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diff --git a/40473-0.txt b/40473-0.txt index 49b159b..a69698c 100644 --- a/40473-0.txt +++ b/40473-0.txt @@ -1,42 +1,4 @@ -Project Gutenberg's The History of Creation, Vol. II (of 2), by Ernst Haeckel - -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 History of Creation, Vol. II (of 2) - Or the Development of the Earth and its Inhabitants by the - Action of Natural Causes - -Author: Ernst Haeckel - -Translator: E. Ray Lankester - -Release Date: August 14, 2012 [EBook #40473] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CREATION, VOL II *** - - - - -Produced by Adrian Mastronardi, Turgut Dincer, Jason Palmer -and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive) - - - - - - - - +*** START OF THE PROJECT GUTENBERG EBOOK 40473 *** +------------------------------------------------------------------+ | Transcriber’s note: | @@ -14694,361 +14656,4 @@ _D. APPLETON & CO., Publishers, 1, 3, & 5 Bond Street, N. 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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 History of Creation, Vol. II (of 2) - Or the Development of the Earth and its Inhabitants by the - Action of Natural Causes - -Author: Ernst Haeckel - -Translator: E. Ray Lankester - -Release Date: August 14, 2012 [EBook #40473] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CREATION, VOL II *** - - - - -Produced by Adrian Mastronardi, Turgut Dincer, Jason Palmer -and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive) - - - - - - - - - - +------------------------------------------------------------------+ - | Transcriber's note: | - | | - | This book was published in two volumes, of which this is the | - | second. The first volume was released as Project Gutenberg ebook | - | #40472, available at http://www.gutenberg.org/ebooks/40472 | - | | - | Numbers enclosed in square brackets, e.g. [1], relate to | - | footnotes, which have been placed at the end of the text. | - | Numbers enclosed in parentheses, e.g. (1), relate to works | - | referred to in the text and listed at the end of this volume. | - | | - | In the text versions of these two volumes, words in _italics_ | - | are enclosed in underscores, +bold+ words are enclosed in plus | - | signs, and words in =Gothic script= are enclosed in equal signs. | - | Curly brackets are used to represent subscripts, e.g. k{1}. | - +------------------------------------------------------------------+ - - - - - THE HISTORY OF CREATION. - - - - -[Illustration: Hypothetical Sketch of the Monophyletic Origin of Man.] - - - - - THE - HISTORY OF CREATION: - - _OR THE DEVELOPMENT OF THE EARTH AND ITS - INHABITANTS BY THE ACTION OF NATURAL CAUSES._ - - A POPULAR EXPOSITION OF - THE DOCTRINE OF EVOLUTION IN GENERAL, AND OF THAT OF - DARWIN, GOETHE, AND LAMARCK IN PARTICULAR. - - FROM THE GERMAN OF - ERNST HAECKEL, - PROFESSOR IN THE UNIVERSITY OF JENA. - - THE TRANSLATION REVISED BY - PROFESSOR E. RAY LANKESTER, M.A., F.R.S., - FELLOW OF EXETER COLLEGE, OXFORD. - - _IN TWO VOLUMES._ - VOL. II. - - NEW YORK: - D. APPLETON AND COMPANY, - 1, 3, AND 5 BOND STREET. - 1880. - - - - - A sense sublime - Of something far more deeply interfused, - Whose dwelling is the light of setting suns, - And the round ocean, and the living air, - And the blue sky, and in the mind of man; - A motion and a spirit that impels - All thinking things, all objects of all thought, - And rolls through all things. - - In all things, in all natures, in the stars - Of azure heaven, the unenduring clouds, - In flower and tree, in every pebbly stone - That paves the brooks, the stationary rocks, - The moving waters and the invisible air. - - WORDSWORTH. - - - - -CONTENTS OF VOL. II. - - - CHAPTER XV. - PAGE - PERIODS OF CREATION AND RECORDS OF CREATION. - - Reform of Systems by the Theory of Descent.--The Natural System - as a Pedigree.--Palæontological Records of the - Pedigree.--Petrifactions as Records of Creation.--Deposits of the - Neptunic Strata and the Enclosure of Organic Remains.--Division - of the Organic History of the Earth into Five Main Periods: - Period of the Tangle Forests, Fern Forests, Pine Forests, - Foliaceous Forests, and of Cultivation.--The Series of Neptunic - Strata.--Immeasurable Duration of the Periods which have elapsed - during their Formation.--Deposits of Strata only during the - Sinking, not during the Elevation of the Ground.--Other Gaps in - the Records of Creation.--Metamorphic Condition of the most - Ancient Neptunic Strata.--Small Extent of Palæontological - Experience.--Small proportion of Organisms and of Parts of - Organisms Capable of Petrifying.--Rarity of many Petrified - Species.--Want of Fossilised Intermediate Forms.--Records of the - Creation in Ontogeny and in Comparative Anatomy 1 - - - CHAPTER XVI. - - PEDIGREE AND HISTORY OF THE KINGDOM OF THE PROTISTA. - - Special Mode of Carrying out the Theory of Descent in the - Natural System of Organisms.--Construction of Pedigrees.--Descent - of all Many-celled from Single-celled Organisms.--Descent of - Cells from Monera.--Meaning of Organic Tribes, or Phyla.--Number - of the Tribes in the Animal and Vegetable Kingdoms.--The - Monophyletic Hypothesis of Descent, or the Hypothesis of one - Common Progenitor, and the Polyphyletic Hypothesis of Descent, - or the Hypothesis of many Progenitors.--The Kingdom of Protista, - or Primæval Beings.--Eight Classes of the Protista Kingdom: - Monera, Amoebæ, or Protoplastæ; Whip-swimmers, or Flagellata; - Ciliated-balls, Cili Catallacta; Labyrinth-streamers, or - Labyrinthuleæ; Flint-cells, or Diatomeæ; Mucous-moulds, or - Myxomycetes; Root-footers (Rhizopoda).--Remarks on the General - Natural History of the Protista: Their Vital Phenomena, - Chemical Composition, and Formation (Individuality and - Fundamental Form).--Phylogeny of the Prostista Kingdom 36 - - - CHAPTER XVII. - - PEDIGREE AND HISTORY OF THE VEGETABLE KINGDOM. - - The Natural System of the Vegetable Kingdom.--Division of the - Vegetable Kingdom into Six Branches and Eighteen Classes.--The - Flowerless Plants (Cryptogamia).--Sub-kingdom of the Thallus - Plants.--The Tangles, or Algæ (Primary Algæ, Green Algæ, Brown - Algæ, Red Algæ).--The Thread-plants, or Inophytes (Lichens and - Fungi).--Sub-kingdom of the Prothallus Plants.--The Mosses, or - Muscinæ (Water-mosses, Liverworts, Leaf-mosses, - Bog-mosses).--The Ferns, or Filicinæ (Leaf-ferns, Bamboo-ferns, - Water-ferns, Scale-ferns).--Sub kingdom of Flowering Plants - (Phanerogamia).--The Gymnosperms, or Plants with Naked Seeds - (Palm-ferns = Cycadeæ; Pines = Coniferæ).--The Angiosperms, or - Plants with Enclosed Seeds.--Monocotylæ.--Dicotylæ.--Cup-blossoms - (Apetalæ).--Star-blossoms (Diapetalæ).--Bell-blossoms - (Gamopetalæ) 77 - - - CHAPTER XVIII. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - I. ANIMAL-PLANTS AND WORMS. - - The Natural System of the Animal Kingdom.--Linnæus' and Lamarck's - Systems.--The Four Types of Bär and Cuvier.--Their Increase to - Seven Types.--Genealogical Importance of the Seven Types as - Independent Tribes of the Animal Kingdom.--Derivation of - Zoophytes and Worms from Primæval Animals.--Monophyletic and - Polyphyletic Hypothesis of the Descent of the Animal - Kingdom.--Common Origin of the Four Higher Animal Tribes out of - the Worm Tribe.--Division of the Seven Animal Tribes into - Sixteen Main Classes, and Thirty-eight Classes.--Primæval - Animals (Monera, Amoebæ, Synamoebæ), Gregarines, Infusoria, - Planæades, and Gastræades (Planula and Gastrula).--Tribe of - Zoophytes.--Spongiæ (Mucous Sponges, Fibrous Sponges, Calcareous - Sponges).--Sea Nettles, or Acalephæ (Corals, Hood-jellies, - Comb-jellies).--Tribe of Worms 117 - - - CHAPTER XIX. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - II. MOLLUSCA, STAR-FISHES, AND ARTICULATED ANIMALS. - - Tribe of Molluscs.--Four Classes of Molluscs: Lamp-shells - (Spirobranchia); Mussels (Lamellibranchia); Snails (Cochlides); - Cuttle-fish (Cephalopoda).--Tribe of Star-fishes, or - Echinoderma.--Their Derivation from Ringed Worms (Mailed Worms, - or Phracthelminthes).--The Alternation of Generation in the - Echinoderma.--Four Classes of Star-fish: Sea-stars (Asteridea); - Sea-lilies (Crinoidea); Sea-urchins (Echinidea); Sea-cucumbers - (Holothuridea).--Tribe of Articulated Animals, or - Arthropoda.--Four Classes of Articulated Animals: Branchiata, or - Crustacea, breathing through gills; Jointed Crabs; Mailed - Crabs; Articulata Tracheata, breathing through Air - Tubes.--Spiders (Long Spiders, Round - Spiders).--Myriopods.--Insects.--Chewing and Sucking - Insects.--Pedigree and History of the Eight Orders of Insects 154 - - - CHAPTER XX. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - III. VERTEBRATE ANIMALS. - - The Records of the Creation of Vertebrate Animals (Comparative - Anatomy, Embryology, and Palæontology).--The Natural System of - Vertebrate Animals.--The Four Classes of Vertebrate Animals, - according to Linnæus and Lamarck.--Their Increase to Nine - Classes.--Main Class of the Tube-hearted, or Skull-less Animals - (the Lancelet).--Blood Relationship between the Skull-less Fish - and the Tunicates.--Agreement in the Embryological Development - of Amphioxus and Ascidiæ.--Origin of the Vertebrate Tribe out of - the Worm Tribe.--Main Class of Single-nostriled, or - Round-mouthed Animals (Hag and Lampreys).--Main Class of - Anamnionate Animals, devoid of Amnion.--Fishes (Primæval Fish, - Cartilaginous Fish, Osseous Fish).--Mud-fish, or Dipneusta.--Sea - Dragons, or Halisauria.--Frogs and Salamanders, or Amphibia - (Mailed Amphibia, Naked Amphibia).--Main Class of Amnionate - Animals, or Amniota.--Reptiles (Primary Reptiles, Lizards, - Serpents, Crocodiles, Tortoises, Flying Reptiles, Dragons, - Beaked Reptiles).--Birds (Feather-tailed, Fan-tailed, - Bush-tailed) 192 - - - CHAPTER XXI. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - IV. MAMMALS. - - The System of Mammals according to Linnæus and - Blainville.--Three Sub-classes of Mammals (Ornithodelphia, - Didelphia, Monodelphia).--Ornithodelphia, or Monotrema.--Beaked - Animals (Ornithostoma).--Didelphia, or Marsupials.--Herbivorous - and Carnivorous Marsupials.--Monodelphia, or Placentalia - (Placental Animals).--Meaning of the Placenta.--Tuft - Placentalia.--Girdle Placentalia.--Disc - Placentalia.--Non-deciduates, or Indeciduata.--Hoofed - Animals.--Single and Double-hoofed Animals.--Whales.--Toothless - Animals.--Deciduates, or Animals with - Decidua.--Semi-apes.--Gnawing Animals.--Pseudo-hoofed - Animals.--Insectivora.--Beasts of Prey.--Bats.--Apes 231 - - - CHAPTER XXII. - - ORIGIN AND PEDIGREE OF MAN. - - The Application of the Theory of Descent to Man.--Its Immense - Importance and Logical Necessity.--Man's Position in the Natural - System of Animals, among Disco-placental Animals.--Incorrect - Separation of the Bimana and Quadrumana.--Correct Separation of - Semi-apes from Apes.--Man's Position in the Order of - Apes.--Narrow-nosed Apes (of the Old World) and Flat-nosed Apes - (of America).--Difference of the two Groups.--Origin of Man from - Narrow-nosed Apes.--Human Apes, or Anthropoides.--African - Human-apes (Gorilla and Chimpanzee).--Asiatic Human-apes (Orang - and Gibbon).--Comparison between the different Human Apes and - the different Races of Men.--Survey of the Series of the - Progenitors of Man.--Invertebrate Progenitors (Prochordata) and - Vertebrate Progenitors 263 - - - CHAPTER XXIII. - - MIGRATION AND DISTRIBUTION OF MANKIND. HUMAN SPECIES AND HUMAN - RACES. - - Age of the Human Race.--Causes of its Origin.--The Origin of - Human Language.--Monophyletic or Single, Polyphyletic or - Multiple Origin of the Human Race.--Derivation of Man from many - Pairs.--Classification of the Human Races.--System of Twelve - Species of Men.--Woolly-Haired Men, or Ulotrichis.--Bushy-Haired - (Papuans, Hottentots).--Fleecy-haired (Caffres, - Negroes).--Straight-haired Men, or Lissotrichi.--Stiff-haired - (Australians, Malays, Mongols, Arctic, and American - Tribes).--Curly-haired (Dravidas, Nubians, Midlanders).--Number - of Population.--Primæval Home of Man (South Asia, or - Lemuria).--Nature of Primæval Men.--Number of Primæval Languages - (Monoglottists and Polyglottists).--Divergence and Migration of - the Human Race.--Geographical Distribution of the Human Species 296 - - - CHAPTER XXIV. - - OBJECTIONS AGAINST, AND PROOFS OF THE TRUTH OF, THE THEORY OF - DESCENT. - - Objections to the Doctrine of Filiation.--Objections of Faith - and Reason.--Immeasurable Length of the Geological - Periods.--Transition Forms between Kindred Species.--Dependence - of Stability of Form on Inheritance, and of the Variability of - Form on Adaptation.--Origin of very Complicated Arrangement of - Organisation.--Gradual Development of Instincts and Mental - Activities.--Origin of à priori Knowledge from Knowledge a - posteriori.--The Knowledge requisite for the Correct - Understanding of the Doctrine of Filiation.--Necessary - Interaction between Empiricism and Philosophy.--Proofs of the - Theory of Descent.--Inner Causal-Connection between all the - Biological Series of Phenomena.--The Direct Proof of the Theory - of Selection.--Relation of the Theory of Descent to - Anthropology.--Proofs of the Animal Origin of Man.--The Pithecoid - Theory as an Inseparable Part of the Theory of - Descent.--Induction and Deduction.--Gradual Development of the - Human Mind.--Body and Mind.--Human Soul and Animal Soul.--A Glance - at the Future 334 - - - LIST OF WORKS REFERRED TO IN THE TEXT 371 - - APPENDIX (Explanation of the Plates) 379 - - INDEX 402 - - - - -LIST OF ILLUSTRATIONS. - - -PLATES. - - XV.--Hypothetical Sketch of the Monophyletic Origin - of Man _Frontispiece_ - - IV.--Hand of Nine different Mammals _To face page_ 34 - - V.--Single-Stemmed, or Monophyletic, Pedigree of the - Vegetable Kingdom " 112 - - VI.--Historical Growth of the Six Great Stems of Animals " 122 - - VII.--Animal Plants, or Zoophytes " 140 - - VIII.--Star Fishes--First Generation _Between pp._ 170, 171 - - IX.--Star Fishes--Second Generation " " " - - X.--Nauplius-Youth-Form of Six Crab Fish " 174, 175 - - XI.--Adult-Form of the same Six Crab Fish " " " - - XII.--Ascidia and Amphioxus " 201, 202 - - XIII.--Ascidia and Amphioxus " " " - - XIV.--Single, or Monophyletic, Pedigree of Back-boned - Animals _To face page_ 222 - - - FIGURES. - - 8.--Protamoeba Primitiva 52 - - 9.--Bathybius Hæckelii 53 - - 10.--Amoeba Sphærococcus 54 - - 11.--Euglena Striata 57 - - 12.--Magosphæra Planula 58 - - 13.--Labyrinthula Macrocystis 59 - - 14.--Navicula Hippocampus 60 - - 15.--Physarum Albipes 61 - - 16.--Cyrtidosphæra Echinoides 66 - - 17.--Caulerpa Denticulata 87 - - 18.--Euastrum Rota 88 - - 19.--Fucus Vesiculosus (egg of) 90 - - - - -THE HISTORY OF CREATION. - - - - -CHAPTER XV. - -PERIODS OF CREATION AND RECORDS OF CREATION. - - - Reform of Systems by the Theory of Descent.--The Natural System - as a Pedigree.--Palæontological Records of the - Pedigree.--Petrifactions as Records of Creation.--Deposits of the - Neptunic Strata and the Enclosure of Organic Remains.--Division - of the Organic History of the Earth into Five Main Periods: - Period of the Tangle Forests, Fern Forests, Pine Forests, - Foliaceous Forests, and of Cultivation.--The Series of Neptunic - Strata.--Immeasurable Duration of the Periods which have elapsed - during their Formation.--Deposits of Strata only during the - Sinking, not during the Elevation of the Ground.--Other Gaps in - the Records of Creation.--Metamorphic Condition of the most - Ancient Neptunic Strata.--Small Extent of Palæontological - Experience.--Small proportion of Organisms and of Parts of - Organisms Capable of Petrifying.--Rarity of many Petrified - Species.--Want of Fossilised Intermediate Forms.--Records of the - Creation in Ontogeny and in Comparative Anatomy. - - -The revolutionary influence which the Theory of Descent must exercise -upon all sciences, will in all probability affect no branch of science, -excepting Anthropology, so much as the descriptive portion of natural -history, that which is known as systematic Zoology and Botany. Most -naturalists who have hitherto occupied themselves with arranging the -different systems of animals and plants, have collected, named, and -arranged the different species of these natural bodies with much the -same interest as antiquarians and ethnographers collect the weapons and -utensils of different nations. Many have not even risen above the degree -of intelligence with which people usually collect, label, and arrange -crests, stamps, and similar curiosities. In the same manner as some -collectors find their pleasure in the similarity of forms, the beauty or -rarity of the crests or stamps, and admire in them the inventive art of -man, so many naturalists take a delight in the manifold forms of animals -and plants, and marvel at the rich imagination of the Creator, at His -unwearied creative activity, and at His curious fancy for forming, by -the side of so many beautiful and useful organisms, also a number of -ugly and useless ones. - -This childlike treatment of systematic Zoology and Botany is completely -annihilated by the Theory of Descent. In the place of the superficial -and playful interest with which most naturalists have hitherto regarded -organic structures, we now have the much higher interest of the -intelligent understanding which detects in the _related forms_ of -organisms their true _blood relationships_. The _Natural System of -animals and plants_, which was formerly valued either only as a registry -of names, to facilitate the survey of the different forms, or as a table -of contents for the short expression of their degrees of similarity, -receives from the Theory of Descent the incomparably higher value of a -true _pedigree of organisms_. This pedigree is to disclose to us the -genealogical connection of the smaller and larger groups. It has to show -us in what way the different classes, orders, families, genera, and -species of the animal and vegetable kingdoms correspond with the -different branches, twigs, and groups of twigs of the pedigree. Every -wider and higher category or stage of the system (for example a class, -or an order) comprises a number of larger and stronger branches of the -pedigree; every narrower and lower category (for example a genus, or a -species) only a smaller and thinner group of twigs. It is only when we -thus view the natural system as a pedigree that we perceive its true -value. (Gen. Morph. ii. Plate XVII. p. 397.) - -Since we hold fast this genealogical conception of the Organic System, -to which alone undoubtedly the future of classificatory Zoology and -Botany belongs, we should now turn our attention to one of the most -essential, but also one of the most difficult, tasks of the -"non-miraculous history of creation," namely, to the actual construction -of the Organic Pedigree. Let us see how far we are already able to point -out all the different organic forms as the divergent descendants of a -single or of some few common original forms. But how can we construct -the actual pedigree of the animal and vegetable group of forms from our -knowledge of them, at present so scanty and fragmentary? The answer to -this question lies in what we have already remarked of the parallelism -of the three series of development--in the important causal relation -which connects the palæontological development of all organic tribes -with the embryological development of individuals, and with the -systematic development of groups. - -In order to accomplish our task we shall first have to direct our -attention to _palæontology_, or _the science of petrifactions_. For if -the Theory of Descent is really true, if the petrified remains of -formerly living animals and plants really proceed from the extinct -primæval ancestors and progenitors of the present organisms, then, -without anything else, the knowledge and comparison of petrifactions -ought to disclose to us the pedigree of organisms. However simple and -clear this may seem in theory, the task becomes extremely hard and -complicated when it is actually taken in hand. Its practical solution -would be very difficult even if the petrifactions were to any extent -completely preserved. But this is by no means the case. The obvious -records of creation which lie buried in petrifactions are imperfect -beyond all measure. Hence it is necessary critically to examine these -records, and to determine the value which petrifactions possess for the -history of the development of organic tribes. As I have previously -discussed the general importance of petrifactions as the records of -creation, when we were considering Cuvier's merits in the science of -fossils, we may now at once examine the conditions and circumstances -under which the remains of organic bodies became petrified and preserved -in a more or less recognizable form. - -As a rule we find petrifactions or fossils enclosed only in those stones -which have been deposited in layers as mud by water, and which are on -that account called neptunic, stratified, or sedimentary rocks. The -deposition of such strata could of course only commence after the -condensation of watery vapour into liquid water had taken place in the -course of the earth's history. After that period, which we considered in -our last chapter, not only did life begin on the earth, but also an -uninterrupted and exceedingly important transformation of the rigid -inorganic crust of the earth. The water began that extremely important -mechanical action by which the surface of the earth is perpetually, -though slowly, transformed. I may surely presume that it is generally -known what an extremely important influence, in this respect, is even -yet exercised by water at every moment. As it falls down as rain, -trickling through the upper strata of the earth's crust, and flowing -down from heights into hollows, it chemically dissolves different -mineral parts of the ground, and mechanically washes away the loose -particles. In flowing down from mountains water carries their debris -into the plains, or deposits it as mud in stagnant lakes. Thus it -continually works at lowering mountains and filling up valleys. In like -manner the breakers of the sea work uninterruptedly at the destruction -of the coasts and at filling up the bottom of the sea with the debris -they wash down. The action of water alone, if it were not counteracted -by other circumstances, would in time level the whole earth. There can -be no doubt that the mountain masses--which are annually carried down as -mud into the sea, and deposited on its floor--are so great that in the -course of a longer or shorter period, say a few millions of years, the -surface of the earth would be completely levelled and become enclosed by -a continuous sheet of water. That this does not happen is owing to the -perpetual volcanic action of the fiery-fluid centre of the earth. The -surging of the melted nucleus against the firm crust necessitates -continual alternations of elevation and depression on the different -parts of the earth's surface. These elevations and depressions for the -most part take place very slowly; but, as they continue for thousands of -years, by the combined effect of small, interrupted movements, they -produce results no less grand than does the counteracting and levelling -action of water. - -Since the elevations and depressions of the different parts of the -earth alternate with one another in the course of millions of years, -first this and then that part of the earth's surface is above or below -the level of the sea. I have already given examples of this in the -preceding chapter (vol. i. p. 361). Hence, in all probability, there is -no part of the outer crust of the earth which has not been repeatedly -above and also below the level of the sea. This repeated change explains -the variety and the different composition of the numerous neptunic -strata of rocks, which in most places have been deposited one above -another in considerable thickness. In the different periods of the -earth's history during which these deposits took place there lived -various and different populations of animals and plants. When their dead -bodies sank to the bottom of the waters, the forms of the bodies -impressed themselves upon the soft mud, and imperishable parts, such as -hard bones, teeth, shells, etc., became enclosed in it uninjured. These -were preserved in the mud, which condensed them into neptunic rock, and -as petrifactions they now serve to characterise the respective strata. -By a careful comparison of the different strata lying one above another, -and the petrifactions preserved in them, it has become possible to -decide the relative age of the strata and groups of strata, and to -establish, by direct observation, the principal eras of phylogeny, that -is to say, the stages in history of the development of animal and -vegetable tribes. - -The different strata of neptunic rocks deposited one above another, -which are composed in very various ways of limestone, clay, and sand, -geologists have grouped together into an ideal System or Series, which -corresponds with the whole course of the organic history of the earth, -or with that portion of the earth's history during which organic life -existed. Just as so-called "universal history" falls into larger and -smaller periods, which are characterized by the conditions of -development of the most important nations at the respective epochs, and -are separated from one another by great events, so we also divide the -infinitely longer organic history of the earth into a series of greater -and less periods. Each of these periods is distinguished by a -characteristic flora and fauna, and by the specially strong development -of certain vegetable or animal groups, and each is separated from the -preceding and succeeding period by a striking change in the character of -its animal and vegetable inhabitants. - -In relation to the following survey of the historical course of -development which the large animal and vegetable tribes have passed -through, it will be desirable to say a few words first as to the -systematic classification of the neptunic groups of strata, and the -larger and smaller periods corresponding to them. As will be seen -directly, we are able to divide the whole of the sedimentary rocks lying -one above another into five main groups or periods, each period into -several subordinate groups of strata or _systems_, and each system of -strata again into still smaller groups or _formations_; finally, each -formation can again be divided into stages or sub-formations, and each -of these again into still smaller layers or beds. Each of the five great -rock-groups was deposited during a great division of the earth's -history, during a long _era_ or _epoch_; each system during a shorter -_period_; each formation during a still shorter _period_. In thus -reducing the periods of the organic history of the earth, and the -neptunic strata containing petrifactions deposited during those periods -into a connected system, we proceed exactly like the historian who -divides the history of nations into the three main divisions of -Antiquity, the Middle Ages, and Modern Times, and each of those sections -again into subordinate periods and epochs. But the historian by this -sharp systematic division, and by fixing the boundary of the periods by -particular dates, only seeks to facilitate his survey, and in no way -means to deny the uninterrupted connection of events and the development -of nations. Exactly the same qualification applies to our systematic -division, specification, or classification of the organic history of the -earth. Here, too, a continuous thread runs through the series of events -unbroken. We must therefore distinctly protest against the idea that by -sharply bounding the larger and smaller groups of strata, and the -periods corresponding with them, we in any way wish to adopt Cuvier's -doctrine of terrestrial revolutions, and of repeated new creations of -organic populations. That this erroneous doctrine has long since been -completely refuted by Lyell, I have already mentioned. (Compare vol. i. -p. 127.) - -The five great main divisions of the organic history of the earth, or -the palæontological history of development, we call the primordial, -primary, secondary, tertiary, and quaternary epochs. Each is distinctly -characterized by the predominating development of certain animal and -vegetable groups in it, and we might accordingly symbolically designate -the five epochs, on the one hand by the names of the groups of the -vegetable kingdom, and on the other hand by those of the different -classes of vertebrate animals. In this case the _first_, or primordial -epoch, would be the era of the Tangles (Algæ) and skull-less -Vertebrates; the _second_, or primary epoch, that of the Ferns and -Fishes; the _third_, or secondary epoch, that of Pine Forests and -Reptiles; the _fourth_, or tertiary epoch, that of Foliaceous Forests -and of Mammals; finally, the _fifth_, or quaternary epoch, the era of -Man, and his Civilization. The divisions or _periods_ which we -distinguish in each of the five _long eras_ (p. 14) are determined by -the different _systems_ of strata into which each of the five great -_rock-groups_ is divided (p. 15). We shall now take a cursory glance at -the series of these systems, and at the same time at the populations of -the five great epochs. - -The first and longest division of the organic history of the earth is -formed by the _primordial epoch_, or _the era of the Tangle Forests_. It -comprises the immense period from the first spontaneous generation, from -the origin of the first terrestrial organism, to the end of the Silurian -system of deposits. During this immeasurable space of time, which in all -probability was much longer than all the other four epochs taken -together, the three most extensive of all the neptunic systems of strata -were deposited, namely, the _Laurentian_, upon that the _Cambrian_, and -upon that the _Silurian_ system. The approximate thickness or size of -these three systems together amounts to 70,000 feet. Of these about -30,000 belong to the Laurentian, 18,000 to the Cambrian, and 22,000 to -the Silurian system. The average thickness of all the four other rock -groups, the primary, secondary, tertiary, and quaternary, taken -together, may amount at most to 60,000 feet; and from this fact alone, -apart from many other reasons, it is evident that the duration of the -primordial period was probably much longer than the duration of all the -subsequent periods down to the present day. Many thousands of millions -of years were required to deposit such masses of strata. Unfortunately, -by far the largest portion of the primordial group of strata is in the -metamorphic state (which we shall directly explain), and consequently -the petrifactions contained in them--the most ancient and most important -of all--have, to a great extent, been destroyed and become -unrecognisable. Only in one portion of the Cambrian strata have -petrifactions been preserved in a recognizable condition and in large -quantities. The most ancient of all distinctly preserved petrifactions -has been found in the lowest Laurentian strata (in the Ottawa -formation), which I shall afterwards have to speak of as the "Canadian -Life's-dawn" (Eozoon canadense). - -Although only by far the smaller portion of the primordial or -archilithic petrifactions are preserved to us in a recognizable -condition, still they possess the value of inestimable documents of the -most ancient and obscure times of the organic history of the earth. What -seems to be shown by them, in the first place, is that during the whole -of this immense period there existed only inhabitants of the waters. As -yet, at any rate, among all archilithic petrifactions, not a single one -has been found which can with certainty be regarded as an organism which -has lived on land. All the vegetable remains we possess of the -primordial period belong to the lowest of all groups of plants, to the -class of Tangles or Algæ, living in water. In the warm primæval sea, -these constituted the forests of the period, of the richness of which in -forms and density we may form an approximate idea from their present -descendants, the tangle forests of the Atlantic Sargasso sea. The -colossal tangle forests of the archilithic period supplied the place of -the forest vegetation of the mainland, which was then utterly wanting. -All the animals, also, whose remains have been found in archilithic -strata, like the plants, lived in water. Only crustacea are met with -among the animals with articulated feet, as yet no spiders and no -insects. Of vertebrate animals, only a very few remains of fishes are -known as having been found in the most recent of all primordial strata, -in the upper Silurian. But the headless vertebrate animals, which we -call _skull-less_, or _Acrania_, and out of which fishes must have been -developed, we suppose to have lived in great numbers during the -primordial epoch. Hence we may call it after the _Acrania_ as well as -after the _Tangles_. - -The _primary epoch_, or _the era of Fern Forests_, the second main -division of the organic history of the earth, which is also called the -palæolithic or palæozoic period, lasted from the end of the Silurian -formation of strata to the end of the Permian formation. This epoch was -also of very long duration, and again falls into three shorter periods, -during which three great systems of strata were deposited, namely, -first, the _Devonian_ system, or the old red sandstone; upon that, the -_Carboniferous_, or coal system; and upon this, the _Permian_ system. -The average thickness of these three systems taken together may amount -to about 42,000 feet, from which we may infer the immense length of time -requisite for their formation. - -The Devonian and Permian formations are especially rich in remains of -fishes, of primæval fish as well as enamelled fish (Ganoids), but the -bony fish (Teleostei) are absent from the strata of the primary epoch. -In coal are found the most ancient remains of animals living on land, -both of articulated animals (spiders and insects) as well as of -vertebrate animals (amphibious animals, like newts and frogs). In the -Permian system there occur, in addition to the amphibious animals, the -more highly-developed reptiles, and, indeed, forms nearly related to our -lizards (Proterosaurus, etc.). But, nevertheless, we may call the -primary epoch that of _Fishes_, because these few amphibious animals and -reptiles are insignificant in comparison with the immense mass of -palæozoic fishes. Just as Fishes predominate over the other vertebrate -animals, so _Ferns_, or Filices, predominate among the plants of this -epoch, and, in fact, real ferns and tree ferns (leafed ferns, or -Phylopteridæ), as well as bamboo ferns (Calamophytæ) and scaled ferns -(Lepidophytæ). These ferns, which grew on land, formed the chief part of -the dense palæolithic island forests, the fossil remains of which are -preserved to us in the enormously large strata of coal of the -Carboniferous system, and in the smaller strata of coal of the Devonian -and Permian systems. We are thus justified in calling the primary epoch -either the era of _Ferns_ or that of _Fishes_. - -The third great division of the palæontological history of development -is formed by the _secondary epoch_, or the _era of Pine Forests_, which -is also called the mesolithic or mesozoic epoch. It extends from the end -of the Permian system to the end of the Chalk formation, and is again -divided into three great periods. The stratified systems deposited -during this period are, first and lowest, the _Triassic_ system, in the -middle the _Jura_ system, and at the top the _Cretaceous_ system. The -average thickness of these three systems taken together is much less -than that of the primary group, and amounts as a whole only to about -15,000 feet. The secondary epoch can accordingly in all probability not -have been half so long as the primary epoch. - -Just as Fishes prevailed in the primary epoch, _Reptiles_ predominated -in the secondary epoch over all other vertebrate animals. It is true -that during this period the first birds and mammals originated; at that -time, also, there existed important amphibious animals, especially the -gigantic Labyrinthodonts, in the sea the wonderful sea-dragons, or -Halisaurii, swam about, and the first fish with bones were associated -with the many primæval fishes (Sharks) and enamelled fish (Ganoids) of -the earlier times; but the very variously developed kinds of reptiles -formed the predominating and characteristic class of vertebrate animals -of the secondary epoch. Besides those reptiles which were very nearly -related to the present living lizards, crocodiles, and turtles, there -were, during the mesolithic period, swarms of grotesquely shaped -dragons. The remarkable flying lizards, or Pterosaurii, and the colossal -land-dragons, or Dinosaurii, of the secondary epoch, are peculiar, as -they occur neither in the preceding nor in the succeeding epochs. The -secondary epoch may be called the era of _Reptiles_; but on the other -hand, it may also be called the era of _Pine Forests_, or more -accurately, of the _Gymnosperms_, that is, the epoch of _plants having -naked seeds_. For this group of plants, especially as represented by the -two important classes--the pines, or _Coniferæ_, and the palm-ferns, or -_Cycadeæ_--during the secondary epoch constituted a predominant part of -the forests. But towards the end of the epoch (in the Chalk period) the -plants of the pine tribe gave place to the leaf-bearing forests which -then developed for the first time. - - -SURVEY - -_Of the Palæontological Periods, or of the Greater Divisions of the -Organic History of the Earth._ - - -I. _First Epoch_: ARCHILITHIC ERA. _Primordial Epoch._ - -(Era of Skull-less Animals and Forests of Tangles.) - - 1. Older Primordial Period or Laurentian Period. - 2. Middle Primordial Period " Cambrian Period. - 3. Later Primordial Period " Silurian Period. - - -II. _Second Epoch_: PALÆOLITHIC ERA. _Primary Epoch._ - -(Era of Fish and Fern Forests.) - - 4. Older Primary Period or Devonian Period. - 5. Mid Primary Period " Coal Period. - 6. Later Primary Period " Permian Period. - - -III. _Third Epoch_: MESOLITHIC ERA. _Secondary Epoch._ - -(Era of Reptiles and Pine Forests.) - - 7. Older Secondary Period or Trias Period. - 8. Middle Secondary Period " Jura Period. - 9. Later Secondary Period " Chalk Period. - - -IV. _Fourth Epoch_: CÆNOLITHIC ERA. _Tertiary Epoch._ - -(Era of Mammals and Leaf Forests.) - - 10. Older Tertiary Period or Eocene Period. - 11. Newer Tertiary Period " Miocene Period. - 12. Recent Tertiary Period " Pliocene Period. - - -V. _Fifth Epoch_: ANTHROPOLITHIC ERA. _Quaternary Epoch._ - -(Era of Man and Cultivated Forests.) - - 13. Older Quaternary Period or Ice or Glacial Period. - 14. Newer Quaternary Period " Post Glacial Period. - 15. Recent Quaternary Period " Period of Culture. - -(The Period of Culture is the Historical Period, or the Period of -Tradition.) - -SURVEY - -_Of the Palæontological Formations, or those Strata of the Earth's Crust -containing Petrifactions._ - - - --------------------+-------------------+----------------------+-------------- - _Rock-Groups._ | _Systems._ | _Formations._ | _Synonyms of - | | | Formations._ - --------------------+-------------------+----------------------+------------- - V. _Quaternary { | - Group_, { XIV. Recent { 36. _Present_ | Upper alluvial - or { (Alluvium) { 35. _Recent_ | Lower alluvial - Anthropolithic { | - (Anthropozoic) { XIII. Pleistocene { 34. _Post glacial_ | Upper diluvial - groups of { (Diluvium) { 33. _Glacial_ | Lower diluvial - strata { | - - - IV. _Tertiary { XII. Pliocene { 32. _Arvernian_ | Upper pliocene - Group_, { (Late tertiary) { 31. _Sub-Appenine_ | Lower pliocene - or { | - Cænolithic { XI. Miocene { 30. _Falunian_ | Upper miocene - (Cænozoic) { (New tertiary) { 29. _Limburgian_ | Lower miocene - groups of { | - strata { { 28. _Gypsum_ | Upper eocene - { X. Eocene { 27. _Nummulitic_ | Mid eocene - { (Old tertiary) { 26. _London clay_ | Lower eocene - - - { { 25. _White chalk_ | Upper cretaceous - { IX. Cretaceous { 24. _Green sand_ | Mid cretaceous - { { 23. _Neocomian_ | Lower cretaceous - III. _Secondary { { 22. _Wealden_ | The Kentish Weald - Group_, { - or { { 21. _Portlandian_ | Upper oolite - Mesolithic { VIII. Jura { 20. _Oxfordian_ | Mid oolite - (Mesozoic) { { 19. _Bath_ | Lower oolite - groups of { { 18. _Lias_ | Lias formation - strata { - { { 17. _Keuper_ | Upper trias - { VII. Trias { 16. _Muschel-kalk_ | Mid trias - { { 15. _Bunter sand_ | Lower trias - - - { VI. Permian { 14. _Zechstein_ | Upper Permian - II. _Primary { { 13. | Lower Permian - Group_, { { 12. _Carboniferous | - or { V. Carbonic sandstone_ | Upper carbonic - Palæolithic { (coal) { 11. _Carboniferous | - (Palæozoic) { { limestone_ | Lower carbonic - groups of { IV. Devonian { 10. _Pilton_ | Upper Devonian - strata {(Old red sandstone){ 9. _Ilfracombe_ | Mid Devonian - { 8. _Linton_ | Lower Devonian - - - I. _Primordial { { 7. _Ludlow_ | Upper Silurian - Group_, { III. Silurian { 6. _Llandovery_ | Mid Silurian - or { { 5. _Llandeilo_ | Lower Silurian - Archilithic { - (Archizoic) { II. Cambrian { 4. _Potsdam_ | Upper Cambrian - groups of { { 3. _Longmynd_ | Lower Cambrian - strata { - { I. Laurentian { 2. _Labrador_ | Upper Laurentian - { { 1. _Ottawa_ | Lower Laurentian - - -The fourth main division of the organic history of the earth, the -_tertiary epoch_, or _era of Leafed Forests_, is much shorter and less -peculiar than the three first epochs. This epoch, which is also called -the cænolithic or cænozoic epoch, extended from the end of the -cretaceous system to the end of the pliocene system. The strata -deposited during it amount only to a thickness of about 3000 feet, and -consequently are much inferior to the three first great groups. The -three systems also into which the tertiary period is subdivided are very -difficult to distinguish from one another. The oldest of them is called -_eocene_, or old tertiary; the newer _miocene_, or mid tertiary; and the -last is the _pliocene_, or later tertiary system. - -The whole population of the tertiary epoch approaches much nearer, on -the whole as well as in detail, to that of the present time than is the -case in the preceding epochs. From this time the class of _Mammals_ -greatly predominates over all other vertebrate animals. In like manner, -in the vegetable kingdom, the group--so rich in forms--of the -_Angiosperms_, or _plants with covered seeds_, predominates, and its -_leafy forests_ constitute the characteristic feature of the tertiary -epoch. The group of the Angiosperms consists of the two classes of -single-seed-lobed plants, or _Monocotyledons_, and the double-seed-lobed -plants, or _Dicotyledons_. The Angiosperms of both classes had, it is -true, made their appearance in the Cretaceous period, and mammals had -already occurred in the Jurassic period, and even in the Triassic -period; but both groups, the mammals and the plants with enclosed seeds, -did not attain their peculiar development and supremacy until the -tertiary epoch, so that it may justly be called after them. - -The fifth and last main division of the organic history of the earth is -the _quaternary epoch, or era of Civilization_, which in comparison with -the length of the four other epochs almost vanishes into nothing, though -with a comical conceit we usually call its record the "history of the -world." As the period is characterized by the development of _Man_ and -his _Culture_, which has influenced the organic world more powerfully -and with greater transforming effect than have all previous conditions, -it may also be called the era of Man, the anthropolithic or anthropozoic -period. It might also be called the era of Cultivated Forests, or -Gardens, because even at the lowest stage of human civilization man's -influence is already perceptible in the utilization of forests and their -products, and therefore also in the physiognomy of the landscape. The -commencement of this era, which extends down to the present time, is -geologically bounded by the end of the pliocene stratification. - -The neptunic strata which have been deposited during the comparatively -short quaternary epoch are very different in different parts of the -earth, but they are mostly of very slight thickness. They are reduced to -two "systems," the older of which is designated the _diluvial_, or -_pleistocene_, and the later the _alluvial_, or _recent_. The diluvial -system is again divided into two "formations," the older _glacial_ and -the more recent _post glacial_ formations. For during the older diluvial -period there occurred that extremely remarkable decrease of the -temperature of the earth which led to an extensive glaciation of the -temperate zones. The great importance which this "ice" or "glacial -period" has exercised on the geographical and topographical distribution -of organisms has already been explained in the preceding chapter (vol. -i. p. 365). But the _post glacial period_, or the more recent diluvial -period, during which the temperature again increased and the ice -retreated towards the poles, was also highly important in regard to the -present state of chorological relations. - -The biological characteristic of the quaternary epoch lies essentially -in the development and dispersion of the human organism and his culture. -Man has acted with a greater transforming, destructive, and modifying -influence upon the animal and vegetable population of the earth than any -other organism. For this reason, and not because we assign to man a -privileged exceptional position in nature in other matters, we may with -full justice designate the development of man and his civilization as -the beginning of a special and last main division of the organic history -of the earth. It is probable indeed that the corporeal development of -primæval man out of man-like apes took place as far back as the earlier -pliocene period, perhaps even in the miocene tertiary period. But the -actual development of _human speech_, which we look upon as the most -powerful agency in the development of the peculiar characteristics of -man and his dominion over other organisms, probably belongs to that -period which on geological grounds is distinguished from the preceding -pliocene period as the pleistocene or diluvial. In fact the time which -has elapsed from the development of human speech down to the present -day, though it may comprise many thousands and perhaps hundreds of -thousands of years, almost vanishes into nothing as compared with the -immeasurable length of the periods which have passed from the beginning -of organic life on the earth down to the origin of the human race. - -The tabular view given on page 15 shows the succession of the -palæontological rock-groups, systems, and formations, that is, the -larger and smaller neptunic groups of strata, which contain -petrifactions, from the uppermost, or Alluvial, down to the lowest, or -Laurentian, deposits. The table on page 14 presents the historical -division of the corresponding eras of the larger and smaller -palæontological periods, and in a reversed succession, from the most -ancient Laurentian up to the most recent Quaternary period. - -Many attempts have been made to make an approximate calculation of the -number of thousands of years constituting these periods. The thickness -of the strata has been compared, which, according to experience, is -deposited during a century, and which amounts only to some few lines or -inches, with the whole thickness of the stratified masses of rock, the -succession of which we have just surveyed. This thickness, on the whole, -may on an average amount to about 130,000 feet; of these 70,000 belong -to the primordial, or archilithic; 42,000 to the primary, or -palæolithic; 15,000 to the secondary, or mesolithic; and finally only -3,000 to the tertiary, or cænolithic group. The very small and scarcely -appreciable thickness of the quaternary, or anthropolithic deposit -cannot here come into consideration at all. On an average, it may at -most be computed as from 500 to 700 feet. But it is self evident that -all these measurements have only an average and approximate value, and -are meant to give only a rough survey of the _relative_ proportion of -the systems of strata and of the spaces of time corresponding with them. - -Now, if we divide the whole period of the organic history of the -earth--that is, from the beginning of life on the earth down to the -present day--into a hundred equal parts, and if then, corresponding to -the thickness of the systems of strata, we calculate the relative -duration of the time of the five main divisions or periods according to -percentages, we obtain the following result:-- - - - I. Archilithic, or primordial period 53.6 - II. Palæolithic, or primary period 32.1 - III. Mesolithic, or secondary period 11.5 - IV. Cænolithic, or tertiary period 2.3 - V. Anthropolithic, or quaternary period 0.5 - ----- - Total 100.0 - - -According to this, the length of the archilithic period, during which no -land-living animals or plants as yet existed, amounts to more than one -half, more than 53 per cent.; on the other hand the length of the -anthropolithic era, during which man has existed, amounts to scarcely -one-half per cent. of the whole length of the organic history of the -earth. It is, however, quite impossible to calculate the length of these -periods, even approximately, by years. - -The thickness of the strata of mud at present deposited during a -century, and which has been used as a basis for this calculation, is of -course quite different in different parts of the earth under the -different conditions in which these deposits take place. It is very -slight at the bottom of the deep sea, in the beds of broad rivers with a -short course, and in inland seas which receive very scanty supplies of -water. It is comparatively great on the sea-shores exposed to strong -breakers, at the estuaries of large rivers with long courses, and in -inland seas with copious supplies of water. At the mouth of the -Mississippi, which carries with it a considerable amount of mud, in the -course of 100,000 years about 600 feet would be deposited. At the bottom -of the open sea, far away from the coasts, during this long period only -some few feet of mud would be deposited. Even on the sea-shores where a -comparatively large quantity of mud is deposited the thickness of the -strata formed during the course of a century may after all amount to no -more than a few inches or lines when condensed into solid stone. In any -case, however, all calculations based upon these comparisons are very -unsafe, and we cannot even approximately conceive the enormous length of -the periods which were requisite for the formation of the systems of -neptunic strata. Here we can apply only relative, not absolute, -measurements of time. - -Moreover, we should entirely err were we to consider the size of these -systems of strata alone as the measure of the actual space of time which -has elapsed during the earth's history. For the elevations and -depressions of the earth's crust have perpetually alternated with one -another, and the mineralogical and palæontological difference--which is -perceived between each two succeeding systems of strata, and between -each two of their formations at any particular spot--corresponds in all -probability with a considerable intermediate space of many thousands of -years, during which that particular part of the earth's crust was raised -above the water. It was only after the lapse of this intermediate -period, when a new depression again laid the part in question under -water, that there occurred a new deposit of earth. As, in the mean time, -the inorganic and organic conditions on this part had undergone a -considerable transformation, the newly-formed layer of mud was -necessarily composed of different earthy constituents and enclosed -different petrifactions. - - IV. Tertiary Group of | - Strata, 3,000 feet. | Eocene, Miocene, Pliocene. - ---------------------------------+------------------------------ - | IX. Chalk System. - III. Mesolithic Group of Strata. | - | - Deposits of the | VIII. Jura System. - Secondary Epoch, about | - 15,000 feet. | - | VII. Trias System. - ---------------------------------+------------------------------ - | - | VI. Permian System. - II. Palæolithic Group of Strata. | - | - Deposits of the | V. Coal System. - Primary Epoch, about | - 42,000 feet. | IV. Devonian System. - ---------------------------------+------------------------------ - | - | III. Silurian System, about - | 22,000 feet. - I. Archilithic Group of Strata. | - | - Deposits of the | II. Cambrian System, about - Primordial Epoch, about | 18,000 feet. - 70,000 feet. | - | I. Laurentian System, about - | 30,000 feet. - - -The striking differences which so frequently occur between the -petrifactions of two strata, lying one above another, are to be -explained in a simple and easy manner by the supposition that the same -part of the earth's surface has been exposed to _repeated depressions -and elevations_. Such alternating elevations and depressions take place -even now extensively, and are ascribed to the heaving of the fiery fluid -nucleus against the rigid crust. Thus, for example, the coast of Sweden -and a portion of the west coast of South America are constantly though -slowly rising, while the coast of Holland and a portion of the east -coast of South America are gradually sinking. The rising as well as the -sinking takes place very slowly, and in the course of a century -sometimes only amounts to some few lines, sometimes to a few inches, or -at most a few feet. But if this action continues uninterruptedly -throughout hundreds of thousands of years it is capable of forming the -highest mountains. - -It is evident that elevations and depressions, such as now can be -measured in these places, have uninterruptedly alternated one with -another in different places during the whole course of the organic -history of the earth. This may be inferred with certainty from the -geographical distribution of organisms. (Compare vol. i. p. 350.) But to -form a judgment of our palæontological records of creation it is -extremely important to show that permanent strata can only be deposited -during a slow sinking of the ground under water, but not during its -continued rising. When the ground slowly sinks more and more below the -level of the sea, the deposited layers of mud get into continually -deeper and quieter water, where they can become condensed into stone -undisturbed. But when, on the other hand, the ground slowly rises, the -newly-deposited layers of mud, which enclose the remains of plants and -animals, again immediately come within the reach of the play of the -waves, and are soon worn away by the force of the breakers, together -with the organic remains which they on close. For this simple but very -important reason, therefore, abundant layers, in which organic remains -are preserved, can only be deposited during a continuous sinking of the -ground. When any two different formations or strata, lying one above the -other, correspond with two different periods of depression, we must -assume a long period of rising between them, of which period we know -nothing, because no fossil remains of the then living animals and plants -could be preserved. It is evident, however, that those _periods of -elevation_, which have passed without leaving any trace behind them, -deserve a no less careful consideration than the greater or less -alternating _periods of depression_, of whose organic population we can -form an approximate idea from the strata containing petrifactions. -Probably the former were not of shorter duration than the latter. - -From this alone it is apparent how imperfect our records must -necessarily be, and all the more so since it can be theoretically proved -that the variety of animal and vegetable life must have increased -greatly during those very periods of elevation. For as new tracts of -land are raised above the water, new islands are formed. Every new -island, however, is a new centre of creation, because the animals and -plants accidentally cast ashore there, find in the new territory, in -the struggle for life, abundant opportunity of developing themselves -peculiarly, and of forming new species. The formation of new species has -evidently taken place pre-eminently during these intermediate periods, -of which, unfortunately, no petrifactions could be preserved, whereas, -on the contrary, during the slow sinking of the ground there was more -chance of numerous species dying out, and of a retrogression into fewer -specific forms. The intermediate forms between the old and the -newly-forming species must also have lived during the periods of -elevation, and consequently could likewise leave no fossil remains. - -In addition to the great and deplorable gaps in the palæontological -records of creation--which are caused by the periods of elevation--there -are, unfortunately, many other circumstances which immensely diminish -their value. I must mention here especially the _metamorphic state of -the most ancient formations_, of those strata which contain the remains -of the most ancient flora and fauna, the original forms of all -subsequent organisms, and which, therefore, would be of especial -interest. It is just these rocks--and, indeed, the greater part of the -primordial, or archilithic strata, almost the whole of the Laurentian, -and a large part of the Cambrian systems--which no longer contain any -recognizable remains, and for the simple reason that these strata have -been subsequently changed or metamorphosed by the influence of the fiery -fluid interior of the earth. These deepest neptunic strata of the crust -have been completely changed from their original condition by the heat -of the glowing nucleus of the earth, and have assumed a crystalline -state. In this process, however, the form of the organic remains -enclosed in them has been entirely destroyed. It has been preserved only -here and there by a happy chance, as in the case of the most ancient -petrifactions known, the _Eozoon canadense_, from the lowest Laurentian -strata. However, from the layers of crystalline charcoal (graphite) and -crystalline limestone (marble), which are found deposited in the -metamorphic rocks, we may with certainty conclude that petrified animal -and vegetable remains existed in them in earlier times. - -Our record of creation is also extremely imperfect from the circumstance -that only a small portion of the earth's surface has been accurately -investigated by geologists, namely, England, Germany, and France. But we -know very little of the other parts of Europe, of Russia, Spain, Italy, -and Turkey. In the whole of Europe, only some few parts of the earth's -crust have been laid open, by far the largest portion of it is unknown -to us. The same applies to North America and to the East Indies. There -some few tracts have been investigated; but of the larger portion of -Asia, the most extensive of all continents, we know almost nothing; of -Africa nothing, excepting the Cape of Good Hope and the shores of the -Mediterranean; of Australia almost nothing; and of South America but -very little. It is clear, therefore, that only quite a small portion, -perhaps scarcely the thousandth part of the whole surface of the earth, -has been palæontologically investigated. We may therefore reasonably -hope, when more extensive geological investigations are made, which are -greatly assisted by the constructions of railroads and mines, to find a -great number of other important petrifactions. A hint that this will be -the case is given by the remarkable petrifactions found in those parts -of Africa and Asia which have been minutely investigated,--the Cape -districts and the Himalaya mountains. A series of entirely new and very -peculiar animal forms have become known to us from the rocks of these -localities. But we must bear in mind that the vast bottom of the -existing oceans is at the present time quite inaccessible to -palæontological investigations, and that the greater part of the -petrifactions which have lain there from primæval times will either -never be known to us, or at best only after the course of many thousands -of years, when the present bottom of the ocean shall have become -accessible by gradual elevation. If we call to mind the fact that -three-fifths of the whole surface of the earth consists of water, and -only two-fifths of land, it becomes plain that on this account the -palæontological record must always present an immense gap. - -But, in addition to these, there exists another series of difficulties -in the way of palæontology which arises from the nature of the organisms -themselves. In the first place, as a rule only the hard and solid parts -of organisms can fall to the bottom of the sea or of fresh waters, and -be there enclosed in the mud and petrified. Hence it is only the bones -and teeth of vertebrate animals, the calcareous shells of molluscs, the -chitinous skeletons of articulated animals, the calcareous skeletons of -star-fishes and corals, and the woody and solid parts of plants, that -are capable of being petrified. But soft and delicate parts, which -constitute by far the greater portion of the bodies of most organisms, -are very rarely deposited in the mud under circumstances favourable to -their becoming petrified, or distinctly impressing their external form -upon the hardening mud. Now, it must be borne in mind that large classes -of organisms, as for example the Medusæ, the naked molluscs without -shells, a large portion of the articulated animals, almost all worms, -and even the lowest vertebrate animals, possess no firm and hard parts -capable of being petrified. In like manner the most important parts of -plants, such as the flowers, are for the most part so soft and tender -that they cannot be preserved in a recognizable form. We therefore -cannot expect to find any petrified remains of these important -organisms. Moreover, all organisms at an early stage of life are so soft -and tender that they are quite incapable of being petrified. -Consequently all the petrifactions found in the neptunic stratifications -of the earth's crust comprise altogether but a very few forms, and of -these for the most part only isolated fragments. - -We must next bear in mind that the dead bodies of the inhabitants of the -sea are much more likely to be preserved and petrified in the deposits -of mud than those of the inhabitants of fresh water and of the land. -Organisms living on land can, as a rule, become petrified only when -their corpses fall accidentally into the water and are buried at the -bottom in the hardening layers of mud. But this event depends upon very -many conditions. We cannot therefore be astonished that by far the -majority of petrifactions belong to organisms which have lived in the -sea, and that of the inhabitants of the land proportionately only very -few are preserved in a fossil state. How many contingencies come into -play here we may infer from the single fact that of many fossil mammals, -in fact of all the mammals of the secondary, or mesozoic epoch, nothing -is known except the lower jawbone. This bone is in the first place -comparatively solid, and in the second place very easily separates -itself from the dead body, which floats on the water. Whilst the body is -driven away and dissolved by the water, the lower jawbone falls down to -the bottom of the water and is there enclosed in the mud. This explains -the remarkable fact that in a stratum of limestone of the Jurassic -system near Oxford, in the slates of Stonesfield, as yet only the lower -jawbones of numerous pouched animals (Marsupials) have been found. They -are the most ancient mammals known, and of the whole of the rest of -their bodies not a single bone exists. The opponents of the theory of -development, according to their usual logic, would from this fact be -obliged to draw the conclusion that the lower jawbone was the only bone -in the body of those animals. - -Footprints are very instructive when we attempt to estimate the many -accidents which so arbitrarily influence our knowledge of fossils; they -are found in great numbers in different extensive layers of sandstone; -for example, in the red sandstone of Connecticut, in North America. -These footprints were evidently made by vertebrate animals, probably by -reptiles, of whose bodies not the slightest trace has been preserved.[1] -The impressions which their feet have left on the mud alone betray the -former existence of these otherwise unknown animals. - -The accidents which, besides these, determine the limits of our -palæontological knowledge, may be inferred from the fact that we know of -only one or two specimens of very many important petrifactions. It is -not ten years since we became acquainted with the imperfect impression -of a bird in the Jurassic or Oolitic system, the knowledge of which -has been of the very greatest importance for the phylogeny of the whole -class of birds. All birds previously known presented a very uniformly -organized group, and showed no striking transitional forms to other -vertebrate classes, not even to the nearly related reptiles. But that -fossil bird from the Jura possessed not an ordinary bird's tail, but a -lizard's tail, and thus confirmed what had been conjectured upon other -grounds, namely, the derivation of birds from lizards. This single -fossil has thus essentially extended not only our knowledge of the age -of the class of birds, but also of their blood relationship to reptiles. -In like manner our knowledge of other animal groups has been often -essentially modified by the accidental discovery of a single fossil. The -palæontological records must necessarily be exceedingly imperfect, -because we know of so very few examples, or only mere fragments of very -many important fossils. - -Another and very sensible gap in these records is caused by the -circumstance that the _intermediate forms_ which connect the different -species have, as a rule, not been preserved, and for the simple reason -that (according to the principle of divergence of character) they were -less favoured in the struggle for life than the most divergent -varieties, which had developed out of one and the same original form. -The intermediate links have, on the whole, always died out _rapidly_, -and have but rarely been preserved as fossils. On the other hand, the -most divergent forms were able to maintain themselves in life for a -longer period as independent species, to propagate more numerously, and -consequently to be more readily petrified. But this does not exclude the -fact that in _some_ cases the connecting intermediate forms of the -species have been preserved so perfectly petrified, that even now they -cause the greatest perplexity and occasion endless disputes among -systematic palæontologists about the arbitrary limits of species. - -An excellent example of this is furnished by the celebrated and very -variable fresh-water snail from the Stuben Valley, near Steinheim, in -Würtemburg, which has been described sometimes as _Paludina_, sometimes -as _Valvata_, and sometimes as _Planorbis multiformis_. The snow-white -shells of these small snails constitute more than half of the mass of -the tertiary limestone hills, and in this one locality show such an -astonishing variety of forms, that the most divergent extremes might be -referred to at least twenty entirely different species. But all these -extreme forms are united by such innumerable intermediate forms, and -they lie so regularly above and beside one another, that Hilgendorf was -able, in the clearest manner, to unravel the pedigree of the whole group -of forms. In like manner, among very many other fossil species (for -example, many ammonites, terebratulæ, sea urchins, lily encrinites, -etc.) there are such masses of connecting intermediate forms, that they -reduce the "dealers in fossil species" to despair. - -When we weigh all the circumstances here mentioned, the number of which -might easily be increased, it does not appear astonishing that the -natural accounts or records of creation formed by petrifactions are -extremely defective and incomplete. But nevertheless, the petrifactions -actually discovered are of the greatest value. Their significance is of -no less importance to the natural history of creation than the -celebrated inscription on the Rosetta stone, and the decree of Canopus, -are to the history of nations--to archæology and philology. Just as it -has become possible by means of these two most ancient inscriptions to -reconstruct the history of ancient Egypt, and to decipher all -hieroglyphic writings, so in many cases a few bones of an animal, or -imperfect impressions of a lower animal or vegetable form, are -sufficient for us to gain the most important starting-points in the -history of the whole group, and in the search after their pedigree. A -couple of small back teeth, which have been found in the Keuper -formation of the Trias, have of themselves alone furnished a sure proof -that mammals existed even in the Triassic period. - -Of the incompleteness of the geological accounts of creation, Darwin, -agreeing with Lyell, the greatest of all recent geologists, says:-- - -"I look at the geological record as a history of the world imperfectly -kept, and written in a changing dialect; of this history we possess the -last volume alone, relating only to two or three countries. Of this -volume, only here and there a short chapter has been preserved; and of -each page, only here and there a few lines. Each word of the -slowly-changing language, more or less different in the successive -chapters, may represent the forms of life which are entombed in our -consecutive formations, and which falsely appear to us to have been -abruptly introduced. On this view, the difficulties above discussed are -greatly diminished, or even disappear."--_Origin of Species_, 6th -Edition, p. 289. - -If we bear in mind the exceeding incompleteness of palæontological -records, we shall not be surprised that we are still dependent upon so -many uncertain hypotheses when actually endeavouring to sketch the -pedigree of the different organic groups. However, we fortunately -possess, besides fossils, other records of the history of the origin of -organisms, which in many cases are of no less value, nay, in several -cases are of much greater value, than fossils. By far the most important -of these other records of creation is, without doubt, _ontogeny_, that -is, the history of the development of the organic individual (embryology -and metamorphology). It briefly repeats in great and marked features the -series of forms which the ancestors of the respective individuals have -passed through from the beginning of their tribe. We have designated the -palæontological history of the development of the ancestors of a living -form as the history of a tribe, or _phylogeny_, and we may therefore -thus enunciate this exceedingly important _biogenetic fundamental -principle_: "_Ontogeny is a short and quick repetition, or -recapitulation, of Phylogeny, determined by the laws of Inheritance and -Adaptation_." As every animal and every plant from the beginning of its -individual existence passes through a series of different forms, it -indicates in rapid succession and in general outlines the long and -slowly changing series of states of form which its progenitors have -passed through from the most ancient times. (Gen. Morph. ii. 6, 110, -300.) - -It is true that the sketch which the ontogeny of organisms gives us of -their phylogeny is in most cases more or less obscured, and all the more -so the more Adaptation, in the course of time, has predominated over -Inheritance, and the more powerfully the law of abbreviated inheritance, -and the law of correlative adaptation, have exerted their influence. -However, this does not lessen the great value which the actual and -faithfully preserved features of that sketch possess. _Ontogeny is of -the most inestimable value for the knowledge of the earliest -palæontological conditions of development_, just because no petrified -remains of the most ancient conditions of the development of tribes and -classes have been preserved. These, indeed, could not have been -preserved on account of the soft and tender nature of their bodies. No -petrifactions could inform us of the fundamental and important fact -which ontogeny reveals to us, that the most ancient common ancestors of -all the different animal and vegetable species were quite simple cells -like the egg-cell. No petrifaction could prove to us the immensely -important fact, established by ontogeny, that the simple increase, the -formation of cell-aggregates and the differentiation of those cells, -produced the infinitely manifold forms of multicellular organisms. Thus -ontogeny helps us over many and large gaps in palæontology. - -[Illustration: Hand of Nine different Mammals. Pl. IV. - -_1. Man_, _2. Gorilla_, _3. Orang_, _4. Dog_, _5. Seal_, _6. Porpoise_, -_7. Bat_, _8. Mole_, _9. Duck-bill_.] - -To the invaluable records of creation furnished by palæontology and -ontogeny are added the no less important evidences for the blood -relationship of organisms furnished by _comparative anatomy_. When -organisms, externally very different, nearly agree in their internal -structure, one may with certainty conclude that the agreement has its -foundation in Inheritance, the dissimilarity its foundation in -Adaptation. Compare, for example, the hands and fore paws of the nine -different animals which are represented on Plate IV., in which the bony -skeleton in the interior of the hand and of the five fingers is visible. -Everywhere we find, though the external forms are most different, the -same bones, and among them the same number, position, and connection. It -will perhaps appear very natural that the hand of _man_ (Fig. 1) differs -very little from that of the _gorilla_ (Fig. 2) and of the -_orang-outang_ (Fig. 3), his nearest relations. But it will be more -surprising if the fore feet of the _dog_ also (Fig. 4), as well as the -breast-fin (the hand) of the _seal_ (Fig. 5), and of the _dolphin_ (Fig. -6), show essentially the same structure. And it will appear still more -wonderful that even the wing of the _bat_ (Fig. 7), the shovel-feet of -the _mole_ (Fig. 8), and the fore feet of the _duck-bill_ -(Ornithorhynchus) (Fig. 9), the most imperfect of all mammals, is -composed of entirely the same bones, only their size and form being -variously changed. Their number, the manner of their arrangement and -connection has remained the same. (Compare also the explanation of Plate -IV., in the Appendix.) It is quite inconceivable that any other cause, -except the common inheritance of the part in question from common -ancestors, could have occasioned this wonderful homology or similarity -in the essential inner structure with such different external forms. -Now, if we go down further in the system below the mammals, and find -that even the wings of birds, the fore feet of reptiles and amphibious -animals, are composed of essentially the same bones as the arms of man -and the fore legs of the other mammals, we can, from this circumstance -alone, with perfect certainty, infer the common origin of all these -vertebrate animals. Here, as in all other cases, the degree of the -internal agreement in the form discloses to us the degree of blood -relationship. - - - - -CHAPTER XVI. - -PEDIGREE AND HISTORY OF THE KINGDOM OF THE PROTISTA. - - - Special Mode of Carrying out the Theory of Descent in the - Natural System of Organisms.--Construction of Pedigrees.--Descent - of all Many-Celled from Single-Celled Organisms.--Descent of - Cells from Monera.--Meaning of Organic Tribes, or Phyla.--Number - of the Tribes in the Animal and Vegetable Kingdoms.--The - Monophyletic Hypothesis of Descent, or the Hypothesis of one - Common Progenitor, and the Polyphyletic Hypothesis of Descent, - or the Hypothesis of Many Progenitors.--The Kingdom of Protista, - or Primæval Beings.--Eight Classes of the Protista - Kingdom.--Monera, Amoebæ, or Protoplastæ.--Whip-swimmers, or - Flagellata.--Ciliated-balls, or Catallacta.--Labyrinth-streamers, - or Labyrinthuleæ.--Flint-cells, or Diatomeæ.--Mucous-moulds, or - Myxomycetes.--Root-footers (Rhizopoda).--Remarks on the General - Natural History of the Protista: Their Vital Phenomena, - Chemical Composition, and Formation (Individuality and - Fundamental Form).--Phylogeny of the Protista Kingdom - - -By a careful comparison of the individual and the palæontological -development, as also by the comparative anatomy of organisms, by the -comparative examination of their fully developed structural -characteristics, we arrive at the knowledge of the degrees of their -different structural relationships. By this, however, we at the same -time obtain an insight into their true _blood relationship_, which, -according to the Theory of Descent, is the real reason of the structural -relationship. Hence by collecting, comparing, and employing the -empirical results of embryology, palæontology, and anatomy for -supplementing each other, we arrive at an approximate knowledge of "the -Natural System," which, according to our views, is the _pedigree_ of -organisms. It is true that our human knowledge, in all things -fragmentary, is especially so in this case, on account of the extreme -incompleteness and defectiveness of the records of creation. However, we -must not allow this to discourage us, or to deter us from undertaking -this highest problem of biology. Let us rather see how far it may even -now be possible, in spite of the imperfect state of our embryological, -palæontological, and anatomical knowledge, to establish a probable -scheme of the genealogical relationships of organisms. - -Darwin in his book gives us no answer to these special questions of the -Theory of Descent; at the conclusion he only expresses his conjecture -"that animals have descended from at most only four or five progenitors, -and plants from an equal or less number." But as these few aboriginal -forms still show traces of relationship, and as the animal and vegetable -kingdoms are connected by intermediate transitional forms, he arrives -afterwards at the opinion "that probably all the organic beings which -have ever lived on the earth have descended from some one primordial -form, into which life was first breathed by the Creator." Like Darwin, -all other adherents of the Theory of Descent have only treated it in a -general way, and not made the attempt to carry it out specially, and to -treat the "Natural System" actually as the pedigree of organisms. If, -therefore, we venture upon this difficult undertaking, we must take up -independent ground. - -Four years ago I set up a number of hypothetical genealogies for the -larger groups of organisms in the systematic introduction to my General -History of Development (Gen. Morph. vol. ii.), and thereby, in fact, -made the first attempt actually to construct the pedigrees of organisms -in the manner required by the theory of development. I was quite -conscious of the extreme difficulty of the task, and as I undertook it -in spite of all discouraging obstacles, I claim no more than the merit -of having made the first attempt and given a stimulus for other and -better attempts. Probably most zoologists and botanists were but little -satisfied with this beginning, and least so in reference to the special -domain in which each one is specially at work. However, it is certainly -in this case much easier to blame than to produce something better, and -what best proves the immense difficulty of this infinitely complicated -task is the fact that no naturalist has as yet supplied the place of my -pedigrees by better ones. But, like all other scientific hypotheses -which serve to explain facts, my genealogical hypotheses may claim to be -taken into consideration until they are replaced by better ones. - -I hope that this replacement will very soon take place; and I wish for -nothing more than that my first attempt may induce very many naturalists -to establish more accurate pedigrees for the individual groups, at least -in the special domain of the animal and vegetable kingdom which happens -to be well known to one or other of them. By numerous attempts of this -kind our genealogical knowledge, in the course of time, will slowly -advance and approach more towards perfection, although it can with -certainty be foreseen that we shall never arrive at a complete -pedigree. We lack, and shall ever lack, the indispensable -palæontological foundations. The most ancient records will ever remain -sealed to us, for reasons which have been previously mentioned. The most -ancient organisms which arose by spontaneous generation--the original -parents of all subsequent organisms--must necessarily be supposed to -have been Monera--simple, soft, albuminous lumps, without structure, -without any definite forms, and entirely without any hard and formed -parts. They and their next offspring were consequently not in any way -capable of being preserved in a petrified condition. But we also lack, -for reasons discussed in detail in the preceding chapter, by far the -greater portion of the innumerable palæontological documents, which are -really requisite for a safe reconstruction of the history of animal -tribes, or phylogeny, and for the true knowledge of the pedigree of -organisms. If we, therefore, in spite of this, venture to undertake -their hypothetical construction, we must chiefly depend for guidance on -the two other series of records which most essentially supplement the -palæontological archives. These are ontogeny and comparative anatomy. - -If thoughtfully and carefully we consult these most valuable records, we -at once perceive what is exceedingly significant, namely, that by far -the greater number of organisms, especially all higher animals and -plants, are composed of a great number of cells, and that they originate -out of an egg, and that this egg, in animals as well as in plants, is a -single, perfectly simple cell--a little lump of albuminous constitution, -in which another albuminous corpuscle, the cell-kernel, is enclosed. -This cell containing its kernel grows and becomes enlarged. By division -it forms an accumulation of cells, and out of these, by division of -labour (as has previously been described), there arise the numberless -different forms which are presented to us in the fully developed animal -and vegetable species. This immensely important process--which we may -follow step by step, with our own eyes, any day in the embryological -development of any animal or vegetable individual, and which as a rule -is by no means considered with the reverence it deserves--informs us -more surely and completely than all petrifactions could do as to the -original palæontological development of all many-celled organisms, that -is, of all higher animals and plants. For as ontogeny, or the -embryological development of every single individual, is essentially -only a recapitulation of phylogeny, or the palæontological development -of its chain of ancestors, we may at once, with full assurance, draw the -simple and important conclusion, that _all many-celled animals and -plants were originally derived from single-celled organisms_. The -primæval ancestors of man, as well as of all other animals, and of all -plants composed of many cells, were simple cells living isolated. This -invaluable secret of the organic pedigree is revealed to us with -infallible certainty by the egg of animals, and by the true egg-cell of -plants. When the opponents of the Theory of Descent assert it to be -miraculous and inconceivable that an exceedingly complicated many-celled -organism could, in the course of time, have proceeded from a simple -single-celled organism, we at once reply that we may see this incredible -miracle at any moment, and follow it with our own eyes. For the -embryology of animals and plants visibly presents to our eyes in the -shortest space of time the same process as that which has taken place in -the origin of the whole tribe during the course of enormous periods of -time. - -Upon the ground of embryological records, therefore, we can with full -assurance maintain that all many-celled, as well as single-celled, -organisms are originally descended from simple cells; connected with -this, of course, is the conclusion that the most ancient root of the -animal and vegetable kingdom was common to both. For the different -primæval "original cells" out of which the few different main groups or -tribes have developed, only acquired their differences after a time, and -were descended from a common "primæval cell." But where did those few -"original cells," or the one primæval cell, come from? For the answer to -this fundamental genealogical question we must return to the theory of -plastids and the hypothesis of spontaneous generation which we have -already discussed (vol. i. p. 327). - -As was then shown, we cannot imagine _cells_ to have arisen by -spontaneous generation, but only _Monera_, those primæval creatures of -the simplest kind conceivable, like the still living Protamoebæ, -Protomyxæ, etc. (vol. i. p. 186, Fig. 1). Only such corpuscules of mucus -without component parts--whose whole albuminous body is as homogeneous -in itself as an inorganic crystal, but which nevertheless fulfills the -two organic fundamental functions of nutrition and propagation--could -have directly arisen out of inorganic matter by autogeny at the -beginning (we may suppose) of the Laurentian period. While some Monera -remained at the original simple stage of formation, others gradually -developed into cells by the inner kernel of the albuminous mass becoming -separated from the external cell-substance. In others, by -differentiation of the outermost layer of the cell-substance, an -external covering (membrane, or skin) was formed round simple cytods -(without kernel), as well as round naked cells (containing a kernel). By -these two processes of separation in the simple primæval mucus of the -Moneron body, by the formation of a kernel in the interior and a -covering on the outer surface of the mass of plasma, there arose out of -the original most simple cytods, or Monera, those four different species -of plastids, or individuals, of the first order, from which, by -differentiation and combination, all other organisms could afterwards -develop themselves. (Compare vol. i. p. 347.) - -The question now forces itself upon us, Are all organic cytods and -cells, and consequently also those "original cells" which we previously -considered to be the primary parents of the few great main groups of the -animal and vegetable kingdoms, descended from a single original form of -Moneron, or were there several different organic primary forms, each -traceable to a peculiar independent species of Moneron which originated -by spontaneous generation? In other words, _Is the whole organic world -of a common origin, or does it owe its origin to several acts of -spontaneous generation?_ This fundamental question of genealogy seems at -first sight to be of exceeding importance. But on a more accurate -examination, we shall soon see that this is not the case, and that it is -in reality a matter of very subordinate importance. - -Let us now pass on to examine and clearly limit our conception of an -_organic tribe_. By _tribe_, or _phylum_, we understand all those -organisms of whose blood relationship and descent from a common primary -form there can be no doubt, or whose relationship, at least, is most -probable from anatomical reasons, as well as from reasons founded on -historical development. Our tribes, or phyla, according to this idea, -essentially coincide with those few "great classes," or "main classes," -of which Darwin also thinks that each contains only organisms related by -blood, and of which, both in the animal and in the vegetable kingdoms, -he only assumes either four or five. In the animal kingdom these tribes -would essentially coincide with those four, five, or six main divisions -which zoologists, since Bär and Cuvier, have distinguished as "main -forms, general plans, branches, or sub-kingdoms" of the animal kingdom. -(Compare vol. i. p. 53.) Bär and Cuvier distinguished only four of them, -namely:--1. The vertebrate animals (Vertebrata); 2. The articulated -animals (Articulata); 3. The molluscous animals (Mollusca); and 4. The -radiated animals (Radiata). At present six are generally distinguished, -since the tribe of the articulated animals is divided into two tribes, -those possessing articulated feet (Arthropoda), and the worms (Vermes); -and in like manner the tribe of radiated animals is subdivided into the -two tribes of the star animals (Echinodermata) and the animal-plants -(Zoophyta). Within each of these six tribes, all the included animals, -in spite of great variety in external form and inner structure, -nevertheless possess such numerous and important characteristics in -common, that there can be no doubt of their blood relationship. The same -applies also to the six great main classes which modern botany -distinguishes in the vegetable kingdom, namely:--1. Flowering plants -(Phanerogamia); 2. Ferns (Filicinæ); 3. Mosses (Muscinæ); 4. Lichens -(Lichenes); 5. Fungi (Fungi); and 6. Water-weeds (Algæ). The last three -groups, again, show such close relations to one another, that by the -name of "Thallus plants" they may be contrasted with the three first -main classes, and consequently the number of phyla, or main groups, of -the vegetable kingdom may be reduced to the number of four. Mosses and -ferns may likewise be comprised as "Prothallus plants" (Prothallophyta), -and thereby the number of plant tribes reduced to three--Flowering -plants, Prothallus plants, and Thallus plants. - -Very important facts in the anatomy and the history of development, both -in the animal and vegetable kingdoms, support the supposition that even -these few main classes or tribes are connected at their roots, that is, -that the lowest and most ancient primary forms of all three are related -by blood to one another. Nay, by a further examination we are obliged to -go still a step further, and to agree with Darwin's supposition, that -even the two pedigrees of the animal and vegetable kingdom are connected -at their lowest roots, and that the lowest and most ancient animals and -plants are derived from a single common primary creature. According to -our view, this common primæval organism can have been nothing but a -Moneron which took its origin by spontaneous generation. - -In the mean time we shall at all events be acting cautiously if we avoid -this last step, and assume true blood relationship only within each -tribe, or phylum, where it has been undeniably and surely established by -facts in comparative anatomy, ontogeny, and phylogeny. But we may here -point to the fact that two different fundamental forms of genealogical -hypothesis are possible, and that all the different investigations of -the Theory of Descent in relation to the origin of organic groups of -forms will, in future, tend more and more in one or the other of these -directions. The unitary, or _monophyletic_, hypothesis of descent will -endeavour to trace the first origin of all individual groups of -organisms, as well as their totality, to a single common species of -Moneron which originated by spontaneous generation (vol. i. p. 343). The -multiple, or _polyphyletic_, hypothesis of descent, on the other hand, -will assume that several different species of Monera have arisen by -spontaneous generation, and that these gave rise to several different -main classes (tribes, or phyla) (vol. i. p. 348). The apparently great -contrast between these two hypotheses is in reality of very little -importance. For both the monophyletic and the polyphyletic hypothesis of -descent must necessarily go back to the Monera as the most ancient root -of the one or of the many organic tribes. But as the whole body of a -Moneron consists only of a simple, formless mass, without component -particles, made up of a single albuminous combination of carbon, it -follows that the differences of the different Monera can only be of a -chemical nature, and can only consist in a different atomic composition -of that mucous albuminous combination. But these subtle and complicated -differences of mixture of the infinitely manifold combinations of -albumen are not appreciable by the rude and imperfect means of human -observation and are, consequently, at present of no further interest to -the task we have in hand. - -The question of the monophyletic or polyphyletic origin will constantly -recur within each individual tribe, where the origin of a smaller or of -a larger group is discussed. In the vegetable kingdom, for example, some -botanists will be inclined to derive all flowering plants from a single -form of fern, while others will prefer the idea that several different -groups of Phanerogama have sprung from several different groups of -ferns. In like manner, in the animal kingdom, some zoologists will be -more in favour of the supposition that all placental animals are derived -from a single pouched animal; others will be more in favour of the -opposite supposition, that several different groups of placental animals -have proceeded from several different pouched animals. In regard to the -human race itself, some will prefer to derive it from a single form of -ape, while others will be more inclined to the idea that several -different races of men have arisen, independently of one another, out of -several different species of ape. Without here expressing our opinion in -favour of either the one or the other conception, we must, nevertheless, -remark that in general _the monophyletic hypothesis of descent deserves -to be preferred to the polyphyletic hypothesis of descent_. In -accordance with the chorological proposition of a single "centre of -creation" or of a single primæval home for most species (which has -already been discussed), we may be permitted to assume that the original -form of every larger or smaller natural group only originated _once_ in -the course of time, and only in _one part_ of the earth. We may safely -assume this simple original root, that is, the monophyletic origin, in -the case of all the more highly developed groups of the animal and -vegetable kingdoms. (Compare vol. i. p. 353.) But it is very possible -that the more complete Theory of Descent of the future will involve the -polyphyletic origin of very many of the low and imperfect groups of the -two organic kingdoms. - -For these reasons I consider it best, in the mean time, to adopt the -_monophyletic hypothesis of descent_ both for the animal and for the -vegetable kingdom. Accordingly, the above-mentioned six tribes, or -phyla, of the animal kingdom must be connected at their lowest root, -and likewise the three or six main classes, or phyla, of the vegetable -kingdom must be traced to a common and most ancient original form. How -the connection of these tribes is to be conceived I shall explain in the -succeeding chapters. But before proceeding to this, we must occupy -ourselves with a very remarkable group of organisms, which cannot -without artificial constraint be assigned either to the pedigree of the -vegetable or to that of the animal kingdom. These interesting and -important organisms are the _primary creatures_, or _Protista_. - -All organisms which we comprise under the name of Protista show in their -external form, in their inner structure, and in all their vital -phenomena, such a remarkable mixture of animal and vegetable properties, -that they cannot with perfect justice be assigned either to the animal -or to the vegetable kingdom; and for more than twenty years an endless -and fruitless dispute has been carried on as to whether they are to be -assigned to this or that kingdom. Most of Protista are so small that -they can scarcely, if at all, be perceived with the naked eye. Hence the -majority of them have only become known during the last fifty years, -since by the help of the improved and general use of the microscope -these minute organisms have been more frequently observed and more -accurately examined. However, no sooner were they better known than -endless disputes arose about their real nature and their position in the -natural system of organisms. Many of these doubtful primary creatures -botanists defined as animals, and zoologists as plants; neither of the -two would own them. Others, again, were declared by botanists to be -plants, and by zoologists to be animals; each claimed them. These -contradictions are not altogether caused by our imperfect knowledge of -the Protista, but in reality by their true nature. Indeed, most Protista -present such a confused mixture of several animal and vegetable -characteristics, that each investigator may arbitrarily assign them -either to the animal or vegetable kingdom. Accordingly as he defines -these two kingdoms, and as he looks upon this or that characteristic as -determining the animal or vegetable nature, he will assign the -individual classes of Protista in one case to the animal and in another -to the vegetable kingdom. But this systematic difficulty has become an -inextricable knot by the fact that all more recent investigations on the -lowest organisms have completely effaced, or at least destroyed, the -sharp boundary between the animal and vegetable kingdom which had -hitherto existed, and to such a degree that its restoration is possible -only by means of a completely artificial definition of the two kingdoms. -But this definition could not be made so as to apply to many of the -Protista. - -For this and other reasons it is, in the mean time, best to exclude the -doubtful beings from the animal as well as from the vegetable kingdom, -and to comprise them in a third organic kingdom standing midway between -the two others. This intermediate kingdom I have established as the -_Kingdom of the Primary Creatures_ (Protista), when discussing general -anatomy in the first volume of my General Morphology, pp. 191-238. In my -Monograph of the Monera,(15) I have recently treated of this kingdom, -having somewhat changed its limits, and given it a more accurate -definition. Of independent classes of the kingdom Protista, we may at -present distinguish the following:-- - -1. The still living Monera; 2. The Amoeboidea, or Protoplasts; 3. The -Whip-swimmers, or Flagellata; 4. The Flimmer-balls, or Catallacta; 5. -The Tram-weavers, or Labyrinthuleæ; 6. The Flint-cells, or Diatomeæ; 7. -The Slime-moulds, or Myxomycetes; 8. The Ray-streamers, or Rhizopoda. - -The most important groups at present distinguishable in these eight -classes of Protista are named in the systematic table on p. 51. Probably -the number of these Protista will be considerably increased in future -days by the progressive investigations of the ontogeny of the simplest -forms of life, which have only lately been carried on with any great -zeal. With most of the classes named we have become intimately -acquainted only during the last ten years. The exceedingly interesting -Monera and Labyrinthuleæ, as also the Catallacta, were indeed discovered -only a few years ago. It is probable also that very numerous groups of -Protista have died out in earlier periods, without having left any -fossil remains, owing to the very soft nature of their bodies. We might -add to the Protista from the still living lowest groups of -organisms--the Fungi; and in so doing should make a very large addition -to its domain. Provisionally we shall leave them among plants, though -many naturalists have separated them altogether from the vegetable -kingdom. - -_The pedigree of the kingdom Protista_ is still enveloped in the -greatest obscurity. The peculiar combination of animal and vegetable -properties, the indifferent and uncertain character of their relations -of forms and vital phenomena, together with a number of several very -peculiar features which separate most of the subordinate classes sharply -from the others, at present baffle every attempt distinctly to make out -their blood relationships with one another, or with the lowest animals -on the one hand, and with the lowest plants on the other hand. It is not -improbable that the classes specified, and many other unknown classes of -Protista, represent quite independent organic tribes, or phyla, each of -which has independently developed from one, perhaps from various, Monera -which have arisen by spontaneous generation. If we do not agree to this -polyphyletic hypothesis of descent, and prefer the monophyletic -hypothesis of the blood relationship of all organisms, we shall have to -Look upon the different classes of protista as the lower small -off-shoots of the root, springing from the same simple monera root, out -of which arose the two mighty and many-branched pedigrees of the animal -kingdom on the one hand, and of the vegetable kingdom on the other. -(compare pp. 74, 75.) before i enter into this difficult question more -accurately, it will be appropriate to premise something further as to -the contents of the classes of protista given on the next page, and -their general natural history. - - -SYSTEMATIC SURVEY - -_Of the Larger and Smaller Groups of the Kingdom Protista._ - - ----------------+--------------------+------------------+----------------- - _Classes of | _Systematic Name | _Orders of | _A name of a - the Protista | of the Classes_. | Families of the | Genus - Kingdom._ | | Classes._ | as an example._ - ----------------+--------------------+------------------+----------------- - { 1. Gymnomonera Protogenes - 1. MONERS Monera { 2. Lepomonera Protomyxa - - { 1. Gymnamoebæ Amoeba - 2. PROTOPLASTS Amoeboida { 2. Leptamoebæ Arcella - { 3. Gregarinæ Monocystis - - { 1. Nudiflagellata Euglena - 3. WHIP-SWIMMERS Flagellata { 2. Cilioflagellata Peridinium - - 4. FLIMMER-BALLS Catallacta 1. Catallacta Magosphæra - - 5. TRAM-WEAVERS Labyrinthuleæ 1. Labyrinthuleæ Labyrinthula - - { 1. Striata Navicula - 6. FLINT-CELLS Diatomea { 2. Vittata Tabellaria - { 3. Areolata Coscinodiscus - - { 1. Physareæ Æthalium - 7. SLIME-MOULDS Myxomycetes { 2. Stemoniteæ Stemonitis - { 3. Trichiaceæ Arcyria - { 4. Lycogaleæ Reticularia - - { I. Acyttaria { 1. Monothalamia Gromia - { { 2. Polythalamia Nummulina - 8. RAY-STREAMERS { - OR RHIZOPODS. { II. Heliozoa 1. Heliozoa Actinosphærium - (Root-feet) { - { { 1. Monocyttaria Cyrtidosphæra - { III. Radiolaria { 2. Polycyttaria Collosphæra - - -[Illustration: FIG. 8.--Protamoeba primitiva, a fresh-water Moneron, -much enlarged. _A._ The entire Moneron with its form-changing processes. -_B._ It begins to divide itself into two halves. _C._ The division of -the two halves is completed, and each now represents an independent -individual.] - -It will perhaps seem strange that I should here again begin with the -remarkable _Monera_ as the first class of the Protista kingdom, as I of -course look upon them as the most ancient primary forms of all organisms -without exception. Still, what are we otherwise to do with the _still -living Monera_? We know nothing of their palæontological origin, we know -nothing of any of their relations to lower animals or plants, and we -know nothing of their possible capability of developing into higher -organisms. The simple and homogeneous little lump of slime or mucus -which constitutes their entire body (Fig. 8) is the most ancient and -original form of animal as well as of vegetable plastids. Hence it would -evidently be just as arbitrary and unreasonable to assign them to the -animal as it would be to assign them to the vegetable kingdom. In any -case we shall for the present be acting more cautiously and critically -if we comprise the still living Monera--whose number and distribution is -probably very great--as a special and independent class, contrasting -them with the other classes of the kingdom Protista, as well as with the -animal kingdom. Morphologically considered, the Monera--on account of -the perfect homogeneity of the albuminous substance of their bodies, on -account of their utter want of heterogeneous particles--are more closely -connected with anorgana than with organisms, and evidently form the -transition between the inorganic and organic world of bodies, as is -necessitated by the hypothesis of spontaneous generation. I have -described and given illustrations of the forms and vital phenomena of -the still living Monera (Protamoeba, Protogenes, Protomyxa, etc.) in my -Monograph of the Monera,(15) and have briefly mentioned the most -important facts in the eighth chapter (vol. i. pp. 183-187). Therefore, -only by way of a specimen, I here repeat the drawing of the fresh-water -Protamoeba (Fig. 8). The history of the life of an orange-red _Protomyxa -adrantiaca_, which I observed at Lanzerote, one of the Canary Islands, -is given in Plate I. (see its explanation in the Appendix). Besides -this, I here add a drawing of the form of Bathybius, that remarkable -Moneron discovered by Huxley, which lives in the greatest depths of the -sea in the shape of naked lumps of protoplasm and reticular mucus (vol. -i. p. 344). - -[Illustration: FIG. 9.--Bathybius Hæckelii, the "creature of primæval -slime," from the greatest depths of the sea. The figure, which is -greatly magnified, only shows that form of the Bathybius which consists -of a naked network of protoplasm, without the discoliths and cyatholiths -which are found in other forms of the same Moneron, and which perhaps -may be considered as the products of its secretion.] - -The _Amoebæ_ of the present day, and the organisms most closely -connected with them, _Arcellidæ_ and _Gregarinæ_, which we here unite as -a second class of Protista under the name of _Amoeboidea_ (Protoplasta), -present no fewer genealogical difficulties than the Monera. These -primary creatures are at present usually placed in the animal kingdom -without its in reality being understood why. For simple naked -cells--that is, shell-less plastids with a kernel--occur as well among -real plants as real animals. The generative cells, for example, in many -Algæ (spores and eggs) exist for a longer or shorter time in water in -the form of naked cells with a kernel, which cannot be distinguished at -all from the naked eggs of many animals (for example, those of the -Siphonophorous Medusæ). (Compare the figure of a naked egg of a -bladder-wrack in Chapter xvii. p. 90.) In reality every naked simple -cell, whether it proceeds from an animal or vegetable body, cannot be -distinguished from an independent Amoeba. For an Amoeba is nothing but a -simple primary cell, a naked little lump of cell-matter, or plasma, -containing a kernel. The contractility of this plasma, which the free -Amoeba shows in stretching out and drawing in its changing processes, is -a general vital property of the organic plasma of all animal as well as -of all vegetable plastids. When a freely moving Amoeba, which -perpetually changes its form, passes into a state of rest, it draws -itself together into the form of a globule, and surrounds itself with a -secreted membrane. It can then be as little distinguished from an animal -egg as from a simple globular vegetable cell (Fig. 10 _A_). - -[Illustration: FIG. 10.--Amoeba sphærococcus, greatly magnified. A -fresh-water Amoeba without a contractile vacuole. _A._ The enclosed -Amoeba in the state of a globular lump of plasma (_c_) enclosing a -kernel and a kernel-speck (_a_). The simple cell is surrounded by a -cyst, or cell membrane (_d_). _B._ The free Amoeba, which has burst and -left the cyst, or cell-membrane. _C._ It begins to divide by its kernel -parting into two kernels, and the cell-substance between the two -contracting. _D._ The division is completed, and the cell-substance has -entirely separated into two bodies. (_Da_ and _Db_).] - -Naked cells, with kernels, like those represented in Fig. 10 _B_, which -are continuously changing, stretching out and drawing in formless, -finger-like processes, and which are on this account called amoeboid, -are found frequently and widely dispersed in fresh water and in the sea; -nay, are even found creeping on land. They take their food in the same -way as was previously described in the case of the Protamoeba (vol. i. -p. 186). Their propagation by division can sometimes be observed. (Fig. -10 _C_, _D_.) I have described the processes in an earlier chapter (vol. -i. p. 187). Many of these formless Amoebæ have lately been recognized as -the early stages of development of other Protista (especially the -Myxomycetæ), or as the freed cells of lower animals and plants. The -colourless blood-cells of animals, for example, those of human blood, -cannot be distinguished from Amoebæ. They, like the latter, can receive -solid corpuscles into their interior, as I was the first to show by -feeding them with finely divided colouring matters (Gen. Morph. i. 271). -However, other Amoebæ (like the one given in Fig. 10) seem to be -independent "good species," since they propagate themselves unchanged -throughout many generations. Besides the real, or _naked_, Amoebæ -(Gymnamoebæ), we also find widely diffused in fresh water _case-bearing_ -Amoebæ (Lepamoebæ), whose naked plasma body is _partially_ protected by -a more or less solid shell (Arcella), sometimes even by a case -(Difflugia) composed of small stones. Lastly, we frequently find in the -body of many lower animals parasitic Amoebæ (Gregarinæ), which, adapting -themselves to a parasitic life, have surrounded their plasma-body with a -delicate closed membrane. - -The simple naked Amoebæ are, next to the Monera, the most important of -all organisms to the whole science of biology, and especially to general -genealogy. For it is evident that the Amoebæ originally arose out of -simple Monera (Protamoebæ), by the important process of segregation -taking place in their homogeneous viscid body--the differentiation of an -inner kernel from the surrounding plasma. By this means the great -progress from a simple cytod (without kernel) into a real cell (with -kernel) was accomplished (compare Fig. 8 _A_ and Fig. 10 _B_). As some -of these cells at an early stage encased themselves by secreting a -hardened membrane, they formed the first vegetable cells, while others, -remaining naked, developed into the first aggregates of animal cells. -The presence or absence of an encircling hard membrane forms the most -important, although by no means the entire, difference of form between -animal and vegetable cells. As vegetable cells even at an early stage -enclose themselves within their hard, thick, and solid cellular shell, -like that of the Amoebæ in a state of rest (Fig. 10 _A_), they remain -more independent and less accessible to the influences of the outer -world than are the soft animal cells, which are in most cases naked, or -merely covered by a thin pliable membrane. But in consequence of this -the vegetable cells cannot combine, as do the animal cells, for the -construction of higher and composite fibrous tracts, for example, the -nervous and muscular tissues. It is probable that, in the case of the -most ancient single-celled organisms, there must have developed at an -early stage the very important difference in the animal and vegetable -mode of receiving food. The most ancient single-celled animals, being -naked cells, could admit solid particles into the interior of their soft -bodies, as do the Amoebæ (Fig. 10 _B_) and the colourless blood-cells; -whereas the most ancient single-celled plants encased by their membranes -were no longer able to do this, and could admit through it only fluid -nutrition (by means of diffusion). - -[Illustration: FIG. 11.--A single Whip-swimmer (Euglena striata), -greatly magnified. Above a thread-like lashing whip is visible; in the -centre the round cellular kernel, with its kernel speck.] - -The _Whip-swimmers_ (Flagellata), which we consider as a third class of -the kingdom Protista, are of no less doubtful nature than the Amoebæ. -They often show as close and important relations to the vegetable as to -the animal kingdom. Some Flagellata at an early stage, when freely -moving about, cannot be distinguished from real plants, especially from -the spores of many Algæ; whereas others are directly allied to real -animals, namely, to the fringed Infusoria (Ciliata). The Flagellata are -simple cells which live in fresh or salt water, either singly or united -in colonies. The characteristic part of their body is a very movable -simple or compound whip-like appendage (whip, or flagellum) by means of -which they actively swim about in the water. This class is divided into -two orders. Among the fringed whip-swimmers (Cilioflagellata) there -exists, in addition to the long whip, a short fringe of vibrating hairs, -which is wanting in the unfringed whip-swimmers (Nudoflagellata). To the -former belong the flint-shelled yellow Peridinia, which are largely -active in causing the phosphorescence of the sea; to the latter belong -the green Euglenæ, immense masses of which frequently make our ponds in -spring quite green. - -[Illustration: FIG. 12.--The Norwegian Flimmer-ball (Magosphæra planula) -swimming by means of its vibratile fringes, as seen from the surface.] - -A very remarkable new form of Protista, which I have named -_Flimmer-ball_ (Magosphæra), I discovered only three years ago (in -September, 1869), on the Norwegian coast (Fig. 12), and have more -accurately described in my Biological Studies(15) (p. 137, Plate V.). -Off the island of Gis-oe, near Bergen, I found swimming about, on the -surface of the sea, extremely neat little balls composed of a number -(between thirty and forty) of fringed pear-shaped cells, the pointed -ends of which were united in the centre like radii. After a time the -ball dissolved. The individual cells swarmed about independently in the -water like fringed Infusoria, or Ciliata. These afterwards sank to the -bottom, drew their fringes into their bodies, and gradually changed into -the form of creeping Amoebæ (like Fig 10 _B_). These last afterwards -encased themselves (as in Fig. 10 _A_), and then divided by repeated -halvings into a large number of cells (exactly as in the case of the -cleavage of the egg, Fig. 6, vol. i. p. 299). The cells became covered -with vibratile hairs, broke through the case enclosing them, and now -again swam about in the shape of a fringed ball (Fig. 12). This -wonderful organism, which sometimes appears like a simple Amoeba, -sometimes as a single fringed cell, sometimes as a many-celled fringed -ball, can evidently be classed with none of the other Protista, and must -be considered as the representative of a new independent group. As this -group stands midway between several Protista, and links them together, -it may bear the name of _Mediator_, or _Catallacta_. - -[Illustration: FIG. 13.--Labyrinthula macrocystis (much enlarged). Below -is a large group of accumulated cells, one of which, on the left, is -separating itself; above are two single cells which are gliding along -the threads of the retiform labyrinth which form their "tramways."] - -The Protista of the fifth class, the _Tram-weavers_, or _Labyrinthuleæ_, -are of a no less puzzling nature; they were lately discovered by -Cienkowski on piles in sea water (Fig. 13). They are spindle-shaped -cells, mostly of a yellow-ochre colour, which are sometimes united into -a dense mass, sometimes move about in a very peculiar way. They form, in -a manner not yet explained, a retiform frame of entangled threads -(compared to a labyrinth), and on the dense filamentous "tramways" of -this frame they glide about. From the shape of the cells of the -Labyrinthuleæ we might consider them as the simplest plants, from their -motion as the simplest animals, but in reality they are neither animals -nor plants. - -[Illustration: FIG. 14.--Navicula hippocampus (greatly magnified). In -the middle of the cell the cell-kernel (nucleus) is visible, together -with its kernel speck (nucleolus).] - -The _Flint-cells_ (Diatomeæ), a sixth class of Protista, are perhaps the -most closely related to the Labyrinthuleæ. These primary -creatures--which at present are generally considered as plants, although -some celebrated naturalists still look upon them as animals--inhabit the -sea and fresh waters in immense masses, and offer an endless variety of -the most elegant forms. They are mostly small microscopic cells, which -either live singly (Fig. 14), or united in great numbers, and occur -either attached to objects, or glide and creep about in a peculiar -manner. Their soft cell-substance, which is of a characteristic brownish -yellow colour, is always enclosed by a solid and hard flinty shell, -possessing the neatest and most varied forms. This flinty covering is -open to the exterior only by one or two slits, through which the -enclosed soft plasma-body communicates with the outer world. The flinty -cases are found petrified in masses, and many rocks--for example, the -Tripoli slate polish, the Swedish mountain meal, etc.,--are in a great -measure composed of them. - -A seventh class of Protista is formed by the remarkable _Slime-moulds_ -(Myxomycetes). They were formerly universally considered as plants, as -real Fungi, until ten years ago the botanist De Bary, by discovering -their ontogeny, proved them to be quite distinct from Fungi, and rather -to be akin to the lower animals. The mature body is a roundish bladder, -often several inches in size, filled with fine spore-dust and soft -flakes (Fig. 15), as in the case of the well-known puff-balls -(Gastromycetes). However, the characteristic cellular threads, or hyphæ, -of a real fungus do not arise from the germinal corpuscles, or spores, -of the Myxomycetes, but merely naked masses of plasma, or cells, which -at first swim about in the form of Flagellata (Fig. 11), afterwards -creep about like the Amoebæ (Fig. 10 _B_), and finally combine with -others of the same kind to form large masses of "slime," or "plasmodia." -Out of these, again, there arises, by-and-by, the bladder-shaped -fruit-body. Many of my readers probably know one of these plasmodia, the -Æthalium septicum, which in summer forms a beautiful yellow mass of soft -mucus, often several feet in breadth, known by the name of "tan -flowers," and penetrates tan-heaps and tan-beds. At an early stage these -slimy, freely-creeping Myxomycetes, which live for the most part in damp -forests, upon decaying vegetable substances, bark of trees, etc., are -with equal justice or injustice declared by zoologists to be animals, -while in the mature, bladder-shaped condition of fructification they are -by botanists defined as plants. - -[Illustration: FIG. 15.--A stalked fruit-body (spore-bladder, filled -with spores) of one of the Myxomycetes (Physarum albipes) not much -enlarged.] - -The nature of the _Ray-streamers_ (Rhizopoda), the eighth class of the -kingdom Protista, is equally obscure. These remarkable organisms have -peopled the sea from the most ancient times of the organic history of -the earth, in an immense variety of forms, sometimes creeping at the -bottom of the sea, sometimes swimming on the surface. Only very few live -in fresh water (Gromia, Actinosphærium). Most of them possess solid -calcareous or flinty shells of an extremely beautiful construction, -which can be perfectly preserved in a fossil state. They have frequently -accumulated in such huge numbers as to form mountain masses, although -the single individuals are very small, and often scarcely visible, or -completely invisible to the naked eye. A very few attain the diameter -of a few lines, or even as much as a couple of inches. The name which -the class bears is given because thousands of exceedingly fine threads -of protoplasm radiate from the entire surface of their naked slimy body; -these rays are quasi-feet, or pseudopodia, which branch off like roots -(whence the term Rhizopoda, signifying root-footed), unite like nets, -and are observed continually to change form, as in the case of the -simpler plasmic feet of the Amoeboidea, or Protoplasts. These -ever-changing little pseudo-feet serve both for locomotion and for -taking food. - -The class of the Rhizopoda is divided into three different legions, viz. -the chamber-shells, or Acyttaria, the sun-animalcules, or Heliozoa, and -the basket-shells, or Radiolaria. The _Chamber-shells_ (Acyttaria) -constitute the first and lowest of these three legions; for the whole of -their soft body consists merely of simple mucous or slimy cell-matter, -or protoplasm, which has not differentiated into cells. However, in -spite of this most primitive nature of body, most of the Acyttaria -secrete a solid shell composed of calcareous earth, which presents a -great variety of exquisite forms. In the more ancient and more simple -Acyttaria this shell is a simple chamber, bell-shaped, tubular, or like -the shell of a snail, from the mouth of which a bundle of plasmic -threads issues. In contrast to these _single-chambered forms_ -(Monothalamia), the _many-chambered forms_ (Polythalamia)--to which the -great majority of the Acyttaria belong--possess a house, which is -composed in an artistic manner of numerous chambers. These chambers -sometimes lie in a row one behind the other, sometimes in concentric -circles or spirals, in the form of a ring round a central point, and -then frequently one above another in many tiers, like the boxes of an -amphitheatre. This formation, for example, is found in the nummulites, -whose calcareous shells, of the size of a lentil, have accumulated to -the number of millions, and form whole mountains on the shores of the -Mediterranean. The stones of which some of the Egyptian pyramids are -built consist of such nummulitic limestone. In most cases the chambers -of the shells of the Polythalamia are wound round one another in a -spiral line. The chambers are connected with one another by passages and -doors, like rooms of a large palace, and are generally open towards the -outside by numerous little windows, out of which the plasmic body can -stream or strain forth its little pseudo-feet, or rays of slime, which -are always changing form. But in spite of the exceedingly complicated -and elegant structure of this calcareous labyrinth, in spite of the -endless variety in the structure and the decoration of its numerous -chambers, and in spite of the regularity and elegance of their -execution, the whole of this artistic palace is found to be the secreted -product of a perfectly formless, slimy mass, devoid of any component -parts! Verily, if the whole of the recent anatomy of animal and -vegetable textures did not support our theory of plastids, if all its -important results did not unanimously corroborate the fact that the -whole miracle of vital phenomena and vital forms is traceable to the -active agency of the formless albuminous combinations of protoplasm, the -Polythalamia alone would secure the triumph of that theory. For we may -here at any moment, by means of the microscope, point out the wonderful -fact, first established by Dujardin and Max Schulze, that the formless -mucus of the soft plasma-body, this true "matter of life," is able to -secrete the neatest, most regular, and most complicated structures. This -secretive skill is simply a result of _inherited adaptation_, and by it -we learn to understand how this same "primæval slime"--this same -protoplasm--can produce in the bodies of animals and plants the most -different and most complicated cellular forms. - -It is, moreover, a matter of special interest that the most ancient -organism, the remains of which are found in a petrified condition, -belongs to the Polythalamia. This organism is the "Canadian Life's-dawn" -(_Eozoon canadense_), which has already been mentioned, and which was -found a few years ago in the Ottawa formation (in the deepest strata of -the Laurentian system), on the Ottawa river in Canada. If we expected to -find organic remains at all in these most ancient deposits of the -primordial period, we should certainly look for such of the most simple -Protista as are covered with a solid shell, and in the organization of -which the difference between animal and plant is as yet not indicated. - -We know of but few species of the _Sun-animalcules_ (Heliozoa), the -second class of the Rhizopoda. One species is very frequently found in -our fresh waters. It was observed even in the last century by a -clergyman in Dantzig, Eichhorn by name, and it has been called after -him, Actinosphærium Eichhornii. To the naked eye it appears as a -gelatinous grey globule of mucus, about the size of a pin's head. -Looking at it through the microscope, we see hundreds or thousands of -fine mucous threads radiating from the central plasma body, and perceive -that the inner layer of its cell-substance is different from the outer -layer, which forms a bladder-like membrane. In consequence of its -structure, this, the little sun-animalcule, although wanting a shell, -really rises above the structureless Acyttaria, and forms the transition -from these to the Radiolaria. The genus Cystophrys is of a nature akin -to it. - -The _Basket-shells_ (Radiolaria) form the third and last class of the -Rhizopoda. Their lower forms are closely allied to the Heliozoa and -Acyttaria, whereas their higher forms rise far above them. They are -essentially distinguished from both by the fact that the central part of -their body is composed of many cells, and surrounded by a solid -membrane. This closed "central capsule," generally of a globular shape, -is covered by a mucous layer of plasma, out of which there radiate on -all sides thousands of exceedingly fine threads, the branching and -confluent so-called pseudopodia. Between these are scattered numerous -yellow cells of unknown function, containing grains of starch. Most -Radiolaria are characterized by a highly developed skeleton, which -consists of flint, and displays a wonderful richness of the neatest and -most curious forms. Sometimes this flinty skeleton forms a simple -trellice-work ball (Fig. 16 _s_), sometimes a marvellous system of -several concentric trelliced balls, encased in one another, and -connected by radial staves. In most cases delicate spikes, which are -frequently branched like a tree, radiate from the surface of the balls. -In other cases the whole skeleton consists of only one flinty star, and -is then generally composed of twenty staves, distributed according to -definite mathematical laws, and united in a common central point. The -skeletons of other Radiolaria again form symmetrical many-chambered -structures, as in the case of the Polythalamia. Perhaps no other group -of organisms develop in the formation of their skeletons such an amount -of various fundamental forms, such geometrical regularity, and such -elegant architecture. Most of the forms as yet discovered, I have given -in the atlas accompanying my Monograph of the Radiolaria.(23) Here I -shall only give as an example the picture of one of the simplest forms, -the _Cyrtidosphæra echinoides_ of Nice. The skeleton in this case -consists only of a simple trelliced ball (_s_), with short radial spikes -(_a_), which loosely surround the central capsule (_c_). Out of the -mucous covering, enclosing the latter, radiate a great number of -delicate little pseudopodia (_p_), which are partly drawn back -underneath the shell, and fused into a lumpy mass of mucus. Between -these are scattered a number of yellow cells (_l_). - -[Illustration: FIG. 16.--Cyrtidosphæra echinoides, 400 times enlarged. -_c._ Globular central capsule. _s._ Basket-work of the perforated flinty -shell. _a._ Radial spikes, which radiate from the latter. _p._ The -pseudo-feet radiating from the mucous covering surrounding the central -capsule. _l._ Yellow globular cells, scattered between the latter, -containing grains of starch.] - -Most Acyttaria live only at the bottom of the sea, on stones and -seaweeds, or creep about in sand and mud by means of their pseudopodia, -but most Radiolaria swim on the surface of the sea by means of long -pseudopodia extending in all directions. They live together there in -immense numbers, but are mostly so small that they have been almost -completely overlooked, and have only become accurately known during the -last fourteen years. Certain Radiolaria living in communities -(Polycyttaria) form gelatinous lumps of some lines in diameter. On the -other hand, most of those living isolated (Monocyttaria) are invisible -to the naked eye; but still their petrified shells are found accumulated -in such masses that in many places they form entire mountains; for -example, the Nicobar Islands in the Indian Archipelago, and the Island -of Barbadoes in the Antilles. - -As most readers are probably but little acquainted with the eight -classes of the Protista just mentioned, I shall now add some further -general observations on their natural history. The great majority of all -Protista live in the sea, some swimming freely on the surface, some -creeping at the bottom, and others attached to stones, shells, plants, -etc. Many species of Protista also live in fresh water, but only a very -small number on dry land (for example, Myxomycetes and some -Protoplasta). Most of them can be seen only through the microscope, -except when millions of individuals are found accumulated. Only a few of -them attain a diameter of some lines, or as much as an inch. What they -lack in size of body they make up for by producing astonishing numbers -of individuals, and they very considerably influence in this way the -economy of nature. The imperishable remains of dead Protista, for -instance, the flinty shells of the Diatomeæ and Radiolaria and the -calcareous shells of the Acyttaria, often form large rock masses. - -In regard to their _vital phenomena_, especially those of nutrition and -propagation, some Protista are more allied to plants, others more to -animals. Both in their mode of taking food and in the chemical changes -of their living substance, they sometimes more resemble the lower -animals, at others the lower plants. _Free locomotion_ is possessed by -many Protista, while others are without it; but this does not constitute -a characteristic distinction, as we know of undoubted animals which -entirely lack free locomotion, and of genuine plants which possess it. -All Protista have a _soul_--that is to say, are "animate"--as well as -all animals and all plants. The soul's activity in the Protista -manifests itself in their _irritability_, that is, in the movements and -other changes which take place in consequence of mechanical, electrical, -and chemical irritation of their contractile protoplasm. Consciousness -and the capability of will and thought are probably wanting in all -Protista. However, the same qualities are in the same degree also -wanting in many of the lower animals, whereas many of the higher animals -in these respects are scarcely inferior to the lower races of human -beings. In the Protista, as in all other organisms, the activities of -the soul are traceable to molecular motions in the protoplasm. - -The most important _physiological characteristic_ of the kingdom -Protista lies in the exclusively _non-sexual propagation_ of all the -organisms belonging to it. The higher animals and plants multiply almost -exclusively in a sexual manner. The lower animals and plants multiply -also, in many cases, in a non-sexual manner, by division, the formation -of buds, the formation of germs, etc. But sexual propagation almost -always exists by the side of it, and often regularly alternates with it -in succeeding generations (Metagenesis, vol. i. p. 206). All Protista, -on the other hand, propagate themselves exclusively in a non-sexual -manner, and in fact, the distinction of the two sexes among them has not -been effected--there are neither male nor female Protista. - -The Protista in regard to their vital phenomena stand midway between -animals and plants, that is to say, between their lowest forms; and the -same must be said in regard to the _chemical composition_ of their -bodies. One of the most important distinctions between the chemical -composition of animal and vegetable bodies consists in the -characteristic formation of the skeleton. The skeleton, or the solid -scaffolding of the body in most genuine plants, consists of a substance -called cellulose, devoid of nitrogen, but secreted by the nitrogenous -cell-substance, or protoplasm. In most genuine animals, on the other -hand, the skeleton generally consists either of nitrogenous combinations -(chitin, etc.) or of calcareous earth. In this respect some Protista are -more like plants, others more like animals. In many of them the skeleton -is principally or entirely formed of calcareous earth, which is met with -both in animal and vegetable bodies. But the active vital substance in -all cases is the mucous protoplasm. - -In regard to the _form_ of the Protista, it is to be remarked that the -_individuality_ of their body almost always remains at an extremely low -stage of development. Very many Protista remain for life simple plastids -or individuals of the first order. Others, indeed, form colonies or -republics of plastids by the union of several individuals. But even -these higher individuals of the second order, formed by the combination -of simple plastids, for the most part remain at a very low stage of -development. The members of such communities among the Protista remain -very similar one to another, and never, or only in a slight degree, -commence a division of labour, and are consequently as little able to -render their community fit for higher functions as are, for example, the -savages of Australia. The community of the plastids remains in most -cases very loose, and each single plastid retains in a great measure its -own individual independence. - -A second structural characteristic, which next to their low stage of -individuality especially distinguishes the Protista, is the low stage of -development of their stereometrical fundamental forms. As I have shown -in my theory of fundamental forms (in the fourth book of the General -Morphology), a definite geometrical fundamental form can be pointed out -in most organisms, both in the general form of the body and in the form -of the individual parts. This ideal fundamental form, or type, which is -determined by the number, position, combination, and differentiation of -the component parts, stands in just the same relation to the _real_ -organic form as the ideal geometrical fundamental form of crystals does -to their imperfect _real_ form. In most bodies and parts of the bodies -of animals and plants this fundamental form is a pyramid. It is a -regular pyramid in the so-called "regular radiate" forms, and an -irregular pyramid in the more highly differentiated, so-called -"bilaterally symmetrical" forms. (Compare the plates in the first volume -of my General Morphology, pp. 556-558.) Among the Protista this -pyramidal type, which prevails in the animal and vegetable kingdom, is -on the whole rare, and instead of it we have either quite irregular -(amorphous) or more simple, regular geometrical types; especially -frequent are the sphere, the cylinder, the ellipsoid, the spheroid, the -double cone, the cone, the regular polygon (tetrahedron, hexahedron, -octahedron, dodecahedron, icosahedron), etc. All the fundamental forms -of the pro-morphological system, which are of a low rank in that system, -prevail in the Protista. However, in many Protista there occur also the -higher, regular, and bilateral types, fundamental forms which -predominate in the animal and vegetable kingdoms. In this respect some -of the Protista are frequently more closely allied to animals (as the -Acyttaria), others more so to plants (as the Radiolaria). - -With regard to the _palæontological development of the kingdom -Protista_, we may form various, but necessarily very unsafe, -genealogical hypotheses. Perhaps the individual classes of the kingdom -are independent tribes, or phyla, which have developed independently of -one another and independently of the animal and the vegetable kingdoms. -Even if we adopt the monophyletic hypothesis of descent, and maintain a -common origin from a single form of Moneron for all organisms, without -exception, which ever have lived and still live upon the earth, even in -this case the connection of the neutral Protista on the one hand with -the vegetable kingdom, and on the other hand with the animal kingdom, -must be considered as very vague. We must regard them (compare p. 74) as -lower off-shoots which have developed directly out of the root of the -great double-branched organic pedigree, or perhaps out of the lowest -tribe of Protista, which may be supposed to have shot up midway between -the two diverging high and vigorous trunks of the animal and vegetable -kingdoms. The individual classes of the Protista, whether they are more -closely connected at their roots in groups, or only form a loose bunch -of root offsets, must in this case be regarded as having nothing to do -either with the diverging groups of organisms belonging to the animal -kingdom on the right, or to the vegetable kingdom on the left. They must -be supposed to have retained the original simple character of the common -primæval living thing more than have genuine animals and genuine plants. - -But if we adopt the polyphyletic hypothesis of descent, we have to -imagine a number of organic tribes, or phyla, which all shoot up by -spontaneous generation out of the same ground, by the side of and -independent of one another. (Compare p. 75.) In that case numbers of -different Monera must have arisen by spontaneous generation whose -differences would depend only upon slight, to us imperceptible, -differences in their chemical composition, and consequently upon -differences in their capability of development. A small number of Monera -would then have given origin to the animal kingdom, and, again, a small -number would have produced the vegetable kingdom. Between these two -groups, however, there would have developed, independently of them, a -large number of independent tribes, which have remained at a lower stage -of organization, and which have neither developed into genuine plants -nor into genuine animals. - -A safe means of deciding between the monophyletic and polyphyletic -hypotheses is as yet quite impossible, considering the imperfect state -of our phylogenetic knowledge. The different groups of Protista, and -those lowest forms of the animal kingdom and of the vegetable kingdom -which are scarcely distinguishable from the Protista, show such a close -connection with one another and such a confused mixture of -characteristics, that at present any systematic division and arrangement -of the groups of forms seem more or less artificial and forced. Hence -the attempt here offered must be regarded as entirely provisional. But -the more deeply we penetrate into the genealogical secrets of this -obscure domain of inquiry, the more probable appears the idea that the -vegetable kingdom and the animal kingdom are each of independent origin, -and that midway between these two great pedigrees a number of other -independent small groups of organisms have arisen by repeated acts of -spontaneous generation, which on account of their indifferent neutral -character, and in consequence of their mixture of animal and vegetable -properties, may lay claim to the designation of independent Protista. - - - II. III. - - =Vegetable Kingdom= =Animal Kingdom= - Plantæ _Animalia_ - /--------^----------\ /-------------------------------^------------\ - Flowering Plants Vertebrate Animals - _Phanerogamia_ _Vertebrata_ - | \-----v-------/ - | | - | | - | Articulated Animals | - | _Arthropoda_ | - | \-----v------/ | - | | | - | | | - | Star-fishes | | Molluscous Animals - Ferns _Echinoderma_ | | _Mollusca_ - _Filicinæ_ \-----v------/ | | \-----v------/ - | | | | | - | | | | | - | | | | | - | | | | | - Mosses \-------------------v---------------/ - _Muscinæ_ Lichens Worms - | _Lichenes_ _Vermes_ - | | | - | | | - | | Animal-trees | - | | _Zoophytes_ | - ---- Fungi | | - _Algæ_ _Fungi_ | | - | | | | - | | | | - \-------v-----/ \-----v---/ - =Neutral= - =Primæval Plants= =Primæval Creatures= =Primæval Animals= - Protophyta Protista Protozoa - \-----v------/ \-----v------/ \-----v------/ - - ||| ||||||||||| ||||| - ||| ||||||||||| ||||| - ||| ||||||||||| ||||| - Vegetable Monera Neutral Monera Animal Monera - | ||||| | - | ||||| | - | ||||| | - \--------------------------v------------/ - - | - | - =Archigonic Monera= - - (Pieces of Protoplasm which have originated by Spontaneous Generation) - - ---------------------------------------------------------------- - - - POLYPHYLETIC PEDIGREE. - - II. I. III. - - =Vegetable= =Protista= =Animal= - =Kingdom= =Kingdom= =Kingdom= - Vegetabilia Protista Animalia - \------v------/ | \-----v----/ - | | | - | | | - | /-----------------------------------^--------------------------------\ | - | Slime-moulds, | - | or | - | Mucous Fungi Ray-streamers | - | _Myxomycetes_ _Rhizopoda_ | - | \-----v------/ \-----v------/ | - | | | | - | | Flint-cells | Flimmer-balls | - | | _Diatomæ_ | _Catallacta_ | - | | \-----v------/ | \-----v------/ | - | | | | | | - | | | Whip-swimmers | | | - | | | _Flagellata_ | | | - | | | \-----v------/ | | | - | | | | | | | - | | | Tram-weavers | | | | - | | | _Labyrinthulea_ | | | | - | | | \-----v------/ | | | | - | | | | | | | | - | | | | Amoebæ, | | | =Primæval= - =Primæval Plants= | | | or | | | =Animals= - Protophyta | | | Protoplasta | | | Protozoa - \------v------/ | | | \-----v------/ | | | \-----v------/ - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - =Vegetable= | | | =Neutral= | | | =Animal= - =Monera= | | | =Monera= | | | =Monera= - | | | | | | T | T T | T | - T | | T | | T | | T | | | | T | |T | T - |T | T | T| | T | |T | T | | | | |T| | | ||T | T |T - ||T | |T | || | | | || | |T | |T| | |||T| | |||T | | || - T|||T | T||T | ||T | T|T | ||T | ||T | ||| | ||||| | |||| | |T||T - ||||| | |||| | ||| | ||| | ||| | ||| | ||| | ||||| | |||| | ||||| - ||||| | |||| | ||| | ||| | ||| | ||| | ||| | ||||| | |||| | ||||| - ------------------------------------------------------------------------------------------- - - N.B.--The lines marked with a T indicate extinct tribes of Protista, - which have arisen independently by repeated acts of Spontaneous Generation. - - -Thus, if we assume one entirely independent trunk for the vegetable -kingdom, and a second for the animal kingdom, we may set up a number of -independent stems of Protista, each of which has developed, quite -independently of other stems and trunks, from a special archigonic form -of Monera. In order to make this relation more clear, we may imagine the -whole world of organisms as an immense meadow which is partially -withered, and upon which two many-branched and mighty trees are -standing, likewise partially withered. The two great trees represent the -animal and vegetable kingdoms, their fresh and still green branches the -living animals and plants; the dead branches with withered leaves -represent the extinct groups. The withered grass of the meadow -corresponds to the numerous extinct tribes, and the few stalks, still -green, to the still living phyla of the kingdom Protista. But the common -soil of the meadow, from which all have sprung up, is primæval by -protoplasm. - - - - -CHAPTER XVII. - -PEDIGREE AND HISTORY OF THE VEGETABLE KINGDOM. - - - The Natural System of the Vegetable Kingdom.--Division of the - Vegetable Kingdom into Six Branches and Eighteen Classes.--The - Flowerless Plants (Cryptogamia).--Sub-kingdom of the Thallus - Plants.--The Tangles, or Algæ (Primary Algæ, Green Algæ, Brown - Algæ, Red Algæ).--The Thread-plants, or Inophytes (Lichens and - Fungi).--Sub-kingdom of the Prothallus Plants.--The Mosses, or - Muscinæ (Water-mosses, Liverworts, Leaf-mosses, - Bog-mosses).--The Ferns, or Filicinæ (Leaf-ferns, Bamboo-ferns, - Water-ferns, Scale-ferns).--Sub-kingdom of Flowering Plants - (Phanerogamia).--The Gymnosperms, or Plants with Naked Seeds - (Palm-ferns = Cycadeæ; Pines = Coniferæ).--The Angiosperms, or - Plants with Enclosed Seeds.--Monocotylæ.--Dicotylæ.--Cup-blossoms - (Apetalæ).--Star-blossoms (Diapetalæ).--Bell-blossoms - (Gamopetalæ). - - -Every attempt that we make to gain a knowledge of the pedigree of any -small or large group of organisms related by blood must, in the first -instance, start with the evidence afforded by the existing "_natural -system_" of this group. For although the natural system of animals and -plants will never become finally settled, but will always represent a -merely approximate knowledge of true blood relationship, still it will -always possess great importance as a hypothetical pedigree. It is true, -by a "natural system" most zoologists and botanists only endeavour to -express in a concise way the subjective conceptions which each has -formed of the objective "_form-relationships_" of organisms. These -form-relationships, however, as the reader has seen, are in reality the -necessary result of true _blood relationship_. Consequently, every -morphologist in promoting our knowledge of the natural system, at the -same time promotes our knowledge of the pedigree, whether he wishes it -or not. The more the natural system deserves its name, and the more -firmly it is established upon the concordance of results obtained from -the study of comparative anatomy, ontogeny, and palæontology, the more -surely may we consider it as the approximate expression of the true -pedigree of the organic world. - -In entering upon the task contemplated in this chapter, the genealogy of -the vegetable kingdom, we shall have, according to this principle, first -to glance at the _natural system of the vegetable kingdom_ as it is at -present (with more or less important modifications) adopted by most -botanists. According to the system generally in vogue, the whole series -of vegetable forms is divided into two main groups. These main -divisions, or sub-kingdoms, are the same as were distinguished more than -a century ago by Charles Linnæus, the founder of systematic natural -history, and which he called _Cryptogamia_, or secretly-blossoming -plants, and _Phanerogamia_, or openly-flowering plants. The latter, -Linnæus, in his artificial system of plants, divided, according to the -different number, formation, and combination of the anthers, and also -according to the distribution of the sexual organs, into twenty-three -different classes, and then added the Cryptogamia to these as the -twenty-fourth and last class. - -The _Cryptogamia_, the secretly-blossoming or flowerless plants, which -were formerly but little observed, have in consequence of the careful -investigations of recent times been proved to present such a great -variety of forms, and such a marked difference in their coarser and -finer structure, that we must distinguish no less than fourteen -different classes of them; whereas the number of classes of flowering -plants, or _Phanerogamia_, may be limited to four. However, these -_eighteen classes of the vegetable kingdom_ can again be naturally -grouped in such a manner that we are able to distinguish in all _six -main divisions_ or _branches_ of the vegetable kingdom. Two of these six -branches belong to the flowering, and four to the flowerless plants. The -table on page 82 shows how the eighteen classes are distributed among -the six branches, and how these again fall under the _sub-kingdoms_ of -the vegetable kingdom. - -The one sub-kingdom of the _Cryptogamia_ may now be naturally divided -into _two_ divisions, or sub-kingdoms, differing very essentially in -their internal structure and in their external form, namely, the Thallus -plants and the Prothallus plants. The group of _Thallus plants_ -comprises the two large branches of Tangles, or Algæ, which live in -water, and the Thread-plants, or Inophytes (Lichens and Fungi), which -grow on land, upon stones, bark of trees, upon decaying bodies, etc. The -group of _Prothallus plants_, on the other hand, comprises the two -branches of Mosses and Ferns, containing a great variety of forms. - -All _Thallus plants, or Thallophytes_, can be directly recognized from -the fact that the two morphological fundamental organs of all other -plants, stem and leaves, cannot be distinguished in their structure. The -complete body of all Algæ and of all Thread-plants is a mass composed of -simple cells, which is called a _lobe_, or _thallus_. This thallus is -as yet not differentiated into axial-organs (stem and root) and -leaf-organs. On this account, as well as through many other -peculiarities, the Thallophytes contrast strongly with all remaining -plants--those comprised under the two sub-kingdoms of Prothallus plants -and Flowering plants--and for this reason the two latter sub-kingdoms -are frequently classed together under the name of _Stemmed plants_, or -_Cormophytes_. The following table will explain the relation of these -three sub-kingdoms to one another according to the two different -views:-- - - - { A. Thallus Plants } I. Thallus Plants - { (_Thallophyta_) } (_Thallophyta_) - I. Flowerless Plants. { - (_Cryptogamia_) { - { B. Prothallus Plants } - { (_Prothallophyta_) } - } II. Stemmed Plants - } (_Cormophyta_) - } - II. Flowering Plants { C. Flowering Plants } - (_Phanerogamia_) { (_Phanerogamia_) } - - -The stemmed plants, or Cormophytes, in the organization of which the -difference of axial-organs (stem and root) and leaf-organs is already -developed, form at present, and have, indeed, for a very long period -formed, the principal portion of the vegetable world. However, this was -not always the case. In fact, stemmed plants, not only of the flowering -group, but even of the prothallus group, did not exist at all during -that immeasurably long space of time which forms the beginning of the -first great division of the organic history of the earth, under the name -of the archilithic, or primordial period. The reader will recollect that -during this period the Laurentian, Cambrian, and Silurian systems of -strata were deposited, the thickness of which, taken as a whole, -amounts to about 70,000 feet. Now, as the thickness of all the more -recent super-incumbent strata, from the Devonian to the deposits of the -present time, taken together, amounts to only about 60,000 feet, we were -enabled from this fact alone to draw the conclusion--which is probable -also for other reasons--that the archilithic, or primordial, period was -of longer duration than the whole succeeding period down to the present -time. During the whole of this immeasurable space of time, which -probably comprises many millions of centuries, vegetable life on our -earth seems to have been represented exclusively by the sub-kingdom of -Thallus plants, and, moreover, only by the class of marine Thallus -plants, that is to say, the Algæ. At least all the petrified remains -which are positively known to be of the primordial period belong -exclusively to this class. As all the animal remains of this immense -period also belong exclusively to animals that lived in water, we come -to the conclusion that at that time organisms adapted to a life on land -did not exist at all. - -For these reasons the first and most imperfect of the great provinces or -branches of the vegetable kingdom, the division of the Algæ, or Tangles, -must be of special interest to us. But, in addition, there is the -interest which this group offers when viewed by itself. In spite of the -exceedingly simple composition of their constituent cells, which are but -little differentiated, the Algæ show an extraordinary variety of -different forms. To them belong the simplest and most imperfect of all -forms, as well as very highly developed and peculiar forms. The -different groups of Algæ are distinguished as much by size of body as by -the perfection and variety of their outer form. At the lowest stage we -find such species as the minute Protococcus, several hundred thousands -of which occupy a space no larger than a pin's head. At the highest -stage we marvel at the gigantic Macrocysts, which attain a length of -from 300 to 400 feet, the longest of all forms in the vegetable kingdom. -It is possible that a large portion of the coal has been formed out of -Algæ. If not for these reasons, yet the Algæ must excite our special -attention from the fact that they form the beginning of vegetable life, -and contain the original forms of all other groups of plants, supposing -that our monophyletic hypothesis of a common origin for all groups of -plants is correct. (Compare p. 83.) - -SYSTEMATIC VIEW - -_Of the Six Branches and Eighteen Classes of the Vegetable Kingdom._ - - - ========================================================================================== - _Primary Groups_ | | | - _or Sub-Kingdoms_ | _Branches or Clades_ | _Classes_ | _Systematic Name_ - _of the_ | _of the_ | _of the_ | _of the_ - _Vegetable Kingdom._ | _Vegetable Kingdom._ | _Vegetable Kingdom._ | _Classes._ - ------------------------+-----------------------+----------------------+------------------ - - { { 1. Primæval algæ 1. _Archephyceæ_ - { { (Protophyta) - { { - { I. { 2. Green algæ 2. _Chlorophyceæ_ - A. { Tangles { (Chloroalgæ) - =Thallus Plants= { _Algæ_ { - Thallophyta { { 3. Brown algæ 3. _Phæophyceæ_ - { { (Fucoideæ) - { { - { { 4. Red algæ 4. _Rhodophyceæ_ - { { (Florideæ) - - { II. { 5. Lichens 5. _Lichenes_ - { Thread-plants { - { _Inophyta_ { 6. Fungi 6. _Fungi_ - { - { { 7. Tangle-mosses 7. _Charobrya_ - { { (Characeæ) - { { - { III. { 8. Liverworts 8. _Thallobrya_ - { Mosses { (Hepaticæ) - { _Muscinæ_ { - { { 9. Frondose-mosses 9. _Phyllobrya_ - B. { { (Frondosæ) - =Prothallus= { { - =Plants= { { 10. Turf-mosses 10. _Sphagnobrya_ - Prothallophyta { (Sphagnaceæ) - { - { { 11. Shaft-ferns 11. _Calamariæ_ - { { (Calamophyta) - { IV. { - { Ferns { 12. Frondose-ferns 12. _Filices_ - { _Felicinæ_ { (Pterideæ) - { { - { { 13. Aquatic ferns 13. _Rhizocarpeæ_ - { { (Hydropterides) - { { - { { 14. Scale-ferns 14. _Selagineæ_ - { { (Lepidophyta) - - { V. { - { Plants with { 15. Palm-ferns 15. _Cycadeæ_ - C. { Naked Seeds { - =Flowering Plants= { _Gymnosperma_ { 16. Pines 16. _Coniferæ_ - Phanerogamia { - { VI. { 17. Plants with 17. _Monocotylæ_ - { Plants with { one seed lobe - { Enclosed Seeds { - { _Angiosperma_ { 18. Plants with 18. _Dicotylæ_ - { { two seed lobes - - ---------------------------------------------------------------- - - - _Gamopetalæ_ - (Flowers with corolla) - | - _Dialypetalæ_ - (Star-shaped flowers) - | - _Monochlamydeæ_ MONOCOTYLEDONÆ - (Flowers with calyx) (One seed-lobed plants) - | | - DICOTYLEDONÆ | - (Two seed-lobed plants) | - | | - \--------------------v-------------/ - CONIFERÆ +Angiospermæ+ - CYCADEÆ (Pines) (Plants with enclosed seeds) - (Palm-ferns) | GNETACEÆ | - | | | | - \-----------v-----------------------/ - +Gymnospermæ+ - (Plants with naked seeds) _Phanerogamæ_ - | (Flowering plants) _Pterideæ_ - _Selagineæ_ | _Rhizocarpeæ_ | (Frondose-ferns) - (Scaled-ferns) |(Water-ferns) | | _Calamariæ_ - | | | | | (Shaft-ferns) - | | | | | | - \-------------------------------v------------------------/ - +Filicinæ+ - _Frondosæ_ _Sphagnaceæ_ (Ferns) - (Leaf-mosses) (Turf-mosses) | - | | | CHARACEÆ - \----------------v------------/ (Tangle-mosses) - | | - _Hepaticæ_ (Liverworts) | - | | - \------------------v--------------------/ - +Muscinæ+ (Mosses) - _Fucoideæ_ | - _Florideæ_ (Brown Algæ) | _Lichenes_ - (Red Algæ) | _Chlorophyceæ_ (Lichens) - | | (Green Algæ) | - | | | | - \------------------v-----------------/ +Fungi Inophyta+ - +Algæ+ (Tangles) (Thread-plants) - | | - \-------v------------------------------/ - _Protophyta_ - (Primæval Plants) - | - _Vegetable Monera_ - -Most people living inland can form but a very imperfect idea of this -exceedingly interesting branch of the vegetable kingdom, because they -know only its proportionately small and simple representatives living in -fresh water. The slimy green aquatic filaments and flakes of our pools -and ditches and springs, the light green slimy coverings of all kinds of -wood which have for any length of time been in contact with water, the -yellowish green, frothy, and oozy growths of our village ponds, the -green filaments resembling tufts of hair which occur everywhere in fresh -water, stagnant and flowing, are for the most part composed of different -species of Algæ. Only those who have visited the sea-shore, and wondered -at the immense masses of cast-up seaweed, and who, from the rocky coast -of the Mediterranean, have seen through the clear blue waters the -beautifully-formed and highly-coloured vegetation of Algæ at the bottom, -know how to estimate the importance of the class of Algæ. And yet, even -these marine Algæ-forests of European shores, so rich in forms, give -only a faint idea of the colossal forests of Sargasso in the Atlantic -ocean, those immense banks of Algæ, covering a space of about 40,000 -square miles--the same which made Columbus, on his voyage of discovery, -believe that a continent was near. Similar but far more extensive -forests of Algæ grew in the primæval ocean, probably in dense masses, -and what countless generations of these archilithic Algæ have died out -one after another is attested, among other facts, by the vast thickness -of Silurian alum schists in Sweden, the peculiar composition of which -proceeds from those masses of submarine Algæ. According to the recently -expressed opinion of Frederick Mohr, a geologist of Bonn, even the -greater part of our coal seams have arisen out of the accumulated dead -bodies of the Algæ forests of the ocean. - -Within the branch of the Algæ we distinguish four different classes, -each of which is again divided into several orders and families. These -again contain a large number of different genera and species. We -designate these four classes as Primæval Algæ, or Archephyceæ, Green -Algæ, or Chlorophyceæ, Brown Algæ, or Phæophyceæ, and Red Algæ, or -Rhodophyceæ. - -The first class of Algæ, the _Primæval_ Algæ (Archephyceæ), might also -be called _primæval plants_, because they contain the simplest and most -imperfect of all plants, and, among them, those most ancient of all -vegetable organisms out of which all other plants have originated. To -them therefore belong those most ancient of all vegetable Monera which -arose by spontaneous generation in the beginning of the Laurentian -period. Further, we have to reckon among them all those vegetable forms -of the simplest organization which first developed out of the Monera in -the Laurentian period, and which possessed the form of a single -plastid. At first the entire body of one of these small primary plants -consisted only of a most simple cytod (a plastid without kernel), and -afterwards attained the higher form of a simple cell, by the separation -of a kernel in the plasma. (Compare above, vol. i. p. 345.) Even at the -present day there exist various most simple forms of Algæ which have -deviated but little from the original primary plants. Among them are the -Algæ of the families Codiolaceæ, Protococcaceæ, Desmidiaceæ, -Palmellaceæ, Hydrodictyeæ, and several others. The remarkable group of -Phycochromaceæ (Chroococcaceæ and Oscillarineæ) might also be comprised -among them, unless we prefer to consider them as an independent tribe of -the kingdom Protista. - -The monoplastic Protophyta--that is, those primary Algæ formed by a -single plastid--are of the greatest interest, because the vegetable -organism in this case completes its whole course of life as a perfectly -simple "individual of the first order," either as a cytod without -kernel, or as a cell containing a kernel. - -Among the primary plants consisting of a single cytod are the -exceedingly remarkable Siphoneæ, which are of considerable size, and -strangely "mimic" the forms of higher plants. Many of the Siphoneæ -attain a size of several feet, and resemble an elegant moss (Bryopsis), -or in some cases a perfect flowering plant with stalks, roots, and -leaves (Caulerpa) (Fig. 17). Yet the whole of this large body, -externally so variously differentiated, consists internally of an -entirely simple sack, possessing the negative characters of a simple -cytod. - -[Illustration: FIG. 17.--Caulerpa denticulata, a monoplastic Siphonean -_of the natural size_. The entire branching primary plant, which appears -to consist of a creeping stalk with fibrous roots and indented leaves, -is in reality only _a single plastid_, and moreover a cytod (without a -kernel), not even attaining the grade of a cell with nucleus.] - -These curious Siphoneæ, Vaucheriæ, and Caulerpæ show us to how great a -degree of elaboration a single cytod, although a most simple individual -of the first order, can develop by continuous adaptation to the -relations of the outer world. Even the _single-celled primary -plants_--which are distinguished from the monocytods by possessing a -kernel--develop into a great variety of exquisite forms by adaptation; -this is the case especially with the beautiful _Desmidiaceæ_, of which -a species of Euastrum is represented in Fig. 18 as a specimen. - -[Illustration: FIG. 18.--Euastrum rota, a single-celled Desmid, much -enlarged. The whole of the star-shaped body of this primæval plant has -the formal value of a simple cell. In its centre lies the kernel, and -within this the kernel corpuscle, or speck.] - -It is very probable that similar primæval plants, the soft body of -which, however, was not capable of being preserved in a fossil state, at -one time peopled the Laurentian primæval sea in great masses and -varieties, and in a great abundance of forms, without, however, going -beyond the stage of individuality of a simple plastid. - -The group of _Green Tangles_ (Chlorophyceæ), or _Green Algæ_ -(Cloroalgæ), are the second class, and the most closely allied to the -primæval group. Like the majority of the Archephyceæ, all the -Chlorophyceæ are coloured green, and by the same colouring matter--the -substance called leaf-green, or chlorophyll--which colours the leaves of -all the higher plants. - -To this class belong, besides a great number of low marine Algæ, most of -the Algæ of fresh water, the common water hair-weeds, or Confervæ, the -green slime-balls, or Gloeosphæræ, the bright green water-lettuce, or -Ulva, which resembles a very thin and long lettuce leaf, and also -numerous small microscopic algæ, dense masses of which form a light -green shiny covering to all sorts of objects lying in water--wood, -stones, etc. - -These forms, however, rise above the simple primary Algæ in the -composition and differentiation of their body. As the green Algæ, like -the primæval Algæ, mostly possess a very soft body, they are but rarely -capable of being petrified. However, it can scarcely be doubted that -this class of Algæ--which was the first to develop out of the preceding -one--most extensively and variously peopled the fresh and salt waters of -the earth in early times. - -In the third class, that of the _Brown Tangles_ (Phæophyceæ), or _Black -Algæ_ (Fucoideæ), the _branch_ of the Algæ attains its highest stage of -development, at least in regard to size and body. The characteristic -colour of the Fucoid is more or less dark brown, sometimes tending more -to an olive green or yellowish green, sometimes more to a brownish red -or black colour. - -Among these are the largest of all Algæ, which are at the same time the -longest of all plants, namely, the colossal giant Algæ, amongst which -the Macrocystis pyrifera, on the coast of California, attains a length -of 400 feet. Also, among our indigenous Algæ, the largest forms belong -to this group. Especially I may mention here the stately sugar-tangle -(Laminaria), whose slimy, olive green thallus-body, resembling gigantic -leaves of from 10 to 15 feet in length, and from a half to one foot in -breadth, are thrown up in great masses on the coasts of the North and -Baltic seas. - -To this class belongs also the bladder-wrack (Fucus vesiculosus) common -in our seas, whose fork-shaped, deeply-cut leaves are kept floating on -the water by numerous air bladders (as is the case, too, with many other -brown Algæ). The freely floating Sargasso Alga (Sargasso bacciferum), -which forms the meadows or forests of the Sargasso Sea, also belongs to -this class. - -Although each individual of these large alga-trees is composed of many -millions of cells, yet at the beginning of its existence it consists, -like all higher plants, of a single cell--a simple egg. This egg--for -example, in the case of our common bladder-wrack--is a naked, uncovered -cell, and as such is so like the naked egg-cells of lower marine -animals--for example, those of the Medusæ--that they might easily be -mistaken one for another (Fig. 19). - -[Illustration: FIG. 19.--The egg of the common bladder-wrack (Fucus -vesiculosus), a simple naked cell, much enlarged. In the centre of the -naked globule of protoplasm the bright kernel is visible.] - -It was probably the Fucoideæ, or Brown Algæ, which during the primordial -period, to a great extent constituted the characteristic alga-forests of -that immense space of time. Their petrified remains, especially those -of the Silurian period, which have been preserved, can, it is true, -give us but a faint idea of them, because the material of these Algæ, -like that of most others, is ill-suited for preservation in a fossil -state. As has already been remarked, a large portion of coal is perhaps -composed of them. - -Less important is the fourth class of Algæ, that of the _Rose-coloured -Algæ_ (Rhodophyceæ), or _Red Sea-weeds_ (Florideæ). This class, it is -true, presents a great number of different forms; but most of them are -of much smaller size than the Brown Algæ. Although they are inferior to -the latter in perfection and differentiation, they far surpass them in -some other respects. To them belong the most beautiful and elegant of -all Algæ, which on account of the fine plumose division of their -leaf-like bodies, and also on account of their pure and delicate red -colour, are among the most charming of plants. The characteristic red -colour sometimes appears as a deep purple, sometimes as a glowing -scarlet, sometimes as a delicate rose tint, and may verge into violet -and bluish purple, or on the other hand into brown and green tints of -marvellous splendour. Whoever has visited one of our sea-coast watering -places, must have admired the lovely forms of the Florideæ, which are -frequently dried on white paper and offered for sale. - -Most of the Red Algæ are so delicate, that they are quite incapable of -being petrified; this is the case with the splendid Ptilotes, Plocamia, -Delesseria, etc. However, there are individual forms, like the Chondria -and Sphærococca, which possess a harder thallus, often almost as hard as -cartilage, and of these fossil remains have been preserved--principally -in the Silurian, Devonian, and Carboniferous strata, and later in the -oolites. It is probable that this class also had an important share in -the composition of the archilithic Algæ flora. - -If we now again take into consideration the flora of the primordial -period, which was exclusively formed by the group of Algæ, we can see -that it is not improbable that its four subordinate classes had a share -in the composition of those submarine forests of the primæval oceans, -similar to that which the four types of vegetation--trees with trunks, -flowering shrubs, grass, and tender leaf-ferns and mosses--at present -take in the composition of our recent land forests. - -We may suppose that the submarine tree forests of the primordial period -were formed by the huge Brown Algæ, or Fucoideæ. The many-coloured -flowers at the foot of these gigantic trees were represented by the gay -Red Algæ, or Florideæ. The green grass between was formed by the -hair-like bunches of Green Algæ, or Chloroalgæ. Finally, the tender -foliage of ferns and mosses, which at present cover the ground of our -forests, fill the crevices left by other plants, and even settle on the -trunks of the trees, at that time probably had representatives in the -moss and fern-like Siphoneæ, in the Caulerpa and Bryopsis, from among -the class of the primary Algæ, Protophyta, or Archephyceæ. - -With regard to the relationships of the different classes of Algæ to one -another and to other plants, it is exceedingly probable that the Primary -Algæ, or Archephyceæ, as already remarked, form the common root of the -pedigree, not merely for the different classes of Algæ, but for the -whole vegetable kingdom. On this account they may with justice be -designated as primæval plants, or Protophyta. - -Out of the naked vegetable Monera, in the beginning of the Laurentian -period, enclosed cytods were probably the first to arise (vol. i. p. -345), by the naked, structureless, albuminous substance of the Monera -becoming condensed in the form of a pellicle on the surface, or by -secreting a membrane. At a later period, out of these enclosed cytods -genuine vegetable cells probably arose, as a kernel or nucleus separated -itself in the interior from the surrounding cell-substance or plasma. - -The three classes of Green Algæ, Brown Algæ, and Red Algæ, are perhaps -three distinct classes, which have arisen independently of one another -out of the common radical group of Primæval Algæ, and then developed -themselves further (each according to its kind), and have variously -branched off into orders and families. The Brown and Red Algæ possess no -close blood relationship to the other classes of the vegetable kingdom. -These latter have most probably arisen out of the Primæval Algæ, either -directly or by the intermediate step of the Green Algæ. - -It is probable that Mosses (out of which, at a later time, Ferns -developed) proceeded from a group of Green Algæ, and that Fungi and -Lichens proceeded from a group of Primæval Algæ. The Phanerogamia -developed at a much later period out of Ferns. - -As a second class of the Vegetable Kingdom we have above mentioned the -_Thread-plants_ (Inophyta). We understood by this term the two closely -related classes of _Lichens_ and _Fungi_. It is possible that these -Thallus plants have not arisen out of the Primæval Algæ, but out of one -or more Monera, which, independently of the latter, arose by spontaneous -generation. It appears conceivable that many of the lowest Fungi, as for -example, many ferment-causing fungi (forms of Micrococcus, etc.), owe -their origin to a number of different _archigonic_ Monera (that is, -Monera originating by spontaneous generation). - -In any case the Thread-plants cannot be considered as the progenitors of -any of the higher vegetable classes. Lichens, as well as fungi, are -distinct from the higher plants in the composition of their soft bodies, -consisting as it does of a dense felt-work of very long, variously -interwoven, and peculiar threads or chains of cells--the so-called -_hyphæ_, on which account we distinguish them as a province under the -name Thread-plants. From their peculiar nature they could not leave any -important fossil remains, and consequently we can form only a very vague -guess at their palæontological development. - -The first class of Thread-plants, the _Fungi_, exhibit a very close -relationship to the lowest Algæ; the Algo-fungi, or Phycomycetes (the -Saprolegniæ and Peronosporæ) in reality only differ from the -bladder-wracks and Siphoneæ (the Vaucheria and Caulerpa) mentioned -previously by the want of leaf-green, or chlorophyll. But, on the other -hand, all genuine Fungi have so many peculiarities, and deviate so much -from other plants, especially in their mode of taking food, that they -might be considered as an entirely distinct province of the vegetable -kingdom. - -Other plants live mostly upon inorganic food, upon simple combinations -which they render more complicated. They produce protoplasm by the -combination of water, carbonic acid, and ammonia. They take in carbonic -acid and give out oxygen. But the Fungi, like animals, live upon organic -food, consisting of complicated combinations of carbon, which they -receive from other organisms and assimilate. They inhale oxygen and -give out carbonic acid like animals. They also never form leaf-green, or -chlorophyll, which is so characteristic of most other plants. In like -manner they never produce starch. Hence many eminent botanists have -repeatedly proposed to remove the Fungi completely out of the vegetable -kingdom, and to regard them as a special and third kingdom, between that -of animals and plants. By this means our kingdom of Protista would be -considerably increased. The Fungi in this case would, in the first -place, be allied to the so-called "slime moulds," or Myxomycetes (which, -however, never form any hyphæ). But as many Fungi propagate in a sexual -manner, and as most botanists, according to the prevalent opinion, look -upon Fungi as genuine plants, we shall here leave them in the vegetable -kingdom, and connect them with lichens, to which they are at all events -most nearly related. - -The phyletic origin of Fungi will probably long remain obscure. The -close relationship already hinted at between the Phycomycetes and -Siphoneæ (especially between the Saprolegniæ and Vaucheriæ) suggests to -us that they are derived from the latter. Fungi would then have to be -considered as Algæ, which by adaptation to a parasitical life have -become very peculiarly transformed. Many facts, however, support the -supposition that the lowest fungi have originated independently from -archigonic Monera. - -The second class of Inophyta, the _Lichens_ (Lichenes), are very -remarkable in relation to phylogeny; for the surprising discoveries of -late years have taught us that every Lichen is really composed of two -distinct plants--of a low form of Alga (Nostochaceæ, Chroococcaceæ), and -of a parasitic form of Fungus (Ascomycetes), which lives as a parasite -upon the former, and upon the nutritive substances prepared by it. The -green cells, containing chlorophyll (gonidia), which are found in every -lichen, belong to the Alga. But the colourless threads (hyphæ) which, -densely interwoven, form the principal mass of the body of Lichens, -belong to the parasitic Fungus. But in all cases the two forms of -plants--Fungus and Alga--which are always considered as members of two -quite distinct provinces of the vegetable kingdom, are so firmly united, -and so thoroughly interwoven, that nearly every one looks upon a Lichen -as a single organism. - -Most Lichens form small, more or less formless or irregularly indented, -crust-like coverings to stones, bark of trees, etc. Their colour varies -through all possible tints, from the purest white to yellow, red, green, -brown, and the deepest black. - -Many lichens are important in the economy of nature from the fact that -they can settle in the driest and most barren localities, especially on -naked rocks upon which no other plant can live. The hard black lava, -which covers many square miles of ground in volcanic regions, and which -for centuries frequently presents the most determined opposition to the -life of every kind of vegetation, is always first occupied by Lichens. -It is the white or grey Lichens (Stereocaulon) which, in the most -desolate and barren fields of lava, always begin to prepare the naked -rocky ground for cultivation, and conquer it for subsequent higher -vegetation. Their decaying bodies form the first mould in which mosses, -ferns, and flowering plants can afterwards take firm root. Hardy Lichens -are also less affected by the severity of climate than any other plants. -Hence the naked rocks, even in the highest mountains--for the most part -covered by eternal snow, on which no plant could thrive--are encrusted -by the dry bodies of Lichens. - -Leaving now the Fungi, Lichens, and Algæ, which are comprised under the -name of Thallus plants, we enter upon the second sub-kingdom of the -vegetable kingdom, that of the _Prothallus plants_ (Prothallophyta), -which by some botanists are called phyllogonic Cryptogamia (in -contradistinction to the Thallus plants, or thallogonic Cryptogamia). -This sub-kingdom comprises the two provinces of _Mosses_ and _Ferns_. - -Here we meet with (except in a few of the lowest forms) the separation -of the vegetable body into two different fundamental organs, -axial-organs (stem and root) and leaves (or lateral organs). In this the -Prothallus plants resemble the Flowering plants, and hence the two -groups have recently often been classed together as stemmed plants, or -Cormophytes. - -But, on the other hand, Mosses and Ferns resemble the Thallus plants, in -the absence of the development of flowers and seeds, and even Linnæus -classed them with these, as Cryptogamia, in contradistinction to the -plants forming seeds; that is, flowering plants (Anthophyta or -Phanerogamia). - -Under the name of "Prothallus plants" we combine the closely-related -Mosses and Ferns, because both exhibit a peculiar and characteristic -"alternation of generation" in the course of their individual -development. For every species exhibits two different generations, of -which the one is usually called the _Prothallium_, or _Fore-growth_, the -other is spoken of as the _Cormus_, or actual _Stem_ of the moss or -fern. - -The first and original generation, the Fore-growth, or Prothallus, also -called Protonema, still remains in that lower stage of elaboration -manifested throughout life by all Thallus plants; that is to say, stem -and leaf-organs have as yet not differentiated, and the entire cell-mass -of the Fore-growth corresponds to a simple thallus. The second and more -perfect generation of mosses and ferns--the Stem, or Cormus--develops a -much more highly elaborate body, which has differentiated into stalk and -leaf (as in the case of flowering plants), except in the lowest mosses, -where this generation also remains in the lower stage of the thallus. - -With the exception of these latter forms the first generation of Mosses -and Ferns (the thallus-shaped Fore-growth) always produces a second -generation with stem and leaves; the latter in its turn produces the -thallus of the first generation, and so on. Thus, in this case, as in -the ordinary cases of alternation of generation in animals, the first -generation is like the third, fifth, etc., the second like the fourth, -sixth, etc. (Compare vol. i. p. 206.) - -Of the two main classes of Prothallus plants, the Mosses in general are -at a much lower stage of development than the Ferns, and their lowest -forms (especially in an anatomical respect) form the transition from the -Thallus plants through the Algæ to Ferns. The genealogical connection of -Mosses and Ferns which is indicated by this fact can, however, be -inferred only from the case of the most imperfect forms of the two -classes; for the more perfect and higher groups of mosses and ferns do -not stand in any close relation to one another, and develop in -completely opposite directions. In any case Mosses have arisen directly -out of Thallus plants, and probably out of Green Algæ. - -Ferns, on the other hand, are probably derived from extinct unknown -Mosses, which were very nearly related to the lowest liverworts of the -present day. In the history of creation, Ferns are of greater importance -than Mosses. - -The branch of _Mosses_ (Muscinæ, also called Musci, or Bryophyta) -contains the lower and more imperfect plants of the group of -Prothallophytes, which as yet do not possess vessels. Their bodies are -mostly so tender and perishable that they are very ill-suited for being -preserved in a recognizable state as fossils. Hence the fossil remains -of all classes of Mosses are rare and insignificant. It is probable that -Mosses developed in very early times out of the Thallus plants, or, to -be more precise, out of the Green Algæ. It is probable that in the -primordial period there existed aquatic forms of transition from the -latter to Mosses, and in the primary period to those living on land. The -Mosses of the present day--out of the gradually differentiating -development of which comparative anatomy may draw some inferences as to -their genealogy--are divided into two different classes, namely: (1) -Liverworts; (2) Leafy Mosses. - -The first and oldest class of Mosses, which is directly allied to the -Green Algæ, or Confervæ, is formed by the _Liverworts_ (Hepaticæ, or -Thallobrya). The mosses belonging to them are, for the most part, small -and insignificant in form, and are little known. Their lowest forms -still possess, in both generations, a simple thallus like the Thallus -plants; as for example, the Ricciæ and Marchantiaceæ. But the more -highly developed liverworts, the Jungermanniaceæ and those akin to them, -gradually commence to differentiate stem and leaf, and their most -highly-developed forms are closely allied to leaf-mosses. By this -transitional series the liverworts show their direct derivation from -the Thallophytes, and more especially from the Green Algæ. - -The Mosses, which are generally the only ones known to the -uninitiated--and which, in fact, form the principal portion of the whole -branch--belong to the second class, or _Leafy Mosses_ (Musci frondosi, -called Musci in a narrow sense, also Phyllobrya). Among them are most of -those pretty little plants which, united in dense groups, form the -bright glossy carpet of moss in our woods, or which, in company with -liverworts and lichens, cover the bark of trees. As reservoirs, -carefully storing up moisture, they are of the greatest importance in -the economy of nature. Wherever man mercilessly cuts down and destroys -forests, there, as a consequence, disappear the leafy mosses which -covered the bark of the trees, or, protected by their shade, clothed the -ground, and filled the spaces between the larger plants. Together with -the leafy mosses disappear the useful reservoirs which stored up rain -and dew for times of drought. Thus arises a disastrous dryness of the -ground, which prevents the growth of any rich vegetation. In the greater -part of Southern Europe--in Greece, Italy, Sicily, and Spain--mosses -have been destroyed by the inconsiderate extirpation of forests, and the -ground has thereby been robbed of its most useful stores of moisture; -once flourishing and rich tracts of land have been changed into dry and -barren wastes. Unfortunately in Germany, also, this rude barbarism is -beginning to prevail more and more. It is probable that the small -frondose mosses have played this exceedingly important part in nature -for a very long time, possibly from the beginning of the primary period. -But as their tender bodies are as little suited as those of all other -mosses for being preserved in a fossil state, palæontology can give us -no information about this. - -We learn from the science of petrifactions much more than we do in the -case of Mosses of the importance which the second branch of Prothallus -plants--that is, Ferns--have had in the history of the vegetable world. -Ferns, or more strictly speaking, the "plants of the fern tribe" -(Filicineæ, or Pterideæ, also called Pteridophyta, or Vascular -Cryptogams), formed during an extremely long period, namely, during the -whole primary or palæolithic period, the principal portion of the -vegetable world, so that we may without hesitation call it the _era of -Fern Forests_. From the beginning of the Devonian period, in which -organisms living on land appeared for the first time, namely, during the -deposits of the Devonian, Carboniferous, and Permian strata, plants like -Ferns predominated so much over all others, that we are justified in -giving this name to that period. In the stratifications just mentioned, -but above all, in the immense layers of coal of the Carboniferous or -coal period, we find such numerous and occasionally well preserved -remains of Ferns, that we can form a tolerable vivid picture of the very -peculiar land flora of the palæolithic period. In the year 1855 the -total number of the then known palæolithic species of plants amounted to -about a thousand, and among these there were no less than 872 Ferns. -Among the remaining 128 species were 77 Gymnosperms (pines and -palm-ferns), 40 Thallus plants (mostly Algæ), and about 20 not -accurately definable Cormophyta (stem-plants). - -As already remarked, Ferns probably developed out of the lower -liverworts in the beginning of the primary period. In their -organization Ferns rise considerably above Mosses, and in their more -highly developed forms even approach the flowering plants. In Mosses, as -in Thallus plants, the entire body is composed of almost equi-formal -cells, little if at all differentiated; but in the tissues of Ferns we -find those peculiarly differentiated strings of cells which are called -the vessels of plants, and which are universally met with in flowering -plants. Hence Ferns are sometimes united as "vascular Cryptogams" with -Phanerogams, and the group so formed is contrasted as that of the -"vascular plants" with "cellular plants,"--that is, with "cellular -cryptogams" (Mosses and Thallus plants). This very important process in -the organization of plants--the formation of vessels--first occurred, -therefore, in the Devonian period, consequently in the beginning of the -second and smaller half of the organic history of the earth. - -The branch of Ferns, or Filicinæ, is divided into five distinct classes: -(1) Frondose Ferns, or Pteridæ; (2) Reed Ferns, or Calamariæ; (3) -Aquatic Ferns, or Rhizocarpeæ; (4) Snakes Tongues, or Ophioglossæ; and -(5) Scale Ferns, or Lepidophyta. By far the most important of these five -classes, and also the richest in forms, were first the Frondose Ferns, -and then the Scale-ferns, which formed the principal portion of the -palæolithic forests. The Reed Ferns, on the other hand, had at that time -already somewhat diminished in number; and of the Aquatic Ferns, we do -not even know with certainty whether they then existed. It is difficult -for us to form any idea of the very peculiar character of those gloomy -palæolithic fern forests, in which the whole of the gay abundance of -flowers of our present flora was entirely wanting, and which were not -enlivened by any birds. Of the flowering plants there then existed only -the two lowest classes, the pines and palm ferns, with naked seeds, -whose simple and insignificant blossoms scarcely deserve the name of -flowers. - -The phylogeny of Ferns, and of the Gymnosperms which have developed out -of them, has been made especially clear by the excellent investigations -which Edward Strasburger published in 1872, on "The Coniferæ and -Gnetaceæ," as also "On Azolla." This thoughtful naturalist and Charles -Martins, of Montpellier, are among the few botanists who have thoroughly -understood the fundamental value of the Theory of Descent, and the -mechanical-causal connection between ontogeny and phylogeny. The -majority of botanists do not even yet know the important difference -between homology and analogy, between the morphological and -physiological comparison of parts--which has long since been recognized -in zoology--but Strasburger has employed this distinction and the -principle of evolution in his "Comparative Anatomy of the Gymnosperms," -in order to sketch the outlines of the blood relationship of this -important group of plants. - -The class among Ferns which has developed most directly out of the -Liverworts is the class of real Ferns, in the narrow sense of the word, -the _Frondose Ferns_ (Filices, or Phyllopterides, also called Pteridæ). -In the present flora of the temperate zones this class forms only a -subordinate part, for it is in most cases represented only by low forms -without trunks. But in the torrid zones, especially in the moist, -steaming forests of tropical regions, this class presents us with the -lofty palm-like _fern trees_. These beautiful tree-ferns of the present -day, which form the chief ornament of our hot-houses, can however give -us but a faint idea of the stately and splendid frondose ferns of the -primary period, whose mighty trunks, densely crowded together, then -formed entire forests. These trunks, accumulated in super-incumbent -masses, are found in the coal seams of the Carboniferous period, and -between them, in an excellent state of preservation, are found the -impressions of the elegant fan-shaped leaves, crowning the top of the -trunk in an umbrella-like bush. The varied outlines and the -feather-like forms of these fronds, the elegant shape of the branching -veins or bunches of vessels in their tender foliage, can still be as -distinctly recognized in the impressions of the palæolithic fronds as in -the fronds of ferns of the present day. In many cases even the clusters -of fruit, which are distributed on the lower surface of the fronds, are -distinctly preserved. After the Carboniferous period, the predominance -of frondose ferns diminished, and towards the end of the secondary -period they played almost as subordinate a part as they do at the -present time. - -The Calamariæ, Ophioglossæ, and Rhizocarpeæ seem to have developed as -three diverging branches out of the Frondose Ferns, or Pteridæ. The -Calamariæ, or Calamophyta, have remained at the lowest level among these -three classes. The Calamariæ comprise three different orders, of which -only one now exists, namely, the Horse-tails (Equisetaceæ). The two -other orders, the Giant Reeds (Calamiteæ), and the Star-leaf Reeds -(Asterophylliteæ), are long since extinct. All Calamariæ are -characterized by a hollow and jointed stalk, stem, or trunk, upon which -the branches and leaves (in cases where they exist) are set so as to -encircle the jointed stem in whorls. The hollow joints of the stalk are -separated from one another by partition walls. In Horse-tails and -Calamiteæ the surface is traversed by longitudinal ribs running -parallel, as in the case of a fluted column, and the outer skin contains -so much silicious earth in the living forms, that it is used for -cleansing and polishing. In the Asterophylliteæ, the star-shaped whorls -of leaves were more strongly developed than in the two other orders. -There exist, at present, of the Calamariæ only the insignificant -Horse-tails (Equisetum), which grow in marshes and on moors; but during -the whole of the primary and secondary periods they were represented by -great trees of the genus Equisetites. There existed, at the same time, -the closely related order of the Giant Reeds (Calamites), whose strong -trunks grew to a height of about fifty feet. The order of the -Asterophyllites, on the other hand, contained smaller and prettier -plants, of a very peculiar form, and belongs exclusively to the primary -period. - -Among all Ferns, the history of the third class, that of the _Root_, or -_Aquatic Ferns_ (Rhizocarpeæ, or Hydropteridæ), is least known to us. In -their structure these ferns, which live in fresh water, are on the one -hand allied to the frond ferns, and on the other to the scaly ferns, but -they are more closely related to the latter. Among them are the but -little known moss ferns (Salvinia), clover ferns (Marsilea), and pill -ferns (Pilularia) of our fresh waters; further, the large Azolla which -floats in tropical ponds. Most of the aquatic ferns are of a delicate -nature, and hence ill-suited for being petrified. This is probably the -reason of their fossil remains being so scarce, and of the oldest of -those known to us having been found in the Jura system. It is probable, -however, that the class is much older, and that it was already -developed during the palæolithic period out of other ferns by adaptation -to an aquatic life. - -The fourth class of ferns is formed by the _Tongue Ferns_ (Ophioglossæ, -or Glossopterides). These ferns, to which belongs the Botrychium, as -well as the Ophioglossum (adder's-tongue) of our native genera, were -formerly considered as forming but a small sub-division of the frondose -ferns. But they deserve to form a special class, because they represent -important transitional forms from the Pterideæ and Lepidophytes towards -higher plants, and must be regarded as among the direct progenitors of -the flowering plants. - -The fifth and last class is formed by the _Scale Ferns_ (Lepidophytes, -or Selagines). In the same way as the Ophioglossæ arose out of the -frondose forms, the scale ferns arose out of the Ophioglossæ. They were -more highly developed than all other ferns, and form the transition to -flowering plants, which must have developed out of them. Next to the -frondose ferns they took the largest part in the composition of the -palæolithic fern forests. This class also contains, as does the class of -reed ferns, three nearly related but still very different orders, of -which only one now exists, the two others having become extinct towards -the end of the Carboniferous period. The scaled ferns still existing -belong to the order of the club-mosses (Lycopodiaceæ). They are mostly -small, pretty moss-like plants, whose tender, many-branched stalk creeps -in curves on the ground like a snake, and is densely encompassed and -covered by small scaly leaves. The pretty creeping Lycopodium of our -woods, which mountain tourists twine round their hats, is known to all, -as also the still more delicate Selaginella, which under the name of -creeping moss is used to adorn the soil of our hot-houses in the form of -a thick carpet. The largest _club-mosses_ of the present day are found -in the Sunda Islands, where their stalks rise to the height of -twenty-five feet, and attain half a foot in thickness. But in the -primary and secondary periods even larger trees of this kind were widely -distributed, the most ancient of which probably were the progenitors of -the pines (Lycopodites). The most important dimensions were, however, -attained by the class of scale trees (Lepidodendreæ), and by the seal -trees (Sigillarieæ). These two orders, with a few species, appear in the -Devonian period, but do not attain their immense and astonishing -development until the Carboniferous period, and become extinct towards -the end of it, or in the Permian period directly following upon it. The -scale trees, or Lepidodendreæ, were probably more closely related to -club-mosses than to Sigillarieæ. They grew into splendid, straight, -unbranching trunks which divided at the top into numerous forked -branches. They bore a large crown of scaly leaves, and like the trunk -were marked in elegant spiral lines by the scars left at the base of the -leaf stalks which had fallen off. We know of scale-marked trees from -forty to sixty feet in length, and from twelve to fifteen feet in -diameter at the root. Some trunks are said to be even more than a -hundred feet in length. In the coal are found still larger accumulations -of the no less highly developed but more slender trunks of the -remarkable seal trees, Sigillarieæ, which in many places form the -principal part of coal seams. Their roots were formerly described as -quite a distinct vegetable form (under the name of Stigmaria). The -Sigillarieæ are in many respects very like the scale-trees, but differ -from them and from ferns in general in many ways. They were possibly -closely related to the extinct Devonian _Lycopterideæ_, combining -characteristic peculiarities of the club-mosses and the frondose ferns, -which Strasburger considers as the hypothetical primary form of -flowering plants. - -In leaving the dense forests of the primary period, which were -principally composed of frond ferns (Lepidodendreæ and Sigillarieæ), we -pass onwards to the no less characteristic pine forests of the secondary -period. Thus we leave the domain of the Cryptogamia, the plants forming -neither flowers nor seeds, and enter the second main division of the -vegetable kingdom, namely, the sub-kingdom of the _Phanerogamia_, -_flowering plants_ forming seeds. This division, so rich in forms, -containing the principal portion of the present vegetable world, and -especially the majority of plants living on land, is certainly of a much -more recent date than the division of Cryptogamia. For it can have -developed out of the latter only in the course of the palæolithic -period. We can with full assurance maintain that, during the whole -archilithic period, hence during the first and longer half of the -organic history of the earth, no flowering plants as yet existed, and -that they first developed during the primary period out of Cryptogamia -of the fern kind. The anatomical and embryological relation of -Phanerogamia to the latter is so close, that from it we can with -certainty infer their genealogical connection, that is, their true blood -relationship. Flowering plants cannot have directly arisen out of -thallus plants, nor out of mosses; but only out of ferns, or Filicines. -Most probably the scaled ferns, or Lepidophyta, and more especially -amongst these the Lycopodiaceæ, forms closely related to the -Selaginella of the present day, have been the direct progenitors of the -Phanerogamia. - -On account of its anatomical structure and its embryological -development, the sub-kingdom of the Phanerogamia has for a long time -been divided into two large branches, into the _Gymnosperms_, or plants -with naked seeds, and the _Angiosperms_, or plants with enclosed seeds. -The latter are in every respect more perfect and more highly organized -than the former, and developed out of them only at a late date during -the secondary period. The Gymnosperms, both anatomically and -embryologically, form the transition group from Ferns to Angiosperms. - -The lower, more imperfect, and the older of the two main classes of -flowering plants, that of the _Archispermeæ_, or _Gymnosperms_ (with -naked seeds), attained its most varied development and widest -distribution during the mesolithic or secondary epoch. It was no less -characteristic of this period, than was the fern group of the preceding -primary, and the Angiosperms of the succeeding tertiary, epoch. Hence we -might call the secondary epoch that of Gymnosperms, or after its most -important representatives, the era of Pine Forests. The Gymnosperms are -divided into three classes: the Coniferæ, Cycadeæ, and Gnetaceæ. We find -fossil remains of the pines, or Conifers, and of the Cycads, even in -coal, and must infer from this that the transition from scaled ferns to -Gymnosperms took place during the Coal, or possibly even in the Devonian -period. However, the Gymnosperms play but a very subordinate part during -the whole of the primary epoch, and do not predominate over Ferns until -the beginning of the secondary epoch. - -Of the two classes of Gymnosperms just mentioned, that of the _Palm -Ferns_ (Zamiæ, or Cycadeæ) stands at the lowest stage, and is directly -allied to ferns, as the name implies, so that some botanists have -actually included them in the fern group. In their external form they -resemble palms, as well as tree ferns (or tree-like frond ferns), and -are adorned by a crown of feathery leaves, which is placed either on a -thick, short trunk, or on a slender, simple trunk like a pillar. At the -present day this class, once so rich in forms, is but scantily -represented by a few forms living in the torrid zones, namely, by the -coniferous ferns (Zamia), the thick-trunked bread-tree (Encephalartos), -and the slender-trunked Caffir bread-tree (Cycas). They may frequently -be seen in hot-houses, and are generally mistaken for palms. A much -greater variety of forms than occurs among the still existing palm ferns -(Cycadeæ) is presented by the extinct and fossil Cycads, which occurred -in great numbers more towards the middle of the secondary period, during -the Jura, and which at that time principally determined the character of -the forests. - -The class of _Pines_, or _coniferous trees_ (Coniferæ), has preserved -down to our day a greater variety of forms than have the palm ferns. -Even at the present time the trees belonging to it--cypresses, juniper -trees, and trees of life (Thuja), the box and ginko trees (Salisburya), -the araucaria and cedars, but above all the genus Pinus, which is so -rich in forms, with its numerous and important species, spruces, pines, -firs, larches, etc.--still play a very important part in the most -different parts of the earth, and almost of themselves constitute -extensive forests. Yet this development of pines seems but weak in -comparison with the predominance which the class had attained over other -plants during the early secondary period, that of the Trias. At that -time mighty coniferous trees--with but proportionately few genera and -species, but standing together in immense masses of individuals--formed -the principal part of the mesolithic forests. This fact justifies us in -calling the secondary period the "era of the pine forests," although the -remains of Cycadeæ predominate over those of coniferous trees in the -Jura period.[2] - -From the pine forests of the mesolithic, or secondary period, we pass on -into the leafy forests of the cænolithic, or tertiary period, and we -arrive thus at the consideration of the sixth and last class of the -vegetable kingdom, that of the _Metaspermæ_, _Angiospermæ_, or _plants -with enclosed seeds_. The first certain and undoubted fossils of plants -with enclosed seeds are found in the strata of the chalk system, and -indeed we here find, side by side, remains of the two classes into which -the main class of Angiosperms is generally divided, namely, the _one -seed-lobed plants_, or _monocotylæ_, and the _two seed-lobed plants_, or -_dicotylæ_. However, the whole group probably originated at an earlier -period during the Trias. For we know of a number of doubtful and not -accurately definable fossil remains of plants from the Oolitic and Trias -(sic) periods, which some botanists consider to be Monocotylæ, whilst -others consider them as Gymnosperms. In regard to the two classes of -plants with enclosed seeds, the Monocotylæ and Dicotylæ, it is -exceedingly probable that the Dicotyledons developed out of the -Gnetaceæ, but that the Monocotyledons developed later out of a branch of -the dicotyledons. - -The class of _one seed-lobed plants_ (Monocotylæ, or Monocotyledons, -also called Endogenæ) comprises those flowering plants whose seeds -possess but one germ leaf or seed lobe (cotyledon). Each whorl of its -flower contains in most cases _three_ leaves, and it is very probable -that the mother plants of all Monocotyledons possessed a regular triple -blossom. The leaves are mostly simple, and traversed by simple, straight -bunches of vessels or "nerves." To this class belong the extensive -families of the rushes, grasses, lilies, irids, and orchids, further a -number of indigenous aquatic plants, the water-onions, sea grasses, -etc., and finally the splendid and highly developed families of the -Aroideæ and Pandaneæ, the bananas and palms. On the whole, the class of -Monocotyledons--in spite of the great variety of forms which it -developed, both in the tertiary and the present period--is much more -simply organized than the class of the Dicotyledons, and its history of -development also offers much less of interest. As their fossil remains -are for the most part difficult to recognize, it still remains at -present an open question in which of the three great secondary -periods--the Trias, Jura, or chalk period--the Monocotyledons -originated. At all events they existed in the chalk period as surely as -did the Dicotyledons. - -[Illustration: - - _Haeckel History of Creation._ - - _PL. V._ - -Relative lengths of the 5 Epochs in percentages. - - Quarternary Epoch 0.5 - Tertiary Epoch 2.3 - Secondary Epoch 11.5 - Primary Epoch 32.1 - Primordial Epoch 53.6 - ----- - _Total_ 100.0 - - Single-stemmed or - MONOPHYLETIC PEDIGREE - of the - VEGETABLE KINGDOM - based on Palæontology.] - -The second class of plants with enclosed seeds, the _two seed-lobed_ -(Dicotylæ, or Dicotyledons, also called Exogenæ) presents much greater -historical and anatomical interest in the development of its subordinate -groups. The flowering plants of this class generally possess, as their -name indicates, two seed lobes or germ leaves (cotyledons). The number -of leaves composing its blossom is generally not three, as in most -Monocotyledons, but four, five, or a multiple of those numbers. Their -leaves, moreover, are generally more highly differentiated and more -composite than those of the Monocotyledons; they are traversed by -crooked, branching bunches of vessels or "veins." To this class belong -most of the leafed trees, and as they predominate in the tertiary period -as well as, at present, over the Gymnosperms and Ferns, we may call the -cænolithic period that of leafed forests. - -Although the majority of Dicotyledons belong to the most highly -developed and most perfect plants, still the lowest division of them is -directly allied to the Gymnosperms, and particularly to the Gnetaceæ. In -the lower Dicotyledons, as in the case of the Monocotyledons, calyx and -corolla are as yet not differentiated. Hence they are called _Apetalous_ -(Monochlamydeæ, or Apetalæ). This sub-class must therefore doubtless be -looked upon as the original group of the Angiosperms, and existed -probably even during the Trias and Jura periods. Among them are most of -the leafed trees bearing catkins--birches and alders, willows and -poplars, beeches and oaks; further, the plants of the nettle -kind--nettles, hemp, and hops, figs, mulberries, and elms; finally, -plants like the spurges, laurels, and amaranth. - -It was not until the chalk period that the second and more perfect class -of the Dicotyledons appeared, namely, the _group with corollas_ -(Dichlamydeæ, or Corollifloræ). These arose out of the Apetalæ from the -simple cover of the blossoms of the latter becoming differentiated into -calyx and corolla. The sub-class of the Corollifloræ is again divided -into two large main divisions or legions, each of which contains a large -number of different orders, families, genera, and species. The first -legion bears the name of star-flowers, or Diapetalæ, the second that of -the bell-flowers, or Gamopetalæ. - -The lower and less perfect of the two legions of the Corollifloræ are -the star-flowers (also called Diapetalæ or Dialypetalæ). To them belong -the extensive families of the Umbelliferæ, or umbrella-worts (wild -carrot, etc.), the Cruciferæ, or cruciform blossoms (cabbage, etc.); -further, the Ranunculaceæ (buttercups) and Crassulaceæ, the Mallows and -Geraniums, and, besides many others, the large group of Roses (which -comprise, besides roses, most of our fruit trees), and the Pea-blossoms -(containing, among others, beans, clover, genista, acacia, and mimosa). -In all these Diapetalæ the blossom-leaves remain separate, and never -grow together, as is the case in the Gamopetalæ. These latter developed -first in the tertiary period out of the Diapetalæ, whereas the Diapetalæ -appeared in the chalk period together with the Apetalæ. - -The highest and most perfect group of the vegetable kingdom is formed by -the second division of the Corollifloræ, namely, the legion of -bell-flowers (Gamopetalæ, also called Monopetalæ or Sympetalæ). In this -group the blossom-leaves, which in other plants generally remain -separate, grow regularly together into a more or less bell-like, -funnel-shaped, or tubular flower. To them belong, among others, the -Bell-flowers and Convolvulus, Primroses and Heaths, Gentian and -Honeysuckle, further the family of the Olives (olive trees, privet, -elder, and ash), and finally, besides many other families, the -extensive division of the Lip-blossoms (Labiatæ) and the Composites. In -these last the differentiation and perfection of the Phanerogamic -blossoms attain their highest stage of development, and we must -therefore place them at the head of the vegetable kingdom, as the most -perfect of all plants. In accordance with this, the legion of the -Gamopetalæ appear in the organic history of the earth later than all the -main groups of the vegetable kingdom--in fact, not until the cænolithic -or tertiary epoch. In the earliest tertiary period the legion is still -very rare, but it gradually increases in the mid-tertiary, and attains -its full development only in the latest tertiary and the quaternary -period. - -Now if, having reached our own time, we look back upon the _whole -history of the development of the vegetable kingdom_, we cannot but -perceive in it a _grand confirmation of the Theory of Descent_. The two -great principles of organic development which have been pointed out as -the necessary results of natural selection in the Struggle for Life, -namely, the laws of _differentiation_ and _perfecting_, manifest -themselves everywhere in the development of the larger and smaller -groups of the natural system of plants. In each larger or smaller period -of the organic history of the earth, the vegetable kingdom increases -both in _variety_ and _perfection_, as a glance at Plate IV. will -clearly show. During the whole of the long primordial period there -existed only the lowest and most imperfect group, that of the Algæ. To -these are added, in the primary period, the higher and more perfect -Cryptogamia, especially the main-class of Ferns. During the coal period -the Phanerogamia begin to develop out of the latter; at first, however, -they are represented only by the lower main-class, that of Gymnosperms. -It was not until the secondary period that the higher main-class, that -of Angiosperms, arose out of them. Of these also there existed at first -only the lower groups without distinct corollas, the Monocotyledons and -the Apetalæ. It was not until the chalk period that the higher -Corollifloræ developed out of the latter. But even this most highly -developed group is represented, in the chalk period, only by the lower -stage of Star-flowers, or Diapetalæ, and only at quite a late date, in -the tertiary period, did the more highly developed Bell-blossoms, -Gamopetalæ, arise out of them, which at the same time are the most -perfect of all flowering plants. Thus, in each succeeding later division -of the organic history of the earth the vegetable kingdom gradually rose -to a higher degree of perfection and variety. - - - - -CHAPTER XVIII. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -I. ANIMAL-PLANTS AND WORMS. - - - The Natural System of the Animal Kingdom.--Linnæus and Lamarck's - Systems.--The Four Types of Bär and Cuvier.--Their Increase to - Seven Types.--Genealogical Importance of the Seven Types as - Independent Tribes of the Animal Kingdom.--Derivation of - Zoophytes and Worms from Primæval Animals.--Monophyletic and - Polyphyletic Hypothesis of the Descent of the Animal - Kingdom.--Common Origin of the Four Higher Animal Tribes out of - the Worm Tribe.--Division of the Seven Animal Tribes into - Sixteen Main Classes, and Thirty-eight Classes.--Primæval - Animals (Monera, Amoebæ, Synamoebæ), Gregarines, Infusoria, - Planæades, and Gastræades (Planula and Gastrula).--Tribe of - Zoophytes.--Spongiæ (Mucous Sponges, Fibrous Sponges, Calcareous - Sponges).--Sea Nettles, or Acalephæ (Corals, Hood-jellies, - Comb-jellies).--Tribe of Worms. - - -The natural system of organisms which we must employ in the animal as -well as in the vegetable kingdom, as a guide in our genealogical -investigations, is in both cases of but recent origin, and essentially -determined by the progress of comparative anatomy and ontogeny (the -history of individual development) during the present century. Almost -all the attempts at classification made in the last century followed the -path of the artificial system, which was first established in a -consistent manner by Charles Linnæus. The artificial system differs -essentially from the natural one, in the fact that it does not make the -whole organization and the internal structure (depending upon the blood -relationship) the basis of classification, but only employs individual, -and for the most part external, characteristics, which readily strike -the eye. Thus Linnæus distinguished his twenty-four classes of the -vegetable kingdom principally by the number, formation, and combination -of the stamens. In like manner he distinguished six classes in the -animal kingdom principally by the nature of the heart and blood. These -six classes were: (1) Mammals; (2) Birds; (3) Amphibious Animals; (4) -Fishes; (5) Insects; and (6) Worms. - -But these six animal classes of Linnæus are by no means of equal value, -and it was an important advance when, at the end of the last century, -Lamarck comprised the first four classes as vertebrate animals -(Vertebrata), and put them in contrast with the remaining animals (the -insects and worms of Linnæus), of which he made a second main -division--the invertebrate animals (Invertebrata). In reality Lamarck -thus agreed with Aristotle, the father of Natural History, who had -distinguished these two main groups, and called the former -_blood-bearing animals_, the latter _bloodless animals_. - -The next important progress towards a natural system of the animal -kingdom was made some decades later by two most illustrious zoologists, -Carl Ernst Bär and George Cuvier. As has already been remarked, they -established, almost simultaneously and independently of one another, the -proposition that it was necessary to distinguish several completely -distinct main groups in the animal kingdom, each of which possessed an -entirely peculiar type or structure (compare above, vol. i. p. 53). In -each of these main divisions there is a tree-shaped and branching -gradation from most simple and imperfect forms to those which are -exceedingly composite and highly developed. The _degree of development_ -within each type is quite independent of the peculiar _plan of -structure_, which forms the basis of the type and gives it a special -characteristic. The "type" is determined by the peculiar relations in -position of the most important parts of the body, and the manner in -which the organs are connected. The degree of development, however, is -dependent upon the greater or less division of labour among organs, and -on the differentiation of the plastids and organs. This extremely -important and fruitful idea was established by Bär, who relied more -distinctly and thoroughly upon the history of individual development -than did Cuvier. Cuvier based his argument upon the results of -comparative anatomy. But neither of them recognized the true cause of -the remarkable relationships pointed out by them, which is first -revealed to us by the Theory of Descent. It shows us that the common -_type_ or plan of structure is determined by _inheritance_, and the -degree of development or differentiation by _adaptation_. (Gen. Morph. -ii. 10). - -Both Bär and Cuvier distinguished four different types in the animal -kingdom, and divided it accordingly into four great main divisions -(branches or circles). The first of these is formed by the vertebrate -animals (Vertebrata), and comprises Linnæus' first four -classes--mammals, birds, amphibious animals, and fishes. The second type -is formed by the articulated animals (Articulata), containing Linnæus' -insects, consequently the six-legged insects, and also the myriopods, -spiders, and crustacea, but besides these, a large number of the worms, -especially the ringed worms. The third main division comprises the -molluscous animals (Mollusca)--slugs, snails, mussels, and some kindred -groups. Finally, the fourth and last circle of the animal kingdom -comprises the various radiated animals (Radiata), which at first sight -differ from the three preceding types by their radiated, flower-like -form of body. For while the bodies of molluscs, articulated animals, and -vertebrated animals consist of two symmetrical lateral halves--of two -counterparts or antimera, of which the one is the mirror of the -other--the bodies of the so-called radiated animals are composed of more -than two, generally of four, five, or six counterparts grouped round a -common central axis, as in the case of a flower. However striking this -difference may seem at first, it is, in reality, a very subordinate one, -and the radial form has by no means the same importance in all "radiated -animals." - -The establishment of these natural main groups or types of the animal -kingdom by Bär and Cuvier was the greatest advance in the classification -of animals since the time of Linnæus. The three groups of vertebrated -animals, articulated animals, and molluscs are so much in accordance -with nature that they are retained, even at the present day, little -altered in extent. But a more accurate knowledge soon showed the utterly -unnatural character of the group of the radiated animals. Leuckart, in -1848, first pointed out that two perfectly distinct types were -confounded under the name, namely, the _Star-fishes_ (Echinoderma)--the -sea-stars, lily encrinites, sea-urchins, and sea-cucumbers; and, on the -other hand, the _Animal-plants_, or _Zoophytes_ (Coelenterata or -Zoophyta)--the sponges, corals, hood-jellies, and comb-jellies. At the -same time, Siebold united the Infusoria with the Rhizopoda, under the -name of Protozoa (lowest animals), into a special main division of the -animal kingdom. By this the number of animal types was increased to six. -It was finally increased to seven by the fact that modern zoologists -separated the main division of the articulated animals into two groups: -(_a_) those possessing _articulated feet_ (Arthropoda), corresponding to -Linnæus' Insects, namely, the Flies (with six legs), Myriopods, Spiders, -and Crustacea; and (_b_) the footless _Worms_ (Vermes), or those -possessing non-articulated feet. These latter comprise only the real or -genuine Worms (ring-worms, round worms, planarian worms, etc.), and -therefore in no way correspond with the Worms of Linnæus, who had -included the molluscs, the radiates, and many other lower animals under -this name. - -Thus, according to the views of modern zoologists, which are given in -all recent manuals and treatises on zoology, the animal kingdom is -composed of seven completely distinct main divisions or types, each of -which is distinguished by a characteristic plan of structure peculiar to -it, and perfectly distinct from every one of the others. In the natural -system of the animal kingdom--which I shall now proceed to explain as -its probable pedigree--I shall on the whole agree with this usual -division, but not without some modifications, which I consider very -important in connection with genealogy, and which are rendered -absolutely necessary in consequence of our view as to the history of the -development of animals. - -We evidently obtain the greatest amount of information concerning the -_pedigree of the animal kingdom_ (as well as concerning that of the -vegetable kingdom) from comparative anatomy and ontogeny. Besides -these, palæontology also throws much valuable light upon the historical -succession of many of the groups. From numerous facts in comparative -anatomy, we may, in the first place, infer the _common origin of all -those animals which belong to one of the seven "types."_ For in spite of -all the variety in the external form developed within each of these -types, the essential relative position of the parts of the body which -determines the type, is so constant, and agrees so completely in all the -members of every type, that on account of their relations of form alone -we are obliged to unite them, in the natural system, into a single main -group. But we must certainly conclude, moreover, that this conjunction -also has its expression in the pedigree of the animal kingdom. For the -true cause of the intimate agreement in structure can only be the actual -blood relationship. Hence we may, without further discussion, lay down -the important proposition that all animals belonging to one and the same -circle or type must be descended from one and the same original primary -form. In other words, the idea of the circle or type, as it is employed -in zoology since Bär and Cuvier's time to designate the few principal -main groups or "sub-kingdoms" of the animal kingdoms, coincides with the -idea of "tribe" or "phylum," as employed by the Theory of Descent. - -If, then, we can trace all the varieties of animal forms to these seven -fundamental forms, the following question next presents itself to us as -a second phylogenetic problem--Where do these seven animal tribes come -from? Are they seven original primary forms of an entirely independent -origin, or are they also distantly related by blood to one another? - -[Illustration: _PL. VI._ - -Historical Growth of the six great stems of Animals. _See the -Explanation._] - -At first we might be inclined to answer this question in a -_polyphyletic_ sense, by saying that we must assume, for each of the -seven great animal tribes, at least one independent primary form -completely distinct from the others. On further considering this -difficult problem, we arrive in the end at the notion of a -_monophyletic_ origin of the animal kingdom, viz., that these seven -primary forms are connected at their lowest roots, and that they are -derived from a single, common primæval form. _In the animal as well as -in the vegetable kingdom, when closely and accurately considered, the -monophyletic hypothesis of descent is found to be more satisfactory than -the polyphyletic hypothesis._ - -It is _comparative ontogeny_ (embryology) which first and foremost leads -to the assumption of the monophyletic origin of the whole animal kingdom -(the Protista excepted of course). The zoologist who has thoughtfully -compared the history of the individual development of various animals, -and has understood the importance of the biogenetic principle (p. 33), -cannot but be convinced that a common root must be assumed for the seven -different animal tribes, and that all animals, including man, are -derived from a single, common primary form. The result of the -consideration of the facts of embryology, or ontogeny, is the following -genealogical or phylogenetic hypothesis, which I have put forward and -explained in detail in my "Philosophy of Calcareous Sponges" (Monograph -of the Calcareous Sponges, vol. i. pp. 464, 465, etc.,--"the Theory of -the Layers of the Embryo, and the Pedigree of Animals"). - -The first stage of organic life in the Animal kingdom (as in the -Vegetable and Protista kingdoms) was formed by perfectly simple -_Monera_, originating by spontaneous generation. The former existence -of this simplest animal form is, even at present, attested by the fact -that the egg-cell of many animals loses its kernel directly after -becoming fructified, and thus relapses to the lower stage of development -of a cytod without a kernel, like a Moneron. This remarkable occurrence -I have interpreted, according to the law of latent inheritance (vol. i. -p. 205), as a phylogenetic _relapse_ of the cellular form into the -original form of a cytod. The _Monerula_, as we may call this egg-cytod -without a kernel, repeats then, according to the biogenetic principle -(vol. ii. p. 33), the most ancient of all animal forms, the common -primary form of the animal kingdom, namely, the Moneron. - -The second ontogenetic process consists in a new kernel being formed in -the Monerula, or egg-cytod, which thus returns again to the value of a -true _egg-cell_. According to this, we must look upon the simple animal -cell, containing a kernel, or the single-celled primæval animal--which -may still be seen in a living state in the _Amoebæ_ of the present -day--as the _second_ step in the series of phylogenetic forms of the -animal kingdom. Like the still living simple Amoebæ, and like the naked -egg-cells of many lower animals (for example, of Sponges and Medusæ, -etc.), which cannot be distinguished from them, the remote phyletic -primary Amoebæ also were perfectly simple naked-cells, which moved about -in the Laurentian primæval ocean, creeping by means of the ever-changing -processes of their body-substance, and nourishing and propagating -themselves in the same way as the Amoebæ of the present day. (Compare -vol. i. p. 188, and vol. ii. p. 54.) The existence of this Amoeba-like, -_single-celled primary form_ of the whole animal kingdom is unmistakably -indicated by the exceedingly important fact that the egg of all animals, -from those of sponges and worms up to those of the ant and man, is a -simple cell. - -Thirdly, from the "single-cell" state arose the _simplest multicellular -state_, namely, a heap or a small community of simple, equi-formal, and -equivalent cells. Even at the present day, in the ontogenetic -development of every animal egg-cell, there first arises a globular heap -of equi-formal naked cells, by the repeated self-division of the primary -cell. (Compare vol. i. p. 190 and the Frontispiece, Fig. 3.) We called -this accumulation of cells the _mulberry state_ (Morula), because it -resembles a mulberry or blackberry. This Morula-body occurs in the same -simple form in all the different tribes of animals, and on account of -this most important circumstance we may infer--according to the -biogenetic principle--that the _most ancient, many-celled, primary form -of the animal kingdom_ resembled a Morula like this, and was in fact a -simple heap of Amoeba-like primæval cells, one similar to the other. We -shall call this most ancient community of Amoebæ--this most simple -accumulation of animal cells--which is recapitulated in individual -development by the Morula--the _Synamoeba_. - -Out of the Synamoebæ, in the early Laurentian period, there afterwards -developed a fourth primary form of the animal kingdom, which we shall -call the ciliated germ (Planæa). This arose out of the Synamoeba by the -outer cells on the surface of the cellular community beginning to extend -vibrating fringes called cilia, and becoming "ciliated cells," and thus -differentiating from the inner and unchanged cells. The Synamoebæ -consisted of completely equi-formed and naked cells, and crept about -slowly, at the bottom of the Laurentian primæval ocean, by means of -movements like those of an Amoeba. The Planæa, on the other hand, -consisted of two kinds of different cells--inner ones like the Amoebæ, -and external "ciliated cells." By the vibrating movements of the cilia -the entire multicellular body acquired a more rapid and stronger motion, -and passed over from the creeping to the swimming mode of locomotion. In -exactly the same manner the _Morula_, in the ontogenesis of lower -animals, still changes into a ciliated form of larva, which has been -known, since the year 1847, under the name of _Planula_. This Planula is -sometimes a globular, sometimes an oval body, which swims about in the -water by means of a vibrating movement; the fringed (ciliated) and -smaller cells of the surface differ from the larger inner cells, which -are unfringed. (Fig. 4 of the Frontispiece.) - -Out of this Planula, or fringed larva, there then develops, in animals -of all tribes, an exceedingly important and interesting animal form, -which, in my Monograph of the Calcareous Sponges, I have named -_Gastrula_ (that is, larva with a stomach or intestine). (Frontispiece, -Fig. 5, 6). This Gastrula externally resembles the Planula, but differs -essentially from it in the fact that it encloses a cavity which opens to -the outside by a mouth. The cavity is the "_primary intestine_," or -"primary stomach," the _progaster_, the first beginning of the -alimentary canal; its opening is the "_primary mouth_" (prostoma). The -wall of the progaster consists of two layers of cells: an outer layer of -smaller ciliated cells (outer skin, or ectoderm), and of an inner layer -of larger non-ciliated cells (inner skin, or entoderm). This exceedingly -important larval form, the "Gastrula," makes its appearance in the -ontogenesis of all tribes of animals--in Sponges, Medusæ, Corals, Worms, -Sea-squirts, Radiated animals, Molluscs, and even in the lowest -Vertebrata (Amphioxus: compare p. 200, Plate XII., Fig. _B_ 4; see also -in the same place the Ascidian, Fig. _A_ 4). - - - Definition of the _forms_ | +Ontogenesis.+ | +Phylogenesis.+ - of the five first stages | The five first stages | The five first stages - of the development of | of the individual | of the phyletic or - the animal body. | development. | historical development. - -------------------------------+------------------------------+------------------------ - | | - _First Stage of Development._ | 1. | 1. - | +Monerula.+ | +Moneron.+ - A simple cytod (a | | - plastid without a kernel.) | Animal egg without a | Most ancient animal - | | kernel (when the egg-kernel | Monera, originating by - | | has disappeared, | spontaneous generation. - | | after being fructified). | | - | | | | | - | | | | | - _Second Stage of Development._ | 2. | 2. - | +Ovulum.+ | +Amoebæ.+ - A simple cell (a | | - plastid containing a | Animal egg with kernel | Animal Amoebæ. - kernel.) | (a simple egg-cell). | | - | | | | | - | | | | | - | | | | | - _Third Stage of Development._ | 3. | 3. - | +Morula.+ | +Synamoeba.+ - A community (an | (_Mulberry form._) | - aggregation of identical | | An aggregation of - simple cells). | Globular heap of homogeneous | Amoebæ. - | | "cleavage spheres." | | - | | | | | - | | | | | - _Fourth Stage of Development._ | 4. | 4. - | +Planula.+ | +Planæa.+ - A solid or bladder-shaped, | (_Ciliated larva_.) | - globular, or oval | | Many-celled primæval - body, _composed of two | Many-celled larva | animal without - kinds of different cells_: | without mouth, composed | mouth, composed of - externally ciliated, | of different cells. | two kinds of different - internally non-ciliated | | | cells. - cells. | | | | - | | | | | - | | | | | - _Fifth Stage of Development._ | 5. | 5. - | +Gastrula.+ | +Gastræa.+ - A globular or oval | (_Larva with mouth._) | - _body with simple intestinal | Many-celled with intestines | Many-celled primæval - cavity and mouth-opening. | and mouth; intestinal | animal with intestine - Body wall composed | wall with two | and mouth; intestinal - of two layers_; an | layers. | wall with two - externally ciliated ectoderm | | layers. (Primary form - (dermal layer), an | | of zoophytes and - internally non-ciliated | | worms.) - entoderm (gastral layer). | | - - -From the ontogenetic occurrence of the Gastrula in the most different -animal classes, from Zoophytes up to Vertebrata, we may, according to -the biogenetic principle, safely draw the conclusion that during the -Laurentian period there existed a common primary form of the six higher -animal tribes, which in all essential points was formed like the -Gastrula, and which we shall call the Gastræa. This Gastræa possessed a -perfectly simple globular or oval body, which enclosed a simple cavity -of like form, namely, the progaster; at one of the poles of the -longitudinal axis the primary intestine opened by a mouth which served -for the reception of nutrition. The body wall (which was also the -intestinal wall) consisted of two layers of cells, the unfringed -entoderm, or intestinal layer, and the fringed ectoderm, or skin-layer; -by the motion of the cilia or fringes of the latter the Gastræa swam -about freely in the Laurentian ocean. Even in those higher animals, in -the ontogenesis of which the original Gastrula form has disappeared, -according to the laws of abbreviated inheritance (vol. i. p. 212), the -composition of the Gastræa body has been transmitted to the phase of -development which directly arises out of the Morula. This phase is an -oval or round disc consisting of two cell-layers or membranes: the outer -cell-layer, the _animal or dermal layer_ (ectoblast), corresponds to the -ectoderm of the Gastræa; out of it develops the external, loose skin -(epidermis), with its glands and appendages, as well as the central -nervous system. The inner cell-layer, the _vegetative or intestinal -layer_ (hypoblast), is originally the entoderm of the Gastræa; out of it -develops the inner membrane (epithelium) of the intestinal canal and its -glands. (Compare my Monograph of the Calcareous Sponges, vol. i. p. 466, -etc.) - -By ontogeny we have already gained five primordial stages of development -of the animal kingdom: (1) the Moneron; (2) the Amoeba; (3) the -Synamoeba; (4) the Planæa; and (5) the Gastræa. The former existence of -these five oldest primary forms, which succeeded one another, and which -must have lived in the Laurentian period, follows as a consequence of -the biogenetic principle; that is to say, from the parallelism and the -mechanico-causal connection of ontogenesis and phylogenesis. (Compare -vol. i. p. 309.) In our genealogical system of the animal kingdom we may -class all these animal forms, long since extinct, and, which on account -of the soft nature of their bodies could leave no fossil remains, among -the tribe of Primæval animals (Protozoa), which also comprises the still -living Infusoria and Gregarinæ. - -The phyletic development of the six higher animal tribes, which are all -derived from the Gastræa, deviated at this point in two directions. In -other words, the _Gastræads_ (as we may call the group of forms -characterized by the Gastræa-type of structure), divided into two -divergent lines or branches; the one branch of Gastræads gave up free -locomotion, adhered to the bottom of the sea, and thus, by adopting an -adhesive mode of life, gave rise to the _Protascus_, the common primary -form of the _Animal-plants_ (Zoophyta). The other branch of the -Gastræads retained free locomotion, did not become adherent and later -on developed into the _Prothelmis_, the common primary form of _Worms_ -(Vermes). (Compare p. 133.) - -This latter tribe (as limited by modern zoology) is of the greatest -interest in the study of genealogy. For among Worms, as we shall see -later, there are, besides very numerous peculiar families, and besides -many independent classes, also very remarkable forms, which may be -considered as _forms of direct transition_ to the four higher animal -tribes. Both comparative anatomy and the ontogeny of these worms enable -us to recognize in them the nearest blood relations of those extinct -animal forms which were the original primary forms of the four higher -animal tribes. Hence these latter, the Molluscs, Star-fishes, -Articulated animals, and Vertebrate animals, do not stand in any close -blood relationship to one another, but have originated independently in -four different places out of the tribe of Worms. - -In this way comparative anatomy and phylogeny lead us to the -_monophyletic pedigree of the animal kingdom_, the outlines of which are -given on p. 133. According to it the seven phyla, or tribes, of the -animal kingdom are of different value in regard to genealogy. The -original primary group of the whole animal kingdom is formed by the -Primæval animals (Protozoa), including the Infusoria and Gastræads. Out -of these latter arose the two tribes of Animal-plants (Zoophyta) and -Worms as diverging branches. Out of four different groups of the Worm -tribe, the four higher tribes of the animal kingdom were developed--the -Star-fishes (Echinoderma) and Insects (Arthropoda) on the one hand, and -the Molluscs (Mollusca) and Vertebrated animals (Vertebrata) on the -other. - -Having thus sketched out the monophyletic pedigree of the animal kingdom -in its most important features, we must now turn to a closer examination -of the historical course of development which the seven tribes of the -animal kingdom, and the classes distinguished in them, have passed -through (p. 132). There is a much larger number of classes in the animal -than in the vegetable kingdom, owing to the simple reason that the -animal body, in consequence of its more varied and perfect vital -activity, could differentiate and develop in very many more different -directions than could the vegetable body. Thus, while we were able to -divide the whole vegetable kingdom into six main classes and nineteen -classes, we have to distinguish, at least, sixteen main classes and -thirty-eight classes in the animal kingdom. These are distributed among -the seven different tribes of the animal kingdom in the way shown in the -Systematic Survey on pages 132 and 133. - -The group of _Primæval animals_ (Protozoa) within the compass which we -here assign to this tribe, comprises the most ancient and the simplest -primary forms of the animal kingdom; for example, the five oldest -phyletic stages of development previously mentioned, and besides these -the Infusoria and Gregarinæ, as well as all those imperfect animal -forms, for which, on account of their simple and indifferent -organization, no place can be found in any of the other six animal -tribes. Most zoologists, in addition to these, include among the -Protozoa a larger or smaller portion of those lowest organisms, which we -mentioned in our neutral kingdom of Protista (in Chapter XVI.). But -these Protista, especially the large division of the Rhizopoda, which -are so rich in forms, cannot be considered as real animals for reasons -previously given. Hence, if we here leave them out of the question, we -may accept two main classes or provinces of real Protozoa, namely, _Egg -animals_ (Ovularia) and _Germ animals_ (Blastularia). To the former -belong the three classes of Archezoa, Gregarinæ, and Infusoria, to the -latter the two classes of Planæads and Gastræads. - -SYSTEMATIC SURVEY - -_Of the 16 Main Classes and 38 Classes of the Animal Kingdom._ - - - ------------------+-----------------------+----------------------+----------------- - _Tribes or Phyla_ | _Main Classes_, | _Classes_ |_Systematic Name_ - _of the_ |_Branches or Clades_ | _of the_ | _of the_ - _Animal Kingdom._ | _of the_ | _Animal Kingdom._ | _Classes._ - | _Animal Kingdom._ | | - ------------------+-----------------------+----------------------+------------------ - - A. { - =Primæval= { I. Egg-animals { 1. Archaic animals 1. Archezoa - =Animals= { _Ovularia_ { 2. Gregarines 2. Gregarinæ - { { 3. Infusoria 3. Infusoria - +Protozoa+ { - {II. Mulberry animals { 4. Planæads 4. Planæadas - { _Blastularia_ { 5. Gastræads 5. Gastræadas - - - B. { - =Animal= { III. Sponges { 6. Sponges 6. Porifera - =Plants= { _Spongiæ_ { - { - +Zoophyta+ { IV. Sea-nettles { 7. Corals 7. Coralla - { _Acalephæ_ { 8. Hood-jellies 8. Hydromedusæ - { { 9. Comb-jellies 9. Ctenophora - - - C. {V. Bloodless worms {10. Planary worms 10. Platyhelminthes - =Worms= { _Acoelomi_ - { {11. Round worms 11. Nemathelminthes - +Vermes+ { VI. Blood-bearing {12. Moss-polyps 12. Bryozoa - { worms {13. Sac-worms 13. Tunicata - { _Coelomati_ {14. Proboscideans 14. Rhynchocoela - { {15. Star-worms 15. Gephyrea - { {16. Wheel animalcules 16. Rotatoria - { {17. Ring-worms 17. Annelida - - - D. {VII. Headless shellfish {18. Lamp-shells 18. Spirobranchia - =Molluscs= { _Acephala_ {19. Mussels 19. Lamellibranchia - { - +Mollusca+ { VIII. Head-bearing {20. Snails 20. Cochlides - { _Eucephala_ {21. Cuttles 21. Cephalopoda - - - E. { IX. Ringed-arms {22. Sea-stars 22. Asterida - =Star-fishes= { _Colobrachia_ {23. Lily-stars 23. Crinoida - { - +Echinoderma+ { X. Armless {24. Sea-urchins 24. Echinida - { _Lipobrachia_ {25. Sea-cucumbers 25. Holothuriæ - - - F. { XI. Gill-breathers {26. Crab-fish 26. Crustacea - =Articulated= { _Carides_ { - =Animals= { - { XII. Tube-breathers {27. Spiders 27. Arachnida - +Arthropoda+ { _Tracheata_ {28. Centipedes 28. Myriopoda - { {29. Flies 29. Insecta - - - { XIII. Skull-less {30. Lancelets 30. Leptocardia - { _Acrania_ { - G. { - =Vertebrate= { XIV. Single-nostriled {31. Lampreys 31. Cyclostoma - =Animals= { _Monorrhina_ { - { - +Vertebrata+ { XV. Amnion-less {32. Fishes 32. Pisces - { _Anamnia_ {33. Mud-fish 33. Dipneusta - { {34. Sea dragons 34. Halisauria - { {35. Amphibians 35. Amphibia - { - { XVI. Amnion-bearing {36. Reptiles 36. Reptilia - { _Amniota_ {37. Birds 37. Aves - { {38. Mammals 38. Mammalia - - ---------------------------------------------------------------- - - +Vertebrata+ - (_Vertebrated animals_) - Craniota - | - +Arthropoda+ | +Mollusca+ - (_Articulated Animals_) | (_Molluscs_) - +Echinoderma+ Tracheata | Eucephala - (_Star-fishes_) | | | - | | | - Lipobrachia Crustacea Acrania | - | Annelida | | Tunicata Acephala - | | | | | Bryozoa | - Colobrachia | | | | | | - | Gephyrea| | Rotatoria \--v---/ \--v---/ - | | | | | | | - | | | | | | | - \---------v-------------------/ \------v-----/ - | | - | +Vermes+ | - | (_Worms_) | - \------------------v-------------------/ - | - | - COELOMATI - (_Worms with a body-cavity_) - | Platyhelminthes - | | - | | - \-----v------/ - +Zoophyta+ | - (_Animal-Plants_) +ACOELOMI+ - Spongiæ Acalephæ (_Worms without body-cavity_) - | | | - | | | - \------v-------/ | - | | - Protascus Prothelmis - | | - | | - \-----------v---------------/ - | - | +Protozoa+ - | (_Primæval animals_) - | - |/-------------^-------------\ - +GASTRÆA+ - | - | Infusoria - | | - +PLANÆA+ | Gregarinæ - | | | - | | | - +SYNAMOEBÆ+ \----v---/ - | | - | | - \---------v--------/ - +AMOEBÆ+ - | - +MONERA+ - - -The first province of the Protozoa consists of the _Egg animals_ -(Ovularia); we include among them all _single-celled animals_, all -animals whose body, in the fully developed state, possesses the -form-value of a _simple plastid_ (of a cytod or a cell), also those -simple animal forms whose body consists of an aggregation of several -cells perfectly similar one to another. - -The _Archaic animals_ (Archezoa) form the first class in the series of -Egg animals. It contains only the most simple and most ancient primary -forms of the animal kingdom, whose former existence we have proved by -means of the fundamental law of biogenesis; they are, (1) Animal Monera; -(2) Animal Amoebæ; (3) Animal Synamoebæ. We may, if we choose, include -among them a portion of the still living Monera and Amoebæ, but another -portion (according to the discussion in Chapter XVI.) must on account of -their neutral nature be considered as Protista, and a third portion, on -account of their vegetable nature, must be considered as plants. - -A second class of the egg animals consists of the _Gregarines_ -(Gregarinæ), which live as parasites in the intestines and body-cavities -of many animals. Some of these Gregarines are perfectly simple cells -like the Amoebæ; some form chains of two or three identical cells, one -lying behind the other. They differ from the naked Amoebæ by possessing -a thick, simple membrane, which surrounds their cell-body; they can be -considered as animal Amoebæ which have adopted a parasitical mode of -life, and in consequence have surrounded themselves with a secreted -covering. - -As a third class of egg animals, we adopt the real _Infusoria_ -(Infusoria), embracing those forms to which modern zoology almost -universally limits this class of animals. The principal portion of them -consists of the small _ciliated Infusoria_ (Ciliata), which inhabit all -the fresh and salt waters of the earth in great numbers, and which swim -about by means of a delicate garb of vibratile fringes. A second and -smaller division consists of the adherent _sucking Infusoria_ (Acinetæ), -which take their food by means of fine sucking-tubes. Although during -the last thirty years numerous and very careful investigations have been -made on these small animalcules,--which are mostly invisible to the -naked eye,--still we are even now not very sure about their development -and form-value. We do not even yet know whether the Infusoria are single -or many-celled; but as no investigator has as yet proved their body to -be a combination of cells, we are, in the mean time, justified in -considering them as single-celled, like the Gregarines and the Amoebæ. - -The second main class of primæval animals consists of the _Germ animals_ -(Blastularia). This name we give to those extinct Protozoa which -correspond to the two ontogenetic embryonic forms of the six higher -animal tribes, namely, the Planula and the Gastrula. The body of these -Blastularia, in a perfectly developed state, was composed of many cells, -and these cells moreover differentiated--in two ways at least--into an -external (animal or dermal) and an internal (vegetative or gastral) -mass. Whether there still exist representatives of this group is -uncertain. Their former existence is undoubtedly proved by the two -exceedingly important ontogenetic animal forms which we have already -described as Planula and Gastrula, and which still occur as a transient -stage of development in the ontogeny of the most different tribes of -animals. Corresponding to these, we may, according to the biogenetic -principle, assume the former existence of two distinct classes of -Blastularia, namely, the _Planæada_ and _Gastræada_. The type of the -_Planæada_ is the _Planæa_--long since extinct--but whose historical -portrait is still presented to us at the present day in the widely -distributed _ciliated larva_ (Planula). (Frontispiece, Fig. 4.) The type -of the _Gastræada_ is the _Gastræa_, of whose original nature the -mouth-and-stomach larva (Gastrula), which recurs in the most different -animal tribes, still gives a faithful representation. (Frontispiece Fig. -5, 6.) Out of the Gastræa, as we have previously mentioned, there were -at one time developed two different primary forms, the Protascus and -Prothelmis; the former must be looked upon as the primary form of the -Zoophytes, the latter as the primary form of Worms. (Compare the -enunciation of this hypothesis in my Monograph of the Calcareous -Sponges, vol i. p. 464.) - -The _Animal-plants_ (Zoophyta, or Coelenterata) which constitute the -second tribe of the animal kingdom, rise considerably above the -primitive animals in the characters of their whole organisation, while -they remain far below most of the higher animals. For in the latter -(with the exception only of the lowest forms) the four distinct -functions of nutrition--namely, digestion, circulation of the blood, -respiration, and excretion--are universally accomplished by four -perfectly different systems of organs: by the intestines, the vascular -system, the organs of respiration, and the urinary apparatus. In -Zoophytes, however, these functions and their organs are not yet -separate, and are all performed by a single system of alimentary canals, -by the so-called gastro-vascular system, or the coelenteric apparatus of -the intestinal cavity. The mouth, which is also the anus, leads into a -stomach, into which the other cavities of the body also open. In -Zoophytes the body-cavity, or "coeloma," possessed by the four higher -tribes of animals is still completely wanting, likewise the vascular -system and blood, as also the organs of respiration, etc. - -All Zoophytes live in water; most of them in the sea, only a very few in -fresh water, such as fresh-water sponges (Spongilla) and some primæval -polyps (Hydra, Cordylophora). A specimen of the pretty flower-like forms -which are met with in great variety among Zoophytes is given on Plate -VII. (Compare its explanation in the Appendix.) - -The tribe of animal-plants, or Zoophytes, is divided into two distinct -provinces, the _Sponges_, or _Spongiæ_, and the _Sea-nettles_, or -_Acalephæ_ (p. 144). The latter are much richer in forms and more highly -organized than the former. In all Sponges the entire body, as well as -the individual organs, are differentiated and perfected to a much less -extent than in Sea-nettles. All Sponges lack the characteristic -_nettle-organs_ which all Sea-nettles possess. - -The common primary form of all Zoophytes must be looked for in the -_Protascus_, an animal form long since extinct, but whose existence is -proved according to the biogenetic principle by the Ascula. This Ascula -is an ontogenetical development form which, in Sponges as well as in -Sea-nettles, proceeds from the Gastrula. (Compare the Ascula of the -calcareous sponge on the Frontispiece, Fig. 7, 8.) For after the -Gastrula of zoophytes has for a time swum about in the water it sinks to -the bottom, and there adheres by that pole of its axis which is opposite -to the opening of the mouth. The external cells of the ectoderm draw in -their vibrating, ciliary hairs, whereas, on the contrary, the inner -cells of the entoderm begin to form them. Thus the Ascula, as we call -this changed form of larva, is a simple sack, its cavity (the cavity of -the stomach or intestine) opening by a mouth externally, at the upper -pole of the longitudinal axis (opposite the basal point of fixture). The -entire body is here in a certain sense a mere stomach or intestinal -canal, as in the case of the Gastrula. The wall of the sack, which is -both body wall and intestinal wall, consists of two layers or coats of -cells, a fringed _entoderm_, or gastral layer (corresponding with the -inner or vegetative germ-layer of the higher animals), and an unfringed -exoderm or dermal layer (corresponding with the external or animal -germ-layer of the higher animals). The original _Protascus_, a true -likeness of which is still furnished by the Ascula, probably formed -egg-cells and sperm-cells out of its gastral layer. - -The Protascads--as we will call the most ancient group of vegetable -animals, represented by the Protascus-type--divided into two lines or -branches, the Spongiæ and the Sea-nettles, or Acalephæ. I have shown in -my Monograph of the Calcareous Sponges (vol. i. p. 485) how closely -these two main classes of Zoophytes are related, and how they must both -be derived, as two diverging forms, from the Protascus-form. The primary -form of Spongiæ, which I have there called Archispongia, arose out of -the Protascus by the formation of pores through its body-wall; the -primary form of Sea-nettles, which I there called Archydra, developed -out of the Protascus by the formation of nettle-organs, as also by the -formation of feelers or tentacles. - -The main-class or branch of the _Sponges_, _Spongiæ_, or _Porifera_, -lives in the sea, with the single exception of the green fresh-water -Sponge (Spongilla). These animals were long considered as plants, later -as Protista; in most Manuals they are still classed among the primæval -animals, or Protozoa. But since I have demonstrated their development -out of the Gastrula, and the construction of their bodies of two -cellular germ-layers (as in all higher animals), their close -relationship to Sea-nettles, and especially to the Hydrapolyps, seems -finally to be established. The _Olynthus_ especially, which I consider -as the common primary form of calcareous sponges, has thrown a complete -and unmistakable light upon this point. - -The numerous forms comprised in the class of Spongiæ have as yet been -but little examined; they may be divided into three legions and eight -orders. The first legion consists of the soft, gelatinous _Mucous -Sponges_ (Myxospongiæ), which are characterized by the absence of any -hard skeleton. Among them are, on the one hand, the long-since-extinct -primary forms of the whole class, the type of which I consider to be the -Archispongia; on the other hand there are the still living, gelatinous -sponges, of which the _Halisarca_ is best known. We can obtain a notion -of the Archispongia, the most ancient primæval sponge, if we imagine the -Olynthus (see Frontispiece), to be deprived of its radiating calcareous -spiculæ. - -The second legion of Spongiæ contains the _Fibrous Sponges_ -(Fibrospongiæ), the soft body of which is supported by a firm, fibrous -skeleton. This fibrous skeleton often consists merely of so-called -"horny fibres," formed of a very elastic, not readily destructible, -organic substance. This is the case for instance in our common bathing -Sponge (Euspongia officinalis), the purified skeleton of which we use -every morning when washing. Blended with the horny, fibrous skeleton of -many of these Sponges, there are numerous flinty spicula; this is the -case for example with the fresh-water Sponge (Spongilla). In others the -whole skeleton consists of only calcareous or silicious spicula which -are frequently interwoven into an extremely beautiful lattice-work, as -in the celebrated Venus' Flower Basket (Euplectella). Three orders of -fibrous sponges may be distinguished according to the different -formation of the spicula, namely, Chalynthina, Geodina, and -Hexactinella. The natural history of the fibrous sponges is of especial -interest to the Theory of Descent, as was first shown by Oscar Schmidt, -the greatest authority on this group of animals. In no other group, -perhaps, can the unlimited pliability of the specific form, and its -relation to Adaptation and Inheritance, be so clearly followed step by -step; perhaps in no other group is the species so difficult to limit and -define. - -[Illustration: Pl. VII. - -E. Haeckel del. Lagesse sc.] - -This proposition, which applies to the great legion of the Fibrous -Sponges, applies in a still higher degree to the smaller but exceedingly -interesting legion of the calcareous sponges (Calcispongiæ), on which in -1872, after five years' careful examination, I published a comprehensive -Monograph. The sixty plates of figures accompanying this Monograph -explain the extreme pliability of these small sponges "good species" of -which, in fact, cannot be spoken of in the usual systematic sense. We -find among them only varying series of forms, which do not even -completely transmit their specific form to their nearest descendants, -but by adaptation to subordinate, external conditions of existence, -perpetually change. It frequently occurs here, that there arise out of -one and the same stock different form-species, which according to the -usual system would belong to several quite distinct genera; this is the -case, for instance, with the remarkable Ascometra (Frontispiece, Fig. -10.) The entire external bodily form is much more pliable and protean in -Calcareous Sponges than in the silicious sponges, which are -characterized by possessing silicious spicula, forming a beautiful -skeleton. Through the study of the comparative anatomy and ontogeny of -calcareous sponges, we can recognise, with the greatest certainty, the -common primary form of the whole group, namely, the sack-shaped -_Olynthus_, whose development is represented in the Frontispiece -(compare its explanation in the Appendix). Out of the Olynthus (Fig. 9 -on the Frontispiece), the order of the Ascones was the first to develop, -out of which, at a later period, the two other orders of Calcareous -Sponges, the _Leucones_ and _Sycones_, arose as diverging branches. -Within these orders, the descent of the individual forms can again be -followed step by step. Thus the Calcareous Sponges in every respect -confirm the proposition which I have elsewhere maintained: that "the -natural history of sponges forms a connected and striking argument in -favour of Darwin." - -The second main class or branch in the tribe of Zoophytes is formed by -the Sea-nettles (Acalephæ, or Cnidæ). This interesting group of animals, -so rich in forms, is composed of three different classes, namely, the -Hood-jellies (Hydromedusæ), the Comb-jellies (Ctenophora), and the -Corals (Coralla). The hypothetical, extinct Archydra must be looked upon -as the common primary form of the whole group; it has left two near -relations in the still living fresh-water polyps (Hydra and -Cordylophora). The Archydra was very closely related to the simplest -forms of Spongiæ (Archispongia and Olynthus), and probably differed from -them only by possessing nettle organs, and by the absence of cutaneous -pores. Out of the Archydra there first developed the different Hydroid -polyps, some of which became the primary forms of Corals, others the -primary forms of Hydromedusæ. The Ctenophora developed later out of a -branch of the latter. - -The Sea-nettles differ from the Spongiæ (with which they agree in the -characteristic formation of the system of the alimentary canal) -principally by the constant possession of nettle organs. These are small -bladders filled with poison, large numbers--generally millions--of which -are dispersed over the skin of the sea nettles, and which burst and -empty their contents when touched. Small animals are killed by this; in -larger animals this nettle poison causes a slight inflammation of the -skin, just as does the poison of our common nettles. Any one who has -often bathed in the sea, will probably have at times come in contact -with large Hood-jellies (Jelly-fish), and become acquainted with the -unpleasant burning feeling which their nettle organs can produce. The -poison in the splendid blue Jelly-fish, Physalia, or Portuguese -Man-of-war, acts so powerfully that it may lead to the death of a human -being. - -The class of Corals (Coralla) lives exclusively in the sea, and is more -especially represented in the warm seas by an abundance of beautiful and -highly-coloured forms like flowers. Hence they are also called -_Flower-animals_ (Anthozoa). Most of them are attached to the bottom of -the sea, and contain an internal calcareous skeleton. Many of them by -continued growth produce such immense stocks that their calcareous -skeletons have formed the foundation of whole islands, as is the case -with the celebrated coral reefs and atolls of the South Seas, the -remarkable forms of which were first explained by Darwin.(13) In corals -the counterparts, or antimera--that is, the corresponding divisions of -the body which radiate from and surround the central main axis of the -body--exist sometimes to the number of four, sometimes to the number of -six or eight. According to this we distinguish three legions, the -Fourfold (Tetracoralla), Sixfold (Hexacoralla), and Eightfold corals -(Octocoralla). The fourfold corals form the common primary group of the -class, out of which the sixfold and eightfold have developed as two -diverging branches. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes and 30 Orders of the Animal Plants, or Zoophytes._ - - ----------------+--------------------+--------------------+--------------- - _Class of the_ | _Legions of the_ | _Orders of the_ | _A Genus Name_ - _Zoophytes._ | _Zoophytes._ | _Zoophytes._ | _as example._ - ----------------+--------------------+--------------------+--------------- - I. { I. Myxospongiæ { 1. Archispongina | Archispongia - { _Mucous Sponges_ { 2. Halisarcina | Halisarca - =Sponges= { | - { II. Fibrospongiæ { 3. Chalynthina | Spongilla - +Spongiæ+ {_Fibrous Sponges_ { 4. Geodina | Ancorina - or { { 5. Hexactinella | Euplectella - +Porifera+ { | - { III. Calcispongiæ { 6. Ascones | Olynthus - {_Calcareous Sponges_ { 7. Leucones | Dyssycus - { { 8. Sycones | Sycurus - | - | - II. { IV. Tetracoralla { 9. Rugosa | Cyathophyllum - {_Fourfold Corals_ { 10. Paranemeta | Cereanthus - =Corals= { | - { V. Hexacoralla { 11. Cauliculata | Antipathes - +Coralla+ {_Sixfold Corals_ { 12. Madreporaria | Astræa - or { { 13. Halirhoda | Actinia - +Anthozoa+ { | - { VI. Octocoralla { 14. Alcyonida | Lobularia - {_Eightfold Corals_ { 15. Gorgonida | Isis - { { 16. Pennatulida | Veretillum - | - | - III. { VII. Archydræ } 17. Hydraria | Hydra - {_Primæval Polyps_ } | - =Jelly-polyps= { | - { VIII. Leptomedusæ { 18. Vesiculata | Sertularia - +Hydromedusæ+ {_Soft Jelly-fish_ { 19. Ocellata | Tubularia - { { 20. Siphonophora | Physophora - or { | - { IX. Trachymedusæ { 21. Marsiporchida| Trachynema - =Hood-jellies= { _Hard Jelly-fish_ { 22. Phyllorchida | Geryonia - { { 23. Elasmorchida | Charybdæ - +Medusa+ { | - { X. Calycozoa } 24. Podactinaria | Lucernaria - { _Stalked Jellies_ } | - { | - { XI. Discomedusæ { 25. Semæostomeæ | Aurelia - { _Disc-jellies_ { 26. Rhizostomeæ | Crambessa - | - | - IV. { XII. Eurystoma } 27. Beroida | Beroe - { _Wide-mouthed_ } | - =Comb-jellies= { | - { XIII. Stenostoma { 28. Saccata | Cydippe - +Ctenophora+ { _Narrow-mouthed_ { 29. Lobata | Eucharis - { { 30. Tæniata | Cestum - - ---------------------------------------------------------------- - - Ctenophora Hydromedusæ - Tæniata Lobata Rhizostomeæ - | | | - | | | - \---v----/ Semæostomeæ - Saccata DISCOMEDUSÆ - STENOSTOMA | - | Trachymedusæ | Siphonophora - | | | | - | | Lucernaria | | - EURYSTOMA> | Calycozoa | | - | | | | | - | | | | | - \-------------------------v----------------/ - LEPTOMEDUSÆ - Coralla | - Octocoralla | - Hexacoralla | | - | | | - | | | - \----v----/ | - Tetracoralla | - Spongiæ | | - Fibrospongiæ Calcispongiæ | | - Chalynthina Leucones Sycones| | - | | | | | - | | | | | - | | | | | - Hexactinella|Geodina Dyssycus Sycurus | Hydroida - | | | | | | | Cordylophora - | | | | | | | | Hydra - \------v---/ \-----v--/ | | | | - | Ascones | | | | - | Myxospongia | | \-----v-------/ - | Halisarcina | | HYDROIDA - | | | Procorallum | - | | | | | - CHALYNTHUS | OLYNTHUS | | - | | | \-----v--------/ - \------v----------/ Hydroida - Archispongiæ | - | | - | Archydra - | | - \--------------v--------/ - Protascus - | - Gastræa - -The second class of Sea-nettles is formed by the _Hood-jellies_ (Medusæ) -or _Polyp-jellies_ (Hydromedusæ). While most corals form stocks like -plants, and are attached to the bottom of the sea, the Hood-jellies -generally swim about freely in the form of gelatinous bells. There are, -however, numbers of them, especially the lower forms, which adhere to -the bottom of the sea, and resemble pretty little trees. The lowest and -simplest members of this class are the little fresh-water polyps (Hydra -and Cordylophora). We may look upon them as but little changed -descendants of those _Primæval polyps_ (Archydræ), from which, during -the primordial period, the whole division of the Sea-nettles originated. -Scarcely distinguishable from the Hydra are the adherent Hydroid polyps -(Campanularia, Tubularia), which produce freely swimming medusæ by -budding, and out of the eggs of these there again arise adherent polyps. -These freely swimming Hood-jellies are mostly of the form of a mushroom, -or of an umbrella, from the rim of which many long and delicate -tentacles hang. They are among the most beautiful and most interesting -inhabitants of the sea. The remarkable history of their lives, and -especially the complicated alternation of generation of polyps and -medusæ, are among the strongest proofs of the truth of the theory of -descent. For just as Medusæ still daily arise out of the Hydroids, did -the freely swimming medusa-form originally proceed, phylogenetically, -out of the adherent polyp-form. Equally important for the theory of -descent is the remarkable _division of labour_ of the individuals, which -among some of them is developed to an astonishingly high degree, more -especially in the splendid _Siphonophora_.(37) (Plate VII. Fig. 13.) - -The third class of Sea-nettles--the peculiar division of Comb-jellies -(Ctenophora), probably developed out of a branch of the Hood-jellies. -The Ctenophora, which are also called Ribbed-jellies, possess a body of -the form of a cucumber, which, like the body of most Hood-jellies, is as -clear and transparent as crystal or cut glass. Comb or Ribbed-jellies -are characterized by their peculiar organs of motion, namely, by eight -rows of paddling, ciliated leaflets, which run in the form of eight ribs -from one end of the longitudinal axis (from the mouth) to the opposite -end. Those with narrow mouths (Stenostoma) probably developed later out -of those with wide mouths (Eurystoma). (Compare Plate VII. Fig. 16.) - -The third tribe of the animal kingdom, the phylum of _Worms_ or -worm-like animals (Vermes, or Helminthes), contains a number of -diverging branches. Some of these numerous branches have developed into -well-marked and perfectly independent classes of Worms, but others -changed long since into the original, radical forms of the four higher -tribes of animals. Each of these four higher tribes (and likewise the -tribe of Zoophytes) we may picture to ourselves in the form of a lofty -tree, whose branches represent the different classes, orders, families, -etc. The phylum of Worms, on the other hand, we have to conceive as a -low bush or shrub, out of whose root a mass of independent branches -shoot up in different directions. From this densely branched shrub, most -of the branches of which are dead, there rise four high stems with many -branches. These are the four lofty trees just mentioned as representing -the higher phyla--the Echinoderma, Articulata, Mollusca, and Vertebrata. -These four stems are directly connected with one another at the root -only, to wit, by the common primary group of the Worm tribe. - -The extraordinary difficulties which the systematic arrangement of Worms -presents, for this reason merely, are still more increased by the fact -that we do not possess any fossil remains of them. Most of the Worms had -and still have such soft bodies that they could not leave any -characteristic traces in the neptunic strata of the earth. Hence in this -case again we are entirely confined to the records of creation furnished -by ontogeny and comparative anatomy. In making then the exceedingly -difficult attempt to throw a few hypothetical rays of light upon the -obscurity of the pedigree of Worms, I must therefore expressly remark -that this sketch, like all similar attempts possesses only a provisional -value. - -The numerous classes distinguished in the tribe of Worms, and which -almost every zoologist groups and defines according to his own personal -views, are, in the first place, divided into two essentially different -groups or branches, which in my Monograph of the Calcareous Sponges I -have termed Acoelomi and Coelomati. For all the lower Worms which are -comprised in the class of Flat-worms (Platyhelminthes), (the -Gliding-worms, Sucker-worms, Tape-worms), differ very strikingly from -other Worms, in the fact that they possess neither blood nor body-cavity -(no coelome); they are, therefore, called Acoelomi. The true cavity, or -coelome, is completely absent in them as in all the Zoophytes; in this -important respect the two groups are directly allied. But _all other -Worms_ (like the four higher tribes of animals) possess a genuine -body-cavity and a vascular system connected with it, which is filled -with blood; hence we class them together as _Coelomati_. - -The main division of _Bloodless Worms_ (Acoelomi) contains, according to -our phylogenetic views, besides the still living Flat-worms, the unknown -and extinct primary forms of the whole tribe of Worms, which we shall -call the Primæval Worms (Archelminthes). The type of these _Primæval -Worms_, the ancient Prothelmis, may be directly derived from the Gastræa -(p. 133). Even at present the Gastrula-form--the faithful historical -portrait of the Gastræa--recurs in the ontogenesis of the most different -kinds of worms as a transient larva-form. The ciliated Gliding-worms -(Turbellaria), the primary group of the present Planary or Flat-worms -(Platyhelminthes), are the nearest akin to the Primæval Worms. The -parasitical Sucker-worms (Trematoda) arose out of the Gliding-worms, -which live freely in water, by adaptation to a parasitical mode of life; -and out of them later on--by an increasing parasitism--arose the -Tape-worms (Cestoda). - -Out of a branch of the Acoelomi arose the second main division of the -Worm tribe, the Worms with blood and body-cavity (Coelomati): of these -there are seven different classes. - -The Pedigree on p. 151 shows how the obscure phylogeny of the seven -classes of Coelomati may be supposed to stand. We shall, however, -mention these classes here quite briefly, as their relationships and -derivation are, at present, still very complicated and obscure. More -numerous and more accurate investigations of the ontogeny of the -different Coelomati will at some future time throw light upon their -phylogenesis. - -The Round Worms (Nemathelminthes) which we mention as the first class of -the Coelomati, and which are characterized by their cylindrical form, -consist principally of parasitical Worms which live in the interior of -other animals. Of human parasites, the celebrated Trichinæ, the -Maw-worms, Whip-worms, etc., for example, belong to them. The Star-worms -(Gephyrea) which live exclusively in the sea are allied to round worms, -and the comprehensive class of Ring-worms (Annelida) are allied to the -former. To the Ring-worms, whose long body is composed of a number of -segments, all alike in structure, belong the Leeches (Hirudinea), -Earth-worms (Lumbricina), and all the marine bristle-footed Worms -(Chætopoda). Nearly akin to them are the Snout-worms (Rhynchocoela), and -the small microscopic Wheel-worms (Rotifera). The unknown, extinct, -primary forms of the tribe of Sea-stars (Echinoderma), and of the tribe -of the articulated animals (Arthropoda), were nearest akin to the -Ring-worms. On the other hand, we must probably look for the primary -forms of the great tribe of Molluscs in extinct Worms, which were very -closely related to the Moss-polyps (Bryozoa) of the present day; and for -the primary forms of the Vertebrata in the unknown Coelomati, whose -nearest kin of the present day are the Sea-sacs, especially the Ascidia. - -SYSTEMATIC SURVEY - -_Of the 8 Classes and 22 Orders of the Worm Tribe._ - -(Compare Gen. Morph. ii. Plate V. pp. 75-77.) - - - ------------------+-------------------------+----------------------+------------------ - _Classes_ | | _Systematic_ | - _of the_ | _Orders of the_ | _Name of the_ | _Name of a Genus_ - _Worm Tribe._ | _Worm Tribe._ | _Orders of Worms_. | _as example._ - | | | - ------------------+-------------------------+----------------------+------------------ - 1. _Flat_ { 1. Primæval worms | 1. Archelminthes | Prothelmis - _Worms_ { 2. Gliding-worms | 2. Turbellaria | Planaria - Platyhel- { 3. Sucker-worms | 3. Trematoda | Distoma - minthes { 4. Tape-worms | 4. Cestoda | Tænia - | | - 2. _Round_ { 5. Arrow-worms | 5. Chætognatha | Sagitta - _Worms_ { 6. Thread-worms | 6. Nematoda | Trichina - Nemathel- { 7. Hook-headed | 7. Acanthocephala | Echinorhynchus - minthes { worms | | - | | - 3. _Moss_ } 8. Horse-shoe-lipped | 8. Lophopoda | Alcyonella - _Polyps_ } 9. Circle-lipped | 9. Stelmopoda | Retepora - Bryozoa } | | - | | - 4. _Sea-sacs_ { 10. Sea-squirts | 10. Ascidia | Phallusia - Tunicata { 11. Sea-barrels | 11. Thaliacea | Salpa - | | - 5. _Proboscideans_ } 12. Tongue-worms | 12. Enteropneusta | Balanoglossus - Rhynchocoela } 13. Cord-worms | 13. Nemertina | Borlasia - | | - { 14. Star-worms without | 14. Sipunculida | Sipunculus - 6. _Star-Worms_ { bristles | | - Gephyrea { 15. Star-worms with | 15. Echiurida | Echiurus - { bristles | | - | | - 7. _Wheel_ } | | - _Animalcule_ } 16. Wheel-worms | 16. Rotatoria | Hydatina - Rotifera } | | - | | - { 17. Bear-worms | 17. Arctisca | Macrobiotus - { 18. Worms with claws | 18. Onychophora | Peripatus - 8. _Ring_ { 19. Leeches | 19. Hirudinea | Hirudo - _Worms_ { 20. Land-worms | 20. Drilomorpha | Lumbricus - Annelida { 21. Mailed worms | 21. Phracthelminthes | Crossopodia - { 22. Bristle-footed | 22. Chætopoda | Aphrodite - { worms | | - - ---------------------------------------------------------------- - - Chætopoda - | Drilomorpha - | | - \-------v-------/ - | - Phracthelminthes | - | | - Echiurida| | Hirudinea - Sipunculida | | | | - | | | | | Onychophora - \----v---/ | | | | - +Gephyrea+ | | | | Arctisca - | | | | | | - | | | | \--v---/ - Chætognatha | \--v-----/ | | - | | | \-----v-----/ - Nematoda | | | | - | | | \---------v---------/ - \--v--/ | +Annelida+ - | Acantho- | | - | cephala | Stelmopoda | - | | | | | Enteropneusta - \--v--/ | | | | - +Nemathelminthes+ | Lophopoda | Ascidia | - | | +Bryozoa+ | Thalicea | | Nemertina - | | | | | | | | - | | | +Rotifera+ | | | | | - | | | | | | | \---v-/ - | | | | | | | +Rhynchocoela+ - | | | | | \--v---/ | - | | | \----v---/ +Tunicata+ | - | | | | | | - \-----------------------v-----------------------------/ - +Coelomati+ (_worms with body-cavity_) - | - Cestoda | - | | - | | - Trematoda | - | | - | | - Turbellaria | - +Platyhelminthes+ | - | | - | | - \-------v---------/ - +Acoelomi+ (_worms without body-cavity_) - | - | - Archelminthes - +Prothelmis+ - | - | - +Gastræa+ - - -The class of Sea-sacs (Tunicata) is one of the most remarkable among -Worms. They all live in the ocean, where some of the Ascidiæ adhere to -the bottom, while others (the sea-barrels, or Thaliacea) swim about -freely. In all of them the non-jointed body has the form of a simple -barrel-shaped sack, which is surrounded by a thick cartilaginous mantle. -This mantle consists of the same non-nitrogenous combination of carbon, -which, under the name of cellulose, plays an important part in the -Vegetable Kingdom, and forms the largest portion of vegetable cellular -membranes, and consequently also the greater part of wood. The -barrel-shaped body generally possesses no external appendages. No one -would recognise in them a trace of relationship to the highly -differentiated vertebrate animals. And yet this can no longer be -doubted, since Kowalewsky's investigations, which in the year 1867 -suddenly threw an exceedingly surprising and unmistakable light upon -them. From these investigations it has become clear that the individual -development of the adherent simple Ascidian Phallusia agrees in most -points with that of the lowest vertebrate animal, namely, the Lancelet -(Amphioxus lanceolatus). The early stages of the Ascidia possess the -beginnings of the _spinal marrow_ and the _spinal column_ (chorda -dorsalis) lying beneath it, which are the two most essential and most -characteristic organs of the vertebrate animal. Accordingly, of all -invertebrate animals known to us, the _Tunicates are without doubt the -nearest blood relations of the Vertebrates_, and must be considered as -the nearest relations of those Worms out of which the vertebrate tribe -has developed. (Compare Plates XII. and XIII.) - -While thus different branches of the Coelomatous group of the Worms -furnish us with several genealogical links leading to the four higher -tribes of animals, and give us important phylogenetic indications of -their origin, the lower group of Acoelomi, on the other hand, show close -relationships to the Zoophytes, and to the Primæval animals. The great -phylogenetic interest of the Worm tribe rests upon this peculiar -intermediate position. - - - - -CHAPTER XIX. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -II. MOLLUSCA, STAR-FISHES, AND ARTICULATED ANIMALS. - - - Tribe of Molluscs.--Four Classes of Molluscs: Lamp-shells - (Spirobranchia); Mussels (Lamellibranchia); Snails (Cochlides); - Cuttle-fish (Cephalopoda).--Tribe of Star-fishes, or - Echinoderma.--Their Derivation from Ringed Worms (Mailed Worms, - or Phracthelminthes).--The Alternation of Generation in the - Echinoderma.--Four Classes of Star-fish: Sea-stars (Asteridea); - Sea-lilies (Crinoidea); Sea-urchins (Echinidea); Sea-cucumbers - (Holothuridea).--Tribe of Articulated Animals, or - Arthropoda.--Four Classes of Articulated Animals: Branchiata, or - Crustacea, breathing through gills; Jointed Crabs; Mailed - Crabs; Articulata Tracheata, breathing through Air - Tubes.--Spiders (Long Spiders, Round - Spiders).--Myriopods.--Insects.--Chewing and Sucking - Insects.--Pedigree and History of the Eight Orders of Insects. - - -The great natural main groups of the animal kingdom, which we have -distinguished as TRIBES, or PHYLA ("types" according to Bär and Cuvier), -are not all of equal systematic importance for our phylogeny or history -of the pedigree of the living world. They can neither be classed in a -single series of stages, one above another, nor be considered as -entirely independent stems, nor as equal branches of a single -family-tree. It seems rather (as we saw in the last chapter) that the -tribe of Protozoa, the so-called primæval animals, is the common radical -group of the whole animal kingdom. Out of the Gastræada--which we class -among the Protozoa--the Zoophytes and the Worms have developed, as two -diverging branches. We must now in turn look upon the varied and -much-branching tribe of Worms as the common primary group, out of which -(from perfectly distinct branches) arose the remaining tribes, the four -higher phyla of the animal kingdom. (Compare the Pedigree, p. 133.) - -Let us now take a genealogical look at these four higher tribes of -animals, and try whether we cannot make out the most important outlines -of their pedigree. Even should this attempt prove defective and -imperfect, we shall at all events have made a beginning, and paved the -road for subsequent and more satisfactory attempts. - -It does not matter in what succession we take up the examination of the -four higher tribes. For these four phyla have no close relationship -whatever among one another, but have grown out from entirely distinct -branches of the group of Worms (p. 133). We may consider the tribe of -Molluscs as the most imperfect and the lowest in point of morphological -development. We nowhere meet among them with the characteristic -articulation or segmented formation of the body, which distinguishes -even the Ring-worms, and which in the other three higher tribes--the -Echinoderma, Articulata, and Vertebrata--is most essentially connected -with the high development of their forms, their differentiation, and -perfection. The body in all Molluscs--in mussels, snails, etc.--is a -simple non-jointed sack, in the cavity of which lie the intestines. The -nervous system consists not of a cord but of several distinct (generally -three) pairs of knots loosely connected with one another. For these and -many other anatomical reasons, I consider the tribe of Molluscs (in -spite of the high physiological development of its most perfect forms) -to be morphologically the lowest among the four higher tribes of -animals. - -Whilst, for reasons already given, we exclude the Moss-polyps, and -Tunicates--which have hitherto been generally classed with the tribe of -Molluscs--we retain as genuine Molluscs the following four classes: -Lamp-shells, Mussels, Snails, and Cuttles. The two lower classes of -Molluscs, the Lamp-shells and Mussels, possess neither head nor teeth, -and they can therefore be comprised under one main class, or branch, as -headless animals (Acephala), or toothless animals (Anodontoda). This -branch is also frequently called that of the clam-shells (Conchifera, or -Bivalvia), because all its members possess a two-valved calcareous -shell. In contrast to these the two higher classes of Molluscs, the -snails and cuttles, may be represented as a second branch with the name -of Head-bearers (Cephalophora), or Tooth-bearers (Odontophora), because -both head and teeth are developed in them. - -The soft, sack-shaped body in most Molluscs is protected by a calcareous -shell or house, which in the Acephala (lamp-shells and mussels) consists -of two valves, but in the Cephalophora (snails and cuttles) is generally -a spiral tube (the so-called snail's house). Although these hard -skeletons are found in large quantities in a petrified state in all the -neptunic strata, yet they tell us but little of the historical -development of the tribe, which must have taken place for the most part -in the primordial period. Even in the Silurian strata we find fossil -remains of all the four classes of Molluscs, one beside the other, and -this, conjointly with much other evidence, distinctly proves that the -tribe of Molluscs had then obtained a strong development, when the -higher tribes, especially the Articulates and Vertebrates, had scarcely -got beyond the beginning of their historical development. In subsequent -periods, especially in the primary and secondary periods, these higher -tribes increased in importance more and more at the expense of Molluscs -and Worms, which were no match for them in the struggle for life, and -accordingly decreased in number. The still living Molluscs and Worms -must be considered as only a proportionately small remnant of the vast -molluscan fauna, which greatly predominated in the primordial and -primary periods over the other tribes. (Compare Plate VI. and -explanation in the Appendix.) - -No tribe of animals shows more distinctly than do the Molluscs, how very -different the value of fossils is in geology and in phylogeny. In -geology the different species of the fossil shells of Molluscs are of -the greatest importance because they serve as excellent marks whereby to -characterize the different groups of strata, and to fix their relative -ages. As far as relates to the genealogy of Molluscs, however, they are -of very little value, because, on the one hand, the shells are parts of -quite subordinate morphological importance, and because the actual -development of the tribe belongs to the earlier primordial period, from -which no distinct fossils have been preserved. If therefore we wish to -construct the pedigree of Molluscs, we are mainly dependent upon the -records of ontogeny and comparative anatomy from which we obtain -something like the following result. (Gen. Morph. ii. Plate VI. pp. -102-116.) - -The lowest stage of the four classes of genuine Molluscs known to us, is -occupied by the Lamp-shells or Spiral-gills (Spirobranchia), frequently -but inappropriately called Arm-footers (Brachiopoda), which have become -attached to the bottom of the sea. There now exist but few forms of -this class; for instance, some species of Lingula, Terebratula, and -others akin to them, which are but feeble remnants of the great variety -of forms which represented the Lamp-shells in earlier periods of the -earth's history. In the Silurian period they constituted the principal -portion of the whole Mollusc tribe. From the agreement which, in many -respects, their early stage of development presents with the Moss -animals, it has been concluded that they have developed out of Worms, -which were nearly related to this class. Of the two sub-classes of -Lamp-shells, the Hinge-less (Ecardines) must be looked upon as the lower -and more imperfect, the Hinged (Testicardines) as the higher and more -fully developed group. - -The anatomical difference between the Lamp-shells and the three other -classes of Molluscs is so considerable that the latter may be -distinguished from the former by the name of Otocardia. All the -Otocardia have a heart with chamber (ventricle) and ante-chamber -(auricle), whereas Lamp-shells do not possess the ante-chamber. -Moreover, the central nervous system is developed only in the former -(and not in the latter) in the shape of a complete pharyngeal ring. -Hence the four classes of Molluscs may be grouped in the following -manner:-- - - - { 1. Lamp-shells } I. Haplocardia - I. Molluscs { (Spirobranchia). } (with simple heart). - without head. { - _Acephala._ { 2. Mussels } - { (Lamellibranchia). } II. Otocardia - } (with chamber - II. Molluscs { 3. Snails } and ante-chamber - with head. { (Cochlides). } to the heart). - _Cephalophora._ { 4. Cuttles } - { (Cephalopoda). } - - -The result of these structural dispositions for the history of the -pedigree of Molluscs, which is confirmed by palæontology, is that -Lamp-shells stand much nearer to the primæval root of the whole tribe of -Molluscs than do the Otocardia. Probably Mussels and Snails developed as -two diverging branches out of Molluscs, which were nearly akin to the -Lamp-shells. - -Mussels, or Plate-gills (Lamellibranchia), possess a bivalved shell like -the Lamp-shells. In the latter, one of the two valves covers the back, -the other the belly of the animal; whereas in Mussels the two valves lie -symmetrically on the right and left side of the body. Most Mussels live -in the sea, only a few in fresh water. The class is divided into two -sub-classes, Asiphonia and Siphonida, of which the latter were developed -at a later period out of the former. Among the Asiphonia are Oysters, -mother-of-pearl Shells, and fresh water Mussels; among the Siphonida, -which are characterized by a respiratory tube, are the Venus-shells, -Razor-shells, and Burrowing Clams. The higher Molluscs seem to have -developed at a later period out of those without head and teeth; they -are distinguished from the latter by the distinct formation of the head, -and more especially by a peculiar kind of tooth apparatus. Their tongue -presents a curious plate, armed with a great number of teeth. In our -common Vineyard Snail (Helix pomatia) the number of teeth amount to -21,000, and in the large Garden Slug (Limax maximus) to 26,800. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes, 8 Sub-classes, and 21 Orders of Molluscs._ - - - ------------------+-----------------------+------------------------+------------------- - _Classes of_ | _Sub-classes of_ | _Orders of_ | _Systematic Name_ - _Molluscs._ | _Molluscs._ | _Molluscs._ | _of the Orders._ - ------------------+-----------------------+------------------------+------------------- - I. _Molluscs without head or teeth_: ACEPHALA _or_ ANODONTODA. - --------------------------------------------------------------------------------------- - I. { I. Ecardines { 1. Stalked 1. Lingulida - =Lamp-shells= { _Hinge-less_ { 2. Flattened 2. Craniada - { - +Spirobranchia+ { - or { - +Brachiopoda+ { II. Testicardines { 3. Fleshy armed 3. Sarcobrachia - { _Hinge-less_ { 4. Calcareous-armed 4. Sclerobrachia - - - II. { III. Asiphonia { 5. One-muscled 5. Monomya - =Mussels= { _Mussels without_ { 6. Uneven-muscled 6. Heteromya - or { _respiratory tubes_ { 7. Even-muscled 7. Isomya - =Plate-gills= { - { - +Lamellibranchia+ { IV. Siphonida { 8. Round-mantled 8. Integripallia - or { _Mussels with_ { 9. Ray-mantled 9. Sinupalliata - +Phyllobranchia+ { _respiratory tubes_ { 10. Tube-mussels 10. Inclusa - - --------------------------------------------------------------------------------------- - II. _Molluscs with head and teeth_: CEPHALOPHORA _or_ ODONTOPHORA. - --------------------------------------------------------------------------------------- - - { V. Stump-headed { 11. Tube-snails 11. Scaphopoda - III. { _Perocephala_ { 12. Butterfly-snails 12. Pteropoda - =Snails= { - { { 13. With hind gills 13. Opisthobranchia - +Cochlides+ { { 14. With fore gills 14. Prosobranchia - or { VI. Large-headed { 15. Swimming-snails 15. Heteropoda - +Gasteropoda+ { _Delocephala_ { 16. Beetle-snails 16. Chitonoida - { { 17. Snails with lungs 17. Pulmonata - - - VII. Chamber-Poulps { 18. Pearl boats 18. Nautilida - IV. with four gills { 19. Ammon's horns 19. Ammonitida - =Cuttles= } _Tetrabranchia_ { - or } - =Poulps= } VIII. Ink-Poulps with { 20. Ten-armed 20. Decabrachiones - } two gills { - +Cephalopoda+ } _Dibranchia_ { 21. Eight-armed 21. Octobrachiones - - ---------------------------------------------------------------- - - Dibranchia - Heteropoda | - | _Prosobranchia_ | - _Pulmonata_ | | Tetrabranchia - | Lipobranchia | | Cephalopoda - | | | | (=Cuttles= or =Poulps=) - | Gymnobranchia | | | - | | \-------v------/ | - | | | | - | Pleurobranchia | Chitonides | - | _Opisthobranchia_ | | | - | | | | | - \---------------------------------v---------/ | - | | - _Delocephala_ | - | | - | | - \--------v----------/ - | - | _Pteropoda_ - Inclusa | | - | | | - | \------v-----/ - Sinupalliata | - | Scaphopoda | - | | | - Integripalliata \---v--/ - Sclerobrachia _Siphoniata_ | - | | _Perocephala_ - | | Cochlides - | | (=Snails=) - Sarcobrachia _Asiphonia_ | - _Testicardines_ Lamellibranchia | - | (=Mussels=) | - | | | - _Ecardines_ \----------v-------------/ - Spirobranchia | - (=Lamp-shells=) Otocardia - | (Molluscs with chamber and ante-chamber - | to the heart) - | | - | | - \-----------------v--------------/ - | - Promollusca (Primæval Molluscs) - Molluscs with simple heart - | - (Worms) - | - Gastræa - - -We distinguish two sub-classes among the Snails (Cochlides, or -Gasteropoda), namely, the Stump-headed and the Large-headed Snails. The -Stump-headed Snails (Perocephala) are very closely allied to Mussels -(through the Tooth-shells), and also to the Cuttle-fish (through the -Butterfly-snails). The more highly developed Snails, with large heads -(Delocephala), can be divided into Snails with gills (Branchiata) and -Snails with lungs (Pulmonata). Among the latter are the Land-snails, the -only Molluscs which have left the water and become habituated to a life -on land. The great majority of Snails live in the sea, only a few live -in fresh water. Some River-snails in the tropics (the Ampullaria) are -amphibious, living sometimes on land, sometimes in water, and at one -time they breathe through gills, at another through lungs. They have -both kinds of respiratory organs, like the Mud-fish and Gilled Newts -among the Vertebrata. - -The fourth and last class, and at the same time the most highly -developed class of Molluscs, is that of the Cuttles, or Poulps, also -called Cephalopoda (foot attached to the head). They all live in the -sea, and are distinguished from Snails by eight, ten, or more long arms, -which surround the mouth in a circle. The Cuttles existing in our recent -oceans--the Sepia, Calamary, Argonaut, and Pearly Nautilus--are, like -the few Spiral-gill Lamp-shells of the present time, but a poor remnant -of the host which represents this class in the oceans of the primordial, -primary, and secondary periods. The numerous fossil "Ammon's horns" -(Ammonites), "pearl boats" (Nautilus), and "thunderbolts" (Belemnites) -are evidences of the long since extinct splendour of the tribe. The -Poulps, or Cuttles, have probably developed out of a low branch of the -snail class, out of the Butterfly-snails (Pteropoda) or kindred forms. - -The different sub-classes and orders, distinguished in the four classes -of Molluscs, whose systematic succession is given on the Table (p. -160), furnish various proofs of the validity of the law of progress by -their historical development and by the systematic development -corresponding to it. As however these subordinate groups of Molluscs are -in themselves of no further special interest, I must refer to the sketch -of their pedigree on p. 161, and to the detailed pedigree of Molluscs -which I have given in my General Morphology, and I shall now at once -turn to the consideration of the tribe of Star-fishes. - -The Star-fishes (Echinoderma, or Estrellæ) among which are the four -classes of Sea-stars, Sea-lilies, Sea-urchins, and Sea-cucumbers are one -of the most interesting divisions of the animal kingdom, and yet we know -less about them than about any. They all live in the sea. Every one who -has been at the sea shore must have seen at least two of their forms, -the Sea-stars and the Sea-urchins. The tribe of Star-fishes must be -considered as a completely independent tribe of the animal kingdom on -account of its very peculiar organization, and must be carefully -distinguished from the Animal-plants--Zoophytes, or Coelenterata, with -which it is still frequently but erroneously classed under the name -Radiata (as for example, by Agassiz, who even to this day defends this -error of Cuvier's, together with many others). - -All Echinoderma are characterized, and at the same time distinguished -from all other animals, by a very remarkable apparatus for locomotion, -which consists of a complicated system of canals or tubes, filled with -sea water from without. The sea water in these aqueducts is moved partly -by the strokes of the cilia, or vibratile hairs lining their walls, and -partly by the contractions of the muscular walls of the tubes -themselves, which resemble india-rubber bags. The water is pressed from -the tubes into a number of little hollow feet, which thereby become -widely distended, and are then employed for walking and suction. The -Sea-stars are moreover characterized by a peculiar calcareous formation -in the skin, which in most cases forms a firm, well-closed coat of mail, -composed of a number of plates. In almost all Echinoderma the body -consists of five radii (counterparts, or antimera) standing round the -main axis of the body, where they meet. It is only in some species of -Sea-stars that the number of these radii amount to more than five--to -6-9, 10-12, or even to 20-40; and in this case the number of radii is -generally not constant, but varies in different individuals of one -species. - -The historical development and the pedigree of the Echinoderma are -completely revealed to us by their numerous and, in most cases, -excellently preserved fossil remains, by their very remarkable -individual developmental history, and by their interesting comparative -anatomy; this is the case with no other tribe of animals, even the -Vertebrata themselves are not to be excepted. By a critical use of those -three archives, and by a careful comparison of the results derived from -their study, we obtain the following genealogy of the Star-fishes, which -I have already published in my General Morphology (vol. ii. Plate IV. -pp. 62-77.) - -The most ancient and original group of the Star-fishes, the primary form -of the whole phylum, consists of the class of the true Sea-stars -(Asterida). This is established by numerous and important arguments in -anatomy and the history of development, but above all by the irregular -and varying number of the radii, or antimera, which in all other -Echinoderma is limited, without exception, to five. Every Star-fish -consists of a central, small, body-disc, all round the circumference of -which are attached five or several long articulated arms. _Each arm of -the Star-fish essentially corresponds in its organisation with an -articulated worm_ of the class of Ring-worms, or Annelida (p. 149). I -therefore consider the Star-fish as a genuine _stock or cormus of five -or more articulated worms_, which have arisen by the star-wise growth of -a number of buds out of a central mother-worm. The connected members, -thus grouped like the rays of a star, have inherited from the -mother-worm the common opening of the mouth, and the common digestive -cavity (stomach) lying in the central body-disc. The end by which they -have grown together, and which fuses in the common central disc, -probably corresponds to the posterior end of the original independent -worms. - -In exactly the same way several individuals of certain kinds of worms -are united so as to form a star-like cormus. This is the case in the -_Botryllidæ_, compound Ascidians, belonging to the class of the -Tunicata. Here also the posterior ends of the individual worms have -grown together, and have formed a common outlet for discharges, a -central cloaca; whereas at the anterior end each worm still possesses -its own mouth. In Star-fishes the original mouths have probably become -closed in the course of the historical development of the cormus, or -colony, whereas the cloaca has developed into a common mouth for the -whole cormus. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes, 9 Sub-classes, and 20 Orders of Star-fishes._ - -(Compare Gen. Morph. II. Plate IV. pp. 62-67.) - - - ----------------+-------------------------+---------------------------+------------------ - _Classes of the | _Sub-classes of the | _Orders of the | _Systematic Name - Star-fishes._ | Star-fishes._ | Star-fishes._ | of the Orders._ - ----------------+-------------------------+---------------------------+------------------ - | - { I. { 1. Primary Stars | 1. Tecastra - { Sea Stars with radiated { 2. Articulated Stars | 2. Colastra - I. { stomach { 3. Brisinga Stars | 3. Brisingastra - =Sea Stars= { _Actinogastra_ | - +Asterida+ { - { II. { 4. Serpent Stars | 4. Ophiastra - { Sea Stars with disc- { 5. Tree Stars | 5. Phytastra - { shaped stomach { 6. Lily Stars | 6. Crinastra - { _Discogastra_ { | - | - { III. { 7. Plated Lilies with | 7. Phatnocrinida - { Lilies with arms { arms | - { _Brachiata_ { 8. Articulated Lilies | 8. Colocrinida - { { with arms | - | - II. { IV. { 9. Regularly budding | 9. Pentremitida - =Sea Lilies= { Lilies with buds { Lilies | - +Crinoida+ { _Blastoidea_ { 10. Lilies budding on | 10. Eleutherocrina - { { two sides | - | - { V. { 11. Bladder Lilies | 11. Agelacrinida - { Bladder Lilies { without stalks | - { _Cystidea_ { 12. Bladder Lilies | 12. Sphæronitida - { with stalks | - | - { VI. { 13. Palechinida with | 13. Melonitida - { Older Sea Urchins { more than 10 | - { (with more than { rows of ambulacral | - { 20 rows of plates) { plates | - III. { _Palechinida_ { 14. Palechinida with | 14. Eocidaria - =Sea Urchins= { { 10 rows of | - +Echinida+ { VII. { ambulacral plates | - { More recent Sea { 15. Autechinida with | 15. Desmosticha - { Urchins (with 20 { band-like ambulacra | - { rows of plates) { 16. Autechnidia with | 16. Petalosticha - { _Autechinida_ { leaf-like ambulacra | - | - { VIII. { 17. Eupodia with scuti- | 17. Aspidochirota - { Sea Cucumbers { form tentacles | - { with aquatic feet { 18. Eupodia with | 18. Dendrochirota - IV. { _Eupodia_ { branching tentacles | - =Sea Cucumbers= { { | - { IX. { | - +Holothuriæ+ { Sea Cucumbers { 19. Apodia with water- | 19. Liodermatida - { without aquatic { lungs | - { feet { 20. Apodia without | 20. Synaptida - { _Apodia_ { water-lungs | - - ---------------------------------------------------------------- - - Clypeastridæ - | - Spatangidæ | - | | - Dysasteridæ | | - | | | - Aspidochirota | | | - | | \------v------/ - Synaptida | | | - | | | Cassidulidæ - | | | +Petalosticha+ - | | | | - | | | | - Liodermatida | | | - +Apodia+ | \------v-------/ Echinonidæ - | | | | - | | Galeritidæ | - | | | Echinometridæ | - \---------v-----------/ | | | - | \------v---------/ - Dendrochirota | - +Eupodia+ Latistellæ - +Holothuriæ+ Salenidæ | - \------v------/ | | - | | | - | \------v------------/ - | | - | Angustistellæ - | +Desmosticha+ - | +Autechinida+ - | | - | | Colocrinæ - | | | - | | Sphæronitidæ | - Phytastra | | | | - | | | | | - | | Eocidaridæ | | Eleutherocrina - | | | | | | - | | | | | | - Ophiastra | | Agelacrinæ | | - +Discogastra+ | | +Cystidea+ | | - | | | | | | - | | | | | | - | | Melonitida | Phatnocrinæ | - Brisingastra | Palechinida | +Brahiata+ Pentremitida - | | +Echinida+ | | +Blastoidea+ - | | | | | | - | | | | | | - Colastra \----------v-----------------/ \-------v-----------/ - | | +Brachiata+ - | | Crinoida - | | Crinastra - | | | - \-------------------------v----------------------------------/ - | - Tocastra - +Actinogastra+ - +Asterida+ - | - Phracthelminthes - | - Coelomati - | - Gastræa - - -Hence the Star-fishes would be compound stocks of worms which, by the -radial formation of buds, have developed out of true articulated worms, -or Annelids. This hypothesis is most strongly supported by the -comparative anatomy, and by the ontogeny of some Star-fishes (Colastra), -and of segmented worms. The many-jointed Ring-worms (Annelida) in their -inner structure are closely allied to the individual arms or radii of -the Star-fishes, that is to the original single worms, which each arm -represents. Each of the five worms of the Star-fish is a chain composed -of a great number of equi-formal members, or metamera, lying one behind -the other, like every segmented Worm, and every Arthropod. As in the -latter a central nervous cord, the ventral nerve cord runs along the -central line of the ventral wall of each segment. On each metameron -there is a pair of non-jointed feet, and besides these, in most cases, -one or more hard thorns or bristles similar to those of many Ring-worms. -A detached arm of a Star-fish can lead an independent life, and can -then, by the radially-directed growth of buds at one end, again become a -complete star. - -The most important proofs, however, of the truth of my hypothesis are -furnished by the ontogeny or the individual development of the -Echinoderma. The most remarkable facts of this ontogeny were first -discovered in the year 1848 by the great zoologist, Johannes Müller of -Berlin. Some of its most important stages are represented on Plates -VIII. and IX. (Compare their explanation in the Appendix.) Fig. _A_ on -Plate IX. shows us a common Sea-star (Uraster), Fig. _B_, a Sea-lily -(Comatula), Fig. _C_, a Sea-urchin (Echinus), and Fig. _D_, a -Sea-cucumber (Synapta). In spite of the extraordinary difference of form -manifested by these four representatives of the different classes of -Star-fishes, yet the beginning of their development is identical in all -cases. Out of the egg an animal-form develops which is utterly -different from the fully developed Star-fish, but very like the ciliated -larvæ of certain segmented Worms (Star-worms and Ring-worms). This -peculiar animal-form is generally called the "larva," but more correctly -the "nurse" of these Star-fish. It is very small and transparent, swims -about by means of a fringe of cilia, and is always composed of two equal -symmetrical halves or sides. The fully grown Echinoderm, however--which -is frequently more than a hundred times larger, and quite opaque--creeps -at the bottom of the sea, and is always composed of at least five -co-ordinate pieces, or antimera, in the form of radii. Plate VIII. shows -the development of the "nurses" of the four Echinoderms represented on -Plate IX. - -The fully developed Echinoderm arises by a very remarkable process of -budding in the interior of the "nurse," of which it retains little more -than the stomach. The nurse, erroneously called the "larva," of the -Echinoderm, must accordingly be regarded as a solitary worm, which by -internal budding produces a second generation, in the form of a stock of -star-shaped and connected worms. The whole of this process is a genuine -alternation of generations, or metagenesis, not a "metamorphosis," as is -generally though erroneously stated. A similar alternation of -generations also occurs in many other worms, especially in some star -worms (Sipunculidæ), and cord worms (Nemertinæ). Now if, bearing in mind -the fundamental law of biogeny, we refer the ontogeny of Echinoderma to -their phylogeny, then the whole historical development of the -Star-fishes suddenly becomes clear and intelligible to us, whereas -without this hypothesis it remains an insoluble mystery. (Compare Gen. -Morph. ii. pp. 95-99.) - -Besides the reasons mentioned, there are many other facts (principally -from the comparative anatomy of Echinoderma) which most distinctly prove -the correctness of my hypothesis. I established this hypothesis in 1866, -without having any idea that _fossil articulated worms_ still existed, -apparently answering to the hypothetical primary forms. Such have in the -mean time, however, really been discovered. In a treatise "On the -Equivalent of the North American Taconic Schist in Germany,"[3] Geinitz -and Liebe, in 1867, have described a number of articulated Silurian -worms, which completely confirm my suppositions. Numbers of these very -remarkable worms are found in an excellent state of preservation in the -slates of Würzbach, in the upper districts of Reusz. They are of the -same structure as the articulated arm of a Star-fish, and evidently -possessed a hard coat of mail, a much denser, more solid cutaneous -skeleton than other worms in general. The number of body-segments, or -metamera, is very considerable, so that the worms, although no more than -a quarter or half an inch in breadth, attained a length of from two to -three feet. The excellently preserved impressions, especially those of -the Phyllodocites thuringiacus and Crossopodia Henrici, are so like the -arms of many Star-fish (Colastra) that their true blood relationship -seems very probable. This primæval group of worms, which are most -probably the ancestors of Star-fish, I call Mailed worms -(Phracthelminthes, p. 150.) - -[Illustration: Pl. viii. - -STAR FISHES. FIRST GENERATION. WORM PERSON.] - -[Illustration: Pl. ix. - -STAR FISHES. SECOND GENERATION. WORM STOCK.] - -The three other classes of Echinoderma evidently arose at a later period -out of the class of Sea-stars which have most faithfully retained the -original form of the stellate colony of worms. The Sea-lilies, or -Crinoida, differ least from them, but having given up the free, slow -motion possessed by other Sea-stars, they have become adherent to rocks, -etc., and form for themselves a long stalk. Some Encrinites, however -(for example, the Comatulæ, Fig. _B_, on Plates VIII. and IX.), -afterwards detach themselves from their stalk. The original worm -individuals in the Crinoida are indeed no longer preserved in the same -independent condition as in the case of the common star-fish; but they -nevertheless always possess articulated arms extending from a common -central disc. Hence we may unite the Sea-lilies and Sea-stars into a -main-class, or branch, characterized as possessing articulated arms -(Colobrachia). - -In the other two classes of Echinoderma, the Sea-urchins and -Sea-cucumbers, the articulated arms are no longer present as independent -parts, but, by the increased centralization of the stock, have -completely fused so as to form a common, inflated, central disc, which -now looks like a simple box or capsule without arms. The original stock -of five individuals has apparently degenerated to the form-value of a -simple individual, a single person. Hence we may represent these two -classes as a branch characterized as being without arms (Lipobrachia), -equivalent to those which possess articulated arms. The first of these -two classes, that of Sea-urchins (Echinida) takes its name from the -numerous and frequently very large thorns which cover the hard shell, -which is itself artistically built up of calcareous plates. (Fig. _C_, -Plates VIII. and IX.) The fundamental form of the shell itself is a -pentagonal pyramid. The Sea-urchins probably developed directly out of -the group of Sea-stars. The different classes and orders of marine -lilies and stars which are given in the following table, illustrate the -laws of progress and differentiation in a striking manner. In each -succeeding period of the earth's history we see the individual classes -continually increasing in variety and perfection. (Gen. Morph. ii. Plate -IV.) - -The history of three of these classes of Star-fish is very minutely -recorded by numerous and excellently preserved fossils, but on the other -hand, we know almost nothing of the historical development of the fourth -class, that of the Sea-cucumbers (Holothuriæ). These curious -sausage-shaped Star-fish manifest externally a deceptive similarity to -worms. (Fig. _D_, Plates VIII. and IX.) The skeletal structures in their -skin are very imperfect, and hence no distinct remains of their -elongated, cylindrical, worm-like body could be preserved in a fossil -state. However, from the comparative anatomy of the Holothuriæ, we can -infer that they have arisen, by the softening of the cutaneous skeleton, -from members of the class of Sea-urchins. - -From the Star-fish we turn to the fifth and most highly developed tribe -of the invertebrate animals, namely, the phylum of Articulata, or those -with _jointed feet_ (Arthropoda). As has already been remarked, this -tribe corresponds to Linnæus' class of Insects. It contains four -classes: (1) the genuine six-legged Insects, or Flies; (2) the -eight-legged Spiders; (3) the Centipedes, with numerous pairs of legs; -and (4) the Crabs, or Crustacea, whose legs vary in number. The last -class breathe water through gills, and may therefore be contrasted as -the main-class of gill-breathing Arthropoda, or Gilled Insects -(Carides), with the three first classes. The latter breathe air by means -of peculiar wind-pipes, or tracheæ, and may therefore appropriately be -united to form the main-class of the trachea-breathing Arthropoda, or -Tracheate Insects (Tracheata). - -In all animals with articulated feet, as the name indicates, the legs -are distinctly articulated, and by this, as well as by the strong -differentiation of the separate parts of the body, or metamera, they are -sharply distinguished from Ringed worms, with which Bär and Cuvier -classed them. They are, however, in every respect so like the Ringed -worms that they can scarcely be considered altogether distinct from -them. They, like the Ringed worms, possess a very characteristic form of -the central nervous system, the so-called ventral marrow, which -commences in a gullet-ring encircling the mouth. From other facts also, -it is evident that the Arthropoda developed at a late period out of -articulated worms. Probably either the Wheel Animalcules or the Ringed -worms are their nearest blood relations in the Worm tribe. (Gen. Morph. -ii. Plate V. pp. 85-102.) - -Now, although the derivation of the Arthropoda from ringed Worms may be -considered as certain, still it cannot with equal assurance be -maintained that the whole tribe of the former has arisen out of one -branch of the latter. For several reasons seem to support the -supposition that the Gilled Arthropods have developed out of a branch of -articulated worms, different from that which gave rise to the Tracheate -Arthropods. But on the whole it remains more probable that both -main-classes have arisen out of one and the same group of Worms. In this -case the Tracheate Insects--Spiders, Flies, and Centipedes--must have -branched off at a later period from the gill-breathing Insects, or -Crustacea. - -The pedigree of the Arthropoda can on the whole be clearly made out from -the palæontology, comparative anatomy, and ontogeny of its four -classes, although here, as everywhere else, many details remain very -obscure. Not until the history of the individual development of all the -different groups has become more accurately known than it is at present, -can this obscurity be removed. The history of the class of Gilled -Insects, or Crabs (Carides), is at present that best known to us; they -are also called encrusted animals (Crustacea), on account of the hard -crust or covering of their body. The ontogeny of these animals is -extremely interesting and, like that of Vertebrate animals, distinctly -reveals the essential outlines of the history of their tribe, that is, -their phylogeny. Fritz Müller, in his work, "Für Darwin,"(16) which has -already been referred to, has explained this remarkable series of facts -in a very able manner. - -[Illustration: _Nauplius. Youth-form of six Crab-fish._ _Pl. X._ - - A. Limnetis. - B. Cyclops. - C. Lernacocera. - D. Lepas. - E. Sacculina. - F. Peneus.] - -[Illustration: _Adult form of the same six Crab-fish._ _Pl. XI._ - - A. Limnetis. - B. Cyclops. - C. Lernacocera. - D. Lepas. - E. Sacculina. - F. Peneus.] - -The common primary form of all Crabs, which in most cases is even now -the first to develop out of the egg, is originally one and the same, the -so-called _Nauplius_. This remarkable primæval crab represents a very -simple form of articulated animal, the body of which in general has the -form of a roundish, oval, or pear-shaped disc, and has on its ventral -side only three pairs of legs. The first of these is uncloven, the two -subsequent pairs are forked. In front, above the mouth, lies a simple, -single eye. Although the different orders of the Crustacean class differ -very widely from one another in the structure of their body and its -appendages, yet the early Nauplius form always remains essentially the -same. In order to be convinced of this, let the reader look attentively -at Plates X. and XI., a more detailed explanation of which is given in -the Appendix. On Plate XI. we see the fully developed representatives of -six different orders of Crabs, a Leaf-footed Crab (Limnetis, Fig. _A -c_); a Stalked Crab (Lepas, Fig. _D c_); a Root Crab (Sacculina, Fig. -_E c_); a Boatman Crab (Cyclops, Fig. _B c_); a Fish Louse (Lernæocera, -Fig. _C c_); and, lastly, a highly developed Shrimp (Peneus, Fig. _F -c_). These six crabs vary very much, as we see, in the entire form of -body, in the number and formation of the legs, etc. When, however, we -look at the earliest stages, or "nauplius," of these six different -classes, after they have crept out of the egg--those marked with -corresponding letters on Plate X. (Fig. _A n-F n_)--we shall be -surprised to find how much they agree. The different forms of Nauplius -of these six orders differ no more from one another than would six -different "good species" of one genus. Consequently, we may with -assurance infer a common derivation of all those orders from a common -Primæval Crab, which was essentially like the Nauplius of the present -day. - - -SYSTEMATIC SURVEY - -_Of the 7 Legions and 20 Orders of Crabs, or Crustacea._ - - - -------------------------+--------------------------+----------------------+-------------- - _Legions of the_ | _Orders of the_ | _Systema Name_ | _Name of a_ - _Crustaceæ._ | _Crustaceæ._ | _of the Orders._ | _Genus as an_ - | | | _example._ - -------------------------+--------------------------+----------------------+-------------- - I. ENTOMOSTRACA, _Lower Crustacea_, or Segmented Crabs (not passing through the - actual Zoëa form in youth). - ------------------------------------------------------------------------------------------ - - +I. Branchiopoda+ { 1. Primæval Crabs 1. Archicarida Nauplius - Gill-footed Crabs { 2. Leaf-foot Crabs 2. Phyllopoda Limnetis - { 3. Trilobites 3. Trilobita Paradoxides - { 4. Water Fleas 4. Cladocera Daphnia - { 5. Bivalve Crabs 5. Ostracoda Cypris - - - +II. Pectostraca+ { 6. Barnacle Crabs 6. Cirripedia Lepas - Fixed Crabs { 7. Root Crabs 7. Rhizocephala Sacculina - - +III. Copepoda+ { 8. Boatmen Crabs 8. Eucopepoda Cyclops - Oar-footed Crabs { 9. Fish Lice 9. Siphonostoma Lernæocera - - +IV. Pantopoda+ {10. No-body Crabs 10. Pycnogonida Nymphon - No-body Crabs { - - +V. Poecilopoda+ {11. Spear-tails 11. Xiphosura Limulus - Shield Crabs {12. Giant Crabs 12. Gigantostraca Eurypterus - - ------------------------------------------------------------------------------------------ - II. MALACOSTRACA, _Higher Crustacea_, or Mailed Crabs (passing through the Zoëa form - in youth). - ------------------------------------------------------------------------------------------ - - +VI. Podophthalma+ {13. Zoëa Crabs 13. Zoëpoda Zoëa - Stalk-eyed Mailed {14. Split-legged Crabs 14. Schizopoda Mysis - Crabs {15. Mouth-footed Crabs 15. Stomatopoda Squilla - {16. Ten-footed Crabs 16. Decapoda Peneus - - +VII. Edriophthalma+ {17. Cuma Crabs 17. Cumacea Cuma - Mailed Crabs with {18. Flea Crabs 18. Amphipoda Gammarus - sessile eyes {19. Wizard Crabs 19. Læmodipoda Caprella - {20. Louse Crabs 20. Isopoda Oniscus - - ---------------------------------------------------------------- - - - Brachyura Isopoda - | | - | Læmodipoda | - | | | - Anomura | | - | | | - | Amphipoda | - | | | - | \-----v----/ - Macrura | - Decapoda Stomatopoda Cumacea - | | +Edriophthalma+ - | | | - \----v----/ | - | | - | | - \---------------------------v------------/ - | - Schizopoda - +Podophthalma+ - | - Zoëpoda - +Malacostraca+ - Gigantostraca | Rhizocephala - | | Siphonostoma | - | Xiphosuræ Zoëa | Cirripediæ - | | | | +Pectostraca+ - | | | | | - \------v------/ | | | - | | | | - +Poecilopoda+ | | | - | Nebaliæ | | | - | | | Eucopepoda | - Belinuroe | | +Copepoda+ | Pycnogonida - | | | | | +Pantopoda+ - Trilobita | | | | | - | Phyllopoda | | Ostracoda | | - Cladoceræ | | | | | | | - | | | | | | | | - \-----------------v-------/ | | \---v---/ | - | | | | | - +Branchiopoda+ | | | | - | | | | | - | | | | | - \----------------------v-------------------------/ - | - Nauplius - | - +Archicaridæ+ - - (Articulated Worms) - - -The pedigree on p. 177 will show how we may at present approximately -conceive the derivation of the twenty orders of Crustacea enumerated on -p. 176, from the common primary form of the Nauplius. Out of the -Nauplius form--which originally existed as an independent genus--the -five legions of lower Crabs developed as diverging branches in different -directions, which in the systematic survey of the class are united as -Segmented Crabs (Entomostraca). The higher division of Mailed Crabs -(Malacostraca) have likewise originated out of the common Nauplius form. -The Nebalia is still a direct form of transition from the Phyllopods to -the Schizopods, that is, to the primary form of the stalk-eyed and -sessile-eyed Mailed Crabs. The Nauplius at this stage gives rise to -another larva form, the so-called Zoëa, which is of great importance. -The order of Schizopoda, those with cloven feet (Mysis, etc.), probably -originated from this curious Zoëa; they are at present still directly -allied, through the Nebalia to the Phyllopoda, those with foliaceous -feet. But of all living crabs the Phyllopods are the most closely allied -to the original primary form of the Nauplius. Out of the Schizopoda the -stalk-eyed and sessile-eyed Mailed Crabs, or Malacostraca, developed as -two diverging branches in different directions: the former through -shrimps (Peneus, etc.), the latter through the Cumacea (Cuma, etc.), -which are still living and closely allied to the Schizopoda. Among those -with stalked eyes is the river crab (cray-fish), the lobster, and the -others with long tails, or the Macrura, out of which, in the chalk -period, the short-tailed crabs, or Brachyura, developed by the -degeneration of the tail. Those with sessile eyes divide into the two -branches of Flea-crabs (Amphipoda) and Louse-crabs (Isopoda); among the -latter are our common Rock-slaters and Wood-lice. - -The second main-class of Articulated animals, that of the Tracheata, or -air-breathing Tracheate Insects[4] (Spiders, Centipedes, and Flies) did -not develop until the beginning of the palæolithic era, after the close -of the archilithic period, because all these animals (in contrast with -the aquatic crabs) are originally inhabitants of land. It is evident -that the Tracheata can have developed only after the lapse of the -Silurian period when terrestrial life first began. But as fossil remains -of spiders and insects have been found, even in the carboniferous beds, -we can pretty accurately determine the time of their origin. The -development of the first Tracheate Insects out of gill-bearing -Zoëa-crabs, must have taken place between the end of the Silurian and -the beginning of the coal period, that is, in the Devonian period. - -Gegenbaur, in his excellent "Outlines of Comparative Anatomy,"(21) has -lately endeavoured to explain the origin of the Tracheata by an -ingenious hypothesis. The system of tracheæ, or air pipes, and the -modifications of organization dependent upon it, distinguish Flies, -Centipedes, and Spiders so much from other animals, that the conception -of its first origin presents no inconsiderable difficulties to -phylogeny. According to Gegenbaur, of all living Tracheate Insects, the -Primæval Flies, or Archiptera, are most closely allied to the common -primary form of the Tracheata. These insects--among which we may -especially mention the delicate Day flies (Ephemera), and the agile -dragon-flies (Libellula)--in their earliest youth, as larvæ, frequently -possess _external tracheate gills_ which lie in two rows on the back of -the body, and are shaped like a leaf or paint-brush. Similar leaf or -paint-brush shaped organs are met with as real water-breathing organs or -gills, in many crabs and ringed worms, and, moreover, in the latter as -real dorsal appendages or limbs. The "tracheate gills," found in the -larvæ of many primæval winged insects, must in all probability be -explained as "_dorsal limbs_," and as having developed out of the -corresponding appendages of the Annelida, or possibly as having really -arisen out of similar parts in Crustacea long since extinct. The present -tracheal respiration of the Tracheata developed at a later period out of -respiration through the "tracheate gills." The tracheate gills -themselves, however, have in some cases disappeared, and in others -become transformed into the _wings_ of the Flies. They have disappeared -entirely in the classes of Spiders and Centipedes, and these groups must -accordingly be conceived of as degenerated or peculiarly developed -lateral branches of the Fly class, which at an early period branched off -from the common primary form of Flies; Spiders probably did so at an -earlier period than Centipedes. Whether that common primary form of all -Tracheata, which in my General Morphology I have named Protracheata, did -develop directly out of genuine Ringed worms, or at first out of -Crustacea of the Zoëa form (Zoëpoda, p. 177) will probably be settled at -some future time by a more accurate knowledge and comparison of the -ontogeny of the Tracheata, Crustacea, and Annelida. However, the root of -the Tracheata, as well as that of the Crustacea, must in any case be -looked for in the group of Ringed worms. - -The genuine Spiders (Arachnida) are distinguished from Flies by the -absence of wings, and by four pairs of legs; but, as is distinctly seen -in the Scorpion-spiders and Tarantulæ, they, like Flies, possess in -reality only three pairs of genuine legs. The apparent "fourth pair of -legs" in spiders (the foremost) are in reality a pair of feelers. Among -the still existing Spiders, there is a small group which is probably -very closely allied to the common primary form of the whole class; this -is the order of Scorpion-spiders, or Solifugæ, (Solpuga, Galeodes), of -which several large species live in Africa and Asia, and are dreaded on -account of their poisonous bite. Their body consists--as we suppose to -have been the case in the common ancestor of the Tracheata--of a head -possessing several pairs of feelers like legs, of a thorax, to the three -rings of which are attached three pairs of legs, and of a hinder body, -or abdomen, consisting of many distinct rings. In the articulation of -their body, the Solifugæ are therefore in reality more closely related -to flies than to other spiders. Out of the Devonian Primæval Spiders, -which were nearly related to the Solifugæ of the present day, the Long -Spiders, the Tailor Spiders, and the Round Spiders probably developed as -three diverging branches. - -The _Long Spiders_ (Arthrogastres), in which the earlier articulation of -body has been better preserved than in Round Spiders, appear to be the -older and more original forms. The most important members of this -sub-class are the scorpions, which are connected with the Solifugæ -through the Tarantella (or Phrynidæ). The small book scorpions, which -inhabit our libraries and herbariums, appear as a degenerate lateral -branch from the true scorpions. Midway between the Scorpions and Round -Spiders are the long-legged Tailor-spiders (Opiliones) which have -possibly arisen out of a special branch of the Solifugæ. The -Pycnogonida, or No-body Crabs, and the Arctisca, or Bear Worms--still -generally included among Long Spiders--must be completely excluded from -the class of Spiders; the former belong to the Crustacea, the latter to -Ringed worms. - - -SYSTEMATIC SURVEY - -_Of the 3 Classes and 17 Orders of the Tracheata._ - - - ------------------+---------------------+----------------------+---------------------- - _Classes of the_ | _Sub-Classes of the_| _Order of the_ | _Two Names of_ - _Tracheata._ | _Tracheata._ | _Tracheata._ |_Genera as examples._ - ------------------+---------------------+----------------------+---------------------- - { { 1. Scorpion spiders { Solpuga - { { _Solifugæ_ { Galeodes - { { - { { 2. Tarantella { Phrynus - { { _Phrynida_ { Thelyphonus - { I. { - I. { Long spiders { 3. Scorpions { Scorpio - =Spiders= { _Arthrogastres_ { _Scorpioda_ { Buthus - { { - +Arachnida+ { { 4. Book scorpions { Obisium - { { _Pseudoscorpioda_ { Chelifer - { { - { { 5. Tailor spiders { Phalangium - { { _Opilionida_ { Opilio - { - { - { II. { 6. Spinning spiders { Epeira - { Round spiders { _Araneæ_ { Mygale - { { { - { _Sphærogastres_ { 7. Mites { Sarcoptes - { { _Acarida_ { Demodex - - - II. { III. - =Centipedes= { Simple-footed { 8. Simple-footed { Scolopendra - { _Chilopoda_ { _Chilopoda_ { Geophilus - { { - +Scolopendria+ { IV. { 9. Double-footed { Julus - or { Double-footed { _Diplopoda_ { Polydesmus - +Myriapoda+ { _Diplopoda_ { - - - { { 10. Primitive flies { Ephemera - { { _Archiptera_ { Libellula - { { - { { 11. Gauze-wings { Hemerobius - { { _Neuroptera_ { Phryganea - { V. { - { Chewing { 12. Straight-wings { Locusta - { _Masticantia_ { _Orthoptera_ { Forficula - { { - III. { { 13. Beetles { Cicindela - =Flies= { { _Coleoptera_ { Melolontha - { { - +Hexapoda+ { { 14. Bee-wings { Apis - { { _Hymenoptera_ { Formica - { - { - { { 15. Bugs { Aphis - { VI. { _Hemiptera_ { Cimex - { Sucking { - { _Sugentia_ { 16. Two-wings { Culex - { { _Diptera_ { Musca - { { - { { 17. Butterflies { Bombyx - - ---------------------------------------------------------------- - - Butterflies - _Lepidoptera_ - | - Bees | Two-wings - _Hymenoptera_ | _Diptera_ - | | | - | | | - Beetles | | | Bugs - _Coleoptera_ \-------v-----/ | _Hemiptera_ - | | | | - | Gauze wings | | - Straight-wings _Neuroptera_ \-------v------/ - _Orthoptera_ | | - | | | - | | | - \----------------------v-----------------------------/ - - Primæval Flies - _Archiptera_ - | - Scorpions | Double-footed - _Scorpioda_ | _Diplopoda_ - Tailor Spiders | | | - _Opiliones_ | | | - | Book Scorpions | | | - Mites | _Pseudoscorpioda_ | | | - _Acarida_ | | | | | - | | \-----v-----/ | | - | | | | | - | | Tarantella | | - Weaving Spiders | _Phrynida_ | Simple-footed - _Araneæ_ | | | _Chilopoda_ - | | | | =Centipedes= - | | | | +Myriapoda+ - \-------------v--------/ | | - | | | - Scorpion Spiders | | - _Solifugæ_ | | - =Spiders.= | | - +Arachnida+ | | - | | | - | =Flies= | - | +Insecta Hexapoda+ | - | | | - | | | - \--------------------v---------------------/ - | - Primary Air-breathing Arthropods - _Protracheata_ - | - | - Articulated Worms - _Coelminthes_ - -Fossil remains of Long Spiders are found in the Coal. The second -sub-class of the Arachnida, the _Round Spiders_ (Sphærogastres), first -appear in the fossil state in the Jura, that is, at a very much later -period. They have developed out of a branch of the Solifuga, by the -rings of the body becoming more and more united with one another. In the -true _Spinning Spiders_ (Araneæ), which we admire on account of their -delicate skill in weaving, the union of the joints of the trunk, or -metamera, goes so far, that the trunk now consists of only two pieces, -of a head-breast (cephalo-thorax) with jaws, feelers, and four pairs of -legs, and of a hinder body without appendages, where the spinning warts -are placed. In _Mites_ (Acarida), which have probably arisen by -degeneration (especially by parasitism) out of a lateral branch of -Spinning Spiders, even these two trunk pieces have become united and now -form an unsegmented mass. - -The class of _Scolopendria_, _Myriapoda_, or Centipedes, the smallest -and poorest in forms of the four classes of Arthropoda, is characterized -by a very elongated body, like that of a segmented Ringed worm, and -often possesses more than a hundred pairs of legs. But these animals -also originally developed out of a six-legged form of Tracheata, as is -distinctly proved by the individual development of the millipede in the -egg. Their embryos have at first only three pairs of legs, like genuine -insects, and only at a later period do the posterior pairs of legs bud, -one by one, from the growing rings of the hinder body. Of the two orders -of Centipedes (which in our country live under barks of trees, in moss, -etc.) the round, _double-footed_ ones (Diplopoda) probably did not -develop until a later period out of the older flat, _single-footed_ ones -(Chilopoda), by successive pairs of rings of the body uniting together. -Fossil remains of the Chilopoda are first met with in the Jura period. - -The third and last class of the Arthropoda breathing through tracheæ, is -that of the _Flies_, or _Insects_, in the narrow sense of the word -(Insecta, or Hexapoda), the largest of all classes of animals, and next -to that of Mammalia, also the most important. Although Flies develop a -greater variety of genera and species than all other animals taken -together, yet these are all in reality only superficial variations of a -single type, which is entirely and constantly preserved in its essential -characteristics. In all Flies the three divisions of the trunk--head, -breast (thorax), and hinder body are quite distinct. The _hinder body_, -or _abdomen_, as in the case of spiders, has no articulated appendages. -The central division, the _breast_ or _thorax_, has on its ventral side -three pairs of legs, on its back _two pairs of wings_. It is true that, -in very many Flies, one or both pairs of wings have become reduced in -size or have even entirely disappeared; but the comparative anatomy of -Flies distinctly shows that this deficiency has arisen only gradually by -the degeneration of the wings, and that all the Flies existing at -present are derived from a common, primary Fly, which possessed three -pairs of legs and two pairs of wings. (Compare p. 256.) These wings, -which so strikingly distinguish Flies from all other Arthropoda, -probably arose, as has been already shown, out of the tracheate gills -which may still be observed in the larvæ of the ephemeral flies -(Ephemera) which live in water. - -The head of Flies universally possesses, besides the eyes, a pair of -articulated feelers, or antennæ, and also three jaws upon each side of -the mouth. These _three pairs of jaws_, although they have arisen in all -Flies from the same original basis, by different kinds of adaptation, -have become changed to very varied and remarkable forms in the various -orders, and are therefore employed for distinguishing and characterizing -the main divisions of the class. In the first place, we may distinguish -two main divisions, namely, Flies with _chewing_ mandibles (Masticantia) -and Flies with _sucking_ mouths (Sugentia). On a closer examination each -of these two divisions may again be divided into two sub-groups. Among -chewing Flies, or Masticantia, we may distinguish the biting and the -licking ones. _Biting flies_ (Mordentia) comprise the most ancient and -primæval winged Flies, the gauzy-winged (Neuroptera), straight-winged -(Orthoptera), and beetles (Coleoptera). _Licking flies_ (Lambentia) are -represented by the one order of skin-winged (Hymenoptera) Flies. We -distinguish two groups of _Sucking Flies_, or Sugentia, namely, those -which prick and those which sip. There are two orders of pricking Flies -(Pungentia), those with half wings (Hemiptera) and gnats and blow-flies -(Diptera); butterflies are the only _sipping_ Flies (Sorbentia), -Lepidoptera. - -Biting Flies, and indeed the order of _Primæval Flies_ (Archiptera, or -Pseudoneuroptera) are nearest akin to the still living Flies, and -include the most ancient of all Flies, the primary forms of the whole -class (hence also those of all Tracheata). Among them are, first of all, -the Ephemeral Flies (Ephemera) whose larvæ which live in water, in all -probability still show us in their tracheæ-gills the organs out of which -the wings of Flies were originally developed. This order further -contains the well known dragon-flies, or Libellula, the wine-glass sugar -mites (Lepisma), the hopping Flies with bladder-like feet (Physopoda), -and the dreaded Termites, fossil remains of which are found even in -coal. The order of Gauze-winged Flies (Neuroptera), probably developed -directly out of the primæval Flies, which differ from them only by their -perfect series of transformations. Among them are the gauze-flies -(Planipennia), caddis-flies (Phryganida), and fan-flies (Strepsiptera). -Fossil Flies, which form the transition from the primæval Flies -(Libellula) to the gauze-winged (Sialidæ), are found even in coal -(Dictyophylebia). - -The order of _Straight-winged Flies_ (Orthoptera) developed at an early -period out of another branch of the primæval Flies by differentiation of -the two pairs of wings. This division is composed of one group with a -great variety of forms--cockroaches, grasshoppers, crickets, etc. -(Ulonata)--and of a smaller group consisting only of the well-known -earwigs (Labidura), which are characterised by nippers at the hinder end -of their bodies. Fossil remains of cockroaches, as well as of crickets -and grasshoppers, have been found in coal. - -Fossil remains of the fourth order of Biting Flies, _beetles_ -(Coleoptera) likewise occur in coal. This extremely comprehensive -order--the favourite one of amateurs and collectors--shows more clearly -than any other what infinite variety of forms can be developed -externally by adaptation to different conditions of life, without the -internal structure and the original form of the body being in any way -essentially changed. Beetles have probably developed out of a branch of -the straight-winged Flies, from which they differ only in their -transformations (larva, pupa, etc.). - -The one order of _Licking Flies_, namely, the interesting group of the -_Bees_, or _Skin-winged Flies_ (Hymenoptera), is closely allied to the -four orders of biting Flies. Among them are those Flies which have risen -to such an astonishing degree of mental development, of intellectual -perfection, and strength of character, by their extensive division of -labour, formation of communities and states, and surpass in this not -merely most invertebrate animals, but even most animals in general. This -may be said especially of all ants and bees, also of wasps, leaf-wasps, -wood-wasps, gall-wasps, etc. They are first met with in a fossil state -in the oolites, but they do not appear in greater numbers until the -tertiary period. Probably these insects developed either out of a branch -of the primæval Flies or the gauze-winged Flies. - -Of the two orders of _Pricking Flies_ (Hemiptera and Diptera), that -containing the _Half-winged Flies_ (Hemiptera), also called Beaked Flies -(Rhynchota), is the older of the two. It includes three sub-orders, -viz., the leaf-lice (Homoptera), the bugs (Heteroptera), and lice -(Pediculina). Fossil remains of the first two classes are found in the -oolites; but an ancient Fly (Eugereon) is found in the Permian system, -and seems to indicate the derivation of the Hemiptera from the -Neuroptera. Probably the most ancient of the three sub-orders of the -Hemiptera are the Homoptera, among which, besides the actual leaf-lice, -are the shield-lice, leaf-fleas, and leaf-crickets, or Cicadæ. Lice have -probably developed out of two different branches of Homoptera, by -continued degeneration (especially by the loss of wings); bugs, on the -other hand, by the perfecting and differentiation of the two pairs of -wings. - -The second order of _pricking flies_, namely, the _Two-winged Flies_ -(Diptera), are also found in a fossil state in the oolites, together -with Half-winged Flies; but they probably developed out of the Hemiptera -by the degeneration of the hind wings. In Diptera the fore wings alone -have remained perfect. The principal portion of this order consists of -the elongated gnats (Nemocera) and of the compact blow-flies and -house-flies (Brachycera), the former of which are probably the older of -the two. However, remains of both are found in the oolitic period. The -two small groups of lice-flies (Pupipara) forming chrysales, and the -hopping-fleas (Aphaniptera), probably developed out of the Diptera by -degeneration resulting from parasitism. - -The eighth and last order of Flies, and at the same time the only one -with mouth-parts adapted to sipping liquids, consists of _moths_ and -_butterflies_ (Lepidoptera). This order appears, in several -morphological respects, to be the most perfect class of Flies, and -accordingly was the last to develop. For we only know of fossil remains -of this order from the tertiary period, whereas the three preceding -orders extend back to the oolites, and the four biting orders even to -the coal period. The close relationship between some moths (Tineæ) and -(Noctuæ), and some caddis-flies (Phryganida) renders it probable that -butterflies have developed from this group, that is, out of the order of -Gauze-winged Flies, or Neuroptera. - -The whole history of Flies, and, moreover, the history of the whole -tribe of Arthropoda, essentially confirms the great laws of -differentiation and perfecting which, according to Darwin's theory of -selection, must be considered as the necessary results of Natural -Selection. The whole tribe, so rich in forms, begins in the Archilithic -period with the class of _Crabs_ breathing by gills, and with the lowest -_Primæval Crabs_, or Archicaridæ. The form of these Primæval Crabs, -which were developed out of segmented worms, is still approximately -preserved by the remarkable _Nauplius_, in the common larval stage of so -many Crabs. Out of the Nauplius, at a later period, the curious Zoëa was -developed, which is the common larval form of all the higher or mailed -crabs (Malacostraca), and, at the same time, possibly of that Arthopod -which at first breathed through tracheæ, and became the common ancestor -of all _Tracheata_. This Devonian ancestor, which must have originated -between the end of the Silurian and the beginning of the Coal period, -was probably most closely related to the still living Primæval Flies, or -_Archiptera_. Out of these there developed, as the main tribe of the -Tracheata, the class of Flies, from the lowest stage of which the -_spiders_ and _centipedes_ separated as two diverging branches. -Throughout a long period there existed only the four biting orders of -Flies--the Primæval flies, Gauze-wings, Straight-wings, and the Beetles, -the first of which is probably the common primary form of the three -others. It was only at a much later period that the Licking, Pricking, -and Sipping flies developed out of the Biting ones, which retained the -original form of the three pairs of jaws most distinctly. The following -table will show once more how these orders succeeded one another in the -history of the earth. - - -CLASSIFICATION OF FLIES. - - { { 1. Primæval winged { M.I. } - { { _Archiptera_ { A.A. } - { { } - { I. { 2. Gauze-winged { M.C. } - A. { Biting Flies { _Neuroptera_ { A.A. } - { { } - =Flies= { _Mordentia_ { 3. Straight-winged { M.I. } - =with Chewing= { { _Orthoptera_ { A.D. } - =Mouths= { { } - { { 4. Beetles { M.C. } - +Masticantia+ { { _Coleoptera_ { A.D. } - { - { - { II. { 5. Skin-winged { M.C. } - { Licking Flies { _Hymenoptera_ { A.A. } - { _Lambentia_ { } - } - } - { { 6. Half-winged { M.I. } - { III. { _Hemiptera_ { A.A. } - B. { Stinging Flies { } - =Flies= { { 7. Tway-flies { M.C. } - =with Sucking= { _Pungentia_ { _Diptera_ { A.D. } - =Mouths= { - { - +Sugentia+ { IV. { 8. Butterflies { M.C. } - { Sipping Flies { _Lepidoptera_ { A.A. } - { { { } - { _Sorbentia_ { { } - - - _Note._--The difference in the metamorphosis or transformation and in - the development of the wings of the eight individual orders of Flies - is also specified by the following letters: M.I. = Imperfect - Metamorphosis. M.C. = Perfect Metamorphosis. (Compare Gen. Morph. ii. - p. 99.) A.A. = Equal wings (fore and hinder wings are the same, or - differ but little). A.D. = Unequal wings (fore and hinder wings very - different in structure and texture, occasioned by strong - differentiation). - - - - -CHAPTER XX. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -III. VERTEBRATE ANIMALS. - - - The Records of the Creation of Vertebrate Animals (Comparative - Anatomy, Embryology, and Palæontology).--The Natural System of - Vertebrate Animals.--The Four Classes of Vertebrate Animals, - according to Linnæus and Lamarck.--Their increase to Nine - Classes.--Main Class of the Tube-hearted, or Skull-less Animals - (the Lancelet).--Blood Relationship between the Skull-less Fish - and the Tunicates.--Agreement in the Embryological Development - of Amphioxus and Ascidiæ.--Origin of the Vertebrate Tribe out of - the Worm Tribe.--Main Class of Single-nostriled, or - Round-mouthed Animals (Hag and Lampreys).--Main Class of - Anamnionate Animals, devoid of Amnion.--Fishes (Primæval Fish, - Cartilaginous Fish, Osseous Fish).--Mud-fish, or Dipneusta.--Sea - Dragons, or Halisauria.--Frogs and Salamanders, or Amphibia - (Mailed Amphibia, Naked Amphibia).--Main Class of Amnionate - Animals, or Amniota.--Reptiles (Primary Reptiles, Lizards, - Serpents, Crocodiles, Tortoises, Flying-Reptiles, Dragons, - Beaked Reptiles).--Birds (Feather-tailed, Fan-tailed, - Bush-tailed). - - -Not one of the natural groups of organisms--which, we have designated as -tribes, or phyla, on account of the blood-relationship of all the -species included in them--is of such great and exceeding importance as -the tribe of Vertebrate Animals. For, according to the unanimous opinion -of all zoologists, man also is a member of the tribe; and his whole -organization and development cannot possibly be distinguished from that -of other Vertebrate animals. But as from the individual history of -human development, we have already recognized the undeniable fact that, -in developing out of the egg, man at first does not differ from other -Vertebrate animals, and especially from Mammals, we must necessarily -come to the conclusion, in regard to the palæontological history of his -development, that man has, historically, actually developed out of the -lower Vertebrata, and that he is directly derived from lower mammals. -This circumstance, together with the many high interests which, in other -respects, entitle the Vertebrata to more consideration than other -organisms, justifies us in examining the pedigree of the Vertebrata and -its expression in the natural system, with special care. - -Fortunately, the records of creation, which must in all cases be our -guide in establishing pedigrees, are especially complete in this -important animal tribe, from which our own race has arisen. Even at the -beginning of our century Cuvier's comparative anatomy and palæontology, -and Bär's ontogeny of the Vertebrate animals, had brought us to a high -level of accurate knowledge on this matter. Since then it is especially -due to Johannes Müller's and Rathke's investigations in comparative -anatomy, and most recently to those of Gegenbaur and Huxley, that our -knowledge of the natural relationships among the different groups of -Vertebrata has become enlarged. It is especially Gegenbaur's classical -works, penetrated as they are throughout with the fundamental principles -of the Theory of Descent, which have demonstrated that the material of -comparative anatomy receives its true importance and value only by the -application of the Theory of Descent, and this in the case of all -animals, but especially in that in the Vertebrate tribe. Here, as -everywhere else, analogies must be traced to Adaptation, homologies to -Transmission by Inheritance. When we see that the limbs of the most -different Vertebrata, in spite of their exceedingly different external -forms, nevertheless possess essentially the same internal structure; -when we see that in the arm of a man and ape, in the wing of a man or a -bird, in the breast fins of whales and sea-dragons, in the fore-legs of -hoofed animals and frogs, the same bones always lie in the same -characteristic position, articulation and connection--we can only -explain this wonderful agreement and homology by the supposition of a -common transmission by inheritance from a single primary form. On the -other hand, the striking differences of these homologous bodily parts -proceed from adaptation to different conditions of existence. (Compare -Plate IV.) - -Ontogeny, or the individual history of development, like comparative -anatomy, is of especial importance to the pedigree of the Vertebrata. -The first stages of development arising out of the egg are essentially -identical in all Vertebrate animals, and retain their agreement the -longer, the nearer the respective Vertebrate animal forms, when fully -developed, stand to one another in the natural system, that is, in the -pedigree. How far this agreement of germ forms, or embryos, extends, -even in the most highly developed Vertebrate animals, I have already had -occasion to explain (vol i. pp. 306-309). The complete agreement in form -and structure, for example, in the embryos of a man and a dog, of a bird -and a tortoise, existing in the stages of development represented on -Plates II. and III., is a fact of incalculable importance, and furnishes -us with the most important data for the construction of their pedigree. - -Finally, the palæontological records of creation are also of especial -value in the case of these same Vertebrate animals; for their fossil -remains belong for the most part to the bony skeleton, a system of -organs which is of the utmost importance for understanding their general -organization. It is true that here, as in all other cases, the fossil -records are exceedingly imperfect and incomplete, but more important -remains of extinct Vertebrate animals have been preserved in a fossil -state, than of most other groups of animals; and single fragments -frequently furnish the most important hints as to the relationship and -the historical succession of the groups. - -The name of _Vertebrate Animals_ (Vertebrata), as I have already said, -originated with the great Lamarck, who towards the end of the last -century comprised under this name, Linnæus' four higher classes of -animals, viz. Mammals, Birds, Amphibious animals, and Fishes, Linnæus' -two lower classes, Insects and Worms, Lamarck contrasted to the -Vertebrata as _Invertebrata_, later also called _Evertebrata_. - -The division of the Vertebrata into the four classes above named was -retained also by Cuvier and his followers, and in consequence by many -zoologists down to the present day. But in 1822 Blanville, the -distinguished anatomist, found out by comparative anatomy--which Bär did -almost at the same time from the ontogeny of Vertebrata--that Linnæus' -class of Amphibious animals was an unnatural union of two very different -classes. These two classes were separated as early as 1820, by Merrin, -as two main groups of Amphibious animals, under the names of Pholidota -and Batrachia. The _Batrachia_, which are at present (in a restricted -sense) called Amphibious animals, comprise Frogs, Salamanders, gilled -Salamanders, Cæcilia, and the extinct Labyrinthodonta. Their entire -organization is closely allied to that of Fishes. The _Pholidota_, or -Reptiles, on the other hand, are much more closely allied to Birds. They -comprise lizards, serpents, crocodiles, and tortoises, and the groups of -the mesolithic Dragons, Flying reptiles, etc. - -In conformity with this natural division of Amphibious animals into two -classes, the whole tribe of Vertebrate animals was divided into two main -groups. The first main group, containing Amphibious animals and Fishes, -breathe throughout their lives, or in early life, by means of gills, and -are therefore called _gilled Vertebrata_ (Branchiata, or Anallantoida). -The second main group--Reptiles, Birds, and Mammals--breathe at no -period of their lives through gills, but exclusively through lungs, and -hence may appropriately be called Gill-less, or _Vertebrata with lungs_ -(Abranchiata, or Allantoida). However correct this distinction may be, -still we cannot remain satisfied with it if we wish to arrive at a true -natural system of the vertebrate tribe, and at a right understanding of -its pedigree. In this case, as I have shown in my General Morphology, we -are obliged to distinguish three other classes of Vertebrate animals, by -dividing what has hitherto been regarded as the class of fishes into -four distinct classes. (Gen. Morph. vol. ii. Plate VII. pp. 116-160.) - -The first and lowest of these classes comprises the _Skull-less_ animals -(Acrania), or animals with _tubular hearts_ (Leptocardia), of which only -one representative now exists, namely, the remarkable little Lancelet -(Amphioxus lanceolatus). Nearly allied to this is the second class, that -of the _Single-nostriled_ animals (Monorrhina), or _Round-mouthed_ -animals (Cyclostoma), which includes the Hags (Myxinoida) and Lampreys -(Petromyzonta). The third class contains only the genuine Fish (Pisces): -the Mud-fishes (Dipneusta) are added to these as a fourth class, and -form the transition from Fish to Amphibious animals. This distinction, -which, as will be seen immediately, is very important for the genealogy -of the Vertebrate animals, increases the original number of Vertebrate -classes from four to eight. - -In most recent times a ninth class of Vertebrata has been added to these -eight classes. Gegenbaur's recently published investigations in -comparative anatomy prove that the remarkable class of _Sea-dragons_ -(Halisauria), which have hitherto been included among Reptiles, must be -considered quite distinct from these, and as a separate class which -branched off from the Vertebrate stock, even before the Amphibious -animals. To it belong the celebrated large Ichthyosauri and Plesiosauri -of the oolitic and chalk periods, and the older Simosauri of the Trias -period, all of which are more closely allied to Fish than to Amphibious -animals. - -These nine classes of Vertebrate animals are, however, by no means of -the same genealogical value. Hence we must divide them, as I have -already shown in the Systematic Survey on p. 133, into four distinct -main-classes or tribes. In the first place, the three highest classes, -Mammals, Birds, and Reptiles, may be comprised as a natural main-class -under the name of _Amnion animals_ (Amnionata). The _Amnion-less -animals_ (Anamnionata), naturally opposed to them as a second -main-class, include the four classes of Batrachians, Sea-dragons, -Mud-fish, and Fishes. The seven classes just named, the Anamnionata as -well as the Amnionata, agree among one another in numerous -characteristics, which distinguish them from the two lowest classes -(the single-nostriled and tubular-hearted animals). Hence we may unite -them in the natural main group of _Double-nostriled_ animals -(Amphirrhina). Finally, these Amphirrhina on the whole are much more -closely related to those animals with round mouths or single nostrils -than to the skull-less or tube-hearted animals. We may, therefore, with -full justice class the single and double-nostriled animals into one -principal main group, and contrast them as _animals with skulls_ -(Craniota), or _bulbular hearts_ (Pachycardia), to the one class of -_skull-less animals_, or animals with _tubular hearts_. This -classification of the Vertebrate animals proposed by me renders it -possible to obtain a clear survey of the nine classes in their most -important genealogical relations. The systematic relationship of these -groups to one another may be briefly expressed by the following table. - - - A. - =Skull-less Animals= 1. Tubular hearts 1. Leptocardia - (+Acrania+) - - { _a._ Single nostriled - { animals { 2. Round-mouths 2. Cyclostoma - B. { _Monorrhina_ { - =Animals with= { - =Skulls= { b. Double { { 3. Fish 3. Pisces - (+Craniota+) { nostriled { I. Non-Amnionate { 4. Mud-fish 4. Dipneusta - { animals { Anamnia { 5. Sea-dragons 5. Halisauria - or { { { 6. Batrachians 6. Amphibia - { _Amphirrhina_ { - =Thick Hearts= { { II. Amnionate. { 7. Reptiles 7. Reptilia - (+Pachycardia+) { { Amniota { 8. Birds 8. Aves - { { { 9. Mammals 9. Mammalia - - -The only one representative of the first class, the small _lanceolate -fish_, or Lancelet (Amphioxus lanceolatus) (Plate XIII. Fig. _B_), -stands at the lowest stage of organization of all the Vertebrate -animals known to us. This exceedingly interesting and important animal, -which throws a surprising light upon the older roots of our pedigree, is -evidently the last of the Mohicans--the last surviving representative of -a lower class of Vertebrate animals, very rich in forms, and very highly -developed during the primordial period, but which unfortunately could -leave no fossil remains on account of the absence of all solid skeleton. -The Lancelet still lives widely distributed in different seas; for -instance, in the Baltic, North Sea, and Mediterranean, where it -generally lies buried in the sand on flat shores. The body, as the name -indicates, has the form of a narrow lanceolate leaf, pointed at both -extremities. When full grown it is about two inches long, of a white -colour and semi-transparent. Externally, the little lanceolate animal is -so little like a vertebrate animal that Pallas, who first discovered it, -regarded it as an imperfect naked snail. It has no legs, and neither -head, skull, nor brain. Externally, the fore end of the body can be -distinguished from the hinder end only by the open mouth. But still the -Amphioxus in its internal structure possesses those most important -features, which distinguish all Vertebrate animals from all Invertebrate -animals, namely, the spinal rod and spinal marrow. The _spinal rod_ -(Chorda dorsalis) is a straight, cylindrical, cartilaginous staff, -pointed at both ends, forming the central axis of the internal skeleton, -and the basis of the vertebral column. Directly above the spinal rod, on -its dorsal side, lies the _spinal marrow_ (medulla spinalis), likewise -originally a straight but internally hollow cord, pointed at both ends. -This forms the principal piece and centre of the nervous system in all -Vertebrate animals. (Compare above vol. i. p. 303.) In all Vertebrate -animals without exception, man included, these important parts of the -body during the embryological development out of the egg, originally -begin in the same simple form, which is retained throughout life by the -Amphioxus. It is only at a later period that the brain develops by the -expansion of the fore end of the spinal marrow, and out of the spinal -rod the skull which encloses the brain. As these two important organs do -not develop at all in the Amphioxus, we may justly call the class -represented by it, _Skull-less animals_ (Acrania), in opposition to all -the others, namely, to the _animals with skulls_ (Craniota). The -Skull-less animals are generally called _tubular-hearted_ (Leptocardia), -because a centralized heart does not as yet exist, and the blood is -circulated in the body by the contractions of the tubular blood-vessels -themselves. The Skulled animals, which possess a centralized, -thick-walled, bulb-shaped heart, ought then by way of contrast to be -called _bulbular-hearted_ animals (Pachycardia). - -[Illustration: _Ascidia (A.) and Amphioxus (B.)_ Pl. XII. - - E. Haeckel del. Legesse sc.] - -Animals with skulls and central hearts evidently developed gradually in -the later primordial period out of those without skulls and with tubular -hearts. Of this the ontogeny of skulled animals leaves no doubt. But -whence are these same skull-less animals derived? It is only very lately -that an exceedingly surprising answer has been given to this important -question. From Kowalewsky's investigations, published in 1867, on the -individual development of the Amphioxus and the adhering Sea-squirts -(Ascidia) belonging to the class of mantled animals (Tunicata), it has -been proved that the ontogenies of these two entirely different looking -animal-forms agree in the first stage of development in a most -remarkable manner. The freely swimming larvæ of the Ascidians (Plate -XII. Fig. _A_) develop the undeniable beginning of a spinal marrow (Fig. -5 _g_) and of a spinal rod (Fig. 5 _c_), and this moreover in entirely -the same way as does the Amphioxus. (Plate XIII. Fig. _B_.) It is true -that in the Ascidians these most important organs of the Vertebrate -animal-body do not afterwards develop further. The Ascidians take on a -retrograde transformation, become attached to the bottom of the sea, and -develop into shapeless lumps, which when looked upon externally would -scarcely be supposed to be animals. (Plate XIII. Fig. _A_.) But the -spinal marrow, as the beginning of the central nervous system, and the -spinal rod, as the first basis of the vertebral column, are such -important organs, so exclusively characteristic of Vertebrate animals, -that we may from them with certitude infer the true blood relationship -of Vertebrate with Tunicate animals. Of course we do not mean to say by -this, that Vertebrate animals are derived from Tunicate animals, but -merely that both groups have arisen out of a common root, and that the -Tunicates, of all the Invertebrata, are the nearest blood relations of -the Vertebrates. It is quite evident that genuine Vertebrate animals -developed progressively during the primordial period (and the skull-less -animals first) out of a group of worms, from which the degenerate -Tunicate animals arose in another and a retrograde direction. (Compare -the more detailed explanation of Plates XII. and XIII. in the Appendix.) - -Out of the Skull-less animals there developed, in the first instance, a -second low class of Vertebrate animals, which still stands far below -that of fish, and which is now represented only by the Hags (Myxinoida) -and Lampreys (Petromyzonta). This class also, on account of the absence -of all solid parts, could, unfortunately, as little as the Skull-less -animals leave fossil remains. From its whole organization and ontogeny -it is quite evident that it represents a very important intermediate -stage between the Skull-less animals and Fishes, and that its few still -existing members are only the last surviving remains of a probably very -highly developed animal group which existed towards the end of the -primordial period. On account of the curious mouth possessed by the Hags -and Lampreys, which they use for sucking, the whole class is usually -called _Round-mouthed_ animals (Cyclostoma). The name of -_Single-nostriled_ animals (Monorrhina) is still more characteristic. -For all Cyclostoma possess a simple, single nasal tube, whereas, in all -other Vertebrate animals (with the exception of the Amphioxus) the nose -consists of two lateral halves, a right and a left nostril. We are -therefore enabled to comprise these latter (Anamnionata and Amnionata) -under the heading, _double-nostriled_ animals (Amphirrhina). All the -Amphirrhina possess a fully developed jaw-skeleton (upper and under -jaw), whereas it is completely wanting in the Monorrhina. - -Apart also from the peculiar nasal formation, and the absence of jaws, -the Single-nostriled animals are distinguished from those with double -nostrils by many peculiarities. Thus they want the important sympathetic -nervous system, and the spleen which the Amphirrhina possess. Of the -swimming bladder, and the two pairs of legs--which all double-nostriled -animals have, at least in their embryonic conditions--not a trace exists -in the Single-nostriled animals, which is the case also in the -Skull-less animals. Hence, we are surely justified in completely -separating the Monorrhina, as we have separated the Skull-less animals, -from the Fishes, with which they have hitherto been erroneously classed. - -[Illustration: _Ascidia (A.) and Amphioxus (B.)_ Pl. XIII. - - E. Haeckel del. Lagesse sc.] - -We owe our first accurate knowledge of the Monorrhina, or Cyclostoma, to -the great zoologist, Johannes Müller of Berlin; his classical work on -the "Comparative Anatomy of the Myxinoida" forms the foundation of our -modern views on the structure of the Vertebrate animals. He -distinguished two distinct groups among the Cyclostoma, which we shall -consider as sub-classes. - -The first sub-class consists of the Hags (Hyperotreta, or Myxinoida). -They live in the sea as parasites upon other fish, into whose skin they -penetrate (Myxine, Bdellostoma). Their organ of hearing has only one -annular canal, and their single nasal tube penetrates the palate. The -second sub-class, that of Lampreys, or Prides (Hyperoartia, or -Petromyzontia) is more highly developed. It includes the well-known -Lamperns, or Nine-eyes, of our rivers (Petromyzon fluviatilis), with -which most persons are acquainted. They are represented in the sea by -the frequently larger marine or genuine Lampreys (Petromyzon marinus). -The nasal tube of these single-nostriled animals does not penetrate the -palate, and in the auricular organ there are two annular canals. - - -SYSTEMATIC SURVEY - -_Of the 4 Main-classes, 9 Classes, and 26 Sub-classes of Vertebrata._ - -Gen. Morph. vol. ii. Plate VII. pp. 116-160. - - - ====================================================================================== - I. =Skull-less= (+Acrania+), or =Tube-hearted= (+Leptocardia+). - - Vertebrata without head, without skull and brain, without centralized heart. - -------------------------------------------------------------------------------------- - 1. =Skull-less= I. Tube-hearted { 1. Lancelet 1. Amphioxus - +Acrania+ _Leptocardia_ { - -------------------------------------------------------------------------------------- - - II. =Animals with skulls= (+Craniota+) and with =thick-walled hearts= (+Pachycardia+). - Vertebrata with head, with skull and brain, with centralized heart. - - ====================================================================================== - _Main-classes_ | _Classes_ | _Sub-classes_ | _Systematic Name_ - _of the Skulled_ | _of the_ | _of the_ | _of the_ - _Animals._ | _Skulled Animals._ | _Skulled Animals._ | _Sub-classes._ - -------------------------------------------------------------------------------------- - 2. =Single-Nostriled= { II. Round mouths { 2. Hags, or Mucous 2. Hyperotreta - +Monorrhina+ { _Cyclostoma_ { Fish (Myxinoida) - { { 3. Lampreys, or 3. Hyperoartia - { { Pride (Petromyzontia) - - - { III. Fish { 4. Primæval fish 4. Selachii - { _Pisces_ { 5. Ganoid fish 5. Ganoides - { { 6. Osseous fish 6. Teleostei - { - { IV. Mud-fish { 7. Mud-fish 7. Protopteri - 3. =Non-amnionate= { _Dipneusta_ { - { - +Anamnionata+ { { 8. Primæval 8. Simosauria - { V. Sea-dragons { dragons - { _Halisauri_ { 9. Snake-dragons 9. Plesiosauria - { { 10. Fish-dragons 10. Ichthyosauria - { - { VI. Batrachians { 11. Mailed Batrachians 11. Phractamphibia - { _Amphibia_ { 12. Naked Batrachians 12. Lissamphibia - - - 4. =Amnion= { VII. Reptiles { 13. Primary reptiles 13. Tocosauria - =Animals= { _Reptilia_ { 14. Lizards 14. Lacertilia - +Amnionata+ { { 15. Serpents 15. Ophidia - { { 16. Crocodiles 16. Crocodilia - { { 17. Tortoises 17. Chelonia - { { 18. Flying reptiles 18. Pterosauria - { { 19. Dragons 19. Dinosauria - { { 20. Beaked reptiles 20. Anomodontia - { - { VIII. Birds { 21. Long-tailed 21. Saururæ - { _Aves_ { 22. Fan-tailed 22. Carinatæ - { { 23. Bush-tailed 23. Ratitæ - { - { IX. Mammals { 24. Cloacal animals 24. Monotrema - { _Mammalia_ { 25. Pouched animals 25. Marsupialia - { { 26. Placental animals 26. Placentalia - - ---------------------------------------------------------------- - - 9. Mammals - _Mammalia_ - 8. Birds | - _Aves_ | - | | - 7. Reptiles | - _Reptilia_ | - 5. Sea-dragons | | - _Halisauria_ \-------v--------/ - | | - Osseous fish | =Amnion Animals= - _Teleostei_ 4. Mud-fish | +Amniota+ - | _Dipneusta_ | | - | | | | - | | | 6. Batrachians - Ganoid fish | | _Amphibia_ - _Ganoidei_ | | | - | | | | - | \--------------v--------------/ - | | - | Vertebrate animals breathing through lungs - | _Amphipneumones_ - | | - | | - \------------v-----------------/ - Primæval fish Selachii - 3. Fishes _Pisces_ - =Double-nostriled= +Amphirrhina+ - | 2. Round-mouthed - | _Cyclostoma_ - | | - | | - \--------------------v-------------/ - =Single-nostriled= Monorrhina - =Animals with skulls= +Craniota+ - - 1. Tube-hearted | - _Leptocardia_ | - | | - | | - \---------v------/ - _Ascidiæ_ | - Sea-barrels | =Skull-less Animals= - _Thaliacea_ | +Acrania+ - | | =Vertebrate Animals= - | | +Vertebrata+ - \----v----/ | - | | - =Tunicate Animals= | - +Tunicata+ | - | | - | | - \-----------v---------/ - | - Worms - _Vermes_ - - -All existing Vertebrate animals, with the exception of the Monorrhina -and Amphioxus just mentioned, belong to the group which we designate as -Double-nostriled animals (Amphirrhina). All these animals possess (in -spite of the great variety in the rest of their forms) a nose consisting -of two lateral halves, a jaw-skeleton, a sympathetic nervous system, -three annular canals connected with the auricular sac, and a spleen. -Further, all Double-nostriled animals possess a bladder-shaped expansion -of the gullet, which, in Fish, has developed into the swimming bladder, -but in all other Double-nostriled animals into lungs. Finally, in all -Double-nostriled animals there exist in the youngest stage of growth the -beginnings of two pairs of extremities, or limbs, a pair of fore legs, -or breast fins, and a pair of hinder legs, or ventral fins. One of these -pairs of legs sometimes degenerates (as in the case of eels, whales, -etc.), or both pairs of legs (as in Cæciliæ and serpents) either -degenerate or entirely disappear; but even in these cases there exists -some trace of their original beginning in an early embryonic period, or -the useless remains of them may be found in the form of rudimentary -organs. (Compare above, vol. i. p. 13.) - -From all these important indications we may conclude with full assurance -that all double-nostriled animals are derived from a single common -primary form, which developed either directly or indirectly during the -primordial period out of the Monorrhina. This primary form must have -possessed the organs above mentioned, and also the beginning of a -swimming bladder and of two pairs of legs or fins. It is evident, that -of all still living double-nostriled animals, the lowest forms of sharks -are most closely allied to this long since extinct, unknown, and -hypothetical primary form, which we may call the Primary -Double-nostriled animals (Proselachii). We may therefore look upon the -group of primæval fish, or Selachii, to which the _Proselachii_ probably -belonged, as a primary group, not only of the Fish class, but of the -whole main-class of double-nostriled animals. - -The class of _Fish_ (Pisces) with which we accordingly begin the series -of Double-nostriled animals, is distinguished from the other six classes -of the series by the swimming bladder never developing into lungs, but -acting only as a hydrostatic apparatus. Agreeing with this, we find that -in fish the nose is formed by two blind holes in front of the mouth, -which never pierce the palate so as to open into the cavity of the -mouth. In the other six classes of double-nostriled animals, both -nostrils are changed into air passages which pierce the palate, and thus -conduct air to the lungs. Genuine fish (after the exclusion of the -Dipneusta) are accordingly the only double-nostriled animals which -exclusively breathe through gills and never through lungs. In accordance -with this, they all live in water, and both pairs of their legs have -retained the original form of paddling fins. - - -SYSTEMATIC SURVEY - -_Of the 7 Legions and 15 Orders of the Fishes._ - - - --------------------------------------------------------------------------------- - _Sub-classes_ | _Legions_ | _Orders_ | _Examples_ - _of_ | _of_ | _of_ | _from_ - _Fishes._ | _Fishes._ | _Fishes._ | _the Orders._ - --------------------------------------------------------------------------------- - { - { { 1. Sharks Sharks, dog-fish - { I. Transverse { _Squalacei_ - A. { mouths { 2. Rays Spiked rays, electric - =Primæval= { _Plagiostomi_ { _Rajacei_ rays, etc. - =Fish= { - +Selachii+ { II. Sea-Cats { 3. Sea-Cats Chimæra, Calorrhynchias - { _Holocephali_ { _Chimæracei_ - - - { { 4. Buckler-heads Cephalaspidæ, Placoderma, - { III. Mailed Ganoid { _Pamphracte_ etc. - { Fish { 5. Sturgeons Spoon-sturgeons, sturgeons, - { _Tabuliferi_ { _Sturiones_ sterlet, etc. - { - { { 6. _Efulcri_ Double-finned - B. { IV. Angular-scaled { 7. _Fulcrati_ Palæoniscus, bony pike, - =Ganoid= { Ganoid Fish { etc. - =Fish= { _Rhombiferi_ { 8. _Semæopteri_ African finny pike, etc. - +Ganoides+ { - { V. Round-scaled { 9. _Coeloscolopes_ Holoptychius, Coelacanthides, - { Ganoid Fish { etc. - { _Cycliferi_ { 10. _Pycnoscolopes_ Coccolepida, Amiadæ, - etc. - - { VI. Osseous Fish { - { with an air { 11. Herring species Herrings, salmon, carp, - { passage to the { _Thrissogenes_ etc. - C. { swimming { 12. Eel species Eels, snake eels, electric - =Osseous= { bladder { _Enchelygenes_ eels, etc. - =Fish= { _Physostomi_ { - +Teleostei+ { - { VII. Osseous Fish { 13. _Stichobranchii_ Perch, wrasse, turbot, - { without an air { etc. - { passage to the { 14. _Plectognathi_ Trunk fish, globe fish, - { swimming { etc. - { bladder { 15. _Lophobranchii_ Pipe fish, sea horses, - { _Physoclisti_ { etc. - - ---------------------------------------------------------------- - -PEDIGREE OF THE NON-AMNIONATE CRANIOTA. - - - Plectognathi Anura - | Lophobranchia Peromela | - | | | | - | | | Sozura - \-------v-----/ Labyrinthodonta | | - | | | | - Stichobranchia | | | - +Physoclisti+ \--v-----/ | - | | | - Enchelygenes | Ganocephala Sozobranchia - | | +Phractamphibia+ +Lissamphibia+ - | | | | - \--v---/ | | - | \-------v-------/ - | | - Thrissogenes +Amphibia+ - +Physostomi+ Semæopteri | - +Teleostei+ | | - | | Protopteri | - | Fulcrati | | | Plesiosauria - Pycnoscolopes | | | | Icthyosauria | - | | | | | | | - Coeloscolopes Efulcri | | | | | - +Cycliferi+ +Rhombiferi+ | | | | - (Cycloganoides) (Rhomboganoides) | | | | - | | | | | | - \---------v--------/ | | \----v-----/ - | +Dipneusta+ | | - Placoderma | | Simosauria - Sturiones | | | +Halisauria+ - | | | | | - Cephalaspidæ | Rajacei \-----------v--------/ - | | | | - | | | Amphipneumona - \-----v-------/ | | - | | | - Pamphracti | | - +Tabuliferi+ | | - (Placoganoides) | Chimæracei | - +Ganoides+ | +Holocephali+ | - | | | | - Squalacei | | | - | | | | - \--------v---------/ | | - | | | - +Plagiostomi+ | | - | | | - \-------------v---------------------/ - | - +Selachii+ - +Fish+ - +Amphirrhina+ - | Cyclostoma - | +Monorrhina+ - | | - \-------v---------/ - | - +Craniota+ - - -Genuine fish are divided into three distinct sub-classes, namely, -Primæval fish, Ganoid fish, and Osseous fish. The oldest of these, where -the original form has been most faithfully preserved, is that of the -_Primæval fish_ (Selachii). Of these there still exist Sharks (Squali), -and Rays (Rajæ), which are classed together as cross-mouthed fishes -(Plagiostomi), and the strange and grotesquely formed Sea-cats, or -_Chimæracei_ (Holocephali). These primary fish of the present day, which -are met with in all seas, are only poor remains of the prevailing animal -groups, rich in forms, which the Selachii formed in the earlier periods -of the earth's history, and especially during the palæolithic period. -Unfortunately all Primæval fish possess a cartilaginous, never a -completely osseous skeleton, which is but little, if at all, capable of -being petrified. The only hard parts of the body which could be -preserved in a fossil state, are the teeth and fin-spikes. These are -found in the older formations in such quantities, varieties, and sizes, -that we may, with certainty, infer a very considerable development of -Primæval fish in those remote ages. They are even found in the Silurian -strata, which contain but few remains of other Vertebrata, such as -Enamelled fish (and these only in the most recent part, that is, in the -upper Silurian). By far the most important and interesting of the three -orders of Primæval fish are Sharks; of all still living double-nostriled -animals, they are probably most closely allied to the original primary -form of the whole group, namely, to the Proselachii. Out of these -Proselachii, which probably differed but little from genuine Sharks, -Enamelled fish, and the present Primæval fish, in all probability, -developed in one direction, and the Dipneusta, Sea-dragons, and Amphibia -in another. - -The _Ganoid_, or _Enamelled fish_ (Ganoides), in regard to their anatomy -stand midway between the Primæval and the Osseous fish. In many -characteristics they agree with the former, and in many others with the -latter. Hence, we infer that genealogically they form the transition -from Primæval to Osseous fish. The Ganoids are for the most part -extinct, and more nearly so than the Primæval fish, whereas they were -developed in great force during the entire palæolithic and mesolithic -periods. Ganoid fish are divided into three legions according to the -form of their external covering, namely, Mailed, Angular-scaled, and -Round-scaled. The _Mailed Ganoid fish_ (Tabuliferi) are the oldest, and -are directly allied to the Selachii, out of which they originated. -Fossil remains of them, though rare, are found even in the upper -Silurian (Pteraspis ludensis of the Ludlow strata). Gigantic species of -them, coated with strong bony plates, are found in the Devonian system. -But of this legion there now lives only the small order of Sturgeons -(Sturiones), including the Spade-sturgeons (Spatularidæ), and those -Sturgeons (Accipenseridæ) to which belong, among others, the Huso, which -yields isinglass, or sturgeon's sound, and the Caviar-sturgeon, whose -eggs we eat in the shape of caviar, etc. Out of the mailed Ganoid fish, -the angular and round-scaled ones probably developed as two diverging -branches. The _Angular-scaled Ganoid fish_ (Rhombiferi)--which can be -distinguished at first sight from all other fish by their square or -rhombic scales--are at present represented only by a few survivors, -namely, the Finny Pike (Polypterus) in African rivers (especially the -Nile), and by the Bony Pike (Lepidosteus) in American rivers. Yet during -the palæolithic and the first half of the mesolithic epochs this legion -formed the most numerous group of fishes. The third legion, that of -_Round-scaled Ganoid fish_ (Cycliferi), was no less rich in forms, and -lived principally during the Devonian and Coal periods. This legion, of -which the Bald Pike (Amia), in North American rivers, is the only -survivor, was especially important, inasmuch as the third sub-class of -fish, namely, Osseous fish, developed out of it. - -_Osseous fish_ (Teleostei) include the greater portion of the fish of -the present day. Among these are by far the greater portion of marine -fish, and all of our fresh-water fish except the Ganoid fish just -mentioned. This class is distinctly proved by numerous fossils to have -arisen about the middle of the Mesolithic epoch out of Ganoid fish, and -moreover out of the Round-scaled, or Cycliferi. The Thrissopidæ of the -Oolitic period (Thrissops, Leptolepis, Tharsis), which are most closely -allied to the herrings of the present day, are probably the oldest of -all Osseous fish, and have directly arisen out of Round-scaled Ganoid -fish, closely allied to the existing Amia. In the older Osseous fish of -the legion called _Physostomi_, as also in the Ganoides, the swimming -bladder throughout life was connected with the throat by a permanent air -passage (a kind of windpipe). This is still the case with all the fish -belonging to this legion, namely, with herrings, salmon, carp, shad, -eels, etc. However, during the chalk period this air passage, in some of -the Physostomi, became constricted and closed, and the swimming bladder -was thus completely separated from the throat. Hence there arose a -second legion of Osseous fish, the _Physoclisti_, which did not attain -their actual development until the tertiary epoch, and soon far -surpassed the Physostomi in variety. To this legion belong most of the -sea fish of the present day, especially the large families of the -Turbot, Tunny, Wrasse, Crowfish, etc., further, the Lock-jaws -(Plectognathi), Trunk fish, and Globe-fish and the Bushy-gills -(Lophobranchi), viz., Pipe-fish, and Sea-horses. There are, however, -only very few Physoclisti among our river fish, for instance, Perch and -Sticklebacks; the majority of river fish are Physostomi. - -Midway between genuine Fish and Amphibia is the remarkable class of -_Mud-fish_, or _Scaly Sirens_ (Dipneusta, or Protopteri). There now -exist only a few representatives of this class, namely, the American -Mud-fish (Lepidosiren paradoxa) in the region of the river Amazon, and -the African Mud-fish (Protopterus annectens) in different parts of -Africa. A third large Salamander-fish (Ceratodus Fosteri) has lately -been discovered in Australia. During the dry season, that is in summer, -these strange animals bury themselves in a nest of leaves in the dry -mud, and then breathe air through lungs like the Amphibia. But during -the wet season, in winter, they live in rivers and bogs, and breathe -water through gills like fish. Externally, they resemble fish of the eel -kind, and are like them covered with scales; in many other -characteristics also--in their internal structure, their skeleton, -extremities, etc.--they resemble Fish more than Amphibia. But in certain -features they resemble the Amphibia, especially in the formation of -their lungs, nose, and heart. There is consequently an endless dispute -among zoologists, as to whether the Mud-fish are genuine Fish or -Amphibia. Distinguished zoologists have expressed themselves in favour -of both opinions. But in fact, owing to the complete blending of -characteristics which they present, they belong neither to the one nor -to the other class, and are probably most correctly dealt with as a -special class of Vertebrata, forming the transition between Fishes and -Amphibians. The still living Dipneusta are probably the last surviving -remains of a group which was formerly rich in forms, but has left no -fossil traces on account of the want of a solid skeleton. In this -respect, these animals are exactly like the Monorrhina and the -Leptocardia. However, teeth are found in the Trias which resemble those -of the living Ceratodus. Possibly the extinct Dipneusta of the -palæolithic period, which developed in the Devonian epoch out of -primæval fish, must be looked upon as the primary forms of the Amphibia, -and thus also of all higher Vertebrata. At all events the unknown forms -of transition--from Primæval fish to Amphibia--were probably very like -the Dipneusta. - -A very peculiar class of Vertebrate animals, long since extinct, and -which appears to have lived only during the secondary epoch, is formed -by the remarkable _Sea-dragons_ (Halisauria, or Enaliosauria, also -called Nexipoda, or Swimming-footed animals). These formidable animals -of prey inhabited the mesolithic oceans in great numbers, and were of -most peculiar forms, sometimes from thirty to forty feet in length. From -many and excellently preserved fossil remains and impressions, both of -the entire body of Sea-dragons as well as of single parts, we have -become very accurately acquainted with the structure of their bodies. -They are usually classed among Reptiles, whilst some anatomists have -placed them in a much lower rank, as directly allied to Fish. -Gegenbaur's recently published investigations, which place the structure -of their limbs in a true light, have led to the surprising conclusion -that the Sea-dragons form quite an isolated group, differing widely both -from Reptiles and Amphibia as well as from Fish. The skeleton of their -four legs, which are transformed into short, broad, paddling fins (like -those of fish and whales) furnishes us with a clear proof that the -Halisauria branched off from the main-stock of Vertebrata at an earlier -period than the Amphibia. For Amphibia, as well as the three higher -classes of Vertebrata, are all derived from a common primary form, which -possessed only _five_ toes or fingers on each leg. But the Sea-dragons -have (either distinctly developed or in a rudimentary condition as parts -of the skeleton of the foot) more than five fingers, as have also the -Selachians or Primæval fish. On the other hand, they breathed air -through lungs, like the Dipneusta, although they always swam about in -the sea. They, therefore, perhaps, in conjunction with the Dipneusta, -branched off from the Selachii, but did not develop into higher -Vertebrata; they form an extinct lateral line of the pedigree, which has -died out. - -The more accurately known Sea-dragons are classed into three orders, -distinct enough one from the other, namely, _Primæval Dragons_, _Fish -Dragons_, and _Serpent Dragons_. The _Primæval Dragons_ (Simosauria) are -the oldest Sea-dragons, and lived only during the Trias period. The -skeletons of many different genera of them are met with in the German -limestone known as "Muschel-kalk." They seem upon the whole to have been -very like the Plesiosauria, and are, consequently, sometimes united with -them into one order as Sauropterygia. The _Serpent Dragons_ -(Plesiosauria) lived in the oolitic and chalk periods together with the -Ichthyosauria. They were characterised by an uncommonly long thin neck, -which was frequently longer than the whole body, and carried a small -head with a short snout. When their arched neck was raised they must -have looked very like a swan; but in place of wings and legs they had -two pairs of short, flat, oval-paddling fins. - -The body of the _Fish Dragons_ (Ichthyosauria) was of an entirely -different form; these animals may be opposed to the two preceding orders -under the name of Fish-finners (Ichthyopterygia). They possessed a very -long extended body, like a fish, and a heavy head with an elongated, -flat snout, but a very short neck. Externally, they were probably very -like porpoises. Their tail was very long, whereas it was very short in -the members of the preceding orders. Also both pairs of paddling fins -are broader and show very different structure from that seen in the -other two orders. Probably the Fish Dragons and Serpent Dragons -developed as two diverging branches out of the Primæval Dragons; but it -is also possible that the Plesiosauria alone originated out of the -Simosauria, and that the Ichthyosauria were lower off-shoots from the -common stock. At all events, they must all be directly, or indirectly -derived from the Selachii, or Primæval fish. - -The succeeding classes of Vertebrata, the _Amphibia_ and the _Amniota_ -(Reptiles, Birds, and Mammals), owing to the characteristic structure -which they all exhibit of five toes to each foot, may all be derived -from a common primary form, which originated from the Selachii, and -which possessed five toes on each of its four limbs. When we find a less -number of toes than five, we can show that the missing ones must have -been lost in the course of time by adaptation. The oldest known -Vertebrata with five toes are the _Batrachias_ (Amphibia). We divide -this class into two sub-classes, namely, mailed Batrachians and naked -Batrachians, the first of which is distinguished by the body being -covered with bony plates or scales. - -The first and elder sub-class of Amphibia consists of the _Mailed -Batrachians_ (Phractamphibia), the oldest land living Vertebrata of -which fossil remains exist. Well-preserved fossil remains of them occur -in the coal, especially of those with _Enamelled heads_ (Ganocephala), -which are most closely allied to fish, namely, the Archegosaurus of -Saarbruck, and the Dendrerpeton of North America. There then follow at a -later period the gigantic _Labyrinth-toothed animals_ (Labyrinthodonta), -which are represented in the Permian system by Zygosaurus, but at a -later period, more especially in the Trias, by Mastodonsaurus, -Trematosaurus, Capitosaurus, etc. The shape of these formidable -rapacious animals seems to have been between that of crocodiles, -salamanders, and frogs, but in their internal structure they were more -closely related to the two latter, while by their solid coat of mail, -formed of strong bony plates, they resembled the first animals. These -gigantic mailed Batrachians seem to have become extinct towards the end -of the Triassic period. No fossil remains of mailed Batrachia are known -during the whole of the subsequent periods. However, the still living -blind Snakes, or _Cæciliæ_ (Peromela)--small-scaled Phractamphibia of -the form and the same mode of life as the earth-worm--prove that this -sub-class continued to exist, and never became completely extinct. - -The second sub-class of Amphibia, the _naked Batrachia_ (Lissamphibia), -probably originated even during the primary and secondary epochs, -although fossil remains of them are first found in the tertiary epoch. -They are distinguished from mailed Batrachia by possessing a naked -smooth, and slimy skin, entirely without scales or coat of mail. They -probably developed either out of a branch of the Phractamphibia, or out -of the same common root with them. The ontogeny of the three still -living orders of naked Batrachia--the gilled Batrachia, tailed -Batrachia, and frog Batrachia--distinctly repeats the historical course -of development of the whole sub-class. The oldest forms are the gilled -Batrachia (Sozobranchia), which retain throughout life the original -primary form of naked Batrachia, and possess a long tail, together with -water-breathing gills. They are most closely allied to the Dipneusta, -from which, however, they differ externally by the absence of the coat -of scales. Most gilled Batrachia live in North America: among others of -the class is the Axolotl, or Siredon, already mentioned. (Compare above, -vol. i. p. 241.) In Europe the order is only represented by one form, -the celebrated "Olm" (Proteus anguinus), which inhabits the grotto of -Adelsberg and other caves in Carinthia, and which, from living in the -dark, has acquired rudimentary eyes which can no longer see (vol. i. p. -13). The order of Tailed Batrachia (Sozura) have developed out of the -gilled Batrachia by the loss of external gills; the order includes our -black and yellow spotted land Salamander (Salamandra maculata), and our -nimble aquatic Salamanders (Tritons). Many of them--for instance, the -celebrated giant Salamanders in Japan (Cryptobranchus Japonicus)--still -retain the gill-slits, although the gills themselves have disappeared. -All of them, however, retain the tail throughout life. Tritons -occasionally--when forced to remain in water always--retain their gills, -and thus remain at the same stage of development as gilled Batrachia. -(Compare above, vol. i. p. 241.) The third order, the _tailless_ or -_frog-like Batrachia_ (Anura), during their metamorphosis, not only lose -their gills, with which in early life (as so-called tadpoles) they -breathe in water, but also the tail with which they swim about. During -their ontogeny, therefore, they pass through the course of development -of the whole sub-class, they being at first _Gilled Batrachia_, then -_Tailed Batrachia_, and finally _Frog-like Batrachia_. The inference -from this is evidently, that _Frog-like Batrachia_ developed at a later -period out of _Tailed Batrachia_, as the latter had developed out of -_Gilled Batrachia_ which originally existed alone. - -In passing from the Amphibia to the next class of Vertebrata, namely, -Reptiles, we observe a very considerable advance in the progress of -organization. All the double-nostriled animals (Amphirrhina) up to this -time considered, and more especially the two larger classes of Fish and -Batrachia, agree in a number of important characteristics, which -essentially distinguish them from the three remaining classes of -Vertebrata--Reptiles, Birds, and Mammals. During the embryological -development of these latter, a peculiarly delicate covering, the _first -foetal membrane_, or _amnion_, which commences at the navel, is formed -round the embryo; this membrane is filled with the amnion-water, and -encloses the embryo or germ in the form of a bladder. On account of this -very important and characteristic formation, we may comprise the three -most highly developed classes of Vertebrata under the term -_Amnion-animals_ (Amniota). The four classes of double-nostriled animals -which we have just considered, in which the amnion is wanting (as is the -case in all lower Vertebrate animals, single-nostriled and skull-less -animals), may on the other hand be opposed to the others as _amnion-less -animals_ (Anamnia). - -The formation of the foetal membrane, or amnion, which distinguishes -reptiles, birds, and mammals from all other Vertebrata, is evidently a -very important process in their ontogeny, and in the phylogeny which -corresponds with it. It coincides with a series of other processes, -which essentially determine the higher development of Amnionate animals. -The first of these important processes is the _total loss of gills_, for -which reason the Amniota, under the name of _Gill-less animals_ -(Ebranchiata), were formerly opposed to all other Vertebrate animals -which breathed through gills (Branchiata). In all the Vertebrate already -discussed, we found that they either always breathed through gills, or -at least did so in early life, as in the case of Frogs and Salamanders. -On the other hand, we never meet with a Reptile, Bird, or Mammal which -at any period of its existence breathes through gills, and the -gill-arches and openings which do exist in the embryos, are, during the -course of the ontogeny, changed into entirely different structures, -viz., into parts of the jaw-apparatus and the organ of hearing. (Compare -above, vol. i. p. 307.) All Amnionate animals have a so-called cochlea -in the organ of hearing, and a "round window" corresponding with it. -These parts are wanting in the Amnion-less animals; moreover, their -skull lies in a straight line with the axis of the vertebral column. In -Amniotic animals the base of the skull appears bent in on the abdominal -side, so that the head sinks upon the breast. (Plate III. Fig. _C_, _D_, -_G_, _H_.) The organs of tears at the side of the eye also first develop -in the Amniota. - -The question now is, When did this important advance take place in the -course of the organic history of the earth? When did the common ancestor -of all Amniota develop out of a branch of the Non-amniota, to wit, out -of the branch of the Amphibia? - -To this question, the fossil remains of Vertebrata do not give us a very -definite, but still they do give an approximate, answer. For with the -exception of two lizard-like animals found in the Permian system (the -Proterosaurus and Rhopalodon), all the fossil remains of Amniota, as yet -known, belong to the _secondary_, _tertiary_, and _quaternary epochs_. -With regard to the two Vertebrata just named, it is still doubtful -whether they are genuine reptiles, or perhaps Amphibia of the salamander -kind. Their skeleton alone is known to us, and even this not perfectly. -Now as we know nothing of the characteristic features of their soft -parts, it is quite possible that the Proterosaurus and Rhopalodon were -non-amnionate animals more closely allied to Amphibia than to Reptiles; -possibly they belonged to the transition form between the two classes. -But, on the other hand, as undoubted fossil remains of Amniota have been -found as early as the Trias, it is probable that the _main class of -Amniota_ first developed in the Trias, that is, in the beginning of the -Mesolithic epoch. As we have already seen, this very period is evidently -one of the most important turning points in the organic history of the -earth. The palæolithic fern forests were then replaced by the pine -forests of the Trias period; important transformations then took place -in many of the classes of Invertebrata. Articulated marine lilies -(Colocrina) developed out of the plated ones (Phatnocrina.) The -Autechinidæ, or sea-urchins with only twenty rows of plates, took the -place of the palæolithic Palechinidæ, the sea-urchins with more than -twenty rows of plates. The Cystideæ, Blastoideæ, Trilobita, and other -characteristic groups of Invertebrata of the primary period became -extinct. It is no wonder that transforming conditions of adaptation -powerfully influenced the Vertebrate tribes also in the beginning of the -Trias period, and caused the origin of Amniotic animals. - -If, however, the two Lizard and Salamander-like animals of the Permian -system, the Proterosaurus and Rhopalodon, are considered genuine -Reptiles, and consequently the most ancient Amniota, then the origin of -this main class must necessarily have taken place in the preceding -period, towards the end of the primary, namely, in the Permian period. -However, all other remains of Reptiles, which were formerly believed to -have been found in the Permian and the Coal system, or even in the -Devonian system, have been proved to be either not remains of Reptiles -at all, or to belong to a more recent date (for the most part to the -Trias). (Compare Plate XIV.) - -The common hypothetical primary form of all Amniotic animals, which we -may call _Protamnion_, and which was possibly nearly related to the -Proterosaurus, very probably stood upon the whole midway between -salamanders and lizards, in regard to its bodily formation. Its -descendants divided at an early period into two different lines, one of -which became the common primary form of Reptiles and Birds, the other -the primary form of Mammals. - -Of all the three classes of Amniota, _Reptiles_ (Reptilia, or Pholidota, -also called Sauria in the widest sense), remain at the lowest stage of -development, and differ least from their ancestors, the Amphibia. Hence -they were formerly universally included among them, although their whole -organization is much more like that of Birds than Amphibia. There now -exist only four orders of Reptiles, namely,--Lizards, Serpents, -Crocodiles, and Tortoises. They, however, form but a poor remnant of the -exceedingly various and highly developed host of Reptiles which lived -during the Mesolithic, or Secondary epoch, and predominated over all -other Vertebrata. The immense development of Reptiles during the -Secondary epoch is so characteristic that we could as well name it after -those animals as after the Gymnosperms (p. 111). Twelve of the -twenty-seven sub-orders, given on the accompanying table, and four of -the eight orders, belong exclusively to the secondary period. These -mesolithic groups are marked by an asterisk. All the orders, with the -exception of Serpents, are found fossilized even in the Jura and Trias -periods. - -[Illustration: _Pl. XIV._ - - [Horizontal axis:] - Branches, - Classes, - and Sub-Classes, - of the Vertebrate - Stem. - - Prochordata - Evertebrate - Forefathers - of the - Vertebrate - - Skull-less - (Acrania) - or - Tube-hearted - Fish, - (Leptocardia) - - Single - nostrilled - (Monorrhina) - or - Round-mouthed - Fishes - (Cyclostoma) - - Anamnia { Paired-nostrilled forms or Amphirrhina - { with gills, without Amnion. - Fish, Pisces - - Primeval - Fish, - Selachii. - - Enamelled - Fish, - Ganoides. - - Bony - Fish, - Teleostei. - - Mud - Fish, - Dipneusta. - - Sea-Dragons, - Halisauria. - - Frogs and - Newts, - Amphibia. - - Amniota { Paired nostrilled or Amphirrhina - { with Amnion, without gills. - - Reptiles, Reptilia. - - Primæval - Reptiles, - Tocosauria. - - Lizards, - Lacertilia. - - Snakes, - Ophidia. - - Crocodiles, - Crocodilia. - - Tortoises, - Chelonia. - - Flying - Reptiles, - Pterosauria. - - Dragons, - Dinosauria. - - Billed - Reptiles, - Anomodontia. - - Birds, - Aves. - - Suckling animals, Mammalia. - - Billed - Animals, - Monotrema. - - Pouched - Animals, - Marsupialia. - - Placental - Animals, - Placentalia. - - [Vertical axis:] - Cenolithic or - Tertiary Epoch. - - Pliocene - Age. - - Miocene - Age. - - Eocene - Age. - - Mesolithic or - Secondary Epoch. - - Chalk - Period. - - Jurassic - Period. - - Triassic - Period. - - Palæolithic or - Primary Epoch. - - Permian - Period. - - Coal - Period. - - Devonian - Period. - - Archilithic or - Primordial Epoch. - - Silurian - Period. - - Cambrian - Period. - - Laurentian - Period. - - [Legend:] - Single or - MONOPHYLETIC PEDIGREE - of the Stem of the - BACK-BONED ANIMALS - Based on Palæontology. - - Relative lengths of the 5 - Epochs in per centages. - - Quarternary Epoch 0.5 - Tertiary Epoch 2.3 - Secondary Epoch 11.5 - Primary Epoch 32.1 - Primordial Epoch 53.6 - ------ - _Total_ 100.0] - -In the first order, that of _Primary Reptiles_, or _Primary Creepers_ -(Tocosauria), we class the extinct _Thecodontia_ of the Trias, together -with those Reptiles which we may look upon as the common primary form of -the whole class. To the latter, which we may call _Primæval Reptiles_ -(Proreptilia), the Proterosaurus of the Permian system very probably -belongs. The seven remaining orders must be considered as diverging -branches, which have developed in different directions out of that -common primary form. The Thecodontia of the Trias, the only positively -known fossil forms of Tocosauria, were Lizards which seem to have been -like the still living monitor lizards (Monitor, Varanus). - - -SYSTEMATIC SURVEY - -_Of the 8 Orders and 27 Sub-orders of Reptiles._ - -(Those groups marked with * became extinct even during the Secondary -Period.) - - ----------------------------------------------------------------------------------- - | _Sub-orders_ | _Systematic Name_ | _A Generic Name_ - _Orders_ | _of_ | _of the_ | _as_ - _of Reptiles._ | _Reptiles._ | _Sub-orders._ | _an example._ - ----------------------------------------------------------------------------------- - I. =Primary= { 1. Primæval reptiles 1. Proreptilia * (Proterosaurus?) - =Reptiles= { - +Tocosauria+ { 2. 2. Thecodontia * Palæosaurus - - { 3. Cleft-tongued 3. Fissilingues Monitor - { 4. Thick-tongued 4. Crassilingues Iguana - II. =Lizards= { 5. Short-tongued 5. Brevilingues Anguis - +Lacertilia+ { 6. Ringed lizards 6. Glyptodermata Amphisbæna - { 7. Chameleons 7. Vermilingues Chamæleo - - { 8. Adders 8. Aglyphodonta Coluber - { 9. Tree serpents 9. Opisthoglypha Dipsas - III. =Serpents= { 10. 10. Proteroglypha Hydrophis - +Ophidia+ { 11. Vipers 11. Solenoglypha Vipera - { 12. Worm serpents 12. Opoterodonta Typhlops - - { 13. Amphicoela 13. Teleosauria * Teleosaurus - IV. =Crocodiles= { 14. Opisthocoela 14. Steneosauria * Steneosaurus - +Crocodilia+ { 15. Prosthocoela 15. Alligatores Alligator - - { 16. Sea tortoises 16. Thalassita Chelone - V. =Tortoises= { 17. River tortoises 17. Potamita Trionyx - +Chelonia+ { 18. Marsh tortoises 18. Elodita Emys - { 19. Land tortoises 19. Chersita Testudo - - { 20. Long-tailed 20. Rhamphorhynchi * Rhamphorhynchus - VI. =Flying= { Flying lizards - =Reptiles= { 21. Short-tailed 21. Pterodactyli * Pterodactylus - +Pterosauria+* { Flying lizards - - { 22. Giant dragons 22. Harpagosauria * Megalosaurus - VII. =Dragons= { 23. Elephantine 23. Therosauria * Iguanodon - +Dinosauria+* { dragons - - { 24. Dog-toothed 24. Cynodontia * Dicynodon - VIII. =Beaked= { 25. Toothless 25. Cryptodontia * Udenodon - =Reptiles= { 26. Kangaroo reptiles 26. Hypsosauria * Compsognathus - +Anomodontia+* { - { 27. Bird reptiles 27. Tocornithes * (Tocornis) - - -Of the four orders of reptiles now existing, and which, moreover, have -alone represented the class since the beginning of the tertiary epoch, -that of _Lizards_ (Lacertilia) is probably most closely allied to the -extinct Primary Reptiles, and especially through the monitors already -named. The class of _Serpents_ (Ophidia) developed out of a branch of -the order of lizards, and this probably not until the beginning of the -tertiary epoch. At least we at present only know of fossil remains of -serpents from the tertiary strata. _Crocodiles_ (Crocodilia) existed -much earlier; the Teleosauria and Steneosauria belonging to the class -are found fossil in large quantities even in the Jura; but the still -living alligators are first met with in a fossil state in the chalk and -tertiary strata. The most isolated of the four existing orders of -reptiles consists of the remarkable group of _Tortoises_ (Chelonia); -fossils of these strange animals are first met with in the Jura. In some -characteristics they are allied to Amphibia, in others, to Crocodiles, -and by certain peculiarities even to Birds, so that their true position -in the pedigree of Reptiles is probably far down at the root. The -extraordinary resemblance of their embryos to Birds, manifested even at -later stages of the ontogenesis, is exceedingly striking. - -The four extinct orders of Reptiles show among one another, and, with -the four existing orders just mentioned, such various and complicated -relationships, that in the present state of our knowledge we are obliged -to give up the attempt at establishing their pedigree. The most -deviating and most curious forms are the _Flying Reptiles_ -(Pterosauria); flying lizards, in which the extremely elongated fifth -finger of the hand served to support an enormous flying membrane. They -probably flew about, in the secondary period, much in the same way as -the bats of the present day. The smallest flying lizards were about the -size of a sparrow; the largest, however, with a breadth of wing of more -than sixteen feet, exceeded the largest of our living flying birds in -stretch of wing (condor and albatross). Numerous fossil remains of them, -of the long-tailed Rhamphorhynchia and of the short-tailed Pterodactylæ -are found in all the strata of the Jura and Chalk periods, but in these -only. - -Not less remarkable and characteristic of the Mesolithic epoch was the -group of _Dragons_ (Dinosauria, or Pachypoda). These colossal reptiles, -which attained a length of more than fifty feet, are the largest -inhabitants of the land which have ever existed on our globe; they lived -exclusively in the secondary epoch. Most of their remains are found in -the lower cretaceous system, more especially in the Wealden formations -of England. The majority of them were fearful beasts of prey (the -Megalosaurus from twenty to thirty, the Pelorosaurus from forty to fifty -feet in length). The Iguanodon, however, and some others lived on -vegetable food, and probably played a part in the forests of the chalk -period similar to that of the unwieldy but smaller elephants, -hippopotami, and rhinoceroses of the present day. - -The _Beaked Reptiles_ (Anomodontia), likewise also long since extinct, -but of which very many remarkable remains are found in the Trias and -Jura, were perhaps closely related to the Dragons. Their jaws, like -those of most Flying Reptiles and Tortoises, had become changed into a -beak, which either possessed only degenerated rudimentary teeth, or no -teeth at all. In this order, if not in the preceding one, we must look -for the primary parents of the bird class, which we may call Bird -Reptiles (Tocornithes). Probably very closely related to them was the -curious, kangaroo-like Compsognathus from the Jura, which in very -important characteristics already shows an approximation to the -structure of birds. - -The class of _Birds_ (Aves), as already remarked, is so closely allied -to Reptiles in internal structure and by embryonal development, that -they undoubtedly originated out of a branch of this class. Even a glance -at Plates II. and III. will show that the embryos of birds at a time -when they already essentially differ from the embryos of Mammals, are -still scarcely distinguishable from those of Tortoises and other -Reptiles. The cleavage of the yolk is partial in the case of Birds and -Reptiles, in Mammals it is total. The red blood-cells of the former -possess a kernel, those of the latter do not. The hair of Mammals -develops in closed follicles in the skin, but the feathers of birds and -also the scales of reptiles develop in hillocks on the skin. The lower -jaw of the latter is much more complicated than that of Mammals; the -latter do not possess the quadrate bone of the former. Whereas in -Mammals (as in the case of Amphibia) the connection between the skull -and the first neck vertebra is formed by two knobbed joints, or -condyles, in Birds and Reptiles those have become united into a single -condyle. The two last classes may therefore justly be united into one -group as Monocondylia, and contrasted to Mammals, or Dicondylia. - -The deviation of Birds from Reptiles, in any case, first took place in -the mesolithic epoch, and this moreover probably during the Trias. The -oldest fossil remains of birds are found in the upper Jura -(Archæopteryx). But there existed, even in the Trias period, different -Saurians (Anomodonta) which in many respects seem to form the transition -from the Tocosauria to the primary ancestors of Birds, the hypothetical -Tocornithes. Probably these Tocornithes were scarcely distinguishable -from other beaked lizards in the system, and were closely related to the -kangaroo-like Compsognathus from the Jura of Solenhofen. Huxley classes -the latter with the Dinosauria, and believes them to be the nearest -relations to the Tocornithes. - -The great majority of Birds--in spite of all the variety in the -colouring of their beautiful feathery dress, and in the formation of -their beaks and feet--are of an exceedingly uniform organization, in -much the same way as are the class of insects. The bird form has adapted -itself on all sides to the external conditions of existence, without -having thereby in any way essentially deviated from the strict -hereditary type of its characteristic structure. There are only two -small groups, the feather-tailed birds (Saururæ) and those of the -ostrich kind, which differ considerably from the usual type of bird, -namely, from those with keel-shaped breasts (Carinatæ), and hence the -whole class may be divided into three sub-classes. - -The first sub-class, the _Reptile-tailed_, or _Feather-tailed Birds_ -(Saururæ), are as yet known only through a single, and that an -imperfect, fossil impression, which, however, in being the oldest and -also a very peculiar fossil bird, is of great importance. This fossil is -the Primæval Griffin, or Archæopteryx lithographica, of which as yet -only one specimen has been found in the lithographic slate at -Solenhofen, in the Upper Jura system of Bavaria. This remarkable bird -seems on the whole to have been of the size and form of a large raven, -especially as regards the legs, which are in a good state of -preservation; head and breast unfortunately are wanting. The formation -of the wings deviates somewhat from that of other birds, but that of the -tail still more so. In all other birds the tail is very short and -composed of but few short vertebræ; the last of these have grown -together into a thin, bony plate standing perpendicularly, upon which -the rudder-feathers of the tail are attached in the form of a fan. The -Archæopteryx, however, has a long tail like a lizard, composed of -numerous (20) long thin vertebræ, and on every vertebra are attached -the strong rudder-feathers in twos, so that the whole tail appears -regularly feathered. This same formation of the tail part of the -vertebral column occurs transiently in the embryos of other birds, so -that the tail of the Archæopteryx evidently represents the original form -of bird-tail inherited from reptiles. Large numbers of similar birds -with lizard-tails probably lived during the middle of the secondary -period; accident has as yet, however, only revealed this one fossil. - -The _Fan-tailed_, or _Keel-breasted birds_ (Carinatæ), which form the -second sub-class, comprise all living Birds of the present day, with the -exception of those of the ostrich kind, or Ratitæ. They probably -developed out of Feather-tailed Birds during the first half of the -secondary period, namely, in the Jura or Chalk period, by the hinder -tail vertebræ growing together, and by the tail becoming shortened. Only -very few remains of them are known from the secondary period, and these -moreover only out of the last section of it, namely, from the Chalk. -These remains belong to a swimming bird of the albatross species, and a -wading bird like a snipe. All the other fossil remains of birds as yet -known have been found in the tertiary strata. - -The _Bushy-tailed_, or _Ostrich-like Birds_ (Ratitæ), also called -_Running Birds_ (Cursores), the third and last sub-class, is now -represented only by a few living species, by the African ostrich with -two toes, the American and Australian ostrich with three toes, by the -Indian cassowary and the four-toed kiwi, or Apteryx, in New Zealand. The -extinct giant birds of Madagascar (Æpyornis) and the New Zealand -Dinornis, which were much larger than the still living ostriches, also -belong to this group. The Birds of the ostrich kind--by giving up the -habit of flying, by the degeneration of the muscles for flying resulting -from this, and of the breast bone which serves as their support, and by -the corresponding stronger development of the hinder legs for -running--have probably arisen out of a branch of the Keel-breasted -birds. But possibly, as Huxley thinks, they may be the nearest relations -of the Dinosauria and of the Reptiles akin to them, especially of the -Compsognathus; at all events, the common primary form of all Birds must -be looked for among the extinct Reptiles. - - - - -CHAPTER XXI. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -IV. MAMMALS. - - - The System of Mammals according to Linnæus and - Blainville.--Three Sub-classes of Mammals (Ornithodelphia, - Didelphia, Monodelphia).--Ornithodelphia, or Monotrema.--Beaked - Animals (Ornithostoma).--Didelphia, or Marsupials.--Herbivorous - and Carnivorous Marsupials.--Monodelphia, or Placentalia - (Placental Animals).--Meaning of the Placenta.--Tuft - Placentalia.--Girdle Placentalia.--Disc - Placentalia.--Non-deciduates, or Indeciduata.--Hoofed - Animals.--Single and Double-hoofed Animals.--Whales.--Toothless - Animals.--Deciduates, or Animals with - Decidua.--Semi-apes.--Gnawing Animals.--Pseudo-hoofed - Animals.--Insectivora.--Beasts of Prey.--Bats.--Apes. - - -There are only a few points in the classification of organisms upon -which naturalists have always agreed. One of these few undisputed points -is the privileged position of the class of Mammals at the head of the -animal kingdom. The reason of this privilege consists partly in the -special interest, also in the various uses and the many pleasures, which -Mammals, more than all other animals, offer to man, and partly in the -circumstance that man himself is a member of this class. For however -differently in other respects man's position in nature and in the system -of animals may have been regarded, yet no naturalist has ever doubted -that man, at least from a purely morphological point of view, belongs -to the class of Mammals. From this there directly follows the -exceedingly important inference that man, by consanguinity also, is a -member of this class of animals, and has historically developed out of -long since extinct forms of Mammals. This circumstance alone justifies -us here in turning our especial attention to the history and the -pedigree of Mammals. Let us, therefore, for this purpose first examine -the groups of this class of animals. - -Older naturalists, especially considering the formation of the jaw and -feet, divided the class of Mammals into a series of from eight to -sixteen orders. The lowest stage of the series was occupied by the -whales, which seemed to differ most from man, who stands at the highest -stage, by their fish-like form of body. Thus Linnæus distinguished the -following eight orders: (1) Cetæ (whales); (2) Belluæ (hippopotami and -horses); (3) Pecora (ruminating animals); (4) Glires (gnawing animals -and rhinoceroses); (5) Bestiæ (insectivora, marsupials, and various -others); (6) Feræ (beasts of prey); (7) Bruta (toothless animals and -elephants); (8) Primates (bats, semi-apes, apes, and men). Cuvier's -classification, which became the standard of most subsequent zoologists, -did not rise much above that of Linnæus. Cuvier distinguished the -following eight orders: (1) Cetacea (whales); (2) Ruminantia (ruminating -animals); (3) Pachyderma (hoofed animals, with the exclusion of -ruminating animals); (4) Edentata (animals poor in teeth); (5) Rodentia -(gnawing animals); (6) Carnassia (marsupials, beasts of prey, -insectivora, and bats); (7) Quadrumana (semi-apes and apes); (8) Bimana -(man). - -The most important advance in the classification of Mammals was made as -early as 1816 by the eminent anatomist Blainville, who has already been -mentioned, and who first clearly recognised the three natural main -groups or sub-classes of Mammals, and distinguished them according to -the formation of their generative organs as _Ornithodelphia_, -_Didelphia_, and _Monodelphia_. As this division is now justly -considered by all scientific zoologists to be the best, on account of -solid foundation on the history of development, let us here keep to it -also. - -The first sub-class consists of the _Cloacal Animals_, or _Breastless -animals_, also called _Forked animals_ (Monotrema, or Ornithodelphia). -This class is now represented only by two species of living mammals, -both of which are confined to Australia and the neighbouring island of -Van Diemen's land, namely, the well-known Water Duck-bill -(Ornithorhynchus paradoxus) with the beak of a bird, and the less known -Beaked Mole (Echidna hystrix), resembling a hedgehog. Both of these -curious animals, which are classed in the order of _Beaked Animals_ -(Ornithostoma), are evidently the last surviving remnants of an animal -group formerly rich in forms, which alone represented the Mammalia in -the secondary epoch, and out of which the second sub-class, the -Didelphia, developed later, probably in the Jurassic period. -Unfortunately, we as yet do not know with certainty of any fossil -remains of this most ancient primary group of Mammals, which we will -call _Primary Mammals_ (Promammalia). Yet they possibly comprise the -oldest of all the fossil Mammalia known, namely, the Microlestes -antiquus, of which animals, however, we as yet only know some few small -molar teeth. These have been found in the uppermost strata of the -Trias, in the Keuper, first in Germany (at Degerloch, near Stuttgart, -in 1847), later also in England (at Frome), in 1858. Similar teeth have -lately been found also in the North American Trias, and have been -described as Dromatherium sylvestre. These remarkable teeth, from the -characteristic form of which we can conclude that they belonged to an -insectivorous mammal, are the only remains of mammals as yet found in -the older secondary strata, namely, in the Trias. It is possible, -however, that besides these many of the other mammalian teeth found in -the Jura and Chalk systems, which are still generally ascribed to -Marsupials, in reality belong to Cloacal Animals. This cannot be decided -with certainty owing to the absence of the characteristic soft parts. In -any case, numerous Monotrema, with well-developed teeth and cloaca, must -have preceded the advent of Marsupial animals. - -The designation, "_Cloacal animals_" (Monotrema), has been given to the -Ornithodelphia on account of the cloaca which distinguishes them from -all other Mammals; but which on the other hand makes them agree with -Birds, Reptiles, and Amphibia, in fact, with the lower Vertebrata. The -formation of the cloaca consists in the last portion of the intestinal -canal receiving the mouth of the urogenital apparatus, that is, the -united urinary and genital organs, whereas in all other Mammals -(Didelphia as well Monodelphia) these organs have an opening distinct -from that of the rectum. However, in these latter also the cloaca -formation exists during the first period of their embryonal life, and -the separation of the two openings takes place only at a later date (in -man about the twelfth week of development). The Cloacal animals have -also been called "_Forked animals_," because the collar-bones, by means -of the breast bone, have become united into one piece, similar to the -well-known fork-bone, or merry-thought, in birds. In all other Mammals -the two collar-bones remain separated in front and do not fuse with the -breast bone. Moreover, the coracoid bones are much more strongly -developed in the Cloacal animals than in the other Mammalia, and are -connected with the breast bone. - -In many other characteristics also--especially in the formation of their -internal genital organs, their auricular labyrinth, and their -brain--Beaked animals are more closely allied to the other Vertebrata -than to Mammals, so that some naturalists have been inclined to separate -them from the latter as a special class. However, like all other -Mammals, they bring forth living young ones, which for a time are -nourished with milk from the mother. But whereas in all other Mammals -the milk issues through nipples, or teats, from the mammary glands, -teats are completely wanting in beaked animals, and the milk comes -simply out of a flat, sieve-like, perforated patch of the skin. Hence -they may also be called _Breastless_ or _Teatless animals_ (Amasta). - -The curious formation of the beak in the two still living Beaked -animals, which is connected with the suppression of the teeth, must -evidently not be looked upon as an essential feature of the whole -sub-class of Cloacal animals, but as an accidental character of -adaptation distinguishing the last remnant of the class as much from the -extinct main group, as the formation of a similar toothless snout -distinguishes many toothless animals (for instance, the ant-eater) from -the other placental animals. The unknown, extinct Primary Mammals, or -Promammalia--which lived during the Trias period, and of which the two -still living orders of Beaked animals represent but a single -degenerated branch developed on one side--probably possessed a very -highly developed jaw like the marsupial animals, which developed from -them. - -_Marsupial_, or _Pouched Animals_ (Didelphia, or Marsupialia), the -second of the three sub-classes of Mammals, form in every respect--both -as regards their anatomy and embryology, as well as their genealogy and -history--the transition between the other sub-classes--the Cloacal and -Placental Animals. Numerous representatives of this group still exist, -especially the well-known kangaroos, pouched rats, and pouched dogs; but -on the whole this sub-class, like the preceding one, is evidently -approaching its complete extinction, and the living members of the class -are the last surviving remnants of a large group rich in forms, which -represented the Mammalia during the more recent secondary and the -earlier tertiary periods. The Marsupial Animals probably developed -towards the middle of the Mesolithic epoch (during the Jura) out of a -branch of the Cloacal Animals, and in the beginning of the Tertiary -epoch again, the group of Placental Animals arose out of the Marsupials, -and the latter then succumbed to the former in the struggle for life. -All the fossil remains of Mammals known to us from the Secondary epoch, -belong either exclusively to Marsupials, or partly perhaps to Cloacal -animals. At that time Marsupials seem to have been distributed over the -whole earth; even in Europe (France and England), well-preserved fossil -remains of them have been found. On the other hand, the last off-shoots -of the sub-class now living are confined to a very narrow tract of -distribution, namely, to Australia, the Australasian, and a small part -of the Asiatic Archipelago. There are also a few species still living -in America, but at the present day not a single marsupial animal lives -on the continent of Asia, Africa, or Europe. - -The name of pouched animals is given to the class on account of the -purse-shaped pouch (marsupium) existing in most instances on the -abdominal side of the female animals, in which the mother carries about -her young for a considerable time after their birth. This pouch is -supported by two characteristic marsupial bones, also existing in -Cloacal animals, but not in Placental animals. The young Marsupial -animal is born in a much more imperfect form than the young Placental -animal, and only attains the same degree of development which the latter -possesses directly at its birth, after it has developed in the pouch for -some time. In the case of the giant kangaroo, which attains the height -of a man, the newly born young one, which has been carried in the -maternal womb not much longer than five weeks, is not more than an inch -in length, and only attains its essential development subsequently, in -the pouch of the mother, where it remains about nine months attached to -the nipple of the mammary gland. - -The different divisions generally distinguished as families in the -sub-class of Marsupial animals, deserve in reality the rank of -independent orders, for they differ from one another in manifold -differentiations of the jaw and limbs, in much the same manner, although -not so sharply, as the various orders of Placental animals. In part they -perfectly agree with the latter. It is evident that adaptation to -similar conditions of life has effected entirely coincident or analogous -transformations of the original fundamental form in the two sub-classes -of Marsupials. According to this, about eight orders of Marsupial -animals may be distinguished, the one half of the main group or legion -of which are herbivorous, the other half carnivorous. The oldest fossil -remains of the two legions (if the previously mentioned Microlestes and -the Dromatherium are not included) occur in the Jurassic strata, namely, -in the slates of Stonesfield, near Oxford. The slates belong to the -Bath, or the Lower Oolite formation--strata which lie directly above the -Lias, the oldest Jura formation. (Compare p. 15.) It is true that the -remains of Marsupials found in the slates of Stonesfield, as well as -those which were found later in the Purbeck strata, consist only of -lower jaws. (Compare p. 29.) But fortunately the lower jaw is just one -of the most characteristic parts of the skeleton of Marsupials. For it -is distinguished by a hook-shaped process of the lower corner of the jaw -turning downwards and backwards, which neither occurs in Placental nor -in the (still living) Cloacal animals, and from the existence of this -process on the lower jaws from Stonesfield, we may infer that they -belonged to Marsupials. - - -SYSTEMATIC SURVEY OF CLOACAL AND MARSUPIAL MAMMALIA. - -I. _First Sub-class of Mammalia:_ - -_Forked or Cloacal Animals (Monotrema, or Ornithodelphia)._ - -Mammals with Cloaca, without Placenta, with Marsupial Bones. - - ------------------------------------------------------------------------------------ - I. } - =Primary Mammals= } Unknown extinct Mammalia from the { (Microlestes?) - +Promammalia+ } Trias Period { (Dromatherium?) - - II. } 1. Aquatic beaked 1. Ornithorhynchida { 1. Ornithorhynchus - =Beaked Animals= } animals { paradoxus - +Ornithostoma+ } 2. Terrestrial 2. Echidnida { 2. Echidna hystrix - } beaked animals { - ------------------------------------------------------------------------------------ - II. _Second Sub-class of Mammalia:_ - - _Pouched or Marsupial Animals (Marsupialia, or Didelphia)._ - - Mammals without Cloaca, without Placenta, with Marsupial Bones. - ------------------------------------------------------------------------------------ - _Legions_ | _Orders_ | _Systematic Name_ | _Families of the_ - _of_ | _of_ | _of_ | _Marsupialia._ - _Marsupialia._ | _Marsupialia._ | _the Orders._ | - ------------------------------------------------------------------------------------ - { 1. Hoofed 1. Barypoda { 1. Stereognathida - { Marsupial animals { 2. Nototherida - III. { { 3. Diprotodontia - =Herbivorous= { - =Marsupial= { 2. Kangaroo 2. Macropoda { 4. Plagiaulacida - =Animals= { Marsupial animals { 5. Halmaturida - { (Leaping pouched { 6. Dendrolagida - +Marsupialia+ { animals) - +Botanophaga+ { - { 3. Root-eating 3. Rhizophaga { - { Marsupial animals { - { (Gnawing pouched { 7. Phascolomyida - { animals) { - { - { 4. Fruit eating 4. Carpophaga { - { Marsupial animals { 8. Phascolarctida - { (Climbing pouched { 9. Phalangistida - { animals) { 10. Petaurida - - { 5. Insectivorous 5. Cantharophaga { 11. Thylacotherida - { Marsupial animals { 12. Spalacotherida - { (Primæval pouched { 13. Myrmecobida - { animals) { 14. Peramelida - IV. { - =Carnivorous= { 6. Marsupial animals 6. Edentula { - =Marsupial= { poor in teeth { - =Animals= { (Pouched animals { 15. Tarsipedina - { with trunks) { - { - { 7. Rapacious marsupial 7. Creophaga { 16. Dasyurida - { animals { 17. Thylacinida - +Marsupialia+ { (Rapacious pouched { 18. Thylacoleonida - +Zoophaga+ { animals) - { - { 8. Ape-footed 8. Pedimana { - { Marsupial animals { 19. Chironectida - { (Pouched animals { 20. Didelphyida - { with hands) - - -SYSTEMATIC SURVEY OF PLACENTAL ANIMALS. - -III. _Third Sub-class of Mammalia:_ - -_Placentalia, or Monodelphia (Placental Animals)._ - -Mammals without Cloaca, with Placenta, without Marsupial Bones. - - - ----------------------------------------------------------------------------------- - _Legions of_ | _Orders of_ | _Sub-orders of_ |_Systematic Name_ - _the_ | _the_ | _the_ | _of_ - _Placental Animals._|_Placental Animals._|_Placental Animals._ | _the Sub-orders._ - ----------------------------------------------------------------------------------- - III. 1. INDECIDUA. _Placental Animals without Decidua._ - ----------------------------------------------------------------------------------- - V. { I. Single-hoofed { 1. Tapirs 1. Tapiromorpha - =Hoofed Animals= { _Perissodactyla_ { 2. Horses 2. Solidungula - +Ungulata+ { - { II. Double-hoofed { 3. Pigs 3. Choeromorpha - { _Artiodactyla_ { 4. Ruminating 4. Ruminantia - - { III. Herbivorous { - VI. { Whales { 5. Sea cows 5. Sirenia - =Whales= { _Phycoceta_ { - +Cetacea+ { - { IV. Carnivorous { 6. Whales 6. Autoceta - { Whales { 7. Zeuglodonta 7. Zeugloceta - { _Sarcoceta_ { - - VII. { V. Digging Animals { 8. Ant-eaters 8. Vermilinguia - =Animals= { _Effodientia_ { 9. Armadilloes 9. Cingulata - =poor in teeth= { - +Edentata+ { VI. Sloths { 10. Giant Sloths 10. Gravigrada - { _Bradypoda_ { 11. Dwarf Sloths 11. Tardigrada - ----------------------------------------------------------------------------------- - III. 2. DECIDUATA. _Placental Animals with Decidua._ - ----------------------------------------------------------------------------------- - VIII. { VII. Rapacious {12. Rapacious land 12. Carnivora - =Placental Animals= { Animals { animals - +Zonoplacentalia+ { _Carnaria_ {13. Rapacious sea 13. Pinnipedia - { { animals - { - { VIII. False-hoofed {14. Hyrax 14. Lamnungia - { Animals {15. Toxodonts 15. Toxodontia - { _Chelophora_ {16. Dinotheria 16. Gonyognatha - { {17. Elephants 17. Proboscidea - - - XI. { IX. Semi-apes {18. Fingered animals 18. Leptodactyla - =Disc Placental= { _Prosimiæ_ {19. Flying lemur 19. Ptenopleura - =Animals= { {20. Long-footed 20. Macrotarsi - +Discoplacentalia+ { {21. Short-footed 21. Brachytarsi - { - { X. Gnawing Animals {22. Squirrel species 22. Sciuromorpha - { _Rodentia_ {23. Mouse species 23. Myomorpha - { {24. Porcupine species 24. Hystrichomorpha - { {25. Hare species 25. Lagomorpha - { - { XI. Insect-eating {26. With a coecum 26. Menotyphla - { Animals {27. Without a 27. Lipotyphla - { _Insectivora_ { coecum - { - { XII. Flying Animals{28. Flying foxes 28. Pterocynes - { _Chiroptera_ {29. Bats 29. Nycterides - { - { XIII. Apes { 30. Clawed apes 30. Arctopitheci - { _Simiæ_ { 31. Flat-nosed 31. Platyrrhinæ - { { 32. Narrow-nosed 32. Catarrhinæ - - ---------------------------------------------------------------- - - =Man= - +Homines+ - Elephants | - _Proboscidea_ | Bats - | | _Nycterides_ - Rock Conies | | | Marine animals of prey - _Lamnungia_ | Narrow-nosed | _Pinnipedia_ - | | _Catarrhinæ_ | | - | | | Flying foxes | - \------v-----/ Flat-nosed | _Pterocynes_ | - Pseudo-hoofed _Platyrrhinæ_ | =Flying Animals= | - _Chelophora_ | | +Chiroptera+ | - | | | | | - | \----v---/ | Land animals of prey - | =Apes= | _Carnivora_ - =Gnawing Animals= +Simiæ+ | =Animals of Prey= - +Rodentia+ | | +Carnaria+ - | Fingered animals | Lemurs | | - | _Leptodactyla_ | _Brachytarsi_ | | - True | | | | \-------v---------/ - whales | | | | Insect eaters - _Sarcoceta_ \-----v----/ \---v----/ _Insectivora_ - | | | | - | \------------------v---------------------/ - Sea cows Semi-apes - _Sirenia_ _Prosimiæ_ - =Whales= =Deciduous Animals= - +Cetacea+ +Deciduata+ - | Poor in teeth | - =Hoofed Animals= _Edentata_ | - +Ungulata+ | | - | | | - \-------v--------/ | - =Indeciduous= | - +Indeciduata+ | - | | - \-------------v-------------/ - =Placental Animals= - +Placentalia+ - Herbivorous marsupials | Carnivorous marsupials - _Marsupialia botanophaga_ | _Marsupialia zoophaga_ - | | | - \--------------v-----------------/ - =Marsupial= - +Marsupialia+ - Beaked animals | - _Ornithostoma_ | - | | - \---------v--------/ - Primary mammals - _Promammalia_ - =Cloacal Animals= - +Monotrema+ - - -Of _Herbivorous marsupials_ (Botanophaga), only two fossils are as yet -known from the Jura, namely, the Stereognathus ooliticus, from the -slates of Stonesfield (Lower Oolite), and the Plagiaulax Becklesii, from -the middle Purbeck strata (Upper Oolite). But in Australia there are -gigantic fossil remains of extinct herbivorous Marsupials from the -diluvial period (Diprotodon and Nototherium) which were far larger than -the largest of the still living Marsupials. The Diprotodon Australis, -whose skull alone is three feet long, exceeded even the river-horse, or -Hippopotamus, in size and upon the whole resembled it in the unwieldy -and clumsy form of body. This extinct group, which probably corresponded -with the gigantic placental hoofed animals of the present day--the -hippopotami and rhinoceroses--may be called Hoofed Marsupials -(Barypoda). Closely allied to them is the order of kangaroos, or Leaping -Marsupials (Macropoda), which all have seen in zoological gardens. In -their shortened fore legs, their very lengthened hind legs, and very -strong tail, which serves as a jumping pole, they correspond with the -leaping mice in the class of Rodents. Their jaw, however, resembles that -of horses, and their complex stomach that of Ruminants. A third order of -Herbivorous Marsupials corresponds in its jaws to Rodents, and in its -subterranean mode of life, especially, to digging mice. Hence they may -be termed Rodent Marsupials, or root-eating pouched animals -(Rhizophaga). They are now represented only by the Australian wombat -(Phascolomys). A fourth and last order of Herbivorous Marsupials is -formed by the climbing or Fruit-eating Marsupials (Carpophaga), whose -mode of life and structure resembles partly that of squirrels, partly -that of apes (Phalangista, Phascolarctus). - -The second legion of Marsupials, the _Carnivorous Marsupials_ -(Zoophaga), is likewise divided into four main groups or orders. The -most ancient of these is that of the primæval, or Insectivorous -Marsupials (Cantharophaga). It probably includes the primary forms of -the whole legion, and possibly also those of the whole sub-class. At -least, all the lower jaws from Stonesfield (with the exception of the -Stereognathus) belong to Insectivorous Marsupials, and the still living -Myrmecobius is their nearest relative. But some of those oolitic -Primæval Marsupials possessed a larger number of teeth than all the -other known mammals, for each half of the lower jaw of the -Thylacotherium contained sixteen teeth (three incisors, one canine -tooth, six pseudo, and six genuine molars). If the upper jaw, which is -unknown, had as many teeth, then the Thylacotherium had no less than -sixty-four teeth, just double the number possessed by man. The Primæval -Marsupials correspond, on the whole, with the Insectivora among -Placental animals, which order includes hedgehogs, moles, and -shrew-mice. A second order, which has probably developed out of a branch -of the last, consists of the Snouted, or Toothless Marsupials -(Edentula), which resemble the Toothless animals, or Edentata, among the -Placental animals by their tube-shaped snout, their degenerated jaws, -and their corresponding mode of life. On the other hand, the mode of -life and formation of the jaws of Rapacious marsupials (Creophaga) -correspond with those of the genuine Beasts of Prey, or Carnivora, among -Placental animals. This order includes the pouched marten (Dasyurus) and -the pouched wolf (Thylacinus) in Australia. Although the latter attains -to the size of a wolf, it is but a dwarf in comparison with the extinct -Australian pouched lions (Thylacoleo) which were at least as large as a -lion, and possessed huge canine teeth more than two inches in length. -Finally, the eighth and last order is formed by the marsupials with -hands, or the Ape-footed Pouched animals (Pedimana), which live both in -Australia and America. They are frequently kept in zoological gardens, -especially the different species of the genus Didelphys, and are known -by the name of pouched rats, bush rats, or opossums. The thumb on their -hinder feet is opposable to the four other toes, as in a hand, and by -this they are directly allied to the Semi-apes, or Prosimia, among -Placental animals. It is possible that these latter are really next akin -to the marsupials with hands, and that they have developed out of their -long since extinct ancestors. - -It is very difficult to discover the genealogy of Marsupials, and this -more especially because we are but very imperfectly acquainted with the -whole sub-class; and the Marsupials of the present day are evidently -only the last remnants of a group that was at one time rich in forms. It -is possible that Marsupials with hands, those with snouts, as well as -rapacious Marsupials, developed as three diverging branches out of the -common primary group of Primæval Marsupials. In a similar manner, on the -other hand, the rodent, leaping, and hoofed Marsupials have perhaps -arisen as three diverging branches out of the common herbivorous primary -group, that is, out of the Climbing Marsupials. Climbing and Primæval -Marsupials might, however, be two diverging branches of the common -primary forms of all Marsupials, that is, of the _Primary Marsupials_ -(Prodidelphia), which originated during the older secondary period out -of Cloacal animals. - -The third and last sub-class of mammals comprises the _Placental -animals_, or _Placentals_ (Monodelphia, or Placentalia). It is by far -the most important, comprehensive, and most perfect of the three -sub-classes; for the class includes all the known mammalia, with the -exception of Marsupials and Beaked animals. Man also belongs to this -sub-class, and has developed out of its lower members. - -Placental animals, as their name indicates, are distinguished from all -other mammals, more especially by the formation of a so called -_placenta_. This is a very peculiar and remarkable organ, which plays -an exceedingly important part in nourishing the young one developing in -the maternal body. The placenta (also called after-birth) is a soft, -spongy, red body, which differs very much in form and size, but which -consists for the most part of an intricate network of veins and blood -vessels. Its importance lies in the exchange of substance between the -nutritive blood of the maternal womb, or uterus, and the body of the -germ, or embryo. (See vol. i. p. 298.) This very important organ is -developed neither in marsupials nor in beaked animals. But placental -animals are also distinguished from these two sub-classes by many other -peculiarities, thus more especially by the absence of marsupial bones, -by the higher development of the internal sexual organs, and by the more -perfect development of the brain, especially of the so-called callous -body or beam (_corpus callosum_), which, as the intermediate commissure, -or transverse bridge, connects the two hemispheres of the large brain -with each other. Placental animals also do not possess the peculiar -hooked process of the lower jaw which characterizes Marsupials. The -following classification (p. 246) of the most important characteristics -of the three sub-classes will best explain how Marsupials, in these -anatomical respects, stand midway between Cloacal and Placental animals. - -Placental animals are more variously differentiated and perfected, and -this, moreover, in a far higher degree, than Marsupials, and they have, -on this account, long since been arranged into a number of orders, -differing principally in the formation of the jaws and feet. But what is -even of more importance than these, is the different development of the -placenta, and the manner of its connection with the maternal uterus. -For in the three lower orders of Placental animals, in Hoofed animals, -Whales, and Toothless animals, the peculiar spongy membrane, which is -called the _deciduous membrane_, or _decidua_, and which connects the -maternal and the foetal portions of the placenta, does _not_ become -developed. This takes place exclusively in the seven higher orders of -Placental animals, and we may, therefore, according to Huxley, class -them in the main group of _Deciduata_, or animals with _decidua_. They -are contrasted with the three first-mentioned legions of indeciduous -animals, or _Indeciduata_. - - - ---------------------------+-------------------+-------------------+------------------- - | _Cloacal Animals_ | _Pouched Animals_ |_Placental Animals_ - _Three Sub-Classes_ | MONOTREMA | MARSUPIALIA | PLACENTALIA - _of_ | _or_ | _or_ | _or_ - _Mammals._ | ORNITHODELPHIA | DIDELPHIA | MONODELPHIA - ---------------------------+-------------------+-------------------+------------------- - 1. Cloaca formation | Constant | Embryonal | Embryonal - | | | - 2. Nipples of the pectoral | Wanting | Existing | Existing - glands, or milk | | | - warts | | | - | | | - 3. Fore collar bones, | United | Not united | Not united - or clavicles, grown | | | - together in the middle, | | | - with the breast bone, | | | - and forming a forked | | | - bone | | | - | | | - 4. Marsupial bones | Existing | Existing | Wanting - | | | - 5. _Corpus callosum_ of | Feebly | Feebly | Strongly developed - the brain | developed | developed | - | | | - 6. Placenta | Wanting | Wanting | Existing - ---------------------------+-------------------+-------------------+------------------- - - -But in the various orders of Placental animals the placenta differs not -only in important internal differences of structure, which are connected -with the absence or the presence of a decidua, but also in the external -form of the placenta itself. In the Indeciduata it consists, in most -cases, of numerous, single, scattered bunches or tufts of vessels, and -hence this group may be called _tufted placental animals_ -(Villiplacentalia). In the Deciduata, however, the single tufts of -vessels are united into a cake, which appears in two different forms. In -the one case it surrounds the embryo in the form of a closed band or -ring, so that only the two poles of the oval egg bladder are free of -tufts; this is the case in animals of prey (Carnaria) and the -pseudo-hoofed animals (Chelophora), which may consequently be comprised -as _girdled-placental animals_ (Zonoplacentalia). In the other -Deciduata, to which man also belongs, the placenta is a simple round -disc, and we therefore call them _disc-placentals_ (Discoplacentalia). -This group includes the five orders of Semi-apes, Gnawing animals, -Insectivora, Bats, and Apes, from the latter of which, in the zoological -system, man cannot be separated. - -It may be considered as quite certain, from reasons based upon their -comparative anatomy and their history of development, that Placental -animals first developed out of Marsupials, and that this very important -development--the first origin of the placenta--probably took place in -the beginning of the tertiary epoch, during the eocene period. But one -of the most difficult questions in the genealogy of animals is the -important consideration whether all Placental animals have arisen out of -one or out of several distinct branches of Marsupials; in other words, -whether the origin of the placenta occurred but once, or several times. - -When, in my General Morphology, I for the first time endeavoured to -establish the pedigree of Mammals, I here, as in most cases, preferred -the monophyletic, or one-rooted, to the polyphyletic, or many-rooted, -hypothesis of descent. I assumed that all Placental animals were derived -from a single form of Marsupial animal, which, for the first time, began -to form a placenta. In this case the Villiplacentals, Zonoplacentals, -and Discoplacentals would perhaps have to be considered as three -diverging branches of the common primary form of Placentals, or it might -also be conceived that the two latter, the Deciduata, had developed only -at a later period out of the Indeciduata, which on their part had arisen -directly out of the Marsupials. However, there are also important -reasons for the alternative; namely, that several groups of Placentals, -differing from the beginning, arose out of several distinct groups of -Marsupials, so that the placenta itself was formed several times -independently. This opinion is maintained by Huxley, the most eminent -English zoologist, and by many others. In this case the Indeciduata and -the Deciduata would perhaps have to be considered as two completely -distinct groups; then the order of Hoofed animals, as the primary group -of the Indeciduata, might be supposed to have originated out of the -Marsupial hoofed animals (Barypoda). Among the Deciduata, on the other -hand, the order of Semi-apes, as the common primary form of the other -orders, might possibly have arisen out of Handed Marsupials (Pedimana). -But it is also conceivable that the Deciduata themselves have arisen out -of several different orders of Marsupials, Animals of Prey out of -Rapacious Marsupials, Gnawing animals out of Gnawing Marsupials, -Semi-apes out of Handed Marsupials, etc. As we do not at present possess -sufficient empiric material to solve this most difficult question, we -must leave it and turn our attention to the history of the different -orders of Placental animals, whose pedigree can often be very accurately -established in detail. - -We must, as already remarked, consider the order of _Hoofed animals_ -(Ungulata) as the primary group of the Indeciduata, or Tuft-placentals; -the two other orders, Whales and Toothless animals, developed out of -them, as two diverging groups, probably only at a later period, by -adaptation to very different modes of life. But it is also possible that -the animals poor in teeth (Edentata) may be of quite a different origin. - -Hoofed animals are in many respects among the most important and the -most interesting Mammals. They distinctly show that a true understanding -of the natural relationship of animals can never be revealed to us -merely by the study of living forms, but in all cases only by an equal -consideration of their extinct and fossil blood-relations and ancestors. -If, as is usually done, only the living Hoofed animals are taken into -consideration, it seems quite natural to divide them into three entirely -distinct orders, namely: (1) Horses, or _Single-hoofed animals_ -(Solidungula, or Equina); (2) Ruminating animals, or _Double-hoofed_ -(Bisulca, or Ruminantia); and (3) Thick-skinned, or _Many-hoofed_ -(Multungula, or Pachyderma). But as soon as the extinct Hoofed animals -of the tertiary period are taken into consideration--of which animals we -possess very numerous and important remains--it is seen that this -division, but more especially the limitation of the Thick-skinned -animals, is completely artificial, and that these three groups are -merely top branches lopped from the pedigree of Hoofed animals, which -are most closely connected by extinct intermediate forms. The one half -of the Thick-skinned animals--rhinoceroses, tapirs, and -palæotheria--manifest the closest relationships to horses, and have like -them odd-toed feet; whereas the other half of the Thick-skinned -animals--pigs, hippopotami, and anoplotheria--on account of their -double-toed feet are much more closely allied to ruminating animals than -to the former. Hence we must, in the first place, among Hoofed animals -distinguish the two orders of Paired-hoofs and Odd-hoofs, as two natural -groups, which developed as diverging branches out of the old tertiary -primary group of Primary Hoofed animals, or Prochela. - -The order of _Odd-hoofed animals_ (Perissodactyla) comprises those -Ungulata in which the middle (or third) toe of the foot is much more -strongly developed than the others, so that it forms the actual centre -of the hoof. This order includes the very ancient, common, primary group -of all Hoofed animals, that is, the _Primary-hoofed animals_ (Prochela), -which are found in a fossil state in the oldest Eocene strata -(Lophiodon, Coryphodon, Pliolophus). Directly allied to this group is -that branch which is the actual primary form of the Odd-hoofed animals, -namely, the _Palæotheria_, fossils of which occur in the upper Eocene -and lower Miocene. Out of the Palæotheria, at a later period, the -rhinoceroses (Nasicornia) and rhinoceros-horses (Elasmotherida) on the -one hand, and the tapirs, lama-tapirs, and primæval horses, on the -other, developed as two diverging branches. The long since extinct -primæval horses, or Anchitheria, formed the transition from the -Palæotheria and tapirs to the Miocene horses, or hipparions, which are -closely allied to the genuine living horses. - -The second main group of Hoofed animals, the order of _Pair-hoofed -animals_ (Artiodactyla), comprises those hoofed animals in which the -middle (third) and fourth toe of the foot are almost equally developed, -so that the space between the two forms the central line of the entire -foot. The order is divided into two sub-orders--the Pig-shaped and the -Cud-chewing, or Ruminating. The _Pig-shaped_ (Choeromorpha) comprise in -the first place the other branch of Primary-Hoofed-animals, the -_Anoplotheria_, which we consider as the common primary form of all -Pair-hoofed animals, or Artiodactyla (Dichobune, etc.). Out of the -Anoplotheria arose, as two diverging branches, the primæval swine, or -Anthracotheria, on the one hand, forming the transition to swine and -river-horses, and the Xiphodonta on the other hand, forming the -transition to Ruminating animals. The oldest _Ruminating animals_ -(Ruminantia) are the Primæval Stags, or Dremotheria, out of which, -possibly, the stag-shaped (Elaphia), the hollow-horned (Cavicornia), and -camels (Tylopoda), have developed as three diverging branches. Yet these -latter are, in many respects, more allied to the Odd-hoofs than to the -genuine Pair-hoofs. The accompanying systematic survey on p. 252, will -show how the numerous families of Hoofed animals are grouped, in -correspondence with this genealogical hypothesis. - - - SYSTEMATIC SURVEY - - _Of the Sections and Families of Hoofed Animals, or Ungulata._ - - (N.B. Those families that are extinct are marked with an asterisk.) - - - ----------------+--------------------------------+------------------------+------------------- - _Orders_ | | | - _of_ | _Sections_ | _Families_ | _Systematic Name_ - _Hoofed_ | _of_ | _of_ | _of_ - _animals._ | _Hoofed Animals._ | _Hoofed Animals._ | _the Families._ - ----------------+----------------------------=---+------------------------+------------------- - I. { I. Primary Hoofed { 1. Lophiodonta 1. Lophiodontia* - =Odd-toed= { Animals.* { 2. Pliolophida 2. Pliolophida* - =Hoofed= { _Prochela_ - =Animals= { { 3. Primary 3. Palæotherida* - { { Odd-hoofs - +Ungulata+ { II. Tapir-shaped { 4. Lama-tapirs 4. Macrauchenida* - { _Tapiromorpha_ { 5. Tapirs 5. Tapirida - +Perissodactyla+ { { 6. Rhinoceroses 6. Nasicornia - { { 7. Rhinoceros-horses 7. Elasmotherida* - { - { III. Single-hoofs { 8. Primæval 8. Anchitherida* - { _Solidungula_ { horses - { { 9. Horses 9. Equina - - { { 10. Primary 10. Anoplotherida* - { { Pair-hoofs - { { 11. Primæval 11. Anthracotherida* - { IV. Pig-shaped { pigs - { _Choeromorpha_ { 12. Pigs 12. Setigera - { { 13. River horses 13. Obesa - { { 14. Primæval 14. Xiphodontia* - { { ruminants - { - { { { {15. Primæval 15. Dremotherida* - { { { { deer - II. { { A. Stag-shaped { a. {16. Pseudo 16. Tragulida - =Pair-toed= { { _Elaphia_ { { musk deer - =Hoofed= { { { - =Animals= { { { b. {17. Musk deer 17. Moschida - { { { {18. Deer 18. Cervina - +Ungulata+ { { { - { V. { { c. {19. Primæval 19. Sivatherida* - +Artiodactyla+ { Ruminating { { { giraffes - { animals { { {20. Giraffes 20. Devexa - { _Ruminantia_ { - { { { {21. Primæval 21. Antilocaprina* - { { { d. { gazelles - { { { {22. Gazelles 22. Antilopina - { { { - { { B. Hollow-horned { {23. Goats 23. Caprina - { { _Caricornia_ { e. {24. Sheep 24. Ovina - { { { {25. Oxen 25. Bovina - { { - { { C. Pad-footed { 26. Lamas 26. Auchenida - { { _Tylopoda_ { 27. Camels 27. Camelida - - ---------------------------------------------------------------- - - Oxen Giraffes - | | - | Sheep Deer | - | | | | - | | | | - \--v---/ Goats \---v---/ Musk deer Horses - | | | | _Equi_ - | | | | | - \---v-----/ Antelopes | | Camels | - | | \----v-----/ and Lamas Intermediate horses - | | Deer-shaped _Tylopoda_ _Hippariones_ - \-----v------/ _Elaphia_ | | - Hollow-horned | | | - _Cavicornia_ | | | - | | | | - | | | Primæval horses - \-------v--------/ | _Anchitherida_ - Primæval deer | | - _Dremotherida_ | | - | | =Single Hoofers= - | | +Solidungula+ - \--v------------------/ | - =Ruminating Animals= | - +Ruminantia+ | - Sea-oxen | Tapirs | - _Sirenia_ | _Tapirida_ | - | River-horses | | Lama-tapirs | - | _Obesa_ | | _Macrauchenida_| - | | | | | | - | | Pigs | | | | - \----v-----/ _Setigera_ | \--------------v--/ | - | | | | | - | | | Rhinoceros-horses | | - | | | _Elasmotherida_ | | - | | | | | | - \------v-------/ | | | | - Primæval pigs | Rhinoceruses | | | - _Anthracotherida_ | _Nasicornia_ | \---v-----/ - | | | | | - | Primæval ruminants | | | - | _Xiphodontia_ \---v---/ | - | | | | - | | | | - \------v------/ \--------v--------/ - =Primary Pair-hoofs= =Primary Odd-hoofs= - +Anoplotherida+ +Palæotherida+ - | | - | | - \------------v-------------/ - _Prochela_ - Primary-hoofed-animals - (_Lophiodontia_ and _Pliophida_) - | - | - (Hoofed marsupials? _Barypoda?_) - - -It is probable that the remarkable legion of _Whales_ (Cetacea) -originated out of Hoofed animals, which accustomed themselves -exclusively to an aquatic life, and thereby became transformed into the -shape of fish. Although these animals seem externally very like many -genuine Fish, yet they are, as even Aristotle perceived, genuine -Mammals. By their whole internal structure--in so far as it has not -become changed by adaptation to an aquatic life--they, of all known -Mammals, are most closely allied to Hoofed animals, and more especially -agree with them in the absence of the decidua and in the tufted -placenta. Even at the present day the river-horse (Hippopotamus) -constitutes a kind of transition form to the Sea Cows (Sirenia), and -from this it seems most probable that the extinct primary forms of the -Cetacea are most closely allied to the Sea Cows of the present day, and -that they developed out of Pair-hoofed animals, which were related to -the hippopotamus. Out of the order of _Herbivorous whales_ -(Phycoceta)--to which the sea cows belong, and which accordingly, very -probably, contain the primary forms of the legion--the other order of -_Carnivorous whales_ (Sarcoceta) appears to have developed at a later -period. But Huxley thinks that these latter were of quite a different -origin, and that they arose out of the Carnaria through the Seals. Among -the Sarcoceta, the extinct gigantic Zeuglodonta (Zeugloceta)--whose -fossil skeletons some time ago excited great interest, it being thought -that they were "sea serpents"--are probably only a peculiarly developed -lateral branch of genuine whales (Autoceta), which comprise, besides the -colossal whalebone whales, the cachalot or spermaceti whales, dolphins, -narwhals, porpoises, etc. - -The third legion of the Indeciduata, or Sparsi-placentalia, comprises -the strange group of the animals _poor in teeth_ (Edentata); it is -composed of the two orders of burrowers and sloths. The order of -_Burrowers_ (Effodientia) consists of the two sub-orders of _ant eaters_ -(Vermilinguia), to which the scaled animals also belong, and the _girdle -animals_ (Cingulata), which were formerly represented by the gigantic -Glyptodons. The order of _Sloths_ (Tardigrada) consists of the two -sub-orders of the small, still living _dwarf sloths_ (Bradypoda), and -of the extinct unwieldy _giant sloths_ (Gravigrada). The enormous fossil -remains of these colossal herbivora suggest that the whole legion is -becoming extinct, and that the Edentata of the present day are but a -poor remnant of the mighty order of the diluvial period. The close -relations between the still living South American Edentata and the -extinct gigantic forms which are found beside the latter on the same -part of the globe, made such an impression upon Darwin on his first -visit to South America, that they even then suggested to him the -fundamental idea of the Theory of Descent. (See above, vol. i. p. 134.) -But it is precisely the genealogy of this legion which is most -difficult. The Edentata are perhaps nothing but a peculiarly developed -lateral branch of the Ungulata; but it may also be that their root lies -in quite another direction. - -We now leave the first main group of Placental animals, the Indeciduata, -and turn to the second main group, namely, the Deciduata, or animals -with decidua, which are distinguished from the former by possessing a -deciduous membrane, or decidua, during their embryonal life. We here -meet with a very remarkable small group of animals, for the most part -extinct, and which probably were the old tertiary (or eocene) ancestors -of man. These are the Semi-apes, or Lemurs (Prosimiæ); these curious -animals are probably the but little changed descendants of the primæval -group of Placentalia which we have to consider as the common primary -form of all Deciduata. They have hitherto been classed together in the -same order with Apes which Blumenbach called Quadrumana (four-handed). -However, I regard them as entirely distinct from these, not merely -because they differ from all Apes, much more than do the most different -Apes from one another, but also because they comprise most interesting -transitional forms leading to the other orders of Deciduata. I conclude -from this that the few still living Semi-apes, which moreover differ -very much among one another, are the last surviving remnants of a -primary group now almost extinct, but which was at one time rich in -forms, and out of which all the other Deciduata (possibly with the -single exception of Beasts of Prey, and Pseudo-hoofed animals) have -developed as diverging branches. The old primary group of Semi-apes has -probably developed out of Handed or Ape-footed Marsupials (Pedimana), -which are surprisingly like them in the transformation of their hinder -feet into grasping hands. The primæval primary forms themselves (which -probably originated in the eocene period) are of course long since -extinct, as are also the greater portion of the transition-forms between -them and all the other orders of Deciduata. However, individual remnants -of the latter are preserved among the Semi-apes of the present day. -Among these, the remarkable Finger-animal of Madagascar (Chiromys -madagascariensis) constitutes the remnant of the group of the -Leptodactyla and the transition to Rodents. The strange flying lemur in -the South Sea and Sunda islands (Galeopithecus), the only remnant of the -group of Pteropleura, forms a perfect intermediate stage between -Semi-apes and Bats. The long-footed Semi-apes (Tarsius, Otolicnus) -constitute the last remnant of that primary branch (Macrotarsi) out of -which the Insectivora developed. The short-footed forms (Brachytarsi) -are the medium of connection between them and genuine Apes. The -Short-footed Semi-apes comprise the long-tailed Lemur, the short-tailed -Lichanotus, and the Stenops, the latter of which seems to be very -closely allied to the probable ancestors of man among the Semi-apes. The -short-footed as well as the long-footed Prosimiæ live widely distributed -over the islands of southern Asia and Africa, more especially in -Madagascar; some live also on the continent of Africa. No Semi-ape, -either living or in a fossil state, has as yet been found in America. -They all lead a solitary, nocturnal kind of life, and climb about on -trees. (Compare vol. i. p. 361.) - -Among the six remaining orders of Deciduata, all of which are probably -derived from long since extinct Semi-apes, the order of _Gnawing -animals_ (Rodentia), which is rich in forms, has remained at the lowest -stage. Among these the _squirrel-like_ animals (Sciuromorpha) stand -nearest akin to the Pedimanous Marsupials. Out of this primary group the -_mouse-like_ animals (Myomorpha) and the _porcupine-like_ animals -(Hystricomorpha) developed probably as two diverging branches, the -former of which are directly connected with the squirrel-like animals, -by the eocene Myoxida, the latter by the eocene Psammoryctida. The -fourth sub-order, the _hare-like_ animals (Lagomorpha), probably -developed only at a later period out of one of the other three -sub-orders. - -Very closely allied to the Rodentia is the remarkable order of -_Pseudo-hoofed animals_ (Chelophora). Of these there now live but two -genera, indigenous to Asia and Africa, namely, Elephants (Elephas), and -Rock Conies (Hyrax). Both have hitherto generally been classed among -real Hoofed animals, or Ungulata, with which they agree in the formation -of the feet. But an identical transformation of nails or claws into -hoofs occurs also in genuine Rodentia and in certain hoofed Rodentia -(Subungulata) which live exclusively in South America. Beside smaller -forms (for example, guinea pigs and gold hares) the Subungulata also -include the largest of all Rodentia, namely, the Capybara Rats, which -are about four feet in length. The Rock Conies, which are externally -very nearly akin to Rodents, especially to the hoofed Rodents, were -formerly classed among Rodentia by some celebrated zoologists, as an -especial sub-class (Lamnungia). Elephants, on the other hand, when not -classed among Hoofed animals, were generally considered as the -representatives of a special order which were called Trunked animals -(Proboscidea). But the formation of the placentas of Elephants and of -Hyrax agree in a remarkable manner, and are entirely distinct from those -of Hoofed animals. These latter never possess a decidua, whereas -Elephants and Hyrax are genuine Deciduata. Their placenta is indeed not -of the form of a disc, but of a girdle, as in the case of Animals of -Prey; it is very possible that the girdle-shaped placenta is but a -secondary development of the discoplacenta. Thus, then, it might be -thought that the Pseudo-hoofed animals have developed out of a branch of -the Rodentia, and in a similar manner perhaps the Carnivora out of a -branch of the Insectivora. At all events, Elephants and Hyrax in many -respects, especially in the formation of important skeletal parts, of -the limbs, etc., are more closely allied to the Rodentia, and more -especially to hoofed Rodentia, than to genuine Hoofed animals. Moreover -several extinct forms, especially the remarkable South American -Arrow-toothed animals (Toxodontia), stand in many respects midway -between Elephants and Rodentia. That the still living Elephants and -Hyrax are but the last survivors of a group of Pseudo-hoofed animals, -which was once rich in forms, is proved not only by the very numerous -fossil species of Elephants and Mastodon (some of which are even larger, -others also much smaller than the Elephants of the present day), but -also by the remarkable miocene _Dinotheria_ (Gonyognatha), between which -and their next kindred, the Elephants, there must be a long series of -unknown connecting intermediate forms. Taking all things into -consideration, the most probable hypothesis which can be established at -present as to the origin and the relationship of Elephants, Dinotheria, -Toxodon, and Hyrax is, that they are the last survivors of a group of -Pseudo-hoofed animals rich in forms, which developed out of the -Rodentia, and probably out of relatives of the Subungulata. - -The order of _Insect Eaters_ (Insectivora) is a very ancient group, and -is next akin to the common extinct primary form of the Deciduata, as -well as to the Semi-apes of the present day. It has probably developed -out of Semi-apes which were closely allied to the Long-footed Lemurs -(Macrotarsi) of the present day. It is separated into two orders, -Menotyphla and Lipotyphla; the Menotyphla are probably the older of the -two, and are distinguished from the Lipotyphla by possessing an -intestinal coecum, or typhlon. The Menotyphla include the climbing -Tupajas of the Sunda Isles, and the leaping Macroscelides of Africa. The -Lipotyphla are represented in our country by shrew mice, moles, and -hedgehogs. The Insectivora, in the formation of their jaws and their -mode of life, are nearly akin to Carnivora, but are, on the other hand, -by their discoplacentas and by their large seminal vesicles, allied to -Rodents. - -It is probable that the order of _Rapacious animals_ (Carnaria) -developed out of a long since extinct branch of Insectivora, at the -beginning of the Eocene period. It is a natural group, very rich in -forms, but still of very uniform organization. The Rapacious animals are -sometimes also called Girdle-placentals (Zonoplacentals), although the -Pseudo-hoofed animals (Chelophora), in the same way, also deserve this -designation. But as the latter, in other respects, are more closely -allied to the Rodentia than to Carnaria, we have already discussed them -in connection with the former. Animals of prey are divided into two, -externally very different, but internally very closely related, -sub-orders, namely, Land animals of prey and Marine animals of prey. The -_Land animals of prey_ (Carnivora) comprise bears, dogs, cats, etc., -whose pedigree can be approximately guessed at by means of many extinct -intermediate forms. The _Marine animals of prey_, or _Seals_ -(Pinnipedia), comprise sea bears, sea dogs, sea lions, and walruses. -Although marine animals of prey appear externally very unlike land -animals of prey, yet by their internal structure, their jaw and their -peculiar girdle-shaped placenta, they are very nearly akin to them, and -have evidently originated out of a branch of them, probably out of a -kind of weasel (Mustelina). Even at the present day the fish otters -(Lutra), and still more so the sea otters (Enhydris), present a direct -form of transition to Seals, and clearly show how the bodies of land -Carnivora are transformed into the shape of a Seal, by adaptation to an -aquatic life, and how the steering fins of marine rapacious animals have -arisen out of the legs of the former. The latter consequently stand in -the same relation to the former as do the Whales to Hoofed animals -among the Indeciduata. In the same way as the river-horse at present -stands midway between the extreme branches of oxen and sea oxen, the sea -otter still forms a surviving intermediate stage between the widely -separated branches of dogs and sea dogs. In both cases the complete -transformation of the external form, consequent upon adaptation to -entirely different conditions of life, has not been able to efface the -solid foundation of the inherited internal peculiarities. - -According to Huxley's opinion, which has already been quoted, only the -Herbivorous Whales (Sirenia) are derived from Hoofed animals; on the -other hand, the Carnivorous Cetacea (Sarcoceta) are derived from the -marine animals of prey; the Zeuglodonts would form a transition between -the two latter. But in this case it would be difficult to understand the -close anatomical relations which exist between the Herbivorous and -Carnivorous Cetacea. The strange peculiarities in the internal and -external structure which so strikingly distinguish the two groups from -all other mammals would then have to be regarded only as _analogies_ -(caused by the same kinds of adaptation), not as _homologies_ -(transmitted from a common primary form). The latter, however, strikes -me as being by far the more probable, and hence I have left all the -Cetacea among the Indeciduata as one group of kindred origin. - -The remarkable order of _Flying Mammals_, or _Bats_ (Chiroptera), stands -near to the Carnaria as well as to the Insectivora. It has become -strikingly transformed by adaptation to a flying mode of life, just as -marine animals of prey have become modified by adaptation to a swimming -mode of life. This order probably also originated out of the Semi-apes, -with which it is even at present closely allied, through the flying -lemurs (Galeopithecus). Of the two orders of flying animals, the -insect-eating forms, or _flying mice_ (Nycterides), probably developed -out of those eating fruits, or _flying foxes_ (Pterocynes); for the -latter are, in many ways, more closely allied to Semi-apes than are the -former. - -We have now still to discuss the genuine Apes (Simiæ) as the last order -of Mammals; but as, according to the zoological system, the human race -belongs to this order, and as it undoubtedly developed historically out -of a branch of this order, we shall devote a special chapter to a more -careful examination of its pedigree and history. - - - - -CHAPTER XXII. - -ORIGIN AND PEDIGREE OF MAN. - - - The Application of the Theory of Descent to Man.--Its Immense - Importance and Logical Necessity.--Man's Position in the Natural - System of Animals, among Disco-placental Animals.--Incorrect - Separation of the Bimana and Quadrumana.--Correct Separation of - Semi-apes from Apes.--Man's Position in the Order of - Apes.--Narrow-nosed Apes (of the Old World) and Flat-nosed Apes - (of America).--Difference of the two Groups.--Origin of Man from - Narrow-nosed Apes.--Human Apes, or Anthropoides.--African Human - Apes (Gorilla and Chimpanzee).--Asiatic Human Apes (Orang and - Gibbon).--Comparison between the different Human Apes and the - different Races of Men.--Survey of the Series of the Progenitors - of Man.--Invertebrate Progenitors (Prochordata) and Vertebrate - Progenitors. - - -Of all the individual questions answered by the Theory of Descent, of -all the special inferences drawn from it, there is none of such -importance as the application of this doctrine to Man himself. As I -remarked at the beginning of this treatise, the inexorable necessity of -the strictest logic forces us to draw the special deductive conclusion -from the general inductive law of the theory, that Man has developed -gradually, and step by step, out of the lower Vertebrata, and more -immediately out of Ape-like Mammals. That this doctrine is an -inseparable part of the Theory of Descent, and hence also of the -universal Theory of Development in general, is recognized by all -thoughtful adherents of the theory, as well as by all its opponents who -reason logically. - -But if the doctrine be true, then the recognition of the animal origin -and pedigree of the human race will necessarily affect more deeply than -any other progress of the human mind the views we form of all human -relations, and the aims of all human science. It must sooner or later -produce a complete revolution in the conception entertained by man of -the entire universe. I am firmly convinced that in future this immense -advance in our knowledge will be regarded as the beginning of a new -period of the development of Mankind. It can only be compared to the -discovery made by Copernicus, who was the first who ventured distinctly -to express the opinion, that it was not the sun which moved round the -earth, but the earth round the sun. Just as the _geocentric conception_ -of the universe--namely, the false opinion that the earth was the centre -of the universe, and that all its other portions revolved round the -earth--was overthrown by the system of the universe established by -Copernicus and his followers, so the _anthropocentric conception_ of the -universe--the vain delusion that Man is the centre of terrestrial -nature, and that its whole aim is merely to serve him--is overthrown by -the application (attempted long since by Lamarck) of the theory of -descent to Man. As Copernicus' system of the universe was mechanically -established by Newton's theory of gravitation, we see Lamarck's theory -of descent attain its causal establishment by Darwin's theory of -selection. This comparison, which is very interesting in many respects, -I have discussed in detail elsewhere. - -In order to carry out this extremely important application of the Theory -of Descent to man, with the necessary impartiality and objectivity, I -must above all beg the reader (at least for a short time) to lay aside -all traditional and customary ideas on the "Creation of Man," and to -divest himself of the deep-rooted prejudices concerning it, which are -implanted in the mind in earliest youth. If he fail to do this, he -cannot objectively estimate the weight of the scientific arguments which -I shall bring forward in favour of the animal derivation of Man, that -is, of his origin out of Ape-like Mammals. We cannot here do better than -imagine ourselves with Huxley to be the inhabitants of another planet, -who, taking the opportunity of a scientific journey through the -universe, have arrived upon the earth and have there met with a peculiar -two-legged mammal called Man, diffused over the whole earth in great -numbers. In order to examine him zoologically, we should pack a number -of the individuals of different ages and from different lands (as we -should do with the other animals collected on the earth) into large -vessels filled with spirits of wine, and on our return to our own planet -we should commence the comparative anatomy of all these terrestrial -animals quite objectively. As we should have no personal interest in -Man, in a creature so entirely different from ourselves, we should -examine and criticise him as impartially and objectively as we should -the other terrestrial animals. In doing this we should, of course, in -the first place refrain from all conjectures and speculations on the -nature of his soul, or on the spiritual side of his nature, as it is -usually called. We should occupy ourselves solely with his bodily -structure, and with that natural conception of it which is offered by -the history of his individual development. - -It is evident that in order correctly to determine Man's position among -the other terrestrial organisms we must, in the first place, follow the -guidance of the natural system. We must endeavour to determine the -position which belongs to Man in the natural system of animals as -accurately and distinctly as possible. We shall then, if in fact the -theory of descent be correct, be able from his position in the system to -determine the real primary relationship, and the degree of consanguinity -connecting Man with the animals most like him. The hypothetical pedigree -of the human race will then follow naturally as the final result of this -anatomical and systematic inquiry. - -Now if, by means of comparative anatomy and ontogeny, we seek for man's -position in that Natural System of animals which formed the subject of -the last two chapters, the incontrovertible fact will at once present -itself to us, that man belongs to the tribe, or phylum, of the -Vertebrata. Every one of the characteristics, which so strikingly -distinguish all the Vertebrata from all Invertebrata, is possessed by -him. It has also never been doubted that of all the Vertebrata the -Mammals are most closely allied to Man, and that he possesses all the -characteristic features distinguishing them from all other Vertebrata. -If then we further carefully examine the three different main groups or -sub-classes of Mammals--the inter-connections of which were discussed in -our last chapter--there cannot be the slightest doubt that Man belongs -to the Placentals, and shares with all other Placentals, the important -characteristics which distinguish them from Marsupials and from -Cloacals. Finally, of the two main groups of placental Mammals, the -Deciduata and the Indeciduata, the group of Deciduata doubtless includes -Man. For the human embryo is developed with a genuine decidua, and is -thus absolutely distinguished from all the Indeciduata. Among the -Deciduata we distinguish two legions, the Zonoplacentalia, with -girdle-shaped placenta (Beasts of Prey and Pseudo-hoofed animals), and -the Discoplacentalia, with disc-shaped placenta (all the remaining -Deciduata). Man possesses a disc-shaped placenta, like all -Discoplacentalia; and thus our next question must be, What is man's -position in this group? - -In the last chapter we distinguished the following five orders of -Discoplacentalia: (1) Semi-apes; (2) Rodents; (3) Insectivora; (4) Bats; -(5) Apes. The last of these five orders, that of Apes, is, as every one -knows, in every bodily feature far more closely allied to Man than the -four others. Hence the only remaining question now is, whether, in the -system of animals, Man is to be directly classed in the order of genuine -Apes, or whether he is to be considered as the representative of a -special sixth order of Discoplacentalia, allied to, but more advanced -than, that of the Apes. - -Linnæus in his system classed Man in the same order with genuine Apes, -Semi-apes, and Bats, which he called _Primates_; that is, lords, as it -were the highest dignitaries of the animal kingdom. But Blumenbach, of -Göttingen, separated Man as a special order, under the name of _Bimana_, -or two-handed, and contrasted him with the Apes and Semi-apes under the -name of _Quadrumana_, or four-handed. This classification was also -adopted by Cuvier and, consequently, by most subsequent zoologists. It -was not until 1863 that Huxley, in his excellent work, the "Evidence as -to Man's Place in Nature,"(26) showed that this classification was based -upon erroneous ideas, and that the so-called "four-handed" Apes and -Semi-apes are "two-handed" as much as man is himself. The difference -between the foot and hand does not consist in the _physiological_ -peculiarity that the first digit or thumb is opposable to the four other -digits or fingers in the hand, and is not so in the foot, for there are -wild tribes of men who can oppose the first or large toe to the other -four, just as if it were a thumb. They can therefore use their "grasping -foot" as well as a so-called "hinder hand," like Apes. The Chinese -boatmen row with this hinder hand, the Bengal workmen weave with it. The -Negro, in whom the big toe is especially strong and freely moveable, -when climbing seizes hold of the branches of the trees with it, just -like the "four-handed" Apes. Nay, even the newly born children of the -most highly developed races of men, during the first months of their -life, grasp as easily with the "hinder hand" as with the "fore hand," -and hold a spoon placed in its clutch as firmly with their big toe as -with the thumb! On the other hand, among the higher Apes, especially the -gorilla, hand and foot are differentiated as in man. (Compare Plate IV.) - -The essential difference between hand and foot is therefore not -physiological, but _morphological_, and is determined by the -characteristic structure of the bony skeleton and of the muscles -attached to it. The ankle-bones differ from the wrist-bones in -arrangement, and the foot possesses three special muscles not existing -in the hand (a short flexor muscle, a short extensor muscle, and a long -fibular muscle). In all these respects, Apes and Semi-apes entirely -agree with man, and hence it was quite erroneous to separate him from -them as a special order on account of the stronger differentiation of -his hand and foot. It is the same also with all the other structural -features by means of which it was attempted to distinguish Man from -Apes; for example, the relative length of the limbs, the structure of -the skull, of the brain, etc. In all these respects, without exception, -the differences between Man and the higher Apes are less than the -corresponding differences between the higher and the lower Apes. Hence -Huxley, for reasons based on the most careful and most accurate -anatomical comparisons, arrives at the extremely important -conclusion--"Thus, whatever system of organs be studied, the comparison -of their modifications in the Ape series leads to one and the same -result, that the structural differences which separate Man from the -Gorilla and Chimpanzee are not so great as those which separate the -Gorilla from the lower Apes." In accordance with this, Huxley, strictly -following the demands of logic, classes Man, Apes, and Semi-apes in a -single order, _Primates_, and divides it into the following seven -families, which are of almost equal systematic value: (1) Anthropini -(Man); (2) Catarrhini (genuine Apes of the Old World); (3) Platyrrhini -(genuine American Apes); (4) Arctopitheci (American clawed Apes); (5) -Lemurini (short-footed and long-footed Semi-apes, p. 255); (6) -Chiromyini (p. 256); (7) Galeopithecini (Flying Lemurs, p. 256). - - -SYSTEMATIC SURVEY - -_Of the Families and Genera of Apes._ - - - -----------------+------------------------+---------------------+------------------ - _Sections_ | _Families_ | _Genera_ | _Systematic Name_ - _of_ | _of_ | _of_ | _of_ - _Apes._ | _Apes._ | _Apes._ | _the Genera._ - -----------------+------------------------+---------------------+------------------ - I. APES OF THE NEW WORLD (+Hesperopitheci+), OR FLAT-NOSED APES (+Platyrrhini+). - ----------------------------------------------------------------------------------- - A. =Platyrrhini= { I. Silky apes { 1. Brush ape 1. Midas - =with claws= { _Hapalida_ { 2. Lion ape 2. Jacchus - { - +Arctopitheci+ { - - { II. Flat-nosed, { 3. Squirrel ape 3. Chrysothrix - { without prehensile { 4. Leaping ape 4. Callithrix - B. =Platyrrhini= { tail { 5. Nocturnal ape 5. Nyctipithecus - =with blunt= { _Aphyocerca_ { 6. Tail ape 6. Pithecia - =nails= { - { III. Flat-nosed, { 7. Rolling ape 7. Cebus - +Dysmopitheci+ { with prehensile { 8. Climbing ape 8. Ateles - { tail { 9. Woolly ape 9. Lagothrix - { _Labidocerca_ { 10. Howling ape 10. Mycetes - ---------------------------------------------------------------------------------- - II. APES OF THE OLD WORLD (+Heopitheci+), OR NARROW-NOSED APES (+Catarrhini+). - ---------------------------------------------------------------------------------- - { IV. Tailed Catarrhini, { - { with { 11. Pavian 11. Cynocephalus - C. =Tailed= { cheek-pouches { 12. Macaque 12. Innus - =Catarrhini= { _Ascoparea_ { 13. Sea cat 13. Cercopithecus - { - +Menocerca+ { V. Tailed Catarrhini, { - { without { 14. Holy ape 14. Semnopithecus - { cheek-pouches { 15. Short ape 15. Colobus - { _Anasca_ { 16. Nose ape 16. Nasalis - - { { 17. Gibbon 17. Hylobates - { VI. Human apes { 18. Orang-Outan 18. Satyrus - D. =Tailless= { _Anthropoides_ { 19. Chimpanzee 19. Engeco - =Catarrhini= { { 20. Gorilla 20. Gorilla - { - +Lipocerca+ { VII. Men { 21. Ape-like man, 21. Pithecanthropus - { _Erecti_ { or speechless man (Alalus) - { (_Anthropi_) { 22. Talking man 22. Homo - - ---------------------------------------------------------------- - - Straight-haired men - _Lissotrichi_ - | - Woolly-haired men | - _Ulotrichi_ | - | | - | | - \-------------v-------------/ - Speechless men (_Alali_), or - Ape-like men (_Pithecanthropi_) - | - Gorilla | - _Gorilla_ | Orang - Chimpanzee | | _Satyrus_ - _Engeco_ | | | Gibbon - | | | | _Hylobates_ - | | | | | - \------v------/ | | | - African \-------v--------/ - Man-like Apes Asiatic - | Man-like Apes - | | - \----------v-----------/ - =Man-like Apes= Nose apes - +Anthropoides+ _Nasalis_ - | | - Silk apes | Tall apes | - _Arctopitheci_ | _Semnopithecus_ | - | Clutch-tails | | | - | _Labidocerca_ | | | - | | | \-v----------/ - | | | Sea cat | Pavian - \-----v-------/ | _Cercopithecus_ | _Cynocephalus_ - Flap-tails | | | | - _Aphyocerca_ | | | | - \--------------v--------------/ - =Flat-nosed Apes= Tailed Narrow-nosed apes - +Platyrrhini+ _Catarrhina menocerca_ - | =Narrow-nosed= - | +Catarrhini+ - | | - | | - \--------------v---------------/ - =Apes= - +Simiæ+ - | - | - Semi-apes - _Prosimiæ_ - - -If we wish to arrive at a natural system, and consequently at the -pedigree of the Primates, we must go a step further still, and entirely -separate the Semi-apes, or Prosimiæ, (Huxley's last three families), -from Genuine Apes, or Simiæ (the first four families). For, as I have -already shown in my General Morphology, and explained in the last -chapter, the Semi-apes differ in many and important respects from -Genuine Apes, and in their individual forms are more closely allied to -the various other orders of Discoplacentalia. Hence the Semi-apes must -probably be considered as the remnants of the common primary group, out -of which the other orders of Discoplacentalia, and, it may be, all -Deciduata, have developed as two diverging branches. (Gen. Morph. ii. -pp. 148 and 153.) But man cannot be separated from the order of Genuine -Apes, or Simiæ, as he is in every respect more closely allied to the -higher Genuine Apes than the latter are to the lower Genuine Apes. - -_Genuine Apes_ (Simiæ) are universally divided into two perfectly -natural groups, namely, the Apes of the New World, or American Apes, and -the Apes of the Old World, which are indigenous to Asia and Africa, and -which formerly also existed in Europe. These two classes differ -principally in the formation of the nose, and they have been named -accordingly. American Apes have flat noses, so that the nostrils are in -front, not below; hence they are called _Flat Noses_ (Platyrrhini). On -the other hand, the Apes of the Old World have a narrow cartilaginous -bridge, and the nostrils turned downwards, as in man; they are, -therefore, called _Narrow Noses_ (Catarrhini). Further, the jaw, which -plays an important part in the classification of Mammals, is essentially -distinct in these two groups. All Catarrhinæ, or Apes of the Old World, -have exactly the same jaws as Man, namely, in each jaw four incisors -above and below, then on each side a canine tooth and five cheek teeth, -of which two are pre-molars and three molars, altogether thirty-two -teeth. But all Apes of the New World, all Platyrrhini, have four more -cheek teeth, namely, three pre-molars and three molars on each side, -above and below: they consequently possess thirty-six teeth. Only one -small group forms an exception to this rule, namely, the _Arctopitheci_, -or _Clawed Apes_, in whom the third molar has degenerated, and they -accordingly have on each half of their jaw three pre-molars and two -molars. They also differ from the other Platyrrhini by having claws on -the fingers of their hands and the toes of their feet, not nails like -Man and the other Apes. This small group of South American Apes, which -includes among others the well-known pretty little Midas-monkey and the -Jacchus, must probably be considered only as a peculiarly developed -lateral branch of the Platyrrhini. - -Now, if we ask what evidence can be drawn, as to the pedigree of Apes, -from the above facts, we must conclude that all the Apes of the New -World have developed out of one tribe, for they all possess the -characteristic jaw and the nasal formation of the Platyrrhini. In like -manner it follows that all the Apes of the Old World must be derived -from one and the same common primary form, which possessed the same -formation of nose and jaw as all the still living Catarrhini. Further, -it can scarcely be doubted that the Apes of the New World, taken as an -entire tribe, are either derived from those of the Old World, or (to -express it more vaguely and cautiously) both are diverging branches of -one and the same tribe of Apes. We also arrive at the exceedingly -important conclusion--which is of the utmost significance in regard to -Man's distribution on the earth's surface--that Man _has developed out -of the Catarrhini_. For we cannot discover a zoological character -distinguishing him in a higher degree from the allied Apes of the Old -World than that in which the most divergent forms of this group are -distinguished from one another. This is the important result of Huxley's -careful anatomical examination of the question, and it cannot be too -highly estimated. The anatomical differences between Man and the most -human-like Catarrhini (Orang, Gorilla, Chimpanzee) are in every respect -less than the anatomical differences between the latter and the lowest -stages of Catarrhini, more especially the Dog-like Baboon. This -exceedingly important conclusion is the result of an impartial -anatomical comparison of the different forms of Catarrhini. - -If, therefore, we recognise the natural system of animals as the guide -to our speculations, and establish upon it our pedigree, we must -necessarily come to the conclusion that _the human race is a small -branch of the group of Catarrhini, and has developed out of long since -extinct Apes of this group in the Old World_. Some adherents of the -Theory of Descent have thought that the American races of Men have -developed, independently of those of the Old World, out of American -Apes. I consider this hypothesis to be quite erroneous, for the complete -agreement of all mankind with the Catarrhini, in regard to the -characteristic formation of the nose and jaws, distinctly proves that -they are of the same origin, and that they developed out of a common -root after the Platyrrhini, or American Apes, had already branched off -from them. The primæval inhabitants of America, as is proved by numerous -ethnographical facts, immigrated from Asia, and partly perhaps from -Polynesia (or even from Europe). - -There still exist great difficulties in establishing an accurate -pedigree of the Human Race; this only can we further assert, that the -nearest progenitors of man were tail-less Catarrhini (Lipocerca), -resembling the still living Man-like Apes. These evidently developed at -a late period out of tailed Catarrhini (Menocerca), the original form of -Ape. Of those tail-less Catarrhini, which are now frequently called -Man-like Apes, or Anthropoides, there still exist four different genera -containing about a dozen different species. - -The largest Man-like Ape is the famous _Gorilla_ (called Gorilla engena, -or Pongo gorilla), which is indigenous to the tropics of western Africa, -and was first discovered by the missionary, Dr. Savage, in 1847, on the -banks of the river Gaboon. Its nearest relative is the _Chimpanzee_ -(Engeco troglodytes, or Pongo troglodytes), also indigenous to western -Africa, but considerably smaller than the Gorilla, which surpasses man -in size and strength. The third of the three large Man-like Apes is the -_Orang_, or _Orang Outang_, indigenous to Borneo and the other Sunda -Islands, of which two kindred species have recently been distinguished, -namely, the large Orang (Satyrus orang, or Pithecus satyrus) and the -small Orang (Satyrus morio, or Pithecus morio). Lastly, there still -exists in southern Asia the genus _Gibbon_ (Hylobates), of which from -four to eight different species are distinguished. They are considerably -smaller than the three first-named Anthropoides, and in most -characteristics differ more from Man. - -The tail-less Man-like Apes--especially since we have become more -intimately acquainted with the Gorilla, and its connection with Man by -the application of the Theory of Descent--have excited such universal -interest, and called forth such a flood of writings, that there is no -occasion for me here to enter into any detail about them. The reader -will find their relations to Man fully discussed in the excellent works -of Huxley,(26) Carl Vogt,(27) Büchner,(43) and Rolle.(28) I shall -therefore confine myself to stating the most important general -conclusion resulting from their thorough comparison with Man, namely, -that each one of the four Man-like Apes stands nearer to Man in one or -several respects than the rest, but that no one of them can in every -respect be called absolutely the most like Man. The Orang stands nearest -to Man in regard to the formation of the brain, the Chimpanzee in -important characteristics in the formation of the skull, the Gorilla in -the development of the feet and hands, and, lastly, the Gibbon in the -formation of the thorax. - -Thus, from a careful examination of the comparative anatomy of the -Anthropoides, we obtain a similar result to that obtained by Weisbach, -from a statistical classification and a thoughtful comparison of the -very numerous and careful measurements which Scherzer and Schwarz made -of the different races of Men during their voyage in the Austrian -frigate _Novara_ round the earth. Weisbach comprises the final result of -his investigations in the following words: "_The ape-like -characteristics of Man_ are by no means concentrated in one or another -race, but are distributed in particular parts of the body, among the -different races, in such a manner that each is endowed with some -heirloom of this relationship--one race more so, another less, and even -we Europeans cannot claim to be entirely free from evidences of this -relationship."[5] - -I must here also point out, what in fact is self-evident, that not one -of all the still living Apes, and consequently not one of the so-called -Man-like Apes, can be the progenitor of the Human Race. This opinion, in -fact, has never been maintained by thoughtful adherents of the Theory of -Descent, but it has been assigned to them by their thoughtless -opponents. The Ape-like progenitors of the Human Race are long since -extinct. We may possibly still find their fossil bones in the tertiary -rocks of southern Asia or Africa. In any case they will, in the -zoological system, have to be classed in the group of _tail-less -Narrow-nosed Apes_ (Catarrhini Lipocerci, or Anthropoides). - -The genealogical hypotheses, to which we have thus far been led by the -application of the Theory of Descent to Man, present themselves to every -clearly and logically reasoning person as the direct results from the -facts of comparative anatomy, ontogeny, and palæontology. Of course our -phylogeny can indicate only in a very general way the outlines of the -human pedigree. Phylogeny is the more in danger of becoming erroneous -the more rigorously it is applied in detail to special animal forms -known to us. However, we can, even now, with approximate certainty -distinguish at least the following twenty-two stages of the ancestors of -Man. Fourteen of these stages belong to the Vertebrata, and eight to the -Invertebrate ancestors of Man (Prochordata.) - - -THE CHAIN OF THE ANIMAL ANCESTORS, OR THE SERIES OF THE PROGENITORS, OF -MAN. - -(Comp. Ch. XX., XXI.; Plate XIV. and p. 22.) - -FIRST HALF OF THE SERIES OF THE ANCESTORS OF MAN. - -INVERTEBRATE ANCESTORS OF MAN (Prochordata). - -FIRST STAGE: +Monera+. - -The most ancient ancestors of Man, as of all other organisms, were -living creatures of the simplest kind imaginable, _organisms without -organs_, like the still living Monera. They consisted of simple, -homogeneous, structureless and formless little lumps of mucous or -albuminous matter (protoplasm), like the still living Protamoeba -primitiva. (Compare vol. i. p. 186, Fig. 1.) The _form value_ of these -most ancient ancestors of man was not even equal to that of a cell, but -merely that of a _cytod_ (compare vol. i. p. 347); for, as in the case -of all Monera, the little lump of protoplasm did not as yet possess a -cell-kernel. The first of these Monera _originated_ in the beginning of -the Laurentian period by _spontaneous generation_, or archigony, out of -so-called "inorganic combinations," namely, out of simple combinations -of carbon, oxygen, hydrogen, and nitrogen. The assumption of this -spontaneous generation, that is, of a mechanical origin of the first -organisms from inorganic matter, has been proved in our thirteenth -chapter to be a necessary hypothesis. (Compare vol. i. p. 338.) A -direct _proof_ of the earlier existence of this most ancient ancestral -stage, based upon the fundamental law of biogeny, is possibly still -furnished by the circumstance that, according to the assertions of many -investigators, in the beginning of the development of the egg, the -cell-kernel, or nucleus, disappears, and the egg-cell thus relapses to -the lower stage of the cytod (Monerula, p. 124; _relapse_ of the -nucleated plastid into a non-nucleated condition). The assumption of -this first stage is necessary for most important general reasons. - - -SECOND STAGE: +Amoebæ+. - -The second ancestral stage of Man, as of all the higher animals and -plants, is formed by _a simple cell_, that is, a little piece of -protoplasm enclosing a kernel. There still exist large numbers of -similar "single-celled organisms." Among them the common, simple Amoebæ -(vol. i. p. 188, Fig. 2) cannot have been essentially different from -these progenitors. The _form value_ of every Amoeba is essentially the -same as that still possessed by the egg of Man, and by the egg of all -other animals. (Vol. i. p. 189, Fig. 3.) The naked egg-cells of Sponges, -which creep about exactly like Amoebæ, cannot be distinguished from -them. The egg-cell of Man, which like that of most other animals is -surrounded by a membrane, resembles an enclosed Amoeba. The first -single-celled animals of this kind arose out of Monera by the -differentiation of the inner kernel and the external protoplasm; they -lived in the earlier Primordial period. An irrefutable proof that such -single-celled primæval animals really existed as the direct ancestors of -Man, is furnished according to the fundamental law of biogeny (vol. i. -p. 309) by the fact that the human egg is nothing more than a simple -cell. (Compare p. 124.) - - -THIRD STAGE: +Synamoebæ+. - -In order to form an approximate conception of the organisation of those -ancestors of Man which first developed out of the single-celled Primæval -animals, it is necessary to trace the changes undergone by the human egg -in the beginning of its individual development. It is just here that -ontogeny guides us with the greatest certainty on to the track of -phylogeny. We have already seen that the egg of Man (in the same way as -that of all other Mammals), after fructification has taken place, falls -by self-division into a mass of simple and equi-formal Amoeba-like cells -(vol. i. p. 190, Fig. 4 _D_). All these divided globules are at first -exactly like one another, naked cells containing a kernel, but without -covering; in many animals they show movements like those of the Amoebæ. -This ontogenetic stage of development which we called Morula (p. 125), -on account of its mulberry shape, is _a certain proof_ that in the early -primordial period there existed ancestors of man which possessed the -_form value_ of a mass of homogeneous, loosely connected cells. They may -be called a _community of Amoebæ_ (Synamoebæ). (Compare p. 127.) They -_originated_ out of the single-celled Primæval animals of the second -stage by repeated self-division and by the permanent union of the -products of this division. - - -FOURTH STAGE: +Ciliated Larva (Planæada)+. - -In the course of the ontogenesis of most of the lower animals, and also -in that of the lowest Vertebrate animals, the Lanceolate Animals, or -Amphioxus, there first develops out of the Morula (Frontispiece, Fig. 3) -a ciliated larva (planula). Those cells, lying on the surface of the -homogeneous mass of cells, extend hair-like processes, or fringes of -hairs, which by striking against the water keep the whole body rotating. -The round many-celled body thus becomes differentiated, in that the -external cells covered with cilia differ from the non-ciliated internal -cells (Frontispiece, Fig. 4). In Man and in all other Vertebrate animals -(with the exception of the Amphioxus), as well as in all Arthropoda, -this stage of the ciliated larva has been lost, in the course of time, -by abbreviated inheritance. There must, however, have existed ancestors -of Man in the early Primordial period which possessed the form value of -these ciliated larvæ (Planæa, p. 125). A certain proof of this is -furnished by the Amphioxus, which is on the one hand related by blood to -Man, but on the other has retained down to the present day the stage of -the planula. - - -FIFTH STAGE: +Primæval Stomach Animals (Gastræada)+. - -In the course of the individual development of Amphioxus, as well as in -the most different lower animals, there first arises out of the planula -the extremely important form of larva which we have named _stomach -larva_, or _gastrula_ (p. 126; Frontispiece, Fig. 5, 6). According to -the fundamental law of biogeny this gastrula proves the former existence -of an independent form of primæval animal of the same structure, and -this we have named primæval stomach animal, or Gastræa (pp. 127, 128). -These Gastræada must have existed during the older Primordial period, -and they must have also included the ancestors of man. A _certain -proof_ of this is furnished by the Amphioxus, which in spite of its -blood relationship to Man still passes through the stage of the gastrula -with a simple intestine and a double intestinal wall. (Compare Plate X. -Fig. _B 4_.) - - -SIXTH STAGE: +Gliding Worms (Turbellaria)+. - -The human ancestors of the sixth stage which originated out of the -Gastræada of the fifth stage, were low worms, which, of all the forms of -worms known to us, were most closely allied to the Gliding Worms, or -Turbellaria, or at least upon the whole possessed their form value. Like -the Turbellaria of the present day, the whole surface of their body was -covered with cilia, and they possessed a simple body of an oval shape, -entirely without appendages. These acoelomatous worms did not as yet -possess a true body-cavity (coelom) nor blood. They _originated_ in the -early primordial period out of the Gastræada, by the formation of a -middle germ-layer, or muscular layer, and also by the further -differentiation of the internal parts into various organs; more -especially the first formation of a nervous system, the simplest organs -of sense, the simplest organs for secretion (kidneys) and generation -(sexual organs). The proof that human ancestors existed of a similar -formation, is to be looked for in the circumstance that comparative -anatomy and ontogeny point to the lower acoelomatous Worms as the common -primary form, not merely of all higher Worms, but also of the four -higher tribes of animals. Now, of all the animals known to us, the -Turbellaria, which possess neither a body-cavity nor blood, are most -closely allied to these primæval acoelomatous Primary Worms. - - -SEVENTH STAGE: +Soft Worms (Scolecida)+. - -Between the Turbellaria of the preceding stage and the Sack Worms of the -next stage, we must necessarily assume at least one connecting -intermediate stage. For the Tunicata, which of all known animals stand -nearest to the eighth stage, and the Turbellaria which most resemble the -sixth stage, indeed both belong to the lower division of the unsegmented -Worms; but still these two divisions differ so much from one another in -their organization, that we must necessarily assume the earlier -existence of extinct intermediate forms between the two. These -connecting links, of which no fossil remains exist, owing to the soft -nature of their bodies, we may comprise as _Soft Worms_, or Scolecida. -They developed out of the Turbellaria of the sixth stage by forming a -true body-cavity (a coelom) and blood in their interior. It is difficult -to say which of the still living Coelomati are nearest akin to these -extinct Scolecida; it may be the Acorn-worms (Balanoglossus). The proof -that even the direct ancestors of man belonged to these Scolecida, is -furnished by the comparative anatomy and the ontogeny of Worms and of -the Amphioxus. The form value of this stage must moreover have been -represented by several very different intermediate stages, in the wide -gap between Turbellaria and Tunicata. - - -EIGHTH STAGE: +Sack Worms (Himatega)+. - -Under the name of Sack worms, or Himatega, we here allude in the eighth -place to those Coelomati, out of which the most ancient skull-less -Vertebrata were directly developed. Among the Coelomati of the present -day, the _Ascidians_ are the nearest relatives of these exceedingly -remarkable Worms, which connect the widely differing classes of -Invertebrate and Vertebrate animals. That the ancestors of man really -existed during the primordial period in the form of these Himatega, is -_distinctly proved_ by the exceedingly remarkable and important -agreement presented by the ontogeny of the Amphioxus and the Ascidia. -(Compare Plates XII. and XIII., also pp. 152, 200, etc.) From this fact -the earlier existence of Sack Worms may be inferred; they of all known -worms were most closely related to our recent Tunicates, especially to -the freely swimming young forms or larvæ of the simple Sea-squirts -(Ascidia, Phallusia). They originated out of the worms of the seventh -stage by the formation of a dorsal nerve-marrow (medulla tube), and by -the formation of the spinal rod (chorda dorsalis) which lies below it. -It is just the position of this central spinal rod, or axial skeleton, -between the dorsal marrow on the dorsal side, and the intestinal canal -on the ventral side, which is most characteristic of all Vertebrate -animals, including man, but also of the larvæ of the Ascidia. The form -value of this stage nearly corresponds with that which the larvæ of the -simple Sea-squirts possess at the time when they show the beginning of -the dorsal marrow and spinal rod. (Plate XII. Fig. _A 5_: compare the -explanation of these figures in the Appendix.) - - -SECOND HALF OF THE SERIES OF HUMAN ANCESTORS. VERTEBRATE ANIMAL -ANCESTORS OF MAN (Vertebrata). - -NINTH STAGE: +Skull-less Animals (Acrania)+. - -The series of human ancestors, which in accordance with their whole -organisation we have to consider as Vertebrate animals, begins with the -Skull-less animals, or Acrania, of whose nature the still living -Lancelet (Amphioxus lanceolatus, Plate XII. _B_, XIII. _B_) gives us a -faint idea. Since this little animal in its earliest embryonal state -entirely agrees with the Ascidia, and in its further development shows -itself to be a true Vertebrate animal, it forms a direct transition from -the Vertebrata to the Invertebrata. Even if the human ancestors of the -ninth stage in many respects differed from the Amphioxus--the last -surviving representative of the Skull-less animals--yet they must have -resembled it in its most essential characteristics, in the absence of -head, skull, and brain. Skull-less animals of such structure--out of -which animals with skulls developed at a later period--lived during the -primordial period, and originated out of the Himatega of the eighth -stage by the formation of the metamera, or body segments, as also by the -further differentiation of all organs, especially the more perfect -development of the dorsal nerve-marrow and the spinal rod lying below -it. Probably the separation of the two sexes (gonochorism) also began at -this stage, whereas all the previously mentioned invertebrate ancestors -(apart from the 3--4 first neutral stages) exhibited the condition of -hermaphrodites (hermaphroditism). (Compare vol. i. p. 196.) The _certain -proof_ of the former existence of these skull-less and brainless -ancestors of man, is furnished by the comparative anatomy and the -ontogeny of the Amphioxus and of the Craniota. - - -TENTH STAGE: +Single-nostriled Animals (Monorrhina)+. - -Out of the Skull-less ancestors of man there arose in the first place -animals with skulls, or Craniota, of the most imperfect nature. The -lowest stage of all still living Craniota is occupied by the class of -round-mouthed animals, or Cyclostoma, namely, the Hag (Myxinoidea) and -Lampreys (Petromyzontia). From the internal organization of these -single-nostriled animals, or Monorrhina, we can form an approximate idea -of the nature of the human ancestors of the tenth stage. In the former, -as also in the latter, skull and brain must have been of the simplest -form, and many important organs, as for example, the swimming bladder, -the sympathetic nerve, the spleen, the jaw skeleton, and both pairs of -legs, may probably as yet not have existed. However, the pouch gills and -the round sucking mouth of the Cyclostoma must probably be looked upon -as purely adaptive characteristics, which did not exist in the -corresponding stage of ancestors. The single-nostriled animals -originated during the primordial period out of the skull-less animals by -the anterior end of the dorsal marrow developing into the brain, and the -anterior end of the dorsal chord into the skull. The _certain proof_ -that such single-nostriled and jawless ancestors of man did exist, is -found in the "comparative anatomy of the Myxinoidea." - - -ELEVENTH STAGE: +Primæval Fish (Selachii.)+. - -Of all known Vertebrate animals, the ancestors of the Primæval Fish -probably showed most resemblance to the still living Sharks (Squalacei). -They _originated_ out of the single-nostriled animals by the division of -the single nostril into two lateral halves, by the formation of a -sympathetic nervous system, a jaw skeleton, a swimming bladder, and two -pairs of legs (breast fins or fore-legs, and ventral fins or hind-legs). -The internal organisation of this stage may probably, upon the whole, -have corresponded to the lowest species of Sharks known to us; the -swimming bladder was however more strongly developed; in the case of the -latter it exists only as a rudimentary organ. They _lived_ as early as -the Silurian period, as is proved by the fossil remains of sharks (teeth -and fin spines) from the Silurian strata. A _certain proof_ that the -Silurian ancestors of man and of all the other double-nostriled animals -were nearest akin to the Selachii, is furnished by the comparative -anatomy of the latter; it shows that the relations of organisation in -all Amphirrhina can be derived from those of the Selachii. - - -TWELFTH STAGE: +Mud Fish (Dipneusta)+. - -Our twelfth ancestral stage is formed by Vertebrate animals which -probably possessed a remote resemblance to the still living Salamander -fish (Ceratodus, Protopterus, Lepidosiren, p. 212). They _originated_ -out of the Primæval fish (probably at the beginning of the palæolithic, -or primary period) by adaptation to life on land, and by the -transformation of the swimming bladder into an air-breathing lung, and -of the nasal cavity (which now opened into the cavity of the mouth) -into air passages. The series of the ancestors of man which breathed air -through lungs began at this stage. Their organisation may probably in -many respects have agreed with that of the still living Ceratodus and -Protopterus, but at the same time may have been very different. They -probably lived at the beginning of the Devonian period. Their existence -is _proved_ by comparative anatomy, which shows the Dipneusta to be an -intermediate stage between the Selachii and Amphibia. - - -THIRTEENTH STAGE: +Gilled Amphibians (Sozobranchia)+. - -Out of those Mud Fish, which we considered the primary forms of all the -Vertebrata which breathe through lungs, there developed the class of -Amphibia as the main line (pp. 205, 216). Here began the five-toed -formation of the foot (the Pentadactyla), which was thence transmitted -to the higher Vertebrata, and finally also to Man. The gilled Amphibians -must be looked upon as our most ancient ancestors of the class of -Amphibia; besides possessing lungs they retained throughout life regular -gills, like the still living Proteus and Axolotl (p. 218). They -_originated_ out of the Dipneusta by the transformation of the paddling -fins into five-toed legs, and also by the more perfect differentiation -of various organs, especially of the vertebral column. In any case they -existed about the middle of the palæolithic, or primary period, possibly -even before the Coal period; for fossil Amphibia are found in coal. The -_proof_ that similar gilled Amphibians were our direct ancestors, is -given by the comparative anatomy and the ontogeny of Amphibia and -Mammals. - - -FOURTEENTH STAGE: +Tailed Amphibians (Sozura)+. - -Our amphibious ancestors which retained their gills throughout life, -were replaced at a later period by other Amphibia, which, by -metamorphosis, lost the gills which they had possessed in early life, -but retained the tail, as in the case of the salamanders and newts of -the present day. (Compare p. 218.) They _originated_ out of the gilled -Amphibians by accustoming themselves in early life to breathe only -through gills, and later in life only through lungs. They probably -existed even in the second half of the primary, namely, during the -Permian period, but possibly even during the Coal period. The _proof_ of -their existence lies in the fact that tailed Amphibians form a necessary -intermediate link between the preceding and succeeding stages. - - -FIFTEENTH STAGE: +Primæval Amniota (Protamnia)+. - -The name Protamnion we have given to the primary form of the three -higher classes of Vertebrate animals, out of which the Proreptilia and -the Promammalia developed as two diverging branches (p. 222). It -_originated_ out of unknown tailed Amphibia by the complete loss of the -gills, by the formation of the amnion, of the cochlea, and of the round -window in the auditory organ, and of the organs of tears. It probably -originated in the beginning of the mesolithic or secondary period, -perhaps even towards the end of the primary, in the Permian period. The -_certain proof_ that it once existed lies in the comparative anatomy and -the ontogeny of the Amniota; for all Reptiles, Birds, and Mammals, -including Man, agree in so many important characteristics that they -must, with full assurance, be admitted to be the descendants of a -single common primary form, namely, of the Protamnion. - - -SIXTEENTH STAGE: +Primary Mammals (Promammalia)+. - -We now find ourselves more at home with our ancestors. From the -sixteenth up to the twenty-second stage they all belong to the large and -well known class of Mammals, the confines of which we ourselves have as -yet not transgressed. The common, long since extinct and unknown primary -forms of all Mammalia, which we have named Promammalia, were at all -events, of all still living animals, of the class most closely related -to the Beaked animals, or Ornithostoma (Ornithorhynchus, Echidna, p. -233). They differed from the latter, however, by the teeth present in -their jaws. The formation of the beak in the Beaked animals of the -present day must be looked upon as an adaptive characteristic which -developed at a later period. The Promammalia arose out of the Protamnia -(probably only at the beginning of the secondary period, namely, in the -Trias) by various advances in their internal organisation, as also by -the transformation of the epidermal scales into hairs, and by the -formation of a mammary gland which furnished milk for the nourishment of -the young ones. The _certain proof_ that the Promammalia--inasmuch as -they are the common primary forms of all Mammals--also belong to our -ancestors, lies in the comparative anatomy and the ontogeny of Mammalia -and Man. - - -SEVENTEENTH STAGE: +Pouched Animals (Marsupialia)+. - -The three sub-classes of Mammalia--as we have already seen--stand in -such a relation to one another that the Marsupials, both as regards -their anatomy and their ontogeny and phylogeny, form the direct -transition from the Monotrema to Placental animals (p. 247). -Consequently, human ancestors must also have existed among Marsupials. -They _originated_ out of the Monotrema--which include the primary -Mammalia, or Promammalia--by the division of the cloaca into the rectum -and the urogenital sinus, by the formation of a nipple on the mammary -gland, and by the partial suppression of the clavicles. The oldest -Marsupials at all events existed as early as the Jura period (perhaps -even in the Trias); during the Chalk period they passed through a series -of stages preparing the way for the origin of Placentalia. The certain -proof of our derivation from Marsupials--nearly akin to the still living -opossum and kangaroo in their essential inner structure--is furnished by -the comparative anatomy and the ontogeny of Mammalia. - - -EIGHTEENTH STAGE: +Semi-apes (Prosimiæ)+. - -The small group of Semi-apes, as we have already seen, is one of the -most important and most interesting orders of Mammalia. It contains the -direct primary forms of Genuine Apes, and thus also of Man. Our Semi-ape -ancestors probably possessed only a very faint external resemblance to -the still living, short-footed Semi-apes (Brachytarsi), especially the -Maki, Indri, and Lori (p. 256). They _originated_ (probably at the -beginning of the Cenolithic, or Tertiary period) out of Marsupials of -Rat-like appearance by the formation of a placenta, the loss of the -marsupium and the marsupial bones, and by the higher development of the -commissures of the brain. The _certain proof_ that Genuine Apes, and -hence also our own race, are the direct descendants of Semi-apes, is to -be found in the comparative anatomy and the ontogeny of Placental -animals. - - -NINETEENTH STAGE: +Tailed Apes (Menocerca)+. - -Of the two classes of Genuine Apes which developed out of the Semi-apes, -it is only the narrow-nosed, or Catarrhini, which are closely related by -blood to Man. Our older ancestors from this group probably resembled the -still living Nose-apes and Holy-apes (Semnopithecus), which possess jaws -and narrow noses like Man, but have a long tail, and their bodies -densely covered with hair (p. 271). The Tailed Apes with narrow noses -(Catarrhini Menocerci) _originated_ out of Semi-apes by the -transformation of the jaw, and by the claws on their toes becoming -changed into nails; this probably took place as early as the older -Tertiary period. The _certain proof_ of our derivation from Tailed -Catarrhini is to be found in the comparative anatomy and the ontogeny of -Apes and of Man. - - -TWENTIETH STAGE: +Man-like Apes (Anthropoides)+. - -Of all still living Apes the large tail-less, narrow-nosed Apes, namely, -the Orang and Gibbon in Asia, the Gorilla and Chimpanzee in Africa, are -most nearly akin to Man. It is probable that these Man-like Apes, or -Anthropoides, originated during the Mid-tertiary period, namely, in the -Miocene period. They developed out of the Tailed Catarrhini of the -preceding stage--with which they essentially agree--by the loss of the -tail, the partial loss of the hairy covering and by the excessive -development of that portion of the brain just above the facial portion -of the skull. There do not exist direct human ancestors among the -Anthropoides of the present day, but they certainly existed among the -unknown extinct Human Apes of the Miocene period. The _certain proof_ of -their former existence is furnished by the comparative anatomy of -Man-like Apes and of Man. - - -TWENTY-FIRST STAGE: +Ape-like Men (Pithecanthropi)+. - -Although the preceding ancestral stage is already so nearly akin to -genuine Men that we scarcely require to assume an intermediate -connecting stage, still we can look upon the speechless Primæval Men -(Alali) as this intermediate link. These Ape-like men, or -Pithecanthropi, very probably existed towards the end of the Tertiary -period. They originated out of the Man-like Apes, or Anthropoides, by -becoming completely habituated to an upright walk, and by the -corresponding stronger differentiation of both pairs of legs. The fore -hand of the Anthropoides became the human hand, their hinder hand became -a foot for walking. Although these Ape-like Men must not merely by the -external formation of their bodies, but also by their internal mental -development, have been much more akin to real Men than the Man-like Apes -could have been, yet they did not possess the real and chief -characteristic of man, namely, the articulate human language of words, -the corresponding development of a higher consciousness, and the -formation of ideas. The _certain proof_ that such Primæval Men without -the power of speech, or Ape-like Men, must have preceded men possessing -speech, is the result arrived at by an inquiring mind from comparative -philology (from the "comparative anatomy" of language), and especially -from the history of the development of language in every child ("glottal -ontogenesis") as well as in every nation ("glottal phylogenesis"). - - -TWENTY-SECOND STAGE: +Men (Homines)+. - -Genuine Men _developed_ out of the Ape-like Men of the preceding stage -by the gradual development of the animal language of sounds into a -connected or articulate language, of words. The development of this -function, of course, went hand in hand with the development of its -organs, namely, the higher differentiation of the larynx and the brain. -The transition from speechless Ape-like Men to Genuine or Talking Men -probably took place at the beginning of the Quaternary period, namely, -in the Diluvial period, but possibly even at an earlier date, in the -more recent Tertiary. As, according to the unanimous opinion of most -eminent philologists, all human languages are not derived from a common -primæval language, we must assume a polyphyletic origin of language, and -in accordance with this a polyphyletic transition from speechless -Ape-like Men to Genuine Men. - - -ANCESTRAL SERIES OF THE HUMAN PEDIGREE. - -M N = Boundary between the Invertebrate and Vertebrate Ancestors. - - - --------------------------------------------------------------------------------------------------- - _Epochs of the_ | _Geological Periods_ | _Animal_ | _Nearest Living_ - _Organic_ | _of the_ | _Ancestral Stages_ | _Relatives of the_ - _History of the_| _Organic History_ | _of_ | _Ancestral Stages._ - _Earth._ | _of the Earth._ | _Man._ | - --------------------------------------------------------------------------------------------------- - { { 1. Monera { _Protogenes_ - { { (_Monera_) { _Protamoeba_ - { { - { { 2. Single-celled { Simple Amoebæ - { { Primæval animals { (_Automoebæ_) - { { - { { 3. Many-celled { Communities of - { { Primæval animals { Amoebæ - { { { (_Synamoebæ_) - { { - { { 4. Ciliated planulæ { Planula larvæ - { { (_Planæada_) { - I. { { - ARCHILITHIC { 1. Laurentian Period { 5. Primæval Intestinal { Gastrula larvæ - OR { { animals (_Gastræada_) { - { 2. Cambrian Period { - PRIMORDIAL { { 6. Gliding Worms { _Rhabdocoela_ - EPOCH { 3. Silurian Period { (_Turbellaria_) { _Dendrocoela_ - { { - { { 7. Soft-worms { ?Between the Sea-squirts - { { (_Scolecida_) { and Gliding worms - { { - { { 8. Sack worms { Sea-squirts - { { (_Himatega_) { (_Ascidiæ_) - { { M.................................................N - { { 9. Skull-less { Lancelets - { { (_Acrania_) { (_Amphioxi_) - { { - { { 10. Single-nostriled { Lampreys - { { (_Monorrhina_) { (_Petromyzonta_) - { (Compare p. 22, and { - { Plate XIV. and its { 11. Primæval fish { Sharks - { explanation.) { (_Selachii_) { (_Squalacei_) - --------------------------------------------------------------------------------------------------- - { 4. Devonian Period { 12. Salamander fish { Mud fish - II. { { (_Dipneusta_) { (_Protopteri_) - PALÆOLITHIC { 5. Coal Period { - OR { { 13. Gilled Amphibia { (_Proteus_) - { 6. Permian Period { (_Sozobranchia_) { Axolotl (_Siredon_) - PRIMARY { { - EPOCH { { 14. Tailed Amphibia { Water-newts - { { (_Sozura_) { (_Tritons_) - --------------------------------------------------------------------------------------------------- - { { 15. Primæval Amniota { ?Between the Tailed-Amphibia - III. { { (_Protamnia_) { and Primary - MESOLITHIC { 7. Trias Period { { mammals - OR { { - { 8. Jura Period { 16. Primary Mammals { Beaked animals - SECONDARY { { (_Promammalia_) { (_Monotrema_) - EPOCH { 9. Chalk Period { - { { 17. Pouched animals { Pouched rats - { { (_Marsupialia_) { (_Didelphys_) - --------------------------------------------------------------------------------------------------- - { { 18. Semi-apes { Lori (_Stenops_) - { { (_Prosimiæ_) { Maki (_Lemur_) - { { - IV. { { 19. Tailed Narrow-nosed { Nose apes - CENOLITHIC { 10. Eocene Period { Apes { Holy apes - OR { { - { 11. Miocene Period { 20. Men-like Apes or { Gorilla, Chimpanzee, - TERTIARY { { Tail-less Narrow-nosed { Orang, - EPOCH { 12. Pliocene Period { Apes { Gibbon - { { - { { 21. Speechless Men or { Deaf and Dumb, - { { Ape-like Men { Cretins or - { { { Microcephali - --------------------------------------------------------------------------------------------------- - V. { { { - QUATERNARY { 13. Diluvial Period { 22. Talking Men { Australians and - EPOCH { 14. Alluvial Period { { Papuans - - - - -CHAPTER XXIII. - -MIGRATION AND DISTRIBUTION OF MANKIND. HUMAN SPECIES AND HUMAN RACES. - - - Age of the Human Race.--Causes of its Origin.--The Origin of - Human Language.--Monophyletic or Single, Polyphyletic or - Multiple Origin of the Human Race.--Derivation of Man from many - Pairs.--Classification of the Human Races.--System of Twelve - Species of Men.--Woolly-haired Men, or Ulotrichis.--Bushy-haired - (Papuans, Hottentots).--Fleecy-haired (Caffres, - Negroes).--Straight-haired men, or Lissotrichi.--Stiff-haired - (Australians, Malays, Mongols, Arctic, and American - Tribes).--Curly-haired (Dravidas, Nubians, Midlanders).--Number - of Population.--Primæval Home of Man (South Asia, or - Lemuria).--Nature of Primæval Men.--Number of Primæval Languages - (Monoglottists and Polyglottists).--Divergence and Migration of - the Human Race.--Geographical Distribution of the Human Species. - - -The rich treasure of knowledge we possess in the comparative anatomy and -the history of the development of Vertebrate animals, enables us even -now to establish the most important outlines of the human pedigree in -the way we have done in the last chapter. One must, however, not expect -to be able to survey satisfactorily in every detail the history or -phylogeny of the human species which will henceforth form the basis of -Anthropology, and of all other sciences. The complete development of -this most important science--of which we can only lay the first -foundation--must remain reserved for the more accurate and extensive -investigations of a future time. This applies also to those more special -questions of human phylogeny at which it is desirable before concluding -to take a cursory glance, namely, the question of the time and place of -the origin of the human race, as also of the different species and races -into which it has differentiated. - -In the first place, the period of the earth's history, within which the -slow and gradual transmutation of the most man-like apes into the most -ape-like men took place, can of course not be determined by years, nor -even by centuries. This much can, however, with full assurance be -maintained, for reasons given in the last chapter, that Man is derived -from Placental animals. Now, as fossil remains of these Placentalia are -found only in the tertiary rocks, the human race can at the earliest -have developed only within the Tertiary period out of perfected man-like -apes. What seems most probable is that this most important process in -the history of terrestrial creation occurred towards the end of the -Tertiary period, that is in the Pliocene, perhaps even in the Miocene -period, but possibly also not until the beginning of the Diluvial -period. At all events Man, as such, lived in central Europe as early as -the Diluvial period, contemporaneously with many large, long since -extinct mammals, especially with the diluvial elephant, or mammoth -(Elephas primigenius), the woolly-haired rhinoceros (Rhinoceros -tichorrhinus), the giant deer (Cervus euryceros), the cave bear (Ursus -spelæus), the cave hyæna (Hyæna spelæa), the cave lion (Felis spelæus), -etc. The results brought to light by recent geology and archæology as to -these fossil men and their animal contemporaries of the diluvial period, -are of the greatest interest. But as a closer examination of them would -occupy too much of my limited space, I must confine myself here to -setting forth their great general importance, and refer for particulars -to the numerous writings which have recently been published on the -Primæval History of Man, more especially to the excellent works of -Charles Lyell,(30) Carl Vogt,(27) Friedrich Rolle,(28) John Lubbock,(44) -L. Büchner,(43) etc. - -The numerous and interesting discoveries presented to us by these -extensive investigations of late years on the primæval history of the -human race, place the important fact (long since probable for many other -reasons) beyond a doubt, that the human race, as such, has existed for -more than twenty thousand years. But it is also probable that more than -a hundred thousand years, perhaps many hundred thousands of years, have -elapsed since its first appearance; and, in contrast to this, it must -seem very absurd that our calendars still represent the "Creation of the -World, according to Calvisius," to have taken place 5821 years ago. - -Now, whether we reckon the period during which the human race, as such, -has existed and diffused itself over the earth, as twenty thousand, a -hundred thousand, or many hundred thousands of years, the lapse of time -is in any case immensely small in comparison with the inconceivable -length of time which was requisite for the gradual development of the -long chain of human ancestors. This is evident even from the small -thickness of all Diluvial deposits in comparison with the Tertiary, and -of these again in comparison with the preceding deposits. (Compare p. -22.) But the infinitely long series of slowly and gradually developing -animal forms from the simplest Moneron to the Amphioxus, from this to -the Primæval Fish, from the Primæval Fish to the first Mammal, and -again, from the latter to Man, also require for their historical -development a succession of periods probably comprising many thousands -of millions of years. (Compare vol. i. p. 129.) - -Those processes of development which led to the origin of the most -Ape-like Men out of the most Man-like Apes must be looked for in the two -adaptational changes which, above all others, are distinctive of Man, -namely, _upright walk_ and _articulate speech_. These two -_physiological_ functions necessarily originated together with two -corresponding _morphological_ transmutations, with which they stand in -the closest correlation, namely, the _differentiation of the two pairs -of limbs and the differentiation of the larynx_. The important -perfecting of these organs and their functions must have necessarily and -powerfully reacted upon the differentiation of the brain and the mental -activities dependent upon it, and thus have paved the way for the -endless career in which Man has since progressively developed, and in -which he has far outstripped his animal ancestors. (Gen. Morph. ii. p. -430.) - -The first and earliest of these three great processes in the development -of the human organism probably was the _higher differentiation and the -perfecting of the extremities_ which was effected by the _habit of an -upright walk_. By the fore feet more and more exclusively adopting and -retaining the function of grasping and handling, and the hinder feet -more and more exclusively the function of standing and walking, there -was developed that contrast between the hand and foot which is indeed -not exclusively characteristic of man, but which is much more strongly -developed in him than in the apes most like men. This differentiation of -the fore and hinder extremities was, however, not merely most -advantageous for their own development and perfecting, but it was -followed at the same time by a whole series of very important changes in -other parts of the body. The whole vertebral column, and more especially -the girdle of the pelvis and shoulders, as also the muscles belonging to -them, thereby experienced those changes which distinguish the human body -from that of the most man-like apes. These transmutations were probably -accomplished long before the origin of articulate speech; and the human -race thus existed for long, with an upright walk and the characteristic -human form of body connected with it, before the actual development of -human language, which would have completed the second and the more -important part of human development. We may therefore distinguish a -special (21st) stage in the series of our human ancestors, namely, -Speechless Man (Alalus), or Ape-man (Pithecanthropus), whose body was -indeed formed exactly like that of Man in all essential characteristics, -but who did not as yet possess articulate speech. - -The origin of _articulate language_, and the _higher differentiation and -perfecting of the larynx_ connected with it, must be looked upon as only -a later, and the most important stage in the process of the development -of Man. It was, doubtless, this process which above all others helped to -create the deep chasm between man and animal, and which also first -caused the most important progress in the mental activity and the -perfecting of the brain connected with it. There indeed exists in very -many animals a language for communicating sensations, desires, and -thoughts, partly a language of gestures, partly a language of feeling or -touch, partly a language of cries or sounds, but a real language of -words or ideas, a so-called "articulate" language, which by abstraction -changes sounds into words, and words into sentences, belongs, as far as -we know, exclusively to Man. - -The origin of human language must, more than anything else, have had an -ennobling and transforming influence upon the mental life of Man, and -consequently upon his brain. The higher differentiation and perfecting -of the brain and mental life as its highest function developed in direct -correlation with its expression by means of speech. Hence, the highest -authorities in comparative philology justly see in the development of -human speech the most important process which distinguishes Man from his -animal ancestors. This has been especially set forth by August -Schleicher, in his treatise "On the Importance of Speech for the Natural -History of Man."(34) In this relation we see one of the closest -connections between comparative zoology and comparative philology; and -here the theory of development assigns to the latter the task of -following the origin of language step by step. This task, as interesting -as it is important, has of late years been successfully undertaken by -many inquirers, but more especially by Wilhelm Bleek, who has been -occupied for seventeen years in South Africa with the study of the -languages of the lowest races of men, and hence has been enabled to -solve the question. August Schleicher more especially discusses, in -accordance with the theory of selection, how the various forms of -speech, like all other organic forms and functions, have developed by -the process of natural selection, and have divided into many species and -dialects. - -I have no space here to follow the process of the formation of language, -and must refer in regard to this to the above-mentioned important work -of Wilhelm Bleek, "On the Origin of Language."(35) But we have still to -mention one of the most important results of comparative philology, -which is of the highest importance to the genealogy of the human -species, that is, that _human language was probably of a multiple, or -polyphyletic origin_. Human speech, as such, did not develop probably -until the genus of Speechless or Primæval Man, or Ape Man, had -separated into several kinds or species. In each of these human species, -and perhaps even in the different sub-species and varieties of this -species, language developed freely and independently of the others. At -least Schleicher, one of the first authorities on the subject, maintains -that "even the beginnings of language--in sounds as well as in regard to -ideas and views which were reflected in sounds, and further, in regard -to their capability of development--must have been different. For it is -positively impossible to trace all languages to one and the same -primæval language. An impartial investigation rather shows that there -are as many primæval languages as there are races."(34) In like manner, -Friederich Müller(41) and other eminent linguists assume a free and -independent origin of the families of languages and their primæval -stocks. It is well known, however, that the boundaries of these tribes -of languages and their ramifications are by no means always the -boundaries of the different human species, or the so-called "races," -distinguished by us on account of their bodily characteristics. This, -as well as the complicated relations of the mixture of races, and the -various forms of hybrids, is the great difficulty lying in the way of -tracing the human pedigree in its individual branches, species, races, -varieties, etc. - -In spite of these great and serious difficulties, we cannot here refrain -from taking one more cursory glance at the ramification of the human -pedigree, and at the same time considering, from the point of view of -the theory of descent, the much discussed question of the monophyletic -or polyphyletic origin of the human race, and its species or races. As -is well known, two great parties have for a long time been at war with -each other upon this question; the _monophylists_ (or monogenists) -maintain the unity of origin and the blood relationship of all races of -men. The _polyphylists_ (or polygenists), on the other hand, are of -opinion that the different races of men are of independent origin. -According to our previous genealogical investigations we cannot doubt -that, at least in a _wide sense_, the monophyletic opinion is the right -one. For even supposing that the transmutation of Man-like Apes into Men -had taken place several times, yet those Apes themselves would again be -allied by the one pedigree common to the whole order of Apes. The -question therefore would always be merely about a nearer or remoter -degree of blood relationship. In a _narrower sense_, on the other hand, -the polyphylist's opinion would probably be right, inasmuch as the -different primæval languages have developed quite independently of one -another. Hence, if the origin of an articulate language is considered as -the real and principal act of humanification, and the species of the -human race are distinguished according to the roots of their language, -it might be said that the different races of men had originated, -independently of one another, by different branches of primæval, -speechless men directly springing from apes, and forming their own -primæval language. Still they would of course be connected further up or -lower down at their root, and thus all would finally be derived from a -common primæval stock. - -While we hold the latter of these convictions, and while we for many -reasons believe that the different species of speechless primæval men -were all derived from a common ape-like human form, we do not of course -mean to say that _all men are descended from one pair_. This latter -supposition, which our modern Indo-Germanic culture has taken from the -Semitic myth of the Mosaic history of creation, is by no means tenable. -The whole of the celebrated dispute, as to whether the human race is -descended from a single pair or not, rests upon a completely false way -of putting the question. It is just as senseless as the dispute as to -whether all sporting dogs or all race-horses are descended from a single -pair. We might with equal justice ask whether all Germans or all -Englishmen are "descended from a single pair," etc. A "first human -pair," or "a first man," has in fact never existed, any more than there -ever existed a first pair or a first individual of Englishmen, Germans, -race-horses, or sporting dogs. The origin of a new species, of course, -always results from an existing species, by a long chain of many -different individuals sharing the slow process of transformation. -Supposing that we had all the different pairs of Human Apes and Ape-like -Men before us--which belong to the true ancestors of the human race--it -would even then be quite impossible (without doing so most arbitrarily) -to call any one of these pairs of ape-like men "the first pair." As -little can we derive each of the twelve races or species of men, which -we shall consider directly, from a "first pair." - -The difficulties met with in classifying the different races or species -of men are quite the same as those which we discover in classifying -animal and vegetable species. In both cases forms apparently quite -different are connected with one another by a chain of intermediate -forms of transition. In both cases the dispute as to what is a kind or a -species, what a race or a variety, can never be determined. Since -Blumenbach's time, as is well known, it has been thought that mankind -may be divided into five races or varieties, namely: (1) the Ethiopian, -or black race (African negro); (2) the Malayan, or brown race (Malays, -Polynesians, and Australians); (3) the Mongolian, or yellow race (the -principal inhabitants of Asia and the Esquimaux of North America); (4) -the Americans, or red race (the aborigines of America); and (5) the -Caucasian, or white race (Europeans, north Africans, and south-western -Asiatics). All of these five races of men, according to the Jewish -legend of creation, are said to have been descended from "a single -pair"--Adam and Eve,--and in accordance with this are said to be -varieties of one kind or species. If, however, we compare them without -prejudice, there can be no doubt that the differences of these five -races are as great and even greater than the "specific differences" by -which zoologists and botanists distinguish recognised "good" animal and -vegetable species ("bonæ species"). The excellent palæontologist -Quenstedt is right in maintaining that, "if Negroes and Caucasians were -snails, zoologists would universally agree that they represented two -very excellent species, which could never have originated from one pair -by gradual divergence." - -The characteristics by which the races of men are gradually -distinguished are partly taken from the formation of the hair, partly -from the colour of the skin, and partly from the formation of the skull. -In regard to the last character, two extremes are distinguished, namely, -long heads and short heads. In _long-headed men_ (Dolichocephali), whose -strongest development is found in Negroes and Australians, the skull is -extended, narrow, and compressed on the right and left. In _short-headed -men_ (Brachycephali), on the other hand, the skull is compressed in an -exactly opposite manner, from the front to the back, is short and broad, -which is especially striking in the case of the Mongolians. -_Medium-headed men_ (Mesocephali), standing between the two extremes, -predominate especially among Americans. In every one of these three -groups we find men with _slanting teeth_ (Prognathi), whose jaws, like -those of the animal snout, strongly project, and whose front teeth -therefore slope in front, and men with _straight teeth_ (Orthognathi), -whose jaws project but little, and whose front teeth stand -perpendicularly. During the last ten years a great deal of time and -trouble have been devoted to the careful examination and measurement of -the forms of skulls, which have, however, not been rewarded by -corresponding results. For within a single species, as for example -within the Mediterranean species, the form of the skull may vary so much -that both extremes are met with in the same species. Much better -starting-points for the classification of the human species are -furnished by the nature of the hair and speech, because they are much -more strictly hereditary than the form of the skull. - -Comparative philology seems especially to be becoming an authority in -this matter. In the latest great work on the races of men, which -Friederich Müller has published in his excellent "Ethnography,"(42) he -justly places language in the fore-ground. Next to it the nature of the -hair of the head is of great importance; for although it is in itself of -course only a subordinate morphological character, yet it seems to be -strictly transmitted within the race. Of the twelve species of men -distinguished on the following table (p. 308), the four lower species -are characterised by the woolly nature of the hair of their heads; every -hair is flattened like a tape, and thus its section is oval. These four -species of _woolly-haired men_ (Ulotrichi) we may reduce into two -groups--tuft-haired and fleecy-haired. The hair on the head of -_tuft-haired men_ (Lophocomi), Papuans and Hottentots, grows in -unequally divided small tufts. The woolly hair of _fleecy-haired men_ -(Eriocomi), on the other hand, in Caffres and Negroes, grows equally all -over the skin of the head. All Ulotrichi, or woolly-haired men, have -slanting teeth and long heads, and the colour of their skin, hair, and -eyes is always very dark. All are inhabitants of the Southern -Hemisphere; it is only in Africa that they come north of the equator. -They are on the whole at a much lower stage of development, and more -like apes, than most of the Lissotrichi, or straight-haired men. The -Ulotrichi are incapable of a true inner culture and of a higher mental -development, even under the favourable conditions of adaptation now -offered to them in the United States of North America. No woolly-haired -nation has ever had an important "history." - - -SYSTEMATIC SURVEY - -_Of the 12 Species of Men and their 36 Races._ - -(Compare Plate XV.) - - - -------------------+--------------------------+----------------------------+------------- - _Species._ | _Races._ | _Home._ | _Immigrated_ - | | | _from the_ - -------------------+--------------------------+----------------------------+------------- - { 1. =Papuan= { 1. Nigritos Malacca, Philippine West - { +Homo Papua+ { Islands - { { 2. New Guinea men New Guinea West - { 2. =Hottentot= { 3. Melanesians Melanesia North-west - { +Homo+ { 4. Tasmanians Van Diemen's Land North-east - { +Hottentottus+ - { { 5. Hottentots The Cape North-east - { { 6. Bushmen The Cape North-east - - { 3. =Kaffre= { 7. Zulu Kaffres Eastern South Africa North - { +Homo Cafer+ { 8. Beschuanas Central South Africa North-east - { { 9. Congo Kaffres Western South Africa East - { - { 4. =Negro= { 10. Tibu negroes Tibu district South-east - { +Homo Niger+ { 11. Soudan negroes Soudan East - { { 12. Senegambians Senegambia East - { { 13. Nigritians Nigritia East - ....................................................................................... - - { 5. =Australian= { 14. North Australians North Australia North - { +H. Australis+ { 15. South Australians South Australia North - { - { 6. =Malay= { 16. Sundanesians Sunda Archipelago West - { +Homo Malayus+ { 17. Polynesians Pacific Archipelago West - { { 18. Natives of Madagascar Madagascar East - { - { 7. =Mongolian= { 19. Indo-Chinese Tibet, China South - { +Homo+ { 20. Coreo-Japanese Corea, Japan South-west - { +Mongolus+ { 21. Altaians } Central Asia, North Asia South - { { 22. Uralians} North-western Asia, South-east - { { Northern Europe, - { { Hungary - { - { 8. =Arctic Men= { 23. Hyperboreans Extreme N.E. of Asia South-west - { +Homo Arcticus+ { 24. Esquimaux The extreme north of West - { { America - { - { 9. =American= { 25. North Americans North America North-west - { +Homo+ { 26. Central Americans Central America North - { +Americanus+ { 27. South Americans South America North - { { 28. Patagonians The extreme south of North - { { South America - - { 10. =Dravidas= { 29. Deccans Hindostan East? - { +Homo Dravida+ { 30. Singalese Ceylon North? - { - { 11. =Nubian= { 31. Dongolese Nubia East - { +Homo Nuba+ { 32. Fulatians Fulu-land (Central East - { { Africa) - { - { 12. { 33. Caucasians Caucasus South-east - { =Mediterranese= { 34. Basque Extreme north of Spain South? - { +Homo+ { 35. Semites Arabia, North Africa, etc. East - { +Mediterraneus+ { 36. Indo-germanic South-western Asia, South-east - { { tribes Europe, etc. - - ---------------------------------------------------------------- - - Indo-Germanians - 9. =Americans= Semites | - | Magyars | | Caucasians - | Esquimaux | | Basques | | - | | Fins | | | | - | | | \---v---/ \----v----/ - | Hyperboreans | | | - | 8. =Arctic Men= | Samoides | | - | | Tartars | | | | - | | | | | \-------v-------/ - \---v----/ | | | 12. =Mediterranese= - | Calmucks | | | Singalese | - | Tungusians | | | | | | Fulatians - | | | | | | Deccans | | - \--------v---------/ \---v---/ 10. =Dravidas= | Dongolese - =Altaians= =Uralians= | | 11. =Nubians= - | | | | | - | | | | | - Japanese \--------v---------/ \-------v--------/ - | =Ural-Altaians= +Euplocomi+ - | Chinese | | - Coreans | Siamese | Madagascars | - | | Tibet | | Polynesians | | - | | | | | | | | 4. =Negroes= - | | | | | | | | 3. =Kaffres= | - =Coreo-Japanese= \---v----/ | \-----v-----/ | | | - | =Indo-Chinese= | Sundanesians | | | - | | | | | \---v-----/ - | | | | | +Eriocomi+ - | | | | | | - \-----------v-------------/ 6. =Malays= | | - 7. =Mongols= | | | - | | | | - | | | | - \-------v-------------------------------------/ | - =Promalays= 2. =Hottentots= | - | 1. =Papuans= | | - | 5. =Australians= | | | - | | | | | - | | \----v---/ | - \-----v-----/ +Lophocomi+ | - +Euthycomi+ | | - | \---------v---------/ - | =Woolly-haired= - =Straight-haired= +Ulotrichi+ - +Lissotrichi+ | - | | - | | - \--------------v-----------------/ - +Primæval Men+ - - -In the eight higher races of men, which we comprise as _straight-haired_ -(Lissotrichi), the hair of the head is never actually woolly, although -it is very much frizzled in some individuals. Every separate hair is -cylindrical (not like a tape), and hence its section is circular (not -oval). - -The eight races of Lissotrichi may likewise be divided into two -groups--stiff-haired and curly-haired. _Stiff-haired men_ (Euthycomi), -the hair of whose heads is quite smooth and straight, and not frizzled, -include Australians, Malays, Mongolians, Arctic tribes, and Americans. -Curly-haired men, on the other hand, the hair of whose heads is more or -less curly, and in whom the beard is more developed than in all other -species, include the Dravidas, Nubians, and Mediterranean races. -(Compare Plate XV.) - -Now, before we venture upon the attempt hypothetically to explain the -phyletic divergence of mankind, and the genealogical connection of its -different species, we will premise a short description of the twelve -named species and of their distribution. In order clearly to survey -their geographical distribution, we must go back some three or four -centuries, to the time when the Indian Islands and America were first -discovered, and when the present great mingling of species, and more -especially the influx of the Indo-Germanic race, had as yet not made -great progress. We begin with the lowest stages, with the woolly-haired -men (Ulotrichi), all of whom are prognathic Dolichocephali. - -The _Papuan_ (Homo Papua), of all the still living human species, is -perhaps most closely related to the original primary form of -woolly-haired men. This species now inhabits only the large island of -New Guinea and the Archipelago of Melanesia lying to the east of it -(Solomon's Islands, New Caledonia, the New Hebrides, etc.). But -scattered remnants of it are also still found in the interior of the -peninsula of Malacca, and likewise in many other islands of the large -Pacific Archipelago; mostly in the inaccessible mountainous parts of the -interior, and especially in the Philippine Islands. The but lately -extinct Tasmanians, or the natives of Van Diemen's Land, belonged to -this group. From these and other circumstances it is clear that the -Papuans in former times possessed a much larger area of distribution in -south-eastern Asia. They were driven out by the Malays and forced -eastwards. The skin of all Papuans is of a black colour, sometimes more -inclining to brown, sometimes more to blue. Their woolly hair grows in -tufts, is spirally twisted in screws, and often more than a foot in -length, so that it forms a strong woolly wig, which stands far out from -the head. Their face, below the narrow depressed forehead, has a large -turned-up nose and thick protruding lips. The peculiar form of their -hair and speech so essentially distinguishes the Papuans from their -straight-haired neighbours, from the Malays as well as from the -Australians, that they must be regarded as an entirely distinct species. - -Closely related to the Papuans by the tufted growth of hair, but -geographically widely separated from them, are the _Hottentots_ (Homo -Hottentottus). They inhabit exclusively the southernmost part of Africa, -the Cape and the adjacent parts, and have immigrated there from the -north-east. The Hottentots, like their original kinsmen the Papuans, -occupied in former times a much larger area (probably the whole of -Eastern Africa), and are now approaching their extinction. Besides the -genuine Hottentots--of whom there now exist only the two tribes of the -Coraca (in the eastern Cape districts) and the Namaca (in the western -portion of the Cape)--this species also includes the Bushmen (in the -mountainous interior of the Cape). The woolly hair of all Hottentots -grows in tufts, like brushes, as in the case of Papuans. Both species -also agree in the posterior part of the body, in the female sex being -specially inclined to form a great accumulation of fat (Steatopygia). -But the skin of Hottentots is much lighter, of a yellowish brown colour. -Their very flat face is remarkable for its small forehead and nose, and -large nostrils. The mouth is very broad with big lips, the chin small -and pointed. Their speech is characterised by several quite peculiar -guttural sounds. - -The next neighbours and kinsmen of Hottentots are _Kaffres_ (Homo -Cafer). This woolly-haired human species is, however, distinguished, -like the following one (the genuine Negro), from Hottentots and Papuans -by the woolly hair not being divided into tufts, but covering the head -as a thick fleece. The colour of their skin varies through all shades, -from the yellowish black of the Hottentot to the brown black or pure -black of the genuine Negro. While in former times the race of Kaffres -was assigned to a very small area of distribution, and was generally -looked upon only as a variety of the genuine Negro, this species is now -considered to include almost the whole of the inhabitants of equatorial -Africa, from the 20th degree south latitude to the 4th degree north; -consequently, all South Africans, with the exception of the Hottentots. -They include especially the inhabitants of the Zulu, Zambesi, and -Mozambique districts on the east coast, the large human families of the -Beschuans or Setschuans in the interior, and the Herrero and Congo -tribes of the west coast. They too, like the Hottentots, have immigrated -from the north-east. Kaffres, who were usually classed with Negroes, -differ very essentially from them by the formation of their skull and by -their speech. Their face is long and narrow, their forehead high, and -their nose prominent and frequently curved, their lips not so -protruding, and their chin pointed. The many languages of the different -tribes of Kaffres can all be derived from an extinct primæval language, -namely, from the Bantu language. - -The genuine _Negro_ (Homo Niger)--when Kaffres, Hottentots, and Nubians -are separated from him--at present forms a much less comprehensive human -species than was formerly supposed. They now only include the Tibus, in -the eastern parts of the Sahara; the Sudan people, or Sudians, who -inhabit the south of that large desert; also the inhabitants of the -Western Coast of Africa, from the mouth of the Senegal in the north, to -beyond the estuary of the Niger in the south (Senegambians and -Nigritians). Genuine Negroes are accordingly confined between the -equator and the Tropic of Capricorn, and only a small portion of the -Tibu tribe in the east have gone beyond this boundary. The Negro species -has spread within this zone, coming from the east. The colour of the -skin of genuine negroes is always more or less of a pure black. Their -skin is velvety to the touch, and characterised by a peculiar offensive -exhalation. Although Negroes agree with Kaffres in the formation of the -woolly hair of the head, yet they differ essentially in the formation of -their face. Their forehead is flatter and lower, their nose broad and -thick, not prominent, their lips large and protruding, and their chin -very short. Genuine Negroes are moreover distinguished by very thin -calves and very long arms. This species of men must have branched into -many separate tribes at a very early period, for their numerous and -entirely distinct languages can in no way be traced to one primæval -language. - -To the four woolly-haired species of men just discussed, straight-haired -men (Homines Lissotrichi) stand in strong contrast, as another main -branch of the genus. Five of the eight species of the latter, as we have -seen, can be comprised as stiff-haired (Euthycomi) and three as -curly-haired (Euplocomi). We shall in the first place consider the -former, which includes the primæval inhabitants of the greater part of -Asia and the whole of America. - -The lowest stage of all straight-haired men, and on the whole perhaps of -all the still living human species, is occupied by the _Australian_, or -_Austral-negro_ (Homo Australis). This species seems to be exclusively -confined to the large island of Australia; it resembles the genuine -African Negro by its black or brownish black hair, and the offensive -smell of the skin, by its very slanting teeth and long-headed form of -skull, the receding forehead, broad nose, protruding lips, and also by -the entire absence of calves. On the other hand Australians differ from -genuine Negroes as well as from their nearest neighbours the Papuans, by -the much weaker and more delicate structure of their bones, and more -especially by the formation of the hair of their heads, which is not -woolly and frizzled, but either quite lank or only slightly curled. The -very low stage of bodily and mental development of the Australian is -perhaps not altogether original, but has arisen by degeneration, that -is, by adaptation to the very unfavourable conditions of existence in -Australia. They probably immigrated to their present home from the north -or north-west, as a very early offshoot of the Euthycomi. They are -probably more closely related to the Dravidas, and hence to the -Euplocomi, than the other Euthycomi. The very peculiar language of the -Australians is broken up into numerous small branches, which are grouped -into a northern and a southern class. - -The _Malay_ (Homo Malayus), the brown race of ethnographers, although -not a large species, is important in regard to its genealogy. An extinct -south Asiatic human species, very closely related to the Malays of the -present day, must probably be looked upon as the common primary form of -this and the following higher human species. We will call this -hypothetical primary species, Primæval Malays, or Promalays. The Malays -of the present day are divided into two widely dispersed races, the -_Sundanesians_, who inhabit Malacca, the Sunda Islands (Sumatra, Java, -Borneo, etc.) and the Philippine Islands, and the _Polynesians_, who are -dispersed over the greater portion of the Pacific Archipelago. The -northern boundary of their wide tract of distribution is formed on the -east by the Sandwich Islands (Hawai), and on the west by the Marian -Islands (Ladrones); the southern boundary on the east is formed by the -Mangareva Archipelago, and on the west by New Zealand. The inhabitants -of Madagascar are an especial branch of Sundanesians who have been -driven to the far west. This wide pelagic distribution of the Malays is -explained by their partiality for nautical life. Their primæval home is -the south-eastern portion of the Asiatic continent, from whence they -spread to the east and south, and drove the Papuans before them. The -Malays, in the formation of body, are nearest akin to the Mongols, but -are also nearly allied to the curly-haired Mediterranese. They are -generally short-headed, more rarely medium-headed, and very rarely -long-headed. Their hair is black and stiff, but frequently somewhat -curled. The colour of their skin is brown, sometimes yellowish, or of a -cinnamon colour, sometimes reddish or copper brown, more rarely dark -brown. In regard to the formation of face, Malays in a great measure -form an intermediate stage between the Mongols and the Mediterranese; -they can frequently not be distinguished from the latter. Their face is -generally broad, with prominent nose and thick lips, the opening for -their eyes not so narrowly cut and slanting as in Mongols. The near -relationship between all Malays and Polynesians is proved by their -language, which indeed broke up at an early period into many small -branches, but still can always be traced to a common and quite peculiar -primæval language. - -The _Mongol_ (Homo Mongolus) is, next to the Mediterranese, the richest -in individuals. Among them are all the inhabitants of the Asiatic -Continent, excepting the Hyperboreans in the north, the few Malays in -the south-east (Malacca), the Dravidas in Western India, and the -Mediterranese in the south-west. In Europe this species of men is -represented by the Fins and Lapps in the north, by the Osmanlis in -Turkey, and the Magyars in Hungary. The colour of the Mongol is always -distinguished by a yellow tone, sometimes a light pea green, or even -white, sometimes a darker brownish yellow. Their hair is always stiff -and black. The form of their skull is, in the great majority of cases, -decidedly short (especially in Kalmucks, Baschkirs, etc.) but frequently -of medium length (Tartars, Chinese, etc.) But among them we never meet -with genuine long-headed men. The narrow openings of their eyes, which -are generally slanting, their prominent cheek bones, broad noses, and -thick lips are very striking, as well as the round form of their faces. -The language of the Mongols is probably traceable to a common primæval -language; but the monosyllabic languages of the Indo-Chinese races, and -the polysyllabic languages of the other Mongol races, stand in contrast -as two main branches which separated at an early time. The monosyllabic -tribes of the Indo-Chinese include the Tibetans, Birmans, Siamese, and -Chinese. The other polysyllabic Mongols are divided into three races, -namely: (1) the Coreo-Japanese (Coreans and Japanese); (2) the Altaians -(Tartars, Kirgises, Kalmucks, Buriats, Tungusians); and (3) the Uralians -(Samoiedes, Fins). The Magyars of Hungary are descended from the Fins. - -The _Polar men_ (Homo Arcticus) must be looked upon as a branch of the -Mongolian human species. We comprise under this name the inhabitants of -the Arctic Polar lands of both hemispheres, the Esquimaux (and -Greenlanders) in North America, and the Hyperboreans in north-eastern -Asia (Jukagirs, Tschuksches, Kuriaks, and Kamtschads). By adaptation to -the Polar climate, this human race has become so peculiarly transformed -that it may be considered as a distinct species. Their stature is low -and of a square build; the formation of their skull of medium size or -even long; their eyes narrow and slanting like the Mongols; their -cheek-bones prominent, and their mouth wide. Their hair is stiff and -black; the colour of their skin is of a light or dark brown tinge, -sometimes more inclined to white or to yellow, like that of the Mongols, -sometimes more to red, like that of the Americans. The languages of -Polar men are as yet little known, but they differ both from the -Mongolian and from the American. Polar men must probably be regarded as -a remnant and a peculiarly adapted branch of that tribe of Mongols which -emigrated from north-eastern Asia to North America, and populated that -part of the earth. - -At the time of the discovery of America, that part of the earth was -peopled (setting aside the Esquimaux) only by a single human species, -namely, by the _Redskins_, or _Americans_ (Homo Americanus). Of all -other human species they are most closely related to the two preceding. -The form of their skull is generally a medium one, rarely short or -long-headed. Their forehead broad and very low; their nose large, -prominent, and frequently aquiline; their cheek-bones prominent; their -lips rather thin than thick. The colour of their skin is characterised -by a red fundamental tint, which is, however, sometimes pure copper-red, -or light red, sometimes a deeper reddish brown, yellow brown or olive -brown. The numerous languages of the various American races and tribes -are extremely different, yet they agree in their original foundation. -Probably America was first peopled from north-eastern Asia by the same -tribe of Mongols from whom the Polar men (Hyperboreans and Esquimaux) -have also branched. This tribe first spread in North America, and from -thence migrated over the isthmus of Central America down to South -America, at the extreme south of which the species degenerated very -much by adaptation to the very unfavourable conditions of existence. But -it is also possible that Mongols and Polynesians immigrated from the -west and mixed with the former tribe. In any case the aborigines of -America came over from the Old World, and did not, as some suppose, in -any way originate out of American apes. Catarrhini, or Narrow-nosed -Apes, never at any period existed in America. - -The three human species still to be considered--the Dravidas, Nubians, -and Mediterranese--agree in several characteristics which seem to -establish a close relationship between them, and distinguish them from -the preceding species. The chief of these characteristics is the strong -development of the beard, which in all other species is either entirely -wanting or but very scanty. The hair of their heads is generally not so -lank and smooth as in the five preceding species, but in most cases more -or less curly. Other characteristics also seem to favour our classing -them in one main group of curly-haired men (Euplocomi). - -The _Dravida man_ (Homo Dravida) seems to stand very near the common -primary form of the Euplocomi, and perhaps of Lissotrichi. At present -this primæval species is only represented by the Deccan tribes in the -southern part of Hindostan, and by the neighbouring inhabitants of the -mountains on the north-east of Ceylon. But in earlier times this race -seems to have occupied the whole of Hindostan, and to have spread even -further. It shows, on the one hand, traits of relationship to the -Australians and Malays; on the other, to the Mongols and Mediterranese. -Their skin is either of a light or dark brown colour; in some tribes, of -a yellowish brown, in others, almost black brown. The hair of their -heads, as in Mediterranese, is more or less curled, neither quite -smooth, like that of the Euthycomi, nor actually woolly, like that of -the Ulotrichi. The strong development of the beard is also like that of -the Mediterranese. The oval form of face seems partly to be akin to that -of the Malays, partly to that of the Mediterranese. Their forehead is -generally high, their nose prominent and narrow, their lips slightly -protruding. Their language is now very much mixed with Indo-Germanic -elements, but seems to have been originally derived from a very peculiar -primæval language. - -The _Nubian_ (Homo Nuba) has caused ethnographers no fewer difficulties -than the Dravida species. By this name we understand not merely the real -Nubians (Schangallas, or Dongolese), but also their near kinsmen, the -Fulas, or Fellatas. The real Nubians inhabit the countries of the Upper -Nile (Dongola, Schangalla, Barabra, Cordofan); the Fulas, or Fellatas, -on the other hand, have thence migrated far westward, and now inhabit a -broad tract in the south of the western Sahara, hemmed in between the -Soudanians in the north and the Nigritos in the south. The Nubian and -Fula races are generally either classed with negroes or with the Hamitic -races (thus with Mediterranese), but are so essentially different from -both that they must be regarded as a distinct species. In former times -they very probably occupied a large part of north-eastern Africa. The -skin of the Nubian and Fula races is of a yellowish or reddish brown -colour, more rarely dark brown or approaching to black. Their hair is -not woolly but curled, frequently even quite smooth; its colour is dark -brown or black. Their beard is much more strongly developed than in -negroes. The oval formation of their faces approaches more to the -Mediterranean than to the Negro type. Their forehead is high and broad, -their nose prominent and not flat, their lips not so protruding as in -the negro. The language of the Nubian races seems to possess no -relationship to those of genuine negroes. - -The _Caucasian_, or _Mediterranean man_ (Homo Mediterraneus), has from -time immemorial been placed at the head of all races of men, as the most -highly developed and perfect. It is generally called the Caucasian race, -but as among all the varieties of the species, the Caucasian branch is -the least important, we prefer the much more suitable appellation -proposed by Friedrich Müller, namely, that of Mediterranean, or Midland -men. For the most important varieties of this species, which are -moreover the most eminent actors in what is called "Universal History," -first rose to a flourishing condition on the shores of the -Mediterranean. The former area of the distribution of this species is -expressed by the name of "Indo-Atlantic" species, whereas at present it -is spread over the whole earth, and is overcoming most of the other -species in the struggle for existence. In bodily as well as in mental -qualities, no other human species can equal the Mediterranean. This -species alone (with the exception of the Mongolian) has had an actual -history; it alone has attained to that degree of civilization which -seems to raise man above the rest of nature. - -The characteristics which distinguish the Mediterranean from the other -species of the race are well known. The chief of the external features -is the light colour of the skin, which however exhibits all shades, from -pure white or reddish white, through yellow or yellowish brown to dark -brown or even black brown. The growth of the hair is generally strong, -the hair of the head more or less curly, the hair of the beard stronger -than in any of the other species. The form of the skull shows a great -development in breadth; medium heads predominate upon the whole, but -long and short heads are also widely distributed. It is only in this one -species of men that the body as a whole attains that symmetry in all -parts, and that equal development, which we call the type of perfect -human beauty. The languages of all the races of this species can by no -means be traced to a single common primæval language; we must at least -assume four radically different primæval languages. In accordance with -this we must also assume within this one species four different races, -which are only connected at their root. Two of these races, the Basques -and Caucasians, now exist only as small remnants. The Basques, which in -earlier times peopled the whole of Spain and the south of France, now -inhabit but a narrow tract of land on the northern coast of Spain, on -the Bay of Biscay. The remnant of the Caucasian race (the Daghestans, -Tschercassians, Mingrelians, and Georgians) are now confined to the -districts of Mount Caucasus. The language of the Caucasians as well as -that of the Basques is entirely peculiar, and can be traced neither to -the Semitic nor to the Indo-Germanic primæval languages. - -Even the languages of the two principal races of the Mediterranean -species--the Semitic and Indo-Germanic--cannot be traced to a common -origin, and consequently these two races must have separated at a very -early period. Semites and Indo-Germani are descended from different -ape-like men. The _Semitic_ race likewise separated at a very early -period into two diverging branches, namely, into the _Egyptian_ and -_Arabic_ branches. The _Egyptian_, or _African_ branch, the -_Dyssemites_--which sometimes under the name of Hamites are entirely -separated from the Semites--embraces the large group of Berbers, who -occupy the whole of north Africa, and in earlier times also peopled the -Canary Islands, and, finally, also the group of the Ethiopians, the -Bedsha, Galla, Danakil, Somali, and other tribes which occupy all the -north-eastern shores of Africa as far as the equator. The _Arabic_, or -_Asiatic_ branch, that is, the _Eusemites_, also called Semites in a -narrow sense, embrace the inhabitants of the large Arabian peninsula, -the primæval family of genuine Arabians ("primæval type of the -Semites"), and also the most highly developed Semitic groups, the Jews, -or Hebrews, and the Aramæans--the Syrians and Chaldæans. A colony of the -southern Arabs (the Himjarites), which crossed the Straits of -Bab-el-Mandeb, has peopled Abyssinia. - -Lastly, the Indo-Germanic race, which has far surpassed all the other -races of men in mental development, separated at a very early period, -like the Semitic, into two diverging branches, the _Ario-Romaic_ and the -_Slavo-Germanic_ branches. Out of the former arose on the one hand the -_Arians_ (Indians and Iranians), on the other the _Græco-Roman_ (Greeks -and Albanians, Italians and Kelts). Out of the Slavo-Germanic branch -were developed on the one hand the _Slavonians_ (Russian, Bulgarian, -Tchec, and Baltic tribes), on the other the _Germani_ (Scandinavians and -Germans, Netherlanders and Anglo-Saxons). August Schleicher has -explained, in a very clear genealogical form, how the further -ramifications of the Indo-Germanic race may be accurately traced in -detail on the basis of comparative philology.(6) (Compare p. 331.) - -The total number of human individuals at present amounts to between -1,300 and 1,400 millions. In our Tabular Survey (p. 333) 1,350 millions -has been assumed as the mean number. According to an approximate -estimate, as far as such a thing is possible, 1,200 millions of these -are straight-haired men, only about 150 millions woolly-haired. The most -highly developed species, Mongols and Mediterranese, far surpass all the -other human species in numbers of individuals, for each of them alone -comprises about 550 millions. (Compare Friederich Müller's Ethnography, -p. 30.) Of course the relative number of the twelve species fluctuates -every year, and that too according to the law developed by Darwin, that -in the struggle for life the more highly developed, the more favoured -and larger groups of forms, possess the positive inclination and the -certain tendency to spread more and more at the expense of the lower, -more backward, and smaller groups. Thus the Mediterranean species, and -within it the Indo-Germanic, have by means of the higher development of -their brain surpassed all the other races and species in the struggle -for life, and have already spread the net of their dominion over the -whole globe. It is only the Mongolian species which can at all -successfully, at least in certain respects, compete with the -Mediterranean. Within the tropical regions, Negroes, Kaffres, and -Nubians, as also the Malays and Dravidas, are in some measure protected -against the encroachments of the Indo-Germanic tribes by their being -better adapted for a hot climate; the case of the arctic tribes of the -polar regions is similar. But the other races, which as it is are very -much diminished in number, will sooner or later completely succumb in -the struggle for existence to the superiority of the Mediterranean -races. The American and Australian tribes are even now fast approaching -their complete extinction, and the same may be said of the Papuans and -Hottentots. - -In now turning to the equally interesting and difficult question of the -relative _connection_, _migration_, and _primæval home_ of the twelve -species of men, I must premise the remark that, in the present state of -our anthropological knowledge, any answer to this question must be -regarded only as a provisional hypothesis. This is much the same as with -any genealogical hypothesis which we may form of the origin of kindred -animal and vegetable species, on the basis of the "Natural System." But -the necessary uncertainty of these special hypotheses of descent, in no -way shakes the absolute certainty of the general theory of descent. Man, -we may feel certain, is descended from Catarrhini, or narrow-nosed apes, -whether we agree with the polyphylites, and suppose each human species, -in its primæval home, to have originated out of a special kind of ape; -or whether, agreeing with the monophylites, we suppose that all the -human species arose only by differentiation from a single species of -primæval man (Homo primigenius). - -For many and weighty reasons we hold the monophyletic hypothesis to be -the more correct, and we therefore assume a _single primæval home_ for -mankind, where he developed out of a long since extinct anthropoid -species of ape. Of the five now existing continents, neither Australia, -nor America, nor Europe can have been this primæval home, or the -so-called "Paradise," the "cradle of the human race." Most -circumstances indicate southern Asia as the locality in question. -Besides southern Asia, the only other of the now existing continents -which might be viewed in this light is Africa. But there are a number of -circumstances (especially chorological facts) which suggest that the -primæval home of man was a continent now sunk below the surface of the -Indian Ocean, which extended along the south of Asia, as it is at -present (and probably in direct connection with it), towards the east, -as far as further India and the Sunda Islands; towards the west, as far -as Madagascar and the south-eastern shores of Africa. We have already -mentioned that many facts in animal and vegetable geography render the -former existence of such a south Indian continent very probable. -(Compare vol. i. p. 361.) Sclater has given this continent the name of -Lemuria, from the Semi-apes which were characteristic of it. By assuming -this Lemuria to have been man's primæval home, we greatly facilitate the -explanation of the geographical distribution of the human species by -migration. (Compare the Table of Migrations XV., and its explanation at -the end.) - -We as yet know of no fossil remains of the hypothetical primæval man -(Homo primigenius) who developed out of anthropoid apes during the -tertiary period, either in Lemuria or in southern Asia, or possibly in -Africa. But considering the extraordinary resemblance between the lowest -woolly-haired men, and the highest man-like apes, which still exist at -the present day, it requires but a slight stretch of the imagination to -conceive an intermediate form connecting the two, and to see in it an -approximate likeness to the supposed primæval men, or ape-like men. The -form of their skull was probably very long, with slanting teeth; their -hair woolly; the colour of their skin dark, of a brownish tint. The hair -covering the whole body was probably thicker than in any of the still -living human species; their arms comparatively longer and stronger; -their legs, on the other hand, knock-kneed, shorter and thinner, with -entirely undeveloped calves; their walk but half erect. - -This ape-like man very probably did not as yet possess an actual human -language, that is, an articulate language of ideas. Human speech, as has -already been remarked, most likely originated after the divergence of -the primæval species of men into different species. The number of -primæval languages is, however, considerably larger than the number of -the species of men above discussed. For philologists have hitherto not -been able to trace the four primæval languages of the Mediterranean -species, namely, the Basque, Caucasian, Semitic, and Indo-Germanic to a -single primæval language. As little can the different Negro languages be -derived from a common primæval language; hence both these species, -Mediterranean and Negro, are certainly _polyglottonic_, that is, their -respective languages originated after the divergence of the speechless -primary species into several races had already taken place. Perhaps the -Mongols, the Arctic and American tribes, are likewise polyglottonic. The -Malayan species is, however, _monoglottonic_; all the Polynesian and -Sundanesian dialects and languages can be derived from a common, long -since extinct primæval language, which is not related to any other -language on earth. All the other human species, Nubians, Dravidas, -Australians, Papuans, Hottentots, and Kaffres are likewise -monoglottonic. (Compare p. 333.) - -Out of speechless primæval man, whom we consider as the common primary -species of all the others, there developed in the first place--probably -by natural selection--various species of men unknown to us, and now long -since extinct, and who still remained at the stage of speechless ape-men -(Alalus, or Pithecanthropus). Two of these species, a woolly-haired and -a straight-haired, which were most strongly divergent, and consequently -overpowered the others in the struggle for life, became the primary -forms of the other remaining human species. - -The main branch of woolly-haired men (Ulotrichi) at first spread only -over the southern hemisphere, and then emigrated partly eastwards, -partly westwards. Remnants of the eastern branch are the Papuans in New -Guinea and Melanesia, who in earlier times were diffused much further -west (in further India and Sundanesia), and it was not until a late -period that they were driven eastwards by the Malays. The Hottentots are -the but little changed remnants of the western branch; they immigrated -to their present home from the north-east. It was perhaps during this -migration that the two nearly related species of Caffres and Negroes -branched off from them; but it may be that they owe their origin to a -peculiar branch of ape-like men. - -The second main branch of primæval straight-haired men (Lissotrichi), -which is more capable of development, has probably left a but little -changed remnant of its common primary form--which migrated to the -south-east--in the ape-like natives of Australia. Probably very closely -related to these latter are the South Asiatic _primæval Malays_, or -_Promalays_, which name we have previously given to the extinct, -hypothetical primary form of the other six human species. Out of this -unknown common primary form there seem to have arisen three diverging -branches, namely, the true Malays, the Mongols, and the Euplocomi; the -first spread to the east, the second to the north, and the third -westwards. - -The primæval home, or the "Centre of Creation," of the Malays must be -looked for in the south-eastern part of the Asiatic continent, or -possibly in the more extensive continent which existed at the time when -further India was directly connected with the Sunda Archipelago and -eastern Lemuria. From thence the Malays spread towards the south-east, -over the Sunda Archipelago as far as Borneo, then wandered, driving the -Papuans before them, eastwards towards the Samoa and Tonga Islands, and -thence gradually diffused over the whole of the islands of the southern -Pacific, to the Sandwich Islands in the north, the Mangareva in the -east, and New Zealand in the south. A single branch of the Malayan tribe -was driven far westwards and peopled Madagascar. - -The second main branch of primæval Malays, that is, the Mongols, at -first also spread in Southern Asia, and, radiating to the east, north, -and north-west, gradually peopled the greater part of the Asiatic -continent. Of the four principal races of the Mongol species, the -Indo-Chinese must perhaps be looked upon as the primary group, out of -which at a later period the other Coreo-Japanese and Ural-Altaian races -developed as diverging branches. The Mongols migrated in many ways from -western Asia into Europe, where the species is still represented in -northern Russia and Scandinavia by the Fins and Lapps, in Hungary by the -kindred Magyars, and in Turkey by the Osmanlis. - - PEDIGREE OF SEMITES - - Amharites +Moors+ +Jews+ - | Tigrites | Samaritans (Hebrews) - | Harrarites | | | Phoenicians | - | | | | | | | - | | | | Chaldeans | | - \-------v------/ | Syrians | \----v-----/ - +Abyssinians+ | | | Canaanites - Ekilians | | | | (+Palestinese+) - | | | \---v---/ | - | Himiarites | +Aramæans+ | - | | | | | - | | | | | - \---v---/ | | | - +South+ +North+ \----------v------------/ - +Arabians+ +Arabians+ +Primæval Jews+ - | | +North-Semites+ - \-------v-----------/ | - +Arabians+ (+South Semites+) | - | | - | | - \----------------------------------------v-----/ - Guanchites +Eusemites+ (+Primæval Semites+) - Schuluhs | Algerians (Semites in a narrow sense) - | | Tunese | \------------------------v---/ - | | | | | - | | | | Tripolitans | - \---v---/ | | | | - Moroccans \----v----/ | +Tuaric+ | - | Cabyles | (+Imoscharh+) | - | | | | | - \--------------v--------------/ | | - +Berbers+ (+Amazirh+) | | - Gallites | | | - | Somalites | | | - | | \------------v-------------/ | - \---v---/ Bedschites +Libians+ Babylonians +Eusemites+ - | | Egyptians | Primæval | | - | | (+Copts+) | Phoenicians | Assyrians | - \----v-----/ | | | | | | - +Ethiopians+ | | | | | | - | | | | | | | - | | | | | | | - \------------v----------/ \-------v------/ | - +Ancient Egyptians+ +Mesopotamians+ | - | (extinct) | - | | | - | | | - \------------v-----------------/ | - +Hamites+ (+Dyssemites+) | - | | - \---------------v--------------/ - +Semites+ - - ---------------------------------------------------------------- - -PEDIGREE OF THE INDO-GERMANI - - Ancient Prussians +Anglo-Saxons+ +High Germans+ - Lithuanians | | Low Germans | - | Letts | | | Netherlanders | - | | | | | | | - | | | | | | | - \-----v----/ | | \----v---/ | - | | | Ancient Saxons | - | | | | | - \-------v-/ | | | - +Baltic Races+ \------v----/ | - Sorbians, or | Saxons Friesians | - Wends | | | | - Poles | | | | | - | | | \----v----/ | - Czecs | | | +Low Germans+ | - | | | | | | - | | | | | | - \--v-----------/ | Scandinavians \-----v------/ - West Sclavonians | | Goths +Germans+ - | Russians | | | | - | South | | | | | - | Sclavonians| | \----v----------------------/ - | | | | +Primæval Germans+ Ancient Britons - | | | | | | - | \---v---/ | | Ancient Scots | Gauls - | South-eastern | | +Romans+ Irish | | | - | Sclavonians | | | | | | | - | | | | | | | \--v-/ - | | | | | \--v-/ Brittanese - | | | | | +Latins+ Gaels | - \----v----/ | | | | | | - +Sclavonians+ | | | | | | - | | | \--v--/ \----v-----/ - | | | Italians +Kelts+ - \------v------/ | | | - +Sclavo-Letts+ | | | - | | \--------v---------/ - | | +Italo-Kelts+ - \--v-----------------/ | - +Sclavo-Germans+ +Albanese+ +Greeks+ | - | | | | - | | | | - | \----v-----/ | - | +Primæval Thracians+ | - | +Indians+ | | - | | +Iranians+ \-------v-------/ - | | | +Græco-Romans+ - | \---v--/ | - | +Arians+ | - | | | - | \-----v----------/ - | +Ario-Romans+ - | | - \-------v-------/ - +Indo-Germans+ - - -On the other hand, a branch of the Mongols migrated from north-eastern -Asia to America, which was probably in earlier times connected with the -former continent by a broad isthmus. The Arctic tribes, or Polar men, -the Hyperboreans of north-eastern Asia, and the Esquimaux of the -extreme north of America, must probably be regarded as an offshoot of -this branch, which became peculiarly degenerated by unfavourable -conditions of existence. The principal portion of the Mongolian -immigrants, however, migrated to the south, and gradually spread over -the whole of America, first over the north, later over South America. - -The third and most important main branch of primæval Malays, the -curly-haired races, or Euplocomi, have probably left in the Dravidas of -Hindostan and Ceylon, that species of man which differs least from the -common primary form of the Euplocomi. The principal portion of the -latter, namely, the Mediterranean species, migrated from their primæval -home (Hindostan?) westwards, and peopled the shores of the -Mediterranean, south-western Asia, north Africa, and Europe. The -Nubians, in the north-east of Africa, must perhaps be regarded as an -offshoot of the primæval Semitic tribes, who migrated far across central -Africa almost to the western shores. The various branches of the -Indo-Germanic race have deviated furthest from the common primary form -of ape-like men. During classic antiquity and the middle ages, the -Romanic branch (the Græco-Italo-Keltic group), one of the two main -branches of the Indo-Germanic species, outstripped all other branches in -the career of civilization, but at present the same position is occupied -by the Germanic. Its chief representatives are the English and Germans, -who are in the present age laying the foundation for a new period of -higher mental development, in the recognition and completion of the -theory of descent. The recognition of the theory of development and the -monistic philosophy based upon it, forms the best criterion for the -degree of man's mental development. - - -SYSTEMATIC SURVEY OF THE TWELVE HUMAN SPECIES. - - N.B.--Column A denotes the Average Number of the Population in - millions. Column B shows the Degree of the Phyletic Development of - the Species, thus Pr = Progressive Diffusion; Co = Comparative - Stability; Re = Retrogression and Extinction. Column C denotes the - Character of the Primæval Language; Mn (Monoglottonic) signifies that - the Species had one Simple Primæval Language; Pl (Polyglottonic) a - Compound Primæval Language. - - - ----------------------+--------------------+--------+-------+--------+----------------------------- - _Tribe._ | _Human | A. | B. | C. | _Home._ - | Species._ | | | | - ----------------------+--------------------+--------+-------+--------+----------------------------- - - TUFT-HAIRED { | | | - +Lophocomi+ { 1. PAPUAN | 2 | Re | Mn { New Guinea and Melanesia, - { | | | { Philippine Islands, Malacca - (about 2 millions) { 2. HOTTENTOT | 1/20 | Re | Mn { The extreme south of Africa - { | | | { (The Cape) - | | | - FLEECY-HAIRED { 3. KAFFRE | 20 | Pr | Mn { South Africa (between 30° - { | | | { S. Lat. and 5° N. Lat.) - +Eriocomi+ { 4. NEGRO | 130 | Pr | Pl { Central Africa (between the - { | | | { Equator and 30° N. Lat.) - (about 150 millions) { | | | - | | | - { 5. AUSTRALIAN | 1/12 | Re | Mn { Australia - { 6. MALAY | 30 | Co | Mn { Malacca, Sundanesia, Polynesia, - { | | | { and Madagascar - STRAIGHT-HAIRED { | | | - +Euthycomi+ { 7. MONGOL | 550 | Pr | Mn? { The greater part of Asia - { | | | { and northern Europe - (about 600 millions) { 8. ARCTIC | 1/25 | Co | Pl? { The extreme north-east of - { MAN | | | { Asia and the extreme north - { | | | { of America - { 9. AMERICAN | 12 | Re | Mn? { The whole of America with - { | | | { the exception of the extreme - { | | | { north - | | | - { 10. DRAVIDAS | 34 | Co | Mn { South Asia (Hindostan and - { | | | { Ceylon) - { | | | - { 11. NUBIAN | 10 | Co | Mn? { Central Africa (Nubia and - { | | | { Fula-land) - CURLY-HAIRED { | | | { In all parts of the world, - { | | | { having migrated from South - +Euplocomi+ { 12. MEDITERRANEAN | 550 | Pr | Pl { Asia to North Africa and - { | | | { South Europe - (about 600 millions) { | | | - { | | | - | | | { In all parts of the world, - 13. HYBRIDS | 11 | Pr | Pl { but predominating in America - OF THE | | | { and Asia - SPECIES | | | - --------------------+--------+ | - TOTAL 1350 - - - - -CHAPTER XXIV. - -OBJECTIONS AGAINST, AND PROOFS OF THE TRUTH OF, THE THEORY OF DESCENT. - - - Objections to the Doctrine of Filiation.--Objections of Faith - and Reason.--Immeasurable Length of the Geological - Periods.--Transition Forms between Kindred Species.--Dependence - of Stability of Form on Inheritance, and of the Variability of - Form on Adaptation.--Origin of very complicated Arrangement of - Organisation.--Gradual Development of Instincts and Mental - Activities.--Origin of a priori Knowledge from Knowledge a - posteriori.--The Knowledge requisite for the Correct - Understanding of the Doctrine of Filiation.--Necessary - Interaction between Empiricism and Philosophy.--Proofs of the - Theory of Descent.--Inner Causal Connection between all the - Biological Series of Phenomena.--The Direct Proof of the Theory - of Selection.--Relation of the Theory of Descent to - Anthropology.--Proofs of the Animal Origin of Man.--The Pithecoid - Theory as an Inseparable Part of the Theory of - Descent.--Induction and Deduction.--Gradual Development of the - Human Mind.--Body and Mind.--Human Soul and Animal Soul.--A Glance - at the Future. - - -If in these chapters I may hope to have made the Theory of Descent seem -more or less probable, and to have even convinced some of my readers of -its unassailable truth, yet I am by no means unconscious that, to most -of them, during the perusal of my explanations, a number of objections -more or less well founded must have occurred. Hence it seems absolutely -necessary at the conclusion of our examination to refute at least the -most important of these, and at the same time, on the other hand, once -more to set forth the convincing arguments which bear testimony to the -truth of the theory of development. - -The objections which are raised to the doctrine of descent may be -divided into two large groups: objections of faith and objections of -reason. The objections of the first group originate in the infinitely -varied forms of faith held by human individuals, and need not here be -taken into consideration at all. For, as I have already remarked at the -beginning of this book, science, as an objective result of sensuous -experience, and of the striving of human reason after knowledge, has -nothing whatever to do with the subjective ideas of faith, which are -preached by a single man as the direct inspirations or revelations of -the Creator, and then believed in by the dependent multitude. This -belief, very different in different nations, only begins, as is well -known, where science ends. Natural Science believes, according to the -maxim of Frederick the Great, "that every one may go to heaven in his -own fashion," and only necessarily enters into conflict with particular -forms of faith where they appear to set a limit to free inquiry and a -goal to human knowledge, beyond which we are not to venture. Now this is -certainly the case here in the highest degree, for the Theory of -Development applies itself to the solution of the greatest of scientific -problems--that of the creation, the coming into existence of things; -more especially the origin of organic forms, and of man at their head. -It is here certainly the right as well as the sacred duty of free -inquiry, to fear no human authority, and courageously to raise the veil -from the image of the Creator, unconcerned as to what natural truth may -lie concealed beneath. The only Divine revelation which we recognise as -true, is written everywhere in nature, and to every one with healthy -senses and a healthy reason it is given to participate in the unerring -revelation of this holy temple of nature, by his own inquiry and -independent discovery. - -If we, therefore, here disregard all objections to the Doctrine of -Descent which may be raised by the priests of the different religious -faiths, we must nevertheless endeavour to refute the most important of -those objections which seem more or less founded on science, and which -we grant might, at first sight, to a certain extent captivate us and -deter us from adopting the Doctrine of Descent. Many persons seem to -think the length of the periods of time required the most important of -these objections. We are not accustomed to deal with such immense -periods as are necessary for the history of the creation. It has already -been mentioned that the periods, during which species originated by -gradual transmutation, must not be calculated by single centuries, but -by hundreds and by millions of centuries. Even the thickness of the -stratified crust of the earth, the consideration of the immense space of -time which was requisite for its deposition from water, taken together -with the periods of elevation between the periods of depression, -indicate a duration of time of the organic history of the earth which -the human intellect cannot realize. We are here in much the same -position as an astronomer in regard to infinite space. In the same way -as the distances between the different planetary systems are not -calculated by miles but by Sirius-distances, each of which comprises -millions of miles, so the organic history of the earth must not be -calculated by thousands of years, but by palæontological or geological -periods, each of which comprises many thousands of years, and perhaps -millions, or even, milliards, of thousands of years. It is of little -importance how high the immeasurable length of these periods may be -approximately estimated, because we are in fact unable with our limited -power of imagination to form a true conception of these periods, and -because we do not as in astronomy possess a secure mathematical basis -for fixing the approximate length of duration in numbers. But we most -positively deny that we see any objection to the theory of development -in the extreme length of these periods which are so completely beyond -the power of our imagination. It is, on the contrary, as I have already -explained in one of the preceding chapters, most advisable, from a -strictly philosophical point of view, to conceive these periods of -creation to be as long as possible, and we are by so much the less in -danger of losing ourselves in improbable hypotheses, the longer we -conceive the periods for organic processes of development to have been. -The longer, for example, we conceive the Permian period to have been, -the easier it will be for us to understand how the important -transmutations took place within it which so essentially distinguish the -fauna and flora of the Coal period from that of the Trias. The great -disinclination which most persons have to assume such immeasurable -periods, arises mainly from the fact of our having in early youth been -brought up in the notion that the whole earth is only some thousands of -years old. Moreover, human life, which at most attains the length of a -century, is an extremely short space of time, and is not suitable as a -standard for the measurement of geological periods. Our life is a -single drop in the ocean of eternity. The reader may call to mind the -duration of life of many trees which is more than fifty times as long; -for example, the dragon-trees (Dracæna) and monkey bread-fruit trees -(Adansonia), whose individual life exceeds a period of five thousand -years; and, on the other hand, the shortness of the individual life of -many of the lower animals, for example, the infusoria, where the -individual, as such, lives but a few days, or even but a few hours, -contrasts no less strongly with human longevity. This comparison brings -the relative nature of all measurement of time very clearly before us. -If the theory of development be true at all, there must certainly have -elapsed immense periods, utterly inconceivable to us, during which the -gradual historical development of the animal and vegetable kingdom -proceeded by the slow transformation of species. There is, however, not -a single reason for accepting a definite limit for the length of these -periods of development. - -A second main objection which many, and more especially systematic -zoologists and botanists, raise against the theory of descent, is that -no _transition forms_ between the different species can be found, -although according to the theory of descent they ought to be found in -great numbers. This objection is partly well founded and partly not so, -for there does exist an extraordinarily large number of transition forms -between living, as well as between extinct species, especially where we -have an opportunity of seeing and comparing very numerous individuals of -kindred species. Those careful investigators of individual species who -so frequently raise this objection are the very persons whom we -constantly find checked in their special series of investigations by the -really insuperable difficulty of sharply distinguishing individual -species. In all systematic works, which are in any degree thorough, one -meets with endless complaints, that here and there species cannot be -distinguished because of the excessive number of transition forms. Hence -every naturalist defines the limit and the number of individual species -differently. Some zoologists and botanists, as I mentioned (vol. i. p. -276), assume in one and the same group of organisms ten species, others -twenty, others a hundred or more, while other systematic naturalists -again look upon these different forms only as varieties of a single -"good" species. In most groups of forms there is, in fact, a -superabundance of transition forms and intermediate stages between the -individual species. - -It is true that in many species the forms of transition are actually -wanting, but this is easily explained by the principle of divergence or -separation, the importance of which I have already explained. The -circumstance that the struggle for existence is the more active between -two kindred forms the closer they stand to each other, must necessarily -favour the speedy extinction of the connecting intermediate forms -between the two divergent species. If one and the same species produce -diverging varieties in different directions, which become new species, -the struggle between these new forms and the common primary form will be -the keener the less they differ from one another; but the stronger the -divergence the less dangerous the struggle. Naturally therefore, it is -principally the connecting intermediate forms which will in most cases -quietly die out, while the most divergent forms remain and reproduce -themselves as distinct "new species." In accordance with this, we in -fact no longer find forms of transition leading to those groups which -are becoming extinct, as, for example, among birds, are the ostriches; -and among mammals, the elephants, giraffes, Semi-apes, Edentata, and -Ornithorhyncus. The groups of forms approaching their extinction no -longer produce new varieties, and naturally the species are what is -called "good," that is, the species are distinctly different from one -another. But in those animal groups where development and progress are -still active, where the existing species deviate into many new species -by the formation of new varieties, we find an abundance of transition -forms which cause the greatest difficulties to systematic naturalists. -This is the case, for example, among birds with the finches; among -mammals with most of the rodents (more especially with those of the -mouse and rat kind), with a number of the ruminants and with genuine -apes, more especially with the South American forms (Cebus), and many -others. The continual development of species by the formation of new -varieties here produces a mass of intermediate forms which connect the -so-called "good" species, which efface their boundaries, and render -their sharp specific distinction completely illusory. - -The reason that this nevertheless does not cause a complete confusion of -forms, nor a universal chaos in the structure of animals and vegetables, -lies simply in the fact that there is a continual counteraction at work -between progressive _adaptation_ on the one hand, and the _retentive_ -power of _inheritance_ on the other hand. The degree of stability and -variability manifested by every organic form is determined solely by the -actual condition of the equilibrium between these two opposite -functions. _Inheritance is the cause of the stability of species, -adaptation the cause of their modification._ When therefore some -naturalists say that, according to the theory of descent, there ought to -be a much greater variety of forms, and others again, that there ought -to be a much greater equality of forms, the former under-estimate the -value of inheritance and the latter the value of adaptation. _The ratio -of the interaction between inheritance and adaptation determines the -ratio of the stability and variability of organic species_ at any given -period. - -Another objection to the theory of descent, which, in the opinion of -many naturalists and philosophers is of great weight, is that it -ascribes the origin of organs which act for a definite purpose to causes -which are either aimless or mechanical in their operation. This -objection seems to be especially important in regard to those organs -which appear so excellently adapted for a certain definite purpose that -the most ingenious mechanician could not invent a more perfect organ for -the purpose. Such are, above all, the higher sense-organs of animals, -the eye and ear. If the eyes and auditory apparatus of the higher -animals alone were known to us, they would indeed cause great and -perhaps insurmountable difficulties. How could we come to the conclusion -that the extraordinarily great and wonderful degree of perfection and -conformity to purpose which we perceive in the eyes and ears of higher -animals, is in every respect attained solely by natural selection? -Fortunately, however, comparative anatomy and the history of -development help us here over all obstacles; for when in the animal -kingdom we follow the gradual progress towards perfection of the eyes -and ears, step by step, we find such a finely graduated series of -improvement, that we can clearly follow the development of the most -complex organs through all the stages towards perfection. Thus, for -example, the eye in the lowest animal is a simple spot of pigment which -does not yet reflect any image of external objects, but at most -perceives and distinguishes the different rays of light. Later, we find -in addition to this a sensitive nerve; then there gradually develops -within the spot of pigment the first beginning of the lens, a refractive -body which is now able to concentrate the rays of light and to reflect a -definite image. But all the composite apparatus for the movement of the -eye and its accommodation to variations of light and distance are still -absent, namely, the various refractive media, the highly differentiated -membrane of the optic nerve, etc., which are so perfectly constructed in -higher animals. Comparative anatomy shows us an uninterrupted succession -of all possible stages of transition, from the simplest organ to the -most highly perfected apparatus, so that we can form a pretty correct -idea of the slow and gradual formation of even such an exceedingly -complex organ. The like gradual progress which we observe in the -development of the organ during the course of individual development, -must have taken place in the historical (phyletic) origin of the organ. - -Many persons when contemplating these most perfect organs--which -apparently were purposely invented and constructed by an ingenious -Creator for a definite function, but which in reality have arisen by the -aimless action of natural selection--experience difficulties in arriving -at a rational understanding of them, which are similar to those -experienced by the uncivilized tribes of nature when contemplating the -latest complicated productions of engineering. Savages who see a ship of -the line, or a locomotive engine for the first time, look upon these -objects as the productions of a supernatural being, and cannot -understand how a man, an organism like themselves, could have produced -such an engine. Even the uneducated classes of our own race cannot -comprehend such an intricate apparatus in its actual workings, nor can -they understand its purely mechanical nature. Most naturalists, however, -as Darwin very justly remarks, stand in much the same position in regard -to the forms of organisms as do savages to ships of the line and to -locomotive engines. A rational understanding of the purely mechanical -origin of organic forms can only be acquired by a thorough and general -training in Biology, and by a special knowledge of comparative anatomy -and the history of development. - -Among the remaining objections to the Theory of Descent, I shall here -finally refer to and refute but one more, as in the eyes of many -unscientific men it seems to possess great weight. How are we, from the -Theory of Descent, to conceive of the origin of the mental faculties of -animals, and more especially their specific expressions--the so-called -instincts? This difficult subject has been so minutely discussed by -Darwin in a special chapter of his chief work (the seventh), that I must -refer the reader to it. We must regard instincts as essentially the -habits of the soul acquired by adaptation, and transmitted and fixed by -inheritance through many generations. Instincts are, therefore, like all -other habits, which, according to the laws of cumulative adaptation -(vol. i. p. 233) and established inheritance (vol. i. p. 216), lead to -the origin of new functions, and thus also to new forms of the organs. -Here, as everywhere, the interaction between function and organ goes -hand in hand. Just as the mental faculties of man have been acquired by -the progressive adaptation of the brain, and been fixed by continual -transmission by inheritance, so the instincts of animals, which differ -from them only in quantity, not in quality, have arisen by the gradual -perfecting of their mental organ, that is, their central nervous system, -by the interaction of Adaptation and Inheritance. Instincts, as is well -known, are inherited, but experiences and, consequently, new adaptations -of the animal mind, are also transmitted by inheritance; and the -training of domestic animals to different mental activities, which wild -animals are incapable of accomplishing, rests upon the possibility of -mental adaptation. We already know a series of examples, in which such -adaptations, after they had been transmitted through a succession of -generations, finally appeared as innate instincts, and yet they have -only been acquired from the ancestors of the animals. Inheritance has -here caused the result of training to become instinct. The -characteristic instincts of sporting dogs, shepherd's dogs, and other -domestic animals, and the natural instincts of wild animals, which they -possess at birth, were in the first place acquired by their ancestors by -adaptation. They may in this respect be compared to man's "knowledge a -priori," which, like all other knowledge, was originally acquired by our -remote ancestors, "a posteriori," by sensuous experience. As I have -already remarked, it is evident that "knowledge a priori" arose only by -long-enduring transmission, by inheritance of acquired adaptations of -the brain, out of originally empiric or experiential "knowledge a -posteriori" (vol. i. p. 31). - -The objections to the Theory of Descent here discussed and refuted are, -I believe, the most important which have been raised against it; I -consider also that I have sufficiently proved to the reader their -futility. The numerous other objections which besides these have been -raised against the Theory of Development in general, or against its -biological part, the Theory of Descent in particular, arise either from -such a degree of ignorance of empirically established facts, or from -such a want of their right understanding, and from such an incapacity to -draw the necessary conclusions, that it is really not worth the trouble -to go further into the refutation. There are only some general points in -regard to which, I should like, in a few words, to draw attention. - -In the first place I must observe, that in order thoroughly to -understand the doctrine of descent, and to be convinced of its absolute -truth, it is indispensable to possess a general knowledge of the whole -of the domain of biological phenomena. _The theory of descent is a -biological theory_, and hence it may with fairness and justice be -demanded that those persons who wish to pass a valid judgment upon it -should possess the requisite degree of biological knowledge. Their -possessing a special empiric knowledge of this or that domain of zoology -or botany, is not sufficient; they must possess a _general insight into -the whole series of phenomena_, at least in the case of one of the three -organic kingdoms. They ought to know what universal laws result from the -comparative morphology and physiology of organisms, but more especially -from comparative anatomy, from the individual and the palæontological -history of development, etc.; and they ought to have some idea of the -deep _mechanical, causal connection_ between all these series of -phenomena. It is self-evident that a certain degree of general culture, -and especially a philosophical education, is requisite; which is, -however, unfortunately by many persons in our day, not considered at all -necessary. _Without the necessary connection of empirical knowledge and -the philosophical understanding of biological phenomena, it is -impossible to gain a thorough conviction of the truth of the Theory of -Descent._ - -Now I ask, in the face of this first preliminary condition for a true -understanding of the Theory of Descent, what we are to think of the -confused mass of persons who have presumed to pass a written or oral -judgment upon it of an adverse character? Most of them are unscientific -persons, who either know nothing of the most important phenomena of -Biology, or at least possess no idea of their deeper significance. What -should we say of an unscientific person who presumed to express an -opinion on the cell-theory, without ever having seen cells; or of one -who presumed to question the vertebral-theory, without ever having -studied comparative anatomy? And yet one may meet with such ridiculous -arrogance any day in the history of the biological Theory of Descent. -One hears thousands of unscientific and but half-educated persons pass a -final judgment upon it, although they know nothing either of botany or -of zoology, of comparative anatomy or the theory of tissues, of -palæontology or embryology. Hence it happens, as Huxley well says, that -most of the writings published against Darwin are not worth the paper -upon which they are written. - -We might add that there are many naturalists, and even celebrated -zoologists and botanists, among the opponents of the Theory of Descent; -but these latter are mostly old stagers, who have grown grey in quite -opposite views, and whom we cannot expect, in the evening of their -lives, to submit to a reform in their conception of the universe, which -has become to them a fixed idea. - -It is, moreover, expressly to be remarked, that not only a general -insight into the _whole_ domain of biological phenomena, but also a -philosophical understanding of it, are the necessary preliminary -conditions for becoming convinced of and adopting the Theory of Descent. -Now we shall find that these indispensable preliminary conditions are, -unfortunately, by no means fulfilled by the majority of naturalists of -the present day. The immense amount of empirical facts with which the -gigantic advances of modern natural science have recently made us -acquainted has led to a prevailing inclination for the special study of -single phenomena and of small and narrow domains. This causes the -knowledge of other paths, and especially of Nature as a great -comprehensive whole, to be in most cases completely neglected. Every one -with sound eyes and a microscope, together with industry and patience -for study, can in our day attain a certain degree of celebrity by -microscopic "discoveries," without, however, deserving the name of a -naturalist. This name is deserved only by him who not merely strives to -_know_ the individual phenomena, but who also seeks to _discover_ their -causal connection. Even in our own day, most palæontologists examine and -describe fossils without knowing the most important facts of embryology. -Embryologists, on the other hand, follow the history of development of a -particular organic individual, without having an idea of the -palæontological history of the whole tribe, of which fossils are the -records. And yet these two branches of the organic history of -development--ontogeny, or the history of the individual, and phylogeny, -or the history of the tribe--stand in the closest causal connection, and -the one cannot be understood without the other. The same may be said of -the systematic and the anatomical part of Biology. There are even now, -in zoology and botany, many systematic naturalists who work with the -erroneous idea that it is possible to construct a natural system of -animals and plants simply by a careful examination of the external and -readily accessible forms of bodies, without a deeper knowledge of their -internal structure. On the other hand, there are anatomists and -histologists who think it possible to obtain a true knowledge of animal -and vegetable bodies merely by a most careful examination of the inner -structure of the body of some individual species, without the -comparative examination of the bodily form of all kindred organisms. And -yet here, as everywhere, the internal and external factors, to wit, -Inheritance and Adaptation, stand in the closest mutual relation, and -the individual can never be thoroughly understood without a comparison -of it with the whole of which it is a part. To those one-sided -specialists we should like in Goethe's words to say:-- - - We must, contemplating Nature, - Part as Whole, give equal heed to: - Nought is inward, nought is outward, - For the inner is the outer.[6] - -And again:-- - - Nature has neither kernel nor shell, - It is she that is All and All at once.[7] - -What is even more detrimental to the general understanding of nature as -a whole than this one-sided tendency, is _the want of a philosophical -culture_, and this applies to most of the naturalists of the present -day. The various errors of the earlier speculative nature-philosophy -made during the first thirty years of our century, have brought the -whole of philosophy into such bad repute with the exact empirical -naturalists, that they live in the strange delusion that it is possible -to erect the edifice of natural science out of mere facts, without their -philosophic connection; in short, out of mere knowledge, without the -understanding of it. But as a purely speculative and absolutely -philosophical system, which does not concern itself with the -indispensable foundation of empirical facts, becomes a castle in the -air, which the first real experiment throws to the winds; so, on the -other hand, a purely empirical system, constructed of nothing but facts, -remains a disorderly heap of stones, which will never deserve the name -of an edifice. Bare facts established by experience are nothing but rude -stones, and without their thoughtful valuation, without their -philosophic connection, no science can be established. As I have already -tried to impress upon my reader, the _strong edifice of true monistic -science_, or what is the same thing, the _Science of Nature, exists only -by the closest interaction, and the reciprocal penetration of philosophy -and empirical knowledge_. - -This lamentable estrangement between science and philosophy, and the -rude empiricism which is now-a-days unfortunately praised by most -naturalists as "exact science," have given rise to those strange freaks -of the understanding, to those gross insults against elementary logic, -and to that incapacity for forming the simplest conclusions which one -may meet with any day in all branches of science, but especially in -zoology and botany. It is here that the neglect of a philosophical -culture and training of the mind, directly avenges itself most -painfully. It is not to be wondered at that the deep inner truth of the -Theory of Descent remains a sealed book to those rude empiricists. As -the common proverb justly says: they cannot see the wood for the trees. -It is only by a more general philosophical study, and especially by a -more strictly logical training of the mind, that this sad state of -things can be remedied. (Compare Gen. Morph. i. 63; ii. p. 447.) - -If we rightly consider this circumstance, and if we further reflect upon -it in connection with the empirical foundation of the philosophical -theory of development, we shall at once see how we are placed respecting -the oft-demanded _proofs of the theory of descent_. The more the -doctrine of filiation has of late years made way for itself, and the -more all thoughtful, younger naturalists, and all truly -biologically-educated philosophers have become convinced of its inner -truth and absolute necessity, the louder have its opponents called for -actual proofs. The same persons who, shortly after the publication of -Darwin's work, declared it to be "a groundless, fantastic system," an -"arbitrary speculation," an "ingenious dream," now kindly condescend to -declare that the theory of descent certainly is a scientific -"_hypothesis_," but that it still requires to be "_proved_." When these -remarks are made by persons who do not possess the requisite -empirico-philosophical culture, nor the necessary knowledge in -comparative anatomy, embryology, and palæontology, we cannot be much -offended, and we refer them to the study of those sciences. But when -similar remarks are made by acknowledged specialists, by teachers of -zoology and botany, who certainly ought to possess a general insight -into the whole domain of their science, or who are actually familiar -with the facts of those scientific domains, then we are really at a loss -what to say. Those who are not satisfied with the treasures of our -present empirical knowledge of nature as a basis on which to establish -the Theory of Descent, will not be convinced by any other facts which -may hereafter be discovered; for we can conceive no circumstances which -would furnish stronger or a more complete testimony to the truth of the -doctrine of filiation than is even now seen, for example, in the -well-known facts of comparative anatomy and ontogeny. I must here again -direct attention to the fact, _that all the great and general laws, and -all the comprehensive series of phenomena of the most different domains -of biology can only be explained and understood by the Theory of -Development_ (and especially by its biological part, the Theory of -Descent), and that without it they remain completely inexplicable and -incomprehensible. _The internal causal connection_ between them all -proves the Theory of Descent to be the greatest _inductive law_ of -Biology. - -Before concluding, I will once more name all those series of inductions, -all those general laws of Biology, upon which this comprehensive law of -development is firmly based. - -(1.) _The palæontological history of the development of organisms_, the -gradual appearance and the historical succession of the different -species and groups of species, the empirical laws of the palæontological -change of species, as furnished to us by the science of fossils, and -more especially the _progressive differentiation and perfecting_ of -animal and vegetable groups in the successive periods of the earth's -history. - -(2.) _The individual history of development of organisms_, embryology -and metamorphology, the gradual changes in the slow development of the -body and its particular organs, especially _the progressive -differentiation and perfecting_ of the organs and parts of the body in -the successive periods of the individual development. - -(3.) _The inner causal connection between ontogeny and phylogeny_, the -parallelism between the individual history of the development of -organisms, and the palæontological history of the development of their -ancestors, a connection which is actually established by the laws of -_Inheritance_ and _Adaptation_, and which may be summed up in the words: -ontogeny, according to the laws of inheritance and adaptation, repeats -in its large features the outlines of phylogeny. - -(4.) _The comparative anatomy of organisms_, the proof of the essential -agreement of the inner structure of kindred organisms, in spite even of -the greatest difference of external form in the various species; their -explanation by the causal dependence of the internal agreement of the -structure on _Inheritance_, the external dissimilarity of the bodily -form on _Adaptation_. - -(5.) _The inner causal connection between comparative anatomy and the -history of development_, the harmonious agreement between the laws of -the gradual development, _the progressive differentiation and -perfecting_, as they may be seen in comparative anatomy on the one hand, -in ontogeny and palæontology on the other. - -(6.) _Dysteleology, or the theory of purposelessness_, the name I have -given to the _science of rudimentary organs_, of suppressed and -degenerated, aimless and inactive, parts of the body; one of the most -important and most interesting branches of comparative anatomy, which, -when rightly estimated, is alone sufficient to refute the fundamental -error of the teleological and dualistic conception of Nature, and to -serve as the foundation of the mechanical and monistic conception of the -universe. - -(7.) _The natural system of organisms_, the natural grouping of all the -different forms of Animals, Plants, and Protista into numerous smaller -or larger groups, arranged beside and above one another; the kindred -connection of species, genera, families, orders, classes, tribes, etc., -more especially, however, the _arboriform branching character of the -natural system_, which is the spontaneous result of a natural -arrangement and classification of all these graduated groups or -categories. The result attained in attempting to exhibit the -relationships of the mere forms of organisms by a tabular classification -is only explicable when regarded as the expression of their actual -_blood relationship_; _the tree shape of the natural system_ can only be -understood as the actual _pedigree of the organisms_. - -(8.) _The chorology of organisms_, the science of the local distribution -of organic species, of their _geographical_ and _topographical -dispersion over the surface of the earth_, over the heights of -mountains and in the depths of the ocean, but especially the important -phenomenon that every species of organism proceeds from a so-called -"_centre of creation_" (more correctly a "_primæval home_" or "_centre -of distribution_"); that is, from a single locality, where it originated -but once, and whence it spread. - -(9.) _The oecology of organisms_, the knowledge of the sum of the -_relations of organisms to the surrounding outer world_, to organic and -inorganic conditions of existence; the so-called "_economy of nature_," -the correlations between all organisms living together in one and the -same locality, their adaptation to their surroundings, their -modification in the struggle for existence, especially the circumstances -of parasitism, etc. It is just these phenomena in "the economy of -nature" which the unscientific, on a superficial consideration, are wont -to regard as the wise arrangements of a Creator acting for a definite -purpose, but which on a more attentive examination show themselves to be -the necessary results of mechanical causes. - -(10.) _The unity of Biology as a whole_, the deep inner connection -existing between all the phenomena named and all the other phenomena -belonging to zoology, protistics, and botany, and which are simply and -naturally explained by a single common principle. This principle can be -no other than the common derivation of all the specifically different -organisms from a single, or from several absolutely simple, primary -forms like the Monera, which possess no organs. The Theory of Descent, -by assuming this common derivation, throws a clear light upon these -individual series of phenomena, as well as upon their totality, without -which their deeper causal connection would remain completely -incomprehensible to us. The opponents of the Theory of Descent can in no -way explain any single one of these series of phenomena or their deeper -connection with one another. So long as they are unable to do this, _the -Theory of Descent remains the one adequate biological theory_. - -We should, on account of the grand proofs just enumerated, have to adopt -Lamarck's Theory of Descent for the explanation of biological phenomena, -even if we did not possess Darwin's Theory of Selection. The one is so -completely and _directly proved_ by the other, and established by -mechanical causes, that there remains nothing to be desired. The laws of -_Inheritance_ and _Adaptation_ are universally acknowledged -_physiological_ facts, the former traceable to _propagation_, the latter -to the _nutrition_ of organisms. On the other hand, the _struggle for -existence_ is a _biological_ fact, which with mathematical necessity -follows from the general disproportion between the average number of -organic individuals and the numerical excess of their germs. But as -Adaptation and Inheritance in the struggle for life are in continual -interaction, it inevitably follows that _natural selection_, which -everywhere influences and continually changes organic species, must, by -making use of _divergence of character_, produce new species. Its -influence is further especially favoured by the active and passive -_migrations_ of organisms, which go on everywhere. If we give these -circumstances due consideration, the continual and gradual modification -or transmutation of organic species will appear as a biological process, -which must, according to causal law, of _necessity_ follow from the -actual nature of organisms and their mutual correlations. - -That even the _origin of man_ must be explained by this general organic -process of transmutation, and that it is simply as well as naturally -explained by it, has, I believe, been sufficiently proved in my last -chapter but one. I cannot, however, avoid here once more directing -attention to the inseparable connection between this so-called "theory -of apes," or "pithecoid theory," and the whole Theory of Descent. If the -latter is the greatest _inductive law_ of biology, then it of necessity -follows that the former is its most important _deductive law_. They -stand and fall together. As all depends upon a right understanding of -this proposition, which in my opinion is very important, and which I -have therefore several times brought before the reader, I may be allowed -to explain it here by an example. - -In all mammals known to us the centre of the nervous system is the -spinal marrow and the brain, and the centre of the vascular system is a -quadrupal heart, consisting of two principal chambers and two -ante-chambers. From this we draw the general inductive conclusion that -all mammals, without exception, those extinct, together with all those -living species as yet unknown to us, as well as the species which we -have examined, possess a like organization, a like heart, brain, and -spinal marrow. Now if, as still happens every year, there be discovered -in any part of the earth a new species of mammal, a new species of -marsupial, or a new species of deer, or a new species of ape, every -zoologist knows with certainty at once, without having examined its -inner structure, that this species must possess a quadruple heart, a -brain and spinal marrow, like all other mammals. Not a single naturalist -would ever think of supposing that the central nervous system of this -new species of mammal could possibly consist of a ventral cord with an -oesophageal collar as in the insects, or of scattered pairs of knots as -in the molluscs, or that its heart could be many-chambered as in flies, -or one-chambered as in the tunicates. This completely certain and safe -conclusion, although it is not based upon any direct experience, is a -_deductive conclusion_. In the same way, as I have shown in a previous -chapter, Goethe, from the comparative anatomy of mammals, established -the general inductive conclusion that they all possess a mid jawbone, -and afterwards drew from it the special deductive conclusion that man, -who in all other respects does not essentially differ from other -mammals, must also possess a like mid jawbone. He maintained this -conclusion without having actually seen the human mid jawbone, and only -proved its existence subsequently by actual observation (vol. i. p. 84). - -The process of _induction_ is a logical system of forming conclusions -_from the special to the general_, by which we advance from many -individual experiences to a general law; _deduction_, on the other hand, -draws a conclusion _from the general to the special_, from a general law -of nature to an individual case. Thus the _Theory of Descent_ is, -without doubt, a great _inductive law_, empirically based upon all the -biological experience cited above; the pithecoid theory, on the other -hand, which asserts that man has developed out of lower, and in the -first place out of ape-like mammals, is a _deductive law_ inseparably -connected with the general inductive law. - -The pedigree of the human race, the approximate outlines of which I gave -in the last chapter but one, of course remains in detail (like all the -pedigrees of animals and plants previously discussed) a more or less -approximate general hypothesis. This however does not affect the -application of the theory of descent to man. Here, as in all -investigations on the derivation of organisms, one must clearly -distinguish between the general _theory_ of descent and the special -_hypotheses_ of descent. The general _theory_ of descent claims full and -lasting value, because it is an inductive law, based upon all the whole -series of biological phenomena and their inner causal connection. Every -special _hypothesis_ of descent, on the other hand, has its special -value determined by the existing condition of our biological knowledge, -and by the extent of the objective empirical basis upon which we -deductively establish this particular hypothesis. Hence, all the -individual attempts to obtain a knowledge of the pedigree of any one -group of organisms possesses but a temporary and conditional value, and -any special hypothesis relating to it will become the more and more -perfect the greater the advance we make in the comparative anatomy, -ontogeny, and palæontology of the group in question. The more, however, -we enter into genealogical details, and the further we trace the -separate off-shoots and branches of the pedigree, the more uncertain and -subjective becomes our special _hypothesis_ of descent on account of the -incompleteness of our empirical basis. This however does no injury to -the general _theory_ of descent, which remains as the indispensable -foundation for really profound apprehension of biological phenomena. -Accordingly, there can be no doubt that we can and must, with full -assurance, regard the derivation of man--in the first place, from -ape-like forms; farther back, from lower mammals, and thus continually -farther back to lower stages of the vertebrata down to their lowest -invertebrate roots, nay, even down to a simple plastid--as a general -_theory_. On the other hand, the special tracing of the human pedigree, -the closer definition of the animal forms known to us, which either -actually belong to the ancestors of man, or at least stand in very close -blood relationship to them, will always remain a more or less -approximate _hypothesis_ of descent, all the more in danger of deviating -from the real pedigree the nearer it endeavours to approach it by -searching for the individual ancestral forms. This state of things -results from the immense gaps in our palæontological knowledge, which -can, under no circumstances, ever attain to even an approximate -completeness. - -A thoughtful consideration of this important circumstance at once -furnishes the answer to a question which is commonly raised in -discussing this subject, namely, the question of scientific _proofs for -the animal origin of the human race_. Not only the opponents of the -Theory of Descent, but even many of its adherents who are wanting in the -requisite philosophical culture, look too much for "signs" and for -special empirical advances in the science of nature. They await the -sudden discovery of a human race with tails, or of a talking species of -ape, or of other living or fossil transition forms between man and the -ape, which shall fill the already narrow chasm between the two, and thus -empirically "prove" the derivation of man from apes. Such special -manifestations, were they ever so convincing and conclusive, would not -furnish the proof desired. Unthinking persons, or those unacquainted -with the series of biological phenomena, would still be able to maintain -the objections to those special testimonies which they now maintain -against our theory. - -The absolute certainty of the Theory of Descent, even in its application -to man, is built on a more solid foundation; and its true inner value -can never be tested simply by reference to individual experience, but -only by a philosophical comparison and estimation of the treasures of -all our biological experiences. The inestimable importance of the Theory -of Descent is surely based upon this, that the theory follows of -necessity (as a general inductive law) from the comparative synthesis of -all organic phenomena of nature, and more especially from the triple -parallelism of comparative anatomy, of ontogeny, and phylogeny; and the -pithecoid theory under all circumstances (apart from all special proofs) -remains as a special deductive conclusion which must of necessity be -drawn from the general inductive law of the Theory of Descent. - -In my opinion, all depends upon a right understanding of this -_philosophical foundation of the Theory of Descent_ and of the -_pithecoid theory_ which is inseparable from it. Many persons will -probably admit this, and yet at the same time maintain that all this -applies only to the _bodily_, not to the _mental_ development of man. -Now, as we have hitherto been occupied only with the former, it is -perhaps necessary here to cast a glance at the latter, in order to show -that it is also subject to the great general law of development. In -doing this it is above all necessary to recollect that body and mind can -in fact never be considered as distinct, but rather that both sides of -nature are inseparably connected, and stand in the closest interaction. -As even Goethe has clearly expressed it--"matter can never exist and act -without mind, and mind never without matter." The artificial discord -between mind and body, between force and matter, which was maintained by -the erroneous dualistic and teleological philosophy of past times has -been disposed of by the advances of natural science, and especially by -the theory of development, and can no longer exist in face of the -prevailing mechanical and monistic philosophy of our day. How human -nature, and its position in regard to the rest of the universe, is to be -conceived of according to the modern view, has been minutely discussed -by Radenhausen in his "Isis,"(33) which is excellent and well worth -perusal. - -With regard to the origin of the human mind or the soul of man, we, in -the first place, perceive that in every human individual it develops -from the beginning, step by step and gradually, just like the body. In a -newly born child we see that it possesses neither an independent -consciousness, nor in fact clear ideas. These arise only gradually when, -by means of sensuous experience, the phenomena of the outer world affect -the central nervous system. But still the little child is wanting in all -those differentiated emotions of the soul which the full-grown man -acquires only by the long experience of years. From this graduated -development of the human soul in every single individual we can, in -accordance with the inner causal connection between ontogeny and -phylogeny, directly infer the gradual development of the human soul in -all mankind, and further, in the whole of the vertebrate tribe. In its -inseparable connection with the body, the human soul or mind has also -had to pass through all those gradual stages of development, all those -various degrees of differentiation and perfecting, of which the -hypothetical series of human ancestors sketched in a late chapter gives -an approximate representation. - -It is true that this conception generally greatly offends most persons -on their first becoming acquainted with the Theory of Development, -because more than all others it most strongly contradicts the -traditional and mythological ideas, and the prejudices which have been -held sacred for thousands of years. But like all other functions of -organisms, the human soul must necessarily have historically developed, -and the comparative or empirical study of animal psychology clearly -shows that this development can only be conceived of as a gradual -evolution from the soul of vertebrate animals, as a gradual -differentiation and perfecting which, in the course of many thousands of -years, has led to the glorious triumph of the human mind over its lower -animal ancestral stages. Here, as everywhere, the only way to arrive at -a knowledge of natural truth is to compare kindred phenomena, and -investigate their development. Hence we must above all, as we did in the -examination of the bodily development, compare the highest animal -phenomena on the one hand with the lowest animal phenomena, and on the -other with the lowest human phenomena. The final result of this -comparison is this--that _between the most highly developed animal -souls, and the lowest developed human souls, there exists only a small -quantitative, but no qualitative difference_, and that this difference -is much less than the difference between the lowest and the highest -human souls, or than the difference between the highest and the lowest -animal souls. - -In order to be convinced of this important result, it is above all -things necessary to study and compare the mental life of wild savages -and of children.(32) At the lowest stage of human mental development are -the Australians, some tribes of the Polynesians, and the Bushmen, -Hottentots, and some of the Negro tribes. Language, the chief -characteristic of genuine men, has with them remained at the lowest -stage of development, and hence also their formation of ideas has -remained at a low stage. Many of these wild tribes have not even a name -for animal, plant, colour, and such most simple ideas, whereas they have -a word for every single, striking _form_ of animal and plant, and for -every single sound or colour. Thus even the most simple abstractions are -wanting. In many of these languages there are numerals only for one, -two, and three: no Australian language counts beyond four. Very many -wild tribes can count no further than ten or twenty, whereas some very -clever dogs have been made to count up to forty and even beyond sixty. -And yet the faculty of appreciating number is the beginning of -mathematics! Nothing, however, is perhaps more remarkable in this -respect, than that some of the wildest tribes in southern Asia and -eastern Africa have no trace whatever of the first foundations of all -human civilization, of family life, and marriage. They live together in -herds, like apes, generally climbing on trees and eating fruits; they do -not know of fire, and use stones and clubs as weapons, just like the -higher apes. All attempts to introduce civilization among these, and -many of the other tribes of the lowest human species, have hitherto been -of no avail; it is impossible to implant human culture where the -requisite soil, namely, the perfecting of the brain, is wanting. Not one -of these tribes has ever been ennobled by civilization; it rather -accelerates their extinction. They have barely risen above the lowest -stage of transition from man-like apes to ape-like men, a stage which -the progenitors of the higher human species had already passed through -thousands of years ago.(44) - -Now consider, on the other hand, the highest stages of development of -mental life in the higher vertebrate animals, especially birds and -mammals. If, as is usually done, we divide the different emotions of the -soul into three principal groups--sensation, will, and thought--we shall -find in regard to every one of them, that the most highly developed -birds and mammals are on a level with the lowest human beings, or even -decidedly surpass them. The _will_ is as distinctly and strongly -developed in higher animals as in men of character. In both cases it is -never actually free, but always determined by a causal chain of ideas. -(Compare vol. i. p. 237.) In like manner, the different degrees of will, -energy, and passion are as variously graduated in higher animals as in -man. The _affections_ of the higher animals are not less tender and warm -than those of man. The fidelity and devotion of the dog, the maternal -love of the lioness, the conjugal love and connubial fidelity of doves -and love-birds are proverbial, and might serve as examples to many men. -If these virtues are to be called "instincts," then they deserve the -same name in mankind. Lastly, with regard to _thought_, the comparative -consideration of which doubtless presents the most difficulties, this -much may with certainty be inferred--especially from an examination of -the comparative psychology of cultivated domestic animals--that the -processes of thinking, here follow the same laws as in ourselves. -Experiences everywhere form the foundation of conceptions, and lead to -the recognition of the connection between cause and effect. In all -cases, as in man, it is the path of induction and deduction which leads -to the formation of conclusions. It is evident that in all these -respects the most highly developed animals stand much nearer to man than -to the lower animals, although they are also connected with the latter -by a chain of gradual and intermediate stages. In Wundt's excellent -"Lectures on the Human and Animal Soul,"(46) there are a number of -proofs of this. - -Now, if instituting comparisons in both directions, we place the lowest -and most ape-like men (the Austral Negroes, Bushmen, and Andamans, -etc.), on the one hand, together with the most highly developed animals, -for instance, with apes, dogs, and elephants, and on the other hand, -with the most highly developed men--Aristotle, Newton, Spinoza, Kant, -Lamarck, or Goethe--we can then no longer consider the assertion, that -the mental life of the higher mammals has gradually developed up to that -of man, as in any way exaggerated. If one must draw a sharp boundary -between them, it has to be drawn between the most highly developed and -civilized man on the one hand, and the rudest savages on the other, and -the latter have to be classed with the animals. This is, in fact, the -opinion of many travellers, who have long watched the lowest human races -in their native countries. Thus, for example, a great English traveller, -who lived for a considerable time on the west coast of Africa, says: "I -consider the negro to be a lower species of man, and cannot make up my -mind to look upon him as 'a man and a brother,' for the gorilla would -then also have to be admitted into the family." Even many Christian -missionaries, who, after long years of fruitless endeavours to civilize -these lowest races, have abandoned the attempt, express the same harsh -judgment, and maintain that it would be easier to train the most -intelligent domestic animals to a moral and civilized life, than these -unreasoning brute-like men. For instance, the able Austrian missionary -Morlang, who tried for many years without the slightest success to -civilize the ape-like negro tribes on the Upper Nile, expressly says: -"that any mission to such savages is absolutely useless. They stand far -below unreasoning animals; the latter at least show signs of affection -towards those who are kind towards them, whereas these brutal natives -are utterly incapable of any feeling of gratitude." - -Now, it clearly follows from these and other testimonies, that the -mental differences between the lowest men and the animals are less than -those between the lowest and the highest men; and if, together with -this, we take into consideration the fact that in every single human -child mental life develops slowly, gradually, and step by step, from the -lowest condition of animal unconsciousness, need we still feel offended -when told that the mind of the whole human race has in like manner gone -through a process of slow, gradual, and historical development? Can we -find it "degrading" to the human soul that, by a long and slow process -of differentiation and perfecting, it has very gradually developed out -of the soul of vertebrate animals? I freely acknowledge that this -objection, which is at present raised by many against the pithecoid -theory, is quite incomprehensible to me. On this point Bernhard Cotta, -in his excellent "Geologie der Gegenwart," very justly remarks: "Our -ancestors may be a great honour to us; but it is much better if we are -an honour to them!"(31) - -Our Theory of Development explains the origin of man and the course of -his historical development in the only natural manner. We see in his -gradually ascensive development out of the lower vertebrata, the -greatest triumph of humanity over the whole of the rest of Nature. We -are proud of having so immensely outstripped our lower animal ancestors, -and derive from it the consoling assurance that in future also, mankind, -as a whole, will follow the glorious career of progressive development, -and attain a still higher degree of mental perfection. When viewed in -this light, the Theory of Descent as applied to man opens up the most -encouraging prospects for the future, and frees us from all those -anxious fears which have been the scarecrows of our opponents. - -We can even now foresee with certainty that the complete victory of our -Theory of Development will bear immensely rich fruits--fruits which have -no equal in the whole history of the civilization of mankind. Its first -and most direct result--the complete reform of _Biology_--will -necessarily be followed by a still more important and fruitful reform of -_Anthropology_. From this new theory of man there will be developed a -new _philosophy_, not like most of the airy systems of metaphysical -speculation hitherto prevalent, but one founded upon the solid ground of -Comparative Zoology. A beginning of this has already been made by the -great English philosopher Herbert Spencer.(45) Just as this new monistic -philosophy first opens up to us a true understanding of the real -universe, so its application to practical human life must open up a new -road towards moral perfection. By its aid we shall at last begin to -raise ourselves out of the state of social barbarism in which, -notwithstanding the much vaunted civilization of our century, we are -still plunged. For, unfortunately, it is only too true, as Alfred -Wallace remarks with regard to this, at the end of his book of travels: -"Compared with our wondrous progress in physical science and its -practical applications, our system of government, of administering -justice, of national education, and our whole social and moral -organisation remains in a state of barbarism." - -This social and moral barbarism we shall never overcome by the -artificial and perverse training, the one-sided and defective teaching, -the inner untruth and the external tinsel, of our present state of -civilization. It is above all things necessary to make a complete and -honest return to Nature and to natural relations. This return, however, -will only become possible when man sees and understands his true "place -in nature." He will then, as Fritz Ratzel has excellently remarked,(47) -"no longer consider himself an _exception_ to natural laws, but begin to -seek for what is lawful in his own actions and thoughts, and endeavour -to lead a life _according_ to natural laws." He will come to arrange his -life with his fellow-creatures--that is, the family and the state--not -according to the laws of distant centuries, but according to the -rational principles deduced from knowledge of nature. Politics, morals, -and the principles of justice, which are still drawn from all possible -sources, will have to be formed in accordance with natural laws only. An -_existence worthy of man_, which has been talked of for thousands of -years, will at length become a reality. - -The highest function of the human mind is perfect knowledge, fully -developed consciousness, and the moral activity arising from it. "Know -thyself!" was the cry of the philosophers of antiquity to their -fellow-men who were striving to ennoble themselves. "Know thyself!" is -the cry of the Theory of Development, not merely to the individual, but -to all mankind. And whilst increased knowledge of self becomes, in the -case of every individual man, a strong force urging to an increased -attention to conduct, mankind as a whole will be led to a higher path of -moral perfection by the knowledge of its true origin and its actual -position in Nature. The simple religion of Nature, which grows from a -true knowledge of Her, and of Her inexhaustible store of revelations, -will in future ennoble and perfect the development of mankind far beyond -that degree which can possibly be attained under the influence of the -multifarious religions of the churches of the various -nations,--religions resting on a blind belief in the vague secrets and -mythical revelations of a sacerdotal caste. Future centuries will -celebrate our age, which was occupied with laying the foundations of the -Doctrine of Descent, as the new era in which began a period of human -development, rich in blessings,--a period which was characterized by the -victory of free inquiry over the despotism of authority, and by the -powerful ennobling influence of the Monistic Philosophy. - - - FOOTNOTES: - - [1] With the exception of a single specimen of the bones of a foot, - preserved in the cabinet of Amherst College.--E. R. L. - - [2] The primary stock of the Coniferæ divided into two branches at an - early period, into the Araucariæ on the one hand, and the Taxaceæ, or - yew-trees, on the other. The majority of recent Coniferæ are derived - from the former. Out of the latter the third class of the - Gymnosperms--the Meningos, or Gnetaceæ--were developed. This small but - very interesting class contains only three different genera--Gnetum, - Welwitschia, and Ephedra; it is, however, of great importance, as it - forms the transition group from the Coniferæ to the Angiosperms, and - more especially to the Dicotyledons. - - [3] "Ueber ein Aequivalent der takonischen Schiefer Nordamerikas in - Deutschland." - - [4] The English word "Insects" might with advantage be used in the - Linnæan sense for the whole group of Arthropods. In this case the - Hexapod Insects might be spoken of as the Flies.--E. R. L. - - [5] Weisbach: "Novara-Reise," Anthropholog. Theil. - - [6] Müsset im Naturbetrachten - Immer Eins wie Alles achten. - Nichts ist drinnen, Nichts ist drauszen, - Denn was innen, das ist auszen. - - [7] Natur hat weder Kern noch Schale, - Alles ist sie mit einem Male. - - - - -LIST OF THE WORKS REFERRED TO IN THE TEXT BY FIGURES, THUS--(1), - -_The study of which is recommended to the Reader._ - - -1. _Charles Darwin_, On the Origin of Species by means of Natural -Selection; or, the Preservation of Favoured Races in the Struggle for -Life. London, 1859. 5th Edition, 1869. - -2. _Jean Lamarck_, Philosophie Zoologique, ou Exposition des -Considérations relatives à l'histoire naturelle des animaux; à la -diversité de leur organisation et des facultés, qu'ils en obtiennent; -aux causes physiques, qui maintiennent en eux la vie et donnent lieu aux -mouvemens, qu'ils exécutent; enfin, à celles qui produisent, les unes le -sentiment, et les autres l'intelligence de ceux qui en sont doués. 2 -Tomes. Paris, 1809. - -3. _Wolfgang Goethe_, Zur Morphologie: Bildung und Umbildung organischer -Naturen. Die Metamorphose der Pflanzen, 1790. Osteologie, 1786. Vorträge -über die drei ersten Capitel des Entwurfs einer allgemeinen Einleitung -in die vergleichende Anatomie, ausgehend von der Osteologie, 1786. Zur -Naturwissenschaft im Allgemeinen, 1780-1832. - -(Wolfgang Goethe, Contributions to Morphology: Formation and -Transformation of Organic Natures. The Metamorphosis of Plants, 1790. -Osteology, 1786. Lectures on the first three chapters of an Attempt at a -General Introduction to Comparative Anatomy, beginning with Osteology, -1786. Contributions to the Science of Nature in general, 1780-1832.) - -4. _Ernst Haeckel_, Generelle Morphologie der Organismen: Allgemeine -Grundzüge der organischen Formenwissenschaft, mechanisch begründet durch -die von Charles Darwin reformirte Descendenz-theorie. I. Band, -Allgemeine Anatomie der Organismen, oder Wissenschaft von den -entwickelten organischen Formen. II. Band, Allgemeine -Entwickelungsgeschichte der Organismen, oder Wissenschaft von den -entstehenden organischen Formen. Berlin, 1866. - -(Ernst Haeckel, General Morphology of Organisms; General Outlines of the -Science of Organic Forms based on Mechanical Principles through the -Theory of Descent as reformed by Charles Darwin. Vol. I., General -Anatomy of Organisms; or, the Science of Fully Developed Organic Forms. -Vol. II., General History of the Development of Organisms; or, the -Science of Organic Forms in their Origin. Berlin, 1866.) - -5. _Louis Agassiz_, An Essay on Classification. Contributions to the -Natural History of the United States. Boston. Vol. I., 1857. - -6. _August Schleicher_, Die Darwin'sche Theorie und die -Sprachwissenschaft. Weimar, 1863. - -(August Schleicher, Darwin's Theory and the Science of Language. Weimar, -1863.) - -7. _M. J. Schleiden_, Grundzüge der wissenschaftlichen Botanik (die -Botanik als inductive Wissenschaft). 2 Bände. Leipzig, 1849. - -(M. J. Schleiden, Principles of Scientific Botany (Botany as an -Inductive Science). 2 Vols. Leipzig, 1849. Translated by Edwin -Lankester, M.D., F.R.S. London, 1849.) - -8. _Franz Unger_, Versuch einer Geschichte der Pflanzenwelt. Wien, 1852. - -(Franz Unger, Essay on the History of the Vegetable Kingdom. Vienna, -1852.) - -9. _Victor Carus_, System der thierischen Morphologie. Leipzig, 1853. - -(Victor Carus, System of Animal Morphology. Leipzig, 1853.) - -10. _Louis Büchner_, Kraft und Stoff. Empirisch-naturphilosophische -Studien in allgemein verständlicher Darstellung, Frankfort, 1855, 3 -Auflage. 1867, 9 Auflage. - -(Louis Büchner, Force and Matter. Studies in the Empirical Philosophy of -Nature, treated popularly. Frankfort, 1855, 3rd Edition. 1867, 9th -Edition.) - -11. _Charles Lyell_, Principles of Geology. London, 1830. 10th Edition, -1868. - -12. _Albert Lange_, Geschichte des Materialismus und Kritik seiner -Bedeutung in der Gegenwart. Iserlohn, 1866. - -(Albert Lange, History of Materialism, and a Criticism of its Importance -at the Present Time. Iserlohn, 1866.) - -13. _Charles Darwin_, Voyage of the _Beagle_. London. - -14. _Charles Darwin_, The Variation of Animals and Plants under -Domestication. 2 Vols. London, 1868. - -15. _Ernst Haeckel_, Studien über Moneren und andere Protisten, nebst -einer Rede über Entwickelungsgang und Aufgabe der Zoologie. Mit 6 -Kupfertafeln. Leipzig, 1870. - -(Ernst Haeckel, Studies on the Monera and other Protista, together with -a Discourse on the Evolution and the Problems of Zoology. With 6 -Copper-plates. Leipzig, 1870.) - -16. _Fritz Müller_, Für Darwin. Leipzig, 1864. - -(Fritz Müller, For Darwin. Translated by W. S. Dallas. London, Murray.) - -17. _Thomas Huxley_, On our Knowledge of the Causes of the Phenomena of -Organic Nature. Six Popular Lectures. London, Hardwicke, 1862. - -18. _H. G. Brönn_, Morphologische Studien über die Gestaltungsgesetze -der Naturkörper überhaupt, und der Organischen insbesondere. Leipzig und -Heidelberg, 1858. - -(H. G. Brönn, Morphological Studies on the Laws of Form of Natural -Bodies in General, and of Organic Bodies in Particular. Leipzig and -Heidelberg, 1858.) - -19. _H. G. Brönn_, Untersuchungen über die Entwickelungsgesetze der -organischen Welt während der Bildungszeit unserer Erdoberfläche. -Stuttgart, 1858. - -(H. G. Brönn, Investigations on the Laws of Development of the Organic -World during the Time of the Formation of the Earth's Crust. Stuttgart, -1858.) - -20. _Carl Ernst Bär_, Ueber Entwickelungsgeschichte der Thiere. -Beobachtung und Reflexion. 2 Bände. 1828. - -(Carl Ernst Bär, On the History of the Development of Animals. -Observation and Reflection. 2 Vols. 1828.) - -21. _Carl Gegenbaur_, Grundzüge der vergleichenden Anatomie. Leipzig, -1859. 2 (Umgearbeitete) Auflage, 1870. - -(Carl Gegenbaur, Outlines of Comparative Anatomy. Leipzig, 1859. 2nd -(Revised) Edition, 1870.) - -22. _Immanuel Kant_, Allgemeine Naturgeschichte und Theorie des Himmels, -oder Versuch von der Verfassung und dem mechanischen Ursprunge des -ganzen Weltgebäudes nach Newton'schen Grundsätzen abgehandelt. -Königsberg, 1755. - -(Immanuel Kant, General History of Nature and Theory of the Heavens; or, -Essay on the Constitution and the Mechanical Origin of the whole -Universe treated according to Newton's Principles. Königsberg, 1755.) - -23. _Ernst Haeckel_, Die Radiolarien. Eine Monographie. Mit einem Atlas -von 35 Kupfertafeln. Berlin, 1862. - -(Ernst Haeckel, The Radiolaria. A Monograph, with Atlas containing 35 -Copper-plates. Berlin, 1862.) - -24. _August Weismann_, Ueber den Einflusz der Isolirung auf die -Artbildung. Leipzig, 1872. - -(August Weismann, On the Influence of Isolation on the Formation of -Species. Leipzig, 1872.) - -25. _Ernst Haeckel_, Ueber die Enstehung und den Stammbaum des -Menschengeschlechts. Zwei Vorträge in der Sammlung gemeinverständlicher -wissenschaftlicher Vorträge, herausgegeben von Virchow und Holtzendorff. -Berlin, 1868. 2 Auflage, 1870. - -(Ernst Haeckel, On the Origin and the Pedigree of the Human Race. Two -Lectures in the Collection of Popular Scientific Lectures, edited by -Virchow and Holtzendorff. Berlin, 1868. 2nd Edition, 1870.) - -26. _Thomas Huxley_, Evidences as to Man's Place in Nature. Three Parts: -1. On the Natural History of the Man-like Apes. 2. On the Relations of -Man to the Lower Animals. 3. On some Fossil Remains of Man. London, -Williams & Norgate. - -27. _Carl Vogt_, Vorlesungen über den Menschen, seine Stellung in der -Schöpfung und in der Geschichte der Erde. 2 Bände. Giessen, 1863. - -(Carl Vogt, Lectures on Man, his Place in Creation and in the History of -the Earth. 2 Vols. Giessen, 1863.) - -28. _Friedrich Rolle_, Der Mensch, seine Abstammung und Gesittung im -Lichte der Darwin'schen Lehre von der Art-Entstehung, und auf Grund der -neueren geologischen Entdeckungen dargestellt. Frankfurt-a-M., 1866. - -(Friedrich Rolle, Man, his Derivation and Civilization, in the Light of -Darwin's Theory of the Origin of Species, based on Recent Geological -Discoveries. Frankfort-a-M., 1866.) - -29. _Eduard Reich_, Die allgemeine Naturlehre des Menschen. Giessen, -1865. - -(Eduard Reich, The General Natural History of Man. Giessen, 1865.) - -30. _Charles Lyell_, The Antiquity of Man. London, Murray. - -31. _Bernhard Cotta_, Die Geologie der Gegenwart. Leipzig, 1866. - -(Bernhard Cotta, The Geology of the Present Day.) - -32. _Karl Zittel_, Aus der Urzeit. Bilder aus der Schöpfungsgeschichte. -München, 1871. - -(Karl Zittel, Primæval Times. Pictures from the History of Creation. -Munich, 1871.) - -33. _C. Radenhausen_, Isis. Der Mensch und die Welt. 4 Bände. Hamburg, -1863. 2 Auflage, 1871. - -(C. Radenhausen, Isis. Man and the Universe. 4 Vols. Hamburg, 1863. 2nd -Edition, 1871.) - -34. _August Schleicher_, Ueber der Bedeutung der Sprache für die -Naturgeschichte des Menschen. Weimar, 1865. - -(August Schleicher, On the Importance of Language to the Natural History -of Man. Weimar, 1865). - -35. _Wilhelm Bleek_, Ueber den Ursprung der Sprache. Herausgegeben mit -einem Vorwort von Ernst Haeckel. Weimar, 1868. - -(Wilhelm Bleek, On the Origin of Language. Edited and with a Preface by -Ernst Haeckel. Weimar, 1868.) - -36. _Alfred Russel Wallace_, The Malayan Archipelago. London, Macmillan. - -37. _Ernst Haeckel_, Ueber Arbeitstheilung in Natur- und Menschenleben. -Sammlung gemeinverständlicher wissenschaftlicher Vorträge, herausgegeben -von Virchow und Holtzendorff. 4 Serie. 1869. Heft 78. - -(Ernst Haeckel, On Differentiation in Nature and in Human Life. A -Collection of Popular Scientific Lectures, edited by Virchow and -Holtzendorff. 4th Series. 1869. No. 78.) - -38. _Hermann Helmholtz_, Populäre wissenschaftliche Vorträge. -Braunschweig, 1871. - -(Hermann Helmholtz, Popular Scientific Lectures. Brunswick, 1871.) - -39. _Alexander Humboldt_, Ansichten der Natur. Stuttgart, 1826. - -(Alexander Humboldt, Views of Nature. Stuttgart, 1826.) - -40. _Moritz Wagner_, Die Darwin'sche Theorie und das Migrationsgesetz -der Organismen. Leipzig, 1868. - -(Moritz Wagner, Darwin's Theory and the Law of the Migration of -Organisms. Leipzig, 1868.) - -41. _Rudolf Virchow_, Vier Reden über Leben und Kranksein. Berlin, 1862. - -(Rudolf Virchow, Four Discourses on Life and Disease. Berlin, 1862.) - -42. _Friedrich Müller_, Ethnographie (Reise der österreichischen -Fregatte Novara. Anthropologischer Theil. 3 Abtheilung). Wien, 1868. - -(Friedrich Müller, Ethnography (Voyage of the Austrian Frigate _Novara_. -Anthropological Part. 3rd Part). Vienna, 1868.) - -43. _Ludwig Büchner_, Die Stellung des Menschen in der Natur, in -Vergangenheit, Gegenwart und Zukunft. Leipzig, 1870. - -(Ludwig Büchner, Man's Place in Nature in the Past, the Present, and the -Future. Leipzig, 1870.) - -44. _John Lubbock_, Prehistoric Times. London, 1867. - -45. _Herbert Spencer_, A System of Philosophy. (1. First Principles. 2. -Principles of Biology. 3. Principles of Psychology, etc.) London, 1867. -2nd Edition. - -46. _Wilhelm Wundt_, Vorlesungen über die Menschen- und Thierseele. -Leipzig, 1863. - -(Wilhelm Wundt, Lectures on the Human and Animal Soul. Leipzig, 1863.) - -47. _Fritz Ratzel_, Sein und Werden der organischen Welt. Eine populäre -Schöpfungsgeschichte. Leipzig, 1869. - -(Fritz Ratzel, Nature and Origin of the Organic World. A Popular History -of Creation. Leipzig, 1869.) - -48. _Charles Darwin_, The Descent of Man, and Selection in Relation to -Sex. 2 Vols. London, 1871. - - - - -APPENDIX. - -EXPLANATION OF THE PLATES. - - - PLATE FACING TITLE-PAGE. - -_Developmental History of a Calcareous Sponge_ (Olynthus). Compare vol. -ii. p. 140. The egg of the Olynthus (Fig. 9), which represents the -common ancestral form of all Calcareous Sponges, is a simple cell (Fig. -1). From this there arises, by repeated division (Fig. 2), a globular, -mulberry-like heap of numerous equi-formal cells (Morula, Fig. 3; vol. -ii. p. 125.) As the result of the change of these cells into an outer -series of clear ciliated cells (Exoderm) and an inner series of dark, -non-ciliated cells (Entoderm), the ciliated larva, or Planula, makes its -appearance. This is oval in shape, and forms a cavity in its centre -(gastric cavity, or primitive stomach, Fig. 6 _g_, with an opening -(mouth-opening, or primitive mouth, Fig. 6 _o_); the wall of the gastric -cavity consists of two layers of cells, or germ-layers, the outer -ciliated Exoderm (_e_) and the inner non-ciliated Entoderm (_i_). Thus -arises the exceedingly important stomach-larva, or Gastrula, which -reappears in the most different tribes of animals as a common larval -form (Fig. 5, seen from the surface; Fig. 6, in long section. Compare, -vol. ii. pp. 126 and 281). After the Gastrula has swum about for some -time in the sea, it fastens itself securely to the sea-bottom, loses its -outer vibratile processes, or cilia, and changes into the Ascula (Fig. -7, seen from the surface; Fig. 8, in long section; letters as in Fig. -6). This Ascula is the recapitulative form, according to the biogenetic -fundamental law, the common ancestor of all Zoophytes, namely, the -Protascus (vol. ii. pp. 129, 133). By the development of pores in the -wall of the stomach and of three-rayed calcareous spicules, the Ascula -changes into the Olynthus (Fig. 9.) In Fig. 9 a piece is cut out from -the stomach-wall of the Olynthus in order to show the inside of the -stomachal cavity, and the eggs which are forming on the surface (_g_). -From the Olynthus the most various forms of Calcareous Sponges can -develop. One of the most remarkable is the Ascometra (Fig. 10), a stock -or colony from which different species, and in fact different generic -forms, grow (on the left Olynthus, in the middle Nardorus, on the right -Soleniscus, etc., etc.). Further details as to these most interesting -forms, and their high importance for the Theory of Descent, may be found -in my "Monograph of the Calcareous Sponges" (1872), especially in the -first volume. (Compare vol. ii. pp. 160, 167). - - - PLATE I. (_Between pages 184 and 185, Vol. I._) - -_History of the Life of the most Simple Organism_, a Moneron (Protomyxa -aurantiaca). Compare vol. i. p. 184, and vol. ii. p. 53. The plate is a -smaller copy of the drawing in my "Monographie der Moneren" (Biologische -Studien, 1 Heft, 1870; Taf. 1), of the developmental history of the -Protomyxa aurantiaca; I have there also given a detailed description of -this remarkable Moneron (pp. 11-30). I discovered this most simple -organism in January, 1867, during a stay in Lanzarote, one of the Canary -Islands; and moreover I found it either adhering to, or creeping about -on the white calcareous shells of a small Cephalopod (vol. ii. p. 162), -the Spirula Peronii, which float there in masses on the surface of the -ocean, or are thrown up on the shore. The Protomyxa aurantiaca is -distinguished from the other Monera by the beautiful and bright -orange-red colour of its perfectly simple body, which consists merely of -primæval slime, or protoplasm. The fully developed Moneron is -represented in Figs. 11 and 12, very much enlarged. When it is hungry -(Fig. 11), there radiate from the surface of the globular corpuscule of -plasm, quantities of tree-shaped, branching and mobile threads -(pseudo-feet, or pseudopodia), which do not become retiformly -connected. When, however, the Moneron eats (Fig. 12), the mucous threads -become variously connected, form net-works and enclose the extraneous -corpuscule which serves as food, which the threads afterwards draw into -the interior of the Protomyxa. Thus in Fig. 12 (above on the right), a -silicious and ciliated Whip-swimmer (Peridinium, vol. ii. pp. 51, 57), -has just been caught by the extended mucous filaments, and has been -drawn into the interior of the mucous globule, in which there already -are several half digested silicious infusoria (Tintinoida), and Diatomeæ -(Isthmia). Now, when the Protomyxa has eaten and grown sufficiently, it -draws in all its mucous filaments (Fig. 15), and contracts into the form -of a globule (Fig. 16 and Fig. 1). In this state of repose the globule -secretes a simple gelatinous covering (Fig. 2), and after a time -subdivides into a large number of small mucous globules (Fig. 3). These -soon commence to move, become pear-shaped (Fig. 4), break through the -common covering (Fig. 5), and then swim about freely in the ocean by -means of a delicate whip-shaped process, like the Flagellata (vol. ii. -p. 57, Fig. 11). When they meet a Spirula shell, or any other suitable -object, they adhere to it, draw in their whip, and creep slowly about on -it by means of form-changing processes (Figs. 6, 7, 8), like Protamoebæ -(vol. i. p. 186, vol. ii. p. 52). These small mucous corpuscules take -food (Figs. 9, 10), and attain their full grown form (Figs. 11, 12), -either by simple growth or by several of them fusing to form a larger -protoplasmic mass (Plasmodium, Figs. 13, 14). - - - PLATES II. AND III. (_Between pages 294 and 295, Vol. I._) - -_Germs or Embryos of four different Vertebrate Animals_, namely, -Tortoise (_A_ and _E_), Hen (_B_ and _F_), Dog (_C_ and _G_), and Man -(_D_ and _H_). Figs. _A_, _D_, an early stage of development; Figs. _E_, -_H_, a later stage. All the eight embryos are represented as seen from -the right side, the curved back turned to the left. Figs. _A_ and _B_ -are seven times enlarged, Figs. _C_ and _D_ five times, Figs. _E_ and -_H_ four times. Plate II. exhibits the very close blood relationship -between birds and reptiles; Plate III. that between man and the other -mammals. - - - PLATE IV. (_Between pages 34 and 35, Vol. II._) - -_The Hand, or Fore Foot, of nine different Mammals._ This plate is -intended to show the importance of Comparative Anatomy to Phylogeny, in -as much as it proves how the internal skeleton of the limbs is -continually preserved by _inheritance_, although the external form is -extremely changed by _adaptation_. The bones of the skeleton of the hand -are drawn in white lines on the brown flesh and skin which surrounds -them. All the nine hands are represented in the same position, namely -the wrist (where the arm would be joined to it) is placed above, whilst -the ends of the fingers or toes are turned downwards. The thumb, or the -first (large) fore-toe is on the left in every figure; the little -finger, or fifth toe is to the right at the edge of the hand. Each hand -consists of three parts, namely (i.) the _wrist_ (carpus), composed of -two cross rows of short bones (at the upper side of the hand); (ii.) the -_mid-hand_ (metacarpus), composed of five long and strong bones (marked -in the centre of the hand by the numbers 1-5); and (iii.) the five -_fingers_, or _fore toes_ (digiti), every one of which again consists of -several (mostly from two to three), _toe-pieces_, or _phalanges_. The -hand of _man_ (Fig. 1), in regard to its entire formation, stands -midway between that of the two large human apes, namely, that of the -_gorilla_ (Fig. 2), and that of the _orang_ (Fig. 3). The fore paw of -the _dog_ (Fig. 4), is more different, and the hand or breast fin of the -_seal_ (Fig. 5) still more so. The adaptation of the hand to the -movement of swimming, and its transformation into a fin for steering, is -still more complete in the _dolphin_ (Ziphius, Fig. 6). The extended -fingers and bones of the central hand here have remained short and -strong in the swimming membrane, but they have become extremely long and -thin in the _bat_ (Fig. 7), where the hand has developed into a wing. -The extreme opposite of the latter formation is the hand of the _mole_ -(Fig. 8), which has acquired a powerful spade-like form for digging, -with fingers which have become extremely short and thick. What is far -more like the human hand than these latter forms, is the fore paw of the -lowest and most imperfect of all mammals, the Australian _beaked animal_ -(Ornithorhynchus, Fig. 9), which in its whole structure stands nearer to -the common, extinct, primary form of mammalia, than any known species. -Hence man differs less in the formation of the hand from this common -primary form than from the bat, mole, dolphin, seal, and many other -mammals. - - - PLATE V. (_Between pages 84 and 85, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Vegetable Kingdom_, -representing the hypothesis of the common derivation of all plants, and -the historical development of the different groups of plants during the -palæontological periods of the earth's history. The horizontal lines -denote the different smaller and larger periods of the organic history -of the earth (which are spoken of in vol. ii. p. 14), and during which -the strata containing fossils were deposited. The vertical lines -separate the different main-classes and classes of the vegetable kingdom -from one another. The arboriform and branching lines indicate, in an -approximate manner, by their greater or less number and thickness, the -greater or less degree of development, differentiation, and perfecting -which each class probably attained in each geological period. (Compare -vol. ii. pp. 82, 83.) - - - PLATE VI. (_Between pages 130 and 131, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Animal Kingdom_, -representing the _historical growth of the six animal tribes_ during the -palæontological periods of the organic history of the earth. The -horizontal lines _g h_, _i k_, _l m_, and _n o_ divide the five large -periods of the organic history of the earth one from another. The field -_g a b h_ comprises the archilithic, the field _i g h k_, the -palæolithic, the field _l i k m_ the mesolithic, and the field _n l o m_ -the cenolithic period. The short, anthropolithic period is indicated -by the line _n o_. (Compare vol. ii. p. 14.) The height of the separate -fields corresponds with the relative length of the periods indicated by -them, as they may approximately be estimated from the relative thickness -of the neptunic strata deposited between them. (Compare vol. ii. p. 22.) -The archilithic and primordial period alone, during which the -Laurentian, Cambrian, and Silurian strata were deposited, was probably -considerably longer than the four subsequent periods taken together. -(Compare vol. ii. pp. 10, 20.) In all probability the two tribes of -worms and Zoophytes attained their full development during the -mid-primordial period (in the Cambrian system); the star-fishes and -molluscs probably somewhat later (in the Silurian system); whereas the -articulata and vertebrata are still increasing in variety and -perfection. - - - PLATE VII. (_Between pages 146 and 147, Vol. II._) - -_Group of Animal-Trees_ (_Zoophytes, or Coelenterata_) _in the -Mediterranean_. On the upper half of the plate is a swarm of swimming -medusæ and ctenophora; on the lower half a few bunches of corals and -hydroid polyps adhering to the bottom of the sea. (Compare the system of -Zoophytes, vol. ii. p. 132, and on the opposite page their pedigree.) -Among the adhering Zoophytes at the bottom of the ocean there is, below -on the right hand, a large coral-colony (1), which is closely akin to -the red precious coral (Eucorallium), and like the latter belongs to the -group of corals with eight rays (Octocoralla Gorgonida); the single -individuals (or persons) of the branching stock have the form of a star -with eight rays, consisting of eight tentacles, which surround the -mouth. (Octocoralla, vol. ii. p. 143.) Directly below and in front of it -(quite below on the right), is a small bush of hydroid polyps (2), -belonging to the group of bell-polyps, or Campanulariæ (vol. ii. p. -146). A larger stock of hydroid polyps (3), belonging to the group of -tube-polyps, or Tubullariæ, rises, to the left, on the opposite side, -with its long thin branches. At its base is spread a stock of silicious -sponges (Halichondria) (4), with short, finger-shaped branches (vol. -ii. p. 139). Behind it, below on the left (5), is a very large marine -rose (Actinia), a single individual from the class of six-rayed corals -(Hexacoralla, vol. ii. p. 143). Its low, cylindrical body has a crown of -very numerous and large leaf-shaped tentacles. Below, in the centre of -the ground (6), is a sea-anemone (Cereanthus) from the group of -fourfold corals (Tetracoralla). Lastly, on a small hill on the bottom -of the sea, there rises, on the right above the corals (1) a cup-polyp -(Lucernaria), as the representative of the stalked-jellies. -(Podactinaria, or Calycozoa, vol. ii. p. 144.) Its cup-shaped, stalked -body (7) has eight globular clusters of small, knotted tentacles on its -rim. - -Among the _swimming Zoophytes_ which occupy the upper half of Plate -VII., the hydromedusæ are especially remarkable, on account of their -alteration of generation. (Compare vol. i. p. 206.) Directly above the -Lucernaria (7) floats a small tiara jelly (Oceania), whose bell-shaped -body has a process like a dome, the form of a papal tiara (8). From the -opening of the bell there hangs a wreath of very fine and long -tentacles. This Oceania is the offspring of a tube-polyp, resembling the -adhering Tubularia below on the left (3). Beside this latter, on the -left, swims a large but very delicate hair-jelly (Æquorea). Its -disc-shaped, slightly arched body is just drawing itself together, and -pressing water out of the cavity of the cup lying below (9). The -numerous, long, and fine hair-like tentacles which hang down from the -rim of the cup are drawn by the ejected water into a conical bunch, -which towards the centre turns upwards like a collar, and is thrown into -folds. Above, in the middle of the cavity of the cup, hangs the stomach, -the mouth of which is surrounded by four lobes. This Æquorea is derived -from a small bell-polyp, resembling the Campanularia (2). The small, -slightly arched cap-jelly (Eucope), swimming above in the centre (10), -is likewise derived from a similar bell-polyp. In these three last cases -(8, 9, 10), as in the majority of the hydromedusæ, the alternation of -generation consists in the freely swimming medusa (8, 9, 10), arising by -the formation of buds (therefore by non-sexual generation, vol. i. p. -192), from adhering hydroid polyps (2, 3). These latter, however, -originate out of the fructified eggs of the medusæ (therefore by sexual -generation, vol. i. p. 195). Hence the non-sexual, adhering generation -of polyps (I., III., V., etc.) regularly alternates with the sexual, -freely swimming generation of medusæ (II., IV., VI., etc.). This -alteration of generation can only be explained by the Theory of Descent. - -The same remark applies to a kindred form of propagation, which is still -more remarkable, and which I discovered in 1864, near Nice, in the -Elephant-jellies (Geryonida), and called _alloeogony_, or -_alloeogenesis_. In this case two completely distinct forms of medusa -are descended from one another; the larger and more highly developed -generation (11), Geryonia, or Carmarina, is six-rayed, with six foliated -sexual organs, and six very movable marginal filaments. From the centre -of its bell-shaped cup, like the tongue of a bell, hangs a long -proboscis, at the end of which is the opening of the mouth and stomach. -In the cavity of the stomach is a long, tongue-shaped bunch of buds -(which on Plate VII. (_n_) is extended from the mouth on the left like a -tongue). On this tongue, when the Geryonia is sexually ripe, there bud a -number of small medusæ. They are, however, not Geryoniæ, but belong to -an entirely distinct but very different form of medusa, namely, to the -genus Cunina, of the family of the _Æginida_. This Cunina (12) is very -differently constructed; it has a flat, semi-globular cup without -proboscis, consists in early life of six divisions, later of sixteen, -and has sixteen bag-shaped sexual organs, and sixteen short, stiff, and -strongly curved tentacles. A further explanation of this wonderful -alloeogenesis may be found in my "Contributions to the Natural History -of the Hydromedusæ." (_Leipzig_, Englemann, 1865), the first part of -which contains a monograph of the Elephant-jellies, or Geryonida, -illustrated by six copper-plates. - -Even more interesting and instructive than these remarkable relations -are the vital phenomena of the _Siphonophora_, whose wonderful -polymorphism I have frequently spoken of, and described in a popular -manner in my lecture on "Differentiation in Nature and Human Life."(37) -(Compare vol. i. p. 270, and vol. ii. p. 140.) An example of this is -given in Plate VII. in the drawing of the beautiful Physophora (13). -This swimming stock or colony of hydromedusæ is kept floating on the -surface of the sea by a small swimming bladder filled with air, which in -the drawing is seen rising above the surface of the water. Below it is a -column of four pairs of swimming bells, which eject water, and thereby -set the whole colony in motion. At the lower end of the column of -swimming bells is a crown-shaped wreath of curved spindle-shaped -_sensitive polyps_, which also serve as a covering, under the protection -of which the other individuals of the stock (the eating, catching, and -reproductive persons) are hidden. The _ontogenesis_ of the Siphonophora -(and especially of this Physophora), I first observed in Lanzerote, one -of the Canary Islands, in 1866, and described in my "History of the -Development of the Siphonophora," and added fourteen plates for its -explanation. (Utrecht, 1869). It is rich in interesting facts, which can -only be explained by the Theory of Descent. - -Another circumstance, which is also only explicable by the Theory of -Descent, is the remarkable change of generation in the higher medusæ, -the disc-jellies (Discomedusæ, vol. ii. p. 136), a representative of -which is given at the top of Plate VII., in the centre (rather in the -background), namely, a Pelagia (14). From the bottom of the bell-shaped -cup, which is strongly arched and the rim of which is neatly indented, -there hang four very long and strong arms. The non-sexual polyps, from -which these disc-jellies are derived, are exceedingly simple primæval -polyps, differing very little from the common fresh-water polyp (Hydra). -The alternation of generation in these Discomedusæ has also been -described in my lecture on Differentiation,(37) and there illustrated by -the Aurelia by way of example. - -Finally, the last class of Zoophytes, the group of comb-jellies -(Ctenophora, vol. ii. p. 142), has two representatives on Plate VII. To -the left, in the centre, between the Æquorea (9), the Physophora (13), -and the Cunina (12), is a long and thin band like a belt (15), winding -like a snake; this is the large and splendid _Venus' girdle_ of the -Mediterranean (Cestum), the colours of which are as varied as those of -the rainbow. The actual body of the animal, which lies in the centre of -the long belt, is very small, and constructed exactly like that of the -_melon-jelly_ (Cydippe), which floats above to the left (16). On the -latter are visible the eight characteristic fringed bands, or ciliated -combs, of the ctenophora, and also two long tentacles which extend right -across the page, and are fringed with still finer threads. - - - PLATES VIII. AND IX. (_Between pages 170 and 171, Vol. II._) - -_History of the Development of Star-fishes_ (_Echinoderma_, or -_Estrella_). The two plates exhibit their alternation of generation -(vol. ii. p. 168), with an example from each of the four classes of -Star-fishes. The sea-stars (Asterida) are represented by Uraster (_A_), -the sea-lilies (Crinoida) by Comatula (_B_), the sea-urchins (Echinida) -by Echinus (_C_), and finally, the sea-cucumbers (Holothuriæ) by Synapta -(_D_). (Compare vol. ii. pp. 166 and 176.) The successive stages of -development are marked by the numbers 1-6. - -Plate VIII. represents the individual development of the first and -non-sexual generation of Star-fishes, that is, of the _nurses_ (usually, -but erroneously, called larvæ). These nurses possess the form-value of a -simple, unsegmented worm-individual. Fig. 1 represents the egg of the -four Star-fishes; and it, in all essential points, agrees with that of -man and of other animals. (Compare vol. i. p. 297, Fig. 5.) As in man, -the protoplasm of the egg-cell (the yolk) is surrounded by a thick, -structureless membrane (zona pellucida), and contains a globular, -cell-kernel (nucleus), as clear as glass, which again encloses a -nucleolus. Out of the fertilised egg of the Star-fish (Fig. _A_ 1) there -develops in the first place, by the repeated sub-division of cells, a -globular mass of homogeneous cells (Fig. 6, vol. i. p. 299), and this -changes into a very simple nurse, which has almost the same shape as a -wooden shoe (Fig. _A_ 2-_D_ 2). The edge of the opening of the shoe is -bordered by a fringe of cilia, the ciliary movements of which keep the -microscopically small and transparent nurse swimming about freely in the -sea. This fringe of cilia is marked in Fig. _A_ 2-_A_ 4, on Plate VII., -by the narrow alternately light and dark seam. The nurse then, in the -first place, forms a perfectly simple intestinal canal for nutrition, -mouth (_o_), stomach (_m_) and anus (_a_). Later, the windings of the -fringe of cilia become more complicated, and there arise arm-like -processes (Fig. _A_ 3-_D_ 3). In sea-stars (_A_ 4) and sea-urchins (_C_ -4) these arm-like processes, which are fringed with cilia, afterwards -become very long. But in the case of sea-lilies (_B_ 3) and -sea-cucumbers (_D_ 4), instead of this, the fringe of cilia, which at -first, through winding in and out, forms one closed ring, changes -subsequently into a succession of separate ciliated girdles, one lying -behind the other. - -In the interior of this curious nurse there then develops, by a -non-sexual process of generation, namely, by the formation of internal -buds or germ-buds (round about the stomach), the second generation of -Star-fishes, which later on become sexually ripe. This second -generation, which is represented on Plate IX. in a fully developed -condition, exists originally as a stock or cormus of five worms, -connected at one end in the form of a star, as is most clearly seen in -the sea-stars, the most ancient and original form of the star-fishes. -The second generation, which grows at the expense of the first, -appropriates only the stomach and a small portion of the other organs of -the latter, but forms for itself a new mouth and anus. The fringe of -cilia, and the other parts of the body of the nurse, afterwards -disappear. The second generation (_A_ 5-_D_ 5), is at first smaller or -not much larger than the nurse, whereas, by growth, it afterwards -becomes more than a hundred times, or even a thousand times, as large. -If the ontogeny of the typical representatives of the four classes of -Star-fishes be compared, it is easily seen that the original kind of -development has been best preserved in sea-stars (_A_) and sea-urchins -(_C_) by inheritance, whereas in sea-lilies (_B_) and sea-cucumbers it -has been suppressed according to the laws of abbreviated inheritance -(vol. i. p. 212). - -Plate IX. shows the fully developed and sexually mature animals of the -second generation from the mouth side, which, in the natural position of -Star-fishes (when creeping at the bottom of the sea), in sea-stars (_A_ -6) and sea-urchins (_C_ 6), is below, in sea-lilies (_B_ 6) above, and -in sea-cucumbers (_D_ 6) in front. In the centre we perceive, in all the -four Star-fishes, the star-shaped, five-pointed opening of the mouth. In -sea-stars, from each arm there extend several rows of little sucking -feet, from the centre of the under-side of each arm to the end. In -sea-lilies (_B_ 6), each arm is split and feather-like from its base -upwards. In sea-urchins (_C_ 6) the five rows of sucking feet are -divided by broader fields of spines. In sea-cucumbers, lastly (_D_ 6), -on the worm-like body it is sometimes only the five rows of little feet, -sometimes only the feathery tentacles surrounding the mouth, from five -to fifteen (in this case ten), that are externally visible. - - - PLATES X. AND XI. (_Between pages 174 and 175, Vol. II._) - -_Historical Development of the Crab-fish_ (Crustacea).--The two plates -illustrate the development of the different Crustacea from the nauplius, -their common primæval form. On Plate XI. six Crustacea, from six -different orders, are represented in a fully developed state, whereas on -Plate X. the early nauplius stages are given. From the essential -agreement between the latter we may, on the ground of the fundamental -law of biogeny, with full assurance maintain the derivation of the -different Crustacea from a single, common primary form, a long since -extinct Nauplius, as was first shown by Fritz Müller in his excellent -work "Für Darwin."(16) - -Plate X. represents the _early nauplius stages_ from the ventral side, -so that the three pairs of legs, on the short, three-jointed trunk are -distinctly visible. The first of these pairs of legs is simple and -unsegmented, whereas the second and third pairs are forked. All three -pairs are furnished with stiff bristles, which, through the paddling -motion of the legs, serve as an apparatus for swimming. In the centre of -the body, the perfectly simple, straight intestinal canal is visible, -possessing a mouth in front, and an anal orifice behind. In front, above -the mouth, lies a simple, single eye. All the six forms of nauplius -entirely agree in all these essential characteristics of organization, -whereas the six fully developed forms of Crustacea belonging to them, -Plate XI., are extremely different in organisation. The differences of -the six nauplius forms are confined to quite subordinate and unessential -relations in regard to size of body, and the formation of the covering -of the skin. If they could be met with in this form in a sexually mature -condition, no zoologist would hesitate to regard them as six different -species of one genus. (Compare vol. ii. p. 175.) - -Plate XI. represents those fully developed and sexually mature forms of -Crustacea, as seen from the right side, which have ontogenetically -(hence also phylogenetically) developed out of the six kinds of -nauplius. Fig. _A c_ shows a freely swimming fresh-water crab (Limnetis -brachyurus) from the order of the Leaf-foot Crabs (Phyllopoda), slightly -enlarged. Of all the still living Crustacea, this order, which belongs -to the legion of Gill-foot Crabs (Branchiopoda), stands nearest to the -original, common primary form of nauplius. The Limnetis is enclosed in a -bivalved shell, like a mussel. Our drawing (which is copied from Grube) -represents the body of a female animal lying in the left shell; the -right half of the shell has been removed. In front, behind the eye, we -see the two feelers (antennæ), and behind them the twelve leaf-shaped -feet of the right side of the body, behind on the back (under the -shell), the eggs. Above, in front, the animal is fixed to the shell. - -Fig. _B c_ represents a common, freely swimming fresh-water crab -(Cyclops quadricornis) from the order of Oar-legged crabs (Eucopepoda), -highly magnified. In front, below the eye, we see the two feelers of the -right side, the foremost of which is longer than the hinder one. Behind -these are the gills, and then the four paddling legs of the right side. -Behind these are the two large egg-sacks, which, in this case, are -attached to the end of the hinder part of the body. - -Fig. _C c_ is a parasitic Oar-legged crab (Lernæocera esocina), from the -order of fish lice (Siphonostoma). These peculiar crabs, which were -formerly regarded as worms, have originated, by adaptation to a -parasitical life, out of freely swimming, Oar-legged crabs (Eucopepoda), -and belong to the same legion (Copepoda, vol. ii. p. 176). By adhering -to the gills on the skin of fish or other crabs, and feeding on the -juice of these creatures, they forfeited their eyes, legs, and other -organs, and developed into formless, inarticulated sacks, which, on a -mere external examination, we should never suppose to be animals. On the -ventral side only there exist, in the shape of short, pointed bristles, -the last remains of legs which have now almost entirely disappeared. Two -of these rudimentary pairs of legs (the third and fourth) are seen in -our drawing on the right. Above, on the head, we see thick, shapeless -appendages, the lower ones of which are split. In the centre of the body -is seen the intestinal canal, which is surrounded by a dark covering of -fat. At its posterior end is the ovary, and the cement-glands of the -female sexual apparatus. The two large egg-sacks hang externally (as in -the Cyclops, Fig. _B_). Our Lernæocera is represented in half profile, -and is copied from Claus. (Compare Claus, "Die Copepoden-Fauna von -Nizza. Ein Beitrag zur Characteristik der Formen und deren Abänderungen -im Sinne Darwins." Marburg, 1866). - -Fig. _D c_ represents a so-called "duck mussel" (Lepas anatifera), from -the order of the Barnacle crabs (Cirripedia). These crabs, upon which -Darwin has written a very careful monograph, are, like mussels, enclosed -in a bivalved, calcareous case, and hence were formerly (even by Cuvier) -universally regarded as a kind of mussel, or mollusc. It was only from a -knowledge of their ontogeny, and their early nauplius form (_D n_, Plate -VIII.), that their crustacean nature was proved. Our drawing shows a -"duck mussel" of the natural size, from the right side. The right half -of the bivalved shell has been removed, so that the body is seen lying -in the left half of the shell. From the rudimentary head of the Lepas -there issues a long, fleshy stalk (curving upwards in our drawing); by -means of it the Barnacle crab grows on rocks, ships, etc. On the ventral -side are six pairs of feet. Every foot is forked and divided into two -long, curved, or curled "tendrils" furnished with bristles. Above and -behind the last pair of feet projects the thin cylindrical tail. - -Fig. _E c_ represents a parasitic sack-crab (Sacculina purpurea) from -the order of Root-crabs (Rhizocephala). These parasites, by adaptation -to a parasitical life, have developed out of Barnacle crabs (Fig. _D -c_), much in the same way as the fish-lice (_C c_), out of the freely -swimming Oar-legged crabs (_B c_). However, the suppression, and the -subsequent degeneration, of all of the organs, has gone much further in -the present case than in most of the fish-lice. Out of the articulated -crab, possessing legs, intestine, and eye, and which in an early stage -as nauplius (_E n_, Plate VIII.), swam about freely, there has developed -a formless, unsegmented sack, a red sausage, which now only contains -sexual organs (eggs and sperm) and an intestinal rudiment. The legs and -the eye have completely disappeared. At the posterior end is the opening -of the genitals. From the mouth grows a thick bunch of numerous -tree-shaped and branching root-like fibres. These spread themselves out -(like the roots of a plant in the ground) in the soft hinder part of the -body of the hermit-crab (Pagurus), upon which the root-crab lives as a -parasite, and from which it draws its nourishment. Our drawing (_E c_), -a copy of Fritz Müller's, is slightly enlarged, and shows the whole of -the sausage-shaped sack-crab, with all its root-fibres, when drawn out -of the body upon which it lives. - -Fig. _F c_ is a _shrimp_ (Peneus Mülleri), from the order of _ten-foot_ -crabs (Decapoda), to which our river cray-fish, and its nearest -relative, the lobster, and the short-tailed shore-crabs also belong. -This order contains the largest and, gastronomically, the most important -crabs, and belongs, together with the mouth-legged and split-legged -crabs, to the legion of the stalk-eyed mailed crabs (Podophthalma). The -shrimp, as well as the river crab, has in front, on each side below the -eye, two long feelers (the first much shorter than the second), then -three jaws, and three jaw-feet, then five very long legs (the three -fore ones of which, in the Peneus, are furnished with nippers, and the -third of which is the longest). Finally, on the first five joints of the -hinder part of the body there are other five pairs of feet. This shrimp, -which is one of the most highly developed and perfect crabs, originates -(according to Fritz Müller's important discovery) out of a nauplius (_F -n_ Plate VIII.), and consequently proves that the higher Crustacea have -developed out of the same form as the lower ones, namely, the nauplius. -(Compare vol. ii. p. 175.) - - - PLATES XII. AND XIII. (_Between pages 200 and 201, Vol. II._) - -_Blood relationship between the Vertebrata and the Invertebrata._ -(Compare vol. ii. pp. 152 and 201.) It is definitely established by -Kowalewski's important discovery, which was confirmed by Kupffer, that -the ontogeny of the lowest vertebrate animal--the Lancelet, or -Amphioxus--agrees in all essential outlines completely with that of the -invertebrate Sea-squirts, or Ascidiæ, from the class of Sea-sacks, or -Tunicata. On our two plates, the ascidia is marked by _A_, the amphioxus -by _B_. Plate XIII. represents these two very different animal-forms in -a _fully developed_ state, as seen from the _left side_, the end of the -mouth above, the opposite end below. Hence, in both figures the dorsal -side is to the right, the ventral to the left. Both figures are slightly -magnified, and the internal organisation of the animals is distinctly -visible through the transparent skin. The full-grown ascidia (Fig. _A_ -6) grows at the bottom of the ocean, from whence it cannot move, and -clings to stones and other objects by means of peculiar roots (_w_) like -a plant. The full-grown amphioxus, on the other hand (Fig. _B_ 6), swims -about freely like a small fish. The letters on both figures indicate the -same parts: (_a_) orifice of the mouth; (_b_) orifice of the body, or -porus abdominalis; (_c_) dorsal rod, or chorda dorsalis; (_d_) -intestine; (_e_) ovary; (_f_) oviduct (same as the sperm-duct); (_g_) -spinal marrow; (_h_) heart; (_i_) blind-sac of the intestine; (_k_) -gill basket (respiratory cavity); (_l_) cavity of the body; (_m_) -muscles; (_n_) testicle (in the ascidia united with the ovary into a -hermaphrodite gland); (_o_) anus; (_p_) genital orifice; (_q_) -well-developed embryos in the body cavity of the ascidia; (_r_) rays of -the dorsal fin of the amphioxus; (_s_) tail-fin of the amphioxus; (_w_) -roots of the ascidia. - -Plate XII. shows the _Ontogenesis_, or the individual development of the -_Ascidia_ (_A_) and the _Amphioxus_ (_B_) in five different stages -(1-5). Fig. 1 is the egg, a simple cell like the egg of man and all -other animals (Fig. _A_ 1 the egg of the ascidia, Fig. _B_ 1 the egg of -the amphioxus). The actual cell-substance, or the protoplasm of the -egg-cell (_z_), the so-called yolk, is surrounded by a covering -(cell-membrane, or yolk-membrane), and encloses a globular cell-kernel, -or nucleus (_y_), the latter, again, contains a kernel-body, or -nucleolus (_x_); when the egg begins to develop, the egg-cell first -subdivides into two cells. By another sub-division there arise four -cells (Fig. _A_ 2, _B_ 2), and out of these, by repeated sub-division, -eight cells (vol. i. p. 190, Fig. 4 _C_, _D_). By fluid gathering in the -interior these form a globular bladder bounded by a layer of cells. On -one spot of its surface the bladder is turned inwards in the form of a -pocket (Fig. _A_ 4, _B_ 4). This depression is the beginning of the -intestine, the cavity (_d_ 1) of which opens externally by the -provisional larval-mouth (_d_ 4). The body-wall, which is at the same -time the stomach-wall, now consists of two layers of cells--the -germ-layers. The globular larva (Gastrula), now grows in length. Fig. -_A_ 5 represents the larva of the ascidia, Fig. _B_ 5 that of the -amphioxus, as seen from the left side in a somewhat more advanced state -of development. The orifice of the intestine (_d_ 1) has closed. The -dorsal side of the intestine (_d_ 2) is concave, the ventral side (_d_ -3) convex. Above the intestinal tube, on its dorsal side, the neural -tube, the beginning of the spinal marrow, is being formed, its cavity -still opens externally in front (_g_ 2). Between the spinal marrow and -the intestine has arisen the spinal rod, or chorda dorsalis (Notochord) -(_c_), the axis of the inner skeleton. In the larva of the ascidia this -rod (_c_) proceeds along the long rudder-tail, a larval organ, which is -cast off in later transformation. Yet there still exist some very small -ascidiæ (Appendicularia) which do not become transformed and attached, -but which through life swim about freely in the sea by means of their -rudder-tail. - -The ontogenetic facts which are systematically represented on Plate XII. -and which were first discovered in 1867, deserve the greatest attention, -and, indeed, cannot be too highly estimated. They fill up the gap which, -according to the opinion of older zoologists existed between the -vertebrate and the so-called "invertebrate" animals. This gap was -universally regarded as so important and so undeniable, that even -eminent zoologists, who were not disinclined to adopt the theory of -descent, saw in this gap one of the chief obstacles against it. Now that -the ontogeny of the amphioxus and the ascidia has set this obstacle -completely aside, we are for the first time enabled to trace the -pedigree of man beyond the amphioxus into the many-branching tribe of -"invertebrate" worms, from which all the other higher animal tribes have -originated. - -If our speculative philosophers, instead of occupying themselves with -castles in the air, were to give their thoughts for some years to the -facts represented on Plates XII. and XIII., as well as to those on -Plates II. and III., they would gain a foundation for true -philosophy--for the knowledge of the universe firmly based on -experience--which would be sure to influence all regions of thought. -These facts of ontogenesis are the indestructible foundations upon which -the monistic philosophy of future times will erect its imperishable -system. - - - PLATE XIV. (_Between pages 206 and 207, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Vertebrate Animal tribe_, -representing the hypothesis of the common derivation of all vertebrate -animals, and the historical development of their different classes -during the palæontological periods of the earth's history. (Compare -Chapter XX. vol. ii. p. 192.) The horizontal lines indicate the periods -(mentioned in vol. ii. p. 14) of the organic history of the earth during -which the deposition of the strata containing fossils took place. The -vertical lines separate the classes and sub-classes of vertebrata from -one another. The tree-shaped and branching lines, by their greater or -lesser number and thickness, indicate the approximate degree of -development, variety, and perfection, which each class probably attained -in each geological period. In those classes which, on account of the -soft nature of their bodies, could not leave any fossil remains (which -is especially the case with Prochordata, Acrania, Monorrhina, and -Dipneusta) the course of development is hypothetically suggested on the -ground of arguments derived from the three records of -creation--comparative anatomy, ontogeny, and palæontology. The most -important starting-points for the hypothetical completion of the -palæontological gaps are here, as in all cases, furnished by the -_fundamental law of biogeny_, which asserts the inner _causal-nexus -existing between ontogeny and phylogeny_. (Compare vol. i. p. 310, and -vol. ii. p. 200; also Plates VIII.-XIII.) In all cases we have to regard -the individual development (determined by the laws of Inheritance but -modified by the laws of Adaptation) as short and quick repetitions of -the palæontological development of the tribe. This proposition is the -"ceterum censeo" of our theory of development. - -The statements of the first appearance, or the period of the origin of -the individual classes and sub-classes of vertebrate animals (apart from -the hypothetical filling in mentioned just now), are taken as strictly -as possible from palæontological facts. It must, however, be observed, -that in reality the origin of most of the groups probably took place one -or two periods earlier than fossils now indicate. In this I agree with -Huxley's views; but on Plates V. and XIV. I have disregarded this -consideration in order not to go too far from palæontological facts. - -The numbers signify as follows (compare also Chapter XX. and vol. ii. -pp. 204, 206):--1. Animal Monera; 2. Animal Amoebæ; 3. Community of -Amoebæ (Synamoebæ); 4. Ciliated Infusoria without mouths; 5. Ciliated -Infusoria with mouths; 6. Gliding worms (Turbellaria); 7. Sea-sacks -(Tunicata); 8. Lancelet (Amphioxus); 9. Hag (Myxinoida); 10. Lamprey -(Petromyzontia); 11. Unknown forms of transition from single-nostriled -animals to primæval fishes; 12. Silurian primæval fish (Onchus, etc.); -13. Living primæval fishes (sharks, rays, Chimæræ); 14. Most ancient -(Silurian) enamelled fishes (Pteraspis); 15. Turtle fishes (Pamphracti); -16. Sturgeons (Sturiones); 17. Angular-scaled enamelled fishes -(Rhombiferi); 18. Bony pike (Lepidosteus); 19. Finny pike (Polypterus); -20. Hollow-boned fishes (Coeloscolopes); 21. Solid boned fishes -(Pycnoscolopes); 22. Bald pike (Amia); 23. Primæval boned fishes -(Thrissopida); 24. Bony fishes with air passage to the swimming bladder -(Physostomi); 25. Bony fishes without air passage to the swimming -bladder (Physoclisti); 26. Unknown forms of transition between primæval -fishes and amphibious fishes; 27. Ceratodus; 27_a_. Extinct Ceratodus -from the Trias; 27_b_. Living Australian Ceratodus; 28. African -amphibious fishes (Protopterus) and American amphibious fishes -(Lepidosiren); 29. Unknown forms of transition between primæval fishes -and amphibia; 30. Enamelled heads (Ganocephala); 31. Labyrinth toothed -(Labyrinthodonta); 32. Blind burrowers (Cæciliæ); 33. Gilled amphibia -(Sozobranchia); 34. Tailed amphibia (Sozura); 35. Frog amphibia (Anura); -36. Dichthacantha (Proterosaurus); 37. Unknown forms of transition -between Amphibia and Protamnia; 38. Protamnia (common primary form of -all Amnion animals); 39. Primary mammals (Promammalia); 40. Primæval -reptiles (Proreptilia); 41. (Thecodontia); 42. Primæval dragons -(Simosauria); 43. Serpent dragons (Plesiosauria); 44. Fish dragons -(Ichthyosauria); 45. Teleosauria (Amphicoela); 46. Steneosauria -(Opisthocoela); 47. Alligators and Crocodiles (Prosthocoela); 48. -Carnivorous Dinosauria (Harpagosauria); 49. Herbivorous Dinosauria -(Therosauria); 50. Mæstricht lizards (Mosasauria); 51. Common primary -form of Serpents (Ophidia); 52. Dog-toothed beaked lizards (Cynodontia); -53. Toothless beaked lizards (Cryptodontia); 54. Long-tailed flying -lizards (Rhamphorhynchi); 55. Short-tailed flying lizards -(Pterodactyli); 56. Land tortoises (Chersita); 57. Birds--reptiles -(Tocornithes), transition form between reptiles and birds; 58. Primæval -griffin (Archæopteryx); 59. Water beaked-animal (Ornithorhynchus); 60. -Land beaked-animal (Echidna); 61. Unknown forms of transition between -Cloacals and Marsupials; 62. Unknown forms of transition between -Marsupials and Placentals; 63. Tuft Placentals (Villiplacentalia); 64. -Girdle Placentals (Zonoplacentalia); 65. Disc Placentals -(Discoplacentalia); 66. Man (Homo pithecogenes, by Linnæus erroneously -called, Homo sapiens.) - - - PLATE XV. (_After page 369, Vol. II._) - -_Hypothetical Sketch of the Monophyletic Origin and the Diffusion of the -Twelve Species of Men from Lemuria over the earth._ The _hypothesis_ -here geographically sketched of course only claims an entirely -_provisional value_, as in the present imperfect state of our -anthropological knowledge it is simply intended to show how the -distribution of the human species, from a single primæval home, may be -_approximately_ indicated. The probable primæval home, or "Paradise," is -here assumed to be _Lemuria_, a tropical continent at present lying -below the level of the Indian Ocean, the former existence of which in -the tertiary period seems very probable from numerous facts in animal -and vegetable geography. (Compare vol. i. p. 361, and vol. ii. p. 315.) -But it is also very possible that the hypothetical "cradle of the human -race" lay further to the east (in Hindostan or Further India), or -further to the west (in eastern Africa). Future investigations, -especially in comparative anthropology and palæontology, will, it is to -be hoped, enable us to determine the probable position of the primæval -home of man more definitely than it is possible to do at present. - -If in opposition to our monophyletic hypothesis, the polyphyletic -hypothesis--which maintains the origin of the different human species -from several different species of anthropoid ape--be preferred and -adopted, then, from among the many possible hypotheses which arise, the -one deserving most confidence seems to be that which assumes a double -pithecoid root for the human race namely, an Asiatic and an African -root. For it is a very remarkable fact, that the African man-like apes -(gorilla and chimpanzee) are characterized by a distinctly long-headed, -or dolichocephalous, form of skull, like the human species peculiar to -Africa (Hottentots, Caffres, Negroes, Nubians). On the other hand, the -Asiatic man-like apes (especially the small and large orang), by their -distinct, short-headed, or brachycephalous, form of skull agree with -human species especially characteristic of Asia (Mongols and Malays). -Hence, one might be tempted to derive the latter (the Asiatic man-like -apes and primæval men) from a common form of brachycephalous ape, and -the former (the African man-like apes and primæval men) from a common -dolichocephalous form of ape. - -In any case, tropical Africa and southern Asia (and between them -Lemuria, which formerly connected them) are those portions of the earth -which deserve the first consideration in the discussion as to the -primæval home of the human race; America and Australia are, on the other -hand, entirely excluded from it. Even Europe (which is in fact but a -western peninsula of Asia) is scarcely of any importance in regard to -the "Paradise question." - -It is self-evident that the migrations of the different human species -from their primæval home, and their geographical distribution, could on -our Plate XV. be indicated only in a very general way, and in the -roughest lines. The numerous migrations of the many branches and tribes -in all directions, as well as the very important re-migrations, had to -be entirely disregarded. In order to make these latter in some degree -clear, our knowledge would, in the first place, need to be much more -complete, and secondly, we should have to make use of an atlas with a -number of plates showing the various migrations. Our Plate XV. claims no -more than to indicate, in a very general way, the approximate -geographical dispersion of the twelve human species as it existed in the -fifteenth century (before the general diffusion of the Indo-Germanic -race), and as it can be sketched out approximately, so as to harmonize -with our hypothesis of descent. The geographical barriers to diffusion -(mountains, deserts, rivers, straits, etc.), have not been taken into -consideration in this general sketch of migration, because, in earlier -periods of the earth's history, they were quite different in size and -form from what they are to-day. The gradual transmutation of catarrhine -apes into pithecoid men probably took place in the tertiary period in -the hypothetical Lemuria, and the boundaries and forms of the present -continents and oceans must then have been completely different from what -they are now. Moreover, the mighty influence of the ice period is of -great importance in the question of the migration and diffusion of the -human species, although it as yet cannot be more accurately defined in -detail. I here, therefore, as in my other hypotheses of development, -expressly guard myself against any dogmatic interpretation; they are -nothing but _first attempts_. - - - - -INDEX. - - A - - ABYSSINIANS, ii. 323, 330 - - Acalephæ, ii. 141 - - Acoelomi, ii. 148, 151 - - Acrania, ii. 196, 198, 200, 204 - - Acyttaria, ii. 51, 62 - - Adaptation, i. 90, 156, 219 - - ---- actual, i. 225, 231 - - ---- correlative, i. 241 - - ---- cumulative, i. 233 - - ---- direct, i. 225, 231 - - ---- divergent, i. 247 - - ---- indirect, i. 224, 227 - - ---- individual, i. 228 - - ---- irregular, i. 229 - - ---- monstrous, i. 229 - - ---- potential, i. 224, 227 - - ---- sexual, i. 230 - - ---- universal, i. 231 - - ---- unlimited, i. 249 - - Agassiz, Louis, i. 61 - - Agassiz's conception of the universe, i. 65 - - ---- essay on classification, i. 61 - - ---- history of creation, i. 63 - - ---- history of development, i. 64 - - ---- idea of species, i. 65 - - Albuminous bodies, i. 331 - - Algæ, ii. 81, 82, 83 - - Alluvial system, ii. 15 - - Altaians, ii. 309, 317 - - Alternation of generations, i. 206 - - Americans, ii. 309, 318 - - Amnion animals, ii. 204, 219 - - Amniota, ii. 204, 219 - - Amoebæ, ii. 53, 279 - - Amoeboidea, ii. 53 - - Amphibia, ii. 209, 216 - - Amphioxus, ii. 198, 285 - - Amphirrhina, ii. 203, 205 - - Anamnionata, ii. 204 - - Animal Plants, ii. 144 - - Angiospermæ, ii. 83, 111 - - Annelida, ii. 133, 149, 151 - - Anorgana, i. 5, 328 - - Anorganology, i. 6 - - Anthozoa, ii. 143 - - Anthropocentric conception of the universe, i. 38 - - Anthropoides, ii. 270, 275, 292 - - Anthropolithic period, ii. 15, 17 - - Anthropology, i. 7 - - Anthropomorphism, i. 18, 66 - - Ape-like men, ii. 293, 300 - - Apes, ii. 241, 268, 270 - - Arabians, ii. 323, 330 - - Arachnida, ii. 180, 182 - - Archelminthes, ii. 148 - - Archezoa, ii. 132, 134 - - Archigony, i. 183, 338 - - Archilithic period, ii. 8, 14 - - Arians, ii. 323, 331 - - Aristotle, i. 55, 76 - - Arthropoda, ii. 132 - - Articulata, ii. 119 - - Ascidia, ii. 152, 200 - - Ascones, ii. 141 - - Asterida, ii. 164, 166 - - Atavism, i. 207 - - Australians, ii. 308, 314 - - Autogeny, i. 339 - - - B - - BÄR, CARL ERNST, i. 109 - - ---- doctrine of filiation, i. 109 - - ---- theory of development, i. 294 - - ---- types of animals, i. 53; ii. 119 - - Basques, ii. 322 - - Bathybius, i. 184, 344; ii. 53 - - Batrachians, ii. 204 - - Bats, ii. 240, 261 - - Beaked mammals, ii. 233, 239 - - ---- reptiles, ii. 224, 226 - - Belief, i. 9; ii. 335 - - Berbers, ii. 323, 330 - - Biogenesis, fundamental law of, i. 309; ii. 33 - - Biology, i. 6 - - Birds, ii. 204, 226 - - Brachiopoda, ii. 157 - - Brain, bladder of, in man, i. 304 - - ---- development of, i. 303 - - Bruno Giordano, i. 22, 70 - - Bryozoa, ii. 150, 152 - - Buch, Leopold, i. 107 - - Büchner, Louis, i. 110 - - Buds, formation of, i. 192 - - - C - - CAFFRES, ii. 312, 333 - - Calcispongiæ, ii. 140, 144 - - Cambrian system, ii. 9, 15 - - Carbon, i. 330, 335 - - ---- theory of, i. 335 - - Carboniferous system, ii. 11, 15 - - Carus Victor, i. 110 - - Catallacta, i. 51, 59 - - Catarrhini, ii. 270, 272 - - Caucasians, ii. 309, 321 - - Causa finalis, i. 34, 75 - - Causal conception of the universe, i. 18, 74 - - Cells, i. 187, 346 - - ---- formation of, i. 347 - - ---- theory of, i. 346 - - Cell-kernel, i. 188 - - ---- membrane, i. 188 - - ---- substance, i. 186 - - Cænolithic period, ii. 14, 16 - - Cephalopoda, ii. 160, 162 - - Chamisso, Adalbert, i. 206 - - Change of climate, i. 363 - - Chelophora, ii. 240, 257 - - Chinese, ii. 309, 317 - - Chorology, i. 351 - - Cloacal animals, ii. 234, 239 - - Cochlides, ii. 159, 160 - - Coelenterata, ii. 136, 144 - - Coelomati, ii. 148, 151 - - Coniferæ, ii. 82, 110 - - Constructive forces, i. 90, 253, 337 - - Copernicus, i. 39 - - Corals, ii. 142, 144 - - Coreo-Japanese, ii. 309, 317 - - Cormophytes, ii. 80 - - Correlation of parts, i. 218 - - Cosmogeny, i. 321 - - Cosmological gas theory, i. 323 - - Crabs, ii. 174, 176 - - Craniota, ii. 198, 204 - - Creation, centres of, i. 352 - - ---- the, i. 8 - - Creator, the, i. 64, 70 - - Cretaceous system, ii. 12, 15 - - Crinoides, ii. 166, 171 - - Crocodiles, ii. 223, 224 - - Crustacea, ii. 173, 176 - - Cryptogamia, ii. 80, 82 - - Ctenophera, ii. 142, 144 - - Cultivated plants, i. 137 - - Curly-haired men, ii. 310, 333 - - Cuttles, ii. 160, 162 - - Cuvier, George, i. 50 - - Cuvier's dispute with Geoffroy, i. 88 - - ---- history of creation, i. 59 - - ---- palæontology, i. 54 - - ---- idea of species, i. 50 - - ---- theory of cataclysms, i. 58 - - ---- theory of revolutions, i. 58 - - ---- types of animals, i. 53; ii. 118 - - Cycadeæ, ii. 82, 110 - - Cyclostoma, ii. 202, 204 - - Cytod, i. 346 - - - D - - DARWIN, CHARLES, i. 131 - - Darwinism, i. 149 - - Darwin's life, i. 132 - - ---- travels, i. 132 - - ---- theory of corals, i. 133 - - ---- theory of selection, i. 150 - - ---- study of pigeons, i. 141 - - Darwin, Erasmus, i. 118 - - Deciduata, ii. 240, 255 - - Deduction, i. 85; ii. 357 - - Democritus, i. 22 - - Devonian system, ii. 11, 14 - - Diatomeæ, ii. 51, 60 - - Dicotylæ, ii. 82, 112 - - Didelphia, ii. 239 - - Differentiation, i. 270, 283 - - Diluvial system, ii. 15 - - Dipneusta, ii. 204, 212 - - Divergence, i. 270 - - Division of labour, i. 247 - - Domestic animals, i. 137 - - Dragons, ii. 225 - - Dravidas, ii. 308, 319 - - Dualistic conception of the universe, i. 20, 75 - - Dysteleology, i. 15; ii. 353 - - - E - - ECHINIDA, ii. 166, 171 - - Echinoderma, ii. 163, 166 - - Edentata, ii. 240, 254 - - Egg Animals, ii. 132, 134 - - Eggs, i. 190, 198 - - Egg of man, i. 190, 297; ii. 279 - - Egg, cleavage of the, i. 190, 299; ii. 280 - - Egyptians, ii. 323, 330 - - Elephants, ii. 257 - - Empiricism, i. 79; ii. 349 - - Eocene system, ii. 15, 16 - - Ethiopians, ii. 323, 330 - - Explanation of phenomena, i. 29 - - - F - - FERNS, ii. 82, 101 - - Fibrous plants, ii. 82 - - Final cause, i. 22 - - Fins, ii. 309, 317 - - Fishes, ii. 206, 208 - - Flagellata, ii. 51, 57 - - Flat-nosed apes, ii. 270, 272 - - Flat worms, ii. 148, 150 - - Flint cells, ii. 51, 60 - - Flowering plants, ii. 82, 108 - - Flower animals, ii. 143 - - Flowerless plants, ii. 80, 82 - - Flying animals, ii. 240, 261 - - Freke, i. 119 - - Fulatians, ii. 308, 320 - - Fungi, ii. 82 - - - G - - GANOID FISH, ii. 208, 210 - - Gastræa, ii. 127, 128, 281 - - Gastrula, ii. 126, 127 - - Gegenbaur, i. 312; ii. 179, 193 - - Gemmation, i. 192 - - Generation, i. 209 - - Genus, i. 41 - - Geocentric conception of the universe, i. 38 - - Geoffroy S. Hilaire, i. 86, 116 - - Germans, ii. 323, 331 - - Germ buds, formation of, i. 193 - - ---- cells, formation of, i. 194 - - Gibbon, ii. 270, 275 - - Gilled insects, ii. 174, 176 - - Gill-arches in man, i. 307 - - God, conception of, i. 70 - - Goethe, Wolfgang, i. 80 - - Goethe's conception of nature, i. 22 - - ---- discovery of mid-jaw bone, i. 84 - - ---- formative tendency i. 91, 253 - - ---- idea of God, i. 71 - - ---- investigations in nature, i. 81 - - ---- materialism, i. 23 - - ---- metamorphosis, i. 90 - - ---- metamorphosis of plants, i. 82 - - ---- philosophy of nature, i. 81 - - ---- theory of development, i. 92 - - ---- vertebræ of skull, i. 83 - - Genochoristus, i. 196 - - Gonochorism, i. 196 - - Gorilla, ii. 270 - - Grant, i. 119 - - Greeks, ii. 323, 331 - - Gregarinæ, ii. 133, 134 - - Gynmosperms, ii. 82, 109 - - - H - - HALISAURIA, ii. 204, 214 - - Hare-rabbit, i. 148, 275 - - Heliozoa, ii. 64 - - Herbert, i. 119 - - Heredity, i. 176 - - Hermaphrodites, i. 196 - - Herschel's cosmogeny, i. 321 - - Holothuriæ, ii. 166, 172 - - Hoofed animals, ii. 249, 252 - - Hooker, i. 119 - - Hottentots, ii. 311, 333 - - Human races, ii. 296, 305, 308 - - ---- soul, ii. 361 - - Huxley, i. 119, 145; ii. 268 - - Hybridism, i. 145, 210, 275 - - Hydromedusæ, ii. 143, 145 - - - I - - ICE PERIOD, i. 367; ii. 17 - - Indecidua, ii. 241, 249 - - Individual development, ii. 293 - - Indo-Chinese, ii. 309, 317 - - Indo-Germanic, ii. 323, 331 - - Induction, i. 85; ii. 357 - - Infusoria, ii. 132, 135 - - Inheritance, abridged, i. 212 - - Inheritance, acquired, i. 213 - - ---- adapted, i. 213 - - ---- amphigonous, i. 210 - - ---- conservative, i. 204 - - ---- constituted, i. 216 - - ---- contemporaneous, i. 217 - - ---- continuous, i. 205 - - ---- established, i. 216 - - ---- homochronous, i. 217 - - ---- interrupted, i. 205 - - ---- latent, i. 205 - - ---- mixed, i. 210 - - ---- progressive, i. 213 - - ---- sexual, i. 209 - - ---- simplified, i. 212 - - ---- uninterrupted, i. 205 - - ---- laws of, i. 204 - - Inophyta, ii. 82, 93 - - Insects, ii. 184 - - Insectivora, ii. 241, 259 - - Instinct, ii. 343 - - Invertebrata, ii. 118, 195 - - Iranians, ii. 323, 331 - - - J - - JAPANESE, ii. 309, 317 - - Jews, ii. 323, 330 - - Jura system, ii. 12, 14 - - - K - - KANT, IMMANUEL, i. 101, 321 - - Kant's Criticism of the faculty of judgment, i. 105 - - ---- mechanisms, i. 37, 102 - - ---- philosophy of nature, i. 101 - - ---- theory of descent, i. 103 - - ---- theory of development, i. 321 - - ---- theory of the formation of the universe, i. 101 - - Knowledge, à posteriori, i. 31; ii. 345 - - ---- à priori, i. 31; ii. 344 - - - L - - LABYRINTHULEÆ, ii. 51 - - Lacertilia, ii. 223 - - Lamarck, Jean, i. 111 - - Lamarck's anthropology, i. 115; ii. 264 - - ---- philosophy of nature, i. 112 - - ---- theory of descent, i. 113 - - Lamarckism, i. 150 - - Lamellibranchia, ii. 158, 160 - - Lancelet, ii. 198, 204, 285 - - Laplace's cosmogeny, i. 321 - - Laurentian system, ii. 9, 14 - - Lemuria, i. 361; ii. 326 - - Leonardo da Vinci, i. 56 - - Leptocardia, ii. 196, 204 - - Leucones, ii. 141 - - Linnæus, Charles, i. 39 - - Linnæus' classification of animals, ii. 118 - - ---- classification of plants, ii. 78 - - ---- designation of species, i. 41 - - ---- history of creation, i. 44 - - ---- system, i. 40 - - Lubbock, Sir John, ii. 298 - - Lyell, Charles, i. 126 - - Lyell's history of creation, i. 128 - - - M - - MAGYARS, ii. 309, 316 - - Malays, ii. 308, 315 - - Malthus' theory of population, i. 161 - - Mammalia, ii. 231, 239 - - Man-apes, ii. 271, 275, 292 - - Marsupials, ii. 236, 239, 290 - - Matagenesis, i. 206 - - Materialism, i. 35 - - Matter, i. 22; ii. 360 - - Mechanical causes, i. 34, 74 - - Mechanical conception of the universe, i. 17, 74 - - Mechanism, i. 37, 102 - - Mediterranese, ii. 308, 321 - - Medusæ, ii. 143, 144 - - Mesolithic period, ii. 14, 20 - - Metamorphosis of the earth's strata, ii. 25 - - Metamorphosis, i. 90 - - Migration, laws of, i. 373 - - ---- of organisms, i. 354 - - ---- of the human species, ii. 325 - - ---- theory of, i. 367 - - Mind, i. 22; ii. 360 - - ---- development of the, ii. 344, 360 - - Miocene period, ii. 15, 16 - - Miracles, i. 22 - - Molluscs, ii. 155, 160 - - Monera, i. 184, 343; ii. 52, 278 - - Mongols, ii. 308, 316 - - Monism, i. 34 - - Monistic conception of the universe, i. 20, 74 - - Monocottylæ, ii. 82, 112 - - Monoglottonic, ii. 327, 333 - - Monogony, i. 183 - - Monophylites, ii. 44 - - Monophyletic hypothesis of descent, ii. 44 - - Monorrhina, ii. 203, 204 - - Monosporogonia, i. 194 - - Monotrema, ii. 234, 239 - - Morphology, i. 21 - - Morula, ii. 125, 127 - - Moses' history of creation, i. 37 - - Moss animals, ii. 150, 152 - - Mosses, ii. 82, 97 - - Müller, Fritz, i. 49, 73; ii. 174 - - Müller, Johannes, i. 312; ii. 203 - - Muscinæ, ii. 82, 99 - - Mussels, ii. 159, 160 - - Myriapoda, ii. 182, 184 - - Myxomycetes, ii. 51, 60 - - - N - - NATURAL PHILOSOPHY, i. 78 - - Negroes, ii. 309, 313, 333 - - Nemathelminthes, ii. 149, 150 - - Newton, i. 25, 106 - - Non-amnionate, ii. 204, 209 - - Nubians, ii. 308, 320 - - - O - - OECOLOGY, ii. 354 - - Oken, Lorenz, i. 95 - - Oken's history of development, i. 293 - - ---- philosophy of nature, i. 96 - - ---- theory of infusoria, i. 97 - - ---- ---- protoplasm, i. 97 - - Olynthus, ii. 141 - - Ontogenesis, i. 293 - - Ontogeny, i. 10; ii. 33 - - Orang, ii. 271, 275 - - Organisms, i. 5, 328 - - Organs, i. 5 - - Origin of language, ii. 302, 327 - - Osseous fishes, ii. 208, 211 - - Ovularia, ii. 132, 134 - - - P - - PACHYCARDIA, ii. 201 - - Palæolithic period, ii. 11, 14 - - Palæontology, i. 54 - - Palissy, i. 56 - - Palm ferns, ii. 82, 110 - - Pander, Christian, i. 294 - - Papuans, ii. 310, 333 - - Paradise, ii. 325 - - Parallelism of development, i. 313 - - Parthenogenesis, i. 197 - - Pedigree of amphibia, ii. 209 - - ---- anamnia, ii. 209 - - ---- apes, ii. 270 - - Permean system, ii. 11, 14 - - Petrifactions, i. 54 - - Phanerogama, ii. 80, 82, 108 - - Philosophy, i. 79; ii. 350 - - Phylogeny, i. 10; ii. 33 - - Phylum, ii. 42 - - Physiology, i. 21 - - Pithecoid, theory, ii. 356 - - Placentalia, ii. 240, 244 - - Planula, ii. 126, 135, 281 - - Planæa, ii. 125, 127 - - Planæada, ii. 280 - - Plasma, i. 185, 330 - - Plasmogony, i. 339 - - Plastids, i. 347 - - Plastids, theory of, i. 347 - - Platyelminthes, ii. 148, 150 - - Platyrrhini, ii. 270, 272 - - Pleistocene system, ii. 15 - - Pliocene system, ii. 15, 16 - - Polar man, ii. 308, 317 - - Polyglottal, ii. 327, 333 - - Polynesians, ii. 308, 315 - - Polyphyletic theory of descent, ii. 45 - - Polyphylites, ii. 45, 303 - - Polyps, ii. 142 - - Polyp jellies, ii. 143, 144 - - Polysporogonia, i. 193 - - Population, number of, ii. 333 - - Porifera, ii. 139, 144 - - Primary mammals, ii. 239, 290 - - Primary period, ii. 11, 14 - - Primæval algæ, ii. 82, 84 - - ---- animals, ii. 131, 132 - - ---- history of man, ii. 298 - - ---- men, ii. 325 - - Primordial period, ii. 9, 14 - - Prochordata, ii. 278 - - Progenitors of man, ii. 279, 295 - - Progress, i. 277, 283 - - Promammalia, ii. 233, 239 - - Propagation, i. 183 - - ---- amphigonic, i. 195 - - ---- monogonic, i. 183 - - ---- non-sexual, i. 183 - - Propagation, sexual, i. 195 - - ---- virginal, i. 197 - - Protamnia, ii. 289, 295 - - Protamoebæ, ii. 52 - - Prothallophytes, ii. 80, 97 - - Prothallus plants, ii. 80, 97 - - Protista, ii. 48 - - Protophyta, ii. 82, 85 - - Protoplasma, i. 185, 330 - - Protoplasts, ii. 51, 53 - - Protozoa, ii. 121, 131, 132 - - Purpose in nature, i. 19 - - Purposelessness in nature, i. 20 - - - R - - RADIATA, ii. 120 - - Radiolaria, i. 333, 371; ii. 65 - - Rapacious animals, ii. 240, 260 - - Recent system, ii. 15 - - Reptiles, ii. 222, 224 - - Rhizopoda, ii. 51, 61 - - Ringed worms, ii. 149, 150 - - Rodentia, ii. 241, 257 - - Romans, ii. 323, 331 - - Rotatoria, ii. 149, 150 - - Rotifera, ii. 150, 152 - - Round worms, ii. 149, 150 - - Rudimentary eyes, i. 13 - - ---- gristle, i. 12 - - ---- legs, i. 14 - - ---- lungs, i. 289 - - ---- mammary glands, i. 290 - - ---- muscles, i. 12 - - ---- nictitating membrane, i. 13 - - ---- organs, i. 12 - - ---- pistils, i. 15 - - ---- stamens, i. 15 - - ---- tails, i. 289 - - ---- teeth, i. 12 - - ---- wings, i. 287 - - - S - - SACK WORMS, ii. 283, 295 - - Sauria, ii. 222 - - Schaaffhausen, i. 110 - - Schleicher, August, i. 108; ii. 301 - - Schleiden, J. M., i. 109 - - Science, i. 9; ii. 335 - - Scolecida, ii. 283, 295 - - Sea stars, ii. 164, 166 - - ---- cucumbers, ii. 166, 171 - - Sea dragons, ii. 204 - - ---- lilies, ii. 166, 177 - - ---- nettles, ii. 141, 144 - - ---- urchins, ii. 166, 171 - - Secondary period, ii. 14, 20 - - Selection æsthetic, i. 268 - - ---- artificial, i. 152, 170, 254 - - ---- homochromic, i. 263 - - ---- medical, i. 173 - - ---- military, i. 171 - - ---- musical, i. 267 - - ---- natural, i. 168, 255 - - ---- psychical, i. 269 - - ---- sexual, i. 265 - - ---- Spartan, i. 170 - - Self-division, i. 191 - - Semites, ii. 322, 330 - - Serpents, ii. 223 - - Sexes, separation of, i. 244 - - Sexual characters, i. 209, 265 - - Silurian system, ii. 8, 14 - - Slavonians, ii. 323, 331 - - Snails, ii. 159, 160 - - Soul, the, i. 71; ii. 343, 362 - - Species, i. 41, 273, 304, 311 - - Specific development, i. 311 - - Spencer, Herbert, i. 119; ii. 367 - - Sperma, i. 197 - - Spiders, i. 180, 182 - - Spirobranchia, ii. 157, 160 - - Sponges, ii. 139, 144 - - Spores, formation of, i. 194 - - Stemmed plants, ii. 280 - - Straight-haired men, ii. 309, 314 - - Struggle for life, i. 161, 252 - - Synamoeba, ii. 125, 280 - - Systematic development, i. 313 - - System of animals, ii. 132 - - ---- apes, ii. 270 - - ---- Arabians, ii. 330 - - ---- arachnida, ii. 182 - - ---- Arians, ii. 331 - - ---- arthropoda, ii. 132 - - ---- articulata, ii. 177, 183 - - ---- catarrhini, ii. 270 - - ---- coelenterata, ii. 144 - - ---- crustacea, ii. 176 - - ---- didelphia, ii. 239 - - ---- echinoderma, ii. 166 - - ---- Egyptians, ii. 330 - - ---- fishes, ii. 208 - - ---- formations, ii. 15 - - ---- Germans, ii. 331 - - ---- gilled Insects, ii. 177 - - ---- Græco-Romans, ii. 331 - - ---- Hamites, ii. 330 - - ---- hoofed animals, ii. 252 - - ---- human ancestors, ii. 295 - - ---- human races, ii. 308 - - ---- human species, ii. 308, 309 - - ---- Indians, ii. 331 - - ---- Indo-Germani, ii. 331 - - ---- insects, ii. 182 - - ---- mammalia, ii. 239 - - ---- mankind, ii. 295 - - ---- marsupials, ii. 239 - - ---- men and apes, ii. 271 - - ---- molluscs, ii. 160 - - ---- monodelphia, ii. 241 - - ---- organisms, ii. 74, 75 - - ---- placentalia, ii. 240 - - ---- plants, ii. 82 - - ---- platyrrhini, ii. 270 - - ---- protista, ii. 51 - - ---- reptiles, ii. 224 - - ---- Semites, ii. 330 - - ---- Slavonians, ii. 331 - - ---- spiders, ii. 182 - - ---- star fishes, ii. 167 - - ---- strata of the earth, ii. 15 - - ---- tracheata, ii. 182 - - ---- ungulata, ii. 252 - - ---- vegetable kingdom, ii. 83 - - ---- vertebrata, ii. 204 - - ---- worms, ii. 150 - - ---- zoophytes, ii. 144 - - - T - - TAIL OF MAN, i. 289, 308 - - Tangles, ii. 61, 82 - - Tartars, ii. 209, 317 - - Teleology, i. 100, 291 - - Teleostei, ii. 208, 211 - - Teleological conception of the universe, i. 20, 75 - - Tertiary period, ii. 14, 16 - - Thallophytes, ii. 80, 82 - - Thickness of the earth's crust, ii. 19 - - Thought, ii. 364 - - Thread plants, ii. 82, 93 - - Tocogony, i. 183 - - Tortoises, ii. 225 - - Tracheata, ii. 182 - - Transition forms, ii. 338 - - Transmutation, theory of, i. 4 - - Treviranus, i. 92 - - Trias system, ii. 12, 14 - - Tuft-haired men, ii. 307, 309 - - Tunicata, ii. 152, 200 - - Turbellaria, ii. 283 - - Turks, ii. 309, 316 - - - U - - UNGER, FRANZ, i. 109 - - Ungulata, ii. 249, 252 - - Unity in nature, i. 22, 338 - - Uralians, ii. 309, 317 - - - V - - Variability, i. 220 - - Variation, i. 219 - - Varieties, i. 276 - - Vertebrata, ii. 195, 205 - - Vital force, i. 22, 334 - - Vitalistic conception of the universe, i. 18 - - - W - - Wagner, Andreas, i. 138 - - Wagner, Moritz, i. 369 - - Wallace, Alfred, i. 135 - - Wallace's chorology, i. 361, 373 - - ---- theory of selection, i. 136 - - Well's theory of selection, i. 150 - - Whales, ii. 240, 251 - - Will, freedom of the, i. 113, 237, 364 - - Wolff's theory of development, i. 293 - - Woolly-haired men, ii. 307, 309 - - Worms, ii. 147, 150 - - - Z - - ZOOPHYTES, ii. 136, 144 - - - - -WORKS OF H. 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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 History of Creation, Vol. II (of 2) - Or the Development of the Earth and its Inhabitants by the - Action of Natural Causes - -Author: Ernst Haeckel - -Translator: E. Ray Lankester - -Release Date: August 14, 2012 [EBook #40473] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CREATION, VOL II *** - - - - -Produced by Adrian Mastronardi, Turgut Dincer, Jason Palmer -and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive) - - - - - - -</pre> - +<div>*** START OF THE PROJECT GUTENBERG EBOOK 40473 ***</div> <div class="box"> Transcriber’s note: @@ -1334,7 +1292,7 @@ Organic History of the Earth.</i></td> <td class="left"> </td> </tr> <tr> -<td class="center" rowspan="7">IV. <i>Tertiary<br />Group</i>,<br />or<br />(Cænozoic)<br />groups of strata.</td> +<td class="center" rowspan="7">IV. <i>Tertiary<br />Group</i>,<br />or<br />(Cænozoic)<br />groups of strata.</td> <td class="center" rowspan="7"><div class="figcenter" style="width: 10px;"><img src="images/cb100.png" width="10" height="100" alt= "{" /></div></td> <td class="center" rowspan="2">XII. Pliocene<br />(Late tertiary)</td> @@ -1457,7 +1415,7 @@ Organic History of the Earth.</i></td> <td class="left"> </td> </tr> <tr> -<td class="center" rowspan="7">II. <i>Primary<br />Group</i>,<br />or<br />Palæolithic<br />(Palæozoic)<br />groups of strata</td> +<td class="center" rowspan="7">II. <i>Primary<br />Group</i>,<br />or<br />Palæolithic<br />(Palæozoic)<br />groups of strata</td> <td class="center" rowspan="7"><div class="figcenter" style="width: 10px;"><img src="images/cb150.png" width="10" height="150" alt= "{" /></div></td> <td class="left" rowspan="2">VI. Permian</td> @@ -2777,15 +2735,15 @@ the next page, and their general natural history.</p> <td class="leftm padt1 smcap" colspan="2" rowspan="3">2. Protoplasts</td> <td class="left vertm padt1" rowspan="3">Amœboida</td> <td class="center padt1" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> -<td class="left padt1">1. Gymnamœbæ</td> +<td class="left padt1">1. Gymnamœbæ</td> <td class="left padt1">Amœba</td> </tr> <tr> -<td class="left">2. Leptamœbæ</td> +<td class="left">2. Leptamœbæ</td> <td class="left">Arcella</td> </tr> <tr> -<td class="left">3. Gregarinæ</td> +<td class="left">3. Gregarinæ</td> <td class="left">Monocystis</td> </tr> <tr> @@ -2807,13 +2765,13 @@ the next page, and their general natural history.</p> <td class="left vertm padt1">Catallacta</td> <td class="center"> </td> <td class="left padt1">1. Catallacta</td> -<td class="left padt1">Magosphæra</td> +<td class="left padt1">Magosphæra</td> </tr> <tr> <td class="left padt1 vertm smcap" colspan="2">5. Tram-weavers</td> -<td class="left padt1 vertm">Labyrinthuleæ</td> +<td class="left padt1 vertm">Labyrinthuleæ</td> <td class="center"> </td> -<td class="left padt1">1. Labyrinthuleæ</td> +<td class="left padt1">1. Labyrinthuleæ</td> <td class="left padt1">Labyrinthula</td> </tr> <tr> @@ -2835,19 +2793,19 @@ the next page, and their general natural history.</p> <td class="left padt1 vertm smcap" colspan="2" rowspan="4">7. Slime-moulds</td> <td class="left padt1 vertm" rowspan="4">Myxomycetes</td> <td class="center padt1" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb75.png" width="10" height="75" alt="{" /></div></td> -<td class="left padt1">1. Physareæ</td> -<td class="left padt1">Æthalium</td> +<td class="left padt1">1. Physareæ</td> +<td class="left padt1">Æthalium</td> </tr> <tr> -<td class="left">2. Stemoniteæ</td> +<td class="left">2. Stemoniteæ</td> <td class="left">Stemonitis</td> </tr> <tr> -<td class="left">3. Trichiaceæ</td> +<td class="left">3. Trichiaceæ</td> <td class="left">Arcyria</td> </tr> <tr> -<td class="left">4. Lycogaleæ</td> +<td class="left">4. Lycogaleæ</td> <td class="left">Reticularia</td> </tr> <tr> @@ -2867,17 +2825,17 @@ the next page, and their general natural history.</p> <td class="left padt1 vertm">II. Heliozoa</td> <td class="center"> </td> <td class="left padt1">1. Heliozoa</td> -<td class="left padt1">Actinosphærium</td> +<td class="left padt1">Actinosphærium</td> </tr> <tr> <td class="left vertm" rowspan="2">III. Radiolaria</td> <td class="center padt1" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left padt1">1. Monocyttaria</td> -<td class="left padt1">Cyrtidosphæra</td> +<td class="left padt1">Cyrtidosphæra</td> </tr> <tr> <td class="left">2. Polycyttaria</td> -<td class="left">Collosphæra</td> +<td class="left">Collosphæra</td> </tr> </table> @@ -3635,7 +3593,7 @@ designation of independent Protista.</p> <table class="pedigree" style="font-size: .85em;" summary="kingdoms" border="0"> <tr> -<td class="center">II.<br /><span class="oldtype">Vegetable Kingdom</span><br /><b>Plantæ</b></td> +<td class="center">II.<br /><span class="oldtype">Vegetable Kingdom</span><br /><b>Plantæ</b></td> <td class="center"> </td> <td class="center" colspan="4">III.<br /><span class="oldtype">Animal Kingdom</span><br /><b>Animalia</b></td> </tr> @@ -3664,7 +3622,7 @@ designation of independent Protista.</p> <td class="center"> </td> </tr> <tr> -<td class="center">Ferns<br /><i>Filicinæ</i><br />│<br /></td> +<td class="center">Ferns<br /><i>Filicinæ</i><br />│<br /></td> <td class="center"> </td> <td class="center">Star-fishes<br /><i>Echinoderma</i><br /><div class="figcenter" style="width: 75px;"><img src="images/cb75h.png" width="75" height="10" alt="-------------" /></div></td> <td class="center">│<br />│<br />│<br /></td> @@ -3688,7 +3646,7 @@ designation of independent Protista.</p> <td class="center">│<br /></td> </tr> <tr> -<td class="center">Mosses<br /><i>Muscinæ</i></td> +<td class="center">Mosses<br /><i>Muscinæ</i></td> <td class="center">Lichens<br /><i>Lichenes</i></td> <td class="center" colspan="4"><div class="figcenter" style="width: 400px;"><img src="images/cb400h.png" width="400" height="10" alt="--------------------------------------------------------------------" /></div></td> </tr> @@ -3712,7 +3670,7 @@ designation of independent Protista.</p> <td class="center">│<br />│<br /></td> </tr> <tr> -<td class="center"><i>Algæ</i></td> +<td class="center"><i>Algæ</i></td> <td class="center">Fungi<br /><i>Fungi</i></td> <td class="center" colspan="2"> </td> <td class="center">│<br />│<br /></td> @@ -3738,9 +3696,9 @@ designation of independent Protista.</p> <td class="center" colspan="2"><div class="figcenter" style="width: 150px;"><img src="images/cb150h.png" width="150" height="10" alt="------------------------" /></div></td> </tr> <tr> -<td class="center" colspan="2"><span class="oldtype">Primæval Plants</span><br /><b>Protophyta</b></td> -<td class="center" colspan="2"><span class="oldtype">Neutral<br />Primæval Creatures</span><br /><b>Protista</b></td> -<td class="center" colspan="2"><span class="oldtype">Primæval Animals</span><br /><b>Protozoa</b></td> +<td class="center" colspan="2"><span class="oldtype">Primæval Plants</span><br /><b>Protophyta</b></td> +<td class="center" colspan="2"><span class="oldtype">Neutral<br />Primæval Creatures</span><br /><b>Protista</b></td> +<td class="center" colspan="2"><span class="oldtype">Primæval Animals</span><br /><b>Protozoa</b></td> </tr> <tr> <td class="center" colspan="2"><div class="figcenter" style="width: 100px;"><img src="images/cb100h.png" width="100" height="10" alt="-----------------" /></div></td> @@ -3835,7 +3793,7 @@ designation of independent Protista.</p> <td class="center">│<br />│<br />│<br />│<br /></td> <td class="center"> </td> -<td class="center" colspan="6">Flint-cells<br /><i>Diatomæ</i><br /><div class="figcenter" style="width: 50px;"> +<td class="center" colspan="6">Flint-cells<br /><i>Diatomæ</i><br /><div class="figcenter" style="width: 50px;"> <img src="images/cb50h.png" alt="-------------" height="10" width="50" /></div></td> <td class="center" colspan="7"> </td> <td class="center" colspan="6"> </td> @@ -3894,19 +3852,19 @@ designation of independent Protista.</p> <td class="center">│<br /></td> </tr> <tr> -<td class="center" colspan="10"><span class="oldtype">Primæval Plants</span><br /><b>Protophyta</b></td> +<td class="center" colspan="10"><span class="oldtype">Primæval Plants</span><br /><b>Protophyta</b></td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="3"> </td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="3"> </td> <td class="center">│<br />│<br />│<br /></td> -<td class="center" colspan="7">Amœbæ<br />or<br />Protoplasta</td> +<td class="center" colspan="7">Amœbæ<br />or<br />Protoplasta</td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="2"> </td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="3"> </td> <td class="center">│<br />│<br />│<br /></td> -<td class="center" colspan="11"><span class="oldtype">Primæval<br />Animals</span><br /><b>Protozoa</b></td> +<td class="center" colspan="11"><span class="oldtype">Primæval<br />Animals</span><br /><b>Protozoa</b></td> </tr> <tr> <td class="center" colspan="3"> </td> @@ -4609,7 +4567,7 @@ exist at all.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center"><i>Gamopetalæ</i><br />(Flowers with corolla)</td> +<td class="center"><i>Gamopetalæ</i><br />(Flowers with corolla)</td> <td class="center" colspan="2"> </td> </tr> <tr> @@ -4619,7 +4577,7 @@ exist at all.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center"><i>Dialypetalæ</i><br />(Star-shaped flowers)</td> +<td class="center"><i>Dialypetalæ</i><br />(Star-shaped flowers)</td> <td class="center" colspan="2"> </td> </tr> <tr> @@ -4629,8 +4587,8 @@ exist at all.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center"><i>Monochlamydeæ</i><br />(Flowers with calyx)</td> -<td class="center"><span class="smcap">Monocotyledonæ</span><br />(One seed-lobed plants)</td> +<td class="center"><i>Monochlamydeæ</i><br />(Flowers with calyx)</td> +<td class="center"><span class="smcap">Monocotyledonæ</span><br />(One seed-lobed plants)</td> <td class="center"> </td> </tr> <tr> @@ -4641,7 +4599,7 @@ exist at all.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center"><span class="smcap">Dicotyledonæ</span><br />(Two seed-lobed plants)</td> +<td class="center"><span class="smcap">Dicotyledonæ</span><br />(Two seed-lobed plants)</td> <td class="center">│<br />│<br />│<br /></td> <td class="center"> </td> </tr> @@ -4658,10 +4616,10 @@ exist at all.</p> </tr> <tr> -<td class="center"><span class="smcap">Cycadeæ</span><br />(Palm-ferns)</td> -<td class="center"><span class="smcap">Coniferæ</span><br />(Pines)</td> -<td class="center"><span class="smcap">Gnetaceæ</span></td> -<td class="center" colspan="2"><b>Angiospermæ</b><br />(Plants with enclosed seeds)</td> +<td class="center"><span class="smcap">Cycadeæ</span><br />(Palm-ferns)</td> +<td class="center"><span class="smcap">Coniferæ</span><br />(Pines)</td> +<td class="center"><span class="smcap">Gnetaceæ</span></td> +<td class="center" colspan="2"><b>Angiospermæ</b><br />(Plants with enclosed seeds)</td> <td class="center"> </td> </tr> <tr> @@ -4679,18 +4637,18 @@ exist at all.</p> </tr> <tr> -<td class="center padr6" colspan="5"><b>Gymnospermæ</b><br />(Plants with naked seeds)</td> +<td class="center padr6" colspan="5"><b>Gymnospermæ</b><br />(Plants with naked seeds)</td> <td class="center"> </td> </tr> <tr> -<td class="center"><i>Selagineæ</i><br />(Scaled-ferns)</td> -<td class="center"><i>Rhizocarpeæ</i><br />(Water-ferns)</td> +<td class="center"><i>Selagineæ</i><br />(Scaled-ferns)</td> +<td class="center"><i>Rhizocarpeæ</i><br />(Water-ferns)</td> <td class="center">│<br />│<br />│<br /></td> -<td class="center"><i>Phanerogamæ</i><br />Flowering plants</td> -<td class="center"><i>Pterideæ</i><br />(Frondose-ferns)</td> -<td class="center"><i>Calamariæ</i><br />(Shaft-ferns)</td> +<td class="center"><i>Phanerogamæ</i><br />Flowering plants</td> +<td class="center"><i>Pterideæ</i><br />(Frondose-ferns)</td> +<td class="center"><i>Calamariæ</i><br />(Shaft-ferns)</td> </tr> <tr> @@ -4711,13 +4669,13 @@ exist at all.</p> <tr> <td class="center"> </td> -<td class="center padr4" colspan="5"><b>Filicinæ</b><br />(Ferns)</td> +<td class="center padr4" colspan="5"><b>Filicinæ</b><br />(Ferns)</td> </tr> <tr> -<td class="center" colspan="2"><i>Frondosæ</i><br />(Leaf-mosses)</td> -<td class="center"><i>Sphagnaceæ</i><br />(Turf-mosses)</td> +<td class="center" colspan="2"><i>Frondosæ</i><br />(Leaf-mosses)</td> +<td class="center"><i>Sphagnaceæ</i><br />(Turf-mosses)</td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="2"> </td> </tr> @@ -4730,13 +4688,13 @@ exist at all.</p> <tr> <td class="center padl2" colspan="4"><div class="figcenter" style="width: 300px;"><img src="images/cb300h.png" width="300" height="10" alt="---------------------------------------------" /></div></td> -<td class="center"><span class="smcap">Characeæ</span><br />(Tangle-mosses)</td> +<td class="center"><span class="smcap">Characeæ</span><br />(Tangle-mosses)</td> <td class="center"> </td> </tr> <tr> -<td class="center" colspan="4"><i>Hepaticæ</i><br />(Liverworts)</td> +<td class="center" colspan="4"><i>Hepaticæ</i><br />(Liverworts)</td> <td class="center">│<br />│<br /></td> <td class="center"> </td> @@ -4754,15 +4712,15 @@ exist at all.</p> </tr> <tr> -<td class="center padl2" colspan="6"><b>Muscinæ</b><br />(Mosses)</td> +<td class="center padl2" colspan="6"><b>Muscinæ</b><br />(Mosses)</td> </tr> <tr> <td class="center"> </td> -<td class="center"><i>Florideæ</i><br />(Red Algæ)</td> -<td class="center"><i>Fucoideæ</i><br />(Brown Algæ)</td> -<td class="center"><i>Chlorophyceæ</i><br />(Green Algæ)</td> +<td class="center"><i>Florideæ</i><br />(Red Algæ)</td> +<td class="center"><i>Fucoideæ</i><br />(Brown Algæ)</td> +<td class="center"><i>Chlorophyceæ</i><br />(Green Algæ)</td> <td class="center"><i>Lichenes</i><br />(Lichens)</td> <td class="center"> </td> @@ -4785,7 +4743,7 @@ exist at all.</p> <tr> <td class="center"> </td> -<td class="center" colspan="3"><b>Algæ</b><br />(Tangles)</td> +<td class="center" colspan="3"><b>Algæ</b><br />(Tangles)</td> <td class="center"><b>Fungi Inophyta</b><br />(Thread-plants)</td> <td class="center"> </td> @@ -4807,7 +4765,7 @@ exist at all.</p> <tr> <td class="center" colspan="2"> </td> -<td class="center" colspan="3"><i>Protophyta</i> (Primæval Plants)</td> +<td class="center" colspan="3"><i>Protophyta</i> (Primæval Plants)</td> <td class="center"> </td> </tr> @@ -6318,13 +6276,13 @@ see also in the same place the Ascidian, Fig. <i>A</i> 4).</p> <tr> <td class="center padl1 padr1 "><i>Second Stage of Development.</i></td> <td class="center vertt padl1 padr1 bl"><b>2.</b><br /><b>Ovulum.</b></td> -<td class="center vertt padl1 padr1 bl"><b>2.</b><br /><b>Amœbæ.</b></td> +<td class="center vertt padl1 padr1 bl"><b>2.</b><br /><b>Amœbæ.</b></td> </tr> <tr> <td class="just vertt">A simple cell (a plastid containing a kernel.)</td> <td class="just vertt padl1 padr1 bl">Animal egg with kernel (a simple egg-cell).</td> -<td class="center vertt padl1 padr1 bl">Animal Amœbæ.</td> +<td class="center vertt padl1 padr1 bl">Animal Amœbæ.</td> </tr> <tr> @@ -6342,7 +6300,7 @@ see also in the same place the Ascidian, Fig. <i>A</i> 4).</p> <tr> <td class="just vertt padl1 padr1">A community (an aggregation of identical simple cells).</td> <td class="just vertt padl1 padr1 bl">Globular heap of homogeneous “cleavage spheres.”</td> -<td class="just vertt padl1 padr1 bl">An aggregation of Amœbæ.</td> +<td class="just vertt padl1 padr1 bl">An aggregation of Amœbæ.</td> </tr> <tr> @@ -6354,13 +6312,13 @@ see also in the same place the Ascidian, Fig. <i>A</i> 4).</p> <tr> <td class="center padl1 padr1"><i>Fourth Stage of Development.</i></td> <td class="center vertt padl1 padr1 bl"><b>4.</b><br /><b>Planula.</b><br />(<i>Ciliated larva</i>.)</td> -<td class="center vertt padl1 padr1 bl"><b>4.</b><br /><b>Planæa.</b></td> +<td class="center vertt padl1 padr1 bl"><b>4.</b><br /><b>Planæa.</b></td> </tr> <tr> <td class="just vertt padl1 padr1">A solid or bladder-shaped, globular, or oval body, <i>composed of two kinds of different cells:</i> externally ciliated, internally non-ciliated cells.</td> <td class="just vertt padl1 padr1 bl">Many-celled larva without mouth, composed of different cells.</td> -<td class="just vertt padl1 padr1 bl">Many-celled primæval animal without mouth, composed of two kinds of different cells.</td> +<td class="just vertt padl1 padr1 bl">Many-celled primæval animal without mouth, composed of two kinds of different cells.</td> </tr> <tr> @@ -6372,7 +6330,7 @@ see also in the same place the Ascidian, Fig. <i>A</i> 4).</p> <tr> <td class="center padl1 padr1"><i>Fifth Stage of Development.</i></td> <td class="center vertt padl1 padr1 bl"><b>5.</b><br /><b>Gastrula.</b><br />(<i>Larva with mouth.</i>)</td> -<td class="center vertt padl1 padr1 bl"><b>5.</b><br /><b>Gastræa.</b></td> +<td class="center vertt padl1 padr1 bl"><b>5.</b><br /><b>Gastræa.</b></td> </tr> <tr> @@ -6380,7 +6338,7 @@ see also in the same place the Ascidian, Fig. <i>A</i> 4).</p> Body wall composed of two layers</i>; an externally ciliated ectoderm (dermal layer), an internally non-ciliated entoderm (gastral layer).</td> <td class="just vertt padl1 padr1 bl">Many-celled with intestines and mouth; intestinal wall with two layers.</td> -<td class="just vertt padl1 padr1 bl">Many-celled primæval animal with intestine and mouth; intestinal wall with two layers. (Primary form of zoophytes and worms.)</td> +<td class="just vertt padl1 padr1 bl">Many-celled primæval animal with intestine and mouth; intestinal wall with two layers. (Primary form of zoophytes and worms.)</td> </tr> </table> @@ -6547,7 +6505,7 @@ the two classes of Planæads and Gastræads.</p> </tr> <tr> -<td class="center" rowspan="6">A.<br /><span class="oldtype">Primæval<br />Animals</span><br /><b>Protozoa</b></td> +<td class="center" rowspan="6">A.<br /><span class="oldtype">Primæval<br />Animals</span><br /><b>Protozoa</b></td> <td class="center" rowspan="6"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> <td class="center" rowspan="4">I. Egg-animals<br /><i>Ovularia</i></td> <td class="center padt1" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> @@ -6560,7 +6518,7 @@ the two classes of Planæads and Gastræads.</p> <td class="right">2.</td> <td class="left">Gregarines</td> <td class="right">2.</td> -<td class="left">Gregarinæ</td> +<td class="left">Gregarinæ</td> </tr> <tr> <td class="right">3.</td> @@ -6575,20 +6533,20 @@ the two classes of Planæads and Gastræads.</p> <td class="center" rowspan="2">II. Mulberry animals<br /><i>Ovularia</i></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb20.png" width="10" height="20" alt="{" /></div></td> <td class="right">4.</td> -<td class="left">Planæads</td> +<td class="left">Planæads</td> <td class="right">4.</td> -<td class="left">Planæadas</td> +<td class="left">Planæadas</td> </tr> <tr> <td class="right">5.</td> -<td class="left">Gastræads</td> +<td class="left">Gastræads</td> <td class="right">5.</td> -<td class="left">Gastræadas</td> +<td class="left">Gastræadas</td> </tr> <tr> <td class="center" rowspan="4">B.<br /><span class="oldtype">Animal<br />Plants</span><br /><b>Zoophyta</b></td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> -<td class="center padt05 padb05">III. Sponges<br /><i>Spongiæ</i></td> +<td class="center padt05 padb05">III. Sponges<br /><i>Spongiæ</i></td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb20.png" width="10" height="20" alt="{" /></div></td> <td class="rightm">6.</td> <td class="left vertm">Sponges</td> @@ -6596,7 +6554,7 @@ the two classes of Planæads and Gastræads.</p> <td class="left vertm">Porifera</td> </tr> <tr> -<td class="center" rowspan="3">IV. Sea-nettles<br /><i>Acalephæ</i></td> +<td class="center" rowspan="3">IV. Sea-nettles<br /><i>Acalephæ</i></td> <td class="center" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="right">7.</td> <td class="left">Corals</td> @@ -6607,7 +6565,7 @@ the two classes of Planæads and Gastræads.</p> <td class="right">8.</td> <td class="left">Hood-jellies</td> <td class="right">8.</td> -<td class="left">Hydromedusæ</td> +<td class="left">Hydromedusæ</td> </tr> <tr> <td class="right">9.</td> @@ -6742,7 +6700,7 @@ the two classes of Planæads and Gastræads.</p> <td class="right">25.</td> <td class="left">Sea-cucumbers</td> <td class="right">25.</td> -<td class="left">Holothuriæ</td> +<td class="left">Holothuriæ</td> </tr> <tr> <td colspan="8"> </td> @@ -6972,8 +6930,8 @@ the two classes of Planæads and Gastræads.</p> </tr> <tr> <td class="center"> </td> -<td class="center">Spongiæ</td> -<td class="center">Acalephæ</td> +<td class="center">Spongiæ</td> +<td class="center">Acalephæ</td> <td class="center"> </td> <td class="center" colspan="2">│<br /></td> <td class="center" colspan="3"> </td> @@ -7022,7 +6980,7 @@ the two classes of Planæads and Gastræads.</p> <td class="center"> </td> <td class="center padr2" colspan="2"> </td> <td class="center">│<br />│<br />│<br /></td> -<td class="center"><b>Protozoa</b><br />(<i>Primæval<br />animals</i>)</td> +<td class="center"><b>Protozoa</b><br />(<i>Primæval<br />animals</i>)</td> <td class="center" colspan="4"> </td> </tr> <tr> @@ -7033,7 +6991,7 @@ the two classes of Planæads and Gastræads.</p> <tr> <td class="center" colspan="3"> </td> -<td class="center"><b><span class="smcap">Gastræa</span></b></td> +<td class="center"><b><span class="smcap">Gastræa</span></b></td> <td class="center" colspan="5"> </td> </tr> <tr> @@ -7045,9 +7003,9 @@ the two classes of Planæads and Gastræads.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center"><b><span class="smcap">Planæa</span></b></td> +<td class="center"><b><span class="smcap">Planæa</span></b></td> <td class="center">│<br /></td> -<td class="center">Gregarinæ</td> +<td class="center">Gregarinæ</td> <td class="center" colspan="3"> </td> </tr> @@ -7062,7 +7020,7 @@ the two classes of Planæads and Gastræads.</p> <tr> <td class="center" colspan="3"> </td> -<td class="center"><b><span class="smcap">Synamœbæ</span></b></td> +<td class="center"><b><span class="smcap">Synamœbæ</span></b></td> <td class="center" colspan="2"><div class="figcenter" style="width: 150px;"><img src="images/cb150h.png" width="150" height="10" alt="------------------------" /></div></td> <td class="center" colspan="3"> </td> @@ -7088,7 +7046,7 @@ the two classes of Planæads and Gastræads.</p> <tr> <td class="center" colspan="3"> </td> -<td class="center padl2" colspan="2"><b><span class="smcap">Amœbæ</span></b></td> +<td class="center padl2" colspan="2"><b><span class="smcap">Amœbæ</span></b></td> <td class="center" colspan="4"> </td> </tr> <tr> @@ -7463,9 +7421,9 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> -<td class="center pad05" rowspan="8">I.<br /><span class="oldtype">Sponges</span><br /><b>Spongiæ</b><br />or<br /><b>Porifera</b></td> +<td class="center pad05" rowspan="8">I.<br /><span class="oldtype">Sponges</span><br /><b>Spongiæ</b><br />or<br /><b>Porifera</b></td> <td class="center" rowspan="8"><div class="figcenter" style="width: 10px;"><img src="images/cb125.png" width="10" height="125" alt="{" /></div></td> -<td class="center padl1 padr1" rowspan="2">I. Myxospongiæ<br /><i>Mucous Sponges</i></td> +<td class="center padl1 padr1" rowspan="2">I. Myxospongiæ<br /><i>Mucous Sponges</i></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt padt1">1.</td> <td class="left padt1">Archispongina</td> @@ -7478,7 +7436,7 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> -<td class="center" rowspan="3">II. Fibrospongiæ<br /><i>Fibrous Sponges</i></td> +<td class="center" rowspan="3">II. Fibrospongiæ<br /><i>Fibrous Sponges</i></td> <td class="center padb05" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">3.</td> <td class="left">Chalynthina</td> @@ -7496,7 +7454,7 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> -<td class="center padb1" rowspan="3">III. Calcispongiæ<br /><i>Calcareous Sponges</i></td> +<td class="center padb1" rowspan="3">III. Calcispongiæ<br /><i>Calcareous Sponges</i></td> <td class="center padb05" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">6.</td> <td class="left">Ascones</td> @@ -7537,7 +7495,7 @@ and eightfold have developed as two diverging branches.</p> <tr> <td class="rightt">12.</td> <td class="left">Madreporaria</td> -<td class="left bl padl05">Astræa</td> +<td class="left bl padl05">Astræa</td> </tr> <tr> <td class="rightt">13.</td> @@ -7563,16 +7521,16 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> -<td class="center" rowspan="10">III.<br /><span class="oldtype">Jelly-polyps</span><br />Hydromedusæ<br />or<br /><span class="oldtype">Hood-jellies</span><br />Medusa</td> +<td class="center" rowspan="10">III.<br /><span class="oldtype">Jelly-polyps</span><br />Hydromedusæ<br />or<br /><span class="oldtype">Hood-jellies</span><br />Medusa</td> <td class="center" rowspan="10"><div class="figcenter" style="width: 10px;"><img src="images/cb200.png" width="10" height="200" alt="{" /></div></td> -<td class="center">VII. Archydræ<br /><i>Primæval Polyps</i></td> +<td class="center">VII. Archydræ<br /><i>Primæval Polyps</i></td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30a.png" width="10" height="30" alt="{" /></div></td> <td class="rightm">17.</td> <td class="left vertm">Hydraria</td> <td class="left vertm bl padl05">Hydra</td> </tr> <tr> -<td class="center" rowspan="3">VIII. Leptomedusæ<br />Soft Jelly-fish</td> +<td class="center" rowspan="3">VIII. Leptomedusæ<br />Soft Jelly-fish</td> <td class="center padb05" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">18.</td> <td class="left">Vesiculata</td> @@ -7590,7 +7548,7 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> -<td class="center" rowspan="3">IX. Trachymedusæ<br /><i>Hard Jelly-fish</i></td> +<td class="center" rowspan="3">IX. Trachymedusæ<br /><i>Hard Jelly-fish</i></td> <td class="center padb05" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">21.</td> <td class="left">Marsiporchida</td> @@ -7604,7 +7562,7 @@ and eightfold have developed as two diverging branches.</p> <tr> <td class="rightt">23.</td> <td class="left">Elasmorchida</td> -<td class="left bl padb1 padl05">Charybdæ</td> +<td class="left bl padb1 padl05">Charybdæ</td> </tr> <tr> @@ -7615,15 +7573,15 @@ and eightfold have developed as two diverging branches.</p> <td class="left vertm bl padl05">Lucernaria</td> </tr> <tr> -<td class="center" rowspan="2">XI. Discomedusæ<br /><i>Disc-jellies</i></td> +<td class="center" rowspan="2">XI. Discomedusæ<br /><i>Disc-jellies</i></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb20.png" width="10" height="20" alt="{" /></div></td> <td class="rightt">25.</td> -<td class="left">Semæostomeæ</td> +<td class="left">Semæostomeæ</td> <td class="left bl padl05">Aurelia</td> </tr> <tr> <td class="rightt">26.</td> -<td class="left">Rhizostomeæ</td> +<td class="left">Rhizostomeæ</td> <td class="left bl padb1 padl05">Crambessa</td> </tr> @@ -7651,7 +7609,7 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> <td class="rightt">30.</td> -<td class="left">Tæniata</td> +<td class="left">Tæniata</td> <td class="left bl padl05">Cestum</td> </tr> </table> @@ -7668,15 +7626,15 @@ and eightfold have developed as two diverging branches.</p> <td colspan="2"> </td> <td class="center" colspan="2">Ctenophora</td> <td colspan="3"> </td> -<td class="center">Hydromedusæ</td> +<td class="center">Hydromedusæ</td> <td> </td> </tr> <tr> <td colspan="2"> </td> -<td class="center">Tæniata</td> +<td class="center">Tæniata</td> <td class="center">Lobata</td> <td colspan="3"> </td> -<td class="center">Rhizostomeæ</td> +<td class="center">Rhizostomeæ</td> <td> </td> </tr> <tr> @@ -7691,13 +7649,13 @@ and eightfold have developed as two diverging branches.</p> <td colspan="2"> </td> <td class="center" colspan="2"><span class="figcenter" style="width: 75px;"><img src="images/cb75h.png" width="75" height="10" alt="-------------" /></span><br />Saccata<br />Stenostoma</td> <td colspan="3"> </td> -<td class="center">Semæostomeæ<br />Discomedusæ</td> +<td class="center">Semæostomeæ<br />Discomedusæ</td> <td> </td> </tr> <tr> <td colspan="2"> </td> <td class="center" colspan="2">│<br /></td> -<td class="center">Trachymedusæ</td> +<td class="center">Trachymedusæ</td> <td colspan="2"> </td> <td class="center">│<br /></td> <td class="center">Siphonophora</td> @@ -7743,7 +7701,7 @@ and eightfold have developed as two diverging branches.</p> </tr> <tr> <td colspan="2"> </td> -<td class="center padl7" colspan="7"><span class="smcap">Leptomedusæ</span></td> +<td class="center padl7" colspan="7"><span class="smcap">Leptomedusæ</span></td> </tr> <tr> <td colspan="4"> </td> @@ -7778,14 +7736,14 @@ and eightfold have developed as two diverging branches.</p> <td colspan="2"> </td> </tr> <tr> -<td class="center" colspan="5">Spongiæ</td> +<td class="center" colspan="5">Spongiæ</td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td colspan="2"> </td> </tr> <tr> -<td class="center" colspan="3">Fibrospongiæ</td> -<td class="center" colspan="2">Calcispongiæ</td> +<td class="center" colspan="3">Fibrospongiæ</td> +<td class="center" colspan="2">Calcispongiæ</td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td colspan="2"> </td> @@ -7869,7 +7827,7 @@ and eightfold have developed as two diverging branches.</p> <td class="center" colspan="3">│<br /></td> </tr> <tr> -<td class="center padr2" colspan="5"><span class="figcenter" style="width: 250px;"><img src="images/cb250h.png" width="250" height="10" alt="------------------------------------------------" /></span><br />Archispongiæ</td> +<td class="center padr2" colspan="5"><span class="figcenter" style="width: 250px;"><img src="images/cb250h.png" width="250" height="10" alt="------------------------------------------------" /></span><br />Archispongiæ</td> <td class="center padr5" colspan="4"><span class="figcenter" style="width: 200px;"><img src="images/cb200h.png" width="200" height="10" alt="----------------------------------------" /></span><br />Hydroida</td> </tr> <tr> @@ -7894,7 +7852,7 @@ and eightfold have developed as two diverging branches.</p> <td class="center padr3" colspan="9">│<br /></td> </tr> <tr> -<td class="center padr3" colspan="9">Gastræa</td> +<td class="center padr3" colspan="9">Gastræa</td> </tr> </table> @@ -8291,7 +8249,7 @@ phylogenesis.</p> <tr> <td colspan="4"> </td> -<td class="center">Chætopoda</td> +<td class="center">Chætopoda</td> <td colspan="5"> </td> </tr> <tr> @@ -8400,7 +8358,7 @@ phylogenesis.</p> </tr> <tr> <td class="center"> </td> -<td class="center">Chætognatha</td> +<td class="center">Chætognatha</td> <td class="center padl4">│<br /></td> <td class="center"> </td> <td class="center padl3" colspan="2"><div class="figcenter" style="width: 75px;"><img src="images/cb75h.png" width="75" height="10" alt="-------------" /></div></td> @@ -8655,7 +8613,7 @@ phylogenesis.</p> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center padl6" colspan="3"><b>Gastræa</b></td> +<td class="center padl6" colspan="3"><b>Gastræa</b></td> <td class="center" colspan="4"> </td> </tr> @@ -9331,7 +9289,7 @@ to 26,800.</p> <td class="center"> </td> </tr> <tr> -<td class="center " colspan="5">Promollusca (Primæval Molluscs)<br />Molluscs with simple heart</td> +<td class="center " colspan="5">Promollusca (Primæval Molluscs)<br />Molluscs with simple heart</td> <td class="center"> </td> </tr> <tr> @@ -9347,7 +9305,7 @@ to 26,800.</p> <td class="center"> </td> </tr> <tr> -<td class="center " colspan="5">Gastræa</td> +<td class="center " colspan="5">Gastræa</td> <td class="center"> </td> </tr> @@ -9611,7 +9569,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="rightt">12.</td> <td class="left">Bladder Lilies<br />with stalks</td> <td class="rightt">12.</td> -<td class="left">Sphæronitida</td> +<td class="left">Sphæronitida</td> </tr> <tr> <td class="blankrow05"> </td> @@ -9653,7 +9611,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="blankrow05"> </td> </tr> <tr> -<td class="center" rowspan="5"><br />IV.<br /><span class="oldtype">Sea Cucumbers</span><br /><b>Holothuriæ</b></td> +<td class="center" rowspan="5"><br />IV.<br /><span class="oldtype">Sea Cucumbers</span><br /><b>Holothuriæ</b></td> <td class="center" rowspan="5"><div class="figcenter" style="width: 10px;"><img src="images/cb100.png" width="10" height="100" alt="{" /></div></td> <td class="center" rowspan="2">VIII.<br />Sea Cucumbers<br />with aquatic feet<br /><i>Eupodia</i></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> @@ -9698,19 +9656,19 @@ has developed into a common mouth for the whole cormus.</p> <tr> <td class="center"> </td> <td class="center" colspan="4"> </td> -<td class="center">Clypeastridæ</td> +<td class="center">Clypeastridæ</td> <td class="center"> </td> </tr> <tr> <td class="center"> </td> <td class="center" colspan="3"> </td> -<td class="center">Spatangidæ</td> +<td class="center">Spatangidæ</td> <td class="center">│<br /></td> <td class="center"> </td> </tr> <tr> <td class="center" colspan="3"> </td> -<td class="center">Dysasteridæ</td> +<td class="center">Dysasteridæ</td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td class="center"> </td> @@ -9727,7 +9685,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center">Synaptida</td> <td class="center">│<br />│<br /></td> <td class="center">│<br />│<br /></td> -<td class="center" colspan="2">Cassidulidæ<br /><b>Petalosticha</b></td> +<td class="center" colspan="2">Cassidulidæ<br /><b>Petalosticha</b></td> <td class="center"> </td> </tr> <tr> @@ -9743,7 +9701,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center">Liodermatida<br /><b>Apodia</b></td> <td class="center">│<br />│<br /></td> <td class="center padr3" colspan="3"><div class="figcenter" style="width: 150px;"><img src="images/cb150h2.png" width="150" height="10" alt="------------------------" /></div></td> -<td class="center">Echinonidæ</td> +<td class="center">Echinonidæ</td> </tr> <tr> <td class="center"> </td> @@ -9756,7 +9714,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center"> </td> <td class="center">│<br /></td> <td class="center">│<br /></td> -<td class="center" colspan="3">Galeritidæ</td> +<td class="center" colspan="3">Galeritidæ</td> <td class="center">│<br /></td> </tr> <tr> @@ -9765,7 +9723,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center">│<br /></td> <td class="center"> </td> <td class="center">│<br /></td> -<td class="center">Echinometridæ</td> +<td class="center">Echinometridæ</td> <td class="center">│<br /></td> </tr> <tr> @@ -9785,9 +9743,9 @@ has developed into a common mouth for the whole cormus.</p> </tr> <tr> <td class="center"> </td> -<td class="center" colspan="2">Dendrochirota<br /><b>Eupodia</b><br /><b>Holothuriæ</b></td> -<td class="center">Salenidæ</td> -<td class="center" colspan="3">Latistellæ</td> +<td class="center" colspan="2">Dendrochirota<br /><b>Eupodia</b><br /><b>Holothuriæ</b></td> +<td class="center">Salenidæ</td> +<td class="center" colspan="3">Latistellæ</td> </tr> <tr> <td class="center"> </td> @@ -9803,7 +9761,7 @@ has developed into a common mouth for the whole cormus.</p> <tr> <td class="center"> </td> <td class="center" colspan="2">│<br />│<br />│<br /></td> -<td class="center">Angustistellæ<br /><b>Desmosticha</b><br /><b>Autechinida</b></td> +<td class="center">Angustistellæ<br /><b>Desmosticha</b><br /><b>Autechinida</b></td> <td class="center" colspan="3"> </td> </tr> <tr> @@ -9811,21 +9769,21 @@ has developed into a common mouth for the whole cormus.</p> <td class="center" colspan="2">│<br /></td> <td class="center">│<br /></td> <td class="center"> </td> -<td class="center">Colocrinæ</td> +<td class="center">Colocrinæ</td> <td class="center"> </td> </tr> <tr> <td class="center">Phytastra</td> <td class="center" colspan="2">│<br /></td> <td class="center">│<br /></td> -<td class="center">Sphæronitidæ</td> +<td class="center">Sphæronitidæ</td> <td class="center">│<br /></td> <td class="center"> </td> </tr> <tr> <td class="center">│<br /></td> <td class="center" colspan="2">│<br /></td> -<td class="center">Eocidaridæ</td> +<td class="center">Eocidaridæ</td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td class="center">Eleutherocrina</td> @@ -9842,7 +9800,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center">Ophiastra<br /><b>Discogastra</b></td> <td class="center" colspan="2">│<br />│<br /></td> <td class="center">│<br />│<br /></td> -<td class="center">Agelacrinæ<br /><b>Cystidea</b></td> +<td class="center">Agelacrinæ<br /><b>Cystidea</b></td> <td class="center">│<br />│<br /></td> <td class="center">│<br />│<br /></td> </tr> @@ -9859,7 +9817,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center" colspan="2">│<br />│<br />│<br /></td> <td class="center">Melonitida<br />Palechinida<br /><b>Echinida</b></td> <td class="center">│<br />│<br />│<br /></td> -<td class="center">Phatnocrinæ<br /><b>Brahiata</b></td> +<td class="center">Phatnocrinæ<br /><b>Brahiata</b></td> <td class="center">│<br />│<br />│<br /></td> </tr> <tr> @@ -9917,7 +9875,7 @@ has developed into a common mouth for the whole cormus.</p> <td class="center"> </td> </tr> <tr> -<td class="center" colspan="6">Gastræa</td> +<td class="center" colspan="6">Gastræa</td> <td class="center"> </td> </tr> </table> @@ -10228,14 +10186,14 @@ the present day.</p> <td colspan="7"> </td> </tr> <tr> -<td class="center padt05 padb05 bt br bb" colspan="2"><i>Legions of the</i><br /><i>Crustaceæ.</i></td> -<td class="center padt05 padb05 bt br bb" colspan="2"><i>Orders of the</i><br /><i>Crustaceæ.</i></td> +<td class="center padt05 padb05 bt br bb" colspan="2"><i>Legions of the</i><br /><i>Crustaceæ.</i></td> +<td class="center padt05 padb05 bt br bb" colspan="2"><i>Orders of the</i><br /><i>Crustaceæ.</i></td> <td class="center padt05 padb05 bt br bb" colspan="2"><i>Systematic name</i><br /><i>of the Orders.</i></td> <td class="center padt05 padb05 bt bb"><i>Name of a</i><br /><i>Genus as an</i><br /><i>example.</i></td> </tr> <tr> <td class="center padt05 padb05 bb" colspan="7">I. <span class="smcap">Entomostraca</span>, <i>Lower Crustacea</i>, or Segmented Crabs (not passing through the -actual Zoëa form in youth).</td> +actual Zoëa form in youth).</td> </tr> <tr class="blankrow05"> <td colspan="7"> </td> @@ -10244,7 +10202,7 @@ actual Zoëa form in youth).</td> <td class="center" rowspan="5"><b>I. Branchiopoda</b><br />Gill-footed Crabs</td> <td class="center" rowspan="5"><div class="figcenter" style="width: 10px;"><img src="images/cb75.png" width="10" height="75" alt="{" /></div></td> <td class="right">1.</td> -<td class="left">Primæval Crabs</td> +<td class="left">Primæval Crabs</td> <td class="right">1.</td> <td class="left">Archicarida</td> <td class="left">Nauplius</td> @@ -10313,7 +10271,7 @@ actual Zoëa form in youth).</td> <td class="left">Fish Lice</td> <td class="right">9.</td> <td class="left">Siphonostoma</td> -<td class="left">Lernæocera</td> +<td class="left">Lernæocera</td> </tr> <tr> <td colspan="7"> </td> @@ -10350,7 +10308,7 @@ actual Zoëa form in youth).</td> <td colspan="7"> </td> </tr> <tr> -<td class="center padt05 padb05 bt bb" colspan="7">II. <span class="smcap">Malacostraca</span>, <i>Higher Crustacea</i>, or Mailed Crabs (passing through the Zoëa form +<td class="center padt05 padb05 bt bb" colspan="7">II. <span class="smcap">Malacostraca</span>, <i>Higher Crustacea</i>, or Mailed Crabs (passing through the Zoëa form in youth).</td> </tr> <tr class="blankrow05"> @@ -10360,10 +10318,10 @@ in youth).</td> <td class="center" rowspan="4"><b>V. Pœcilopoda</b><br />Oar-footed Crabs</td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> <td class="right">13.</td> -<td class="left">Zoëa Crabs</td> +<td class="left">Zoëa Crabs</td> <td class="right">13.</td> -<td class="left">Zoëpoda</td> -<td class="left">Zoëa</td> +<td class="left">Zoëpoda</td> +<td class="left">Zoëa</td> </tr> <tr> <td class="right">14.</td> @@ -10409,7 +10367,7 @@ in youth).</td> <td class="right">19.</td> <td class="left">Wizard Crabs</td> <td class="right">19.</td> -<td class="left">Læmodipoda</td> +<td class="left">Læmodipoda</td> <td class="left">Caprella</td> </tr> <tr> @@ -10441,7 +10399,7 @@ in youth).</td> <td class="center"> </td> <td class="center">│<br /></td> <td class="center" colspan="4"> </td> -<td class="center">Læmodipoda</td> +<td class="center">Læmodipoda</td> <td class="center">│<br /></td> <td class="center"> </td> </tr> @@ -10535,7 +10493,7 @@ in youth).</td> <tr> <td class="center"> </td> <td class="center" colspan="3"> </td> -<td class="center">Zoëpoda<br /><b>Malacostraca</b></td> +<td class="center">Zoëpoda<br /><b>Malacostraca</b></td> <td class="center" colspan="4"> </td> </tr> <tr> @@ -10571,12 +10529,12 @@ in youth).</td> <tr> <td class="center"> </td> <td class="center">│<br />│<br /></td> -<td class="center">Xiphosuræ</td> +<td class="center">Xiphosuræ</td> <td class="center"> </td> -<td class="center">Zoëa</td> +<td class="center">Zoëa</td> <td class="center">│<br />│<br /></td> <td class="center"> </td> -<td class="center">Cirripediæ<br /><b>Pectostraca</b></td> +<td class="center">Cirripediæ<br /><b>Pectostraca</b></td> <td class="center"> </td> </tr> <tr> @@ -10624,7 +10582,7 @@ in youth).</td> <tr> <td class="center"> </td> <td class="center" colspan="2">│<br /></td> -<td class="center">Nebaliæ</td> +<td class="center">Nebaliæ</td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td class="center"> </td> @@ -10681,7 +10639,7 @@ in youth).</td> <td class="center">│<br /></td> </tr> <tr> -<td class="center">Cladoceræ</td> +<td class="center">Cladoceræ</td> <td class="center" colspan="2">│<br /></td> <td class="center" >│<br /></td> <td class="center"> </td> @@ -10736,7 +10694,7 @@ in youth).</td> </tr> <tr> <td class="center"> </td> -<td class="center padl2" colspan="8"><b>Archicaridæ</b></td> +<td class="center padl2" colspan="8"><b>Archicaridæ</b></td> </tr> <tr> <td class="center"> </td> @@ -10915,7 +10873,7 @@ Crustacea, the latter to Ringed worms.</p> <td class="center" rowspan="5">I.<br />Long spiders<br /><i>Arthrogastres</i></td> <td class="center" rowspan="5"><div class="figcenter" style="width: 10px;"><img src="images/cb150.png" width="10" height="150" alt="{" /></div></td> <td class="rightt">1.</td> -<td class="left vertt">Scorpion spiders<br /><i>Solifugæ</i></td> +<td class="left vertt">Scorpion spiders<br /><i>Solifugæ</i></td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left">Solpuga<br />Galeodes</td> </tr> @@ -10945,10 +10903,10 @@ Crustacea, the latter to Ringed worms.</p> </tr> <tr> -<td class="center" rowspan="2">II.<br />Round spiders<br /><i>Sphærogastres</i></td> +<td class="center" rowspan="2">II.<br />Round spiders<br /><i>Sphærogastres</i></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> <td class="rightt">6.</td> -<td class="left vertt">Spinning spiders<br /><i>Araneæ</i></td> +<td class="left vertt">Spinning spiders<br /><i>Araneæ</i></td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left">Epeira<br />Mygale</td> </tr> @@ -11110,7 +11068,7 @@ Crustacea, the latter to Ringed worms.</p> </tr> <tr> <td class="center" colspan="4"> </td> -<td class="center">Primæval Flies<br /><i>Archiptera</i></td> +<td class="center">Primæval Flies<br /><i>Archiptera</i></td> <td class="center"> </td> </tr> <tr> @@ -11159,7 +11117,7 @@ Crustacea, the latter to Ringed worms.</p> <td class="center">│<br />│<br /></td> </tr> <tr> -<td class="center">Weaving Spiders<br /><i>Araneæ</i><br />│<br />│<br /></td> +<td class="center">Weaving Spiders<br /><i>Araneæ</i><br />│<br />│<br /></td> <td class="center">│<br />│<br />│<br />│<br /></td> <td class="center" colspan="2">│<br />│<br />│<br />│<br /></td> <td class="center">│<br />│<br />│<br />│<br /></td> @@ -11171,7 +11129,7 @@ Crustacea, the latter to Ringed worms.</p> <td class="center">│<br /></td> </tr> <tr> -<td class="center" colspan="4">Scorpion Spiders<br />Solifugæ<br /><span class="oldtype">Spiders.</span><br /><b>Arachnida</b></td> +<td class="center" colspan="4">Scorpion Spiders<br />Solifugæ<br /><span class="oldtype">Spiders.</span><br /><b>Arachnida</b></td> <td class="center">│<br />│<br />│<br />│<br /></td> <td class="center">│<br />│<br />│<br />│<br /></td> </tr> @@ -11455,7 +11413,7 @@ another in the history of the earth.</p> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb100.png" width="10" height="100" alt="{" /></div></td> <td class="rightt">1.</td> -<td class="left">Primæval winged<br /><i>Archiptera</i></td> +<td class="left">Primæval winged<br /><i>Archiptera</i></td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left">M.I.<br />A.A.</td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb100a.png" width="10" height="100" alt="{" /></div></td> @@ -12091,7 +12049,7 @@ Vertebrata with head, with skull and brain, with centralized heart.</td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt= "{" /></div></td> <td class="rightt">4.</td> -<td class="left">Primæval fish</td> +<td class="left">Primæval fish</td> <td class="rightt">4.</td> <td class="left">Selachii</td> </tr> @@ -12127,7 +12085,7 @@ Vertebrata with head, with skull and brain, with centralized heart.</td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt= "{" /></div></td> <td class="rightt">8.</td> -<td class="left">Primæval<br />dragons</td> +<td class="left">Primæval<br />dragons</td> <td class="rightt">8.</td> <td class="left">Simosauria</td> </tr> @@ -12228,19 +12186,19 @@ Vertebrata with head, with skull and brain, with centralized heart.</td> <td class="rightt">21.</td> <td class="left">Long-tailed</td> <td class="rightt">21.</td> -<td class="left">Saururæ</td> +<td class="left">Saururæ</td> </tr> <tr> <td class="rightt">22.</td> <td class="left">Fan-tailed</td> <td class="rightt">22.</td> -<td class="left">Carinatæ</td> +<td class="left">Carinatæ</td> </tr> <tr> <td class="rightt">23.</td> <td class="left">Bush-tailed</td> <td class="rightt">23.</td> -<td class="left">Ratitæ</td> +<td class="left">Ratitæ</td> </tr> <tr class="blankrow"> <td> </td> @@ -12352,7 +12310,7 @@ Vertebrata with head, with skull and brain, with centralized heart.</td> <tr> <td class="center"> </td> -<td class="center">Primæval fish<br />3. Fishes<br /><span class="oldtype">Double-nostriled</span></td> +<td class="center">Primæval fish<br />3. Fishes<br /><span class="oldtype">Double-nostriled</span></td> <td class="center padr4">Selachii<br /><i>Pisces</i><br /><b>Amphirrhina</b></td> <td class="center" colspan="2"> </td> </tr> @@ -12392,7 +12350,7 @@ Vertebrata with head, with skull and brain, with centralized heart.</td> </tr> <tr> <td class="center">Sea-barrels<br /><i>Thaliacea</i></td> -<td class="center"><i>Ascidiæ</i><br />│<br /></td> +<td class="center"><i>Ascidiæ</i><br />│<br /></td> <td class="center padl1" colspan="2"><div class="figcenter" style="width: 200px;"><img src="images/cb200h.png" width="200" height="10" alt= "-------------------------------" /></div></td> <td class="center"> </td> @@ -12513,7 +12471,7 @@ form of paddling fins.</p> <td> </td> </tr> <tr> -<td class="center" rowspan="4"><span class="oldtype">A.<br />Primæval<br />Fish</span><br /><b>Selachii</b></td> +<td class="center" rowspan="4"><span class="oldtype">A.<br />Primæval<br />Fish</span><br /><b>Selachii</b></td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb75.png" width="10" height="75" alt= "{" /></div></td> <td class="center" rowspan="3">I. Transverse<br />mouths<br /><i>Plagiostomi</i></td> @@ -12536,8 +12494,8 @@ form of paddling fins.</p> <td class="center vertt"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt= "{" /></div></td> <td class="center vertt">3.</td> -<td class="left">Sea-Cats<br /><i>Chimæracei</i></td> -<td class="left">Chimæra, Calorrhynchias</td> +<td class="left">Sea-Cats<br /><i>Chimæracei</i></td> +<td class="left">Chimæra, Calorrhynchias</td> </tr> <tr class="blankrow"> <td> </td> @@ -12551,7 +12509,7 @@ form of paddling fins.</p> "{" /></div></td> <td class="center vertt">4.</td> <td class="left">Buckler-heads<br /><i>Pamphracte</i></td> -<td class="left">Cephalaspidæ, Placoderma, etc.</td> +<td class="left">Cephalaspidæ, Placoderma, etc.</td> </tr> <tr> <td class="center vertt">5.</td> @@ -12572,11 +12530,11 @@ form of paddling fins.</p> <tr> <td class="center vertt">7.</td> <td class="left"><i>Fulcrati</i></td> -<td class="left">Palæoniscus, bony pike, etc.</td> +<td class="left">Palæoniscus, bony pike, etc.</td> </tr> <tr> <td class="center vertt">8.</td> -<td class="left"><i>Semæopteri</i></td> +<td class="left"><i>Semæopteri</i></td> <td class="left">African finny pike, etc.</td> </tr> <tr class="blankrow"> @@ -12593,7 +12551,7 @@ form of paddling fins.</p> <tr> <td class="center vertt">10.</td> <td class="left"><i>Pycnoscolopes</i></td> -<td class="left">Coccolepida, Amiadæ, etc.</td> +<td class="left">Coccolepida, Amiadæ, etc.</td> </tr> <tr class="blankrow"> <td> </td> @@ -12737,7 +12695,7 @@ form of paddling fins.</p> <tr> <td class="center" colspan="2">Thrissogenes<br /><b>Physostomi</b><br /><b>Teleostei</b></td> <td class="center" colspan="2"> </td> -<td class="center"><br />Semæopteri<br /></td> +<td class="center"><br />Semæopteri<br /></td> <td class="center" colspan="2"> </td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="3"> </td> @@ -12829,7 +12787,7 @@ form of paddling fins.</p> <td class="center" colspan="2">│<br /></td> </tr> <tr> -<td class="center">Cephalaspidæ</td> +<td class="center">Cephalaspidæ</td> <td class="center" colspan="3">│<br /></td> <td class="center">Rajacei</td> <td class="center">│<br /></td> @@ -12855,7 +12813,7 @@ form of paddling fins.</p> <tr> <td class="center" colspan="4">│<br />│<br /></td> <td class="center">│<br />│<br /></td> -<td class="center">Chimæracei<br /><b>Holocephali</b></td> +<td class="center">Chimæracei<br /><b>Holocephali</b></td> <td class="center"> </td> <td class="center" colspan="4">│<br />│<br /></td> </tr> @@ -13440,7 +13398,7 @@ lizards (Monitor, Varanus).</p> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt= "{" /></div></td> <td class="center vertt">1.</td> -<td class="left">Primæval reptiles</td> +<td class="left">Primæval reptiles</td> <td class="center vertt">1.</td> <td class="left">Proreptilia</td> <td class="center vertt">*</td> @@ -13452,7 +13410,7 @@ lizards (Monitor, Varanus).</p> <td class="center vertt">2.</td> <td class="left">Thecodontia</td> <td class="center vertt">*</td> -<td class="left vertt">Palæosaurus</td> +<td class="left vertt">Palæosaurus</td> </tr> <tr class="blankrow"> <td> </td> @@ -13490,7 +13448,7 @@ lizards (Monitor, Varanus).</p> <td class="center vertt">6.</td> <td class="left">Glyptodermata</td> <td class="center vertt"> </td> -<td class="left vertt">Amphisbæna</td> +<td class="left vertt">Amphisbæna</td> </tr> <tr> <td class="center vertt">7.</td> @@ -13498,7 +13456,7 @@ lizards (Monitor, Varanus).</p> <td class="center vertt">7.</td> <td class="left">Vermilingues</td> <td class="center vertt"> </td> -<td class="left vertt">Chamæleo</td> +<td class="left vertt">Chamæleo</td> </tr> <tr class="blankrow"> <td> </td> @@ -14282,7 +14240,7 @@ alt="{" /></div></td> <b>Marsupialia</b><br /><b>Zoophaga</b></td> <td class="center" rowspan="14"><div class="figcenter" style="width: 10px;"><img src="images/cb200.png" width="10" height="200" alt="{" /></div></td> -<td class="center" colspan="2" rowspan="4">5. Insectivorous<br />Marsupial animals<br />Primæval pouched animals)</td> +<td class="center" colspan="2" rowspan="4">5. Insectivorous<br />Marsupial animals<br />Primæval pouched animals)</td> <td class="rightm" rowspan="4">5.</td> <td class="left vertm" rowspan="4">Cantharophaga</td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" @@ -14541,7 +14499,7 @@ alt="{" /></div></td> <td class="center" rowspan="19">XI.<br /><span class="oldtype">Disc Placental</span><br /><span class="oldtype">Animals</span><br /><b>Zonoplacentalia</b></td> <td class="center vertt" rowspan="19"><div class="figcenter" style="width: 10px;"><img src="images/cb300.png" width="10" height="300" alt="{" /></div></td> -<td class="center" rowspan="5">IX. Semi-apes<br /><i>Prosimiæ</i></td> +<td class="center" rowspan="5">IX. Semi-apes<br /><i>Prosimiæ</i></td> <td class="center" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb50.png" width="10" height="50" alt="{" /></div></td> <td class="rightt">18.</td> @@ -14637,7 +14595,7 @@ alt="{" /></div></td> <td> </td> </tr> <tr> -<td class="center" rowspan="3">XIII. Apes<br /><i>Simiæ</i></td> +<td class="center" rowspan="3">XIII. Apes<br /><i>Simiæ</i></td> <td class="center" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">30.</td> @@ -14649,13 +14607,13 @@ alt="{" /></div></td> <td class="rightt">31.</td> <td class="left">Flat-nosed</td> <td class="rightt">31.</td> -<td class="left">Platyrrhinæ</td> +<td class="left">Platyrrhinæ</td> </tr> <tr> <td class="rightt">32.</td> <td class="left">Narrow-nosed</td> <td class="rightt">32.</td> -<td class="left">Catarrhinæ</td> +<td class="left">Catarrhinæ</td> </tr> </table> @@ -14686,7 +14644,7 @@ alt="{" /></div></td> <td class="center">Rock Conies<br /><i>Lamnungia</i></td> <td class="center">│<br />│<br /></td> <td class="center" colspan="2"> </td> -<td class="center">Narrow-nosed<br /><i>Catarrhinæ</i></td> +<td class="center">Narrow-nosed<br /><i>Catarrhinæ</i></td> <td class="center"> </td> <td class="center">│<br />│<br /></td> <td class="center"> </td> @@ -14706,7 +14664,7 @@ alt="{" /></div></td> <td class="center" colspan="2"><div class="figcenter" style="width: 100px;"><img src="images/cb100h.png" width="100" height="10" alt="{" /></div>Pseudo-hoofed<br /><i>Chelophora</i><br />│<br />│<br /></td> <td class="center"> </td> -<td class="center">Flat-nosed<br /><i>Platyrrhinæ</i><br />│<br />│<br />│<br /></td> +<td class="center">Flat-nosed<br /><i>Platyrrhinæ</i><br />│<br />│<br />│<br /></td> <td class="center">│<br />│<br />│<br />│<br />│<br /></td> <td class="center"> </td> <td class="center">Flying foxes<br /><i>Pterocynes</i><br /><span class="oldtype">Flying Animals</span><br /><b>Chiroptera</b></td> @@ -14727,7 +14685,7 @@ alt="{" /></div>Pseudo-hoofed<br /><i>Chelophora</i><br />│<br />│<b <td class="center " colspan="2"><span class="oldtype">Gnawing Animals</span><br />│<br />│<br />│<br />│<br />│<br /></td> <td class="center"> </td> <td class="center" colspan="2"><div class="figcenter" style="width: 100px;"><img src="images/cb100h.png" width="100" height="10" -alt="{" /></div><span class="oldtype">Apes</span><br /><b>Simiæ</b><br />│<br />│<br />│<br /></td> +alt="{" /></div><span class="oldtype">Apes</span><br /><b>Simiæ</b><br />│<br />│<br />│<br /></td> <td class="center"> </td> <td class="center">│<br />│<br />│<br />│<br />│<br />│<br /></td> <td class="center">Land animals of prey<br /><i>Carnivora</i><br /><span class="oldtype">Animals of Prey</span><br /><b>Carnaria</b></td> @@ -15281,7 +15239,7 @@ alt="{" /></div></td> <td class="rightt">3.</td> <td class="left">Primary Odd-hoofs</td> <td class="rightt">3.</td> -<td class="left">Palæotherida*</td> +<td class="left">Palæotherida*</td> </tr> <tr> <td class="rightt">4.</td> @@ -15312,7 +15270,7 @@ alt="{" /></div></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">8.</td> -<td class="left">Primæval horses</td> +<td class="left">Primæval horses</td> <td class="rightt">8.</td> <td class="left">Anchitherida*</td> </tr> @@ -15339,7 +15297,7 @@ alt="{" /></div></td> </tr> <tr> <td class="rightt">11.</td> -<td class="left">Primæval pigs</td> +<td class="left">Primæval pigs</td> <td class="rightt">11.</td> <td class="left">Anthracotherida*</td> </tr> @@ -15357,7 +15315,7 @@ alt="{" /></div></td> </tr> <tr> <td class="rightt">14.</td> -<td class="left padr1">Primæval ruminants</td> +<td class="left padr1">Primæval ruminants</td> <td class="rightt">14.</td> <td class="left">Xiphodontia*</td> </tr> @@ -15372,7 +15330,7 @@ alt="{" /></div></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">15.</td> -<td class="left">Primæval deer</td> +<td class="left">Primæval deer</td> <td class="rightt">15.</td> <td class="left">Dremotherida*</td> </tr> @@ -15402,7 +15360,7 @@ alt="{" /></div></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">19.</td> -<td class="left">Primæval giraffes</td> +<td class="left">Primæval giraffes</td> <td class="rightt">19.</td> <td class="left">Sivatherida*</td> </tr> @@ -15420,7 +15378,7 @@ alt="{" /></div></td> <td class="center" rowspan="2"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="rightt">21.</td> -<td class="left">Primæval gazelles</td> +<td class="left">Primæval gazelles</td> <td class="rightt">21.</td> <td class="left">Antilocaprina*</td> </tr> @@ -15546,7 +15504,7 @@ alt="{" /></div></td> <td class="center padl5" colspan="4">│<br />│<br />│<br /></td> <td class="center padl4" colspan="3">│<br />│<br />│<br /></td> <td class="center">│<br />│<br />│<br /></td> -<td class="center">Primæval horses<br /><i>Anchitherida</i></td> +<td class="center">Primæval horses<br /><i>Anchitherida</i></td> </tr> <tr> <td class="center padl5" colspan="4">│<br /></td> @@ -15614,7 +15572,7 @@ alt="{" /></div></td> <td class="center">│<br /></td> </tr> <tr> -<td class="center" colspan="3">Primæval pigs<br /><i>Anthracotherida</i></td> +<td class="center" colspan="3">Primæval pigs<br /><i>Anthracotherida</i></td> <td class="center">│<br />│<br />│<br /></td> <td class="center"> </td> <td class="center">Rhinoceros-horses<br /><i>Elasmotherida</i></td> @@ -15638,7 +15596,7 @@ alt="{" /></div></td> </tr> <tr> <td class="center" colspan="3">│<br />│<br />│<br /></td> -<td class="center">Primæval<br />ruminants<br /><i>Xiphodontia</i></td> +<td class="center">Primæval<br />ruminants<br /><i>Xiphodontia</i></td> <td class="center padr1" colspan="2"><div class="figcenter" style="width: 100px;"><img src="images/cb100h.png" width="100" height="10" alt= "----------------" /></div>│<br />│<br /></td> <td class="center padl1" colspan="3">│<br />│<br />│<br /></td> @@ -15653,7 +15611,7 @@ alt="{" /></div></td> <td class="center padl305" colspan="4"><div class="figcenter" style="width: 150px;"><img src="images/cb150h.png" width="150" height="10" alt= "------------------------" /></div><span class="oldtype">Primary Pair-hoofs</span><br /><b>Anoplotherida</b></td> <td class="center padr2" colspan="5"><div class="figcenter" style="width: 250px;"><img src="images/cb250h.png" width="250" height="10" alt= -"----------------------------------------" /></div><span class="oldtype">Primary Odd-hoofs</span><br /><b>Palæotherida</b></td> +"----------------------------------------" /></div><span class="oldtype">Primary Odd-hoofs</span><br /><b>Palæotherida</b></td> </tr> <tr> <td class="center padl305" colspan="4">│<br /></td> @@ -16525,7 +16483,7 @@ of the Old World); (3) Platyrrhini (genuine American Apes); </tr> <tr> <td class="center padr3" colspan="5"><div class="figcenter" style="width: 350px;"><img src="images/cb350h.png" width="350" height="10" alt= -"------------------------------------------------------" /></div><span class="oldtype">Apes</span><br /><b>Simiæ</b></td> +"------------------------------------------------------" /></div><span class="oldtype">Apes</span><br /><b>Simiæ</b></td> <td class="center"> </td> </tr> <tr> @@ -16533,7 +16491,7 @@ of the Old World); (3) Platyrrhini (genuine American Apes); <td class="center"> </td> </tr> <tr> -<td class="center padr2" colspan="5">Semi-apes<br /><i>Prosimiæ</i></td> +<td class="center padr2" colspan="5">Semi-apes<br /><i>Prosimiæ</i></td> <td class="center"> </td> </tr> </table> @@ -17330,33 +17288,33 @@ Epoch</span></td> <td class="right"> </td> <td class="left"> </td> <td class="rightt">2.</td> -<td class="left">Single-celled<br />Primæval animals</td> +<td class="left">Single-celled<br />Primæval animals</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">Simple Amœbæ<br />(<i>Automœbæ</i>)</td> +<td class="left">Simple Amœbæ<br />(<i>Automœbæ</i>)</td> </tr> <tr> <td class="right"> </td> <td class="left"> </td> <td class="rightt">3.</td> -<td class="left">Many-celled<br />Primæval animals</td> +<td class="left">Many-celled<br />Primæval animals</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">Communities of<br />Amœbæ<br />(<i>Synamœbæ</i>)</td> +<td class="left">Communities of<br />Amœbæ<br />(<i>Synamœbæ</i>)</td> </tr> <tr> <td class="right"> </td> <td class="left"> </td> <td class="rightt">4.</td> -<td class="left">Ciliated planulæ<br />(<i>Planæada</i>)</td> +<td class="left">Ciliated planulæ<br />(<i>Planæada</i>)</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">Planula larvæ</td> +<td class="left">Planula larvæ</td> </tr> <tr> <td class="rightt">1.</td> <td class="left">Laurentian Period</td> <td class="rightt">5.</td> -<td class="left">Primæval Intestinal<br />animals<br />(<i>Gastræada</i>)</td> +<td class="left">Primæval Intestinal<br />animals<br />(<i>Gastræada</i>)</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="leftm">Gastrula larvæ</td> +<td class="leftm">Gastrula larvæ</td> </tr> <tr> <td class="rightt">2.</td> @@ -17380,7 +17338,7 @@ Epoch</span></td> <td class="rightt">8.</td> <td class="left">Sack worms<br />(<i>Himatega</i>)</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">Sea-squirts<br />(<i>Ascidiæ</i>)</td> +<td class="left">Sea-squirts<br />(<i>Ascidiæ</i>)</td> </tr> <tr> @@ -17407,13 +17365,13 @@ Epoch</span></td> <tr> <td class="left bb" colspan="2">(Compare p. <a href="#Page_22">22</a>, and<br />Plate <a href="#plxiv">XIV</a>. and its explanation.)</td> <td class="rightt bb">11.</td> -<td class="left bb">Primæval fish<br />(<i>Selachii</i>)</td> +<td class="left bb">Primæval fish<br />(<i>Selachii</i>)</td> <td class="center bb"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left bb">Sharks<br />(<i>Squalacei</i>)</td> </tr> <tr> <td class="center bb" rowspan="3"><span class="smcap">II.<br /> -Palæolithic<br /> +Palæolithic<br /> or<br /> Primary<br /> Epoch</span></td> @@ -17453,7 +17411,7 @@ Epoch</span></td> <td class="left">Trias Period</td> <td class="center bb" rowspan="3"><div class="figcenter" style="width: 10px;"><img src="images/cb100.png" width="10" height="100" alt="{" /></div></td> <td class="rightt">15.</td> -<td class="left">Primæval Amniota<br />(<i>Protamnia</i>)</td> +<td class="left">Primæval Amniota<br />(<i>Protamnia</i>)</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left">?Between the Tailed-Amphibia<br />and Primary mammals</td> </tr> @@ -17484,7 +17442,7 @@ Epoch</span></td> <td class="left"> </td> <td class="center bb" rowspan="4"><div class="figcenter" style="width: 10px;"><img src="images/cb100.png" width="10" height="100" alt="{" /></div></td> <td class="rightt">18.</td> -<td class="left">Semi-apes<br />(<i>Prosimiæ</i>)</td> +<td class="left">Semi-apes<br />(<i>Prosimiæ</i>)</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> <td class="left">Lori (<i>Stenops</i>)<br />Maki (<i>Lemur</i>)</td> </tr> @@ -18547,7 +18505,7 @@ alt="{" /></div><span class="oldtype">Woolly-haired</span><br /><b>Ulotrichi</b> <tr> <td class="center"> </td> <td class="center" colspan="9"><div class="figcenter" style="width: 400px;"><img src="images/cb400h.png" width="400" height="10" -alt="{" /></div><b>Primæval Men</b></td> +alt="{" /></div><b>Primæval Men</b></td> </tr> </table> @@ -19299,7 +19257,7 @@ kindred Magyars, and in Turkey by the Osmanlis.</p> <td class="center" colspan="3">Himiarites</td> <td class="center">│<br />│<br /></td> <td class="center" colspan="2"><div class="figcenter" style="width: 100px;"><img src="images/cb100h.png" width="100" height="10" alt= -"-------------------" /></div><b>Aramæans</b></td> +"-------------------" /></div><b>Aramæans</b></td> <td class="center" colspan="2">│<br />│<br /></td> </tr> <tr> @@ -19314,7 +19272,7 @@ kindred Magyars, and in Turkey by the Osmanlis.</p> "-------------------" /></div><b>South Arabians</b></td> <td class="center"><b>North Arabians</b></td> <td class="center" colspan="4"><div class="figcenter" style="width: 200px;"><img src="images/cb200h.png" width="200" height="10" alt= -"-------------------" /></div><b>Primæval Jews</b><br /><b>North-Semites</b></td> +"-------------------" /></div><b>Primæval Jews</b><br /><b>North-Semites</b></td> </tr> <tr> <td class="center" colspan="4">│<br /></td> @@ -19339,7 +19297,7 @@ kindred Magyars, and in Turkey by the Osmanlis.</p> <td class="center"> </td> <td class="center"><br />Guanchites</td> <td class="center" colspan="3"> </td> -<td class="center padl5" colspan="4">Eusemites (<b>Primæval Semites</b>)<br />(Semites in a narrow sense)</td> +<td class="center padl5" colspan="4">Eusemites (<b>Primæval Semites</b>)<br />(Semites in a narrow sense)</td> </tr> <tr> @@ -19419,7 +19377,7 @@ kindred Magyars, and in Turkey by the Osmanlis.</p> <td class="center">│<br />│<br />│<br /></td> <td class="center">Modern<br />Egyptians<br />(<b>Copts</b>)</td> <td class="center">│<br />│<br />│<br /></td> -<td class="center">Primæval<br />Phœnicians</td> +<td class="center">Primæval<br />Phœnicians</td> <td class="center">Babylonians</td> <td class="center">Assyrians</td> <td class="center">│<br />│<br />│<br /></td> @@ -19664,7 +19622,7 @@ alt="{" /></div></td> <td class="center">│<br /></td> <td class="center">│<br /></td> <td class="center">│<br /></td> -<td class="center padr12" colspan="5"><b>Primæval Germans</b></td> +<td class="center padr12" colspan="5"><b>Primæval Germans</b></td> <td class="center">│<br /></td> </tr> <tr> @@ -19777,7 +19735,7 @@ alt="{" /></div><b>Sclavo-Germans </b>< <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="2"> </td> <td class="center" colspan="2"><div class="figcenter" style="width: 75px;"><img src="images/cb75h.png" width="75" height="10" -alt="{" /></div><b>Primæval Thracians</b></td> +alt="{" /></div><b>Primæval Thracians</b></td> <td class="center">│<br />│<br />│<br /></td> <td class="center" colspan="3"> </td> @@ -19798,7 +19756,7 @@ alt="{" /></div><b>Primæval Thracians</b></td> <td class="center">│<br />│<br /></td> <td class="center">│<br />│<br /></td> <td class="center padl1" colspan="3"><div class="figcenter" style="width: 125px;"><img src="images/cb125h.png" width="125" height="10" -alt="{" /></div><b>Græco-Romans</b></td> +alt="{" /></div><b>Græco-Romans</b></td> <td class="center" colspan="3"> </td> </tr> <tr> @@ -19952,7 +19910,7 @@ a Compound Primæval Language.</p></td> <td class="center bl">Pr</td> <td class="center bl">Mn</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">South Africa (between 30° Lat. and 5° N. Lat.)</td> +<td class="left">South Africa (between 30° Lat. and 5° N. Lat.)</td> </tr> <tr> <td class="center">4.</td> @@ -19961,7 +19919,7 @@ a Compound Primæval Language.</p></td> <td class="center bl">Pr</td> <td class="center bl">Pl</td> <td class="center"><div class="figcenter" style="width: 10px;"><img src="images/cb30.png" width="10" height="30" alt="{" /></div></td> -<td class="left">Central Africa (between the Equator and 30° N. Lat.)</td> +<td class="left">Central Africa (between the Equator and 30° N. Lat.)</td> </tr> <tr> <td class="center" colspan="4"> </td> @@ -24105,383 +24063,6 @@ enterprises and heroic achievements.”—<i>New York Evening Post.</i>< <p><i>D. APPLETON & CO., Publishers, 1, 3, & 5 Bond Street, N. Y.</i></p> - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of The History of Creation, Vol. II (of 2), by -Ernst Haeckel - -*** END OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CREATION, VOL II *** - -***** This file should be named 40473-h.htm or 40473-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/4/0/4/7/40473/ - -Produced by Adrian Mastronardi, Turgut Dincer, Jason Palmer -and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive) - - -Updated editions will replace the previous one--the old editions -will be renamed. - -Creating the works from public domain print editions means that no -one owns a United States copyright in these works, so the Foundation -(and you!) can copy and distribute it in the United States without -permission and without paying copyright royalties. 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Thus, we do not necessarily -keep eBooks in compliance with any particular paper edition. - -Most people start at our Web site which has the main PG search facility: - - www.gutenberg.org - -This Web site includes information about Project Gutenberg-tm, -including how to make donations to the Project Gutenberg Literary -Archive Foundation, how to help produce our new eBooks, and how to -subscribe to our email newsletter to hear about new eBooks. - - -</pre> - +<div>*** END OF THE PROJECT GUTENBERG EBOOK 40473 ***</div> </body> </html> diff --git a/40473.txt b/40473.txt deleted file mode 100644 index 1d3ff40..0000000 --- a/40473.txt +++ /dev/null @@ -1,15061 +0,0 @@ -Project Gutenberg's The History of Creation, Vol. II (of 2), by Ernst Haeckel - -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 History of Creation, Vol. II (of 2) - Or the Development of the Earth and its Inhabitants by the - Action of Natural Causes - -Author: Ernst Haeckel - -Translator: E. Ray Lankester - -Release Date: August 14, 2012 [EBook #40473] - -Language: English - -Character set encoding: ASCII - -*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CREATION, VOL II *** - - - - -Produced by Adrian Mastronardi, Turgut Dincer, Jason Palmer -and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive) - - - - - - - - - - +------------------------------------------------------------------+ - | Transcriber's note: | - | | - | This book was published in two volumes, of which this is the | - | second. The first volume was released as Project Gutenberg ebook | - | #40472, available at http://www.gutenberg.org/ebooks/40472 | - | | - | Numbers enclosed in square brackets, e.g. [1], relate to | - | footnotes, which have been placed at the end of the text. | - | Numbers enclosed in parentheses, e.g. (1), relate to works | - | referred to in the text and listed at the end of this volume. | - | | - | In the text versions of these two volumes, words in _italics_ | - | are enclosed in underscores, +bold+ words are enclosed in plus | - | signs, and words in =Gothic script= are enclosed in equal signs. | - | Curly brackets are used to represent subscripts, e.g. k{1}. | - +------------------------------------------------------------------+ - - - - - THE HISTORY OF CREATION. - - - - -[Illustration: Hypothetical Sketch of the Monophyletic Origin of Man.] - - - - - THE - HISTORY OF CREATION: - - _OR THE DEVELOPMENT OF THE EARTH AND ITS - INHABITANTS BY THE ACTION OF NATURAL CAUSES._ - - A POPULAR EXPOSITION OF - THE DOCTRINE OF EVOLUTION IN GENERAL, AND OF THAT OF - DARWIN, GOETHE, AND LAMARCK IN PARTICULAR. - - FROM THE GERMAN OF - ERNST HAECKEL, - PROFESSOR IN THE UNIVERSITY OF JENA. - - THE TRANSLATION REVISED BY - PROFESSOR E. RAY LANKESTER, M.A., F.R.S., - FELLOW OF EXETER COLLEGE, OXFORD. - - _IN TWO VOLUMES._ - VOL. II. - - NEW YORK: - D. APPLETON AND COMPANY, - 1, 3, AND 5 BOND STREET. - 1880. - - - - - A sense sublime - Of something far more deeply interfused, - Whose dwelling is the light of setting suns, - And the round ocean, and the living air, - And the blue sky, and in the mind of man; - A motion and a spirit that impels - All thinking things, all objects of all thought, - And rolls through all things. - - In all things, in all natures, in the stars - Of azure heaven, the unenduring clouds, - In flower and tree, in every pebbly stone - That paves the brooks, the stationary rocks, - The moving waters and the invisible air. - - WORDSWORTH. - - - - -CONTENTS OF VOL. II. - - - CHAPTER XV. - PAGE - PERIODS OF CREATION AND RECORDS OF CREATION. - - Reform of Systems by the Theory of Descent.--The Natural System - as a Pedigree.--Palaeontological Records of the - Pedigree.--Petrifactions as Records of Creation.--Deposits of the - Neptunic Strata and the Enclosure of Organic Remains.--Division - of the Organic History of the Earth into Five Main Periods: - Period of the Tangle Forests, Fern Forests, Pine Forests, - Foliaceous Forests, and of Cultivation.--The Series of Neptunic - Strata.--Immeasurable Duration of the Periods which have elapsed - during their Formation.--Deposits of Strata only during the - Sinking, not during the Elevation of the Ground.--Other Gaps in - the Records of Creation.--Metamorphic Condition of the most - Ancient Neptunic Strata.--Small Extent of Palaeontological - Experience.--Small proportion of Organisms and of Parts of - Organisms Capable of Petrifying.--Rarity of many Petrified - Species.--Want of Fossilised Intermediate Forms.--Records of the - Creation in Ontogeny and in Comparative Anatomy 1 - - - CHAPTER XVI. - - PEDIGREE AND HISTORY OF THE KINGDOM OF THE PROTISTA. - - Special Mode of Carrying out the Theory of Descent in the - Natural System of Organisms.--Construction of Pedigrees.--Descent - of all Many-celled from Single-celled Organisms.--Descent of - Cells from Monera.--Meaning of Organic Tribes, or Phyla.--Number - of the Tribes in the Animal and Vegetable Kingdoms.--The - Monophyletic Hypothesis of Descent, or the Hypothesis of one - Common Progenitor, and the Polyphyletic Hypothesis of Descent, - or the Hypothesis of many Progenitors.--The Kingdom of Protista, - or Primaeval Beings.--Eight Classes of the Protista Kingdom: - Monera, Amoebae, or Protoplastae; Whip-swimmers, or Flagellata; - Ciliated-balls, Cili Catallacta; Labyrinth-streamers, or - Labyrinthuleae; Flint-cells, or Diatomeae; Mucous-moulds, or - Myxomycetes; Root-footers (Rhizopoda).--Remarks on the General - Natural History of the Protista: Their Vital Phenomena, - Chemical Composition, and Formation (Individuality and - Fundamental Form).--Phylogeny of the Prostista Kingdom 36 - - - CHAPTER XVII. - - PEDIGREE AND HISTORY OF THE VEGETABLE KINGDOM. - - The Natural System of the Vegetable Kingdom.--Division of the - Vegetable Kingdom into Six Branches and Eighteen Classes.--The - Flowerless Plants (Cryptogamia).--Sub-kingdom of the Thallus - Plants.--The Tangles, or Algae (Primary Algae, Green Algae, Brown - Algae, Red Algae).--The Thread-plants, or Inophytes (Lichens and - Fungi).--Sub-kingdom of the Prothallus Plants.--The Mosses, or - Muscinae (Water-mosses, Liverworts, Leaf-mosses, - Bog-mosses).--The Ferns, or Filicinae (Leaf-ferns, Bamboo-ferns, - Water-ferns, Scale-ferns).--Sub kingdom of Flowering Plants - (Phanerogamia).--The Gymnosperms, or Plants with Naked Seeds - (Palm-ferns = Cycadeae; Pines = Coniferae).--The Angiosperms, or - Plants with Enclosed Seeds.--Monocotylae.--Dicotylae.--Cup-blossoms - (Apetalae).--Star-blossoms (Diapetalae).--Bell-blossoms - (Gamopetalae) 77 - - - CHAPTER XVIII. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - I. ANIMAL-PLANTS AND WORMS. - - The Natural System of the Animal Kingdom.--Linnaeus' and Lamarck's - Systems.--The Four Types of Baer and Cuvier.--Their Increase to - Seven Types.--Genealogical Importance of the Seven Types as - Independent Tribes of the Animal Kingdom.--Derivation of - Zoophytes and Worms from Primaeval Animals.--Monophyletic and - Polyphyletic Hypothesis of the Descent of the Animal - Kingdom.--Common Origin of the Four Higher Animal Tribes out of - the Worm Tribe.--Division of the Seven Animal Tribes into - Sixteen Main Classes, and Thirty-eight Classes.--Primaeval - Animals (Monera, Amoebae, Synamoebae), Gregarines, Infusoria, - Planaeades, and Gastraeades (Planula and Gastrula).--Tribe of - Zoophytes.--Spongiae (Mucous Sponges, Fibrous Sponges, Calcareous - Sponges).--Sea Nettles, or Acalephae (Corals, Hood-jellies, - Comb-jellies).--Tribe of Worms 117 - - - CHAPTER XIX. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - II. MOLLUSCA, STAR-FISHES, AND ARTICULATED ANIMALS. - - Tribe of Molluscs.--Four Classes of Molluscs: Lamp-shells - (Spirobranchia); Mussels (Lamellibranchia); Snails (Cochlides); - Cuttle-fish (Cephalopoda).--Tribe of Star-fishes, or - Echinoderma.--Their Derivation from Ringed Worms (Mailed Worms, - or Phracthelminthes).--The Alternation of Generation in the - Echinoderma.--Four Classes of Star-fish: Sea-stars (Asteridea); - Sea-lilies (Crinoidea); Sea-urchins (Echinidea); Sea-cucumbers - (Holothuridea).--Tribe of Articulated Animals, or - Arthropoda.--Four Classes of Articulated Animals: Branchiata, or - Crustacea, breathing through gills; Jointed Crabs; Mailed - Crabs; Articulata Tracheata, breathing through Air - Tubes.--Spiders (Long Spiders, Round - Spiders).--Myriopods.--Insects.--Chewing and Sucking - Insects.--Pedigree and History of the Eight Orders of Insects 154 - - - CHAPTER XX. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - III. VERTEBRATE ANIMALS. - - The Records of the Creation of Vertebrate Animals (Comparative - Anatomy, Embryology, and Palaeontology).--The Natural System of - Vertebrate Animals.--The Four Classes of Vertebrate Animals, - according to Linnaeus and Lamarck.--Their Increase to Nine - Classes.--Main Class of the Tube-hearted, or Skull-less Animals - (the Lancelet).--Blood Relationship between the Skull-less Fish - and the Tunicates.--Agreement in the Embryological Development - of Amphioxus and Ascidiae.--Origin of the Vertebrate Tribe out of - the Worm Tribe.--Main Class of Single-nostriled, or - Round-mouthed Animals (Hag and Lampreys).--Main Class of - Anamnionate Animals, devoid of Amnion.--Fishes (Primaeval Fish, - Cartilaginous Fish, Osseous Fish).--Mud-fish, or Dipneusta.--Sea - Dragons, or Halisauria.--Frogs and Salamanders, or Amphibia - (Mailed Amphibia, Naked Amphibia).--Main Class of Amnionate - Animals, or Amniota.--Reptiles (Primary Reptiles, Lizards, - Serpents, Crocodiles, Tortoises, Flying Reptiles, Dragons, - Beaked Reptiles).--Birds (Feather-tailed, Fan-tailed, - Bush-tailed) 192 - - - CHAPTER XXI. - - PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - - IV. MAMMALS. - - The System of Mammals according to Linnaeus and - Blainville.--Three Sub-classes of Mammals (Ornithodelphia, - Didelphia, Monodelphia).--Ornithodelphia, or Monotrema.--Beaked - Animals (Ornithostoma).--Didelphia, or Marsupials.--Herbivorous - and Carnivorous Marsupials.--Monodelphia, or Placentalia - (Placental Animals).--Meaning of the Placenta.--Tuft - Placentalia.--Girdle Placentalia.--Disc - Placentalia.--Non-deciduates, or Indeciduata.--Hoofed - Animals.--Single and Double-hoofed Animals.--Whales.--Toothless - Animals.--Deciduates, or Animals with - Decidua.--Semi-apes.--Gnawing Animals.--Pseudo-hoofed - Animals.--Insectivora.--Beasts of Prey.--Bats.--Apes 231 - - - CHAPTER XXII. - - ORIGIN AND PEDIGREE OF MAN. - - The Application of the Theory of Descent to Man.--Its Immense - Importance and Logical Necessity.--Man's Position in the Natural - System of Animals, among Disco-placental Animals.--Incorrect - Separation of the Bimana and Quadrumana.--Correct Separation of - Semi-apes from Apes.--Man's Position in the Order of - Apes.--Narrow-nosed Apes (of the Old World) and Flat-nosed Apes - (of America).--Difference of the two Groups.--Origin of Man from - Narrow-nosed Apes.--Human Apes, or Anthropoides.--African - Human-apes (Gorilla and Chimpanzee).--Asiatic Human-apes (Orang - and Gibbon).--Comparison between the different Human Apes and - the different Races of Men.--Survey of the Series of the - Progenitors of Man.--Invertebrate Progenitors (Prochordata) and - Vertebrate Progenitors 263 - - - CHAPTER XXIII. - - MIGRATION AND DISTRIBUTION OF MANKIND. HUMAN SPECIES AND HUMAN - RACES. - - Age of the Human Race.--Causes of its Origin.--The Origin of - Human Language.--Monophyletic or Single, Polyphyletic or - Multiple Origin of the Human Race.--Derivation of Man from many - Pairs.--Classification of the Human Races.--System of Twelve - Species of Men.--Woolly-Haired Men, or Ulotrichis.--Bushy-Haired - (Papuans, Hottentots).--Fleecy-haired (Caffres, - Negroes).--Straight-haired Men, or Lissotrichi.--Stiff-haired - (Australians, Malays, Mongols, Arctic, and American - Tribes).--Curly-haired (Dravidas, Nubians, Midlanders).--Number - of Population.--Primaeval Home of Man (South Asia, or - Lemuria).--Nature of Primaeval Men.--Number of Primaeval Languages - (Monoglottists and Polyglottists).--Divergence and Migration of - the Human Race.--Geographical Distribution of the Human Species 296 - - - CHAPTER XXIV. - - OBJECTIONS AGAINST, AND PROOFS OF THE TRUTH OF, THE THEORY OF - DESCENT. - - Objections to the Doctrine of Filiation.--Objections of Faith - and Reason.--Immeasurable Length of the Geological - Periods.--Transition Forms between Kindred Species.--Dependence - of Stability of Form on Inheritance, and of the Variability of - Form on Adaptation.--Origin of very Complicated Arrangement of - Organisation.--Gradual Development of Instincts and Mental - Activities.--Origin of a priori Knowledge from Knowledge a - posteriori.--The Knowledge requisite for the Correct - Understanding of the Doctrine of Filiation.--Necessary - Interaction between Empiricism and Philosophy.--Proofs of the - Theory of Descent.--Inner Causal-Connection between all the - Biological Series of Phenomena.--The Direct Proof of the Theory - of Selection.--Relation of the Theory of Descent to - Anthropology.--Proofs of the Animal Origin of Man.--The Pithecoid - Theory as an Inseparable Part of the Theory of - Descent.--Induction and Deduction.--Gradual Development of the - Human Mind.--Body and Mind.--Human Soul and Animal Soul.--A Glance - at the Future 334 - - - LIST OF WORKS REFERRED TO IN THE TEXT 371 - - APPENDIX (Explanation of the Plates) 379 - - INDEX 402 - - - - -LIST OF ILLUSTRATIONS. - - -PLATES. - - XV.--Hypothetical Sketch of the Monophyletic Origin - of Man _Frontispiece_ - - IV.--Hand of Nine different Mammals _To face page_ 34 - - V.--Single-Stemmed, or Monophyletic, Pedigree of the - Vegetable Kingdom " 112 - - VI.--Historical Growth of the Six Great Stems of Animals " 122 - - VII.--Animal Plants, or Zoophytes " 140 - - VIII.--Star Fishes--First Generation _Between pp._ 170, 171 - - IX.--Star Fishes--Second Generation " " " - - X.--Nauplius-Youth-Form of Six Crab Fish " 174, 175 - - XI.--Adult-Form of the same Six Crab Fish " " " - - XII.--Ascidia and Amphioxus " 201, 202 - - XIII.--Ascidia and Amphioxus " " " - - XIV.--Single, or Monophyletic, Pedigree of Back-boned - Animals _To face page_ 222 - - - FIGURES. - - 8.--Protamoeba Primitiva 52 - - 9.--Bathybius Haeckelii 53 - - 10.--Amoeba Sphaerococcus 54 - - 11.--Euglena Striata 57 - - 12.--Magosphaera Planula 58 - - 13.--Labyrinthula Macrocystis 59 - - 14.--Navicula Hippocampus 60 - - 15.--Physarum Albipes 61 - - 16.--Cyrtidosphaera Echinoides 66 - - 17.--Caulerpa Denticulata 87 - - 18.--Euastrum Rota 88 - - 19.--Fucus Vesiculosus (egg of) 90 - - - - -THE HISTORY OF CREATION. - - - - -CHAPTER XV. - -PERIODS OF CREATION AND RECORDS OF CREATION. - - - Reform of Systems by the Theory of Descent.--The Natural System - as a Pedigree.--Palaeontological Records of the - Pedigree.--Petrifactions as Records of Creation.--Deposits of the - Neptunic Strata and the Enclosure of Organic Remains.--Division - of the Organic History of the Earth into Five Main Periods: - Period of the Tangle Forests, Fern Forests, Pine Forests, - Foliaceous Forests, and of Cultivation.--The Series of Neptunic - Strata.--Immeasurable Duration of the Periods which have elapsed - during their Formation.--Deposits of Strata only during the - Sinking, not during the Elevation of the Ground.--Other Gaps in - the Records of Creation.--Metamorphic Condition of the most - Ancient Neptunic Strata.--Small Extent of Palaeontological - Experience.--Small proportion of Organisms and of Parts of - Organisms Capable of Petrifying.--Rarity of many Petrified - Species.--Want of Fossilised Intermediate Forms.--Records of the - Creation in Ontogeny and in Comparative Anatomy. - - -The revolutionary influence which the Theory of Descent must exercise -upon all sciences, will in all probability affect no branch of science, -excepting Anthropology, so much as the descriptive portion of natural -history, that which is known as systematic Zoology and Botany. Most -naturalists who have hitherto occupied themselves with arranging the -different systems of animals and plants, have collected, named, and -arranged the different species of these natural bodies with much the -same interest as antiquarians and ethnographers collect the weapons and -utensils of different nations. Many have not even risen above the degree -of intelligence with which people usually collect, label, and arrange -crests, stamps, and similar curiosities. In the same manner as some -collectors find their pleasure in the similarity of forms, the beauty or -rarity of the crests or stamps, and admire in them the inventive art of -man, so many naturalists take a delight in the manifold forms of animals -and plants, and marvel at the rich imagination of the Creator, at His -unwearied creative activity, and at His curious fancy for forming, by -the side of so many beautiful and useful organisms, also a number of -ugly and useless ones. - -This childlike treatment of systematic Zoology and Botany is completely -annihilated by the Theory of Descent. In the place of the superficial -and playful interest with which most naturalists have hitherto regarded -organic structures, we now have the much higher interest of the -intelligent understanding which detects in the _related forms_ of -organisms their true _blood relationships_. The _Natural System of -animals and plants_, which was formerly valued either only as a registry -of names, to facilitate the survey of the different forms, or as a table -of contents for the short expression of their degrees of similarity, -receives from the Theory of Descent the incomparably higher value of a -true _pedigree of organisms_. This pedigree is to disclose to us the -genealogical connection of the smaller and larger groups. It has to show -us in what way the different classes, orders, families, genera, and -species of the animal and vegetable kingdoms correspond with the -different branches, twigs, and groups of twigs of the pedigree. Every -wider and higher category or stage of the system (for example a class, -or an order) comprises a number of larger and stronger branches of the -pedigree; every narrower and lower category (for example a genus, or a -species) only a smaller and thinner group of twigs. It is only when we -thus view the natural system as a pedigree that we perceive its true -value. (Gen. Morph. ii. Plate XVII. p. 397.) - -Since we hold fast this genealogical conception of the Organic System, -to which alone undoubtedly the future of classificatory Zoology and -Botany belongs, we should now turn our attention to one of the most -essential, but also one of the most difficult, tasks of the -"non-miraculous history of creation," namely, to the actual construction -of the Organic Pedigree. Let us see how far we are already able to point -out all the different organic forms as the divergent descendants of a -single or of some few common original forms. But how can we construct -the actual pedigree of the animal and vegetable group of forms from our -knowledge of them, at present so scanty and fragmentary? The answer to -this question lies in what we have already remarked of the parallelism -of the three series of development--in the important causal relation -which connects the palaeontological development of all organic tribes -with the embryological development of individuals, and with the -systematic development of groups. - -In order to accomplish our task we shall first have to direct our -attention to _palaeontology_, or _the science of petrifactions_. For if -the Theory of Descent is really true, if the petrified remains of -formerly living animals and plants really proceed from the extinct -primaeval ancestors and progenitors of the present organisms, then, -without anything else, the knowledge and comparison of petrifactions -ought to disclose to us the pedigree of organisms. However simple and -clear this may seem in theory, the task becomes extremely hard and -complicated when it is actually taken in hand. Its practical solution -would be very difficult even if the petrifactions were to any extent -completely preserved. But this is by no means the case. The obvious -records of creation which lie buried in petrifactions are imperfect -beyond all measure. Hence it is necessary critically to examine these -records, and to determine the value which petrifactions possess for the -history of the development of organic tribes. As I have previously -discussed the general importance of petrifactions as the records of -creation, when we were considering Cuvier's merits in the science of -fossils, we may now at once examine the conditions and circumstances -under which the remains of organic bodies became petrified and preserved -in a more or less recognizable form. - -As a rule we find petrifactions or fossils enclosed only in those stones -which have been deposited in layers as mud by water, and which are on -that account called neptunic, stratified, or sedimentary rocks. The -deposition of such strata could of course only commence after the -condensation of watery vapour into liquid water had taken place in the -course of the earth's history. After that period, which we considered in -our last chapter, not only did life begin on the earth, but also an -uninterrupted and exceedingly important transformation of the rigid -inorganic crust of the earth. The water began that extremely important -mechanical action by which the surface of the earth is perpetually, -though slowly, transformed. I may surely presume that it is generally -known what an extremely important influence, in this respect, is even -yet exercised by water at every moment. As it falls down as rain, -trickling through the upper strata of the earth's crust, and flowing -down from heights into hollows, it chemically dissolves different -mineral parts of the ground, and mechanically washes away the loose -particles. In flowing down from mountains water carries their debris -into the plains, or deposits it as mud in stagnant lakes. Thus it -continually works at lowering mountains and filling up valleys. In like -manner the breakers of the sea work uninterruptedly at the destruction -of the coasts and at filling up the bottom of the sea with the debris -they wash down. The action of water alone, if it were not counteracted -by other circumstances, would in time level the whole earth. There can -be no doubt that the mountain masses--which are annually carried down as -mud into the sea, and deposited on its floor--are so great that in the -course of a longer or shorter period, say a few millions of years, the -surface of the earth would be completely levelled and become enclosed by -a continuous sheet of water. That this does not happen is owing to the -perpetual volcanic action of the fiery-fluid centre of the earth. The -surging of the melted nucleus against the firm crust necessitates -continual alternations of elevation and depression on the different -parts of the earth's surface. These elevations and depressions for the -most part take place very slowly; but, as they continue for thousands of -years, by the combined effect of small, interrupted movements, they -produce results no less grand than does the counteracting and levelling -action of water. - -Since the elevations and depressions of the different parts of the -earth alternate with one another in the course of millions of years, -first this and then that part of the earth's surface is above or below -the level of the sea. I have already given examples of this in the -preceding chapter (vol. i. p. 361). Hence, in all probability, there is -no part of the outer crust of the earth which has not been repeatedly -above and also below the level of the sea. This repeated change explains -the variety and the different composition of the numerous neptunic -strata of rocks, which in most places have been deposited one above -another in considerable thickness. In the different periods of the -earth's history during which these deposits took place there lived -various and different populations of animals and plants. When their dead -bodies sank to the bottom of the waters, the forms of the bodies -impressed themselves upon the soft mud, and imperishable parts, such as -hard bones, teeth, shells, etc., became enclosed in it uninjured. These -were preserved in the mud, which condensed them into neptunic rock, and -as petrifactions they now serve to characterise the respective strata. -By a careful comparison of the different strata lying one above another, -and the petrifactions preserved in them, it has become possible to -decide the relative age of the strata and groups of strata, and to -establish, by direct observation, the principal eras of phylogeny, that -is to say, the stages in history of the development of animal and -vegetable tribes. - -The different strata of neptunic rocks deposited one above another, -which are composed in very various ways of limestone, clay, and sand, -geologists have grouped together into an ideal System or Series, which -corresponds with the whole course of the organic history of the earth, -or with that portion of the earth's history during which organic life -existed. Just as so-called "universal history" falls into larger and -smaller periods, which are characterized by the conditions of -development of the most important nations at the respective epochs, and -are separated from one another by great events, so we also divide the -infinitely longer organic history of the earth into a series of greater -and less periods. Each of these periods is distinguished by a -characteristic flora and fauna, and by the specially strong development -of certain vegetable or animal groups, and each is separated from the -preceding and succeeding period by a striking change in the character of -its animal and vegetable inhabitants. - -In relation to the following survey of the historical course of -development which the large animal and vegetable tribes have passed -through, it will be desirable to say a few words first as to the -systematic classification of the neptunic groups of strata, and the -larger and smaller periods corresponding to them. As will be seen -directly, we are able to divide the whole of the sedimentary rocks lying -one above another into five main groups or periods, each period into -several subordinate groups of strata or _systems_, and each system of -strata again into still smaller groups or _formations_; finally, each -formation can again be divided into stages or sub-formations, and each -of these again into still smaller layers or beds. Each of the five great -rock-groups was deposited during a great division of the earth's -history, during a long _era_ or _epoch_; each system during a shorter -_period_; each formation during a still shorter _period_. In thus -reducing the periods of the organic history of the earth, and the -neptunic strata containing petrifactions deposited during those periods -into a connected system, we proceed exactly like the historian who -divides the history of nations into the three main divisions of -Antiquity, the Middle Ages, and Modern Times, and each of those sections -again into subordinate periods and epochs. But the historian by this -sharp systematic division, and by fixing the boundary of the periods by -particular dates, only seeks to facilitate his survey, and in no way -means to deny the uninterrupted connection of events and the development -of nations. Exactly the same qualification applies to our systematic -division, specification, or classification of the organic history of the -earth. Here, too, a continuous thread runs through the series of events -unbroken. We must therefore distinctly protest against the idea that by -sharply bounding the larger and smaller groups of strata, and the -periods corresponding with them, we in any way wish to adopt Cuvier's -doctrine of terrestrial revolutions, and of repeated new creations of -organic populations. That this erroneous doctrine has long since been -completely refuted by Lyell, I have already mentioned. (Compare vol. i. -p. 127.) - -The five great main divisions of the organic history of the earth, or -the palaeontological history of development, we call the primordial, -primary, secondary, tertiary, and quaternary epochs. Each is distinctly -characterized by the predominating development of certain animal and -vegetable groups in it, and we might accordingly symbolically designate -the five epochs, on the one hand by the names of the groups of the -vegetable kingdom, and on the other hand by those of the different -classes of vertebrate animals. In this case the _first_, or primordial -epoch, would be the era of the Tangles (Algae) and skull-less -Vertebrates; the _second_, or primary epoch, that of the Ferns and -Fishes; the _third_, or secondary epoch, that of Pine Forests and -Reptiles; the _fourth_, or tertiary epoch, that of Foliaceous Forests -and of Mammals; finally, the _fifth_, or quaternary epoch, the era of -Man, and his Civilization. The divisions or _periods_ which we -distinguish in each of the five _long eras_ (p. 14) are determined by -the different _systems_ of strata into which each of the five great -_rock-groups_ is divided (p. 15). We shall now take a cursory glance at -the series of these systems, and at the same time at the populations of -the five great epochs. - -The first and longest division of the organic history of the earth is -formed by the _primordial epoch_, or _the era of the Tangle Forests_. It -comprises the immense period from the first spontaneous generation, from -the origin of the first terrestrial organism, to the end of the Silurian -system of deposits. During this immeasurable space of time, which in all -probability was much longer than all the other four epochs taken -together, the three most extensive of all the neptunic systems of strata -were deposited, namely, the _Laurentian_, upon that the _Cambrian_, and -upon that the _Silurian_ system. The approximate thickness or size of -these three systems together amounts to 70,000 feet. Of these about -30,000 belong to the Laurentian, 18,000 to the Cambrian, and 22,000 to -the Silurian system. The average thickness of all the four other rock -groups, the primary, secondary, tertiary, and quaternary, taken -together, may amount at most to 60,000 feet; and from this fact alone, -apart from many other reasons, it is evident that the duration of the -primordial period was probably much longer than the duration of all the -subsequent periods down to the present day. Many thousands of millions -of years were required to deposit such masses of strata. Unfortunately, -by far the largest portion of the primordial group of strata is in the -metamorphic state (which we shall directly explain), and consequently -the petrifactions contained in them--the most ancient and most important -of all--have, to a great extent, been destroyed and become -unrecognisable. Only in one portion of the Cambrian strata have -petrifactions been preserved in a recognizable condition and in large -quantities. The most ancient of all distinctly preserved petrifactions -has been found in the lowest Laurentian strata (in the Ottawa -formation), which I shall afterwards have to speak of as the "Canadian -Life's-dawn" (Eozoon canadense). - -Although only by far the smaller portion of the primordial or -archilithic petrifactions are preserved to us in a recognizable -condition, still they possess the value of inestimable documents of the -most ancient and obscure times of the organic history of the earth. What -seems to be shown by them, in the first place, is that during the whole -of this immense period there existed only inhabitants of the waters. As -yet, at any rate, among all archilithic petrifactions, not a single one -has been found which can with certainty be regarded as an organism which -has lived on land. All the vegetable remains we possess of the -primordial period belong to the lowest of all groups of plants, to the -class of Tangles or Algae, living in water. In the warm primaeval sea, -these constituted the forests of the period, of the richness of which in -forms and density we may form an approximate idea from their present -descendants, the tangle forests of the Atlantic Sargasso sea. The -colossal tangle forests of the archilithic period supplied the place of -the forest vegetation of the mainland, which was then utterly wanting. -All the animals, also, whose remains have been found in archilithic -strata, like the plants, lived in water. Only crustacea are met with -among the animals with articulated feet, as yet no spiders and no -insects. Of vertebrate animals, only a very few remains of fishes are -known as having been found in the most recent of all primordial strata, -in the upper Silurian. But the headless vertebrate animals, which we -call _skull-less_, or _Acrania_, and out of which fishes must have been -developed, we suppose to have lived in great numbers during the -primordial epoch. Hence we may call it after the _Acrania_ as well as -after the _Tangles_. - -The _primary epoch_, or _the era of Fern Forests_, the second main -division of the organic history of the earth, which is also called the -palaeolithic or palaeozoic period, lasted from the end of the Silurian -formation of strata to the end of the Permian formation. This epoch was -also of very long duration, and again falls into three shorter periods, -during which three great systems of strata were deposited, namely, -first, the _Devonian_ system, or the old red sandstone; upon that, the -_Carboniferous_, or coal system; and upon this, the _Permian_ system. -The average thickness of these three systems taken together may amount -to about 42,000 feet, from which we may infer the immense length of time -requisite for their formation. - -The Devonian and Permian formations are especially rich in remains of -fishes, of primaeval fish as well as enamelled fish (Ganoids), but the -bony fish (Teleostei) are absent from the strata of the primary epoch. -In coal are found the most ancient remains of animals living on land, -both of articulated animals (spiders and insects) as well as of -vertebrate animals (amphibious animals, like newts and frogs). In the -Permian system there occur, in addition to the amphibious animals, the -more highly-developed reptiles, and, indeed, forms nearly related to our -lizards (Proterosaurus, etc.). But, nevertheless, we may call the -primary epoch that of _Fishes_, because these few amphibious animals and -reptiles are insignificant in comparison with the immense mass of -palaeozoic fishes. Just as Fishes predominate over the other vertebrate -animals, so _Ferns_, or Filices, predominate among the plants of this -epoch, and, in fact, real ferns and tree ferns (leafed ferns, or -Phylopteridae), as well as bamboo ferns (Calamophytae) and scaled ferns -(Lepidophytae). These ferns, which grew on land, formed the chief part of -the dense palaeolithic island forests, the fossil remains of which are -preserved to us in the enormously large strata of coal of the -Carboniferous system, and in the smaller strata of coal of the Devonian -and Permian systems. We are thus justified in calling the primary epoch -either the era of _Ferns_ or that of _Fishes_. - -The third great division of the palaeontological history of development -is formed by the _secondary epoch_, or the _era of Pine Forests_, which -is also called the mesolithic or mesozoic epoch. It extends from the end -of the Permian system to the end of the Chalk formation, and is again -divided into three great periods. The stratified systems deposited -during this period are, first and lowest, the _Triassic_ system, in the -middle the _Jura_ system, and at the top the _Cretaceous_ system. The -average thickness of these three systems taken together is much less -than that of the primary group, and amounts as a whole only to about -15,000 feet. The secondary epoch can accordingly in all probability not -have been half so long as the primary epoch. - -Just as Fishes prevailed in the primary epoch, _Reptiles_ predominated -in the secondary epoch over all other vertebrate animals. It is true -that during this period the first birds and mammals originated; at that -time, also, there existed important amphibious animals, especially the -gigantic Labyrinthodonts, in the sea the wonderful sea-dragons, or -Halisaurii, swam about, and the first fish with bones were associated -with the many primaeval fishes (Sharks) and enamelled fish (Ganoids) of -the earlier times; but the very variously developed kinds of reptiles -formed the predominating and characteristic class of vertebrate animals -of the secondary epoch. Besides those reptiles which were very nearly -related to the present living lizards, crocodiles, and turtles, there -were, during the mesolithic period, swarms of grotesquely shaped -dragons. The remarkable flying lizards, or Pterosaurii, and the colossal -land-dragons, or Dinosaurii, of the secondary epoch, are peculiar, as -they occur neither in the preceding nor in the succeeding epochs. The -secondary epoch may be called the era of _Reptiles_; but on the other -hand, it may also be called the era of _Pine Forests_, or more -accurately, of the _Gymnosperms_, that is, the epoch of _plants having -naked seeds_. For this group of plants, especially as represented by the -two important classes--the pines, or _Coniferae_, and the palm-ferns, or -_Cycadeae_--during the secondary epoch constituted a predominant part of -the forests. But towards the end of the epoch (in the Chalk period) the -plants of the pine tribe gave place to the leaf-bearing forests which -then developed for the first time. - - -SURVEY - -_Of the Palaeontological Periods, or of the Greater Divisions of the -Organic History of the Earth._ - - -I. _First Epoch_: ARCHILITHIC ERA. _Primordial Epoch._ - -(Era of Skull-less Animals and Forests of Tangles.) - - 1. Older Primordial Period or Laurentian Period. - 2. Middle Primordial Period " Cambrian Period. - 3. Later Primordial Period " Silurian Period. - - -II. _Second Epoch_: PALAEOLITHIC ERA. _Primary Epoch._ - -(Era of Fish and Fern Forests.) - - 4. Older Primary Period or Devonian Period. - 5. Mid Primary Period " Coal Period. - 6. Later Primary Period " Permian Period. - - -III. _Third Epoch_: MESOLITHIC ERA. _Secondary Epoch._ - -(Era of Reptiles and Pine Forests.) - - 7. Older Secondary Period or Trias Period. - 8. Middle Secondary Period " Jura Period. - 9. Later Secondary Period " Chalk Period. - - -IV. _Fourth Epoch_: CAENOLITHIC ERA. _Tertiary Epoch._ - -(Era of Mammals and Leaf Forests.) - - 10. Older Tertiary Period or Eocene Period. - 11. Newer Tertiary Period " Miocene Period. - 12. Recent Tertiary Period " Pliocene Period. - - -V. _Fifth Epoch_: ANTHROPOLITHIC ERA. _Quaternary Epoch._ - -(Era of Man and Cultivated Forests.) - - 13. Older Quaternary Period or Ice or Glacial Period. - 14. Newer Quaternary Period " Post Glacial Period. - 15. Recent Quaternary Period " Period of Culture. - -(The Period of Culture is the Historical Period, or the Period of -Tradition.) - -SURVEY - -_Of the Palaeontological Formations, or those Strata of the Earth's Crust -containing Petrifactions._ - - - --------------------+-------------------+----------------------+-------------- - _Rock-Groups._ | _Systems._ | _Formations._ | _Synonyms of - | | | Formations._ - --------------------+-------------------+----------------------+------------- - V. _Quaternary { | - Group_, { XIV. Recent { 36. _Present_ | Upper alluvial - or { (Alluvium) { 35. _Recent_ | Lower alluvial - Anthropolithic { | - (Anthropozoic) { XIII. Pleistocene { 34. _Post glacial_ | Upper diluvial - groups of { (Diluvium) { 33. _Glacial_ | Lower diluvial - strata { | - - - IV. _Tertiary { XII. Pliocene { 32. _Arvernian_ | Upper pliocene - Group_, { (Late tertiary) { 31. _Sub-Appenine_ | Lower pliocene - or { | - Caenolithic { XI. Miocene { 30. _Falunian_ | Upper miocene - (Caenozoic) { (New tertiary) { 29. _Limburgian_ | Lower miocene - groups of { | - strata { { 28. _Gypsum_ | Upper eocene - { X. Eocene { 27. _Nummulitic_ | Mid eocene - { (Old tertiary) { 26. _London clay_ | Lower eocene - - - { { 25. _White chalk_ | Upper cretaceous - { IX. Cretaceous { 24. _Green sand_ | Mid cretaceous - { { 23. _Neocomian_ | Lower cretaceous - III. _Secondary { { 22. _Wealden_ | The Kentish Weald - Group_, { - or { { 21. _Portlandian_ | Upper oolite - Mesolithic { VIII. Jura { 20. _Oxfordian_ | Mid oolite - (Mesozoic) { { 19. _Bath_ | Lower oolite - groups of { { 18. _Lias_ | Lias formation - strata { - { { 17. _Keuper_ | Upper trias - { VII. Trias { 16. _Muschel-kalk_ | Mid trias - { { 15. _Bunter sand_ | Lower trias - - - { VI. Permian { 14. _Zechstein_ | Upper Permian - II. _Primary { { 13. | Lower Permian - Group_, { { 12. _Carboniferous | - or { V. Carbonic sandstone_ | Upper carbonic - Palaeolithic { (coal) { 11. _Carboniferous | - (Palaeozoic) { { limestone_ | Lower carbonic - groups of { IV. Devonian { 10. _Pilton_ | Upper Devonian - strata {(Old red sandstone){ 9. _Ilfracombe_ | Mid Devonian - { 8. _Linton_ | Lower Devonian - - - I. _Primordial { { 7. _Ludlow_ | Upper Silurian - Group_, { III. Silurian { 6. _Llandovery_ | Mid Silurian - or { { 5. _Llandeilo_ | Lower Silurian - Archilithic { - (Archizoic) { II. Cambrian { 4. _Potsdam_ | Upper Cambrian - groups of { { 3. _Longmynd_ | Lower Cambrian - strata { - { I. Laurentian { 2. _Labrador_ | Upper Laurentian - { { 1. _Ottawa_ | Lower Laurentian - - -The fourth main division of the organic history of the earth, the -_tertiary epoch_, or _era of Leafed Forests_, is much shorter and less -peculiar than the three first epochs. This epoch, which is also called -the caenolithic or caenozoic epoch, extended from the end of the -cretaceous system to the end of the pliocene system. The strata -deposited during it amount only to a thickness of about 3000 feet, and -consequently are much inferior to the three first great groups. The -three systems also into which the tertiary period is subdivided are very -difficult to distinguish from one another. The oldest of them is called -_eocene_, or old tertiary; the newer _miocene_, or mid tertiary; and the -last is the _pliocene_, or later tertiary system. - -The whole population of the tertiary epoch approaches much nearer, on -the whole as well as in detail, to that of the present time than is the -case in the preceding epochs. From this time the class of _Mammals_ -greatly predominates over all other vertebrate animals. In like manner, -in the vegetable kingdom, the group--so rich in forms--of the -_Angiosperms_, or _plants with covered seeds_, predominates, and its -_leafy forests_ constitute the characteristic feature of the tertiary -epoch. The group of the Angiosperms consists of the two classes of -single-seed-lobed plants, or _Monocotyledons_, and the double-seed-lobed -plants, or _Dicotyledons_. The Angiosperms of both classes had, it is -true, made their appearance in the Cretaceous period, and mammals had -already occurred in the Jurassic period, and even in the Triassic -period; but both groups, the mammals and the plants with enclosed seeds, -did not attain their peculiar development and supremacy until the -tertiary epoch, so that it may justly be called after them. - -The fifth and last main division of the organic history of the earth is -the _quaternary epoch, or era of Civilization_, which in comparison with -the length of the four other epochs almost vanishes into nothing, though -with a comical conceit we usually call its record the "history of the -world." As the period is characterized by the development of _Man_ and -his _Culture_, which has influenced the organic world more powerfully -and with greater transforming effect than have all previous conditions, -it may also be called the era of Man, the anthropolithic or anthropozoic -period. It might also be called the era of Cultivated Forests, or -Gardens, because even at the lowest stage of human civilization man's -influence is already perceptible in the utilization of forests and their -products, and therefore also in the physiognomy of the landscape. The -commencement of this era, which extends down to the present time, is -geologically bounded by the end of the pliocene stratification. - -The neptunic strata which have been deposited during the comparatively -short quaternary epoch are very different in different parts of the -earth, but they are mostly of very slight thickness. They are reduced to -two "systems," the older of which is designated the _diluvial_, or -_pleistocene_, and the later the _alluvial_, or _recent_. The diluvial -system is again divided into two "formations," the older _glacial_ and -the more recent _post glacial_ formations. For during the older diluvial -period there occurred that extremely remarkable decrease of the -temperature of the earth which led to an extensive glaciation of the -temperate zones. The great importance which this "ice" or "glacial -period" has exercised on the geographical and topographical distribution -of organisms has already been explained in the preceding chapter (vol. -i. p. 365). But the _post glacial period_, or the more recent diluvial -period, during which the temperature again increased and the ice -retreated towards the poles, was also highly important in regard to the -present state of chorological relations. - -The biological characteristic of the quaternary epoch lies essentially -in the development and dispersion of the human organism and his culture. -Man has acted with a greater transforming, destructive, and modifying -influence upon the animal and vegetable population of the earth than any -other organism. For this reason, and not because we assign to man a -privileged exceptional position in nature in other matters, we may with -full justice designate the development of man and his civilization as -the beginning of a special and last main division of the organic history -of the earth. It is probable indeed that the corporeal development of -primaeval man out of man-like apes took place as far back as the earlier -pliocene period, perhaps even in the miocene tertiary period. But the -actual development of _human speech_, which we look upon as the most -powerful agency in the development of the peculiar characteristics of -man and his dominion over other organisms, probably belongs to that -period which on geological grounds is distinguished from the preceding -pliocene period as the pleistocene or diluvial. In fact the time which -has elapsed from the development of human speech down to the present -day, though it may comprise many thousands and perhaps hundreds of -thousands of years, almost vanishes into nothing as compared with the -immeasurable length of the periods which have passed from the beginning -of organic life on the earth down to the origin of the human race. - -The tabular view given on page 15 shows the succession of the -palaeontological rock-groups, systems, and formations, that is, the -larger and smaller neptunic groups of strata, which contain -petrifactions, from the uppermost, or Alluvial, down to the lowest, or -Laurentian, deposits. The table on page 14 presents the historical -division of the corresponding eras of the larger and smaller -palaeontological periods, and in a reversed succession, from the most -ancient Laurentian up to the most recent Quaternary period. - -Many attempts have been made to make an approximate calculation of the -number of thousands of years constituting these periods. The thickness -of the strata has been compared, which, according to experience, is -deposited during a century, and which amounts only to some few lines or -inches, with the whole thickness of the stratified masses of rock, the -succession of which we have just surveyed. This thickness, on the whole, -may on an average amount to about 130,000 feet; of these 70,000 belong -to the primordial, or archilithic; 42,000 to the primary, or -palaeolithic; 15,000 to the secondary, or mesolithic; and finally only -3,000 to the tertiary, or caenolithic group. The very small and scarcely -appreciable thickness of the quaternary, or anthropolithic deposit -cannot here come into consideration at all. On an average, it may at -most be computed as from 500 to 700 feet. But it is self evident that -all these measurements have only an average and approximate value, and -are meant to give only a rough survey of the _relative_ proportion of -the systems of strata and of the spaces of time corresponding with them. - -Now, if we divide the whole period of the organic history of the -earth--that is, from the beginning of life on the earth down to the -present day--into a hundred equal parts, and if then, corresponding to -the thickness of the systems of strata, we calculate the relative -duration of the time of the five main divisions or periods according to -percentages, we obtain the following result:-- - - - I. Archilithic, or primordial period 53.6 - II. Palaeolithic, or primary period 32.1 - III. Mesolithic, or secondary period 11.5 - IV. Caenolithic, or tertiary period 2.3 - V. Anthropolithic, or quaternary period 0.5 - ----- - Total 100.0 - - -According to this, the length of the archilithic period, during which no -land-living animals or plants as yet existed, amounts to more than one -half, more than 53 per cent.; on the other hand the length of the -anthropolithic era, during which man has existed, amounts to scarcely -one-half per cent. of the whole length of the organic history of the -earth. It is, however, quite impossible to calculate the length of these -periods, even approximately, by years. - -The thickness of the strata of mud at present deposited during a -century, and which has been used as a basis for this calculation, is of -course quite different in different parts of the earth under the -different conditions in which these deposits take place. It is very -slight at the bottom of the deep sea, in the beds of broad rivers with a -short course, and in inland seas which receive very scanty supplies of -water. It is comparatively great on the sea-shores exposed to strong -breakers, at the estuaries of large rivers with long courses, and in -inland seas with copious supplies of water. At the mouth of the -Mississippi, which carries with it a considerable amount of mud, in the -course of 100,000 years about 600 feet would be deposited. At the bottom -of the open sea, far away from the coasts, during this long period only -some few feet of mud would be deposited. Even on the sea-shores where a -comparatively large quantity of mud is deposited the thickness of the -strata formed during the course of a century may after all amount to no -more than a few inches or lines when condensed into solid stone. In any -case, however, all calculations based upon these comparisons are very -unsafe, and we cannot even approximately conceive the enormous length of -the periods which were requisite for the formation of the systems of -neptunic strata. Here we can apply only relative, not absolute, -measurements of time. - -Moreover, we should entirely err were we to consider the size of these -systems of strata alone as the measure of the actual space of time which -has elapsed during the earth's history. For the elevations and -depressions of the earth's crust have perpetually alternated with one -another, and the mineralogical and palaeontological difference--which is -perceived between each two succeeding systems of strata, and between -each two of their formations at any particular spot--corresponds in all -probability with a considerable intermediate space of many thousands of -years, during which that particular part of the earth's crust was raised -above the water. It was only after the lapse of this intermediate -period, when a new depression again laid the part in question under -water, that there occurred a new deposit of earth. As, in the mean time, -the inorganic and organic conditions on this part had undergone a -considerable transformation, the newly-formed layer of mud was -necessarily composed of different earthy constituents and enclosed -different petrifactions. - - IV. Tertiary Group of | - Strata, 3,000 feet. | Eocene, Miocene, Pliocene. - ---------------------------------+------------------------------ - | IX. Chalk System. - III. Mesolithic Group of Strata. | - | - Deposits of the | VIII. Jura System. - Secondary Epoch, about | - 15,000 feet. | - | VII. Trias System. - ---------------------------------+------------------------------ - | - | VI. Permian System. - II. Palaeolithic Group of Strata. | - | - Deposits of the | V. Coal System. - Primary Epoch, about | - 42,000 feet. | IV. Devonian System. - ---------------------------------+------------------------------ - | - | III. Silurian System, about - | 22,000 feet. - I. Archilithic Group of Strata. | - | - Deposits of the | II. Cambrian System, about - Primordial Epoch, about | 18,000 feet. - 70,000 feet. | - | I. Laurentian System, about - | 30,000 feet. - - -The striking differences which so frequently occur between the -petrifactions of two strata, lying one above another, are to be -explained in a simple and easy manner by the supposition that the same -part of the earth's surface has been exposed to _repeated depressions -and elevations_. Such alternating elevations and depressions take place -even now extensively, and are ascribed to the heaving of the fiery fluid -nucleus against the rigid crust. Thus, for example, the coast of Sweden -and a portion of the west coast of South America are constantly though -slowly rising, while the coast of Holland and a portion of the east -coast of South America are gradually sinking. The rising as well as the -sinking takes place very slowly, and in the course of a century -sometimes only amounts to some few lines, sometimes to a few inches, or -at most a few feet. But if this action continues uninterruptedly -throughout hundreds of thousands of years it is capable of forming the -highest mountains. - -It is evident that elevations and depressions, such as now can be -measured in these places, have uninterruptedly alternated one with -another in different places during the whole course of the organic -history of the earth. This may be inferred with certainty from the -geographical distribution of organisms. (Compare vol. i. p. 350.) But to -form a judgment of our palaeontological records of creation it is -extremely important to show that permanent strata can only be deposited -during a slow sinking of the ground under water, but not during its -continued rising. When the ground slowly sinks more and more below the -level of the sea, the deposited layers of mud get into continually -deeper and quieter water, where they can become condensed into stone -undisturbed. But when, on the other hand, the ground slowly rises, the -newly-deposited layers of mud, which enclose the remains of plants and -animals, again immediately come within the reach of the play of the -waves, and are soon worn away by the force of the breakers, together -with the organic remains which they on close. For this simple but very -important reason, therefore, abundant layers, in which organic remains -are preserved, can only be deposited during a continuous sinking of the -ground. When any two different formations or strata, lying one above the -other, correspond with two different periods of depression, we must -assume a long period of rising between them, of which period we know -nothing, because no fossil remains of the then living animals and plants -could be preserved. It is evident, however, that those _periods of -elevation_, which have passed without leaving any trace behind them, -deserve a no less careful consideration than the greater or less -alternating _periods of depression_, of whose organic population we can -form an approximate idea from the strata containing petrifactions. -Probably the former were not of shorter duration than the latter. - -From this alone it is apparent how imperfect our records must -necessarily be, and all the more so since it can be theoretically proved -that the variety of animal and vegetable life must have increased -greatly during those very periods of elevation. For as new tracts of -land are raised above the water, new islands are formed. Every new -island, however, is a new centre of creation, because the animals and -plants accidentally cast ashore there, find in the new territory, in -the struggle for life, abundant opportunity of developing themselves -peculiarly, and of forming new species. The formation of new species has -evidently taken place pre-eminently during these intermediate periods, -of which, unfortunately, no petrifactions could be preserved, whereas, -on the contrary, during the slow sinking of the ground there was more -chance of numerous species dying out, and of a retrogression into fewer -specific forms. The intermediate forms between the old and the -newly-forming species must also have lived during the periods of -elevation, and consequently could likewise leave no fossil remains. - -In addition to the great and deplorable gaps in the palaeontological -records of creation--which are caused by the periods of elevation--there -are, unfortunately, many other circumstances which immensely diminish -their value. I must mention here especially the _metamorphic state of -the most ancient formations_, of those strata which contain the remains -of the most ancient flora and fauna, the original forms of all -subsequent organisms, and which, therefore, would be of especial -interest. It is just these rocks--and, indeed, the greater part of the -primordial, or archilithic strata, almost the whole of the Laurentian, -and a large part of the Cambrian systems--which no longer contain any -recognizable remains, and for the simple reason that these strata have -been subsequently changed or metamorphosed by the influence of the fiery -fluid interior of the earth. These deepest neptunic strata of the crust -have been completely changed from their original condition by the heat -of the glowing nucleus of the earth, and have assumed a crystalline -state. In this process, however, the form of the organic remains -enclosed in them has been entirely destroyed. It has been preserved only -here and there by a happy chance, as in the case of the most ancient -petrifactions known, the _Eozoon canadense_, from the lowest Laurentian -strata. However, from the layers of crystalline charcoal (graphite) and -crystalline limestone (marble), which are found deposited in the -metamorphic rocks, we may with certainty conclude that petrified animal -and vegetable remains existed in them in earlier times. - -Our record of creation is also extremely imperfect from the circumstance -that only a small portion of the earth's surface has been accurately -investigated by geologists, namely, England, Germany, and France. But we -know very little of the other parts of Europe, of Russia, Spain, Italy, -and Turkey. In the whole of Europe, only some few parts of the earth's -crust have been laid open, by far the largest portion of it is unknown -to us. The same applies to North America and to the East Indies. There -some few tracts have been investigated; but of the larger portion of -Asia, the most extensive of all continents, we know almost nothing; of -Africa nothing, excepting the Cape of Good Hope and the shores of the -Mediterranean; of Australia almost nothing; and of South America but -very little. It is clear, therefore, that only quite a small portion, -perhaps scarcely the thousandth part of the whole surface of the earth, -has been palaeontologically investigated. We may therefore reasonably -hope, when more extensive geological investigations are made, which are -greatly assisted by the constructions of railroads and mines, to find a -great number of other important petrifactions. A hint that this will be -the case is given by the remarkable petrifactions found in those parts -of Africa and Asia which have been minutely investigated,--the Cape -districts and the Himalaya mountains. A series of entirely new and very -peculiar animal forms have become known to us from the rocks of these -localities. But we must bear in mind that the vast bottom of the -existing oceans is at the present time quite inaccessible to -palaeontological investigations, and that the greater part of the -petrifactions which have lain there from primaeval times will either -never be known to us, or at best only after the course of many thousands -of years, when the present bottom of the ocean shall have become -accessible by gradual elevation. If we call to mind the fact that -three-fifths of the whole surface of the earth consists of water, and -only two-fifths of land, it becomes plain that on this account the -palaeontological record must always present an immense gap. - -But, in addition to these, there exists another series of difficulties -in the way of palaeontology which arises from the nature of the organisms -themselves. In the first place, as a rule only the hard and solid parts -of organisms can fall to the bottom of the sea or of fresh waters, and -be there enclosed in the mud and petrified. Hence it is only the bones -and teeth of vertebrate animals, the calcareous shells of molluscs, the -chitinous skeletons of articulated animals, the calcareous skeletons of -star-fishes and corals, and the woody and solid parts of plants, that -are capable of being petrified. But soft and delicate parts, which -constitute by far the greater portion of the bodies of most organisms, -are very rarely deposited in the mud under circumstances favourable to -their becoming petrified, or distinctly impressing their external form -upon the hardening mud. Now, it must be borne in mind that large classes -of organisms, as for example the Medusae, the naked molluscs without -shells, a large portion of the articulated animals, almost all worms, -and even the lowest vertebrate animals, possess no firm and hard parts -capable of being petrified. In like manner the most important parts of -plants, such as the flowers, are for the most part so soft and tender -that they cannot be preserved in a recognizable form. We therefore -cannot expect to find any petrified remains of these important -organisms. Moreover, all organisms at an early stage of life are so soft -and tender that they are quite incapable of being petrified. -Consequently all the petrifactions found in the neptunic stratifications -of the earth's crust comprise altogether but a very few forms, and of -these for the most part only isolated fragments. - -We must next bear in mind that the dead bodies of the inhabitants of the -sea are much more likely to be preserved and petrified in the deposits -of mud than those of the inhabitants of fresh water and of the land. -Organisms living on land can, as a rule, become petrified only when -their corpses fall accidentally into the water and are buried at the -bottom in the hardening layers of mud. But this event depends upon very -many conditions. We cannot therefore be astonished that by far the -majority of petrifactions belong to organisms which have lived in the -sea, and that of the inhabitants of the land proportionately only very -few are preserved in a fossil state. How many contingencies come into -play here we may infer from the single fact that of many fossil mammals, -in fact of all the mammals of the secondary, or mesozoic epoch, nothing -is known except the lower jawbone. This bone is in the first place -comparatively solid, and in the second place very easily separates -itself from the dead body, which floats on the water. Whilst the body is -driven away and dissolved by the water, the lower jawbone falls down to -the bottom of the water and is there enclosed in the mud. This explains -the remarkable fact that in a stratum of limestone of the Jurassic -system near Oxford, in the slates of Stonesfield, as yet only the lower -jawbones of numerous pouched animals (Marsupials) have been found. They -are the most ancient mammals known, and of the whole of the rest of -their bodies not a single bone exists. The opponents of the theory of -development, according to their usual logic, would from this fact be -obliged to draw the conclusion that the lower jawbone was the only bone -in the body of those animals. - -Footprints are very instructive when we attempt to estimate the many -accidents which so arbitrarily influence our knowledge of fossils; they -are found in great numbers in different extensive layers of sandstone; -for example, in the red sandstone of Connecticut, in North America. -These footprints were evidently made by vertebrate animals, probably by -reptiles, of whose bodies not the slightest trace has been preserved.[1] -The impressions which their feet have left on the mud alone betray the -former existence of these otherwise unknown animals. - -The accidents which, besides these, determine the limits of our -palaeontological knowledge, may be inferred from the fact that we know of -only one or two specimens of very many important petrifactions. It is -not ten years since we became acquainted with the imperfect impression -of a bird in the Jurassic or Oolitic system, the knowledge of which -has been of the very greatest importance for the phylogeny of the whole -class of birds. All birds previously known presented a very uniformly -organized group, and showed no striking transitional forms to other -vertebrate classes, not even to the nearly related reptiles. But that -fossil bird from the Jura possessed not an ordinary bird's tail, but a -lizard's tail, and thus confirmed what had been conjectured upon other -grounds, namely, the derivation of birds from lizards. This single -fossil has thus essentially extended not only our knowledge of the age -of the class of birds, but also of their blood relationship to reptiles. -In like manner our knowledge of other animal groups has been often -essentially modified by the accidental discovery of a single fossil. The -palaeontological records must necessarily be exceedingly imperfect, -because we know of so very few examples, or only mere fragments of very -many important fossils. - -Another and very sensible gap in these records is caused by the -circumstance that the _intermediate forms_ which connect the different -species have, as a rule, not been preserved, and for the simple reason -that (according to the principle of divergence of character) they were -less favoured in the struggle for life than the most divergent -varieties, which had developed out of one and the same original form. -The intermediate links have, on the whole, always died out _rapidly_, -and have but rarely been preserved as fossils. On the other hand, the -most divergent forms were able to maintain themselves in life for a -longer period as independent species, to propagate more numerously, and -consequently to be more readily petrified. But this does not exclude the -fact that in _some_ cases the connecting intermediate forms of the -species have been preserved so perfectly petrified, that even now they -cause the greatest perplexity and occasion endless disputes among -systematic palaeontologists about the arbitrary limits of species. - -An excellent example of this is furnished by the celebrated and very -variable fresh-water snail from the Stuben Valley, near Steinheim, in -Wuertemburg, which has been described sometimes as _Paludina_, sometimes -as _Valvata_, and sometimes as _Planorbis multiformis_. The snow-white -shells of these small snails constitute more than half of the mass of -the tertiary limestone hills, and in this one locality show such an -astonishing variety of forms, that the most divergent extremes might be -referred to at least twenty entirely different species. But all these -extreme forms are united by such innumerable intermediate forms, and -they lie so regularly above and beside one another, that Hilgendorf was -able, in the clearest manner, to unravel the pedigree of the whole group -of forms. In like manner, among very many other fossil species (for -example, many ammonites, terebratulae, sea urchins, lily encrinites, -etc.) there are such masses of connecting intermediate forms, that they -reduce the "dealers in fossil species" to despair. - -When we weigh all the circumstances here mentioned, the number of which -might easily be increased, it does not appear astonishing that the -natural accounts or records of creation formed by petrifactions are -extremely defective and incomplete. But nevertheless, the petrifactions -actually discovered are of the greatest value. Their significance is of -no less importance to the natural history of creation than the -celebrated inscription on the Rosetta stone, and the decree of Canopus, -are to the history of nations--to archaeology and philology. Just as it -has become possible by means of these two most ancient inscriptions to -reconstruct the history of ancient Egypt, and to decipher all -hieroglyphic writings, so in many cases a few bones of an animal, or -imperfect impressions of a lower animal or vegetable form, are -sufficient for us to gain the most important starting-points in the -history of the whole group, and in the search after their pedigree. A -couple of small back teeth, which have been found in the Keuper -formation of the Trias, have of themselves alone furnished a sure proof -that mammals existed even in the Triassic period. - -Of the incompleteness of the geological accounts of creation, Darwin, -agreeing with Lyell, the greatest of all recent geologists, says:-- - -"I look at the geological record as a history of the world imperfectly -kept, and written in a changing dialect; of this history we possess the -last volume alone, relating only to two or three countries. Of this -volume, only here and there a short chapter has been preserved; and of -each page, only here and there a few lines. Each word of the -slowly-changing language, more or less different in the successive -chapters, may represent the forms of life which are entombed in our -consecutive formations, and which falsely appear to us to have been -abruptly introduced. On this view, the difficulties above discussed are -greatly diminished, or even disappear."--_Origin of Species_, 6th -Edition, p. 289. - -If we bear in mind the exceeding incompleteness of palaeontological -records, we shall not be surprised that we are still dependent upon so -many uncertain hypotheses when actually endeavouring to sketch the -pedigree of the different organic groups. However, we fortunately -possess, besides fossils, other records of the history of the origin of -organisms, which in many cases are of no less value, nay, in several -cases are of much greater value, than fossils. By far the most important -of these other records of creation is, without doubt, _ontogeny_, that -is, the history of the development of the organic individual (embryology -and metamorphology). It briefly repeats in great and marked features the -series of forms which the ancestors of the respective individuals have -passed through from the beginning of their tribe. We have designated the -palaeontological history of the development of the ancestors of a living -form as the history of a tribe, or _phylogeny_, and we may therefore -thus enunciate this exceedingly important _biogenetic fundamental -principle_: "_Ontogeny is a short and quick repetition, or -recapitulation, of Phylogeny, determined by the laws of Inheritance and -Adaptation_." As every animal and every plant from the beginning of its -individual existence passes through a series of different forms, it -indicates in rapid succession and in general outlines the long and -slowly changing series of states of form which its progenitors have -passed through from the most ancient times. (Gen. Morph. ii. 6, 110, -300.) - -It is true that the sketch which the ontogeny of organisms gives us of -their phylogeny is in most cases more or less obscured, and all the more -so the more Adaptation, in the course of time, has predominated over -Inheritance, and the more powerfully the law of abbreviated inheritance, -and the law of correlative adaptation, have exerted their influence. -However, this does not lessen the great value which the actual and -faithfully preserved features of that sketch possess. _Ontogeny is of -the most inestimable value for the knowledge of the earliest -palaeontological conditions of development_, just because no petrified -remains of the most ancient conditions of the development of tribes and -classes have been preserved. These, indeed, could not have been -preserved on account of the soft and tender nature of their bodies. No -petrifactions could inform us of the fundamental and important fact -which ontogeny reveals to us, that the most ancient common ancestors of -all the different animal and vegetable species were quite simple cells -like the egg-cell. No petrifaction could prove to us the immensely -important fact, established by ontogeny, that the simple increase, the -formation of cell-aggregates and the differentiation of those cells, -produced the infinitely manifold forms of multicellular organisms. Thus -ontogeny helps us over many and large gaps in palaeontology. - -[Illustration: Hand of Nine different Mammals. Pl. IV. - -_1. Man_, _2. Gorilla_, _3. Orang_, _4. Dog_, _5. Seal_, _6. Porpoise_, -_7. Bat_, _8. Mole_, _9. Duck-bill_.] - -To the invaluable records of creation furnished by palaeontology and -ontogeny are added the no less important evidences for the blood -relationship of organisms furnished by _comparative anatomy_. When -organisms, externally very different, nearly agree in their internal -structure, one may with certainty conclude that the agreement has its -foundation in Inheritance, the dissimilarity its foundation in -Adaptation. Compare, for example, the hands and fore paws of the nine -different animals which are represented on Plate IV., in which the bony -skeleton in the interior of the hand and of the five fingers is visible. -Everywhere we find, though the external forms are most different, the -same bones, and among them the same number, position, and connection. It -will perhaps appear very natural that the hand of _man_ (Fig. 1) differs -very little from that of the _gorilla_ (Fig. 2) and of the -_orang-outang_ (Fig. 3), his nearest relations. But it will be more -surprising if the fore feet of the _dog_ also (Fig. 4), as well as the -breast-fin (the hand) of the _seal_ (Fig. 5), and of the _dolphin_ (Fig. -6), show essentially the same structure. And it will appear still more -wonderful that even the wing of the _bat_ (Fig. 7), the shovel-feet of -the _mole_ (Fig. 8), and the fore feet of the _duck-bill_ -(Ornithorhynchus) (Fig. 9), the most imperfect of all mammals, is -composed of entirely the same bones, only their size and form being -variously changed. Their number, the manner of their arrangement and -connection has remained the same. (Compare also the explanation of Plate -IV., in the Appendix.) It is quite inconceivable that any other cause, -except the common inheritance of the part in question from common -ancestors, could have occasioned this wonderful homology or similarity -in the essential inner structure with such different external forms. -Now, if we go down further in the system below the mammals, and find -that even the wings of birds, the fore feet of reptiles and amphibious -animals, are composed of essentially the same bones as the arms of man -and the fore legs of the other mammals, we can, from this circumstance -alone, with perfect certainty, infer the common origin of all these -vertebrate animals. Here, as in all other cases, the degree of the -internal agreement in the form discloses to us the degree of blood -relationship. - - - - -CHAPTER XVI. - -PEDIGREE AND HISTORY OF THE KINGDOM OF THE PROTISTA. - - - Special Mode of Carrying out the Theory of Descent in the - Natural System of Organisms.--Construction of Pedigrees.--Descent - of all Many-Celled from Single-Celled Organisms.--Descent of - Cells from Monera.--Meaning of Organic Tribes, or Phyla.--Number - of the Tribes in the Animal and Vegetable Kingdoms.--The - Monophyletic Hypothesis of Descent, or the Hypothesis of one - Common Progenitor, and the Polyphyletic Hypothesis of Descent, - or the Hypothesis of Many Progenitors.--The Kingdom of Protista, - or Primaeval Beings.--Eight Classes of the Protista - Kingdom.--Monera, Amoebae, or Protoplastae.--Whip-swimmers, or - Flagellata.--Ciliated-balls, or Catallacta.--Labyrinth-streamers, - or Labyrinthuleae.--Flint-cells, or Diatomeae.--Mucous-moulds, or - Myxomycetes.--Root-footers (Rhizopoda).--Remarks on the General - Natural History of the Protista: Their Vital Phenomena, - Chemical Composition, and Formation (Individuality and - Fundamental Form).--Phylogeny of the Protista Kingdom - - -By a careful comparison of the individual and the palaeontological -development, as also by the comparative anatomy of organisms, by the -comparative examination of their fully developed structural -characteristics, we arrive at the knowledge of the degrees of their -different structural relationships. By this, however, we at the same -time obtain an insight into their true _blood relationship_, which, -according to the Theory of Descent, is the real reason of the structural -relationship. Hence by collecting, comparing, and employing the -empirical results of embryology, palaeontology, and anatomy for -supplementing each other, we arrive at an approximate knowledge of "the -Natural System," which, according to our views, is the _pedigree_ of -organisms. It is true that our human knowledge, in all things -fragmentary, is especially so in this case, on account of the extreme -incompleteness and defectiveness of the records of creation. However, we -must not allow this to discourage us, or to deter us from undertaking -this highest problem of biology. Let us rather see how far it may even -now be possible, in spite of the imperfect state of our embryological, -palaeontological, and anatomical knowledge, to establish a probable -scheme of the genealogical relationships of organisms. - -Darwin in his book gives us no answer to these special questions of the -Theory of Descent; at the conclusion he only expresses his conjecture -"that animals have descended from at most only four or five progenitors, -and plants from an equal or less number." But as these few aboriginal -forms still show traces of relationship, and as the animal and vegetable -kingdoms are connected by intermediate transitional forms, he arrives -afterwards at the opinion "that probably all the organic beings which -have ever lived on the earth have descended from some one primordial -form, into which life was first breathed by the Creator." Like Darwin, -all other adherents of the Theory of Descent have only treated it in a -general way, and not made the attempt to carry it out specially, and to -treat the "Natural System" actually as the pedigree of organisms. If, -therefore, we venture upon this difficult undertaking, we must take up -independent ground. - -Four years ago I set up a number of hypothetical genealogies for the -larger groups of organisms in the systematic introduction to my General -History of Development (Gen. Morph. vol. ii.), and thereby, in fact, -made the first attempt actually to construct the pedigrees of organisms -in the manner required by the theory of development. I was quite -conscious of the extreme difficulty of the task, and as I undertook it -in spite of all discouraging obstacles, I claim no more than the merit -of having made the first attempt and given a stimulus for other and -better attempts. Probably most zoologists and botanists were but little -satisfied with this beginning, and least so in reference to the special -domain in which each one is specially at work. However, it is certainly -in this case much easier to blame than to produce something better, and -what best proves the immense difficulty of this infinitely complicated -task is the fact that no naturalist has as yet supplied the place of my -pedigrees by better ones. But, like all other scientific hypotheses -which serve to explain facts, my genealogical hypotheses may claim to be -taken into consideration until they are replaced by better ones. - -I hope that this replacement will very soon take place; and I wish for -nothing more than that my first attempt may induce very many naturalists -to establish more accurate pedigrees for the individual groups, at least -in the special domain of the animal and vegetable kingdom which happens -to be well known to one or other of them. By numerous attempts of this -kind our genealogical knowledge, in the course of time, will slowly -advance and approach more towards perfection, although it can with -certainty be foreseen that we shall never arrive at a complete -pedigree. We lack, and shall ever lack, the indispensable -palaeontological foundations. The most ancient records will ever remain -sealed to us, for reasons which have been previously mentioned. The most -ancient organisms which arose by spontaneous generation--the original -parents of all subsequent organisms--must necessarily be supposed to -have been Monera--simple, soft, albuminous lumps, without structure, -without any definite forms, and entirely without any hard and formed -parts. They and their next offspring were consequently not in any way -capable of being preserved in a petrified condition. But we also lack, -for reasons discussed in detail in the preceding chapter, by far the -greater portion of the innumerable palaeontological documents, which are -really requisite for a safe reconstruction of the history of animal -tribes, or phylogeny, and for the true knowledge of the pedigree of -organisms. If we, therefore, in spite of this, venture to undertake -their hypothetical construction, we must chiefly depend for guidance on -the two other series of records which most essentially supplement the -palaeontological archives. These are ontogeny and comparative anatomy. - -If thoughtfully and carefully we consult these most valuable records, we -at once perceive what is exceedingly significant, namely, that by far -the greater number of organisms, especially all higher animals and -plants, are composed of a great number of cells, and that they originate -out of an egg, and that this egg, in animals as well as in plants, is a -single, perfectly simple cell--a little lump of albuminous constitution, -in which another albuminous corpuscle, the cell-kernel, is enclosed. -This cell containing its kernel grows and becomes enlarged. By division -it forms an accumulation of cells, and out of these, by division of -labour (as has previously been described), there arise the numberless -different forms which are presented to us in the fully developed animal -and vegetable species. This immensely important process--which we may -follow step by step, with our own eyes, any day in the embryological -development of any animal or vegetable individual, and which as a rule -is by no means considered with the reverence it deserves--informs us -more surely and completely than all petrifactions could do as to the -original palaeontological development of all many-celled organisms, that -is, of all higher animals and plants. For as ontogeny, or the -embryological development of every single individual, is essentially -only a recapitulation of phylogeny, or the palaeontological development -of its chain of ancestors, we may at once, with full assurance, draw the -simple and important conclusion, that _all many-celled animals and -plants were originally derived from single-celled organisms_. The -primaeval ancestors of man, as well as of all other animals, and of all -plants composed of many cells, were simple cells living isolated. This -invaluable secret of the organic pedigree is revealed to us with -infallible certainty by the egg of animals, and by the true egg-cell of -plants. When the opponents of the Theory of Descent assert it to be -miraculous and inconceivable that an exceedingly complicated many-celled -organism could, in the course of time, have proceeded from a simple -single-celled organism, we at once reply that we may see this incredible -miracle at any moment, and follow it with our own eyes. For the -embryology of animals and plants visibly presents to our eyes in the -shortest space of time the same process as that which has taken place in -the origin of the whole tribe during the course of enormous periods of -time. - -Upon the ground of embryological records, therefore, we can with full -assurance maintain that all many-celled, as well as single-celled, -organisms are originally descended from simple cells; connected with -this, of course, is the conclusion that the most ancient root of the -animal and vegetable kingdom was common to both. For the different -primaeval "original cells" out of which the few different main groups or -tribes have developed, only acquired their differences after a time, and -were descended from a common "primaeval cell." But where did those few -"original cells," or the one primaeval cell, come from? For the answer to -this fundamental genealogical question we must return to the theory of -plastids and the hypothesis of spontaneous generation which we have -already discussed (vol. i. p. 327). - -As was then shown, we cannot imagine _cells_ to have arisen by -spontaneous generation, but only _Monera_, those primaeval creatures of -the simplest kind conceivable, like the still living Protamoebae, -Protomyxae, etc. (vol. i. p. 186, Fig. 1). Only such corpuscules of mucus -without component parts--whose whole albuminous body is as homogeneous -in itself as an inorganic crystal, but which nevertheless fulfills the -two organic fundamental functions of nutrition and propagation--could -have directly arisen out of inorganic matter by autogeny at the -beginning (we may suppose) of the Laurentian period. While some Monera -remained at the original simple stage of formation, others gradually -developed into cells by the inner kernel of the albuminous mass becoming -separated from the external cell-substance. In others, by -differentiation of the outermost layer of the cell-substance, an -external covering (membrane, or skin) was formed round simple cytods -(without kernel), as well as round naked cells (containing a kernel). By -these two processes of separation in the simple primaeval mucus of the -Moneron body, by the formation of a kernel in the interior and a -covering on the outer surface of the mass of plasma, there arose out of -the original most simple cytods, or Monera, those four different species -of plastids, or individuals, of the first order, from which, by -differentiation and combination, all other organisms could afterwards -develop themselves. (Compare vol. i. p. 347.) - -The question now forces itself upon us, Are all organic cytods and -cells, and consequently also those "original cells" which we previously -considered to be the primary parents of the few great main groups of the -animal and vegetable kingdoms, descended from a single original form of -Moneron, or were there several different organic primary forms, each -traceable to a peculiar independent species of Moneron which originated -by spontaneous generation? In other words, _Is the whole organic world -of a common origin, or does it owe its origin to several acts of -spontaneous generation?_ This fundamental question of genealogy seems at -first sight to be of exceeding importance. But on a more accurate -examination, we shall soon see that this is not the case, and that it is -in reality a matter of very subordinate importance. - -Let us now pass on to examine and clearly limit our conception of an -_organic tribe_. By _tribe_, or _phylum_, we understand all those -organisms of whose blood relationship and descent from a common primary -form there can be no doubt, or whose relationship, at least, is most -probable from anatomical reasons, as well as from reasons founded on -historical development. Our tribes, or phyla, according to this idea, -essentially coincide with those few "great classes," or "main classes," -of which Darwin also thinks that each contains only organisms related by -blood, and of which, both in the animal and in the vegetable kingdoms, -he only assumes either four or five. In the animal kingdom these tribes -would essentially coincide with those four, five, or six main divisions -which zoologists, since Baer and Cuvier, have distinguished as "main -forms, general plans, branches, or sub-kingdoms" of the animal kingdom. -(Compare vol. i. p. 53.) Baer and Cuvier distinguished only four of them, -namely:--1. The vertebrate animals (Vertebrata); 2. The articulated -animals (Articulata); 3. The molluscous animals (Mollusca); and 4. The -radiated animals (Radiata). At present six are generally distinguished, -since the tribe of the articulated animals is divided into two tribes, -those possessing articulated feet (Arthropoda), and the worms (Vermes); -and in like manner the tribe of radiated animals is subdivided into the -two tribes of the star animals (Echinodermata) and the animal-plants -(Zoophyta). Within each of these six tribes, all the included animals, -in spite of great variety in external form and inner structure, -nevertheless possess such numerous and important characteristics in -common, that there can be no doubt of their blood relationship. The same -applies also to the six great main classes which modern botany -distinguishes in the vegetable kingdom, namely:--1. Flowering plants -(Phanerogamia); 2. Ferns (Filicinae); 3. Mosses (Muscinae); 4. Lichens -(Lichenes); 5. Fungi (Fungi); and 6. Water-weeds (Algae). The last three -groups, again, show such close relations to one another, that by the -name of "Thallus plants" they may be contrasted with the three first -main classes, and consequently the number of phyla, or main groups, of -the vegetable kingdom may be reduced to the number of four. Mosses and -ferns may likewise be comprised as "Prothallus plants" (Prothallophyta), -and thereby the number of plant tribes reduced to three--Flowering -plants, Prothallus plants, and Thallus plants. - -Very important facts in the anatomy and the history of development, both -in the animal and vegetable kingdoms, support the supposition that even -these few main classes or tribes are connected at their roots, that is, -that the lowest and most ancient primary forms of all three are related -by blood to one another. Nay, by a further examination we are obliged to -go still a step further, and to agree with Darwin's supposition, that -even the two pedigrees of the animal and vegetable kingdom are connected -at their lowest roots, and that the lowest and most ancient animals and -plants are derived from a single common primary creature. According to -our view, this common primaeval organism can have been nothing but a -Moneron which took its origin by spontaneous generation. - -In the mean time we shall at all events be acting cautiously if we avoid -this last step, and assume true blood relationship only within each -tribe, or phylum, where it has been undeniably and surely established by -facts in comparative anatomy, ontogeny, and phylogeny. But we may here -point to the fact that two different fundamental forms of genealogical -hypothesis are possible, and that all the different investigations of -the Theory of Descent in relation to the origin of organic groups of -forms will, in future, tend more and more in one or the other of these -directions. The unitary, or _monophyletic_, hypothesis of descent will -endeavour to trace the first origin of all individual groups of -organisms, as well as their totality, to a single common species of -Moneron which originated by spontaneous generation (vol. i. p. 343). The -multiple, or _polyphyletic_, hypothesis of descent, on the other hand, -will assume that several different species of Monera have arisen by -spontaneous generation, and that these gave rise to several different -main classes (tribes, or phyla) (vol. i. p. 348). The apparently great -contrast between these two hypotheses is in reality of very little -importance. For both the monophyletic and the polyphyletic hypothesis of -descent must necessarily go back to the Monera as the most ancient root -of the one or of the many organic tribes. But as the whole body of a -Moneron consists only of a simple, formless mass, without component -particles, made up of a single albuminous combination of carbon, it -follows that the differences of the different Monera can only be of a -chemical nature, and can only consist in a different atomic composition -of that mucous albuminous combination. But these subtle and complicated -differences of mixture of the infinitely manifold combinations of -albumen are not appreciable by the rude and imperfect means of human -observation and are, consequently, at present of no further interest to -the task we have in hand. - -The question of the monophyletic or polyphyletic origin will constantly -recur within each individual tribe, where the origin of a smaller or of -a larger group is discussed. In the vegetable kingdom, for example, some -botanists will be inclined to derive all flowering plants from a single -form of fern, while others will prefer the idea that several different -groups of Phanerogama have sprung from several different groups of -ferns. In like manner, in the animal kingdom, some zoologists will be -more in favour of the supposition that all placental animals are derived -from a single pouched animal; others will be more in favour of the -opposite supposition, that several different groups of placental animals -have proceeded from several different pouched animals. In regard to the -human race itself, some will prefer to derive it from a single form of -ape, while others will be more inclined to the idea that several -different races of men have arisen, independently of one another, out of -several different species of ape. Without here expressing our opinion in -favour of either the one or the other conception, we must, nevertheless, -remark that in general _the monophyletic hypothesis of descent deserves -to be preferred to the polyphyletic hypothesis of descent_. In -accordance with the chorological proposition of a single "centre of -creation" or of a single primaeval home for most species (which has -already been discussed), we may be permitted to assume that the original -form of every larger or smaller natural group only originated _once_ in -the course of time, and only in _one part_ of the earth. We may safely -assume this simple original root, that is, the monophyletic origin, in -the case of all the more highly developed groups of the animal and -vegetable kingdoms. (Compare vol. i. p. 353.) But it is very possible -that the more complete Theory of Descent of the future will involve the -polyphyletic origin of very many of the low and imperfect groups of the -two organic kingdoms. - -For these reasons I consider it best, in the mean time, to adopt the -_monophyletic hypothesis of descent_ both for the animal and for the -vegetable kingdom. Accordingly, the above-mentioned six tribes, or -phyla, of the animal kingdom must be connected at their lowest root, -and likewise the three or six main classes, or phyla, of the vegetable -kingdom must be traced to a common and most ancient original form. How -the connection of these tribes is to be conceived I shall explain in the -succeeding chapters. But before proceeding to this, we must occupy -ourselves with a very remarkable group of organisms, which cannot -without artificial constraint be assigned either to the pedigree of the -vegetable or to that of the animal kingdom. These interesting and -important organisms are the _primary creatures_, or _Protista_. - -All organisms which we comprise under the name of Protista show in their -external form, in their inner structure, and in all their vital -phenomena, such a remarkable mixture of animal and vegetable properties, -that they cannot with perfect justice be assigned either to the animal -or to the vegetable kingdom; and for more than twenty years an endless -and fruitless dispute has been carried on as to whether they are to be -assigned to this or that kingdom. Most of Protista are so small that -they can scarcely, if at all, be perceived with the naked eye. Hence the -majority of them have only become known during the last fifty years, -since by the help of the improved and general use of the microscope -these minute organisms have been more frequently observed and more -accurately examined. However, no sooner were they better known than -endless disputes arose about their real nature and their position in the -natural system of organisms. Many of these doubtful primary creatures -botanists defined as animals, and zoologists as plants; neither of the -two would own them. Others, again, were declared by botanists to be -plants, and by zoologists to be animals; each claimed them. These -contradictions are not altogether caused by our imperfect knowledge of -the Protista, but in reality by their true nature. Indeed, most Protista -present such a confused mixture of several animal and vegetable -characteristics, that each investigator may arbitrarily assign them -either to the animal or vegetable kingdom. Accordingly as he defines -these two kingdoms, and as he looks upon this or that characteristic as -determining the animal or vegetable nature, he will assign the -individual classes of Protista in one case to the animal and in another -to the vegetable kingdom. But this systematic difficulty has become an -inextricable knot by the fact that all more recent investigations on the -lowest organisms have completely effaced, or at least destroyed, the -sharp boundary between the animal and vegetable kingdom which had -hitherto existed, and to such a degree that its restoration is possible -only by means of a completely artificial definition of the two kingdoms. -But this definition could not be made so as to apply to many of the -Protista. - -For this and other reasons it is, in the mean time, best to exclude the -doubtful beings from the animal as well as from the vegetable kingdom, -and to comprise them in a third organic kingdom standing midway between -the two others. This intermediate kingdom I have established as the -_Kingdom of the Primary Creatures_ (Protista), when discussing general -anatomy in the first volume of my General Morphology, pp. 191-238. In my -Monograph of the Monera,(15) I have recently treated of this kingdom, -having somewhat changed its limits, and given it a more accurate -definition. Of independent classes of the kingdom Protista, we may at -present distinguish the following:-- - -1. The still living Monera; 2. The Amoeboidea, or Protoplasts; 3. The -Whip-swimmers, or Flagellata; 4. The Flimmer-balls, or Catallacta; 5. -The Tram-weavers, or Labyrinthuleae; 6. The Flint-cells, or Diatomeae; 7. -The Slime-moulds, or Myxomycetes; 8. The Ray-streamers, or Rhizopoda. - -The most important groups at present distinguishable in these eight -classes of Protista are named in the systematic table on p. 51. Probably -the number of these Protista will be considerably increased in future -days by the progressive investigations of the ontogeny of the simplest -forms of life, which have only lately been carried on with any great -zeal. With most of the classes named we have become intimately -acquainted only during the last ten years. The exceedingly interesting -Monera and Labyrinthuleae, as also the Catallacta, were indeed discovered -only a few years ago. It is probable also that very numerous groups of -Protista have died out in earlier periods, without having left any -fossil remains, owing to the very soft nature of their bodies. We might -add to the Protista from the still living lowest groups of -organisms--the Fungi; and in so doing should make a very large addition -to its domain. Provisionally we shall leave them among plants, though -many naturalists have separated them altogether from the vegetable -kingdom. - -_The pedigree of the kingdom Protista_ is still enveloped in the -greatest obscurity. The peculiar combination of animal and vegetable -properties, the indifferent and uncertain character of their relations -of forms and vital phenomena, together with a number of several very -peculiar features which separate most of the subordinate classes sharply -from the others, at present baffle every attempt distinctly to make out -their blood relationships with one another, or with the lowest animals -on the one hand, and with the lowest plants on the other hand. It is not -improbable that the classes specified, and many other unknown classes of -Protista, represent quite independent organic tribes, or phyla, each of -which has independently developed from one, perhaps from various, Monera -which have arisen by spontaneous generation. If we do not agree to this -polyphyletic hypothesis of descent, and prefer the monophyletic -hypothesis of the blood relationship of all organisms, we shall have to -Look upon the different classes of protista as the lower small -off-shoots of the root, springing from the same simple monera root, out -of which arose the two mighty and many-branched pedigrees of the animal -kingdom on the one hand, and of the vegetable kingdom on the other. -(compare pp. 74, 75.) before i enter into this difficult question more -accurately, it will be appropriate to premise something further as to -the contents of the classes of protista given on the next page, and -their general natural history. - - -SYSTEMATIC SURVEY - -_Of the Larger and Smaller Groups of the Kingdom Protista._ - - ----------------+--------------------+------------------+----------------- - _Classes of | _Systematic Name | _Orders of | _A name of a - the Protista | of the Classes_. | Families of the | Genus - Kingdom._ | | Classes._ | as an example._ - ----------------+--------------------+------------------+----------------- - { 1. Gymnomonera Protogenes - 1. MONERS Monera { 2. Lepomonera Protomyxa - - { 1. Gymnamoebae Amoeba - 2. PROTOPLASTS Amoeboida { 2. Leptamoebae Arcella - { 3. Gregarinae Monocystis - - { 1. Nudiflagellata Euglena - 3. WHIP-SWIMMERS Flagellata { 2. Cilioflagellata Peridinium - - 4. FLIMMER-BALLS Catallacta 1. Catallacta Magosphaera - - 5. TRAM-WEAVERS Labyrinthuleae 1. Labyrinthuleae Labyrinthula - - { 1. Striata Navicula - 6. FLINT-CELLS Diatomea { 2. Vittata Tabellaria - { 3. Areolata Coscinodiscus - - { 1. Physareae AEthalium - 7. SLIME-MOULDS Myxomycetes { 2. Stemoniteae Stemonitis - { 3. Trichiaceae Arcyria - { 4. Lycogaleae Reticularia - - { I. Acyttaria { 1. Monothalamia Gromia - { { 2. Polythalamia Nummulina - 8. RAY-STREAMERS { - OR RHIZOPODS. { II. Heliozoa 1. Heliozoa Actinosphaerium - (Root-feet) { - { { 1. Monocyttaria Cyrtidosphaera - { III. Radiolaria { 2. Polycyttaria Collosphaera - - -[Illustration: FIG. 8.--Protamoeba primitiva, a fresh-water Moneron, -much enlarged. _A._ The entire Moneron with its form-changing processes. -_B._ It begins to divide itself into two halves. _C._ The division of -the two halves is completed, and each now represents an independent -individual.] - -It will perhaps seem strange that I should here again begin with the -remarkable _Monera_ as the first class of the Protista kingdom, as I of -course look upon them as the most ancient primary forms of all organisms -without exception. Still, what are we otherwise to do with the _still -living Monera_? We know nothing of their palaeontological origin, we know -nothing of any of their relations to lower animals or plants, and we -know nothing of their possible capability of developing into higher -organisms. The simple and homogeneous little lump of slime or mucus -which constitutes their entire body (Fig. 8) is the most ancient and -original form of animal as well as of vegetable plastids. Hence it would -evidently be just as arbitrary and unreasonable to assign them to the -animal as it would be to assign them to the vegetable kingdom. In any -case we shall for the present be acting more cautiously and critically -if we comprise the still living Monera--whose number and distribution is -probably very great--as a special and independent class, contrasting -them with the other classes of the kingdom Protista, as well as with the -animal kingdom. Morphologically considered, the Monera--on account of -the perfect homogeneity of the albuminous substance of their bodies, on -account of their utter want of heterogeneous particles--are more closely -connected with anorgana than with organisms, and evidently form the -transition between the inorganic and organic world of bodies, as is -necessitated by the hypothesis of spontaneous generation. I have -described and given illustrations of the forms and vital phenomena of -the still living Monera (Protamoeba, Protogenes, Protomyxa, etc.) in my -Monograph of the Monera,(15) and have briefly mentioned the most -important facts in the eighth chapter (vol. i. pp. 183-187). Therefore, -only by way of a specimen, I here repeat the drawing of the fresh-water -Protamoeba (Fig. 8). The history of the life of an orange-red _Protomyxa -adrantiaca_, which I observed at Lanzerote, one of the Canary Islands, -is given in Plate I. (see its explanation in the Appendix). Besides -this, I here add a drawing of the form of Bathybius, that remarkable -Moneron discovered by Huxley, which lives in the greatest depths of the -sea in the shape of naked lumps of protoplasm and reticular mucus (vol. -i. p. 344). - -[Illustration: FIG. 9.--Bathybius Haeckelii, the "creature of primaeval -slime," from the greatest depths of the sea. The figure, which is -greatly magnified, only shows that form of the Bathybius which consists -of a naked network of protoplasm, without the discoliths and cyatholiths -which are found in other forms of the same Moneron, and which perhaps -may be considered as the products of its secretion.] - -The _Amoebae_ of the present day, and the organisms most closely -connected with them, _Arcellidae_ and _Gregarinae_, which we here unite as -a second class of Protista under the name of _Amoeboidea_ (Protoplasta), -present no fewer genealogical difficulties than the Monera. These -primary creatures are at present usually placed in the animal kingdom -without its in reality being understood why. For simple naked -cells--that is, shell-less plastids with a kernel--occur as well among -real plants as real animals. The generative cells, for example, in many -Algae (spores and eggs) exist for a longer or shorter time in water in -the form of naked cells with a kernel, which cannot be distinguished at -all from the naked eggs of many animals (for example, those of the -Siphonophorous Medusae). (Compare the figure of a naked egg of a -bladder-wrack in Chapter xvii. p. 90.) In reality every naked simple -cell, whether it proceeds from an animal or vegetable body, cannot be -distinguished from an independent Amoeba. For an Amoeba is nothing but a -simple primary cell, a naked little lump of cell-matter, or plasma, -containing a kernel. The contractility of this plasma, which the free -Amoeba shows in stretching out and drawing in its changing processes, is -a general vital property of the organic plasma of all animal as well as -of all vegetable plastids. When a freely moving Amoeba, which -perpetually changes its form, passes into a state of rest, it draws -itself together into the form of a globule, and surrounds itself with a -secreted membrane. It can then be as little distinguished from an animal -egg as from a simple globular vegetable cell (Fig. 10 _A_). - -[Illustration: FIG. 10.--Amoeba sphaerococcus, greatly magnified. A -fresh-water Amoeba without a contractile vacuole. _A._ The enclosed -Amoeba in the state of a globular lump of plasma (_c_) enclosing a -kernel and a kernel-speck (_a_). The simple cell is surrounded by a -cyst, or cell membrane (_d_). _B._ The free Amoeba, which has burst and -left the cyst, or cell-membrane. _C._ It begins to divide by its kernel -parting into two kernels, and the cell-substance between the two -contracting. _D._ The division is completed, and the cell-substance has -entirely separated into two bodies. (_Da_ and _Db_).] - -Naked cells, with kernels, like those represented in Fig. 10 _B_, which -are continuously changing, stretching out and drawing in formless, -finger-like processes, and which are on this account called amoeboid, -are found frequently and widely dispersed in fresh water and in the sea; -nay, are even found creeping on land. They take their food in the same -way as was previously described in the case of the Protamoeba (vol. i. -p. 186). Their propagation by division can sometimes be observed. (Fig. -10 _C_, _D_.) I have described the processes in an earlier chapter (vol. -i. p. 187). Many of these formless Amoebae have lately been recognized as -the early stages of development of other Protista (especially the -Myxomycetae), or as the freed cells of lower animals and plants. The -colourless blood-cells of animals, for example, those of human blood, -cannot be distinguished from Amoebae. They, like the latter, can receive -solid corpuscles into their interior, as I was the first to show by -feeding them with finely divided colouring matters (Gen. Morph. i. 271). -However, other Amoebae (like the one given in Fig. 10) seem to be -independent "good species," since they propagate themselves unchanged -throughout many generations. Besides the real, or _naked_, Amoebae -(Gymnamoebae), we also find widely diffused in fresh water _case-bearing_ -Amoebae (Lepamoebae), whose naked plasma body is _partially_ protected by -a more or less solid shell (Arcella), sometimes even by a case -(Difflugia) composed of small stones. Lastly, we frequently find in the -body of many lower animals parasitic Amoebae (Gregarinae), which, adapting -themselves to a parasitic life, have surrounded their plasma-body with a -delicate closed membrane. - -The simple naked Amoebae are, next to the Monera, the most important of -all organisms to the whole science of biology, and especially to general -genealogy. For it is evident that the Amoebae originally arose out of -simple Monera (Protamoebae), by the important process of segregation -taking place in their homogeneous viscid body--the differentiation of an -inner kernel from the surrounding plasma. By this means the great -progress from a simple cytod (without kernel) into a real cell (with -kernel) was accomplished (compare Fig. 8 _A_ and Fig. 10 _B_). As some -of these cells at an early stage encased themselves by secreting a -hardened membrane, they formed the first vegetable cells, while others, -remaining naked, developed into the first aggregates of animal cells. -The presence or absence of an encircling hard membrane forms the most -important, although by no means the entire, difference of form between -animal and vegetable cells. As vegetable cells even at an early stage -enclose themselves within their hard, thick, and solid cellular shell, -like that of the Amoebae in a state of rest (Fig. 10 _A_), they remain -more independent and less accessible to the influences of the outer -world than are the soft animal cells, which are in most cases naked, or -merely covered by a thin pliable membrane. But in consequence of this -the vegetable cells cannot combine, as do the animal cells, for the -construction of higher and composite fibrous tracts, for example, the -nervous and muscular tissues. It is probable that, in the case of the -most ancient single-celled organisms, there must have developed at an -early stage the very important difference in the animal and vegetable -mode of receiving food. The most ancient single-celled animals, being -naked cells, could admit solid particles into the interior of their soft -bodies, as do the Amoebae (Fig. 10 _B_) and the colourless blood-cells; -whereas the most ancient single-celled plants encased by their membranes -were no longer able to do this, and could admit through it only fluid -nutrition (by means of diffusion). - -[Illustration: FIG. 11.--A single Whip-swimmer (Euglena striata), -greatly magnified. Above a thread-like lashing whip is visible; in the -centre the round cellular kernel, with its kernel speck.] - -The _Whip-swimmers_ (Flagellata), which we consider as a third class of -the kingdom Protista, are of no less doubtful nature than the Amoebae. -They often show as close and important relations to the vegetable as to -the animal kingdom. Some Flagellata at an early stage, when freely -moving about, cannot be distinguished from real plants, especially from -the spores of many Algae; whereas others are directly allied to real -animals, namely, to the fringed Infusoria (Ciliata). The Flagellata are -simple cells which live in fresh or salt water, either singly or united -in colonies. The characteristic part of their body is a very movable -simple or compound whip-like appendage (whip, or flagellum) by means of -which they actively swim about in the water. This class is divided into -two orders. Among the fringed whip-swimmers (Cilioflagellata) there -exists, in addition to the long whip, a short fringe of vibrating hairs, -which is wanting in the unfringed whip-swimmers (Nudoflagellata). To the -former belong the flint-shelled yellow Peridinia, which are largely -active in causing the phosphorescence of the sea; to the latter belong -the green Euglenae, immense masses of which frequently make our ponds in -spring quite green. - -[Illustration: FIG. 12.--The Norwegian Flimmer-ball (Magosphaera planula) -swimming by means of its vibratile fringes, as seen from the surface.] - -A very remarkable new form of Protista, which I have named -_Flimmer-ball_ (Magosphaera), I discovered only three years ago (in -September, 1869), on the Norwegian coast (Fig. 12), and have more -accurately described in my Biological Studies(15) (p. 137, Plate V.). -Off the island of Gis-oe, near Bergen, I found swimming about, on the -surface of the sea, extremely neat little balls composed of a number -(between thirty and forty) of fringed pear-shaped cells, the pointed -ends of which were united in the centre like radii. After a time the -ball dissolved. The individual cells swarmed about independently in the -water like fringed Infusoria, or Ciliata. These afterwards sank to the -bottom, drew their fringes into their bodies, and gradually changed into -the form of creeping Amoebae (like Fig 10 _B_). These last afterwards -encased themselves (as in Fig. 10 _A_), and then divided by repeated -halvings into a large number of cells (exactly as in the case of the -cleavage of the egg, Fig. 6, vol. i. p. 299). The cells became covered -with vibratile hairs, broke through the case enclosing them, and now -again swam about in the shape of a fringed ball (Fig. 12). This -wonderful organism, which sometimes appears like a simple Amoeba, -sometimes as a single fringed cell, sometimes as a many-celled fringed -ball, can evidently be classed with none of the other Protista, and must -be considered as the representative of a new independent group. As this -group stands midway between several Protista, and links them together, -it may bear the name of _Mediator_, or _Catallacta_. - -[Illustration: FIG. 13.--Labyrinthula macrocystis (much enlarged). Below -is a large group of accumulated cells, one of which, on the left, is -separating itself; above are two single cells which are gliding along -the threads of the retiform labyrinth which form their "tramways."] - -The Protista of the fifth class, the _Tram-weavers_, or _Labyrinthuleae_, -are of a no less puzzling nature; they were lately discovered by -Cienkowski on piles in sea water (Fig. 13). They are spindle-shaped -cells, mostly of a yellow-ochre colour, which are sometimes united into -a dense mass, sometimes move about in a very peculiar way. They form, in -a manner not yet explained, a retiform frame of entangled threads -(compared to a labyrinth), and on the dense filamentous "tramways" of -this frame they glide about. From the shape of the cells of the -Labyrinthuleae we might consider them as the simplest plants, from their -motion as the simplest animals, but in reality they are neither animals -nor plants. - -[Illustration: FIG. 14.--Navicula hippocampus (greatly magnified). In -the middle of the cell the cell-kernel (nucleus) is visible, together -with its kernel speck (nucleolus).] - -The _Flint-cells_ (Diatomeae), a sixth class of Protista, are perhaps the -most closely related to the Labyrinthuleae. These primary -creatures--which at present are generally considered as plants, although -some celebrated naturalists still look upon them as animals--inhabit the -sea and fresh waters in immense masses, and offer an endless variety of -the most elegant forms. They are mostly small microscopic cells, which -either live singly (Fig. 14), or united in great numbers, and occur -either attached to objects, or glide and creep about in a peculiar -manner. Their soft cell-substance, which is of a characteristic brownish -yellow colour, is always enclosed by a solid and hard flinty shell, -possessing the neatest and most varied forms. This flinty covering is -open to the exterior only by one or two slits, through which the -enclosed soft plasma-body communicates with the outer world. The flinty -cases are found petrified in masses, and many rocks--for example, the -Tripoli slate polish, the Swedish mountain meal, etc.,--are in a great -measure composed of them. - -A seventh class of Protista is formed by the remarkable _Slime-moulds_ -(Myxomycetes). They were formerly universally considered as plants, as -real Fungi, until ten years ago the botanist De Bary, by discovering -their ontogeny, proved them to be quite distinct from Fungi, and rather -to be akin to the lower animals. The mature body is a roundish bladder, -often several inches in size, filled with fine spore-dust and soft -flakes (Fig. 15), as in the case of the well-known puff-balls -(Gastromycetes). However, the characteristic cellular threads, or hyphae, -of a real fungus do not arise from the germinal corpuscles, or spores, -of the Myxomycetes, but merely naked masses of plasma, or cells, which -at first swim about in the form of Flagellata (Fig. 11), afterwards -creep about like the Amoebae (Fig. 10 _B_), and finally combine with -others of the same kind to form large masses of "slime," or "plasmodia." -Out of these, again, there arises, by-and-by, the bladder-shaped -fruit-body. Many of my readers probably know one of these plasmodia, the -AEthalium septicum, which in summer forms a beautiful yellow mass of soft -mucus, often several feet in breadth, known by the name of "tan -flowers," and penetrates tan-heaps and tan-beds. At an early stage these -slimy, freely-creeping Myxomycetes, which live for the most part in damp -forests, upon decaying vegetable substances, bark of trees, etc., are -with equal justice or injustice declared by zoologists to be animals, -while in the mature, bladder-shaped condition of fructification they are -by botanists defined as plants. - -[Illustration: FIG. 15.--A stalked fruit-body (spore-bladder, filled -with spores) of one of the Myxomycetes (Physarum albipes) not much -enlarged.] - -The nature of the _Ray-streamers_ (Rhizopoda), the eighth class of the -kingdom Protista, is equally obscure. These remarkable organisms have -peopled the sea from the most ancient times of the organic history of -the earth, in an immense variety of forms, sometimes creeping at the -bottom of the sea, sometimes swimming on the surface. Only very few live -in fresh water (Gromia, Actinosphaerium). Most of them possess solid -calcareous or flinty shells of an extremely beautiful construction, -which can be perfectly preserved in a fossil state. They have frequently -accumulated in such huge numbers as to form mountain masses, although -the single individuals are very small, and often scarcely visible, or -completely invisible to the naked eye. A very few attain the diameter -of a few lines, or even as much as a couple of inches. The name which -the class bears is given because thousands of exceedingly fine threads -of protoplasm radiate from the entire surface of their naked slimy body; -these rays are quasi-feet, or pseudopodia, which branch off like roots -(whence the term Rhizopoda, signifying root-footed), unite like nets, -and are observed continually to change form, as in the case of the -simpler plasmic feet of the Amoeboidea, or Protoplasts. These -ever-changing little pseudo-feet serve both for locomotion and for -taking food. - -The class of the Rhizopoda is divided into three different legions, viz. -the chamber-shells, or Acyttaria, the sun-animalcules, or Heliozoa, and -the basket-shells, or Radiolaria. The _Chamber-shells_ (Acyttaria) -constitute the first and lowest of these three legions; for the whole of -their soft body consists merely of simple mucous or slimy cell-matter, -or protoplasm, which has not differentiated into cells. However, in -spite of this most primitive nature of body, most of the Acyttaria -secrete a solid shell composed of calcareous earth, which presents a -great variety of exquisite forms. In the more ancient and more simple -Acyttaria this shell is a simple chamber, bell-shaped, tubular, or like -the shell of a snail, from the mouth of which a bundle of plasmic -threads issues. In contrast to these _single-chambered forms_ -(Monothalamia), the _many-chambered forms_ (Polythalamia)--to which the -great majority of the Acyttaria belong--possess a house, which is -composed in an artistic manner of numerous chambers. These chambers -sometimes lie in a row one behind the other, sometimes in concentric -circles or spirals, in the form of a ring round a central point, and -then frequently one above another in many tiers, like the boxes of an -amphitheatre. This formation, for example, is found in the nummulites, -whose calcareous shells, of the size of a lentil, have accumulated to -the number of millions, and form whole mountains on the shores of the -Mediterranean. The stones of which some of the Egyptian pyramids are -built consist of such nummulitic limestone. In most cases the chambers -of the shells of the Polythalamia are wound round one another in a -spiral line. The chambers are connected with one another by passages and -doors, like rooms of a large palace, and are generally open towards the -outside by numerous little windows, out of which the plasmic body can -stream or strain forth its little pseudo-feet, or rays of slime, which -are always changing form. But in spite of the exceedingly complicated -and elegant structure of this calcareous labyrinth, in spite of the -endless variety in the structure and the decoration of its numerous -chambers, and in spite of the regularity and elegance of their -execution, the whole of this artistic palace is found to be the secreted -product of a perfectly formless, slimy mass, devoid of any component -parts! Verily, if the whole of the recent anatomy of animal and -vegetable textures did not support our theory of plastids, if all its -important results did not unanimously corroborate the fact that the -whole miracle of vital phenomena and vital forms is traceable to the -active agency of the formless albuminous combinations of protoplasm, the -Polythalamia alone would secure the triumph of that theory. For we may -here at any moment, by means of the microscope, point out the wonderful -fact, first established by Dujardin and Max Schulze, that the formless -mucus of the soft plasma-body, this true "matter of life," is able to -secrete the neatest, most regular, and most complicated structures. This -secretive skill is simply a result of _inherited adaptation_, and by it -we learn to understand how this same "primaeval slime"--this same -protoplasm--can produce in the bodies of animals and plants the most -different and most complicated cellular forms. - -It is, moreover, a matter of special interest that the most ancient -organism, the remains of which are found in a petrified condition, -belongs to the Polythalamia. This organism is the "Canadian Life's-dawn" -(_Eozoon canadense_), which has already been mentioned, and which was -found a few years ago in the Ottawa formation (in the deepest strata of -the Laurentian system), on the Ottawa river in Canada. If we expected to -find organic remains at all in these most ancient deposits of the -primordial period, we should certainly look for such of the most simple -Protista as are covered with a solid shell, and in the organization of -which the difference between animal and plant is as yet not indicated. - -We know of but few species of the _Sun-animalcules_ (Heliozoa), the -second class of the Rhizopoda. One species is very frequently found in -our fresh waters. It was observed even in the last century by a -clergyman in Dantzig, Eichhorn by name, and it has been called after -him, Actinosphaerium Eichhornii. To the naked eye it appears as a -gelatinous grey globule of mucus, about the size of a pin's head. -Looking at it through the microscope, we see hundreds or thousands of -fine mucous threads radiating from the central plasma body, and perceive -that the inner layer of its cell-substance is different from the outer -layer, which forms a bladder-like membrane. In consequence of its -structure, this, the little sun-animalcule, although wanting a shell, -really rises above the structureless Acyttaria, and forms the transition -from these to the Radiolaria. The genus Cystophrys is of a nature akin -to it. - -The _Basket-shells_ (Radiolaria) form the third and last class of the -Rhizopoda. Their lower forms are closely allied to the Heliozoa and -Acyttaria, whereas their higher forms rise far above them. They are -essentially distinguished from both by the fact that the central part of -their body is composed of many cells, and surrounded by a solid -membrane. This closed "central capsule," generally of a globular shape, -is covered by a mucous layer of plasma, out of which there radiate on -all sides thousands of exceedingly fine threads, the branching and -confluent so-called pseudopodia. Between these are scattered numerous -yellow cells of unknown function, containing grains of starch. Most -Radiolaria are characterized by a highly developed skeleton, which -consists of flint, and displays a wonderful richness of the neatest and -most curious forms. Sometimes this flinty skeleton forms a simple -trellice-work ball (Fig. 16 _s_), sometimes a marvellous system of -several concentric trelliced balls, encased in one another, and -connected by radial staves. In most cases delicate spikes, which are -frequently branched like a tree, radiate from the surface of the balls. -In other cases the whole skeleton consists of only one flinty star, and -is then generally composed of twenty staves, distributed according to -definite mathematical laws, and united in a common central point. The -skeletons of other Radiolaria again form symmetrical many-chambered -structures, as in the case of the Polythalamia. Perhaps no other group -of organisms develop in the formation of their skeletons such an amount -of various fundamental forms, such geometrical regularity, and such -elegant architecture. Most of the forms as yet discovered, I have given -in the atlas accompanying my Monograph of the Radiolaria.(23) Here I -shall only give as an example the picture of one of the simplest forms, -the _Cyrtidosphaera echinoides_ of Nice. The skeleton in this case -consists only of a simple trelliced ball (_s_), with short radial spikes -(_a_), which loosely surround the central capsule (_c_). Out of the -mucous covering, enclosing the latter, radiate a great number of -delicate little pseudopodia (_p_), which are partly drawn back -underneath the shell, and fused into a lumpy mass of mucus. Between -these are scattered a number of yellow cells (_l_). - -[Illustration: FIG. 16.--Cyrtidosphaera echinoides, 400 times enlarged. -_c._ Globular central capsule. _s._ Basket-work of the perforated flinty -shell. _a._ Radial spikes, which radiate from the latter. _p._ The -pseudo-feet radiating from the mucous covering surrounding the central -capsule. _l._ Yellow globular cells, scattered between the latter, -containing grains of starch.] - -Most Acyttaria live only at the bottom of the sea, on stones and -seaweeds, or creep about in sand and mud by means of their pseudopodia, -but most Radiolaria swim on the surface of the sea by means of long -pseudopodia extending in all directions. They live together there in -immense numbers, but are mostly so small that they have been almost -completely overlooked, and have only become accurately known during the -last fourteen years. Certain Radiolaria living in communities -(Polycyttaria) form gelatinous lumps of some lines in diameter. On the -other hand, most of those living isolated (Monocyttaria) are invisible -to the naked eye; but still their petrified shells are found accumulated -in such masses that in many places they form entire mountains; for -example, the Nicobar Islands in the Indian Archipelago, and the Island -of Barbadoes in the Antilles. - -As most readers are probably but little acquainted with the eight -classes of the Protista just mentioned, I shall now add some further -general observations on their natural history. The great majority of all -Protista live in the sea, some swimming freely on the surface, some -creeping at the bottom, and others attached to stones, shells, plants, -etc. Many species of Protista also live in fresh water, but only a very -small number on dry land (for example, Myxomycetes and some -Protoplasta). Most of them can be seen only through the microscope, -except when millions of individuals are found accumulated. Only a few of -them attain a diameter of some lines, or as much as an inch. What they -lack in size of body they make up for by producing astonishing numbers -of individuals, and they very considerably influence in this way the -economy of nature. The imperishable remains of dead Protista, for -instance, the flinty shells of the Diatomeae and Radiolaria and the -calcareous shells of the Acyttaria, often form large rock masses. - -In regard to their _vital phenomena_, especially those of nutrition and -propagation, some Protista are more allied to plants, others more to -animals. Both in their mode of taking food and in the chemical changes -of their living substance, they sometimes more resemble the lower -animals, at others the lower plants. _Free locomotion_ is possessed by -many Protista, while others are without it; but this does not constitute -a characteristic distinction, as we know of undoubted animals which -entirely lack free locomotion, and of genuine plants which possess it. -All Protista have a _soul_--that is to say, are "animate"--as well as -all animals and all plants. The soul's activity in the Protista -manifests itself in their _irritability_, that is, in the movements and -other changes which take place in consequence of mechanical, electrical, -and chemical irritation of their contractile protoplasm. Consciousness -and the capability of will and thought are probably wanting in all -Protista. However, the same qualities are in the same degree also -wanting in many of the lower animals, whereas many of the higher animals -in these respects are scarcely inferior to the lower races of human -beings. In the Protista, as in all other organisms, the activities of -the soul are traceable to molecular motions in the protoplasm. - -The most important _physiological characteristic_ of the kingdom -Protista lies in the exclusively _non-sexual propagation_ of all the -organisms belonging to it. The higher animals and plants multiply almost -exclusively in a sexual manner. The lower animals and plants multiply -also, in many cases, in a non-sexual manner, by division, the formation -of buds, the formation of germs, etc. But sexual propagation almost -always exists by the side of it, and often regularly alternates with it -in succeeding generations (Metagenesis, vol. i. p. 206). All Protista, -on the other hand, propagate themselves exclusively in a non-sexual -manner, and in fact, the distinction of the two sexes among them has not -been effected--there are neither male nor female Protista. - -The Protista in regard to their vital phenomena stand midway between -animals and plants, that is to say, between their lowest forms; and the -same must be said in regard to the _chemical composition_ of their -bodies. One of the most important distinctions between the chemical -composition of animal and vegetable bodies consists in the -characteristic formation of the skeleton. The skeleton, or the solid -scaffolding of the body in most genuine plants, consists of a substance -called cellulose, devoid of nitrogen, but secreted by the nitrogenous -cell-substance, or protoplasm. In most genuine animals, on the other -hand, the skeleton generally consists either of nitrogenous combinations -(chitin, etc.) or of calcareous earth. In this respect some Protista are -more like plants, others more like animals. In many of them the skeleton -is principally or entirely formed of calcareous earth, which is met with -both in animal and vegetable bodies. But the active vital substance in -all cases is the mucous protoplasm. - -In regard to the _form_ of the Protista, it is to be remarked that the -_individuality_ of their body almost always remains at an extremely low -stage of development. Very many Protista remain for life simple plastids -or individuals of the first order. Others, indeed, form colonies or -republics of plastids by the union of several individuals. But even -these higher individuals of the second order, formed by the combination -of simple plastids, for the most part remain at a very low stage of -development. The members of such communities among the Protista remain -very similar one to another, and never, or only in a slight degree, -commence a division of labour, and are consequently as little able to -render their community fit for higher functions as are, for example, the -savages of Australia. The community of the plastids remains in most -cases very loose, and each single plastid retains in a great measure its -own individual independence. - -A second structural characteristic, which next to their low stage of -individuality especially distinguishes the Protista, is the low stage of -development of their stereometrical fundamental forms. As I have shown -in my theory of fundamental forms (in the fourth book of the General -Morphology), a definite geometrical fundamental form can be pointed out -in most organisms, both in the general form of the body and in the form -of the individual parts. This ideal fundamental form, or type, which is -determined by the number, position, combination, and differentiation of -the component parts, stands in just the same relation to the _real_ -organic form as the ideal geometrical fundamental form of crystals does -to their imperfect _real_ form. In most bodies and parts of the bodies -of animals and plants this fundamental form is a pyramid. It is a -regular pyramid in the so-called "regular radiate" forms, and an -irregular pyramid in the more highly differentiated, so-called -"bilaterally symmetrical" forms. (Compare the plates in the first volume -of my General Morphology, pp. 556-558.) Among the Protista this -pyramidal type, which prevails in the animal and vegetable kingdom, is -on the whole rare, and instead of it we have either quite irregular -(amorphous) or more simple, regular geometrical types; especially -frequent are the sphere, the cylinder, the ellipsoid, the spheroid, the -double cone, the cone, the regular polygon (tetrahedron, hexahedron, -octahedron, dodecahedron, icosahedron), etc. All the fundamental forms -of the pro-morphological system, which are of a low rank in that system, -prevail in the Protista. However, in many Protista there occur also the -higher, regular, and bilateral types, fundamental forms which -predominate in the animal and vegetable kingdoms. In this respect some -of the Protista are frequently more closely allied to animals (as the -Acyttaria), others more so to plants (as the Radiolaria). - -With regard to the _palaeontological development of the kingdom -Protista_, we may form various, but necessarily very unsafe, -genealogical hypotheses. Perhaps the individual classes of the kingdom -are independent tribes, or phyla, which have developed independently of -one another and independently of the animal and the vegetable kingdoms. -Even if we adopt the monophyletic hypothesis of descent, and maintain a -common origin from a single form of Moneron for all organisms, without -exception, which ever have lived and still live upon the earth, even in -this case the connection of the neutral Protista on the one hand with -the vegetable kingdom, and on the other hand with the animal kingdom, -must be considered as very vague. We must regard them (compare p. 74) as -lower off-shoots which have developed directly out of the root of the -great double-branched organic pedigree, or perhaps out of the lowest -tribe of Protista, which may be supposed to have shot up midway between -the two diverging high and vigorous trunks of the animal and vegetable -kingdoms. The individual classes of the Protista, whether they are more -closely connected at their roots in groups, or only form a loose bunch -of root offsets, must in this case be regarded as having nothing to do -either with the diverging groups of organisms belonging to the animal -kingdom on the right, or to the vegetable kingdom on the left. They must -be supposed to have retained the original simple character of the common -primaeval living thing more than have genuine animals and genuine plants. - -But if we adopt the polyphyletic hypothesis of descent, we have to -imagine a number of organic tribes, or phyla, which all shoot up by -spontaneous generation out of the same ground, by the side of and -independent of one another. (Compare p. 75.) In that case numbers of -different Monera must have arisen by spontaneous generation whose -differences would depend only upon slight, to us imperceptible, -differences in their chemical composition, and consequently upon -differences in their capability of development. A small number of Monera -would then have given origin to the animal kingdom, and, again, a small -number would have produced the vegetable kingdom. Between these two -groups, however, there would have developed, independently of them, a -large number of independent tribes, which have remained at a lower stage -of organization, and which have neither developed into genuine plants -nor into genuine animals. - -A safe means of deciding between the monophyletic and polyphyletic -hypotheses is as yet quite impossible, considering the imperfect state -of our phylogenetic knowledge. The different groups of Protista, and -those lowest forms of the animal kingdom and of the vegetable kingdom -which are scarcely distinguishable from the Protista, show such a close -connection with one another and such a confused mixture of -characteristics, that at present any systematic division and arrangement -of the groups of forms seem more or less artificial and forced. Hence -the attempt here offered must be regarded as entirely provisional. But -the more deeply we penetrate into the genealogical secrets of this -obscure domain of inquiry, the more probable appears the idea that the -vegetable kingdom and the animal kingdom are each of independent origin, -and that midway between these two great pedigrees a number of other -independent small groups of organisms have arisen by repeated acts of -spontaneous generation, which on account of their indifferent neutral -character, and in consequence of their mixture of animal and vegetable -properties, may lay claim to the designation of independent Protista. - - - II. III. - - =Vegetable Kingdom= =Animal Kingdom= - Plantae _Animalia_ - /--------^----------\ /-------------------------------^------------\ - Flowering Plants Vertebrate Animals - _Phanerogamia_ _Vertebrata_ - | \-----v-------/ - | | - | | - | Articulated Animals | - | _Arthropoda_ | - | \-----v------/ | - | | | - | | | - | Star-fishes | | Molluscous Animals - Ferns _Echinoderma_ | | _Mollusca_ - _Filicinae_ \-----v------/ | | \-----v------/ - | | | | | - | | | | | - | | | | | - | | | | | - Mosses \-------------------v---------------/ - _Muscinae_ Lichens Worms - | _Lichenes_ _Vermes_ - | | | - | | | - | | Animal-trees | - | | _Zoophytes_ | - ---- Fungi | | - _Algae_ _Fungi_ | | - | | | | - | | | | - \-------v-----/ \-----v---/ - =Neutral= - =Primaeval Plants= =Primaeval Creatures= =Primaeval Animals= - Protophyta Protista Protozoa - \-----v------/ \-----v------/ \-----v------/ - - ||| ||||||||||| ||||| - ||| ||||||||||| ||||| - ||| ||||||||||| ||||| - Vegetable Monera Neutral Monera Animal Monera - | ||||| | - | ||||| | - | ||||| | - \--------------------------v------------/ - - | - | - =Archigonic Monera= - - (Pieces of Protoplasm which have originated by Spontaneous Generation) - - ---------------------------------------------------------------- - - - POLYPHYLETIC PEDIGREE. - - II. I. III. - - =Vegetable= =Protista= =Animal= - =Kingdom= =Kingdom= =Kingdom= - Vegetabilia Protista Animalia - \------v------/ | \-----v----/ - | | | - | | | - | /-----------------------------------^--------------------------------\ | - | Slime-moulds, | - | or | - | Mucous Fungi Ray-streamers | - | _Myxomycetes_ _Rhizopoda_ | - | \-----v------/ \-----v------/ | - | | | | - | | Flint-cells | Flimmer-balls | - | | _Diatomae_ | _Catallacta_ | - | | \-----v------/ | \-----v------/ | - | | | | | | - | | | Whip-swimmers | | | - | | | _Flagellata_ | | | - | | | \-----v------/ | | | - | | | | | | | - | | | Tram-weavers | | | | - | | | _Labyrinthulea_ | | | | - | | | \-----v------/ | | | | - | | | | | | | | - | | | | Amoebae, | | | =Primaeval= - =Primaeval Plants= | | | or | | | =Animals= - Protophyta | | | Protoplasta | | | Protozoa - \------v------/ | | | \-----v------/ | | | \-----v------/ - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - ||| | | | ||||| | | | ||||||| - =Vegetable= | | | =Neutral= | | | =Animal= - =Monera= | | | =Monera= | | | =Monera= - | | | | | | T | T T | T | - T | | T | | T | | T | | | | T | |T | T - |T | T | T| | T | |T | T | | | | |T| | | ||T | T |T - ||T | |T | || | | | || | |T | |T| | |||T| | |||T | | || - T|||T | T||T | ||T | T|T | ||T | ||T | ||| | ||||| | |||| | |T||T - ||||| | |||| | ||| | ||| | ||| | ||| | ||| | ||||| | |||| | ||||| - ||||| | |||| | ||| | ||| | ||| | ||| | ||| | ||||| | |||| | ||||| - ------------------------------------------------------------------------------------------- - - N.B.--The lines marked with a T indicate extinct tribes of Protista, - which have arisen independently by repeated acts of Spontaneous Generation. - - -Thus, if we assume one entirely independent trunk for the vegetable -kingdom, and a second for the animal kingdom, we may set up a number of -independent stems of Protista, each of which has developed, quite -independently of other stems and trunks, from a special archigonic form -of Monera. In order to make this relation more clear, we may imagine the -whole world of organisms as an immense meadow which is partially -withered, and upon which two many-branched and mighty trees are -standing, likewise partially withered. The two great trees represent the -animal and vegetable kingdoms, their fresh and still green branches the -living animals and plants; the dead branches with withered leaves -represent the extinct groups. The withered grass of the meadow -corresponds to the numerous extinct tribes, and the few stalks, still -green, to the still living phyla of the kingdom Protista. But the common -soil of the meadow, from which all have sprung up, is primaeval by -protoplasm. - - - - -CHAPTER XVII. - -PEDIGREE AND HISTORY OF THE VEGETABLE KINGDOM. - - - The Natural System of the Vegetable Kingdom.--Division of the - Vegetable Kingdom into Six Branches and Eighteen Classes.--The - Flowerless Plants (Cryptogamia).--Sub-kingdom of the Thallus - Plants.--The Tangles, or Algae (Primary Algae, Green Algae, Brown - Algae, Red Algae).--The Thread-plants, or Inophytes (Lichens and - Fungi).--Sub-kingdom of the Prothallus Plants.--The Mosses, or - Muscinae (Water-mosses, Liverworts, Leaf-mosses, - Bog-mosses).--The Ferns, or Filicinae (Leaf-ferns, Bamboo-ferns, - Water-ferns, Scale-ferns).--Sub-kingdom of Flowering Plants - (Phanerogamia).--The Gymnosperms, or Plants with Naked Seeds - (Palm-ferns = Cycadeae; Pines = Coniferae).--The Angiosperms, or - Plants with Enclosed Seeds.--Monocotylae.--Dicotylae.--Cup-blossoms - (Apetalae).--Star-blossoms (Diapetalae).--Bell-blossoms - (Gamopetalae). - - -Every attempt that we make to gain a knowledge of the pedigree of any -small or large group of organisms related by blood must, in the first -instance, start with the evidence afforded by the existing "_natural -system_" of this group. For although the natural system of animals and -plants will never become finally settled, but will always represent a -merely approximate knowledge of true blood relationship, still it will -always possess great importance as a hypothetical pedigree. It is true, -by a "natural system" most zoologists and botanists only endeavour to -express in a concise way the subjective conceptions which each has -formed of the objective "_form-relationships_" of organisms. These -form-relationships, however, as the reader has seen, are in reality the -necessary result of true _blood relationship_. Consequently, every -morphologist in promoting our knowledge of the natural system, at the -same time promotes our knowledge of the pedigree, whether he wishes it -or not. The more the natural system deserves its name, and the more -firmly it is established upon the concordance of results obtained from -the study of comparative anatomy, ontogeny, and palaeontology, the more -surely may we consider it as the approximate expression of the true -pedigree of the organic world. - -In entering upon the task contemplated in this chapter, the genealogy of -the vegetable kingdom, we shall have, according to this principle, first -to glance at the _natural system of the vegetable kingdom_ as it is at -present (with more or less important modifications) adopted by most -botanists. According to the system generally in vogue, the whole series -of vegetable forms is divided into two main groups. These main -divisions, or sub-kingdoms, are the same as were distinguished more than -a century ago by Charles Linnaeus, the founder of systematic natural -history, and which he called _Cryptogamia_, or secretly-blossoming -plants, and _Phanerogamia_, or openly-flowering plants. The latter, -Linnaeus, in his artificial system of plants, divided, according to the -different number, formation, and combination of the anthers, and also -according to the distribution of the sexual organs, into twenty-three -different classes, and then added the Cryptogamia to these as the -twenty-fourth and last class. - -The _Cryptogamia_, the secretly-blossoming or flowerless plants, which -were formerly but little observed, have in consequence of the careful -investigations of recent times been proved to present such a great -variety of forms, and such a marked difference in their coarser and -finer structure, that we must distinguish no less than fourteen -different classes of them; whereas the number of classes of flowering -plants, or _Phanerogamia_, may be limited to four. However, these -_eighteen classes of the vegetable kingdom_ can again be naturally -grouped in such a manner that we are able to distinguish in all _six -main divisions_ or _branches_ of the vegetable kingdom. Two of these six -branches belong to the flowering, and four to the flowerless plants. The -table on page 82 shows how the eighteen classes are distributed among -the six branches, and how these again fall under the _sub-kingdoms_ of -the vegetable kingdom. - -The one sub-kingdom of the _Cryptogamia_ may now be naturally divided -into _two_ divisions, or sub-kingdoms, differing very essentially in -their internal structure and in their external form, namely, the Thallus -plants and the Prothallus plants. The group of _Thallus plants_ -comprises the two large branches of Tangles, or Algae, which live in -water, and the Thread-plants, or Inophytes (Lichens and Fungi), which -grow on land, upon stones, bark of trees, upon decaying bodies, etc. The -group of _Prothallus plants_, on the other hand, comprises the two -branches of Mosses and Ferns, containing a great variety of forms. - -All _Thallus plants, or Thallophytes_, can be directly recognized from -the fact that the two morphological fundamental organs of all other -plants, stem and leaves, cannot be distinguished in their structure. The -complete body of all Algae and of all Thread-plants is a mass composed of -simple cells, which is called a _lobe_, or _thallus_. This thallus is -as yet not differentiated into axial-organs (stem and root) and -leaf-organs. On this account, as well as through many other -peculiarities, the Thallophytes contrast strongly with all remaining -plants--those comprised under the two sub-kingdoms of Prothallus plants -and Flowering plants--and for this reason the two latter sub-kingdoms -are frequently classed together under the name of _Stemmed plants_, or -_Cormophytes_. The following table will explain the relation of these -three sub-kingdoms to one another according to the two different -views:-- - - - { A. Thallus Plants } I. Thallus Plants - { (_Thallophyta_) } (_Thallophyta_) - I. Flowerless Plants. { - (_Cryptogamia_) { - { B. Prothallus Plants } - { (_Prothallophyta_) } - } II. Stemmed Plants - } (_Cormophyta_) - } - II. Flowering Plants { C. Flowering Plants } - (_Phanerogamia_) { (_Phanerogamia_) } - - -The stemmed plants, or Cormophytes, in the organization of which the -difference of axial-organs (stem and root) and leaf-organs is already -developed, form at present, and have, indeed, for a very long period -formed, the principal portion of the vegetable world. However, this was -not always the case. In fact, stemmed plants, not only of the flowering -group, but even of the prothallus group, did not exist at all during -that immeasurably long space of time which forms the beginning of the -first great division of the organic history of the earth, under the name -of the archilithic, or primordial period. The reader will recollect that -during this period the Laurentian, Cambrian, and Silurian systems of -strata were deposited, the thickness of which, taken as a whole, -amounts to about 70,000 feet. Now, as the thickness of all the more -recent super-incumbent strata, from the Devonian to the deposits of the -present time, taken together, amounts to only about 60,000 feet, we were -enabled from this fact alone to draw the conclusion--which is probable -also for other reasons--that the archilithic, or primordial, period was -of longer duration than the whole succeeding period down to the present -time. During the whole of this immeasurable space of time, which -probably comprises many millions of centuries, vegetable life on our -earth seems to have been represented exclusively by the sub-kingdom of -Thallus plants, and, moreover, only by the class of marine Thallus -plants, that is to say, the Algae. At least all the petrified remains -which are positively known to be of the primordial period belong -exclusively to this class. As all the animal remains of this immense -period also belong exclusively to animals that lived in water, we come -to the conclusion that at that time organisms adapted to a life on land -did not exist at all. - -For these reasons the first and most imperfect of the great provinces or -branches of the vegetable kingdom, the division of the Algae, or Tangles, -must be of special interest to us. But, in addition, there is the -interest which this group offers when viewed by itself. In spite of the -exceedingly simple composition of their constituent cells, which are but -little differentiated, the Algae show an extraordinary variety of -different forms. To them belong the simplest and most imperfect of all -forms, as well as very highly developed and peculiar forms. The -different groups of Algae are distinguished as much by size of body as by -the perfection and variety of their outer form. At the lowest stage we -find such species as the minute Protococcus, several hundred thousands -of which occupy a space no larger than a pin's head. At the highest -stage we marvel at the gigantic Macrocysts, which attain a length of -from 300 to 400 feet, the longest of all forms in the vegetable kingdom. -It is possible that a large portion of the coal has been formed out of -Algae. If not for these reasons, yet the Algae must excite our special -attention from the fact that they form the beginning of vegetable life, -and contain the original forms of all other groups of plants, supposing -that our monophyletic hypothesis of a common origin for all groups of -plants is correct. (Compare p. 83.) - -SYSTEMATIC VIEW - -_Of the Six Branches and Eighteen Classes of the Vegetable Kingdom._ - - - ========================================================================================== - _Primary Groups_ | | | - _or Sub-Kingdoms_ | _Branches or Clades_ | _Classes_ | _Systematic Name_ - _of the_ | _of the_ | _of the_ | _of the_ - _Vegetable Kingdom._ | _Vegetable Kingdom._ | _Vegetable Kingdom._ | _Classes._ - ------------------------+-----------------------+----------------------+------------------ - - { { 1. Primaeval algae 1. _Archephyceae_ - { { (Protophyta) - { { - { I. { 2. Green algae 2. _Chlorophyceae_ - A. { Tangles { (Chloroalgae) - =Thallus Plants= { _Algae_ { - Thallophyta { { 3. Brown algae 3. _Phaeophyceae_ - { { (Fucoideae) - { { - { { 4. Red algae 4. _Rhodophyceae_ - { { (Florideae) - - { II. { 5. Lichens 5. _Lichenes_ - { Thread-plants { - { _Inophyta_ { 6. Fungi 6. _Fungi_ - { - { { 7. Tangle-mosses 7. _Charobrya_ - { { (Characeae) - { { - { III. { 8. Liverworts 8. _Thallobrya_ - { Mosses { (Hepaticae) - { _Muscinae_ { - { { 9. Frondose-mosses 9. _Phyllobrya_ - B. { { (Frondosae) - =Prothallus= { { - =Plants= { { 10. Turf-mosses 10. _Sphagnobrya_ - Prothallophyta { (Sphagnaceae) - { - { { 11. Shaft-ferns 11. _Calamariae_ - { { (Calamophyta) - { IV. { - { Ferns { 12. Frondose-ferns 12. _Filices_ - { _Felicinae_ { (Pterideae) - { { - { { 13. Aquatic ferns 13. _Rhizocarpeae_ - { { (Hydropterides) - { { - { { 14. Scale-ferns 14. _Selagineae_ - { { (Lepidophyta) - - { V. { - { Plants with { 15. Palm-ferns 15. _Cycadeae_ - C. { Naked Seeds { - =Flowering Plants= { _Gymnosperma_ { 16. Pines 16. _Coniferae_ - Phanerogamia { - { VI. { 17. Plants with 17. _Monocotylae_ - { Plants with { one seed lobe - { Enclosed Seeds { - { _Angiosperma_ { 18. Plants with 18. _Dicotylae_ - { { two seed lobes - - ---------------------------------------------------------------- - - - _Gamopetalae_ - (Flowers with corolla) - | - _Dialypetalae_ - (Star-shaped flowers) - | - _Monochlamydeae_ MONOCOTYLEDONAE - (Flowers with calyx) (One seed-lobed plants) - | | - DICOTYLEDONAE | - (Two seed-lobed plants) | - | | - \--------------------v-------------/ - CONIFERAE +Angiospermae+ - CYCADEAE (Pines) (Plants with enclosed seeds) - (Palm-ferns) | GNETACEAE | - | | | | - \-----------v-----------------------/ - +Gymnospermae+ - (Plants with naked seeds) _Phanerogamae_ - | (Flowering plants) _Pterideae_ - _Selagineae_ | _Rhizocarpeae_ | (Frondose-ferns) - (Scaled-ferns) |(Water-ferns) | | _Calamariae_ - | | | | | (Shaft-ferns) - | | | | | | - \-------------------------------v------------------------/ - +Filicinae+ - _Frondosae_ _Sphagnaceae_ (Ferns) - (Leaf-mosses) (Turf-mosses) | - | | | CHARACEAE - \----------------v------------/ (Tangle-mosses) - | | - _Hepaticae_ (Liverworts) | - | | - \------------------v--------------------/ - +Muscinae+ (Mosses) - _Fucoideae_ | - _Florideae_ (Brown Algae) | _Lichenes_ - (Red Algae) | _Chlorophyceae_ (Lichens) - | | (Green Algae) | - | | | | - \------------------v-----------------/ +Fungi Inophyta+ - +Algae+ (Tangles) (Thread-plants) - | | - \-------v------------------------------/ - _Protophyta_ - (Primaeval Plants) - | - _Vegetable Monera_ - -Most people living inland can form but a very imperfect idea of this -exceedingly interesting branch of the vegetable kingdom, because they -know only its proportionately small and simple representatives living in -fresh water. The slimy green aquatic filaments and flakes of our pools -and ditches and springs, the light green slimy coverings of all kinds of -wood which have for any length of time been in contact with water, the -yellowish green, frothy, and oozy growths of our village ponds, the -green filaments resembling tufts of hair which occur everywhere in fresh -water, stagnant and flowing, are for the most part composed of different -species of Algae. Only those who have visited the sea-shore, and wondered -at the immense masses of cast-up seaweed, and who, from the rocky coast -of the Mediterranean, have seen through the clear blue waters the -beautifully-formed and highly-coloured vegetation of Algae at the bottom, -know how to estimate the importance of the class of Algae. And yet, even -these marine Algae-forests of European shores, so rich in forms, give -only a faint idea of the colossal forests of Sargasso in the Atlantic -ocean, those immense banks of Algae, covering a space of about 40,000 -square miles--the same which made Columbus, on his voyage of discovery, -believe that a continent was near. Similar but far more extensive -forests of Algae grew in the primaeval ocean, probably in dense masses, -and what countless generations of these archilithic Algae have died out -one after another is attested, among other facts, by the vast thickness -of Silurian alum schists in Sweden, the peculiar composition of which -proceeds from those masses of submarine Algae. According to the recently -expressed opinion of Frederick Mohr, a geologist of Bonn, even the -greater part of our coal seams have arisen out of the accumulated dead -bodies of the Algae forests of the ocean. - -Within the branch of the Algae we distinguish four different classes, -each of which is again divided into several orders and families. These -again contain a large number of different genera and species. We -designate these four classes as Primaeval Algae, or Archephyceae, Green -Algae, or Chlorophyceae, Brown Algae, or Phaeophyceae, and Red Algae, or -Rhodophyceae. - -The first class of Algae, the _Primaeval_ Algae (Archephyceae), might also -be called _primaeval plants_, because they contain the simplest and most -imperfect of all plants, and, among them, those most ancient of all -vegetable organisms out of which all other plants have originated. To -them therefore belong those most ancient of all vegetable Monera which -arose by spontaneous generation in the beginning of the Laurentian -period. Further, we have to reckon among them all those vegetable forms -of the simplest organization which first developed out of the Monera in -the Laurentian period, and which possessed the form of a single -plastid. At first the entire body of one of these small primary plants -consisted only of a most simple cytod (a plastid without kernel), and -afterwards attained the higher form of a simple cell, by the separation -of a kernel in the plasma. (Compare above, vol. i. p. 345.) Even at the -present day there exist various most simple forms of Algae which have -deviated but little from the original primary plants. Among them are the -Algae of the families Codiolaceae, Protococcaceae, Desmidiaceae, -Palmellaceae, Hydrodictyeae, and several others. The remarkable group of -Phycochromaceae (Chroococcaceae and Oscillarineae) might also be comprised -among them, unless we prefer to consider them as an independent tribe of -the kingdom Protista. - -The monoplastic Protophyta--that is, those primary Algae formed by a -single plastid--are of the greatest interest, because the vegetable -organism in this case completes its whole course of life as a perfectly -simple "individual of the first order," either as a cytod without -kernel, or as a cell containing a kernel. - -Among the primary plants consisting of a single cytod are the -exceedingly remarkable Siphoneae, which are of considerable size, and -strangely "mimic" the forms of higher plants. Many of the Siphoneae -attain a size of several feet, and resemble an elegant moss (Bryopsis), -or in some cases a perfect flowering plant with stalks, roots, and -leaves (Caulerpa) (Fig. 17). Yet the whole of this large body, -externally so variously differentiated, consists internally of an -entirely simple sack, possessing the negative characters of a simple -cytod. - -[Illustration: FIG. 17.--Caulerpa denticulata, a monoplastic Siphonean -_of the natural size_. The entire branching primary plant, which appears -to consist of a creeping stalk with fibrous roots and indented leaves, -is in reality only _a single plastid_, and moreover a cytod (without a -kernel), not even attaining the grade of a cell with nucleus.] - -These curious Siphoneae, Vaucheriae, and Caulerpae show us to how great a -degree of elaboration a single cytod, although a most simple individual -of the first order, can develop by continuous adaptation to the -relations of the outer world. Even the _single-celled primary -plants_--which are distinguished from the monocytods by possessing a -kernel--develop into a great variety of exquisite forms by adaptation; -this is the case especially with the beautiful _Desmidiaceae_, of which -a species of Euastrum is represented in Fig. 18 as a specimen. - -[Illustration: FIG. 18.--Euastrum rota, a single-celled Desmid, much -enlarged. The whole of the star-shaped body of this primaeval plant has -the formal value of a simple cell. In its centre lies the kernel, and -within this the kernel corpuscle, or speck.] - -It is very probable that similar primaeval plants, the soft body of -which, however, was not capable of being preserved in a fossil state, at -one time peopled the Laurentian primaeval sea in great masses and -varieties, and in a great abundance of forms, without, however, going -beyond the stage of individuality of a simple plastid. - -The group of _Green Tangles_ (Chlorophyceae), or _Green Algae_ -(Cloroalgae), are the second class, and the most closely allied to the -primaeval group. Like the majority of the Archephyceae, all the -Chlorophyceae are coloured green, and by the same colouring matter--the -substance called leaf-green, or chlorophyll--which colours the leaves of -all the higher plants. - -To this class belong, besides a great number of low marine Algae, most of -the Algae of fresh water, the common water hair-weeds, or Confervae, the -green slime-balls, or Gloeosphaerae, the bright green water-lettuce, or -Ulva, which resembles a very thin and long lettuce leaf, and also -numerous small microscopic algae, dense masses of which form a light -green shiny covering to all sorts of objects lying in water--wood, -stones, etc. - -These forms, however, rise above the simple primary Algae in the -composition and differentiation of their body. As the green Algae, like -the primaeval Algae, mostly possess a very soft body, they are but rarely -capable of being petrified. However, it can scarcely be doubted that -this class of Algae--which was the first to develop out of the preceding -one--most extensively and variously peopled the fresh and salt waters of -the earth in early times. - -In the third class, that of the _Brown Tangles_ (Phaeophyceae), or _Black -Algae_ (Fucoideae), the _branch_ of the Algae attains its highest stage of -development, at least in regard to size and body. The characteristic -colour of the Fucoid is more or less dark brown, sometimes tending more -to an olive green or yellowish green, sometimes more to a brownish red -or black colour. - -Among these are the largest of all Algae, which are at the same time the -longest of all plants, namely, the colossal giant Algae, amongst which -the Macrocystis pyrifera, on the coast of California, attains a length -of 400 feet. Also, among our indigenous Algae, the largest forms belong -to this group. Especially I may mention here the stately sugar-tangle -(Laminaria), whose slimy, olive green thallus-body, resembling gigantic -leaves of from 10 to 15 feet in length, and from a half to one foot in -breadth, are thrown up in great masses on the coasts of the North and -Baltic seas. - -To this class belongs also the bladder-wrack (Fucus vesiculosus) common -in our seas, whose fork-shaped, deeply-cut leaves are kept floating on -the water by numerous air bladders (as is the case, too, with many other -brown Algae). The freely floating Sargasso Alga (Sargasso bacciferum), -which forms the meadows or forests of the Sargasso Sea, also belongs to -this class. - -Although each individual of these large alga-trees is composed of many -millions of cells, yet at the beginning of its existence it consists, -like all higher plants, of a single cell--a simple egg. This egg--for -example, in the case of our common bladder-wrack--is a naked, uncovered -cell, and as such is so like the naked egg-cells of lower marine -animals--for example, those of the Medusae--that they might easily be -mistaken one for another (Fig. 19). - -[Illustration: FIG. 19.--The egg of the common bladder-wrack (Fucus -vesiculosus), a simple naked cell, much enlarged. In the centre of the -naked globule of protoplasm the bright kernel is visible.] - -It was probably the Fucoideae, or Brown Algae, which during the primordial -period, to a great extent constituted the characteristic alga-forests of -that immense space of time. Their petrified remains, especially those -of the Silurian period, which have been preserved, can, it is true, -give us but a faint idea of them, because the material of these Algae, -like that of most others, is ill-suited for preservation in a fossil -state. As has already been remarked, a large portion of coal is perhaps -composed of them. - -Less important is the fourth class of Algae, that of the _Rose-coloured -Algae_ (Rhodophyceae), or _Red Sea-weeds_ (Florideae). This class, it is -true, presents a great number of different forms; but most of them are -of much smaller size than the Brown Algae. Although they are inferior to -the latter in perfection and differentiation, they far surpass them in -some other respects. To them belong the most beautiful and elegant of -all Algae, which on account of the fine plumose division of their -leaf-like bodies, and also on account of their pure and delicate red -colour, are among the most charming of plants. The characteristic red -colour sometimes appears as a deep purple, sometimes as a glowing -scarlet, sometimes as a delicate rose tint, and may verge into violet -and bluish purple, or on the other hand into brown and green tints of -marvellous splendour. Whoever has visited one of our sea-coast watering -places, must have admired the lovely forms of the Florideae, which are -frequently dried on white paper and offered for sale. - -Most of the Red Algae are so delicate, that they are quite incapable of -being petrified; this is the case with the splendid Ptilotes, Plocamia, -Delesseria, etc. However, there are individual forms, like the Chondria -and Sphaerococca, which possess a harder thallus, often almost as hard as -cartilage, and of these fossil remains have been preserved--principally -in the Silurian, Devonian, and Carboniferous strata, and later in the -oolites. It is probable that this class also had an important share in -the composition of the archilithic Algae flora. - -If we now again take into consideration the flora of the primordial -period, which was exclusively formed by the group of Algae, we can see -that it is not improbable that its four subordinate classes had a share -in the composition of those submarine forests of the primaeval oceans, -similar to that which the four types of vegetation--trees with trunks, -flowering shrubs, grass, and tender leaf-ferns and mosses--at present -take in the composition of our recent land forests. - -We may suppose that the submarine tree forests of the primordial period -were formed by the huge Brown Algae, or Fucoideae. The many-coloured -flowers at the foot of these gigantic trees were represented by the gay -Red Algae, or Florideae. The green grass between was formed by the -hair-like bunches of Green Algae, or Chloroalgae. Finally, the tender -foliage of ferns and mosses, which at present cover the ground of our -forests, fill the crevices left by other plants, and even settle on the -trunks of the trees, at that time probably had representatives in the -moss and fern-like Siphoneae, in the Caulerpa and Bryopsis, from among -the class of the primary Algae, Protophyta, or Archephyceae. - -With regard to the relationships of the different classes of Algae to one -another and to other plants, it is exceedingly probable that the Primary -Algae, or Archephyceae, as already remarked, form the common root of the -pedigree, not merely for the different classes of Algae, but for the -whole vegetable kingdom. On this account they may with justice be -designated as primaeval plants, or Protophyta. - -Out of the naked vegetable Monera, in the beginning of the Laurentian -period, enclosed cytods were probably the first to arise (vol. i. p. -345), by the naked, structureless, albuminous substance of the Monera -becoming condensed in the form of a pellicle on the surface, or by -secreting a membrane. At a later period, out of these enclosed cytods -genuine vegetable cells probably arose, as a kernel or nucleus separated -itself in the interior from the surrounding cell-substance or plasma. - -The three classes of Green Algae, Brown Algae, and Red Algae, are perhaps -three distinct classes, which have arisen independently of one another -out of the common radical group of Primaeval Algae, and then developed -themselves further (each according to its kind), and have variously -branched off into orders and families. The Brown and Red Algae possess no -close blood relationship to the other classes of the vegetable kingdom. -These latter have most probably arisen out of the Primaeval Algae, either -directly or by the intermediate step of the Green Algae. - -It is probable that Mosses (out of which, at a later time, Ferns -developed) proceeded from a group of Green Algae, and that Fungi and -Lichens proceeded from a group of Primaeval Algae. The Phanerogamia -developed at a much later period out of Ferns. - -As a second class of the Vegetable Kingdom we have above mentioned the -_Thread-plants_ (Inophyta). We understood by this term the two closely -related classes of _Lichens_ and _Fungi_. It is possible that these -Thallus plants have not arisen out of the Primaeval Algae, but out of one -or more Monera, which, independently of the latter, arose by spontaneous -generation. It appears conceivable that many of the lowest Fungi, as for -example, many ferment-causing fungi (forms of Micrococcus, etc.), owe -their origin to a number of different _archigonic_ Monera (that is, -Monera originating by spontaneous generation). - -In any case the Thread-plants cannot be considered as the progenitors of -any of the higher vegetable classes. Lichens, as well as fungi, are -distinct from the higher plants in the composition of their soft bodies, -consisting as it does of a dense felt-work of very long, variously -interwoven, and peculiar threads or chains of cells--the so-called -_hyphae_, on which account we distinguish them as a province under the -name Thread-plants. From their peculiar nature they could not leave any -important fossil remains, and consequently we can form only a very vague -guess at their palaeontological development. - -The first class of Thread-plants, the _Fungi_, exhibit a very close -relationship to the lowest Algae; the Algo-fungi, or Phycomycetes (the -Saprolegniae and Peronosporae) in reality only differ from the -bladder-wracks and Siphoneae (the Vaucheria and Caulerpa) mentioned -previously by the want of leaf-green, or chlorophyll. But, on the other -hand, all genuine Fungi have so many peculiarities, and deviate so much -from other plants, especially in their mode of taking food, that they -might be considered as an entirely distinct province of the vegetable -kingdom. - -Other plants live mostly upon inorganic food, upon simple combinations -which they render more complicated. They produce protoplasm by the -combination of water, carbonic acid, and ammonia. They take in carbonic -acid and give out oxygen. But the Fungi, like animals, live upon organic -food, consisting of complicated combinations of carbon, which they -receive from other organisms and assimilate. They inhale oxygen and -give out carbonic acid like animals. They also never form leaf-green, or -chlorophyll, which is so characteristic of most other plants. In like -manner they never produce starch. Hence many eminent botanists have -repeatedly proposed to remove the Fungi completely out of the vegetable -kingdom, and to regard them as a special and third kingdom, between that -of animals and plants. By this means our kingdom of Protista would be -considerably increased. The Fungi in this case would, in the first -place, be allied to the so-called "slime moulds," or Myxomycetes (which, -however, never form any hyphae). But as many Fungi propagate in a sexual -manner, and as most botanists, according to the prevalent opinion, look -upon Fungi as genuine plants, we shall here leave them in the vegetable -kingdom, and connect them with lichens, to which they are at all events -most nearly related. - -The phyletic origin of Fungi will probably long remain obscure. The -close relationship already hinted at between the Phycomycetes and -Siphoneae (especially between the Saprolegniae and Vaucheriae) suggests to -us that they are derived from the latter. Fungi would then have to be -considered as Algae, which by adaptation to a parasitical life have -become very peculiarly transformed. Many facts, however, support the -supposition that the lowest fungi have originated independently from -archigonic Monera. - -The second class of Inophyta, the _Lichens_ (Lichenes), are very -remarkable in relation to phylogeny; for the surprising discoveries of -late years have taught us that every Lichen is really composed of two -distinct plants--of a low form of Alga (Nostochaceae, Chroococcaceae), and -of a parasitic form of Fungus (Ascomycetes), which lives as a parasite -upon the former, and upon the nutritive substances prepared by it. The -green cells, containing chlorophyll (gonidia), which are found in every -lichen, belong to the Alga. But the colourless threads (hyphae) which, -densely interwoven, form the principal mass of the body of Lichens, -belong to the parasitic Fungus. But in all cases the two forms of -plants--Fungus and Alga--which are always considered as members of two -quite distinct provinces of the vegetable kingdom, are so firmly united, -and so thoroughly interwoven, that nearly every one looks upon a Lichen -as a single organism. - -Most Lichens form small, more or less formless or irregularly indented, -crust-like coverings to stones, bark of trees, etc. Their colour varies -through all possible tints, from the purest white to yellow, red, green, -brown, and the deepest black. - -Many lichens are important in the economy of nature from the fact that -they can settle in the driest and most barren localities, especially on -naked rocks upon which no other plant can live. The hard black lava, -which covers many square miles of ground in volcanic regions, and which -for centuries frequently presents the most determined opposition to the -life of every kind of vegetation, is always first occupied by Lichens. -It is the white or grey Lichens (Stereocaulon) which, in the most -desolate and barren fields of lava, always begin to prepare the naked -rocky ground for cultivation, and conquer it for subsequent higher -vegetation. Their decaying bodies form the first mould in which mosses, -ferns, and flowering plants can afterwards take firm root. Hardy Lichens -are also less affected by the severity of climate than any other plants. -Hence the naked rocks, even in the highest mountains--for the most part -covered by eternal snow, on which no plant could thrive--are encrusted -by the dry bodies of Lichens. - -Leaving now the Fungi, Lichens, and Algae, which are comprised under the -name of Thallus plants, we enter upon the second sub-kingdom of the -vegetable kingdom, that of the _Prothallus plants_ (Prothallophyta), -which by some botanists are called phyllogonic Cryptogamia (in -contradistinction to the Thallus plants, or thallogonic Cryptogamia). -This sub-kingdom comprises the two provinces of _Mosses_ and _Ferns_. - -Here we meet with (except in a few of the lowest forms) the separation -of the vegetable body into two different fundamental organs, -axial-organs (stem and root) and leaves (or lateral organs). In this the -Prothallus plants resemble the Flowering plants, and hence the two -groups have recently often been classed together as stemmed plants, or -Cormophytes. - -But, on the other hand, Mosses and Ferns resemble the Thallus plants, in -the absence of the development of flowers and seeds, and even Linnaeus -classed them with these, as Cryptogamia, in contradistinction to the -plants forming seeds; that is, flowering plants (Anthophyta or -Phanerogamia). - -Under the name of "Prothallus plants" we combine the closely-related -Mosses and Ferns, because both exhibit a peculiar and characteristic -"alternation of generation" in the course of their individual -development. For every species exhibits two different generations, of -which the one is usually called the _Prothallium_, or _Fore-growth_, the -other is spoken of as the _Cormus_, or actual _Stem_ of the moss or -fern. - -The first and original generation, the Fore-growth, or Prothallus, also -called Protonema, still remains in that lower stage of elaboration -manifested throughout life by all Thallus plants; that is to say, stem -and leaf-organs have as yet not differentiated, and the entire cell-mass -of the Fore-growth corresponds to a simple thallus. The second and more -perfect generation of mosses and ferns--the Stem, or Cormus--develops a -much more highly elaborate body, which has differentiated into stalk and -leaf (as in the case of flowering plants), except in the lowest mosses, -where this generation also remains in the lower stage of the thallus. - -With the exception of these latter forms the first generation of Mosses -and Ferns (the thallus-shaped Fore-growth) always produces a second -generation with stem and leaves; the latter in its turn produces the -thallus of the first generation, and so on. Thus, in this case, as in -the ordinary cases of alternation of generation in animals, the first -generation is like the third, fifth, etc., the second like the fourth, -sixth, etc. (Compare vol. i. p. 206.) - -Of the two main classes of Prothallus plants, the Mosses in general are -at a much lower stage of development than the Ferns, and their lowest -forms (especially in an anatomical respect) form the transition from the -Thallus plants through the Algae to Ferns. The genealogical connection of -Mosses and Ferns which is indicated by this fact can, however, be -inferred only from the case of the most imperfect forms of the two -classes; for the more perfect and higher groups of mosses and ferns do -not stand in any close relation to one another, and develop in -completely opposite directions. In any case Mosses have arisen directly -out of Thallus plants, and probably out of Green Algae. - -Ferns, on the other hand, are probably derived from extinct unknown -Mosses, which were very nearly related to the lowest liverworts of the -present day. In the history of creation, Ferns are of greater importance -than Mosses. - -The branch of _Mosses_ (Muscinae, also called Musci, or Bryophyta) -contains the lower and more imperfect plants of the group of -Prothallophytes, which as yet do not possess vessels. Their bodies are -mostly so tender and perishable that they are very ill-suited for being -preserved in a recognizable state as fossils. Hence the fossil remains -of all classes of Mosses are rare and insignificant. It is probable that -Mosses developed in very early times out of the Thallus plants, or, to -be more precise, out of the Green Algae. It is probable that in the -primordial period there existed aquatic forms of transition from the -latter to Mosses, and in the primary period to those living on land. The -Mosses of the present day--out of the gradually differentiating -development of which comparative anatomy may draw some inferences as to -their genealogy--are divided into two different classes, namely: (1) -Liverworts; (2) Leafy Mosses. - -The first and oldest class of Mosses, which is directly allied to the -Green Algae, or Confervae, is formed by the _Liverworts_ (Hepaticae, or -Thallobrya). The mosses belonging to them are, for the most part, small -and insignificant in form, and are little known. Their lowest forms -still possess, in both generations, a simple thallus like the Thallus -plants; as for example, the Ricciae and Marchantiaceae. But the more -highly developed liverworts, the Jungermanniaceae and those akin to them, -gradually commence to differentiate stem and leaf, and their most -highly-developed forms are closely allied to leaf-mosses. By this -transitional series the liverworts show their direct derivation from -the Thallophytes, and more especially from the Green Algae. - -The Mosses, which are generally the only ones known to the -uninitiated--and which, in fact, form the principal portion of the whole -branch--belong to the second class, or _Leafy Mosses_ (Musci frondosi, -called Musci in a narrow sense, also Phyllobrya). Among them are most of -those pretty little plants which, united in dense groups, form the -bright glossy carpet of moss in our woods, or which, in company with -liverworts and lichens, cover the bark of trees. As reservoirs, -carefully storing up moisture, they are of the greatest importance in -the economy of nature. Wherever man mercilessly cuts down and destroys -forests, there, as a consequence, disappear the leafy mosses which -covered the bark of the trees, or, protected by their shade, clothed the -ground, and filled the spaces between the larger plants. Together with -the leafy mosses disappear the useful reservoirs which stored up rain -and dew for times of drought. Thus arises a disastrous dryness of the -ground, which prevents the growth of any rich vegetation. In the greater -part of Southern Europe--in Greece, Italy, Sicily, and Spain--mosses -have been destroyed by the inconsiderate extirpation of forests, and the -ground has thereby been robbed of its most useful stores of moisture; -once flourishing and rich tracts of land have been changed into dry and -barren wastes. Unfortunately in Germany, also, this rude barbarism is -beginning to prevail more and more. It is probable that the small -frondose mosses have played this exceedingly important part in nature -for a very long time, possibly from the beginning of the primary period. -But as their tender bodies are as little suited as those of all other -mosses for being preserved in a fossil state, palaeontology can give us -no information about this. - -We learn from the science of petrifactions much more than we do in the -case of Mosses of the importance which the second branch of Prothallus -plants--that is, Ferns--have had in the history of the vegetable world. -Ferns, or more strictly speaking, the "plants of the fern tribe" -(Filicineae, or Pterideae, also called Pteridophyta, or Vascular -Cryptogams), formed during an extremely long period, namely, during the -whole primary or palaeolithic period, the principal portion of the -vegetable world, so that we may without hesitation call it the _era of -Fern Forests_. From the beginning of the Devonian period, in which -organisms living on land appeared for the first time, namely, during the -deposits of the Devonian, Carboniferous, and Permian strata, plants like -Ferns predominated so much over all others, that we are justified in -giving this name to that period. In the stratifications just mentioned, -but above all, in the immense layers of coal of the Carboniferous or -coal period, we find such numerous and occasionally well preserved -remains of Ferns, that we can form a tolerable vivid picture of the very -peculiar land flora of the palaeolithic period. In the year 1855 the -total number of the then known palaeolithic species of plants amounted to -about a thousand, and among these there were no less than 872 Ferns. -Among the remaining 128 species were 77 Gymnosperms (pines and -palm-ferns), 40 Thallus plants (mostly Algae), and about 20 not -accurately definable Cormophyta (stem-plants). - -As already remarked, Ferns probably developed out of the lower -liverworts in the beginning of the primary period. In their -organization Ferns rise considerably above Mosses, and in their more -highly developed forms even approach the flowering plants. In Mosses, as -in Thallus plants, the entire body is composed of almost equi-formal -cells, little if at all differentiated; but in the tissues of Ferns we -find those peculiarly differentiated strings of cells which are called -the vessels of plants, and which are universally met with in flowering -plants. Hence Ferns are sometimes united as "vascular Cryptogams" with -Phanerogams, and the group so formed is contrasted as that of the -"vascular plants" with "cellular plants,"--that is, with "cellular -cryptogams" (Mosses and Thallus plants). This very important process in -the organization of plants--the formation of vessels--first occurred, -therefore, in the Devonian period, consequently in the beginning of the -second and smaller half of the organic history of the earth. - -The branch of Ferns, or Filicinae, is divided into five distinct classes: -(1) Frondose Ferns, or Pteridae; (2) Reed Ferns, or Calamariae; (3) -Aquatic Ferns, or Rhizocarpeae; (4) Snakes Tongues, or Ophioglossae; and -(5) Scale Ferns, or Lepidophyta. By far the most important of these five -classes, and also the richest in forms, were first the Frondose Ferns, -and then the Scale-ferns, which formed the principal portion of the -palaeolithic forests. The Reed Ferns, on the other hand, had at that time -already somewhat diminished in number; and of the Aquatic Ferns, we do -not even know with certainty whether they then existed. It is difficult -for us to form any idea of the very peculiar character of those gloomy -palaeolithic fern forests, in which the whole of the gay abundance of -flowers of our present flora was entirely wanting, and which were not -enlivened by any birds. Of the flowering plants there then existed only -the two lowest classes, the pines and palm ferns, with naked seeds, -whose simple and insignificant blossoms scarcely deserve the name of -flowers. - -The phylogeny of Ferns, and of the Gymnosperms which have developed out -of them, has been made especially clear by the excellent investigations -which Edward Strasburger published in 1872, on "The Coniferae and -Gnetaceae," as also "On Azolla." This thoughtful naturalist and Charles -Martins, of Montpellier, are among the few botanists who have thoroughly -understood the fundamental value of the Theory of Descent, and the -mechanical-causal connection between ontogeny and phylogeny. The -majority of botanists do not even yet know the important difference -between homology and analogy, between the morphological and -physiological comparison of parts--which has long since been recognized -in zoology--but Strasburger has employed this distinction and the -principle of evolution in his "Comparative Anatomy of the Gymnosperms," -in order to sketch the outlines of the blood relationship of this -important group of plants. - -The class among Ferns which has developed most directly out of the -Liverworts is the class of real Ferns, in the narrow sense of the word, -the _Frondose Ferns_ (Filices, or Phyllopterides, also called Pteridae). -In the present flora of the temperate zones this class forms only a -subordinate part, for it is in most cases represented only by low forms -without trunks. But in the torrid zones, especially in the moist, -steaming forests of tropical regions, this class presents us with the -lofty palm-like _fern trees_. These beautiful tree-ferns of the present -day, which form the chief ornament of our hot-houses, can however give -us but a faint idea of the stately and splendid frondose ferns of the -primary period, whose mighty trunks, densely crowded together, then -formed entire forests. These trunks, accumulated in super-incumbent -masses, are found in the coal seams of the Carboniferous period, and -between them, in an excellent state of preservation, are found the -impressions of the elegant fan-shaped leaves, crowning the top of the -trunk in an umbrella-like bush. The varied outlines and the -feather-like forms of these fronds, the elegant shape of the branching -veins or bunches of vessels in their tender foliage, can still be as -distinctly recognized in the impressions of the palaeolithic fronds as in -the fronds of ferns of the present day. In many cases even the clusters -of fruit, which are distributed on the lower surface of the fronds, are -distinctly preserved. After the Carboniferous period, the predominance -of frondose ferns diminished, and towards the end of the secondary -period they played almost as subordinate a part as they do at the -present time. - -The Calamariae, Ophioglossae, and Rhizocarpeae seem to have developed as -three diverging branches out of the Frondose Ferns, or Pteridae. The -Calamariae, or Calamophyta, have remained at the lowest level among these -three classes. The Calamariae comprise three different orders, of which -only one now exists, namely, the Horse-tails (Equisetaceae). The two -other orders, the Giant Reeds (Calamiteae), and the Star-leaf Reeds -(Asterophylliteae), are long since extinct. All Calamariae are -characterized by a hollow and jointed stalk, stem, or trunk, upon which -the branches and leaves (in cases where they exist) are set so as to -encircle the jointed stem in whorls. The hollow joints of the stalk are -separated from one another by partition walls. In Horse-tails and -Calamiteae the surface is traversed by longitudinal ribs running -parallel, as in the case of a fluted column, and the outer skin contains -so much silicious earth in the living forms, that it is used for -cleansing and polishing. In the Asterophylliteae, the star-shaped whorls -of leaves were more strongly developed than in the two other orders. -There exist, at present, of the Calamariae only the insignificant -Horse-tails (Equisetum), which grow in marshes and on moors; but during -the whole of the primary and secondary periods they were represented by -great trees of the genus Equisetites. There existed, at the same time, -the closely related order of the Giant Reeds (Calamites), whose strong -trunks grew to a height of about fifty feet. The order of the -Asterophyllites, on the other hand, contained smaller and prettier -plants, of a very peculiar form, and belongs exclusively to the primary -period. - -Among all Ferns, the history of the third class, that of the _Root_, or -_Aquatic Ferns_ (Rhizocarpeae, or Hydropteridae), is least known to us. In -their structure these ferns, which live in fresh water, are on the one -hand allied to the frond ferns, and on the other to the scaly ferns, but -they are more closely related to the latter. Among them are the but -little known moss ferns (Salvinia), clover ferns (Marsilea), and pill -ferns (Pilularia) of our fresh waters; further, the large Azolla which -floats in tropical ponds. Most of the aquatic ferns are of a delicate -nature, and hence ill-suited for being petrified. This is probably the -reason of their fossil remains being so scarce, and of the oldest of -those known to us having been found in the Jura system. It is probable, -however, that the class is much older, and that it was already -developed during the palaeolithic period out of other ferns by adaptation -to an aquatic life. - -The fourth class of ferns is formed by the _Tongue Ferns_ (Ophioglossae, -or Glossopterides). These ferns, to which belongs the Botrychium, as -well as the Ophioglossum (adder's-tongue) of our native genera, were -formerly considered as forming but a small sub-division of the frondose -ferns. But they deserve to form a special class, because they represent -important transitional forms from the Pterideae and Lepidophytes towards -higher plants, and must be regarded as among the direct progenitors of -the flowering plants. - -The fifth and last class is formed by the _Scale Ferns_ (Lepidophytes, -or Selagines). In the same way as the Ophioglossae arose out of the -frondose forms, the scale ferns arose out of the Ophioglossae. They were -more highly developed than all other ferns, and form the transition to -flowering plants, which must have developed out of them. Next to the -frondose ferns they took the largest part in the composition of the -palaeolithic fern forests. This class also contains, as does the class of -reed ferns, three nearly related but still very different orders, of -which only one now exists, the two others having become extinct towards -the end of the Carboniferous period. The scaled ferns still existing -belong to the order of the club-mosses (Lycopodiaceae). They are mostly -small, pretty moss-like plants, whose tender, many-branched stalk creeps -in curves on the ground like a snake, and is densely encompassed and -covered by small scaly leaves. The pretty creeping Lycopodium of our -woods, which mountain tourists twine round their hats, is known to all, -as also the still more delicate Selaginella, which under the name of -creeping moss is used to adorn the soil of our hot-houses in the form of -a thick carpet. The largest _club-mosses_ of the present day are found -in the Sunda Islands, where their stalks rise to the height of -twenty-five feet, and attain half a foot in thickness. But in the -primary and secondary periods even larger trees of this kind were widely -distributed, the most ancient of which probably were the progenitors of -the pines (Lycopodites). The most important dimensions were, however, -attained by the class of scale trees (Lepidodendreae), and by the seal -trees (Sigillarieae). These two orders, with a few species, appear in the -Devonian period, but do not attain their immense and astonishing -development until the Carboniferous period, and become extinct towards -the end of it, or in the Permian period directly following upon it. The -scale trees, or Lepidodendreae, were probably more closely related to -club-mosses than to Sigillarieae. They grew into splendid, straight, -unbranching trunks which divided at the top into numerous forked -branches. They bore a large crown of scaly leaves, and like the trunk -were marked in elegant spiral lines by the scars left at the base of the -leaf stalks which had fallen off. We know of scale-marked trees from -forty to sixty feet in length, and from twelve to fifteen feet in -diameter at the root. Some trunks are said to be even more than a -hundred feet in length. In the coal are found still larger accumulations -of the no less highly developed but more slender trunks of the -remarkable seal trees, Sigillarieae, which in many places form the -principal part of coal seams. Their roots were formerly described as -quite a distinct vegetable form (under the name of Stigmaria). The -Sigillarieae are in many respects very like the scale-trees, but differ -from them and from ferns in general in many ways. They were possibly -closely related to the extinct Devonian _Lycopterideae_, combining -characteristic peculiarities of the club-mosses and the frondose ferns, -which Strasburger considers as the hypothetical primary form of -flowering plants. - -In leaving the dense forests of the primary period, which were -principally composed of frond ferns (Lepidodendreae and Sigillarieae), we -pass onwards to the no less characteristic pine forests of the secondary -period. Thus we leave the domain of the Cryptogamia, the plants forming -neither flowers nor seeds, and enter the second main division of the -vegetable kingdom, namely, the sub-kingdom of the _Phanerogamia_, -_flowering plants_ forming seeds. This division, so rich in forms, -containing the principal portion of the present vegetable world, and -especially the majority of plants living on land, is certainly of a much -more recent date than the division of Cryptogamia. For it can have -developed out of the latter only in the course of the palaeolithic -period. We can with full assurance maintain that, during the whole -archilithic period, hence during the first and longer half of the -organic history of the earth, no flowering plants as yet existed, and -that they first developed during the primary period out of Cryptogamia -of the fern kind. The anatomical and embryological relation of -Phanerogamia to the latter is so close, that from it we can with -certainty infer their genealogical connection, that is, their true blood -relationship. Flowering plants cannot have directly arisen out of -thallus plants, nor out of mosses; but only out of ferns, or Filicines. -Most probably the scaled ferns, or Lepidophyta, and more especially -amongst these the Lycopodiaceae, forms closely related to the -Selaginella of the present day, have been the direct progenitors of the -Phanerogamia. - -On account of its anatomical structure and its embryological -development, the sub-kingdom of the Phanerogamia has for a long time -been divided into two large branches, into the _Gymnosperms_, or plants -with naked seeds, and the _Angiosperms_, or plants with enclosed seeds. -The latter are in every respect more perfect and more highly organized -than the former, and developed out of them only at a late date during -the secondary period. The Gymnosperms, both anatomically and -embryologically, form the transition group from Ferns to Angiosperms. - -The lower, more imperfect, and the older of the two main classes of -flowering plants, that of the _Archispermeae_, or _Gymnosperms_ (with -naked seeds), attained its most varied development and widest -distribution during the mesolithic or secondary epoch. It was no less -characteristic of this period, than was the fern group of the preceding -primary, and the Angiosperms of the succeeding tertiary, epoch. Hence we -might call the secondary epoch that of Gymnosperms, or after its most -important representatives, the era of Pine Forests. The Gymnosperms are -divided into three classes: the Coniferae, Cycadeae, and Gnetaceae. We find -fossil remains of the pines, or Conifers, and of the Cycads, even in -coal, and must infer from this that the transition from scaled ferns to -Gymnosperms took place during the Coal, or possibly even in the Devonian -period. However, the Gymnosperms play but a very subordinate part during -the whole of the primary epoch, and do not predominate over Ferns until -the beginning of the secondary epoch. - -Of the two classes of Gymnosperms just mentioned, that of the _Palm -Ferns_ (Zamiae, or Cycadeae) stands at the lowest stage, and is directly -allied to ferns, as the name implies, so that some botanists have -actually included them in the fern group. In their external form they -resemble palms, as well as tree ferns (or tree-like frond ferns), and -are adorned by a crown of feathery leaves, which is placed either on a -thick, short trunk, or on a slender, simple trunk like a pillar. At the -present day this class, once so rich in forms, is but scantily -represented by a few forms living in the torrid zones, namely, by the -coniferous ferns (Zamia), the thick-trunked bread-tree (Encephalartos), -and the slender-trunked Caffir bread-tree (Cycas). They may frequently -be seen in hot-houses, and are generally mistaken for palms. A much -greater variety of forms than occurs among the still existing palm ferns -(Cycadeae) is presented by the extinct and fossil Cycads, which occurred -in great numbers more towards the middle of the secondary period, during -the Jura, and which at that time principally determined the character of -the forests. - -The class of _Pines_, or _coniferous trees_ (Coniferae), has preserved -down to our day a greater variety of forms than have the palm ferns. -Even at the present time the trees belonging to it--cypresses, juniper -trees, and trees of life (Thuja), the box and ginko trees (Salisburya), -the araucaria and cedars, but above all the genus Pinus, which is so -rich in forms, with its numerous and important species, spruces, pines, -firs, larches, etc.--still play a very important part in the most -different parts of the earth, and almost of themselves constitute -extensive forests. Yet this development of pines seems but weak in -comparison with the predominance which the class had attained over other -plants during the early secondary period, that of the Trias. At that -time mighty coniferous trees--with but proportionately few genera and -species, but standing together in immense masses of individuals--formed -the principal part of the mesolithic forests. This fact justifies us in -calling the secondary period the "era of the pine forests," although the -remains of Cycadeae predominate over those of coniferous trees in the -Jura period.[2] - -From the pine forests of the mesolithic, or secondary period, we pass on -into the leafy forests of the caenolithic, or tertiary period, and we -arrive thus at the consideration of the sixth and last class of the -vegetable kingdom, that of the _Metaspermae_, _Angiospermae_, or _plants -with enclosed seeds_. The first certain and undoubted fossils of plants -with enclosed seeds are found in the strata of the chalk system, and -indeed we here find, side by side, remains of the two classes into which -the main class of Angiosperms is generally divided, namely, the _one -seed-lobed plants_, or _monocotylae_, and the _two seed-lobed plants_, or -_dicotylae_. However, the whole group probably originated at an earlier -period during the Trias. For we know of a number of doubtful and not -accurately definable fossil remains of plants from the Oolitic and Trias -(sic) periods, which some botanists consider to be Monocotylae, whilst -others consider them as Gymnosperms. In regard to the two classes of -plants with enclosed seeds, the Monocotylae and Dicotylae, it is -exceedingly probable that the Dicotyledons developed out of the -Gnetaceae, but that the Monocotyledons developed later out of a branch of -the dicotyledons. - -The class of _one seed-lobed plants_ (Monocotylae, or Monocotyledons, -also called Endogenae) comprises those flowering plants whose seeds -possess but one germ leaf or seed lobe (cotyledon). Each whorl of its -flower contains in most cases _three_ leaves, and it is very probable -that the mother plants of all Monocotyledons possessed a regular triple -blossom. The leaves are mostly simple, and traversed by simple, straight -bunches of vessels or "nerves." To this class belong the extensive -families of the rushes, grasses, lilies, irids, and orchids, further a -number of indigenous aquatic plants, the water-onions, sea grasses, -etc., and finally the splendid and highly developed families of the -Aroideae and Pandaneae, the bananas and palms. On the whole, the class of -Monocotyledons--in spite of the great variety of forms which it -developed, both in the tertiary and the present period--is much more -simply organized than the class of the Dicotyledons, and its history of -development also offers much less of interest. As their fossil remains -are for the most part difficult to recognize, it still remains at -present an open question in which of the three great secondary -periods--the Trias, Jura, or chalk period--the Monocotyledons -originated. At all events they existed in the chalk period as surely as -did the Dicotyledons. - -[Illustration: - - _Haeckel History of Creation._ - - _PL. V._ - -Relative lengths of the 5 Epochs in percentages. - - Quarternary Epoch 0.5 - Tertiary Epoch 2.3 - Secondary Epoch 11.5 - Primary Epoch 32.1 - Primordial Epoch 53.6 - ----- - _Total_ 100.0 - - Single-stemmed or - MONOPHYLETIC PEDIGREE - of the - VEGETABLE KINGDOM - based on Palaeontology.] - -The second class of plants with enclosed seeds, the _two seed-lobed_ -(Dicotylae, or Dicotyledons, also called Exogenae) presents much greater -historical and anatomical interest in the development of its subordinate -groups. The flowering plants of this class generally possess, as their -name indicates, two seed lobes or germ leaves (cotyledons). The number -of leaves composing its blossom is generally not three, as in most -Monocotyledons, but four, five, or a multiple of those numbers. Their -leaves, moreover, are generally more highly differentiated and more -composite than those of the Monocotyledons; they are traversed by -crooked, branching bunches of vessels or "veins." To this class belong -most of the leafed trees, and as they predominate in the tertiary period -as well as, at present, over the Gymnosperms and Ferns, we may call the -caenolithic period that of leafed forests. - -Although the majority of Dicotyledons belong to the most highly -developed and most perfect plants, still the lowest division of them is -directly allied to the Gymnosperms, and particularly to the Gnetaceae. In -the lower Dicotyledons, as in the case of the Monocotyledons, calyx and -corolla are as yet not differentiated. Hence they are called _Apetalous_ -(Monochlamydeae, or Apetalae). This sub-class must therefore doubtless be -looked upon as the original group of the Angiosperms, and existed -probably even during the Trias and Jura periods. Among them are most of -the leafed trees bearing catkins--birches and alders, willows and -poplars, beeches and oaks; further, the plants of the nettle -kind--nettles, hemp, and hops, figs, mulberries, and elms; finally, -plants like the spurges, laurels, and amaranth. - -It was not until the chalk period that the second and more perfect class -of the Dicotyledons appeared, namely, the _group with corollas_ -(Dichlamydeae, or Corolliflorae). These arose out of the Apetalae from the -simple cover of the blossoms of the latter becoming differentiated into -calyx and corolla. The sub-class of the Corolliflorae is again divided -into two large main divisions or legions, each of which contains a large -number of different orders, families, genera, and species. The first -legion bears the name of star-flowers, or Diapetalae, the second that of -the bell-flowers, or Gamopetalae. - -The lower and less perfect of the two legions of the Corolliflorae are -the star-flowers (also called Diapetalae or Dialypetalae). To them belong -the extensive families of the Umbelliferae, or umbrella-worts (wild -carrot, etc.), the Cruciferae, or cruciform blossoms (cabbage, etc.); -further, the Ranunculaceae (buttercups) and Crassulaceae, the Mallows and -Geraniums, and, besides many others, the large group of Roses (which -comprise, besides roses, most of our fruit trees), and the Pea-blossoms -(containing, among others, beans, clover, genista, acacia, and mimosa). -In all these Diapetalae the blossom-leaves remain separate, and never -grow together, as is the case in the Gamopetalae. These latter developed -first in the tertiary period out of the Diapetalae, whereas the Diapetalae -appeared in the chalk period together with the Apetalae. - -The highest and most perfect group of the vegetable kingdom is formed by -the second division of the Corolliflorae, namely, the legion of -bell-flowers (Gamopetalae, also called Monopetalae or Sympetalae). In this -group the blossom-leaves, which in other plants generally remain -separate, grow regularly together into a more or less bell-like, -funnel-shaped, or tubular flower. To them belong, among others, the -Bell-flowers and Convolvulus, Primroses and Heaths, Gentian and -Honeysuckle, further the family of the Olives (olive trees, privet, -elder, and ash), and finally, besides many other families, the -extensive division of the Lip-blossoms (Labiatae) and the Composites. In -these last the differentiation and perfection of the Phanerogamic -blossoms attain their highest stage of development, and we must -therefore place them at the head of the vegetable kingdom, as the most -perfect of all plants. In accordance with this, the legion of the -Gamopetalae appear in the organic history of the earth later than all the -main groups of the vegetable kingdom--in fact, not until the caenolithic -or tertiary epoch. In the earliest tertiary period the legion is still -very rare, but it gradually increases in the mid-tertiary, and attains -its full development only in the latest tertiary and the quaternary -period. - -Now if, having reached our own time, we look back upon the _whole -history of the development of the vegetable kingdom_, we cannot but -perceive in it a _grand confirmation of the Theory of Descent_. The two -great principles of organic development which have been pointed out as -the necessary results of natural selection in the Struggle for Life, -namely, the laws of _differentiation_ and _perfecting_, manifest -themselves everywhere in the development of the larger and smaller -groups of the natural system of plants. In each larger or smaller period -of the organic history of the earth, the vegetable kingdom increases -both in _variety_ and _perfection_, as a glance at Plate IV. will -clearly show. During the whole of the long primordial period there -existed only the lowest and most imperfect group, that of the Algae. To -these are added, in the primary period, the higher and more perfect -Cryptogamia, especially the main-class of Ferns. During the coal period -the Phanerogamia begin to develop out of the latter; at first, however, -they are represented only by the lower main-class, that of Gymnosperms. -It was not until the secondary period that the higher main-class, that -of Angiosperms, arose out of them. Of these also there existed at first -only the lower groups without distinct corollas, the Monocotyledons and -the Apetalae. It was not until the chalk period that the higher -Corolliflorae developed out of the latter. But even this most highly -developed group is represented, in the chalk period, only by the lower -stage of Star-flowers, or Diapetalae, and only at quite a late date, in -the tertiary period, did the more highly developed Bell-blossoms, -Gamopetalae, arise out of them, which at the same time are the most -perfect of all flowering plants. Thus, in each succeeding later division -of the organic history of the earth the vegetable kingdom gradually rose -to a higher degree of perfection and variety. - - - - -CHAPTER XVIII. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -I. ANIMAL-PLANTS AND WORMS. - - - The Natural System of the Animal Kingdom.--Linnaeus and Lamarck's - Systems.--The Four Types of Baer and Cuvier.--Their Increase to - Seven Types.--Genealogical Importance of the Seven Types as - Independent Tribes of the Animal Kingdom.--Derivation of - Zoophytes and Worms from Primaeval Animals.--Monophyletic and - Polyphyletic Hypothesis of the Descent of the Animal - Kingdom.--Common Origin of the Four Higher Animal Tribes out of - the Worm Tribe.--Division of the Seven Animal Tribes into - Sixteen Main Classes, and Thirty-eight Classes.--Primaeval - Animals (Monera, Amoebae, Synamoebae), Gregarines, Infusoria, - Planaeades, and Gastraeades (Planula and Gastrula).--Tribe of - Zoophytes.--Spongiae (Mucous Sponges, Fibrous Sponges, Calcareous - Sponges).--Sea Nettles, or Acalephae (Corals, Hood-jellies, - Comb-jellies).--Tribe of Worms. - - -The natural system of organisms which we must employ in the animal as -well as in the vegetable kingdom, as a guide in our genealogical -investigations, is in both cases of but recent origin, and essentially -determined by the progress of comparative anatomy and ontogeny (the -history of individual development) during the present century. Almost -all the attempts at classification made in the last century followed the -path of the artificial system, which was first established in a -consistent manner by Charles Linnaeus. The artificial system differs -essentially from the natural one, in the fact that it does not make the -whole organization and the internal structure (depending upon the blood -relationship) the basis of classification, but only employs individual, -and for the most part external, characteristics, which readily strike -the eye. Thus Linnaeus distinguished his twenty-four classes of the -vegetable kingdom principally by the number, formation, and combination -of the stamens. In like manner he distinguished six classes in the -animal kingdom principally by the nature of the heart and blood. These -six classes were: (1) Mammals; (2) Birds; (3) Amphibious Animals; (4) -Fishes; (5) Insects; and (6) Worms. - -But these six animal classes of Linnaeus are by no means of equal value, -and it was an important advance when, at the end of the last century, -Lamarck comprised the first four classes as vertebrate animals -(Vertebrata), and put them in contrast with the remaining animals (the -insects and worms of Linnaeus), of which he made a second main -division--the invertebrate animals (Invertebrata). In reality Lamarck -thus agreed with Aristotle, the father of Natural History, who had -distinguished these two main groups, and called the former -_blood-bearing animals_, the latter _bloodless animals_. - -The next important progress towards a natural system of the animal -kingdom was made some decades later by two most illustrious zoologists, -Carl Ernst Baer and George Cuvier. As has already been remarked, they -established, almost simultaneously and independently of one another, the -proposition that it was necessary to distinguish several completely -distinct main groups in the animal kingdom, each of which possessed an -entirely peculiar type or structure (compare above, vol. i. p. 53). In -each of these main divisions there is a tree-shaped and branching -gradation from most simple and imperfect forms to those which are -exceedingly composite and highly developed. The _degree of development_ -within each type is quite independent of the peculiar _plan of -structure_, which forms the basis of the type and gives it a special -characteristic. The "type" is determined by the peculiar relations in -position of the most important parts of the body, and the manner in -which the organs are connected. The degree of development, however, is -dependent upon the greater or less division of labour among organs, and -on the differentiation of the plastids and organs. This extremely -important and fruitful idea was established by Baer, who relied more -distinctly and thoroughly upon the history of individual development -than did Cuvier. Cuvier based his argument upon the results of -comparative anatomy. But neither of them recognized the true cause of -the remarkable relationships pointed out by them, which is first -revealed to us by the Theory of Descent. It shows us that the common -_type_ or plan of structure is determined by _inheritance_, and the -degree of development or differentiation by _adaptation_. (Gen. Morph. -ii. 10). - -Both Baer and Cuvier distinguished four different types in the animal -kingdom, and divided it accordingly into four great main divisions -(branches or circles). The first of these is formed by the vertebrate -animals (Vertebrata), and comprises Linnaeus' first four -classes--mammals, birds, amphibious animals, and fishes. The second type -is formed by the articulated animals (Articulata), containing Linnaeus' -insects, consequently the six-legged insects, and also the myriopods, -spiders, and crustacea, but besides these, a large number of the worms, -especially the ringed worms. The third main division comprises the -molluscous animals (Mollusca)--slugs, snails, mussels, and some kindred -groups. Finally, the fourth and last circle of the animal kingdom -comprises the various radiated animals (Radiata), which at first sight -differ from the three preceding types by their radiated, flower-like -form of body. For while the bodies of molluscs, articulated animals, and -vertebrated animals consist of two symmetrical lateral halves--of two -counterparts or antimera, of which the one is the mirror of the -other--the bodies of the so-called radiated animals are composed of more -than two, generally of four, five, or six counterparts grouped round a -common central axis, as in the case of a flower. However striking this -difference may seem at first, it is, in reality, a very subordinate one, -and the radial form has by no means the same importance in all "radiated -animals." - -The establishment of these natural main groups or types of the animal -kingdom by Baer and Cuvier was the greatest advance in the classification -of animals since the time of Linnaeus. The three groups of vertebrated -animals, articulated animals, and molluscs are so much in accordance -with nature that they are retained, even at the present day, little -altered in extent. But a more accurate knowledge soon showed the utterly -unnatural character of the group of the radiated animals. Leuckart, in -1848, first pointed out that two perfectly distinct types were -confounded under the name, namely, the _Star-fishes_ (Echinoderma)--the -sea-stars, lily encrinites, sea-urchins, and sea-cucumbers; and, on the -other hand, the _Animal-plants_, or _Zoophytes_ (Coelenterata or -Zoophyta)--the sponges, corals, hood-jellies, and comb-jellies. At the -same time, Siebold united the Infusoria with the Rhizopoda, under the -name of Protozoa (lowest animals), into a special main division of the -animal kingdom. By this the number of animal types was increased to six. -It was finally increased to seven by the fact that modern zoologists -separated the main division of the articulated animals into two groups: -(_a_) those possessing _articulated feet_ (Arthropoda), corresponding to -Linnaeus' Insects, namely, the Flies (with six legs), Myriopods, Spiders, -and Crustacea; and (_b_) the footless _Worms_ (Vermes), or those -possessing non-articulated feet. These latter comprise only the real or -genuine Worms (ring-worms, round worms, planarian worms, etc.), and -therefore in no way correspond with the Worms of Linnaeus, who had -included the molluscs, the radiates, and many other lower animals under -this name. - -Thus, according to the views of modern zoologists, which are given in -all recent manuals and treatises on zoology, the animal kingdom is -composed of seven completely distinct main divisions or types, each of -which is distinguished by a characteristic plan of structure peculiar to -it, and perfectly distinct from every one of the others. In the natural -system of the animal kingdom--which I shall now proceed to explain as -its probable pedigree--I shall on the whole agree with this usual -division, but not without some modifications, which I consider very -important in connection with genealogy, and which are rendered -absolutely necessary in consequence of our view as to the history of the -development of animals. - -We evidently obtain the greatest amount of information concerning the -_pedigree of the animal kingdom_ (as well as concerning that of the -vegetable kingdom) from comparative anatomy and ontogeny. Besides -these, palaeontology also throws much valuable light upon the historical -succession of many of the groups. From numerous facts in comparative -anatomy, we may, in the first place, infer the _common origin of all -those animals which belong to one of the seven "types."_ For in spite of -all the variety in the external form developed within each of these -types, the essential relative position of the parts of the body which -determines the type, is so constant, and agrees so completely in all the -members of every type, that on account of their relations of form alone -we are obliged to unite them, in the natural system, into a single main -group. But we must certainly conclude, moreover, that this conjunction -also has its expression in the pedigree of the animal kingdom. For the -true cause of the intimate agreement in structure can only be the actual -blood relationship. Hence we may, without further discussion, lay down -the important proposition that all animals belonging to one and the same -circle or type must be descended from one and the same original primary -form. In other words, the idea of the circle or type, as it is employed -in zoology since Baer and Cuvier's time to designate the few principal -main groups or "sub-kingdoms" of the animal kingdoms, coincides with the -idea of "tribe" or "phylum," as employed by the Theory of Descent. - -If, then, we can trace all the varieties of animal forms to these seven -fundamental forms, the following question next presents itself to us as -a second phylogenetic problem--Where do these seven animal tribes come -from? Are they seven original primary forms of an entirely independent -origin, or are they also distantly related by blood to one another? - -[Illustration: _PL. VI._ - -Historical Growth of the six great stems of Animals. _See the -Explanation._] - -At first we might be inclined to answer this question in a -_polyphyletic_ sense, by saying that we must assume, for each of the -seven great animal tribes, at least one independent primary form -completely distinct from the others. On further considering this -difficult problem, we arrive in the end at the notion of a -_monophyletic_ origin of the animal kingdom, viz., that these seven -primary forms are connected at their lowest roots, and that they are -derived from a single, common primaeval form. _In the animal as well as -in the vegetable kingdom, when closely and accurately considered, the -monophyletic hypothesis of descent is found to be more satisfactory than -the polyphyletic hypothesis._ - -It is _comparative ontogeny_ (embryology) which first and foremost leads -to the assumption of the monophyletic origin of the whole animal kingdom -(the Protista excepted of course). The zoologist who has thoughtfully -compared the history of the individual development of various animals, -and has understood the importance of the biogenetic principle (p. 33), -cannot but be convinced that a common root must be assumed for the seven -different animal tribes, and that all animals, including man, are -derived from a single, common primary form. The result of the -consideration of the facts of embryology, or ontogeny, is the following -genealogical or phylogenetic hypothesis, which I have put forward and -explained in detail in my "Philosophy of Calcareous Sponges" (Monograph -of the Calcareous Sponges, vol. i. pp. 464, 465, etc.,--"the Theory of -the Layers of the Embryo, and the Pedigree of Animals"). - -The first stage of organic life in the Animal kingdom (as in the -Vegetable and Protista kingdoms) was formed by perfectly simple -_Monera_, originating by spontaneous generation. The former existence -of this simplest animal form is, even at present, attested by the fact -that the egg-cell of many animals loses its kernel directly after -becoming fructified, and thus relapses to the lower stage of development -of a cytod without a kernel, like a Moneron. This remarkable occurrence -I have interpreted, according to the law of latent inheritance (vol. i. -p. 205), as a phylogenetic _relapse_ of the cellular form into the -original form of a cytod. The _Monerula_, as we may call this egg-cytod -without a kernel, repeats then, according to the biogenetic principle -(vol. ii. p. 33), the most ancient of all animal forms, the common -primary form of the animal kingdom, namely, the Moneron. - -The second ontogenetic process consists in a new kernel being formed in -the Monerula, or egg-cytod, which thus returns again to the value of a -true _egg-cell_. According to this, we must look upon the simple animal -cell, containing a kernel, or the single-celled primaeval animal--which -may still be seen in a living state in the _Amoebae_ of the present -day--as the _second_ step in the series of phylogenetic forms of the -animal kingdom. Like the still living simple Amoebae, and like the naked -egg-cells of many lower animals (for example, of Sponges and Medusae, -etc.), which cannot be distinguished from them, the remote phyletic -primary Amoebae also were perfectly simple naked-cells, which moved about -in the Laurentian primaeval ocean, creeping by means of the ever-changing -processes of their body-substance, and nourishing and propagating -themselves in the same way as the Amoebae of the present day. (Compare -vol. i. p. 188, and vol. ii. p. 54.) The existence of this Amoeba-like, -_single-celled primary form_ of the whole animal kingdom is unmistakably -indicated by the exceedingly important fact that the egg of all animals, -from those of sponges and worms up to those of the ant and man, is a -simple cell. - -Thirdly, from the "single-cell" state arose the _simplest multicellular -state_, namely, a heap or a small community of simple, equi-formal, and -equivalent cells. Even at the present day, in the ontogenetic -development of every animal egg-cell, there first arises a globular heap -of equi-formal naked cells, by the repeated self-division of the primary -cell. (Compare vol. i. p. 190 and the Frontispiece, Fig. 3.) We called -this accumulation of cells the _mulberry state_ (Morula), because it -resembles a mulberry or blackberry. This Morula-body occurs in the same -simple form in all the different tribes of animals, and on account of -this most important circumstance we may infer--according to the -biogenetic principle--that the _most ancient, many-celled, primary form -of the animal kingdom_ resembled a Morula like this, and was in fact a -simple heap of Amoeba-like primaeval cells, one similar to the other. We -shall call this most ancient community of Amoebae--this most simple -accumulation of animal cells--which is recapitulated in individual -development by the Morula--the _Synamoeba_. - -Out of the Synamoebae, in the early Laurentian period, there afterwards -developed a fourth primary form of the animal kingdom, which we shall -call the ciliated germ (Planaea). This arose out of the Synamoeba by the -outer cells on the surface of the cellular community beginning to extend -vibrating fringes called cilia, and becoming "ciliated cells," and thus -differentiating from the inner and unchanged cells. The Synamoebae -consisted of completely equi-formed and naked cells, and crept about -slowly, at the bottom of the Laurentian primaeval ocean, by means of -movements like those of an Amoeba. The Planaea, on the other hand, -consisted of two kinds of different cells--inner ones like the Amoebae, -and external "ciliated cells." By the vibrating movements of the cilia -the entire multicellular body acquired a more rapid and stronger motion, -and passed over from the creeping to the swimming mode of locomotion. In -exactly the same manner the _Morula_, in the ontogenesis of lower -animals, still changes into a ciliated form of larva, which has been -known, since the year 1847, under the name of _Planula_. This Planula is -sometimes a globular, sometimes an oval body, which swims about in the -water by means of a vibrating movement; the fringed (ciliated) and -smaller cells of the surface differ from the larger inner cells, which -are unfringed. (Fig. 4 of the Frontispiece.) - -Out of this Planula, or fringed larva, there then develops, in animals -of all tribes, an exceedingly important and interesting animal form, -which, in my Monograph of the Calcareous Sponges, I have named -_Gastrula_ (that is, larva with a stomach or intestine). (Frontispiece, -Fig. 5, 6). This Gastrula externally resembles the Planula, but differs -essentially from it in the fact that it encloses a cavity which opens to -the outside by a mouth. The cavity is the "_primary intestine_," or -"primary stomach," the _progaster_, the first beginning of the -alimentary canal; its opening is the "_primary mouth_" (prostoma). The -wall of the progaster consists of two layers of cells: an outer layer of -smaller ciliated cells (outer skin, or ectoderm), and of an inner layer -of larger non-ciliated cells (inner skin, or entoderm). This exceedingly -important larval form, the "Gastrula," makes its appearance in the -ontogenesis of all tribes of animals--in Sponges, Medusae, Corals, Worms, -Sea-squirts, Radiated animals, Molluscs, and even in the lowest -Vertebrata (Amphioxus: compare p. 200, Plate XII., Fig. _B_ 4; see also -in the same place the Ascidian, Fig. _A_ 4). - - - Definition of the _forms_ | +Ontogenesis.+ | +Phylogenesis.+ - of the five first stages | The five first stages | The five first stages - of the development of | of the individual | of the phyletic or - the animal body. | development. | historical development. - -------------------------------+------------------------------+------------------------ - | | - _First Stage of Development._ | 1. | 1. - | +Monerula.+ | +Moneron.+ - A simple cytod (a | | - plastid without a kernel.) | Animal egg without a | Most ancient animal - | | kernel (when the egg-kernel | Monera, originating by - | | has disappeared, | spontaneous generation. - | | after being fructified). | | - | | | | | - | | | | | - _Second Stage of Development._ | 2. | 2. - | +Ovulum.+ | +Amoebae.+ - A simple cell (a | | - plastid containing a | Animal egg with kernel | Animal Amoebae. - kernel.) | (a simple egg-cell). | | - | | | | | - | | | | | - | | | | | - _Third Stage of Development._ | 3. | 3. - | +Morula.+ | +Synamoeba.+ - A community (an | (_Mulberry form._) | - aggregation of identical | | An aggregation of - simple cells). | Globular heap of homogeneous | Amoebae. - | | "cleavage spheres." | | - | | | | | - | | | | | - _Fourth Stage of Development._ | 4. | 4. - | +Planula.+ | +Planaea.+ - A solid or bladder-shaped, | (_Ciliated larva_.) | - globular, or oval | | Many-celled primaeval - body, _composed of two | Many-celled larva | animal without - kinds of different cells_: | without mouth, composed | mouth, composed of - externally ciliated, | of different cells. | two kinds of different - internally non-ciliated | | | cells. - cells. | | | | - | | | | | - | | | | | - _Fifth Stage of Development._ | 5. | 5. - | +Gastrula.+ | +Gastraea.+ - A globular or oval | (_Larva with mouth._) | - _body with simple intestinal | Many-celled with intestines | Many-celled primaeval - cavity and mouth-opening. | and mouth; intestinal | animal with intestine - Body wall composed | wall with two | and mouth; intestinal - of two layers_; an | layers. | wall with two - externally ciliated ectoderm | | layers. (Primary form - (dermal layer), an | | of zoophytes and - internally non-ciliated | | worms.) - entoderm (gastral layer). | | - - -From the ontogenetic occurrence of the Gastrula in the most different -animal classes, from Zoophytes up to Vertebrata, we may, according to -the biogenetic principle, safely draw the conclusion that during the -Laurentian period there existed a common primary form of the six higher -animal tribes, which in all essential points was formed like the -Gastrula, and which we shall call the Gastraea. This Gastraea possessed a -perfectly simple globular or oval body, which enclosed a simple cavity -of like form, namely, the progaster; at one of the poles of the -longitudinal axis the primary intestine opened by a mouth which served -for the reception of nutrition. The body wall (which was also the -intestinal wall) consisted of two layers of cells, the unfringed -entoderm, or intestinal layer, and the fringed ectoderm, or skin-layer; -by the motion of the cilia or fringes of the latter the Gastraea swam -about freely in the Laurentian ocean. Even in those higher animals, in -the ontogenesis of which the original Gastrula form has disappeared, -according to the laws of abbreviated inheritance (vol. i. p. 212), the -composition of the Gastraea body has been transmitted to the phase of -development which directly arises out of the Morula. This phase is an -oval or round disc consisting of two cell-layers or membranes: the outer -cell-layer, the _animal or dermal layer_ (ectoblast), corresponds to the -ectoderm of the Gastraea; out of it develops the external, loose skin -(epidermis), with its glands and appendages, as well as the central -nervous system. The inner cell-layer, the _vegetative or intestinal -layer_ (hypoblast), is originally the entoderm of the Gastraea; out of it -develops the inner membrane (epithelium) of the intestinal canal and its -glands. (Compare my Monograph of the Calcareous Sponges, vol. i. p. 466, -etc.) - -By ontogeny we have already gained five primordial stages of development -of the animal kingdom: (1) the Moneron; (2) the Amoeba; (3) the -Synamoeba; (4) the Planaea; and (5) the Gastraea. The former existence of -these five oldest primary forms, which succeeded one another, and which -must have lived in the Laurentian period, follows as a consequence of -the biogenetic principle; that is to say, from the parallelism and the -mechanico-causal connection of ontogenesis and phylogenesis. (Compare -vol. i. p. 309.) In our genealogical system of the animal kingdom we may -class all these animal forms, long since extinct, and, which on account -of the soft nature of their bodies could leave no fossil remains, among -the tribe of Primaeval animals (Protozoa), which also comprises the still -living Infusoria and Gregarinae. - -The phyletic development of the six higher animal tribes, which are all -derived from the Gastraea, deviated at this point in two directions. In -other words, the _Gastraeads_ (as we may call the group of forms -characterized by the Gastraea-type of structure), divided into two -divergent lines or branches; the one branch of Gastraeads gave up free -locomotion, adhered to the bottom of the sea, and thus, by adopting an -adhesive mode of life, gave rise to the _Protascus_, the common primary -form of the _Animal-plants_ (Zoophyta). The other branch of the -Gastraeads retained free locomotion, did not become adherent and later -on developed into the _Prothelmis_, the common primary form of _Worms_ -(Vermes). (Compare p. 133.) - -This latter tribe (as limited by modern zoology) is of the greatest -interest in the study of genealogy. For among Worms, as we shall see -later, there are, besides very numerous peculiar families, and besides -many independent classes, also very remarkable forms, which may be -considered as _forms of direct transition_ to the four higher animal -tribes. Both comparative anatomy and the ontogeny of these worms enable -us to recognize in them the nearest blood relations of those extinct -animal forms which were the original primary forms of the four higher -animal tribes. Hence these latter, the Molluscs, Star-fishes, -Articulated animals, and Vertebrate animals, do not stand in any close -blood relationship to one another, but have originated independently in -four different places out of the tribe of Worms. - -In this way comparative anatomy and phylogeny lead us to the -_monophyletic pedigree of the animal kingdom_, the outlines of which are -given on p. 133. According to it the seven phyla, or tribes, of the -animal kingdom are of different value in regard to genealogy. The -original primary group of the whole animal kingdom is formed by the -Primaeval animals (Protozoa), including the Infusoria and Gastraeads. Out -of these latter arose the two tribes of Animal-plants (Zoophyta) and -Worms as diverging branches. Out of four different groups of the Worm -tribe, the four higher tribes of the animal kingdom were developed--the -Star-fishes (Echinoderma) and Insects (Arthropoda) on the one hand, and -the Molluscs (Mollusca) and Vertebrated animals (Vertebrata) on the -other. - -Having thus sketched out the monophyletic pedigree of the animal kingdom -in its most important features, we must now turn to a closer examination -of the historical course of development which the seven tribes of the -animal kingdom, and the classes distinguished in them, have passed -through (p. 132). There is a much larger number of classes in the animal -than in the vegetable kingdom, owing to the simple reason that the -animal body, in consequence of its more varied and perfect vital -activity, could differentiate and develop in very many more different -directions than could the vegetable body. Thus, while we were able to -divide the whole vegetable kingdom into six main classes and nineteen -classes, we have to distinguish, at least, sixteen main classes and -thirty-eight classes in the animal kingdom. These are distributed among -the seven different tribes of the animal kingdom in the way shown in the -Systematic Survey on pages 132 and 133. - -The group of _Primaeval animals_ (Protozoa) within the compass which we -here assign to this tribe, comprises the most ancient and the simplest -primary forms of the animal kingdom; for example, the five oldest -phyletic stages of development previously mentioned, and besides these -the Infusoria and Gregarinae, as well as all those imperfect animal -forms, for which, on account of their simple and indifferent -organization, no place can be found in any of the other six animal -tribes. Most zoologists, in addition to these, include among the -Protozoa a larger or smaller portion of those lowest organisms, which we -mentioned in our neutral kingdom of Protista (in Chapter XVI.). But -these Protista, especially the large division of the Rhizopoda, which -are so rich in forms, cannot be considered as real animals for reasons -previously given. Hence, if we here leave them out of the question, we -may accept two main classes or provinces of real Protozoa, namely, _Egg -animals_ (Ovularia) and _Germ animals_ (Blastularia). To the former -belong the three classes of Archezoa, Gregarinae, and Infusoria, to the -latter the two classes of Planaeads and Gastraeads. - -SYSTEMATIC SURVEY - -_Of the 16 Main Classes and 38 Classes of the Animal Kingdom._ - - - ------------------+-----------------------+----------------------+----------------- - _Tribes or Phyla_ | _Main Classes_, | _Classes_ |_Systematic Name_ - _of the_ |_Branches or Clades_ | _of the_ | _of the_ - _Animal Kingdom._ | _of the_ | _Animal Kingdom._ | _Classes._ - | _Animal Kingdom._ | | - ------------------+-----------------------+----------------------+------------------ - - A. { - =Primaeval= { I. Egg-animals { 1. Archaic animals 1. Archezoa - =Animals= { _Ovularia_ { 2. Gregarines 2. Gregarinae - { { 3. Infusoria 3. Infusoria - +Protozoa+ { - {II. Mulberry animals { 4. Planaeads 4. Planaeadas - { _Blastularia_ { 5. Gastraeads 5. Gastraeadas - - - B. { - =Animal= { III. Sponges { 6. Sponges 6. Porifera - =Plants= { _Spongiae_ { - { - +Zoophyta+ { IV. Sea-nettles { 7. Corals 7. Coralla - { _Acalephae_ { 8. Hood-jellies 8. Hydromedusae - { { 9. Comb-jellies 9. Ctenophora - - - C. {V. Bloodless worms {10. Planary worms 10. Platyhelminthes - =Worms= { _Acoelomi_ - { {11. Round worms 11. Nemathelminthes - +Vermes+ { VI. Blood-bearing {12. Moss-polyps 12. Bryozoa - { worms {13. Sac-worms 13. Tunicata - { _Coelomati_ {14. Proboscideans 14. Rhynchocoela - { {15. Star-worms 15. Gephyrea - { {16. Wheel animalcules 16. Rotatoria - { {17. Ring-worms 17. Annelida - - - D. {VII. Headless shellfish {18. Lamp-shells 18. Spirobranchia - =Molluscs= { _Acephala_ {19. Mussels 19. Lamellibranchia - { - +Mollusca+ { VIII. Head-bearing {20. Snails 20. Cochlides - { _Eucephala_ {21. Cuttles 21. Cephalopoda - - - E. { IX. Ringed-arms {22. Sea-stars 22. Asterida - =Star-fishes= { _Colobrachia_ {23. Lily-stars 23. Crinoida - { - +Echinoderma+ { X. Armless {24. Sea-urchins 24. Echinida - { _Lipobrachia_ {25. Sea-cucumbers 25. Holothuriae - - - F. { XI. Gill-breathers {26. Crab-fish 26. Crustacea - =Articulated= { _Carides_ { - =Animals= { - { XII. Tube-breathers {27. Spiders 27. Arachnida - +Arthropoda+ { _Tracheata_ {28. Centipedes 28. Myriopoda - { {29. Flies 29. Insecta - - - { XIII. Skull-less {30. Lancelets 30. Leptocardia - { _Acrania_ { - G. { - =Vertebrate= { XIV. Single-nostriled {31. Lampreys 31. Cyclostoma - =Animals= { _Monorrhina_ { - { - +Vertebrata+ { XV. Amnion-less {32. Fishes 32. Pisces - { _Anamnia_ {33. Mud-fish 33. Dipneusta - { {34. Sea dragons 34. Halisauria - { {35. Amphibians 35. Amphibia - { - { XVI. Amnion-bearing {36. Reptiles 36. Reptilia - { _Amniota_ {37. Birds 37. Aves - { {38. Mammals 38. Mammalia - - ---------------------------------------------------------------- - - +Vertebrata+ - (_Vertebrated animals_) - Craniota - | - +Arthropoda+ | +Mollusca+ - (_Articulated Animals_) | (_Molluscs_) - +Echinoderma+ Tracheata | Eucephala - (_Star-fishes_) | | | - | | | - Lipobrachia Crustacea Acrania | - | Annelida | | Tunicata Acephala - | | | | | Bryozoa | - Colobrachia | | | | | | - | Gephyrea| | Rotatoria \--v---/ \--v---/ - | | | | | | | - | | | | | | | - \---------v-------------------/ \------v-----/ - | | - | +Vermes+ | - | (_Worms_) | - \------------------v-------------------/ - | - | - COELOMATI - (_Worms with a body-cavity_) - | Platyhelminthes - | | - | | - \-----v------/ - +Zoophyta+ | - (_Animal-Plants_) +ACOELOMI+ - Spongiae Acalephae (_Worms without body-cavity_) - | | | - | | | - \------v-------/ | - | | - Protascus Prothelmis - | | - | | - \-----------v---------------/ - | - | +Protozoa+ - | (_Primaeval animals_) - | - |/-------------^-------------\ - +GASTRAEA+ - | - | Infusoria - | | - +PLANAEA+ | Gregarinae - | | | - | | | - +SYNAMOEBAE+ \----v---/ - | | - | | - \---------v--------/ - +AMOEBAE+ - | - +MONERA+ - - -The first province of the Protozoa consists of the _Egg animals_ -(Ovularia); we include among them all _single-celled animals_, all -animals whose body, in the fully developed state, possesses the -form-value of a _simple plastid_ (of a cytod or a cell), also those -simple animal forms whose body consists of an aggregation of several -cells perfectly similar one to another. - -The _Archaic animals_ (Archezoa) form the first class in the series of -Egg animals. It contains only the most simple and most ancient primary -forms of the animal kingdom, whose former existence we have proved by -means of the fundamental law of biogenesis; they are, (1) Animal Monera; -(2) Animal Amoebae; (3) Animal Synamoebae. We may, if we choose, include -among them a portion of the still living Monera and Amoebae, but another -portion (according to the discussion in Chapter XVI.) must on account of -their neutral nature be considered as Protista, and a third portion, on -account of their vegetable nature, must be considered as plants. - -A second class of the egg animals consists of the _Gregarines_ -(Gregarinae), which live as parasites in the intestines and body-cavities -of many animals. Some of these Gregarines are perfectly simple cells -like the Amoebae; some form chains of two or three identical cells, one -lying behind the other. They differ from the naked Amoebae by possessing -a thick, simple membrane, which surrounds their cell-body; they can be -considered as animal Amoebae which have adopted a parasitical mode of -life, and in consequence have surrounded themselves with a secreted -covering. - -As a third class of egg animals, we adopt the real _Infusoria_ -(Infusoria), embracing those forms to which modern zoology almost -universally limits this class of animals. The principal portion of them -consists of the small _ciliated Infusoria_ (Ciliata), which inhabit all -the fresh and salt waters of the earth in great numbers, and which swim -about by means of a delicate garb of vibratile fringes. A second and -smaller division consists of the adherent _sucking Infusoria_ (Acinetae), -which take their food by means of fine sucking-tubes. Although during -the last thirty years numerous and very careful investigations have been -made on these small animalcules,--which are mostly invisible to the -naked eye,--still we are even now not very sure about their development -and form-value. We do not even yet know whether the Infusoria are single -or many-celled; but as no investigator has as yet proved their body to -be a combination of cells, we are, in the mean time, justified in -considering them as single-celled, like the Gregarines and the Amoebae. - -The second main class of primaeval animals consists of the _Germ animals_ -(Blastularia). This name we give to those extinct Protozoa which -correspond to the two ontogenetic embryonic forms of the six higher -animal tribes, namely, the Planula and the Gastrula. The body of these -Blastularia, in a perfectly developed state, was composed of many cells, -and these cells moreover differentiated--in two ways at least--into an -external (animal or dermal) and an internal (vegetative or gastral) -mass. Whether there still exist representatives of this group is -uncertain. Their former existence is undoubtedly proved by the two -exceedingly important ontogenetic animal forms which we have already -described as Planula and Gastrula, and which still occur as a transient -stage of development in the ontogeny of the most different tribes of -animals. Corresponding to these, we may, according to the biogenetic -principle, assume the former existence of two distinct classes of -Blastularia, namely, the _Planaeada_ and _Gastraeada_. The type of the -_Planaeada_ is the _Planaea_--long since extinct--but whose historical -portrait is still presented to us at the present day in the widely -distributed _ciliated larva_ (Planula). (Frontispiece, Fig. 4.) The type -of the _Gastraeada_ is the _Gastraea_, of whose original nature the -mouth-and-stomach larva (Gastrula), which recurs in the most different -animal tribes, still gives a faithful representation. (Frontispiece Fig. -5, 6.) Out of the Gastraea, as we have previously mentioned, there were -at one time developed two different primary forms, the Protascus and -Prothelmis; the former must be looked upon as the primary form of the -Zoophytes, the latter as the primary form of Worms. (Compare the -enunciation of this hypothesis in my Monograph of the Calcareous -Sponges, vol i. p. 464.) - -The _Animal-plants_ (Zoophyta, or Coelenterata) which constitute the -second tribe of the animal kingdom, rise considerably above the -primitive animals in the characters of their whole organisation, while -they remain far below most of the higher animals. For in the latter -(with the exception only of the lowest forms) the four distinct -functions of nutrition--namely, digestion, circulation of the blood, -respiration, and excretion--are universally accomplished by four -perfectly different systems of organs: by the intestines, the vascular -system, the organs of respiration, and the urinary apparatus. In -Zoophytes, however, these functions and their organs are not yet -separate, and are all performed by a single system of alimentary canals, -by the so-called gastro-vascular system, or the coelenteric apparatus of -the intestinal cavity. The mouth, which is also the anus, leads into a -stomach, into which the other cavities of the body also open. In -Zoophytes the body-cavity, or "coeloma," possessed by the four higher -tribes of animals is still completely wanting, likewise the vascular -system and blood, as also the organs of respiration, etc. - -All Zoophytes live in water; most of them in the sea, only a very few in -fresh water, such as fresh-water sponges (Spongilla) and some primaeval -polyps (Hydra, Cordylophora). A specimen of the pretty flower-like forms -which are met with in great variety among Zoophytes is given on Plate -VII. (Compare its explanation in the Appendix.) - -The tribe of animal-plants, or Zoophytes, is divided into two distinct -provinces, the _Sponges_, or _Spongiae_, and the _Sea-nettles_, or -_Acalephae_ (p. 144). The latter are much richer in forms and more highly -organized than the former. In all Sponges the entire body, as well as -the individual organs, are differentiated and perfected to a much less -extent than in Sea-nettles. All Sponges lack the characteristic -_nettle-organs_ which all Sea-nettles possess. - -The common primary form of all Zoophytes must be looked for in the -_Protascus_, an animal form long since extinct, but whose existence is -proved according to the biogenetic principle by the Ascula. This Ascula -is an ontogenetical development form which, in Sponges as well as in -Sea-nettles, proceeds from the Gastrula. (Compare the Ascula of the -calcareous sponge on the Frontispiece, Fig. 7, 8.) For after the -Gastrula of zoophytes has for a time swum about in the water it sinks to -the bottom, and there adheres by that pole of its axis which is opposite -to the opening of the mouth. The external cells of the ectoderm draw in -their vibrating, ciliary hairs, whereas, on the contrary, the inner -cells of the entoderm begin to form them. Thus the Ascula, as we call -this changed form of larva, is a simple sack, its cavity (the cavity of -the stomach or intestine) opening by a mouth externally, at the upper -pole of the longitudinal axis (opposite the basal point of fixture). The -entire body is here in a certain sense a mere stomach or intestinal -canal, as in the case of the Gastrula. The wall of the sack, which is -both body wall and intestinal wall, consists of two layers or coats of -cells, a fringed _entoderm_, or gastral layer (corresponding with the -inner or vegetative germ-layer of the higher animals), and an unfringed -exoderm or dermal layer (corresponding with the external or animal -germ-layer of the higher animals). The original _Protascus_, a true -likeness of which is still furnished by the Ascula, probably formed -egg-cells and sperm-cells out of its gastral layer. - -The Protascads--as we will call the most ancient group of vegetable -animals, represented by the Protascus-type--divided into two lines or -branches, the Spongiae and the Sea-nettles, or Acalephae. I have shown in -my Monograph of the Calcareous Sponges (vol. i. p. 485) how closely -these two main classes of Zoophytes are related, and how they must both -be derived, as two diverging forms, from the Protascus-form. The primary -form of Spongiae, which I have there called Archispongia, arose out of -the Protascus by the formation of pores through its body-wall; the -primary form of Sea-nettles, which I there called Archydra, developed -out of the Protascus by the formation of nettle-organs, as also by the -formation of feelers or tentacles. - -The main-class or branch of the _Sponges_, _Spongiae_, or _Porifera_, -lives in the sea, with the single exception of the green fresh-water -Sponge (Spongilla). These animals were long considered as plants, later -as Protista; in most Manuals they are still classed among the primaeval -animals, or Protozoa. But since I have demonstrated their development -out of the Gastrula, and the construction of their bodies of two -cellular germ-layers (as in all higher animals), their close -relationship to Sea-nettles, and especially to the Hydrapolyps, seems -finally to be established. The _Olynthus_ especially, which I consider -as the common primary form of calcareous sponges, has thrown a complete -and unmistakable light upon this point. - -The numerous forms comprised in the class of Spongiae have as yet been -but little examined; they may be divided into three legions and eight -orders. The first legion consists of the soft, gelatinous _Mucous -Sponges_ (Myxospongiae), which are characterized by the absence of any -hard skeleton. Among them are, on the one hand, the long-since-extinct -primary forms of the whole class, the type of which I consider to be the -Archispongia; on the other hand there are the still living, gelatinous -sponges, of which the _Halisarca_ is best known. We can obtain a notion -of the Archispongia, the most ancient primaeval sponge, if we imagine the -Olynthus (see Frontispiece), to be deprived of its radiating calcareous -spiculae. - -The second legion of Spongiae contains the _Fibrous Sponges_ -(Fibrospongiae), the soft body of which is supported by a firm, fibrous -skeleton. This fibrous skeleton often consists merely of so-called -"horny fibres," formed of a very elastic, not readily destructible, -organic substance. This is the case for instance in our common bathing -Sponge (Euspongia officinalis), the purified skeleton of which we use -every morning when washing. Blended with the horny, fibrous skeleton of -many of these Sponges, there are numerous flinty spicula; this is the -case for example with the fresh-water Sponge (Spongilla). In others the -whole skeleton consists of only calcareous or silicious spicula which -are frequently interwoven into an extremely beautiful lattice-work, as -in the celebrated Venus' Flower Basket (Euplectella). Three orders of -fibrous sponges may be distinguished according to the different -formation of the spicula, namely, Chalynthina, Geodina, and -Hexactinella. The natural history of the fibrous sponges is of especial -interest to the Theory of Descent, as was first shown by Oscar Schmidt, -the greatest authority on this group of animals. In no other group, -perhaps, can the unlimited pliability of the specific form, and its -relation to Adaptation and Inheritance, be so clearly followed step by -step; perhaps in no other group is the species so difficult to limit and -define. - -[Illustration: Pl. VII. - -E. Haeckel del. Lagesse sc.] - -This proposition, which applies to the great legion of the Fibrous -Sponges, applies in a still higher degree to the smaller but exceedingly -interesting legion of the calcareous sponges (Calcispongiae), on which in -1872, after five years' careful examination, I published a comprehensive -Monograph. The sixty plates of figures accompanying this Monograph -explain the extreme pliability of these small sponges "good species" of -which, in fact, cannot be spoken of in the usual systematic sense. We -find among them only varying series of forms, which do not even -completely transmit their specific form to their nearest descendants, -but by adaptation to subordinate, external conditions of existence, -perpetually change. It frequently occurs here, that there arise out of -one and the same stock different form-species, which according to the -usual system would belong to several quite distinct genera; this is the -case, for instance, with the remarkable Ascometra (Frontispiece, Fig. -10.) The entire external bodily form is much more pliable and protean in -Calcareous Sponges than in the silicious sponges, which are -characterized by possessing silicious spicula, forming a beautiful -skeleton. Through the study of the comparative anatomy and ontogeny of -calcareous sponges, we can recognise, with the greatest certainty, the -common primary form of the whole group, namely, the sack-shaped -_Olynthus_, whose development is represented in the Frontispiece -(compare its explanation in the Appendix). Out of the Olynthus (Fig. 9 -on the Frontispiece), the order of the Ascones was the first to develop, -out of which, at a later period, the two other orders of Calcareous -Sponges, the _Leucones_ and _Sycones_, arose as diverging branches. -Within these orders, the descent of the individual forms can again be -followed step by step. Thus the Calcareous Sponges in every respect -confirm the proposition which I have elsewhere maintained: that "the -natural history of sponges forms a connected and striking argument in -favour of Darwin." - -The second main class or branch in the tribe of Zoophytes is formed by -the Sea-nettles (Acalephae, or Cnidae). This interesting group of animals, -so rich in forms, is composed of three different classes, namely, the -Hood-jellies (Hydromedusae), the Comb-jellies (Ctenophora), and the -Corals (Coralla). The hypothetical, extinct Archydra must be looked upon -as the common primary form of the whole group; it has left two near -relations in the still living fresh-water polyps (Hydra and -Cordylophora). The Archydra was very closely related to the simplest -forms of Spongiae (Archispongia and Olynthus), and probably differed from -them only by possessing nettle organs, and by the absence of cutaneous -pores. Out of the Archydra there first developed the different Hydroid -polyps, some of which became the primary forms of Corals, others the -primary forms of Hydromedusae. The Ctenophora developed later out of a -branch of the latter. - -The Sea-nettles differ from the Spongiae (with which they agree in the -characteristic formation of the system of the alimentary canal) -principally by the constant possession of nettle organs. These are small -bladders filled with poison, large numbers--generally millions--of which -are dispersed over the skin of the sea nettles, and which burst and -empty their contents when touched. Small animals are killed by this; in -larger animals this nettle poison causes a slight inflammation of the -skin, just as does the poison of our common nettles. Any one who has -often bathed in the sea, will probably have at times come in contact -with large Hood-jellies (Jelly-fish), and become acquainted with the -unpleasant burning feeling which their nettle organs can produce. The -poison in the splendid blue Jelly-fish, Physalia, or Portuguese -Man-of-war, acts so powerfully that it may lead to the death of a human -being. - -The class of Corals (Coralla) lives exclusively in the sea, and is more -especially represented in the warm seas by an abundance of beautiful and -highly-coloured forms like flowers. Hence they are also called -_Flower-animals_ (Anthozoa). Most of them are attached to the bottom of -the sea, and contain an internal calcareous skeleton. Many of them by -continued growth produce such immense stocks that their calcareous -skeletons have formed the foundation of whole islands, as is the case -with the celebrated coral reefs and atolls of the South Seas, the -remarkable forms of which were first explained by Darwin.(13) In corals -the counterparts, or antimera--that is, the corresponding divisions of -the body which radiate from and surround the central main axis of the -body--exist sometimes to the number of four, sometimes to the number of -six or eight. According to this we distinguish three legions, the -Fourfold (Tetracoralla), Sixfold (Hexacoralla), and Eightfold corals -(Octocoralla). The fourfold corals form the common primary group of the -class, out of which the sixfold and eightfold have developed as two -diverging branches. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes and 30 Orders of the Animal Plants, or Zoophytes._ - - ----------------+--------------------+--------------------+--------------- - _Class of the_ | _Legions of the_ | _Orders of the_ | _A Genus Name_ - _Zoophytes._ | _Zoophytes._ | _Zoophytes._ | _as example._ - ----------------+--------------------+--------------------+--------------- - I. { I. Myxospongiae { 1. Archispongina | Archispongia - { _Mucous Sponges_ { 2. Halisarcina | Halisarca - =Sponges= { | - { II. Fibrospongiae { 3. Chalynthina | Spongilla - +Spongiae+ {_Fibrous Sponges_ { 4. Geodina | Ancorina - or { { 5. Hexactinella | Euplectella - +Porifera+ { | - { III. Calcispongiae { 6. Ascones | Olynthus - {_Calcareous Sponges_ { 7. Leucones | Dyssycus - { { 8. Sycones | Sycurus - | - | - II. { IV. Tetracoralla { 9. Rugosa | Cyathophyllum - {_Fourfold Corals_ { 10. Paranemeta | Cereanthus - =Corals= { | - { V. Hexacoralla { 11. Cauliculata | Antipathes - +Coralla+ {_Sixfold Corals_ { 12. Madreporaria | Astraea - or { { 13. Halirhoda | Actinia - +Anthozoa+ { | - { VI. Octocoralla { 14. Alcyonida | Lobularia - {_Eightfold Corals_ { 15. Gorgonida | Isis - { { 16. Pennatulida | Veretillum - | - | - III. { VII. Archydrae } 17. Hydraria | Hydra - {_Primaeval Polyps_ } | - =Jelly-polyps= { | - { VIII. Leptomedusae { 18. Vesiculata | Sertularia - +Hydromedusae+ {_Soft Jelly-fish_ { 19. Ocellata | Tubularia - { { 20. Siphonophora | Physophora - or { | - { IX. Trachymedusae { 21. Marsiporchida| Trachynema - =Hood-jellies= { _Hard Jelly-fish_ { 22. Phyllorchida | Geryonia - { { 23. Elasmorchida | Charybdae - +Medusa+ { | - { X. Calycozoa } 24. Podactinaria | Lucernaria - { _Stalked Jellies_ } | - { | - { XI. Discomedusae { 25. Semaeostomeae | Aurelia - { _Disc-jellies_ { 26. Rhizostomeae | Crambessa - | - | - IV. { XII. Eurystoma } 27. Beroida | Beroe - { _Wide-mouthed_ } | - =Comb-jellies= { | - { XIII. Stenostoma { 28. Saccata | Cydippe - +Ctenophora+ { _Narrow-mouthed_ { 29. Lobata | Eucharis - { { 30. Taeniata | Cestum - - ---------------------------------------------------------------- - - Ctenophora Hydromedusae - Taeniata Lobata Rhizostomeae - | | | - | | | - \---v----/ Semaeostomeae - Saccata DISCOMEDUSAE - STENOSTOMA | - | Trachymedusae | Siphonophora - | | | | - | | Lucernaria | | - EURYSTOMA> | Calycozoa | | - | | | | | - | | | | | - \-------------------------v----------------/ - LEPTOMEDUSAE - Coralla | - Octocoralla | - Hexacoralla | | - | | | - | | | - \----v----/ | - Tetracoralla | - Spongiae | | - Fibrospongiae Calcispongiae | | - Chalynthina Leucones Sycones| | - | | | | | - | | | | | - | | | | | - Hexactinella|Geodina Dyssycus Sycurus | Hydroida - | | | | | | | Cordylophora - | | | | | | | | Hydra - \------v---/ \-----v--/ | | | | - | Ascones | | | | - | Myxospongia | | \-----v-------/ - | Halisarcina | | HYDROIDA - | | | Procorallum | - | | | | | - CHALYNTHUS | OLYNTHUS | | - | | | \-----v--------/ - \------v----------/ Hydroida - Archispongiae | - | | - | Archydra - | | - \--------------v--------/ - Protascus - | - Gastraea - -The second class of Sea-nettles is formed by the _Hood-jellies_ (Medusae) -or _Polyp-jellies_ (Hydromedusae). While most corals form stocks like -plants, and are attached to the bottom of the sea, the Hood-jellies -generally swim about freely in the form of gelatinous bells. There are, -however, numbers of them, especially the lower forms, which adhere to -the bottom of the sea, and resemble pretty little trees. The lowest and -simplest members of this class are the little fresh-water polyps (Hydra -and Cordylophora). We may look upon them as but little changed -descendants of those _Primaeval polyps_ (Archydrae), from which, during -the primordial period, the whole division of the Sea-nettles originated. -Scarcely distinguishable from the Hydra are the adherent Hydroid polyps -(Campanularia, Tubularia), which produce freely swimming medusae by -budding, and out of the eggs of these there again arise adherent polyps. -These freely swimming Hood-jellies are mostly of the form of a mushroom, -or of an umbrella, from the rim of which many long and delicate -tentacles hang. They are among the most beautiful and most interesting -inhabitants of the sea. The remarkable history of their lives, and -especially the complicated alternation of generation of polyps and -medusae, are among the strongest proofs of the truth of the theory of -descent. For just as Medusae still daily arise out of the Hydroids, did -the freely swimming medusa-form originally proceed, phylogenetically, -out of the adherent polyp-form. Equally important for the theory of -descent is the remarkable _division of labour_ of the individuals, which -among some of them is developed to an astonishingly high degree, more -especially in the splendid _Siphonophora_.(37) (Plate VII. Fig. 13.) - -The third class of Sea-nettles--the peculiar division of Comb-jellies -(Ctenophora), probably developed out of a branch of the Hood-jellies. -The Ctenophora, which are also called Ribbed-jellies, possess a body of -the form of a cucumber, which, like the body of most Hood-jellies, is as -clear and transparent as crystal or cut glass. Comb or Ribbed-jellies -are characterized by their peculiar organs of motion, namely, by eight -rows of paddling, ciliated leaflets, which run in the form of eight ribs -from one end of the longitudinal axis (from the mouth) to the opposite -end. Those with narrow mouths (Stenostoma) probably developed later out -of those with wide mouths (Eurystoma). (Compare Plate VII. Fig. 16.) - -The third tribe of the animal kingdom, the phylum of _Worms_ or -worm-like animals (Vermes, or Helminthes), contains a number of -diverging branches. Some of these numerous branches have developed into -well-marked and perfectly independent classes of Worms, but others -changed long since into the original, radical forms of the four higher -tribes of animals. Each of these four higher tribes (and likewise the -tribe of Zoophytes) we may picture to ourselves in the form of a lofty -tree, whose branches represent the different classes, orders, families, -etc. The phylum of Worms, on the other hand, we have to conceive as a -low bush or shrub, out of whose root a mass of independent branches -shoot up in different directions. From this densely branched shrub, most -of the branches of which are dead, there rise four high stems with many -branches. These are the four lofty trees just mentioned as representing -the higher phyla--the Echinoderma, Articulata, Mollusca, and Vertebrata. -These four stems are directly connected with one another at the root -only, to wit, by the common primary group of the Worm tribe. - -The extraordinary difficulties which the systematic arrangement of Worms -presents, for this reason merely, are still more increased by the fact -that we do not possess any fossil remains of them. Most of the Worms had -and still have such soft bodies that they could not leave any -characteristic traces in the neptunic strata of the earth. Hence in this -case again we are entirely confined to the records of creation furnished -by ontogeny and comparative anatomy. In making then the exceedingly -difficult attempt to throw a few hypothetical rays of light upon the -obscurity of the pedigree of Worms, I must therefore expressly remark -that this sketch, like all similar attempts possesses only a provisional -value. - -The numerous classes distinguished in the tribe of Worms, and which -almost every zoologist groups and defines according to his own personal -views, are, in the first place, divided into two essentially different -groups or branches, which in my Monograph of the Calcareous Sponges I -have termed Acoelomi and Coelomati. For all the lower Worms which are -comprised in the class of Flat-worms (Platyhelminthes), (the -Gliding-worms, Sucker-worms, Tape-worms), differ very strikingly from -other Worms, in the fact that they possess neither blood nor body-cavity -(no coelome); they are, therefore, called Acoelomi. The true cavity, or -coelome, is completely absent in them as in all the Zoophytes; in this -important respect the two groups are directly allied. But _all other -Worms_ (like the four higher tribes of animals) possess a genuine -body-cavity and a vascular system connected with it, which is filled -with blood; hence we class them together as _Coelomati_. - -The main division of _Bloodless Worms_ (Acoelomi) contains, according to -our phylogenetic views, besides the still living Flat-worms, the unknown -and extinct primary forms of the whole tribe of Worms, which we shall -call the Primaeval Worms (Archelminthes). The type of these _Primaeval -Worms_, the ancient Prothelmis, may be directly derived from the Gastraea -(p. 133). Even at present the Gastrula-form--the faithful historical -portrait of the Gastraea--recurs in the ontogenesis of the most different -kinds of worms as a transient larva-form. The ciliated Gliding-worms -(Turbellaria), the primary group of the present Planary or Flat-worms -(Platyhelminthes), are the nearest akin to the Primaeval Worms. The -parasitical Sucker-worms (Trematoda) arose out of the Gliding-worms, -which live freely in water, by adaptation to a parasitical mode of life; -and out of them later on--by an increasing parasitism--arose the -Tape-worms (Cestoda). - -Out of a branch of the Acoelomi arose the second main division of the -Worm tribe, the Worms with blood and body-cavity (Coelomati): of these -there are seven different classes. - -The Pedigree on p. 151 shows how the obscure phylogeny of the seven -classes of Coelomati may be supposed to stand. We shall, however, -mention these classes here quite briefly, as their relationships and -derivation are, at present, still very complicated and obscure. More -numerous and more accurate investigations of the ontogeny of the -different Coelomati will at some future time throw light upon their -phylogenesis. - -The Round Worms (Nemathelminthes) which we mention as the first class of -the Coelomati, and which are characterized by their cylindrical form, -consist principally of parasitical Worms which live in the interior of -other animals. Of human parasites, the celebrated Trichinae, the -Maw-worms, Whip-worms, etc., for example, belong to them. The Star-worms -(Gephyrea) which live exclusively in the sea are allied to round worms, -and the comprehensive class of Ring-worms (Annelida) are allied to the -former. To the Ring-worms, whose long body is composed of a number of -segments, all alike in structure, belong the Leeches (Hirudinea), -Earth-worms (Lumbricina), and all the marine bristle-footed Worms -(Chaetopoda). Nearly akin to them are the Snout-worms (Rhynchocoela), and -the small microscopic Wheel-worms (Rotifera). The unknown, extinct, -primary forms of the tribe of Sea-stars (Echinoderma), and of the tribe -of the articulated animals (Arthropoda), were nearest akin to the -Ring-worms. On the other hand, we must probably look for the primary -forms of the great tribe of Molluscs in extinct Worms, which were very -closely related to the Moss-polyps (Bryozoa) of the present day; and for -the primary forms of the Vertebrata in the unknown Coelomati, whose -nearest kin of the present day are the Sea-sacs, especially the Ascidia. - -SYSTEMATIC SURVEY - -_Of the 8 Classes and 22 Orders of the Worm Tribe._ - -(Compare Gen. Morph. ii. Plate V. pp. 75-77.) - - - ------------------+-------------------------+----------------------+------------------ - _Classes_ | | _Systematic_ | - _of the_ | _Orders of the_ | _Name of the_ | _Name of a Genus_ - _Worm Tribe._ | _Worm Tribe._ | _Orders of Worms_. | _as example._ - | | | - ------------------+-------------------------+----------------------+------------------ - 1. _Flat_ { 1. Primaeval worms | 1. Archelminthes | Prothelmis - _Worms_ { 2. Gliding-worms | 2. Turbellaria | Planaria - Platyhel- { 3. Sucker-worms | 3. Trematoda | Distoma - minthes { 4. Tape-worms | 4. Cestoda | Taenia - | | - 2. _Round_ { 5. Arrow-worms | 5. Chaetognatha | Sagitta - _Worms_ { 6. Thread-worms | 6. Nematoda | Trichina - Nemathel- { 7. Hook-headed | 7. Acanthocephala | Echinorhynchus - minthes { worms | | - | | - 3. _Moss_ } 8. Horse-shoe-lipped | 8. Lophopoda | Alcyonella - _Polyps_ } 9. Circle-lipped | 9. Stelmopoda | Retepora - Bryozoa } | | - | | - 4. _Sea-sacs_ { 10. Sea-squirts | 10. Ascidia | Phallusia - Tunicata { 11. Sea-barrels | 11. Thaliacea | Salpa - | | - 5. _Proboscideans_ } 12. Tongue-worms | 12. Enteropneusta | Balanoglossus - Rhynchocoela } 13. Cord-worms | 13. Nemertina | Borlasia - | | - { 14. Star-worms without | 14. Sipunculida | Sipunculus - 6. _Star-Worms_ { bristles | | - Gephyrea { 15. Star-worms with | 15. Echiurida | Echiurus - { bristles | | - | | - 7. _Wheel_ } | | - _Animalcule_ } 16. Wheel-worms | 16. Rotatoria | Hydatina - Rotifera } | | - | | - { 17. Bear-worms | 17. Arctisca | Macrobiotus - { 18. Worms with claws | 18. Onychophora | Peripatus - 8. _Ring_ { 19. Leeches | 19. Hirudinea | Hirudo - _Worms_ { 20. Land-worms | 20. Drilomorpha | Lumbricus - Annelida { 21. Mailed worms | 21. Phracthelminthes | Crossopodia - { 22. Bristle-footed | 22. Chaetopoda | Aphrodite - { worms | | - - ---------------------------------------------------------------- - - Chaetopoda - | Drilomorpha - | | - \-------v-------/ - | - Phracthelminthes | - | | - Echiurida| | Hirudinea - Sipunculida | | | | - | | | | | Onychophora - \----v---/ | | | | - +Gephyrea+ | | | | Arctisca - | | | | | | - | | | | \--v---/ - Chaetognatha | \--v-----/ | | - | | | \-----v-----/ - Nematoda | | | | - | | | \---------v---------/ - \--v--/ | +Annelida+ - | Acantho- | | - | cephala | Stelmopoda | - | | | | | Enteropneusta - \--v--/ | | | | - +Nemathelminthes+ | Lophopoda | Ascidia | - | | +Bryozoa+ | Thalicea | | Nemertina - | | | | | | | | - | | | +Rotifera+ | | | | | - | | | | | | | \---v-/ - | | | | | | | +Rhynchocoela+ - | | | | | \--v---/ | - | | | \----v---/ +Tunicata+ | - | | | | | | - \-----------------------v-----------------------------/ - +Coelomati+ (_worms with body-cavity_) - | - Cestoda | - | | - | | - Trematoda | - | | - | | - Turbellaria | - +Platyhelminthes+ | - | | - | | - \-------v---------/ - +Acoelomi+ (_worms without body-cavity_) - | - | - Archelminthes - +Prothelmis+ - | - | - +Gastraea+ - - -The class of Sea-sacs (Tunicata) is one of the most remarkable among -Worms. They all live in the ocean, where some of the Ascidiae adhere to -the bottom, while others (the sea-barrels, or Thaliacea) swim about -freely. In all of them the non-jointed body has the form of a simple -barrel-shaped sack, which is surrounded by a thick cartilaginous mantle. -This mantle consists of the same non-nitrogenous combination of carbon, -which, under the name of cellulose, plays an important part in the -Vegetable Kingdom, and forms the largest portion of vegetable cellular -membranes, and consequently also the greater part of wood. The -barrel-shaped body generally possesses no external appendages. No one -would recognise in them a trace of relationship to the highly -differentiated vertebrate animals. And yet this can no longer be -doubted, since Kowalewsky's investigations, which in the year 1867 -suddenly threw an exceedingly surprising and unmistakable light upon -them. From these investigations it has become clear that the individual -development of the adherent simple Ascidian Phallusia agrees in most -points with that of the lowest vertebrate animal, namely, the Lancelet -(Amphioxus lanceolatus). The early stages of the Ascidia possess the -beginnings of the _spinal marrow_ and the _spinal column_ (chorda -dorsalis) lying beneath it, which are the two most essential and most -characteristic organs of the vertebrate animal. Accordingly, of all -invertebrate animals known to us, the _Tunicates are without doubt the -nearest blood relations of the Vertebrates_, and must be considered as -the nearest relations of those Worms out of which the vertebrate tribe -has developed. (Compare Plates XII. and XIII.) - -While thus different branches of the Coelomatous group of the Worms -furnish us with several genealogical links leading to the four higher -tribes of animals, and give us important phylogenetic indications of -their origin, the lower group of Acoelomi, on the other hand, show close -relationships to the Zoophytes, and to the Primaeval animals. The great -phylogenetic interest of the Worm tribe rests upon this peculiar -intermediate position. - - - - -CHAPTER XIX. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -II. MOLLUSCA, STAR-FISHES, AND ARTICULATED ANIMALS. - - - Tribe of Molluscs.--Four Classes of Molluscs: Lamp-shells - (Spirobranchia); Mussels (Lamellibranchia); Snails (Cochlides); - Cuttle-fish (Cephalopoda).--Tribe of Star-fishes, or - Echinoderma.--Their Derivation from Ringed Worms (Mailed Worms, - or Phracthelminthes).--The Alternation of Generation in the - Echinoderma.--Four Classes of Star-fish: Sea-stars (Asteridea); - Sea-lilies (Crinoidea); Sea-urchins (Echinidea); Sea-cucumbers - (Holothuridea).--Tribe of Articulated Animals, or - Arthropoda.--Four Classes of Articulated Animals: Branchiata, or - Crustacea, breathing through gills; Jointed Crabs; Mailed - Crabs; Articulata Tracheata, breathing through Air - Tubes.--Spiders (Long Spiders, Round - Spiders).--Myriopods.--Insects.--Chewing and Sucking - Insects.--Pedigree and History of the Eight Orders of Insects. - - -The great natural main groups of the animal kingdom, which we have -distinguished as TRIBES, or PHYLA ("types" according to Baer and Cuvier), -are not all of equal systematic importance for our phylogeny or history -of the pedigree of the living world. They can neither be classed in a -single series of stages, one above another, nor be considered as -entirely independent stems, nor as equal branches of a single -family-tree. It seems rather (as we saw in the last chapter) that the -tribe of Protozoa, the so-called primaeval animals, is the common radical -group of the whole animal kingdom. Out of the Gastraeada--which we class -among the Protozoa--the Zoophytes and the Worms have developed, as two -diverging branches. We must now in turn look upon the varied and -much-branching tribe of Worms as the common primary group, out of which -(from perfectly distinct branches) arose the remaining tribes, the four -higher phyla of the animal kingdom. (Compare the Pedigree, p. 133.) - -Let us now take a genealogical look at these four higher tribes of -animals, and try whether we cannot make out the most important outlines -of their pedigree. Even should this attempt prove defective and -imperfect, we shall at all events have made a beginning, and paved the -road for subsequent and more satisfactory attempts. - -It does not matter in what succession we take up the examination of the -four higher tribes. For these four phyla have no close relationship -whatever among one another, but have grown out from entirely distinct -branches of the group of Worms (p. 133). We may consider the tribe of -Molluscs as the most imperfect and the lowest in point of morphological -development. We nowhere meet among them with the characteristic -articulation or segmented formation of the body, which distinguishes -even the Ring-worms, and which in the other three higher tribes--the -Echinoderma, Articulata, and Vertebrata--is most essentially connected -with the high development of their forms, their differentiation, and -perfection. The body in all Molluscs--in mussels, snails, etc.--is a -simple non-jointed sack, in the cavity of which lie the intestines. The -nervous system consists not of a cord but of several distinct (generally -three) pairs of knots loosely connected with one another. For these and -many other anatomical reasons, I consider the tribe of Molluscs (in -spite of the high physiological development of its most perfect forms) -to be morphologically the lowest among the four higher tribes of -animals. - -Whilst, for reasons already given, we exclude the Moss-polyps, and -Tunicates--which have hitherto been generally classed with the tribe of -Molluscs--we retain as genuine Molluscs the following four classes: -Lamp-shells, Mussels, Snails, and Cuttles. The two lower classes of -Molluscs, the Lamp-shells and Mussels, possess neither head nor teeth, -and they can therefore be comprised under one main class, or branch, as -headless animals (Acephala), or toothless animals (Anodontoda). This -branch is also frequently called that of the clam-shells (Conchifera, or -Bivalvia), because all its members possess a two-valved calcareous -shell. In contrast to these the two higher classes of Molluscs, the -snails and cuttles, may be represented as a second branch with the name -of Head-bearers (Cephalophora), or Tooth-bearers (Odontophora), because -both head and teeth are developed in them. - -The soft, sack-shaped body in most Molluscs is protected by a calcareous -shell or house, which in the Acephala (lamp-shells and mussels) consists -of two valves, but in the Cephalophora (snails and cuttles) is generally -a spiral tube (the so-called snail's house). Although these hard -skeletons are found in large quantities in a petrified state in all the -neptunic strata, yet they tell us but little of the historical -development of the tribe, which must have taken place for the most part -in the primordial period. Even in the Silurian strata we find fossil -remains of all the four classes of Molluscs, one beside the other, and -this, conjointly with much other evidence, distinctly proves that the -tribe of Molluscs had then obtained a strong development, when the -higher tribes, especially the Articulates and Vertebrates, had scarcely -got beyond the beginning of their historical development. In subsequent -periods, especially in the primary and secondary periods, these higher -tribes increased in importance more and more at the expense of Molluscs -and Worms, which were no match for them in the struggle for life, and -accordingly decreased in number. The still living Molluscs and Worms -must be considered as only a proportionately small remnant of the vast -molluscan fauna, which greatly predominated in the primordial and -primary periods over the other tribes. (Compare Plate VI. and -explanation in the Appendix.) - -No tribe of animals shows more distinctly than do the Molluscs, how very -different the value of fossils is in geology and in phylogeny. In -geology the different species of the fossil shells of Molluscs are of -the greatest importance because they serve as excellent marks whereby to -characterize the different groups of strata, and to fix their relative -ages. As far as relates to the genealogy of Molluscs, however, they are -of very little value, because, on the one hand, the shells are parts of -quite subordinate morphological importance, and because the actual -development of the tribe belongs to the earlier primordial period, from -which no distinct fossils have been preserved. If therefore we wish to -construct the pedigree of Molluscs, we are mainly dependent upon the -records of ontogeny and comparative anatomy from which we obtain -something like the following result. (Gen. Morph. ii. Plate VI. pp. -102-116.) - -The lowest stage of the four classes of genuine Molluscs known to us, is -occupied by the Lamp-shells or Spiral-gills (Spirobranchia), frequently -but inappropriately called Arm-footers (Brachiopoda), which have become -attached to the bottom of the sea. There now exist but few forms of -this class; for instance, some species of Lingula, Terebratula, and -others akin to them, which are but feeble remnants of the great variety -of forms which represented the Lamp-shells in earlier periods of the -earth's history. In the Silurian period they constituted the principal -portion of the whole Mollusc tribe. From the agreement which, in many -respects, their early stage of development presents with the Moss -animals, it has been concluded that they have developed out of Worms, -which were nearly related to this class. Of the two sub-classes of -Lamp-shells, the Hinge-less (Ecardines) must be looked upon as the lower -and more imperfect, the Hinged (Testicardines) as the higher and more -fully developed group. - -The anatomical difference between the Lamp-shells and the three other -classes of Molluscs is so considerable that the latter may be -distinguished from the former by the name of Otocardia. All the -Otocardia have a heart with chamber (ventricle) and ante-chamber -(auricle), whereas Lamp-shells do not possess the ante-chamber. -Moreover, the central nervous system is developed only in the former -(and not in the latter) in the shape of a complete pharyngeal ring. -Hence the four classes of Molluscs may be grouped in the following -manner:-- - - - { 1. Lamp-shells } I. Haplocardia - I. Molluscs { (Spirobranchia). } (with simple heart). - without head. { - _Acephala._ { 2. Mussels } - { (Lamellibranchia). } II. Otocardia - } (with chamber - II. Molluscs { 3. Snails } and ante-chamber - with head. { (Cochlides). } to the heart). - _Cephalophora._ { 4. Cuttles } - { (Cephalopoda). } - - -The result of these structural dispositions for the history of the -pedigree of Molluscs, which is confirmed by palaeontology, is that -Lamp-shells stand much nearer to the primaeval root of the whole tribe of -Molluscs than do the Otocardia. Probably Mussels and Snails developed as -two diverging branches out of Molluscs, which were nearly akin to the -Lamp-shells. - -Mussels, or Plate-gills (Lamellibranchia), possess a bivalved shell like -the Lamp-shells. In the latter, one of the two valves covers the back, -the other the belly of the animal; whereas in Mussels the two valves lie -symmetrically on the right and left side of the body. Most Mussels live -in the sea, only a few in fresh water. The class is divided into two -sub-classes, Asiphonia and Siphonida, of which the latter were developed -at a later period out of the former. Among the Asiphonia are Oysters, -mother-of-pearl Shells, and fresh water Mussels; among the Siphonida, -which are characterized by a respiratory tube, are the Venus-shells, -Razor-shells, and Burrowing Clams. The higher Molluscs seem to have -developed at a later period out of those without head and teeth; they -are distinguished from the latter by the distinct formation of the head, -and more especially by a peculiar kind of tooth apparatus. Their tongue -presents a curious plate, armed with a great number of teeth. In our -common Vineyard Snail (Helix pomatia) the number of teeth amount to -21,000, and in the large Garden Slug (Limax maximus) to 26,800. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes, 8 Sub-classes, and 21 Orders of Molluscs._ - - - ------------------+-----------------------+------------------------+------------------- - _Classes of_ | _Sub-classes of_ | _Orders of_ | _Systematic Name_ - _Molluscs._ | _Molluscs._ | _Molluscs._ | _of the Orders._ - ------------------+-----------------------+------------------------+------------------- - I. _Molluscs without head or teeth_: ACEPHALA _or_ ANODONTODA. - --------------------------------------------------------------------------------------- - I. { I. Ecardines { 1. Stalked 1. Lingulida - =Lamp-shells= { _Hinge-less_ { 2. Flattened 2. Craniada - { - +Spirobranchia+ { - or { - +Brachiopoda+ { II. Testicardines { 3. Fleshy armed 3. Sarcobrachia - { _Hinge-less_ { 4. Calcareous-armed 4. Sclerobrachia - - - II. { III. Asiphonia { 5. One-muscled 5. Monomya - =Mussels= { _Mussels without_ { 6. Uneven-muscled 6. Heteromya - or { _respiratory tubes_ { 7. Even-muscled 7. Isomya - =Plate-gills= { - { - +Lamellibranchia+ { IV. Siphonida { 8. Round-mantled 8. Integripallia - or { _Mussels with_ { 9. Ray-mantled 9. Sinupalliata - +Phyllobranchia+ { _respiratory tubes_ { 10. Tube-mussels 10. Inclusa - - --------------------------------------------------------------------------------------- - II. _Molluscs with head and teeth_: CEPHALOPHORA _or_ ODONTOPHORA. - --------------------------------------------------------------------------------------- - - { V. Stump-headed { 11. Tube-snails 11. Scaphopoda - III. { _Perocephala_ { 12. Butterfly-snails 12. Pteropoda - =Snails= { - { { 13. With hind gills 13. Opisthobranchia - +Cochlides+ { { 14. With fore gills 14. Prosobranchia - or { VI. Large-headed { 15. Swimming-snails 15. Heteropoda - +Gasteropoda+ { _Delocephala_ { 16. Beetle-snails 16. Chitonoida - { { 17. Snails with lungs 17. Pulmonata - - - VII. Chamber-Poulps { 18. Pearl boats 18. Nautilida - IV. with four gills { 19. Ammon's horns 19. Ammonitida - =Cuttles= } _Tetrabranchia_ { - or } - =Poulps= } VIII. Ink-Poulps with { 20. Ten-armed 20. Decabrachiones - } two gills { - +Cephalopoda+ } _Dibranchia_ { 21. Eight-armed 21. Octobrachiones - - ---------------------------------------------------------------- - - Dibranchia - Heteropoda | - | _Prosobranchia_ | - _Pulmonata_ | | Tetrabranchia - | Lipobranchia | | Cephalopoda - | | | | (=Cuttles= or =Poulps=) - | Gymnobranchia | | | - | | \-------v------/ | - | | | | - | Pleurobranchia | Chitonides | - | _Opisthobranchia_ | | | - | | | | | - \---------------------------------v---------/ | - | | - _Delocephala_ | - | | - | | - \--------v----------/ - | - | _Pteropoda_ - Inclusa | | - | | | - | \------v-----/ - Sinupalliata | - | Scaphopoda | - | | | - Integripalliata \---v--/ - Sclerobrachia _Siphoniata_ | - | | _Perocephala_ - | | Cochlides - | | (=Snails=) - Sarcobrachia _Asiphonia_ | - _Testicardines_ Lamellibranchia | - | (=Mussels=) | - | | | - _Ecardines_ \----------v-------------/ - Spirobranchia | - (=Lamp-shells=) Otocardia - | (Molluscs with chamber and ante-chamber - | to the heart) - | | - | | - \-----------------v--------------/ - | - Promollusca (Primaeval Molluscs) - Molluscs with simple heart - | - (Worms) - | - Gastraea - - -We distinguish two sub-classes among the Snails (Cochlides, or -Gasteropoda), namely, the Stump-headed and the Large-headed Snails. The -Stump-headed Snails (Perocephala) are very closely allied to Mussels -(through the Tooth-shells), and also to the Cuttle-fish (through the -Butterfly-snails). The more highly developed Snails, with large heads -(Delocephala), can be divided into Snails with gills (Branchiata) and -Snails with lungs (Pulmonata). Among the latter are the Land-snails, the -only Molluscs which have left the water and become habituated to a life -on land. The great majority of Snails live in the sea, only a few live -in fresh water. Some River-snails in the tropics (the Ampullaria) are -amphibious, living sometimes on land, sometimes in water, and at one -time they breathe through gills, at another through lungs. They have -both kinds of respiratory organs, like the Mud-fish and Gilled Newts -among the Vertebrata. - -The fourth and last class, and at the same time the most highly -developed class of Molluscs, is that of the Cuttles, or Poulps, also -called Cephalopoda (foot attached to the head). They all live in the -sea, and are distinguished from Snails by eight, ten, or more long arms, -which surround the mouth in a circle. The Cuttles existing in our recent -oceans--the Sepia, Calamary, Argonaut, and Pearly Nautilus--are, like -the few Spiral-gill Lamp-shells of the present time, but a poor remnant -of the host which represents this class in the oceans of the primordial, -primary, and secondary periods. The numerous fossil "Ammon's horns" -(Ammonites), "pearl boats" (Nautilus), and "thunderbolts" (Belemnites) -are evidences of the long since extinct splendour of the tribe. The -Poulps, or Cuttles, have probably developed out of a low branch of the -snail class, out of the Butterfly-snails (Pteropoda) or kindred forms. - -The different sub-classes and orders, distinguished in the four classes -of Molluscs, whose systematic succession is given on the Table (p. -160), furnish various proofs of the validity of the law of progress by -their historical development and by the systematic development -corresponding to it. As however these subordinate groups of Molluscs are -in themselves of no further special interest, I must refer to the sketch -of their pedigree on p. 161, and to the detailed pedigree of Molluscs -which I have given in my General Morphology, and I shall now at once -turn to the consideration of the tribe of Star-fishes. - -The Star-fishes (Echinoderma, or Estrellae) among which are the four -classes of Sea-stars, Sea-lilies, Sea-urchins, and Sea-cucumbers are one -of the most interesting divisions of the animal kingdom, and yet we know -less about them than about any. They all live in the sea. Every one who -has been at the sea shore must have seen at least two of their forms, -the Sea-stars and the Sea-urchins. The tribe of Star-fishes must be -considered as a completely independent tribe of the animal kingdom on -account of its very peculiar organization, and must be carefully -distinguished from the Animal-plants--Zoophytes, or Coelenterata, with -which it is still frequently but erroneously classed under the name -Radiata (as for example, by Agassiz, who even to this day defends this -error of Cuvier's, together with many others). - -All Echinoderma are characterized, and at the same time distinguished -from all other animals, by a very remarkable apparatus for locomotion, -which consists of a complicated system of canals or tubes, filled with -sea water from without. The sea water in these aqueducts is moved partly -by the strokes of the cilia, or vibratile hairs lining their walls, and -partly by the contractions of the muscular walls of the tubes -themselves, which resemble india-rubber bags. The water is pressed from -the tubes into a number of little hollow feet, which thereby become -widely distended, and are then employed for walking and suction. The -Sea-stars are moreover characterized by a peculiar calcareous formation -in the skin, which in most cases forms a firm, well-closed coat of mail, -composed of a number of plates. In almost all Echinoderma the body -consists of five radii (counterparts, or antimera) standing round the -main axis of the body, where they meet. It is only in some species of -Sea-stars that the number of these radii amount to more than five--to -6-9, 10-12, or even to 20-40; and in this case the number of radii is -generally not constant, but varies in different individuals of one -species. - -The historical development and the pedigree of the Echinoderma are -completely revealed to us by their numerous and, in most cases, -excellently preserved fossil remains, by their very remarkable -individual developmental history, and by their interesting comparative -anatomy; this is the case with no other tribe of animals, even the -Vertebrata themselves are not to be excepted. By a critical use of those -three archives, and by a careful comparison of the results derived from -their study, we obtain the following genealogy of the Star-fishes, which -I have already published in my General Morphology (vol. ii. Plate IV. -pp. 62-77.) - -The most ancient and original group of the Star-fishes, the primary form -of the whole phylum, consists of the class of the true Sea-stars -(Asterida). This is established by numerous and important arguments in -anatomy and the history of development, but above all by the irregular -and varying number of the radii, or antimera, which in all other -Echinoderma is limited, without exception, to five. Every Star-fish -consists of a central, small, body-disc, all round the circumference of -which are attached five or several long articulated arms. _Each arm of -the Star-fish essentially corresponds in its organisation with an -articulated worm_ of the class of Ring-worms, or Annelida (p. 149). I -therefore consider the Star-fish as a genuine _stock or cormus of five -or more articulated worms_, which have arisen by the star-wise growth of -a number of buds out of a central mother-worm. The connected members, -thus grouped like the rays of a star, have inherited from the -mother-worm the common opening of the mouth, and the common digestive -cavity (stomach) lying in the central body-disc. The end by which they -have grown together, and which fuses in the common central disc, -probably corresponds to the posterior end of the original independent -worms. - -In exactly the same way several individuals of certain kinds of worms -are united so as to form a star-like cormus. This is the case in the -_Botryllidae_, compound Ascidians, belonging to the class of the -Tunicata. Here also the posterior ends of the individual worms have -grown together, and have formed a common outlet for discharges, a -central cloaca; whereas at the anterior end each worm still possesses -its own mouth. In Star-fishes the original mouths have probably become -closed in the course of the historical development of the cormus, or -colony, whereas the cloaca has developed into a common mouth for the -whole cormus. - - -SYSTEMATIC SURVEY - -_Of the 4 Classes, 9 Sub-classes, and 20 Orders of Star-fishes._ - -(Compare Gen. Morph. II. Plate IV. pp. 62-67.) - - - ----------------+-------------------------+---------------------------+------------------ - _Classes of the | _Sub-classes of the | _Orders of the | _Systematic Name - Star-fishes._ | Star-fishes._ | Star-fishes._ | of the Orders._ - ----------------+-------------------------+---------------------------+------------------ - | - { I. { 1. Primary Stars | 1. Tecastra - { Sea Stars with radiated { 2. Articulated Stars | 2. Colastra - I. { stomach { 3. Brisinga Stars | 3. Brisingastra - =Sea Stars= { _Actinogastra_ | - +Asterida+ { - { II. { 4. Serpent Stars | 4. Ophiastra - { Sea Stars with disc- { 5. Tree Stars | 5. Phytastra - { shaped stomach { 6. Lily Stars | 6. Crinastra - { _Discogastra_ { | - | - { III. { 7. Plated Lilies with | 7. Phatnocrinida - { Lilies with arms { arms | - { _Brachiata_ { 8. Articulated Lilies | 8. Colocrinida - { { with arms | - | - II. { IV. { 9. Regularly budding | 9. Pentremitida - =Sea Lilies= { Lilies with buds { Lilies | - +Crinoida+ { _Blastoidea_ { 10. Lilies budding on | 10. Eleutherocrina - { { two sides | - | - { V. { 11. Bladder Lilies | 11. Agelacrinida - { Bladder Lilies { without stalks | - { _Cystidea_ { 12. Bladder Lilies | 12. Sphaeronitida - { with stalks | - | - { VI. { 13. Palechinida with | 13. Melonitida - { Older Sea Urchins { more than 10 | - { (with more than { rows of ambulacral | - { 20 rows of plates) { plates | - III. { _Palechinida_ { 14. Palechinida with | 14. Eocidaria - =Sea Urchins= { { 10 rows of | - +Echinida+ { VII. { ambulacral plates | - { More recent Sea { 15. Autechinida with | 15. Desmosticha - { Urchins (with 20 { band-like ambulacra | - { rows of plates) { 16. Autechnidia with | 16. Petalosticha - { _Autechinida_ { leaf-like ambulacra | - | - { VIII. { 17. Eupodia with scuti- | 17. Aspidochirota - { Sea Cucumbers { form tentacles | - { with aquatic feet { 18. Eupodia with | 18. Dendrochirota - IV. { _Eupodia_ { branching tentacles | - =Sea Cucumbers= { { | - { IX. { | - +Holothuriae+ { Sea Cucumbers { 19. Apodia with water- | 19. Liodermatida - { without aquatic { lungs | - { feet { 20. Apodia without | 20. Synaptida - { _Apodia_ { water-lungs | - - ---------------------------------------------------------------- - - Clypeastridae - | - Spatangidae | - | | - Dysasteridae | | - | | | - Aspidochirota | | | - | | \------v------/ - Synaptida | | | - | | | Cassidulidae - | | | +Petalosticha+ - | | | | - | | | | - Liodermatida | | | - +Apodia+ | \------v-------/ Echinonidae - | | | | - | | Galeritidae | - | | | Echinometridae | - \---------v-----------/ | | | - | \------v---------/ - Dendrochirota | - +Eupodia+ Latistellae - +Holothuriae+ Salenidae | - \------v------/ | | - | | | - | \------v------------/ - | | - | Angustistellae - | +Desmosticha+ - | +Autechinida+ - | | - | | Colocrinae - | | | - | | Sphaeronitidae | - Phytastra | | | | - | | | | | - | | Eocidaridae | | Eleutherocrina - | | | | | | - | | | | | | - Ophiastra | | Agelacrinae | | - +Discogastra+ | | +Cystidea+ | | - | | | | | | - | | | | | | - | | Melonitida | Phatnocrinae | - Brisingastra | Palechinida | +Brahiata+ Pentremitida - | | +Echinida+ | | +Blastoidea+ - | | | | | | - | | | | | | - Colastra \----------v-----------------/ \-------v-----------/ - | | +Brachiata+ - | | Crinoida - | | Crinastra - | | | - \-------------------------v----------------------------------/ - | - Tocastra - +Actinogastra+ - +Asterida+ - | - Phracthelminthes - | - Coelomati - | - Gastraea - - -Hence the Star-fishes would be compound stocks of worms which, by the -radial formation of buds, have developed out of true articulated worms, -or Annelids. This hypothesis is most strongly supported by the -comparative anatomy, and by the ontogeny of some Star-fishes (Colastra), -and of segmented worms. The many-jointed Ring-worms (Annelida) in their -inner structure are closely allied to the individual arms or radii of -the Star-fishes, that is to the original single worms, which each arm -represents. Each of the five worms of the Star-fish is a chain composed -of a great number of equi-formal members, or metamera, lying one behind -the other, like every segmented Worm, and every Arthropod. As in the -latter a central nervous cord, the ventral nerve cord runs along the -central line of the ventral wall of each segment. On each metameron -there is a pair of non-jointed feet, and besides these, in most cases, -one or more hard thorns or bristles similar to those of many Ring-worms. -A detached arm of a Star-fish can lead an independent life, and can -then, by the radially-directed growth of buds at one end, again become a -complete star. - -The most important proofs, however, of the truth of my hypothesis are -furnished by the ontogeny or the individual development of the -Echinoderma. The most remarkable facts of this ontogeny were first -discovered in the year 1848 by the great zoologist, Johannes Mueller of -Berlin. Some of its most important stages are represented on Plates -VIII. and IX. (Compare their explanation in the Appendix.) Fig. _A_ on -Plate IX. shows us a common Sea-star (Uraster), Fig. _B_, a Sea-lily -(Comatula), Fig. _C_, a Sea-urchin (Echinus), and Fig. _D_, a -Sea-cucumber (Synapta). In spite of the extraordinary difference of form -manifested by these four representatives of the different classes of -Star-fishes, yet the beginning of their development is identical in all -cases. Out of the egg an animal-form develops which is utterly -different from the fully developed Star-fish, but very like the ciliated -larvae of certain segmented Worms (Star-worms and Ring-worms). This -peculiar animal-form is generally called the "larva," but more correctly -the "nurse" of these Star-fish. It is very small and transparent, swims -about by means of a fringe of cilia, and is always composed of two equal -symmetrical halves or sides. The fully grown Echinoderm, however--which -is frequently more than a hundred times larger, and quite opaque--creeps -at the bottom of the sea, and is always composed of at least five -co-ordinate pieces, or antimera, in the form of radii. Plate VIII. shows -the development of the "nurses" of the four Echinoderms represented on -Plate IX. - -The fully developed Echinoderm arises by a very remarkable process of -budding in the interior of the "nurse," of which it retains little more -than the stomach. The nurse, erroneously called the "larva," of the -Echinoderm, must accordingly be regarded as a solitary worm, which by -internal budding produces a second generation, in the form of a stock of -star-shaped and connected worms. The whole of this process is a genuine -alternation of generations, or metagenesis, not a "metamorphosis," as is -generally though erroneously stated. A similar alternation of -generations also occurs in many other worms, especially in some star -worms (Sipunculidae), and cord worms (Nemertinae). Now if, bearing in mind -the fundamental law of biogeny, we refer the ontogeny of Echinoderma to -their phylogeny, then the whole historical development of the -Star-fishes suddenly becomes clear and intelligible to us, whereas -without this hypothesis it remains an insoluble mystery. (Compare Gen. -Morph. ii. pp. 95-99.) - -Besides the reasons mentioned, there are many other facts (principally -from the comparative anatomy of Echinoderma) which most distinctly prove -the correctness of my hypothesis. I established this hypothesis in 1866, -without having any idea that _fossil articulated worms_ still existed, -apparently answering to the hypothetical primary forms. Such have in the -mean time, however, really been discovered. In a treatise "On the -Equivalent of the North American Taconic Schist in Germany,"[3] Geinitz -and Liebe, in 1867, have described a number of articulated Silurian -worms, which completely confirm my suppositions. Numbers of these very -remarkable worms are found in an excellent state of preservation in the -slates of Wuerzbach, in the upper districts of Reusz. They are of the -same structure as the articulated arm of a Star-fish, and evidently -possessed a hard coat of mail, a much denser, more solid cutaneous -skeleton than other worms in general. The number of body-segments, or -metamera, is very considerable, so that the worms, although no more than -a quarter or half an inch in breadth, attained a length of from two to -three feet. The excellently preserved impressions, especially those of -the Phyllodocites thuringiacus and Crossopodia Henrici, are so like the -arms of many Star-fish (Colastra) that their true blood relationship -seems very probable. This primaeval group of worms, which are most -probably the ancestors of Star-fish, I call Mailed worms -(Phracthelminthes, p. 150.) - -[Illustration: Pl. viii. - -STAR FISHES. FIRST GENERATION. WORM PERSON.] - -[Illustration: Pl. ix. - -STAR FISHES. SECOND GENERATION. WORM STOCK.] - -The three other classes of Echinoderma evidently arose at a later period -out of the class of Sea-stars which have most faithfully retained the -original form of the stellate colony of worms. The Sea-lilies, or -Crinoida, differ least from them, but having given up the free, slow -motion possessed by other Sea-stars, they have become adherent to rocks, -etc., and form for themselves a long stalk. Some Encrinites, however -(for example, the Comatulae, Fig. _B_, on Plates VIII. and IX.), -afterwards detach themselves from their stalk. The original worm -individuals in the Crinoida are indeed no longer preserved in the same -independent condition as in the case of the common star-fish; but they -nevertheless always possess articulated arms extending from a common -central disc. Hence we may unite the Sea-lilies and Sea-stars into a -main-class, or branch, characterized as possessing articulated arms -(Colobrachia). - -In the other two classes of Echinoderma, the Sea-urchins and -Sea-cucumbers, the articulated arms are no longer present as independent -parts, but, by the increased centralization of the stock, have -completely fused so as to form a common, inflated, central disc, which -now looks like a simple box or capsule without arms. The original stock -of five individuals has apparently degenerated to the form-value of a -simple individual, a single person. Hence we may represent these two -classes as a branch characterized as being without arms (Lipobrachia), -equivalent to those which possess articulated arms. The first of these -two classes, that of Sea-urchins (Echinida) takes its name from the -numerous and frequently very large thorns which cover the hard shell, -which is itself artistically built up of calcareous plates. (Fig. _C_, -Plates VIII. and IX.) The fundamental form of the shell itself is a -pentagonal pyramid. The Sea-urchins probably developed directly out of -the group of Sea-stars. The different classes and orders of marine -lilies and stars which are given in the following table, illustrate the -laws of progress and differentiation in a striking manner. In each -succeeding period of the earth's history we see the individual classes -continually increasing in variety and perfection. (Gen. Morph. ii. Plate -IV.) - -The history of three of these classes of Star-fish is very minutely -recorded by numerous and excellently preserved fossils, but on the other -hand, we know almost nothing of the historical development of the fourth -class, that of the Sea-cucumbers (Holothuriae). These curious -sausage-shaped Star-fish manifest externally a deceptive similarity to -worms. (Fig. _D_, Plates VIII. and IX.) The skeletal structures in their -skin are very imperfect, and hence no distinct remains of their -elongated, cylindrical, worm-like body could be preserved in a fossil -state. However, from the comparative anatomy of the Holothuriae, we can -infer that they have arisen, by the softening of the cutaneous skeleton, -from members of the class of Sea-urchins. - -From the Star-fish we turn to the fifth and most highly developed tribe -of the invertebrate animals, namely, the phylum of Articulata, or those -with _jointed feet_ (Arthropoda). As has already been remarked, this -tribe corresponds to Linnaeus' class of Insects. It contains four -classes: (1) the genuine six-legged Insects, or Flies; (2) the -eight-legged Spiders; (3) the Centipedes, with numerous pairs of legs; -and (4) the Crabs, or Crustacea, whose legs vary in number. The last -class breathe water through gills, and may therefore be contrasted as -the main-class of gill-breathing Arthropoda, or Gilled Insects -(Carides), with the three first classes. The latter breathe air by means -of peculiar wind-pipes, or tracheae, and may therefore appropriately be -united to form the main-class of the trachea-breathing Arthropoda, or -Tracheate Insects (Tracheata). - -In all animals with articulated feet, as the name indicates, the legs -are distinctly articulated, and by this, as well as by the strong -differentiation of the separate parts of the body, or metamera, they are -sharply distinguished from Ringed worms, with which Baer and Cuvier -classed them. They are, however, in every respect so like the Ringed -worms that they can scarcely be considered altogether distinct from -them. They, like the Ringed worms, possess a very characteristic form of -the central nervous system, the so-called ventral marrow, which -commences in a gullet-ring encircling the mouth. From other facts also, -it is evident that the Arthropoda developed at a late period out of -articulated worms. Probably either the Wheel Animalcules or the Ringed -worms are their nearest blood relations in the Worm tribe. (Gen. Morph. -ii. Plate V. pp. 85-102.) - -Now, although the derivation of the Arthropoda from ringed Worms may be -considered as certain, still it cannot with equal assurance be -maintained that the whole tribe of the former has arisen out of one -branch of the latter. For several reasons seem to support the -supposition that the Gilled Arthropods have developed out of a branch of -articulated worms, different from that which gave rise to the Tracheate -Arthropods. But on the whole it remains more probable that both -main-classes have arisen out of one and the same group of Worms. In this -case the Tracheate Insects--Spiders, Flies, and Centipedes--must have -branched off at a later period from the gill-breathing Insects, or -Crustacea. - -The pedigree of the Arthropoda can on the whole be clearly made out from -the palaeontology, comparative anatomy, and ontogeny of its four -classes, although here, as everywhere else, many details remain very -obscure. Not until the history of the individual development of all the -different groups has become more accurately known than it is at present, -can this obscurity be removed. The history of the class of Gilled -Insects, or Crabs (Carides), is at present that best known to us; they -are also called encrusted animals (Crustacea), on account of the hard -crust or covering of their body. The ontogeny of these animals is -extremely interesting and, like that of Vertebrate animals, distinctly -reveals the essential outlines of the history of their tribe, that is, -their phylogeny. Fritz Mueller, in his work, "Fuer Darwin,"(16) which has -already been referred to, has explained this remarkable series of facts -in a very able manner. - -[Illustration: _Nauplius. Youth-form of six Crab-fish._ _Pl. X._ - - A. Limnetis. - B. Cyclops. - C. Lernacocera. - D. Lepas. - E. Sacculina. - F. Peneus.] - -[Illustration: _Adult form of the same six Crab-fish._ _Pl. XI._ - - A. Limnetis. - B. Cyclops. - C. Lernacocera. - D. Lepas. - E. Sacculina. - F. Peneus.] - -The common primary form of all Crabs, which in most cases is even now -the first to develop out of the egg, is originally one and the same, the -so-called _Nauplius_. This remarkable primaeval crab represents a very -simple form of articulated animal, the body of which in general has the -form of a roundish, oval, or pear-shaped disc, and has on its ventral -side only three pairs of legs. The first of these is uncloven, the two -subsequent pairs are forked. In front, above the mouth, lies a simple, -single eye. Although the different orders of the Crustacean class differ -very widely from one another in the structure of their body and its -appendages, yet the early Nauplius form always remains essentially the -same. In order to be convinced of this, let the reader look attentively -at Plates X. and XI., a more detailed explanation of which is given in -the Appendix. On Plate XI. we see the fully developed representatives of -six different orders of Crabs, a Leaf-footed Crab (Limnetis, Fig. _A -c_); a Stalked Crab (Lepas, Fig. _D c_); a Root Crab (Sacculina, Fig. -_E c_); a Boatman Crab (Cyclops, Fig. _B c_); a Fish Louse (Lernaeocera, -Fig. _C c_); and, lastly, a highly developed Shrimp (Peneus, Fig. _F -c_). These six crabs vary very much, as we see, in the entire form of -body, in the number and formation of the legs, etc. When, however, we -look at the earliest stages, or "nauplius," of these six different -classes, after they have crept out of the egg--those marked with -corresponding letters on Plate X. (Fig. _A n-F n_)--we shall be -surprised to find how much they agree. The different forms of Nauplius -of these six orders differ no more from one another than would six -different "good species" of one genus. Consequently, we may with -assurance infer a common derivation of all those orders from a common -Primaeval Crab, which was essentially like the Nauplius of the present -day. - - -SYSTEMATIC SURVEY - -_Of the 7 Legions and 20 Orders of Crabs, or Crustacea._ - - - -------------------------+--------------------------+----------------------+-------------- - _Legions of the_ | _Orders of the_ | _Systema Name_ | _Name of a_ - _Crustaceae._ | _Crustaceae._ | _of the Orders._ | _Genus as an_ - | | | _example._ - -------------------------+--------------------------+----------------------+-------------- - I. ENTOMOSTRACA, _Lower Crustacea_, or Segmented Crabs (not passing through the - actual Zoea form in youth). - ------------------------------------------------------------------------------------------ - - +I. Branchiopoda+ { 1. Primaeval Crabs 1. Archicarida Nauplius - Gill-footed Crabs { 2. Leaf-foot Crabs 2. Phyllopoda Limnetis - { 3. Trilobites 3. Trilobita Paradoxides - { 4. Water Fleas 4. Cladocera Daphnia - { 5. Bivalve Crabs 5. Ostracoda Cypris - - - +II. Pectostraca+ { 6. Barnacle Crabs 6. Cirripedia Lepas - Fixed Crabs { 7. Root Crabs 7. Rhizocephala Sacculina - - +III. Copepoda+ { 8. Boatmen Crabs 8. Eucopepoda Cyclops - Oar-footed Crabs { 9. Fish Lice 9. Siphonostoma Lernaeocera - - +IV. Pantopoda+ {10. No-body Crabs 10. Pycnogonida Nymphon - No-body Crabs { - - +V. Poecilopoda+ {11. Spear-tails 11. Xiphosura Limulus - Shield Crabs {12. Giant Crabs 12. Gigantostraca Eurypterus - - ------------------------------------------------------------------------------------------ - II. MALACOSTRACA, _Higher Crustacea_, or Mailed Crabs (passing through the Zoea form - in youth). - ------------------------------------------------------------------------------------------ - - +VI. Podophthalma+ {13. Zoea Crabs 13. Zoepoda Zoea - Stalk-eyed Mailed {14. Split-legged Crabs 14. Schizopoda Mysis - Crabs {15. Mouth-footed Crabs 15. Stomatopoda Squilla - {16. Ten-footed Crabs 16. Decapoda Peneus - - +VII. Edriophthalma+ {17. Cuma Crabs 17. Cumacea Cuma - Mailed Crabs with {18. Flea Crabs 18. Amphipoda Gammarus - sessile eyes {19. Wizard Crabs 19. Laemodipoda Caprella - {20. Louse Crabs 20. Isopoda Oniscus - - ---------------------------------------------------------------- - - - Brachyura Isopoda - | | - | Laemodipoda | - | | | - Anomura | | - | | | - | Amphipoda | - | | | - | \-----v----/ - Macrura | - Decapoda Stomatopoda Cumacea - | | +Edriophthalma+ - | | | - \----v----/ | - | | - | | - \---------------------------v------------/ - | - Schizopoda - +Podophthalma+ - | - Zoepoda - +Malacostraca+ - Gigantostraca | Rhizocephala - | | Siphonostoma | - | Xiphosurae Zoea | Cirripediae - | | | | +Pectostraca+ - | | | | | - \------v------/ | | | - | | | | - +Poecilopoda+ | | | - | Nebaliae | | | - | | | Eucopepoda | - Belinuroe | | +Copepoda+ | Pycnogonida - | | | | | +Pantopoda+ - Trilobita | | | | | - | Phyllopoda | | Ostracoda | | - Cladocerae | | | | | | | - | | | | | | | | - \-----------------v-------/ | | \---v---/ | - | | | | | - +Branchiopoda+ | | | | - | | | | | - | | | | | - \----------------------v-------------------------/ - | - Nauplius - | - +Archicaridae+ - - (Articulated Worms) - - -The pedigree on p. 177 will show how we may at present approximately -conceive the derivation of the twenty orders of Crustacea enumerated on -p. 176, from the common primary form of the Nauplius. Out of the -Nauplius form--which originally existed as an independent genus--the -five legions of lower Crabs developed as diverging branches in different -directions, which in the systematic survey of the class are united as -Segmented Crabs (Entomostraca). The higher division of Mailed Crabs -(Malacostraca) have likewise originated out of the common Nauplius form. -The Nebalia is still a direct form of transition from the Phyllopods to -the Schizopods, that is, to the primary form of the stalk-eyed and -sessile-eyed Mailed Crabs. The Nauplius at this stage gives rise to -another larva form, the so-called Zoea, which is of great importance. -The order of Schizopoda, those with cloven feet (Mysis, etc.), probably -originated from this curious Zoea; they are at present still directly -allied, through the Nebalia to the Phyllopoda, those with foliaceous -feet. But of all living crabs the Phyllopods are the most closely allied -to the original primary form of the Nauplius. Out of the Schizopoda the -stalk-eyed and sessile-eyed Mailed Crabs, or Malacostraca, developed as -two diverging branches in different directions: the former through -shrimps (Peneus, etc.), the latter through the Cumacea (Cuma, etc.), -which are still living and closely allied to the Schizopoda. Among those -with stalked eyes is the river crab (cray-fish), the lobster, and the -others with long tails, or the Macrura, out of which, in the chalk -period, the short-tailed crabs, or Brachyura, developed by the -degeneration of the tail. Those with sessile eyes divide into the two -branches of Flea-crabs (Amphipoda) and Louse-crabs (Isopoda); among the -latter are our common Rock-slaters and Wood-lice. - -The second main-class of Articulated animals, that of the Tracheata, or -air-breathing Tracheate Insects[4] (Spiders, Centipedes, and Flies) did -not develop until the beginning of the palaeolithic era, after the close -of the archilithic period, because all these animals (in contrast with -the aquatic crabs) are originally inhabitants of land. It is evident -that the Tracheata can have developed only after the lapse of the -Silurian period when terrestrial life first began. But as fossil remains -of spiders and insects have been found, even in the carboniferous beds, -we can pretty accurately determine the time of their origin. The -development of the first Tracheate Insects out of gill-bearing -Zoea-crabs, must have taken place between the end of the Silurian and -the beginning of the coal period, that is, in the Devonian period. - -Gegenbaur, in his excellent "Outlines of Comparative Anatomy,"(21) has -lately endeavoured to explain the origin of the Tracheata by an -ingenious hypothesis. The system of tracheae, or air pipes, and the -modifications of organization dependent upon it, distinguish Flies, -Centipedes, and Spiders so much from other animals, that the conception -of its first origin presents no inconsiderable difficulties to -phylogeny. According to Gegenbaur, of all living Tracheate Insects, the -Primaeval Flies, or Archiptera, are most closely allied to the common -primary form of the Tracheata. These insects--among which we may -especially mention the delicate Day flies (Ephemera), and the agile -dragon-flies (Libellula)--in their earliest youth, as larvae, frequently -possess _external tracheate gills_ which lie in two rows on the back of -the body, and are shaped like a leaf or paint-brush. Similar leaf or -paint-brush shaped organs are met with as real water-breathing organs or -gills, in many crabs and ringed worms, and, moreover, in the latter as -real dorsal appendages or limbs. The "tracheate gills," found in the -larvae of many primaeval winged insects, must in all probability be -explained as "_dorsal limbs_," and as having developed out of the -corresponding appendages of the Annelida, or possibly as having really -arisen out of similar parts in Crustacea long since extinct. The present -tracheal respiration of the Tracheata developed at a later period out of -respiration through the "tracheate gills." The tracheate gills -themselves, however, have in some cases disappeared, and in others -become transformed into the _wings_ of the Flies. They have disappeared -entirely in the classes of Spiders and Centipedes, and these groups must -accordingly be conceived of as degenerated or peculiarly developed -lateral branches of the Fly class, which at an early period branched off -from the common primary form of Flies; Spiders probably did so at an -earlier period than Centipedes. Whether that common primary form of all -Tracheata, which in my General Morphology I have named Protracheata, did -develop directly out of genuine Ringed worms, or at first out of -Crustacea of the Zoea form (Zoepoda, p. 177) will probably be settled at -some future time by a more accurate knowledge and comparison of the -ontogeny of the Tracheata, Crustacea, and Annelida. However, the root of -the Tracheata, as well as that of the Crustacea, must in any case be -looked for in the group of Ringed worms. - -The genuine Spiders (Arachnida) are distinguished from Flies by the -absence of wings, and by four pairs of legs; but, as is distinctly seen -in the Scorpion-spiders and Tarantulae, they, like Flies, possess in -reality only three pairs of genuine legs. The apparent "fourth pair of -legs" in spiders (the foremost) are in reality a pair of feelers. Among -the still existing Spiders, there is a small group which is probably -very closely allied to the common primary form of the whole class; this -is the order of Scorpion-spiders, or Solifugae, (Solpuga, Galeodes), of -which several large species live in Africa and Asia, and are dreaded on -account of their poisonous bite. Their body consists--as we suppose to -have been the case in the common ancestor of the Tracheata--of a head -possessing several pairs of feelers like legs, of a thorax, to the three -rings of which are attached three pairs of legs, and of a hinder body, -or abdomen, consisting of many distinct rings. In the articulation of -their body, the Solifugae are therefore in reality more closely related -to flies than to other spiders. Out of the Devonian Primaeval Spiders, -which were nearly related to the Solifugae of the present day, the Long -Spiders, the Tailor Spiders, and the Round Spiders probably developed as -three diverging branches. - -The _Long Spiders_ (Arthrogastres), in which the earlier articulation of -body has been better preserved than in Round Spiders, appear to be the -older and more original forms. The most important members of this -sub-class are the scorpions, which are connected with the Solifugae -through the Tarantella (or Phrynidae). The small book scorpions, which -inhabit our libraries and herbariums, appear as a degenerate lateral -branch from the true scorpions. Midway between the Scorpions and Round -Spiders are the long-legged Tailor-spiders (Opiliones) which have -possibly arisen out of a special branch of the Solifugae. The -Pycnogonida, or No-body Crabs, and the Arctisca, or Bear Worms--still -generally included among Long Spiders--must be completely excluded from -the class of Spiders; the former belong to the Crustacea, the latter to -Ringed worms. - - -SYSTEMATIC SURVEY - -_Of the 3 Classes and 17 Orders of the Tracheata._ - - - ------------------+---------------------+----------------------+---------------------- - _Classes of the_ | _Sub-Classes of the_| _Order of the_ | _Two Names of_ - _Tracheata._ | _Tracheata._ | _Tracheata._ |_Genera as examples._ - ------------------+---------------------+----------------------+---------------------- - { { 1. Scorpion spiders { Solpuga - { { _Solifugae_ { Galeodes - { { - { { 2. Tarantella { Phrynus - { { _Phrynida_ { Thelyphonus - { I. { - I. { Long spiders { 3. Scorpions { Scorpio - =Spiders= { _Arthrogastres_ { _Scorpioda_ { Buthus - { { - +Arachnida+ { { 4. Book scorpions { Obisium - { { _Pseudoscorpioda_ { Chelifer - { { - { { 5. Tailor spiders { Phalangium - { { _Opilionida_ { Opilio - { - { - { II. { 6. Spinning spiders { Epeira - { Round spiders { _Araneae_ { Mygale - { { { - { _Sphaerogastres_ { 7. Mites { Sarcoptes - { { _Acarida_ { Demodex - - - II. { III. - =Centipedes= { Simple-footed { 8. Simple-footed { Scolopendra - { _Chilopoda_ { _Chilopoda_ { Geophilus - { { - +Scolopendria+ { IV. { 9. Double-footed { Julus - or { Double-footed { _Diplopoda_ { Polydesmus - +Myriapoda+ { _Diplopoda_ { - - - { { 10. Primitive flies { Ephemera - { { _Archiptera_ { Libellula - { { - { { 11. Gauze-wings { Hemerobius - { { _Neuroptera_ { Phryganea - { V. { - { Chewing { 12. Straight-wings { Locusta - { _Masticantia_ { _Orthoptera_ { Forficula - { { - III. { { 13. Beetles { Cicindela - =Flies= { { _Coleoptera_ { Melolontha - { { - +Hexapoda+ { { 14. Bee-wings { Apis - { { _Hymenoptera_ { Formica - { - { - { { 15. Bugs { Aphis - { VI. { _Hemiptera_ { Cimex - { Sucking { - { _Sugentia_ { 16. Two-wings { Culex - { { _Diptera_ { Musca - { { - { { 17. Butterflies { Bombyx - - ---------------------------------------------------------------- - - Butterflies - _Lepidoptera_ - | - Bees | Two-wings - _Hymenoptera_ | _Diptera_ - | | | - | | | - Beetles | | | Bugs - _Coleoptera_ \-------v-----/ | _Hemiptera_ - | | | | - | Gauze wings | | - Straight-wings _Neuroptera_ \-------v------/ - _Orthoptera_ | | - | | | - | | | - \----------------------v-----------------------------/ - - Primaeval Flies - _Archiptera_ - | - Scorpions | Double-footed - _Scorpioda_ | _Diplopoda_ - Tailor Spiders | | | - _Opiliones_ | | | - | Book Scorpions | | | - Mites | _Pseudoscorpioda_ | | | - _Acarida_ | | | | | - | | \-----v-----/ | | - | | | | | - | | Tarantella | | - Weaving Spiders | _Phrynida_ | Simple-footed - _Araneae_ | | | _Chilopoda_ - | | | | =Centipedes= - | | | | +Myriapoda+ - \-------------v--------/ | | - | | | - Scorpion Spiders | | - _Solifugae_ | | - =Spiders.= | | - +Arachnida+ | | - | | | - | =Flies= | - | +Insecta Hexapoda+ | - | | | - | | | - \--------------------v---------------------/ - | - Primary Air-breathing Arthropods - _Protracheata_ - | - | - Articulated Worms - _Coelminthes_ - -Fossil remains of Long Spiders are found in the Coal. The second -sub-class of the Arachnida, the _Round Spiders_ (Sphaerogastres), first -appear in the fossil state in the Jura, that is, at a very much later -period. They have developed out of a branch of the Solifuga, by the -rings of the body becoming more and more united with one another. In the -true _Spinning Spiders_ (Araneae), which we admire on account of their -delicate skill in weaving, the union of the joints of the trunk, or -metamera, goes so far, that the trunk now consists of only two pieces, -of a head-breast (cephalo-thorax) with jaws, feelers, and four pairs of -legs, and of a hinder body without appendages, where the spinning warts -are placed. In _Mites_ (Acarida), which have probably arisen by -degeneration (especially by parasitism) out of a lateral branch of -Spinning Spiders, even these two trunk pieces have become united and now -form an unsegmented mass. - -The class of _Scolopendria_, _Myriapoda_, or Centipedes, the smallest -and poorest in forms of the four classes of Arthropoda, is characterized -by a very elongated body, like that of a segmented Ringed worm, and -often possesses more than a hundred pairs of legs. But these animals -also originally developed out of a six-legged form of Tracheata, as is -distinctly proved by the individual development of the millipede in the -egg. Their embryos have at first only three pairs of legs, like genuine -insects, and only at a later period do the posterior pairs of legs bud, -one by one, from the growing rings of the hinder body. Of the two orders -of Centipedes (which in our country live under barks of trees, in moss, -etc.) the round, _double-footed_ ones (Diplopoda) probably did not -develop until a later period out of the older flat, _single-footed_ ones -(Chilopoda), by successive pairs of rings of the body uniting together. -Fossil remains of the Chilopoda are first met with in the Jura period. - -The third and last class of the Arthropoda breathing through tracheae, is -that of the _Flies_, or _Insects_, in the narrow sense of the word -(Insecta, or Hexapoda), the largest of all classes of animals, and next -to that of Mammalia, also the most important. Although Flies develop a -greater variety of genera and species than all other animals taken -together, yet these are all in reality only superficial variations of a -single type, which is entirely and constantly preserved in its essential -characteristics. In all Flies the three divisions of the trunk--head, -breast (thorax), and hinder body are quite distinct. The _hinder body_, -or _abdomen_, as in the case of spiders, has no articulated appendages. -The central division, the _breast_ or _thorax_, has on its ventral side -three pairs of legs, on its back _two pairs of wings_. It is true that, -in very many Flies, one or both pairs of wings have become reduced in -size or have even entirely disappeared; but the comparative anatomy of -Flies distinctly shows that this deficiency has arisen only gradually by -the degeneration of the wings, and that all the Flies existing at -present are derived from a common, primary Fly, which possessed three -pairs of legs and two pairs of wings. (Compare p. 256.) These wings, -which so strikingly distinguish Flies from all other Arthropoda, -probably arose, as has been already shown, out of the tracheate gills -which may still be observed in the larvae of the ephemeral flies -(Ephemera) which live in water. - -The head of Flies universally possesses, besides the eyes, a pair of -articulated feelers, or antennae, and also three jaws upon each side of -the mouth. These _three pairs of jaws_, although they have arisen in all -Flies from the same original basis, by different kinds of adaptation, -have become changed to very varied and remarkable forms in the various -orders, and are therefore employed for distinguishing and characterizing -the main divisions of the class. In the first place, we may distinguish -two main divisions, namely, Flies with _chewing_ mandibles (Masticantia) -and Flies with _sucking_ mouths (Sugentia). On a closer examination each -of these two divisions may again be divided into two sub-groups. Among -chewing Flies, or Masticantia, we may distinguish the biting and the -licking ones. _Biting flies_ (Mordentia) comprise the most ancient and -primaeval winged Flies, the gauzy-winged (Neuroptera), straight-winged -(Orthoptera), and beetles (Coleoptera). _Licking flies_ (Lambentia) are -represented by the one order of skin-winged (Hymenoptera) Flies. We -distinguish two groups of _Sucking Flies_, or Sugentia, namely, those -which prick and those which sip. There are two orders of pricking Flies -(Pungentia), those with half wings (Hemiptera) and gnats and blow-flies -(Diptera); butterflies are the only _sipping_ Flies (Sorbentia), -Lepidoptera. - -Biting Flies, and indeed the order of _Primaeval Flies_ (Archiptera, or -Pseudoneuroptera) are nearest akin to the still living Flies, and -include the most ancient of all Flies, the primary forms of the whole -class (hence also those of all Tracheata). Among them are, first of all, -the Ephemeral Flies (Ephemera) whose larvae which live in water, in all -probability still show us in their tracheae-gills the organs out of which -the wings of Flies were originally developed. This order further -contains the well known dragon-flies, or Libellula, the wine-glass sugar -mites (Lepisma), the hopping Flies with bladder-like feet (Physopoda), -and the dreaded Termites, fossil remains of which are found even in -coal. The order of Gauze-winged Flies (Neuroptera), probably developed -directly out of the primaeval Flies, which differ from them only by their -perfect series of transformations. Among them are the gauze-flies -(Planipennia), caddis-flies (Phryganida), and fan-flies (Strepsiptera). -Fossil Flies, which form the transition from the primaeval Flies -(Libellula) to the gauze-winged (Sialidae), are found even in coal -(Dictyophylebia). - -The order of _Straight-winged Flies_ (Orthoptera) developed at an early -period out of another branch of the primaeval Flies by differentiation of -the two pairs of wings. This division is composed of one group with a -great variety of forms--cockroaches, grasshoppers, crickets, etc. -(Ulonata)--and of a smaller group consisting only of the well-known -earwigs (Labidura), which are characterised by nippers at the hinder end -of their bodies. Fossil remains of cockroaches, as well as of crickets -and grasshoppers, have been found in coal. - -Fossil remains of the fourth order of Biting Flies, _beetles_ -(Coleoptera) likewise occur in coal. This extremely comprehensive -order--the favourite one of amateurs and collectors--shows more clearly -than any other what infinite variety of forms can be developed -externally by adaptation to different conditions of life, without the -internal structure and the original form of the body being in any way -essentially changed. Beetles have probably developed out of a branch of -the straight-winged Flies, from which they differ only in their -transformations (larva, pupa, etc.). - -The one order of _Licking Flies_, namely, the interesting group of the -_Bees_, or _Skin-winged Flies_ (Hymenoptera), is closely allied to the -four orders of biting Flies. Among them are those Flies which have risen -to such an astonishing degree of mental development, of intellectual -perfection, and strength of character, by their extensive division of -labour, formation of communities and states, and surpass in this not -merely most invertebrate animals, but even most animals in general. This -may be said especially of all ants and bees, also of wasps, leaf-wasps, -wood-wasps, gall-wasps, etc. They are first met with in a fossil state -in the oolites, but they do not appear in greater numbers until the -tertiary period. Probably these insects developed either out of a branch -of the primaeval Flies or the gauze-winged Flies. - -Of the two orders of _Pricking Flies_ (Hemiptera and Diptera), that -containing the _Half-winged Flies_ (Hemiptera), also called Beaked Flies -(Rhynchota), is the older of the two. It includes three sub-orders, -viz., the leaf-lice (Homoptera), the bugs (Heteroptera), and lice -(Pediculina). Fossil remains of the first two classes are found in the -oolites; but an ancient Fly (Eugereon) is found in the Permian system, -and seems to indicate the derivation of the Hemiptera from the -Neuroptera. Probably the most ancient of the three sub-orders of the -Hemiptera are the Homoptera, among which, besides the actual leaf-lice, -are the shield-lice, leaf-fleas, and leaf-crickets, or Cicadae. Lice have -probably developed out of two different branches of Homoptera, by -continued degeneration (especially by the loss of wings); bugs, on the -other hand, by the perfecting and differentiation of the two pairs of -wings. - -The second order of _pricking flies_, namely, the _Two-winged Flies_ -(Diptera), are also found in a fossil state in the oolites, together -with Half-winged Flies; but they probably developed out of the Hemiptera -by the degeneration of the hind wings. In Diptera the fore wings alone -have remained perfect. The principal portion of this order consists of -the elongated gnats (Nemocera) and of the compact blow-flies and -house-flies (Brachycera), the former of which are probably the older of -the two. However, remains of both are found in the oolitic period. The -two small groups of lice-flies (Pupipara) forming chrysales, and the -hopping-fleas (Aphaniptera), probably developed out of the Diptera by -degeneration resulting from parasitism. - -The eighth and last order of Flies, and at the same time the only one -with mouth-parts adapted to sipping liquids, consists of _moths_ and -_butterflies_ (Lepidoptera). This order appears, in several -morphological respects, to be the most perfect class of Flies, and -accordingly was the last to develop. For we only know of fossil remains -of this order from the tertiary period, whereas the three preceding -orders extend back to the oolites, and the four biting orders even to -the coal period. The close relationship between some moths (Tineae) and -(Noctuae), and some caddis-flies (Phryganida) renders it probable that -butterflies have developed from this group, that is, out of the order of -Gauze-winged Flies, or Neuroptera. - -The whole history of Flies, and, moreover, the history of the whole -tribe of Arthropoda, essentially confirms the great laws of -differentiation and perfecting which, according to Darwin's theory of -selection, must be considered as the necessary results of Natural -Selection. The whole tribe, so rich in forms, begins in the Archilithic -period with the class of _Crabs_ breathing by gills, and with the lowest -_Primaeval Crabs_, or Archicaridae. The form of these Primaeval Crabs, -which were developed out of segmented worms, is still approximately -preserved by the remarkable _Nauplius_, in the common larval stage of so -many Crabs. Out of the Nauplius, at a later period, the curious Zoea was -developed, which is the common larval form of all the higher or mailed -crabs (Malacostraca), and, at the same time, possibly of that Arthopod -which at first breathed through tracheae, and became the common ancestor -of all _Tracheata_. This Devonian ancestor, which must have originated -between the end of the Silurian and the beginning of the Coal period, -was probably most closely related to the still living Primaeval Flies, or -_Archiptera_. Out of these there developed, as the main tribe of the -Tracheata, the class of Flies, from the lowest stage of which the -_spiders_ and _centipedes_ separated as two diverging branches. -Throughout a long period there existed only the four biting orders of -Flies--the Primaeval flies, Gauze-wings, Straight-wings, and the Beetles, -the first of which is probably the common primary form of the three -others. It was only at a much later period that the Licking, Pricking, -and Sipping flies developed out of the Biting ones, which retained the -original form of the three pairs of jaws most distinctly. The following -table will show once more how these orders succeeded one another in the -history of the earth. - - -CLASSIFICATION OF FLIES. - - { { 1. Primaeval winged { M.I. } - { { _Archiptera_ { A.A. } - { { } - { I. { 2. Gauze-winged { M.C. } - A. { Biting Flies { _Neuroptera_ { A.A. } - { { } - =Flies= { _Mordentia_ { 3. Straight-winged { M.I. } - =with Chewing= { { _Orthoptera_ { A.D. } - =Mouths= { { } - { { 4. Beetles { M.C. } - +Masticantia+ { { _Coleoptera_ { A.D. } - { - { - { II. { 5. Skin-winged { M.C. } - { Licking Flies { _Hymenoptera_ { A.A. } - { _Lambentia_ { } - } - } - { { 6. Half-winged { M.I. } - { III. { _Hemiptera_ { A.A. } - B. { Stinging Flies { } - =Flies= { { 7. Tway-flies { M.C. } - =with Sucking= { _Pungentia_ { _Diptera_ { A.D. } - =Mouths= { - { - +Sugentia+ { IV. { 8. Butterflies { M.C. } - { Sipping Flies { _Lepidoptera_ { A.A. } - { { { } - { _Sorbentia_ { { } - - - _Note._--The difference in the metamorphosis or transformation and in - the development of the wings of the eight individual orders of Flies - is also specified by the following letters: M.I. = Imperfect - Metamorphosis. M.C. = Perfect Metamorphosis. (Compare Gen. Morph. ii. - p. 99.) A.A. = Equal wings (fore and hinder wings are the same, or - differ but little). A.D. = Unequal wings (fore and hinder wings very - different in structure and texture, occasioned by strong - differentiation). - - - - -CHAPTER XX. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -III. VERTEBRATE ANIMALS. - - - The Records of the Creation of Vertebrate Animals (Comparative - Anatomy, Embryology, and Palaeontology).--The Natural System of - Vertebrate Animals.--The Four Classes of Vertebrate Animals, - according to Linnaeus and Lamarck.--Their increase to Nine - Classes.--Main Class of the Tube-hearted, or Skull-less Animals - (the Lancelet).--Blood Relationship between the Skull-less Fish - and the Tunicates.--Agreement in the Embryological Development - of Amphioxus and Ascidiae.--Origin of the Vertebrate Tribe out of - the Worm Tribe.--Main Class of Single-nostriled, or - Round-mouthed Animals (Hag and Lampreys).--Main Class of - Anamnionate Animals, devoid of Amnion.--Fishes (Primaeval Fish, - Cartilaginous Fish, Osseous Fish).--Mud-fish, or Dipneusta.--Sea - Dragons, or Halisauria.--Frogs and Salamanders, or Amphibia - (Mailed Amphibia, Naked Amphibia).--Main Class of Amnionate - Animals, or Amniota.--Reptiles (Primary Reptiles, Lizards, - Serpents, Crocodiles, Tortoises, Flying-Reptiles, Dragons, - Beaked Reptiles).--Birds (Feather-tailed, Fan-tailed, - Bush-tailed). - - -Not one of the natural groups of organisms--which, we have designated as -tribes, or phyla, on account of the blood-relationship of all the -species included in them--is of such great and exceeding importance as -the tribe of Vertebrate Animals. For, according to the unanimous opinion -of all zoologists, man also is a member of the tribe; and his whole -organization and development cannot possibly be distinguished from that -of other Vertebrate animals. But as from the individual history of -human development, we have already recognized the undeniable fact that, -in developing out of the egg, man at first does not differ from other -Vertebrate animals, and especially from Mammals, we must necessarily -come to the conclusion, in regard to the palaeontological history of his -development, that man has, historically, actually developed out of the -lower Vertebrata, and that he is directly derived from lower mammals. -This circumstance, together with the many high interests which, in other -respects, entitle the Vertebrata to more consideration than other -organisms, justifies us in examining the pedigree of the Vertebrata and -its expression in the natural system, with special care. - -Fortunately, the records of creation, which must in all cases be our -guide in establishing pedigrees, are especially complete in this -important animal tribe, from which our own race has arisen. Even at the -beginning of our century Cuvier's comparative anatomy and palaeontology, -and Baer's ontogeny of the Vertebrate animals, had brought us to a high -level of accurate knowledge on this matter. Since then it is especially -due to Johannes Mueller's and Rathke's investigations in comparative -anatomy, and most recently to those of Gegenbaur and Huxley, that our -knowledge of the natural relationships among the different groups of -Vertebrata has become enlarged. It is especially Gegenbaur's classical -works, penetrated as they are throughout with the fundamental principles -of the Theory of Descent, which have demonstrated that the material of -comparative anatomy receives its true importance and value only by the -application of the Theory of Descent, and this in the case of all -animals, but especially in that in the Vertebrate tribe. Here, as -everywhere else, analogies must be traced to Adaptation, homologies to -Transmission by Inheritance. When we see that the limbs of the most -different Vertebrata, in spite of their exceedingly different external -forms, nevertheless possess essentially the same internal structure; -when we see that in the arm of a man and ape, in the wing of a man or a -bird, in the breast fins of whales and sea-dragons, in the fore-legs of -hoofed animals and frogs, the same bones always lie in the same -characteristic position, articulation and connection--we can only -explain this wonderful agreement and homology by the supposition of a -common transmission by inheritance from a single primary form. On the -other hand, the striking differences of these homologous bodily parts -proceed from adaptation to different conditions of existence. (Compare -Plate IV.) - -Ontogeny, or the individual history of development, like comparative -anatomy, is of especial importance to the pedigree of the Vertebrata. -The first stages of development arising out of the egg are essentially -identical in all Vertebrate animals, and retain their agreement the -longer, the nearer the respective Vertebrate animal forms, when fully -developed, stand to one another in the natural system, that is, in the -pedigree. How far this agreement of germ forms, or embryos, extends, -even in the most highly developed Vertebrate animals, I have already had -occasion to explain (vol i. pp. 306-309). The complete agreement in form -and structure, for example, in the embryos of a man and a dog, of a bird -and a tortoise, existing in the stages of development represented on -Plates II. and III., is a fact of incalculable importance, and furnishes -us with the most important data for the construction of their pedigree. - -Finally, the palaeontological records of creation are also of especial -value in the case of these same Vertebrate animals; for their fossil -remains belong for the most part to the bony skeleton, a system of -organs which is of the utmost importance for understanding their general -organization. It is true that here, as in all other cases, the fossil -records are exceedingly imperfect and incomplete, but more important -remains of extinct Vertebrate animals have been preserved in a fossil -state, than of most other groups of animals; and single fragments -frequently furnish the most important hints as to the relationship and -the historical succession of the groups. - -The name of _Vertebrate Animals_ (Vertebrata), as I have already said, -originated with the great Lamarck, who towards the end of the last -century comprised under this name, Linnaeus' four higher classes of -animals, viz. Mammals, Birds, Amphibious animals, and Fishes, Linnaeus' -two lower classes, Insects and Worms, Lamarck contrasted to the -Vertebrata as _Invertebrata_, later also called _Evertebrata_. - -The division of the Vertebrata into the four classes above named was -retained also by Cuvier and his followers, and in consequence by many -zoologists down to the present day. But in 1822 Blanville, the -distinguished anatomist, found out by comparative anatomy--which Baer did -almost at the same time from the ontogeny of Vertebrata--that Linnaeus' -class of Amphibious animals was an unnatural union of two very different -classes. These two classes were separated as early as 1820, by Merrin, -as two main groups of Amphibious animals, under the names of Pholidota -and Batrachia. The _Batrachia_, which are at present (in a restricted -sense) called Amphibious animals, comprise Frogs, Salamanders, gilled -Salamanders, Caecilia, and the extinct Labyrinthodonta. Their entire -organization is closely allied to that of Fishes. The _Pholidota_, or -Reptiles, on the other hand, are much more closely allied to Birds. They -comprise lizards, serpents, crocodiles, and tortoises, and the groups of -the mesolithic Dragons, Flying reptiles, etc. - -In conformity with this natural division of Amphibious animals into two -classes, the whole tribe of Vertebrate animals was divided into two main -groups. The first main group, containing Amphibious animals and Fishes, -breathe throughout their lives, or in early life, by means of gills, and -are therefore called _gilled Vertebrata_ (Branchiata, or Anallantoida). -The second main group--Reptiles, Birds, and Mammals--breathe at no -period of their lives through gills, but exclusively through lungs, and -hence may appropriately be called Gill-less, or _Vertebrata with lungs_ -(Abranchiata, or Allantoida). However correct this distinction may be, -still we cannot remain satisfied with it if we wish to arrive at a true -natural system of the vertebrate tribe, and at a right understanding of -its pedigree. In this case, as I have shown in my General Morphology, we -are obliged to distinguish three other classes of Vertebrate animals, by -dividing what has hitherto been regarded as the class of fishes into -four distinct classes. (Gen. Morph. vol. ii. Plate VII. pp. 116-160.) - -The first and lowest of these classes comprises the _Skull-less_ animals -(Acrania), or animals with _tubular hearts_ (Leptocardia), of which only -one representative now exists, namely, the remarkable little Lancelet -(Amphioxus lanceolatus). Nearly allied to this is the second class, that -of the _Single-nostriled_ animals (Monorrhina), or _Round-mouthed_ -animals (Cyclostoma), which includes the Hags (Myxinoida) and Lampreys -(Petromyzonta). The third class contains only the genuine Fish (Pisces): -the Mud-fishes (Dipneusta) are added to these as a fourth class, and -form the transition from Fish to Amphibious animals. This distinction, -which, as will be seen immediately, is very important for the genealogy -of the Vertebrate animals, increases the original number of Vertebrate -classes from four to eight. - -In most recent times a ninth class of Vertebrata has been added to these -eight classes. Gegenbaur's recently published investigations in -comparative anatomy prove that the remarkable class of _Sea-dragons_ -(Halisauria), which have hitherto been included among Reptiles, must be -considered quite distinct from these, and as a separate class which -branched off from the Vertebrate stock, even before the Amphibious -animals. To it belong the celebrated large Ichthyosauri and Plesiosauri -of the oolitic and chalk periods, and the older Simosauri of the Trias -period, all of which are more closely allied to Fish than to Amphibious -animals. - -These nine classes of Vertebrate animals are, however, by no means of -the same genealogical value. Hence we must divide them, as I have -already shown in the Systematic Survey on p. 133, into four distinct -main-classes or tribes. In the first place, the three highest classes, -Mammals, Birds, and Reptiles, may be comprised as a natural main-class -under the name of _Amnion animals_ (Amnionata). The _Amnion-less -animals_ (Anamnionata), naturally opposed to them as a second -main-class, include the four classes of Batrachians, Sea-dragons, -Mud-fish, and Fishes. The seven classes just named, the Anamnionata as -well as the Amnionata, agree among one another in numerous -characteristics, which distinguish them from the two lowest classes -(the single-nostriled and tubular-hearted animals). Hence we may unite -them in the natural main group of _Double-nostriled_ animals -(Amphirrhina). Finally, these Amphirrhina on the whole are much more -closely related to those animals with round mouths or single nostrils -than to the skull-less or tube-hearted animals. We may, therefore, with -full justice class the single and double-nostriled animals into one -principal main group, and contrast them as _animals with skulls_ -(Craniota), or _bulbular hearts_ (Pachycardia), to the one class of -_skull-less animals_, or animals with _tubular hearts_. This -classification of the Vertebrate animals proposed by me renders it -possible to obtain a clear survey of the nine classes in their most -important genealogical relations. The systematic relationship of these -groups to one another may be briefly expressed by the following table. - - - A. - =Skull-less Animals= 1. Tubular hearts 1. Leptocardia - (+Acrania+) - - { _a._ Single nostriled - { animals { 2. Round-mouths 2. Cyclostoma - B. { _Monorrhina_ { - =Animals with= { - =Skulls= { b. Double { { 3. Fish 3. Pisces - (+Craniota+) { nostriled { I. Non-Amnionate { 4. Mud-fish 4. Dipneusta - { animals { Anamnia { 5. Sea-dragons 5. Halisauria - or { { { 6. Batrachians 6. Amphibia - { _Amphirrhina_ { - =Thick Hearts= { { II. Amnionate. { 7. Reptiles 7. Reptilia - (+Pachycardia+) { { Amniota { 8. Birds 8. Aves - { { { 9. Mammals 9. Mammalia - - -The only one representative of the first class, the small _lanceolate -fish_, or Lancelet (Amphioxus lanceolatus) (Plate XIII. Fig. _B_), -stands at the lowest stage of organization of all the Vertebrate -animals known to us. This exceedingly interesting and important animal, -which throws a surprising light upon the older roots of our pedigree, is -evidently the last of the Mohicans--the last surviving representative of -a lower class of Vertebrate animals, very rich in forms, and very highly -developed during the primordial period, but which unfortunately could -leave no fossil remains on account of the absence of all solid skeleton. -The Lancelet still lives widely distributed in different seas; for -instance, in the Baltic, North Sea, and Mediterranean, where it -generally lies buried in the sand on flat shores. The body, as the name -indicates, has the form of a narrow lanceolate leaf, pointed at both -extremities. When full grown it is about two inches long, of a white -colour and semi-transparent. Externally, the little lanceolate animal is -so little like a vertebrate animal that Pallas, who first discovered it, -regarded it as an imperfect naked snail. It has no legs, and neither -head, skull, nor brain. Externally, the fore end of the body can be -distinguished from the hinder end only by the open mouth. But still the -Amphioxus in its internal structure possesses those most important -features, which distinguish all Vertebrate animals from all Invertebrate -animals, namely, the spinal rod and spinal marrow. The _spinal rod_ -(Chorda dorsalis) is a straight, cylindrical, cartilaginous staff, -pointed at both ends, forming the central axis of the internal skeleton, -and the basis of the vertebral column. Directly above the spinal rod, on -its dorsal side, lies the _spinal marrow_ (medulla spinalis), likewise -originally a straight but internally hollow cord, pointed at both ends. -This forms the principal piece and centre of the nervous system in all -Vertebrate animals. (Compare above vol. i. p. 303.) In all Vertebrate -animals without exception, man included, these important parts of the -body during the embryological development out of the egg, originally -begin in the same simple form, which is retained throughout life by the -Amphioxus. It is only at a later period that the brain develops by the -expansion of the fore end of the spinal marrow, and out of the spinal -rod the skull which encloses the brain. As these two important organs do -not develop at all in the Amphioxus, we may justly call the class -represented by it, _Skull-less animals_ (Acrania), in opposition to all -the others, namely, to the _animals with skulls_ (Craniota). The -Skull-less animals are generally called _tubular-hearted_ (Leptocardia), -because a centralized heart does not as yet exist, and the blood is -circulated in the body by the contractions of the tubular blood-vessels -themselves. The Skulled animals, which possess a centralized, -thick-walled, bulb-shaped heart, ought then by way of contrast to be -called _bulbular-hearted_ animals (Pachycardia). - -[Illustration: _Ascidia (A.) and Amphioxus (B.)_ Pl. XII. - - E. Haeckel del. Legesse sc.] - -Animals with skulls and central hearts evidently developed gradually in -the later primordial period out of those without skulls and with tubular -hearts. Of this the ontogeny of skulled animals leaves no doubt. But -whence are these same skull-less animals derived? It is only very lately -that an exceedingly surprising answer has been given to this important -question. From Kowalewsky's investigations, published in 1867, on the -individual development of the Amphioxus and the adhering Sea-squirts -(Ascidia) belonging to the class of mantled animals (Tunicata), it has -been proved that the ontogenies of these two entirely different looking -animal-forms agree in the first stage of development in a most -remarkable manner. The freely swimming larvae of the Ascidians (Plate -XII. Fig. _A_) develop the undeniable beginning of a spinal marrow (Fig. -5 _g_) and of a spinal rod (Fig. 5 _c_), and this moreover in entirely -the same way as does the Amphioxus. (Plate XIII. Fig. _B_.) It is true -that in the Ascidians these most important organs of the Vertebrate -animal-body do not afterwards develop further. The Ascidians take on a -retrograde transformation, become attached to the bottom of the sea, and -develop into shapeless lumps, which when looked upon externally would -scarcely be supposed to be animals. (Plate XIII. Fig. _A_.) But the -spinal marrow, as the beginning of the central nervous system, and the -spinal rod, as the first basis of the vertebral column, are such -important organs, so exclusively characteristic of Vertebrate animals, -that we may from them with certitude infer the true blood relationship -of Vertebrate with Tunicate animals. Of course we do not mean to say by -this, that Vertebrate animals are derived from Tunicate animals, but -merely that both groups have arisen out of a common root, and that the -Tunicates, of all the Invertebrata, are the nearest blood relations of -the Vertebrates. It is quite evident that genuine Vertebrate animals -developed progressively during the primordial period (and the skull-less -animals first) out of a group of worms, from which the degenerate -Tunicate animals arose in another and a retrograde direction. (Compare -the more detailed explanation of Plates XII. and XIII. in the Appendix.) - -Out of the Skull-less animals there developed, in the first instance, a -second low class of Vertebrate animals, which still stands far below -that of fish, and which is now represented only by the Hags (Myxinoida) -and Lampreys (Petromyzonta). This class also, on account of the absence -of all solid parts, could, unfortunately, as little as the Skull-less -animals leave fossil remains. From its whole organization and ontogeny -it is quite evident that it represents a very important intermediate -stage between the Skull-less animals and Fishes, and that its few still -existing members are only the last surviving remains of a probably very -highly developed animal group which existed towards the end of the -primordial period. On account of the curious mouth possessed by the Hags -and Lampreys, which they use for sucking, the whole class is usually -called _Round-mouthed_ animals (Cyclostoma). The name of -_Single-nostriled_ animals (Monorrhina) is still more characteristic. -For all Cyclostoma possess a simple, single nasal tube, whereas, in all -other Vertebrate animals (with the exception of the Amphioxus) the nose -consists of two lateral halves, a right and a left nostril. We are -therefore enabled to comprise these latter (Anamnionata and Amnionata) -under the heading, _double-nostriled_ animals (Amphirrhina). All the -Amphirrhina possess a fully developed jaw-skeleton (upper and under -jaw), whereas it is completely wanting in the Monorrhina. - -Apart also from the peculiar nasal formation, and the absence of jaws, -the Single-nostriled animals are distinguished from those with double -nostrils by many peculiarities. Thus they want the important sympathetic -nervous system, and the spleen which the Amphirrhina possess. Of the -swimming bladder, and the two pairs of legs--which all double-nostriled -animals have, at least in their embryonic conditions--not a trace exists -in the Single-nostriled animals, which is the case also in the -Skull-less animals. Hence, we are surely justified in completely -separating the Monorrhina, as we have separated the Skull-less animals, -from the Fishes, with which they have hitherto been erroneously classed. - -[Illustration: _Ascidia (A.) and Amphioxus (B.)_ Pl. XIII. - - E. Haeckel del. Lagesse sc.] - -We owe our first accurate knowledge of the Monorrhina, or Cyclostoma, to -the great zoologist, Johannes Mueller of Berlin; his classical work on -the "Comparative Anatomy of the Myxinoida" forms the foundation of our -modern views on the structure of the Vertebrate animals. He -distinguished two distinct groups among the Cyclostoma, which we shall -consider as sub-classes. - -The first sub-class consists of the Hags (Hyperotreta, or Myxinoida). -They live in the sea as parasites upon other fish, into whose skin they -penetrate (Myxine, Bdellostoma). Their organ of hearing has only one -annular canal, and their single nasal tube penetrates the palate. The -second sub-class, that of Lampreys, or Prides (Hyperoartia, or -Petromyzontia) is more highly developed. It includes the well-known -Lamperns, or Nine-eyes, of our rivers (Petromyzon fluviatilis), with -which most persons are acquainted. They are represented in the sea by -the frequently larger marine or genuine Lampreys (Petromyzon marinus). -The nasal tube of these single-nostriled animals does not penetrate the -palate, and in the auricular organ there are two annular canals. - - -SYSTEMATIC SURVEY - -_Of the 4 Main-classes, 9 Classes, and 26 Sub-classes of Vertebrata._ - -Gen. Morph. vol. ii. Plate VII. pp. 116-160. - - - ====================================================================================== - I. =Skull-less= (+Acrania+), or =Tube-hearted= (+Leptocardia+). - - Vertebrata without head, without skull and brain, without centralized heart. - -------------------------------------------------------------------------------------- - 1. =Skull-less= I. Tube-hearted { 1. Lancelet 1. Amphioxus - +Acrania+ _Leptocardia_ { - -------------------------------------------------------------------------------------- - - II. =Animals with skulls= (+Craniota+) and with =thick-walled hearts= (+Pachycardia+). - Vertebrata with head, with skull and brain, with centralized heart. - - ====================================================================================== - _Main-classes_ | _Classes_ | _Sub-classes_ | _Systematic Name_ - _of the Skulled_ | _of the_ | _of the_ | _of the_ - _Animals._ | _Skulled Animals._ | _Skulled Animals._ | _Sub-classes._ - -------------------------------------------------------------------------------------- - 2. =Single-Nostriled= { II. Round mouths { 2. Hags, or Mucous 2. Hyperotreta - +Monorrhina+ { _Cyclostoma_ { Fish (Myxinoida) - { { 3. Lampreys, or 3. Hyperoartia - { { Pride (Petromyzontia) - - - { III. Fish { 4. Primaeval fish 4. Selachii - { _Pisces_ { 5. Ganoid fish 5. Ganoides - { { 6. Osseous fish 6. Teleostei - { - { IV. Mud-fish { 7. Mud-fish 7. Protopteri - 3. =Non-amnionate= { _Dipneusta_ { - { - +Anamnionata+ { { 8. Primaeval 8. Simosauria - { V. Sea-dragons { dragons - { _Halisauri_ { 9. Snake-dragons 9. Plesiosauria - { { 10. Fish-dragons 10. Ichthyosauria - { - { VI. Batrachians { 11. Mailed Batrachians 11. Phractamphibia - { _Amphibia_ { 12. Naked Batrachians 12. Lissamphibia - - - 4. =Amnion= { VII. Reptiles { 13. Primary reptiles 13. Tocosauria - =Animals= { _Reptilia_ { 14. Lizards 14. Lacertilia - +Amnionata+ { { 15. Serpents 15. Ophidia - { { 16. Crocodiles 16. Crocodilia - { { 17. Tortoises 17. Chelonia - { { 18. Flying reptiles 18. Pterosauria - { { 19. Dragons 19. Dinosauria - { { 20. Beaked reptiles 20. Anomodontia - { - { VIII. Birds { 21. Long-tailed 21. Saururae - { _Aves_ { 22. Fan-tailed 22. Carinatae - { { 23. Bush-tailed 23. Ratitae - { - { IX. Mammals { 24. Cloacal animals 24. Monotrema - { _Mammalia_ { 25. Pouched animals 25. Marsupialia - { { 26. Placental animals 26. Placentalia - - ---------------------------------------------------------------- - - 9. Mammals - _Mammalia_ - 8. Birds | - _Aves_ | - | | - 7. Reptiles | - _Reptilia_ | - 5. Sea-dragons | | - _Halisauria_ \-------v--------/ - | | - Osseous fish | =Amnion Animals= - _Teleostei_ 4. Mud-fish | +Amniota+ - | _Dipneusta_ | | - | | | | - | | | 6. Batrachians - Ganoid fish | | _Amphibia_ - _Ganoidei_ | | | - | | | | - | \--------------v--------------/ - | | - | Vertebrate animals breathing through lungs - | _Amphipneumones_ - | | - | | - \------------v-----------------/ - Primaeval fish Selachii - 3. Fishes _Pisces_ - =Double-nostriled= +Amphirrhina+ - | 2. Round-mouthed - | _Cyclostoma_ - | | - | | - \--------------------v-------------/ - =Single-nostriled= Monorrhina - =Animals with skulls= +Craniota+ - - 1. Tube-hearted | - _Leptocardia_ | - | | - | | - \---------v------/ - _Ascidiae_ | - Sea-barrels | =Skull-less Animals= - _Thaliacea_ | +Acrania+ - | | =Vertebrate Animals= - | | +Vertebrata+ - \----v----/ | - | | - =Tunicate Animals= | - +Tunicata+ | - | | - | | - \-----------v---------/ - | - Worms - _Vermes_ - - -All existing Vertebrate animals, with the exception of the Monorrhina -and Amphioxus just mentioned, belong to the group which we designate as -Double-nostriled animals (Amphirrhina). All these animals possess (in -spite of the great variety in the rest of their forms) a nose consisting -of two lateral halves, a jaw-skeleton, a sympathetic nervous system, -three annular canals connected with the auricular sac, and a spleen. -Further, all Double-nostriled animals possess a bladder-shaped expansion -of the gullet, which, in Fish, has developed into the swimming bladder, -but in all other Double-nostriled animals into lungs. Finally, in all -Double-nostriled animals there exist in the youngest stage of growth the -beginnings of two pairs of extremities, or limbs, a pair of fore legs, -or breast fins, and a pair of hinder legs, or ventral fins. One of these -pairs of legs sometimes degenerates (as in the case of eels, whales, -etc.), or both pairs of legs (as in Caeciliae and serpents) either -degenerate or entirely disappear; but even in these cases there exists -some trace of their original beginning in an early embryonic period, or -the useless remains of them may be found in the form of rudimentary -organs. (Compare above, vol. i. p. 13.) - -From all these important indications we may conclude with full assurance -that all double-nostriled animals are derived from a single common -primary form, which developed either directly or indirectly during the -primordial period out of the Monorrhina. This primary form must have -possessed the organs above mentioned, and also the beginning of a -swimming bladder and of two pairs of legs or fins. It is evident, that -of all still living double-nostriled animals, the lowest forms of sharks -are most closely allied to this long since extinct, unknown, and -hypothetical primary form, which we may call the Primary -Double-nostriled animals (Proselachii). We may therefore look upon the -group of primaeval fish, or Selachii, to which the _Proselachii_ probably -belonged, as a primary group, not only of the Fish class, but of the -whole main-class of double-nostriled animals. - -The class of _Fish_ (Pisces) with which we accordingly begin the series -of Double-nostriled animals, is distinguished from the other six classes -of the series by the swimming bladder never developing into lungs, but -acting only as a hydrostatic apparatus. Agreeing with this, we find that -in fish the nose is formed by two blind holes in front of the mouth, -which never pierce the palate so as to open into the cavity of the -mouth. In the other six classes of double-nostriled animals, both -nostrils are changed into air passages which pierce the palate, and thus -conduct air to the lungs. Genuine fish (after the exclusion of the -Dipneusta) are accordingly the only double-nostriled animals which -exclusively breathe through gills and never through lungs. In accordance -with this, they all live in water, and both pairs of their legs have -retained the original form of paddling fins. - - -SYSTEMATIC SURVEY - -_Of the 7 Legions and 15 Orders of the Fishes._ - - - --------------------------------------------------------------------------------- - _Sub-classes_ | _Legions_ | _Orders_ | _Examples_ - _of_ | _of_ | _of_ | _from_ - _Fishes._ | _Fishes._ | _Fishes._ | _the Orders._ - --------------------------------------------------------------------------------- - { - { { 1. Sharks Sharks, dog-fish - { I. Transverse { _Squalacei_ - A. { mouths { 2. Rays Spiked rays, electric - =Primaeval= { _Plagiostomi_ { _Rajacei_ rays, etc. - =Fish= { - +Selachii+ { II. Sea-Cats { 3. Sea-Cats Chimaera, Calorrhynchias - { _Holocephali_ { _Chimaeracei_ - - - { { 4. Buckler-heads Cephalaspidae, Placoderma, - { III. Mailed Ganoid { _Pamphracte_ etc. - { Fish { 5. Sturgeons Spoon-sturgeons, sturgeons, - { _Tabuliferi_ { _Sturiones_ sterlet, etc. - { - { { 6. _Efulcri_ Double-finned - B. { IV. Angular-scaled { 7. _Fulcrati_ Palaeoniscus, bony pike, - =Ganoid= { Ganoid Fish { etc. - =Fish= { _Rhombiferi_ { 8. _Semaeopteri_ African finny pike, etc. - +Ganoides+ { - { V. Round-scaled { 9. _Coeloscolopes_ Holoptychius, Coelacanthides, - { Ganoid Fish { etc. - { _Cycliferi_ { 10. _Pycnoscolopes_ Coccolepida, Amiadae, - etc. - - { VI. Osseous Fish { - { with an air { 11. Herring species Herrings, salmon, carp, - { passage to the { _Thrissogenes_ etc. - C. { swimming { 12. Eel species Eels, snake eels, electric - =Osseous= { bladder { _Enchelygenes_ eels, etc. - =Fish= { _Physostomi_ { - +Teleostei+ { - { VII. Osseous Fish { 13. _Stichobranchii_ Perch, wrasse, turbot, - { without an air { etc. - { passage to the { 14. _Plectognathi_ Trunk fish, globe fish, - { swimming { etc. - { bladder { 15. _Lophobranchii_ Pipe fish, sea horses, - { _Physoclisti_ { etc. - - ---------------------------------------------------------------- - -PEDIGREE OF THE NON-AMNIONATE CRANIOTA. - - - Plectognathi Anura - | Lophobranchia Peromela | - | | | | - | | | Sozura - \-------v-----/ Labyrinthodonta | | - | | | | - Stichobranchia | | | - +Physoclisti+ \--v-----/ | - | | | - Enchelygenes | Ganocephala Sozobranchia - | | +Phractamphibia+ +Lissamphibia+ - | | | | - \--v---/ | | - | \-------v-------/ - | | - Thrissogenes +Amphibia+ - +Physostomi+ Semaeopteri | - +Teleostei+ | | - | | Protopteri | - | Fulcrati | | | Plesiosauria - Pycnoscolopes | | | | Icthyosauria | - | | | | | | | - Coeloscolopes Efulcri | | | | | - +Cycliferi+ +Rhombiferi+ | | | | - (Cycloganoides) (Rhomboganoides) | | | | - | | | | | | - \---------v--------/ | | \----v-----/ - | +Dipneusta+ | | - Placoderma | | Simosauria - Sturiones | | | +Halisauria+ - | | | | | - Cephalaspidae | Rajacei \-----------v--------/ - | | | | - | | | Amphipneumona - \-----v-------/ | | - | | | - Pamphracti | | - +Tabuliferi+ | | - (Placoganoides) | Chimaeracei | - +Ganoides+ | +Holocephali+ | - | | | | - Squalacei | | | - | | | | - \--------v---------/ | | - | | | - +Plagiostomi+ | | - | | | - \-------------v---------------------/ - | - +Selachii+ - +Fish+ - +Amphirrhina+ - | Cyclostoma - | +Monorrhina+ - | | - \-------v---------/ - | - +Craniota+ - - -Genuine fish are divided into three distinct sub-classes, namely, -Primaeval fish, Ganoid fish, and Osseous fish. The oldest of these, where -the original form has been most faithfully preserved, is that of the -_Primaeval fish_ (Selachii). Of these there still exist Sharks (Squali), -and Rays (Rajae), which are classed together as cross-mouthed fishes -(Plagiostomi), and the strange and grotesquely formed Sea-cats, or -_Chimaeracei_ (Holocephali). These primary fish of the present day, which -are met with in all seas, are only poor remains of the prevailing animal -groups, rich in forms, which the Selachii formed in the earlier periods -of the earth's history, and especially during the palaeolithic period. -Unfortunately all Primaeval fish possess a cartilaginous, never a -completely osseous skeleton, which is but little, if at all, capable of -being petrified. The only hard parts of the body which could be -preserved in a fossil state, are the teeth and fin-spikes. These are -found in the older formations in such quantities, varieties, and sizes, -that we may, with certainty, infer a very considerable development of -Primaeval fish in those remote ages. They are even found in the Silurian -strata, which contain but few remains of other Vertebrata, such as -Enamelled fish (and these only in the most recent part, that is, in the -upper Silurian). By far the most important and interesting of the three -orders of Primaeval fish are Sharks; of all still living double-nostriled -animals, they are probably most closely allied to the original primary -form of the whole group, namely, to the Proselachii. Out of these -Proselachii, which probably differed but little from genuine Sharks, -Enamelled fish, and the present Primaeval fish, in all probability, -developed in one direction, and the Dipneusta, Sea-dragons, and Amphibia -in another. - -The _Ganoid_, or _Enamelled fish_ (Ganoides), in regard to their anatomy -stand midway between the Primaeval and the Osseous fish. In many -characteristics they agree with the former, and in many others with the -latter. Hence, we infer that genealogically they form the transition -from Primaeval to Osseous fish. The Ganoids are for the most part -extinct, and more nearly so than the Primaeval fish, whereas they were -developed in great force during the entire palaeolithic and mesolithic -periods. Ganoid fish are divided into three legions according to the -form of their external covering, namely, Mailed, Angular-scaled, and -Round-scaled. The _Mailed Ganoid fish_ (Tabuliferi) are the oldest, and -are directly allied to the Selachii, out of which they originated. -Fossil remains of them, though rare, are found even in the upper -Silurian (Pteraspis ludensis of the Ludlow strata). Gigantic species of -them, coated with strong bony plates, are found in the Devonian system. -But of this legion there now lives only the small order of Sturgeons -(Sturiones), including the Spade-sturgeons (Spatularidae), and those -Sturgeons (Accipenseridae) to which belong, among others, the Huso, which -yields isinglass, or sturgeon's sound, and the Caviar-sturgeon, whose -eggs we eat in the shape of caviar, etc. Out of the mailed Ganoid fish, -the angular and round-scaled ones probably developed as two diverging -branches. The _Angular-scaled Ganoid fish_ (Rhombiferi)--which can be -distinguished at first sight from all other fish by their square or -rhombic scales--are at present represented only by a few survivors, -namely, the Finny Pike (Polypterus) in African rivers (especially the -Nile), and by the Bony Pike (Lepidosteus) in American rivers. Yet during -the palaeolithic and the first half of the mesolithic epochs this legion -formed the most numerous group of fishes. The third legion, that of -_Round-scaled Ganoid fish_ (Cycliferi), was no less rich in forms, and -lived principally during the Devonian and Coal periods. This legion, of -which the Bald Pike (Amia), in North American rivers, is the only -survivor, was especially important, inasmuch as the third sub-class of -fish, namely, Osseous fish, developed out of it. - -_Osseous fish_ (Teleostei) include the greater portion of the fish of -the present day. Among these are by far the greater portion of marine -fish, and all of our fresh-water fish except the Ganoid fish just -mentioned. This class is distinctly proved by numerous fossils to have -arisen about the middle of the Mesolithic epoch out of Ganoid fish, and -moreover out of the Round-scaled, or Cycliferi. The Thrissopidae of the -Oolitic period (Thrissops, Leptolepis, Tharsis), which are most closely -allied to the herrings of the present day, are probably the oldest of -all Osseous fish, and have directly arisen out of Round-scaled Ganoid -fish, closely allied to the existing Amia. In the older Osseous fish of -the legion called _Physostomi_, as also in the Ganoides, the swimming -bladder throughout life was connected with the throat by a permanent air -passage (a kind of windpipe). This is still the case with all the fish -belonging to this legion, namely, with herrings, salmon, carp, shad, -eels, etc. However, during the chalk period this air passage, in some of -the Physostomi, became constricted and closed, and the swimming bladder -was thus completely separated from the throat. Hence there arose a -second legion of Osseous fish, the _Physoclisti_, which did not attain -their actual development until the tertiary epoch, and soon far -surpassed the Physostomi in variety. To this legion belong most of the -sea fish of the present day, especially the large families of the -Turbot, Tunny, Wrasse, Crowfish, etc., further, the Lock-jaws -(Plectognathi), Trunk fish, and Globe-fish and the Bushy-gills -(Lophobranchi), viz., Pipe-fish, and Sea-horses. There are, however, -only very few Physoclisti among our river fish, for instance, Perch and -Sticklebacks; the majority of river fish are Physostomi. - -Midway between genuine Fish and Amphibia is the remarkable class of -_Mud-fish_, or _Scaly Sirens_ (Dipneusta, or Protopteri). There now -exist only a few representatives of this class, namely, the American -Mud-fish (Lepidosiren paradoxa) in the region of the river Amazon, and -the African Mud-fish (Protopterus annectens) in different parts of -Africa. A third large Salamander-fish (Ceratodus Fosteri) has lately -been discovered in Australia. During the dry season, that is in summer, -these strange animals bury themselves in a nest of leaves in the dry -mud, and then breathe air through lungs like the Amphibia. But during -the wet season, in winter, they live in rivers and bogs, and breathe -water through gills like fish. Externally, they resemble fish of the eel -kind, and are like them covered with scales; in many other -characteristics also--in their internal structure, their skeleton, -extremities, etc.--they resemble Fish more than Amphibia. But in certain -features they resemble the Amphibia, especially in the formation of -their lungs, nose, and heart. There is consequently an endless dispute -among zoologists, as to whether the Mud-fish are genuine Fish or -Amphibia. Distinguished zoologists have expressed themselves in favour -of both opinions. But in fact, owing to the complete blending of -characteristics which they present, they belong neither to the one nor -to the other class, and are probably most correctly dealt with as a -special class of Vertebrata, forming the transition between Fishes and -Amphibians. The still living Dipneusta are probably the last surviving -remains of a group which was formerly rich in forms, but has left no -fossil traces on account of the want of a solid skeleton. In this -respect, these animals are exactly like the Monorrhina and the -Leptocardia. However, teeth are found in the Trias which resemble those -of the living Ceratodus. Possibly the extinct Dipneusta of the -palaeolithic period, which developed in the Devonian epoch out of -primaeval fish, must be looked upon as the primary forms of the Amphibia, -and thus also of all higher Vertebrata. At all events the unknown forms -of transition--from Primaeval fish to Amphibia--were probably very like -the Dipneusta. - -A very peculiar class of Vertebrate animals, long since extinct, and -which appears to have lived only during the secondary epoch, is formed -by the remarkable _Sea-dragons_ (Halisauria, or Enaliosauria, also -called Nexipoda, or Swimming-footed animals). These formidable animals -of prey inhabited the mesolithic oceans in great numbers, and were of -most peculiar forms, sometimes from thirty to forty feet in length. From -many and excellently preserved fossil remains and impressions, both of -the entire body of Sea-dragons as well as of single parts, we have -become very accurately acquainted with the structure of their bodies. -They are usually classed among Reptiles, whilst some anatomists have -placed them in a much lower rank, as directly allied to Fish. -Gegenbaur's recently published investigations, which place the structure -of their limbs in a true light, have led to the surprising conclusion -that the Sea-dragons form quite an isolated group, differing widely both -from Reptiles and Amphibia as well as from Fish. The skeleton of their -four legs, which are transformed into short, broad, paddling fins (like -those of fish and whales) furnishes us with a clear proof that the -Halisauria branched off from the main-stock of Vertebrata at an earlier -period than the Amphibia. For Amphibia, as well as the three higher -classes of Vertebrata, are all derived from a common primary form, which -possessed only _five_ toes or fingers on each leg. But the Sea-dragons -have (either distinctly developed or in a rudimentary condition as parts -of the skeleton of the foot) more than five fingers, as have also the -Selachians or Primaeval fish. On the other hand, they breathed air -through lungs, like the Dipneusta, although they always swam about in -the sea. They, therefore, perhaps, in conjunction with the Dipneusta, -branched off from the Selachii, but did not develop into higher -Vertebrata; they form an extinct lateral line of the pedigree, which has -died out. - -The more accurately known Sea-dragons are classed into three orders, -distinct enough one from the other, namely, _Primaeval Dragons_, _Fish -Dragons_, and _Serpent Dragons_. The _Primaeval Dragons_ (Simosauria) are -the oldest Sea-dragons, and lived only during the Trias period. The -skeletons of many different genera of them are met with in the German -limestone known as "Muschel-kalk." They seem upon the whole to have been -very like the Plesiosauria, and are, consequently, sometimes united with -them into one order as Sauropterygia. The _Serpent Dragons_ -(Plesiosauria) lived in the oolitic and chalk periods together with the -Ichthyosauria. They were characterised by an uncommonly long thin neck, -which was frequently longer than the whole body, and carried a small -head with a short snout. When their arched neck was raised they must -have looked very like a swan; but in place of wings and legs they had -two pairs of short, flat, oval-paddling fins. - -The body of the _Fish Dragons_ (Ichthyosauria) was of an entirely -different form; these animals may be opposed to the two preceding orders -under the name of Fish-finners (Ichthyopterygia). They possessed a very -long extended body, like a fish, and a heavy head with an elongated, -flat snout, but a very short neck. Externally, they were probably very -like porpoises. Their tail was very long, whereas it was very short in -the members of the preceding orders. Also both pairs of paddling fins -are broader and show very different structure from that seen in the -other two orders. Probably the Fish Dragons and Serpent Dragons -developed as two diverging branches out of the Primaeval Dragons; but it -is also possible that the Plesiosauria alone originated out of the -Simosauria, and that the Ichthyosauria were lower off-shoots from the -common stock. At all events, they must all be directly, or indirectly -derived from the Selachii, or Primaeval fish. - -The succeeding classes of Vertebrata, the _Amphibia_ and the _Amniota_ -(Reptiles, Birds, and Mammals), owing to the characteristic structure -which they all exhibit of five toes to each foot, may all be derived -from a common primary form, which originated from the Selachii, and -which possessed five toes on each of its four limbs. When we find a less -number of toes than five, we can show that the missing ones must have -been lost in the course of time by adaptation. The oldest known -Vertebrata with five toes are the _Batrachias_ (Amphibia). We divide -this class into two sub-classes, namely, mailed Batrachians and naked -Batrachians, the first of which is distinguished by the body being -covered with bony plates or scales. - -The first and elder sub-class of Amphibia consists of the _Mailed -Batrachians_ (Phractamphibia), the oldest land living Vertebrata of -which fossil remains exist. Well-preserved fossil remains of them occur -in the coal, especially of those with _Enamelled heads_ (Ganocephala), -which are most closely allied to fish, namely, the Archegosaurus of -Saarbruck, and the Dendrerpeton of North America. There then follow at a -later period the gigantic _Labyrinth-toothed animals_ (Labyrinthodonta), -which are represented in the Permian system by Zygosaurus, but at a -later period, more especially in the Trias, by Mastodonsaurus, -Trematosaurus, Capitosaurus, etc. The shape of these formidable -rapacious animals seems to have been between that of crocodiles, -salamanders, and frogs, but in their internal structure they were more -closely related to the two latter, while by their solid coat of mail, -formed of strong bony plates, they resembled the first animals. These -gigantic mailed Batrachians seem to have become extinct towards the end -of the Triassic period. No fossil remains of mailed Batrachia are known -during the whole of the subsequent periods. However, the still living -blind Snakes, or _Caeciliae_ (Peromela)--small-scaled Phractamphibia of -the form and the same mode of life as the earth-worm--prove that this -sub-class continued to exist, and never became completely extinct. - -The second sub-class of Amphibia, the _naked Batrachia_ (Lissamphibia), -probably originated even during the primary and secondary epochs, -although fossil remains of them are first found in the tertiary epoch. -They are distinguished from mailed Batrachia by possessing a naked -smooth, and slimy skin, entirely without scales or coat of mail. They -probably developed either out of a branch of the Phractamphibia, or out -of the same common root with them. The ontogeny of the three still -living orders of naked Batrachia--the gilled Batrachia, tailed -Batrachia, and frog Batrachia--distinctly repeats the historical course -of development of the whole sub-class. The oldest forms are the gilled -Batrachia (Sozobranchia), which retain throughout life the original -primary form of naked Batrachia, and possess a long tail, together with -water-breathing gills. They are most closely allied to the Dipneusta, -from which, however, they differ externally by the absence of the coat -of scales. Most gilled Batrachia live in North America: among others of -the class is the Axolotl, or Siredon, already mentioned. (Compare above, -vol. i. p. 241.) In Europe the order is only represented by one form, -the celebrated "Olm" (Proteus anguinus), which inhabits the grotto of -Adelsberg and other caves in Carinthia, and which, from living in the -dark, has acquired rudimentary eyes which can no longer see (vol. i. p. -13). The order of Tailed Batrachia (Sozura) have developed out of the -gilled Batrachia by the loss of external gills; the order includes our -black and yellow spotted land Salamander (Salamandra maculata), and our -nimble aquatic Salamanders (Tritons). Many of them--for instance, the -celebrated giant Salamanders in Japan (Cryptobranchus Japonicus)--still -retain the gill-slits, although the gills themselves have disappeared. -All of them, however, retain the tail throughout life. Tritons -occasionally--when forced to remain in water always--retain their gills, -and thus remain at the same stage of development as gilled Batrachia. -(Compare above, vol. i. p. 241.) The third order, the _tailless_ or -_frog-like Batrachia_ (Anura), during their metamorphosis, not only lose -their gills, with which in early life (as so-called tadpoles) they -breathe in water, but also the tail with which they swim about. During -their ontogeny, therefore, they pass through the course of development -of the whole sub-class, they being at first _Gilled Batrachia_, then -_Tailed Batrachia_, and finally _Frog-like Batrachia_. The inference -from this is evidently, that _Frog-like Batrachia_ developed at a later -period out of _Tailed Batrachia_, as the latter had developed out of -_Gilled Batrachia_ which originally existed alone. - -In passing from the Amphibia to the next class of Vertebrata, namely, -Reptiles, we observe a very considerable advance in the progress of -organization. All the double-nostriled animals (Amphirrhina) up to this -time considered, and more especially the two larger classes of Fish and -Batrachia, agree in a number of important characteristics, which -essentially distinguish them from the three remaining classes of -Vertebrata--Reptiles, Birds, and Mammals. During the embryological -development of these latter, a peculiarly delicate covering, the _first -foetal membrane_, or _amnion_, which commences at the navel, is formed -round the embryo; this membrane is filled with the amnion-water, and -encloses the embryo or germ in the form of a bladder. On account of this -very important and characteristic formation, we may comprise the three -most highly developed classes of Vertebrata under the term -_Amnion-animals_ (Amniota). The four classes of double-nostriled animals -which we have just considered, in which the amnion is wanting (as is the -case in all lower Vertebrate animals, single-nostriled and skull-less -animals), may on the other hand be opposed to the others as _amnion-less -animals_ (Anamnia). - -The formation of the foetal membrane, or amnion, which distinguishes -reptiles, birds, and mammals from all other Vertebrata, is evidently a -very important process in their ontogeny, and in the phylogeny which -corresponds with it. It coincides with a series of other processes, -which essentially determine the higher development of Amnionate animals. -The first of these important processes is the _total loss of gills_, for -which reason the Amniota, under the name of _Gill-less animals_ -(Ebranchiata), were formerly opposed to all other Vertebrate animals -which breathed through gills (Branchiata). In all the Vertebrate already -discussed, we found that they either always breathed through gills, or -at least did so in early life, as in the case of Frogs and Salamanders. -On the other hand, we never meet with a Reptile, Bird, or Mammal which -at any period of its existence breathes through gills, and the -gill-arches and openings which do exist in the embryos, are, during the -course of the ontogeny, changed into entirely different structures, -viz., into parts of the jaw-apparatus and the organ of hearing. (Compare -above, vol. i. p. 307.) All Amnionate animals have a so-called cochlea -in the organ of hearing, and a "round window" corresponding with it. -These parts are wanting in the Amnion-less animals; moreover, their -skull lies in a straight line with the axis of the vertebral column. In -Amniotic animals the base of the skull appears bent in on the abdominal -side, so that the head sinks upon the breast. (Plate III. Fig. _C_, _D_, -_G_, _H_.) The organs of tears at the side of the eye also first develop -in the Amniota. - -The question now is, When did this important advance take place in the -course of the organic history of the earth? When did the common ancestor -of all Amniota develop out of a branch of the Non-amniota, to wit, out -of the branch of the Amphibia? - -To this question, the fossil remains of Vertebrata do not give us a very -definite, but still they do give an approximate, answer. For with the -exception of two lizard-like animals found in the Permian system (the -Proterosaurus and Rhopalodon), all the fossil remains of Amniota, as yet -known, belong to the _secondary_, _tertiary_, and _quaternary epochs_. -With regard to the two Vertebrata just named, it is still doubtful -whether they are genuine reptiles, or perhaps Amphibia of the salamander -kind. Their skeleton alone is known to us, and even this not perfectly. -Now as we know nothing of the characteristic features of their soft -parts, it is quite possible that the Proterosaurus and Rhopalodon were -non-amnionate animals more closely allied to Amphibia than to Reptiles; -possibly they belonged to the transition form between the two classes. -But, on the other hand, as undoubted fossil remains of Amniota have been -found as early as the Trias, it is probable that the _main class of -Amniota_ first developed in the Trias, that is, in the beginning of the -Mesolithic epoch. As we have already seen, this very period is evidently -one of the most important turning points in the organic history of the -earth. The palaeolithic fern forests were then replaced by the pine -forests of the Trias period; important transformations then took place -in many of the classes of Invertebrata. Articulated marine lilies -(Colocrina) developed out of the plated ones (Phatnocrina.) The -Autechinidae, or sea-urchins with only twenty rows of plates, took the -place of the palaeolithic Palechinidae, the sea-urchins with more than -twenty rows of plates. The Cystideae, Blastoideae, Trilobita, and other -characteristic groups of Invertebrata of the primary period became -extinct. It is no wonder that transforming conditions of adaptation -powerfully influenced the Vertebrate tribes also in the beginning of the -Trias period, and caused the origin of Amniotic animals. - -If, however, the two Lizard and Salamander-like animals of the Permian -system, the Proterosaurus and Rhopalodon, are considered genuine -Reptiles, and consequently the most ancient Amniota, then the origin of -this main class must necessarily have taken place in the preceding -period, towards the end of the primary, namely, in the Permian period. -However, all other remains of Reptiles, which were formerly believed to -have been found in the Permian and the Coal system, or even in the -Devonian system, have been proved to be either not remains of Reptiles -at all, or to belong to a more recent date (for the most part to the -Trias). (Compare Plate XIV.) - -The common hypothetical primary form of all Amniotic animals, which we -may call _Protamnion_, and which was possibly nearly related to the -Proterosaurus, very probably stood upon the whole midway between -salamanders and lizards, in regard to its bodily formation. Its -descendants divided at an early period into two different lines, one of -which became the common primary form of Reptiles and Birds, the other -the primary form of Mammals. - -Of all the three classes of Amniota, _Reptiles_ (Reptilia, or Pholidota, -also called Sauria in the widest sense), remain at the lowest stage of -development, and differ least from their ancestors, the Amphibia. Hence -they were formerly universally included among them, although their whole -organization is much more like that of Birds than Amphibia. There now -exist only four orders of Reptiles, namely,--Lizards, Serpents, -Crocodiles, and Tortoises. They, however, form but a poor remnant of the -exceedingly various and highly developed host of Reptiles which lived -during the Mesolithic, or Secondary epoch, and predominated over all -other Vertebrata. The immense development of Reptiles during the -Secondary epoch is so characteristic that we could as well name it after -those animals as after the Gymnosperms (p. 111). Twelve of the -twenty-seven sub-orders, given on the accompanying table, and four of -the eight orders, belong exclusively to the secondary period. These -mesolithic groups are marked by an asterisk. All the orders, with the -exception of Serpents, are found fossilized even in the Jura and Trias -periods. - -[Illustration: _Pl. XIV._ - - [Horizontal axis:] - Branches, - Classes, - and Sub-Classes, - of the Vertebrate - Stem. - - Prochordata - Evertebrate - Forefathers - of the - Vertebrate - - Skull-less - (Acrania) - or - Tube-hearted - Fish, - (Leptocardia) - - Single - nostrilled - (Monorrhina) - or - Round-mouthed - Fishes - (Cyclostoma) - - Anamnia { Paired-nostrilled forms or Amphirrhina - { with gills, without Amnion. - Fish, Pisces - - Primeval - Fish, - Selachii. - - Enamelled - Fish, - Ganoides. - - Bony - Fish, - Teleostei. - - Mud - Fish, - Dipneusta. - - Sea-Dragons, - Halisauria. - - Frogs and - Newts, - Amphibia. - - Amniota { Paired nostrilled or Amphirrhina - { with Amnion, without gills. - - Reptiles, Reptilia. - - Primaeval - Reptiles, - Tocosauria. - - Lizards, - Lacertilia. - - Snakes, - Ophidia. - - Crocodiles, - Crocodilia. - - Tortoises, - Chelonia. - - Flying - Reptiles, - Pterosauria. - - Dragons, - Dinosauria. - - Billed - Reptiles, - Anomodontia. - - Birds, - Aves. - - Suckling animals, Mammalia. - - Billed - Animals, - Monotrema. - - Pouched - Animals, - Marsupialia. - - Placental - Animals, - Placentalia. - - [Vertical axis:] - Cenolithic or - Tertiary Epoch. - - Pliocene - Age. - - Miocene - Age. - - Eocene - Age. - - Mesolithic or - Secondary Epoch. - - Chalk - Period. - - Jurassic - Period. - - Triassic - Period. - - Palaeolithic or - Primary Epoch. - - Permian - Period. - - Coal - Period. - - Devonian - Period. - - Archilithic or - Primordial Epoch. - - Silurian - Period. - - Cambrian - Period. - - Laurentian - Period. - - [Legend:] - Single or - MONOPHYLETIC PEDIGREE - of the Stem of the - BACK-BONED ANIMALS - Based on Palaeontology. - - Relative lengths of the 5 - Epochs in per centages. - - Quarternary Epoch 0.5 - Tertiary Epoch 2.3 - Secondary Epoch 11.5 - Primary Epoch 32.1 - Primordial Epoch 53.6 - ------ - _Total_ 100.0] - -In the first order, that of _Primary Reptiles_, or _Primary Creepers_ -(Tocosauria), we class the extinct _Thecodontia_ of the Trias, together -with those Reptiles which we may look upon as the common primary form of -the whole class. To the latter, which we may call _Primaeval Reptiles_ -(Proreptilia), the Proterosaurus of the Permian system very probably -belongs. The seven remaining orders must be considered as diverging -branches, which have developed in different directions out of that -common primary form. The Thecodontia of the Trias, the only positively -known fossil forms of Tocosauria, were Lizards which seem to have been -like the still living monitor lizards (Monitor, Varanus). - - -SYSTEMATIC SURVEY - -_Of the 8 Orders and 27 Sub-orders of Reptiles._ - -(Those groups marked with * became extinct even during the Secondary -Period.) - - ----------------------------------------------------------------------------------- - | _Sub-orders_ | _Systematic Name_ | _A Generic Name_ - _Orders_ | _of_ | _of the_ | _as_ - _of Reptiles._ | _Reptiles._ | _Sub-orders._ | _an example._ - ----------------------------------------------------------------------------------- - I. =Primary= { 1. Primaeval reptiles 1. Proreptilia * (Proterosaurus?) - =Reptiles= { - +Tocosauria+ { 2. 2. Thecodontia * Palaeosaurus - - { 3. Cleft-tongued 3. Fissilingues Monitor - { 4. Thick-tongued 4. Crassilingues Iguana - II. =Lizards= { 5. Short-tongued 5. Brevilingues Anguis - +Lacertilia+ { 6. Ringed lizards 6. Glyptodermata Amphisbaena - { 7. Chameleons 7. Vermilingues Chamaeleo - - { 8. Adders 8. Aglyphodonta Coluber - { 9. Tree serpents 9. Opisthoglypha Dipsas - III. =Serpents= { 10. 10. Proteroglypha Hydrophis - +Ophidia+ { 11. Vipers 11. Solenoglypha Vipera - { 12. Worm serpents 12. Opoterodonta Typhlops - - { 13. Amphicoela 13. Teleosauria * Teleosaurus - IV. =Crocodiles= { 14. Opisthocoela 14. Steneosauria * Steneosaurus - +Crocodilia+ { 15. Prosthocoela 15. Alligatores Alligator - - { 16. Sea tortoises 16. Thalassita Chelone - V. =Tortoises= { 17. River tortoises 17. Potamita Trionyx - +Chelonia+ { 18. Marsh tortoises 18. Elodita Emys - { 19. Land tortoises 19. Chersita Testudo - - { 20. Long-tailed 20. Rhamphorhynchi * Rhamphorhynchus - VI. =Flying= { Flying lizards - =Reptiles= { 21. Short-tailed 21. Pterodactyli * Pterodactylus - +Pterosauria+* { Flying lizards - - { 22. Giant dragons 22. Harpagosauria * Megalosaurus - VII. =Dragons= { 23. Elephantine 23. Therosauria * Iguanodon - +Dinosauria+* { dragons - - { 24. Dog-toothed 24. Cynodontia * Dicynodon - VIII. =Beaked= { 25. Toothless 25. Cryptodontia * Udenodon - =Reptiles= { 26. Kangaroo reptiles 26. Hypsosauria * Compsognathus - +Anomodontia+* { - { 27. Bird reptiles 27. Tocornithes * (Tocornis) - - -Of the four orders of reptiles now existing, and which, moreover, have -alone represented the class since the beginning of the tertiary epoch, -that of _Lizards_ (Lacertilia) is probably most closely allied to the -extinct Primary Reptiles, and especially through the monitors already -named. The class of _Serpents_ (Ophidia) developed out of a branch of -the order of lizards, and this probably not until the beginning of the -tertiary epoch. At least we at present only know of fossil remains of -serpents from the tertiary strata. _Crocodiles_ (Crocodilia) existed -much earlier; the Teleosauria and Steneosauria belonging to the class -are found fossil in large quantities even in the Jura; but the still -living alligators are first met with in a fossil state in the chalk and -tertiary strata. The most isolated of the four existing orders of -reptiles consists of the remarkable group of _Tortoises_ (Chelonia); -fossils of these strange animals are first met with in the Jura. In some -characteristics they are allied to Amphibia, in others, to Crocodiles, -and by certain peculiarities even to Birds, so that their true position -in the pedigree of Reptiles is probably far down at the root. The -extraordinary resemblance of their embryos to Birds, manifested even at -later stages of the ontogenesis, is exceedingly striking. - -The four extinct orders of Reptiles show among one another, and, with -the four existing orders just mentioned, such various and complicated -relationships, that in the present state of our knowledge we are obliged -to give up the attempt at establishing their pedigree. The most -deviating and most curious forms are the _Flying Reptiles_ -(Pterosauria); flying lizards, in which the extremely elongated fifth -finger of the hand served to support an enormous flying membrane. They -probably flew about, in the secondary period, much in the same way as -the bats of the present day. The smallest flying lizards were about the -size of a sparrow; the largest, however, with a breadth of wing of more -than sixteen feet, exceeded the largest of our living flying birds in -stretch of wing (condor and albatross). Numerous fossil remains of them, -of the long-tailed Rhamphorhynchia and of the short-tailed Pterodactylae -are found in all the strata of the Jura and Chalk periods, but in these -only. - -Not less remarkable and characteristic of the Mesolithic epoch was the -group of _Dragons_ (Dinosauria, or Pachypoda). These colossal reptiles, -which attained a length of more than fifty feet, are the largest -inhabitants of the land which have ever existed on our globe; they lived -exclusively in the secondary epoch. Most of their remains are found in -the lower cretaceous system, more especially in the Wealden formations -of England. The majority of them were fearful beasts of prey (the -Megalosaurus from twenty to thirty, the Pelorosaurus from forty to fifty -feet in length). The Iguanodon, however, and some others lived on -vegetable food, and probably played a part in the forests of the chalk -period similar to that of the unwieldy but smaller elephants, -hippopotami, and rhinoceroses of the present day. - -The _Beaked Reptiles_ (Anomodontia), likewise also long since extinct, -but of which very many remarkable remains are found in the Trias and -Jura, were perhaps closely related to the Dragons. Their jaws, like -those of most Flying Reptiles and Tortoises, had become changed into a -beak, which either possessed only degenerated rudimentary teeth, or no -teeth at all. In this order, if not in the preceding one, we must look -for the primary parents of the bird class, which we may call Bird -Reptiles (Tocornithes). Probably very closely related to them was the -curious, kangaroo-like Compsognathus from the Jura, which in very -important characteristics already shows an approximation to the -structure of birds. - -The class of _Birds_ (Aves), as already remarked, is so closely allied -to Reptiles in internal structure and by embryonal development, that -they undoubtedly originated out of a branch of this class. Even a glance -at Plates II. and III. will show that the embryos of birds at a time -when they already essentially differ from the embryos of Mammals, are -still scarcely distinguishable from those of Tortoises and other -Reptiles. The cleavage of the yolk is partial in the case of Birds and -Reptiles, in Mammals it is total. The red blood-cells of the former -possess a kernel, those of the latter do not. The hair of Mammals -develops in closed follicles in the skin, but the feathers of birds and -also the scales of reptiles develop in hillocks on the skin. The lower -jaw of the latter is much more complicated than that of Mammals; the -latter do not possess the quadrate bone of the former. Whereas in -Mammals (as in the case of Amphibia) the connection between the skull -and the first neck vertebra is formed by two knobbed joints, or -condyles, in Birds and Reptiles those have become united into a single -condyle. The two last classes may therefore justly be united into one -group as Monocondylia, and contrasted to Mammals, or Dicondylia. - -The deviation of Birds from Reptiles, in any case, first took place in -the mesolithic epoch, and this moreover probably during the Trias. The -oldest fossil remains of birds are found in the upper Jura -(Archaeopteryx). But there existed, even in the Trias period, different -Saurians (Anomodonta) which in many respects seem to form the transition -from the Tocosauria to the primary ancestors of Birds, the hypothetical -Tocornithes. Probably these Tocornithes were scarcely distinguishable -from other beaked lizards in the system, and were closely related to the -kangaroo-like Compsognathus from the Jura of Solenhofen. Huxley classes -the latter with the Dinosauria, and believes them to be the nearest -relations to the Tocornithes. - -The great majority of Birds--in spite of all the variety in the -colouring of their beautiful feathery dress, and in the formation of -their beaks and feet--are of an exceedingly uniform organization, in -much the same way as are the class of insects. The bird form has adapted -itself on all sides to the external conditions of existence, without -having thereby in any way essentially deviated from the strict -hereditary type of its characteristic structure. There are only two -small groups, the feather-tailed birds (Saururae) and those of the -ostrich kind, which differ considerably from the usual type of bird, -namely, from those with keel-shaped breasts (Carinatae), and hence the -whole class may be divided into three sub-classes. - -The first sub-class, the _Reptile-tailed_, or _Feather-tailed Birds_ -(Saururae), are as yet known only through a single, and that an -imperfect, fossil impression, which, however, in being the oldest and -also a very peculiar fossil bird, is of great importance. This fossil is -the Primaeval Griffin, or Archaeopteryx lithographica, of which as yet -only one specimen has been found in the lithographic slate at -Solenhofen, in the Upper Jura system of Bavaria. This remarkable bird -seems on the whole to have been of the size and form of a large raven, -especially as regards the legs, which are in a good state of -preservation; head and breast unfortunately are wanting. The formation -of the wings deviates somewhat from that of other birds, but that of the -tail still more so. In all other birds the tail is very short and -composed of but few short vertebrae; the last of these have grown -together into a thin, bony plate standing perpendicularly, upon which -the rudder-feathers of the tail are attached in the form of a fan. The -Archaeopteryx, however, has a long tail like a lizard, composed of -numerous (20) long thin vertebrae, and on every vertebra are attached -the strong rudder-feathers in twos, so that the whole tail appears -regularly feathered. This same formation of the tail part of the -vertebral column occurs transiently in the embryos of other birds, so -that the tail of the Archaeopteryx evidently represents the original form -of bird-tail inherited from reptiles. Large numbers of similar birds -with lizard-tails probably lived during the middle of the secondary -period; accident has as yet, however, only revealed this one fossil. - -The _Fan-tailed_, or _Keel-breasted birds_ (Carinatae), which form the -second sub-class, comprise all living Birds of the present day, with the -exception of those of the ostrich kind, or Ratitae. They probably -developed out of Feather-tailed Birds during the first half of the -secondary period, namely, in the Jura or Chalk period, by the hinder -tail vertebrae growing together, and by the tail becoming shortened. Only -very few remains of them are known from the secondary period, and these -moreover only out of the last section of it, namely, from the Chalk. -These remains belong to a swimming bird of the albatross species, and a -wading bird like a snipe. All the other fossil remains of birds as yet -known have been found in the tertiary strata. - -The _Bushy-tailed_, or _Ostrich-like Birds_ (Ratitae), also called -_Running Birds_ (Cursores), the third and last sub-class, is now -represented only by a few living species, by the African ostrich with -two toes, the American and Australian ostrich with three toes, by the -Indian cassowary and the four-toed kiwi, or Apteryx, in New Zealand. The -extinct giant birds of Madagascar (AEpyornis) and the New Zealand -Dinornis, which were much larger than the still living ostriches, also -belong to this group. The Birds of the ostrich kind--by giving up the -habit of flying, by the degeneration of the muscles for flying resulting -from this, and of the breast bone which serves as their support, and by -the corresponding stronger development of the hinder legs for -running--have probably arisen out of a branch of the Keel-breasted -birds. But possibly, as Huxley thinks, they may be the nearest relations -of the Dinosauria and of the Reptiles akin to them, especially of the -Compsognathus; at all events, the common primary form of all Birds must -be looked for among the extinct Reptiles. - - - - -CHAPTER XXI. - -PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. - -IV. MAMMALS. - - - The System of Mammals according to Linnaeus and - Blainville.--Three Sub-classes of Mammals (Ornithodelphia, - Didelphia, Monodelphia).--Ornithodelphia, or Monotrema.--Beaked - Animals (Ornithostoma).--Didelphia, or Marsupials.--Herbivorous - and Carnivorous Marsupials.--Monodelphia, or Placentalia - (Placental Animals).--Meaning of the Placenta.--Tuft - Placentalia.--Girdle Placentalia.--Disc - Placentalia.--Non-deciduates, or Indeciduata.--Hoofed - Animals.--Single and Double-hoofed Animals.--Whales.--Toothless - Animals.--Deciduates, or Animals with - Decidua.--Semi-apes.--Gnawing Animals.--Pseudo-hoofed - Animals.--Insectivora.--Beasts of Prey.--Bats.--Apes. - - -There are only a few points in the classification of organisms upon -which naturalists have always agreed. One of these few undisputed points -is the privileged position of the class of Mammals at the head of the -animal kingdom. The reason of this privilege consists partly in the -special interest, also in the various uses and the many pleasures, which -Mammals, more than all other animals, offer to man, and partly in the -circumstance that man himself is a member of this class. For however -differently in other respects man's position in nature and in the system -of animals may have been regarded, yet no naturalist has ever doubted -that man, at least from a purely morphological point of view, belongs -to the class of Mammals. From this there directly follows the -exceedingly important inference that man, by consanguinity also, is a -member of this class of animals, and has historically developed out of -long since extinct forms of Mammals. This circumstance alone justifies -us here in turning our especial attention to the history and the -pedigree of Mammals. Let us, therefore, for this purpose first examine -the groups of this class of animals. - -Older naturalists, especially considering the formation of the jaw and -feet, divided the class of Mammals into a series of from eight to -sixteen orders. The lowest stage of the series was occupied by the -whales, which seemed to differ most from man, who stands at the highest -stage, by their fish-like form of body. Thus Linnaeus distinguished the -following eight orders: (1) Cetae (whales); (2) Belluae (hippopotami and -horses); (3) Pecora (ruminating animals); (4) Glires (gnawing animals -and rhinoceroses); (5) Bestiae (insectivora, marsupials, and various -others); (6) Ferae (beasts of prey); (7) Bruta (toothless animals and -elephants); (8) Primates (bats, semi-apes, apes, and men). Cuvier's -classification, which became the standard of most subsequent zoologists, -did not rise much above that of Linnaeus. Cuvier distinguished the -following eight orders: (1) Cetacea (whales); (2) Ruminantia (ruminating -animals); (3) Pachyderma (hoofed animals, with the exclusion of -ruminating animals); (4) Edentata (animals poor in teeth); (5) Rodentia -(gnawing animals); (6) Carnassia (marsupials, beasts of prey, -insectivora, and bats); (7) Quadrumana (semi-apes and apes); (8) Bimana -(man). - -The most important advance in the classification of Mammals was made as -early as 1816 by the eminent anatomist Blainville, who has already been -mentioned, and who first clearly recognised the three natural main -groups or sub-classes of Mammals, and distinguished them according to -the formation of their generative organs as _Ornithodelphia_, -_Didelphia_, and _Monodelphia_. As this division is now justly -considered by all scientific zoologists to be the best, on account of -solid foundation on the history of development, let us here keep to it -also. - -The first sub-class consists of the _Cloacal Animals_, or _Breastless -animals_, also called _Forked animals_ (Monotrema, or Ornithodelphia). -This class is now represented only by two species of living mammals, -both of which are confined to Australia and the neighbouring island of -Van Diemen's land, namely, the well-known Water Duck-bill -(Ornithorhynchus paradoxus) with the beak of a bird, and the less known -Beaked Mole (Echidna hystrix), resembling a hedgehog. Both of these -curious animals, which are classed in the order of _Beaked Animals_ -(Ornithostoma), are evidently the last surviving remnants of an animal -group formerly rich in forms, which alone represented the Mammalia in -the secondary epoch, and out of which the second sub-class, the -Didelphia, developed later, probably in the Jurassic period. -Unfortunately, we as yet do not know with certainty of any fossil -remains of this most ancient primary group of Mammals, which we will -call _Primary Mammals_ (Promammalia). Yet they possibly comprise the -oldest of all the fossil Mammalia known, namely, the Microlestes -antiquus, of which animals, however, we as yet only know some few small -molar teeth. These have been found in the uppermost strata of the -Trias, in the Keuper, first in Germany (at Degerloch, near Stuttgart, -in 1847), later also in England (at Frome), in 1858. Similar teeth have -lately been found also in the North American Trias, and have been -described as Dromatherium sylvestre. These remarkable teeth, from the -characteristic form of which we can conclude that they belonged to an -insectivorous mammal, are the only remains of mammals as yet found in -the older secondary strata, namely, in the Trias. It is possible, -however, that besides these many of the other mammalian teeth found in -the Jura and Chalk systems, which are still generally ascribed to -Marsupials, in reality belong to Cloacal Animals. This cannot be decided -with certainty owing to the absence of the characteristic soft parts. In -any case, numerous Monotrema, with well-developed teeth and cloaca, must -have preceded the advent of Marsupial animals. - -The designation, "_Cloacal animals_" (Monotrema), has been given to the -Ornithodelphia on account of the cloaca which distinguishes them from -all other Mammals; but which on the other hand makes them agree with -Birds, Reptiles, and Amphibia, in fact, with the lower Vertebrata. The -formation of the cloaca consists in the last portion of the intestinal -canal receiving the mouth of the urogenital apparatus, that is, the -united urinary and genital organs, whereas in all other Mammals -(Didelphia as well Monodelphia) these organs have an opening distinct -from that of the rectum. However, in these latter also the cloaca -formation exists during the first period of their embryonal life, and -the separation of the two openings takes place only at a later date (in -man about the twelfth week of development). The Cloacal animals have -also been called "_Forked animals_," because the collar-bones, by means -of the breast bone, have become united into one piece, similar to the -well-known fork-bone, or merry-thought, in birds. In all other Mammals -the two collar-bones remain separated in front and do not fuse with the -breast bone. Moreover, the coracoid bones are much more strongly -developed in the Cloacal animals than in the other Mammalia, and are -connected with the breast bone. - -In many other characteristics also--especially in the formation of their -internal genital organs, their auricular labyrinth, and their -brain--Beaked animals are more closely allied to the other Vertebrata -than to Mammals, so that some naturalists have been inclined to separate -them from the latter as a special class. However, like all other -Mammals, they bring forth living young ones, which for a time are -nourished with milk from the mother. But whereas in all other Mammals -the milk issues through nipples, or teats, from the mammary glands, -teats are completely wanting in beaked animals, and the milk comes -simply out of a flat, sieve-like, perforated patch of the skin. Hence -they may also be called _Breastless_ or _Teatless animals_ (Amasta). - -The curious formation of the beak in the two still living Beaked -animals, which is connected with the suppression of the teeth, must -evidently not be looked upon as an essential feature of the whole -sub-class of Cloacal animals, but as an accidental character of -adaptation distinguishing the last remnant of the class as much from the -extinct main group, as the formation of a similar toothless snout -distinguishes many toothless animals (for instance, the ant-eater) from -the other placental animals. The unknown, extinct Primary Mammals, or -Promammalia--which lived during the Trias period, and of which the two -still living orders of Beaked animals represent but a single -degenerated branch developed on one side--probably possessed a very -highly developed jaw like the marsupial animals, which developed from -them. - -_Marsupial_, or _Pouched Animals_ (Didelphia, or Marsupialia), the -second of the three sub-classes of Mammals, form in every respect--both -as regards their anatomy and embryology, as well as their genealogy and -history--the transition between the other sub-classes--the Cloacal and -Placental Animals. Numerous representatives of this group still exist, -especially the well-known kangaroos, pouched rats, and pouched dogs; but -on the whole this sub-class, like the preceding one, is evidently -approaching its complete extinction, and the living members of the class -are the last surviving remnants of a large group rich in forms, which -represented the Mammalia during the more recent secondary and the -earlier tertiary periods. The Marsupial Animals probably developed -towards the middle of the Mesolithic epoch (during the Jura) out of a -branch of the Cloacal Animals, and in the beginning of the Tertiary -epoch again, the group of Placental Animals arose out of the Marsupials, -and the latter then succumbed to the former in the struggle for life. -All the fossil remains of Mammals known to us from the Secondary epoch, -belong either exclusively to Marsupials, or partly perhaps to Cloacal -animals. At that time Marsupials seem to have been distributed over the -whole earth; even in Europe (France and England), well-preserved fossil -remains of them have been found. On the other hand, the last off-shoots -of the sub-class now living are confined to a very narrow tract of -distribution, namely, to Australia, the Australasian, and a small part -of the Asiatic Archipelago. There are also a few species still living -in America, but at the present day not a single marsupial animal lives -on the continent of Asia, Africa, or Europe. - -The name of pouched animals is given to the class on account of the -purse-shaped pouch (marsupium) existing in most instances on the -abdominal side of the female animals, in which the mother carries about -her young for a considerable time after their birth. This pouch is -supported by two characteristic marsupial bones, also existing in -Cloacal animals, but not in Placental animals. The young Marsupial -animal is born in a much more imperfect form than the young Placental -animal, and only attains the same degree of development which the latter -possesses directly at its birth, after it has developed in the pouch for -some time. In the case of the giant kangaroo, which attains the height -of a man, the newly born young one, which has been carried in the -maternal womb not much longer than five weeks, is not more than an inch -in length, and only attains its essential development subsequently, in -the pouch of the mother, where it remains about nine months attached to -the nipple of the mammary gland. - -The different divisions generally distinguished as families in the -sub-class of Marsupial animals, deserve in reality the rank of -independent orders, for they differ from one another in manifold -differentiations of the jaw and limbs, in much the same manner, although -not so sharply, as the various orders of Placental animals. In part they -perfectly agree with the latter. It is evident that adaptation to -similar conditions of life has effected entirely coincident or analogous -transformations of the original fundamental form in the two sub-classes -of Marsupials. According to this, about eight orders of Marsupial -animals may be distinguished, the one half of the main group or legion -of which are herbivorous, the other half carnivorous. The oldest fossil -remains of the two legions (if the previously mentioned Microlestes and -the Dromatherium are not included) occur in the Jurassic strata, namely, -in the slates of Stonesfield, near Oxford. The slates belong to the -Bath, or the Lower Oolite formation--strata which lie directly above the -Lias, the oldest Jura formation. (Compare p. 15.) It is true that the -remains of Marsupials found in the slates of Stonesfield, as well as -those which were found later in the Purbeck strata, consist only of -lower jaws. (Compare p. 29.) But fortunately the lower jaw is just one -of the most characteristic parts of the skeleton of Marsupials. For it -is distinguished by a hook-shaped process of the lower corner of the jaw -turning downwards and backwards, which neither occurs in Placental nor -in the (still living) Cloacal animals, and from the existence of this -process on the lower jaws from Stonesfield, we may infer that they -belonged to Marsupials. - - -SYSTEMATIC SURVEY OF CLOACAL AND MARSUPIAL MAMMALIA. - -I. _First Sub-class of Mammalia:_ - -_Forked or Cloacal Animals (Monotrema, or Ornithodelphia)._ - -Mammals with Cloaca, without Placenta, with Marsupial Bones. - - ------------------------------------------------------------------------------------ - I. } - =Primary Mammals= } Unknown extinct Mammalia from the { (Microlestes?) - +Promammalia+ } Trias Period { (Dromatherium?) - - II. } 1. Aquatic beaked 1. Ornithorhynchida { 1. Ornithorhynchus - =Beaked Animals= } animals { paradoxus - +Ornithostoma+ } 2. Terrestrial 2. Echidnida { 2. Echidna hystrix - } beaked animals { - ------------------------------------------------------------------------------------ - II. _Second Sub-class of Mammalia:_ - - _Pouched or Marsupial Animals (Marsupialia, or Didelphia)._ - - Mammals without Cloaca, without Placenta, with Marsupial Bones. - ------------------------------------------------------------------------------------ - _Legions_ | _Orders_ | _Systematic Name_ | _Families of the_ - _of_ | _of_ | _of_ | _Marsupialia._ - _Marsupialia._ | _Marsupialia._ | _the Orders._ | - ------------------------------------------------------------------------------------ - { 1. Hoofed 1. Barypoda { 1. Stereognathida - { Marsupial animals { 2. Nototherida - III. { { 3. Diprotodontia - =Herbivorous= { - =Marsupial= { 2. Kangaroo 2. Macropoda { 4. Plagiaulacida - =Animals= { Marsupial animals { 5. Halmaturida - { (Leaping pouched { 6. Dendrolagida - +Marsupialia+ { animals) - +Botanophaga+ { - { 3. Root-eating 3. Rhizophaga { - { Marsupial animals { - { (Gnawing pouched { 7. Phascolomyida - { animals) { - { - { 4. Fruit eating 4. Carpophaga { - { Marsupial animals { 8. Phascolarctida - { (Climbing pouched { 9. Phalangistida - { animals) { 10. Petaurida - - { 5. Insectivorous 5. Cantharophaga { 11. Thylacotherida - { Marsupial animals { 12. Spalacotherida - { (Primaeval pouched { 13. Myrmecobida - { animals) { 14. Peramelida - IV. { - =Carnivorous= { 6. Marsupial animals 6. Edentula { - =Marsupial= { poor in teeth { - =Animals= { (Pouched animals { 15. Tarsipedina - { with trunks) { - { - { 7. Rapacious marsupial 7. Creophaga { 16. Dasyurida - { animals { 17. Thylacinida - +Marsupialia+ { (Rapacious pouched { 18. Thylacoleonida - +Zoophaga+ { animals) - { - { 8. Ape-footed 8. Pedimana { - { Marsupial animals { 19. Chironectida - { (Pouched animals { 20. Didelphyida - { with hands) - - -SYSTEMATIC SURVEY OF PLACENTAL ANIMALS. - -III. _Third Sub-class of Mammalia:_ - -_Placentalia, or Monodelphia (Placental Animals)._ - -Mammals without Cloaca, with Placenta, without Marsupial Bones. - - - ----------------------------------------------------------------------------------- - _Legions of_ | _Orders of_ | _Sub-orders of_ |_Systematic Name_ - _the_ | _the_ | _the_ | _of_ - _Placental Animals._|_Placental Animals._|_Placental Animals._ | _the Sub-orders._ - ----------------------------------------------------------------------------------- - III. 1. INDECIDUA. _Placental Animals without Decidua._ - ----------------------------------------------------------------------------------- - V. { I. Single-hoofed { 1. Tapirs 1. Tapiromorpha - =Hoofed Animals= { _Perissodactyla_ { 2. Horses 2. Solidungula - +Ungulata+ { - { II. Double-hoofed { 3. Pigs 3. Choeromorpha - { _Artiodactyla_ { 4. Ruminating 4. Ruminantia - - { III. Herbivorous { - VI. { Whales { 5. Sea cows 5. Sirenia - =Whales= { _Phycoceta_ { - +Cetacea+ { - { IV. Carnivorous { 6. Whales 6. Autoceta - { Whales { 7. Zeuglodonta 7. Zeugloceta - { _Sarcoceta_ { - - VII. { V. Digging Animals { 8. Ant-eaters 8. Vermilinguia - =Animals= { _Effodientia_ { 9. Armadilloes 9. Cingulata - =poor in teeth= { - +Edentata+ { VI. Sloths { 10. Giant Sloths 10. Gravigrada - { _Bradypoda_ { 11. Dwarf Sloths 11. Tardigrada - ----------------------------------------------------------------------------------- - III. 2. DECIDUATA. _Placental Animals with Decidua._ - ----------------------------------------------------------------------------------- - VIII. { VII. Rapacious {12. Rapacious land 12. Carnivora - =Placental Animals= { Animals { animals - +Zonoplacentalia+ { _Carnaria_ {13. Rapacious sea 13. Pinnipedia - { { animals - { - { VIII. False-hoofed {14. Hyrax 14. Lamnungia - { Animals {15. Toxodonts 15. Toxodontia - { _Chelophora_ {16. Dinotheria 16. Gonyognatha - { {17. Elephants 17. Proboscidea - - - XI. { IX. Semi-apes {18. Fingered animals 18. Leptodactyla - =Disc Placental= { _Prosimiae_ {19. Flying lemur 19. Ptenopleura - =Animals= { {20. Long-footed 20. Macrotarsi - +Discoplacentalia+ { {21. Short-footed 21. Brachytarsi - { - { X. Gnawing Animals {22. Squirrel species 22. Sciuromorpha - { _Rodentia_ {23. Mouse species 23. Myomorpha - { {24. Porcupine species 24. Hystrichomorpha - { {25. Hare species 25. Lagomorpha - { - { XI. Insect-eating {26. With a coecum 26. Menotyphla - { Animals {27. Without a 27. Lipotyphla - { _Insectivora_ { coecum - { - { XII. Flying Animals{28. Flying foxes 28. Pterocynes - { _Chiroptera_ {29. Bats 29. Nycterides - { - { XIII. Apes { 30. Clawed apes 30. Arctopitheci - { _Simiae_ { 31. Flat-nosed 31. Platyrrhinae - { { 32. Narrow-nosed 32. Catarrhinae - - ---------------------------------------------------------------- - - =Man= - +Homines+ - Elephants | - _Proboscidea_ | Bats - | | _Nycterides_ - Rock Conies | | | Marine animals of prey - _Lamnungia_ | Narrow-nosed | _Pinnipedia_ - | | _Catarrhinae_ | | - | | | Flying foxes | - \------v-----/ Flat-nosed | _Pterocynes_ | - Pseudo-hoofed _Platyrrhinae_ | =Flying Animals= | - _Chelophora_ | | +Chiroptera+ | - | | | | | - | \----v---/ | Land animals of prey - | =Apes= | _Carnivora_ - =Gnawing Animals= +Simiae+ | =Animals of Prey= - +Rodentia+ | | +Carnaria+ - | Fingered animals | Lemurs | | - | _Leptodactyla_ | _Brachytarsi_ | | - True | | | | \-------v---------/ - whales | | | | Insect eaters - _Sarcoceta_ \-----v----/ \---v----/ _Insectivora_ - | | | | - | \------------------v---------------------/ - Sea cows Semi-apes - _Sirenia_ _Prosimiae_ - =Whales= =Deciduous Animals= - +Cetacea+ +Deciduata+ - | Poor in teeth | - =Hoofed Animals= _Edentata_ | - +Ungulata+ | | - | | | - \-------v--------/ | - =Indeciduous= | - +Indeciduata+ | - | | - \-------------v-------------/ - =Placental Animals= - +Placentalia+ - Herbivorous marsupials | Carnivorous marsupials - _Marsupialia botanophaga_ | _Marsupialia zoophaga_ - | | | - \--------------v-----------------/ - =Marsupial= - +Marsupialia+ - Beaked animals | - _Ornithostoma_ | - | | - \---------v--------/ - Primary mammals - _Promammalia_ - =Cloacal Animals= - +Monotrema+ - - -Of _Herbivorous marsupials_ (Botanophaga), only two fossils are as yet -known from the Jura, namely, the Stereognathus ooliticus, from the -slates of Stonesfield (Lower Oolite), and the Plagiaulax Becklesii, from -the middle Purbeck strata (Upper Oolite). But in Australia there are -gigantic fossil remains of extinct herbivorous Marsupials from the -diluvial period (Diprotodon and Nototherium) which were far larger than -the largest of the still living Marsupials. The Diprotodon Australis, -whose skull alone is three feet long, exceeded even the river-horse, or -Hippopotamus, in size and upon the whole resembled it in the unwieldy -and clumsy form of body. This extinct group, which probably corresponded -with the gigantic placental hoofed animals of the present day--the -hippopotami and rhinoceroses--may be called Hoofed Marsupials -(Barypoda). Closely allied to them is the order of kangaroos, or Leaping -Marsupials (Macropoda), which all have seen in zoological gardens. In -their shortened fore legs, their very lengthened hind legs, and very -strong tail, which serves as a jumping pole, they correspond with the -leaping mice in the class of Rodents. Their jaw, however, resembles that -of horses, and their complex stomach that of Ruminants. A third order of -Herbivorous Marsupials corresponds in its jaws to Rodents, and in its -subterranean mode of life, especially, to digging mice. Hence they may -be termed Rodent Marsupials, or root-eating pouched animals -(Rhizophaga). They are now represented only by the Australian wombat -(Phascolomys). A fourth and last order of Herbivorous Marsupials is -formed by the climbing or Fruit-eating Marsupials (Carpophaga), whose -mode of life and structure resembles partly that of squirrels, partly -that of apes (Phalangista, Phascolarctus). - -The second legion of Marsupials, the _Carnivorous Marsupials_ -(Zoophaga), is likewise divided into four main groups or orders. The -most ancient of these is that of the primaeval, or Insectivorous -Marsupials (Cantharophaga). It probably includes the primary forms of -the whole legion, and possibly also those of the whole sub-class. At -least, all the lower jaws from Stonesfield (with the exception of the -Stereognathus) belong to Insectivorous Marsupials, and the still living -Myrmecobius is their nearest relative. But some of those oolitic -Primaeval Marsupials possessed a larger number of teeth than all the -other known mammals, for each half of the lower jaw of the -Thylacotherium contained sixteen teeth (three incisors, one canine -tooth, six pseudo, and six genuine molars). If the upper jaw, which is -unknown, had as many teeth, then the Thylacotherium had no less than -sixty-four teeth, just double the number possessed by man. The Primaeval -Marsupials correspond, on the whole, with the Insectivora among -Placental animals, which order includes hedgehogs, moles, and -shrew-mice. A second order, which has probably developed out of a branch -of the last, consists of the Snouted, or Toothless Marsupials -(Edentula), which resemble the Toothless animals, or Edentata, among the -Placental animals by their tube-shaped snout, their degenerated jaws, -and their corresponding mode of life. On the other hand, the mode of -life and formation of the jaws of Rapacious marsupials (Creophaga) -correspond with those of the genuine Beasts of Prey, or Carnivora, among -Placental animals. This order includes the pouched marten (Dasyurus) and -the pouched wolf (Thylacinus) in Australia. Although the latter attains -to the size of a wolf, it is but a dwarf in comparison with the extinct -Australian pouched lions (Thylacoleo) which were at least as large as a -lion, and possessed huge canine teeth more than two inches in length. -Finally, the eighth and last order is formed by the marsupials with -hands, or the Ape-footed Pouched animals (Pedimana), which live both in -Australia and America. They are frequently kept in zoological gardens, -especially the different species of the genus Didelphys, and are known -by the name of pouched rats, bush rats, or opossums. The thumb on their -hinder feet is opposable to the four other toes, as in a hand, and by -this they are directly allied to the Semi-apes, or Prosimia, among -Placental animals. It is possible that these latter are really next akin -to the marsupials with hands, and that they have developed out of their -long since extinct ancestors. - -It is very difficult to discover the genealogy of Marsupials, and this -more especially because we are but very imperfectly acquainted with the -whole sub-class; and the Marsupials of the present day are evidently -only the last remnants of a group that was at one time rich in forms. It -is possible that Marsupials with hands, those with snouts, as well as -rapacious Marsupials, developed as three diverging branches out of the -common primary group of Primaeval Marsupials. In a similar manner, on the -other hand, the rodent, leaping, and hoofed Marsupials have perhaps -arisen as three diverging branches out of the common herbivorous primary -group, that is, out of the Climbing Marsupials. Climbing and Primaeval -Marsupials might, however, be two diverging branches of the common -primary forms of all Marsupials, that is, of the _Primary Marsupials_ -(Prodidelphia), which originated during the older secondary period out -of Cloacal animals. - -The third and last sub-class of mammals comprises the _Placental -animals_, or _Placentals_ (Monodelphia, or Placentalia). It is by far -the most important, comprehensive, and most perfect of the three -sub-classes; for the class includes all the known mammalia, with the -exception of Marsupials and Beaked animals. Man also belongs to this -sub-class, and has developed out of its lower members. - -Placental animals, as their name indicates, are distinguished from all -other mammals, more especially by the formation of a so called -_placenta_. This is a very peculiar and remarkable organ, which plays -an exceedingly important part in nourishing the young one developing in -the maternal body. The placenta (also called after-birth) is a soft, -spongy, red body, which differs very much in form and size, but which -consists for the most part of an intricate network of veins and blood -vessels. Its importance lies in the exchange of substance between the -nutritive blood of the maternal womb, or uterus, and the body of the -germ, or embryo. (See vol. i. p. 298.) This very important organ is -developed neither in marsupials nor in beaked animals. But placental -animals are also distinguished from these two sub-classes by many other -peculiarities, thus more especially by the absence of marsupial bones, -by the higher development of the internal sexual organs, and by the more -perfect development of the brain, especially of the so-called callous -body or beam (_corpus callosum_), which, as the intermediate commissure, -or transverse bridge, connects the two hemispheres of the large brain -with each other. Placental animals also do not possess the peculiar -hooked process of the lower jaw which characterizes Marsupials. The -following classification (p. 246) of the most important characteristics -of the three sub-classes will best explain how Marsupials, in these -anatomical respects, stand midway between Cloacal and Placental animals. - -Placental animals are more variously differentiated and perfected, and -this, moreover, in a far higher degree, than Marsupials, and they have, -on this account, long since been arranged into a number of orders, -differing principally in the formation of the jaws and feet. But what is -even of more importance than these, is the different development of the -placenta, and the manner of its connection with the maternal uterus. -For in the three lower orders of Placental animals, in Hoofed animals, -Whales, and Toothless animals, the peculiar spongy membrane, which is -called the _deciduous membrane_, or _decidua_, and which connects the -maternal and the foetal portions of the placenta, does _not_ become -developed. This takes place exclusively in the seven higher orders of -Placental animals, and we may, therefore, according to Huxley, class -them in the main group of _Deciduata_, or animals with _decidua_. They -are contrasted with the three first-mentioned legions of indeciduous -animals, or _Indeciduata_. - - - ---------------------------+-------------------+-------------------+------------------- - | _Cloacal Animals_ | _Pouched Animals_ |_Placental Animals_ - _Three Sub-Classes_ | MONOTREMA | MARSUPIALIA | PLACENTALIA - _of_ | _or_ | _or_ | _or_ - _Mammals._ | ORNITHODELPHIA | DIDELPHIA | MONODELPHIA - ---------------------------+-------------------+-------------------+------------------- - 1. Cloaca formation | Constant | Embryonal | Embryonal - | | | - 2. Nipples of the pectoral | Wanting | Existing | Existing - glands, or milk | | | - warts | | | - | | | - 3. Fore collar bones, | United | Not united | Not united - or clavicles, grown | | | - together in the middle, | | | - with the breast bone, | | | - and forming a forked | | | - bone | | | - | | | - 4. Marsupial bones | Existing | Existing | Wanting - | | | - 5. _Corpus callosum_ of | Feebly | Feebly | Strongly developed - the brain | developed | developed | - | | | - 6. Placenta | Wanting | Wanting | Existing - ---------------------------+-------------------+-------------------+------------------- - - -But in the various orders of Placental animals the placenta differs not -only in important internal differences of structure, which are connected -with the absence or the presence of a decidua, but also in the external -form of the placenta itself. In the Indeciduata it consists, in most -cases, of numerous, single, scattered bunches or tufts of vessels, and -hence this group may be called _tufted placental animals_ -(Villiplacentalia). In the Deciduata, however, the single tufts of -vessels are united into a cake, which appears in two different forms. In -the one case it surrounds the embryo in the form of a closed band or -ring, so that only the two poles of the oval egg bladder are free of -tufts; this is the case in animals of prey (Carnaria) and the -pseudo-hoofed animals (Chelophora), which may consequently be comprised -as _girdled-placental animals_ (Zonoplacentalia). In the other -Deciduata, to which man also belongs, the placenta is a simple round -disc, and we therefore call them _disc-placentals_ (Discoplacentalia). -This group includes the five orders of Semi-apes, Gnawing animals, -Insectivora, Bats, and Apes, from the latter of which, in the zoological -system, man cannot be separated. - -It may be considered as quite certain, from reasons based upon their -comparative anatomy and their history of development, that Placental -animals first developed out of Marsupials, and that this very important -development--the first origin of the placenta--probably took place in -the beginning of the tertiary epoch, during the eocene period. But one -of the most difficult questions in the genealogy of animals is the -important consideration whether all Placental animals have arisen out of -one or out of several distinct branches of Marsupials; in other words, -whether the origin of the placenta occurred but once, or several times. - -When, in my General Morphology, I for the first time endeavoured to -establish the pedigree of Mammals, I here, as in most cases, preferred -the monophyletic, or one-rooted, to the polyphyletic, or many-rooted, -hypothesis of descent. I assumed that all Placental animals were derived -from a single form of Marsupial animal, which, for the first time, began -to form a placenta. In this case the Villiplacentals, Zonoplacentals, -and Discoplacentals would perhaps have to be considered as three -diverging branches of the common primary form of Placentals, or it might -also be conceived that the two latter, the Deciduata, had developed only -at a later period out of the Indeciduata, which on their part had arisen -directly out of the Marsupials. However, there are also important -reasons for the alternative; namely, that several groups of Placentals, -differing from the beginning, arose out of several distinct groups of -Marsupials, so that the placenta itself was formed several times -independently. This opinion is maintained by Huxley, the most eminent -English zoologist, and by many others. In this case the Indeciduata and -the Deciduata would perhaps have to be considered as two completely -distinct groups; then the order of Hoofed animals, as the primary group -of the Indeciduata, might be supposed to have originated out of the -Marsupial hoofed animals (Barypoda). Among the Deciduata, on the other -hand, the order of Semi-apes, as the common primary form of the other -orders, might possibly have arisen out of Handed Marsupials (Pedimana). -But it is also conceivable that the Deciduata themselves have arisen out -of several different orders of Marsupials, Animals of Prey out of -Rapacious Marsupials, Gnawing animals out of Gnawing Marsupials, -Semi-apes out of Handed Marsupials, etc. As we do not at present possess -sufficient empiric material to solve this most difficult question, we -must leave it and turn our attention to the history of the different -orders of Placental animals, whose pedigree can often be very accurately -established in detail. - -We must, as already remarked, consider the order of _Hoofed animals_ -(Ungulata) as the primary group of the Indeciduata, or Tuft-placentals; -the two other orders, Whales and Toothless animals, developed out of -them, as two diverging groups, probably only at a later period, by -adaptation to very different modes of life. But it is also possible that -the animals poor in teeth (Edentata) may be of quite a different origin. - -Hoofed animals are in many respects among the most important and the -most interesting Mammals. They distinctly show that a true understanding -of the natural relationship of animals can never be revealed to us -merely by the study of living forms, but in all cases only by an equal -consideration of their extinct and fossil blood-relations and ancestors. -If, as is usually done, only the living Hoofed animals are taken into -consideration, it seems quite natural to divide them into three entirely -distinct orders, namely: (1) Horses, or _Single-hoofed animals_ -(Solidungula, or Equina); (2) Ruminating animals, or _Double-hoofed_ -(Bisulca, or Ruminantia); and (3) Thick-skinned, or _Many-hoofed_ -(Multungula, or Pachyderma). But as soon as the extinct Hoofed animals -of the tertiary period are taken into consideration--of which animals we -possess very numerous and important remains--it is seen that this -division, but more especially the limitation of the Thick-skinned -animals, is completely artificial, and that these three groups are -merely top branches lopped from the pedigree of Hoofed animals, which -are most closely connected by extinct intermediate forms. The one half -of the Thick-skinned animals--rhinoceroses, tapirs, and -palaeotheria--manifest the closest relationships to horses, and have like -them odd-toed feet; whereas the other half of the Thick-skinned -animals--pigs, hippopotami, and anoplotheria--on account of their -double-toed feet are much more closely allied to ruminating animals than -to the former. Hence we must, in the first place, among Hoofed animals -distinguish the two orders of Paired-hoofs and Odd-hoofs, as two natural -groups, which developed as diverging branches out of the old tertiary -primary group of Primary Hoofed animals, or Prochela. - -The order of _Odd-hoofed animals_ (Perissodactyla) comprises those -Ungulata in which the middle (or third) toe of the foot is much more -strongly developed than the others, so that it forms the actual centre -of the hoof. This order includes the very ancient, common, primary group -of all Hoofed animals, that is, the _Primary-hoofed animals_ (Prochela), -which are found in a fossil state in the oldest Eocene strata -(Lophiodon, Coryphodon, Pliolophus). Directly allied to this group is -that branch which is the actual primary form of the Odd-hoofed animals, -namely, the _Palaeotheria_, fossils of which occur in the upper Eocene -and lower Miocene. Out of the Palaeotheria, at a later period, the -rhinoceroses (Nasicornia) and rhinoceros-horses (Elasmotherida) on the -one hand, and the tapirs, lama-tapirs, and primaeval horses, on the -other, developed as two diverging branches. The long since extinct -primaeval horses, or Anchitheria, formed the transition from the -Palaeotheria and tapirs to the Miocene horses, or hipparions, which are -closely allied to the genuine living horses. - -The second main group of Hoofed animals, the order of _Pair-hoofed -animals_ (Artiodactyla), comprises those hoofed animals in which the -middle (third) and fourth toe of the foot are almost equally developed, -so that the space between the two forms the central line of the entire -foot. The order is divided into two sub-orders--the Pig-shaped and the -Cud-chewing, or Ruminating. The _Pig-shaped_ (Choeromorpha) comprise in -the first place the other branch of Primary-Hoofed-animals, the -_Anoplotheria_, which we consider as the common primary form of all -Pair-hoofed animals, or Artiodactyla (Dichobune, etc.). Out of the -Anoplotheria arose, as two diverging branches, the primaeval swine, or -Anthracotheria, on the one hand, forming the transition to swine and -river-horses, and the Xiphodonta on the other hand, forming the -transition to Ruminating animals. The oldest _Ruminating animals_ -(Ruminantia) are the Primaeval Stags, or Dremotheria, out of which, -possibly, the stag-shaped (Elaphia), the hollow-horned (Cavicornia), and -camels (Tylopoda), have developed as three diverging branches. Yet these -latter are, in many respects, more allied to the Odd-hoofs than to the -genuine Pair-hoofs. The accompanying systematic survey on p. 252, will -show how the numerous families of Hoofed animals are grouped, in -correspondence with this genealogical hypothesis. - - - SYSTEMATIC SURVEY - - _Of the Sections and Families of Hoofed Animals, or Ungulata._ - - (N.B. Those families that are extinct are marked with an asterisk.) - - - ----------------+--------------------------------+------------------------+------------------- - _Orders_ | | | - _of_ | _Sections_ | _Families_ | _Systematic Name_ - _Hoofed_ | _of_ | _of_ | _of_ - _animals._ | _Hoofed Animals._ | _Hoofed Animals._ | _the Families._ - ----------------+----------------------------=---+------------------------+------------------- - I. { I. Primary Hoofed { 1. Lophiodonta 1. Lophiodontia* - =Odd-toed= { Animals.* { 2. Pliolophida 2. Pliolophida* - =Hoofed= { _Prochela_ - =Animals= { { 3. Primary 3. Palaeotherida* - { { Odd-hoofs - +Ungulata+ { II. Tapir-shaped { 4. Lama-tapirs 4. Macrauchenida* - { _Tapiromorpha_ { 5. Tapirs 5. Tapirida - +Perissodactyla+ { { 6. Rhinoceroses 6. Nasicornia - { { 7. Rhinoceros-horses 7. Elasmotherida* - { - { III. Single-hoofs { 8. Primaeval 8. Anchitherida* - { _Solidungula_ { horses - { { 9. Horses 9. Equina - - { { 10. Primary 10. Anoplotherida* - { { Pair-hoofs - { { 11. Primaeval 11. Anthracotherida* - { IV. Pig-shaped { pigs - { _Choeromorpha_ { 12. Pigs 12. Setigera - { { 13. River horses 13. Obesa - { { 14. Primaeval 14. Xiphodontia* - { { ruminants - { - { { { {15. Primaeval 15. Dremotherida* - { { { { deer - II. { { A. Stag-shaped { a. {16. Pseudo 16. Tragulida - =Pair-toed= { { _Elaphia_ { { musk deer - =Hoofed= { { { - =Animals= { { { b. {17. Musk deer 17. Moschida - { { { {18. Deer 18. Cervina - +Ungulata+ { { { - { V. { { c. {19. Primaeval 19. Sivatherida* - +Artiodactyla+ { Ruminating { { { giraffes - { animals { { {20. Giraffes 20. Devexa - { _Ruminantia_ { - { { { {21. Primaeval 21. Antilocaprina* - { { { d. { gazelles - { { { {22. Gazelles 22. Antilopina - { { { - { { B. Hollow-horned { {23. Goats 23. Caprina - { { _Caricornia_ { e. {24. Sheep 24. Ovina - { { { {25. Oxen 25. Bovina - { { - { { C. Pad-footed { 26. Lamas 26. Auchenida - { { _Tylopoda_ { 27. Camels 27. Camelida - - ---------------------------------------------------------------- - - Oxen Giraffes - | | - | Sheep Deer | - | | | | - | | | | - \--v---/ Goats \---v---/ Musk deer Horses - | | | | _Equi_ - | | | | | - \---v-----/ Antelopes | | Camels | - | | \----v-----/ and Lamas Intermediate horses - | | Deer-shaped _Tylopoda_ _Hippariones_ - \-----v------/ _Elaphia_ | | - Hollow-horned | | | - _Cavicornia_ | | | - | | | | - | | | Primaeval horses - \-------v--------/ | _Anchitherida_ - Primaeval deer | | - _Dremotherida_ | | - | | =Single Hoofers= - | | +Solidungula+ - \--v------------------/ | - =Ruminating Animals= | - +Ruminantia+ | - Sea-oxen | Tapirs | - _Sirenia_ | _Tapirida_ | - | River-horses | | Lama-tapirs | - | _Obesa_ | | _Macrauchenida_| - | | | | | | - | | Pigs | | | | - \----v-----/ _Setigera_ | \--------------v--/ | - | | | | | - | | | Rhinoceros-horses | | - | | | _Elasmotherida_ | | - | | | | | | - \------v-------/ | | | | - Primaeval pigs | Rhinoceruses | | | - _Anthracotherida_ | _Nasicornia_ | \---v-----/ - | | | | | - | Primaeval ruminants | | | - | _Xiphodontia_ \---v---/ | - | | | | - | | | | - \------v------/ \--------v--------/ - =Primary Pair-hoofs= =Primary Odd-hoofs= - +Anoplotherida+ +Palaeotherida+ - | | - | | - \------------v-------------/ - _Prochela_ - Primary-hoofed-animals - (_Lophiodontia_ and _Pliophida_) - | - | - (Hoofed marsupials? _Barypoda?_) - - -It is probable that the remarkable legion of _Whales_ (Cetacea) -originated out of Hoofed animals, which accustomed themselves -exclusively to an aquatic life, and thereby became transformed into the -shape of fish. Although these animals seem externally very like many -genuine Fish, yet they are, as even Aristotle perceived, genuine -Mammals. By their whole internal structure--in so far as it has not -become changed by adaptation to an aquatic life--they, of all known -Mammals, are most closely allied to Hoofed animals, and more especially -agree with them in the absence of the decidua and in the tufted -placenta. Even at the present day the river-horse (Hippopotamus) -constitutes a kind of transition form to the Sea Cows (Sirenia), and -from this it seems most probable that the extinct primary forms of the -Cetacea are most closely allied to the Sea Cows of the present day, and -that they developed out of Pair-hoofed animals, which were related to -the hippopotamus. Out of the order of _Herbivorous whales_ -(Phycoceta)--to which the sea cows belong, and which accordingly, very -probably, contain the primary forms of the legion--the other order of -_Carnivorous whales_ (Sarcoceta) appears to have developed at a later -period. But Huxley thinks that these latter were of quite a different -origin, and that they arose out of the Carnaria through the Seals. Among -the Sarcoceta, the extinct gigantic Zeuglodonta (Zeugloceta)--whose -fossil skeletons some time ago excited great interest, it being thought -that they were "sea serpents"--are probably only a peculiarly developed -lateral branch of genuine whales (Autoceta), which comprise, besides the -colossal whalebone whales, the cachalot or spermaceti whales, dolphins, -narwhals, porpoises, etc. - -The third legion of the Indeciduata, or Sparsi-placentalia, comprises -the strange group of the animals _poor in teeth_ (Edentata); it is -composed of the two orders of burrowers and sloths. The order of -_Burrowers_ (Effodientia) consists of the two sub-orders of _ant eaters_ -(Vermilinguia), to which the scaled animals also belong, and the _girdle -animals_ (Cingulata), which were formerly represented by the gigantic -Glyptodons. The order of _Sloths_ (Tardigrada) consists of the two -sub-orders of the small, still living _dwarf sloths_ (Bradypoda), and -of the extinct unwieldy _giant sloths_ (Gravigrada). The enormous fossil -remains of these colossal herbivora suggest that the whole legion is -becoming extinct, and that the Edentata of the present day are but a -poor remnant of the mighty order of the diluvial period. The close -relations between the still living South American Edentata and the -extinct gigantic forms which are found beside the latter on the same -part of the globe, made such an impression upon Darwin on his first -visit to South America, that they even then suggested to him the -fundamental idea of the Theory of Descent. (See above, vol. i. p. 134.) -But it is precisely the genealogy of this legion which is most -difficult. The Edentata are perhaps nothing but a peculiarly developed -lateral branch of the Ungulata; but it may also be that their root lies -in quite another direction. - -We now leave the first main group of Placental animals, the Indeciduata, -and turn to the second main group, namely, the Deciduata, or animals -with decidua, which are distinguished from the former by possessing a -deciduous membrane, or decidua, during their embryonal life. We here -meet with a very remarkable small group of animals, for the most part -extinct, and which probably were the old tertiary (or eocene) ancestors -of man. These are the Semi-apes, or Lemurs (Prosimiae); these curious -animals are probably the but little changed descendants of the primaeval -group of Placentalia which we have to consider as the common primary -form of all Deciduata. They have hitherto been classed together in the -same order with Apes which Blumenbach called Quadrumana (four-handed). -However, I regard them as entirely distinct from these, not merely -because they differ from all Apes, much more than do the most different -Apes from one another, but also because they comprise most interesting -transitional forms leading to the other orders of Deciduata. I conclude -from this that the few still living Semi-apes, which moreover differ -very much among one another, are the last surviving remnants of a -primary group now almost extinct, but which was at one time rich in -forms, and out of which all the other Deciduata (possibly with the -single exception of Beasts of Prey, and Pseudo-hoofed animals) have -developed as diverging branches. The old primary group of Semi-apes has -probably developed out of Handed or Ape-footed Marsupials (Pedimana), -which are surprisingly like them in the transformation of their hinder -feet into grasping hands. The primaeval primary forms themselves (which -probably originated in the eocene period) are of course long since -extinct, as are also the greater portion of the transition-forms between -them and all the other orders of Deciduata. However, individual remnants -of the latter are preserved among the Semi-apes of the present day. -Among these, the remarkable Finger-animal of Madagascar (Chiromys -madagascariensis) constitutes the remnant of the group of the -Leptodactyla and the transition to Rodents. The strange flying lemur in -the South Sea and Sunda islands (Galeopithecus), the only remnant of the -group of Pteropleura, forms a perfect intermediate stage between -Semi-apes and Bats. The long-footed Semi-apes (Tarsius, Otolicnus) -constitute the last remnant of that primary branch (Macrotarsi) out of -which the Insectivora developed. The short-footed forms (Brachytarsi) -are the medium of connection between them and genuine Apes. The -Short-footed Semi-apes comprise the long-tailed Lemur, the short-tailed -Lichanotus, and the Stenops, the latter of which seems to be very -closely allied to the probable ancestors of man among the Semi-apes. The -short-footed as well as the long-footed Prosimiae live widely distributed -over the islands of southern Asia and Africa, more especially in -Madagascar; some live also on the continent of Africa. No Semi-ape, -either living or in a fossil state, has as yet been found in America. -They all lead a solitary, nocturnal kind of life, and climb about on -trees. (Compare vol. i. p. 361.) - -Among the six remaining orders of Deciduata, all of which are probably -derived from long since extinct Semi-apes, the order of _Gnawing -animals_ (Rodentia), which is rich in forms, has remained at the lowest -stage. Among these the _squirrel-like_ animals (Sciuromorpha) stand -nearest akin to the Pedimanous Marsupials. Out of this primary group the -_mouse-like_ animals (Myomorpha) and the _porcupine-like_ animals -(Hystricomorpha) developed probably as two diverging branches, the -former of which are directly connected with the squirrel-like animals, -by the eocene Myoxida, the latter by the eocene Psammoryctida. The -fourth sub-order, the _hare-like_ animals (Lagomorpha), probably -developed only at a later period out of one of the other three -sub-orders. - -Very closely allied to the Rodentia is the remarkable order of -_Pseudo-hoofed animals_ (Chelophora). Of these there now live but two -genera, indigenous to Asia and Africa, namely, Elephants (Elephas), and -Rock Conies (Hyrax). Both have hitherto generally been classed among -real Hoofed animals, or Ungulata, with which they agree in the formation -of the feet. But an identical transformation of nails or claws into -hoofs occurs also in genuine Rodentia and in certain hoofed Rodentia -(Subungulata) which live exclusively in South America. Beside smaller -forms (for example, guinea pigs and gold hares) the Subungulata also -include the largest of all Rodentia, namely, the Capybara Rats, which -are about four feet in length. The Rock Conies, which are externally -very nearly akin to Rodents, especially to the hoofed Rodents, were -formerly classed among Rodentia by some celebrated zoologists, as an -especial sub-class (Lamnungia). Elephants, on the other hand, when not -classed among Hoofed animals, were generally considered as the -representatives of a special order which were called Trunked animals -(Proboscidea). But the formation of the placentas of Elephants and of -Hyrax agree in a remarkable manner, and are entirely distinct from those -of Hoofed animals. These latter never possess a decidua, whereas -Elephants and Hyrax are genuine Deciduata. Their placenta is indeed not -of the form of a disc, but of a girdle, as in the case of Animals of -Prey; it is very possible that the girdle-shaped placenta is but a -secondary development of the discoplacenta. Thus, then, it might be -thought that the Pseudo-hoofed animals have developed out of a branch of -the Rodentia, and in a similar manner perhaps the Carnivora out of a -branch of the Insectivora. At all events, Elephants and Hyrax in many -respects, especially in the formation of important skeletal parts, of -the limbs, etc., are more closely allied to the Rodentia, and more -especially to hoofed Rodentia, than to genuine Hoofed animals. Moreover -several extinct forms, especially the remarkable South American -Arrow-toothed animals (Toxodontia), stand in many respects midway -between Elephants and Rodentia. That the still living Elephants and -Hyrax are but the last survivors of a group of Pseudo-hoofed animals, -which was once rich in forms, is proved not only by the very numerous -fossil species of Elephants and Mastodon (some of which are even larger, -others also much smaller than the Elephants of the present day), but -also by the remarkable miocene _Dinotheria_ (Gonyognatha), between which -and their next kindred, the Elephants, there must be a long series of -unknown connecting intermediate forms. Taking all things into -consideration, the most probable hypothesis which can be established at -present as to the origin and the relationship of Elephants, Dinotheria, -Toxodon, and Hyrax is, that they are the last survivors of a group of -Pseudo-hoofed animals rich in forms, which developed out of the -Rodentia, and probably out of relatives of the Subungulata. - -The order of _Insect Eaters_ (Insectivora) is a very ancient group, and -is next akin to the common extinct primary form of the Deciduata, as -well as to the Semi-apes of the present day. It has probably developed -out of Semi-apes which were closely allied to the Long-footed Lemurs -(Macrotarsi) of the present day. It is separated into two orders, -Menotyphla and Lipotyphla; the Menotyphla are probably the older of the -two, and are distinguished from the Lipotyphla by possessing an -intestinal coecum, or typhlon. The Menotyphla include the climbing -Tupajas of the Sunda Isles, and the leaping Macroscelides of Africa. The -Lipotyphla are represented in our country by shrew mice, moles, and -hedgehogs. The Insectivora, in the formation of their jaws and their -mode of life, are nearly akin to Carnivora, but are, on the other hand, -by their discoplacentas and by their large seminal vesicles, allied to -Rodents. - -It is probable that the order of _Rapacious animals_ (Carnaria) -developed out of a long since extinct branch of Insectivora, at the -beginning of the Eocene period. It is a natural group, very rich in -forms, but still of very uniform organization. The Rapacious animals are -sometimes also called Girdle-placentals (Zonoplacentals), although the -Pseudo-hoofed animals (Chelophora), in the same way, also deserve this -designation. But as the latter, in other respects, are more closely -allied to the Rodentia than to Carnaria, we have already discussed them -in connection with the former. Animals of prey are divided into two, -externally very different, but internally very closely related, -sub-orders, namely, Land animals of prey and Marine animals of prey. The -_Land animals of prey_ (Carnivora) comprise bears, dogs, cats, etc., -whose pedigree can be approximately guessed at by means of many extinct -intermediate forms. The _Marine animals of prey_, or _Seals_ -(Pinnipedia), comprise sea bears, sea dogs, sea lions, and walruses. -Although marine animals of prey appear externally very unlike land -animals of prey, yet by their internal structure, their jaw and their -peculiar girdle-shaped placenta, they are very nearly akin to them, and -have evidently originated out of a branch of them, probably out of a -kind of weasel (Mustelina). Even at the present day the fish otters -(Lutra), and still more so the sea otters (Enhydris), present a direct -form of transition to Seals, and clearly show how the bodies of land -Carnivora are transformed into the shape of a Seal, by adaptation to an -aquatic life, and how the steering fins of marine rapacious animals have -arisen out of the legs of the former. The latter consequently stand in -the same relation to the former as do the Whales to Hoofed animals -among the Indeciduata. In the same way as the river-horse at present -stands midway between the extreme branches of oxen and sea oxen, the sea -otter still forms a surviving intermediate stage between the widely -separated branches of dogs and sea dogs. In both cases the complete -transformation of the external form, consequent upon adaptation to -entirely different conditions of life, has not been able to efface the -solid foundation of the inherited internal peculiarities. - -According to Huxley's opinion, which has already been quoted, only the -Herbivorous Whales (Sirenia) are derived from Hoofed animals; on the -other hand, the Carnivorous Cetacea (Sarcoceta) are derived from the -marine animals of prey; the Zeuglodonts would form a transition between -the two latter. But in this case it would be difficult to understand the -close anatomical relations which exist between the Herbivorous and -Carnivorous Cetacea. The strange peculiarities in the internal and -external structure which so strikingly distinguish the two groups from -all other mammals would then have to be regarded only as _analogies_ -(caused by the same kinds of adaptation), not as _homologies_ -(transmitted from a common primary form). The latter, however, strikes -me as being by far the more probable, and hence I have left all the -Cetacea among the Indeciduata as one group of kindred origin. - -The remarkable order of _Flying Mammals_, or _Bats_ (Chiroptera), stands -near to the Carnaria as well as to the Insectivora. It has become -strikingly transformed by adaptation to a flying mode of life, just as -marine animals of prey have become modified by adaptation to a swimming -mode of life. This order probably also originated out of the Semi-apes, -with which it is even at present closely allied, through the flying -lemurs (Galeopithecus). Of the two orders of flying animals, the -insect-eating forms, or _flying mice_ (Nycterides), probably developed -out of those eating fruits, or _flying foxes_ (Pterocynes); for the -latter are, in many ways, more closely allied to Semi-apes than are the -former. - -We have now still to discuss the genuine Apes (Simiae) as the last order -of Mammals; but as, according to the zoological system, the human race -belongs to this order, and as it undoubtedly developed historically out -of a branch of this order, we shall devote a special chapter to a more -careful examination of its pedigree and history. - - - - -CHAPTER XXII. - -ORIGIN AND PEDIGREE OF MAN. - - - The Application of the Theory of Descent to Man.--Its Immense - Importance and Logical Necessity.--Man's Position in the Natural - System of Animals, among Disco-placental Animals.--Incorrect - Separation of the Bimana and Quadrumana.--Correct Separation of - Semi-apes from Apes.--Man's Position in the Order of - Apes.--Narrow-nosed Apes (of the Old World) and Flat-nosed Apes - (of America).--Difference of the two Groups.--Origin of Man from - Narrow-nosed Apes.--Human Apes, or Anthropoides.--African Human - Apes (Gorilla and Chimpanzee).--Asiatic Human Apes (Orang and - Gibbon).--Comparison between the different Human Apes and the - different Races of Men.--Survey of the Series of the Progenitors - of Man.--Invertebrate Progenitors (Prochordata) and Vertebrate - Progenitors. - - -Of all the individual questions answered by the Theory of Descent, of -all the special inferences drawn from it, there is none of such -importance as the application of this doctrine to Man himself. As I -remarked at the beginning of this treatise, the inexorable necessity of -the strictest logic forces us to draw the special deductive conclusion -from the general inductive law of the theory, that Man has developed -gradually, and step by step, out of the lower Vertebrata, and more -immediately out of Ape-like Mammals. That this doctrine is an -inseparable part of the Theory of Descent, and hence also of the -universal Theory of Development in general, is recognized by all -thoughtful adherents of the theory, as well as by all its opponents who -reason logically. - -But if the doctrine be true, then the recognition of the animal origin -and pedigree of the human race will necessarily affect more deeply than -any other progress of the human mind the views we form of all human -relations, and the aims of all human science. It must sooner or later -produce a complete revolution in the conception entertained by man of -the entire universe. I am firmly convinced that in future this immense -advance in our knowledge will be regarded as the beginning of a new -period of the development of Mankind. It can only be compared to the -discovery made by Copernicus, who was the first who ventured distinctly -to express the opinion, that it was not the sun which moved round the -earth, but the earth round the sun. Just as the _geocentric conception_ -of the universe--namely, the false opinion that the earth was the centre -of the universe, and that all its other portions revolved round the -earth--was overthrown by the system of the universe established by -Copernicus and his followers, so the _anthropocentric conception_ of the -universe--the vain delusion that Man is the centre of terrestrial -nature, and that its whole aim is merely to serve him--is overthrown by -the application (attempted long since by Lamarck) of the theory of -descent to Man. As Copernicus' system of the universe was mechanically -established by Newton's theory of gravitation, we see Lamarck's theory -of descent attain its causal establishment by Darwin's theory of -selection. This comparison, which is very interesting in many respects, -I have discussed in detail elsewhere. - -In order to carry out this extremely important application of the Theory -of Descent to man, with the necessary impartiality and objectivity, I -must above all beg the reader (at least for a short time) to lay aside -all traditional and customary ideas on the "Creation of Man," and to -divest himself of the deep-rooted prejudices concerning it, which are -implanted in the mind in earliest youth. If he fail to do this, he -cannot objectively estimate the weight of the scientific arguments which -I shall bring forward in favour of the animal derivation of Man, that -is, of his origin out of Ape-like Mammals. We cannot here do better than -imagine ourselves with Huxley to be the inhabitants of another planet, -who, taking the opportunity of a scientific journey through the -universe, have arrived upon the earth and have there met with a peculiar -two-legged mammal called Man, diffused over the whole earth in great -numbers. In order to examine him zoologically, we should pack a number -of the individuals of different ages and from different lands (as we -should do with the other animals collected on the earth) into large -vessels filled with spirits of wine, and on our return to our own planet -we should commence the comparative anatomy of all these terrestrial -animals quite objectively. As we should have no personal interest in -Man, in a creature so entirely different from ourselves, we should -examine and criticise him as impartially and objectively as we should -the other terrestrial animals. In doing this we should, of course, in -the first place refrain from all conjectures and speculations on the -nature of his soul, or on the spiritual side of his nature, as it is -usually called. We should occupy ourselves solely with his bodily -structure, and with that natural conception of it which is offered by -the history of his individual development. - -It is evident that in order correctly to determine Man's position among -the other terrestrial organisms we must, in the first place, follow the -guidance of the natural system. We must endeavour to determine the -position which belongs to Man in the natural system of animals as -accurately and distinctly as possible. We shall then, if in fact the -theory of descent be correct, be able from his position in the system to -determine the real primary relationship, and the degree of consanguinity -connecting Man with the animals most like him. The hypothetical pedigree -of the human race will then follow naturally as the final result of this -anatomical and systematic inquiry. - -Now if, by means of comparative anatomy and ontogeny, we seek for man's -position in that Natural System of animals which formed the subject of -the last two chapters, the incontrovertible fact will at once present -itself to us, that man belongs to the tribe, or phylum, of the -Vertebrata. Every one of the characteristics, which so strikingly -distinguish all the Vertebrata from all Invertebrata, is possessed by -him. It has also never been doubted that of all the Vertebrata the -Mammals are most closely allied to Man, and that he possesses all the -characteristic features distinguishing them from all other Vertebrata. -If then we further carefully examine the three different main groups or -sub-classes of Mammals--the inter-connections of which were discussed in -our last chapter--there cannot be the slightest doubt that Man belongs -to the Placentals, and shares with all other Placentals, the important -characteristics which distinguish them from Marsupials and from -Cloacals. Finally, of the two main groups of placental Mammals, the -Deciduata and the Indeciduata, the group of Deciduata doubtless includes -Man. For the human embryo is developed with a genuine decidua, and is -thus absolutely distinguished from all the Indeciduata. Among the -Deciduata we distinguish two legions, the Zonoplacentalia, with -girdle-shaped placenta (Beasts of Prey and Pseudo-hoofed animals), and -the Discoplacentalia, with disc-shaped placenta (all the remaining -Deciduata). Man possesses a disc-shaped placenta, like all -Discoplacentalia; and thus our next question must be, What is man's -position in this group? - -In the last chapter we distinguished the following five orders of -Discoplacentalia: (1) Semi-apes; (2) Rodents; (3) Insectivora; (4) Bats; -(5) Apes. The last of these five orders, that of Apes, is, as every one -knows, in every bodily feature far more closely allied to Man than the -four others. Hence the only remaining question now is, whether, in the -system of animals, Man is to be directly classed in the order of genuine -Apes, or whether he is to be considered as the representative of a -special sixth order of Discoplacentalia, allied to, but more advanced -than, that of the Apes. - -Linnaeus in his system classed Man in the same order with genuine Apes, -Semi-apes, and Bats, which he called _Primates_; that is, lords, as it -were the highest dignitaries of the animal kingdom. But Blumenbach, of -Goettingen, separated Man as a special order, under the name of _Bimana_, -or two-handed, and contrasted him with the Apes and Semi-apes under the -name of _Quadrumana_, or four-handed. This classification was also -adopted by Cuvier and, consequently, by most subsequent zoologists. It -was not until 1863 that Huxley, in his excellent work, the "Evidence as -to Man's Place in Nature,"(26) showed that this classification was based -upon erroneous ideas, and that the so-called "four-handed" Apes and -Semi-apes are "two-handed" as much as man is himself. The difference -between the foot and hand does not consist in the _physiological_ -peculiarity that the first digit or thumb is opposable to the four other -digits or fingers in the hand, and is not so in the foot, for there are -wild tribes of men who can oppose the first or large toe to the other -four, just as if it were a thumb. They can therefore use their "grasping -foot" as well as a so-called "hinder hand," like Apes. The Chinese -boatmen row with this hinder hand, the Bengal workmen weave with it. The -Negro, in whom the big toe is especially strong and freely moveable, -when climbing seizes hold of the branches of the trees with it, just -like the "four-handed" Apes. Nay, even the newly born children of the -most highly developed races of men, during the first months of their -life, grasp as easily with the "hinder hand" as with the "fore hand," -and hold a spoon placed in its clutch as firmly with their big toe as -with the thumb! On the other hand, among the higher Apes, especially the -gorilla, hand and foot are differentiated as in man. (Compare Plate IV.) - -The essential difference between hand and foot is therefore not -physiological, but _morphological_, and is determined by the -characteristic structure of the bony skeleton and of the muscles -attached to it. The ankle-bones differ from the wrist-bones in -arrangement, and the foot possesses three special muscles not existing -in the hand (a short flexor muscle, a short extensor muscle, and a long -fibular muscle). In all these respects, Apes and Semi-apes entirely -agree with man, and hence it was quite erroneous to separate him from -them as a special order on account of the stronger differentiation of -his hand and foot. It is the same also with all the other structural -features by means of which it was attempted to distinguish Man from -Apes; for example, the relative length of the limbs, the structure of -the skull, of the brain, etc. In all these respects, without exception, -the differences between Man and the higher Apes are less than the -corresponding differences between the higher and the lower Apes. Hence -Huxley, for reasons based on the most careful and most accurate -anatomical comparisons, arrives at the extremely important -conclusion--"Thus, whatever system of organs be studied, the comparison -of their modifications in the Ape series leads to one and the same -result, that the structural differences which separate Man from the -Gorilla and Chimpanzee are not so great as those which separate the -Gorilla from the lower Apes." In accordance with this, Huxley, strictly -following the demands of logic, classes Man, Apes, and Semi-apes in a -single order, _Primates_, and divides it into the following seven -families, which are of almost equal systematic value: (1) Anthropini -(Man); (2) Catarrhini (genuine Apes of the Old World); (3) Platyrrhini -(genuine American Apes); (4) Arctopitheci (American clawed Apes); (5) -Lemurini (short-footed and long-footed Semi-apes, p. 255); (6) -Chiromyini (p. 256); (7) Galeopithecini (Flying Lemurs, p. 256). - - -SYSTEMATIC SURVEY - -_Of the Families and Genera of Apes._ - - - -----------------+------------------------+---------------------+------------------ - _Sections_ | _Families_ | _Genera_ | _Systematic Name_ - _of_ | _of_ | _of_ | _of_ - _Apes._ | _Apes._ | _Apes._ | _the Genera._ - -----------------+------------------------+---------------------+------------------ - I. APES OF THE NEW WORLD (+Hesperopitheci+), OR FLAT-NOSED APES (+Platyrrhini+). - ----------------------------------------------------------------------------------- - A. =Platyrrhini= { I. Silky apes { 1. Brush ape 1. Midas - =with claws= { _Hapalida_ { 2. Lion ape 2. Jacchus - { - +Arctopitheci+ { - - { II. Flat-nosed, { 3. Squirrel ape 3. Chrysothrix - { without prehensile { 4. Leaping ape 4. Callithrix - B. =Platyrrhini= { tail { 5. Nocturnal ape 5. Nyctipithecus - =with blunt= { _Aphyocerca_ { 6. Tail ape 6. Pithecia - =nails= { - { III. Flat-nosed, { 7. Rolling ape 7. Cebus - +Dysmopitheci+ { with prehensile { 8. Climbing ape 8. Ateles - { tail { 9. Woolly ape 9. Lagothrix - { _Labidocerca_ { 10. Howling ape 10. Mycetes - ---------------------------------------------------------------------------------- - II. APES OF THE OLD WORLD (+Heopitheci+), OR NARROW-NOSED APES (+Catarrhini+). - ---------------------------------------------------------------------------------- - { IV. Tailed Catarrhini, { - { with { 11. Pavian 11. Cynocephalus - C. =Tailed= { cheek-pouches { 12. Macaque 12. Innus - =Catarrhini= { _Ascoparea_ { 13. Sea cat 13. Cercopithecus - { - +Menocerca+ { V. Tailed Catarrhini, { - { without { 14. Holy ape 14. Semnopithecus - { cheek-pouches { 15. Short ape 15. Colobus - { _Anasca_ { 16. Nose ape 16. Nasalis - - { { 17. Gibbon 17. Hylobates - { VI. Human apes { 18. Orang-Outan 18. Satyrus - D. =Tailless= { _Anthropoides_ { 19. Chimpanzee 19. Engeco - =Catarrhini= { { 20. Gorilla 20. Gorilla - { - +Lipocerca+ { VII. Men { 21. Ape-like man, 21. Pithecanthropus - { _Erecti_ { or speechless man (Alalus) - { (_Anthropi_) { 22. Talking man 22. Homo - - ---------------------------------------------------------------- - - Straight-haired men - _Lissotrichi_ - | - Woolly-haired men | - _Ulotrichi_ | - | | - | | - \-------------v-------------/ - Speechless men (_Alali_), or - Ape-like men (_Pithecanthropi_) - | - Gorilla | - _Gorilla_ | Orang - Chimpanzee | | _Satyrus_ - _Engeco_ | | | Gibbon - | | | | _Hylobates_ - | | | | | - \------v------/ | | | - African \-------v--------/ - Man-like Apes Asiatic - | Man-like Apes - | | - \----------v-----------/ - =Man-like Apes= Nose apes - +Anthropoides+ _Nasalis_ - | | - Silk apes | Tall apes | - _Arctopitheci_ | _Semnopithecus_ | - | Clutch-tails | | | - | _Labidocerca_ | | | - | | | \-v----------/ - | | | Sea cat | Pavian - \-----v-------/ | _Cercopithecus_ | _Cynocephalus_ - Flap-tails | | | | - _Aphyocerca_ | | | | - \--------------v--------------/ - =Flat-nosed Apes= Tailed Narrow-nosed apes - +Platyrrhini+ _Catarrhina menocerca_ - | =Narrow-nosed= - | +Catarrhini+ - | | - | | - \--------------v---------------/ - =Apes= - +Simiae+ - | - | - Semi-apes - _Prosimiae_ - - -If we wish to arrive at a natural system, and consequently at the -pedigree of the Primates, we must go a step further still, and entirely -separate the Semi-apes, or Prosimiae, (Huxley's last three families), -from Genuine Apes, or Simiae (the first four families). For, as I have -already shown in my General Morphology, and explained in the last -chapter, the Semi-apes differ in many and important respects from -Genuine Apes, and in their individual forms are more closely allied to -the various other orders of Discoplacentalia. Hence the Semi-apes must -probably be considered as the remnants of the common primary group, out -of which the other orders of Discoplacentalia, and, it may be, all -Deciduata, have developed as two diverging branches. (Gen. Morph. ii. -pp. 148 and 153.) But man cannot be separated from the order of Genuine -Apes, or Simiae, as he is in every respect more closely allied to the -higher Genuine Apes than the latter are to the lower Genuine Apes. - -_Genuine Apes_ (Simiae) are universally divided into two perfectly -natural groups, namely, the Apes of the New World, or American Apes, and -the Apes of the Old World, which are indigenous to Asia and Africa, and -which formerly also existed in Europe. These two classes differ -principally in the formation of the nose, and they have been named -accordingly. American Apes have flat noses, so that the nostrils are in -front, not below; hence they are called _Flat Noses_ (Platyrrhini). On -the other hand, the Apes of the Old World have a narrow cartilaginous -bridge, and the nostrils turned downwards, as in man; they are, -therefore, called _Narrow Noses_ (Catarrhini). Further, the jaw, which -plays an important part in the classification of Mammals, is essentially -distinct in these two groups. All Catarrhinae, or Apes of the Old World, -have exactly the same jaws as Man, namely, in each jaw four incisors -above and below, then on each side a canine tooth and five cheek teeth, -of which two are pre-molars and three molars, altogether thirty-two -teeth. But all Apes of the New World, all Platyrrhini, have four more -cheek teeth, namely, three pre-molars and three molars on each side, -above and below: they consequently possess thirty-six teeth. Only one -small group forms an exception to this rule, namely, the _Arctopitheci_, -or _Clawed Apes_, in whom the third molar has degenerated, and they -accordingly have on each half of their jaw three pre-molars and two -molars. They also differ from the other Platyrrhini by having claws on -the fingers of their hands and the toes of their feet, not nails like -Man and the other Apes. This small group of South American Apes, which -includes among others the well-known pretty little Midas-monkey and the -Jacchus, must probably be considered only as a peculiarly developed -lateral branch of the Platyrrhini. - -Now, if we ask what evidence can be drawn, as to the pedigree of Apes, -from the above facts, we must conclude that all the Apes of the New -World have developed out of one tribe, for they all possess the -characteristic jaw and the nasal formation of the Platyrrhini. In like -manner it follows that all the Apes of the Old World must be derived -from one and the same common primary form, which possessed the same -formation of nose and jaw as all the still living Catarrhini. Further, -it can scarcely be doubted that the Apes of the New World, taken as an -entire tribe, are either derived from those of the Old World, or (to -express it more vaguely and cautiously) both are diverging branches of -one and the same tribe of Apes. We also arrive at the exceedingly -important conclusion--which is of the utmost significance in regard to -Man's distribution on the earth's surface--that Man _has developed out -of the Catarrhini_. For we cannot discover a zoological character -distinguishing him in a higher degree from the allied Apes of the Old -World than that in which the most divergent forms of this group are -distinguished from one another. This is the important result of Huxley's -careful anatomical examination of the question, and it cannot be too -highly estimated. The anatomical differences between Man and the most -human-like Catarrhini (Orang, Gorilla, Chimpanzee) are in every respect -less than the anatomical differences between the latter and the lowest -stages of Catarrhini, more especially the Dog-like Baboon. This -exceedingly important conclusion is the result of an impartial -anatomical comparison of the different forms of Catarrhini. - -If, therefore, we recognise the natural system of animals as the guide -to our speculations, and establish upon it our pedigree, we must -necessarily come to the conclusion that _the human race is a small -branch of the group of Catarrhini, and has developed out of long since -extinct Apes of this group in the Old World_. Some adherents of the -Theory of Descent have thought that the American races of Men have -developed, independently of those of the Old World, out of American -Apes. I consider this hypothesis to be quite erroneous, for the complete -agreement of all mankind with the Catarrhini, in regard to the -characteristic formation of the nose and jaws, distinctly proves that -they are of the same origin, and that they developed out of a common -root after the Platyrrhini, or American Apes, had already branched off -from them. The primaeval inhabitants of America, as is proved by numerous -ethnographical facts, immigrated from Asia, and partly perhaps from -Polynesia (or even from Europe). - -There still exist great difficulties in establishing an accurate -pedigree of the Human Race; this only can we further assert, that the -nearest progenitors of man were tail-less Catarrhini (Lipocerca), -resembling the still living Man-like Apes. These evidently developed at -a late period out of tailed Catarrhini (Menocerca), the original form of -Ape. Of those tail-less Catarrhini, which are now frequently called -Man-like Apes, or Anthropoides, there still exist four different genera -containing about a dozen different species. - -The largest Man-like Ape is the famous _Gorilla_ (called Gorilla engena, -or Pongo gorilla), which is indigenous to the tropics of western Africa, -and was first discovered by the missionary, Dr. Savage, in 1847, on the -banks of the river Gaboon. Its nearest relative is the _Chimpanzee_ -(Engeco troglodytes, or Pongo troglodytes), also indigenous to western -Africa, but considerably smaller than the Gorilla, which surpasses man -in size and strength. The third of the three large Man-like Apes is the -_Orang_, or _Orang Outang_, indigenous to Borneo and the other Sunda -Islands, of which two kindred species have recently been distinguished, -namely, the large Orang (Satyrus orang, or Pithecus satyrus) and the -small Orang (Satyrus morio, or Pithecus morio). Lastly, there still -exists in southern Asia the genus _Gibbon_ (Hylobates), of which from -four to eight different species are distinguished. They are considerably -smaller than the three first-named Anthropoides, and in most -characteristics differ more from Man. - -The tail-less Man-like Apes--especially since we have become more -intimately acquainted with the Gorilla, and its connection with Man by -the application of the Theory of Descent--have excited such universal -interest, and called forth such a flood of writings, that there is no -occasion for me here to enter into any detail about them. The reader -will find their relations to Man fully discussed in the excellent works -of Huxley,(26) Carl Vogt,(27) Buechner,(43) and Rolle.(28) I shall -therefore confine myself to stating the most important general -conclusion resulting from their thorough comparison with Man, namely, -that each one of the four Man-like Apes stands nearer to Man in one or -several respects than the rest, but that no one of them can in every -respect be called absolutely the most like Man. The Orang stands nearest -to Man in regard to the formation of the brain, the Chimpanzee in -important characteristics in the formation of the skull, the Gorilla in -the development of the feet and hands, and, lastly, the Gibbon in the -formation of the thorax. - -Thus, from a careful examination of the comparative anatomy of the -Anthropoides, we obtain a similar result to that obtained by Weisbach, -from a statistical classification and a thoughtful comparison of the -very numerous and careful measurements which Scherzer and Schwarz made -of the different races of Men during their voyage in the Austrian -frigate _Novara_ round the earth. Weisbach comprises the final result of -his investigations in the following words: "_The ape-like -characteristics of Man_ are by no means concentrated in one or another -race, but are distributed in particular parts of the body, among the -different races, in such a manner that each is endowed with some -heirloom of this relationship--one race more so, another less, and even -we Europeans cannot claim to be entirely free from evidences of this -relationship."[5] - -I must here also point out, what in fact is self-evident, that not one -of all the still living Apes, and consequently not one of the so-called -Man-like Apes, can be the progenitor of the Human Race. This opinion, in -fact, has never been maintained by thoughtful adherents of the Theory of -Descent, but it has been assigned to them by their thoughtless -opponents. The Ape-like progenitors of the Human Race are long since -extinct. We may possibly still find their fossil bones in the tertiary -rocks of southern Asia or Africa. In any case they will, in the -zoological system, have to be classed in the group of _tail-less -Narrow-nosed Apes_ (Catarrhini Lipocerci, or Anthropoides). - -The genealogical hypotheses, to which we have thus far been led by the -application of the Theory of Descent to Man, present themselves to every -clearly and logically reasoning person as the direct results from the -facts of comparative anatomy, ontogeny, and palaeontology. Of course our -phylogeny can indicate only in a very general way the outlines of the -human pedigree. Phylogeny is the more in danger of becoming erroneous -the more rigorously it is applied in detail to special animal forms -known to us. However, we can, even now, with approximate certainty -distinguish at least the following twenty-two stages of the ancestors of -Man. Fourteen of these stages belong to the Vertebrata, and eight to the -Invertebrate ancestors of Man (Prochordata.) - - -THE CHAIN OF THE ANIMAL ANCESTORS, OR THE SERIES OF THE PROGENITORS, OF -MAN. - -(Comp. Ch. XX., XXI.; Plate XIV. and p. 22.) - -FIRST HALF OF THE SERIES OF THE ANCESTORS OF MAN. - -INVERTEBRATE ANCESTORS OF MAN (Prochordata). - -FIRST STAGE: +Monera+. - -The most ancient ancestors of Man, as of all other organisms, were -living creatures of the simplest kind imaginable, _organisms without -organs_, like the still living Monera. They consisted of simple, -homogeneous, structureless and formless little lumps of mucous or -albuminous matter (protoplasm), like the still living Protamoeba -primitiva. (Compare vol. i. p. 186, Fig. 1.) The _form value_ of these -most ancient ancestors of man was not even equal to that of a cell, but -merely that of a _cytod_ (compare vol. i. p. 347); for, as in the case -of all Monera, the little lump of protoplasm did not as yet possess a -cell-kernel. The first of these Monera _originated_ in the beginning of -the Laurentian period by _spontaneous generation_, or archigony, out of -so-called "inorganic combinations," namely, out of simple combinations -of carbon, oxygen, hydrogen, and nitrogen. The assumption of this -spontaneous generation, that is, of a mechanical origin of the first -organisms from inorganic matter, has been proved in our thirteenth -chapter to be a necessary hypothesis. (Compare vol. i. p. 338.) A -direct _proof_ of the earlier existence of this most ancient ancestral -stage, based upon the fundamental law of biogeny, is possibly still -furnished by the circumstance that, according to the assertions of many -investigators, in the beginning of the development of the egg, the -cell-kernel, or nucleus, disappears, and the egg-cell thus relapses to -the lower stage of the cytod (Monerula, p. 124; _relapse_ of the -nucleated plastid into a non-nucleated condition). The assumption of -this first stage is necessary for most important general reasons. - - -SECOND STAGE: +Amoebae+. - -The second ancestral stage of Man, as of all the higher animals and -plants, is formed by _a simple cell_, that is, a little piece of -protoplasm enclosing a kernel. There still exist large numbers of -similar "single-celled organisms." Among them the common, simple Amoebae -(vol. i. p. 188, Fig. 2) cannot have been essentially different from -these progenitors. The _form value_ of every Amoeba is essentially the -same as that still possessed by the egg of Man, and by the egg of all -other animals. (Vol. i. p. 189, Fig. 3.) The naked egg-cells of Sponges, -which creep about exactly like Amoebae, cannot be distinguished from -them. The egg-cell of Man, which like that of most other animals is -surrounded by a membrane, resembles an enclosed Amoeba. The first -single-celled animals of this kind arose out of Monera by the -differentiation of the inner kernel and the external protoplasm; they -lived in the earlier Primordial period. An irrefutable proof that such -single-celled primaeval animals really existed as the direct ancestors of -Man, is furnished according to the fundamental law of biogeny (vol. i. -p. 309) by the fact that the human egg is nothing more than a simple -cell. (Compare p. 124.) - - -THIRD STAGE: +Synamoebae+. - -In order to form an approximate conception of the organisation of those -ancestors of Man which first developed out of the single-celled Primaeval -animals, it is necessary to trace the changes undergone by the human egg -in the beginning of its individual development. It is just here that -ontogeny guides us with the greatest certainty on to the track of -phylogeny. We have already seen that the egg of Man (in the same way as -that of all other Mammals), after fructification has taken place, falls -by self-division into a mass of simple and equi-formal Amoeba-like cells -(vol. i. p. 190, Fig. 4 _D_). All these divided globules are at first -exactly like one another, naked cells containing a kernel, but without -covering; in many animals they show movements like those of the Amoebae. -This ontogenetic stage of development which we called Morula (p. 125), -on account of its mulberry shape, is _a certain proof_ that in the early -primordial period there existed ancestors of man which possessed the -_form value_ of a mass of homogeneous, loosely connected cells. They may -be called a _community of Amoebae_ (Synamoebae). (Compare p. 127.) They -_originated_ out of the single-celled Primaeval animals of the second -stage by repeated self-division and by the permanent union of the -products of this division. - - -FOURTH STAGE: +Ciliated Larva (Planaeada)+. - -In the course of the ontogenesis of most of the lower animals, and also -in that of the lowest Vertebrate animals, the Lanceolate Animals, or -Amphioxus, there first develops out of the Morula (Frontispiece, Fig. 3) -a ciliated larva (planula). Those cells, lying on the surface of the -homogeneous mass of cells, extend hair-like processes, or fringes of -hairs, which by striking against the water keep the whole body rotating. -The round many-celled body thus becomes differentiated, in that the -external cells covered with cilia differ from the non-ciliated internal -cells (Frontispiece, Fig. 4). In Man and in all other Vertebrate animals -(with the exception of the Amphioxus), as well as in all Arthropoda, -this stage of the ciliated larva has been lost, in the course of time, -by abbreviated inheritance. There must, however, have existed ancestors -of Man in the early Primordial period which possessed the form value of -these ciliated larvae (Planaea, p. 125). A certain proof of this is -furnished by the Amphioxus, which is on the one hand related by blood to -Man, but on the other has retained down to the present day the stage of -the planula. - - -FIFTH STAGE: +Primaeval Stomach Animals (Gastraeada)+. - -In the course of the individual development of Amphioxus, as well as in -the most different lower animals, there first arises out of the planula -the extremely important form of larva which we have named _stomach -larva_, or _gastrula_ (p. 126; Frontispiece, Fig. 5, 6). According to -the fundamental law of biogeny this gastrula proves the former existence -of an independent form of primaeval animal of the same structure, and -this we have named primaeval stomach animal, or Gastraea (pp. 127, 128). -These Gastraeada must have existed during the older Primordial period, -and they must have also included the ancestors of man. A _certain -proof_ of this is furnished by the Amphioxus, which in spite of its -blood relationship to Man still passes through the stage of the gastrula -with a simple intestine and a double intestinal wall. (Compare Plate X. -Fig. _B 4_.) - - -SIXTH STAGE: +Gliding Worms (Turbellaria)+. - -The human ancestors of the sixth stage which originated out of the -Gastraeada of the fifth stage, were low worms, which, of all the forms of -worms known to us, were most closely allied to the Gliding Worms, or -Turbellaria, or at least upon the whole possessed their form value. Like -the Turbellaria of the present day, the whole surface of their body was -covered with cilia, and they possessed a simple body of an oval shape, -entirely without appendages. These acoelomatous worms did not as yet -possess a true body-cavity (coelom) nor blood. They _originated_ in the -early primordial period out of the Gastraeada, by the formation of a -middle germ-layer, or muscular layer, and also by the further -differentiation of the internal parts into various organs; more -especially the first formation of a nervous system, the simplest organs -of sense, the simplest organs for secretion (kidneys) and generation -(sexual organs). The proof that human ancestors existed of a similar -formation, is to be looked for in the circumstance that comparative -anatomy and ontogeny point to the lower acoelomatous Worms as the common -primary form, not merely of all higher Worms, but also of the four -higher tribes of animals. Now, of all the animals known to us, the -Turbellaria, which possess neither a body-cavity nor blood, are most -closely allied to these primaeval acoelomatous Primary Worms. - - -SEVENTH STAGE: +Soft Worms (Scolecida)+. - -Between the Turbellaria of the preceding stage and the Sack Worms of the -next stage, we must necessarily assume at least one connecting -intermediate stage. For the Tunicata, which of all known animals stand -nearest to the eighth stage, and the Turbellaria which most resemble the -sixth stage, indeed both belong to the lower division of the unsegmented -Worms; but still these two divisions differ so much from one another in -their organization, that we must necessarily assume the earlier -existence of extinct intermediate forms between the two. These -connecting links, of which no fossil remains exist, owing to the soft -nature of their bodies, we may comprise as _Soft Worms_, or Scolecida. -They developed out of the Turbellaria of the sixth stage by forming a -true body-cavity (a coelom) and blood in their interior. It is difficult -to say which of the still living Coelomati are nearest akin to these -extinct Scolecida; it may be the Acorn-worms (Balanoglossus). The proof -that even the direct ancestors of man belonged to these Scolecida, is -furnished by the comparative anatomy and the ontogeny of Worms and of -the Amphioxus. The form value of this stage must moreover have been -represented by several very different intermediate stages, in the wide -gap between Turbellaria and Tunicata. - - -EIGHTH STAGE: +Sack Worms (Himatega)+. - -Under the name of Sack worms, or Himatega, we here allude in the eighth -place to those Coelomati, out of which the most ancient skull-less -Vertebrata were directly developed. Among the Coelomati of the present -day, the _Ascidians_ are the nearest relatives of these exceedingly -remarkable Worms, which connect the widely differing classes of -Invertebrate and Vertebrate animals. That the ancestors of man really -existed during the primordial period in the form of these Himatega, is -_distinctly proved_ by the exceedingly remarkable and important -agreement presented by the ontogeny of the Amphioxus and the Ascidia. -(Compare Plates XII. and XIII., also pp. 152, 200, etc.) From this fact -the earlier existence of Sack Worms may be inferred; they of all known -worms were most closely related to our recent Tunicates, especially to -the freely swimming young forms or larvae of the simple Sea-squirts -(Ascidia, Phallusia). They originated out of the worms of the seventh -stage by the formation of a dorsal nerve-marrow (medulla tube), and by -the formation of the spinal rod (chorda dorsalis) which lies below it. -It is just the position of this central spinal rod, or axial skeleton, -between the dorsal marrow on the dorsal side, and the intestinal canal -on the ventral side, which is most characteristic of all Vertebrate -animals, including man, but also of the larvae of the Ascidia. The form -value of this stage nearly corresponds with that which the larvae of the -simple Sea-squirts possess at the time when they show the beginning of -the dorsal marrow and spinal rod. (Plate XII. Fig. _A 5_: compare the -explanation of these figures in the Appendix.) - - -SECOND HALF OF THE SERIES OF HUMAN ANCESTORS. VERTEBRATE ANIMAL -ANCESTORS OF MAN (Vertebrata). - -NINTH STAGE: +Skull-less Animals (Acrania)+. - -The series of human ancestors, which in accordance with their whole -organisation we have to consider as Vertebrate animals, begins with the -Skull-less animals, or Acrania, of whose nature the still living -Lancelet (Amphioxus lanceolatus, Plate XII. _B_, XIII. _B_) gives us a -faint idea. Since this little animal in its earliest embryonal state -entirely agrees with the Ascidia, and in its further development shows -itself to be a true Vertebrate animal, it forms a direct transition from -the Vertebrata to the Invertebrata. Even if the human ancestors of the -ninth stage in many respects differed from the Amphioxus--the last -surviving representative of the Skull-less animals--yet they must have -resembled it in its most essential characteristics, in the absence of -head, skull, and brain. Skull-less animals of such structure--out of -which animals with skulls developed at a later period--lived during the -primordial period, and originated out of the Himatega of the eighth -stage by the formation of the metamera, or body segments, as also by the -further differentiation of all organs, especially the more perfect -development of the dorsal nerve-marrow and the spinal rod lying below -it. Probably the separation of the two sexes (gonochorism) also began at -this stage, whereas all the previously mentioned invertebrate ancestors -(apart from the 3--4 first neutral stages) exhibited the condition of -hermaphrodites (hermaphroditism). (Compare vol. i. p. 196.) The _certain -proof_ of the former existence of these skull-less and brainless -ancestors of man, is furnished by the comparative anatomy and the -ontogeny of the Amphioxus and of the Craniota. - - -TENTH STAGE: +Single-nostriled Animals (Monorrhina)+. - -Out of the Skull-less ancestors of man there arose in the first place -animals with skulls, or Craniota, of the most imperfect nature. The -lowest stage of all still living Craniota is occupied by the class of -round-mouthed animals, or Cyclostoma, namely, the Hag (Myxinoidea) and -Lampreys (Petromyzontia). From the internal organization of these -single-nostriled animals, or Monorrhina, we can form an approximate idea -of the nature of the human ancestors of the tenth stage. In the former, -as also in the latter, skull and brain must have been of the simplest -form, and many important organs, as for example, the swimming bladder, -the sympathetic nerve, the spleen, the jaw skeleton, and both pairs of -legs, may probably as yet not have existed. However, the pouch gills and -the round sucking mouth of the Cyclostoma must probably be looked upon -as purely adaptive characteristics, which did not exist in the -corresponding stage of ancestors. The single-nostriled animals -originated during the primordial period out of the skull-less animals by -the anterior end of the dorsal marrow developing into the brain, and the -anterior end of the dorsal chord into the skull. The _certain proof_ -that such single-nostriled and jawless ancestors of man did exist, is -found in the "comparative anatomy of the Myxinoidea." - - -ELEVENTH STAGE: +Primaeval Fish (Selachii.)+. - -Of all known Vertebrate animals, the ancestors of the Primaeval Fish -probably showed most resemblance to the still living Sharks (Squalacei). -They _originated_ out of the single-nostriled animals by the division of -the single nostril into two lateral halves, by the formation of a -sympathetic nervous system, a jaw skeleton, a swimming bladder, and two -pairs of legs (breast fins or fore-legs, and ventral fins or hind-legs). -The internal organisation of this stage may probably, upon the whole, -have corresponded to the lowest species of Sharks known to us; the -swimming bladder was however more strongly developed; in the case of the -latter it exists only as a rudimentary organ. They _lived_ as early as -the Silurian period, as is proved by the fossil remains of sharks (teeth -and fin spines) from the Silurian strata. A _certain proof_ that the -Silurian ancestors of man and of all the other double-nostriled animals -were nearest akin to the Selachii, is furnished by the comparative -anatomy of the latter; it shows that the relations of organisation in -all Amphirrhina can be derived from those of the Selachii. - - -TWELFTH STAGE: +Mud Fish (Dipneusta)+. - -Our twelfth ancestral stage is formed by Vertebrate animals which -probably possessed a remote resemblance to the still living Salamander -fish (Ceratodus, Protopterus, Lepidosiren, p. 212). They _originated_ -out of the Primaeval fish (probably at the beginning of the palaeolithic, -or primary period) by adaptation to life on land, and by the -transformation of the swimming bladder into an air-breathing lung, and -of the nasal cavity (which now opened into the cavity of the mouth) -into air passages. The series of the ancestors of man which breathed air -through lungs began at this stage. Their organisation may probably in -many respects have agreed with that of the still living Ceratodus and -Protopterus, but at the same time may have been very different. They -probably lived at the beginning of the Devonian period. Their existence -is _proved_ by comparative anatomy, which shows the Dipneusta to be an -intermediate stage between the Selachii and Amphibia. - - -THIRTEENTH STAGE: +Gilled Amphibians (Sozobranchia)+. - -Out of those Mud Fish, which we considered the primary forms of all the -Vertebrata which breathe through lungs, there developed the class of -Amphibia as the main line (pp. 205, 216). Here began the five-toed -formation of the foot (the Pentadactyla), which was thence transmitted -to the higher Vertebrata, and finally also to Man. The gilled Amphibians -must be looked upon as our most ancient ancestors of the class of -Amphibia; besides possessing lungs they retained throughout life regular -gills, like the still living Proteus and Axolotl (p. 218). They -_originated_ out of the Dipneusta by the transformation of the paddling -fins into five-toed legs, and also by the more perfect differentiation -of various organs, especially of the vertebral column. In any case they -existed about the middle of the palaeolithic, or primary period, possibly -even before the Coal period; for fossil Amphibia are found in coal. The -_proof_ that similar gilled Amphibians were our direct ancestors, is -given by the comparative anatomy and the ontogeny of Amphibia and -Mammals. - - -FOURTEENTH STAGE: +Tailed Amphibians (Sozura)+. - -Our amphibious ancestors which retained their gills throughout life, -were replaced at a later period by other Amphibia, which, by -metamorphosis, lost the gills which they had possessed in early life, -but retained the tail, as in the case of the salamanders and newts of -the present day. (Compare p. 218.) They _originated_ out of the gilled -Amphibians by accustoming themselves in early life to breathe only -through gills, and later in life only through lungs. They probably -existed even in the second half of the primary, namely, during the -Permian period, but possibly even during the Coal period. The _proof_ of -their existence lies in the fact that tailed Amphibians form a necessary -intermediate link between the preceding and succeeding stages. - - -FIFTEENTH STAGE: +Primaeval Amniota (Protamnia)+. - -The name Protamnion we have given to the primary form of the three -higher classes of Vertebrate animals, out of which the Proreptilia and -the Promammalia developed as two diverging branches (p. 222). It -_originated_ out of unknown tailed Amphibia by the complete loss of the -gills, by the formation of the amnion, of the cochlea, and of the round -window in the auditory organ, and of the organs of tears. It probably -originated in the beginning of the mesolithic or secondary period, -perhaps even towards the end of the primary, in the Permian period. The -_certain proof_ that it once existed lies in the comparative anatomy and -the ontogeny of the Amniota; for all Reptiles, Birds, and Mammals, -including Man, agree in so many important characteristics that they -must, with full assurance, be admitted to be the descendants of a -single common primary form, namely, of the Protamnion. - - -SIXTEENTH STAGE: +Primary Mammals (Promammalia)+. - -We now find ourselves more at home with our ancestors. From the -sixteenth up to the twenty-second stage they all belong to the large and -well known class of Mammals, the confines of which we ourselves have as -yet not transgressed. The common, long since extinct and unknown primary -forms of all Mammalia, which we have named Promammalia, were at all -events, of all still living animals, of the class most closely related -to the Beaked animals, or Ornithostoma (Ornithorhynchus, Echidna, p. -233). They differed from the latter, however, by the teeth present in -their jaws. The formation of the beak in the Beaked animals of the -present day must be looked upon as an adaptive characteristic which -developed at a later period. The Promammalia arose out of the Protamnia -(probably only at the beginning of the secondary period, namely, in the -Trias) by various advances in their internal organisation, as also by -the transformation of the epidermal scales into hairs, and by the -formation of a mammary gland which furnished milk for the nourishment of -the young ones. The _certain proof_ that the Promammalia--inasmuch as -they are the common primary forms of all Mammals--also belong to our -ancestors, lies in the comparative anatomy and the ontogeny of Mammalia -and Man. - - -SEVENTEENTH STAGE: +Pouched Animals (Marsupialia)+. - -The three sub-classes of Mammalia--as we have already seen--stand in -such a relation to one another that the Marsupials, both as regards -their anatomy and their ontogeny and phylogeny, form the direct -transition from the Monotrema to Placental animals (p. 247). -Consequently, human ancestors must also have existed among Marsupials. -They _originated_ out of the Monotrema--which include the primary -Mammalia, or Promammalia--by the division of the cloaca into the rectum -and the urogenital sinus, by the formation of a nipple on the mammary -gland, and by the partial suppression of the clavicles. The oldest -Marsupials at all events existed as early as the Jura period (perhaps -even in the Trias); during the Chalk period they passed through a series -of stages preparing the way for the origin of Placentalia. The certain -proof of our derivation from Marsupials--nearly akin to the still living -opossum and kangaroo in their essential inner structure--is furnished by -the comparative anatomy and the ontogeny of Mammalia. - - -EIGHTEENTH STAGE: +Semi-apes (Prosimiae)+. - -The small group of Semi-apes, as we have already seen, is one of the -most important and most interesting orders of Mammalia. It contains the -direct primary forms of Genuine Apes, and thus also of Man. Our Semi-ape -ancestors probably possessed only a very faint external resemblance to -the still living, short-footed Semi-apes (Brachytarsi), especially the -Maki, Indri, and Lori (p. 256). They _originated_ (probably at the -beginning of the Cenolithic, or Tertiary period) out of Marsupials of -Rat-like appearance by the formation of a placenta, the loss of the -marsupium and the marsupial bones, and by the higher development of the -commissures of the brain. The _certain proof_ that Genuine Apes, and -hence also our own race, are the direct descendants of Semi-apes, is to -be found in the comparative anatomy and the ontogeny of Placental -animals. - - -NINETEENTH STAGE: +Tailed Apes (Menocerca)+. - -Of the two classes of Genuine Apes which developed out of the Semi-apes, -it is only the narrow-nosed, or Catarrhini, which are closely related by -blood to Man. Our older ancestors from this group probably resembled the -still living Nose-apes and Holy-apes (Semnopithecus), which possess jaws -and narrow noses like Man, but have a long tail, and their bodies -densely covered with hair (p. 271). The Tailed Apes with narrow noses -(Catarrhini Menocerci) _originated_ out of Semi-apes by the -transformation of the jaw, and by the claws on their toes becoming -changed into nails; this probably took place as early as the older -Tertiary period. The _certain proof_ of our derivation from Tailed -Catarrhini is to be found in the comparative anatomy and the ontogeny of -Apes and of Man. - - -TWENTIETH STAGE: +Man-like Apes (Anthropoides)+. - -Of all still living Apes the large tail-less, narrow-nosed Apes, namely, -the Orang and Gibbon in Asia, the Gorilla and Chimpanzee in Africa, are -most nearly akin to Man. It is probable that these Man-like Apes, or -Anthropoides, originated during the Mid-tertiary period, namely, in the -Miocene period. They developed out of the Tailed Catarrhini of the -preceding stage--with which they essentially agree--by the loss of the -tail, the partial loss of the hairy covering and by the excessive -development of that portion of the brain just above the facial portion -of the skull. There do not exist direct human ancestors among the -Anthropoides of the present day, but they certainly existed among the -unknown extinct Human Apes of the Miocene period. The _certain proof_ of -their former existence is furnished by the comparative anatomy of -Man-like Apes and of Man. - - -TWENTY-FIRST STAGE: +Ape-like Men (Pithecanthropi)+. - -Although the preceding ancestral stage is already so nearly akin to -genuine Men that we scarcely require to assume an intermediate -connecting stage, still we can look upon the speechless Primaeval Men -(Alali) as this intermediate link. These Ape-like men, or -Pithecanthropi, very probably existed towards the end of the Tertiary -period. They originated out of the Man-like Apes, or Anthropoides, by -becoming completely habituated to an upright walk, and by the -corresponding stronger differentiation of both pairs of legs. The fore -hand of the Anthropoides became the human hand, their hinder hand became -a foot for walking. Although these Ape-like Men must not merely by the -external formation of their bodies, but also by their internal mental -development, have been much more akin to real Men than the Man-like Apes -could have been, yet they did not possess the real and chief -characteristic of man, namely, the articulate human language of words, -the corresponding development of a higher consciousness, and the -formation of ideas. The _certain proof_ that such Primaeval Men without -the power of speech, or Ape-like Men, must have preceded men possessing -speech, is the result arrived at by an inquiring mind from comparative -philology (from the "comparative anatomy" of language), and especially -from the history of the development of language in every child ("glottal -ontogenesis") as well as in every nation ("glottal phylogenesis"). - - -TWENTY-SECOND STAGE: +Men (Homines)+. - -Genuine Men _developed_ out of the Ape-like Men of the preceding stage -by the gradual development of the animal language of sounds into a -connected or articulate language, of words. The development of this -function, of course, went hand in hand with the development of its -organs, namely, the higher differentiation of the larynx and the brain. -The transition from speechless Ape-like Men to Genuine or Talking Men -probably took place at the beginning of the Quaternary period, namely, -in the Diluvial period, but possibly even at an earlier date, in the -more recent Tertiary. As, according to the unanimous opinion of most -eminent philologists, all human languages are not derived from a common -primaeval language, we must assume a polyphyletic origin of language, and -in accordance with this a polyphyletic transition from speechless -Ape-like Men to Genuine Men. - - -ANCESTRAL SERIES OF THE HUMAN PEDIGREE. - -M N = Boundary between the Invertebrate and Vertebrate Ancestors. - - - --------------------------------------------------------------------------------------------------- - _Epochs of the_ | _Geological Periods_ | _Animal_ | _Nearest Living_ - _Organic_ | _of the_ | _Ancestral Stages_ | _Relatives of the_ - _History of the_| _Organic History_ | _of_ | _Ancestral Stages._ - _Earth._ | _of the Earth._ | _Man._ | - --------------------------------------------------------------------------------------------------- - { { 1. Monera { _Protogenes_ - { { (_Monera_) { _Protamoeba_ - { { - { { 2. Single-celled { Simple Amoebae - { { Primaeval animals { (_Automoebae_) - { { - { { 3. Many-celled { Communities of - { { Primaeval animals { Amoebae - { { { (_Synamoebae_) - { { - { { 4. Ciliated planulae { Planula larvae - { { (_Planaeada_) { - I. { { - ARCHILITHIC { 1. Laurentian Period { 5. Primaeval Intestinal { Gastrula larvae - OR { { animals (_Gastraeada_) { - { 2. Cambrian Period { - PRIMORDIAL { { 6. Gliding Worms { _Rhabdocoela_ - EPOCH { 3. Silurian Period { (_Turbellaria_) { _Dendrocoela_ - { { - { { 7. Soft-worms { ?Between the Sea-squirts - { { (_Scolecida_) { and Gliding worms - { { - { { 8. Sack worms { Sea-squirts - { { (_Himatega_) { (_Ascidiae_) - { { M.................................................N - { { 9. Skull-less { Lancelets - { { (_Acrania_) { (_Amphioxi_) - { { - { { 10. Single-nostriled { Lampreys - { { (_Monorrhina_) { (_Petromyzonta_) - { (Compare p. 22, and { - { Plate XIV. and its { 11. Primaeval fish { Sharks - { explanation.) { (_Selachii_) { (_Squalacei_) - --------------------------------------------------------------------------------------------------- - { 4. Devonian Period { 12. Salamander fish { Mud fish - II. { { (_Dipneusta_) { (_Protopteri_) - PALAEOLITHIC { 5. Coal Period { - OR { { 13. Gilled Amphibia { (_Proteus_) - { 6. Permian Period { (_Sozobranchia_) { Axolotl (_Siredon_) - PRIMARY { { - EPOCH { { 14. Tailed Amphibia { Water-newts - { { (_Sozura_) { (_Tritons_) - --------------------------------------------------------------------------------------------------- - { { 15. Primaeval Amniota { ?Between the Tailed-Amphibia - III. { { (_Protamnia_) { and Primary - MESOLITHIC { 7. Trias Period { { mammals - OR { { - { 8. Jura Period { 16. Primary Mammals { Beaked animals - SECONDARY { { (_Promammalia_) { (_Monotrema_) - EPOCH { 9. Chalk Period { - { { 17. Pouched animals { Pouched rats - { { (_Marsupialia_) { (_Didelphys_) - --------------------------------------------------------------------------------------------------- - { { 18. Semi-apes { Lori (_Stenops_) - { { (_Prosimiae_) { Maki (_Lemur_) - { { - IV. { { 19. Tailed Narrow-nosed { Nose apes - CENOLITHIC { 10. Eocene Period { Apes { Holy apes - OR { { - { 11. Miocene Period { 20. Men-like Apes or { Gorilla, Chimpanzee, - TERTIARY { { Tail-less Narrow-nosed { Orang, - EPOCH { 12. Pliocene Period { Apes { Gibbon - { { - { { 21. Speechless Men or { Deaf and Dumb, - { { Ape-like Men { Cretins or - { { { Microcephali - --------------------------------------------------------------------------------------------------- - V. { { { - QUATERNARY { 13. Diluvial Period { 22. Talking Men { Australians and - EPOCH { 14. Alluvial Period { { Papuans - - - - -CHAPTER XXIII. - -MIGRATION AND DISTRIBUTION OF MANKIND. HUMAN SPECIES AND HUMAN RACES. - - - Age of the Human Race.--Causes of its Origin.--The Origin of - Human Language.--Monophyletic or Single, Polyphyletic or - Multiple Origin of the Human Race.--Derivation of Man from many - Pairs.--Classification of the Human Races.--System of Twelve - Species of Men.--Woolly-haired Men, or Ulotrichis.--Bushy-haired - (Papuans, Hottentots).--Fleecy-haired (Caffres, - Negroes).--Straight-haired men, or Lissotrichi.--Stiff-haired - (Australians, Malays, Mongols, Arctic, and American - Tribes).--Curly-haired (Dravidas, Nubians, Midlanders).--Number - of Population.--Primaeval Home of Man (South Asia, or - Lemuria).--Nature of Primaeval Men.--Number of Primaeval Languages - (Monoglottists and Polyglottists).--Divergence and Migration of - the Human Race.--Geographical Distribution of the Human Species. - - -The rich treasure of knowledge we possess in the comparative anatomy and -the history of the development of Vertebrate animals, enables us even -now to establish the most important outlines of the human pedigree in -the way we have done in the last chapter. One must, however, not expect -to be able to survey satisfactorily in every detail the history or -phylogeny of the human species which will henceforth form the basis of -Anthropology, and of all other sciences. The complete development of -this most important science--of which we can only lay the first -foundation--must remain reserved for the more accurate and extensive -investigations of a future time. This applies also to those more special -questions of human phylogeny at which it is desirable before concluding -to take a cursory glance, namely, the question of the time and place of -the origin of the human race, as also of the different species and races -into which it has differentiated. - -In the first place, the period of the earth's history, within which the -slow and gradual transmutation of the most man-like apes into the most -ape-like men took place, can of course not be determined by years, nor -even by centuries. This much can, however, with full assurance be -maintained, for reasons given in the last chapter, that Man is derived -from Placental animals. Now, as fossil remains of these Placentalia are -found only in the tertiary rocks, the human race can at the earliest -have developed only within the Tertiary period out of perfected man-like -apes. What seems most probable is that this most important process in -the history of terrestrial creation occurred towards the end of the -Tertiary period, that is in the Pliocene, perhaps even in the Miocene -period, but possibly also not until the beginning of the Diluvial -period. At all events Man, as such, lived in central Europe as early as -the Diluvial period, contemporaneously with many large, long since -extinct mammals, especially with the diluvial elephant, or mammoth -(Elephas primigenius), the woolly-haired rhinoceros (Rhinoceros -tichorrhinus), the giant deer (Cervus euryceros), the cave bear (Ursus -spelaeus), the cave hyaena (Hyaena spelaea), the cave lion (Felis spelaeus), -etc. The results brought to light by recent geology and archaeology as to -these fossil men and their animal contemporaries of the diluvial period, -are of the greatest interest. But as a closer examination of them would -occupy too much of my limited space, I must confine myself here to -setting forth their great general importance, and refer for particulars -to the numerous writings which have recently been published on the -Primaeval History of Man, more especially to the excellent works of -Charles Lyell,(30) Carl Vogt,(27) Friedrich Rolle,(28) John Lubbock,(44) -L. Buechner,(43) etc. - -The numerous and interesting discoveries presented to us by these -extensive investigations of late years on the primaeval history of the -human race, place the important fact (long since probable for many other -reasons) beyond a doubt, that the human race, as such, has existed for -more than twenty thousand years. But it is also probable that more than -a hundred thousand years, perhaps many hundred thousands of years, have -elapsed since its first appearance; and, in contrast to this, it must -seem very absurd that our calendars still represent the "Creation of the -World, according to Calvisius," to have taken place 5821 years ago. - -Now, whether we reckon the period during which the human race, as such, -has existed and diffused itself over the earth, as twenty thousand, a -hundred thousand, or many hundred thousands of years, the lapse of time -is in any case immensely small in comparison with the inconceivable -length of time which was requisite for the gradual development of the -long chain of human ancestors. This is evident even from the small -thickness of all Diluvial deposits in comparison with the Tertiary, and -of these again in comparison with the preceding deposits. (Compare p. -22.) But the infinitely long series of slowly and gradually developing -animal forms from the simplest Moneron to the Amphioxus, from this to -the Primaeval Fish, from the Primaeval Fish to the first Mammal, and -again, from the latter to Man, also require for their historical -development a succession of periods probably comprising many thousands -of millions of years. (Compare vol. i. p. 129.) - -Those processes of development which led to the origin of the most -Ape-like Men out of the most Man-like Apes must be looked for in the two -adaptational changes which, above all others, are distinctive of Man, -namely, _upright walk_ and _articulate speech_. These two -_physiological_ functions necessarily originated together with two -corresponding _morphological_ transmutations, with which they stand in -the closest correlation, namely, the _differentiation of the two pairs -of limbs and the differentiation of the larynx_. The important -perfecting of these organs and their functions must have necessarily and -powerfully reacted upon the differentiation of the brain and the mental -activities dependent upon it, and thus have paved the way for the -endless career in which Man has since progressively developed, and in -which he has far outstripped his animal ancestors. (Gen. Morph. ii. p. -430.) - -The first and earliest of these three great processes in the development -of the human organism probably was the _higher differentiation and the -perfecting of the extremities_ which was effected by the _habit of an -upright walk_. By the fore feet more and more exclusively adopting and -retaining the function of grasping and handling, and the hinder feet -more and more exclusively the function of standing and walking, there -was developed that contrast between the hand and foot which is indeed -not exclusively characteristic of man, but which is much more strongly -developed in him than in the apes most like men. This differentiation of -the fore and hinder extremities was, however, not merely most -advantageous for their own development and perfecting, but it was -followed at the same time by a whole series of very important changes in -other parts of the body. The whole vertebral column, and more especially -the girdle of the pelvis and shoulders, as also the muscles belonging to -them, thereby experienced those changes which distinguish the human body -from that of the most man-like apes. These transmutations were probably -accomplished long before the origin of articulate speech; and the human -race thus existed for long, with an upright walk and the characteristic -human form of body connected with it, before the actual development of -human language, which would have completed the second and the more -important part of human development. We may therefore distinguish a -special (21st) stage in the series of our human ancestors, namely, -Speechless Man (Alalus), or Ape-man (Pithecanthropus), whose body was -indeed formed exactly like that of Man in all essential characteristics, -but who did not as yet possess articulate speech. - -The origin of _articulate language_, and the _higher differentiation and -perfecting of the larynx_ connected with it, must be looked upon as only -a later, and the most important stage in the process of the development -of Man. It was, doubtless, this process which above all others helped to -create the deep chasm between man and animal, and which also first -caused the most important progress in the mental activity and the -perfecting of the brain connected with it. There indeed exists in very -many animals a language for communicating sensations, desires, and -thoughts, partly a language of gestures, partly a language of feeling or -touch, partly a language of cries or sounds, but a real language of -words or ideas, a so-called "articulate" language, which by abstraction -changes sounds into words, and words into sentences, belongs, as far as -we know, exclusively to Man. - -The origin of human language must, more than anything else, have had an -ennobling and transforming influence upon the mental life of Man, and -consequently upon his brain. The higher differentiation and perfecting -of the brain and mental life as its highest function developed in direct -correlation with its expression by means of speech. Hence, the highest -authorities in comparative philology justly see in the development of -human speech the most important process which distinguishes Man from his -animal ancestors. This has been especially set forth by August -Schleicher, in his treatise "On the Importance of Speech for the Natural -History of Man."(34) In this relation we see one of the closest -connections between comparative zoology and comparative philology; and -here the theory of development assigns to the latter the task of -following the origin of language step by step. This task, as interesting -as it is important, has of late years been successfully undertaken by -many inquirers, but more especially by Wilhelm Bleek, who has been -occupied for seventeen years in South Africa with the study of the -languages of the lowest races of men, and hence has been enabled to -solve the question. August Schleicher more especially discusses, in -accordance with the theory of selection, how the various forms of -speech, like all other organic forms and functions, have developed by -the process of natural selection, and have divided into many species and -dialects. - -I have no space here to follow the process of the formation of language, -and must refer in regard to this to the above-mentioned important work -of Wilhelm Bleek, "On the Origin of Language."(35) But we have still to -mention one of the most important results of comparative philology, -which is of the highest importance to the genealogy of the human -species, that is, that _human language was probably of a multiple, or -polyphyletic origin_. Human speech, as such, did not develop probably -until the genus of Speechless or Primaeval Man, or Ape Man, had -separated into several kinds or species. In each of these human species, -and perhaps even in the different sub-species and varieties of this -species, language developed freely and independently of the others. At -least Schleicher, one of the first authorities on the subject, maintains -that "even the beginnings of language--in sounds as well as in regard to -ideas and views which were reflected in sounds, and further, in regard -to their capability of development--must have been different. For it is -positively impossible to trace all languages to one and the same -primaeval language. An impartial investigation rather shows that there -are as many primaeval languages as there are races."(34) In like manner, -Friederich Mueller(41) and other eminent linguists assume a free and -independent origin of the families of languages and their primaeval -stocks. It is well known, however, that the boundaries of these tribes -of languages and their ramifications are by no means always the -boundaries of the different human species, or the so-called "races," -distinguished by us on account of their bodily characteristics. This, -as well as the complicated relations of the mixture of races, and the -various forms of hybrids, is the great difficulty lying in the way of -tracing the human pedigree in its individual branches, species, races, -varieties, etc. - -In spite of these great and serious difficulties, we cannot here refrain -from taking one more cursory glance at the ramification of the human -pedigree, and at the same time considering, from the point of view of -the theory of descent, the much discussed question of the monophyletic -or polyphyletic origin of the human race, and its species or races. As -is well known, two great parties have for a long time been at war with -each other upon this question; the _monophylists_ (or monogenists) -maintain the unity of origin and the blood relationship of all races of -men. The _polyphylists_ (or polygenists), on the other hand, are of -opinion that the different races of men are of independent origin. -According to our previous genealogical investigations we cannot doubt -that, at least in a _wide sense_, the monophyletic opinion is the right -one. For even supposing that the transmutation of Man-like Apes into Men -had taken place several times, yet those Apes themselves would again be -allied by the one pedigree common to the whole order of Apes. The -question therefore would always be merely about a nearer or remoter -degree of blood relationship. In a _narrower sense_, on the other hand, -the polyphylist's opinion would probably be right, inasmuch as the -different primaeval languages have developed quite independently of one -another. Hence, if the origin of an articulate language is considered as -the real and principal act of humanification, and the species of the -human race are distinguished according to the roots of their language, -it might be said that the different races of men had originated, -independently of one another, by different branches of primaeval, -speechless men directly springing from apes, and forming their own -primaeval language. Still they would of course be connected further up or -lower down at their root, and thus all would finally be derived from a -common primaeval stock. - -While we hold the latter of these convictions, and while we for many -reasons believe that the different species of speechless primaeval men -were all derived from a common ape-like human form, we do not of course -mean to say that _all men are descended from one pair_. This latter -supposition, which our modern Indo-Germanic culture has taken from the -Semitic myth of the Mosaic history of creation, is by no means tenable. -The whole of the celebrated dispute, as to whether the human race is -descended from a single pair or not, rests upon a completely false way -of putting the question. It is just as senseless as the dispute as to -whether all sporting dogs or all race-horses are descended from a single -pair. We might with equal justice ask whether all Germans or all -Englishmen are "descended from a single pair," etc. A "first human -pair," or "a first man," has in fact never existed, any more than there -ever existed a first pair or a first individual of Englishmen, Germans, -race-horses, or sporting dogs. The origin of a new species, of course, -always results from an existing species, by a long chain of many -different individuals sharing the slow process of transformation. -Supposing that we had all the different pairs of Human Apes and Ape-like -Men before us--which belong to the true ancestors of the human race--it -would even then be quite impossible (without doing so most arbitrarily) -to call any one of these pairs of ape-like men "the first pair." As -little can we derive each of the twelve races or species of men, which -we shall consider directly, from a "first pair." - -The difficulties met with in classifying the different races or species -of men are quite the same as those which we discover in classifying -animal and vegetable species. In both cases forms apparently quite -different are connected with one another by a chain of intermediate -forms of transition. In both cases the dispute as to what is a kind or a -species, what a race or a variety, can never be determined. Since -Blumenbach's time, as is well known, it has been thought that mankind -may be divided into five races or varieties, namely: (1) the Ethiopian, -or black race (African negro); (2) the Malayan, or brown race (Malays, -Polynesians, and Australians); (3) the Mongolian, or yellow race (the -principal inhabitants of Asia and the Esquimaux of North America); (4) -the Americans, or red race (the aborigines of America); and (5) the -Caucasian, or white race (Europeans, north Africans, and south-western -Asiatics). All of these five races of men, according to the Jewish -legend of creation, are said to have been descended from "a single -pair"--Adam and Eve,--and in accordance with this are said to be -varieties of one kind or species. If, however, we compare them without -prejudice, there can be no doubt that the differences of these five -races are as great and even greater than the "specific differences" by -which zoologists and botanists distinguish recognised "good" animal and -vegetable species ("bonae species"). The excellent palaeontologist -Quenstedt is right in maintaining that, "if Negroes and Caucasians were -snails, zoologists would universally agree that they represented two -very excellent species, which could never have originated from one pair -by gradual divergence." - -The characteristics by which the races of men are gradually -distinguished are partly taken from the formation of the hair, partly -from the colour of the skin, and partly from the formation of the skull. -In regard to the last character, two extremes are distinguished, namely, -long heads and short heads. In _long-headed men_ (Dolichocephali), whose -strongest development is found in Negroes and Australians, the skull is -extended, narrow, and compressed on the right and left. In _short-headed -men_ (Brachycephali), on the other hand, the skull is compressed in an -exactly opposite manner, from the front to the back, is short and broad, -which is especially striking in the case of the Mongolians. -_Medium-headed men_ (Mesocephali), standing between the two extremes, -predominate especially among Americans. In every one of these three -groups we find men with _slanting teeth_ (Prognathi), whose jaws, like -those of the animal snout, strongly project, and whose front teeth -therefore slope in front, and men with _straight teeth_ (Orthognathi), -whose jaws project but little, and whose front teeth stand -perpendicularly. During the last ten years a great deal of time and -trouble have been devoted to the careful examination and measurement of -the forms of skulls, which have, however, not been rewarded by -corresponding results. For within a single species, as for example -within the Mediterranean species, the form of the skull may vary so much -that both extremes are met with in the same species. Much better -starting-points for the classification of the human species are -furnished by the nature of the hair and speech, because they are much -more strictly hereditary than the form of the skull. - -Comparative philology seems especially to be becoming an authority in -this matter. In the latest great work on the races of men, which -Friederich Mueller has published in his excellent "Ethnography,"(42) he -justly places language in the fore-ground. Next to it the nature of the -hair of the head is of great importance; for although it is in itself of -course only a subordinate morphological character, yet it seems to be -strictly transmitted within the race. Of the twelve species of men -distinguished on the following table (p. 308), the four lower species -are characterised by the woolly nature of the hair of their heads; every -hair is flattened like a tape, and thus its section is oval. These four -species of _woolly-haired men_ (Ulotrichi) we may reduce into two -groups--tuft-haired and fleecy-haired. The hair on the head of -_tuft-haired men_ (Lophocomi), Papuans and Hottentots, grows in -unequally divided small tufts. The woolly hair of _fleecy-haired men_ -(Eriocomi), on the other hand, in Caffres and Negroes, grows equally all -over the skin of the head. All Ulotrichi, or woolly-haired men, have -slanting teeth and long heads, and the colour of their skin, hair, and -eyes is always very dark. All are inhabitants of the Southern -Hemisphere; it is only in Africa that they come north of the equator. -They are on the whole at a much lower stage of development, and more -like apes, than most of the Lissotrichi, or straight-haired men. The -Ulotrichi are incapable of a true inner culture and of a higher mental -development, even under the favourable conditions of adaptation now -offered to them in the United States of North America. No woolly-haired -nation has ever had an important "history." - - -SYSTEMATIC SURVEY - -_Of the 12 Species of Men and their 36 Races._ - -(Compare Plate XV.) - - - -------------------+--------------------------+----------------------------+------------- - _Species._ | _Races._ | _Home._ | _Immigrated_ - | | | _from the_ - -------------------+--------------------------+----------------------------+------------- - { 1. =Papuan= { 1. Nigritos Malacca, Philippine West - { +Homo Papua+ { Islands - { { 2. New Guinea men New Guinea West - { 2. =Hottentot= { 3. Melanesians Melanesia North-west - { +Homo+ { 4. Tasmanians Van Diemen's Land North-east - { +Hottentottus+ - { { 5. Hottentots The Cape North-east - { { 6. Bushmen The Cape North-east - - { 3. =Kaffre= { 7. Zulu Kaffres Eastern South Africa North - { +Homo Cafer+ { 8. Beschuanas Central South Africa North-east - { { 9. Congo Kaffres Western South Africa East - { - { 4. =Negro= { 10. Tibu negroes Tibu district South-east - { +Homo Niger+ { 11. Soudan negroes Soudan East - { { 12. Senegambians Senegambia East - { { 13. Nigritians Nigritia East - ....................................................................................... - - { 5. =Australian= { 14. North Australians North Australia North - { +H. Australis+ { 15. South Australians South Australia North - { - { 6. =Malay= { 16. Sundanesians Sunda Archipelago West - { +Homo Malayus+ { 17. Polynesians Pacific Archipelago West - { { 18. Natives of Madagascar Madagascar East - { - { 7. =Mongolian= { 19. Indo-Chinese Tibet, China South - { +Homo+ { 20. Coreo-Japanese Corea, Japan South-west - { +Mongolus+ { 21. Altaians } Central Asia, North Asia South - { { 22. Uralians} North-western Asia, South-east - { { Northern Europe, - { { Hungary - { - { 8. =Arctic Men= { 23. Hyperboreans Extreme N.E. of Asia South-west - { +Homo Arcticus+ { 24. Esquimaux The extreme north of West - { { America - { - { 9. =American= { 25. North Americans North America North-west - { +Homo+ { 26. Central Americans Central America North - { +Americanus+ { 27. South Americans South America North - { { 28. Patagonians The extreme south of North - { { South America - - { 10. =Dravidas= { 29. Deccans Hindostan East? - { +Homo Dravida+ { 30. Singalese Ceylon North? - { - { 11. =Nubian= { 31. Dongolese Nubia East - { +Homo Nuba+ { 32. Fulatians Fulu-land (Central East - { { Africa) - { - { 12. { 33. Caucasians Caucasus South-east - { =Mediterranese= { 34. Basque Extreme north of Spain South? - { +Homo+ { 35. Semites Arabia, North Africa, etc. East - { +Mediterraneus+ { 36. Indo-germanic South-western Asia, South-east - { { tribes Europe, etc. - - ---------------------------------------------------------------- - - Indo-Germanians - 9. =Americans= Semites | - | Magyars | | Caucasians - | Esquimaux | | Basques | | - | | Fins | | | | - | | | \---v---/ \----v----/ - | Hyperboreans | | | - | 8. =Arctic Men= | Samoides | | - | | Tartars | | | | - | | | | | \-------v-------/ - \---v----/ | | | 12. =Mediterranese= - | Calmucks | | | Singalese | - | Tungusians | | | | | | Fulatians - | | | | | | Deccans | | - \--------v---------/ \---v---/ 10. =Dravidas= | Dongolese - =Altaians= =Uralians= | | 11. =Nubians= - | | | | | - | | | | | - Japanese \--------v---------/ \-------v--------/ - | =Ural-Altaians= +Euplocomi+ - | Chinese | | - Coreans | Siamese | Madagascars | - | | Tibet | | Polynesians | | - | | | | | | | | 4. =Negroes= - | | | | | | | | 3. =Kaffres= | - =Coreo-Japanese= \---v----/ | \-----v-----/ | | | - | =Indo-Chinese= | Sundanesians | | | - | | | | | \---v-----/ - | | | | | +Eriocomi+ - | | | | | | - \-----------v-------------/ 6. =Malays= | | - 7. =Mongols= | | | - | | | | - | | | | - \-------v-------------------------------------/ | - =Promalays= 2. =Hottentots= | - | 1. =Papuans= | | - | 5. =Australians= | | | - | | | | | - | | \----v---/ | - \-----v-----/ +Lophocomi+ | - +Euthycomi+ | | - | \---------v---------/ - | =Woolly-haired= - =Straight-haired= +Ulotrichi+ - +Lissotrichi+ | - | | - | | - \--------------v-----------------/ - +Primaeval Men+ - - -In the eight higher races of men, which we comprise as _straight-haired_ -(Lissotrichi), the hair of the head is never actually woolly, although -it is very much frizzled in some individuals. Every separate hair is -cylindrical (not like a tape), and hence its section is circular (not -oval). - -The eight races of Lissotrichi may likewise be divided into two -groups--stiff-haired and curly-haired. _Stiff-haired men_ (Euthycomi), -the hair of whose heads is quite smooth and straight, and not frizzled, -include Australians, Malays, Mongolians, Arctic tribes, and Americans. -Curly-haired men, on the other hand, the hair of whose heads is more or -less curly, and in whom the beard is more developed than in all other -species, include the Dravidas, Nubians, and Mediterranean races. -(Compare Plate XV.) - -Now, before we venture upon the attempt hypothetically to explain the -phyletic divergence of mankind, and the genealogical connection of its -different species, we will premise a short description of the twelve -named species and of their distribution. In order clearly to survey -their geographical distribution, we must go back some three or four -centuries, to the time when the Indian Islands and America were first -discovered, and when the present great mingling of species, and more -especially the influx of the Indo-Germanic race, had as yet not made -great progress. We begin with the lowest stages, with the woolly-haired -men (Ulotrichi), all of whom are prognathic Dolichocephali. - -The _Papuan_ (Homo Papua), of all the still living human species, is -perhaps most closely related to the original primary form of -woolly-haired men. This species now inhabits only the large island of -New Guinea and the Archipelago of Melanesia lying to the east of it -(Solomon's Islands, New Caledonia, the New Hebrides, etc.). But -scattered remnants of it are also still found in the interior of the -peninsula of Malacca, and likewise in many other islands of the large -Pacific Archipelago; mostly in the inaccessible mountainous parts of the -interior, and especially in the Philippine Islands. The but lately -extinct Tasmanians, or the natives of Van Diemen's Land, belonged to -this group. From these and other circumstances it is clear that the -Papuans in former times possessed a much larger area of distribution in -south-eastern Asia. They were driven out by the Malays and forced -eastwards. The skin of all Papuans is of a black colour, sometimes more -inclining to brown, sometimes more to blue. Their woolly hair grows in -tufts, is spirally twisted in screws, and often more than a foot in -length, so that it forms a strong woolly wig, which stands far out from -the head. Their face, below the narrow depressed forehead, has a large -turned-up nose and thick protruding lips. The peculiar form of their -hair and speech so essentially distinguishes the Papuans from their -straight-haired neighbours, from the Malays as well as from the -Australians, that they must be regarded as an entirely distinct species. - -Closely related to the Papuans by the tufted growth of hair, but -geographically widely separated from them, are the _Hottentots_ (Homo -Hottentottus). They inhabit exclusively the southernmost part of Africa, -the Cape and the adjacent parts, and have immigrated there from the -north-east. The Hottentots, like their original kinsmen the Papuans, -occupied in former times a much larger area (probably the whole of -Eastern Africa), and are now approaching their extinction. Besides the -genuine Hottentots--of whom there now exist only the two tribes of the -Coraca (in the eastern Cape districts) and the Namaca (in the western -portion of the Cape)--this species also includes the Bushmen (in the -mountainous interior of the Cape). The woolly hair of all Hottentots -grows in tufts, like brushes, as in the case of Papuans. Both species -also agree in the posterior part of the body, in the female sex being -specially inclined to form a great accumulation of fat (Steatopygia). -But the skin of Hottentots is much lighter, of a yellowish brown colour. -Their very flat face is remarkable for its small forehead and nose, and -large nostrils. The mouth is very broad with big lips, the chin small -and pointed. Their speech is characterised by several quite peculiar -guttural sounds. - -The next neighbours and kinsmen of Hottentots are _Kaffres_ (Homo -Cafer). This woolly-haired human species is, however, distinguished, -like the following one (the genuine Negro), from Hottentots and Papuans -by the woolly hair not being divided into tufts, but covering the head -as a thick fleece. The colour of their skin varies through all shades, -from the yellowish black of the Hottentot to the brown black or pure -black of the genuine Negro. While in former times the race of Kaffres -was assigned to a very small area of distribution, and was generally -looked upon only as a variety of the genuine Negro, this species is now -considered to include almost the whole of the inhabitants of equatorial -Africa, from the 20th degree south latitude to the 4th degree north; -consequently, all South Africans, with the exception of the Hottentots. -They include especially the inhabitants of the Zulu, Zambesi, and -Mozambique districts on the east coast, the large human families of the -Beschuans or Setschuans in the interior, and the Herrero and Congo -tribes of the west coast. They too, like the Hottentots, have immigrated -from the north-east. Kaffres, who were usually classed with Negroes, -differ very essentially from them by the formation of their skull and by -their speech. Their face is long and narrow, their forehead high, and -their nose prominent and frequently curved, their lips not so -protruding, and their chin pointed. The many languages of the different -tribes of Kaffres can all be derived from an extinct primaeval language, -namely, from the Bantu language. - -The genuine _Negro_ (Homo Niger)--when Kaffres, Hottentots, and Nubians -are separated from him--at present forms a much less comprehensive human -species than was formerly supposed. They now only include the Tibus, in -the eastern parts of the Sahara; the Sudan people, or Sudians, who -inhabit the south of that large desert; also the inhabitants of the -Western Coast of Africa, from the mouth of the Senegal in the north, to -beyond the estuary of the Niger in the south (Senegambians and -Nigritians). Genuine Negroes are accordingly confined between the -equator and the Tropic of Capricorn, and only a small portion of the -Tibu tribe in the east have gone beyond this boundary. The Negro species -has spread within this zone, coming from the east. The colour of the -skin of genuine negroes is always more or less of a pure black. Their -skin is velvety to the touch, and characterised by a peculiar offensive -exhalation. Although Negroes agree with Kaffres in the formation of the -woolly hair of the head, yet they differ essentially in the formation of -their face. Their forehead is flatter and lower, their nose broad and -thick, not prominent, their lips large and protruding, and their chin -very short. Genuine Negroes are moreover distinguished by very thin -calves and very long arms. This species of men must have branched into -many separate tribes at a very early period, for their numerous and -entirely distinct languages can in no way be traced to one primaeval -language. - -To the four woolly-haired species of men just discussed, straight-haired -men (Homines Lissotrichi) stand in strong contrast, as another main -branch of the genus. Five of the eight species of the latter, as we have -seen, can be comprised as stiff-haired (Euthycomi) and three as -curly-haired (Euplocomi). We shall in the first place consider the -former, which includes the primaeval inhabitants of the greater part of -Asia and the whole of America. - -The lowest stage of all straight-haired men, and on the whole perhaps of -all the still living human species, is occupied by the _Australian_, or -_Austral-negro_ (Homo Australis). This species seems to be exclusively -confined to the large island of Australia; it resembles the genuine -African Negro by its black or brownish black hair, and the offensive -smell of the skin, by its very slanting teeth and long-headed form of -skull, the receding forehead, broad nose, protruding lips, and also by -the entire absence of calves. On the other hand Australians differ from -genuine Negroes as well as from their nearest neighbours the Papuans, by -the much weaker and more delicate structure of their bones, and more -especially by the formation of the hair of their heads, which is not -woolly and frizzled, but either quite lank or only slightly curled. The -very low stage of bodily and mental development of the Australian is -perhaps not altogether original, but has arisen by degeneration, that -is, by adaptation to the very unfavourable conditions of existence in -Australia. They probably immigrated to their present home from the north -or north-west, as a very early offshoot of the Euthycomi. They are -probably more closely related to the Dravidas, and hence to the -Euplocomi, than the other Euthycomi. The very peculiar language of the -Australians is broken up into numerous small branches, which are grouped -into a northern and a southern class. - -The _Malay_ (Homo Malayus), the brown race of ethnographers, although -not a large species, is important in regard to its genealogy. An extinct -south Asiatic human species, very closely related to the Malays of the -present day, must probably be looked upon as the common primary form of -this and the following higher human species. We will call this -hypothetical primary species, Primaeval Malays, or Promalays. The Malays -of the present day are divided into two widely dispersed races, the -_Sundanesians_, who inhabit Malacca, the Sunda Islands (Sumatra, Java, -Borneo, etc.) and the Philippine Islands, and the _Polynesians_, who are -dispersed over the greater portion of the Pacific Archipelago. The -northern boundary of their wide tract of distribution is formed on the -east by the Sandwich Islands (Hawai), and on the west by the Marian -Islands (Ladrones); the southern boundary on the east is formed by the -Mangareva Archipelago, and on the west by New Zealand. The inhabitants -of Madagascar are an especial branch of Sundanesians who have been -driven to the far west. This wide pelagic distribution of the Malays is -explained by their partiality for nautical life. Their primaeval home is -the south-eastern portion of the Asiatic continent, from whence they -spread to the east and south, and drove the Papuans before them. The -Malays, in the formation of body, are nearest akin to the Mongols, but -are also nearly allied to the curly-haired Mediterranese. They are -generally short-headed, more rarely medium-headed, and very rarely -long-headed. Their hair is black and stiff, but frequently somewhat -curled. The colour of their skin is brown, sometimes yellowish, or of a -cinnamon colour, sometimes reddish or copper brown, more rarely dark -brown. In regard to the formation of face, Malays in a great measure -form an intermediate stage between the Mongols and the Mediterranese; -they can frequently not be distinguished from the latter. Their face is -generally broad, with prominent nose and thick lips, the opening for -their eyes not so narrowly cut and slanting as in Mongols. The near -relationship between all Malays and Polynesians is proved by their -language, which indeed broke up at an early period into many small -branches, but still can always be traced to a common and quite peculiar -primaeval language. - -The _Mongol_ (Homo Mongolus) is, next to the Mediterranese, the richest -in individuals. Among them are all the inhabitants of the Asiatic -Continent, excepting the Hyperboreans in the north, the few Malays in -the south-east (Malacca), the Dravidas in Western India, and the -Mediterranese in the south-west. In Europe this species of men is -represented by the Fins and Lapps in the north, by the Osmanlis in -Turkey, and the Magyars in Hungary. The colour of the Mongol is always -distinguished by a yellow tone, sometimes a light pea green, or even -white, sometimes a darker brownish yellow. Their hair is always stiff -and black. The form of their skull is, in the great majority of cases, -decidedly short (especially in Kalmucks, Baschkirs, etc.) but frequently -of medium length (Tartars, Chinese, etc.) But among them we never meet -with genuine long-headed men. The narrow openings of their eyes, which -are generally slanting, their prominent cheek bones, broad noses, and -thick lips are very striking, as well as the round form of their faces. -The language of the Mongols is probably traceable to a common primaeval -language; but the monosyllabic languages of the Indo-Chinese races, and -the polysyllabic languages of the other Mongol races, stand in contrast -as two main branches which separated at an early time. The monosyllabic -tribes of the Indo-Chinese include the Tibetans, Birmans, Siamese, and -Chinese. The other polysyllabic Mongols are divided into three races, -namely: (1) the Coreo-Japanese (Coreans and Japanese); (2) the Altaians -(Tartars, Kirgises, Kalmucks, Buriats, Tungusians); and (3) the Uralians -(Samoiedes, Fins). The Magyars of Hungary are descended from the Fins. - -The _Polar men_ (Homo Arcticus) must be looked upon as a branch of the -Mongolian human species. We comprise under this name the inhabitants of -the Arctic Polar lands of both hemispheres, the Esquimaux (and -Greenlanders) in North America, and the Hyperboreans in north-eastern -Asia (Jukagirs, Tschuksches, Kuriaks, and Kamtschads). By adaptation to -the Polar climate, this human race has become so peculiarly transformed -that it may be considered as a distinct species. Their stature is low -and of a square build; the formation of their skull of medium size or -even long; their eyes narrow and slanting like the Mongols; their -cheek-bones prominent, and their mouth wide. Their hair is stiff and -black; the colour of their skin is of a light or dark brown tinge, -sometimes more inclined to white or to yellow, like that of the Mongols, -sometimes more to red, like that of the Americans. The languages of -Polar men are as yet little known, but they differ both from the -Mongolian and from the American. Polar men must probably be regarded as -a remnant and a peculiarly adapted branch of that tribe of Mongols which -emigrated from north-eastern Asia to North America, and populated that -part of the earth. - -At the time of the discovery of America, that part of the earth was -peopled (setting aside the Esquimaux) only by a single human species, -namely, by the _Redskins_, or _Americans_ (Homo Americanus). Of all -other human species they are most closely related to the two preceding. -The form of their skull is generally a medium one, rarely short or -long-headed. Their forehead broad and very low; their nose large, -prominent, and frequently aquiline; their cheek-bones prominent; their -lips rather thin than thick. The colour of their skin is characterised -by a red fundamental tint, which is, however, sometimes pure copper-red, -or light red, sometimes a deeper reddish brown, yellow brown or olive -brown. The numerous languages of the various American races and tribes -are extremely different, yet they agree in their original foundation. -Probably America was first peopled from north-eastern Asia by the same -tribe of Mongols from whom the Polar men (Hyperboreans and Esquimaux) -have also branched. This tribe first spread in North America, and from -thence migrated over the isthmus of Central America down to South -America, at the extreme south of which the species degenerated very -much by adaptation to the very unfavourable conditions of existence. But -it is also possible that Mongols and Polynesians immigrated from the -west and mixed with the former tribe. In any case the aborigines of -America came over from the Old World, and did not, as some suppose, in -any way originate out of American apes. Catarrhini, or Narrow-nosed -Apes, never at any period existed in America. - -The three human species still to be considered--the Dravidas, Nubians, -and Mediterranese--agree in several characteristics which seem to -establish a close relationship between them, and distinguish them from -the preceding species. The chief of these characteristics is the strong -development of the beard, which in all other species is either entirely -wanting or but very scanty. The hair of their heads is generally not so -lank and smooth as in the five preceding species, but in most cases more -or less curly. Other characteristics also seem to favour our classing -them in one main group of curly-haired men (Euplocomi). - -The _Dravida man_ (Homo Dravida) seems to stand very near the common -primary form of the Euplocomi, and perhaps of Lissotrichi. At present -this primaeval species is only represented by the Deccan tribes in the -southern part of Hindostan, and by the neighbouring inhabitants of the -mountains on the north-east of Ceylon. But in earlier times this race -seems to have occupied the whole of Hindostan, and to have spread even -further. It shows, on the one hand, traits of relationship to the -Australians and Malays; on the other, to the Mongols and Mediterranese. -Their skin is either of a light or dark brown colour; in some tribes, of -a yellowish brown, in others, almost black brown. The hair of their -heads, as in Mediterranese, is more or less curled, neither quite -smooth, like that of the Euthycomi, nor actually woolly, like that of -the Ulotrichi. The strong development of the beard is also like that of -the Mediterranese. The oval form of face seems partly to be akin to that -of the Malays, partly to that of the Mediterranese. Their forehead is -generally high, their nose prominent and narrow, their lips slightly -protruding. Their language is now very much mixed with Indo-Germanic -elements, but seems to have been originally derived from a very peculiar -primaeval language. - -The _Nubian_ (Homo Nuba) has caused ethnographers no fewer difficulties -than the Dravida species. By this name we understand not merely the real -Nubians (Schangallas, or Dongolese), but also their near kinsmen, the -Fulas, or Fellatas. The real Nubians inhabit the countries of the Upper -Nile (Dongola, Schangalla, Barabra, Cordofan); the Fulas, or Fellatas, -on the other hand, have thence migrated far westward, and now inhabit a -broad tract in the south of the western Sahara, hemmed in between the -Soudanians in the north and the Nigritos in the south. The Nubian and -Fula races are generally either classed with negroes or with the Hamitic -races (thus with Mediterranese), but are so essentially different from -both that they must be regarded as a distinct species. In former times -they very probably occupied a large part of north-eastern Africa. The -skin of the Nubian and Fula races is of a yellowish or reddish brown -colour, more rarely dark brown or approaching to black. Their hair is -not woolly but curled, frequently even quite smooth; its colour is dark -brown or black. Their beard is much more strongly developed than in -negroes. The oval formation of their faces approaches more to the -Mediterranean than to the Negro type. Their forehead is high and broad, -their nose prominent and not flat, their lips not so protruding as in -the negro. The language of the Nubian races seems to possess no -relationship to those of genuine negroes. - -The _Caucasian_, or _Mediterranean man_ (Homo Mediterraneus), has from -time immemorial been placed at the head of all races of men, as the most -highly developed and perfect. It is generally called the Caucasian race, -but as among all the varieties of the species, the Caucasian branch is -the least important, we prefer the much more suitable appellation -proposed by Friedrich Mueller, namely, that of Mediterranean, or Midland -men. For the most important varieties of this species, which are -moreover the most eminent actors in what is called "Universal History," -first rose to a flourishing condition on the shores of the -Mediterranean. The former area of the distribution of this species is -expressed by the name of "Indo-Atlantic" species, whereas at present it -is spread over the whole earth, and is overcoming most of the other -species in the struggle for existence. In bodily as well as in mental -qualities, no other human species can equal the Mediterranean. This -species alone (with the exception of the Mongolian) has had an actual -history; it alone has attained to that degree of civilization which -seems to raise man above the rest of nature. - -The characteristics which distinguish the Mediterranean from the other -species of the race are well known. The chief of the external features -is the light colour of the skin, which however exhibits all shades, from -pure white or reddish white, through yellow or yellowish brown to dark -brown or even black brown. The growth of the hair is generally strong, -the hair of the head more or less curly, the hair of the beard stronger -than in any of the other species. The form of the skull shows a great -development in breadth; medium heads predominate upon the whole, but -long and short heads are also widely distributed. It is only in this one -species of men that the body as a whole attains that symmetry in all -parts, and that equal development, which we call the type of perfect -human beauty. The languages of all the races of this species can by no -means be traced to a single common primaeval language; we must at least -assume four radically different primaeval languages. In accordance with -this we must also assume within this one species four different races, -which are only connected at their root. Two of these races, the Basques -and Caucasians, now exist only as small remnants. The Basques, which in -earlier times peopled the whole of Spain and the south of France, now -inhabit but a narrow tract of land on the northern coast of Spain, on -the Bay of Biscay. The remnant of the Caucasian race (the Daghestans, -Tschercassians, Mingrelians, and Georgians) are now confined to the -districts of Mount Caucasus. The language of the Caucasians as well as -that of the Basques is entirely peculiar, and can be traced neither to -the Semitic nor to the Indo-Germanic primaeval languages. - -Even the languages of the two principal races of the Mediterranean -species--the Semitic and Indo-Germanic--cannot be traced to a common -origin, and consequently these two races must have separated at a very -early period. Semites and Indo-Germani are descended from different -ape-like men. The _Semitic_ race likewise separated at a very early -period into two diverging branches, namely, into the _Egyptian_ and -_Arabic_ branches. The _Egyptian_, or _African_ branch, the -_Dyssemites_--which sometimes under the name of Hamites are entirely -separated from the Semites--embraces the large group of Berbers, who -occupy the whole of north Africa, and in earlier times also peopled the -Canary Islands, and, finally, also the group of the Ethiopians, the -Bedsha, Galla, Danakil, Somali, and other tribes which occupy all the -north-eastern shores of Africa as far as the equator. The _Arabic_, or -_Asiatic_ branch, that is, the _Eusemites_, also called Semites in a -narrow sense, embrace the inhabitants of the large Arabian peninsula, -the primaeval family of genuine Arabians ("primaeval type of the -Semites"), and also the most highly developed Semitic groups, the Jews, -or Hebrews, and the Aramaeans--the Syrians and Chaldaeans. A colony of the -southern Arabs (the Himjarites), which crossed the Straits of -Bab-el-Mandeb, has peopled Abyssinia. - -Lastly, the Indo-Germanic race, which has far surpassed all the other -races of men in mental development, separated at a very early period, -like the Semitic, into two diverging branches, the _Ario-Romaic_ and the -_Slavo-Germanic_ branches. Out of the former arose on the one hand the -_Arians_ (Indians and Iranians), on the other the _Graeco-Roman_ (Greeks -and Albanians, Italians and Kelts). Out of the Slavo-Germanic branch -were developed on the one hand the _Slavonians_ (Russian, Bulgarian, -Tchec, and Baltic tribes), on the other the _Germani_ (Scandinavians and -Germans, Netherlanders and Anglo-Saxons). August Schleicher has -explained, in a very clear genealogical form, how the further -ramifications of the Indo-Germanic race may be accurately traced in -detail on the basis of comparative philology.(6) (Compare p. 331.) - -The total number of human individuals at present amounts to between -1,300 and 1,400 millions. In our Tabular Survey (p. 333) 1,350 millions -has been assumed as the mean number. According to an approximate -estimate, as far as such a thing is possible, 1,200 millions of these -are straight-haired men, only about 150 millions woolly-haired. The most -highly developed species, Mongols and Mediterranese, far surpass all the -other human species in numbers of individuals, for each of them alone -comprises about 550 millions. (Compare Friederich Mueller's Ethnography, -p. 30.) Of course the relative number of the twelve species fluctuates -every year, and that too according to the law developed by Darwin, that -in the struggle for life the more highly developed, the more favoured -and larger groups of forms, possess the positive inclination and the -certain tendency to spread more and more at the expense of the lower, -more backward, and smaller groups. Thus the Mediterranean species, and -within it the Indo-Germanic, have by means of the higher development of -their brain surpassed all the other races and species in the struggle -for life, and have already spread the net of their dominion over the -whole globe. It is only the Mongolian species which can at all -successfully, at least in certain respects, compete with the -Mediterranean. Within the tropical regions, Negroes, Kaffres, and -Nubians, as also the Malays and Dravidas, are in some measure protected -against the encroachments of the Indo-Germanic tribes by their being -better adapted for a hot climate; the case of the arctic tribes of the -polar regions is similar. But the other races, which as it is are very -much diminished in number, will sooner or later completely succumb in -the struggle for existence to the superiority of the Mediterranean -races. The American and Australian tribes are even now fast approaching -their complete extinction, and the same may be said of the Papuans and -Hottentots. - -In now turning to the equally interesting and difficult question of the -relative _connection_, _migration_, and _primaeval home_ of the twelve -species of men, I must premise the remark that, in the present state of -our anthropological knowledge, any answer to this question must be -regarded only as a provisional hypothesis. This is much the same as with -any genealogical hypothesis which we may form of the origin of kindred -animal and vegetable species, on the basis of the "Natural System." But -the necessary uncertainty of these special hypotheses of descent, in no -way shakes the absolute certainty of the general theory of descent. Man, -we may feel certain, is descended from Catarrhini, or narrow-nosed apes, -whether we agree with the polyphylites, and suppose each human species, -in its primaeval home, to have originated out of a special kind of ape; -or whether, agreeing with the monophylites, we suppose that all the -human species arose only by differentiation from a single species of -primaeval man (Homo primigenius). - -For many and weighty reasons we hold the monophyletic hypothesis to be -the more correct, and we therefore assume a _single primaeval home_ for -mankind, where he developed out of a long since extinct anthropoid -species of ape. Of the five now existing continents, neither Australia, -nor America, nor Europe can have been this primaeval home, or the -so-called "Paradise," the "cradle of the human race." Most -circumstances indicate southern Asia as the locality in question. -Besides southern Asia, the only other of the now existing continents -which might be viewed in this light is Africa. But there are a number of -circumstances (especially chorological facts) which suggest that the -primaeval home of man was a continent now sunk below the surface of the -Indian Ocean, which extended along the south of Asia, as it is at -present (and probably in direct connection with it), towards the east, -as far as further India and the Sunda Islands; towards the west, as far -as Madagascar and the south-eastern shores of Africa. We have already -mentioned that many facts in animal and vegetable geography render the -former existence of such a south Indian continent very probable. -(Compare vol. i. p. 361.) Sclater has given this continent the name of -Lemuria, from the Semi-apes which were characteristic of it. By assuming -this Lemuria to have been man's primaeval home, we greatly facilitate the -explanation of the geographical distribution of the human species by -migration. (Compare the Table of Migrations XV., and its explanation at -the end.) - -We as yet know of no fossil remains of the hypothetical primaeval man -(Homo primigenius) who developed out of anthropoid apes during the -tertiary period, either in Lemuria or in southern Asia, or possibly in -Africa. But considering the extraordinary resemblance between the lowest -woolly-haired men, and the highest man-like apes, which still exist at -the present day, it requires but a slight stretch of the imagination to -conceive an intermediate form connecting the two, and to see in it an -approximate likeness to the supposed primaeval men, or ape-like men. The -form of their skull was probably very long, with slanting teeth; their -hair woolly; the colour of their skin dark, of a brownish tint. The hair -covering the whole body was probably thicker than in any of the still -living human species; their arms comparatively longer and stronger; -their legs, on the other hand, knock-kneed, shorter and thinner, with -entirely undeveloped calves; their walk but half erect. - -This ape-like man very probably did not as yet possess an actual human -language, that is, an articulate language of ideas. Human speech, as has -already been remarked, most likely originated after the divergence of -the primaeval species of men into different species. The number of -primaeval languages is, however, considerably larger than the number of -the species of men above discussed. For philologists have hitherto not -been able to trace the four primaeval languages of the Mediterranean -species, namely, the Basque, Caucasian, Semitic, and Indo-Germanic to a -single primaeval language. As little can the different Negro languages be -derived from a common primaeval language; hence both these species, -Mediterranean and Negro, are certainly _polyglottonic_, that is, their -respective languages originated after the divergence of the speechless -primary species into several races had already taken place. Perhaps the -Mongols, the Arctic and American tribes, are likewise polyglottonic. The -Malayan species is, however, _monoglottonic_; all the Polynesian and -Sundanesian dialects and languages can be derived from a common, long -since extinct primaeval language, which is not related to any other -language on earth. All the other human species, Nubians, Dravidas, -Australians, Papuans, Hottentots, and Kaffres are likewise -monoglottonic. (Compare p. 333.) - -Out of speechless primaeval man, whom we consider as the common primary -species of all the others, there developed in the first place--probably -by natural selection--various species of men unknown to us, and now long -since extinct, and who still remained at the stage of speechless ape-men -(Alalus, or Pithecanthropus). Two of these species, a woolly-haired and -a straight-haired, which were most strongly divergent, and consequently -overpowered the others in the struggle for life, became the primary -forms of the other remaining human species. - -The main branch of woolly-haired men (Ulotrichi) at first spread only -over the southern hemisphere, and then emigrated partly eastwards, -partly westwards. Remnants of the eastern branch are the Papuans in New -Guinea and Melanesia, who in earlier times were diffused much further -west (in further India and Sundanesia), and it was not until a late -period that they were driven eastwards by the Malays. The Hottentots are -the but little changed remnants of the western branch; they immigrated -to their present home from the north-east. It was perhaps during this -migration that the two nearly related species of Caffres and Negroes -branched off from them; but it may be that they owe their origin to a -peculiar branch of ape-like men. - -The second main branch of primaeval straight-haired men (Lissotrichi), -which is more capable of development, has probably left a but little -changed remnant of its common primary form--which migrated to the -south-east--in the ape-like natives of Australia. Probably very closely -related to these latter are the South Asiatic _primaeval Malays_, or -_Promalays_, which name we have previously given to the extinct, -hypothetical primary form of the other six human species. Out of this -unknown common primary form there seem to have arisen three diverging -branches, namely, the true Malays, the Mongols, and the Euplocomi; the -first spread to the east, the second to the north, and the third -westwards. - -The primaeval home, or the "Centre of Creation," of the Malays must be -looked for in the south-eastern part of the Asiatic continent, or -possibly in the more extensive continent which existed at the time when -further India was directly connected with the Sunda Archipelago and -eastern Lemuria. From thence the Malays spread towards the south-east, -over the Sunda Archipelago as far as Borneo, then wandered, driving the -Papuans before them, eastwards towards the Samoa and Tonga Islands, and -thence gradually diffused over the whole of the islands of the southern -Pacific, to the Sandwich Islands in the north, the Mangareva in the -east, and New Zealand in the south. A single branch of the Malayan tribe -was driven far westwards and peopled Madagascar. - -The second main branch of primaeval Malays, that is, the Mongols, at -first also spread in Southern Asia, and, radiating to the east, north, -and north-west, gradually peopled the greater part of the Asiatic -continent. Of the four principal races of the Mongol species, the -Indo-Chinese must perhaps be looked upon as the primary group, out of -which at a later period the other Coreo-Japanese and Ural-Altaian races -developed as diverging branches. The Mongols migrated in many ways from -western Asia into Europe, where the species is still represented in -northern Russia and Scandinavia by the Fins and Lapps, in Hungary by the -kindred Magyars, and in Turkey by the Osmanlis. - - PEDIGREE OF SEMITES - - Amharites +Moors+ +Jews+ - | Tigrites | Samaritans (Hebrews) - | Harrarites | | | Phoenicians | - | | | | | | | - | | | | Chaldeans | | - \-------v------/ | Syrians | \----v-----/ - +Abyssinians+ | | | Canaanites - Ekilians | | | | (+Palestinese+) - | | | \---v---/ | - | Himiarites | +Aramaeans+ | - | | | | | - | | | | | - \---v---/ | | | - +South+ +North+ \----------v------------/ - +Arabians+ +Arabians+ +Primaeval Jews+ - | | +North-Semites+ - \-------v-----------/ | - +Arabians+ (+South Semites+) | - | | - | | - \----------------------------------------v-----/ - Guanchites +Eusemites+ (+Primaeval Semites+) - Schuluhs | Algerians (Semites in a narrow sense) - | | Tunese | \------------------------v---/ - | | | | | - | | | | Tripolitans | - \---v---/ | | | | - Moroccans \----v----/ | +Tuaric+ | - | Cabyles | (+Imoscharh+) | - | | | | | - \--------------v--------------/ | | - +Berbers+ (+Amazirh+) | | - Gallites | | | - | Somalites | | | - | | \------------v-------------/ | - \---v---/ Bedschites +Libians+ Babylonians +Eusemites+ - | | Egyptians | Primaeval | | - | | (+Copts+) | Phoenicians | Assyrians | - \----v-----/ | | | | | | - +Ethiopians+ | | | | | | - | | | | | | | - | | | | | | | - \------------v----------/ \-------v------/ | - +Ancient Egyptians+ +Mesopotamians+ | - | (extinct) | - | | | - | | | - \------------v-----------------/ | - +Hamites+ (+Dyssemites+) | - | | - \---------------v--------------/ - +Semites+ - - ---------------------------------------------------------------- - -PEDIGREE OF THE INDO-GERMANI - - Ancient Prussians +Anglo-Saxons+ +High Germans+ - Lithuanians | | Low Germans | - | Letts | | | Netherlanders | - | | | | | | | - | | | | | | | - \-----v----/ | | \----v---/ | - | | | Ancient Saxons | - | | | | | - \-------v-/ | | | - +Baltic Races+ \------v----/ | - Sorbians, or | Saxons Friesians | - Wends | | | | - Poles | | | | | - | | | \----v----/ | - Czecs | | | +Low Germans+ | - | | | | | | - | | | | | | - \--v-----------/ | Scandinavians \-----v------/ - West Sclavonians | | Goths +Germans+ - | Russians | | | | - | South | | | | | - | Sclavonians| | \----v----------------------/ - | | | | +Primaeval Germans+ Ancient Britons - | | | | | | - | \---v---/ | | Ancient Scots | Gauls - | South-eastern | | +Romans+ Irish | | | - | Sclavonians | | | | | | | - | | | | | | | \--v-/ - | | | | | \--v-/ Brittanese - | | | | | +Latins+ Gaels | - \----v----/ | | | | | | - +Sclavonians+ | | | | | | - | | | \--v--/ \----v-----/ - | | | Italians +Kelts+ - \------v------/ | | | - +Sclavo-Letts+ | | | - | | \--------v---------/ - | | +Italo-Kelts+ - \--v-----------------/ | - +Sclavo-Germans+ +Albanese+ +Greeks+ | - | | | | - | | | | - | \----v-----/ | - | +Primaeval Thracians+ | - | +Indians+ | | - | | +Iranians+ \-------v-------/ - | | | +Graeco-Romans+ - | \---v--/ | - | +Arians+ | - | | | - | \-----v----------/ - | +Ario-Romans+ - | | - \-------v-------/ - +Indo-Germans+ - - -On the other hand, a branch of the Mongols migrated from north-eastern -Asia to America, which was probably in earlier times connected with the -former continent by a broad isthmus. The Arctic tribes, or Polar men, -the Hyperboreans of north-eastern Asia, and the Esquimaux of the -extreme north of America, must probably be regarded as an offshoot of -this branch, which became peculiarly degenerated by unfavourable -conditions of existence. The principal portion of the Mongolian -immigrants, however, migrated to the south, and gradually spread over -the whole of America, first over the north, later over South America. - -The third and most important main branch of primaeval Malays, the -curly-haired races, or Euplocomi, have probably left in the Dravidas of -Hindostan and Ceylon, that species of man which differs least from the -common primary form of the Euplocomi. The principal portion of the -latter, namely, the Mediterranean species, migrated from their primaeval -home (Hindostan?) westwards, and peopled the shores of the -Mediterranean, south-western Asia, north Africa, and Europe. The -Nubians, in the north-east of Africa, must perhaps be regarded as an -offshoot of the primaeval Semitic tribes, who migrated far across central -Africa almost to the western shores. The various branches of the -Indo-Germanic race have deviated furthest from the common primary form -of ape-like men. During classic antiquity and the middle ages, the -Romanic branch (the Graeco-Italo-Keltic group), one of the two main -branches of the Indo-Germanic species, outstripped all other branches in -the career of civilization, but at present the same position is occupied -by the Germanic. Its chief representatives are the English and Germans, -who are in the present age laying the foundation for a new period of -higher mental development, in the recognition and completion of the -theory of descent. The recognition of the theory of development and the -monistic philosophy based upon it, forms the best criterion for the -degree of man's mental development. - - -SYSTEMATIC SURVEY OF THE TWELVE HUMAN SPECIES. - - N.B.--Column A denotes the Average Number of the Population in - millions. Column B shows the Degree of the Phyletic Development of - the Species, thus Pr = Progressive Diffusion; Co = Comparative - Stability; Re = Retrogression and Extinction. Column C denotes the - Character of the Primaeval Language; Mn (Monoglottonic) signifies that - the Species had one Simple Primaeval Language; Pl (Polyglottonic) a - Compound Primaeval Language. - - - ----------------------+--------------------+--------+-------+--------+----------------------------- - _Tribe._ | _Human | A. | B. | C. | _Home._ - | Species._ | | | | - ----------------------+--------------------+--------+-------+--------+----------------------------- - - TUFT-HAIRED { | | | - +Lophocomi+ { 1. PAPUAN | 2 | Re | Mn { New Guinea and Melanesia, - { | | | { Philippine Islands, Malacca - (about 2 millions) { 2. HOTTENTOT | 1/20 | Re | Mn { The extreme south of Africa - { | | | { (The Cape) - | | | - FLEECY-HAIRED { 3. KAFFRE | 20 | Pr | Mn { South Africa (between 30 deg. - { | | | { S. Lat. and 5 deg. N. Lat.) - +Eriocomi+ { 4. NEGRO | 130 | Pr | Pl { Central Africa (between the - { | | | { Equator and 30 deg. N. Lat.) - (about 150 millions) { | | | - | | | - { 5. AUSTRALIAN | 1/12 | Re | Mn { Australia - { 6. MALAY | 30 | Co | Mn { Malacca, Sundanesia, Polynesia, - { | | | { and Madagascar - STRAIGHT-HAIRED { | | | - +Euthycomi+ { 7. MONGOL | 550 | Pr | Mn? { The greater part of Asia - { | | | { and northern Europe - (about 600 millions) { 8. ARCTIC | 1/25 | Co | Pl? { The extreme north-east of - { MAN | | | { Asia and the extreme north - { | | | { of America - { 9. AMERICAN | 12 | Re | Mn? { The whole of America with - { | | | { the exception of the extreme - { | | | { north - | | | - { 10. DRAVIDAS | 34 | Co | Mn { South Asia (Hindostan and - { | | | { Ceylon) - { | | | - { 11. NUBIAN | 10 | Co | Mn? { Central Africa (Nubia and - { | | | { Fula-land) - CURLY-HAIRED { | | | { In all parts of the world, - { | | | { having migrated from South - +Euplocomi+ { 12. MEDITERRANEAN | 550 | Pr | Pl { Asia to North Africa and - { | | | { South Europe - (about 600 millions) { | | | - { | | | - | | | { In all parts of the world, - 13. HYBRIDS | 11 | Pr | Pl { but predominating in America - OF THE | | | { and Asia - SPECIES | | | - --------------------+--------+ | - TOTAL 1350 - - - - -CHAPTER XXIV. - -OBJECTIONS AGAINST, AND PROOFS OF THE TRUTH OF, THE THEORY OF DESCENT. - - - Objections to the Doctrine of Filiation.--Objections of Faith - and Reason.--Immeasurable Length of the Geological - Periods.--Transition Forms between Kindred Species.--Dependence - of Stability of Form on Inheritance, and of the Variability of - Form on Adaptation.--Origin of very complicated Arrangement of - Organisation.--Gradual Development of Instincts and Mental - Activities.--Origin of a priori Knowledge from Knowledge a - posteriori.--The Knowledge requisite for the Correct - Understanding of the Doctrine of Filiation.--Necessary - Interaction between Empiricism and Philosophy.--Proofs of the - Theory of Descent.--Inner Causal Connection between all the - Biological Series of Phenomena.--The Direct Proof of the Theory - of Selection.--Relation of the Theory of Descent to - Anthropology.--Proofs of the Animal Origin of Man.--The Pithecoid - Theory as an Inseparable Part of the Theory of - Descent.--Induction and Deduction.--Gradual Development of the - Human Mind.--Body and Mind.--Human Soul and Animal Soul.--A Glance - at the Future. - - -If in these chapters I may hope to have made the Theory of Descent seem -more or less probable, and to have even convinced some of my readers of -its unassailable truth, yet I am by no means unconscious that, to most -of them, during the perusal of my explanations, a number of objections -more or less well founded must have occurred. Hence it seems absolutely -necessary at the conclusion of our examination to refute at least the -most important of these, and at the same time, on the other hand, once -more to set forth the convincing arguments which bear testimony to the -truth of the theory of development. - -The objections which are raised to the doctrine of descent may be -divided into two large groups: objections of faith and objections of -reason. The objections of the first group originate in the infinitely -varied forms of faith held by human individuals, and need not here be -taken into consideration at all. For, as I have already remarked at the -beginning of this book, science, as an objective result of sensuous -experience, and of the striving of human reason after knowledge, has -nothing whatever to do with the subjective ideas of faith, which are -preached by a single man as the direct inspirations or revelations of -the Creator, and then believed in by the dependent multitude. This -belief, very different in different nations, only begins, as is well -known, where science ends. Natural Science believes, according to the -maxim of Frederick the Great, "that every one may go to heaven in his -own fashion," and only necessarily enters into conflict with particular -forms of faith where they appear to set a limit to free inquiry and a -goal to human knowledge, beyond which we are not to venture. Now this is -certainly the case here in the highest degree, for the Theory of -Development applies itself to the solution of the greatest of scientific -problems--that of the creation, the coming into existence of things; -more especially the origin of organic forms, and of man at their head. -It is here certainly the right as well as the sacred duty of free -inquiry, to fear no human authority, and courageously to raise the veil -from the image of the Creator, unconcerned as to what natural truth may -lie concealed beneath. The only Divine revelation which we recognise as -true, is written everywhere in nature, and to every one with healthy -senses and a healthy reason it is given to participate in the unerring -revelation of this holy temple of nature, by his own inquiry and -independent discovery. - -If we, therefore, here disregard all objections to the Doctrine of -Descent which may be raised by the priests of the different religious -faiths, we must nevertheless endeavour to refute the most important of -those objections which seem more or less founded on science, and which -we grant might, at first sight, to a certain extent captivate us and -deter us from adopting the Doctrine of Descent. Many persons seem to -think the length of the periods of time required the most important of -these objections. We are not accustomed to deal with such immense -periods as are necessary for the history of the creation. It has already -been mentioned that the periods, during which species originated by -gradual transmutation, must not be calculated by single centuries, but -by hundreds and by millions of centuries. Even the thickness of the -stratified crust of the earth, the consideration of the immense space of -time which was requisite for its deposition from water, taken together -with the periods of elevation between the periods of depression, -indicate a duration of time of the organic history of the earth which -the human intellect cannot realize. We are here in much the same -position as an astronomer in regard to infinite space. In the same way -as the distances between the different planetary systems are not -calculated by miles but by Sirius-distances, each of which comprises -millions of miles, so the organic history of the earth must not be -calculated by thousands of years, but by palaeontological or geological -periods, each of which comprises many thousands of years, and perhaps -millions, or even, milliards, of thousands of years. It is of little -importance how high the immeasurable length of these periods may be -approximately estimated, because we are in fact unable with our limited -power of imagination to form a true conception of these periods, and -because we do not as in astronomy possess a secure mathematical basis -for fixing the approximate length of duration in numbers. But we most -positively deny that we see any objection to the theory of development -in the extreme length of these periods which are so completely beyond -the power of our imagination. It is, on the contrary, as I have already -explained in one of the preceding chapters, most advisable, from a -strictly philosophical point of view, to conceive these periods of -creation to be as long as possible, and we are by so much the less in -danger of losing ourselves in improbable hypotheses, the longer we -conceive the periods for organic processes of development to have been. -The longer, for example, we conceive the Permian period to have been, -the easier it will be for us to understand how the important -transmutations took place within it which so essentially distinguish the -fauna and flora of the Coal period from that of the Trias. The great -disinclination which most persons have to assume such immeasurable -periods, arises mainly from the fact of our having in early youth been -brought up in the notion that the whole earth is only some thousands of -years old. Moreover, human life, which at most attains the length of a -century, is an extremely short space of time, and is not suitable as a -standard for the measurement of geological periods. Our life is a -single drop in the ocean of eternity. The reader may call to mind the -duration of life of many trees which is more than fifty times as long; -for example, the dragon-trees (Dracaena) and monkey bread-fruit trees -(Adansonia), whose individual life exceeds a period of five thousand -years; and, on the other hand, the shortness of the individual life of -many of the lower animals, for example, the infusoria, where the -individual, as such, lives but a few days, or even but a few hours, -contrasts no less strongly with human longevity. This comparison brings -the relative nature of all measurement of time very clearly before us. -If the theory of development be true at all, there must certainly have -elapsed immense periods, utterly inconceivable to us, during which the -gradual historical development of the animal and vegetable kingdom -proceeded by the slow transformation of species. There is, however, not -a single reason for accepting a definite limit for the length of these -periods of development. - -A second main objection which many, and more especially systematic -zoologists and botanists, raise against the theory of descent, is that -no _transition forms_ between the different species can be found, -although according to the theory of descent they ought to be found in -great numbers. This objection is partly well founded and partly not so, -for there does exist an extraordinarily large number of transition forms -between living, as well as between extinct species, especially where we -have an opportunity of seeing and comparing very numerous individuals of -kindred species. Those careful investigators of individual species who -so frequently raise this objection are the very persons whom we -constantly find checked in their special series of investigations by the -really insuperable difficulty of sharply distinguishing individual -species. In all systematic works, which are in any degree thorough, one -meets with endless complaints, that here and there species cannot be -distinguished because of the excessive number of transition forms. Hence -every naturalist defines the limit and the number of individual species -differently. Some zoologists and botanists, as I mentioned (vol. i. p. -276), assume in one and the same group of organisms ten species, others -twenty, others a hundred or more, while other systematic naturalists -again look upon these different forms only as varieties of a single -"good" species. In most groups of forms there is, in fact, a -superabundance of transition forms and intermediate stages between the -individual species. - -It is true that in many species the forms of transition are actually -wanting, but this is easily explained by the principle of divergence or -separation, the importance of which I have already explained. The -circumstance that the struggle for existence is the more active between -two kindred forms the closer they stand to each other, must necessarily -favour the speedy extinction of the connecting intermediate forms -between the two divergent species. If one and the same species produce -diverging varieties in different directions, which become new species, -the struggle between these new forms and the common primary form will be -the keener the less they differ from one another; but the stronger the -divergence the less dangerous the struggle. Naturally therefore, it is -principally the connecting intermediate forms which will in most cases -quietly die out, while the most divergent forms remain and reproduce -themselves as distinct "new species." In accordance with this, we in -fact no longer find forms of transition leading to those groups which -are becoming extinct, as, for example, among birds, are the ostriches; -and among mammals, the elephants, giraffes, Semi-apes, Edentata, and -Ornithorhyncus. The groups of forms approaching their extinction no -longer produce new varieties, and naturally the species are what is -called "good," that is, the species are distinctly different from one -another. But in those animal groups where development and progress are -still active, where the existing species deviate into many new species -by the formation of new varieties, we find an abundance of transition -forms which cause the greatest difficulties to systematic naturalists. -This is the case, for example, among birds with the finches; among -mammals with most of the rodents (more especially with those of the -mouse and rat kind), with a number of the ruminants and with genuine -apes, more especially with the South American forms (Cebus), and many -others. The continual development of species by the formation of new -varieties here produces a mass of intermediate forms which connect the -so-called "good" species, which efface their boundaries, and render -their sharp specific distinction completely illusory. - -The reason that this nevertheless does not cause a complete confusion of -forms, nor a universal chaos in the structure of animals and vegetables, -lies simply in the fact that there is a continual counteraction at work -between progressive _adaptation_ on the one hand, and the _retentive_ -power of _inheritance_ on the other hand. The degree of stability and -variability manifested by every organic form is determined solely by the -actual condition of the equilibrium between these two opposite -functions. _Inheritance is the cause of the stability of species, -adaptation the cause of their modification._ When therefore some -naturalists say that, according to the theory of descent, there ought to -be a much greater variety of forms, and others again, that there ought -to be a much greater equality of forms, the former under-estimate the -value of inheritance and the latter the value of adaptation. _The ratio -of the interaction between inheritance and adaptation determines the -ratio of the stability and variability of organic species_ at any given -period. - -Another objection to the theory of descent, which, in the opinion of -many naturalists and philosophers is of great weight, is that it -ascribes the origin of organs which act for a definite purpose to causes -which are either aimless or mechanical in their operation. This -objection seems to be especially important in regard to those organs -which appear so excellently adapted for a certain definite purpose that -the most ingenious mechanician could not invent a more perfect organ for -the purpose. Such are, above all, the higher sense-organs of animals, -the eye and ear. If the eyes and auditory apparatus of the higher -animals alone were known to us, they would indeed cause great and -perhaps insurmountable difficulties. How could we come to the conclusion -that the extraordinarily great and wonderful degree of perfection and -conformity to purpose which we perceive in the eyes and ears of higher -animals, is in every respect attained solely by natural selection? -Fortunately, however, comparative anatomy and the history of -development help us here over all obstacles; for when in the animal -kingdom we follow the gradual progress towards perfection of the eyes -and ears, step by step, we find such a finely graduated series of -improvement, that we can clearly follow the development of the most -complex organs through all the stages towards perfection. Thus, for -example, the eye in the lowest animal is a simple spot of pigment which -does not yet reflect any image of external objects, but at most -perceives and distinguishes the different rays of light. Later, we find -in addition to this a sensitive nerve; then there gradually develops -within the spot of pigment the first beginning of the lens, a refractive -body which is now able to concentrate the rays of light and to reflect a -definite image. But all the composite apparatus for the movement of the -eye and its accommodation to variations of light and distance are still -absent, namely, the various refractive media, the highly differentiated -membrane of the optic nerve, etc., which are so perfectly constructed in -higher animals. Comparative anatomy shows us an uninterrupted succession -of all possible stages of transition, from the simplest organ to the -most highly perfected apparatus, so that we can form a pretty correct -idea of the slow and gradual formation of even such an exceedingly -complex organ. The like gradual progress which we observe in the -development of the organ during the course of individual development, -must have taken place in the historical (phyletic) origin of the organ. - -Many persons when contemplating these most perfect organs--which -apparently were purposely invented and constructed by an ingenious -Creator for a definite function, but which in reality have arisen by the -aimless action of natural selection--experience difficulties in arriving -at a rational understanding of them, which are similar to those -experienced by the uncivilized tribes of nature when contemplating the -latest complicated productions of engineering. Savages who see a ship of -the line, or a locomotive engine for the first time, look upon these -objects as the productions of a supernatural being, and cannot -understand how a man, an organism like themselves, could have produced -such an engine. Even the uneducated classes of our own race cannot -comprehend such an intricate apparatus in its actual workings, nor can -they understand its purely mechanical nature. Most naturalists, however, -as Darwin very justly remarks, stand in much the same position in regard -to the forms of organisms as do savages to ships of the line and to -locomotive engines. A rational understanding of the purely mechanical -origin of organic forms can only be acquired by a thorough and general -training in Biology, and by a special knowledge of comparative anatomy -and the history of development. - -Among the remaining objections to the Theory of Descent, I shall here -finally refer to and refute but one more, as in the eyes of many -unscientific men it seems to possess great weight. How are we, from the -Theory of Descent, to conceive of the origin of the mental faculties of -animals, and more especially their specific expressions--the so-called -instincts? This difficult subject has been so minutely discussed by -Darwin in a special chapter of his chief work (the seventh), that I must -refer the reader to it. We must regard instincts as essentially the -habits of the soul acquired by adaptation, and transmitted and fixed by -inheritance through many generations. Instincts are, therefore, like all -other habits, which, according to the laws of cumulative adaptation -(vol. i. p. 233) and established inheritance (vol. i. p. 216), lead to -the origin of new functions, and thus also to new forms of the organs. -Here, as everywhere, the interaction between function and organ goes -hand in hand. Just as the mental faculties of man have been acquired by -the progressive adaptation of the brain, and been fixed by continual -transmission by inheritance, so the instincts of animals, which differ -from them only in quantity, not in quality, have arisen by the gradual -perfecting of their mental organ, that is, their central nervous system, -by the interaction of Adaptation and Inheritance. Instincts, as is well -known, are inherited, but experiences and, consequently, new adaptations -of the animal mind, are also transmitted by inheritance; and the -training of domestic animals to different mental activities, which wild -animals are incapable of accomplishing, rests upon the possibility of -mental adaptation. We already know a series of examples, in which such -adaptations, after they had been transmitted through a succession of -generations, finally appeared as innate instincts, and yet they have -only been acquired from the ancestors of the animals. Inheritance has -here caused the result of training to become instinct. The -characteristic instincts of sporting dogs, shepherd's dogs, and other -domestic animals, and the natural instincts of wild animals, which they -possess at birth, were in the first place acquired by their ancestors by -adaptation. They may in this respect be compared to man's "knowledge a -priori," which, like all other knowledge, was originally acquired by our -remote ancestors, "a posteriori," by sensuous experience. As I have -already remarked, it is evident that "knowledge a priori" arose only by -long-enduring transmission, by inheritance of acquired adaptations of -the brain, out of originally empiric or experiential "knowledge a -posteriori" (vol. i. p. 31). - -The objections to the Theory of Descent here discussed and refuted are, -I believe, the most important which have been raised against it; I -consider also that I have sufficiently proved to the reader their -futility. The numerous other objections which besides these have been -raised against the Theory of Development in general, or against its -biological part, the Theory of Descent in particular, arise either from -such a degree of ignorance of empirically established facts, or from -such a want of their right understanding, and from such an incapacity to -draw the necessary conclusions, that it is really not worth the trouble -to go further into the refutation. There are only some general points in -regard to which, I should like, in a few words, to draw attention. - -In the first place I must observe, that in order thoroughly to -understand the doctrine of descent, and to be convinced of its absolute -truth, it is indispensable to possess a general knowledge of the whole -of the domain of biological phenomena. _The theory of descent is a -biological theory_, and hence it may with fairness and justice be -demanded that those persons who wish to pass a valid judgment upon it -should possess the requisite degree of biological knowledge. Their -possessing a special empiric knowledge of this or that domain of zoology -or botany, is not sufficient; they must possess a _general insight into -the whole series of phenomena_, at least in the case of one of the three -organic kingdoms. They ought to know what universal laws result from the -comparative morphology and physiology of organisms, but more especially -from comparative anatomy, from the individual and the palaeontological -history of development, etc.; and they ought to have some idea of the -deep _mechanical, causal connection_ between all these series of -phenomena. It is self-evident that a certain degree of general culture, -and especially a philosophical education, is requisite; which is, -however, unfortunately by many persons in our day, not considered at all -necessary. _Without the necessary connection of empirical knowledge and -the philosophical understanding of biological phenomena, it is -impossible to gain a thorough conviction of the truth of the Theory of -Descent._ - -Now I ask, in the face of this first preliminary condition for a true -understanding of the Theory of Descent, what we are to think of the -confused mass of persons who have presumed to pass a written or oral -judgment upon it of an adverse character? Most of them are unscientific -persons, who either know nothing of the most important phenomena of -Biology, or at least possess no idea of their deeper significance. What -should we say of an unscientific person who presumed to express an -opinion on the cell-theory, without ever having seen cells; or of one -who presumed to question the vertebral-theory, without ever having -studied comparative anatomy? And yet one may meet with such ridiculous -arrogance any day in the history of the biological Theory of Descent. -One hears thousands of unscientific and but half-educated persons pass a -final judgment upon it, although they know nothing either of botany or -of zoology, of comparative anatomy or the theory of tissues, of -palaeontology or embryology. Hence it happens, as Huxley well says, that -most of the writings published against Darwin are not worth the paper -upon which they are written. - -We might add that there are many naturalists, and even celebrated -zoologists and botanists, among the opponents of the Theory of Descent; -but these latter are mostly old stagers, who have grown grey in quite -opposite views, and whom we cannot expect, in the evening of their -lives, to submit to a reform in their conception of the universe, which -has become to them a fixed idea. - -It is, moreover, expressly to be remarked, that not only a general -insight into the _whole_ domain of biological phenomena, but also a -philosophical understanding of it, are the necessary preliminary -conditions for becoming convinced of and adopting the Theory of Descent. -Now we shall find that these indispensable preliminary conditions are, -unfortunately, by no means fulfilled by the majority of naturalists of -the present day. The immense amount of empirical facts with which the -gigantic advances of modern natural science have recently made us -acquainted has led to a prevailing inclination for the special study of -single phenomena and of small and narrow domains. This causes the -knowledge of other paths, and especially of Nature as a great -comprehensive whole, to be in most cases completely neglected. Every one -with sound eyes and a microscope, together with industry and patience -for study, can in our day attain a certain degree of celebrity by -microscopic "discoveries," without, however, deserving the name of a -naturalist. This name is deserved only by him who not merely strives to -_know_ the individual phenomena, but who also seeks to _discover_ their -causal connection. Even in our own day, most palaeontologists examine and -describe fossils without knowing the most important facts of embryology. -Embryologists, on the other hand, follow the history of development of a -particular organic individual, without having an idea of the -palaeontological history of the whole tribe, of which fossils are the -records. And yet these two branches of the organic history of -development--ontogeny, or the history of the individual, and phylogeny, -or the history of the tribe--stand in the closest causal connection, and -the one cannot be understood without the other. The same may be said of -the systematic and the anatomical part of Biology. There are even now, -in zoology and botany, many systematic naturalists who work with the -erroneous idea that it is possible to construct a natural system of -animals and plants simply by a careful examination of the external and -readily accessible forms of bodies, without a deeper knowledge of their -internal structure. On the other hand, there are anatomists and -histologists who think it possible to obtain a true knowledge of animal -and vegetable bodies merely by a most careful examination of the inner -structure of the body of some individual species, without the -comparative examination of the bodily form of all kindred organisms. And -yet here, as everywhere, the internal and external factors, to wit, -Inheritance and Adaptation, stand in the closest mutual relation, and -the individual can never be thoroughly understood without a comparison -of it with the whole of which it is a part. To those one-sided -specialists we should like in Goethe's words to say:-- - - We must, contemplating Nature, - Part as Whole, give equal heed to: - Nought is inward, nought is outward, - For the inner is the outer.[6] - -And again:-- - - Nature has neither kernel nor shell, - It is she that is All and All at once.[7] - -What is even more detrimental to the general understanding of nature as -a whole than this one-sided tendency, is _the want of a philosophical -culture_, and this applies to most of the naturalists of the present -day. The various errors of the earlier speculative nature-philosophy -made during the first thirty years of our century, have brought the -whole of philosophy into such bad repute with the exact empirical -naturalists, that they live in the strange delusion that it is possible -to erect the edifice of natural science out of mere facts, without their -philosophic connection; in short, out of mere knowledge, without the -understanding of it. But as a purely speculative and absolutely -philosophical system, which does not concern itself with the -indispensable foundation of empirical facts, becomes a castle in the -air, which the first real experiment throws to the winds; so, on the -other hand, a purely empirical system, constructed of nothing but facts, -remains a disorderly heap of stones, which will never deserve the name -of an edifice. Bare facts established by experience are nothing but rude -stones, and without their thoughtful valuation, without their -philosophic connection, no science can be established. As I have already -tried to impress upon my reader, the _strong edifice of true monistic -science_, or what is the same thing, the _Science of Nature, exists only -by the closest interaction, and the reciprocal penetration of philosophy -and empirical knowledge_. - -This lamentable estrangement between science and philosophy, and the -rude empiricism which is now-a-days unfortunately praised by most -naturalists as "exact science," have given rise to those strange freaks -of the understanding, to those gross insults against elementary logic, -and to that incapacity for forming the simplest conclusions which one -may meet with any day in all branches of science, but especially in -zoology and botany. It is here that the neglect of a philosophical -culture and training of the mind, directly avenges itself most -painfully. It is not to be wondered at that the deep inner truth of the -Theory of Descent remains a sealed book to those rude empiricists. As -the common proverb justly says: they cannot see the wood for the trees. -It is only by a more general philosophical study, and especially by a -more strictly logical training of the mind, that this sad state of -things can be remedied. (Compare Gen. Morph. i. 63; ii. p. 447.) - -If we rightly consider this circumstance, and if we further reflect upon -it in connection with the empirical foundation of the philosophical -theory of development, we shall at once see how we are placed respecting -the oft-demanded _proofs of the theory of descent_. The more the -doctrine of filiation has of late years made way for itself, and the -more all thoughtful, younger naturalists, and all truly -biologically-educated philosophers have become convinced of its inner -truth and absolute necessity, the louder have its opponents called for -actual proofs. The same persons who, shortly after the publication of -Darwin's work, declared it to be "a groundless, fantastic system," an -"arbitrary speculation," an "ingenious dream," now kindly condescend to -declare that the theory of descent certainly is a scientific -"_hypothesis_," but that it still requires to be "_proved_." When these -remarks are made by persons who do not possess the requisite -empirico-philosophical culture, nor the necessary knowledge in -comparative anatomy, embryology, and palaeontology, we cannot be much -offended, and we refer them to the study of those sciences. But when -similar remarks are made by acknowledged specialists, by teachers of -zoology and botany, who certainly ought to possess a general insight -into the whole domain of their science, or who are actually familiar -with the facts of those scientific domains, then we are really at a loss -what to say. Those who are not satisfied with the treasures of our -present empirical knowledge of nature as a basis on which to establish -the Theory of Descent, will not be convinced by any other facts which -may hereafter be discovered; for we can conceive no circumstances which -would furnish stronger or a more complete testimony to the truth of the -doctrine of filiation than is even now seen, for example, in the -well-known facts of comparative anatomy and ontogeny. I must here again -direct attention to the fact, _that all the great and general laws, and -all the comprehensive series of phenomena of the most different domains -of biology can only be explained and understood by the Theory of -Development_ (and especially by its biological part, the Theory of -Descent), and that without it they remain completely inexplicable and -incomprehensible. _The internal causal connection_ between them all -proves the Theory of Descent to be the greatest _inductive law_ of -Biology. - -Before concluding, I will once more name all those series of inductions, -all those general laws of Biology, upon which this comprehensive law of -development is firmly based. - -(1.) _The palaeontological history of the development of organisms_, the -gradual appearance and the historical succession of the different -species and groups of species, the empirical laws of the palaeontological -change of species, as furnished to us by the science of fossils, and -more especially the _progressive differentiation and perfecting_ of -animal and vegetable groups in the successive periods of the earth's -history. - -(2.) _The individual history of development of organisms_, embryology -and metamorphology, the gradual changes in the slow development of the -body and its particular organs, especially _the progressive -differentiation and perfecting_ of the organs and parts of the body in -the successive periods of the individual development. - -(3.) _The inner causal connection between ontogeny and phylogeny_, the -parallelism between the individual history of the development of -organisms, and the palaeontological history of the development of their -ancestors, a connection which is actually established by the laws of -_Inheritance_ and _Adaptation_, and which may be summed up in the words: -ontogeny, according to the laws of inheritance and adaptation, repeats -in its large features the outlines of phylogeny. - -(4.) _The comparative anatomy of organisms_, the proof of the essential -agreement of the inner structure of kindred organisms, in spite even of -the greatest difference of external form in the various species; their -explanation by the causal dependence of the internal agreement of the -structure on _Inheritance_, the external dissimilarity of the bodily -form on _Adaptation_. - -(5.) _The inner causal connection between comparative anatomy and the -history of development_, the harmonious agreement between the laws of -the gradual development, _the progressive differentiation and -perfecting_, as they may be seen in comparative anatomy on the one hand, -in ontogeny and palaeontology on the other. - -(6.) _Dysteleology, or the theory of purposelessness_, the name I have -given to the _science of rudimentary organs_, of suppressed and -degenerated, aimless and inactive, parts of the body; one of the most -important and most interesting branches of comparative anatomy, which, -when rightly estimated, is alone sufficient to refute the fundamental -error of the teleological and dualistic conception of Nature, and to -serve as the foundation of the mechanical and monistic conception of the -universe. - -(7.) _The natural system of organisms_, the natural grouping of all the -different forms of Animals, Plants, and Protista into numerous smaller -or larger groups, arranged beside and above one another; the kindred -connection of species, genera, families, orders, classes, tribes, etc., -more especially, however, the _arboriform branching character of the -natural system_, which is the spontaneous result of a natural -arrangement and classification of all these graduated groups or -categories. The result attained in attempting to exhibit the -relationships of the mere forms of organisms by a tabular classification -is only explicable when regarded as the expression of their actual -_blood relationship_; _the tree shape of the natural system_ can only be -understood as the actual _pedigree of the organisms_. - -(8.) _The chorology of organisms_, the science of the local distribution -of organic species, of their _geographical_ and _topographical -dispersion over the surface of the earth_, over the heights of -mountains and in the depths of the ocean, but especially the important -phenomenon that every species of organism proceeds from a so-called -"_centre of creation_" (more correctly a "_primaeval home_" or "_centre -of distribution_"); that is, from a single locality, where it originated -but once, and whence it spread. - -(9.) _The oecology of organisms_, the knowledge of the sum of the -_relations of organisms to the surrounding outer world_, to organic and -inorganic conditions of existence; the so-called "_economy of nature_," -the correlations between all organisms living together in one and the -same locality, their adaptation to their surroundings, their -modification in the struggle for existence, especially the circumstances -of parasitism, etc. It is just these phenomena in "the economy of -nature" which the unscientific, on a superficial consideration, are wont -to regard as the wise arrangements of a Creator acting for a definite -purpose, but which on a more attentive examination show themselves to be -the necessary results of mechanical causes. - -(10.) _The unity of Biology as a whole_, the deep inner connection -existing between all the phenomena named and all the other phenomena -belonging to zoology, protistics, and botany, and which are simply and -naturally explained by a single common principle. This principle can be -no other than the common derivation of all the specifically different -organisms from a single, or from several absolutely simple, primary -forms like the Monera, which possess no organs. The Theory of Descent, -by assuming this common derivation, throws a clear light upon these -individual series of phenomena, as well as upon their totality, without -which their deeper causal connection would remain completely -incomprehensible to us. The opponents of the Theory of Descent can in no -way explain any single one of these series of phenomena or their deeper -connection with one another. So long as they are unable to do this, _the -Theory of Descent remains the one adequate biological theory_. - -We should, on account of the grand proofs just enumerated, have to adopt -Lamarck's Theory of Descent for the explanation of biological phenomena, -even if we did not possess Darwin's Theory of Selection. The one is so -completely and _directly proved_ by the other, and established by -mechanical causes, that there remains nothing to be desired. The laws of -_Inheritance_ and _Adaptation_ are universally acknowledged -_physiological_ facts, the former traceable to _propagation_, the latter -to the _nutrition_ of organisms. On the other hand, the _struggle for -existence_ is a _biological_ fact, which with mathematical necessity -follows from the general disproportion between the average number of -organic individuals and the numerical excess of their germs. But as -Adaptation and Inheritance in the struggle for life are in continual -interaction, it inevitably follows that _natural selection_, which -everywhere influences and continually changes organic species, must, by -making use of _divergence of character_, produce new species. Its -influence is further especially favoured by the active and passive -_migrations_ of organisms, which go on everywhere. If we give these -circumstances due consideration, the continual and gradual modification -or transmutation of organic species will appear as a biological process, -which must, according to causal law, of _necessity_ follow from the -actual nature of organisms and their mutual correlations. - -That even the _origin of man_ must be explained by this general organic -process of transmutation, and that it is simply as well as naturally -explained by it, has, I believe, been sufficiently proved in my last -chapter but one. I cannot, however, avoid here once more directing -attention to the inseparable connection between this so-called "theory -of apes," or "pithecoid theory," and the whole Theory of Descent. If the -latter is the greatest _inductive law_ of biology, then it of necessity -follows that the former is its most important _deductive law_. They -stand and fall together. As all depends upon a right understanding of -this proposition, which in my opinion is very important, and which I -have therefore several times brought before the reader, I may be allowed -to explain it here by an example. - -In all mammals known to us the centre of the nervous system is the -spinal marrow and the brain, and the centre of the vascular system is a -quadrupal heart, consisting of two principal chambers and two -ante-chambers. From this we draw the general inductive conclusion that -all mammals, without exception, those extinct, together with all those -living species as yet unknown to us, as well as the species which we -have examined, possess a like organization, a like heart, brain, and -spinal marrow. Now if, as still happens every year, there be discovered -in any part of the earth a new species of mammal, a new species of -marsupial, or a new species of deer, or a new species of ape, every -zoologist knows with certainty at once, without having examined its -inner structure, that this species must possess a quadruple heart, a -brain and spinal marrow, like all other mammals. Not a single naturalist -would ever think of supposing that the central nervous system of this -new species of mammal could possibly consist of a ventral cord with an -oesophageal collar as in the insects, or of scattered pairs of knots as -in the molluscs, or that its heart could be many-chambered as in flies, -or one-chambered as in the tunicates. This completely certain and safe -conclusion, although it is not based upon any direct experience, is a -_deductive conclusion_. In the same way, as I have shown in a previous -chapter, Goethe, from the comparative anatomy of mammals, established -the general inductive conclusion that they all possess a mid jawbone, -and afterwards drew from it the special deductive conclusion that man, -who in all other respects does not essentially differ from other -mammals, must also possess a like mid jawbone. He maintained this -conclusion without having actually seen the human mid jawbone, and only -proved its existence subsequently by actual observation (vol. i. p. 84). - -The process of _induction_ is a logical system of forming conclusions -_from the special to the general_, by which we advance from many -individual experiences to a general law; _deduction_, on the other hand, -draws a conclusion _from the general to the special_, from a general law -of nature to an individual case. Thus the _Theory of Descent_ is, -without doubt, a great _inductive law_, empirically based upon all the -biological experience cited above; the pithecoid theory, on the other -hand, which asserts that man has developed out of lower, and in the -first place out of ape-like mammals, is a _deductive law_ inseparably -connected with the general inductive law. - -The pedigree of the human race, the approximate outlines of which I gave -in the last chapter but one, of course remains in detail (like all the -pedigrees of animals and plants previously discussed) a more or less -approximate general hypothesis. This however does not affect the -application of the theory of descent to man. Here, as in all -investigations on the derivation of organisms, one must clearly -distinguish between the general _theory_ of descent and the special -_hypotheses_ of descent. The general _theory_ of descent claims full and -lasting value, because it is an inductive law, based upon all the whole -series of biological phenomena and their inner causal connection. Every -special _hypothesis_ of descent, on the other hand, has its special -value determined by the existing condition of our biological knowledge, -and by the extent of the objective empirical basis upon which we -deductively establish this particular hypothesis. Hence, all the -individual attempts to obtain a knowledge of the pedigree of any one -group of organisms possesses but a temporary and conditional value, and -any special hypothesis relating to it will become the more and more -perfect the greater the advance we make in the comparative anatomy, -ontogeny, and palaeontology of the group in question. The more, however, -we enter into genealogical details, and the further we trace the -separate off-shoots and branches of the pedigree, the more uncertain and -subjective becomes our special _hypothesis_ of descent on account of the -incompleteness of our empirical basis. This however does no injury to -the general _theory_ of descent, which remains as the indispensable -foundation for really profound apprehension of biological phenomena. -Accordingly, there can be no doubt that we can and must, with full -assurance, regard the derivation of man--in the first place, from -ape-like forms; farther back, from lower mammals, and thus continually -farther back to lower stages of the vertebrata down to their lowest -invertebrate roots, nay, even down to a simple plastid--as a general -_theory_. On the other hand, the special tracing of the human pedigree, -the closer definition of the animal forms known to us, which either -actually belong to the ancestors of man, or at least stand in very close -blood relationship to them, will always remain a more or less -approximate _hypothesis_ of descent, all the more in danger of deviating -from the real pedigree the nearer it endeavours to approach it by -searching for the individual ancestral forms. This state of things -results from the immense gaps in our palaeontological knowledge, which -can, under no circumstances, ever attain to even an approximate -completeness. - -A thoughtful consideration of this important circumstance at once -furnishes the answer to a question which is commonly raised in -discussing this subject, namely, the question of scientific _proofs for -the animal origin of the human race_. Not only the opponents of the -Theory of Descent, but even many of its adherents who are wanting in the -requisite philosophical culture, look too much for "signs" and for -special empirical advances in the science of nature. They await the -sudden discovery of a human race with tails, or of a talking species of -ape, or of other living or fossil transition forms between man and the -ape, which shall fill the already narrow chasm between the two, and thus -empirically "prove" the derivation of man from apes. Such special -manifestations, were they ever so convincing and conclusive, would not -furnish the proof desired. Unthinking persons, or those unacquainted -with the series of biological phenomena, would still be able to maintain -the objections to those special testimonies which they now maintain -against our theory. - -The absolute certainty of the Theory of Descent, even in its application -to man, is built on a more solid foundation; and its true inner value -can never be tested simply by reference to individual experience, but -only by a philosophical comparison and estimation of the treasures of -all our biological experiences. The inestimable importance of the Theory -of Descent is surely based upon this, that the theory follows of -necessity (as a general inductive law) from the comparative synthesis of -all organic phenomena of nature, and more especially from the triple -parallelism of comparative anatomy, of ontogeny, and phylogeny; and the -pithecoid theory under all circumstances (apart from all special proofs) -remains as a special deductive conclusion which must of necessity be -drawn from the general inductive law of the Theory of Descent. - -In my opinion, all depends upon a right understanding of this -_philosophical foundation of the Theory of Descent_ and of the -_pithecoid theory_ which is inseparable from it. Many persons will -probably admit this, and yet at the same time maintain that all this -applies only to the _bodily_, not to the _mental_ development of man. -Now, as we have hitherto been occupied only with the former, it is -perhaps necessary here to cast a glance at the latter, in order to show -that it is also subject to the great general law of development. In -doing this it is above all necessary to recollect that body and mind can -in fact never be considered as distinct, but rather that both sides of -nature are inseparably connected, and stand in the closest interaction. -As even Goethe has clearly expressed it--"matter can never exist and act -without mind, and mind never without matter." The artificial discord -between mind and body, between force and matter, which was maintained by -the erroneous dualistic and teleological philosophy of past times has -been disposed of by the advances of natural science, and especially by -the theory of development, and can no longer exist in face of the -prevailing mechanical and monistic philosophy of our day. How human -nature, and its position in regard to the rest of the universe, is to be -conceived of according to the modern view, has been minutely discussed -by Radenhausen in his "Isis,"(33) which is excellent and well worth -perusal. - -With regard to the origin of the human mind or the soul of man, we, in -the first place, perceive that in every human individual it develops -from the beginning, step by step and gradually, just like the body. In a -newly born child we see that it possesses neither an independent -consciousness, nor in fact clear ideas. These arise only gradually when, -by means of sensuous experience, the phenomena of the outer world affect -the central nervous system. But still the little child is wanting in all -those differentiated emotions of the soul which the full-grown man -acquires only by the long experience of years. From this graduated -development of the human soul in every single individual we can, in -accordance with the inner causal connection between ontogeny and -phylogeny, directly infer the gradual development of the human soul in -all mankind, and further, in the whole of the vertebrate tribe. In its -inseparable connection with the body, the human soul or mind has also -had to pass through all those gradual stages of development, all those -various degrees of differentiation and perfecting, of which the -hypothetical series of human ancestors sketched in a late chapter gives -an approximate representation. - -It is true that this conception generally greatly offends most persons -on their first becoming acquainted with the Theory of Development, -because more than all others it most strongly contradicts the -traditional and mythological ideas, and the prejudices which have been -held sacred for thousands of years. But like all other functions of -organisms, the human soul must necessarily have historically developed, -and the comparative or empirical study of animal psychology clearly -shows that this development can only be conceived of as a gradual -evolution from the soul of vertebrate animals, as a gradual -differentiation and perfecting which, in the course of many thousands of -years, has led to the glorious triumph of the human mind over its lower -animal ancestral stages. Here, as everywhere, the only way to arrive at -a knowledge of natural truth is to compare kindred phenomena, and -investigate their development. Hence we must above all, as we did in the -examination of the bodily development, compare the highest animal -phenomena on the one hand with the lowest animal phenomena, and on the -other with the lowest human phenomena. The final result of this -comparison is this--that _between the most highly developed animal -souls, and the lowest developed human souls, there exists only a small -quantitative, but no qualitative difference_, and that this difference -is much less than the difference between the lowest and the highest -human souls, or than the difference between the highest and the lowest -animal souls. - -In order to be convinced of this important result, it is above all -things necessary to study and compare the mental life of wild savages -and of children.(32) At the lowest stage of human mental development are -the Australians, some tribes of the Polynesians, and the Bushmen, -Hottentots, and some of the Negro tribes. Language, the chief -characteristic of genuine men, has with them remained at the lowest -stage of development, and hence also their formation of ideas has -remained at a low stage. Many of these wild tribes have not even a name -for animal, plant, colour, and such most simple ideas, whereas they have -a word for every single, striking _form_ of animal and plant, and for -every single sound or colour. Thus even the most simple abstractions are -wanting. In many of these languages there are numerals only for one, -two, and three: no Australian language counts beyond four. Very many -wild tribes can count no further than ten or twenty, whereas some very -clever dogs have been made to count up to forty and even beyond sixty. -And yet the faculty of appreciating number is the beginning of -mathematics! Nothing, however, is perhaps more remarkable in this -respect, than that some of the wildest tribes in southern Asia and -eastern Africa have no trace whatever of the first foundations of all -human civilization, of family life, and marriage. They live together in -herds, like apes, generally climbing on trees and eating fruits; they do -not know of fire, and use stones and clubs as weapons, just like the -higher apes. All attempts to introduce civilization among these, and -many of the other tribes of the lowest human species, have hitherto been -of no avail; it is impossible to implant human culture where the -requisite soil, namely, the perfecting of the brain, is wanting. Not one -of these tribes has ever been ennobled by civilization; it rather -accelerates their extinction. They have barely risen above the lowest -stage of transition from man-like apes to ape-like men, a stage which -the progenitors of the higher human species had already passed through -thousands of years ago.(44) - -Now consider, on the other hand, the highest stages of development of -mental life in the higher vertebrate animals, especially birds and -mammals. If, as is usually done, we divide the different emotions of the -soul into three principal groups--sensation, will, and thought--we shall -find in regard to every one of them, that the most highly developed -birds and mammals are on a level with the lowest human beings, or even -decidedly surpass them. The _will_ is as distinctly and strongly -developed in higher animals as in men of character. In both cases it is -never actually free, but always determined by a causal chain of ideas. -(Compare vol. i. p. 237.) In like manner, the different degrees of will, -energy, and passion are as variously graduated in higher animals as in -man. The _affections_ of the higher animals are not less tender and warm -than those of man. The fidelity and devotion of the dog, the maternal -love of the lioness, the conjugal love and connubial fidelity of doves -and love-birds are proverbial, and might serve as examples to many men. -If these virtues are to be called "instincts," then they deserve the -same name in mankind. Lastly, with regard to _thought_, the comparative -consideration of which doubtless presents the most difficulties, this -much may with certainty be inferred--especially from an examination of -the comparative psychology of cultivated domestic animals--that the -processes of thinking, here follow the same laws as in ourselves. -Experiences everywhere form the foundation of conceptions, and lead to -the recognition of the connection between cause and effect. In all -cases, as in man, it is the path of induction and deduction which leads -to the formation of conclusions. It is evident that in all these -respects the most highly developed animals stand much nearer to man than -to the lower animals, although they are also connected with the latter -by a chain of gradual and intermediate stages. In Wundt's excellent -"Lectures on the Human and Animal Soul,"(46) there are a number of -proofs of this. - -Now, if instituting comparisons in both directions, we place the lowest -and most ape-like men (the Austral Negroes, Bushmen, and Andamans, -etc.), on the one hand, together with the most highly developed animals, -for instance, with apes, dogs, and elephants, and on the other hand, -with the most highly developed men--Aristotle, Newton, Spinoza, Kant, -Lamarck, or Goethe--we can then no longer consider the assertion, that -the mental life of the higher mammals has gradually developed up to that -of man, as in any way exaggerated. If one must draw a sharp boundary -between them, it has to be drawn between the most highly developed and -civilized man on the one hand, and the rudest savages on the other, and -the latter have to be classed with the animals. This is, in fact, the -opinion of many travellers, who have long watched the lowest human races -in their native countries. Thus, for example, a great English traveller, -who lived for a considerable time on the west coast of Africa, says: "I -consider the negro to be a lower species of man, and cannot make up my -mind to look upon him as 'a man and a brother,' for the gorilla would -then also have to be admitted into the family." Even many Christian -missionaries, who, after long years of fruitless endeavours to civilize -these lowest races, have abandoned the attempt, express the same harsh -judgment, and maintain that it would be easier to train the most -intelligent domestic animals to a moral and civilized life, than these -unreasoning brute-like men. For instance, the able Austrian missionary -Morlang, who tried for many years without the slightest success to -civilize the ape-like negro tribes on the Upper Nile, expressly says: -"that any mission to such savages is absolutely useless. They stand far -below unreasoning animals; the latter at least show signs of affection -towards those who are kind towards them, whereas these brutal natives -are utterly incapable of any feeling of gratitude." - -Now, it clearly follows from these and other testimonies, that the -mental differences between the lowest men and the animals are less than -those between the lowest and the highest men; and if, together with -this, we take into consideration the fact that in every single human -child mental life develops slowly, gradually, and step by step, from the -lowest condition of animal unconsciousness, need we still feel offended -when told that the mind of the whole human race has in like manner gone -through a process of slow, gradual, and historical development? Can we -find it "degrading" to the human soul that, by a long and slow process -of differentiation and perfecting, it has very gradually developed out -of the soul of vertebrate animals? I freely acknowledge that this -objection, which is at present raised by many against the pithecoid -theory, is quite incomprehensible to me. On this point Bernhard Cotta, -in his excellent "Geologie der Gegenwart," very justly remarks: "Our -ancestors may be a great honour to us; but it is much better if we are -an honour to them!"(31) - -Our Theory of Development explains the origin of man and the course of -his historical development in the only natural manner. We see in his -gradually ascensive development out of the lower vertebrata, the -greatest triumph of humanity over the whole of the rest of Nature. We -are proud of having so immensely outstripped our lower animal ancestors, -and derive from it the consoling assurance that in future also, mankind, -as a whole, will follow the glorious career of progressive development, -and attain a still higher degree of mental perfection. When viewed in -this light, the Theory of Descent as applied to man opens up the most -encouraging prospects for the future, and frees us from all those -anxious fears which have been the scarecrows of our opponents. - -We can even now foresee with certainty that the complete victory of our -Theory of Development will bear immensely rich fruits--fruits which have -no equal in the whole history of the civilization of mankind. Its first -and most direct result--the complete reform of _Biology_--will -necessarily be followed by a still more important and fruitful reform of -_Anthropology_. From this new theory of man there will be developed a -new _philosophy_, not like most of the airy systems of metaphysical -speculation hitherto prevalent, but one founded upon the solid ground of -Comparative Zoology. A beginning of this has already been made by the -great English philosopher Herbert Spencer.(45) Just as this new monistic -philosophy first opens up to us a true understanding of the real -universe, so its application to practical human life must open up a new -road towards moral perfection. By its aid we shall at last begin to -raise ourselves out of the state of social barbarism in which, -notwithstanding the much vaunted civilization of our century, we are -still plunged. For, unfortunately, it is only too true, as Alfred -Wallace remarks with regard to this, at the end of his book of travels: -"Compared with our wondrous progress in physical science and its -practical applications, our system of government, of administering -justice, of national education, and our whole social and moral -organisation remains in a state of barbarism." - -This social and moral barbarism we shall never overcome by the -artificial and perverse training, the one-sided and defective teaching, -the inner untruth and the external tinsel, of our present state of -civilization. It is above all things necessary to make a complete and -honest return to Nature and to natural relations. This return, however, -will only become possible when man sees and understands his true "place -in nature." He will then, as Fritz Ratzel has excellently remarked,(47) -"no longer consider himself an _exception_ to natural laws, but begin to -seek for what is lawful in his own actions and thoughts, and endeavour -to lead a life _according_ to natural laws." He will come to arrange his -life with his fellow-creatures--that is, the family and the state--not -according to the laws of distant centuries, but according to the -rational principles deduced from knowledge of nature. Politics, morals, -and the principles of justice, which are still drawn from all possible -sources, will have to be formed in accordance with natural laws only. An -_existence worthy of man_, which has been talked of for thousands of -years, will at length become a reality. - -The highest function of the human mind is perfect knowledge, fully -developed consciousness, and the moral activity arising from it. "Know -thyself!" was the cry of the philosophers of antiquity to their -fellow-men who were striving to ennoble themselves. "Know thyself!" is -the cry of the Theory of Development, not merely to the individual, but -to all mankind. And whilst increased knowledge of self becomes, in the -case of every individual man, a strong force urging to an increased -attention to conduct, mankind as a whole will be led to a higher path of -moral perfection by the knowledge of its true origin and its actual -position in Nature. The simple religion of Nature, which grows from a -true knowledge of Her, and of Her inexhaustible store of revelations, -will in future ennoble and perfect the development of mankind far beyond -that degree which can possibly be attained under the influence of the -multifarious religions of the churches of the various -nations,--religions resting on a blind belief in the vague secrets and -mythical revelations of a sacerdotal caste. Future centuries will -celebrate our age, which was occupied with laying the foundations of the -Doctrine of Descent, as the new era in which began a period of human -development, rich in blessings,--a period which was characterized by the -victory of free inquiry over the despotism of authority, and by the -powerful ennobling influence of the Monistic Philosophy. - - - FOOTNOTES: - - [1] With the exception of a single specimen of the bones of a foot, - preserved in the cabinet of Amherst College.--E. R. L. - - [2] The primary stock of the Coniferae divided into two branches at an - early period, into the Araucariae on the one hand, and the Taxaceae, or - yew-trees, on the other. The majority of recent Coniferae are derived - from the former. Out of the latter the third class of the - Gymnosperms--the Meningos, or Gnetaceae--were developed. This small but - very interesting class contains only three different genera--Gnetum, - Welwitschia, and Ephedra; it is, however, of great importance, as it - forms the transition group from the Coniferae to the Angiosperms, and - more especially to the Dicotyledons. - - [3] "Ueber ein Aequivalent der takonischen Schiefer Nordamerikas in - Deutschland." - - [4] The English word "Insects" might with advantage be used in the - Linnaean sense for the whole group of Arthropods. In this case the - Hexapod Insects might be spoken of as the Flies.--E. R. L. - - [5] Weisbach: "Novara-Reise," Anthropholog. Theil. - - [6] Muesset im Naturbetrachten - Immer Eins wie Alles achten. - Nichts ist drinnen, Nichts ist drauszen, - Denn was innen, das ist auszen. - - [7] Natur hat weder Kern noch Schale, - Alles ist sie mit einem Male. - - - - -LIST OF THE WORKS REFERRED TO IN THE TEXT BY FIGURES, THUS--(1), - -_The study of which is recommended to the Reader._ - - -1. _Charles Darwin_, On the Origin of Species by means of Natural -Selection; or, the Preservation of Favoured Races in the Struggle for -Life. London, 1859. 5th Edition, 1869. - -2. _Jean Lamarck_, Philosophie Zoologique, ou Exposition des -Considerations relatives a l'histoire naturelle des animaux; a la -diversite de leur organisation et des facultes, qu'ils en obtiennent; -aux causes physiques, qui maintiennent en eux la vie et donnent lieu aux -mouvemens, qu'ils executent; enfin, a celles qui produisent, les unes le -sentiment, et les autres l'intelligence de ceux qui en sont doues. 2 -Tomes. Paris, 1809. - -3. _Wolfgang Goethe_, Zur Morphologie: Bildung und Umbildung organischer -Naturen. Die Metamorphose der Pflanzen, 1790. Osteologie, 1786. Vortraege -ueber die drei ersten Capitel des Entwurfs einer allgemeinen Einleitung -in die vergleichende Anatomie, ausgehend von der Osteologie, 1786. Zur -Naturwissenschaft im Allgemeinen, 1780-1832. - -(Wolfgang Goethe, Contributions to Morphology: Formation and -Transformation of Organic Natures. The Metamorphosis of Plants, 1790. -Osteology, 1786. Lectures on the first three chapters of an Attempt at a -General Introduction to Comparative Anatomy, beginning with Osteology, -1786. Contributions to the Science of Nature in general, 1780-1832.) - -4. _Ernst Haeckel_, Generelle Morphologie der Organismen: Allgemeine -Grundzuege der organischen Formenwissenschaft, mechanisch begruendet durch -die von Charles Darwin reformirte Descendenz-theorie. I. Band, -Allgemeine Anatomie der Organismen, oder Wissenschaft von den -entwickelten organischen Formen. II. Band, Allgemeine -Entwickelungsgeschichte der Organismen, oder Wissenschaft von den -entstehenden organischen Formen. Berlin, 1866. - -(Ernst Haeckel, General Morphology of Organisms; General Outlines of the -Science of Organic Forms based on Mechanical Principles through the -Theory of Descent as reformed by Charles Darwin. Vol. I., General -Anatomy of Organisms; or, the Science of Fully Developed Organic Forms. -Vol. II., General History of the Development of Organisms; or, the -Science of Organic Forms in their Origin. Berlin, 1866.) - -5. _Louis Agassiz_, An Essay on Classification. Contributions to the -Natural History of the United States. Boston. Vol. I., 1857. - -6. _August Schleicher_, Die Darwin'sche Theorie und die -Sprachwissenschaft. Weimar, 1863. - -(August Schleicher, Darwin's Theory and the Science of Language. Weimar, -1863.) - -7. _M. J. Schleiden_, Grundzuege der wissenschaftlichen Botanik (die -Botanik als inductive Wissenschaft). 2 Baende. Leipzig, 1849. - -(M. J. Schleiden, Principles of Scientific Botany (Botany as an -Inductive Science). 2 Vols. Leipzig, 1849. Translated by Edwin -Lankester, M.D., F.R.S. London, 1849.) - -8. _Franz Unger_, Versuch einer Geschichte der Pflanzenwelt. Wien, 1852. - -(Franz Unger, Essay on the History of the Vegetable Kingdom. Vienna, -1852.) - -9. _Victor Carus_, System der thierischen Morphologie. Leipzig, 1853. - -(Victor Carus, System of Animal Morphology. Leipzig, 1853.) - -10. _Louis Buechner_, Kraft und Stoff. Empirisch-naturphilosophische -Studien in allgemein verstaendlicher Darstellung, Frankfort, 1855, 3 -Auflage. 1867, 9 Auflage. - -(Louis Buechner, Force and Matter. Studies in the Empirical Philosophy of -Nature, treated popularly. Frankfort, 1855, 3rd Edition. 1867, 9th -Edition.) - -11. _Charles Lyell_, Principles of Geology. London, 1830. 10th Edition, -1868. - -12. _Albert Lange_, Geschichte des Materialismus und Kritik seiner -Bedeutung in der Gegenwart. Iserlohn, 1866. - -(Albert Lange, History of Materialism, and a Criticism of its Importance -at the Present Time. Iserlohn, 1866.) - -13. _Charles Darwin_, Voyage of the _Beagle_. London. - -14. _Charles Darwin_, The Variation of Animals and Plants under -Domestication. 2 Vols. London, 1868. - -15. _Ernst Haeckel_, Studien ueber Moneren und andere Protisten, nebst -einer Rede ueber Entwickelungsgang und Aufgabe der Zoologie. Mit 6 -Kupfertafeln. Leipzig, 1870. - -(Ernst Haeckel, Studies on the Monera and other Protista, together with -a Discourse on the Evolution and the Problems of Zoology. With 6 -Copper-plates. Leipzig, 1870.) - -16. _Fritz Mueller_, Fuer Darwin. Leipzig, 1864. - -(Fritz Mueller, For Darwin. Translated by W. S. Dallas. London, Murray.) - -17. _Thomas Huxley_, On our Knowledge of the Causes of the Phenomena of -Organic Nature. Six Popular Lectures. London, Hardwicke, 1862. - -18. _H. G. Broenn_, Morphologische Studien ueber die Gestaltungsgesetze -der Naturkoerper ueberhaupt, und der Organischen insbesondere. Leipzig und -Heidelberg, 1858. - -(H. G. Broenn, Morphological Studies on the Laws of Form of Natural -Bodies in General, and of Organic Bodies in Particular. Leipzig and -Heidelberg, 1858.) - -19. _H. G. Broenn_, Untersuchungen ueber die Entwickelungsgesetze der -organischen Welt waehrend der Bildungszeit unserer Erdoberflaeche. -Stuttgart, 1858. - -(H. G. Broenn, Investigations on the Laws of Development of the Organic -World during the Time of the Formation of the Earth's Crust. Stuttgart, -1858.) - -20. _Carl Ernst Baer_, Ueber Entwickelungsgeschichte der Thiere. -Beobachtung und Reflexion. 2 Baende. 1828. - -(Carl Ernst Baer, On the History of the Development of Animals. -Observation and Reflection. 2 Vols. 1828.) - -21. _Carl Gegenbaur_, Grundzuege der vergleichenden Anatomie. Leipzig, -1859. 2 (Umgearbeitete) Auflage, 1870. - -(Carl Gegenbaur, Outlines of Comparative Anatomy. Leipzig, 1859. 2nd -(Revised) Edition, 1870.) - -22. _Immanuel Kant_, Allgemeine Naturgeschichte und Theorie des Himmels, -oder Versuch von der Verfassung und dem mechanischen Ursprunge des -ganzen Weltgebaeudes nach Newton'schen Grundsaetzen abgehandelt. -Koenigsberg, 1755. - -(Immanuel Kant, General History of Nature and Theory of the Heavens; or, -Essay on the Constitution and the Mechanical Origin of the whole -Universe treated according to Newton's Principles. Koenigsberg, 1755.) - -23. _Ernst Haeckel_, Die Radiolarien. Eine Monographie. Mit einem Atlas -von 35 Kupfertafeln. Berlin, 1862. - -(Ernst Haeckel, The Radiolaria. A Monograph, with Atlas containing 35 -Copper-plates. Berlin, 1862.) - -24. _August Weismann_, Ueber den Einflusz der Isolirung auf die -Artbildung. Leipzig, 1872. - -(August Weismann, On the Influence of Isolation on the Formation of -Species. Leipzig, 1872.) - -25. _Ernst Haeckel_, Ueber die Enstehung und den Stammbaum des -Menschengeschlechts. Zwei Vortraege in der Sammlung gemeinverstaendlicher -wissenschaftlicher Vortraege, herausgegeben von Virchow und Holtzendorff. -Berlin, 1868. 2 Auflage, 1870. - -(Ernst Haeckel, On the Origin and the Pedigree of the Human Race. Two -Lectures in the Collection of Popular Scientific Lectures, edited by -Virchow and Holtzendorff. Berlin, 1868. 2nd Edition, 1870.) - -26. _Thomas Huxley_, Evidences as to Man's Place in Nature. Three Parts: -1. On the Natural History of the Man-like Apes. 2. On the Relations of -Man to the Lower Animals. 3. On some Fossil Remains of Man. London, -Williams & Norgate. - -27. _Carl Vogt_, Vorlesungen ueber den Menschen, seine Stellung in der -Schoepfung und in der Geschichte der Erde. 2 Baende. Giessen, 1863. - -(Carl Vogt, Lectures on Man, his Place in Creation and in the History of -the Earth. 2 Vols. Giessen, 1863.) - -28. _Friedrich Rolle_, Der Mensch, seine Abstammung und Gesittung im -Lichte der Darwin'schen Lehre von der Art-Entstehung, und auf Grund der -neueren geologischen Entdeckungen dargestellt. Frankfurt-a-M., 1866. - -(Friedrich Rolle, Man, his Derivation and Civilization, in the Light of -Darwin's Theory of the Origin of Species, based on Recent Geological -Discoveries. Frankfort-a-M., 1866.) - -29. _Eduard Reich_, Die allgemeine Naturlehre des Menschen. Giessen, -1865. - -(Eduard Reich, The General Natural History of Man. Giessen, 1865.) - -30. _Charles Lyell_, The Antiquity of Man. London, Murray. - -31. _Bernhard Cotta_, Die Geologie der Gegenwart. Leipzig, 1866. - -(Bernhard Cotta, The Geology of the Present Day.) - -32. _Karl Zittel_, Aus der Urzeit. Bilder aus der Schoepfungsgeschichte. -Muenchen, 1871. - -(Karl Zittel, Primaeval Times. Pictures from the History of Creation. -Munich, 1871.) - -33. _C. Radenhausen_, Isis. Der Mensch und die Welt. 4 Baende. Hamburg, -1863. 2 Auflage, 1871. - -(C. Radenhausen, Isis. Man and the Universe. 4 Vols. Hamburg, 1863. 2nd -Edition, 1871.) - -34. _August Schleicher_, Ueber der Bedeutung der Sprache fuer die -Naturgeschichte des Menschen. Weimar, 1865. - -(August Schleicher, On the Importance of Language to the Natural History -of Man. Weimar, 1865). - -35. _Wilhelm Bleek_, Ueber den Ursprung der Sprache. Herausgegeben mit -einem Vorwort von Ernst Haeckel. Weimar, 1868. - -(Wilhelm Bleek, On the Origin of Language. Edited and with a Preface by -Ernst Haeckel. Weimar, 1868.) - -36. _Alfred Russel Wallace_, The Malayan Archipelago. London, Macmillan. - -37. _Ernst Haeckel_, Ueber Arbeitstheilung in Natur- und Menschenleben. -Sammlung gemeinverstaendlicher wissenschaftlicher Vortraege, herausgegeben -von Virchow und Holtzendorff. 4 Serie. 1869. Heft 78. - -(Ernst Haeckel, On Differentiation in Nature and in Human Life. A -Collection of Popular Scientific Lectures, edited by Virchow and -Holtzendorff. 4th Series. 1869. No. 78.) - -38. _Hermann Helmholtz_, Populaere wissenschaftliche Vortraege. -Braunschweig, 1871. - -(Hermann Helmholtz, Popular Scientific Lectures. Brunswick, 1871.) - -39. _Alexander Humboldt_, Ansichten der Natur. Stuttgart, 1826. - -(Alexander Humboldt, Views of Nature. Stuttgart, 1826.) - -40. _Moritz Wagner_, Die Darwin'sche Theorie und das Migrationsgesetz -der Organismen. Leipzig, 1868. - -(Moritz Wagner, Darwin's Theory and the Law of the Migration of -Organisms. Leipzig, 1868.) - -41. _Rudolf Virchow_, Vier Reden ueber Leben und Kranksein. Berlin, 1862. - -(Rudolf Virchow, Four Discourses on Life and Disease. Berlin, 1862.) - -42. _Friedrich Mueller_, Ethnographie (Reise der oesterreichischen -Fregatte Novara. Anthropologischer Theil. 3 Abtheilung). Wien, 1868. - -(Friedrich Mueller, Ethnography (Voyage of the Austrian Frigate _Novara_. -Anthropological Part. 3rd Part). Vienna, 1868.) - -43. _Ludwig Buechner_, Die Stellung des Menschen in der Natur, in -Vergangenheit, Gegenwart und Zukunft. Leipzig, 1870. - -(Ludwig Buechner, Man's Place in Nature in the Past, the Present, and the -Future. Leipzig, 1870.) - -44. _John Lubbock_, Prehistoric Times. London, 1867. - -45. _Herbert Spencer_, A System of Philosophy. (1. First Principles. 2. -Principles of Biology. 3. Principles of Psychology, etc.) London, 1867. -2nd Edition. - -46. _Wilhelm Wundt_, Vorlesungen ueber die Menschen- und Thierseele. -Leipzig, 1863. - -(Wilhelm Wundt, Lectures on the Human and Animal Soul. Leipzig, 1863.) - -47. _Fritz Ratzel_, Sein und Werden der organischen Welt. Eine populaere -Schoepfungsgeschichte. Leipzig, 1869. - -(Fritz Ratzel, Nature and Origin of the Organic World. A Popular History -of Creation. Leipzig, 1869.) - -48. _Charles Darwin_, The Descent of Man, and Selection in Relation to -Sex. 2 Vols. London, 1871. - - - - -APPENDIX. - -EXPLANATION OF THE PLATES. - - - PLATE FACING TITLE-PAGE. - -_Developmental History of a Calcareous Sponge_ (Olynthus). Compare vol. -ii. p. 140. The egg of the Olynthus (Fig. 9), which represents the -common ancestral form of all Calcareous Sponges, is a simple cell (Fig. -1). From this there arises, by repeated division (Fig. 2), a globular, -mulberry-like heap of numerous equi-formal cells (Morula, Fig. 3; vol. -ii. p. 125.) As the result of the change of these cells into an outer -series of clear ciliated cells (Exoderm) and an inner series of dark, -non-ciliated cells (Entoderm), the ciliated larva, or Planula, makes its -appearance. This is oval in shape, and forms a cavity in its centre -(gastric cavity, or primitive stomach, Fig. 6 _g_, with an opening -(mouth-opening, or primitive mouth, Fig. 6 _o_); the wall of the gastric -cavity consists of two layers of cells, or germ-layers, the outer -ciliated Exoderm (_e_) and the inner non-ciliated Entoderm (_i_). Thus -arises the exceedingly important stomach-larva, or Gastrula, which -reappears in the most different tribes of animals as a common larval -form (Fig. 5, seen from the surface; Fig. 6, in long section. Compare, -vol. ii. pp. 126 and 281). After the Gastrula has swum about for some -time in the sea, it fastens itself securely to the sea-bottom, loses its -outer vibratile processes, or cilia, and changes into the Ascula (Fig. -7, seen from the surface; Fig. 8, in long section; letters as in Fig. -6). This Ascula is the recapitulative form, according to the biogenetic -fundamental law, the common ancestor of all Zoophytes, namely, the -Protascus (vol. ii. pp. 129, 133). By the development of pores in the -wall of the stomach and of three-rayed calcareous spicules, the Ascula -changes into the Olynthus (Fig. 9.) In Fig. 9 a piece is cut out from -the stomach-wall of the Olynthus in order to show the inside of the -stomachal cavity, and the eggs which are forming on the surface (_g_). -From the Olynthus the most various forms of Calcareous Sponges can -develop. One of the most remarkable is the Ascometra (Fig. 10), a stock -or colony from which different species, and in fact different generic -forms, grow (on the left Olynthus, in the middle Nardorus, on the right -Soleniscus, etc., etc.). Further details as to these most interesting -forms, and their high importance for the Theory of Descent, may be found -in my "Monograph of the Calcareous Sponges" (1872), especially in the -first volume. (Compare vol. ii. pp. 160, 167). - - - PLATE I. (_Between pages 184 and 185, Vol. I._) - -_History of the Life of the most Simple Organism_, a Moneron (Protomyxa -aurantiaca). Compare vol. i. p. 184, and vol. ii. p. 53. The plate is a -smaller copy of the drawing in my "Monographie der Moneren" (Biologische -Studien, 1 Heft, 1870; Taf. 1), of the developmental history of the -Protomyxa aurantiaca; I have there also given a detailed description of -this remarkable Moneron (pp. 11-30). I discovered this most simple -organism in January, 1867, during a stay in Lanzarote, one of the Canary -Islands; and moreover I found it either adhering to, or creeping about -on the white calcareous shells of a small Cephalopod (vol. ii. p. 162), -the Spirula Peronii, which float there in masses on the surface of the -ocean, or are thrown up on the shore. The Protomyxa aurantiaca is -distinguished from the other Monera by the beautiful and bright -orange-red colour of its perfectly simple body, which consists merely of -primaeval slime, or protoplasm. The fully developed Moneron is -represented in Figs. 11 and 12, very much enlarged. When it is hungry -(Fig. 11), there radiate from the surface of the globular corpuscule of -plasm, quantities of tree-shaped, branching and mobile threads -(pseudo-feet, or pseudopodia), which do not become retiformly -connected. When, however, the Moneron eats (Fig. 12), the mucous threads -become variously connected, form net-works and enclose the extraneous -corpuscule which serves as food, which the threads afterwards draw into -the interior of the Protomyxa. Thus in Fig. 12 (above on the right), a -silicious and ciliated Whip-swimmer (Peridinium, vol. ii. pp. 51, 57), -has just been caught by the extended mucous filaments, and has been -drawn into the interior of the mucous globule, in which there already -are several half digested silicious infusoria (Tintinoida), and Diatomeae -(Isthmia). Now, when the Protomyxa has eaten and grown sufficiently, it -draws in all its mucous filaments (Fig. 15), and contracts into the form -of a globule (Fig. 16 and Fig. 1). In this state of repose the globule -secretes a simple gelatinous covering (Fig. 2), and after a time -subdivides into a large number of small mucous globules (Fig. 3). These -soon commence to move, become pear-shaped (Fig. 4), break through the -common covering (Fig. 5), and then swim about freely in the ocean by -means of a delicate whip-shaped process, like the Flagellata (vol. ii. -p. 57, Fig. 11). When they meet a Spirula shell, or any other suitable -object, they adhere to it, draw in their whip, and creep slowly about on -it by means of form-changing processes (Figs. 6, 7, 8), like Protamoebae -(vol. i. p. 186, vol. ii. p. 52). These small mucous corpuscules take -food (Figs. 9, 10), and attain their full grown form (Figs. 11, 12), -either by simple growth or by several of them fusing to form a larger -protoplasmic mass (Plasmodium, Figs. 13, 14). - - - PLATES II. AND III. (_Between pages 294 and 295, Vol. I._) - -_Germs or Embryos of four different Vertebrate Animals_, namely, -Tortoise (_A_ and _E_), Hen (_B_ and _F_), Dog (_C_ and _G_), and Man -(_D_ and _H_). Figs. _A_, _D_, an early stage of development; Figs. _E_, -_H_, a later stage. All the eight embryos are represented as seen from -the right side, the curved back turned to the left. Figs. _A_ and _B_ -are seven times enlarged, Figs. _C_ and _D_ five times, Figs. _E_ and -_H_ four times. Plate II. exhibits the very close blood relationship -between birds and reptiles; Plate III. that between man and the other -mammals. - - - PLATE IV. (_Between pages 34 and 35, Vol. II._) - -_The Hand, or Fore Foot, of nine different Mammals._ This plate is -intended to show the importance of Comparative Anatomy to Phylogeny, in -as much as it proves how the internal skeleton of the limbs is -continually preserved by _inheritance_, although the external form is -extremely changed by _adaptation_. The bones of the skeleton of the hand -are drawn in white lines on the brown flesh and skin which surrounds -them. All the nine hands are represented in the same position, namely -the wrist (where the arm would be joined to it) is placed above, whilst -the ends of the fingers or toes are turned downwards. The thumb, or the -first (large) fore-toe is on the left in every figure; the little -finger, or fifth toe is to the right at the edge of the hand. Each hand -consists of three parts, namely (i.) the _wrist_ (carpus), composed of -two cross rows of short bones (at the upper side of the hand); (ii.) the -_mid-hand_ (metacarpus), composed of five long and strong bones (marked -in the centre of the hand by the numbers 1-5); and (iii.) the five -_fingers_, or _fore toes_ (digiti), every one of which again consists of -several (mostly from two to three), _toe-pieces_, or _phalanges_. The -hand of _man_ (Fig. 1), in regard to its entire formation, stands -midway between that of the two large human apes, namely, that of the -_gorilla_ (Fig. 2), and that of the _orang_ (Fig. 3). The fore paw of -the _dog_ (Fig. 4), is more different, and the hand or breast fin of the -_seal_ (Fig. 5) still more so. The adaptation of the hand to the -movement of swimming, and its transformation into a fin for steering, is -still more complete in the _dolphin_ (Ziphius, Fig. 6). The extended -fingers and bones of the central hand here have remained short and -strong in the swimming membrane, but they have become extremely long and -thin in the _bat_ (Fig. 7), where the hand has developed into a wing. -The extreme opposite of the latter formation is the hand of the _mole_ -(Fig. 8), which has acquired a powerful spade-like form for digging, -with fingers which have become extremely short and thick. What is far -more like the human hand than these latter forms, is the fore paw of the -lowest and most imperfect of all mammals, the Australian _beaked animal_ -(Ornithorhynchus, Fig. 9), which in its whole structure stands nearer to -the common, extinct, primary form of mammalia, than any known species. -Hence man differs less in the formation of the hand from this common -primary form than from the bat, mole, dolphin, seal, and many other -mammals. - - - PLATE V. (_Between pages 84 and 85, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Vegetable Kingdom_, -representing the hypothesis of the common derivation of all plants, and -the historical development of the different groups of plants during the -palaeontological periods of the earth's history. The horizontal lines -denote the different smaller and larger periods of the organic history -of the earth (which are spoken of in vol. ii. p. 14), and during which -the strata containing fossils were deposited. The vertical lines -separate the different main-classes and classes of the vegetable kingdom -from one another. The arboriform and branching lines indicate, in an -approximate manner, by their greater or less number and thickness, the -greater or less degree of development, differentiation, and perfecting -which each class probably attained in each geological period. (Compare -vol. ii. pp. 82, 83.) - - - PLATE VI. (_Between pages 130 and 131, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Animal Kingdom_, -representing the _historical growth of the six animal tribes_ during the -palaeontological periods of the organic history of the earth. The -horizontal lines _g h_, _i k_, _l m_, and _n o_ divide the five large -periods of the organic history of the earth one from another. The field -_g a b h_ comprises the archilithic, the field _i g h k_, the -palaeolithic, the field _l i k m_ the mesolithic, and the field _n l o m_ -the cenolithic period. The short, anthropolithic period is indicated -by the line _n o_. (Compare vol. ii. p. 14.) The height of the separate -fields corresponds with the relative length of the periods indicated by -them, as they may approximately be estimated from the relative thickness -of the neptunic strata deposited between them. (Compare vol. ii. p. 22.) -The archilithic and primordial period alone, during which the -Laurentian, Cambrian, and Silurian strata were deposited, was probably -considerably longer than the four subsequent periods taken together. -(Compare vol. ii. pp. 10, 20.) In all probability the two tribes of -worms and Zoophytes attained their full development during the -mid-primordial period (in the Cambrian system); the star-fishes and -molluscs probably somewhat later (in the Silurian system); whereas the -articulata and vertebrata are still increasing in variety and -perfection. - - - PLATE VII. (_Between pages 146 and 147, Vol. II._) - -_Group of Animal-Trees_ (_Zoophytes, or Coelenterata_) _in the -Mediterranean_. On the upper half of the plate is a swarm of swimming -medusae and ctenophora; on the lower half a few bunches of corals and -hydroid polyps adhering to the bottom of the sea. (Compare the system of -Zoophytes, vol. ii. p. 132, and on the opposite page their pedigree.) -Among the adhering Zoophytes at the bottom of the ocean there is, below -on the right hand, a large coral-colony (1), which is closely akin to -the red precious coral (Eucorallium), and like the latter belongs to the -group of corals with eight rays (Octocoralla Gorgonida); the single -individuals (or persons) of the branching stock have the form of a star -with eight rays, consisting of eight tentacles, which surround the -mouth. (Octocoralla, vol. ii. p. 143.) Directly below and in front of it -(quite below on the right), is a small bush of hydroid polyps (2), -belonging to the group of bell-polyps, or Campanulariae (vol. ii. p. -146). A larger stock of hydroid polyps (3), belonging to the group of -tube-polyps, or Tubullariae, rises, to the left, on the opposite side, -with its long thin branches. At its base is spread a stock of silicious -sponges (Halichondria) (4), with short, finger-shaped branches (vol. -ii. p. 139). Behind it, below on the left (5), is a very large marine -rose (Actinia), a single individual from the class of six-rayed corals -(Hexacoralla, vol. ii. p. 143). Its low, cylindrical body has a crown of -very numerous and large leaf-shaped tentacles. Below, in the centre of -the ground (6), is a sea-anemone (Cereanthus) from the group of -fourfold corals (Tetracoralla). Lastly, on a small hill on the bottom -of the sea, there rises, on the right above the corals (1) a cup-polyp -(Lucernaria), as the representative of the stalked-jellies. -(Podactinaria, or Calycozoa, vol. ii. p. 144.) Its cup-shaped, stalked -body (7) has eight globular clusters of small, knotted tentacles on its -rim. - -Among the _swimming Zoophytes_ which occupy the upper half of Plate -VII., the hydromedusae are especially remarkable, on account of their -alteration of generation. (Compare vol. i. p. 206.) Directly above the -Lucernaria (7) floats a small tiara jelly (Oceania), whose bell-shaped -body has a process like a dome, the form of a papal tiara (8). From the -opening of the bell there hangs a wreath of very fine and long -tentacles. This Oceania is the offspring of a tube-polyp, resembling the -adhering Tubularia below on the left (3). Beside this latter, on the -left, swims a large but very delicate hair-jelly (AEquorea). Its -disc-shaped, slightly arched body is just drawing itself together, and -pressing water out of the cavity of the cup lying below (9). The -numerous, long, and fine hair-like tentacles which hang down from the -rim of the cup are drawn by the ejected water into a conical bunch, -which towards the centre turns upwards like a collar, and is thrown into -folds. Above, in the middle of the cavity of the cup, hangs the stomach, -the mouth of which is surrounded by four lobes. This AEquorea is derived -from a small bell-polyp, resembling the Campanularia (2). The small, -slightly arched cap-jelly (Eucope), swimming above in the centre (10), -is likewise derived from a similar bell-polyp. In these three last cases -(8, 9, 10), as in the majority of the hydromedusae, the alternation of -generation consists in the freely swimming medusa (8, 9, 10), arising by -the formation of buds (therefore by non-sexual generation, vol. i. p. -192), from adhering hydroid polyps (2, 3). These latter, however, -originate out of the fructified eggs of the medusae (therefore by sexual -generation, vol. i. p. 195). Hence the non-sexual, adhering generation -of polyps (I., III., V., etc.) regularly alternates with the sexual, -freely swimming generation of medusae (II., IV., VI., etc.). This -alteration of generation can only be explained by the Theory of Descent. - -The same remark applies to a kindred form of propagation, which is still -more remarkable, and which I discovered in 1864, near Nice, in the -Elephant-jellies (Geryonida), and called _alloeogony_, or -_alloeogenesis_. In this case two completely distinct forms of medusa -are descended from one another; the larger and more highly developed -generation (11), Geryonia, or Carmarina, is six-rayed, with six foliated -sexual organs, and six very movable marginal filaments. From the centre -of its bell-shaped cup, like the tongue of a bell, hangs a long -proboscis, at the end of which is the opening of the mouth and stomach. -In the cavity of the stomach is a long, tongue-shaped bunch of buds -(which on Plate VII. (_n_) is extended from the mouth on the left like a -tongue). On this tongue, when the Geryonia is sexually ripe, there bud a -number of small medusae. They are, however, not Geryoniae, but belong to -an entirely distinct but very different form of medusa, namely, to the -genus Cunina, of the family of the _AEginida_. This Cunina (12) is very -differently constructed; it has a flat, semi-globular cup without -proboscis, consists in early life of six divisions, later of sixteen, -and has sixteen bag-shaped sexual organs, and sixteen short, stiff, and -strongly curved tentacles. A further explanation of this wonderful -alloeogenesis may be found in my "Contributions to the Natural History -of the Hydromedusae." (_Leipzig_, Englemann, 1865), the first part of -which contains a monograph of the Elephant-jellies, or Geryonida, -illustrated by six copper-plates. - -Even more interesting and instructive than these remarkable relations -are the vital phenomena of the _Siphonophora_, whose wonderful -polymorphism I have frequently spoken of, and described in a popular -manner in my lecture on "Differentiation in Nature and Human Life."(37) -(Compare vol. i. p. 270, and vol. ii. p. 140.) An example of this is -given in Plate VII. in the drawing of the beautiful Physophora (13). -This swimming stock or colony of hydromedusae is kept floating on the -surface of the sea by a small swimming bladder filled with air, which in -the drawing is seen rising above the surface of the water. Below it is a -column of four pairs of swimming bells, which eject water, and thereby -set the whole colony in motion. At the lower end of the column of -swimming bells is a crown-shaped wreath of curved spindle-shaped -_sensitive polyps_, which also serve as a covering, under the protection -of which the other individuals of the stock (the eating, catching, and -reproductive persons) are hidden. The _ontogenesis_ of the Siphonophora -(and especially of this Physophora), I first observed in Lanzerote, one -of the Canary Islands, in 1866, and described in my "History of the -Development of the Siphonophora," and added fourteen plates for its -explanation. (Utrecht, 1869). It is rich in interesting facts, which can -only be explained by the Theory of Descent. - -Another circumstance, which is also only explicable by the Theory of -Descent, is the remarkable change of generation in the higher medusae, -the disc-jellies (Discomedusae, vol. ii. p. 136), a representative of -which is given at the top of Plate VII., in the centre (rather in the -background), namely, a Pelagia (14). From the bottom of the bell-shaped -cup, which is strongly arched and the rim of which is neatly indented, -there hang four very long and strong arms. The non-sexual polyps, from -which these disc-jellies are derived, are exceedingly simple primaeval -polyps, differing very little from the common fresh-water polyp (Hydra). -The alternation of generation in these Discomedusae has also been -described in my lecture on Differentiation,(37) and there illustrated by -the Aurelia by way of example. - -Finally, the last class of Zoophytes, the group of comb-jellies -(Ctenophora, vol. ii. p. 142), has two representatives on Plate VII. To -the left, in the centre, between the AEquorea (9), the Physophora (13), -and the Cunina (12), is a long and thin band like a belt (15), winding -like a snake; this is the large and splendid _Venus' girdle_ of the -Mediterranean (Cestum), the colours of which are as varied as those of -the rainbow. The actual body of the animal, which lies in the centre of -the long belt, is very small, and constructed exactly like that of the -_melon-jelly_ (Cydippe), which floats above to the left (16). On the -latter are visible the eight characteristic fringed bands, or ciliated -combs, of the ctenophora, and also two long tentacles which extend right -across the page, and are fringed with still finer threads. - - - PLATES VIII. AND IX. (_Between pages 170 and 171, Vol. II._) - -_History of the Development of Star-fishes_ (_Echinoderma_, or -_Estrella_). The two plates exhibit their alternation of generation -(vol. ii. p. 168), with an example from each of the four classes of -Star-fishes. The sea-stars (Asterida) are represented by Uraster (_A_), -the sea-lilies (Crinoida) by Comatula (_B_), the sea-urchins (Echinida) -by Echinus (_C_), and finally, the sea-cucumbers (Holothuriae) by Synapta -(_D_). (Compare vol. ii. pp. 166 and 176.) The successive stages of -development are marked by the numbers 1-6. - -Plate VIII. represents the individual development of the first and -non-sexual generation of Star-fishes, that is, of the _nurses_ (usually, -but erroneously, called larvae). These nurses possess the form-value of a -simple, unsegmented worm-individual. Fig. 1 represents the egg of the -four Star-fishes; and it, in all essential points, agrees with that of -man and of other animals. (Compare vol. i. p. 297, Fig. 5.) As in man, -the protoplasm of the egg-cell (the yolk) is surrounded by a thick, -structureless membrane (zona pellucida), and contains a globular, -cell-kernel (nucleus), as clear as glass, which again encloses a -nucleolus. Out of the fertilised egg of the Star-fish (Fig. _A_ 1) there -develops in the first place, by the repeated sub-division of cells, a -globular mass of homogeneous cells (Fig. 6, vol. i. p. 299), and this -changes into a very simple nurse, which has almost the same shape as a -wooden shoe (Fig. _A_ 2-_D_ 2). The edge of the opening of the shoe is -bordered by a fringe of cilia, the ciliary movements of which keep the -microscopically small and transparent nurse swimming about freely in the -sea. This fringe of cilia is marked in Fig. _A_ 2-_A_ 4, on Plate VII., -by the narrow alternately light and dark seam. The nurse then, in the -first place, forms a perfectly simple intestinal canal for nutrition, -mouth (_o_), stomach (_m_) and anus (_a_). Later, the windings of the -fringe of cilia become more complicated, and there arise arm-like -processes (Fig. _A_ 3-_D_ 3). In sea-stars (_A_ 4) and sea-urchins (_C_ -4) these arm-like processes, which are fringed with cilia, afterwards -become very long. But in the case of sea-lilies (_B_ 3) and -sea-cucumbers (_D_ 4), instead of this, the fringe of cilia, which at -first, through winding in and out, forms one closed ring, changes -subsequently into a succession of separate ciliated girdles, one lying -behind the other. - -In the interior of this curious nurse there then develops, by a -non-sexual process of generation, namely, by the formation of internal -buds or germ-buds (round about the stomach), the second generation of -Star-fishes, which later on become sexually ripe. This second -generation, which is represented on Plate IX. in a fully developed -condition, exists originally as a stock or cormus of five worms, -connected at one end in the form of a star, as is most clearly seen in -the sea-stars, the most ancient and original form of the star-fishes. -The second generation, which grows at the expense of the first, -appropriates only the stomach and a small portion of the other organs of -the latter, but forms for itself a new mouth and anus. The fringe of -cilia, and the other parts of the body of the nurse, afterwards -disappear. The second generation (_A_ 5-_D_ 5), is at first smaller or -not much larger than the nurse, whereas, by growth, it afterwards -becomes more than a hundred times, or even a thousand times, as large. -If the ontogeny of the typical representatives of the four classes of -Star-fishes be compared, it is easily seen that the original kind of -development has been best preserved in sea-stars (_A_) and sea-urchins -(_C_) by inheritance, whereas in sea-lilies (_B_) and sea-cucumbers it -has been suppressed according to the laws of abbreviated inheritance -(vol. i. p. 212). - -Plate IX. shows the fully developed and sexually mature animals of the -second generation from the mouth side, which, in the natural position of -Star-fishes (when creeping at the bottom of the sea), in sea-stars (_A_ -6) and sea-urchins (_C_ 6), is below, in sea-lilies (_B_ 6) above, and -in sea-cucumbers (_D_ 6) in front. In the centre we perceive, in all the -four Star-fishes, the star-shaped, five-pointed opening of the mouth. In -sea-stars, from each arm there extend several rows of little sucking -feet, from the centre of the under-side of each arm to the end. In -sea-lilies (_B_ 6), each arm is split and feather-like from its base -upwards. In sea-urchins (_C_ 6) the five rows of sucking feet are -divided by broader fields of spines. In sea-cucumbers, lastly (_D_ 6), -on the worm-like body it is sometimes only the five rows of little feet, -sometimes only the feathery tentacles surrounding the mouth, from five -to fifteen (in this case ten), that are externally visible. - - - PLATES X. AND XI. (_Between pages 174 and 175, Vol. II._) - -_Historical Development of the Crab-fish_ (Crustacea).--The two plates -illustrate the development of the different Crustacea from the nauplius, -their common primaeval form. On Plate XI. six Crustacea, from six -different orders, are represented in a fully developed state, whereas on -Plate X. the early nauplius stages are given. From the essential -agreement between the latter we may, on the ground of the fundamental -law of biogeny, with full assurance maintain the derivation of the -different Crustacea from a single, common primary form, a long since -extinct Nauplius, as was first shown by Fritz Mueller in his excellent -work "Fuer Darwin."(16) - -Plate X. represents the _early nauplius stages_ from the ventral side, -so that the three pairs of legs, on the short, three-jointed trunk are -distinctly visible. The first of these pairs of legs is simple and -unsegmented, whereas the second and third pairs are forked. All three -pairs are furnished with stiff bristles, which, through the paddling -motion of the legs, serve as an apparatus for swimming. In the centre of -the body, the perfectly simple, straight intestinal canal is visible, -possessing a mouth in front, and an anal orifice behind. In front, above -the mouth, lies a simple, single eye. All the six forms of nauplius -entirely agree in all these essential characteristics of organization, -whereas the six fully developed forms of Crustacea belonging to them, -Plate XI., are extremely different in organisation. The differences of -the six nauplius forms are confined to quite subordinate and unessential -relations in regard to size of body, and the formation of the covering -of the skin. If they could be met with in this form in a sexually mature -condition, no zoologist would hesitate to regard them as six different -species of one genus. (Compare vol. ii. p. 175.) - -Plate XI. represents those fully developed and sexually mature forms of -Crustacea, as seen from the right side, which have ontogenetically -(hence also phylogenetically) developed out of the six kinds of -nauplius. Fig. _A c_ shows a freely swimming fresh-water crab (Limnetis -brachyurus) from the order of the Leaf-foot Crabs (Phyllopoda), slightly -enlarged. Of all the still living Crustacea, this order, which belongs -to the legion of Gill-foot Crabs (Branchiopoda), stands nearest to the -original, common primary form of nauplius. The Limnetis is enclosed in a -bivalved shell, like a mussel. Our drawing (which is copied from Grube) -represents the body of a female animal lying in the left shell; the -right half of the shell has been removed. In front, behind the eye, we -see the two feelers (antennae), and behind them the twelve leaf-shaped -feet of the right side of the body, behind on the back (under the -shell), the eggs. Above, in front, the animal is fixed to the shell. - -Fig. _B c_ represents a common, freely swimming fresh-water crab -(Cyclops quadricornis) from the order of Oar-legged crabs (Eucopepoda), -highly magnified. In front, below the eye, we see the two feelers of the -right side, the foremost of which is longer than the hinder one. Behind -these are the gills, and then the four paddling legs of the right side. -Behind these are the two large egg-sacks, which, in this case, are -attached to the end of the hinder part of the body. - -Fig. _C c_ is a parasitic Oar-legged crab (Lernaeocera esocina), from the -order of fish lice (Siphonostoma). These peculiar crabs, which were -formerly regarded as worms, have originated, by adaptation to a -parasitical life, out of freely swimming, Oar-legged crabs (Eucopepoda), -and belong to the same legion (Copepoda, vol. ii. p. 176). By adhering -to the gills on the skin of fish or other crabs, and feeding on the -juice of these creatures, they forfeited their eyes, legs, and other -organs, and developed into formless, inarticulated sacks, which, on a -mere external examination, we should never suppose to be animals. On the -ventral side only there exist, in the shape of short, pointed bristles, -the last remains of legs which have now almost entirely disappeared. Two -of these rudimentary pairs of legs (the third and fourth) are seen in -our drawing on the right. Above, on the head, we see thick, shapeless -appendages, the lower ones of which are split. In the centre of the body -is seen the intestinal canal, which is surrounded by a dark covering of -fat. At its posterior end is the ovary, and the cement-glands of the -female sexual apparatus. The two large egg-sacks hang externally (as in -the Cyclops, Fig. _B_). Our Lernaeocera is represented in half profile, -and is copied from Claus. (Compare Claus, "Die Copepoden-Fauna von -Nizza. Ein Beitrag zur Characteristik der Formen und deren Abaenderungen -im Sinne Darwins." Marburg, 1866). - -Fig. _D c_ represents a so-called "duck mussel" (Lepas anatifera), from -the order of the Barnacle crabs (Cirripedia). These crabs, upon which -Darwin has written a very careful monograph, are, like mussels, enclosed -in a bivalved, calcareous case, and hence were formerly (even by Cuvier) -universally regarded as a kind of mussel, or mollusc. It was only from a -knowledge of their ontogeny, and their early nauplius form (_D n_, Plate -VIII.), that their crustacean nature was proved. Our drawing shows a -"duck mussel" of the natural size, from the right side. The right half -of the bivalved shell has been removed, so that the body is seen lying -in the left half of the shell. From the rudimentary head of the Lepas -there issues a long, fleshy stalk (curving upwards in our drawing); by -means of it the Barnacle crab grows on rocks, ships, etc. On the ventral -side are six pairs of feet. Every foot is forked and divided into two -long, curved, or curled "tendrils" furnished with bristles. Above and -behind the last pair of feet projects the thin cylindrical tail. - -Fig. _E c_ represents a parasitic sack-crab (Sacculina purpurea) from -the order of Root-crabs (Rhizocephala). These parasites, by adaptation -to a parasitical life, have developed out of Barnacle crabs (Fig. _D -c_), much in the same way as the fish-lice (_C c_), out of the freely -swimming Oar-legged crabs (_B c_). However, the suppression, and the -subsequent degeneration, of all of the organs, has gone much further in -the present case than in most of the fish-lice. Out of the articulated -crab, possessing legs, intestine, and eye, and which in an early stage -as nauplius (_E n_, Plate VIII.), swam about freely, there has developed -a formless, unsegmented sack, a red sausage, which now only contains -sexual organs (eggs and sperm) and an intestinal rudiment. The legs and -the eye have completely disappeared. At the posterior end is the opening -of the genitals. From the mouth grows a thick bunch of numerous -tree-shaped and branching root-like fibres. These spread themselves out -(like the roots of a plant in the ground) in the soft hinder part of the -body of the hermit-crab (Pagurus), upon which the root-crab lives as a -parasite, and from which it draws its nourishment. Our drawing (_E c_), -a copy of Fritz Mueller's, is slightly enlarged, and shows the whole of -the sausage-shaped sack-crab, with all its root-fibres, when drawn out -of the body upon which it lives. - -Fig. _F c_ is a _shrimp_ (Peneus Muelleri), from the order of _ten-foot_ -crabs (Decapoda), to which our river cray-fish, and its nearest -relative, the lobster, and the short-tailed shore-crabs also belong. -This order contains the largest and, gastronomically, the most important -crabs, and belongs, together with the mouth-legged and split-legged -crabs, to the legion of the stalk-eyed mailed crabs (Podophthalma). The -shrimp, as well as the river crab, has in front, on each side below the -eye, two long feelers (the first much shorter than the second), then -three jaws, and three jaw-feet, then five very long legs (the three -fore ones of which, in the Peneus, are furnished with nippers, and the -third of which is the longest). Finally, on the first five joints of the -hinder part of the body there are other five pairs of feet. This shrimp, -which is one of the most highly developed and perfect crabs, originates -(according to Fritz Mueller's important discovery) out of a nauplius (_F -n_ Plate VIII.), and consequently proves that the higher Crustacea have -developed out of the same form as the lower ones, namely, the nauplius. -(Compare vol. ii. p. 175.) - - - PLATES XII. AND XIII. (_Between pages 200 and 201, Vol. II._) - -_Blood relationship between the Vertebrata and the Invertebrata._ -(Compare vol. ii. pp. 152 and 201.) It is definitely established by -Kowalewski's important discovery, which was confirmed by Kupffer, that -the ontogeny of the lowest vertebrate animal--the Lancelet, or -Amphioxus--agrees in all essential outlines completely with that of the -invertebrate Sea-squirts, or Ascidiae, from the class of Sea-sacks, or -Tunicata. On our two plates, the ascidia is marked by _A_, the amphioxus -by _B_. Plate XIII. represents these two very different animal-forms in -a _fully developed_ state, as seen from the _left side_, the end of the -mouth above, the opposite end below. Hence, in both figures the dorsal -side is to the right, the ventral to the left. Both figures are slightly -magnified, and the internal organisation of the animals is distinctly -visible through the transparent skin. The full-grown ascidia (Fig. _A_ -6) grows at the bottom of the ocean, from whence it cannot move, and -clings to stones and other objects by means of peculiar roots (_w_) like -a plant. The full-grown amphioxus, on the other hand (Fig. _B_ 6), swims -about freely like a small fish. The letters on both figures indicate the -same parts: (_a_) orifice of the mouth; (_b_) orifice of the body, or -porus abdominalis; (_c_) dorsal rod, or chorda dorsalis; (_d_) -intestine; (_e_) ovary; (_f_) oviduct (same as the sperm-duct); (_g_) -spinal marrow; (_h_) heart; (_i_) blind-sac of the intestine; (_k_) -gill basket (respiratory cavity); (_l_) cavity of the body; (_m_) -muscles; (_n_) testicle (in the ascidia united with the ovary into a -hermaphrodite gland); (_o_) anus; (_p_) genital orifice; (_q_) -well-developed embryos in the body cavity of the ascidia; (_r_) rays of -the dorsal fin of the amphioxus; (_s_) tail-fin of the amphioxus; (_w_) -roots of the ascidia. - -Plate XII. shows the _Ontogenesis_, or the individual development of the -_Ascidia_ (_A_) and the _Amphioxus_ (_B_) in five different stages -(1-5). Fig. 1 is the egg, a simple cell like the egg of man and all -other animals (Fig. _A_ 1 the egg of the ascidia, Fig. _B_ 1 the egg of -the amphioxus). The actual cell-substance, or the protoplasm of the -egg-cell (_z_), the so-called yolk, is surrounded by a covering -(cell-membrane, or yolk-membrane), and encloses a globular cell-kernel, -or nucleus (_y_), the latter, again, contains a kernel-body, or -nucleolus (_x_); when the egg begins to develop, the egg-cell first -subdivides into two cells. By another sub-division there arise four -cells (Fig. _A_ 2, _B_ 2), and out of these, by repeated sub-division, -eight cells (vol. i. p. 190, Fig. 4 _C_, _D_). By fluid gathering in the -interior these form a globular bladder bounded by a layer of cells. On -one spot of its surface the bladder is turned inwards in the form of a -pocket (Fig. _A_ 4, _B_ 4). This depression is the beginning of the -intestine, the cavity (_d_ 1) of which opens externally by the -provisional larval-mouth (_d_ 4). The body-wall, which is at the same -time the stomach-wall, now consists of two layers of cells--the -germ-layers. The globular larva (Gastrula), now grows in length. Fig. -_A_ 5 represents the larva of the ascidia, Fig. _B_ 5 that of the -amphioxus, as seen from the left side in a somewhat more advanced state -of development. The orifice of the intestine (_d_ 1) has closed. The -dorsal side of the intestine (_d_ 2) is concave, the ventral side (_d_ -3) convex. Above the intestinal tube, on its dorsal side, the neural -tube, the beginning of the spinal marrow, is being formed, its cavity -still opens externally in front (_g_ 2). Between the spinal marrow and -the intestine has arisen the spinal rod, or chorda dorsalis (Notochord) -(_c_), the axis of the inner skeleton. In the larva of the ascidia this -rod (_c_) proceeds along the long rudder-tail, a larval organ, which is -cast off in later transformation. Yet there still exist some very small -ascidiae (Appendicularia) which do not become transformed and attached, -but which through life swim about freely in the sea by means of their -rudder-tail. - -The ontogenetic facts which are systematically represented on Plate XII. -and which were first discovered in 1867, deserve the greatest attention, -and, indeed, cannot be too highly estimated. They fill up the gap which, -according to the opinion of older zoologists existed between the -vertebrate and the so-called "invertebrate" animals. This gap was -universally regarded as so important and so undeniable, that even -eminent zoologists, who were not disinclined to adopt the theory of -descent, saw in this gap one of the chief obstacles against it. Now that -the ontogeny of the amphioxus and the ascidia has set this obstacle -completely aside, we are for the first time enabled to trace the -pedigree of man beyond the amphioxus into the many-branching tribe of -"invertebrate" worms, from which all the other higher animal tribes have -originated. - -If our speculative philosophers, instead of occupying themselves with -castles in the air, were to give their thoughts for some years to the -facts represented on Plates XII. and XIII., as well as to those on -Plates II. and III., they would gain a foundation for true -philosophy--for the knowledge of the universe firmly based on -experience--which would be sure to influence all regions of thought. -These facts of ontogenesis are the indestructible foundations upon which -the monistic philosophy of future times will erect its imperishable -system. - - - PLATE XIV. (_Between pages 206 and 207, Vol. II._) - -_Monophyletic, or One-rooted Pedigree of the Vertebrate Animal tribe_, -representing the hypothesis of the common derivation of all vertebrate -animals, and the historical development of their different classes -during the palaeontological periods of the earth's history. (Compare -Chapter XX. vol. ii. p. 192.) The horizontal lines indicate the periods -(mentioned in vol. ii. p. 14) of the organic history of the earth during -which the deposition of the strata containing fossils took place. The -vertical lines separate the classes and sub-classes of vertebrata from -one another. The tree-shaped and branching lines, by their greater or -lesser number and thickness, indicate the approximate degree of -development, variety, and perfection, which each class probably attained -in each geological period. In those classes which, on account of the -soft nature of their bodies, could not leave any fossil remains (which -is especially the case with Prochordata, Acrania, Monorrhina, and -Dipneusta) the course of development is hypothetically suggested on the -ground of arguments derived from the three records of -creation--comparative anatomy, ontogeny, and palaeontology. The most -important starting-points for the hypothetical completion of the -palaeontological gaps are here, as in all cases, furnished by the -_fundamental law of biogeny_, which asserts the inner _causal-nexus -existing between ontogeny and phylogeny_. (Compare vol. i. p. 310, and -vol. ii. p. 200; also Plates VIII.-XIII.) In all cases we have to regard -the individual development (determined by the laws of Inheritance but -modified by the laws of Adaptation) as short and quick repetitions of -the palaeontological development of the tribe. This proposition is the -"ceterum censeo" of our theory of development. - -The statements of the first appearance, or the period of the origin of -the individual classes and sub-classes of vertebrate animals (apart from -the hypothetical filling in mentioned just now), are taken as strictly -as possible from palaeontological facts. It must, however, be observed, -that in reality the origin of most of the groups probably took place one -or two periods earlier than fossils now indicate. In this I agree with -Huxley's views; but on Plates V. and XIV. I have disregarded this -consideration in order not to go too far from palaeontological facts. - -The numbers signify as follows (compare also Chapter XX. and vol. ii. -pp. 204, 206):--1. Animal Monera; 2. Animal Amoebae; 3. Community of -Amoebae (Synamoebae); 4. Ciliated Infusoria without mouths; 5. Ciliated -Infusoria with mouths; 6. Gliding worms (Turbellaria); 7. Sea-sacks -(Tunicata); 8. Lancelet (Amphioxus); 9. Hag (Myxinoida); 10. Lamprey -(Petromyzontia); 11. Unknown forms of transition from single-nostriled -animals to primaeval fishes; 12. Silurian primaeval fish (Onchus, etc.); -13. Living primaeval fishes (sharks, rays, Chimaerae); 14. Most ancient -(Silurian) enamelled fishes (Pteraspis); 15. Turtle fishes (Pamphracti); -16. Sturgeons (Sturiones); 17. Angular-scaled enamelled fishes -(Rhombiferi); 18. Bony pike (Lepidosteus); 19. Finny pike (Polypterus); -20. Hollow-boned fishes (Coeloscolopes); 21. Solid boned fishes -(Pycnoscolopes); 22. Bald pike (Amia); 23. Primaeval boned fishes -(Thrissopida); 24. Bony fishes with air passage to the swimming bladder -(Physostomi); 25. Bony fishes without air passage to the swimming -bladder (Physoclisti); 26. Unknown forms of transition between primaeval -fishes and amphibious fishes; 27. Ceratodus; 27_a_. Extinct Ceratodus -from the Trias; 27_b_. Living Australian Ceratodus; 28. African -amphibious fishes (Protopterus) and American amphibious fishes -(Lepidosiren); 29. Unknown forms of transition between primaeval fishes -and amphibia; 30. Enamelled heads (Ganocephala); 31. Labyrinth toothed -(Labyrinthodonta); 32. Blind burrowers (Caeciliae); 33. Gilled amphibia -(Sozobranchia); 34. Tailed amphibia (Sozura); 35. Frog amphibia (Anura); -36. Dichthacantha (Proterosaurus); 37. Unknown forms of transition -between Amphibia and Protamnia; 38. Protamnia (common primary form of -all Amnion animals); 39. Primary mammals (Promammalia); 40. Primaeval -reptiles (Proreptilia); 41. (Thecodontia); 42. Primaeval dragons -(Simosauria); 43. Serpent dragons (Plesiosauria); 44. Fish dragons -(Ichthyosauria); 45. Teleosauria (Amphicoela); 46. Steneosauria -(Opisthocoela); 47. Alligators and Crocodiles (Prosthocoela); 48. -Carnivorous Dinosauria (Harpagosauria); 49. Herbivorous Dinosauria -(Therosauria); 50. Maestricht lizards (Mosasauria); 51. Common primary -form of Serpents (Ophidia); 52. Dog-toothed beaked lizards (Cynodontia); -53. Toothless beaked lizards (Cryptodontia); 54. Long-tailed flying -lizards (Rhamphorhynchi); 55. Short-tailed flying lizards -(Pterodactyli); 56. Land tortoises (Chersita); 57. Birds--reptiles -(Tocornithes), transition form between reptiles and birds; 58. Primaeval -griffin (Archaeopteryx); 59. Water beaked-animal (Ornithorhynchus); 60. -Land beaked-animal (Echidna); 61. Unknown forms of transition between -Cloacals and Marsupials; 62. Unknown forms of transition between -Marsupials and Placentals; 63. Tuft Placentals (Villiplacentalia); 64. -Girdle Placentals (Zonoplacentalia); 65. Disc Placentals -(Discoplacentalia); 66. Man (Homo pithecogenes, by Linnaeus erroneously -called, Homo sapiens.) - - - PLATE XV. (_After page 369, Vol. II._) - -_Hypothetical Sketch of the Monophyletic Origin and the Diffusion of the -Twelve Species of Men from Lemuria over the earth._ The _hypothesis_ -here geographically sketched of course only claims an entirely -_provisional value_, as in the present imperfect state of our -anthropological knowledge it is simply intended to show how the -distribution of the human species, from a single primaeval home, may be -_approximately_ indicated. The probable primaeval home, or "Paradise," is -here assumed to be _Lemuria_, a tropical continent at present lying -below the level of the Indian Ocean, the former existence of which in -the tertiary period seems very probable from numerous facts in animal -and vegetable geography. (Compare vol. i. p. 361, and vol. ii. p. 315.) -But it is also very possible that the hypothetical "cradle of the human -race" lay further to the east (in Hindostan or Further India), or -further to the west (in eastern Africa). Future investigations, -especially in comparative anthropology and palaeontology, will, it is to -be hoped, enable us to determine the probable position of the primaeval -home of man more definitely than it is possible to do at present. - -If in opposition to our monophyletic hypothesis, the polyphyletic -hypothesis--which maintains the origin of the different human species -from several different species of anthropoid ape--be preferred and -adopted, then, from among the many possible hypotheses which arise, the -one deserving most confidence seems to be that which assumes a double -pithecoid root for the human race namely, an Asiatic and an African -root. For it is a very remarkable fact, that the African man-like apes -(gorilla and chimpanzee) are characterized by a distinctly long-headed, -or dolichocephalous, form of skull, like the human species peculiar to -Africa (Hottentots, Caffres, Negroes, Nubians). On the other hand, the -Asiatic man-like apes (especially the small and large orang), by their -distinct, short-headed, or brachycephalous, form of skull agree with -human species especially characteristic of Asia (Mongols and Malays). -Hence, one might be tempted to derive the latter (the Asiatic man-like -apes and primaeval men) from a common form of brachycephalous ape, and -the former (the African man-like apes and primaeval men) from a common -dolichocephalous form of ape. - -In any case, tropical Africa and southern Asia (and between them -Lemuria, which formerly connected them) are those portions of the earth -which deserve the first consideration in the discussion as to the -primaeval home of the human race; America and Australia are, on the other -hand, entirely excluded from it. Even Europe (which is in fact but a -western peninsula of Asia) is scarcely of any importance in regard to -the "Paradise question." - -It is self-evident that the migrations of the different human species -from their primaeval home, and their geographical distribution, could on -our Plate XV. be indicated only in a very general way, and in the -roughest lines. The numerous migrations of the many branches and tribes -in all directions, as well as the very important re-migrations, had to -be entirely disregarded. In order to make these latter in some degree -clear, our knowledge would, in the first place, need to be much more -complete, and secondly, we should have to make use of an atlas with a -number of plates showing the various migrations. Our Plate XV. claims no -more than to indicate, in a very general way, the approximate -geographical dispersion of the twelve human species as it existed in the -fifteenth century (before the general diffusion of the Indo-Germanic -race), and as it can be sketched out approximately, so as to harmonize -with our hypothesis of descent. The geographical barriers to diffusion -(mountains, deserts, rivers, straits, etc.), have not been taken into -consideration in this general sketch of migration, because, in earlier -periods of the earth's history, they were quite different in size and -form from what they are to-day. The gradual transmutation of catarrhine -apes into pithecoid men probably took place in the tertiary period in -the hypothetical Lemuria, and the boundaries and forms of the present -continents and oceans must then have been completely different from what -they are now. Moreover, the mighty influence of the ice period is of -great importance in the question of the migration and diffusion of the -human species, although it as yet cannot be more accurately defined in -detail. I here, therefore, as in my other hypotheses of development, -expressly guard myself against any dogmatic interpretation; they are -nothing but _first attempts_. - - - - -INDEX. - - A - - ABYSSINIANS, ii. 323, 330 - - Acalephae, ii. 141 - - Acoelomi, ii. 148, 151 - - Acrania, ii. 196, 198, 200, 204 - - Acyttaria, ii. 51, 62 - - Adaptation, i. 90, 156, 219 - - ---- actual, i. 225, 231 - - ---- correlative, i. 241 - - ---- cumulative, i. 233 - - ---- direct, i. 225, 231 - - ---- divergent, i. 247 - - ---- indirect, i. 224, 227 - - ---- individual, i. 228 - - ---- irregular, i. 229 - - ---- monstrous, i. 229 - - ---- potential, i. 224, 227 - - ---- sexual, i. 230 - - ---- universal, i. 231 - - ---- unlimited, i. 249 - - Agassiz, Louis, i. 61 - - Agassiz's conception of the universe, i. 65 - - ---- essay on classification, i. 61 - - ---- history of creation, i. 63 - - ---- history of development, i. 64 - - ---- idea of species, i. 65 - - Albuminous bodies, i. 331 - - Algae, ii. 81, 82, 83 - - Alluvial system, ii. 15 - - Altaians, ii. 309, 317 - - Alternation of generations, i. 206 - - Americans, ii. 309, 318 - - Amnion animals, ii. 204, 219 - - Amniota, ii. 204, 219 - - Amoebae, ii. 53, 279 - - Amoeboidea, ii. 53 - - Amphibia, ii. 209, 216 - - Amphioxus, ii. 198, 285 - - Amphirrhina, ii. 203, 205 - - Anamnionata, ii. 204 - - Animal Plants, ii. 144 - - Angiospermae, ii. 83, 111 - - Annelida, ii. 133, 149, 151 - - Anorgana, i. 5, 328 - - Anorganology, i. 6 - - Anthozoa, ii. 143 - - Anthropocentric conception of the universe, i. 38 - - Anthropoides, ii. 270, 275, 292 - - Anthropolithic period, ii. 15, 17 - - Anthropology, i. 7 - - Anthropomorphism, i. 18, 66 - - Ape-like men, ii. 293, 300 - - Apes, ii. 241, 268, 270 - - Arabians, ii. 323, 330 - - Arachnida, ii. 180, 182 - - Archelminthes, ii. 148 - - Archezoa, ii. 132, 134 - - Archigony, i. 183, 338 - - Archilithic period, ii. 8, 14 - - Arians, ii. 323, 331 - - Aristotle, i. 55, 76 - - Arthropoda, ii. 132 - - Articulata, ii. 119 - - Ascidia, ii. 152, 200 - - Ascones, ii. 141 - - Asterida, ii. 164, 166 - - Atavism, i. 207 - - Australians, ii. 308, 314 - - Autogeny, i. 339 - - - B - - BAeR, CARL ERNST, i. 109 - - ---- doctrine of filiation, i. 109 - - ---- theory of development, i. 294 - - ---- types of animals, i. 53; ii. 119 - - Basques, ii. 322 - - Bathybius, i. 184, 344; ii. 53 - - Batrachians, ii. 204 - - Bats, ii. 240, 261 - - Beaked mammals, ii. 233, 239 - - ---- reptiles, ii. 224, 226 - - Belief, i. 9; ii. 335 - - Berbers, ii. 323, 330 - - Biogenesis, fundamental law of, i. 309; ii. 33 - - Biology, i. 6 - - Birds, ii. 204, 226 - - Brachiopoda, ii. 157 - - Brain, bladder of, in man, i. 304 - - ---- development of, i. 303 - - Bruno Giordano, i. 22, 70 - - Bryozoa, ii. 150, 152 - - Buch, Leopold, i. 107 - - Buechner, Louis, i. 110 - - Buds, formation of, i. 192 - - - C - - CAFFRES, ii. 312, 333 - - Calcispongiae, ii. 140, 144 - - Cambrian system, ii. 9, 15 - - Carbon, i. 330, 335 - - ---- theory of, i. 335 - - Carboniferous system, ii. 11, 15 - - Carus Victor, i. 110 - - Catallacta, i. 51, 59 - - Catarrhini, ii. 270, 272 - - Caucasians, ii. 309, 321 - - Causa finalis, i. 34, 75 - - Causal conception of the universe, i. 18, 74 - - Cells, i. 187, 346 - - ---- formation of, i. 347 - - ---- theory of, i. 346 - - Cell-kernel, i. 188 - - ---- membrane, i. 188 - - ---- substance, i. 186 - - Caenolithic period, ii. 14, 16 - - Cephalopoda, ii. 160, 162 - - Chamisso, Adalbert, i. 206 - - Change of climate, i. 363 - - Chelophora, ii. 240, 257 - - Chinese, ii. 309, 317 - - Chorology, i. 351 - - Cloacal animals, ii. 234, 239 - - Cochlides, ii. 159, 160 - - Coelenterata, ii. 136, 144 - - Coelomati, ii. 148, 151 - - Coniferae, ii. 82, 110 - - Constructive forces, i. 90, 253, 337 - - Copernicus, i. 39 - - Corals, ii. 142, 144 - - Coreo-Japanese, ii. 309, 317 - - Cormophytes, ii. 80 - - Correlation of parts, i. 218 - - Cosmogeny, i. 321 - - Cosmological gas theory, i. 323 - - Crabs, ii. 174, 176 - - Craniota, ii. 198, 204 - - Creation, centres of, i. 352 - - ---- the, i. 8 - - Creator, the, i. 64, 70 - - Cretaceous system, ii. 12, 15 - - Crinoides, ii. 166, 171 - - Crocodiles, ii. 223, 224 - - Crustacea, ii. 173, 176 - - Cryptogamia, ii. 80, 82 - - Ctenophera, ii. 142, 144 - - Cultivated plants, i. 137 - - Curly-haired men, ii. 310, 333 - - Cuttles, ii. 160, 162 - - Cuvier, George, i. 50 - - Cuvier's dispute with Geoffroy, i. 88 - - ---- history of creation, i. 59 - - ---- palaeontology, i. 54 - - ---- idea of species, i. 50 - - ---- theory of cataclysms, i. 58 - - ---- theory of revolutions, i. 58 - - ---- types of animals, i. 53; ii. 118 - - Cycadeae, ii. 82, 110 - - Cyclostoma, ii. 202, 204 - - Cytod, i. 346 - - - D - - DARWIN, CHARLES, i. 131 - - Darwinism, i. 149 - - Darwin's life, i. 132 - - ---- travels, i. 132 - - ---- theory of corals, i. 133 - - ---- theory of selection, i. 150 - - ---- study of pigeons, i. 141 - - Darwin, Erasmus, i. 118 - - Deciduata, ii. 240, 255 - - Deduction, i. 85; ii. 357 - - Democritus, i. 22 - - Devonian system, ii. 11, 14 - - Diatomeae, ii. 51, 60 - - Dicotylae, ii. 82, 112 - - Didelphia, ii. 239 - - Differentiation, i. 270, 283 - - Diluvial system, ii. 15 - - Dipneusta, ii. 204, 212 - - Divergence, i. 270 - - Division of labour, i. 247 - - Domestic animals, i. 137 - - Dragons, ii. 225 - - Dravidas, ii. 308, 319 - - Dualistic conception of the universe, i. 20, 75 - - Dysteleology, i. 15; ii. 353 - - - E - - ECHINIDA, ii. 166, 171 - - Echinoderma, ii. 163, 166 - - Edentata, ii. 240, 254 - - Egg Animals, ii. 132, 134 - - Eggs, i. 190, 198 - - Egg of man, i. 190, 297; ii. 279 - - Egg, cleavage of the, i. 190, 299; ii. 280 - - Egyptians, ii. 323, 330 - - Elephants, ii. 257 - - Empiricism, i. 79; ii. 349 - - Eocene system, ii. 15, 16 - - Ethiopians, ii. 323, 330 - - Explanation of phenomena, i. 29 - - - F - - FERNS, ii. 82, 101 - - Fibrous plants, ii. 82 - - Final cause, i. 22 - - Fins, ii. 309, 317 - - Fishes, ii. 206, 208 - - Flagellata, ii. 51, 57 - - Flat-nosed apes, ii. 270, 272 - - Flat worms, ii. 148, 150 - - Flint cells, ii. 51, 60 - - Flowering plants, ii. 82, 108 - - Flower animals, ii. 143 - - Flowerless plants, ii. 80, 82 - - Flying animals, ii. 240, 261 - - Freke, i. 119 - - Fulatians, ii. 308, 320 - - Fungi, ii. 82 - - - G - - GANOID FISH, ii. 208, 210 - - Gastraea, ii. 127, 128, 281 - - Gastrula, ii. 126, 127 - - Gegenbaur, i. 312; ii. 179, 193 - - Gemmation, i. 192 - - Generation, i. 209 - - Genus, i. 41 - - Geocentric conception of the universe, i. 38 - - Geoffroy S. Hilaire, i. 86, 116 - - Germans, ii. 323, 331 - - Germ buds, formation of, i. 193 - - ---- cells, formation of, i. 194 - - Gibbon, ii. 270, 275 - - Gilled insects, ii. 174, 176 - - Gill-arches in man, i. 307 - - God, conception of, i. 70 - - Goethe, Wolfgang, i. 80 - - Goethe's conception of nature, i. 22 - - ---- discovery of mid-jaw bone, i. 84 - - ---- formative tendency i. 91, 253 - - ---- idea of God, i. 71 - - ---- investigations in nature, i. 81 - - ---- materialism, i. 23 - - ---- metamorphosis, i. 90 - - ---- metamorphosis of plants, i. 82 - - ---- philosophy of nature, i. 81 - - ---- theory of development, i. 92 - - ---- vertebrae of skull, i. 83 - - Genochoristus, i. 196 - - Gonochorism, i. 196 - - Gorilla, ii. 270 - - Grant, i. 119 - - Greeks, ii. 323, 331 - - Gregarinae, ii. 133, 134 - - Gynmosperms, ii. 82, 109 - - - H - - HALISAURIA, ii. 204, 214 - - Hare-rabbit, i. 148, 275 - - Heliozoa, ii. 64 - - Herbert, i. 119 - - Heredity, i. 176 - - Hermaphrodites, i. 196 - - Herschel's cosmogeny, i. 321 - - Holothuriae, ii. 166, 172 - - Hoofed animals, ii. 249, 252 - - Hooker, i. 119 - - Hottentots, ii. 311, 333 - - Human races, ii. 296, 305, 308 - - ---- soul, ii. 361 - - Huxley, i. 119, 145; ii. 268 - - Hybridism, i. 145, 210, 275 - - Hydromedusae, ii. 143, 145 - - - I - - ICE PERIOD, i. 367; ii. 17 - - Indecidua, ii. 241, 249 - - Individual development, ii. 293 - - Indo-Chinese, ii. 309, 317 - - Indo-Germanic, ii. 323, 331 - - Induction, i. 85; ii. 357 - - Infusoria, ii. 132, 135 - - Inheritance, abridged, i. 212 - - Inheritance, acquired, i. 213 - - ---- adapted, i. 213 - - ---- amphigonous, i. 210 - - ---- conservative, i. 204 - - ---- constituted, i. 216 - - ---- contemporaneous, i. 217 - - ---- continuous, i. 205 - - ---- established, i. 216 - - ---- homochronous, i. 217 - - ---- interrupted, i. 205 - - ---- latent, i. 205 - - ---- mixed, i. 210 - - ---- progressive, i. 213 - - ---- sexual, i. 209 - - ---- simplified, i. 212 - - ---- uninterrupted, i. 205 - - ---- laws of, i. 204 - - Inophyta, ii. 82, 93 - - Insects, ii. 184 - - Insectivora, ii. 241, 259 - - Instinct, ii. 343 - - Invertebrata, ii. 118, 195 - - Iranians, ii. 323, 331 - - - J - - JAPANESE, ii. 309, 317 - - Jews, ii. 323, 330 - - Jura system, ii. 12, 14 - - - K - - KANT, IMMANUEL, i. 101, 321 - - Kant's Criticism of the faculty of judgment, i. 105 - - ---- mechanisms, i. 37, 102 - - ---- philosophy of nature, i. 101 - - ---- theory of descent, i. 103 - - ---- theory of development, i. 321 - - ---- theory of the formation of the universe, i. 101 - - Knowledge, a posteriori, i. 31; ii. 345 - - ---- a priori, i. 31; ii. 344 - - - L - - LABYRINTHULEAE, ii. 51 - - Lacertilia, ii. 223 - - Lamarck, Jean, i. 111 - - Lamarck's anthropology, i. 115; ii. 264 - - ---- philosophy of nature, i. 112 - - ---- theory of descent, i. 113 - - Lamarckism, i. 150 - - Lamellibranchia, ii. 158, 160 - - Lancelet, ii. 198, 204, 285 - - Laplace's cosmogeny, i. 321 - - Laurentian system, ii. 9, 14 - - Lemuria, i. 361; ii. 326 - - Leonardo da Vinci, i. 56 - - Leptocardia, ii. 196, 204 - - Leucones, ii. 141 - - Linnaeus, Charles, i. 39 - - Linnaeus' classification of animals, ii. 118 - - ---- classification of plants, ii. 78 - - ---- designation of species, i. 41 - - ---- history of creation, i. 44 - - ---- system, i. 40 - - Lubbock, Sir John, ii. 298 - - Lyell, Charles, i. 126 - - Lyell's history of creation, i. 128 - - - M - - MAGYARS, ii. 309, 316 - - Malays, ii. 308, 315 - - Malthus' theory of population, i. 161 - - Mammalia, ii. 231, 239 - - Man-apes, ii. 271, 275, 292 - - Marsupials, ii. 236, 239, 290 - - Matagenesis, i. 206 - - Materialism, i. 35 - - Matter, i. 22; ii. 360 - - Mechanical causes, i. 34, 74 - - Mechanical conception of the universe, i. 17, 74 - - Mechanism, i. 37, 102 - - Mediterranese, ii. 308, 321 - - Medusae, ii. 143, 144 - - Mesolithic period, ii. 14, 20 - - Metamorphosis of the earth's strata, ii. 25 - - Metamorphosis, i. 90 - - Migration, laws of, i. 373 - - ---- of organisms, i. 354 - - ---- of the human species, ii. 325 - - ---- theory of, i. 367 - - Mind, i. 22; ii. 360 - - ---- development of the, ii. 344, 360 - - Miocene period, ii. 15, 16 - - Miracles, i. 22 - - Molluscs, ii. 155, 160 - - Monera, i. 184, 343; ii. 52, 278 - - Mongols, ii. 308, 316 - - Monism, i. 34 - - Monistic conception of the universe, i. 20, 74 - - Monocottylae, ii. 82, 112 - - Monoglottonic, ii. 327, 333 - - Monogony, i. 183 - - Monophylites, ii. 44 - - Monophyletic hypothesis of descent, ii. 44 - - Monorrhina, ii. 203, 204 - - Monosporogonia, i. 194 - - Monotrema, ii. 234, 239 - - Morphology, i. 21 - - Morula, ii. 125, 127 - - Moses' history of creation, i. 37 - - Moss animals, ii. 150, 152 - - Mosses, ii. 82, 97 - - Mueller, Fritz, i. 49, 73; ii. 174 - - Mueller, Johannes, i. 312; ii. 203 - - Muscinae, ii. 82, 99 - - Mussels, ii. 159, 160 - - Myriapoda, ii. 182, 184 - - Myxomycetes, ii. 51, 60 - - - N - - NATURAL PHILOSOPHY, i. 78 - - Negroes, ii. 309, 313, 333 - - Nemathelminthes, ii. 149, 150 - - Newton, i. 25, 106 - - Non-amnionate, ii. 204, 209 - - Nubians, ii. 308, 320 - - - O - - OECOLOGY, ii. 354 - - Oken, Lorenz, i. 95 - - Oken's history of development, i. 293 - - ---- philosophy of nature, i. 96 - - ---- theory of infusoria, i. 97 - - ---- ---- protoplasm, i. 97 - - Olynthus, ii. 141 - - Ontogenesis, i. 293 - - Ontogeny, i. 10; ii. 33 - - Orang, ii. 271, 275 - - Organisms, i. 5, 328 - - Organs, i. 5 - - Origin of language, ii. 302, 327 - - Osseous fishes, ii. 208, 211 - - Ovularia, ii. 132, 134 - - - P - - PACHYCARDIA, ii. 201 - - Palaeolithic period, ii. 11, 14 - - Palaeontology, i. 54 - - Palissy, i. 56 - - Palm ferns, ii. 82, 110 - - Pander, Christian, i. 294 - - Papuans, ii. 310, 333 - - Paradise, ii. 325 - - Parallelism of development, i. 313 - - Parthenogenesis, i. 197 - - Pedigree of amphibia, ii. 209 - - ---- anamnia, ii. 209 - - ---- apes, ii. 270 - - Permean system, ii. 11, 14 - - Petrifactions, i. 54 - - Phanerogama, ii. 80, 82, 108 - - Philosophy, i. 79; ii. 350 - - Phylogeny, i. 10; ii. 33 - - Phylum, ii. 42 - - Physiology, i. 21 - - Pithecoid, theory, ii. 356 - - Placentalia, ii. 240, 244 - - Planula, ii. 126, 135, 281 - - Planaea, ii. 125, 127 - - Planaeada, ii. 280 - - Plasma, i. 185, 330 - - Plasmogony, i. 339 - - Plastids, i. 347 - - Plastids, theory of, i. 347 - - Platyelminthes, ii. 148, 150 - - Platyrrhini, ii. 270, 272 - - Pleistocene system, ii. 15 - - Pliocene system, ii. 15, 16 - - Polar man, ii. 308, 317 - - Polyglottal, ii. 327, 333 - - Polynesians, ii. 308, 315 - - Polyphyletic theory of descent, ii. 45 - - Polyphylites, ii. 45, 303 - - Polyps, ii. 142 - - Polyp jellies, ii. 143, 144 - - Polysporogonia, i. 193 - - Population, number of, ii. 333 - - Porifera, ii. 139, 144 - - Primary mammals, ii. 239, 290 - - Primary period, ii. 11, 14 - - Primaeval algae, ii. 82, 84 - - ---- animals, ii. 131, 132 - - ---- history of man, ii. 298 - - ---- men, ii. 325 - - Primordial period, ii. 9, 14 - - Prochordata, ii. 278 - - Progenitors of man, ii. 279, 295 - - Progress, i. 277, 283 - - Promammalia, ii. 233, 239 - - Propagation, i. 183 - - ---- amphigonic, i. 195 - - ---- monogonic, i. 183 - - ---- non-sexual, i. 183 - - Propagation, sexual, i. 195 - - ---- virginal, i. 197 - - Protamnia, ii. 289, 295 - - Protamoebae, ii. 52 - - Prothallophytes, ii. 80, 97 - - Prothallus plants, ii. 80, 97 - - Protista, ii. 48 - - Protophyta, ii. 82, 85 - - Protoplasma, i. 185, 330 - - Protoplasts, ii. 51, 53 - - Protozoa, ii. 121, 131, 132 - - Purpose in nature, i. 19 - - Purposelessness in nature, i. 20 - - - R - - RADIATA, ii. 120 - - Radiolaria, i. 333, 371; ii. 65 - - Rapacious animals, ii. 240, 260 - - Recent system, ii. 15 - - Reptiles, ii. 222, 224 - - Rhizopoda, ii. 51, 61 - - Ringed worms, ii. 149, 150 - - Rodentia, ii. 241, 257 - - Romans, ii. 323, 331 - - Rotatoria, ii. 149, 150 - - Rotifera, ii. 150, 152 - - Round worms, ii. 149, 150 - - Rudimentary eyes, i. 13 - - ---- gristle, i. 12 - - ---- legs, i. 14 - - ---- lungs, i. 289 - - ---- mammary glands, i. 290 - - ---- muscles, i. 12 - - ---- nictitating membrane, i. 13 - - ---- organs, i. 12 - - ---- pistils, i. 15 - - ---- stamens, i. 15 - - ---- tails, i. 289 - - ---- teeth, i. 12 - - ---- wings, i. 287 - - - S - - SACK WORMS, ii. 283, 295 - - Sauria, ii. 222 - - Schaaffhausen, i. 110 - - Schleicher, August, i. 108; ii. 301 - - Schleiden, J. M., i. 109 - - Science, i. 9; ii. 335 - - Scolecida, ii. 283, 295 - - Sea stars, ii. 164, 166 - - ---- cucumbers, ii. 166, 171 - - Sea dragons, ii. 204 - - ---- lilies, ii. 166, 177 - - ---- nettles, ii. 141, 144 - - ---- urchins, ii. 166, 171 - - Secondary period, ii. 14, 20 - - Selection aesthetic, i. 268 - - ---- artificial, i. 152, 170, 254 - - ---- homochromic, i. 263 - - ---- medical, i. 173 - - ---- military, i. 171 - - ---- musical, i. 267 - - ---- natural, i. 168, 255 - - ---- psychical, i. 269 - - ---- sexual, i. 265 - - ---- Spartan, i. 170 - - Self-division, i. 191 - - Semites, ii. 322, 330 - - Serpents, ii. 223 - - Sexes, separation of, i. 244 - - Sexual characters, i. 209, 265 - - Silurian system, ii. 8, 14 - - Slavonians, ii. 323, 331 - - Snails, ii. 159, 160 - - Soul, the, i. 71; ii. 343, 362 - - Species, i. 41, 273, 304, 311 - - Specific development, i. 311 - - Spencer, Herbert, i. 119; ii. 367 - - Sperma, i. 197 - - Spiders, i. 180, 182 - - Spirobranchia, ii. 157, 160 - - Sponges, ii. 139, 144 - - Spores, formation of, i. 194 - - Stemmed plants, ii. 280 - - Straight-haired men, ii. 309, 314 - - Struggle for life, i. 161, 252 - - Synamoeba, ii. 125, 280 - - Systematic development, i. 313 - - System of animals, ii. 132 - - ---- apes, ii. 270 - - ---- Arabians, ii. 330 - - ---- arachnida, ii. 182 - - ---- Arians, ii. 331 - - ---- arthropoda, ii. 132 - - ---- articulata, ii. 177, 183 - - ---- catarrhini, ii. 270 - - ---- coelenterata, ii. 144 - - ---- crustacea, ii. 176 - - ---- didelphia, ii. 239 - - ---- echinoderma, ii. 166 - - ---- Egyptians, ii. 330 - - ---- fishes, ii. 208 - - ---- formations, ii. 15 - - ---- Germans, ii. 331 - - ---- gilled Insects, ii. 177 - - ---- Graeco-Romans, ii. 331 - - ---- Hamites, ii. 330 - - ---- hoofed animals, ii. 252 - - ---- human ancestors, ii. 295 - - ---- human races, ii. 308 - - ---- human species, ii. 308, 309 - - ---- Indians, ii. 331 - - ---- Indo-Germani, ii. 331 - - ---- insects, ii. 182 - - ---- mammalia, ii. 239 - - ---- mankind, ii. 295 - - ---- marsupials, ii. 239 - - ---- men and apes, ii. 271 - - ---- molluscs, ii. 160 - - ---- monodelphia, ii. 241 - - ---- organisms, ii. 74, 75 - - ---- placentalia, ii. 240 - - ---- plants, ii. 82 - - ---- platyrrhini, ii. 270 - - ---- protista, ii. 51 - - ---- reptiles, ii. 224 - - ---- Semites, ii. 330 - - ---- Slavonians, ii. 331 - - ---- spiders, ii. 182 - - ---- star fishes, ii. 167 - - ---- strata of the earth, ii. 15 - - ---- tracheata, ii. 182 - - ---- ungulata, ii. 252 - - ---- vegetable kingdom, ii. 83 - - ---- vertebrata, ii. 204 - - ---- worms, ii. 150 - - ---- zoophytes, ii. 144 - - - T - - TAIL OF MAN, i. 289, 308 - - Tangles, ii. 61, 82 - - Tartars, ii. 209, 317 - - Teleology, i. 100, 291 - - Teleostei, ii. 208, 211 - - Teleological conception of the universe, i. 20, 75 - - Tertiary period, ii. 14, 16 - - Thallophytes, ii. 80, 82 - - Thickness of the earth's crust, ii. 19 - - Thought, ii. 364 - - Thread plants, ii. 82, 93 - - Tocogony, i. 183 - - Tortoises, ii. 225 - - Tracheata, ii. 182 - - Transition forms, ii. 338 - - Transmutation, theory of, i. 4 - - Treviranus, i. 92 - - Trias system, ii. 12, 14 - - Tuft-haired men, ii. 307, 309 - - Tunicata, ii. 152, 200 - - Turbellaria, ii. 283 - - Turks, ii. 309, 316 - - - U - - UNGER, FRANZ, i. 109 - - Ungulata, ii. 249, 252 - - Unity in nature, i. 22, 338 - - Uralians, ii. 309, 317 - - - V - - Variability, i. 220 - - Variation, i. 219 - - Varieties, i. 276 - - Vertebrata, ii. 195, 205 - - Vital force, i. 22, 334 - - Vitalistic conception of the universe, i. 18 - - - W - - Wagner, Andreas, i. 138 - - Wagner, Moritz, i. 369 - - Wallace, Alfred, i. 135 - - Wallace's chorology, i. 361, 373 - - ---- theory of selection, i. 136 - - Well's theory of selection, i. 150 - - Whales, ii. 240, 251 - - Will, freedom of the, i. 113, 237, 364 - - Wolff's theory of development, i. 293 - - Woolly-haired men, ii. 307, 309 - - Worms, ii. 147, 150 - - - Z - - ZOOPHYTES, ii. 136, 144 - - - - -WORKS OF H. 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