publications. I will only say here, that the end of each single morphogenetic
+act may either be determined at the very beginning or occur as an
+actual stopping of a process which otherwise would go on for ever and ever;
+in the first case some terminating factors are included in the very nature of
+the morphogenetic act itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_44_44" id="Footnote_44_44"></a><a href="#FNanchor_44_44"><span class="label">44</span></a> A full account of the present state of the subject will be found in
+Morgan’s <cite>Experimental Zoology</cite>, New York, 1907.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_45_45" id="Footnote_45_45"></a><a href="#FNanchor_45_45"><span class="label">45</span></a> But there certainly exist many formative relations between the real
+sexual organs and the so-called secondary sexual characters. Herbst has
+given a full analytical discussion of all that is known on this subject; but
+the facts are much more complicated than is generally supposed, and do not
+lend themselves therefore to short description. See also Foges, <i>Pflüger’s Arch.</i>
+93, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_46_46" id="Footnote_46_46"></a><a href="#FNanchor_46_46"><span class="label">46</span></a> It seems that in some cases (<i class="biological-name">Dinophilus</i>, certain Arthropods) the sexual
+products are invariably determined as “arrenogennetic” or as “thelygennetic”
+(Wilson, <cite>Journ. Exp. Zool.</cite> ii. and iii. 1905–6), whilst in others
+(Amphibia) the state of maturation or “super”-maturation determines the
+sex of the future organism (R. Hertwig, <cite lang="de" xml:lang="de">Verh. D. Zool. Ges.</cite> 1905–7).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_47_47" id="Footnote_47_47"></a><a href="#FNanchor_47_47"><span class="label">47</span></a> Driesch, <cite lang="de" xml:lang="de">Die organischen Regulationen</cite>, Leipzig, 1901; Morgan, <cite>Regeneration</cite>,
+New York, 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_48_48" id="Footnote_48_48"></a><a href="#FNanchor_48_48"><span class="label">48</span></a> But real compensatory differentiation occurs in the cases of so-called
+“hypertypy” as first discovered by Przibram and afterwards studied by
+Zeleny: here the two organs of a pair show a different degree of differentiation.
+Whenever the more specialised organ is removed the less developed
+one assumes its form. Similar cases, which might simply be called “compensatory
+heterotypy,” are known in plants, though only relating to the
+actual fate of undifferentiated “Anlagen” in these organisms. A leaf may
+be formed out of the Anlage of a scale, if all the leaves are cut off, and so on.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_49_49" id="Footnote_49_49"></a><a href="#FNanchor_49_49"><span class="label">49</span></a> For a fuller analysis compare my opening address delivered before the
+section of “Experimental Zoology” at the Seventh Zoological Congress,
+Boston, 1907: “The Stimuli of Restitutions” (see Proceedings of that
+Congress).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_50_50" id="Footnote_50_50"></a><a href="#FNanchor_50_50"><span class="label">50</span></a> The problem of the stimulus of a secondary restitution as a whole must
+not be confused with the very different question, what the single “formative
+stimuli” concerned in the performance of a certain restitutive act may be.
+With regard to restitution as a <em>whole</em> these single “formative stimuli”
+might properly be said to belong to its “internal means”&mdash;in the widest
+sense of the word.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_51_51" id="Footnote_51_51"></a><a href="#FNanchor_51_51"><span class="label">51</span></a> T. H. Morgan is very right in stating that, in regeneration, the
+“obstacle” itself is newly formed by the mere process of healing, previous
+to all restitution, and that true restitution happens all the same.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_52_52" id="Footnote_52_52"></a><a href="#FNanchor_52_52"><span class="label">52</span></a> I merely mention here the still “simpler” one&mdash;applicable of course
+to regeneration proper exclusively&mdash;that for the simple reason of being
+“wounded,” <i>i.e.</i> being a surface open to the medium, the “wound” brings
+forth all that is necessary to complete the organism.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_53_53" id="Footnote_53_53"></a><a href="#FNanchor_53_53"><span class="label">53</span></a> That compensatory hypertrophy cannot be due to “functional adaptation”&mdash;to
+be analysed later on&mdash;was proved by an experiment of Ribbert’s. Compensation may occur before the function has made its appearance, as was
+shown to be the case in the testicles and mammae of rabbits. (<cite lang="de" xml:lang="de">Arch. Entw.
+Mech.</cite> 1, 1894, p. 69.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_54_54" id="Footnote_54_54"></a><a href="#FNanchor_54_54"><span class="label">54</span></a> At any given time only the absolute size of the regenerated part is
+greater in animals which are well fed; the degree of differentiation is the
+same in all. Zeleny has found that, if all five arms of a starfish are removed,
+each one of them will regenerate more material in a given time than it
+would have done if it alone had been removed. But these differences also
+only relate to absolute size and not to the degree of differentiation. They
+possibly may be due in fact to conditions of nourishment, but even here
+other explanations seems possible (Zeleny, <cite>Journ. exp. Zool.</cite> 2, 1905).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_55_55" id="Footnote_55_55"></a><a href="#FNanchor_55_55"><span class="label">55</span></a> For a good discussion of “super-regeneration” in the roots of plants see
+Němec, <cite lang="de" xml:lang="de">Studien über die Regeneration</cite>, Berlin, 1905. Goebel and Winkler
+have succeeded in provoking the “restitution” of parts which were not
+removed at all by simply stopping their functions (leaves of certain plants
+were covered with plaster, etc.). (<cite lang="de" xml:lang="de">Biol. Centralbl.</cite> 22, 1902, p. 385; <cite lang="de" xml:lang="de">Ber.
+Bot. Ges.</cite> 20, 1902, p. 81.) A fine experiment is due to Miehe. The alga
+<i class="biological-name">Cladophora</i> was subjected to “plasmolysis,” each cell then formed a new
+membrane of its own around the smaller volume of its protoplasm; after
+that the plants were brought back to a medium of normal osmotic pressure,
+and then each single cell grew up into a little plant (all of them being of
+the same polarity!). Two questions seem to be answered by this fact:
+loss of communication is of fundamental importance to restitution, and the
+removal of mechanical obstacles plays no part in it, for the mechanical
+resistances were the same at the end of the experiment as they had been at
+the beginning. (<cite lang="de" xml:lang="de">Ber. Bot. Ges.</cite> 23, 1905, p. 257.) For fuller analysis of all
+the problems of this chapter see my Organische Regulationen, my reviews
+in the <cite lang="de" xml:lang="de">Ergebnisse der Anatomie und Entwickelungsgeschichte</cite>, vols. viii. xi.
+xiv., and my Boston address mentioned above. Compare also Fitting,
+<cite lang="de" xml:lang="de">Ergebn. d. Physiol.</cite> vols. iv. and v.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_56_56" id="Footnote_56_56"></a><a href="#FNanchor_56_56"><span class="label">56</span></a> The so-called “inner secretion” in physiology proper would offer a
+certain analogy to the facts assumed by such an hypothesis. Compare the
+excellent summary given by E. Starling at the seventy-eighth meeting of the
+German “Naturforscherversammlung,” Stuttgart, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_57_57" id="Footnote_57_57"></a><a href="#FNanchor_57_57"><span class="label">57</span></a> The name of singular-equipotential systems might also be applied to
+elementary organs, the single potencies of which are awaked to organogenesis
+by specific formative stimuli from without; but that is not the case in the
+systems studied in this chapter.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_58_58" id="Footnote_58_58"></a><a href="#FNanchor_58_58"><span class="label">58</span></a> The distance of the other boundary line from <i>a</i> or <i>b</i> would be given by
+the value of <i>s</i>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_59_59" id="Footnote_59_59"></a><a href="#FNanchor_59_59"><span class="label">59</span></a> A far more thorough analysis of this differentiation has been attempted
+in my paper, “Die Localisation morphogenetischer Vorgänge. Ein Beweis
+vitalistischen Geschehens,” Leipzig, 1899.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_60_60" id="Footnote_60_60"></a><a href="#FNanchor_60_60"><span class="label">60</span></a> This statement is <em>not strictly</em> correct for <i class="biological-name">Tubularia</i>. I found (<cite lang="de" xml:lang="de">Archiv f.
+Entwickelungsmechanik</cite>, ix. 1899), that a reduction of the length of the
+stem is always followed by a reduction of the size of the hydranth-primordium,
+but there is no real proportionality between them. It is only for
+theoretical simplification that a strict proportionality is assumed here, both
+in the text and the diagram. But there is an almost strict proportionality
+in all cases of “closed forms.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_61_61" id="Footnote_61_61"></a><a href="#FNanchor_61_61"><span class="label">61</span></a> One might object here that in a piece of a <i class="biological-name">Tubularia</i> stem, for instance,
+the tissues are in direct contact with the sea-water at the two points of the
+wounds only, and that at these very points a stimulus might be set up&mdash;say
+by a process of diffusion&mdash;which gradually decreases in intensity on its way
+inward. And a similar argument might apply to the small but whole
+blastula of Echinus, and to all other cases. But, in the first place, stimuli
+which only differ in intensity could hardly call forth the typical and typically
+localised single features realised in differentiation. On the other hand&mdash;and
+this will overthrow such an hypothesis completely&mdash;the dependence of
+the single localised effects in every case on the <em>absolute size</em> of the fragment
+or piece chosen for restoration renders quite impossible the assumption
+that all the singularities in the differentiation of the harmonious systems
+might be called forth by single stimuli originating in two fixed places in an
+<em>independent</em> way. These would never result in any “harmonious,” any
+proportionate structure, but a structure of the “normal” proportionality
+<em>and size</em> at its two ends and non-existent in the middle!</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_62_62" id="Footnote_62_62"></a><a href="#FNanchor_62_62"><span class="label">62</span></a> See my article in <cite lang="de" xml:lang="de">Biolog. Centralblatt</cite>, 27, 1907, p. 69. The question is
+rendered still more complicated by the fact that in the case of the regeneration,
+say, of a leg it is not the original “morphogenetic compound” which
+is again required for disintegration, after it has become disintegrated once
+already, but only a specific part of it: just that part of it which is necessary
+for producing the leg! On the other hand, it would be impossible to understand,
+on the basis of physical chemistry, how the isolated branchial apparatus
+of <i class="biological-name">Clavellina</i> could be transformed, by chemical processes exclusively, into
+a system of which only a certain <em>part</em> consists of that substance of which
+the starting-point had been composed in its <em>completeness</em>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_63_63" id="Footnote_63_63"></a><a href="#FNanchor_63_63"><span class="label">63</span></a> Besides the specified poles determined by the polar-bilateral structure
+of the protoplasm.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_64_64" id="Footnote_64_64"></a><a href="#FNanchor_64_64"><span class="label">64</span></a> The pressure experiments and the dislocation experiments come into
+account here; for the sake of simplicity they have not been alluded to in the
+main line of our argument.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_65_65" id="Footnote_65_65"></a><a href="#FNanchor_65_65"><span class="label">65</span></a> My “first proof of vitalism” was first developed in the paper, “Die
+Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional
+remarks in <cite lang="de" xml:lang="de">Organische Regulationem</cite>, Leipzig, 1901, and in <cite lang="de" xml:lang="de">Archiv für
+Entwickelungsmechanik</cite>, 14, 1902.) I cannot admit that any really serious
+objection has been brought forward against it. (See my articles in <cite lang="de" xml:lang="de">Biologisches
+Centralblatt</cite>, 22, 23, 27, and in <cite lang="de" xml:lang="de">Ergebnisse d. Anat. u. Entwickelungsgesch</cite>.
+11, 14.) An historical sketch of vitalism will be found in my book, <cite lang="de" xml:lang="de">Der
+Vitalismus als Geschichte und als Lehre</cite>, Leipzig, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_66_66" id="Footnote_66_66"></a><a href="#FNanchor_66_66"><span class="label">66</span></a> We are dealing here with morphogenesis and so-called vegetative
+physiology only; to certain psychologists, who have refuted the theory of
+psycho-physical parallelism, I must grant that they also have proved
+vitalism. (See Volume II.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_67_67" id="Footnote_67_67"></a><a href="#FNanchor_67_67"><span class="label">67</span></a> The eight larvae would be incomplete in some respect, but not with
+regard to symmetry. They would be “whole” ones, only showing certain
+defects in their organisation. See page <a href="#Page_65">65</a> note <a href="#Footnote_17_17">17</a>, and page <a href="#Page_73">73</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_68_68" id="Footnote_68_68"></a><a href="#FNanchor_68_68"><span class="label">68</span></a> Reciprocal harmony may be reduced in some cases to the given proportions
+of one original harmonious system, from which the single constituents
+of the complicated system, showing reciprocal harmony, are derived. Then
+we have only an instance of “harmony of constellation” (see p. <a href="#Page_109">109</a>). But
+reciprocal harmony seems to become a problem itself, if it occurs in
+restitutions starting from quite a typical point, selected by the experimenter.
+It will be a problem of future research to give an exact formula of what
+happens here. Reciprocal harmony also occurs in regeneration proper. It is
+known that the formation of the regenerative bud and the differentiation
+of this bud follow each other. As the bud is composed of different elementary
+systems, it follows that these different systems, of which every single one is
+harmonious, also have to work in reciprocity to each other, in order that
+one whole proportionate formation may result.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_69_69" id="Footnote_69_69"></a><a href="#FNanchor_69_69"><span class="label">69</span></a> <cite lang="de" xml:lang="de">Biol. Centralblatt.</cite> 23, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_70_70" id="Footnote_70_70"></a><a href="#FNanchor_70_70"><span class="label">70</span></a> Certain phenomena of the physiology of growth of <i class="biological-name">Geranium Robertianum</i>,
+recently discussed by Francé from a vitalistic point of view (<cite lang="de" xml:lang="de">Zeitschr. Entw.
+lehre</cite>. 1, 1907, Heft iv.), might also belong here. I cannot see an independent
+proof of vitalism in these facts if taken by themselves; a pre-existing
+“machine” cannot be absolutely excluded here.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_71_71" id="Footnote_71_71"></a><a href="#FNanchor_71_71"><span class="label">71</span></a> Driesch, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 5, 1897.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_72_72" id="Footnote_72_72"></a><a href="#FNanchor_72_72"><span class="label">72</span></a> Driesch, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 14, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_73_73" id="Footnote_73_73"></a><a href="#FNanchor_73_73"><span class="label">73</span></a> The root may be restored by regeneration proper, or by the production
+of adventitious roots, or by one of the side-roots changing its geotropism from
+horizontal to positive, according to the smaller or greater distance of the
+wound from the tip.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_74_74" id="Footnote_74_74"></a><a href="#FNanchor_74_74"><span class="label">74</span></a> “Retro”-differentiation, of course, is not “Re”-differentiation (“Umdifferenzierung,”
+see p. <a href="#Page_111">111</a>), though it may help it to occur.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_75_75" id="Footnote_75_75"></a><a href="#FNanchor_75_75"><span class="label">75</span></a> Of course such a real decay of parts may happen in other cases.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_76_76" id="Footnote_76_76"></a><a href="#FNanchor_76_76"><span class="label">76</span></a> Certain cases of retro-differentiation occurring under conditions of strict
+fasting will be described in a later chapter.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_77_77" id="Footnote_77_77"></a><a href="#FNanchor_77_77"><span class="label">77</span></a> Klebs has suppressed the reproductive phase of organisation altogether,
+in fungi as well as in flowering plants, or has made it occur abnormally early,
+merely by changing the “external conditions” and by altering the “internal”
+ones correspondingly. There is hardly anything like an adaptation in these
+cases, which, by the way, offer certain difficulties to analysis, as the boundaries
+between “cause” and “means” are not very sharp here.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_78_78" id="Footnote_78_78"></a><a href="#FNanchor_78_78"><span class="label">78</span></a> Compare Herbst, <cite lang="de" xml:lang="de">Biol. Centralbl.</cite> 15, 1895; and Detto, <cite lang="de" xml:lang="de">Die Theorie der
+direkten Anpassung</cite>, Jena, 1904. A full account of the literature will be
+found in these papers.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_79_79" id="Footnote_79_79"></a><a href="#FNanchor_79_79"><span class="label">79</span></a> Vöchting (<cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 34, 1899) forced the bulbs of plants to
+become parts of the stem, and parts of the stem to form bulbs; in both cases
+the most characteristic changes in histology could be observed, being in part
+adaptations, but in part restitutions of the proper type. (See also my
+<cite lang="de" xml:lang="de">Organische Regulationen</cite>, 1901, p. 84.) A true and simple instance of a
+“secondary adaptation” seems to be furnished in a case described by
+Boirivant. In <i class="biological-name">Robinia</i> all the leaflets of a leaf-stalk were cut off: the leaf-stalk
+itself then changed its structure in order to assist assimilation, and also
+formed real stomata.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_80_80" id="Footnote_80_80"></a><a href="#FNanchor_80_80"><span class="label">80</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 17, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_81_81" id="Footnote_81_81"></a><a href="#FNanchor_81_81"><span class="label">81</span></a> Roux, <cite lang="de" xml:lang="de">Gesammelte Abhandlungen</cite>, vol. i. 1895; in particular, <cite lang="de" xml:lang="de">Der Kampf
+der Teile im Organismus</cite>, Leipzig, 1881.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_82_82" id="Footnote_82_82"></a><a href="#FNanchor_82_82"><span class="label">82</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 21, 1906. By a very detailed comparative study
+Babák was able to prove that it is the plant proteids to which the effect of
+vegetable food is chiefly due; thus we have an adaptation to digestibility.
+Mechanical circumstances are only of secondary importance. (See also Yung.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_83_83" id="Footnote_83_83"></a><a href="#FNanchor_83_83"><span class="label">83</span></a> Atrophy of muscles by inactivity is not to be confused with atrophy by
+cutting the motor nerve; the latter is very much more complete.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_84_84" id="Footnote_84_84"></a><a href="#FNanchor_84_84"><span class="label">84</span></a> Loeb has advocated the view that the “adaptive” growth of working
+muscles is simply due to the presence of a greater number of molecules in
+their protoplasm, muscular activity being generated by a process of chemical
+decomposition.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_85_85" id="Footnote_85_85"></a><a href="#FNanchor_85_85"><span class="label">85</span></a> What has been really <em>proved</em> to exist by the very careful studies carried
+out by Child, is only certain cases of functional adaptation to mechanical
+conditions of the strictest kind, and relating to the general mobility only, but
+nothing more; such adaptations can be said to accompany restitution. See,
+for instance, <cite>Journ. exp. Zool.</cite> 3, 1906, where Child has given a summary of
+his theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_86_86" id="Footnote_86_86"></a><a href="#FNanchor_86_86"><span class="label">86</span></a> Even in Vöchting’s experiments (see page <a href="#Page_174">174</a>, note <a href="#Footnote_79_79">79</a>), in which adaptations
+are mixed with true restitutions in the closest possible manner, a few
+phenomena of the latter type could most clearly be separated. The stimulus
+which called them forth must have been one of the hypothetic sort alluded
+to in a former chapter (see page <a href="#Page_113">113</a>). The best instances of true restitutions
+were offered in those cases, where, after the removal of all the bulbs, typical
+starch-storing cells were formed without the presence of any starch.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_87_87" id="Footnote_87_87"></a><a href="#FNanchor_87_87"><span class="label">87</span></a> <cite lang="de" xml:lang="de">Beiträge zur Lehre von den Functionen der Nervencentren des Frosches</cite>,
+Berlin, 1869.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_88_88" id="Footnote_88_88"></a><a href="#FNanchor_88_88"><span class="label">88</span></a> The “secondary adaptations” observed by Vöchting are too complicated
+and too much mingled with restitutions to allow any definite analysis of the
+fact of the “secondary adaptation” as such.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_89_89" id="Footnote_89_89"></a><a href="#FNanchor_89_89"><span class="label">89</span></a> General literature: Fröhlich, <cite lang="de" xml:lang="de">Das natürliche Zweckmüssigkeitsprincip
+in seiner Bedeutung für Krankheit und Heilung</cite>, 1894. Driesch, <cite lang="de" xml:lang="de">Die
+organischen Regulationen</cite>, 1901. A. Tschermak, “Das Anpassungsproblem in
+der Physiologie der Gegenwart,” in a collection of papers in honour of J. P.
+Pawlow, St. Petersburg, 1904. Bieganski, “Ueber die Zweckmässigkeit in den
+pathologischen Erscheinungen,” <cite lang="de" xml:lang="de">Annal. d. Naturphil.</cite> 5, 1906. Among the
+general text-books of physiology those by Pfeffer (<cite lang="de" xml:lang="de">Pflanzenphysiologie</cite>, 1897–1904)
+and von Bunge (<cite lang="de" xml:lang="de">Lehrbuch d. Phys. d. Menschen</cite>, 1901) are the fullest on
+the subject of “regulations.” See also different papers on general pathology
+by Ribbert.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_90_90" id="Footnote_90_90"></a><a href="#FNanchor_90_90"><span class="label">90</span></a> According to investigations of the last two years, the physics of colloids
+seems to play as important a part in physiology as osmosis does; we here
+meet “means” of functioning just as we have already had “means” of
+organogenesis.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_91_91" id="Footnote_91_91"></a><a href="#FNanchor_91_91"><span class="label">91</span></a> I only mention here that certain modern psychologists have assigned
+the true law of Weber to the sphere of judgment and not of sensation. If
+applied to objective reactions only, in their dependence on objective stimuli,
+it, of course, becomes less ambiguous, and may, in a certain sense, be said to
+measure “acclimatisation” with regard to the stimulus in question. The
+mathematical analogy of the law of Weber to the most fundamental law of
+chemical dynamics seems very important.
+</p>
+<p>
+As to “acclimatisation” in the more usual meaning of the word, with
+regard to a change of the general faculty of resisting certain agents of the
+medium, “immunity” proper is to form a special paragraph of what follows,
+and to “acclimatisation” towards different degrees of salinity (in algae or
+fishes) some special remarks will also be devoted on a proper occasion.
+There remains only “acclimatisation” to different temperatures; but on this
+topic not much more than the fact is known (see Davenport, <cite lang="de" xml:lang="de">Arch. f. Entw.
+Mech.</cite> 2, p. 227). “Acclimatisation” does not allow of a sharp general definition;
+it may be the result of very <em>different</em> kinds of adaptations in our sense
+of the word.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_92_92" id="Footnote_92_92"></a><a href="#FNanchor_92_92"><span class="label">92</span></a> I should think that the problem of the re-establishment of irritability,
+in principle at least, arises even when there is not a trace of so-called
+“fatigue” or of a “refractory period.” The process of restoring may be so
+rapid as not to be noticeable, nevertheless some sort of restoring is to be
+postulated. We may say the “irritability” of an elastic ball is re-established
+by its elasticity. A certain analogy to this case may perhaps be found in the
+muscle. But the irritability of nerves with respect to nervous conduction,
+and of glands with respect to secretion, or of the articulations of <i class="biological-name">Mimosa</i>
+may be well understood, hypothetically at least, if we assume that the
+ordinary course of metabolic events is apt in itself to lead to a certain state
+or condition of the organs in question upon which their irritability is based.
+Certain general conditions of functioning, as for instance the presence of
+oxygen for the contraction of the muscle, would better be looked upon as
+necessary “means” of functioning than as being part of irritability as such.
+“Fatigue,” of course, may also be due to the absence of such “means” or to
+abnormal conditions originated by functioning itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_93_93" id="Footnote_93_93"></a><a href="#FNanchor_93_93"><span class="label">93</span></a> Rubner, <cite lang="de" xml:lang="de">Die Gesetze des Energieverbrauches bei der Ernährung</cite>, Leipzig
+u. Wein, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_94_94" id="Footnote_94_94"></a><a href="#FNanchor_94_94"><span class="label">94</span></a> The phenomenon of fever we leave out of account here; it is regarded by
+some as regulation, by others as a disturbance of heat regulation. Of course,
+if the first view should ever prove to be the right one, fever might be classified
+among the real regulations of the secondary type.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_95_95" id="Footnote_95_95"></a><a href="#FNanchor_95_95"><span class="label">95</span></a> <cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 36, 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_96_96" id="Footnote_96_96"></a><a href="#FNanchor_96_96"><span class="label">96</span></a> Carbohydrates cannot be ionised, and therefore there is no doubt that in
+von Mayenburg’s experiments the organism itself is actively at work. As to
+compounds liable to ionisation, it has been noticed by Maillard that a certain
+regulatory character is contained simply in the physical fact that the degree
+of ionisation changes with concentration: decrease of concentration for instance
+would be followed by an increase of ionisation, and so the osmotic pressure
+may be preserved (<cite lang="fr" xml:lang="fr">C. rend. Soc. Biol.</cite> 53, 1901, p. 880).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_97_97" id="Footnote_97_97"></a><a href="#FNanchor_97_97"><span class="label">97</span></a> In the different experiments of Nathansohn (<cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite> 38, 1902,
+and 39, 1903) the salinity of the medium was changed in such a way that
+there was in each case either an abnormal increase or an abnormal decrease in
+the concentration of one single ion necessary for metabolism. The cell was
+found to stand these abnormal changes in such a way that in the case of the
+increase of the concentration of the medium it did not allow more than
+a certain amount of the ion in question to come in, and that in the case of
+the decrease it did not allow more than a certain quantity of the ion to go
+out. It thus seems as if the permeability of the surface were adjusted
+to a certain minimum and to a certain maximum of every single ion or
+salt, the permeability being stopped from within to without, whenever the
+minimum, and from without to within, whenever the maximum is reached
+in the cell sap; both irrespective of proper physical osmotic equilibrium
+(“Physiologisches Gleichgewicht”). Thus, in fact, there only would be a
+case of primary regulation, nothing more. It would all appear rather similar
+to what occurs in the kidney. Of course we do not assert that our explanation
+is right, but it is possible and is at the same time the most simple, and
+it is our general practice always to prefer the most simple hypotheses.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_98_98" id="Footnote_98_98"></a><a href="#FNanchor_98_98"><span class="label">98</span></a> Many fishes are able to withstand great changes in the osmotic pressure
+of sea-water; the osmotic pressure of their body fluids, though never in a
+real physical equilibrium with the pressure of the medium, nevertheless may
+vary whenever the abnormal conditions of the latter exceed certain limits.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_99_99" id="Footnote_99_99"></a><a href="#FNanchor_99_99"><span class="label">99</span></a> See Stahl, <cite lang="de" xml:lang="de">Naturw. Wochenschrift</cite>, N. F. 5, 1906, No. 19.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_100_100" id="Footnote_100_100"></a><a href="#FNanchor_100_100"><span class="label">100</span></a> <cite>Arch. Anat. Phys.</cite>, Phys. Abt. Suppl., 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_101_101" id="Footnote_101_101"></a><a href="#FNanchor_101_101"><span class="label">101</span></a> The adaptive phenomena discovered by Gaidukow depend upon a real
+alteration in the formation of pigments. In the (primary) chromatic adaptation
+of pupae of Lepidoptera with respect to the colour of the ground they
+live upon, we only have the variable effects of pre-established chromatophores
+(Poulton, <cite>Phil. Trans. London</cite>, 178 B, 1888; Merrifield, <cite>Trans. Ent. Soc.
+London</cite>, 1898). The same holds for chromatic adaptations in crabs (Gamble
+and Keeble, <cite>Quart. Journ. Micr. Sci.</cite> 43, 1900; Minkiewicz, <cite>Arch. Zool. exp.
+et gén.</cite> sér. 4, 7, notes, 1907).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_102_102" id="Footnote_102_102"></a><a href="#FNanchor_102_102"><span class="label">102</span></a> The theory of oxidation we have shortly sketched here was developed
+in chapter B. 5, of my <cite lang="de" xml:lang="de">Organische Regulationen</cite>. Recent discoveries of
+Winterstein’s (<cite lang="de" xml:lang="de">Zeitschr. allg. Physiol.</cite> 6, 1907) have given the strongest
+support to my hypothetic statements, and, in fact, can be said to have
+brought the doctrine of organic oxidation to a critical point. There can be
+no doubt that oxygen not only plays the “antipoisonous” rôle I had
+assigned to it, but that it is not even of such great importance for the supply
+of functional energy as former times had assumed. No doubt it serves to
+drive the functional machine, but decomposition of certain chemical constituents
+of the organism serves this purpose even more. The latter does so
+in the most fundamental and original manner, so to speak, whilst oxidation
+only burns up its products. Almost all elemental functions, in nerve-tissue
+at least, go on very well in the absence of oxygen, provided that certain
+“poisonous” substances, resulting from this anaërobic metabolism, are
+constantly removed. In normal conditions that is done by oxygen, and in
+doing so oxygen certainly assists the supply of energy, but it does not furnish
+the whole of it. The difference between so-called “aërobic” and “anaërobic”
+life almost completely disappears under such a view, and many so-called
+“regulations,” of course, disappear at the same time; there is no more
+“intramolecular respiration.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_103_103" id="Footnote_103_103"></a><a href="#FNanchor_103_103"><span class="label">103</span></a> But nevertheless albumen is not to be replaced altogether in vertebrates
+by fat or carbohydrate; it probably serves some special function besides
+combustion, even in the adult.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_104_104" id="Footnote_104_104"></a><a href="#FNanchor_104_104"><span class="label">104</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 18, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_105_105" id="Footnote_105_105"></a><a href="#FNanchor_105_105"><span class="label">105</span></a> To a physiological friend of mine I owe the suggestion that it is the
+permanently functioning tissues which stand hunger better than the others,
+at least if the sexual cells might be regarded as capable of a <i lang="fr" xml:lang="fr">sécrétion interne</i>
+in all cases. Then the adaptations in the state of hunger might be said to be
+reduced in some degree to “functional adaptation.” But it must remain an
+open question, it seems to me, whether such a view may indeed hold in the
+face of the facts observed in <i class="biological-name">Planaria</i> and infusorians.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_106_106" id="Footnote_106_106"></a><a href="#FNanchor_106_106"><span class="label">106</span></a> In all cases where fungi of the same species are able to live on different
+hosts, that is, to penetrate membranes of a different chemical character, a
+similar objection as to the “secondary” type of such a regulation may be
+made.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_107_107" id="Footnote_107_107"></a><a href="#FNanchor_107_107"><span class="label">107</span></a> The discovery of Weinland that adult dogs are able to produce “lactase”
+in their pancreas, whenever they are fed, quite abnormally, with milk-sugar,
+has recently been said to be vitiated by an analytical mistake.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_108_108" id="Footnote_108_108"></a><a href="#FNanchor_108_108"><span class="label">108</span></a> Compare the excellent review of the subject by Bayliss and Starling in
+the <cite lang="de" xml:lang="de">Ergebnisse der Physiologie</cite>, 5, 1906, p. 664. The reader who misses here
+an analysis of the brilliant discoveries of Pawlow and his followers, relating
+to so-called “psychical and associative secretion,” will find these facts dealt
+with in another section of the book. These facts, indeed, would prove
+vitalism, it seems to me.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_109_109" id="Footnote_109_109"></a><a href="#FNanchor_109_109"><span class="label">109</span></a> It would be a true secondary metabolic regulation, if after the extirpation
+of one gland another different one were to assume its function. Nothing is
+known in this respect except a few rather doubtful observations about the
+interchange of functions between thymus and thyroid, except also the fact
+that the so-called lymph-glands increase in size after the extirpation of the
+spleen. Even here, of course, a sort of “restitution” would be included in
+adaptation proper.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_110_110" id="Footnote_110_110"></a><a href="#FNanchor_110_110"><span class="label">110</span></a> A good review is given by E. Fromm, <cite lang="de" xml:lang="de">Die chemischen Schutzmittel des
+Tierkörpers bei Vergiftungen</cite>, Strassburg, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_111_111" id="Footnote_111_111"></a><a href="#FNanchor_111_111"><span class="label">111</span></a> Davenport, <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 2, 1895–1896, and Hausmann, <i>Pflüger’s
+Arch.</i> 113, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_112_112" id="Footnote_112_112"></a><a href="#FNanchor_112_112"><span class="label">112</span></a> <i>Leçons sur la pathologie comparée de l’inflammation</i>, Paris, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_113_113" id="Footnote_113_113"></a><a href="#FNanchor_113_113"><span class="label">113</span></a> The other steps or phases in the process of inflammation have also been
+regarded as adaptive: the increased quantity of body fluid for instance is
+said to serve to dilute poisonous substances.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_114_114" id="Footnote_114_114"></a><a href="#FNanchor_114_114"><span class="label">114</span></a> See Jacoby, <cite lang="de" xml:lang="de">Immunität und Disposition</cite>, Wiesbaden, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_115_115" id="Footnote_115_115"></a><a href="#FNanchor_115_115"><span class="label">115</span></a> <cite>Collected Studies on Immunity by Ehrlich and his Collaborators</cite>, translated
+by Ch. Bolduan, New York and London, 1906.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_116_116" id="Footnote_116_116"></a><a href="#FNanchor_116_116"><span class="label">116</span></a> So-called genuine or innate immunity, in contrast to the immunity
+which is acquired, is of course a case of adaptedness only and not of adaptation.
+There also exists a high degree of specific adaptedness in some animals
+with regard to their faculty of coagulating blood. (See Leo Loeb, <cite>Biol. Bull.</cite>
+9, 1905.)</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_117_117" id="Footnote_117_117"></a><a href="#FNanchor_117_117"><span class="label">117</span></a> We cannot do more than barely mention here the problem of the localisation
+of anti-body production. In general it seems to be true that anti-bodies
+are produced by those cells which require to be protected against
+toxins; that would agree with the general rule, that all compensation of the
+change of any functional state proceeds from the part changed in its function.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_118_118" id="Footnote_118_118"></a><a href="#FNanchor_118_118"><span class="label">118</span></a> Here again I should like to except from this statement the discoveries
+of Pawlow. See page <a href="#Page_204">204</a>, note <a href="#Footnote_108_108">108</a>.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_119_119" id="Footnote_119_119"></a><a href="#FNanchor_119_119"><span class="label">119</span></a> The few cases of an “improvement” of morphogenetic acts in hydroids
+described by myself are too isolated at present to be more than mere
+problems (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 5, 1897). The same is true, it seems to me,
+with regard to certain recent discoveries made by R. Pearl on <i class="biological-name">Ceratophyllum</i>
+(<cite>Carnegie Inst. Wash. Publ.</cite> No. 58, 1907); and by Zeleny on a medusa
+(<cite>Journ. exp. Zool.</cite> 5, 1907). Pawlow’s discovery, that the enzymotic composition
+of the pancreatic fluid in dogs becomes more and more adapted to
+a specific composition of the food (either meat or bread and milk) the longer
+such a specific composition is offered to the individual animal, may probably
+be understood as a case of mere functional adaptation of the cells of the
+digestive glands, if it stands criticism at all (see Bayliss and Starling, <cite lang="de" xml:lang="de">Ergeb.
+Physiol.</cite> 5, 1906, p. 682).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_120_120" id="Footnote_120_120"></a><a href="#FNanchor_120_120"><span class="label">120</span></a> Experiments carried out in the “Biologische Versuchsanstalt” at Vienna
+indeed have shown that many animal types are capable of at least a certain
+degree of restitution, although they had previously been denied this faculty
+by zoologists.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_121_121" id="Footnote_121_121"></a><a href="#FNanchor_121_121"><span class="label">121</span></a> <cite lang="de" xml:lang="de">Ueber das Gedächtnis als eine allgemeine Function der organischen
+Materie</cite>, Wien, 1870. New edition in <cite lang="de" xml:lang="de">Klassiker d. exakt. Wiss.</cite>, Leipzig,
+Engelmann.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_122_122" id="Footnote_122_122"></a><a href="#FNanchor_122_122"><span class="label">122</span></a> <cite lang="de" xml:lang="de">Die Mneme</cite>, Leipzig, 1904.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_123_123" id="Footnote_123_123"></a><a href="#FNanchor_123_123"><span class="label">123</span></a> Driesch, <cite lang="de" xml:lang="de">Organ. Regul.</cite> 1901.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_124_124" id="Footnote_124_124"></a><a href="#FNanchor_124_124"><span class="label">124</span></a> The “ideal whole” is also proved to exist, if any <em>given</em> “Anlage,” say
+of a branch, is forced to give origin to a root, as has really been observed in
+certain plants. This case, like many other less extreme cases of what might
+be called “compensatory heterotypy,” are best to be understood by the aid
+of the concept of “prospective potency.” It is very misleading to speak of
+a metamorphosis here. I fully agree with Krašan about this question. See
+also page <a href="#Page_112">112</a>, note <a href="#Footnote_48_48">48</a>, and my <cite lang="de" xml:lang="de">Organ. Regul.</cite> pp. 77, 78.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_125_125" id="Footnote_125_125"></a><a href="#FNanchor_125_125"><span class="label">125</span></a> Winkler has discovered the important fact, that the adventitious buds
+formed upon leaves may originate either from one single cell of the epidermis
+or from several cells together; a result that is very important with respect
+to the problem of the distribution of “potencies.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_126_126" id="Footnote_126_126"></a><a href="#FNanchor_126_126"><span class="label">126</span></a> The “regeneration” of the brain of annelids for instance is far better
+regarded as an adventitious formation than as regeneration proper: nothing
+indeed goes on here at the locality of the wound; a new brain is formed out
+of the ectoderm at a certain distance from it.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_127_127" id="Footnote_127_127"></a><a href="#FNanchor_127_127"><span class="label">127</span></a> A full “analytical theory of regeneration” has been developed elsewhere
+(<cite lang="de" xml:lang="de">Organ. Regul.</cite> p. 44, etc.). I can only mention here that many different
+problems have to be studied by such a theory. The formation of the
+“Anlage” out of the body and the differentiation of it into the completely
+formed results of regeneration are two of them. The former embraces the
+question about the potencies not only of the regenerating body but of the
+elements of the Anlage also; the latter has to deal with the specific order
+of the single acts of regenerative processes.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_128_128" id="Footnote_128_128"></a><a href="#FNanchor_128_128"><span class="label">128</span></a> And, of course, at the root of every new starting of certain parts of
+morphogenesis also, as in regeneration and in adventitious budding; these
+processes, as we know, being also founded upon “complex-equipotential
+systems,” which have had their “genesis.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_129_129" id="Footnote_129_129"></a><a href="#FNanchor_129_129"><span class="label">129</span></a> New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann;
+see also Bateson, <i>Mendel’s Principles of Heredity</i>, Cambridge, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_130_130" id="Footnote_130_130"></a><a href="#FNanchor_130_130"><span class="label">130</span></a> For the sake of simplicity I shall not deal here with those cases of
+hybridisation in which one quality is “recessive,” the other “dominant,”
+but only allude to the cases, less numerous though they be, where a real
+mixture of maternal and paternal qualities occurs.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_131_131" id="Footnote_131_131"></a><a href="#FNanchor_131_131"><span class="label">131</span></a> This hypothesis was first suggested by Sutton and is at present held by
+orthodox Mendelians; but probably things are a little more complicated in
+reality, as seems to be shown by some facts in the behaviour of so-called
+“extracted recessives.” In Morgan’s <cite>Experimental Zoology</cite>, New York, 1907,
+a full account of the whole matter is given.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_132_132" id="Footnote_132_132"></a><a href="#FNanchor_132_132"><span class="label">132</span></a> <cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 21, 22, and 24, 1906–7; see also Doncaster, <cite>Phil. Trans.
+Royal Soc.</cite> London, B. 196, 1903. The influence of different temperature
+upon the organisation of the hybrids is not always quite pure, inasmuch as
+the paternal and the maternal forms may themselves be changed by this agent.
+In spite of that there exists an influence of the temperature upon the hybrid
+<em>as such</em>, at least with regard to certain features of its organisation.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_133_133" id="Footnote_133_133"></a><a href="#FNanchor_133_133"><span class="label">133</span></a> Only the nucleus of the egg had entered its first stages of activity.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_134_134" id="Footnote_134_134"></a><a href="#FNanchor_134_134"><span class="label">134</span></a> The first proof of vitalism, indeed, rests upon the analysis of the
+differentiation of an harmonious-equipotential system as a <em>whole</em>: this <em>whole</em>
+cannot be a machine that would relate to differentiation as a <em>whole</em>; the
+question whether there might be any machines distributed <em>in</em> the whole, in
+the form of the nuclei is of no importance at all in this argument. Moreover
+the pressure experiments (see page <a href="#Page_63">63</a>) prove the unimportance of such
+“machines” for the specificity of differentiation, and the second proof of
+vitalism shows that the nuclei cannot be regarded as machines accounting for
+differentiation in <em>any</em> way.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_135_135" id="Footnote_135_135"></a><a href="#FNanchor_135_135"><span class="label">135</span></a> Boveri tried to fertilise enucleated fragments of the egg of <i class="biological-name">Sphaerechinus</i>
+with the sperm of <i class="biological-name">Echinus</i>. He failed to get any results in isolated experiments,
+but found a few small larvae of the pure <i class="biological-name">Echinus</i> type in large
+cultures consisting of shaken eggs. But later experiments on hybridisation
+in sea-urchins have shown that a full hybrid of <i class="biological-name">Echinus</i> and <i class="biological-name">Sphaerechinus</i>
+may be purely paternal also.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_136_136" id="Footnote_136_136"></a><a href="#FNanchor_136_136"><span class="label">136</span></a> Surely the new results of Herbst, mentioned above, are another indication
+of the importance of something in the nucleus. The first stage in parthenogenesis,
+which he used in his experiments, is a nuclear phenomenon.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_137_137" id="Footnote_137_137"></a><a href="#FNanchor_137_137"><span class="label">137</span></a> Boveri (<cite lang="de" xml:lang="de">Ergebn. üb. d. Konstitution etc. des Zellkerns</cite>, Jena, 1904;
+and “Zellen-Studien VI.” <cite lang="de" xml:lang="de">Jen. Zeitschr.</cite> 43, 1907) has made it highly probable
+by experiments that the different chromosomes of the nucleus of the sexual
+products play a different part in morphogenesis, though not in the sense of
+different single representatives of different single organs. This doctrine, of
+course, would not alter the whole problem very much: the chromosomes
+would only be <em>means</em> of morphogenesis and nothing else, no matter whether
+they were of equal or of different formative value. It only is with regard to
+the problem of the determination of sex (see page <a href="#Page_107">107</a>, note <a href="#Footnote_46_46">46</a>), that the
+morphogenetic singularity of <em>one</em> certain specific chromosome can be said to
+be proved.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_138_138" id="Footnote_138_138"></a><a href="#FNanchor_138_138"><span class="label">138</span></a> H. M. Vernon, <cite>Variations in Animals and Plants</cite>, London, 1903.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_139_139" id="Footnote_139_139"></a><a href="#FNanchor_139_139"><span class="label">139</span></a> De Vries, <cite lang="de" xml:lang="de">Die Mutationstheorie</cite>, i., 1901; and Klebs, <cite lang="de" xml:lang="de">Jahrb. wiss. Bot.</cite>
+42, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_140_140" id="Footnote_140_140"></a><a href="#FNanchor_140_140"><span class="label">140</span></a> They would not be “real exceptions” if Klebs (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 24,
+1907) were right in saying that both variations and mutations owe their
+existence to external agents. What is really <em>proved</em> by Klebs is the possibility
+of changing the <em>type</em> of a curve of variation and of provoking certain discontinuous
+varieties by external means. See also Blaringhem (<cite lang="fr" xml:lang="fr">Comptes rend.</cite>
+1905–6, and <cite lang="fr" xml:lang="fr">Soc. de Biol.</cite> 59, 1905), and MacDougal (<i>Rep. Depart. Bot. Res.,
+5th Year-book Carnegie Inst.</i>, Washington, 129).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_141_141" id="Footnote_141_141"></a><a href="#FNanchor_141_141"><span class="label">141</span></a> H. de Vries, <i>Species and Varieties: their Origin by Mutation</i>, London,
+1905. A short review of the “mutation-theory” is given by Francé in
+<cite lang="de" xml:lang="de">Zeitschrift f. d. Ausbau d. Entwickelungslehre</cite>, i. 1907. It is well known
+that Gautier, and, in the first place, Korshinsky, advocated a similar view
+previous to the authors named in the text.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_142_142" id="Footnote_142_142"></a><a href="#FNanchor_142_142"><span class="label">142</span></a> Recent years have created the beginnings of a systematics based on
+chemical differences of metabolism and its products: such differences in
+fact have been found to go hand in hand with diversities of the type in
+some cases (v. Bunge, Przibram, etc.).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_143_143" id="Footnote_143_143"></a><a href="#FNanchor_143_143"><span class="label">143</span></a> We prefer this unpretending definition of the theory of descent to every
+other. As soon as one introduces into the definition the concept of the
+“transmutability of species,” the term “species” would require a special
+definition, and that would lead to difficulties which it is unnecessary
+to deal with for our main purposes. It has been remarked by Krašan,
+(<cite lang="de" xml:lang="de">Ausichten und Gespräche über die individuelle und specifische Gestaltung
+in der Natur</cite>) and by several other writers, that the problem of
+mutability or immutability of course relates to the individuals in the first
+place. I should like to add to this remark that the possibility must be
+admitted of the individuals being transmutable, whilst the “species”
+are not transmutable at the same time, the line of the “species” being a fixed
+order, through which the “individuals” have to pass in the course of their
+generations. What is meant here will become clearer, when we study the
+different possible aspects of “phylogeny.”</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_144_144" id="Footnote_144_144"></a><a href="#FNanchor_144_144"><span class="label">144</span></a> It seems to me that my argument gives a broader logical basis to the
+theory of descent than does that of G. Wolff (<cite lang="de" xml:lang="de">Die Begründung der
+Abstammungslehre</cite>, München, 1907). Wolff starts from the concept of
+organic teleology, and thus finds the only reason for accepting the theory
+of transformism in the existence of so-called “rudimentary organs”; these
+organs would form an obstacle to teleology if they could not be regarded
+as inherited.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_145_145" id="Footnote_145_145"></a><a href="#FNanchor_145_145"><span class="label">145</span></a> See Wigand, <i>Der Darwinismus und die Naturforschung Newton’s und
+Cuvier’s</i>, Braunschweig, 1874–7; Nägeli, <i>Mechanisch-physiologische Theorie
+der Abstammungslehre</i>, München, 1884; G. Wolff, <i>Beiträge zur Kritik der
+Darwin’schen Lehre</i>, 2nd ed. Leipzig, 1898; etc.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_146_146" id="Footnote_146_146"></a><a href="#FNanchor_146_146"><span class="label">146</span></a> <cite lang="de" xml:lang="de">Darwinismus und Lamarckismus</cite>, München, 1905.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_147_147" id="Footnote_147_147"></a><a href="#FNanchor_147_147"><span class="label">147</span></a> This would not be true, if the varieties of plants produced by Blaringhem,
+Klebs, and MacDougal by means of <em>external</em> agents were really
+“mutations” (comp. page 238, note 3).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_148_148" id="Footnote_148_148"></a><a href="#FNanchor_148_148"><span class="label">148</span></a> Of course, the inheritance of mutations would imply a certain sort of
+“inheritance of acquired characters,” on the condition stated in the preceding
+note. But, probably, the germs of the next generation might be
+regarded here as being directly affected by the external agent, in a manner
+that will briefly be mentioned later on in the text.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_149_149" id="Footnote_149_149"></a><a href="#FNanchor_149_149"><span class="label">149</span></a> Comp. page 238, note 2.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_150_150" id="Footnote_150_150"></a><a href="#FNanchor_150_150"><span class="label">150</span></a> Certain English authors have applied the term “modification” to all kinds
+of organic properties acquired from without, whether they are adapted or not.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_151_151" id="Footnote_151_151"></a><a href="#FNanchor_151_151"><span class="label">151</span></a> Of course the inheritance of specific values from the results of fluctuating
+variations, leading to new averages of variability (see p. <a href="#Page_265">265</a>), may also be
+understood in this manner, the conditions of nourishment acting upon the
+adult and upon its germs equally well.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_152_152" id="Footnote_152_152"></a><a href="#FNanchor_152_152"><span class="label">152</span></a> <cite lang="de" xml:lang="de">Berichte üb. d. Sitzung. d. Ges. f. Bot.</cite>, Hamburg, 1887, 3 Heft.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_153_153" id="Footnote_153_153"></a><a href="#FNanchor_153_153"><span class="label">153</span></a> Quite recently Kammerer (<cite lang="de" xml:lang="de">Arch. Entw. Mech.</cite> 25, 1907, p. 7) has
+published very important experiments on the inheritance of “acquired”
+modifications with regard to the peculiarities of reproduction in <i class="biological-name">Salamandra
+atra</i> and <i class="biological-name">S. maculosa</i>. It seems rather improbable&mdash;though not absolutely
+impossible&mdash;that the germ cells were directly affected by the external
+modifying agent in this case.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_154_154" id="Footnote_154_154"></a><a href="#FNanchor_154_154"><span class="label">154</span></a> We have not spoken about the hypothetic inheritance of pure physiological
+adaptations, for it is clear without further discussion that innate
+specific immunity, for instance, being a specific “adaptedness” (<i>see</i> p. <a href="#Page_186">186</a>)
+<em>might</em> be due to the inheritance of the results of active immunity as an
+adaptation, just as adaptive congenital structures <em>might</em> be due to such
+an inheritance.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_155_155" id="Footnote_155_155"></a><a href="#FNanchor_155_155"><span class="label">155</span></a> C. E. v. Baer clearly discriminated between the type, the degree of
+organisation, and the histological structure. All these three topics indeed
+have to be taken into account separately; the third alone is of the adaptive
+type. All of them may be independent of each other: the Amoeba may
+be as adapted histologically as is a high vertebrate, but it is of much
+lower type; and in its own type it is of a lower degree of organisation than
+Radiolaria are.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_156_156" id="Footnote_156_156"></a><a href="#FNanchor_156_156"><span class="label">156</span></a> I repeat once more that we are dealing here with dogmatic “Neo-”Lamarckism
+exclusively. This theory indeed claims to explain <em>all</em> features
+and properties of organic bodies on the basis of the feeling of needs and
+storing of contingent fulfilments and on this basis alone, just as dogmatic
+“Neo”-Darwinism claims to account for <em>all</em> those phenomena on the
+ground of contingent variations and natural selection. Darwin himself, as
+we have seen, intentionally left unexplained certain primary features of life
+and therefore cannot be blamed for having failed to explain them, though
+even then his theory remains wrong. Lamarck personally considered a
+real primary organisatory law of phylogeny as being of fundamental importance,
+and therefore he is not in the least responsible if “Neo-Lamarckism”
+fails as a universal theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_157_157" id="Footnote_157_157"></a><a href="#FNanchor_157_157"><span class="label">157</span></a> Compare also the excellent criticism of Lamarckism lately given by
+G. Wolff, <cite lang="de" xml:lang="de">Die Begründung der Abstammungslehre</cite>, München, 1907.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_158_158" id="Footnote_158_158"></a><a href="#FNanchor_158_158"><span class="label">158</span></a> It has also very often been said by Darwinians that Lamarckism is
+only able to explain those cases of adaptedness which relate to active
+functioning but not mere passive adapted characters, like “mimicry” for
+example. But this argument <em>taken by itself</em>, it seems to me, would not be
+fatal to Neo-Lamarckism in the special form August Pauly gave to this
+doctrine.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_159_159" id="Footnote_159_159"></a><a href="#FNanchor_159_159"><span class="label">159</span></a> But nothing more. All “mutations” hitherto observed in nature or
+(comp. page 238, note 3) experimentally produced relate only to “varieties”
+and not to “species.” One could hardly say that the recent investigations
+about the production of mutations by <em>external</em> means have strengthened
+their importance for the general theory of transformism.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_160_160" id="Footnote_160_160"></a><a href="#FNanchor_160_160"><span class="label">160</span></a> The word “possible” relating to originating, of course, not to surviving.
+It is here that natural selection may acquire its logical importance alluded
+to above (see page <a href="#Page_264">264</a>).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_161_161" id="Footnote_161_161"></a><a href="#FNanchor_161_161"><span class="label">161</span></a> The discussions in the second volume of this book will show the possible
+significance of such an analysis. We at present are dealing with entelechy
+in a quasi-popular manner.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_162_162" id="Footnote_162_162"></a><a href="#FNanchor_162_162"><span class="label">162</span></a> See pp. <a href="#Page_26">26</a>, <a href="#Page_45">45</a>, <a href="#Page_54">54</a>, etc.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_163_163" id="Footnote_163_163"></a><a href="#FNanchor_163_163"><span class="label">163</span></a> An immanent vitalistic phylogeny <em>without</em> a pre-established end has
+recently been advocated by H. Bergson (<i>L’évolution créatrice</i>, Paris, 1907).</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_164_164" id="Footnote_164_164"></a><a href="#FNanchor_164_164"><span class="label">164</span></a> In this connection the problem may be raised, whether there can be such
+a thing as unchangeable “species” in spite of the mutability of the
+individuals. Compare page 251, note 1.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_165_165" id="Footnote_165_165"></a><a href="#FNanchor_165_165"><span class="label">165</span></a> On account of the limited size of the earth a certain final stage of
+human civilisation might be expected in a future time; but it would be
+the size of the earth which determined this end, and not the process of
+civilisation itself.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_166_166" id="Footnote_166_166"></a><a href="#FNanchor_166_166"><span class="label">166</span></a> <cite lang="de" xml:lang="de">Die Grenzen der naturwissenschaftlichen Begriffsbildung</cite>, Tübingen and
+Leipzig, 1902.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_167_167" id="Footnote_167_167"></a><a href="#FNanchor_167_167"><span class="label">167</span></a> The word “universality” to be understood here in quite an unpretentious
+quasi-popular meaning, not strictly epistemologically.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_168_168" id="Footnote_168_168"></a><a href="#FNanchor_168_168"><span class="label">168</span></a> To avoid mistakes I wish to say here most emphatically that, according
+to Rickert, the method of history is regarded as completely <em>free</em> from subjectivity
+as soon as its “values” are once <em>established</em>. But this cannot
+avail to save the theory.</p></div>
+
+<div class="footnote">
+
+<p><a name="Footnote_169_169" id="Footnote_169_169"></a><a href="#FNanchor_169_169"><span class="label">169</span></a> This is a rather optimistic conception of “history.” Personally, I
+must confess that even its emotional and practical importance seems to me
+to be at least diminished by the retarding effects which all sorts of
+“historical” considerations&mdash;in science as well as in arts and in public life&mdash;carry
+with them. All real progress is non-historical&mdash;and its champions
+almost always have become martyrs: this fact seems not to recommend
+history as a means of education, except for persons of a very strong
+character.</p></div></div>
+
+
+
+
+
+
+
+
+
+<pre>
+
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+
+
+
+End of the Project Gutenberg EBook of The Science and Philosophy of the
+Organism, by Hans Driesch
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+</body>
+</html>
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author	Roger Frank <rfrank@pglaf.org>	2025-10-14 18:40:16 -0700
committer	Roger Frank <rfrank@pglaf.org>	2025-10-14 18:40:16 -0700
commit	b8080dd6580de79d538913ecf030c66f01538630 (patch)
tree	53ba070735e7b8c80b3488ea62b2a08d14fa9341