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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 02:43:58 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 02:43:58 -0700 |
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text-indent: 1em;} + .figure p.in, .figcenter p.in, .figright p.in, .figleft p.in {margin: 0; text-indent: 8em;} + .figcenter p.poem {margin-left: 1em; text-align: left; text-indent: 0;} + .figcenter {margin: auto;} + .figright {float: right;} + .figleft {float: left;} + img.middle { border: none; vertical-align: middle } + + hr.pg { width: 100%; + margin-top: 3em; + margin-bottom: 0em; + margin-left: auto; + margin-right: auto; + height: 4px; + border-width: 4px 0 0 0; /* remove all borders except the top one */ + border-style: solid; + border-color: #000000; + clear: both; } + </style> +</head> +<body> +<h1>The Project Gutenberg eBook, The Variation of Animals and Plants Under +Domestication, Volume II (of 2), by Charles Darwin</h1> +<pre> +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 <a href = "http://www.gutenberg.org">www.gutenberg.org</a></pre> +<p>Title: The Variation of Animals and Plants Under Domestication, Volume II (of 2)</p> +<p>Author: Charles Darwin</p> +<p>Release Date: May 20, 2009 [eBook #28897]</p> +<p>Language: English</p> +<p>Character set encoding: ISO-8859-1</p> +<p>***START OF THE PROJECT GUTENBERG EBOOK THE VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION, VOLUME II (OF 2)***</p> +<p> </p> +<h3>E-text prepared by Steven Gibbs, Keith Edkins,<br /> + and the Project Gutenberg Online Distributed Proofreading Team<br /> + (http://www.pgdp.net)</h3> +<p> </p> +<table border="0" cellpadding="10" style="background-color: #ccccff;"> +<tr> +<td style="width:25%; vertical-align:top"> +Transcriber's note: +</td> +<td> +A few typographical errors have been corrected. They +appear in the text <span class="correction" title="explanation will pop up">like this</span>, and the +explanation will appear when the mouse pointer is moved over the marked +passage. +</td> +</tr> +</table> +<p> </p> +<hr class="pg" /> +<p> </p> +<p> </p> +<p> </p> + +<h2>THE VARIATION</h2> + +<p class="cenhead">OF</p> + +<h1>ANIMALS AND PLANTS</h1> + +<h2>UNDER DOMESTICATION.</h2> + +<h3><span class="sc">By</span> CHARLES DARWIN, M.A., F.R.S., &c.</h3> + +<h3>IN TWO VOLUMES.—<span class="sc">Vol</span>. II.</h3> + +<h4>WITH ILLUSTRATIONS.</h4> +<p> </p> +<p> </p> + +<h3>LONDON:</h3> + +<h3>JOHN MURRAY, ALBEMARLE STREET.</h3> + +<h3>1868.</h3> + +<p class="cenhead"><i>The right of Translation is reserved.</i></p> + +<p class="cenhead"><span class="scac">LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET, AND CHARING CROSS.</span></p> + +<hr class="full" /> + +<p><!-- Page iii --><span class="pagenum"><a name="pageiii"></a>{iii}</span></p> + +<h2>CONTENTS OF VOLUME II.</h2> + +<h3>CHAPTER XII.</h3> + +<p class="cenhead">INHERITANCE.</p> + + <p><span class="scac">WONDERFUL NATURE OF INHERITANCE</span>—<span + class="scac">PEDIGREES OF OUR DOMESTICATED ANIMALS</span>—<span + class="scac">INHERITANCE NOT DUE TO CHANCE</span>—<span + class="scac">TRIFLING CHARACTERS INHERITED</span>—<span + class="scac">DISEASES INHERITED</span>—<span + class="scac">PECULIARITIES IN THE EYE INHERITED</span>—<span + class="scac">DISEASES IN THE HORSE</span>—<span + class="scac">LONGEVITY AND VIGOUR</span>—<span + class="scac">ASYMMETRICAL DEVIATIONS OF STRUCTURE</span>—<span + class="scac">POLYDACTYLISM AND REGROWTH OF SUPERNUMERARY DIGITS AFTER + AMPUTATION</span>—<span class="scac">CASES OF SEVERAL CHILDREN + SIMILARLY AFFECTED FROM NON-AFFECTED PARENTS</span>—<span + class="scac">WEAK AND FLUCTUATING INHERITANCE: IN WEEPING TREES, IN + DWARFNESS, COLOUR OF FRUIT AND FLOWERS, COLOUR OF + HORSES</span>—<span class="scac">NON-INHERITANCE IN CERTAIN + CASES</span>—<span class="scac">INHERITANCE OF STRUCTURE AND HABITS + OVERBORNE BY HOSTILE CONDITIONS OF LIFE, BY INCESSANTLY RECURRING + VARIABILITY, AND BY REVERSION</span>—<span + class="scac">CONCLUSION</span> ... Page <a href="#page1">1</a></p> + +<h3>CHAPTER XIII.</h3> + +<p class="cenhead">INHERITANCE <i>continued</i>—REVERSION OR ATAVISM.</p> + + <p><span class="scac">DIFFERENT FORMS OF REVERSION</span>—<span + class="scac">IN PURE OR UNCROSSED BREEDS, AS IN PIGEONS, FOWLS, HORNLESS + CATTLE AND SHEEP, IN CULTIVATED PLANTS</span>—<span + class="scac">REVERSION IN FERAL ANIMALS AND PLANTS</span>—<span + class="scac">REVERSION IN CROSSED VARIETIES AND + SPECIES</span>—<span class="scac">REVERSION THROUGH + BUD-PROPAGATION, AND BY SEGMENTS IN THE SAME FLOWER OR + FRUIT</span>—<span class="scac">IN DIFFERENT PARTS OF THE BODY IN + THE SAME ANIMAL</span>—<span class="scac">THE ACT OF CROSSING A + DIRECT CAUSE OF REVERSION, VARIOUS CASES OF, WITH + INSTINCTS</span>—<span class="scac">OTHER PROXIMATE CAUSES OF + REVERSION</span>—<span class="scac">LATENT + CHARACTERS</span>—<span class="scac">SECONDARY SEXUAL + CHARACTERS</span>—<span class="scac">UNEQUAL DEVELOPMENT OF THE TWO + SIDES OF THE BODY</span>—<span class="scac"><span + class="correction" title="Original reads `ARPEARANCE'.">APPEARANCE</span> + WITH ADVANCING AGE OF CHARACTERS DERIVED FROM A CROSS</span>—<span + class="scac">THE GERM WITH ALL ITS LATENT CHARACTERS A WONDERFUL + OBJECT</span>—<span class="scac">MONSTROSITIES</span>—<span + class="scac">PELORIC FLOWERS DUE IN SOME CASES TO REVERSION</span> ... + Page <a href="#page28">28</a></p> + +<h3>CHAPTER XIV.</h3> + +<p class="cenhead">INHERITANCE <i>continued</i>—FIXEDNESS OF CHARACTER—PREPOTENCY—SEXUAL +LIMITATION—CORRESPONDENCE OF AGE.</p> + + <p><span class="scac">FIXEDNESS OF CHARACTER APPARENTLY NOT DUE TO + ANTIQUITY OF INHERITANCE</span>—<span class="scac">PREPOTENCY OF + TRANSMISSION IN INDIVIDUALS OF THE SAME FAMILY, IN CROSSED BREEDS AND + SPECIES; OFTEN STRONGER IN ONE SEX THAN THE OTHER; SOMETIMES DUE TO THE + SAME CHARACTER BEING PRESENT AND VISIBLE IN ONE BREED AND LATENT IN THE + OTHER</span>—<span class="scac">INHERITANCE AS LIMITED BY + SEX</span>—<span class="scac">NEWLY-ACQUIRED CHARACTERS IN OUR + DOMESTICATED ANIMALS OFTEN TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST + BY ONE SEX ALONE</span>—<span class="scac">INHERITANCE AT + CORRESPONDING PERIODS OF LIFE</span>—<span class="scac">THE + IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRYOLOGY; AS EXHIBITED IN + DOMESTICATED ANIMALS; AS EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF + INHERITED DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN + THE PARENT</span>—<span class="scac">SUMMARY OF THE THREE PRECEDING + CHAPTERS</span> ... Page <a href="#page62">62</a></p> + +<p><!-- Page iv --><span class="pagenum"><a name="pageiv"></a>{iv}</span></p> + +<h3>CHAPTER XV.</h3> + +<p class="cenhead">ON CROSSING.</p> + + <p><span class="scac">FREE INTERCROSSING OBLITERATES THE DIFFERENCES + BETWEEN ALLIED BREEDS</span>—<span class="scac">WHEN THE NUMBERS OF + TWO COMMINGLING BREEDS ARE UNEQUAL, ONE ABSORBS THE + OTHER</span>—<span class="scac">THE RATE OF ABSORPTION DETERMINED + BY PREPOTENCY OF TRANSMISSION, BY THE CONDITIONS OF LIFE, AND BY NATURAL + SELECTION</span>—<span class="scac">ALL ORGANIC BEINGS OCCASIONALLY + INTERCROSS; APPARENT EXCEPTIONS</span>—<span class="scac">ON + CERTAIN CHARACTERS INCAPABLE OF FUSION; CHIEFLY OR EXCLUSIVELY THOSE + WHICH HAVE SUDDENLY APPEARED IN THE INDIVIDUAL</span>—<span + class="scac">ON THE MODIFICATION OF OLD RACES, AND THE FORMATION OF NEW + RACES, BY CROSSING</span>—<span class="scac">SOME CROSSED RACES + HAVE BRED TRUE FROM THEIR FIRST PRODUCTION</span>—<span + class="scac">ON THE CROSSING OF DISTINCT SPECIES IN RELATION TO THE + FORMATION OF DOMESTIC RACES</span> ... Page <a href="#page85">85</a></p> + +<h3>CHAPTER XVI.</h3> + +<p class="cenhead">CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF +VARIETIES—INFLUENCE OF DOMESTICATION ON FERTILITY.</p> + + <p><span class="scac">DIFFICULTIES IN JUDGING OF THE FERTILITY OF + VARIETIES WHEN CROSSED</span>—<span class="scac">VARIOUS CAUSES + WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD OF BREEDING AND SEXUAL + PREFERENCE</span>—<span class="scac">VARIETIES OF WHEAT SAID TO BE + STERILE WHEN CROSSED</span>—<span class="scac">VARIETIES OF MAIZE, + VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO, RENDERED IN SOME + DEGREE MUTUALLY STERILE</span>—<span class="scac">DOMESTICATION + ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES WHEN + CROSSED</span>—<span class="scac">ON THE INCREASED FERTILITY OF + UNCROSSED ANIMALS AND PLANTS FROM DOMESTICATION AND CULTIVATION</span> + ... Page <a href="#page100">100</a></p> + +<h3>CHAPTER XVII.</h3> + +<p class="cenhead">ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL +EFFECTS OF CLOSE INTERBREEDING.</p> + + <p><span class="scac">DEFINITION OF CLOSE + INTERBREEDING</span>—<span class="scac">AUGMENTATION OF MORBID + TENDENCIES</span>—<span class="scac">GENERAL EVIDENCE ON THE GOOD + EFFECTS DERIVED FROM CROSSING, AND ON THE EVIL EFFECTS FROM CLOSE + INTERBREEDING</span>—<span class="scac">CATTLE, CLOSELY INTERBRED; + HALF-WILD CATTLE LONG KEPT IN THE SAME PARKS</span>—<span + class="scac">SHEEP</span>—<span + class="scac">FALLOW-DEER</span>—<span + class="scac">DOGS</span>—<span + class="scac">RABBITS</span>—<span + class="scac">PIGS</span>—<span class="scac">MAN, ORIGIN OF HIS + ABHORRENCE OF INCESTUOUS MARRIAGES</span>—<span + class="scac">FOWLS</span>—<span + class="scac">PIGEONS</span>—<span + class="scac">HIVE-BEES</span>—<span class="scac">PLANTS, GENERAL + CONSIDERATIONS ON THE BENEFITS DERIVED FROM CROSSING</span>—<span + class="scac">MELONS, FRUIT-TREES, PEAS, CABBAGES, WHEAT, AND + FOREST-TREES</span>—<span class="scac">ON THE INCREASED SIZE OF + HYBRID PLANTS, NOT EXCLUSIVELY DUE TO THEIR STERILITY</span>—<span + class="scac">ON CERTAIN PLANTS WHICH EITHER NORMALLY OR ABNORMALLY ARE + SELF-IMPOTENT, BUT ARE FERTILE, BOTH ON THE MALE AND FEMALE SIDE, WHEN + CROSSED WITH DISTINCT INDIVIDUALS EITHER OF THE SAME OR ANOTHER + SPECIES</span>—<span class="scac">CONCLUSION</span> ... Page <a + href="#page114">114</a></p> + +<p><!-- Page v --><span class="pagenum"><a name="pagev"></a>{v}</span></p> + +<h3>CHAPTER XVIII.</h3> + +<p class="cenhead">ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED +CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES.</p> + + <p><span class="scac">ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE + CONDITIONS OF LIFE</span>—<span class="scac">STERILITY FROM CHANGED + CONDITIONS, IN ANIMALS, IN THEIR NATIVE COUNTRY AND IN + MENAGERIES</span>—<span class="scac">MAMMALS, BIRDS, AND + INSECTS</span>—<span class="scac">LOSS OF SECONDARY SEXUAL + CHARACTERS AND OF INSTINCTS</span>—<span class="scac">CAUSES OF + STERILITY</span>—<span class="scac">STERILITY OF DOMESTICATED + ANIMALS FROM CHANGED CONDITIONS</span>—<span class="scac">SEXUAL + INCOMPATIBILITY OF INDIVIDUAL ANIMALS</span>—<span + class="scac">STERILITY OF PLANTS FROM CHANGED CONDITIONS OF + LIFE</span>—<span class="scac">CONTABESCENCE OF THE + ANTHERS</span>—<span class="scac">MONSTROSITIES AS A CAUSE OF + STERILITY</span>—<span class="scac">DOUBLE + FLOWERS</span>—<span class="scac">SEEDLESS FRUIT</span>—<span + class="scac">STERILITY FROM THE EXCESSIVE DEVELOPMENT OF THE ORGANS OF + VEGETATION</span>—<span class="scac">FROM LONG-CONTINUED + PROPAGATION BY BUDS</span>—<span class="scac">INCIPIENT STERILITY + THE PRIMARY CAUSE OF DOUBLE FLOWERS AND SEEDLESS FRUIT</span> ... Page <a + href="#page145">145</a></p> + +<h3>CHAPTER XIX.</h3> + +<p class="cenhead">SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS +ON HYBRIDISM.</p> + + <p><span class="scac">ON THE EFFECTS OF CROSSING</span>—<span + class="scac">THE INFLUENCE OF DOMESTICATION ON + FERTILITY</span>—<span class="scac">CLOSE + INTERBREEDING</span>—<span class="scac">GOOD AND EVIL RESULTS FROM + CHANGED CONDITIONS OF LIFE</span>—<span class="scac">VARIETIES WHEN + CROSSED NOT INVARIABLY FERTILE</span>—<span class="scac">ON THE + DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND + VARIETIES</span>—<span class="scac">CONCLUSIONS WITH RESPECT TO + HYBRIDISM</span>—<span class="scac">LIGHT THROWN ON HYBRIDISM BY + THE ILLEGITIMATE PROGENY OF DIMORPHIC AND TRIMORPHIC + PLANTS</span>—<span class="scac">STERILITY OF CROSSED SPECIES DUE + TO DIFFERENCES CONFINED TO THE REPRODUCTIVE SYSTEM</span>—<span + class="scac">NOT ACCUMULATED THROUGH NATURAL SELECTION</span>—<span + class="scac">REASONS WHY DOMESTIC VARIETIES ARE NOT MUTUALLY + STERILE</span>—<span class="scac">TOO MUCH STRESS HAS BEEN LAID ON + THE DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED + VARIETIES</span>—<span class="scac">CONCLUSION</span> ... Page <a + href="#page173">173</a></p> + +<h3>CHAPTER XX.</h3> + +<p class="cenhead">SELECTION BY MAN.</p> + + <p><span class="scac">SELECTION A DIFFICULT ART</span>—<span + class="scac">METHODICAL, UNCONSCIOUS, AND NATURAL + SELECTION</span>—<span class="scac">RESULTS OF METHODICAL + SELECTION</span>—<span class="scac">CARE TAKEN IN + SELECTION</span>—<span class="scac">SELECTION WITH + PLANTS</span>—<span class="scac">SELECTION CARRIED ON BY THE + ANCIENTS, AND BY SEMI-CIVILISED PEOPLE</span>—<span + class="scac">UNIMPORTANT CHARACTERS OFTEN ATTENDED TO</span>—<span + class="scac">UNCONSCIOUS SELECTION</span>—<span class="scac">AS + CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR DOMESTICATED ANIMALS CHANGED + THROUGH THE ACTION OF UNCONSCIOUS SELECTION</span>—<span + class="scac">INFLUENCE OF DIFFERENT BREEDERS ON THE SAME + SUB-VARIETY</span>—<span class="scac">PLANTS AS AFFECTED BY + UNCONSCIOUS SELECTION</span>—<span class="scac">EFFECTS OF + SELECTION AS SHOWN BY THE GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST + VALUED BY MAN</span> ... Page <a href="#page192">192</a></p> + +<p><!-- Page vi --><span class="pagenum"><a name="pagevi"></a>{vi}</span></p> + +<h3>CHAPTER XXI.</h3> + +<p class="cenhead">SELECTION—<i>continued.</i></p> + + <p><span class="scac">NATURAL SELECTION AS AFFECTING DOMESTIC + PRODUCTIONS</span>—<span class="scac">CHARACTERS WHICH APPEAR OF + TRIFLING VALUE OFTEN OF REAL IMPORTANCE</span>—<span + class="scac">CIRCUMSTANCES FAVOURABLE TO SELECTION BY + MAN</span>—<span class="scac">FACILITY IN PREVENTING CROSSES, AND + THE NATURE OF THE CONDITIONS</span>—<span class="scac">CLOSE + ATTENTION AND PERSEVERANCE INDISPENSABLE</span>—<span + class="scac">THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS ESPECIALLY + FAVOURABLE</span>—<span class="scac">WHEN NO SELECTION IS APPLIED, + DISTINCT RACES ARE NOT FORMED</span>—<span class="scac">HIGHLY-BRED + ANIMALS LIABLE TO DEGENERATION</span>—<span class="scac">TENDENCY + IN MAN TO CARRY THE SELECTION OF EACH CHARACTER TO AN EXTREME POINT, + LEADING TO DIVERGENCE OF CHARACTER, RARELY TO + CONVERGENCE</span>—<span class="scac">CHARACTERS CONTINUING TO VARY + IN THE SAME DIRECTION IN WHICH THEY HAVE ALREADY + VARIED</span>—<span class="scac">DIVERGENCE OF CHARACTER, WITH THE + EXTINCTION OF INTERMEDIATE VARIETIES, LEADS TO DISTINCTNESS IN OUR + DOMESTIC RACES</span>—<span class="scac">LIMIT TO THE POWER OF + SELECTION</span>—<span class="scac">LAPSE OF TIME + IMPORTANT</span>—<span class="scac">MANNER IN WHICH DOMESTIC RACES + HAVE ORIGINATED</span>—<span class="scac">SUMMARY</span> ... Page + <a href="#page224">224</a></p> + +<h3>CHAPTER XXII.</h3> + +<p class="cenhead">CAUSES OF VARIABILITY.</p> + + <p><span class="scac">VARIABILITY DOES NOT NECESSARILY ACCOMPANY + REPRODUCTION</span>—<span class="scac">CAUSES ASSIGNED BY VARIOUS + AUTHORS</span>—<span class="scac">INDIVIDUAL + DIFFERENCES</span>—<span class="scac">VARIABILITY OF EVERY KIND DUE + TO CHANGED CONDITIONS OF LIFE</span>—<span class="scac">ON THE + NATURE OF SUCH CHANGES</span>—<span class="scac">CLIMATE, FOOD, + EXCESS OF NUTRIMENT</span>—<span class="scac">SLIGHT CHANGES <span + class="correction" title="Original reads `SUFFICENT'." + >SUFFICIENT</span></span>—<span class="scac">EFFECTS OF GRAFTING ON + THE VARIABILITY OF SEEDLING-TREES</span>—<span + class="scac">DOMESTIC PRODUCTIONS BECOME HABITUATED TO CHANGED + CONDITIONS</span>—<span class="scac">ON THE ACCUMULATIVE ACTION OF + CHANGED CONDITIONS</span>—<span class="scac">CLOSE INTERBREEDING + AND THE IMAGINATION OF THE MOTHER SUPPOSED TO CAUSE + VARIABILITY</span>—<span class="scac">CROSSING AS A CAUSE OF THE + APPEARANCE OF NEW CHARACTERS</span>—<span class="scac">VARIABILITY + FROM THE COMMINGLING OF CHARACTERS AND FROM REVERSION</span>—<span + class="scac">ON THE MANNER AND PERIOD OF ACTION OF THE CAUSES WHICH + EITHER DIRECTLY, OR INDIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE + VARIABILITY</span> ... Page <a href="#page250">250</a></p> + +<h3>CHAPTER XXIII.</h3> + +<p class="cenhead">DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS +OF LIFE.</p> + + <p><span class="scac">SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE + ACTION OF CHANGED CONDITIONS, IN SIZE, COLOUR, CHEMICAL PROPERTIES, AND + IN THE STATE OF THE TISSUES</span>—<span class="scac">LOCAL + DISEASES</span>—<span class="scac">CONSPICUOUS MODIFICATIONS FROM + CHANGED CLIMATE OR FOOD, ETC.</span>—<span class="scac">PLUMAGE OF + BIRDS AFFECTED BY PECULIAR NUTRIMENT, AND BY THE INOCULATION OF + POISON</span>—<span class="scac">LAND-SHELLS</span>—<span + class="scac">MODIFICATIONS OF ORGANIC BEINGS IN A STATE OF NATURE THROUGH + THE DEFINITE ACTION OF EXTERNAL CONDITIONS</span>—<span + class="scac">COMPARISON OF AMERICAN AND EUROPEAN TREES</span>—<span + class="scac">GALLS</span>—<span class="scac">EFFECTS OF PARASITIC + FUNGI</span>—<span class="scac">CONSIDERATIONS OPPOSED TO THE + BELIEF IN THE POTENT INFLUENCE OF CHANGED EXTERNAL + CONDITIONS</span>—<span class="scac">PARALLEL SERIES OF + VARIETIES</span>—<span class="scac">AMOUNT OF VARIATION DOES NOT + CORRESPOND WITH THE DEGREE OF CHANGE IN THE CONDITIONS</span>—<span + class="scac">BUD-VARIATION</span>—<span class="scac">MONSTROSITIES + PRODUCED BY UNNATURAL TREATMENT</span>—<span + class="scac">SUMMARY</span> ... Page <a href="#page271">271</a></p> + +<p><!-- Page vii --><span class="pagenum"><a name="pagevii"></a>{vii}</span></p> + +<h3>CHAPTER XXIV.</h3> + +<p class="cenhead">LAWS OF VARIATION—USE AND DISUSE, ETC.</p> + + <p><span class="scac">NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE + ORGANISATION</span>—<span class="scac">ON THE EFFECTS OF THE + INCREASED USE AND DISUSE OF ORGANS</span>—<span + class="scac">CHANGED HABITS OF LIFE</span>—<span + class="scac">ACCLIMATISATION WITH ANIMALS AND PLANTS</span>—<span + class="scac">VARIOUS METHODS BY WHICH THIS CAN BE + EFFECTED</span>—<span class="scac">ARRESTS OF + DEVELOPMENT</span>—<span class="scac">RUDIMENTARY ORGANS</span> ... + Page <a href="#page293">293</a></p> + +<h3>CHAPTER XXV.</h3> + +<p class="cenhead">LAWS OF VARIATION, <i>continued</i>—CORRELATED VARIABILITY.</p> + + <p><span class="scac">EXPLANATION OF TERM</span>—<span + class="scac">CORRELATION AS CONNECTED WITH DEVELOPMENT</span>—<span + class="scac">MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED + SIZE OF PARTS</span>—<span class="scac">CORRELATED VARIATION OF + HOMOLOGOUS PARTS</span>—<span class="scac">FEATHERED FEET IN BIRDS + ASSUMING THE STRUCTURE OF THE WINGS</span>—<span + class="scac">CORRELATION BETWEEN THE HEAD AND THE + EXTREMITIES</span>—<span class="scac">BETWEEN THE SKIN AND DERMAL + APPENDAGES</span>—<span class="scac">BETWEEN THE ORGANS OF SIGHT + AND HEARING</span>—<span class="scac">CORRELATED MODIFICATIONS IN + THE ORGANS OF PLANTS</span>—<span class="scac">CORRELATED + MONSTROSITIES</span>—<span class="scac">CORRELATION BETWEEN THE + SKULL AND EARS</span>—<span class="scac">SKULL AND CREST OF + FEATHERS</span>—<span class="scac">SKULL AND + HORNS</span>—<span class="scac">CORRELATION OF GROWTH COMPLICATED + BY THE ACCUMULATED EFFECTS OF NATURAL SELECTION</span>—<span + class="scac">COLOUR AS CORRELATED WITH CONSTITUTIONAL + PECULIARITIES</span> ... Page <a href="#page319">319</a></p> + +<h3>CHAPTER XXVI.</h3> + +<p class="cenhead">LAWS OF VARIATION, <i>continued</i>—SUMMARY.</p> + + <p><span class="scac">ON THE AFFINITY AND COHESION OF HOMOLOGOUS + PARTS</span>—<span class="scac">ON THE VARIABILITY OF MULTIPLE AND + HOMOLOGOUS PARTS</span>—<span class="scac">COMPENSATION OF + GROWTH</span>—<span class="scac">MECHANICAL + PRESSURE</span>—<span class="scac">RELATIVE POSITION OF FLOWERS + WITH RESPECT TO THE AXIS OF THE PLANT, AND OF SEEDS IN THE CAPSULE, AS + INDUCING VARIATION</span>—<span class="scac">ANALOGOUS OR PARALLEL + VARIETIES</span>—<span class="scac">SUMMARY OF THE THREE LAST + CHAPTERS</span> ... Page <a href="#page339">339</a></p> + +<h3>CHAPTER XXVII.</h3> + +<p class="cenhead">PROVISIONAL HYPOTHESIS OF PANGENESIS.</p> + + <p><span class="scac">PRELIMINARY REMARKS</span>—<span + class="scac">FIRST PART:</span>—<span class="scac">THE FACTS TO BE + CONNECTED UNDER A SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF + REPRODUCTION</span>—<span class="scac">THE DIRECT ACTION OF THE + MALE ELEMENT ON THE FEMALE</span>—<span + class="scac">DEVELOPMENT</span>—<span class="scac">THE FUNCTIONAL + INDEPENDENCE OF THE ELEMENTS OR UNITS OF THE BODY</span>—<span + class="scac">VARIABILITY</span>—<span + class="scac">INHERITANCE</span>—<span + class="scac">REVERSION</span>.</p> + + <p><span class="scac">SECOND PART:</span>—<span + class="scac">STATEMENT OF THE HYPOTHESIS</span>—<span + class="scac">HOW FAR THE NECESSARY ASSUMPTIONS ARE + IMPROBABLE</span>—<span class="scac">EXPLANATION BY AID OF THE + HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST + PART</span>—<span class="scac">CONCLUSION</span> ... Page <a + href="#page357">357</a></p> + +<p><!-- Page viii --><span class="pagenum"><a name="pageviii"></a>{viii}</span></p> + +<h3>CHAPTER XXVIII.</h3> + +<p class="cenhead">CONCLUDING REMARKS.</p> + + <p><span class="scac">DOMESTICATION</span>—<span + class="scac">NATURE AND CAUSES OF VARIABILITY</span>—<span + class="scac">SELECTION</span>—<span class="scac">DIVERGENCE AND + DISTINCTNESS OF CHARACTER</span>—<span class="scac">EXTINCTION OF + RACES</span>—<span class="scac">CIRCUMSTANCES FAVOURABLE TO + SELECTION BY MAN</span>—<span class="scac">ANTIQUITY OF CERTAIN + RACES</span>—<span class="scac">THE QUESTION WHETHER EACH + PARTICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED</span> ... Page <a + href="#page405">405</a></p> + + <p><span class="sc">Index</span> ... Page <a href="#page433">433</a></p> + +<hr class="short" /> + +<p class="cenhead">ERRATA.</p> + + <div class="poem"> + <div class="stanza"> + <p>Vol. II., pp. 18, 232, 258, <i>for</i> Cratægus oxycantha, <i>read</i> oxyacantha.</p> + <p> ,, p. 98, 8 lines from top, <i>for</i> Dianthus armoria <i>read</i> armeria.</p> + <p> ,, ,, 156, 15 lines from bottom, <i>for</i> Casuarinus <i>read</i> Casuarius.</p> + <p> ,, ,, ,, 4 lines from bottom, <i>for</i> Grus cineria <i>read</i> cinerea.</p> + <p> ,, ,, 168, 11 lines from top, <i>for</i> Œsculus <i>read</i> Æsculus.</p> + <p> ,, ,, 300, 3 lines from top, <i>for</i> anastomising <i>read</i> anastomosing.</p> + <p> ,, ,, ,, foot-note, <i>for</i> Birckell <i>read</i> Brickell.</p> + </div> + </div> + +<hr class="full" /> + +<p><!-- Page 1 --><span class="pagenum"><a name="page1"></a>{1}</span></p> + +<p class="cenhead">THE</p> + +<h2>VARIATION OF ANIMALS AND PLANTS</h2> + +<h3>UNDER DOMESTICATION.</h3> + +<hr class="short" /> + +<h3>CHAPTER XII.</h3> + +<p class="cenhead">INHERITANCE.</p> + +<blockquote class="b1n"> + + <p><span class="scac">WONDERFUL NATURE OF INHERITANCE</span>—<span + class="scac">PEDIGREES OF OUR DOMESTICATED ANIMALS</span>—<span + class="scac">INHERITANCE NOT DUE TO CHANCE</span>—<span + class="scac">TRIFLING CHARACTERS INHERITED</span>—<span + class="scac">DISEASES INHERITED</span>—<span + class="scac">PECULIARITIES IN THE EYE INHERITED</span>—<span + class="scac">DISEASES IN THE HORSE</span>—<span + class="scac">LONGEVITY AND VIGOUR</span>—<span + class="scac">ASYMMETRICAL DEVIATIONS OF STRUCTURE</span>—<span + class="scac">POLYDACTYLISM AND REGROWTH OF SUPERNUMERARY DIGITS AFTER + AMPUTATION</span>—<span class="scac">CASES OF SEVERAL CHILDREN + SIMILARLY AFFECTED FROM NON-AFFECTED PARENTS</span>—<span + class="scac">WEAK AND FLUCTUATING INHERITANCE: IN WEEPING TREES, IN + DWARFNESS, COLOUR OF FRUIT AND FLOWERS, COLOUR OF + HORSES</span>—<span class="scac">NON-INHERITANCE IN CERTAIN + CASES</span>—<span class="scac">INHERITANCE OF STRUCTURE AND HABITS + OVERBORNE BY HOSTILE CONDITIONS OF LIFE, BY INCESSANTLY RECURRING + VARIABILITY, AND BY REVERSION</span>—<span + class="scac">CONCLUSION.</span></p> + +</blockquote> + + <p>The subject of inheritance is an immense one, and has been treated by + many authors. One work alone, 'De l'Hérédité Naturelle,' by Dr. Prosper + Lucas, runs to the length of 1562 pages. We must confine ourselves to + certain points which have an important bearing on the general subject of + variation, both with domestic and natural productions. It is obvious that + a variation which is not inherited throws no light on the derivation of + species, nor is of any service to man, except in the case of perennial + plants, which can be propagated by buds.</p> + + <p>If animals and plants had never been domesticated, and wild ones alone + had been observed, we should probably never have heard the saying, that + "like begets like." The proposition would have been as self-evident, as + that all the buds on the same tree are alike, though neither proposition + is strictly true. For, as has often been remarked, probably no two + individuals are <!-- Page 2 --><span class="pagenum"><a + name="page2"></a>{2}</span>identically the same. All wild animals + recognise each other, which shows that there is some difference between + them; and when the eye is well practised, the shepherd knows each sheep, + and man can distinguish a fellow-man out of millions on millions of other + men. Some authors have gone so far as to maintain that the production of + slight differences is as much a necessary function of the powers of + generation, as the production of offspring like their parents. This view, + as we shall see in a future chapter, is not theoretically probable, + though practically it holds good. The saying that "like begets like" has + in fact arisen from the perfect confidence felt by breeders, that a + superior or inferior animal will generally reproduce its kind; but this + very superiority or inferiority shows that the individual in question has + departed slightly from its type.</p> + + <p>The whole subject of inheritance is wonderful. When a new character + arises, whatever its nature may be, it generally tends to be inherited, + at least in a temporary and sometimes in a most persistent manner. What + can be more wonderful than that some trifling peculiarity, not + primordially attached to the species, should be transmitted through the + male or female sexual cells, which are so minute as not to be visible to + the naked eye, and afterwards through the incessant changes of a long + course of development, undergone either in the womb or in the egg, and + ultimately appear in the offspring when mature, or even when quite old, + as in the case of certain diseases? Or again, what can be more wonderful + than the well-ascertained fact that the minute ovule of a good milking + cow will produce a male, from whom a cell, in union with an ovule, will + produce a female, and she, when mature, will have large mammary glands, + yielding an abundant supply of milk, and even milk of a particular + quality? Nevertheless, the real subject of surprise is, as Sir H. Holland + has well remarked,<a name="NtA_1" href="#Nt_1"><sup>[1]</sup></a> not + that a character should be inherited, but that any should ever fail to be + inherited. In a future chapter, devoted to an hypothesis which I have + termed pangenesis, an attempt will be made to show the means by which + characters of all kinds are transmitted from generation to + generation.</p> + +<p><!-- Page 3 --><span class="pagenum"><a name="page3"></a>{3}</span></p> + + <p>Some writers,<a name="NtA_2" href="#Nt_2"><sup>[2]</sup></a> who have + not attended to natural history, have attempted to show that the force of + inheritance has been much exaggerated. The breeders of animals would + smile at such simplicity; and if they condescended to make any answer, + might ask what would be the chance of winning a prize if two inferior + animals were paired together? They might ask whether the half-wild Arabs + were led by theoretical notions to keep pedigrees of their horses? Why + have pedigrees been scrupulously kept and published of the Shorthorn + cattle, and more recently of the Hereford breed? Is it an illusion that + these recently improved animals safely transmit their excellent qualities + even when crossed with other breeds? have the Shorthorns, without good + reason, been purchased at immense prices and exported to almost every + quarter of the globe, a thousand guineas having been given for a bull? + With greyhounds pedigrees have likewise been kept, and the names of such + dogs, as Snowball, Major, &c., are as well known to coursers as those + of Eclipse and Herod on the turf. Even with the Gamecock pedigrees of + famous strains were formerly kept, and extended back for a century. With + pigs, the Yorkshire and Cumberland breeders "preserve and print + pedigrees;" and to show how such highly-bred animals are valued, I may + mention that Mr. Brown, who won all the first prizes for small breeds at + Birmingham in 1850, sold a young sow and boar of his breed to Lord Ducie + for 43 guineas; the sow alone was afterwards sold to the Rev. F. Thursby + for 65 guineas; who writes, "she paid me very well, having sold her + produce for 300<i>l</i>., and having now four breeding sows from her."<a + name="NtA_3" href="#Nt_3"><sup>[3]</sup></a> Hard cash paid down, over + and over again, is an excellent test of inherited superiority. In fact, + the whole art of breeding, from which such great results have been + attained during the present century, depends on the inheritance of each + small <!-- Page 4 --><span class="pagenum"><a + name="page4"></a>{4}</span>detail of structure. But inheritance is not + certain; for if it were, the breeder's art<a name="NtA_4" + href="#Nt_4"><sup>[4]</sup></a> would be reduced to a certainty, and + there would be little scope left for all that skill and perseverance + shown by the men who have left an enduring monument of their success in + the present state of our domesticated animals.</p> + + <p>It is hardly possible, within a moderate compass, to impress on the + mind of those who have not attended to the subject, the full conviction + of the force of inheritance which is slowly acquired by rearing animals, + by studying the many treatises which have been published on the various + domestic animals, and by conversing with breeders. I will select a few + facts of the kind, which, as far as I can judge, have most influenced my + own mind. With man and the domestic animals, certain peculiarities have + appeared in an individual, at rare intervals, or only once or twice in + the history of the world, but have reappeared in several of the children + and grandchildren. Thus Lambert, "the porcupine-man," whose skin was + thickly covered with warty projections, which were periodically moulted, + had all his six children and two grandsons similarly affected.<a + name="NtA_5" href="#Nt_5"><sup>[5]</sup></a> The face and body being + covered with long hair, accompanied by deficient teeth (to which I shall + hereafter refer), occurred in three successive generations in a Siamese + family; but this case is not unique, as a woman<a name="NtA_6" + href="#Nt_6"><sup>[6]</sup></a> with a completely hairy face was + exhibited in London in 1663, and another instance has recently occurred. + Colonel Hallam<a name="NtA_7" href="#Nt_7"><sup>[7]</sup></a> has + described a race of two-legged pigs, "the hinder extremities being + entirely wanting;" and this deficiency was transmitted through three + generations. In fact, all races presenting any remarkable peculiarity, + such as solid-hoofed swine, Mauchamp sheep, niata cattle, &c., are + instances of the long-continued inheritance of rare deviations of + structure.</p> + + <p>When we reflect that certain extraordinary peculiarities have <!-- + Page 5 --><span class="pagenum"><a name="page5"></a>{5}</span>thus + appeared in a single individual out of many millions, all exposed in the + same country to the same general conditions of life, and, again, that the + same extraordinary peculiarity has sometimes appeared in individuals + living under widely different conditions of life, we are driven to + conclude that such peculiarities are not directly due to the action of + the surrounding conditions, but to unknown laws acting on the + organisation or constitution of the individual;—that their + production stands in hardly closer relation to the conditions than does + life itself. If this be so, and the occurrence of the same unusual + character in the child and parent cannot be attributed to both having + been exposed to the same unusual conditions, then the following problem + is worth consideration, as showing that the result cannot be due, as some + authors have supposed, to mere coincidence, but must be consequent on the + members of the same family inheriting something in common in their + constitution. Let it be assumed that, in a large population, a particular + affection occurs on an average in one out of a million, so that the <i>à + priori</i> chance that an individual taken at random will be so affected + is only one in a million. Let the population consist of sixty millions, + composed, we will assume, of ten million families, each containing six + members. On these data, Professor Stokes has calculated for me that the + odds will be no less than 8333 millions to 1 that in the ten million + families there will not be even a single family in which one parent and + two children will be affected by the peculiarity in question. But + numerous cases could be given, in which several children have been + affected by the same rare peculiarity with one of their parents; and in + this case, more especially if the grandchildren be included in the + calculation, the odds against mere coincidence become something + prodigious, almost beyond enumeration.</p> + + <p>In some respects the evidence of inheritance is more striking when we + consider the reappearance of trifling peculiarities. Dr. Hodgkin formerly + told me of an English family in which, for many generations, some members + had a single lock differently coloured from the rest of the hair. I knew + an Irish gentleman, who, on the right side of his head, had a small white + lock in the midst of his dark hair: he assured me that his grandmother + had <!-- Page 6 --><span class="pagenum"><a name="page6"></a>{6}</span>a + similar lock on the same side, and his mother on the opposite side. But + it is superfluous to give instances; every shade of expression, which may + often be seen alike in parents and children, tells the same story. On + what a curious combination of corporeal structure, mental character, and + training, must handwriting depend! yet every one must have noted the + occasional close similarity of the handwriting in father and son, + although the father had not taught his son. A great collector of franks + assured me that in his collection there were several franks of father and + son hardly distinguishable except by their dates. Hofacker, in Germany, + remarks on the inheritance of handwriting; and it has even been asserted + that English boys when taught to write in France naturally cling to their + English manner of writing.<a name="NtA_8" href="#Nt_8"><sup>[8]</sup></a> + Gait, gestures, voice, and general bearing are all inherited, as the + illustrious Hunter and Sir A. Carlisle have insisted.<a name="NtA_9" + href="#Nt_9"><sup>[9]</sup></a> My father communicated to me two or three + striking instances, in one of which a man died during the early infancy + of his son, and my father, who did not see this son until grown up and + out of health, declared that it seemed to him as if his old friend had + risen from the grave, with all his highly peculiar habits and manners. + Peculiar manners pass into tricks, and several instances could be given + of their inheritance; as in the case, often quoted, of the father who + generally slept on his back, with his right leg crossed over the left, + and whose daughter, whilst an infant in the cradle, followed exactly the + same habit, though an attempt was made to cure her.<a name="NtA_10" + href="#Nt_10"><sup>[10]</sup></a> I will give one instance which has + fallen under my own observation, and which is curious from being a trick + associated with a peculiar state of mind, namely, pleasurable emotion. A + boy had the singular habit, when pleased, of rapidly moving his fingers + parallel to each other, and, when much excited, of raising both hands, + with the fingers still moving, to the sides of his face on a level with + the eyes; this boy, when almost an old man, could still hardly resist + this trick when much pleased, but from its absurdity concealed it. He had + eight children. Of these, a girl, when <!-- Page 7 --><span + class="pagenum"><a name="page7"></a>{7}</span>pleased, at the age of four + and a half years, moved her fingers in exactly the same way, and what is + still odder, when much excited, the raised both her hands, with her + fingers still moving, to the sides of her face, in exactly the same + manner as her father had done, and sometimes even still continued to do + when alone. I never heard of any one excepting this one man and his + little daughter who had this strange habit; and certainly imitation was + in this instance out of the question.</p> + + <p>Some writers have doubted whether those complex mental attributes, on + which genius and talent depend, are inherited, even when both parents are + thus endowed. But he who will read Mr. Galton's able paper<a + name="NtA_11" href="#Nt_11"><sup>[11]</sup></a> on hereditary talent will + have his doubts allayed.</p> + + <p>Unfortunately it matters not, as far as inheritance is concerned, how + injurious a quality or structure may be if compatible with life. No one + can read the many treatises<a name="NtA_12" + href="#Nt_12"><sup>[12]</sup></a> on hereditary disease and doubt this. + The ancients were strongly of this opinion, or, as Ranchin expresses it, + <i>Omnes Græci, Arabes, et Latini in eo consentiunt</i>. A long catalogue + could be given of all sorts of inherited malformations and of + predisposition to various diseases. With gout, fifty per cent. of the + cases observed in hospital practice are, according to Dr. Garrod, + inherited, and a greater percentage in private practice. Every one knows + how often insanity runs in families, and some of the cases given by Mr. + Sedgwick are awful,—as of a surgeon, whose brother, father, and + four paternal uncles were all insane, the latter dying by suicide; of a + Jew, whose father, mother, and six brothers and sisters were all mad; and + in some other cases several members of the same family, during three or + four successive generations, have committed suicide. Striking instances + <!-- Page 8 --><span class="pagenum"><a name="page8"></a>{8}</span>have + been recorded of epilepsy, consumption, asthma, stone in the bladder, + cancer, profuse bleeding from the slightest injuries, of the mother not + giving milk, and of bad parturition being inherited. In this latter + respect I may mention an odd case given by a good observer,<a + name="NtA_13" href="#Nt_13"><sup>[13]</sup></a> in which the fault lay in + the offspring, and not in the mother: in a part of Yorkshire the farmers + continued to select cattle with large hind-quarters, until they made a + strain called "Dutch-buttocked," and "the monstrous size of the buttocks + of the calf was frequently fatal to the cow, and numbers of cows were + annually lost in calving."</p> + +<blockquote class="b1n"> + + <p>Instead of giving numerous details on various inherited malformations + and diseases, I will confine myself to one organ, that which is the most + complex, delicate, and probably best-known in the human frame, namely, + the eye, with its accessory parts. To begin with the latter: I have heard + of a family in which parents and children were affected by drooping + eyelids, in so peculiar a manner, that they could not see without + throwing their heads backwards; and Sir A. Carlisle<a name="NtA_14" + href="#Nt_14"><sup>[14]</sup></a> specifies a pendulous fold to the + eyelids as inherited. "In a family," says Sir H. Holland,<a name="NtA_15" + href="#Nt_15"><sup>[15]</sup></a> "where the father had a singular + elongation of the upper eyelid, seven or eight children were born with + the same deformity; two or three other children having it not." Many + persons, as I year from Mr. Paget, have two or three of the hairs in + their eyebrows (apparently corresponding with the vibrissæ of the lower + animals) much longer than the others; and even so trifling a peculiarity + as this certainly runs in families.</p> + + <p>With respect to the eye itself, the highest authority in England, Mr. + Bowman, has been so kind as to give me the following remarks on certain + inherited imperfections. First, hypermetropia, or morbidly long sight: in + this affection, the organ, instead of being spherical, is too flat from + front to back, and is often altogether too small, so that the retina is + brought too forward for the focus of the humours; consequently a convex + glass is required for clear vision of near objects, and frequently even + of distant ones. This state occurs congenitally, or at a very early age, + often in several children of the same family, where one of the parents + has presented it.<a name="NtA_16" href="#Nt_16"><sup>[16]</sup></a> + Secondly, myopia, or short-sight, in which the eye is egg-shaped, and too + long from front to back; the retina in this case lies behind the focus, + and is therefore fitted to see distinctly only very near objects. This + condition is not commonly congenital, but comes on in youth, the + liability to it being well known to be transmissible from parent to + child. The change from the spherical to the ovoidal shape seems the + immediate <!-- Page 9 --><span class="pagenum"><a + name="page9"></a>{9}</span>consequence of something like inflammation of + the coats, under which they yield, and there is ground for believing that + it may often originate in causes acting directly on the individual + affected, and may thenceforward become transmissible. When both parents + are myopic Mr. Bowman has observed the hereditary tendency in this + direction to be heightened, and some of the children to be myopic at an + earlier age or in a higher degree than their parents. Thirdly, squinting + is a familiar example of hereditary transmission: it is frequently a + result of such optical defects as have been above mentioned; but the more + primary and uncomplicated forms of it are also sometimes in a marked + degree transmitted in a family. Fourthly, <i>Cataract</i>, or opacity of + the crystalline lens, is commonly observed in persons whose parents have + been similarly affected, and often at an earlier age in the children than + in the parents. Occasionally more than one child in a family is thus + afflicted, one of whose parents or other relation presents the senile + form of the complaint. When cataract affects several members of a family + in the same generation, it is often seen to commence at about the same + age in each; <i>e.g.</i>, in one family several infants or young persons + may suffer from it; in another, several persons of middle age. Mr. Bowman + also informs me that he has occasionally seen, in several members of the + same family, various defects in either the right or left eye; and Mr. + White Cooper has often seen peculiarities of vision confined to one eye + reappearing in the same eye in the offspring.<a name="NtA_17" + href="#Nt_17"><sup>[17]</sup></a></p> + + <p>The following cases are taken from an able paper by Mr. W. Sedgwick, + and from Dr. Prosper Lucas.<a name="NtA_18" + href="#Nt_18"><sup>[18]</sup></a> Amaurosis, either congenital or coming + on late in life, and causing total blindness, is often inherited; it has + been observed in three successive generations. Congenital absence of the + iris has likewise been transmitted for three generations, a cleft-iris + for four generations, being limited in this latter case to the males of + the family. Opacity of the cornea and congenital smallness of the eyes + have been inherited. Portal records a curious case, in which a father and + two sons were rendered blind, whenever the head was bent downwards, + apparently owing to the crystalline lens, with its capsule, slipping + through an unusually large pupil into the anterior chamber of the eye. + Day-blindness, or imperfect vision under a bright light, is inherited, as + is night-blindness, or an incapacity to see except under a strong light: + a case has been recorded, by M. Cunier, of this latter defect having + affected eighty-five members of the same family during six generations. + The singular incapacity of distinguishing colours, which has been called + <i>Daltonism</i>, is notoriously hereditary, and has been traced through + five generations, in which it was confined to the female sex.</p> + + <p>With respect to the colour of the iris: deficiency of colouring matter + is well known to be hereditary in albinoes. The iris of one eye being of + a different colour from that of the other, and the iris being spotted, + are cases which have been inherited. Mr. Sedgwick gives, in addition, on + the <!-- Page 10 --><span class="pagenum"><a + name="page10"></a>{10}</span>authority of Dr. Osborne,<a name="NtA_19" + href="#Nt_19"><sup>[19]</sup></a> the following curious instance of + strong inheritance: a family of sixteen sons and five daughters all had + eyes "resembling in miniature the markings on the back of a tortoiseshell + cat." The mother of this large family had three sisters and a brother all + similarly marked, and they derived this peculiarity from their mother, + who belonged to a family notorious for transmitting it to their + posterity.</p> + + <p>Finally, Dr. Lucas emphatically remarks that there is not one single + faculty of the eye which is not subject to anomalies; and not one which + is not subjected to the principle of inheritance. Mr. Bowman agrees with + the general truth of this proposition; which of course does not imply + that all malformations are necessarily inherited; this would not even + follow if both parents were affected by an anomaly which in most cases + was transmissible.</p> + +</blockquote> + + <p>Even if no single fact had been known with respect to the inheritance + of disease and malformations by man, the evidence would have been ample + in the case of the horse. And this might have been expected, as horses + breed much quicker than man, are matched with care, and are highly + valued. I have consulted many works, and the unanimity of the belief by + veterinaries of all nations in the transmission of various morbid + tendencies is surprising. Authors, who have had wide experience, give in + detail many singular cases, and assert that contracted feet, with the + numerous contingent evils, of ring-bones, curbs, splints, spavin, founder + and weakness of the front legs, roaring or broken and thick wind, + melanosis, specific ophthalmia, and blindness (the great French + veterinary Hazard going so far as to say that a blind race could soon be + formed), crib-biting, jibbing, and ill-temper, are all plainly + hereditary. Youatt sums up by saying "there is scarcely a malady to which + the horse is subject which is not hereditary;" and M. Bernard adds that + the doctrine "that there is scarcely a disease which does not run in the + stock, is gaining new advocates every day."<a name="NtA_20" + href="#Nt_20"><sup>[20]</sup></a> So it <!-- Page 11 --><span + class="pagenum"><a name="page11"></a>{11}</span>is in regard to cattle, + with consumption, good and bad teeth, fine skin, &c. &c. But + enough, and more than enough, has been said on disease. Andrew Knight, + from his own experience, asserts that disease is hereditary with plants; + and this assertion is endorsed by Lindley.<a name="NtA_21" + href="#Nt_21"><sup>[21]</sup></a></p> + + <p>Seeing how hereditary evil qualities are, it is fortunate that good + health, vigour, and longevity are equally inherited. It was formerly a + well-known practice, when annuities were purchased to be received during + the lifetime of a nominee, to search out a person belonging to a family + of which many members had lived to extreme old age. As to the inheritance + of vigour and endurance, the English race-horse offers an excellent + instance. Eclipse begot 334, and King Herod 497 winners. A "cock-tail" is + a horse not purely bred, but with only one-eighth or one-sixteenth impure + blood in his veins, yet very few instances have ever occurred of such + horses having won a great race. They are sometimes as fleet for short + distances as thoroughbreds, but as Mr. Robson, the great trainer, + asserts, they are deficient in wind, and cannot keep up the pace. Mr. + Lawrence also remarks, "perhaps no instance has ever occurred of a + three-part-bred horse saving his '<i>distance</i>' in running two miles + with thoroughbred racers." It has been stated by Cecil, that when unknown + horses, whose parents were not celebrated, have unexpectedly won great + races, as in the case of Priam, they can always be proved to be descended + on both sides, through many generations, from first-rate ancestors. On + the Continent, Baron Cameronn challenges, in a German veterinary + periodical, the opponents of the English race-horse, to name one good + horse on the Continent which has not some English race-blood in his + veins.<a name="NtA_22" href="#Nt_22"><sup>[22]</sup></a></p> + + <p>With respect to the transmission of the many slight, but <!-- Page 12 + --><span class="pagenum"><a name="page12"></a>{12}</span>infinitely + diversified characters, by which the domestic races of animals and plants + are distinguished, nothing need be said; for the very existence of + persistent races proclaims the power of inheritance.</p> + + <p>A few special cases, however, deserve some consideration. It might + have been anticipated, that deviations from the law of symmetry would not + have been inherited. But Anderson<a name="NtA_23" + href="#Nt_23"><sup>[23]</sup></a> states that a rabbit produced in a + litter a young animal having only one ear; and from this animal a breed + was formed which steadily produced one-eared rabbits. He also mentions a + bitch, with a single leg deficient, and she produced several puppies with + the same deficiency. From Hofacker's account<a name="NtA_24" + href="#Nt_24"><sup>[24]</sup></a> it appears that a one-horned stag was + seen in 1781 in a forest in Germany, in 1788 two, and afterwards, from + year to year, many were observed with only one horn on the right side of + the head. A cow lost a horn by suppuration,<a name="NtA_25" + href="#Nt_25"><sup>[25]</sup></a> and she produced three calves which had + on the same side of the head, instead of a horn, a small bony lump + attached merely to the skin; but we here approach the doubtful subject of + inherited mutilations. A man who is left-handed, and a shell in which the + spire turns in the wrong direction, are departures from the normal though + a symmetrical condition, and they are well known to be inherited.</p> + +<blockquote class="b1n"> + + <p><i>Polydactylism.</i>—Supernumerary fingers and toes are + eminently liable, as various authors have insisted, to transmission, but + they are noticed here chiefly on account of their occasional regrowth + after amputation. Polydactylism graduates<a name="NtA_26" + href="#Nt_26"><sup>[26]</sup></a> by multifarious steps from a mere + cutaneous appendage, not including any bone, to a double hand. But an + additional digit, supported on a metacarpal bone, and furnished with all + the proper muscles, nerves, and vessels, is sometimes so perfect, that it + escapes detection, unless the fingers are actually counted. Occasionally + there are several supernumerary digits; but usually only one, making the + total number six. This one may represent either a thumb or finger, being + attached to the inner or outer margin of the hand. Generally, through the + law of correlation, both hands and feet are similarly affected. I have + tabulated the cases recorded in various works or privately communicated + <!-- Page 13 --><span class="pagenum"><a name="page13"></a>{13}</span>to + me, of forty-six persons with extra digits on one or both hands and feet; + if in each case all four extremities had been similarly affected, the + table would have shown a total of ninety-two hands and ninety-two feet + each with six digits. As it is, seventy-three hands and seventy-five feet + were thus affected. This proves, in contradiction to the result arrived + at by Dr. Struthers,<a name="NtA_27" href="#Nt_27"><sup>[27]</sup></a> + that the hands are not more frequently affected than the feet.</p> + + <p>The presence of more than five digits is a great anomaly, for this + number is not normally exceeded by any mammal, bird, or existing + reptile.<a name="NtA_28" href="#Nt_28"><sup>[28]</sup></a> Nevertheless, + supernumerary digits are strongly inherited; they have been transmitted + through five generations; and in some cases, after disappearing for one, + two, or even three generations, have reappeared through reversion. These + facts are rendered, as Professor Huxley has observed, more remarkable + from its being known in most cases that the affected person had not + married one similarly affected. In such cases the child of the fifth + generation would have only 1-32nd part of the blood of his first + sedigitated ancestor. Other cases are rendered remarkable by the + affection gathering force, as Dr. Struthers has shown, in each + generation, though in each the affected person had married one not + affected; moreover such additional digits are often amputated soon after + birth, and can seldom have been strengthened by use. Dr. Struthers gives + the following instance: in the first generation an additional digit + appeared on one hand; in the second, on both hands; in the third, three + brothers had both hands, and one of the brothers a foot affected; and in + the fourth generation all four limbs were affected. Yet we must not + over-estimate the force of inheritance. Dr. Struthers asserts that cases + of non-inheritance and of the first appearance of additional digits in + unaffected families are much more frequent than cases of inheritance. + Many other deviations of structure, of a nature almost as anomalous as + supernumerary digits, such as deficient phalanges, thickened joints, + crooked fingers, &c., are in like manner strongly inherited, and are + equally subject to intermission with reversion, though in such cases + there is no reason to suppose that both parents had been similarly + affected.<a name="NtA_29" href="#Nt_29"><sup>[29]</sup></a></p> + +<p><!-- Page 14 --><span class="pagenum"><a name="page14"></a>{14}</span></p> + + <p>Additional digits have been observed in negroes as well as in other + races of man, and in several of the lower animals. Six toes have been + described on the hind feet of the newt (<i>Salamandra cristata</i>), and, + as it is said, of the frog. It deserves notice from what follows, that + the six-toed newt, though adult, had preserved some of its larval + characters; for part of the hyoidal apparatus, which is properly absorbed + during the act of metamorphosis, was retained. In the dog, six toes on + the hinder feet have been transmitted through three generations; and I + have heard of a race of six-toed cats. In several breeds of the fowl the + hinder toe is double, and is generally transmitted truly, as is well + shown when Dorkings are crossed with common four-toed breeds.<a + name="NtA_30" href="#Nt_30"><sup>[30]</sup></a> With animals which have + properly less than five digits, the number is sometimes increased to + five, especially in the front legs, though rarely carried beyond that + number; but this is due to the development of a digit already existing in + a more or less rudimentary state. Thus the dog has properly four toes + behind, but in the larger breeds a fifth toe is commonly, though not + perfectly, developed. Horses, which properly have one toe alone fully + developed with rudiments of the others, have been described with each + foot bearing two or three small separate hoofs: analogous facts have been + noticed with sheep, goats, and pigs.<a name="NtA_31" + href="#Nt_31"><sup>[31]</sup></a></p> + + <p>The most interesting point with respect to supernumerary digits is + their occasional regrowth after amputation. Mr. White<a name="NtA_32" + href="#Nt_32"><sup>[32]</sup></a> describes a child, three years old, + with a thumb double from the first joint. He removed the lesser thumb, + which was furnished with a nail; but to his astonishment it grew again, + and reproduced a nail. The child was then taken to an eminent London + surgeon, and the newly-grown thumb was wholly removed by its + socket-joint, but again it grew and reproduced a nail. Dr. Struthers + mentions a case of partial regrowth of an additional thumb, amputated + when the child was three months old; and the late Dr. Falconer + communicated to me an analogous case which had fallen under his own + observation. A gentleman, who first called my attention to this subject, + has given me the following facts which occurred in his own family. He + himself, two brothers, and a sister were born with an extra digit to each + extremity. His parents were not affected, and there was no tradition in + the family, or in the village in which the family had long resided, of + any member having been thus affected. Whilst a child, both additional + toes, which were attached by bones, were rudely cut off; but the stump of + one grew again, and a second operation was performed in his thirty-third + year.</p> + +<p><!-- Page 15 --><span class="pagenum"><a name="page15"></a>{15}</span></p> + + <p>He has had fourteen children, of whom three have inherited additional + digits; and one of them, when about six weeks old, was operated on by an + eminent surgeon. The additional finger, which was attached by bone to the + outer side of the hand, was removed at the joint; the wound healed, but + immediately the digit began growing; and in about three months' time the + stump was removed for the second time by the root. But it has since grown + again, and is now fully a third of an inch in length, including a bone; + so that it will for the third time have to be operated on.</p> + + <p>Now the normal digits in adult man and other mammals, in birds, and, + as I believe, in true reptiles, have no power of regrowth. The nearest + approach to this power is exhibited by the occasional reappearance in man + of imperfect nails on the stumps of his fingers after amputation.<a + name="NtA_33" href="#Nt_33"><sup>[33]</sup></a> But man in his embryonic + condition has a considerable power of reproduction, for Sir J. Simpson<a + name="NtA_34" href="#Nt_34"><sup>[34]</sup></a> has several times + observed arms which had been cut off in the womb by bands of false + membrane, and which had grown again to a certain extent. In one instance, + the extremity was "divided into three minute nodules, on two of which + small points of nails could be detected;" so that these nodules clearly + represented fingers in process of regrowth. When, however, we descend to + the lower vertebrate classes, which are generally looked at as + representing the higher classes in their embryonic condition, we find + ample powers of regrowth. Spallanzani<a name="NtA_35" + href="#Nt_35"><sup>[35]</sup></a> cut off the legs and tail of a + salamander six times, and Bonnet eight times, successively, and they were + reproduced. An additional digit beyond the proper number was occasionally + formed after Bonnet had cut off or had divided longitudinally the hand or + foot, and in one instance three additional digits were thus formed.<a + name="NtA_36" href="#Nt_36"><sup>[36]</sup></a> These latter cases appear + at first sight quite distinct from the congenital production of + additional digits in the higher animals; but theoretically, as we shall + see in a future chapter, they probably present no real difference. The + larvæ or tadpoles of the tailless Batrachians, but not the adults,<a + name="NtA_37" href="#Nt_37"><sup>[37]</sup></a> are capable of + reproducing lost members.<a name="NtA_38" + href="#Nt_38"><sup>[38]</sup></a> Lastly, as I have been informed by Mr. + J. J. Briggs and Mr. F. Buckland, when portions of the pectoral and tail + fins of various <!-- Page 16 --><span class="pagenum"><a + name="page16"></a>{16}</span>fresh-water fish are cut off, they are + perfectly reproduced in about six weeks' time.</p> + +</blockquote> + + <p>From these several facts we may infer that supernumerary digits in man + retain to a certain extent an embryonic condition, and that they resemble + in this respect the normal digits and limbs in the lower vertebrate + classes. They also resemble the digits of some of the lower animals in + the number exceeding five; for no mammal, bird, existing reptile, or + amphibian (unless the tubercle on the hind feet of the toad and other + tailless Batrachians be viewed as a digit) has more than five; whilst + fishes sometimes have in their pectoral fins as many as twenty metacarpal + and phalangeal bones, which, together with the bony filaments, apparently + represent our digits with their nails. So, again, in certain extinct + reptiles, namely, the Ichthyopterygia, "the digits may be seven, eight, + or nine in number, a significant mark," says Professor Owen, "of piscine + affinity."<a name="NtA_39" href="#Nt_39"><sup>[39]</sup></a></p> + + <p>We encounter much difficulty in attempting to reduce these various + facts to any rule or law. The inconstant number of the additional + digits—their irregular attachment to either the inner or outer + margin of the hand—the gradation which can be traced from a mere + loose rudiment of a single digit to a completely double hand—the + occasional appearance of additional digits in the salamander after a limb + has been amputated—these various facts appear to indicate mere + fluctuating monstrosity; and this perhaps is all that can be safely said. + Nevertheless, as supernumerary digits in the higher animals, from their + power of regrowth and from the number thus acquired exceeding five, + partake of the nature of the digits in the lower vertebrate + animals;—as they occur by no means rarely, and are transmitted with + remarkable strength, though perhaps not more strongly than some other + anomalies;—and as with animals which have fewer than five digits, + when an additional one appears it is generally due to the development of + a visible rudiment;—we are led in all cases to suspect, that, + although no actual rudiment can be detected, yet that a latent tendency + to the formation of an additional digit exists in all mammals, including + man. On this view, as we shall more plainly see in the <!-- Page 17 + --><span class="pagenum"><a name="page17"></a>{17}</span>next chapter + when discussing latent tendencies, we should have to look at the whole + case as one of reversion to an enormously remote, lowly-organised, and + multidigitate progenitor.</p> + +<hr class="short" /> + + <p>I may here allude to a class of facts closely allied to, but somewhat + different from, ordinary cases of inheritance. Sir H. Holland<a + name="NtA_40" href="#Nt_40"><sup>[40]</sup></a> states that brothers and + sisters of the same family are frequently affected, often at about the + same age, by the same peculiar disease, not known to have previously + occurred in the family. He specifies the occurrence of diabetes in three + brothers under ten years old; he also remarks that children of the same + family often exhibit in common infantile diseases the same peculiar + symptoms. My father mentioned to me the case of four brothers who died + between the ages of sixty and seventy, in the same highly peculiar + comatose state. An instance has been already given of supernumerary + digits appearing in four children out of six in a previously unaffected + family. Dr. Devay states<a name="NtA_41" + href="#Nt_41"><sup>[41]</sup></a> that two brothers married two sisters, + their first-cousins, none of the four nor any relation being an albino; + but the seven children produced from this double marriage were all + perfect albinoes. Some of these cases, as Mr. Sedgwick<a name="NtA_42" + href="#Nt_42"><sup>[42]</sup></a> has shown, are probably the result of + reversion to a remote ancestor, of whom no record had been preserved; and + all these cases are so far directly connected with inheritance that no + doubt the children inherited a similar constitution from their parents, + and, from being exposed to nearly similar conditions of life, it is not + surprising that they should be affected in the same manner and at the + same period of life.</p> + +<hr class="short" /> + + <p>Most of the facts hitherto given have served to illustrate the force + of inheritance, but we must now consider cases, grouped as well as the + subject allows into classes, showing how feeble, capricious, or deficient + the power of inheritance sometimes is. When a new peculiarity first + appears, we can never predict whether it will be inherited. If both + parents from their birth present <!-- Page 18 --><span class="pagenum"><a + name="page18"></a>{18}</span>the same peculiarity, the probability is + strong that it will be transmitted to at least some of their offspring. + We have seen that variegation is transmitted much more feebly by seed + from a branch which had become variegated through bud-variation, than + from plants which were variegated as seedlings. With most plants the + power of transmission notoriously depends on some innate capacity in the + individual: thus Vilmorin<a name="NtA_43" + href="#Nt_43"><sup>[43]</sup></a> raised from a peculiarly coloured + balsam some seedlings, which all resembled their parent; but of these + seedlings some failed to transmit the new character, whilst others + transmitted it to all their descendants during several successive + generations. So again with a variety of the rose, two plants alone out of + six were found by Vilmorin to be capable of transmitting the desired + character.</p> + +<blockquote class="b1n"> + + <p>The weeping or pendulous growth of trees is strongly inherited in some + cases, and, without any assignable reason, feebly in other cases. I have + selected this character as an instance of capricious inheritance, because + it is certainly not proper to the parent-species, and because, both sexes + being borne on the same tree, both tend to transmit the same character. + Even supposing that there may have been in some instances crossing with + adjoining trees of the same species, it is not probable that all the + seedlings would have been thus affected. At Moccas Court there is a + famous weeping oak; many of its branches "are 30 feet long, and no + thicker in any part of this length than a common rope:" this tree + transmits its weeping character, in a greater or less degree, to all its + seedlings; some of the young oaks being so flexible that they have to be + supported by props; others not showing the weeping tendency till about + twenty years old.<a name="NtA_44" href="#Nt_44"><sup>[44]</sup></a> Mr. + Rivers fertilized, as he informs me, the flowers of a new Belgian weeping + thorn (<i>Cratægus <span class="correction" title="Original reads `oxycantha', corrected by errata, page viii." + >oxyacantha</span></i>) with pollen from a crimson not-weeping variety, + and three young trees, "now six or seven years old, show a decided + tendency to be pendulous, but as yet are not so much so as the + mother-plant." According to Mr. MacNab,<a name="NtA_45" + href="#Nt_45"><sup>[45]</sup></a> seedlings from a magnificent weeping + birch (<i>Betula alba</i>), in the Botanic Garden at Edinburgh, grew for + the first ten or fifteen years upright, but then all became weepers like + their parent. A peach with pendulous branches, like those of the weeping + willow, has been found capable of propagation by seed.<a name="NtA_46" + href="#Nt_46"><sup>[46]</sup></a> Lastly, a weeping and almost prostrate + yew (<i>Taxus baccata</i>) was found in a hedge in Shropshire; it was a + male, but one branch bore female flowers, and produced berries; these, + <!-- Page 19 --><span class="pagenum"><a + name="page19"></a>{19}</span>being sown, produced seventeen trees, all of + which had exactly the same peculiar habit with the parent-tree.<a + name="NtA_47" href="#Nt_47"><sup>[47]</sup></a></p> + + <p>These facts, it might have been thought, would have been sufficient to + render it probable that a pendulous habit would in all cases be strictly + inherited. But let us look to the other side. Mr. MacNab<a name="NtA_48" + href="#Nt_48"><sup>[48]</sup></a> sowed seeds of the weeping beech + (<i>Fagus sylvanica</i>), but succeeded in raising only common beeches. + Mr. Rivers, at my request, raised a number of seedlings from three + distinct varieties of weeping elm; and at least one of the parent-trees + was so situated that it could not have been crossed by any other elm; but + none of the young trees, now about a foot or two in height, show the + least signs of weeping. Mr. Rivers formerly sowed above twenty thousand + seeds of the weeping ash (<i>Fraxinus excelsior</i>), and not a single + seedling was in the least degree pendulous: in Germany, M. Borchmeyer + raised a thousand seedlings, with the same result. Nevertheless, Mr. + Anderson, of the Chelsea Botanic Garden, by sowing seed from a weeping + ash, which was found before the year 1780, in Cambridgeshire, raised + several pendulous trees.<a name="NtA_49" + href="#Nt_49"><sup>[49]</sup></a> Professor Henslow also informs me that + some seedlings from a female weeping ash in the Botanic Garden at + Cambridge were at first a little pendulous, but afterwards became quite + upright: it is probable that this latter tree, which transmits to a + certain extent its pendulous habit, was derived by a bud from the same + original Cambridgeshire stock; whilst other weeping ashes may have had a + distinct origin. But the crowning case, communicated to me by Mr. Rivers, + which shows how capricious is the inheritance of a pendulous habit, is + that a variety of another species of ash (<i>F. lentiscifolia</i>) which + was formerly pendulous, "now about twenty years old has long lost this + habit, every shoot being remarkably erect; but seedlings formerly raised + from it were perfectly prostrate, the stems not rising more than two + inches above the ground." Thus the weeping variety of the common ash, + which has been extensively propagated by buds during a long period, did + not, with Mr. Rivers, transmit its character to one seedling out of above + twenty thousand; whereas the weeping variety of a second species of ash, + which could not, whilst grown in the same garden, retain its own weeping + character, transmitted to its seedlings the pendulous habit in + excess!</p> + + <p>Many analogous facts could be given, showing how apparently capricious + is the principle of inheritance. All the seedlings from a variety of the + Barberry (<i>B. vulgaris</i>) with red leaves inherited the same + character; only about one-third of the seedlings of the copper Beech + (<i>Fagus sylvatica</i>) had purple leaves. Not one out of a hundred + seedlings of a variety of the <i>Cerasus padus</i>, with yellow fruit, + bore yellow fruit: one-twelfth of the seedlings of the variety of + <i>Cornus mascula</i>, with yellow fruit, came true:<a name="NtA_50" + href="#Nt_50"><sup>[50]</sup></a> and lastly, all the trees raised by my + father from a yellow-berried holly (<i>Ilex aquifolium</i>), <!-- Page 20 + --><span class="pagenum"><a name="page20"></a>{20}</span>found wild, + produced yellow berries. Vilmorin<a name="NtA_51" + href="#Nt_51"><sup>[51]</sup></a> observed in a bed of <i>Saponaria + calabrica</i> an extremely dwarf variety, and raised from it a large + number of seedlings; some of these partially resembled their parent, and + he selected their seed; but the grandchildren were not in the least + dwarfed: on the other hand, he observed a stunted and bushy variety of + <i>Tagetes signata</i> growing in the midst of the common varieties by + which it was probably crossed; for most of the seedlings raised from this + plant were intermediate in character, only two perfectly resembling their + parent; but seed saved from these two plants reproduced the new variety + so truly, that hardly any selection has since been necessary.</p> + + <p>Flowers transmit their colour truly, or most capriciously. Many + annuals come true: thus I purchased German seeds of thirty-four named + sub-varieties of one <i>race</i> of ten-week stocks (<i>Matthiola + annua</i>), and raised a hundred and forty plants, all of which, with the + exception of a single plant, came true. In saying this, however, it must + be understood that I could distinguish only twenty kinds out of the + thirty-four named sub-varieties; nor did the colour of the flower always + correspond with the name affixed to the packet; but I say that they came + true, because in each of the thirty-six short rows every plant was + absolutely alike, with the one single exception. Again, I procured + packets of German seed of twenty-five named varieties of common and + quilled asters, and raised a hundred and twenty-four plants; of these, + all except ten were true in the above limited sense; and I considered + even a wrong shade of colour as false.</p> + + <p>It is a singular circumstance that white varieties generally transmit + their colour much more truly than any other variety. This fact probably + stands in close relation with one observed by Verlot,<a name="NtA_52" + href="#Nt_52"><sup>[52]</sup></a> namely, that flowers which are normally + white rarely vary into any other colour. I have found that the white + varieties of <i>Delphinium consolida</i> and of the Stock are the truest. + It is, indeed, sufficient to look through a nurseryman's seed-list, to + see the large number of white varieties which can be propagated by seed. + The several coloured varieties of the sweet-pea (<i>Lathyrus + odoratus</i>) are very true; but I hear from Mr. Masters, of Canterbury, + who has particularly attended to this plant, that the white variety is + the truest. The hyacinth, when propagated by seed, is extremely + inconstant in colour, but "white hyacinths almost always give by seed + white-flowered plants;"<a name="NtA_53" href="#Nt_53"><sup>[53]</sup></a> + and Mr. Masters informs me that the yellow varieties also reproduce their + colour, but of different shades. On the other hand, pink and blue + varieties, the latter being the natural colour, are not nearly so true: + hence, as Mr. Masters has remarked to me, "we see that a garden variety + may acquire a more permanent habit than a natural species;" but it should + have been added, that this occurs under cultivation, and therefore under + changed conditions.</p> + + <p>With many flowers, especially perennials, nothing can be more + fluctuating than the colour of the seedlings, as is notoriously the case + with verbenas, carnations, dahlias, cinerarias, and others.<a + name="NtA_54" href="#Nt_54"><sup>[54]</sup></a> I sowed seed of twelve + <!-- Page 21 --><span class="pagenum"><a + name="page21"></a>{21}</span>named varieties of Snapdragon + (<i>Antirrhinum majus</i>), and utter confusion was the result. In most + cases the extremely fluctuating colour of seedling plants is probably in + chief part due to crosses between differently-coloured varieties during + previous generations. It is almost certain that this is the case with the + polyanthus and coloured primrose (<i>Primula veris</i> and + <i>vulgaris</i>), from their reciprocally dimorphic structure;<a + name="NtA_55" href="#Nt_55"><sup>[55]</sup></a> and these are plants + which florists speak of as never come true by seed: but if care be taken + to prevent crossing, neither species is by any means very inconstant in + colour; thus I raised twenty-three plants from a purple primrose, + fertilised by Mr. J. Scott with its own pollen, and eighteen came up + purple of different shades, and only five reverted to the ordinary yellow + colour: again, I raised twenty plants from a bright-red cowslip, + similarly treated by Mr. Scott, and every one perfectly resembled its + parent in colour, as likewise did, with the exception of a single plant, + 73 grandchildren. Even with the most variable flowers, it is probable + that each delicate shade of colour might be permanently fixed so as to be + transmitted by seed, by cultivation in the same soil, by long-continued + selection, and especially by the prevention of crosses. I infer this from + certain annual larkspurs (<i>Delphinium consolida</i> and <i>ajacis</i>), + of which common seedlings present a greater diversity of colour than any + other plant known to me; yet on procuring seed of five named German + varieties of <i>D. consolida</i>, only nine plants out of ninety-four + were false; and the seedlings of six varieties of <i>D. ajacis</i> were + true in the same manner and degree as with the stocks above described. A + distinguished botanist maintains that the annual species of Delphinium + are always self-fertilised; therefore I may mention that thirty-two + flowers on a branch of <i>D. consolida</i>, enclosed in a net, yielded + twenty-seven capsules, with an average of 17.2 seed in each; whilst five + flowers, under the same net, which were artificially fertilised, in the + same manner as must be effected by bees during their incessant visits, + yielded five capsules with an average of 35.2 fine seed; and this shows + that the agency of insects is necessary for the full fertility of this + plant. Analogous facts could be given with respect to the crossing of + many other flowers, such as carnations, &c., of which the varieties + fluctuate much in colour.</p> + + <p>As with flowers, so with our domesticated animals, no character is + more variable than colour, and probably in no animal more so than with + the horse. Yet with a little care in breeding, it appears that races of + any colour might soon be formed. Hofacker gives the result of matching + two hundred and sixteen mares of four different colours with + like-coloured stallions, without regard to the colour of their ancestors; + and of the two hundred and sixteen colts born, eleven alone failed to + inherit the colour of their parents: Autenrieth and Ammon assert that, + after two generations, colts of a uniform colour are produced with + certainty.<a name="NtA_56" href="#Nt_56"><sup>[56]</sup></a></p> + +</blockquote> + + <p>In a few rare cases peculiarities fail to be inherited, apparently + from the force of inheritance being too strong. I have been assured by + breeders of the canary-bird that to get a good <!-- Page 22 --><span + class="pagenum"><a name="page22"></a>{22}</span>jonquil-coloured bird it + does not answer to pair two jonquils, as the colour then comes out too + strong, or is even brown. So again, if two crested canaries are paired, + the young birds rarely inherit this character:<a name="NtA_57" + href="#Nt_57"><sup>[57]</sup></a> for in crested birds a narrow space of + bare skin is left on the back of the head, where the feathers are + up-turned to form the crest, and, when both parents are thus + characterised, the bareness becomes excessive, and the crest itself fails + to be developed. Mr. Hewitt, speaking of Laced Sebright Bantams, says<a + name="NtA_58" href="#Nt_58"><sup>[58]</sup></a> that, "why this should be + so, I know not, but I am confident that those that are best laced + frequently produce offspring very far from perfect in their markings, + whilst those exhibited by myself, which have so often proved successful, + were bred from the union of heavily-laced birds with those that were + scarcely sufficiently laced."</p> + + <p>It is a singular fact that, although several deaf-mutes often occur in + the same family, and though their cousins and other relations are often + in the same condition, yet their parents are very rarely deaf-mutes. To + give a single instance: not one scholar out of 148, who were at the same + time in the London Institution, was the child of parents similarly + afflicted. So again, when a male or a female deaf-mute marries a sound + person, their children are most rarely affected: in Ireland out of 203 + children thus produced one alone was mute. Even when both parents have + been deaf-mutes, as in the case of forty-one marriages in the United + States and of six in Ireland, only two deaf and dumb children were + produced. Mr. Sedgwick,<a name="NtA_59" href="#Nt_59"><sup>[59]</sup></a> + in commenting on this remarkable and fortunate failure in the power of + transmission in the direct line, remarks that it may possibly be owing to + "excess having reversed the action of some natural law in development." + But it is safer in the present state of our knowledge to look at the + whole case as simply unintelligible.</p> + +<hr class="short" /> + + <p>With respect to the inheritance of structures mutilated by injuries or + altered by disease it is difficult to come to any <!-- Page 23 --><span + class="pagenum"><a name="page23"></a>{23}</span>definite conclusion. In + some cases mutilations have been practised for a vast number of + generations without any inherited result. Godron has remarked<a + name="NtA_60" href="#Nt_60"><sup>[60]</sup></a> that different races of + man have from time immemorial knocked out their upper incisors, cut off + joints of their fingers, made holes of immense size through the lobes of + their ears or through their nostrils, made deep gashes in various parts + of their bodies, and there is no reason whatever to suppose that these + mutilations have ever been inherited. Adhesions due to inflammation and + pits from the small-pox (and formerly many consecutive generations must + have been thus pitted) are not inherited. With respect to Jews, I have + been assured by three medical men of the Jewish faith that circumcision, + which has been practised for so many ages, has produced no inherited + effect; Blumenbach, on the other hand, asserts<a name="NtA_61" + href="#Nt_61"><sup>[61]</sup></a> that in Germany Jews are often born in + a condition rendering circumcision difficult, so that a name is here + applied to them signifying "born circumcised." The oak and other trees + must have borne galls from primeval times, yet they do not produce + inherited excrescences; many other such facts could be adduced.</p> + + <p>On the other hand, various cases have been recorded of cats, dogs, and + horses, which have had their tails, legs, &c., amputated or injured, + producing offspring with the same parts ill-formed; but as it is not at + all rare for similar malformations to appear spontaneously, all such + cases may be due to mere coincidence. Nevertheless, Dr. Prosper Lucas has + given, on good authorities, such a long list of inherited injuries, that + it is difficult not to believe in them. Thus, a cow that had lost a horn + from an accident with consequent suppuration, produced three calves which + were hornless on the same side of the head. With the horse, there seems + hardly a doubt that bony exostoses on the legs, caused by too much + travelling on hard roads, are inherited. Blumenbach records the case of a + man who had his little finger on the right hand almost cut off, and which + in consequence grew crooked, and his sons had the same finger on the same + hand similarly crooked. A soldier, fifteen years before his marriage, + lost his left eye from purulent ophthalmia, and his <!-- Page 24 --><span + class="pagenum"><a name="page24"></a>{24}</span>two sons were + microphthalmic on the same side.<a name="NtA_62" + href="#Nt_62"><sup>[62]</sup></a> In all such cases, if truthfully + reported, in which the parent has had an organ injured on one side, and + more than one child has been born with the same organ affected on the + same side, the chances against mere coincidence are enormous. But perhaps + the most remarkable and trustworthy fact is that given by Dr. + Brown-Séquard,<a name="NtA_63" href="#Nt_63"><sup>[63]</sup></a> namely, + that many young guinea-pigs inherited an epileptic tendency from parents + which had been subjected to a particular operation, inducing in the + course of a few weeks a convulsive disease like epilepsy: and it should + be especially noted that this eminent physiologist bred a large number of + guinea-pigs from animals which had not been operated on, and not one of + these manifested the epileptic tendency. On the whole, we can hardly + avoid admitting, that injuries and mutilations, especially when followed + by disease, or perhaps exclusively when thus followed, are occasionally + inherited.</p> + + <p>Although many congenital monstrosities are inherited, of which + examples have already been given, and to which may be added the lately + recorded case of the transmission during a century of hare-lip with a + cleft-palate in the writer's own family,<a name="NtA_64" + href="#Nt_64"><sup>[64]</sup></a> yet other malformations are rarely or + never inherited. Of these later cases, many are probably due to injuries + in the womb or egg, and would come under the head of non-inherited + injuries or mutilations. With plants, a long catalogue of inherited + monstrosities of the most serious and diversified nature could easily be + given; and with plants, there is no reason to suppose that monstrosities + are caused by direct injuries to the seed or embryo.</p> + +<p class="cenhead"><i>Causes of Non-inheritance.</i></p> + + <p>A large number of cases of non-inheritance are intelligible on the + principle, that a strong tendency to inheritance does exist, but <!-- + Page 25 --><span class="pagenum"><a name="page25"></a>{25}</span>that it + is overborne by hostile or unfavourable conditions of life. No one would + expect that our improved pigs, if forced during several generations to + travel about and root in the ground for their own subsistence, would + transmit, as truly as they now do, their tendency to fatten, and their + short muzzles and legs. Dray-horses assuredly would not long transmit + their great size and massive limbs, if compelled to live on a cold, damp + mountainous region; we have indeed evidence of such deterioration in the + horses which have run wild on the Falkland Islands. European dogs in + India often fail to transmit their true character. Our sheep in tropical + countries lose their wool in a few generations. There seems also to be a + close relation between certain peculiar pastures and the inheritance of + an enlarged tail in fat-tailed sheep, which form one of the most ancient + breeds in the world. With plants, we have seen that the American + varieties of maize lose their proper character in the course of two or + three generations, when cultivated in Europe. Our cabbages, which here + come so true by seed, cannot form heads in hot countries. Under changed + circumstances, periodical habits of life soon fail to be transmitted, as + the period of maturity in summer and winter wheat, barley, and vetches. + So it is with animals; for instance, a person whose statement I can + trust, procured eggs of Aylesbury ducks from that town, where they are + kept in houses and are reared as early as possible for the London market; + the ducks bred from these eggs in a distant part of England, hatched + their first brood on January 24th, whilst common ducks, kept in the same + yard and treated in the same manner, did not hatch till the end of March; + and this shows that the period of hatching was inherited. But the + grandchildren of these Aylesbury ducks completely lost their early habit + of incubation, and hatched their eggs at the same time with the common + ducks of the same place.</p> + + <p>Many cases of non-inheritance apparently result from the conditions of + life continually inducing fresh variability. We have seen that when the + seeds of pears, plums, apples, &c., are sown, the seedlings generally + inherit some degree of family likeness from the parent-variety. Mingled + with these seedlings, a few, and sometimes many, worthless, wild-looking + plants commonly appear; and their appearance may be attributed to the + principle of reversion. But scarcely a single seedling will be found <!-- + Page 26 --><span class="pagenum"><a + name="page26"></a>{26}</span>perfectly to resemble the parent-form; and + this, I believe, may be accounted for by constantly recurring variability + induced by the conditions of life. I believe in this, because it has been + observed that certain fruit-trees truly propagate their kind whilst + growing on their own roots, but when grafted on other stocks, and by this + process their natural state is manifestly affected, they produce + seedlings which vary greatly, departing from the parental type in many + characters.<a name="NtA_65" href="#Nt_65"><sup>[65]</sup></a> Metzger, as + stated in the ninth chapter, found that certain kinds of wheat brought + from Spain and cultivated in Germany, failed during many years to + reproduce themselves truly; but that at last, when accustomed to their + new conditions, they ceased to be variable,—that is, they became + amenable to the power of inheritance. Nearly all the plants which cannot + be propagated with any approach to certainty by seed, are kinds which + have long been propagated by buds, cuttings, offsets, tubers, &c., + and have in consequence been frequently exposed during their individual + lives to widely diversified conditions of life. Plants thus propagated + become so variable, that they are subject, as we have seen in the last + chapter, even to bud-variation. Our domesticated animals, on the other + hand, are not exposed during their individual lives to such extremely + diversified conditions, and are not liable to such extreme variability; + therefore they do not lose the power of transmitting most of their + characteristic features. In the foregoing remarks on non-inheritance, + crossed breeds are of course excluded, as their diversity mainly depends + on the unequal development of characters derived from either parent, + modified by the principles of reversion and prepotency.</p> + +<p class="cenhead"><i>Conclusion.</i></p> + + <p>It has, I think, been shown in the early part of this chapter how + strongly new characters of the most diversified nature, whether normal or + abnormal, injurious or beneficial, whether affecting organs of the + highest or most trifling importance, are inherited. Contrary to the + common opinion, it is often sufficient for the inheritance of some + peculiar character, that one parent alone should possess it, as in most + cases in which the rarer <!-- Page 27 --><span class="pagenum"><a + name="page27"></a>{27}</span>anomalies have been transmitted. But the + power of transmission is extremely variable: in a number of individuals + descended from the same parents, and treated in the same manner, some + display this power in a perfect manner, and in some it is quite + deficient; and for this difference no reason can be assigned. In some + cases the effects of injuries or mutilations apparently are inherited; + and we shall see in a future chapter that the effects of the + long-continued use and disuse of parts are certainly inherited. Even + those characters which are considered the most fluctuating, such as + colour, are with rare exceptions transmitted much more forcibly than is + generally supposed. The wonder, indeed, in all cases is not that any + character should be transmitted, but that the power of inheritance should + ever fail. The checks to inheritance, as far as we know them, are, + firstly, circumstances hostile to the particular character in question; + secondly, conditions of life incessantly inducing fresh variability; and + lastly, the crossing of distinct varieties during some previous + generation, together with reversion or atavism—that is, the + tendency in the child to resemble its grand-parents or more remote + ancestors instead of its immediate parents. This latter subject will be + fully discussed in the following chapter.</p> + +<hr class="full" /> + +<p><!-- Page 28 --><span class="pagenum"><a name="page28"></a>{28}</span></p> + +<h3>CHAPTER XIII.</h3> + +<p class="cenhead">INHERITANCE <i>continued</i>—REVERSION OR ATAVISM.</p> + +<blockquote class="b1n"> + + <p><span class="scac">DIFFERENT FORMS OF REVERSION</span>—<span + class="scac">IN PURE OR UNCROSSED BREEDS, AS IN PIGEONS, FOWLS, HORNLESS + CATTLE AND SHEEP, IN CULTIVATED PLANTS</span>—<span + class="scac">REVERSION IN FERAL ANIMALS AND PLANTS</span>—<span + class="scac">REVERSION IN CROSSED VARIETIES AND + SPECIES</span>—<span class="scac">REVERSION THROUGH + BUD-PROPAGATION, AND BY SEGMENTS IN THE SAME FLOWER OR + FRUIT</span>—<span class="scac">IN DIFFERENT PARTS OF THE BODY IN + THE SAME ANIMAL</span>—<span class="scac">THE ACT OF CROSSING A + DIRECT CAUSE OF REVERSION, VARIOUS CASES OF, WITH + INSTINCTS</span>—<span class="scac">OTHER PROXIMATE CAUSES OF + REVERSION</span>—<span class="scac">LATENT + CHARACTERS</span>—<span class="scac">SECONDARY SEXUAL + CHARACTERS</span>—<span class="scac">UNEQUAL DEVELOPMENT OF THE TWO + SIDES OF THE BODY</span>—<span class="scac">APPEARANCE WITH + ADVANCING AGE OF CHARACTERS DERIVED FROM A CROSS</span>—<span + class="scac">THE GERM WITH ALL ITS LATENT CHARACTERS A WONDERFUL + OBJECT</span>—<span class="scac">MONSTROSITIES</span>—<span + class="scac">PELORIC FLOWERS DUE IN SOME CASES TO REVERSION.</span></p> + +</blockquote> + + <p>The great principle of inheritance to be discussed in this chapter has + been recognised by agriculturists and authors of various nations, as + shown by the scientific term <i>Atavism</i>, derived from atavus, an + ancestor; by the English terms of <i>Reversion</i>, or <i>Throwing + back</i>; by the French <i>Pas-en-arrière</i>; and by the German + <i>Rück-schlag</i>, or <i>Rück-schritt</i>. When the child resembles + either grandparent more closely than its immediate parents, our attention + is not much arrested, though in truth the fact is highly remarkable; but + when the child resembles some remote ancestor, or some distant member in + a collateral line,—and we must attribute the latter case to the + descent of all the members from a common progenitor,—we feel a just + degree of astonishment. When one parent alone displays some + newly-acquired and generally inheritable character, and the offspring do + not inherit it, the cause may lie in the other parent having the power of + prepotent transmission. But when both parents are similarly + characterised, and the child does not, whatever the cause may be, inherit + the character in question, but resembles its grandparents, we have one of + the simplest cases of reversion. We continually see another and even more + simple case of atavism, though not generally included under this head, + namely, when <!-- Page 29 --><span class="pagenum"><a + name="page29"></a>{29}</span>the son more closely resembles his maternal + than his paternal grandsire in some male attribute, as in any peculiarity + in the beard of man, the horns of the bull, the hackles or comb of the + cock, or, as in certain diseases necessarily confined to the male sex; + for the mother cannot possess or exhibit such male attributes, yet the + child has inherited them, through her blood, from his maternal + grandsire.</p> + + <p>The cases of reversion may be divided into two main classes, which, + however, in some instances, blend into each other; namely, first, those + occurring in a variety or race which has not been crossed, but has lost + by variation some character that it formerly possessed, and which + afterwards reappears. The second class includes all cases in which a + distinguishable individual, sub-variety, race, or species, has at some + former period been crossed with a distinct form, and a character derived + from this cross, after having disappeared during one or several + generations, suddenly reappears. A third class, differing only in the + manner of reproduction, might be formed to include all cases of reversion + effected by means of buds, and therefore independent of true or seminal + generation. Perhaps even a fourth class might be instituted, to include + reversions by segments in the same individual flower or fruit, and in + different parts of the body in the same individual animal as it grows + old. But the two first main classes will be sufficient for our + purpose.</p> + +<hr class="short" /> + + <p><i>Reversion to lost Characters by pure or uncrossed + forms.</i>—Striking instances of this first class of cases were + given in the sixth chapter, namely, of the occasional reappearance, in + variously-coloured pure breeds of the pigeon, of blue birds with all the + marks which characterise the wild <i>Columba livia</i>. Similar cases + were given in the case of the fowl. With the common ass, as we now know + that the legs of the wild progenitor are striped, we may feel assured + that the occasional appearance of such stripes in the domestic animal is + a case of simple reversion. But I shall be compelled to refer again to + these cases, and therefore will here pass them over.</p> + + <p>The aboriginal species from which our domesticated cattle and sheep + are descended, no doubt possessed horns; but several hornless breeds are + now well established. Yet in these—for instance, <!-- Page 30 + --><span class="pagenum"><a name="page30"></a>{30}</span>in Southdown + sheep—"it is not unusual to find among the male lambs some with + small horns." The horns, which thus occasionally reappear in other polled + breeds, either "grow to the full size, or are curiously attached to the + skin alone and hang loosely down, or drop off."<a name="NtA_66" + href="#Nt_66"><sup>[66]</sup></a> The Galloways and Suffolk cattle have + been hornless for the last 100 or 150 years, but a horned calf, with the + horn often loosely attached, is occasionally born.<a name="NtA_67" + href="#Nt_67"><sup>[67]</sup></a></p> + + <p>There is reason to believe that sheep in their early domesticated + condition were "brown or dingy black;" but even in the time of David + certain flocks were spoken of as white as snow. During the classical + period the sheep of Spain are described by several ancient authors as + being black, red, or tawny.<a name="NtA_68" + href="#Nt_68"><sup>[68]</sup></a> At the present day, notwithstanding the + great care which is taken to prevent it, particoloured lambs and some + entirely black are occasionally dropped by our most highly improved and + valued breeds, such as the Southdowns. Since the time of the famous + Bakewell, during the last century, the Leicester sheep have been bred + with the most scrupulous care; yet occasionally grey-faced, or + black-spotted, or wholly black lambs appear.<a name="NtA_69" + href="#Nt_69"><sup>[69]</sup></a> This occurs still more frequently with + the less improved breeds, such as the Norfolks.<a name="NtA_70" + href="#Nt_70"><sup>[70]</sup></a> As bearing on this tendency in sheep to + revert to dark colours, I may state (though in doing so I trench on the + reversion of crossed breeds, and likewise on the subject of prepotency) + that the Rev. W. D. Fox was informed that seven white Southdown ewes were + put to a so-called Spanish ram, which had two small black spots on his + sides, and they produced thirteen lambs, all perfectly black. Mr. Fox + believes that this ram belonged to a breed which he has himself kept, and + which is always spotted with black and white; and he finds that Leicester + sheep crossed by rams of this breed always produce black lambs: he has + gone on recrossing these crossed sheep with pure white Leicesters during + three successive <!-- Page 31 --><span class="pagenum"><a + name="page31"></a>{31}</span>generations, but always with the same + result. Mr. Fox was also told by the friend from whom the spotted breed + was procured, that he likewise had gone on for six or seven generations + crossing with white sheep, but still black lambs were invariably + produced.</p> + + <p>Similar facts could be given with respect to tailless breeds of + various animals. For instance, Mr. Hewitt<a name="NtA_71" + href="#Nt_71"><sup>[71]</sup></a> states that chickens bred from some + Rumpless fowls, which were reckoned so good that they won a prize at an + exhibition, "in a considerable number of instances were furnished with + fully developed tail-feathers." On inquiry, the original breeder of these + fowls stated that, from the time when he had first kept them, they had + often produced fowls furnished with tails; but that these latter would + again reproduce rumpless chickens.</p> + + <p>Analogous cases of reversion occur in the vegetable kingdom; thus + "from seeds gathered from the finest cultivated varieties of Heartsease + (<i>Viola tricolor</i>), plants perfectly wild both in their foliage and + their flowers are frequently produced;"<a name="NtA_72" + href="#Nt_72"><sup>[72]</sup></a> but the reversion in this instance is + not to a very ancient period, for the best existing varieties of the + heartsease are of comparatively modern origin. With most of our + cultivated vegetables there is some tendency to reversion to what is + known to be, or may be presumed to be, their aboriginal state; and this + would be more evident if gardeners did not generally look over their beds + of seedlings, and pull up the false plants or "rogues" as they are + called. It has already been remarked, that some few seedling apples and + pears generally resemble, but apparently are not identical with, the wild + trees from which they are descended. In our turnip<a name="NtA_73" + href="#Nt_73"><sup>[73]</sup></a> and carrot-beds a few plants often + "break"—that is, flower too soon; and their roots are generally + found to be hard and stringy, as in the parent-species. By the aid of a + little selection, carried on during a few generations, most of our + cultivated plants could probably be brought back, without any great + change in their conditions of life, to a wild or nearly wild condition: + Mr. Buckman has effected this with the parsnip;<a name="NtA_74" + href="#Nt_74"><sup>[74]</sup></a> <!-- Page 32 --><span + class="pagenum"><a name="page32"></a>{32}</span>and Mr. Hewett C. Watson, + as he informs me, selected, during three generations, "the most diverging + plants of Scotch kail, perhaps one of the least modified varieties of the + cabbage; and in the third generation some of the plants came very close + to the forms now established in England about old castle-walls, and + called indigenous."</p> + +<hr class="short" /> + + <p><i>Reversion in Animals and Plants which have run wild.</i>—In + the cases hitherto considered, the reverting animals and plants have not + been exposed to any great or abrupt change in their conditions of life + which could have induced this tendency; but it is very different with + animals and plants which have become feral or run wild. It has been + repeatedly asserted in the most positive manner by various authors, that + feral animals and plants invariably return to their primitive specific + type. It is curious on what little evidence this belief rests. Many of + our domesticated animals could not subsist in a wild state; thus, the + more highly improved breeds of the pigeon will not "field" or search for + their own food. Sheep have never become feral, and would be destroyed by + almost every beast of prey. In several cases we do not know the + aboriginal parent-species, and cannot possibly tell whether or not there + has been any close degree of reversion. It is not known in any instance + what variety was first turned out; several varieties have probably in + some cases run wild, and their crossing alone would tend to obliterate + their proper character. Our domesticated animals and plants, when they + run wild, must always be exposed to new conditions of life, for, as Mr. + Wallace<a name="NtA_75" href="#Nt_75"><sup>[75]</sup></a> has well + remarked, they have to obtain their own food, and are exposed to + competition with the native productions. Under these circumstances, if + our domesticated animals did not undergo change of some kind, the result + would be quite opposed to the conclusions arrived at in this work. + Nevertheless, I do not doubt that the simple fact of animals and plants + becoming feral, does cause some tendency to reversion to the primitive + state; though this tendency has been much exaggerated by some + authors.</p> + +<p><!-- Page 33 --><span class="pagenum"><a name="page33"></a>{33}</span></p> + +<blockquote class="b1n"> + + <p>I will briefly run through the recorded cases. With neither horses nor + cattle is the primitive stock known; and it has been shown in former + chapters that they have assumed different colours in different countries. + Thus the horses which have run wild in South America are generally + brownish-bay, and in the East dun-coloured; their heads have become + larger and coarser, and this may be due to reversion. No careful + description has been given of the feral goat. Dogs which have run wild in + various countries have hardly anywhere assumed a uniform character; but + they are probably descended from several domestic races, and aboriginally + from several distinct species. Feral cats, both in Europe and La Plata, + are regularly striped; in some cases they have grown to an unusually + large size, but do not differ from the domestic animal in any other + character. When variously-coloured tame rabbits are turned out in Europe, + they generally reacquire the colouring of the wild animal; there can be + no doubt that this does really occur, but we should remember that + oddly-coloured and conspicuous animals would suffer much from beasts of + prey and from being easily shot; this at least was the opinion of a + gentleman who tried to stock his woods with a nearly white variety; and + when thus destroyed, they would in truth be supplanted by, instead of + being transformed into, the common rabbit. We have seen that the feral + rabbits of Jamaica, and especially of Porto Santo, have assumed new + colours and other new characters. The best known case of reversion, and + that on which the widely-spread belief in its universality apparently + rests, is that of pigs. These animals have run wild in the West Indies, + South America, and the Falkland Islands, and have everywhere acquired the + dark colour, the thick bristles, and great tusks of the wild boar; and + the young have reacquired longitudinal stripes. But even in the case of + the pig, Roulin describes the half-wild animals in different parts of + South America as differing in several respects. In Louisiana the pig<a + name="NtA_76" href="#Nt_76"><sup>[76]</sup></a> has run wild, and is said + to differ a little in form, and much in colour, from the domestic animal, + yet does not closely resemble the wild boar of Europe. With pigeons and + fowls,<a name="NtA_77" href="#Nt_77"><sup>[77]</sup></a> it is not known + what variety was first turned out, nor what character the feral birds + have assumed. The guinea-fowl in the West Indies, when feral, seems to + vary more than in the domesticated state.</p> + + <p>With respect to plants run wild, Dr. Hooker<a name="NtA_78" + href="#Nt_78"><sup>[78]</sup></a> has strongly insisted on what slight + evidence the common belief in their power of reversion rests. Godron<a + name="NtA_79" href="#Nt_79"><sup>[79]</sup></a> describes wild turnips, + carrots, and celery; but these plants in their cultivated state hardly + differ from their wild prototypes, except in the <!-- Page 34 --><span + class="pagenum"><a name="page34"></a>{34}</span>succulency and + enlargement of certain parts,—characters which would be surely lost + by plants growing in a poor soil and struggling with other plants. No + cultivated plant has run wild on so enormous a scale as the cardoon + (<i>Cynara cardunculus</i>) in La Plata. Every botanist who has seen it + growing there, in vast beds, as high as a horse's back, has been struck + with its peculiar appearance; but whether it differs in any important + point from the cultivated Spanish form, which is said not to be prickly + like its American descendant, or whether it differs from he wild + Mediterranean species, which is said not to be social, I do not know.</p> + +</blockquote> + +<hr class="short" /> + + <p><i>Reversion to Characters derived from a Cross, in the case of + Sub-varieties, Races, and Species.</i>—When an individual having + some recognizable peculiarity unites with another of the same + sub-variety, not having the peculiarity in question, it often reappears + in the descendants after an interval of several generations. Every one + must have noticed, or heard from old people of children closely + resembling in appearance or mental disposition, or in so small and + complex a character as expression, one of their grandparents, or some + more distant collateral relation. Very many anomalies of structure and + diseases,<a name="NtA_80" href="#Nt_80"><sup>[80]</sup></a> of which + instances have been given in the last chapter, have come into a family + from one parent, and have reappeared in the progeny after passing over + two or three generations. The following case has been communicated to me + on good authority, and may, I believe, be fully trusted: a pointer-bitch + produced seven puppies; four were marked with blue and white, which is so + unusual a colour with pointers that she was thought to have played false + with one of the greyhounds, and the whole litter was condemned; but the + gamekeeper was permitted to save one as a curiosity. Two years afterwards + a friend of the owner saw the young dog, and declared that he was the + image of his old pointer-bitch Sappho, the only blue and white pointer of + pure descent which he had ever seen. This led to close inquiry, and it + was proved that he was the great-great-grandson of Sappho; so that, + according to the common expression, he had only 1-16th of her blood in + his veins. Here it can hardly be doubted that a character derived from a + cross with an individual of the same variety reappeared after passing + over three generations.</p> + +<p><!-- Page 35 --><span class="pagenum"><a name="page35"></a>{35}</span></p> + + <p>When two distinct races are crossed, it is notorious that the tendency + in the offspring to revert to one or both parent-forms is strong, and + endures for many generations. I have myself seen the clearest evidence of + this in crossed pigeons and with various plants. Mr. Sidney<a + name="NtA_81" href="#Nt_81"><sup>[81]</sup></a> states that, in a litter + of Essex pigs, two young ones appeared which were the image of the + Berkshire boar that had been used twenty-eight years before in giving + size and constitution to the breed. I observed in the farmyard at Betley + Hall some fowls showing a strong likeness to the Malay breed, and was + told by Mr. Tollet that he had forty years before crossed his birds with + Malays; and that, though he had at first attempted to get rid of this + strain, he had subsequently given up the attempt in despair, as the Malay + character would reappear.</p> + + <p>This strong tendency in crossed breeds to revert has given rise to + endless discussions in how many generations after a single cross, either + with a distinct breed or merely with an inferior animal, the breed may be + considered as pure, and free from all danger of reversion. No one + supposes that less than three generations suffices, and most breeders + think that six, seven, or eight are necessary, and some go to still + greater lengths.<a name="NtA_82" href="#Nt_82"><sup>[82]</sup></a> But + neither in the case of a breed which has been contaminated by a single + cross, nor when, in the attempt to form an intermediate breed, half-bred + animals have been matched together during many generations, can any rule + be laid down how soon the tendency to reversion will be obliterated. It + depends on the difference in the strength or prepotency of transmission + in the two parent-forms, on their actual amount of difference, and on the + nature of the conditions of life to which the crossed offspring are + exposed. But we must be careful not to confound these cases of reversion + to characters gained from a cross, with those given under the first + class, in which characters originally common to <i>both</i> parents, but + lost at some former period, reappear; for such characters may recur after + an almost indefinite number of generations.</p> + +<p><!-- Page 36 --><span class="pagenum"><a name="page36"></a>{36}</span></p> + + <p>The law of reversion is equally powerful with hybrids, when they are + sufficiently fertile to breed together, or when they are repeatedly + crossed with either pure parent-form, as with mongrels. It is not + necessary to give instances, for in the case of plants almost every one + who has worked on this subject from the time of Kölreuter to the present + day has insisted on this tendency. Gärtner has recorded some good + instances; but no one has given more striking cases than Naudin.<a + name="NtA_83" href="#Nt_83"><sup>[83]</sup></a> The tendency differs in + degree or strength in different groups, and partly depends, as we shall + presently see, on the fact of the parent-plants having been long + cultivated. Although the tendency to reversion is extremely general with + nearly all mongrels and hybrids, it cannot be considered as invariably + characteristic of them; there is, also, reason to believe that it may be + mastered by long-continued selection; but these subjects will more + properly be discussed in a future chapter on Crossing. From what we see + of the power and scope of reversion, both in pure races and when + varieties or species are crossed, we may infer that characters of almost + every kind are capable of reappearance after having been lost for a great + length of time. But it does not follow from this that in each particular + case certain characters will reappear: for instance, this will not occur + when a race is crossed with another endowed with prepotency of + transmission. In some few cases the power of reversion wholly fails, + without our being able to assign any cause for the failure: thus it has + been stated that in a French family in which 85 out of above 600 members, + during six generations, had been subject to night-blindness, "there has + not been a single example of this affection in the children of parents + who were themselves free from it."<a name="NtA_84" + href="#Nt_84"><sup>[84]</sup></a></p> + +<hr class="short" /> + + <p><i>Reversion through Bud-propagation—Partial Reversion, by + segments in the same flower or fruit, or in different parts of the <!-- + Page 37 --><span class="pagenum"><a name="page37"></a>{37}</span>body in + the same individual animal.</i>—In the eleventh chapter, many cases + of reversion by buds, independently of seminal generation, were + given—as when a leaf-bud on a variegated, curled, or laciniated + variety suddenly reassumes its proper character; or as when a + Provence-rose appears on a moss-rose, or a peach on a nectarine-tree. In + some of these cases only half the flower or fruit, or a smaller segment, + or mere stripes, reassumed their former character; and here we have with + buds reversion by segments. Vilmorin<a name="NtA_85" + href="#Nt_85"><sup>[85]</sup></a> has also recorded several cases with + plants derived from seed, of flowers reverting by stripes or blotches to + their primitive colours: he states that in all such cases a white or + pale-coloured variety must first be formed, and, when this is propagated + for a length of time by seed, striped seedlings occasionally make their + appearance; and these can afterwards by care be multiplied by seed.</p> + + <p>The stripes and segments just referred to are not due, as far as is + known, to reversion to characters derived from a cross, but to characters + lost by variation. These cases, however, as Naudin<a name="NtA_86" + href="#Nt_86"><sup>[86]</sup></a> insists in his discussion on + disjunction of character, are closely analogous with those given in the + eleventh chapter, in which crossed plants are known to have produced + half-and-half or striped flowers and fruit, or distinct kinds of flowers + on the same root resembling the two parent-forms. Many piebald animals + probably come under this same head. Such cases, as we shall see in the + chapter on Crossing, apparently result from certain characters not + readily blending together, and, as a consequence of this incapacity for + fusion, the offspring either perfectly resemble one of their two parents, + or resemble one parent in one part and the other parent in another part; + or whilst young are intermediate in character, but with advancing age + revert wholly or by segments to either parent-form, or to both. Thus + young trees of the <i>Cytisus adami</i> are intermediate in foliage and + flowers between the two parent-forms; but when older the buds continually + revert either partially or wholly to both forms. The cases given in the + eleventh chapter on the changes which occurred during growth <!-- Page 38 + --><span class="pagenum"><a name="page38"></a>{38}</span>in crossed + plants of Tropæolum, Cereus, Datura, and Lathyrus are all analogous. As + however these plants are hybrids of the first generation, and as their + buds after a time come to resemble their parents and not their + grandparents, these cases do not at first appear to come under the law of + reversion in the ordinary sense of the word; nevertheless, as the change + is effected through a succession of bud-generations on the same plant, + they may be thus included.</p> + + <p>Analogous facts have been observed in the animal kingdom, and are more + remarkable, as they occur strictly in the same individual, and not as + with plants through a succession of bud-generations. With animals the act + of reversion, if it can be so designated, does not pass over a true + generation, but merely over the early stages of growth in the same + individual. For instance, I crossed several white hens with a black cock, + and many of the chickens were during the first year perfectly white, but + acquired during the second year black feathers; on the other hand, some + of the chickens which were at first black became during the second year + piebald with white. A great breeder<a name="NtA_87" + href="#Nt_87"><sup>[87]</sup></a> says, that a Pencilled Brahma hen which + has any of the blood of the Light Brahma in her, will "occasionally + produce a pullet well pencilled during the first year, but she will most + likely moult brown on the shoulders and become quite unlike her original + colours in the second year." The same thing occurs with Light Brahmas if + of impure blood. I have observed exactly similar cases with the crossed + offspring from differently coloured pigeons. But here is a more + remarkable fact: I crossed a turbit, which has a frill formed by the + feathers being reversed on its breast, with a trumpeter; and one of the + young pigeons thus raised showed at first not a trace of the frill, but, + after moulting thrice, a small yet unmistakably distinct frill appeared + on its breast. According to Girou,<a name="NtA_88" + href="#Nt_88"><sup>[88]</sup></a> calves produced from a red cow by a + black bull, or from a black cow by a red bull, are not rarely born red, + and subsequently become black.</p> + + <p>In the foregoing cases, the characters which appear with advancing age + are the result of a cross in the previous or some <!-- Page 39 --><span + class="pagenum"><a name="page39"></a>{39}</span>former generation; but in + the following cases, the characters which thus reappear formerly + appertained to the species, and were lost at a more or less remote epoch. + Thus, according to Azara,<a name="NtA_89" + href="#Nt_89"><sup>[89]</sup></a> the calves of a hornless race of cattle + which originated in Corrientes, though at first quite hornless, as they + become adult sometimes acquire small, crooked, and loose horns; and these + in succeeding years occasionally become attached to the skull. White and + black bantams, both of which generally breed true, sometimes assume as + they grow old a saffron or red plumage. For instance, a first-rate black + bantam has been described, which during three seasons was perfectly + black, but then annually became more and more red; and it deserves notice + that this tendency to change, whenever it occurs in a bantam, "is almost + certain to prove hereditary."<a name="NtA_90" + href="#Nt_90"><sup>[90]</sup></a> The cuckoo or blue-mottled Dorking + cock, when old, is liable to acquire yellow or orange hackles in place of + his proper bluish-grey hackles.<a name="NtA_91" + href="#Nt_91"><sup>[91]</sup></a> Now, as <i>Gallus bankiva</i> is + coloured red and orange, and as Dorking fowls and both kinds of bantams + are descended from this species, we can hardly doubt that the change + which occasionally occurs in the plumage of these birds as their age + advances, results from a tendency in the individual to revert to the + primitive type.</p> + +<hr class="short" /> + + <p><i>Crossing as a direct cause of Reversion.</i>—It has long been + notorious that hybrids and mongrels often revert to both or to one of + their parent-forms, after an interval of from two to seven or eight, or + according to some authorities even a greater number of generations. But + that the act of crossing in itself gives an impulse towards reversion, as + shown by the reappearance of long-lost characters, has never, I believe, + been hitherto proved. The proof lies in certain peculiarities, which do + not characterise the immediate parents, and therefore cannot have been + derived from them, frequently appearing in the offspring of two breeds + when crossed, which peculiarities never appear, or appear with extreme + rarity, in these same breeds, as long as they are <!-- Page 40 --><span + class="pagenum"><a name="page40"></a>{40}</span>precluded from crossing. + As this conclusion seems to me highly curious and novel, I will give the + evidence in detail.</p> + +<blockquote class="b1n"> + + <p>My attention was first called to this subject, and I was led to make + numerous experiments, by MM. Boitard and Corbié having stated that, when + they crossed certain breeds, pigeons coloured like the wild <i>C. + livia</i>, or the common dovecot, namely, slaty-blue, with double black + wing-bars, sometimes chequered with black, white loins, the tail barred + with black, with the outer feathers edged with white, were almost + invariably produced. The breeds which I crossed, and the remarkable + results attained, have been fully described in the sixth chapter. I + selected pigeons, belonging to true and ancient breeds, which had not a + trace of blue or any of the above specified marks; but when crossed, and + their mongrels recrossed, young birds were continually produced, more or + less plainly coloured slaty-blue, with some or all of the proper + characteristic marks. I may recall to the reader's memory one case, + namely, that of a pigeon, hardly distinguishable from the wild Shetland + species, the grandchild of a red-spot, white fantail, and two black + barbs, from any of which, when purely-bred, the production of a pigeon + coloured like the wild <i>C. livia</i> would have been almost a + prodigy.</p> + + <p>I was thus led to make the experiments, recorded in the seventh + chapter, on fowls. I selected long-established, pure breeds, in which + there was not a trace of red, yet in several of the mongrels feathers of + this colour appeared; and one magnificent bird, the offspring of a black + Spanish cock and white Silk hen, was coloured almost exactly like the + wild <i>Gallus bankiva</i>. All who know anything of the breeding of + poultry will admit that tens of thousands of pure Spanish and of pure + white Silk fowls might have been reared without the appearance of a red + feather. The fact, given on the authority of Mr. Tegetmeier, of the + frequent appearance, in mongrel fowls, of pencilled or + transversely-barred feathers, like those common to many gallinaceous + birds, is likewise apparently a case of reversion to a character formerly + possessed by some ancient progenitor of the family. I owe to the kindness + of this same excellent observer the inspection of some neck-hackles and + tail-feathers from a hybrid between the common fowl and a very distinct + species, the <i>Gallus varius</i>; and these feathers are transversely + striped in a conspicuous manner with dark metallic blue and grey, a + character which could not have been derived from either immediate + parent.</p> + + <p>I have been informed by Mr. B. P. Brent, that he crossed a white + Aylesbury drake and a black so-called Labrador duck, both of which are + true breeds, and he obtained a young drake closely like the mallard + (<i>A. boschas</i>). Of the musk-duck (<i>A. moschata</i>, Linn.) there + are two sub-breeds, namely, white and slate-coloured; and these I am + informed breed true, or nearly true. But the Rev. W. D. Fox tells me + that, by putting a white drake to a slate-coloured duck, black birds, + pied with white, like the wild musk-duck, were always produced.</p> + + <p>We have seen in the fourth chapter, that the so-called Himalayan + rabbit, with its snow-white body, black ears, nose, tail, and feet, + breeds <!-- Page 41 --><span class="pagenum"><a + name="page41"></a>{41}</span>perfectly true. This race is known to have + been formed by the union of two varieties of silver-grey rabbits. Now, + when a Himalayan doe was crossed by a sandy-coloured buck, a silver-grey + rabbit was produced; and this is evidently a case of reversion to one of + the parent varieties. The young of the Himalayan rabbit are born + snow-white, and the dark marks do not appear until some time + subsequently; but occasionally young Himalayan rabbits are born of a + light silver-grey, which colour soon disappears; so that here we have a + trace of reversion, during an early period of life, to the + parent-varieties, independently of any recent cross.</p> + + <p>In the third chapter is was shown that at an ancient period some + breeds of cattle in the wilder parts of Britain were white with dark + ears, and that the cattle now kept half wild in certain parks, and those + which have run quite wild in two distant parts of the world, are likewise + thus coloured. Now, an experienced breeder, Mr. J. Beasley, of + Northamptonshire,<a name="NtA_92" href="#Nt_92"><sup>[92]</sup></a> + crossed some carefully selected West Highland cows with purely-bred + shorthorn bulls. The bulls were red, red and white, or dark roan; and the + Highland cows were all of a red colour, inclining to a light or yellow + shade. But a considerable number of the offspring—and Mr. Beasley + calls attention to this as a remarkable fact—were white, or white + with red ears. Bearing in mind that none of the parents were white, and + that they were purely-bred animals, it is highly probable that here the + offspring reverted, in consequence of the cross, to the colour either of + the aboriginal parent-species or of some ancient and half-wild + parent-breed. The following case, perhaps, comes under the same head: + cows in their natural state have their udders but little developed, and + do not yield nearly so much milk as our domesticated animals. Now there + is some reason to believe<a name="NtA_93" + href="#Nt_93"><sup>[93]</sup></a> that cross-bred animals between two + kinds, both of which are good milkers, such as Alderneys and Shorthorns, + often turn out worthless in this respect.</p> + + <p>In the chapter on the Horse reasons were assigned for believing that + the primitive stock was striped and dun-coloured; and details were given, + showing that in all parts of the world stripes of a dark colour + frequently appear along the spine, across the legs, and on the shoulders, + where they are occasionally double or treble, and even sometimes on the + face and body of horses of all breeds and of all colours. But the stripes + appear most frequently on the various kinds of duns. They may sometimes + plainly be seen on foals, and subsequently disappear. The dun-colour and + the stripes are strongly transmitted when a horse thus characterised is + crossed with any other; but I was not able to prove that striped duns are + generally produced from the crossing of two distinct breeds, neither of + which are duns, though this does sometimes occur.</p> + + <p>The legs of the ass are often striped, and this may be considered as a + reversion to the wild parent-form, the <i>Asinus tæniopus</i> of + Abyssinia,<a name="NtA_94" href="#Nt_94"><sup>[94]</sup></a> which is + thus striped. In the domestic animal the stripes on the shoulder are + occasionally double, or forked at the extremity, as in certain zebrine + <!-- Page 42 --><span class="pagenum"><a + name="page42"></a>{42}</span>species. There is reason to believe that the + foal is frequently more plainly striped on the legs than the adult + animal. As with the horse, I have not acquired any distinct evidence that + the crossing of differently-coloured varieties of the ass brings out the + stripes.</p> + + <p>But now let us turn to the result of crossing the horse and ass. + Although mules are not nearly so numerous in England as asses, I have + seen a much greater number with striped legs, and with the stripes far + more conspicuous than in either parent-form. Such mules are generally + light-coloured, and might be called fallow-duns. The shoulder-stripe in + one instance was deeply forked at the extremity, and in another instance + was double, though united in the middle. Mr. Martin gives a figure of a + Spanish mule with strong zebra-like marks on its legs,<a name="NtA_95" + href="#Nt_95"><sup>[95]</sup></a> and remarks, that mules are + particularly liable to be thus striped on their legs. In South America, + according to Roulin,<a name="NtA_96" href="#Nt_96"><sup>[96]</sup></a> + such stripes are more frequent and conspicuous in the mule than in the + ass. In the United States, Mr. Gosse,<a name="NtA_97" + href="#Nt_97"><sup>[97]</sup></a> speaking of these animals, says, "that + in a great number, perhaps in nine out of every ten, the legs are banded + with transverse dark stripes."</p> + + <p>Many years ago I saw in the Zoological Gardens a curious triple + hybrid, from a bay mare, by a hybrid from a male ass and female zebra. + This animal when old had hardly any stripes; but I was assured by the + superintendent, that when young it had shoulder-stripes, and faint + stripes on its flanks and legs. I mention this case more especially as an + instance of the stripes being much plainer during youth than in old + age.</p> + + <p>As the zebra has such conspicuously striped legs, it might have been + expected that the hybrids from this animal and the common ass would have + had their legs in some degree striped; but it appears from the figures + given in Dr. Gray's 'Knowsley Gleanings,' and still more plainly from + that given by Geoffroy and F. Cuvier,<a name="NtA_98" + href="#Nt_98"><sup>[98]</sup></a> that the legs are much more + conspicuously striped than the rest of the body; and this fact is + intelligible only on the belief that the ass aids in giving, through the + power of reversion, this character to its hybrid offspring.</p> + + <p>The quagga is banded over the whole front part of its body like a + zebra, but has no stripes on its legs, or mere traces of them. But in the + famous hybrid bred by Lord Morton,<a name="NtA_99" + href="#Nt_99"><sup>[99]</sup></a> from a chesnut, nearly purely-bred, + Arabian mare, by a male quagga, the stripes were "more strongly defined + and darker than those on the legs of the quagga." The mare was + subsequently put to a black Arabian horse, and bore two colts, both of + which, as formerly stated, were plainly striped on the legs, and one of + them likewise had stripes on the neck and body.</p> + + <p>The <i>Asinus Indicus</i><a name="NtA_100" + href="#Nt_100"><sup>[100]</sup></a> is characterised by a spinal stripe, + without shoulder <!-- Page 43 --><span class="pagenum"><a + name="page43"></a>{43}</span>or leg stripes; but traces of these latter + stripes may occasionally be seen even in the adult;<a name="NtA_101" + href="#Nt_101"><sup>[101]</sup></a> and Colonel S. Poole, who has had + ample opportunities for observation, informs me that in the foal, when + first born, the head and legs are often striped, but the shoulder-stripe + is not so distinct as in the domestic ass; all these stripes, excepting + that along the spine, soon disappear. Now a hybrid, raised at Knowsley<a + name="NtA_102" href="#Nt_102"><sup>[102]</sup></a> from a female of this + species by a male domestic ass, had all four legs transversely and + conspicuously striped, had three short stripes on each shoulder, and had + even some zebra-like stripes on its face! Dr. Gray informs me that he has + seen a second hybrid of the same parentage similarly striped.</p> + +</blockquote> + + <p>From these facts we see that the crossing of the several equine + species tends in a marked manner to cause stripes to appear on various + parts of the body, especially on the legs. As we do not know whether the + primordial parent of the genus was striped, the appearance of the stripes + can only hypothetically be attributed to reversion. But most persons, + after considering the many undoubted cases of variously coloured marks + reappearing by reversion in crossed pigeons, fowls, ducks, &c., will + come to the same conclusion with respect to the horse-genus; and in this + case we must admit that the progenitor of the group was striped on the + legs, shoulders, face, and probably over the whole body, like a zebra. If + we reject this view, the frequent and almost regular appearance of + stripes in the several foregoing hybrids is left without any + explanation.</p> + +<hr class="short" /> + + <p>It would appear that with crossed animals a similar tendency to the + recovery of lost characters holds good even with instincts. There are + some breeds of fowls which are called "everlasting layers," because they + have lost the instinct of incubation; and so rare is it for them to + incubate that I have seen notices published in works on poultry, when + hens of such breeds have taken to sit.<a name="NtA_103" + href="#Nt_103"><sup>[103]</sup></a> Yet the aboriginal species was of + course a good incubator; for with birds in a state of nature hardly any + <!-- Page 44 --><span class="pagenum"><a + name="page44"></a>{44}</span>instinct is so strong as this. Now, so many + cases have been recorded of the crossed offspring from two races, neither + of which are incubators, becoming first-rate sitters, that the + reappearance of this instinct must be attributed to reversion from + crossing. One author goes so far as to say, "that a cross between two + non-sitting varieties almost invariably produces a mongrel that becomes + broody, and sits with remarkable steadiness."<a name="NtA_104" + href="#Nt_104"><sup>[104]</sup></a> Another author, after giving a + striking example, remarks that the fact can be explained only on the + principle that "two negatives make a positive." It cannot, however, be + maintained that hens produced from a cross between two non-sitting breeds + invariably recover their lost instinct, any more than that crossed fowls + or pigeons invariably recover the red or blue plumage of their + prototypes. I raised several chickens from a Polish hen by a Spanish + cock,—breeds which do not incubate,—and none of the young + hens at first recovered their instinct, and this appeared to afford a + well-marked exception to the foregoing rule; but one of these hens, the + only one which was preserved, in the third year sat well on her eggs and + reared a brood of chickens. So that here we have the appearance with + advancing age of a primitive instinct, in the same manner as we have seen + that the red plumage of the <i>Gallus bankiva</i> is sometimes reacquired + by crossed and purely-bred fowls of various kinds as they grow old.</p> + + <p>The parents of all our domesticated animals were of course + aboriginally wild in disposition; and when a domesticated species is + crossed with a distinct species, whether this is a domesticated or only + tamed animal, the hybrids are often wild <!-- Page 45 --><span + class="pagenum"><a name="page45"></a>{45}</span>to such a degree, that + the fact is intelligible only on the principle that the cross has caused + a partial return to the primitive disposition.</p> + + <p>The Earl of Powis formerly imported some thoroughly domesticated + humped cattle from India, and crossed them with English breeds, which + belong to a distinct species; and his agent remarked to me, without any + question having been asked, how oddly wild the cross-bred animals were. + The European wild boar and the Chinese domesticated pig are almost + certainly specifically distinct: Sir F. Darwin crossed a sow of the + latter breed with a wild Alpine boar which had become extremely tame, but + the young, though having half-domesticated blood in their veins, were + "extremely wild in confinement, and would not eat swill like common + English pigs." Mr. Hewitt, who has had great experience in crossing tame + cock-pheasants with fowls belonging to five breeds, gives as the + character of all "extraordinary wildness;"<a name="NtA_105" + href="#Nt_105"><sup>[105]</sup></a> but I have myself seen one exception + to this rule. Mr. S. J. Salter,<a name="NtA_106" + href="#Nt_106"><sup>[106]</sup></a> who raised a large number of hybrids + from a bantam-hen by <i>Gallus Sonneratii</i>, states that "all were + exceedingly wild." Mr. Waterton<a name="NtA_107" + href="#Nt_107"><sup>[107]</sup></a> bred some wild ducks from eggs + hatched under a common duck, and the young were allowed to cross freely + both amongst themselves and with the tame ducks; they were "half wild and + half tame; they came to the windows to be fed, but still they had a + wariness about them quite remarkable."</p> + + <p>On the other hand, mules from the horse and ass are certainly not in + the least wild, yet they are notorious for obstinacy and vice. Mr. Brent, + who has crossed canary-birds with many kinds of finches, has not + observed, as he informs me, that the hybrids were in any way remarkably + wild. Hybrids are often raised between the common and musk duck, and I + have been assured by three persons, who have kept these crossed birds, + that they were not wild; but Mr. Garnett<a name="NtA_108" + href="#Nt_108"><sup>[108]</sup></a> observed that his female hybrids + exhibited "migratory propensities," of which there is not a vestige in + the common or musk duck. No case is <!-- Page 46 --><span + class="pagenum"><a name="page46"></a>{46}</span>known of this latter bird + having escaped and become wild in Europe or Asia, except, according to + Pallas, on the Caspian Sea; and the common domestic duck only + occasionally becomes wild in districts where large lakes and fens abound. + Nevertheless, a large number of cases have been recorded<a name="NtA_109" + href="#Nt_109"><sup>[109]</sup></a> of hybrids from these two ducks, + although so few are reared in comparison with purely-bred birds of either + species, having been shot in a completely wild state. It is improbable + that any of these hybrids could have acquired their wildness from the + musk-duck having paired with a truly wild duck; and this is known not to + be the case in North America; hence we must infer that they have + reacquired, through reversion, their wildness, as well as renewed powers + of flight.</p> + + <p>These latter facts remind us of the statements, so frequently made by + travellers in all parts of the world, on the degraded state and savage + disposition of crossed races of man. That many excellent and kind-hearted + mulattos have existed no one will dispute; and a more mild and gentle set + of men could hardly be found than the inhabitants of the island of + Chiloe, who consist of Indians commingled with Spaniards in various + proportions. On the other hand, many years ago, long before I had thought + of the present subject, I was struck with the fact that, in South + America, men of complicated descent between Negroes, Indians, and + Spaniards, seldom had, whatever the cause might be, a good expression.<a + name="NtA_110" href="#Nt_110"><sup>[110]</sup></a> Livingstone,—and + a more unimpeachable authority cannot be quoted,—after speaking of + a half-caste man on the Zambesi, described by the Portuguese as a rare + monster of inhumanity, remarks, "It is unaccountable why half-castes, + such as he, are so much more cruel than the Portuguese, but such is + undoubtedly the case." An inhabitant remarked to Livingstone, "God made + white men, and God made black men, but the Devil made half-castes."<a + name="NtA_111" href="#Nt_111"><sup>[111]</sup></a> When two races, both + <!-- Page 47 --><span class="pagenum"><a name="page47"></a>{47}</span>low + in the scale, are crossed, the progeny seems to be eminently bad. Thus + the noble-hearted Humboldt, who felt none of that prejudice against the + inferior races now so current in England, speaks in strong terms of the + bad and savage disposition of Zambos, or half-castes between Indians and + Negroes; and this conclusion has been arrived at by various observers.<a + name="NtA_112" href="#Nt_112"><sup>[112]</sup></a> From these facts we + may perhaps infer that the degraded state of so many half-castes is in + part due to reversion to a primitive and savage condition, induced by the + act of crossing, as well as to the unfavourable moral conditions under + which they generally exist.</p> + +<hr class="short" /> + + <p><i>Summary on the proximate causes leading to + Reversion.</i>—When purely-bred animals or plants reassume + long-lost characters,—when the common ass, for instance, is born + with striped legs, when a pure race of black or white pigeons throws a + slaty-blue bird, or when a cultivated heartsease with large and rounded + flowers produces a seedling with small and elongated flowers,—we + are quite unable to assign any proximate cause. When animals run wild, + the tendency to reversion, which, though it has been greatly exaggerated, + no doubt exists, is sometimes to a certain extent intelligible. Thus, + with feral pigs, exposure to the weather will probably favour the growth + of the bristles, as is known to be the case with the hair of other + domesticated animals, and through correlation the tusks will tend to be + redeveloped. But the reappearance of coloured longitudinal stripes on + young feral pigs cannot be attributed to the direct action of external + conditions. In this case, and in many others, we can only say that + changed habits of life apparently have favoured a tendency, inherent or + latent in the species, to return to the primitive state.</p> + + <p>It will be shown in a future chapter that the position of flowers on + the summit of the axis, and the position of seeds within the capsule, + sometimes determine a tendency towards reversion; and this apparently + depends on the amount of sap or nutriment which the flower-buds and seeds + receive. The position, also, of buds, either on branches or on roots, + sometimes determines, as was formerly shown, the transmission of the <!-- + Page 48 --><span class="pagenum"><a name="page48"></a>{48}</span>proper + character of the variety, or its reversion to a former state.</p> + + <p>We have seen in the last section that when two races or species are + crossed there is the strongest tendency to the reappearance in the + offspring of long-lost characters, possessed by neither parent nor + immediate progenitor. When two white, or red, or black pigeons, of + well-established breeds, are united, the offspring are almost sure to + inherit the same colours; but when differently-coloured birds are + crossed, the opposed forces of inheritance apparently counteract each + other, and the tendency which is inherent in both parents to produce + slaty-blue offspring becomes predominant. So it is in several other + cases. But when, for instance, the ass is crossed with <i>A. Indicus</i> + or with the horse,—animals which have not striped legs,—and + the hybrids have conspicuous stripes on their legs and even on their + faces, all that can be said is, that an inherent tendency to reversion is + evolved through some disturbance in the organisation caused by the act of + crossing.</p> + + <p>Another form of reversion is far commoner, indeed is almost universal + with the offspring from a cross, namely, to the characters proper to + either pure parent-form. As a general rule, crossed offspring in the + first generation are nearly intermediate between their parents, but the + grandchildren and succeeding generations continually revert, in a greater + or lesser degree, to one or both of their progenitors. Several authors + have maintained that hybrids and mongrels include all the characters of + both parents, not fused together, but merely mingled in different + proportions in different parts of the body; or, as Naudin<a + name="NtA_113" href="#Nt_113"><sup>[113]</sup></a> has expressed it, a + hybrid is a living mosaic-work, in which the eye cannot distinguish the + discordant elements, so completely are they intermingled. We can hardly + doubt that, in a certain sense, this is true, as when we behold in a + hybrid the elements of both species segregating themselves into segments + in the same flower or fruit, by a process of self-attraction or + self-affinity; this segregation taking place either by seminal or by + bud-propagation. Naudin further believes that the segregation of the two + specific elements or essences is eminently liable to occur in the male + and female reproductive matter; and he thus explains the almost <!-- Page + 49 --><span class="pagenum"><a name="page49"></a>{49}</span>universal + tendency to reversion in successive hybrid generations. For this would be + the natural result of the union of pollen and ovules, in both of which + the elements of the same species had been segregated by self-affinity. + If, on the other hand, pollen which included the elements of one species + happened to unite with ovules including the elements of the other + species, the intermediate or hybrid state would still be retained, and + there would be no reversion. But it would, as I suspect, be more correct + to say that the elements of both parent-species exist in every hybrid in + a double state, namely, blended together and completely separate. How + this is possible, and what the term specific essence or element may be + supposed to express, I shall attempt to show in the hypothetical chapter + on pangenesis.</p> + + <p>But Naudin's view, as propounded by him, is not applicable to the + reappearance of characters lost long ago by variation; and it is hardly + applicable to races or species which, after having been crossed at some + former period with a distinct form, and having since lost all traces of + the cross, nevertheless occasionally yield an individual which reverts + (as in the case of the great-great-grandchild of the pointer Sappho) to + the crossing form. The most simple case of reversion, namely, of a hybrid + or mongrel to its grandparents, is connected by an almost perfect series + with the extreme case of a purely-bred race recovering characters which + had been lost during many ages; and we are thus led to infer that all the + cases must be related by some common bond.</p> + + <p>Gärtner believed that only those hybrid plants which are highly + sterile exhibit any tendency to reversion to their parent-forms. It is + rash to doubt so good an observer, but this conclusion must I think be an + error; and it may perhaps be accounted for by the nature of the genera + observed by him, for he admits that the tendency differs in different + genera. The statement is also directly contradicted by Naudin's + observations, and by the notorious fact that perfectly fertile mongrels + exhibit the tendency in a high degree,—even in a higher degree, + according to Gärtner himself, than hybrids.<a name="NtA_114" + href="#Nt_114"><sup>[114]</sup></a></p> + + <p>Gärtner further states that reversions rarely occur with <!-- Page 50 + --><span class="pagenum"><a name="page50"></a>{50}</span>hybrid plants + raised from species which have not been cultivated, whilst, with those + which have been long cultivated, they are of frequent occurrence. This + conclusion explains a curious discrepancy: Max Wichura,<a name="NtA_115" + href="#Nt_115"><sup>[115]</sup></a> who worked exclusively on willows, + which had not been subjected to culture, never saw an instance of + reversion; and he goes so far as to suspect that the careful Gärtner had + not sufficiently protected his hybrids from the pollen of the + parent-species: Naudin, on the other hand, who chiefly experimented on + cucurbitaceous and other cultivated plants, insists more strenuously than + any other author on the tendency to reversion in all hybrids. The + conclusion that the condition of the parent-species, as affected by + culture, is one of the proximate causes leading to reversion, agrees + fairly well with the converse case of domesticated animals and cultivated + plants being liable to reversion when they become feral; for in both + cases the organisation or constitution must be disturbed, though in a + very different way.</p> + + <p>Finally, we have seen that characters often reappear in purely-bred + races without our being able to assign any proximate cause; but when they + become feral this is either indirectly or directly induced by the change + in their conditions of life. With crossed breeds, the act of crossing in + itself certainly leads to the recovery of long-lost characters, as well + as of those derived from either parent-form. Changed conditions, + consequent on cultivation, and the relative position of buds, flowers, + and seeds on the plant, all apparently aid in giving this same tendency. + Reversion may occur either through seminal or bud generation, generally + at birth, but sometimes only with an advance of age. Segments or portions + of the individual may alone be thus affected. That a being should be born + resembling in certain characters an ancestor removed by two or three, and + in some cases by hundreds or even thousands of generations, is assuredly + a wonderful fact. In these cases the child is commonly said to inherit + such characters directly from its grandparents or more remote ancestors. + But this view is hardly conceivable. If, however, we suppose that every + character is derived <!-- Page 51 --><span class="pagenum"><a + name="page51"></a>{51}</span>exclusively from the father or mother, but + that many characters lie latent in both parents during a long succession + of generations, the foregoing facts are intelligible. In what manner + characters may be conceived to lie latent, will be considered in a future + chapter to which I have lately alluded.</p> + +<hr class="short" /> + + <p><i>Latent Characters.</i>—But I must explain what is meant by + characters lying latent. The most obvious illustration is afforded by + secondary sexual characters. In every female all the secondary male + characters, and in every male all the secondary female characters, + apparently exist in a latent state, ready to be evolved under certain + conditions. It is well known that a large number of female birds, such as + fowls, various pheasants, partridges, peahens, ducks, &c., when old + or diseased, or when operated on, partly assume the secondary male + characters of their species. In the case of the hen-pheasant this has + been observed to occur far more frequently during certain seasons than + during others.<a name="NtA_116" href="#Nt_116"><sup>[116]</sup></a> A + duck ten years old has been known to assume both the perfect winter and + summer plumage of the drake.<a name="NtA_117" + href="#Nt_117"><sup>[117]</sup></a> Waterton<a name="NtA_118" + href="#Nt_118"><sup>[118]</sup></a> gives a curious case of a hen which + had ceased laying, and had assumed the plumage, voice, spurs, and warlike + disposition of the cock; when opposed to an enemy she would erect her + hackles and show fight. Thus every character, even to the instinct and + manner of fighting, must have lain dormant in this hen as long as her + ovaria continued to act. The females of two kinds of deer, when old, have + been known to acquire horns; and, as Hunter has remarked, we see + something of an analogous nature in the human species.</p> + + <p>On the other hand, with male animals, it is notorious that the + secondary sexual characters are more or less completely lost when they + are subjected to castration. Thus, if the operation be performed on a + young cock, he never, as Yarrell states, crows <!-- Page 52 --><span + class="pagenum"><a name="page52"></a>{52}</span>again; the comb, wattles, + and spurs do not grow to their full size, and the hackles assume an + intermediate appearance between true hackles and the feathers of the hen. + Cases are recorded of confinement alone causing analogous results. But + characters properly confined to the female are likewise acquired; the + capon takes to sitting on eggs, and will bring up chickens; and what is + more curious, the utterly sterile male hybrids from the pheasant and the + fowl act in the same manner, "their delight being to watch when the hens + leave their nests, and to take on themselves the office of a sitter."<a + name="NtA_119" href="#Nt_119"><sup>[119]</sup></a> That admirable + observer Réaumur<a name="NtA_120" href="#Nt_120"><sup>[120]</sup></a> + asserts that a cock, by being long confined in solitude and darkness, can + be taught to take charge of young chickens; he then utters a peculiar + cry, and retains during his whole life this newly acquired maternal + instinct. The many well-ascertained cases of various male mammals giving + milk, show that their rudimentary mammary glands retain this capacity in + a latent condition.</p> + + <p>We thus see that in many, probably in all cases, the secondary + characters of each sex lie dormant or latent in the opposite sex, ready + to be evolved under peculiar circumstances. We can thus understand how, + for instance, it is possible for a good milking cow to transmit her good + qualities through her male offspring to future generations; for we may + confidently believe that these qualities are present, though latent, in + the males of each generation. So it is with the game-cock, who can + transmit his superiority in courage and vigour through his female to his + male offspring; and with man it is known <a name="NtA_121" + href="#Nt_121"><sup>[121]</sup></a> that diseases, such as hydrocele, + necessarily confined to the male sex, can be transmitted through the + female to the grandson. Such cases as these offer, as was remarked at the + commencement of this chapter, the simplest possible examples of + reversion; and they are intelligible on the belief that characters common + to the grandparent and grandchild of the same sex are present, though + latent, in the intermediate parent of the opposite sex.</p> + + <p>The subject of latent characters is so important, as we shall see in a + future chapter, that I will give another illustration. <!-- Page 53 + --><span class="pagenum"><a name="page53"></a>{53}</span>Many animals + have the right and left sides of their body unequally developed: this is + well known to be the case with flat-fish, in which the one side differs + in thickness and colour, and in the shape of the fins, from the other; + and during the growth of the young fish one eye actually travels, as + shown by Steenstrup, from the lower to the upper surface.<a + name="NtA_122" href="#Nt_122"><sup>[122]</sup></a> In most flat-fishes + the left is the blind side, but in some it is the right; though in both + cases "wrong fishes," which are developed in a reversed manner to what is + usual, occasionally occur, and in <i>Platessa flesus</i> the right or + left side is indifferently developed, the one as often as the other. With + gasteropods or shell-fish, the right and left sides are extremely + unequal; the far greater number of species are dextral, with rare and + occasional reversals of development, and some few are normally sinistral; + but certain species of Bulimus, and, many Achatinellæ,<a name="NtA_123" + href="#Nt_123"><sup>[123]</sup></a> are as often sinistral as dextral. I + will give an analogous case in the great Articulate kingdom: the two + sides of Verruca<a name="NtA_124" href="#Nt_124"><sup>[124]</sup></a> are + so wonderfully unlike, that without careful dissection it is extremely + difficult to recognise the corresponding parts on the opposite sides of + the body; yet it is apparently a mere matter of chance whether it be the + right or the left side that undergoes so singular an amount of change. + One plant is known to me<a name="NtA_125" + href="#Nt_125"><sup>[125]</sup></a> in which the flower, according as it + stands on the one or other side of the spike, is unequally developed. In + all the foregoing cases the two sides of the animal are perfectly + symmetrical at an early period of growth. Now, whenever a species is as + liable to be unequally developed on the one as on the other side, we may + infer that the capacity for such development is present, though latent, + in the undeveloped side. And as a reversal of development occasionally + occurs in animals of many kinds, this latent capacity is probably very + common.</p> + + <p>The best yet simplest instances of characters lying dormant are, + perhaps, those previously given, in which chickens and <!-- Page 54 + --><span class="pagenum"><a name="page54"></a>{54}</span>young pigeons, + raised from a cross between differently coloured birds, are at first of + one colour, but in a year or two acquire feathers of the colour of the + other parent; for in this case the tendency to a change of plumage is + clearly latent in the young bird. So it is with hornless breeds of + cattle, some of which acquire, as they grow old, small horns. Purely bred + black and white bantams, and some other fowls, occasionally assume, with + advancing years, the red feathers of the parent-species. I will here add + a somewhat different case, as it connects in a striking manner latent + characters of two classes. Mr. Hewitt<a name="NtA_126" + href="#Nt_126"><sup>[126]</sup></a> possessed an excellent Sebright + gold-laced hen bantam, which, as she became old, grew diseased in her + ovaria, and assumed male characters. In this breed the males resemble the + females in all respects except in their combs, wattles, spurs, and + instincts; hence it might have been expected that the diseased hen would + have assumed only those masculine characters which are proper to the + breed, but she acquired, in addition, well-arched tail sickle-feathers + quite a foot in length, saddle-feathers on the loins, and hackles on the + neck,—ornaments which, as Mr. Hewitt remarks, "would be held as + abominable in this breed." The Sebright bantam is known<a name="NtA_127" + href="#Nt_127"><sup>[127]</sup></a> to have originated about the year + 1800 from a cross between a common bantam and a Polish fowl, recrossed by + a hen-tailed bantam, and carefully selected; hence there can hardly be a + doubt that the sickle-feathers and hackles which appeared in the old hen + were derived from the Polish fowl or common bantam; and we thus see that + not only certain masculine characters proper to the Sebright bantam, but + other masculine characters derived from the first progenitors of the + breed, removed by a period of above sixty years, were lying latent in + this hen-bird, ready to be evolved as soon as her ovaria became + diseased.</p> + + <p>From these several facts it must be admitted that certain characters, + capacities, and instincts may lie latent in an individual, and even in a + succession of individuals, without our being able to detect the least + signs of their presence. We have <!-- Page 55 --><span class="pagenum"><a + name="page55"></a>{55}</span>already seen that the transmission of a + character from the grandparent to the grandchild, with its apparent + omission in the intermediate parent of the opposite sex, becomes simple + on this view. When fowls, pigeons, or cattle of different colours are + crossed, and their offspring change colour as they grow old, or when the + crossed turbit acquired the characteristic frill after its third moult, + or when purely-bred bantams partially assume the red plumage of their + prototype, we cannot doubt that these qualities were from the first + present, though latent, in the individual animal, like the characters of + a moth in the caterpillar. Now, if these animals had produced offspring + before they had acquired with advancing age their new characters, nothing + is more probable than that they would have transmitted them to some of + their offspring, which in this case would in appearance have received + such characters from their grandparents or more distant progenitors. We + should then have had a case of reversion, that is, of the reappearance in + the child of an ancestral character, actually present, though during + youth completely latent, in the parent; and this we may safely conclude + is what occurs with reversions of all kinds to progenitors however + remote.</p> + + <p>This view of the latency in each generation of all the characters + which appear through reversion, is also supported by their actual + presence in some cases during early youth alone, or by their more + frequent appearance and greater distinctness at this age than during + maturity. We have seen that this is often the case with the stripes on + the legs and faces of the several species of the horse-genus. The + Himalayan rabbit, when crossed, sometimes produces offspring which revert + to the parent silver-grey breed, and we have seen that in purely bred + animals pale-grey fur occasionally reappears during early youth. Black + cats, we may feel assured, would occasionally produce by reversion + tabbies; and on young black kittens, with a pedigree<a name="NtA_128" + href="#Nt_128"><sup>[128]</sup></a> known to have been long pure, faint + traces of stripes may almost always be seen which afterwards disappear. + Hornless Suffolk cattle occasionally produce by reversion horned animals; + and Youatt<a name="NtA_129" href="#Nt_129"><sup>[129]</sup></a> asserts + that even in hornless individuals <!-- Page 56 --><span + class="pagenum"><a name="page56"></a>{56}</span>"the rudiment of a horn + may be often felt at an early age."</p> + + <p>No doubt it appears at first sight in the highest degree improbable + that in every horse of every generation there should be a latent capacity + and tendency to produce stripes, though these may not appear once in a + thousand generations; that in every white, black, or other coloured + pigeon, which may have transmitted its proper colour during centuries, + there should be a latent capacity in the plumage to become blue and to be + marked with certain characteristic bars; that in every child in a + six-fingered family there should be the capacity for the production of an + additional digit; and so in other cases. Nevertheless there is no more + inherent improbability in this being the case than in a useless and + rudimentary organ, or even in only a tendency to the production of a + rudimentary organ, being inherited during millions of generations, as is + well known to occur with a multitude of organic beings. There is no more + inherent improbability in each domestic pig, during a thousand + generations, retaining the capacity and tendency to develop great tusks + under fitting conditions, than in the young calf having retained for an + indefinite number of generations rudimentary incisor teeth, which never + protrude through the gums.</p> + + <p>I shall give at the end of the next chapter a summary of the three + preceding chapters; but as isolated and striking cases of reversion have + here been chiefly insisted on, I wish to guard the reader against + supposing that reversion is due to some rare or accidental combination of + circumstances. When a character, lost during hundreds of generations, + suddenly reappears, no doubt some such combination must occur; but + reversions may be constantly observed, at least to the immediately + preceding generations, in the offspring of most unions. This has been + universally recognised in the case of hybrids and mongrels, but it has + been recognised simply from the difference between the united forms + rendering the resemblance of the offspring to their grandparents or more + remote progenitors of easy detection. Reversion is likewise almost + invariably the rule, as Mr. Sedgwick has shown, with certain diseases. + Hence we must conclude that a tendency to this peculiar form of + transmission is an integral part of the general law of inheritance. <!-- + Page 57 --><span class="pagenum"><a name="page57"></a>{57}</span></p> + +<hr class="short" /> + + <p><i>Monstrosities.</i>—A large number of monstrous growths and of + lesser anomalies are admitted by every one to be due to an arrest of + development, that is to the persistence of an embryonic condition. If + every horse or ass had striped legs whilst young, the stripes which + occasionally appear on these animals when adult would have to be + considered as due to the anomalous retention of an early character, and + not as due to reversion. Now, the leg-stripes in the horse-genus, and + some other characters in analogous cases, are apt to occur during early + youth and then to disappear; thus the persistence of early characters and + reversion are brought into close connexion.</p> + + <p>But many monstrosities can hardly be considered as the result of an + arrest of development; for parts of which no trace can be detected in the + embryo, but which occur in other members of the same class of animals or + plants, occasionally appear, and these may probably with truth be + attributed to reversion. For instance: supernumerary mammæ, capable of + secreting milk, are not extremely rare in women; and as many as five have + been observed. When four are developed, they are generally arranged + symmetrically on each side of the chest; and in one instance a woman (the + daughter of another with supernumerary mammæ) had one mamma, which + yielded milk, developed in the inguinal region. This latter case, when we + remember the position of the mammæ in some of the lower animals on both + the chest and inguinal region, is highly remarkable, and leads to the + belief that in all cases the additional mammæ in woman are due to + reversion. The facts given in the last chapter on the tendency in + supernumerary digits to regrowth after amputation, indicate their + relation to the digits of the lower vertebrate animals, and lead to the + suspicion that their appearance may in some manner be connected with + reversion. But I shall have to recur, in the chapter on pangenesis, to + the abnormal multiplication of organs, and likewise to their occasional + transposition. The occasional development in man of the coccygeal + vertebræ into a short and free tail, though it thus becomes in one sense + more perfectly developed, may at the same time be considered as an arrest + of development, and as a case of reversion. The greater frequency of a + monstrous kind of proboscis in the pig than in any other mammal, + considering the position of the pig <!-- Page 58 --><span + class="pagenum"><a name="page58"></a>{58}</span>in the mammalian series, + has likewise been attributed, perhaps truly, to reversion.<a + name="NtA_130" href="#Nt_130"><sup>[130]</sup></a></p> + +<blockquote class="b1n"> + + <p>When flowers which are properly irregular in structure become regular + or peloric, the change is generally looked at by botanists as a return to + the primitive state. But Dr. Maxwell Masters,<a name="NtA_131" + href="#Nt_131"><sup>[131]</sup></a> who has ably discussed this subject, + remarks that when, for instance, all the sepals of a Tropæolum become + green and of the same shape, instead of being coloured with one alone + prolonged into a spur, or when all the petals of a Linaria become simple + and regular, such cases may be due merely to an arrest of development; + for in these flowers all the organs during their earliest condition are + symmetrical, and, if arrested at this stage of growth, they would not + become irregular. If, moreover, the arrest were to take place at a still + earlier period of development, the result would be a simple tuft of green + leaves; and no one probably would call this a case of reversion. Dr. + Masters designates the cases first alluded to as regular peloria; and + others, in which all the corresponding parts assume a similar form of + irregularity, as when all the petals in a Linaria become spurred, as + irregular peloria. We have no right to attribute these latter cases to + reversion, until it can be shown to be probable that the parent-form, for + instance, of the genus Linaria had had all its petals spurred; for a + change of this nature might result from the spreading of an anomalous + structure, in accordance with the law, to be discussed in a future + chapter, of homologous parts tending to vary in the same manner. But as + both forms of peloria frequently occur on the same individual plant of + the Linaria,<a name="NtA_132" href="#Nt_132"><sup>[132]</sup></a> they + probably stand in some close relation to each other. On the doctrine that + peloria is simply the result of an arrest of development, it is difficult + to understand how an organ arrested at a very early period of growth + should acquire its full functional perfection;—how a petal, + supposed to be thus arrested, should acquire its brilliant colours, and + serve as an envelope to the flower, or a stamen produce efficient pollen; + yet this occurs with many peloric flowers. That pelorism is not due to + mere chance variability, but either to an arrest of development or to + reversion, we may infer from an observation made by Ch. Morren,<a + name="NtA_133" href="#Nt_133"><sup>[133]</sup></a> namely, that families + which have irregular flowers often "return by these monstrous growths to + their regular form; whilst we never see a regular flower realise the + structure of an irregular one."</p> + + <p>Some flowers have almost certainly become more or less completely + peloric through reversion. <i>Corydalis tuberosa</i> properly has one of + its two nectaries colourless, destitute of nectar, only half the size of + the other, and <!-- Page 59 --><span class="pagenum"><a + name="page59"></a>{59}</span>therefore, to a certain extent, in a + rudimentary state; the pistil is curved towards the perfect nectary, and + the hood, formed of the inner petals, slips off the pistil and stamens in + one direction alone, so that, when a bee sucks the perfect nectary, the + stigma and stamens are exposed and rubbed against the insect's body. In + several closely allied genera, as in Dielytra, &c., there are two + perfect nectaries, the pistil is straight, and the hood slips off on + either side, according as the bee sucks either nectary. Now, I have + examined several flowers of <i>Corydalis tuberosa</i>, in which both + nectaries were equally developed and contained nectar; in this we see + only the redevelopment of a partially aborted organ; but with this + redevelopment the pistil becomes straight, and the hood slips off in + either direction; so that these flowers have acquired the perfect + structure, so well adapted for insect agency, of Dielytra and its allies. + We cannot attribute these coadapted modifications to chance, or to + correlated variability; we must attribute them to reversion to a + primordial condition of the species.</p> + + <p>The peloric flowers of Pelargonium have their five petals in all + respects alike, and there is no nectary; so that they resemble the + symmetrical flowers of the closely allied Geranium-genus; but the + alternate stamens are also sometimes destitute of anthers, the shortened + filaments being left as rudiments, and in this respect they resemble the + symmetrical flowers of the closely allied genus, Erodium. Hence we are + led to look at the peloric flowers of Pelargonium as having probably + reverted to the state of some primordial form, the progenitor of the + three closely related genera of Pelargonium, Geranium, and Erodium.</p> + + <p>In the peloric form of <i>Antirrhinum majus</i>, appropriately called + the "<i>Wonder</i>," the tubular and elongated flowers differ wonderfully + from those of the common snapdragon; the calyx and the mouth of the + corolla consist of six equal lobes, and include six equal instead of four + unequal stamens. One of the two additional stamens is manifestly formed + by the development of a microscopically minute papilla, which may be + found at the base of the upper lip of the flower in all common + snapdragons, at least in nineteen plants examined by me. That this + papilla is a rudiment of a stamen was well shown by its various degrees + of development in crossed plants between the common and peloric + Antirrhinum. Again, a peloric <i>Galeobdolon luteum</i>, growing in my + garden, had five equal petals, all striped like the ordinary lower lip, + and included five equal instead of four unequal stamens; but Mr. R. + Keeley, who sent me this plant, informs me that the flowers vary greatly, + having from four to six lobes to the corolla, and from three to six + stamens.<a name="NtA_134" href="#Nt_134"><sup>[134]</sup></a> Now, as the + members of the two great families to which the Antirrhinum and + Galeobdolon belong are properly pentamerous, with some of the parts + confluent and others suppressed, we ought not to look at the sixth stamen + and the sixth lobe to the corolla in either case as due to reversion, any + more than the additional petals in double flowers in these same two + families. But the case is different with the fifth stamen in the peloric + Antirrhinum, which <!-- Page 60 --><span class="pagenum"><a + name="page60"></a>{60}</span>is produced by the redevelopment of a + rudiment always present, and which probably reveals to us the state of + the flower, as far as the stamens are concerned, at some ancient epoch. + It is also difficult to believe that the other four stamens and the + petals, after an arrest of development at a very early embryonic age, + would have come to full perfection in colour, structure, and function, + unless these organs had at some former period normally passed through a + similar course of growth. Hence it appears to me probable that the + progenitor of the genus Antirrhinum must at some remote epoch have + included five stamens and borne flowers in some degree resembling those + now produced by the peloric form.</p> + + <p>Lastly, I may add that many instances have been recorded of flowers, + not generally ranked as peloric, in which certain organs, normally few in + number, have been abnormally augmented. As such an increase of parts + cannot be looked at as an arrest of development, nor as due to the + redevelopment of rudiments, for no rudiments are present, and as these + additional parts bring the plant into closer relationship with its + natural allies, they ought probably to be viewed as reversions to a + primordial condition.</p> + +</blockquote> + + <p>These several facts show us in an interesting manner how intimately + certain abnormal states are connected together; namely, arrests of + development causing parts to become rudimentary or to be wholly + suppressed,—the redevelopment of parts at present in a more or less + rudimentary condition,—the reappearance of organs of which not a + vestige can now be detected,—and to these may be added, in the case + of animals, the presence during youth, and subsequent disappearance, of + certain characters which occasionally are retained throughout life. Some + naturalists look at all such abnormal structures as a return to the ideal + state of the group to which the affected being belongs; but it is + difficult to conceive what is meant to be conveyed by this expression. + Other naturalists maintain, with greater probability and distinctness of + view, that the common bond of connection between the several foregoing + cases is an actual, though partial, return to the structure of the + ancient progenitor of the group. If this view be correct, we must believe + that a vast number of characters, capable of evolution, lie hidden in + every organic being. But it would be a mistake to suppose that the number + is equally great in all beings. We know, for instance, that plants of + many orders occasionally become peloric; but many more cases have been + observed in the Labiatæ and Scrophulariaceæ than in any other order; and + in one genus of the Scrophulariaceæ, namely Linaria, no less <!-- Page 61 + --><span class="pagenum"><a name="page61"></a>{61}</span>than thirteen + species have been described in a peloric condition.<a name="NtA_135" + href="#Nt_135"><sup>[135]</sup></a> On this view of the nature of peloric + flowers, and <span class="correction" title="Original reads `bearnig'." + >bearing</span> in mind what has been said with respect to certain + monstrosities in the animal kingdom, we must conclude that the + progenitors of most plants and animals, though widely different in + structure, have left an impression capable of redevelopment on the germs + of their descendants.</p> + + <p>The fertilised germ of one of the higher animals, subjected as it is + to so vast a series of changes from the germinal cell to old + age,—incessantly agitated by what Quatrefages well calls the + <i>tourbillon vital</i>,—is perhaps the most wonderful object in + nature. It is probable that hardly a change of any kind affects either + parent, without some mark being left on the germ. But on the doctrine of + reversion, as given in this chapter, the germ becomes a far more + marvellous object, for, besides the visible changes to which it is + subjected, we must believe that it is crowded with invisible characters, + proper to both sexes, to both the right and left side of the body, and to + a long line of male and female ancestors separated by hundreds or even + thousands of generations from the present time; and these characters, + like those written on paper with invisible ink, all lie ready to be + evolved under certain known or unknown conditions.</p> + +<hr class="full" /> + +<p><!-- Page 62 --><span class="pagenum"><a name="page62"></a>{62}</span></p> + +<h3>CHAPTER XIV.</h3> + +<p class="cenhead">INHERITANCE <i>continued</i>—FIXEDNESS OF CHARACTER—PREPOTENCY—SEXUAL +LIMITATION—CORRESPONDENCE OF AGE.</p> + +<blockquote class="b1n"> + + <p><span class="scac">FIXEDNESS OF CHARACTER APPARENTLY NOT DUE TO + ANTIQUITY OF INHERITANCE</span>—<span class="scac">PREPOTENCY OF + TRANSMISSION IN INDIVIDUALS OF THE SAME FAMILY, IN CROSSED BREEDS AND + SPECIES; OFTEN STRONGER IN ONE SEX THAN THE OTHER; SOMETIMES DUE TO THE + SAME CHARACTER BEING PRESENT AND VISIBLE IN ONE BREED AND LATENT IN THE + OTHER</span>—<span class="scac">INHERITANCE AS LIMITED BY + SEX</span>—<span class="scac">NEWLY-ACQUIRED CHARACTERS IN OUR + DOMESTICATED ANIMALS OFTEN TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST + BY ONE SEX ALONE</span>—<span class="scac">INHERITANCE AT + CORRESPONDING PERIODS OF LIFE</span>—<span class="scac">THE + IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRYOLOGY; AS EXHIBITED IN + DOMESTICATED ANIMALS; AS EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF + INHERITED DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN + THE PARENT</span>—<span class="scac">SUMMARY OF THE THREE PRECEDING + CHAPTERS.</span></p> + +</blockquote> + + <p>In the two last chapters the nature and force of Inheritance, the + circumstances which interfere with its power, and the tendency to + Reversion, with its many remarkable contingencies, were discussed. In the + present chapter some other related phenomena will be treated of, as fully + as my materials permit.</p> + +<p class="cenhead"><i>Fixedness of Character.</i></p> + + <p>It is a general belief amongst breeders that the longer any character + has been transmitted by a breed, the more firmly it will continue to be + transmitted. I do not wish to dispute the truth of the proposition, that + inheritance gains strength simply through long continuance, but I doubt + whether it can be proved. In one sense the proposition is little better + than a truism; if any character has remained constant during many + generations, it will obviously be little likely, the conditions of life + remaining the same, to vary during the next generation. So, again, in + improving a breed, if care be taken for a length of time to exclude all + inferior individuals, the breed will obviously tend to become truer, as + it will not have been crossed during many generations by an inferior + animal. We have previously seen, <!-- Page 63 --><span class="pagenum"><a + name="page63"></a>{63}</span>but without being able to assign any cause, + that, when a new character appears, it is occasionally from the first + well fixed, or fluctuates much, or wholly fails to be transmitted. So it + is with the aggregate of slight differences which characterise a new + variety, for some propagate their kind from the first much truer than + others. Even with plants multiplied by bulbs, layers, &c., which may + in one sense be said to form parts of the same individual, it is well + known that certain varieties retain and transmit through successive + bud-generations their newly-acquired characters more truly than others. + In none of these, nor in the following cases, does there appear to be any + relation between the force with which a character is transmissible and + the length of time during which it has already been transmitted. Some + varieties, such as white and yellow hyacinths and white sweet-peas, + transmit their colours more faithfully than do the varieties which have + retained their natural colour. In the Irish family, mentioned in the + twelfth chapter, the peculiar tortoiseshell-like colouring of the eyes + was transmitted far more faithfully than any ordinary colour. Ancon and + Mauchamp sheep and niata cattle, which are all comparatively modern + breeds, exhibit remarkably strong powers of inheritance. Many similar + cases could be adduced.</p> + + <p>As all domesticated animals and cultivated plants have varied, and yet + are descended from aboriginally wild forms, which no doubt had retained + the same character from an immensely remote epoch, we see that scarcely + any degree of antiquity ensures a character being transmitted perfectly + true. In this case, however, it may be said that changed conditions of + life induce certain modifications, and not that the power of inheritance + fails; but in every case of failure, some cause, either internal or + external, must interfere. It will generally be found that the parts in + our domesticated productions which have varied, or which still continue + to vary,—that is, which fail to retain their primordial + state,—are the same with the parts which differ in the natural + species of the same genus. As, on the theory of descent with + modification, the species of the same genus have been modified since they + branched off from a common progenitor, it follows that the characters by + which they differ from each other have varied whilst other parts of the + organisation have remained unchanged; and it might be argued that <!-- + Page 64 --><span class="pagenum"><a name="page64"></a>{64}</span>these + same characters now vary under domestication, or fail to be inherited, + owing to their lesser antiquity. But we must believe structures, which + have already varied, would be more liable to go on varying, rather than + structures which during an immense lapse of time have remained unaltered; + and this variation is probably the result of certain relations between + the conditions of life and the organisation, quite independently of the + greater or less antiquity of each particular character.</p> + + <p>Fixedness of character, or the strength of inheritance, has often been + judged of by the preponderance of certain characters in the crossed + offspring between distinct races; but prepotency of transmission here + comes into play, and this, as we shall immediately see, is a very + different consideration from the strength or weakness of inheritance. It + has often been observed<a name="NtA_136" + href="#Nt_136"><sup>[136]</sup></a> that breeds of animals inhabiting + wild and mountainous countries cannot be permanently modified by our + improved breeds; and as these latter are of modern origin, it has been + thought that the greater antiquity of the wilder breeds has been the + cause of their resistance to improvement by crossing; but it is more + probably due to their structure and constitution being better adapted to + the surrounding conditions. When plants are first subjected to culture, + it has been found that, during several generations, they transmit their + characters truly, that is, do not vary, and this has been attributed to + ancient characters being strongly inherited; but it may with equal or + greater probability be consequent on changed conditions of life requiring + a long time for their accumulative action. Notwithstanding these + considerations, it would perhaps be rash to deny that characters become + more strongly fixed the longer they are transmitted; but I believe that + the proposition resolves itself into this,—that all characters of + all kinds, whether new or old, tend to be inherited, and that those which + have already withstood all counteracting influences and been truly + transmitted, will, as a general rule, continue to withstand them, and + consequently be faithfully inherited.</p> + +<p><!-- Page 65 --><span class="pagenum"><a name="page65"></a>{65}</span></p> + +<p class="cenhead"><i>Prepotency in the Transmission of Character.</i></p> + + <p>When individuals distinct enough to be recognised, but of the same + family, or when two well-marked races, or two species, are crossed, the + usual result, as stated in the previous chapter, is, that the offspring + in the first generation are intermediate between their parents, or + resemble one parent in one part and the other parent in another part. But + this is by no means the invariable rule; for in many cases it is found + that certain individuals, races, and species are prepotent in + transmitting their likeness. This subject has been ably discussed by + Prosper Lucas,<a name="NtA_137" href="#Nt_137"><sup>[137]</sup></a> but + is rendered extremely complicated by the prepotency sometimes running + equally in both sexes, and sometimes more strongly in one sex than in the + other; it is likewise complicated by the presence of secondary sexual + characters, which render the comparison of mongrels with their + parent-breeds difficult.</p> + + <p>It would appear that in certain families some one ancestor, and after + him others in the same family, must have had great power in transmitting + their likeness through the male line; for we cannot otherwise understand + how the same features should so often be transmitted after marriages with + various females, as has been the case with the Austrian Emperors, and as, + according to Niebuhr, formerly occurred in certain Roman families with + their mental qualities.<a name="NtA_138" + href="#Nt_138"><sup>[138]</sup></a> The famous bull Favourite is + believed<a name="NtA_139" href="#Nt_139"><sup>[139]</sup></a> to have had + a prepotent influence on the shorthorn race. It has also been observed<a + name="NtA_140" href="#Nt_140"><sup>[140]</sup></a> with English + race-horses that certain mares have generally transmitted their own + character, whilst other mares of equally pure blood have allowed the + character of the sire to prevail.</p> + +<blockquote class="b1n"> + + <p>The truth of the principle of prepotency comes out more clearly when + certain races are crossed. The improved Shorthorns, notwithstanding that + the breed is comparatively modern, are generally acknowledged to possess + great power in impressing their likeness on all other breeds; and it is + chiefly in consequence of this power that they are so highly valued <!-- + Page 66 --><span class="pagenum"><a name="page66"></a>{66}</span>for + exportation.<a name="NtA_141" href="#Nt_141"><sup>[141]</sup></a> Godine + has given a curious case of a ram of a goat-like breed of sheep from the + Cape of Good Hope, which produced offspring hardly to be distinguished + from himself, when crossed with ewes of twelve other breeds. But two of + these half-bred ewes, when put to a merino ram, produced lambs closely + resembling the merino breed. Girou de Buzareingues<a name="NtA_142" + href="#Nt_142"><sup>[142]</sup></a> found that of two races of French + sheep the ewes of one, when crossed during successive generations with + merino rams, yielded up their character far sooner than the ewes of the + other race. Sturm and Girou have given analogous cases with other breeds + of sheep and with cattle, the prepotency running in these cases through + the male side; but I was assured on good authority in South America, that + when niata cattle are crossed with common cattle, though the niata breed + is prepotent whether males or females are used, yet that the prepotency + is strongest through the female line. The Manx cat is tailless and has + long hind legs; Dr. Wilson crossed a male Manx with common cats, and, out + of twenty-three kittens, seventeen were destitute of tails; but when the + female Manx was crossed by common male cats all the kittens had tails, + though they were generally short and imperfect.<a name="NtA_143" + href="#Nt_143"><sup>[143]</sup></a></p> + + <p>In making reciprocal crosses between pouter and fantail pigeons, the + pouter-race seemed to be prepotent through both sexes over the fantail. + But this is probably due to weak power in the fantail rather than to any + unusually strong power in the pouter, for I have observed that barbs also + preponderated over fantails. This weakness of transmission in the + fantail, though the breed is an ancient one, is said<a name="NtA_144" + href="#Nt_144"><sup>[144]</sup></a> to be general; but I have observed + one exception to the rule, namely, in a cross between a fantail and + laugher. The most curious instance known to me of weak power in both + sexes is in the trumpeter pigeon. This breed has been well known for at + least 130 years: it breeds perfectly true, as I have been assured by + those who have long kept many birds: it is characterised by a peculiar + tuft of feathers over the beak, by a crest on the head, by a most + peculiar coo quite unlike that of any other breed, and by much-feathered + feet. I have crossed both sexes with turbits of two sub-breeds, with + almond tumblers, spots, and runts, and reared many mongrels and recrossed + them; and though the crest on the head and feathered feet were inherited + (as is generally the case with most breeds), I have never seen a vestige + of the tuft over the beak or heard the peculiar coo. Boitard and Corbié<a + name="NtA_145" href="#Nt_145"><sup>[145]</sup></a> assert that this is + the invariable result of crossing trumpeters with any other breed: + Neumeister,<a name="NtA_146" href="#Nt_146"><sup>[146]</sup></a> however, + states that in Germany mongrels have been obtained, though very rarely, + which were furnished with the tuft and would trumpet: but a pair of these + mongrels with a tuft, which I imported, never trumpeted. Mr. Brent + states<a name="NtA_147" href="#Nt_147"><sup>[147]</sup></a> that the + crossed offspring of a trumpeter were crossed <!-- Page 67 --><span + class="pagenum"><a name="page67"></a>{67}</span>with trumpeters for three + generations, by which time the mongrels had 7-8ths of this blood in their + veins, yet the tuft over the beak did not appear. At the fourth + generation the tuft appeared, but the birds, though now having 15-16ths + trumpeter's blood, still did not trumpet. This case well shows the wide + difference between inheritance and prepotency; for here we have a + well-established old race which transmits it characters faithfully, but + which, when crossed with any other race, has the feeblest power of + transmitting its two chief characteristic qualities.</p> + + <p>I will give one other instance with fowls and pigeons of weakness and + strength in the transmission of the same character to their crossed + offspring. The Silk-fowl breeds true, and there is reason to believe is a + very ancient race; but when I reared a large number of mongrels from a + Silk-hen by a Spanish cock, not one exhibited even a trace of the + so-called silkiness. Mr. Hewitt also asserts that in no instance are the + silky feathers transmitted by this breed when crossed with any other + variety. But three birds out of many raised by Mr. Orton from a cross + between a silk-cock and a bantam-hen, had silky feathers.<a + name="NtA_148" href="#Nt_148"><sup>[148]</sup></a> So that it is certain + that this breed very seldom has the power of transmitting its peculiar + plumage to its crossed progeny. On the other hand, there is a silk + sub-variety of the fantail pigeon, which has its feathers in nearly the + same state as in the Silk-fowl: now we have already seen that fantails, + when crossed, possess singularly weak power in transmitting their general + qualities; but the silk sub-variety when crossed with any other + small-sized race invariably transmits its silky feathers!<a + name="NtA_149" href="#Nt_149"><sup>[149]</sup></a></p> + + <p>The law of prepotency comes into action when species are crossed, as + with races and individuals. Gärtner has unequivocally shown<a + name="NtA_150" href="#Nt_150"><sup>[150]</sup></a> that this is the case + with plants. To give one instance: when <i>Nicotiana paniculata</i> and + <i>vincæflora</i> are crossed, the character of <i>N. paniculata</i> is + almost completely lost in the hybrid; but if <i>N. quadrivalvis</i> be + crossed with <i>N. vincæflora</i>, this later species, which was before + so prepotent, now in its turn almost disappears under the power of <i>N. + quadrivalvis</i>. It is remarkable that the prepotency of one species + over another in transmission is quite independent, as shown by Gärtner, + of the greater or less facility with which the one fertilises the + other.</p> + + <p>With animals, the jackal is prepotent over the dog, as is stated by + Flourens who made many crosses between these animals; and this was + likewise the case with a hybrid which I once saw between a jackal and + terrier. I cannot doubt, from the observations of Colin and others, that + the ass is prepotent over the horse; the prepotency in this instance + running more strongly through the male than through the female ass; so + that the mule resembles the ass more closely than does the hinny.<a + name="NtA_151" href="#Nt_151"><sup>[151]</sup></a> The <!-- Page 68 + --><span class="pagenum"><a name="page68"></a>{68}</span>male pheasant, + judging from Mr. Hewitt's descriptions,<a name="NtA_152" + href="#Nt_152"><sup>[152]</sup></a> and from the hybrids which I have + seen, preponderates over the domestic fowl; but the latter, as far as + colour is concerned, has considerable power of transmission, for hybrids + raised from five differently coloured hens differed greatly in plumage. I + formerly examined some curious hybrids in the Zoological Gardens, between + the Penguin variety of the common duck and the Egyptian goose (<i>Tadorna + Ægyptiaca</i>); and although I will not assert that the domesticated + variety preponderated over the natural species, yet it had strongly + impressed its unnatural upright figure on these hybrids.</p> + + <p>I am aware that such cases as the foregoing have been ascribed by + various authors, not to one species, race, or individual being prepotent + over the other in impressing it character on its crossed offspring, but + to such rules as that the father influences the external characters and + the mother the internal or vital organs. But the great diversity of the + rules given by various authors almost proves their falseness. Dr. Prosper + Lucas has fully discussed this point, and has shown<a name="NtA_153" + href="#Nt_153"><sup>[153]</sup></a> that none of the rules (and I could + add others to those quoted by him) apply to all animals. Similar rules + have been enounced for plants, and have been proved by Gärtner<a + name="NtA_154" href="#Nt_154"><sup>[154]</sup></a> to be all erroneous. + If we confine our view to the domesticated races of a single species, or + perhaps even to the species of the same genus, some such rules may hold + good; for instance, it seems that in reciprocally crossing various breeds + of fowls the male generally gives colour;<a name="NtA_155" + href="#Nt_155"><sup>[155]</sup></a> but conspicuous exceptions have + passed under my own eyes. In sheep it seems that the ram usually gives + its peculiar horns and fleece to its crossed offspring, and the bull the + presence or absence of horns.</p> + + <p>In the following chapter on Crossing I shall have occasion to show + that certain characters are rarely or never blended by crossing, but are + <!-- Page 69 --><span class="pagenum"><a + name="page69"></a>{69}</span>transmitted in an unmodified state from + either parent-form; I refer to this fact here because it is sometimes + accompanied on the one side by prepotency, which thus acquires the false + appearance of unusual strength. In the same chapter I shall show that the + rate at which a species or breed absorbs and obliterates another by + repeated crosses, depends in chief part on prepotency in + transmission.</p> + +</blockquote> + + <p>In conclusion, some of the cases above given,—for instance, that + of the trumpeter pigeon,—prove that there is a wide difference + between mere inheritance and prepotency. This latter power seems to us, + in our ignorance, to act in most cases quite capriciously. The very same + character, even though it be an abnormal or monstrous one, such as silky + feathers, may be transmitted by different species, when crossed, either + with prepotent force or singular feebleness. It is obvious, that a + purely-bred form of either sex, in all cases in which prepotency does not + run more strongly in one sex than the other, will transmit its character + with prepotent force over a mongrelized and already variable form.<a + name="NtA_156" href="#Nt_156"><sup>[156]</sup></a> From several of the + above-given cases we may conclude that mere antiquity of character does + not by any means necessarily make it prepotent. In some cases prepotency + apparently depends on the same character being present and visible in one + of the two breeds which are crossed, and latent or invisible in the other + breed; and in this case it is natural that the character which is + potentially present in both should be prepotent. Thus, we have reason to + believe that there is a latent tendency in all horses to be dun-coloured + and striped; and when a horse of this kind is crossed with one of any + other colour, it is said that the offspring are almost sure to be + striped. Sheep have a similar latent tendency to become dark-coloured, + and we have seen with what prepotent force a ram with a few black spots, + when crossed with sheep of various breeds, coloured its offspring. All + pigeons have a latent tendency to become slaty-blue, with certain + characteristic marks, and it is known that, when a bird thus coloured is + crossed with one of any other colour, it is most difficult afterwards to + eradicate the blue tint. A nearly parallel case is offered by those black + bantams which, as they grow <!-- Page 70 --><span class="pagenum"><a + name="page70"></a>{70}</span>old, develop a latent tendency to acquire + red feathers. But there are exceptions to the rule: hornless breeds of + cattle possess a latent capacity to reproduce horns, yet when crossed + with horned breeds they do not invariably produce offspring bearing + horns.</p> + + <p>We meet with analogous cases with plants. Striped flowers, though they + can be propagated truly by seed, have a latent tendency to become + uniformly coloured, but when once crossed by a uniformly coloured + variety, they ever afterwards fail to produce striped seedlings.<a + name="NtA_157" href="#Nt_157"><sup>[157]</sup></a> Another case is in + some respects more curious: plants bearing peloric or regular flowers + have so strong a latent tendency to reproduce their normally irregular + flowers, that this often occurs by buds when a plant is transplanted into + poorer or richer soil.<a name="NtA_158" + href="#Nt_158"><sup>[158]</sup></a> Now I crossed the peloric snapdragon + (<i>Antirrhinum majus</i>), described in the last chapter, with pollen of + the common form; and the latter, reciprocally, with peloric pollen. I + thus raised two great beds of seedlings, and not one was peloric. + Naudin<a name="NtA_159" href="#Nt_159"><sup>[159]</sup></a> obtained the + same result from crossing a peloric Linaria with the common form. I + carefully examined the flowers of ninety plants of the crossed + Antirrhinum in the two beds, and their structure had not been in the + least affected by the cross, except that in a few instances the minute + rudiment of the fifth stamen, which is always present, was more fully or + even completely developed. It must not be supposed that this entire + obliteration of the peloric structure in the crossed plants can be + accounted for by any incapacity of transmission; for I raised a large bed + of plants from the peloric Antirrhinum, artificially fertilised by its + own pollen, and sixteen plants, which alone survived the winter, were all + as perfectly peloric as the parent-plant. Here we have a good instance of + the wide difference between the inheritance of a character and the power + of transmitting it to crossed offspring. The crossed plants, which + perfectly resembled the common snapdragon, were allowed to sow + themselves, and, out of a hundred and twenty-seven seedlings, + eighty-eight proved to be common snapdragons, two were in an intermediate + condition between the peloric and normal state, <!-- Page 71 --><span + class="pagenum"><a name="page71"></a>{71}</span>and thirty-seven were + perfectly peloric, having reverted to the structure of their one + grandparent. This case seems at first sight to offer an exception to the + rule formerly given, namely, that a character which is present in one + form and latent in the other is generally transmitted with prepotent + force when the two forms are crossed. For in all the Scrophulariaceæ, and + especially in the genera Antirrhinum and Linaria, there is, as was shown + in the last chapter, a strong latent tendency to become peloric; and + there is also, as we have just seen, a still stronger tendency in all + peloric plants to reacquire their normal irregular structure. So that we + have two opposed latent tendencies in the same plants. Now, with the + crossed Antirrhinums the tendency to produce normal or irregular flowers, + like those of the common Snapdragon, prevailed in the first generation; + whilst the tendency to pelorism, appearing to gain strength by the + intermission of a generation, prevailed to a large extent in the second + set of seedlings. How it is possible for a character to gain strength by + the intermission of a generation, will be considered in the chapter on + pangenesis.</p> + + <p>On the whole, the subject of prepotency is extremely + intricate,—from its varying so much in strength, even in regard to + the same character, in different animals,—from its running either + equally in both sexes, or, as frequently is the case with animals, but + not with plants, much stronger in the one sex than the other,—from + the existence of secondary sexual characters,—from the transmission + of certain characters being limited, as we shall immediately see, by + sex,—from certain characters not blending together,—and, + perhaps, occasionally from the effects of a previous fertilisation on the + mother. It is therefore not surprising that every one hitherto has been + baffled in drawing up general rules on the subject of prepotency.</p> + +<p class="cenhead"><i>Inheritance as limited by Sex.</i></p> + + <p>New characters often appear in one sex, and are afterwards transmitted + to the same sex, either exclusively or in a much greater degree than to + the other. This subject is important, because with animals of many kinds + in a state of nature, both high and low in the scale, secondary sexual + characters, not in <!-- Page 72 --><span class="pagenum"><a + name="page72"></a>{72}</span>any way directly connected with the organs + of reproduction, are often conspicuously present. With our domesticated + animals, also, these same secondary characters are often found to differ + greatly from the state in which they exist in the parent-species. And the + principle of inheritance as limited by sex shows how such characters + might have been first acquired and subsequently modified.</p> + +<blockquote class="b1n"> + + <p>Dr. P. Lucas, who has collected many facts on this subject, shows<a + name="NtA_160" href="#Nt_160"><sup>[160]</sup></a> that when a + peculiarity, in no manner connected with the reproductive organs, appears + in either parent, it is often transmitted exclusively to the offspring of + the same sex, or to a much greater number of them than of the opposite + sex. Thus, in the family of Lambert, the horn-like projections on the + skin were transmitted from the father to his sons and grandsons alone; so + it has been with other cases of ichthyosis, with supernumerary digits, + with a deficiency of digits and phalanges, and in a lesser degree with + various diseases, especially with colour-blindness, and a hæmorrhagic + diathesis, that is, an extreme liability to profuse and uncontrollable + bleeding from trifling wounds. On the other hand, mothers have + transmitted, during several generations, to their daughters alone, + supernumerary and deficient digits, colour-blindness, and other + peculiarities. So that we see that the very same peculiarity may become + attached to either sex, and be long inherited by that sex alone; but the + attachment in certain cases is much more frequent to one than the other + sex. The same peculiarities also may be promiscuously transmitted to + either sex. Dr. Lucas gives other cases, showing that the male + occasionally transmits his peculiarities to his daughters alone, and the + mother to her sons alone; but even in this case we see that inheritance + is to a certain extent, though inversely, regulated by sex. Dr. Lucas, + after weighing the whole evidence, comes to the conclusion that every + peculiarity, according to the sex in which it first appears, tends to be + transmitted in a greater or lesser degree to that sex.</p> + + <p>A few details from the many cases collected by Mr. Sedgwick,<a + name="NtA_161" href="#Nt_161"><sup>[161]</sup></a> may be here given. + Colour-blindness, from some unknown cause, shows itself much oftener in + males than in females; in upwards of two hundred cases collected by Mr. + Sedgwick, nine-tenths related to men; but it is eminently liable to be + transmitted through women. In the case given by Dr. Earle, members of + eight related families were affected during five generations: these + families consisted of sixty-one individuals, namely, of thirty-two males, + of whom nine-sixteenths were incapable of distinguishing colour, and of + twenty-nine females, of whom only one-fifteenth were thus affected. <!-- + Page 73 --><span class="pagenum"><a name="page73"></a>{73}</span>Although + colour-blindness thus generally clings to the male sex, nevertheless, in + one instance in which it first appeared in a female, it was transmitted + during five generations to thirteen individuals, all of whom were + females. A hæmorrhagic diathesis, often accompanied by rheumatism, has + been known to affect the males alone during five generations, being + transmitted, however, through the females. It is said that deficient + phalanges in the fingers have been inherited by the females alone during + ten generations. In another case, a man thus deficient in both hands and + feet, transmitted the peculiarity to his two sons and one daughter; but + in the third generation, out of nineteen grandchildren, twelve sons had + the family defect, whilst the seven daughters were free. In ordinary + cases of sexual limitation, the sons or daughters inherit the + peculiarity, whatever it may be, from their father or mother, and + transmit it to their children of the same sex; but generally with the + hæmorrhagic diathesis, and often with colour-blindness, and in some other + cases, the sons never inherit the peculiarity directly from their + fathers, but the daughters, and the daughters alone, transmit the latent + tendency, so that the sons of the daughters alone exhibit it. Thus, the + father, grandson, and great-great-grandson will exhibit a + peculiarity,—the grandmother, daughter, and great-granddaughter + having transmitted it in a latent state. Hence we have, as Mr. Sedgwick + remarks, a double kind of atavism or reversion; each grandson apparently + receiving and developing the peculiarity from his grandfather, and each + daughter apparently receiving the latent tendency from her + grandmother.</p> + + <p>From the various facts recorded by Dr. Prosper Lucas, Mr. Sedgwick, + and others, there can be no doubt that peculiarities first appearing in + either sex, though not in any way necessarily or invariably connected + with that sex, strongly tend to be inherited by the offspring of the same + sex, but are often transmitted in a latent state through the opposite + sex.</p> + + <p>Turning now to domesticated animals, we find that certain characters + not proper to the parent-species are often confined to, and inherited by, + one sex alone; but we do not know the history of the first appearance of + such characters. In the chapter on Sheep, we have seen that the males of + certain races differ greatly from the females in the shape of their + horns, these being absent in the ewes of some breeds, in the development + of fat in the tail in certain fat-tailed breeds, and in the outline of + the forehead. These differences, judging from the character of the allied + wild species, cannot be accounted for by supposing that they have been + derived from distinct parent-forms. There is, also, a great difference + between the horns of the two sexes in one Indian breed of goats. The bull + zebu is said to have a larger hump than the cow. In the Scotch deer-hound + the two sexes differ in size more than in any other variety of the dog,<a + name="NtA_162" href="#Nt_162"><sup>[162]</sup></a> and, judging from + analogy, more than in the aboriginal parent-species. The peculiar colour + called tortoise-shell is very rarely seen in a male cat; the males of + this variety being of a rusty tint. A tendency to baldness in man before + the advent of old age is certainly inherited; and in the European, or at + least in the <!-- Page 74 --><span class="pagenum"><a + name="page74"></a>{74}</span>Englishman, is an attribute of the male sex, + and may almost be ranked as an incipient secondary sexual character.</p> + + <p>In various breeds of the fowl the males and females often differ + greatly; and these differences are far from being the same with those + which distinguish the two sexes in the parent-species, the <i>Gallus + bankiva</i>; and consequently have originated under domestication. In + certain sub-varieties of the Game race we have the unusual case of the + hens differing from each other more than the cocks. In an Indian breed of + a white colour stained with soot, the hens invariably have black skins, + and their bones are covered by a black periosteum, whilst the cocks are + never or most rarely thus characterised. Pigeons offer a more interesting + case; for the two sexes rarely differ throughout the whole great family, + and the males and females of the parent-form, the <i>C. livia</i>, are + undistinguishable; yet we have seen that with Pouters the male has the + characteristic quality of pouting more strongly developed than the + female; and in certain sub-varieties<a name="NtA_163" + href="#Nt_163"><sup>[163]</sup></a> the males alone are spotted or + striated with black. When male and female English carrier-pigeons are + exhibited in separate pens, the difference in the development of the + wattle over the beak and round the eyes is conspicuous. So that here we + have instances of the appearance of secondary sexual characters in the + domesticated races of a species in which such differences are naturally + quite absent.</p> + +</blockquote> + + <p>On the other hand, secondary sexual characters which properly belong + to the species are sometimes quite lost, or greatly diminished, under + domestication. We see this in the small size of the tusks in our improved + breeds of the pig, in comparison with those of the wild boar. There are + sub-breeds of fowls in which the males have lost the fine flowing + tail-feathers and hackles; and others in which there is no difference in + colour between the two sexes. In some cases the barred plumage, which in + gallinaceous birds is commonly the attribute of the hen, has been + transferred to the cock, as in the cuckoo sub-breeds. In other cases + masculine characters have been partly transferred to the female, as with + the splendid plumage of the golden-spangled Hamburgh hen, the enlarged + comb of the Spanish hen, the pugnacious disposition of the Game hen, and + as in the well-developed spurs which occasionally appear in the hens of + various breeds. In Polish fowls both sexes are ornamented with a topknot, + that of the male being formed of hackle-like feathers, and this is a new + male character in the genus Gallus. On the whole, as far as I can judge, + new characters are more apt <!-- Page 75 --><span class="pagenum"><a + name="page75"></a>{75}</span>to appear in the males of our domesticated + animals than in the females, and afterwards to be either exclusively or + more strongly inherited by the males. Finally, in accordance with the + principle of inheritance as limited by sex, the appearance of secondary + sexual characters in natural species offers no especial difficulty, and + their subsequent increase and modification, if of any service to the + species, would follow through that form of selection which in my 'Origin + of Species' I have called sexual selection.</p> + +<p class="cenhead"><i>Inheritance at corresponding periods of Life.</i></p> + + <p>This is an important subject. Since the publication of my 'Origin of + Species,' I have seen no reason to doubt the truth of the explanation + there given of perhaps the most remarkable of all the facts in biology, + namely, the difference between the embryo and the adult animal. The + explanation is, that variations do not necessarily or generally occur at + a very early period of embryonic growth, and that such variations are + inherited at a corresponding age. As a consequence of this the embryo, + even when the parent-form undergoes a great amount of modification, is + left only slightly modified; and the embryos of widely-different animals + which are descended from a common progenitor remain in many important + respects like each other and their common progenitor. We can thus + understand why embryology should throw a flood of light on the natural + system of classification, for this ought to be as far as possible + genealogical. When the embryo leads an independent life, that is, becomes + a larva, it has to be adapted to the surrounding conditions in its + structure and instincts, independently of those of its parents; and the + principle of inheritance at corresponding periods of life renders this + possible.</p> + + <p>This principle is, indeed, in one way so obvious that it escapes + attention. We possess a number of races of animals and plants, which, + when compared with each other and with their parent-forms, present + conspicuous differences, both in the immature and mature states. Look at + the seeds of the several kinds of peas, beans, maize, which can be + propagated truly, and see how they differ in size, colour, and shape, + whilst the <!-- Page 76 --><span class="pagenum"><a + name="page76"></a>{76}</span>full-grown plants differ but little. + Cabbages on the other hand differ greatly in foliage and manner of + growth, but hardly at all in their seeds; and generally it will be found + that the differences between cultivated plants at different periods of + growth are not necessarily closely connected together, for plants may + differ much in their seeds and little when full-grown, and conversely may + yield seeds hardly distinguishable, yet differ much when full-grown. In + the several breeds of poultry, descended from a single species, + differences in the eggs and chickens, in the plumage at the first and + subsequent moults, in the comb and wattles during maturity, are all + inherited. With man peculiarities in the milk and second teeth, of which + I have received the details, are inheritable, and with man longevity is + often transmitted. So again with our improved breeds of cattle and sheep, + early maturity, including the early development of the teeth, and with + certain breeds of fowl the early appearance of secondary sexual + characters, all come under the same head of inheritance at corresponding + periods.</p> + + <p>Numerous analogous facts could be given. The silk-moth, perhaps, + offers the best instance; for in the breeds which transmit their + characters truly, the eggs differ in size, colour, and shape;—the + caterpillars differ, in moulting three or four times, in colour, even in + having a dark-coloured mark like an eyebrow, and in the loss of certain + instincts;—the cocoons differ in size, shape, and in the colour and + quality of the silk; these several differences being followed by slight + or barely distinguishable differences in the mature moth.</p> + + <p>But it may be said that, if in the above cases a new peculiarity is + inherited, it must be at the corresponding stage of development; for an + egg or seed can resemble only an egg or seed, and the horn in a + full-grown ox can resemble only a horn. The following cases show + inheritance at corresponding periods more plainly, because they refer to + peculiarities which might have supervened, as far as we can see, earlier + or later in life, yet are inherited at the same period at which they + first appeared.</p> + +<blockquote class="b1n"> + + <p>In the Lambert family the porcupine-like excrescences appeared in the + father and sons at the same age, namely, about nine weeks after <!-- Page + 77 --><span class="pagenum"><a name="page77"></a>{77}</span>birth.<a + name="NtA_164" href="#Nt_164"><sup>[164]</sup></a> In the extraordinary + hairy family described by Mr. Crawfurd,<a name="NtA_165" + href="#Nt_165"><sup>[165]</sup></a> children were produced during three + generations with hairy ears; in the father the hair began to grow over + his body at six years old; in his daughter somewhat earlier, namely, at + one year; and in both generations the milk teeth appeared late in life, + the permanent teeth being afterwards singularly deficient. Greyness of + hair at an unusually early age has been transmitted in some families. + These cases border on diseases inherited at corresponding periods of + life, to which I shall immediately refer.</p> + + <p>It is a well-known peculiarity with almond-tumbler pigeons, that the + full beauty and peculiar character of the plumage does not appear until + the bird has moulted two or three times. Neumeister describes and figures + a breed of pigeons in which the whole body is white except the breast, + neck, and head; but before the first moult all the white feathers acquire + coloured edges. Another breed is more remarkable: its first plumage is + black, with rusty-red wing-bars and a crescent-shaped mark on the breast; + these marks then became white, and remain so during three or four moults; + but after this period the white spreads over the body, and the bird loses + its beauty.<a name="NtA_166" href="#Nt_166"><sup>[166]</sup></a> Prize + canary-birds have their wings and tail black: "this colour, however, is + only retained until the first moult, so that they must be exhibited ere + the change takes place. Once moulted, the peculiarity has ceased. Of + course all the birds emanating from this stock have black wings and tails + the first year."<a name="NtA_167" href="#Nt_167"><sup>[167]</sup></a> A + curious and somewhat analogous account has been given<a name="NtA_168" + href="#Nt_168"><sup>[168]</sup></a> of a family of wild pied rooks which + were first observed in 1798, near Chalfont, and which every year from + that date up to the period of the published notice, viz. 1837, "have + several of their brood particoloured, black and white. This variegation + of the plumage, however, disappears with the first moult; but among the + next young families there are always a few pied ones." These changes of + plumage, which appear and are inherited at various corresponding periods + of life in the pigeon, canary-bird, and rook, are remarkable, because the + parent-species undergo no such change.</p> + + <p>Inherited diseases afford evidence in some respects of less value than + the foregoing cases, because diseases are not necessarily connected with + any change in structure; but in other respects of more value, because the + periods have been more carefully observed. Certain diseases are + communicated to the child apparently by a process like inoculation, and + the child is from the first affected; such cases may be here passed over. + Large classes of diseases usually appear at certain ages, such as St. + Vitus's dance in youth, consumption in early mid-life, gout later, and + apoplexy still later; and these are naturally inherited at the same + period. But even in diseases of this class, instances have been recorded, + as with St. Vitus's <!-- Page 78 --><span class="pagenum"><a + name="page78"></a>{78}</span>dance, showing that an unusually early or + late tendency to the disease is inheritable.<a name="NtA_169" + href="#Nt_169"><sup>[169]</sup></a> In most cases the appearance of any + inherited disease is largely determined by certain critical periods in + each person's life, as well as by unfavourable conditions. There are many + other diseases, which are not attached to any <span class="correction" + title="Original reads `particuliar'.">particular</span> period, but which + certainly tend to appear in the child at about the same age at which the + parent was first attacked. An array of high authorities, ancient and + modern, could be given in support of this proposition. The illustrious + Hunter believed in it; and Piorry<a name="NtA_170" + href="#Nt_170"><sup>[170]</sup></a> cautions the physician to look + closely to the child at the period when any grave inheritable disease + attacked the parent. Dr. Prosper Lucas,<a name="NtA_171" + href="#Nt_171"><sup>[171]</sup></a> after collecting facts from every + source, asserts that affections of all kinds, though not related to any + particular period of life, tend to reappear in the offspring at whatever + period of life they first appeared in the progenitor.</p> + + <p>As the subject is important, it may be well to give a few instances, + simply as illustrations, not as proof; for proof, recourse must be had to + the authorities above quoted. Some of the following cases have been + selected for the sake of showing that, when a slight departure from the + rule occurs, the child is affected somewhat earlier in life than the + parent. In the family of Le Compte blindness was inherited during three + generations, and no less than thirty-seven children and grandchildren + were all affected at about the same age, namely seventeen or eighteen.<a + name="NtA_172" href="#Nt_172"><sup>[172]</sup></a> In another case a + father and his four children all became blind at twenty-one years old; in + another, a grandmother grew blind at thirty-five, her daughter at + nineteen, and three grandchildren at the ages of thirteen and eleven.<a + name="NtA_173" href="#Nt_173"><sup>[173]</sup></a> So with deafness, two + brothers, their father and paternal grandfather, all became deaf at the + age of forty.<a name="NtA_174" href="#Nt_174"><sup>[174]</sup></a></p> + + <p>Esquirol gives several striking instances of insanity coming on at the + same age, as that of a grandfather, father, and son, who all committed + suicide near their fiftieth year. Many other cases could be given, as of + a whole family who became insane at the age of forty.<a name="NtA_175" + href="#Nt_175"><sup>[175]</sup></a> Other cerebral affections sometimes + follow the same rule,—for instance, epilepsy and apoplexy. A woman + died of the latter disease when sixty-three years old; one of her + daughters at forty-three, and the other at sixty-seven: the latter had + twelve children, who all died from tubercular meningitis.<a + name="NtA_176" href="#Nt_176"><sup>[176]</sup></a> I mention this latter + case because it illustrates a frequent occurrence, namely, a change in + the precise nature of an inherited disease, though still affecting the + same organ.</p> + +<p><!-- Page 79 --><span class="pagenum"><a name="page79"></a>{79}</span></p> + + <p>Asthma has attacked several members of the same family when forty + years old, and other families during infancy. The most different + diseases, as angina pectoris, stone in the bladder, and various + affections of the skin, have appeared in successive generations at nearly + the same age. The little finger of a man began from some unknown cause to + grow inwards, and the same finger in his two sons began at the same age + to bend inwards in a similar manner. Strange and inexplicable neuralgic + affections have caused parents and children to suffer agonies at about + the same period of life.<a name="NtA_177" + href="#Nt_177"><sup>[177]</sup></a></p> + + <p>I will give only two other cases, which are interesting as + illustrating the disappearance as well as the appearance of disease at + the same age. Two brothers, their father, their paternal uncles, seven + cousins, and their paternal grandfather, were all similarly affected by a + skin-disease, called pityriasis versicolor; "the disease, strictly + limited to the males of the family (though transmitted through the + females), usually appeared at puberty, and disappeared at about the age + of forty or forty-five years." The second case is that of four brothers, + who when about twelve years old suffered almost every week from severe + headaches, which were relieved only by a recumbent position in a dark + room. Their father, paternal uncles, paternal grandfather, and paternal + granduncles all suffered in the same way from headaches, which ceased at + the age of fifty-four or fifty-five in all those who lived so long. None + of the females of the family were affected.<a name="NtA_178" + href="#Nt_178"><sup>[178]</sup></a></p> + +</blockquote> + + <p>It is impossible to read the foregoing accounts, and the many others + which have been recorded, of diseases coming on during three or even more + generations, at the same age in several members of the same family, + especially in the case of rare affections in which the coincidence cannot + be attributed to chance, and doubt that there is a strong tendency to + inheritance in disease at corresponding periods of life. When the rule + fails, the disease is apt to come on earlier in the child than in the + parent; the exceptions in the other direction being vey much rarer. Dr. + Lucas<a name="NtA_179" href="#Nt_179"><sup>[179]</sup></a> alludes to + several cases of inherited diseases coming on at an earlier period. I + have already given one striking instance with blindness during three + generations; and Mr. Bowman remarks that this frequently occurs with + cataract. With cancer there seems to be a peculiar liability to earlier + inheritance: Mr. Paget, who has particularly <!-- Page 80 --><span + class="pagenum"><a name="page80"></a>{80}</span>attended to this subject, + and tabulated a large number of cases, informs me that he believes that + in nine cases out of ten the later generation suffers from the disease at + an earlier period than the previous generation. He adds, "In the + instances in which the opposite relation holds, and the members of later + generations have cancer at a later age than their predecessors, I think + it will be found that the non-cancerous parents have lived to extreme old + ages." So that the longevity of a non-affected parent seems to have the + power of determining in the offspring the fatal period; and we thus + apparently get another element of complexity in inheritance.</p> + + <p>The facts, showing that with certain diseases the period of + inheritance occasionally or even frequently advances, are important with + respect to the general descent-theory, for they render it in some degree + probable that the same thing would occur with ordinary modifications of + structure. The final result of a long series of such advances would be + the gradual obliteration of characters proper to the embryo and larva, + which would thus come to resemble more and more closely the mature + parent-form. But any structure which was of service to the embryo or + larva would be preserved by the destruction at this stage of growth of + each individual which manifested any tendency to lose at too early an age + its own proper character.</p> + + <p>Finally, from the numerous races of cultivated plants and domestic + animals, in which the seed or eggs, the young or old, differ from each + other and from their parent-species;—from the cases in which new + characters have appeared at a particular period, and afterwards have been + inherited at the same period;—and from what we know with respect to + disease, we must believe in the truth of the great principle of + inheritance at corresponding periods of life.</p> + +<hr class="short" /> + + <p><i>Summary of the three preceding Chapters.</i>—Strong as is the + force of inheritance, it allows the incessant appearance of new + characters. These, whether beneficial or injurious, of the most trifling + importance, such as a shade of colour in a flower, a coloured lock of + hair, or a mere gesture; or of the highest importance, as when affecting + the brain or an organ so perfect <!-- Page 81 --><span class="pagenum"><a + name="page81"></a>{81}</span>and complex as the eye; or of so grave a + nature as to deserve to be called a monstrosity, or so peculiar as not to + occur normally in any member of the same natural class, are all sometimes + strongly inherited by man, the lower animals, and plants. In numberless + cases it suffices for the inheritance of a peculiarity that one parent + alone should be thus characterised. Inequalities in the two sides of the + body, though opposed to the law of symmetry, may be transmitted. There is + a considerable body of evidence showing that even mutilations, and the + effects of accidents, especially or perhaps exclusively when followed by + disease, are occasionally inherited. There can be no doubt that the evil + effects of long-continued exposure in the parent to injurious conditions + are sometimes transmitted to the offspring. So it is, as we shall see in + a future chapter, with the effects of the use and disuse of parts, and of + mental habits. Periodical habits are likewise transmitted, but generally, + as it would appear, with little force.</p> + + <p>Hence we are led to look at inheritance as the rule, and + non-inheritance as the anomaly. But this power often appears to us in our + ignorance to act capriciously, transmitting a character with inexplicable + strength or feebleness. The very same peculiarity, as the weeping habit + of trees, silky-feathers, &c., may be inherited either firmly or not + at all by different members of the same group, and even by different + individuals of the same species, though treated in the same manner. In + this latter case we see that the power of transmission is a quality which + is merely individual in its attachment. As with single characters, so it + is with the several concurrent slight differences which distinguish + sub-varieties or races; for of these, some can be propagated almost as + truly as species, whilst others cannot be relied on. The same rule holds + good with plants, when propagated by bulbs, offsets, &c., which in + one sense still form parts of the same individual, for some varieties + retain or inherit through successive bud-generations their character far + more truly than others.</p> + + <p>Some characters not proper to the parent-species have certainly been + inherited from an extremely remote epoch, and may therefore be considered + as firmly fixed. But it is doubtful whether length of inheritance in + itself gives fixedness of character; <!-- Page 82 --><span + class="pagenum"><a name="page82"></a>{82}</span>though the chances are + obviously in favour of any character which has long been transmitted true + or unaltered, still being transmitted true as long as the conditions of + life remain the same. We know that many species, after having retained + the same character for countless ages, whilst living under their natural + conditions, when domesticated have varied in the most diversified manner, + that is, have failed to transmit their original form; so that no + character appears to be absolutely fixed. We can sometimes account for + the failure of inheritance by the conditions of life being opposed to the + development of certain characters; and still oftener, as with plants + cultivated by grafts and buds, by the conditions causing new and slight + modifications incessantly to appear. In this latter case it is not that + inheritance wholly fails, but that new characters are continually + superadded. In some few cases, in which both parents are similarly + characterised, inheritance seems to gain so much force by the combined + action of the two parents, that it counteracts its own power, and a new + modification is the result.</p> + + <p>In many cases the failure of the parents to transmit their likeness is + due to the breed having been at some former period crossed; and the child + takes after his grandparent or more remote ancestor of foreign blood. In + other cases, in which the breed has not been crossed, but some ancient + character has been lost through variation, it occasionally reappears + through reversion, so that the parents apparently fail to transmit their + own likeness. In all cases, however, we may safely conclude that the + child inherits all its characters from its parents, in whom certain + characters are latent, like the secondary sexual characters of one sex in + the other. When, after a long succession of bud-generations, a flower or + fruit becomes separated into distinct segments, having the colours or + other attributes of both parent-forms, we cannot doubt that these + characters were latent in the earlier buds, though they could not then be + detected, or could be detected only in an intimately commingled state. So + it is with animals of crossed parentage, which with advancing years + occasionally exhibit characters derived from one of their two parents, of + which not a trace could at first be perceived. Certain monstrosities, + which resemble what naturalists call the typical form of the group in + question, <!-- Page 83 --><span class="pagenum"><a + name="page83"></a>{83}</span>apparently come under the same law of + reversion. It is assuredly an astonishing fact that the male and female + sexual elements, that buds, and even full-grown animals, should retain + characters, during several generations in the case of crossed breeds, and + during thousands of generations in the case of pure breeds, written as it + were in invisible ink, yet ready at any time to be evolved under the + requisite conditions.</p> + + <p>What these conditions are, we do not in many cases at all know. But + the act of crossing in itself, apparently from causing some disturbance + in the organisation, certainly gives a strong tendency to the + reappearance of long-lost characters, both corporeal and mental, + independently of those derived from the cross. A return of any species to + its natural conditions of life, as with feral animals and plants, favours + reversion; though it is certain that this tendency exists, we do not know + how far it prevails, and it has been much exaggerated. On the other hand, + the crossed offspring of plants which have had their organisation + disturbed by cultivation, are more liable to reversion than the crossed + offspring of species which have always lived under their natural + conditions.</p> + + <p>When distinguishable individuals of the same family, or races, or + species are crossed, we see that the one is often prepotent over the + other in transmitting its own character. A race may possess a strong + power of inheritance, and yet when crossed, as we have seen with + trumpeter-pigeons, yield to the prepotency of every other race. + Prepotentcy of transmission may be equal in the two sexes of the same + species, but often runs more strongly in one sex. It plays an important + part in determining the rate at which one race can be modified or wholly + absorbed by repeated crosses with another. We can seldom tell what makes + one race or species prepotent over another; but it sometimes depends on + the same character being present and visible in one parent, and latent or + potentially present in the other.</p> + + <p>Characters may first appear in either sex, but oftener in the male + than in the female, and afterwards be transmitted to the offspring of the + same sex. In this case we may feel confident that the peculiarity in + question is really present though latent in the opposite sex; hence the + father may transmit through his daughter any character to his grandson; + and the mother <!-- Page 84 --><span class="pagenum"><a + name="page84"></a>{84}</span>conversely to her granddaughter. We thus + learn, and the fact is an important one, that transmission and + development are distinct powers. Occasionally these two powers seem to be + antagonistic, or incapable of combination in the same individual; for + several cases have been recorded in which the son has not directly + inherited a character from his father, or directly transmitted it to his + son, but has received it by transmission through his non-affected mother, + and transmitted it through his non-affected daughter. Owing to + inheritance being limited by sex, we can see how secondary sexual + characters may first have arisen under nature; their preservation and + accumulation being dependent on their service to either sex.</p> + + <p>At whatever period of life a new character first appears, it generally + remains latent in the offspring until a corresponding age is attained, + and then it is developed. When this rule fails, the child generally + exhibits the character at an earlier period than the parent. On this + principle of inheritance at corresponding periods, we can understand how + it is that most animals display from the germ to maturity such a + marvellous succession of characters.</p> + + <p>Finally, though much remains obscure with respect to Inheritance, we + may look at the following laws as fairly well established. Firstly, a + tendency in every character, new and old, to be transmitted by seminal + and bud generation, though often counteracted by various known and + unknown causes. Secondly, reversion or atavism, which depends on + transmission and development being distinct powers: it acts in various + degrees and manners through both seminal and bud generation. Thirdly, + prepotency of transmission, which may be confined to one sex, or be + common to both sexes of the prepotent form. Fourthly, transmission, + limited by sex, generally to the same sex in which the inherited + character first appeared. Fifthly, inheritance at corresponding periods + of life, with some tendency to the earlier development of the inherited + character. In these laws of Inheritance, as displayed under + domestication, we see an ample provision for the production, through + variability and natural selection, of new specific forms.</p> + +<hr class="full" /> + +<p><!-- Page 85 --><span class="pagenum"><a name="page85"></a>{85}</span></p> + +<h3>CHAPTER XV.</h3> + +<p class="cenhead">ON CROSSING.</p> + +<blockquote class="b1n"> + + <p><span class="scac">FREE INTERCROSSING OBLITERATES THE DIFFERENCES + BETWEEN ALLIED BREEDS</span>—<span class="scac">WHEN THE NUMBERS OF + TWO COMMINGLING BREEDS ARE UNEQUAL, ONE ABSORBS THE + OTHER</span>—<span class="scac">THE RATE OF ABSORPTION DETERMINED + BY PREPOTENCY OF TRANSMISSION, BY THE CONDITIONS OF LIFE, AND BY NATURAL + SELECTION</span>—<span class="scac">ALL ORGANIC BEINGS OCCASIONALLY + INTERCROSS; APPARENT EXCEPTIONS</span>—<span class="scac">ON + CERTAIN CHARACTERS INCAPABLE OF FUSION; CHIEFLY OR EXCLUSIVELY THOSE + WHICH HAVE SUDDENLY APPEARED IN THE INDIVIDUAL</span>—<span + class="scac">ON THE MODIFICATION OF OLD RACES, AND THE FORMATION OF NEW + RACES, BY CROSSING</span>—<span class="scac">SOME CROSSED RACES + HAVE BRED TRUE FROM THEIR FIRST PRODUCTION</span>—<span + class="scac">ON THE CROSSING OF DISTINCT SPECIES IN RELATION TO THE + FORMATION OF DOMESTIC RACES.</span></p> + +</blockquote> + + <p>In the two previous chapters, when discussing reversion and + prepotency, I was necessarily led to give many facts on crossing. In the + present chapter I shall consider the part which crossing plays in two + opposed directions,—firstly, in obliterating characters, and + consequently in preventing the formation of new races; and secondly, in + the modification of old races, or in the formation of new and + intermediate races, by a combination of characters. I shall also show + that certain characters are incapable of fusion.</p> + + <p>The effects of free or uncontrolled breeding between the members of + the same variety or of closely allied varieties are important; but are so + obvious that they need not be discussed at much length. It is free + intercrossing which chiefly gives uniformity, both under nature and under + domestication, to the individuals of the same species or variety, when + they live mingled together and are not exposed to any cause inducing + excessive variability. The prevention of free crossing, and the + intentional matching of individual animals, are the corner-stones of the + breeder's art. No man in his senses would expect to improve or modify a + breed in any particular manner, or keep an old breed true and distinct, + unless he separated his animals. The killing of inferior animals in each + generation comes to the <!-- Page 86 --><span class="pagenum"><a + name="page86"></a>{86}</span>same thing as their separation. In savage + and semi-civilised countries, where the inhabitants have not the means of + separating their animals, more than a single breed of the same species + rarely or never exists. In former times, even in a country so civilised + as North America, there were no distinct races of sheep, for all had been + mingled together.<a name="NtA_180" href="#Nt_180"><sup>[180]</sup></a> + The celebrated agriculturist Marshall<a name="NtA_181" + href="#Nt_181"><sup>[181]</sup></a> remarks that "sheep that are kept + within fences, as well as shepherded flocks in open countries, have + generally a similarity, if not a uniformity, of character in the + individuals of each flock;" for they breed freely together, and are + prevented from crossing with other kinds; whereas in the unenclosed parts + of England the unshepherded sheep, even of the same flock, are far from + true or uniform, owing to various breeds having mingled and crossed. We + have seen that the half-wild cattle in the several British parks are + uniform in character in each; but in the different parks, from not having + mingled and crossed during many generations, they differ in a slight + degree.</p> + + <p>We cannot doubt that the extraordinary number of varieties and + sub-varieties of the pigeon, amounting to at least one hundred and fifty, + is partly due to their remaining, differently from other domesticated + birds, paired for life when once matched. On the other hand, breeds of + cats imported into this country soon disappear, for their nocturnal and + rambling habits render it hardly possible to prevent free crossing. + Rengger<a name="NtA_182" href="#Nt_182"><sup>[182]</sup></a> gives an + interesting case with respect to the cat in Paraguay: in all the distant + parts of the kingdom it has assumed, apparently from the effects of the + climate, a peculiar character, but near the capital this change has been + prevented, owing, as he asserts, to the native animal frequently crossing + with cats imported from Europe. In all cases like the foregoing, the + effects of an occasional cross will be augmented by the increased vigour + and fertility of the crossed offspring, of which fact evidence will + hereafter be given; for this will lead to the mongrels increasing more + rapidly than the pure parent-breeds.</p> + +<p><!-- Page 87 --><span class="pagenum"><a name="page87"></a>{87}</span></p> + + <p>When distinct breeds are allowed to cross freely, the result will be a + heterogenous body; for instance, the dogs in Paraguay are far from + uniform, and can no longer be affiliated to their parent-races.<a + name="NtA_183" href="#Nt_183"><sup>[183]</sup></a> The character which a + crossed body of animals will ultimately assume must depend on several + contingencies,—namely, on the relative numbers of the individuals + belonging to the two or more races which are allowed to mingle; on the + prepotency of one race over the other in the transmission of character; + and on the conditions of life to which they are exposed. When two + commingled breeds exist at first in nearly equal numbers, the whole will + sooner or later become intimately blended, but not so soon, both breeds + being equally favoured in all respects, as might have been expected. The + following calculation<a name="NtA_184" + href="#Nt_184"><sup>[184]</sup></a> shows that this is the case: if a + colony with an equal number of black and white men were founded, and we + assume that they marry indiscriminately, are equally prolific, and that + one in thirty annually dies and is born; then "in 65 years the number of + blacks, whites, and mulattoes would be equal. In 91 years the whites + would be 1-10th, the blacks 1-10th, and the mulattoes, or people of + intermediate degrees of colour, 8-10ths of the whole number. In three + centuries not 1-100th part of the whites would exist."</p> + + <p>When one of two mingled races exceeds the other greatly in number, the + latter will soon be wholly, or almost wholly, absorbed and lost.<a + name="NtA_185" href="#Nt_185"><sup>[185]</sup></a> Thus European pigs and + dogs have been largely introduced into the islands of the Pacific Ocean, + and the native races have been absorbed and lost in the course of about + fifty or sixty years;<a name="NtA_186" + href="#Nt_186"><sup>[186]</sup></a> but the imported races no doubt were + favoured. Rats may be considered as semi-domesticated animals. Some + snake-rats (<i>Mus alexandrinus</i>) escaped in the Zoological Gardens of + London, "and for a long time afterwards the keepers frequently caught + cross-bred rats, at first half-breds, afterwards with less and less of + the character of the snake-rat, till at length all traces of it + disappeared."<a name="NtA_187" href="#Nt_187"><sup>[187]</sup></a> On the + other hand, <!-- Page 88 --><span class="pagenum"><a + name="page88"></a>{88}</span>in some parts of London, especially near the + docks, where fresh rats are frequently imported, an endless variety of + intermediate forms may be found between the brown, black, and snake rat, + which are all three usually ranked as distinct species.</p> + + <p>How many generations are necessary for one species or race to absorb + another by repeated crosses has often been discussed;<a name="NtA_188" + href="#Nt_188"><sup>[188]</sup></a> and the requisite number has probably + been much exaggerated. Some writers have maintained that a dozen, or + score, or even more generations, are necessary; but this in itself is + improbable, for in the tenth generation there will be only 1-1024th part + of foreign blood in the offspring. Gärtner found,<a name="NtA_189" + href="#Nt_189"><sup>[189]</sup></a> that with plants one species could be + made to absorb another in from three to five generations, and he believes + that this could always be effected in from six to seventh generations. In + one instance, however, Kölreuter<a name="NtA_190" + href="#Nt_190"><sup>[190]</sup></a> speaks of the offspring of + <i>Mirabilis vulgaris</i>, crossed during eight successive generations by + <i>M. longiflora</i>, as resembling this latter species so closely, that + the most scrupulous observer could detect "vix aliquam notabilem + differentiam;"—he succeeded, as he says, "ad plenariam fere + transmutationem." But this expression shows that the act of absorption + was not even then absolutely complete, though these crossed plants + contained only the 1-256th part of <i>M. vulgaris</i>. The conclusions of + such accurate observers as Gärtner and Kölreuter are of far higher worth + than those made without scientific aim by breeders. The most remarkable + statement which I have met with of the persistent endurance of the + effects of a single cross is given by Fleischmann,<a name="NtA_191" + href="#Nt_191"><sup>[191]</sup></a> who, in reference to German sheep, + says "that the original coarse sheep have 5500 fibres of wool on a square + inch; grades of the third or fourth Merino cross produced about 8000, the + twentieth cross 27,000, the perfect pure Merino blood 40,000 to 48,000." + So that in this case common German sheep crossed twenty times + successively with Merinos have not by any means acquired wool as fine as + that of the pure breed. In all cases, the rate of absorption will <!-- + Page 89 --><span class="pagenum"><a name="page89"></a>{89}</span>depend + largely on the conditions of life being favourable to any particular + character; and we may suspect that there would be under the climate of + Germany a constant tendency to degeneration in the wool of Merinos, + unless prevented by careful selection; and thus perhaps the foregoing + remarkable case may be explained. The rate of absorption must also depend + on the amount of distinguishable difference between the two forms which + are crossed, and especially, as Gärtner insists, on prepotency of + transmission in the one form over the other. We have seen in the last + chapter that one of two French breeds of sheep yielded up its character, + when crossed with Merinos, very much slower than the other; and the + common German sheep referred to by Fleischmann may present an analogous + case. But in all cases there will be during many subsequent generations + more or less liability to reversion, and it is this fact which has + probably led authors to maintain that a score or more of generations are + requisite for one race to absorb another. In considering the final result + of the commingling of two or more breeds, we must not forget that the act + of crossing in itself tends to bring back long-lost characters not proper + to the immediate parent-forms.</p> + + <p>With respect to the influence of the conditions of life on any two + breeds which are allowed to cross freely, unless both are indigenous and + have long been accustomed to the country where they live, they will, in + all probability, be unequally affected by the conditions, and this will + modify the result. Even with indigenous breeds, it will rarely or never + occur that both are equally well adapted to the surrounding + circumstances; more especially when permitted to roam freely, and not + carefully tended, as will generally be the case with breeds allowed to + cross. As a consequence of this, natural selection will to a certain + extent come into action, and the best fitted will survive, and this will + aid in determining the ultimate character of the commingled body.</p> + + <p>How long a time it would require before such a crossed body of animals + would assume within a limited area a uniform character no one can say; + that they would ultimately become uniform from free intercrossing, and + from the survival of the fittest, we may feel assured; but the character + thus acquired would rarely or never, as we may infer from the several + previous <!-- Page 90 --><span class="pagenum"><a + name="page90"></a>{90}</span>considerations, be exactly intermediate + between that of the two parent-breeds. With respect to the very slight + differences by which the individuals of the same sub-variety, or even of + allied varieties, are characterised, it is obvious that free crossing + would soon obliterate such small distinctions. The formation of new + varieties, independently of selection, would also thus be prevented; + except when the same variation continually recurred from the action of + some strongly predisposing cause. Hence we may conclude that free + crossing has in all cases played an important part in giving to all the + members of the same domestic race, and of the same natural species, + uniformity of character, though largely modified by natural selection and + by the direct action of the surrounding conditions.</p> + + <p><i>On the possibility of all organic beings occasionally + intercrossing.</i>—But it may be asked, can free crossing occur + with hermaphrodite animals and plants? All the higher animals, and the + few insects which have been domesticated, have separated sexes, and must + inevitably unite for each birth. With respect to the crossing of + hermaphrodites, the subject is too large for the present volume, and will + be more properly treated in a succeeding work. In my 'Origin of Species,' + however, I have given a short abstract of the reasons which induce me to + believe that all organic beings occasionally cross, though perhaps in + some cases only at long intervals of time.<a name="NtA_192" + href="#Nt_192"><sup>[192]</sup></a> I will here just recall the fact that + many plants, though hermaphrodite in structure, are unisexual in + function;—such as those called by C. K. Sprengel + <i>dichogamous</i>, in which the pollen and stigma of the same flower are + matured at different periods; or those called by me <i>reciprocally + dimorphic</i>, in which the flower's own pollen is not fitted to + fertilise its own stigma; or again, the many kinds in which curious + mechanical contrivances exist, effectually preventing self-fertilisation. + There are, however, many hermaphrodite plants which are not in any way + specially constructed to favour intercrossing, but which nevertheless + commingle almost as freely as animals with separated sexes. This is the + case with cabbages, radishes, and onions, as I know from <!-- Page 91 + --><span class="pagenum"><a name="page91"></a>{91}</span>having + experimented on them: even the peasants of Liguria say that cabbages must + be prevented "from falling in love" with each other. In the orange tribe, + Gallesio<a name="NtA_193" href="#Nt_193"><sup>[193]</sup></a> remarks + that the amelioration of the various kinds is checked by their continual + and almost regular crossing. So it is with numerous other plants.</p> + + <p>Nevertheless some cultivated plants can be named which rarely + intercross, as the common pea, or which never intercross, as I have + reason to believe is the case with the sweet-pea (<i>Lathyrus + odoratus</i>); yet the structure of these flowers certainly favours an + occasional cross. The varieties of the tomato and aubergine + (<i>Solanum</i>) and pimenta (<i>Pimenta vulgaris?</i>) are said<a + name="NtA_194" href="#Nt_194"><sup>[194]</sup></a> never to cross, even + when growing alongside each other. But it should be observed that these + are all exotic plants, and we do not know how they would behave in their + native country when visited by the proper insects.</p> + + <p>It must also be admitted that some few natural species appear under + our present state of knowledge to be perpetually self-fertilised, as in + the case of the Bee Ophrys (<i>O. apifera</i>), though adapted in its + structure to be occasionally crossed. The <i>Leersia oryzoides</i> + produces minute enclosed flowers which cannot possibly be crossed, and + these alone, to the exclusion of the ordinary flowers, have as yet been + known to yield seed.<a name="NtA_195" href="#Nt_195"><sup>[195]</sup></a> + A few additional and analogous cases could be advanced. But these facts + do not make me doubt that it is a general law of nature that the + individuals of the same species occasionally intercross, and that some + great advantage is derived from this act. It is well known (and I shall + hereafter have to give instances) that some plants, both indigenous and + naturalised, rarely or never produce flowers; or, if they flower, never + produce seeds. But no one is thus led to doubt that it is a general law + of nature that phanerogamic plants should produce flowers, and that these + flowers should produce seed. When they fail, we believe that such plants + would perform their proper functions under different conditions, or that + they formerly did so and will do so again. On analogous grounds, I + believe that the few flowers <!-- Page 92 --><span class="pagenum"><a + name="page92"></a>{92}</span>which do not now intercross, either would do + so under different conditions, or that they formerly fertilised each + other at intervals—the means for effecting this being generally + still retained—and they will do so again at some future period, + unless indeed they become extinct. On this view alone, many points in the + structure and action of the reproductive organs in hermaphrodite plants + and animals are intelligible,—for instance, the male and female + organs never being so completely enclosed as to render access from + without impossible. Hence we may conclude that the most important of all + the means for giving uniformity to the individuals of the same species, + namely, the capacity of occasionally intercrossing, is present, or has + been formerly present, with all organic beings.</p> + +<blockquote class="b1n"> + + <p><i>On certain Characters not blending.</i>—When two breeds are + crossed their characters usually become intimately fused together; but + some characters refuse to blend, and are transmitted in an unmodified + state either from both parents or from one. When grey and white mice are + paired, the young are not piebald nor of an intermediate tint, but are + pure white or of the ordinary grey colour: so it is when white and common + collared turtle-doves are paired. In breeding Game fowls, a great + authority, Mr. J. Douglas, remarks, "I may here state a strange fact: if + you cross a black with a white game, you get birds of both breeds of the + clearest colour." Sir R. Heron crossed during many years white, black, + brown, and fawn-coloured Angora rabbits, and never once got these colours + mingled in the same animal, but often all four colours in the same + litter.<a name="NtA_196" href="#Nt_196"><sup>[196]</sup></a> Additional + cases could be given, but this form of inheritance is very far from + universal even with respect to the most distinct colours. When turnspit + dogs and ancon sheep, both of which have dwarfed limbs, are crossed with + common breeds, the offspring are not intermediate in structure, but take + after either parent. When tailless or hornless animals are crossed with + perfect animals, it frequently, but by no means invariably, happens that + the offspring are <!-- Page 93 --><span class="pagenum"><a + name="page93"></a>{93}</span>either perfectly furnished with these organs + or are quite destitute of them. According to Rengger, the hairless + condition of the Paraguay dog is either perfectly or not at all + transmitted to its mongrel offspring; but I have seen one partial + exception in a dog of this parentage which had part of its skin hairy, + and part naked; the parts being distinctly separated as in a piebald + animal. When Dorking fowls with five toes are crossed with other breeds, + the chickens often have five toes on one foot and four on the other. Some + crossed pigs raised by Sir R. Heron between the solid-hoofed and common + pig had not all four feet in an intermediate condition, but two feet were + furnished with properly divided, and two with united hoofs.</p> + + <p>Analogous facts have been observed with plants: Major Trevor Clarke + crossed the little, glabrous-leaved, annual stock (<i>Matthiola</i>), + with pollen of a large, red-flowered, rough-leaved, biennial stock, + called <i>cocardeau</i> by the French, and the result was that half the + seedlings had glabrous and the other half rough leaves, but none had + leaves in an intermediate state. That the glabrous seedlings were the + product of the rough-leaved variety, and not accidentally of the + mother-plant's own pollen, was shown by their tall and strong habit of + growth.<a name="NtA_197" href="#Nt_197"><sup>[197]</sup></a> In the + succeeding generations raised from the rough-leaved crossed seedlings, + some glabrous plants appeared, showing that the glabrous character, + though incapable of blending with and modifying the rough leaves, was all + the time latent in this family of plants. The numerous plants formerly + referred to, which I raised from reciprocal crosses between the peloric + and common Antirrhinum, offer a nearly parallel case; for in the first + generation all the plants resembled the common form, and in the next + generation, out of one hundred and thirty-seven plants, two alone were in + an intermediate condition, the others perfectly resembling either the + peloric or common form. Major Trevor Clarke also fertilised the + above-mentioned red-flowered stock with pollen from the purple Queen + stock, and about half the seedlings scarcely differed in habit, and not + at all in the red colour of the flower, from the mother-plant, the other + half bearing blossoms of a rich purple, closely like those of the + paternal plant. Gärtner crossed many white and yellow-flowered species + and varieties of Verbascum; and these colours were never blended, but the + offspring bore either pure white or pure yellow blossoms; the former in + the larger proportion.<a name="NtA_198" + href="#Nt_198"><sup>[198]</sup></a> Dr. Herbert raised many seedlings, as + he informed me, from Swedish turnips crossed by two other varieties, and + these never produced flowers of an intermediate tint, but always like one + of their parents. I fertilised the purple sweet-pea (<i>Lathyrus + odoratus</i>), which has a dark reddish-purple standard-petal and + violet-coloured wings and keel, with pollen of the painted-lady + sweet-pea, which has a pale cherry-coloured standard, and almost white + wings and keel; and from the same pod I twice raised plants perfectly + resembling both sorts; the greater number resembling the father. So + perfect was the resemblance, that I should have thought there had <!-- + Page 94 --><span class="pagenum"><a name="page94"></a>{94}</span>been + some mistake, if the plants which were at first identical with the + paternal variety, namely, the painted-lady, had not later in the season + produced, as mentioned in a former chapter, flowers blotched and streaked + with dark purple. I raised grandchildren and great-grandchildren from + these crossed plants, and they continued to resemble the painted-lady, + but during the later generations became rather more blotched with purple, + yet none reverted completely to the original mother-plant, the purple + sweet-pea. The following case is slightly different, but still shows the + same principle: Naudin<a name="NtA_199" + href="#Nt_199"><sup>[199]</sup></a> raised numerous hybrids between the + yellow <i>Linaria vulgaris</i> and the purple <i>L. purpurea</i>, and + during three successive generations the colours kept distinct in + different parts of the same flower.</p> + + <p>From such cases as the foregoing, in which the offspring of the first + generation perfectly resemble either parent, we come by a small step to + those cases in which differently coloured flowers borne on the same root + resemble both parents, and by another step to those in which the same + flower or fruit is striped or blotched with the two parental colours, or + bears a single stripe of the colour or other characteristic quality of + one of the parent-forms. With hybrids and mongrels it frequently or even + generally happens that one part of the body resembles more or less + closely one parent and another part the other parent; and here again some + resistance to fusion, or, what comes to the same thing, some mutual + affinity between the organic atoms of the same nature, apparently comes + into play, for otherwise all parts of the body would be equally + intermediate in character. So again, when the offspring of hybrids or + mongrels, which are themselves nearly intermediate in character, revert + either wholly or by segments to their ancestors, the principle of the + affinity of similar, or the repulsion of dissimilar atoms, must come into + action. To this principle, which seems to be extremely general, we shall + recur in the chapter on pangenesis.</p> + + <p>It is remarkable, as has been strongly insisted upon by Isidore + Geoffroy St. Hilaire in regard to animals, that the transmission of + characters without fusion occurs most rarely when species are crossed; I + know of one exception alone, namely, with the hybrids naturally produced + between the common and hooded crow (<i>Corvus corone</i> and + <i>cornix</i>), which, however, are closely allied species, differing in + nothing except colour. Nor have I met with any well-ascertained cases of + transmission of this kind, even when one form is strongly prepotent over + another, when two races are crossed which have been slowly formed by + man's selection, and therefore resemble to a certain extent natural + species. Such cases as puppies in the same litter closely resembling two + distinct breeds, are probably due to super-fœtation,—that is, + to the influence of two fathers. All the characters above enumerated, + which are transmitted in a perfect state to some of the offspring and not + to others,—such as distinct colours, nakedness of skin, smoothness + of leaves, absence of horns or tail, additional toes, pelorism, dwarfed + structure, &c.,—have all been known to appear suddenly in + individual animals and plants. From this fact, and from the several + slight, aggregated differences which distinguish domestic races and + species from <!-- Page 95 --><span class="pagenum"><a + name="page95"></a>{95}</span>each other, not being liable to this + peculiar form of transmission, we may conclude that it is in some way + connected with the sudden appearance of the characters in question.</p> + +</blockquote> + + <p><i>On the Modification of old Races and the Formation of new Races by + Crossing.</i>—We have hitherto chiefly considered the effects of + crossing in giving uniformity of character; we must now look to an + opposite result. There can be no doubt that crossing, with the aid of + rigorous selection during several generations, has been a potent means in + modifying old races, and in forming new ones. Lord Orford crossed his + famous stud of greyhounds once with the bulldog, which breed was chosen + from being deficient in scenting powers, and from having what was wanted, + courage and perseverance. In the course of six or seven generations all + traces of the external form of the bulldog were eliminated, but courage + and perseverance remained. Certain pointers have been crossed, as I hear + from the Rev. W. D. Fox, with the foxhound, to give them dash and speed. + Certain strains of Dorking fowls have had a slight infusion of Game + blood; and I have known a great fancier who on a single occasion crossed + his turbit-pigeons with barbs, for the sake of gaining greater breadth of + beak.</p> + + <p>In the foregoing cases breeds have been crossed once, for the sake of + modifying some particular character; but with most of the improved races + of the pig, which now breed true, there have been repeated + crosses,—for instance, the improved Essex owes its excellence to + repeated crosses with the Neapolitan, together probably with some + infusion of Chinese blood.<a name="NtA_200" + href="#Nt_200"><sup>[200]</sup></a> So with our British sheep: almost all + the races, except the Southdown, have been largely crossed; "this, in + fact, has been the history of our principal breeds."<a name="NtA_201" + href="#Nt_201"><sup>[201]</sup></a> To give an example, the "Oxfordshire + Downs" now rank as an established breed.<a name="NtA_202" + href="#Nt_202"><sup>[202]</sup></a> They were produced about the year + 1830 by crossing "Hampshire and in some instances Southdown ewes with + Cotswold rams:" now the Hampshire ram was itself produced by repeated + crosses between the native <!-- Page 96 --><span class="pagenum"><a + name="page96"></a>{96}</span>Hampshire sheep and Southdowns; and the + long-woolled Cotswold were improved by crosses with the Leicester, which + latter again is believed to have been a cross between several + long-woolled sheep. Mr. Spooner, after considering the various cases + which have been carefully recorded, concludes "that from a judicious + pairing of cross-bred animals it is practicable to establish a new + breed." On the Continent the history of several crossed races of cattle + and of other animals has been well ascertained. To give one instance: the + King of Wurtemberg, after twenty-five years' careful breeding, that is + after six or seven generations, made a new breed of cattle from a cross + between a Dutch and Swiss breed, combined with other breeds.<a + name="NtA_203" href="#Nt_203"><sup>[203]</sup></a> The Sebright bantam, + which breeds as true as any other kind of fowl, was formed about sixty + years ago by a complicated cross.<a name="NtA_204" + href="#Nt_204"><sup>[204]</sup></a> Dark Brahmas, which are believed by + some fanciers to constitute a distinct species, were undoubtedly formed<a + name="NtA_205" href="#Nt_205"><sup>[205]</sup></a> in the United States, + within a recent period, by a cross between Chittagongs and Cochins. With + plants I believe there is little doubt that some kinds of turnips, now + extensively cultivated, are crossed races; and the history of a variety + of wheat which was raised from two very distinct varieties, and which + after six years' culture presented an even sample, has been recorded on + good authority.<a name="NtA_206" href="#Nt_206"><sup>[206]</sup></a></p> + + <p>Until quite lately, cautious and experienced breeders, though not + averse to a single infusion of foreign blood, were almost universally + convinced that the attempt to establish a new race, intermediate between + two widely distinct races, was hopeless: "they clung with superstitious + tenacity to the doctrine of purity of blood, believing it to be the ark + in which alone true safety could be found."<a name="NtA_207" + href="#Nt_207"><sup>[207]</sup></a> Nor was this conviction unreasonable: + when two distinct races are crossed, the offspring of the first + generation are generally nearly uniform in character; but even this + sometimes fails to be the case, especially with crossed dogs and fowls, + the young of which from the first are sometimes much <!-- Page 97 + --><span class="pagenum"><a name="page97"></a>{97}</span>diversified. As + cross-bred animals are generally of large size and vigorous, they have + been raised in great numbers for immediate consumption. But for breeding + they are found to be utterly useless; for though they may be themselves + uniform in character, when paired together they yield during many + generations offspring astonishingly diversified. The breeder is driven to + despair, and concludes that he will never form an intermediate race. But + from the cases already given, and from others which have been recorded, + it appears that patience alone is necessary; as Mr. Spooner remarks, + "nature opposes no barrier to successful admixture; in the course of + time, by the aid of selection and careful weeding, it is practicable to + establish a new breed." After six or seven generations the hoped-for + result will in most cases be obtained; but even then an occasional + reversion, or failure to keep true, may be expected. The attempt, + however, will assuredly fail if the conditions of life be decidedly + unfavourable to the characters of either parent-breed.<a name="NtA_208" + href="#Nt_208"><sup>[208]</sup></a></p> + + <p>Although the grandchildren and succeeding generations of cross-bred + animals are generally variable in an extreme degree, some curious + exceptions to the rule have been observed, both with crossed races and + species. Thus Boitard and Corbié<a name="NtA_209" + href="#Nt_209"><sup>[209]</sup></a> assert that from a Pouter and a Runt + "a Cavalier will appear, which we have classed amongst pigeons of pure + race, because it transmits all its qualities to its posterity." The + editor of the 'Poultry Chronicle'<a name="NtA_210" + href="#Nt_210"><sup>[210]</sup></a> bred some bluish fowls from a black + Spanish cock and a Malay hen; and these remained true to colour + "generation after generation." The Himalayan breed of rabbits was + certainly formed by crossing two sub-varieties of the silver-grey rabbit; + although it suddenly assumed its present character, which differs much + from that of either parent-breed, yet it has ever since been easily and + truly propagated. I crossed some Labrador and Penguin ducks, and + recrossed the mongrels with Penguins; afterwards, most of the ducks + reared during three generations were nearly uniform in character, being + brown with a white crescentic mark on the lower part of the breast, <!-- + Page 98 --><span class="pagenum"><a name="page98"></a>{98}</span>and with + some white spots at the base of the beak; so that by the aid of a little + selection a new breed might easily have been formed. In regard to crossed + varieties of plants, Mr. Beaton remarks<a name="NtA_211" + href="#Nt_211"><sup>[211]</sup></a> that "Melville's extraordinary cross + between the Scotch kale and an early cabbage is as true and genuine as + any on record;" but in this case no doubt selection was practised. + Gärtner<a name="NtA_212" href="#Nt_212"><sup>[212]</sup></a> has given + five cases of hybrids, in which the progeny kept constant; and hybrids + between <i>Dianthus <span class="correction" title="Original reads `armoria', corrected by errata, page viii." + >armeria</span></i> and <i>deltoides</i> remained true and uniform to the + tenth generation. Dr. Herbert likewise showed me a hybrid from two + species of Loasa which from its first production had kept constant during + several generations.</p> + + <p>We have seen in the earlier chapters, that some of our domesticated + animals, such as dogs, cattle, pigs, &c., are almost certainly + descended from more than one species, or wild race, if any one prefers to + apply this latter term to forms which were enabled to keep distinct in a + state of nature. Hence the crossing of aboriginally distinct species + probably came into play at an early period in the formation of our + present races. From Rütimeyer's observations there can be little doubt + that this occurred with cattle; but in most cases some one of the forms + which were allowed to cross freely, will, it is probable, have absorbed + and obliterated the others. For it is not likely that semi-civilized men + would have taken the necessary pains to modify by selection their + commingled, crossed, and fluctuating stock. Nevertheless, those animals + which were best adapted to their conditions of life would have survived + through natural selection; and by this means crossing will often have + indirectly aided in the formation of primeval domesticated breeds.</p> + + <p>Within recent times, as far as animals are concerned, the crossing of + distinct species has done little or nothing in the formation or + modification of our races. It is not yet known whether the species of + silk-moth which have been recently crossed in France will yield permanent + races. In the fourth chapter I alluded with some hesitation to the + statement that a new breed, between the hare and rabbit, called + leporides, had been formed in France, and was found capable of + propagating <!-- Page 99 --><span class="pagenum"><a + name="page99"></a>{99}</span>itself; but it is now positively affirmed<a + name="NtA_213" href="#Nt_213"><sup>[213]</sup></a> that this is an error. + With plants which can be multiplied by buds and cuttings, hybridisation + has done wonders, as with many kinds of Roses, Rhododendrons, + Pelargoniums, Calceolarias, and Petunias. Nearly all these plants can be + propagated by seed; most of them freely; but extremely few or none come + true by seed.</p> + + <p>Some authors believe that crossing is the chief cause of + variability,—that is, of the appearance of absolutely new + characters. Some have gone so far as to look at it as the sole cause; but + this conclusion is disproved by some of the facts given in the chapter on + Bud-variation. The belief that characters not present in either parent or + in their ancestors frequently originate from crossing is doubtful; that + they occasionally thus arise is probable; but this subject will be more + conveniently discussed in a future chapter on the causes of + Variability.</p> + + <p>A condensed summary of this and of the three following chapters, + together with some remarks on Hybridism, will be given in the nineteenth + chapter.</p> + +<hr class="full" /> + +<p><!-- Page 100 --><span class="pagenum"><a name="page100"></a>{100}</span></p> + +<h3>CHAPTER XVI.</h3> + +<p class="cenhead">CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF +VARIETIES—INFLUENCE OF DOMESTICATION ON FERTILITY.</p> + +<blockquote class="b1n"> + + <p><span class="scac">DIFFICULTIES IN JUDGING OF THE FERTILITY OF + VARIETIES WHEN CROSSED</span>—<span class="scac">VARIOUS CAUSES + WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD OF BREEDING AND SEXUAL + PREFERENCE</span>—<span class="scac">VARIETIES OF WHEAT SAID TO BE + STERILE WHEN CROSSED</span>—<span class="scac">VARIETIES OF MAIZE, + VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO, RENDERED IN SOME + DEGREE MUTUALLY STERILE</span>—<span class="scac">DOMESTICATION + ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES WHEN + CROSSED</span>—<span class="scac">ON THE INCREASED FERTILITY OF + UNCROSSED ANIMALS AND PLANTS FROM DOMESTICATION AND + CULTIVATION.</span></p> + +</blockquote> + + <p>The domesticated races of both animals and plants, when crossed, are + with extremely few exceptions quite prolific,—in some cases even + more so than the purely bred parent-races. The offspring, also, raised + from such crosses are likewise, as we shall see in the following chapter, + generally more vigorous and fertile than their parents. On the other + hand, species when crossed, and their hybrid offspring, are almost + invariability in some degree sterile; and here there seems to exist a + broad and insuperable distinction between races and species. The + importance of this subject as bearing on the origin of species is + obvious; and we shall hereafter recur to it.</p> + + <p>It is unfortunate how few precise observations have been made on the + fertility of mongrel animals and plants during several successive + generations. Dr. Broca<a name="NtA_214" + href="#Nt_214"><sup>[214]</sup></a> has remarked that no one has observed + whether, for instance, mongrel dogs, bred <i>inter se</i>, are + indefinitely fertile; yet, if a shade of infertility be detected by + careful observation in the offspring of natural forms when crossed, it is + thought that their specific distinction is proved. But so many breeds of + sheep, cattle, pigs, dogs, and poultry, have been crossed and recrossed + in various ways, that any sterility, if it had existed, would from being + injurious <!-- Page 101 --><span class="pagenum"><a + name="page101"></a>{101}</span>almost certainly have been observed. In + investigating the fertility of crossed varieties many sources of doubt + occur. Whenever the least trace of sterility between two plants, however + closely allied, was observed by Kölreuter, and more especially by + Gärtner, who counted the exact number of seed in each capsule, the two + forms were at once ranked as distinct species; and if this rule be + followed, assuredly it will never be proved that varieties when crossed + are in any degree sterile. We have formerly seen that certain breeds of + dogs do not readily pair together; but no observations have been made + whether, when paired, they produce the full number of young, and whether + the latter are perfectly fertile <i>inter se</i>; but, supposing that + some degree of sterility were found to exist, naturalists would simply + infer that these breeds were descended from aboriginally distinct + species; and it would be scarcely possible to ascertain whether or not + this explanation was the true one.</p> + + <p>The Sebright Bantam is much less prolific than any other breed of + fowls, and is descended from a cross between two very distinct breeds, + recrossed by a third sub-variety. But it would be extremely rash to infer + that the loss of fertility was in any manner connected with its crossed + origin, for it may with more probability be attributed either to + long-continued close interbreeding, or to an innate tendency to sterility + correlated with the absence of hackles and sickle tail-feathers.</p> + + <p>Before giving the few recorded cases of forms, which must be ranked as + varieties, being in some degree sterile when crossed, I may remark that + other causes sometimes interfere with varieties freely intercrossing. + Thus they may differ too greatly in size, as with some kinds of dogs and + fowls: for instance, the editor of the 'Journal of Horticulture, + &c.,'<a name="NtA_215" href="#Nt_215"><sup>[215]</sup></a> says that + he can keep Bantams with the larger breeds without much danger of their + crossing, but not with the smaller breeds, such as Games, Hamburgs, + &c. With plants a difference in the period of flowering serves to + keep varieties distinct, as with the various kinds of maize and wheat: + thus Colonel Le Couteur<a name="NtA_216" + href="#Nt_216"><sup>[216]</sup></a> remarks, "the Talavera wheat, from + flowering much earlier than any other kind, is sure to continue pure." In + different parts of <!-- Page 102 --><span class="pagenum"><a + name="page102"></a>{102}</span>the Falkland Islands the cattle are + breaking up into herds of different colours; and those on the higher + ground, which are generally white, usually breed, as I am informed by + Admiral Sulivan, three months earlier than those on the lowlands; and + this would manifestly tend to keep the herds from blending.</p> + + <p>Certain domestic races seem to prefer breeding with their own kind; + and this is a fact of some importance, for it is a step towards that + instinctive feeling which helps to keep closely allied species in a state + of nature distinct. We have now abundant evidence that, if it were not + for this feeling, many more hybrids would be naturally produced than is + the case. We have seen in the first chapter that the alco dog of Mexico + dislikes dogs of other breeds; and the hairless dog of Paraguay mixes + less readily with the European races, than the latter do with each other. + In Germany the female Spitz-dog is said to receive the fox more readily + than will other dogs; a female Australian Dingo in England attracted the + wild male foxes. But these differences in the sexual instinct and + attractive power of the various breeds may be wholly due to their descent + from distinct species. In Paraguay the horses have much freedom, and an + excellent observer<a name="NtA_217" href="#Nt_217"><sup>[217]</sup></a> + believes that the native horses of the same colour and size prefer + associating with each other, and that the horses which have been imported + from Entre Rios and Banda Oriental into Paraguay likewise prefer + associating together. In Circassia six sub-races of the horse are known + and have received distinct names; and a native proprietor of rank<a + name="NtA_218" href="#Nt_218"><sup>[218]</sup></a> asserts that horses of + three of these races, whilst living a free life, almost always refuse to + mingle and cross, and will even attack each other.</p> + + <p>It has been observed, in a district stocked with heavy Lincolnshire + and light Norfolk sheep, that both kinds, though bred together, when + turned out, "in a short time separate to a sheep;" the Lincolnshires + drawing off to the rich soil, and the Norfolks to their own dry light + soil; and as long as there is plenty of grass, "the two breeds keep + themselves as distinct as rooks and pigeons." In this case different + habits of <!-- Page 103 --><span class="pagenum"><a + name="page103"></a>{103}</span>life tend to keep the races distinct. On + one of the Faroe islands, not more than half a mile in diameter, the + half-wild native black sheep are said not to have readily mixed with the + imported white sheep. It is a more curious fact that the semi-monstrous + ancon sheep of modern origin "have been observed to keep together, + separating themselves from the rest of the flock, when put into + enclosures with other sheep."<a name="NtA_219" + href="#Nt_219"><sup>[219]</sup></a> With respect to fallow deer, which + live in a semi-domesticated condition, Mr. Bennett<a name="NtA_220" + href="#Nt_220"><sup>[220]</sup></a> states that the dark and pale + coloured herds, which have long been kept together in the Forest of Dean, + in High Meadow Woods, and in the New Forest, have never been known to + mingle: the dark-coloured deer, it may be added, are believed to have + been first brought by James I. from Norway, on account of their greater + hardiness. I imported from the island of Porto Santo two of the feral + rabbits, which differ, as described in the fourth chapter, from common + rabbits; both proved to be males, and, though they lived during some + years in the Zoological Gardens, the superintendent, Mr. Bartlett, in + vain endeavoured to make them breed with various tame kinds; but whether + this refusal to breed was due to any change in instinct, or simply to + their extreme wildness; or whether confinement had rendered them sterile, + as often occurs, cannot be told.</p> + + <p>Whilst matching for the sake of experiment many of the most distinct + breeds of pigeons, it frequently appeared to me that the birds, though + faithful to their marriage vow, retained some desire after their own + kind. Accordingly I asked Mr. Wicking, who has kept a larger stock of + various breeds together than any man in England, whether he thought that + they would prefer pairing with their own kind, supposing that there were + males and females enough of each; and he without hesitation answered that + he was convinced that this was the case. It has often been noticed that + the dovecot pigeon seems to have an actual aversion towards the several + fancy breeds;<a name="NtA_221" href="#Nt_221"><sup>[221]</sup></a> yet + all have <!-- Page 104 --><span class="pagenum"><a + name="page104"></a>{104}</span>certainly sprung from a common progenitor. + The Rev. W. D. Fox informs me that his flocks of white and common Chinese + geese kept distinct.</p> + + <p>These facts and statements, though some of them are incapable of + proof, resting only on the opinion of experienced observers, show that + some domestic races are led by different habits of life to keep to a + certain extent separate, and that others prefer coupling with their own + kind, in the same manner as species in a state of nature, though in a + much less degree.</p> + +<blockquote class="b1n"> + + <p>With respect to sterility from the crossing of domestic races, I know + of no well-ascertained case with animals. This fact, seeing the great + difference in structure between some breeds of pigeons, fowls, pigs, + dogs, &c., is extraordinary, in contrast with the sterility of many + closely allied natural species when crossed; but we shall hereafter + attempt to show that it is not so extraordinary as it at first appears. + And it may be well here to recall to mind that the amount of external + difference between two species will not safely guide us in foretelling + whether or not they will breed together,—some closely allied + species when crossed being utterly sterile, and others which are + extremely unlike being moderately fertile. I have said that no case of + sterility in crossed races rests on satisfactory evidence; but here is + one which at first seems trustworthy. Mr. Youatt,<a name="NtA_222" + href="#Nt_222"><sup>[222]</sup></a> and a better authority cannot be + quoted, states, that formerly in Lancashire crosses were frequently made + between longhorn and shorthorn cattle; the first cross was excellent, but + the produce was uncertain; in the third or fourth generation the cows + were bad milkers; "in addition to which, there was much uncertainty + whether the cows would conceive; and full one-third of the cows among + some of these half-breds failed to be in calf." This at first seems a + good case; but Mr. Wilkinson states,<a name="NtA_223" + href="#Nt_223"><sup>[223]</sup></a> that a breed derived from this same + cross was actually established in another part of England; and if it had + failed in fertility, the fact would surely have been noticed. Moreover, + supposing that Mr. Youatt had proved his case, it might be argued that + the sterility was wholly due to the two parent-breeds being descended + from primordially distinct species.</p> + + <p>I will give a case with plants, to show how difficult it is to get + sufficient evidence. Mr. Sheriff, who has been so successful in the + formation of new races of wheat, fertilised the Hopetoun with the + Talavera; in the first and second generations the produce was + intermediate in character, but in the fourth generation "it was found to + consist of many varieties; nine-tenths of the florets proved barren, and + many of the seeds seemed shrivelled abortions, void of vitality, and the + whole race was evidently verging to extinction."<a name="NtA_224" + href="#Nt_224"><sup>[224]</sup></a> Now, considering how little these + <!-- Page 105 --><span class="pagenum"><a + name="page105"></a>{105}</span>varieties of wheat differ in any important + character, it seems to me very improbable that the sterility resulted, as + Mr. Sheriff thought, from the cross, but from some quite distinct cause. + Until such experiments are many times repeated, it would be rash to trust + them; but unfortunately they have been rarely tried even once with + sufficient care.</p> + + <p>Gärtner has recorded a more remarkable and trustworthy case: he + fertilised thirteen panicles (and subsequently nine others) on a dwarf + maize bearing yellow seed<a name="NtA_225" + href="#Nt_225"><sup>[225]</sup></a> with pollen of a tall maize having + red seed; and one head alone produced good seed, only five in number. + Though these plants are monœcious, and therefore do not require + castration, yet I should have suspected some accident in the manipulation + had not Gärtner expressly stated that he had during many years grown + these two varieties together, and they did not spontaneously cross; and + this, considering that the plants are monœcious and abound with + pollen, and are well known generally to cross freely, seems explicable + only on the belief that these two varieties are in some degree mutually + infertile. The hybrid plants raised from the above five seed were + intermediate in structure, extremely variable, and perfectly fertile.<a + name="NtA_226" href="#Nt_226"><sup>[226]</sup></a> No one, I believe, has + hitherto suspected that these varieties of maize are distinct species; + but had the hybrids been in the least sterile, no doubt Gärtner would at + once have so classed them. I may here remark, that with undoubted species + there is not necessarily any close relation between the sterility of a + first cross and that of the hybrid offspring. Some species can be crossed + with facility, but produce utterly sterile hybrids; others can be crossed + with extreme difficulty, but the hybrids when produced are moderately + fertile. I am not aware, however, of any instance quite like this of the + maize with natural species, namely, of a first cross made with + difficulty, but yielding perfectly fertile hybrids.</p> + + <p>The following case is much more remarkable, and evidently perplexed + Gärtner, whose strong wish it was to draw a broad line of distinction + between species and varieties. In the genus Verbascum, he made, during + eighteen years, a vast number of experiments, and crossed no less than + 1085 flowers and counted their seeds. Many of these experiments consisted + in crossing white and yellow varieties of both <i>V. lychnitis</i> and + <i>V. blattaria</i> with nine other species and their hybrids. That the + white and yellow flowered plants of these two species are really + varieties, no one has doubted; and Gärtner actually raised in the case of + both species one variety from the seed of the other. Now in two of his + works<a name="NtA_227" href="#Nt_227"><sup>[227]</sup></a> he distinctly + asserts that crosses between similarly-coloured flowers yield more seed + than between dissimilarly-coloured; so that the yellow-flowered variety + of either species (and conversely with the white-flowered variety), when + crossed with pollen of its own kind, yields more seed than when crossed + with that of the white variety; and so it is when differently coloured + species are crossed. The general results may be seen in the Table at the + <!-- Page 106 --><span class="pagenum"><a + name="page106"></a>{106}</span>end of his volume. In one instance he + gives<a name="NtA_228" href="#Nt_228"><sup>[228]</sup></a> the following + details; but I must premise that Gärtner, to avoid exaggerating the + degree of sterility in his crosses, always compares the <i>maximum</i> + number obtained from a cross with the <i>average</i> number naturally + given by the pure mother-plant. The white-variety of <i>V. lychnitis</i>, + naturally fertilised by its own pollen, gave from an <i>average</i> of + twelve capsules ninety-six good seeds in each; whilst twenty flowers + fertilised with pollen from the yellow variety of this same species, gave + as the <i>maximum</i> only eighty-nine good seed; so that we have the + proportion of 1000 to 908, according to Gärtner's usual scale. I should + have thought it possible that so small a difference in fertility might + have been accounted for by the evil effects of the necessary castration; + but Gärtner shows that the white variety of <i>V. lychnitis</i>, when + fertilised first by the white variety of <i>V. blattaria</i>, and then by + the yellow variety of this species, yielded seed in the proportion of 622 + to 438; and in both these cases castration was performed. Now the + sterility which results from the crossing of the differently coloured + varieties of the same species, is fully as great as that which occurs in + many cases when distinct species are crossed. Unfortunately Gärtner + compared the results of the first unions alone, and not the sterility of + the two sets of hybrids produced from the white variety of <i>V. + lychnitis</i> when fertilised by the white and yellow varieties of <i>V. + blattaria</i>, for it is probable that they would have differed in this + respect.</p> + + <p>Mr. J. Scott has given me the results of a series of experiments on + Verbascum, made by him in the Botanic Gardens of Edinburgh. He repeated + some of Gärtner's experiments on distinct species, but obtained only + fluctuating results; some confirmatory, but the greater number + contradictory; nevertheless these seem hardly sufficient to overthrow the + conclusions arrived at by Gärtner from experiments tried on a much larger + scale. In the second place Mr. Scott experimented on the relative + fertility of unions between similarly and dissimilarly-coloured varieties + of the same species. Thus he fertilised six flowers of the yellow variety + of <i>V. lychnitis</i> by its own pollen, and obtained six capsules, and + calling, for the sake of having a standard of comparison, the average + number of good seed in each one hundred, he found that this same yellow + variety, when fertilised by the white variety, yielded from seven + capsules an average of ninety-four seed. On the same principle, the white + variety of <i>V. lychnitis</i> by its own pollen (from six capsules), and + by the pollen of the yellow variety (eight capsules), yielded seed in the + proportion of 100 to 82. The yellow variety of <i>V. thapsus</i> by its + own pollen (eight capsules), and by that of the white variety (only two + capsules), yielded seed in the proportion of 100 to 94. Lastly, the white + variety of <i>V. blattaria</i> by its own pollen (eight capsules), and by + that of the yellow variety (five capsules), yielded seed in the + proportion of 100 to 79. So that in every case the unions of + dissimilarly-coloured varieties of the same species were less fertile + than the unions of similarly-coloured varieties; when all the cases are + grouped together, the difference of fertility is as 86 to 100. Some + additional trials were made, and altogether thirty-six similarly-coloured + unions yielded thirty-five good <!-- Page 107 --><span class="pagenum"><a + name="page107"></a>{107}</span>capsules; whilst thirty-five + dissimilarly-coloured unions yielded only twenty-six good capsules. + Besides the foregoing experiments, the purple <i>V. phœniceum</i> + was crossed by a rose-coloured and a white variety of the same species; + these two varieties were also crossed together, and these several unions + yielded less seed than <i>V. phœniceum</i> by its own pollen. Hence + it follows from Mr. Scott's experiments, that in the genus Verbascum the + similarly and dissimilarly-coloured varieties of the same species behave, + when crossed, like closely allied but distinct species.<a name="NtA_229" + href="#Nt_229"><sup>[229]</sup></a></p> + + <p>This remarkable fact of the sexual affinity of similarly-coloured + varieties, as observed by Gärtner and Mr. Scott, may not be of very rare + occurrence; for the subject has not been attended to by others. The + following case is worth giving, partly to show how difficult it is to + avoid error. Dr. Herbert<a name="NtA_230" + href="#Nt_230"><sup>[230]</sup></a> has remarked that variously-coloured + double varieties of the hollyhock (<i>Althæa rosea</i>) may be raised + with certainty by seed from plants growing close together. I have been + informed that nurserymen who raise seed for sale do not separate their + plants; accordingly I procured seed of eighteen named varieties; of + these, eleven varieties produced sixty-two plants all perfectly true to + their kind; and seven produced forty-nine plants, half of which were true + and half false. Mr. Masters of Canterbury has given me a more striking + case; he saved seed from a great bed of twenty-four named varieties + planted in closely adjoining rows, and each variety reproduced itself + truly with only sometimes a shade of difference in tint. Now in the + hollyhock the pollen, which is abundant, is matured and nearly all shed + before the stigma of the same flower is ready to receive it;<a + name="NtA_231" href="#Nt_231"><sup>[231]</sup></a> and as bees covered + with pollen incessantly fly from plant to plant, it would appear that + adjoining varieties could not escape being crossed. As, however, this + does not occur, it appeared to me probable that the pollen <!-- Page 108 + --><span class="pagenum"><a name="page108"></a>{108}</span>of each + variety was prepotent on its own stigma over that of all other varieties. + But Mr. C. Turner of Slough, well known for his success in the + cultivation of this plant, informs me that it is the doubleness of the + flowers which prevents the bees gaining access to the pollen and stigma; + and he finds that it is difficult even to cross them artificially. + Whether this explanation will fully account for varieties in close + proximity propagating themselves so truly by seed, I do not know.</p> + + <p>The following cases are worth giving, as they relate to + monœcious forms, which do not require, and consequently have not + been injured by, castration. Girou de Buzareingues crossed what he + designates three varieties of gourd,<a name="NtA_232" + href="#Nt_232"><sup>[232]</sup></a> and asserts that their mutual + fertilisation is less easy in proportion to the difference which they + present. I am aware how imperfectly the forms in this group were until + recently known; but Sageret,<a name="NtA_233" + href="#Nt_233"><sup>[233]</sup></a> who ranked them according to their + mutual fertility, considers the three forms above alluded to as + varieties, as does a far higher authority, namely, M. Naudin.<a + name="NtA_234" href="#Nt_234"><sup>[234]</sup></a> Sageret<a + name="NtA_235" href="#Nt_235"><sup>[235]</sup></a> has observed that + certain melons have a greater tendency, whatever the cause may be, to + keep true than others; and M. Naudin, who has had such immense experience + in this group, informs me that he believes that certain varieties + intercross more readily than others of the same species; but he has not + proved the truth of this conclusion; the frequent abortion of the pollen + near Paris being one great difficulty. Nevertheless, he has grown close + together, during seven years, certain forms of Citrullus, which, as they + could be artificially crossed with perfect facility and produced fertile + offspring, are ranked as varieties; but these forms when not artificially + crossed kept true. Many other varieties, on the other hand, in the same + group cross with such facility, as M. Naudin repeatedly insists, that + without being grown far apart they cannot be kept in the least true.</p> + + <p>Another case, though somewhat different, may be here given, as it is + highly remarkable, and is established on excellent evidence. Kölreuter + minutely describes five varieties of the common tobacco,<a name="NtA_236" + href="#Nt_236"><sup>[236]</sup></a> which were reciprocally crossed, and + the offspring were intermediate in character and as fertile as their + parents: from this fact Kölreuter inferred that they are really + varieties; and no one, as far as I can discover, seems to have doubted + that such is the case. He also crossed reciprocally these five varieties + with <i>N. glutinosa</i>, and they yielded very sterile hybrids; but + those raised from the <i>var. perennis</i>, whether used as the father or + mother plant, were not so sterile as the hybrids from the four other + varieties.<a name="NtA_237" href="#Nt_237"><sup>[237]</sup></a> So that + the sexual <!-- Page 109 --><span class="pagenum"><a + name="page109"></a>{109}</span>capacity of this one variety has certainly + been in some degree modified, so as to approach in nature that of <i>N. + glutinosa</i>.<a name="NtA_238" href="#Nt_238"><sup>[238]</sup></a></p> + +</blockquote> + + <p>These facts with respect to plants show that in some few cases certain + varieties have had their sexual powers so far modified, that they cross + together less readily and yield less seed than other varieties of the + same species. We shall presently see that the sexual functions of most + animals and plants are eminently liable to be affected by the conditions + of life to which they are exposed; and hereafter we shall briefly discuss + the conjoint bearing of this and other facts on the difference in + fertility between crossed varieties and crossed species.</p> + +<p class="cenhead"><i>Domestication eliminates the tendency to Sterility which is general +with Species when crossed.</i></p> + + <p>This hypothesis was first propounded by Pallas,<a name="NtA_239" + href="#Nt_239"><sup>[239]</sup></a> and has been adopted by several + authors. I can find hardly any direct facts in its support; but + unfortunately no one has compared, in the case of either animals or + plants, the fertility of anciently domesticated varieties, when crossed + with a distinct species, with that of the wild parent-species when + similarly crossed. No one has compared, for instance, the fertility of + <i>Gallus bankiva</i> and of the domesticated fowl, when crossed with a + distinct species of Gallus or Phasianus; and the <!-- Page 110 --><span + class="pagenum"><a name="page110"></a>{110}</span>experiment would in all + cases be surrounded by many difficulties. Dureau de la Malle, who has so + closely studied classical literature, states<a name="NtA_240" + href="#Nt_240"><sup>[240]</sup></a> that in the time of the Romans the + common mule was produced with more difficulty than at the present day; + but whether this statement may be trusted I know not. A much more + important, though somewhat different, case is given by M. Groenland,<a + name="NtA_241" href="#Nt_241"><sup>[241]</sup></a> namely, that plants, + known from their intermediate character and sterility to be hybrids + between Ægilops and wheat, have perpetuated themselves under culture + since 1857, <i>with a rapid but varying increase of fertility in each + generation</i>. In the fourth generation the plants, still retaining + their intermediate character, had become as fertile as common cultivated + wheat.</p> + + <p>The indirect evidence in favour of the Pallasian doctrine appears to + me to be extremely strong. In the earlier chapters I have attempted to + show that our various breeds of dogs are descended from several wild + species; and this probably is the case with sheep. There can no longer be + any doubt that the Zebu or humped Indian ox belongs to a distinct species + from European cattle: the latter, moreover, are descended from two or + three forms, which may be called either species or wild races, but which + co-existed in a state of nature and kept distinct. We have good evidence + that our domesticated pigs belong to at least two specific types, <i>S. + scrofa</i> and <i>Indica</i>, which probably lived together in a wild + state in South-eastern Europe. Now, a widely-extended analogy leads to + the belief that if these several allied species, in the wild state or + when first reclaimed, had been crossed, they would have exhibited, both + in their first unions and in their hybrid offspring, some degree of + sterility. Nevertheless the several domesticated races descended from + them are now all, as far as can be ascertained, perfectly fertile + together. If this reasoning be trustworthy, and it is apparently sound, + we must admit the Pallasian doctrine that long-continued domestication + tends to eliminate that sterility which is natural to species when + crossed in their aboriginal state.</p> + +<p><!-- Page 111 --><span class="pagenum"><a name="page111"></a>{111}</span></p> + +<p class="cenhead"><i>On increased Fertility from Domestication and Cultivation.</i></p> + + <p>Increased fertility from domestication, without any reference to + crossing, may be here briefly considered. This subject bears indirectly + on two or three points connected with the modification of organic beings. + As Buffon long ago remarked,<a name="NtA_242" + href="#Nt_242"><sup>[242]</sup></a> domestic animals breed oftener in the + year and produce more young at a birth than wild animals of the same + species; they, also, sometimes breed at an earlier age. The case would + hardly have deserved further notice, had not some authors lately + attempted to show that fertility increases and decreases in an inverse + ratio with the amount of food. This strange doctrine has apparently + arisen from individual animals when supplied with an inordinate quantity + of food, and from plants of many kinds when grown on excessively rich + soil, as on a dunghill, becoming sterile; but to this latter point I + shall have occasion presently to return. With hardly an exception, our + domesticated animals, which have long been habituated to a regular and + copious supply of food, without the labour of searching for it, are more + fertile than the corresponding wild animals. It is notorious how + frequently cats and dogs breed, and how many young they produce at a + birth. The wild rabbit is said generally to breed four times yearly, and + to produce from four to eight young; the tame rabbit breeds six or seven + times yearly, and produces from four to eleven young. The ferret, though + generally so closely confined, is more prolific than its supposed wild + prototype. The wild sow is remarkably prolific, for she often breeds + twice in the year, and produces from four to eight and sometimes even + twelve young at a birth; but the domestic sow regularly breeds twice a + year, and would breed oftener if permitted; and a sow that produces less + than eight at a birth "is worth little, and the sooner she is fattened + for the butcher the better." The amount of food affects the fertility + even of the same individual: thus sheep, which on mountains never produce + more than one lamb at a birth, when brought <!-- Page 112 --><span + class="pagenum"><a name="page112"></a>{112}</span>down to lowland + pastures frequently bear twins. This difference apparently is not due to + the cold of the higher land, for sheep and other domestic animals are + said to be extremely prolific in Lapland. Hard living, also, retards the + period at which animals conceive; for it has been found disadvantageous + in the northern islands of Scotland to allow cows to bear calves before + they are four years old.<a name="NtA_243" + href="#Nt_243"><sup>[243]</sup></a></p> + +<blockquote class="b1n"> + + <p>Birds offer still better evidence of increased fertility from + domestication: the hen of the wild <i>Gallus bankiva</i> lays from six to + ten eggs, a number which would be thought nothing of with the domestic + hen. The wild duck lays from five to ten eggs; the tame one in the course + of the year from eighty to one hundred. The wild grey-lag goose lays from + five to eight eggs; the tame from thirteen to eighteen, and she lays a + second time; as Mr. Dixon has remarked, "high-feeding, care, and moderate + warmth induce a habit of prolificacy which becomes in some measure + hereditary." Whether the semi-domesticated dovecot pigeon is more fertile + than the wild rock-pigeon <i>C. livia</i>, I know not; but the more + thoroughly domesticated breeds are nearly twice as fertile as dovecots: + the latter, however, when caged and highly fed, become equally fertile + with house pigeons. The peahen alone of domesticated birds is rather more + fertile, according to some accounts, when wild in its native Indian home, + than when domesticated in Europe and exposed to our much colder + climate.<a name="NtA_244" href="#Nt_244"><sup>[244]</sup></a></p> + + <p>With respect to plants, no one would expect wheat to tiller more, and + each ear to produce more grain, in poor than in rich soil; or to get in + poor soil a heavy crop of peas or beans. Seeds vary so much in number + <!-- Page 113 --><span class="pagenum"><a + name="page113"></a>{113}</span>that it is difficult to estimate them; but + on comparing beds of carrots saved for seed in a nursery garden with wild + plants, the former seemed to produce about twice as much seed. Cultivated + cabbages yielded thrice as many pods by measure as wild cabbages from the + rocks of South Wales. The excess of berries produced by the cultivated + Asparagus in comparison with the wild plant is enormous. No doubt many + highly cultivated plants, such as pears, pineapples, bananas, sugar-cane, + &c., are nearly or quite sterile; and I am inclined to attribute this + sterility to excess of food and to other unnatural conditions; but to + this subject I shall presently recur.</p> + +</blockquote> + + <p>In some cases, as with the pig, rabbit, &c., and with those plants + which are valued for their seed, the direct selection of the more fertile + individuals has probably much increased their fertility; and in all cases + this may have occurred indirectly, from the better chance of the more + numerous offspring produced by the more fertile individuals having + survived. But with cats, ferrets, and dogs, and with plants like carrots, + cabbages, and asparagus, which are not valued for their prolificacy, + selection can have played only a subordinate part; and their increased + fertility must be attributed to the more favourable conditions of life + under which they have long existed.</p> + +<hr class="full" /> + +<p><!-- Page 114 --><span class="pagenum"><a name="page114"></a>{114}</span></p> + +<h3>CHAPTER XVII.</h3> + +<p class="cenhead">ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL +EFFECTS OF CLOSE INTERBREEDING.</p> + +<blockquote class="b1n"> + + <p><span class="scac">DEFINITION OF CLOSE + INTERBREEDING</span>—<span class="scac">AUGMENTATION OF MORBID + TENDENCIES</span>—<span class="scac">GENERAL EVIDENCE ON THE GOOD + EFFECTS DERIVED FROM CROSSING, AND ON THE EVIL EFFECTS FROM CLOSE + INTERBREEDING</span>—<span class="scac">CATTLE, CLOSELY INTERBRED; + HALF-WILD CATTLE LONG KEPT IN THE SAME PARKS</span>—<span + class="scac">SHEEP</span>—<span + class="scac">FALLOW-DEER</span>—<span + class="scac">DOGS</span>—<span + class="scac">RABBITS</span>—<span + class="scac">PIGS</span>—<span class="scac">MAN, ORIGIN OF HIS + ABHORRENCE OF INCESTUOUS MARRIAGES</span>—<span + class="scac">FOWLS</span>—<span + class="scac">PIGEONS</span>—<span + class="scac">HIVE-BEES</span>—<span class="scac">PLANTS, GENERAL + CONSIDERATIONS ON THE BENEFITS DERIVED FROM CROSSING</span>—<span + class="scac">MELONS, FRUIT-TREES, PEAS, CABBAGES, WHEAT, AND + FOREST-TREES</span>—<span class="scac">ON THE INCREASED SIZE OF + HYBRID PLANTS, NOT EXCLUSIVELY DUE TO THEIR STERILITY</span>—<span + class="scac">ON CERTAIN PLANTS WHICH EITHER NORMALLY OR ABNORMALLY ARE + SELF-IMPOTENT, BUT ARE FERTILE, BOTH ON THE MALE AND FEMALE SIDE, WHEN + CROSSED WITH DISTINCT INDIVIDUALS EITHER OF THE SAME OR ANOTHER + SPECIES</span>—<span class="scac">CONCLUSION.</span></p> + +</blockquote> + + <p>The gain in constitutional vigour, derived from an occasional cross + between individuals of the same variety, but belonging to distinct + families, or between distinct varieties, has not been so largely or so + frequently discussed, as have the evil effects of too close + interbreeding. But the former point is the more important of the two, + inasmuch as the evidence is more decisive. The evil results from close + interbreeding are difficult to detect, for they accumulate slowly, and + differ much in degree with different species; whilst the good effects + which almost invariably follow a cross are from the first manifest. It + should, however, be clearly understood that the advantage of close + interbreeding, as far as the retention of character is concerned, is + indisputable, and often outweighs the evil of a slight loss of + constitutional vigour. In relation to the subject of domestication, the + whole question is of some importance, as too close interbreeding + interferes with the improvement of old races, and especially with the + formation of new ones. It is important as indirectly bearing on + Hybridism; and perhaps on the extinction of species, when any form has + become so rare that only a few individuals <!-- Page 115 --><span + class="pagenum"><a name="page115"></a>{115}</span>remain within a + confined area. It bears in an important manner on the influence of free + intercrossing, in obliterating individual differences, and thus giving + uniformity of character to the individuals of the same race or species; + for if additional vigour and fertility be thus gained, the crossed + offspring will multiply and prevail, and the ultimate result will be far + greater than otherwise would have occurred. Lastly, the question is of + high interest, as bearing on mankind. Hence I shall discuss this subject + at full length. As the facts which prove the evil effects of close + interbreeding are more copious, though less decisive, than those on the + good effects of crossing, I shall, under each group of beings, begin with + the former.</p> + + <p>There is no difficulty in defining what is meant by a cross; but this + is by no means easy in regard to "breeding in and in" or "too close + interbreeding," because, as we shall see, different species of animals + are differently affected by the same degree of interbreeding. The pairing + of a father and daughter, or mother and son, or brothers and sisters, if + carried on during several generations, is the closest possible form of + interbreeding. But some good judges, for instance Sir J. Sebright, + believe that the pairing of a brother and sister is closer than that of + parents and children; for when the father is matched with his daughter he + crosses, as is said, with only half his own blood. The consequences of + close interbreeding carried on for too long a time, are, as is generally + believed, loss of size, constitutional vigour, and fertility, sometimes + accompanied by a tendency to malformation. Manifest evil does not usually + follow from pairing the nearest relations for two, three, or even four + generations; but several causes interfere with our detecting the + evil—such as the deterioration being very gradual, and the + difficulty of distinguishing between such direct evil and the inevitable + augmentation of any morbid tendencies which may be latent or apparent in + the related parents. On the other hand, the benefit from a cross, even + when there has not been any very close interbreeding, is almost + invariably at once conspicuous. There is reason to believe, and this was + the opinion of that most experienced observer Sir J. Sebright,<a + name="NtA_245" href="#Nt_245"><sup>[245]</sup></a> that the evil effects + of close interbreeding may be checked by the related individuals <!-- + Page 116 --><span class="pagenum"><a name="page116"></a>{116}</span>being + separated during a few generations and exposed to different conditions of + life.</p> + + <p>That evil directly follows from any degree of close interbreeding has + been denied by many persons; but rarely by any practical breeder; and + never, as far as I know, by one who has largely bred animals which + propagate their kind quickly. Many physiologists attribute the evil + exclusively to the combination and consequent increase of morbid + tendencies common to both parents: that this is an active source of + mischief there can be no doubt. It is unfortunately too notorious that + men and various domestic animals endowed with a wretched constitution, + and with a strong hereditary disposition to disease, if not actually ill, + are fully capable of procreating their kind. Close interbreeding, on the + other hand, induces sterility; and this indicates something quite + distinct from the augmentation of morbid tendencies common to both + parents. The evidence immediately to be given convinces me that it is a + great law of nature, that all organic beings profit from an occasional + cross with individuals not closely related to them in blood; and that, on + the other hand, long-continued close interbreeding is injurious.</p> + + <p>Various general considerations have had much influence in leading me + to this conclusion; but the reader will probably rely more on special + facts and opinions. The authority of experienced observers, even when + they do not advance the grounds of their belief, is of some little value. + Now almost all men who have bred many kinds of animals and have written + on the subject, such as Sir J. Sebright, Andrew Knight, &c.,<a + name="NtA_246" href="#Nt_246"><sup>[246]</sup></a> have expressed the + strongest conviction on the impossibility of long-continued close + interbreeding. Those who have compiled works on agriculture, and have + associated much with breeders, such as the sagacious Youatt, Low, + &c., have strongly declared their opinion to the same effect. Prosper + Lucas, trusting largely to French authorities, has come to a similar + conclusion. The distinguished German agriculturist Hermann von Nathusius, + who has written the most able treatise on this subject which I have met + with, concurs; and as I shall have to quote from <!-- Page 117 --><span + class="pagenum"><a name="page117"></a>{117}</span>this treatise, I may + state that Nathusius is not only intimately acquainted with works on + agriculture in all languages, and knows the pedigrees of our British + breeds better than most Englishmen, but has imported many of our improved + animals, and is himself an experienced breeder.</p> + + <p>Evidence of the evil effects of close interbreeding can most readily + be acquired in the case of animals, such as fowls, pigeons, &c., + which propagate quickly, and, from being kept in the same place, are + exposed to the same conditions. Now I have inquired of very many breeders + of these birds, and I have hitherto not met with a single man who was not + thoroughly convinced that an occasional cross with another strain of the + same sub-variety was absolutely necessary. Most breeders of + highly-improved or fancy birds value their own strain, and are most + unwilling, at the risk, in their opinion, of deterioration, to make a + cross. The purchase of a first-rate bird of another strain is expensive, + and exchanges are troublesome; yet all breeders, as far as I can hear, + excepting those who keep large stocks at different places for the sake of + crossing, are driven after a time to take this step.</p> + + <p>Another general consideration which has had great influence on my mind + is, that with all hermaphrodite animals and plants, which it might have + been thought would have perpetually fertilised themselves, and thus have + been subjected for long ages to the closest interbreeding, there is no + single species, as far as I can discover, in which the structure ensures + self-fertilisation. On the contrary, there are in a multitude of cases, + as briefly stated in the fifteenth chapter, manifest adaptations which + favour or inevitably lead to an occasional cross between one + hermaphrodite and another of the same species; and these adaptive + structures are utterly purposeless, as far as we can see, for any other + end.</p> + +<blockquote class="b1n"> + + <p>With <i>Cattle</i> there can be no doubt that extremely close + interbreeding may be long carried on, advantageously with respect to + external characters and with no manifestly apparent evil as far as + constitution is concerned. The same remark is applicable to sheep. + Whether these animals have gradually been rendered less susceptible than + others to this evil, in order to permit them to live in herds,—a + habit which leads the old and vigorous males to expel all intruders, and + in consequence often to pair with their own daughters, I will not pretend + to decide. The case of Bakewell's Long-horns, which were closely + interbred for a long period, has often been <!-- Page 118 --><span + class="pagenum"><a name="page118"></a>{118}</span>quoted; yet Youatt + says<a name="NtA_247" href="#Nt_247"><sup>[247]</sup></a> the breed "had + acquired a delicacy of constitution inconsistent with common management," + and "the propagation of the species was not always certain." But the + Shorthorns offer the most striking case of close interbreeding; for + instance, the famous bull Favourite (who was himself the offspring of a + half-brother and sister from Foljambe) was matched with his own daughter, + granddaughter, and great-granddaughter; so that the produce of this last + union, or the great-great-granddaughter, had 15-16ths, or 93.75 per cent. + of the blood of Favourite in her veins. This cow was matched with the + bull Wellington, having 62.5 per cent. of Favourite blood in his veins, + and produced Clarissa; Clarissa was matched with the bull Lancaster, + having 68.75 of the same blood, and she yielded valuable offspring.<a + name="NtA_248" href="#Nt_248"><sup>[248]</sup></a> Nevertheless Collings, + who reared these animals, and was a strong advocate for close breeding, + once crossed his stock with a Galloway, and the cows from this cross + realised the highest prices. Bates's herd was esteemed the most + celebrated in the world. For thirteen years he bred most closely in and + in; but during the next seventeen years, though he had the most exalted + notion of the value of his own stock, he thrice infused fresh blood into + his herd: it is said that he did this, not to improve the form of his + animals, but on account of their lessened fertility. Mr. Bates's own + view, as given by a celebrated breeder,<a name="NtA_249" + href="#Nt_249"><sup>[249]</sup></a> was, that "to breed in and in from a + bad stock was ruin and devastation; yet that the practice may be safely + followed within certain limits when the parents so related are descended + from first-rate animals." We thus see that there has been extremely close + interbreeding with Shorthorns; but Nathusius, after the most careful + study of their pedigrees, says that he can find no instance of a breeder + who has strictly followed this practice during his whole life. From this + study and his own experience, he concludes that close interbreeding is + necessary to ennoble the stock; but that in effecting this the greatest + care is necessary, on account of the tendency to infertility and + weakness. It may be added, that another high authority<a name="NtA_250" + href="#Nt_250"><sup>[250]</sup></a> asserts that many more calves are + born cripples from Shorthorns than from other and less closely interbred + races of cattle.</p> + + <p>Although by carefully selecting the best animals (as Nature + effectually does by the law of battle) close interbreeding may be long + carried on with cattle, yet the good effects of a cross between almost + any two breeds is at once shown by the greater size and vigour of the + offspring; as Mr. Spooner writes to me, "crossing distinct breeds + certainly improves cattle for the butcher." Such crossed animals are of + course of no value to the breeder; but they have been raised during many + years in several <!-- Page 119 --><span class="pagenum"><a + name="page119"></a>{119}</span>parts of England to be slaughtered;<a + name="NtA_251" href="#Nt_251"><sup>[251]</sup></a> and their merit is now + so fully recognised, that at fat-cattle shows a separate class has been + formed for their reception. The best fat ox at the great show at + Islington in 1862 was a crossed animal.</p> + + <p>The half-wild cattle, which have been kept in British parks probably + for 400 or 500 years, or even for a longer period, have been advanced by + Culley and others as a case of long-continued interbreeding within the + limits of the same herd without any consequent injury. With respect to + the cattle at Chillingham, the late Lord Tankerville owned that they were + bad breeders.<a name="NtA_252" href="#Nt_252"><sup>[252]</sup></a> The + agent, Mr. Hardy, estimates (in a letter to me, dated May, 1861) that in + the herd of about fifty the average number annually slaughtered, killed + by fighting, and dying, is about ten, or one in five. As the herd is kept + up to nearly the same average number, the annual rate of increase must be + likewise about one in five. The bulls, I may add, engage in furious + battles, of which battles the present Lord Tankerville has given me a + graphic description, so that there will always be rigorous selection of + the most vigorous males. I procured in 1855 from Mr. D. Gardner, agent to + the Duke of Hamilton, the following account of the wild cattle kept in + the Duke's park in Lanarkshire, which is about 200 acres in extent. The + number of cattle varies from sixty-five to eighty; and the number + annually killed (I presume by all causes) is from eight to ten; so that + the annual rate of increase can hardly be more than one in six. Now in + South America, where the herds are half-wild, and therefore offer a + nearly fair standard of comparison, according to Azara the natural + increase of the cattle on an estancia is from one-third to one-fourth of + the total number, or one in between three and four; and this, no doubt, + applies exclusively to adult animals fit for consumption. Hence the + half-wild British cattle which have long interbred within the limits of + the same herd are relatively far less fertile. Although in an unenclosed + country like Paraguay there must be some crossing between the different + herds, yet even there the inhabitants believe that the occasional + introduction of animals from distant localities is necessary to prevent + "degeneration in size and diminution of fertility."<a name="NtA_253" + href="#Nt_253"><sup>[253]</sup></a> The decrease in size from ancient + times in the Chillingham and Hamilton cattle must have been prodigious, + for Professor Rütimeyer has shown that they are almost certainly the + descendants of the gigantic <i>Bos primigenius</i>. No doubt this + decrease in size may be largely attributed to less favourable conditions + of life; yet animals roaming over large parks, and fed during severe + winters, can hardly be considered as placed under very unfavourable + conditions.</p> + + <p>With <i>Sheep</i> there has often been long-continued interbreeding + within the limits of the same flock; but whether the nearest relations + have been matched so frequently as in the case of Shorthorn cattle, I do + not know. The Messrs. Brown during fifty years have never infused fresh + blood into their excellent flock of Leicesters. Since 1810 Mr. Barford + has acted on the same principle with the Foscote flock. He asserts that + half a century <!-- Page 120 --><span class="pagenum"><a + name="page120"></a>{120}</span>of experience has convinced him that when + two nearly related animals are quite sound in constitution, in-and-in + breeding does not induce degeneracy; but he adds that he "does not pride + himself on breeding from the nearest affinities." In France the Naz flock + has been bred for sixty years without the introduction of a single + strange ram.<a name="NtA_254" href="#Nt_254"><sup>[254]</sup></a> + Nevertheless, most great breeders of sheep have protested against close + interbreeding prolonged for too great a length of time.<a name="NtA_255" + href="#Nt_255"><sup>[255]</sup></a> The most celebrated of recent + breeders, Jonas Webb, kept five separate families to work on, thus + "retaining the requisite distance of relationship between the sexes."<a + name="NtA_256" href="#Nt_256"><sup>[256]</sup></a></p> + + <p>Although by the aid of careful selection the near interbreeding of + sheep may be long continued without any manifest evil, yet it has often + been the practice with farmers to cross distinct breeds to obtain animals + for the butcher, which plainly shows that good is derived from this + practice. Mr. Spooner sums up his excellent Essay on Crossing by + asserting that there is a direct pecuniary advantage in judicious + cross-breeding, especially when the male is larger than the female. A + former celebrated breeder, Lord Somerville, distinctly states that his + half-breeds from Ryelands and Spanish sheep were larger animals than + either the pure Ryelands or pure Spanish sheep.<a name="NtA_257" + href="#Nt_257"><sup>[257]</sup></a></p> + + <p>As some of our British parks are ancient, it occurred to me that there + must have been long-continued close interbreeding with the fallow deer + (<i>Cervus dama</i>) kept in them; but on inquiry I find that it is a + common practice to infuse new blood by procuring bucks from other parks. + Mr. Shirley,<a name="NtA_258" href="#Nt_258"><sup>[258]</sup></a> who has + carefully studied the management of deer, admits that in some parks there + has been no admixture of foreign blood from a time beyond the memory of + man. But he concludes "that in the end the constant breeding in-and-in is + sure to tell to the disadvantage of the whole herd, though it may take a + very long time to prove it; moreover, when we find, as is very constantly + the case, that the introduction of fresh blood has been of the very + greatest use to deer, both by improving their size and appearance, and + particularly by being of service in removing the taint of 'rickback,' if + not of other diseases, to which deer are sometimes subject when the blood + has not been changed, there can, I think, be no doubt but that a + judicious cross with a good stock is of the greatest consequence, and is + indeed essential, sooner or later, to the prosperity of every + well-ordered park."</p> + + <p>Mr. Meynell's famous foxhounds have been adduced, as showing that no + ill effects follow from close interbreeding; and Sir J. Sebright + ascertained from him that he frequently bred from father and daughter, + mother and <!-- Page 121 --><span class="pagenum"><a + name="page121"></a>{121}</span>son, and sometimes even from brothers and + sisters. Sir J. Sebright, however, declares,<a name="NtA_259" + href="#Nt_259"><sup>[259]</sup></a> that by breeding <i>in-and-in</i>, by + which he means matching brothers and sisters, he has actually seen strong + spaniels become weak and diminutive lapdogs. The Rev. W. D. Fox has + communicated to me the case of a small lot of bloodhounds, long kept in + the same family, which had become very bad breeders, and nearly all had a + bony enlargement in the tail. A single cross with a distinct strain of + bloodhounds restored their fertility, and drove away the tendency to + malformation in the tail. I have heard the particulars of another case + with bloodhounds, in which the female had to be held to the male. + Considering how rapid is the natural increase of the dog, it is difficult + to understand the high price of most highly improved breeds, which almost + implies long-continued close interbreeding, except on the belief that + this process lessens fertility and increases liability to distemper and + other diseases. A high authority, Mr. Scrope, attributes the rarity and + deterioration in size of the Scotch deerhound (the few individuals now + existing throughout the country being all related) in large part to close + interbreeding.</p> + + <p>With all highly-bred animals there is more or less difficulty in + getting them to procreate quickly, and all suffer much from delicacy of + constitution; but I do not pretend that these effects ought to be wholly + attributed to close interbreeding. A great judge of rabbits<a + name="NtA_260" href="#Nt_260"><sup>[260]</sup></a> says, "the long-eared + does are often too highly bred or forced in their youth to be of much + value as breeders, often turning out barren or bad mothers." Again: "Very + long-eared bucks will also sometimes prove barren." These highly-bred + rabbits often desert their young, so that it is necessary to have + nurse-rabbits.</p> + + <p>With <i>Pigs</i> there is more unanimity amongst breeders on the evil + effects of close interbreeding than, perhaps, with any other large + animal. Mr. Druce, a great and successful breeder of the Improved + Oxfordshires (a crossed race), writes, "without a change of boars of a + different tribe, but of the same breed, constitution cannot be + preserved." Mr. Fisher Hobbs, the raiser of the celebrated Improved Essex + breed, divided his stock into three separate families, by which means he + maintained the breed for more than twenty years, "by judicious selection + from the <i>three distinct families</i>."<a name="NtA_261" + href="#Nt_261"><sup>[261]</sup></a> Lord Western was the first importer + of a Neapolitan boar and sow. "From this pair he bred in-and-in, until + the breed was in danger of becoming extinct, a sure result (as Mr. Sidney + remarks) of in-and-in breeding." Lord Western then crossed his Neapolitan + pigs with the old Essex, and made the first great step towards the + Improved Essex breed. Here is a more interesting case. Mr. J. Wright, + well known as a breeder, crossed<a name="NtA_262" + href="#Nt_262"><sup>[262]</sup></a> the same boar with the daughter, + granddaughter, and great-granddaughter, and so on for seven generations. + The result was, that in many instances the offspring failed to breed; in + others they produced few that lived; and of the latter many were idiotic, + without sense <!-- Page 122 --><span class="pagenum"><a + name="page122"></a>{122}</span>even to suck, and when attempting to move + could not walk straight. Now it deserves especial notice, that the two + last sows produced by this long course of interbreeding were sent to + other boars, and they bore several litters of healthy pigs. The best sow + in external appearance produced during the whole seven generations was + one in the last stage of descent; but the litter consisted of this one + sow. She would not breed to her sire, yet bred at the first trial to a + stranger in blood. So that, in Mr. Wright's case, long-continued and + extremely close interbreeding did not affect the external form or merit + of the young; but with many of them the general constitution and mental + powers, and especially the reproductive functions, were seriously + affected.</p> + + <p>Nathusius gives<a name="NtA_263" href="#Nt_263"><sup>[263]</sup></a> + an analogous and even more striking case: he imported from England a + pregnant sow of the large Yorkshire breed, and bred the product closely + in-and-in for three generations: the result was unfavourable, as the + young were weak in constitution, with impaired fertility. One of the + latest sows, which he esteemed a good animal, produced, when paired with + her own uncle (who was known to be productive with sows of other breeds), + a litter of six, and a second time a litter of only five weak young pigs. + He then paired this sow with a boar of a small black breed, which he had + likewise imported from England, and which boar, when matched with sows of + his own breed, produced from seven to nine young: now, the sow of the + large breed, which was so unproductive when paired with her own uncle, + yielded to the small black boar, in the first litter twenty-one, and in + the second litter eighteen young pigs; so that in one year she produced + thirty-nine fine young animals!</p> + + <p>As in the case of several other animals already mentioned, even when + no injury is perceptible from moderately close interbreeding, yet, to + quote the words of Mr. Coate, a most successful breeder (who five times + won the annual gold medal of the Smithfield Club Show for the best pen of + pigs), "Crosses answer well for profit to the farmer, as you get more + constitution and quicker growth; but for me, who sell a great number of + pigs for breeding purposes, I find it will not do, as it requires many + years to get anything like purity of blood again."<a name="NtA_264" + href="#Nt_264"><sup>[264]</sup></a></p> + +</blockquote> + + <p>Before passing on to Birds, I ought to refer to man, though I am + unwilling to enter on this subject, as it is surrounded by natural + prejudices. It has moreover been discussed by various authors under many + points of view.<a name="NtA_265" href="#Nt_265"><sup>[265]</sup></a> Mr. + Tylor<a name="NtA_266" href="#Nt_266"><sup>[266]</sup></a> has shown <!-- + Page 123 --><span class="pagenum"><a name="page123"></a>{123}</span>that + with widely different races, in the most distant quarters of the world, + marriages between relations—even between distant + relations—have been strictly prohibited. A few exceptional cases + can be specified, especially with royal families; and these have been + enlarged on in a learned article<a name="NtA_267" + href="#Nt_267"><sup>[267]</sup></a> by Mr. W. Adam, and formerly in 1828 + by Hofacker. Mr. Tylor is inclined to believe that the almost universal + prohibition of closely-related marriages has arisen from their evil + effects having been observed, and he ingeniously explains some apparent + anomalies in the prohibition not extending equally to the relations on + both the male and female side. He admits, however, that other causes, + such as the extension of friendly alliances, may have come into play. Mr. + W. Adam, on the other hand, concludes that related marriages are + prohibited and viewed with repugnance from the confusion which would thus + arise in the descent of property, and from other still more recondite + reasons; but I cannot accept this view, seeing that the savages of + Australia and South America,<a name="NtA_268" + href="#Nt_268"><sup>[268]</sup></a> who have no property to bequeath or + fine moral feelings to confuse, hold the crime of incest in + abhorrence.</p> + + <p>It would be interesting to know, if it could be ascertained, as + throwing light on this question with respect to man, what occurs with the + higher anthropomorphous apes—whether the young males and females + soon wander away from their parents, or whether the old males become + jealous of their sons and expel them, or whether any inherited + instinctive feeling, from being beneficial, has been generated, leading + the young males and females of the same family to prefer pairing with + distinct families, and to dislike pairing with each other. A considerable + body of evidence has already been advanced, showing that the offspring + from parents which are not related are more vigorous and fertile than + those from parents which are closely related; hence any slight feeling, + arising from the sexual excitement of novelty or other cause, which led + to the former rather than to the latter unions, would be augmented + through natural selection, and thus might become instinctive; for those + individuals which had an innate preference of this kind would increase in + number. It seems more probable, that degraded savages should <!-- Page + 124 --><span class="pagenum"><a name="page124"></a>{124}</span>thus + unconsciously have acquired their dislike and even abhorrence of + incestuous marriages, rather than that they should have discovered by + reasoning and observation the evil results. The abhorrence occasionally + failing is no valid argument against the feeling being instinctive, for + any instinct may occasionally fail or become vitiated, as sometimes + occurs with parental love and the social sympathies. In the case of man, + the question whether evil follows from close interbreeding will probably + never be answered by direct evidence, as he propagates his kind so slowly + and cannot be subjected to experiment; but the almost universal practice + of all races at all times of avoiding closely-related marriages is an + argument of considerable weight; and whatever conclusion we arrive at in + regard to the higher animals may be safely extended to man.</p> + +<blockquote class="b1n"> + + <p>Turning now to Birds: in the case of the <i>Fowl</i> a whole array of + authorities could be given against too close interbreeding. Sir J. + Sebright positively asserts that he made many trials, and that his fowls, + when thus treated, became long in the legs, small in the body, and bad + breeders.<a name="NtA_269" href="#Nt_269"><sup>[269]</sup></a> He + produced the famous Sebright Bantams by complicated crosses, and by + breeding in-and-in; and since his time there has been much close + interbreeding with these Bantams; and they are now notoriously bad + breeders. I have seen Silver Bantams, directly descended from his stock, + which had become almost as barren as hybrids; for not a single chicken + had been that year hatched from two full nests of eggs. Mr. Hewitt says + that with these Bantams the sterility of the male stands, with rare + exceptions, in the closest relation with their loss of certain secondary + male characters: he adds, "I have noticed, as a general rule, that even + the slightest deviation from feminine character in the tail of the male + Sebright—say the elongation by only half an inch of the two + principal tail-feathers—brings with it improved probability of + increased fertility."<a name="NtA_270" + href="#Nt_270"><sup>[270]</sup></a></p> + + <p>Mr. Wright states<a name="NtA_271" href="#Nt_271"><sup>[271]</sup></a> + that Mr. Clark, "whose fighting-cocks were so notorious, continued to + breed from his own kind till they lost their disposition to fight, but + stood to be cut up without making any resistance, and were so reduced in + size as to be under those weights required for the best prizes; but on + obtaining a cross from Mr. Leighton, they again resumed their former + courage and weight." It should be borne in mind that game-cocks before + they fought were always weighed, so that nothing was left to the + imagination about any reduction or increase of <!-- Page 125 --><span + class="pagenum"><a name="page125"></a>{125}</span>weight. Mr. Clark does + not seem to have bred from brothers and sisters, which is the most + injurious kind of union; and he found, after repeated trials, that there + was a greater reduction in weight in the young from a father paired with + his daughter, than from a mother with her son. I may add that Mr. Eyton, + of Eyton, the well-known ornithologist, who is a large breeder of Grey + Dorkings, informs me that they certainly diminish in size, and become + less prolific, unless a cross with another strain is occasionally + obtained. So it is with Malays, according to Mr. Hewitt, as far as size + is concerned.<a name="NtA_272" href="#Nt_272"><sup>[272]</sup></a></p> + + <p>An experienced writer<a name="NtA_273" + href="#Nt_273"><sup>[273]</sup></a> remarks that the same amateur, as is + well known, seldom long maintains the superiority of his birds; and this, + he adds, undoubtedly is due to all his stock "being of the same blood;" + hence it is indispensable that he should occasionally procure a bird of + another strain. But this is not necessary with those who keep a stock of + fowls at different stations. Thus, Mr. Ballance, who has bred Malays for + thirty years, and has won more prizes with these birds than any other + fancier in England, says that breeding in-and-in does not necessarily + cause deterioration; "but all depends upon how this is managed." "My plan + has been to keep about five or six distinct runs, and to rear about two + hundred or three hundred chickens each year, and select the best birds + from each run for crossing. I thus secure sufficient crossing to prevent + deterioration."<a name="NtA_274" href="#Nt_274"><sup>[274]</sup></a></p> + + <p>We thus see that there is almost complete unanimity with + poultry-breeders that, when fowls are kept at the same place, evil + quickly follows from interbreeding carried on to an extent which would be + disregarded in the case of most quadrupeds. On the other hand, it is a + generally received opinion that cross-bred chickens are the hardiest and + most easily reared.<a name="NtA_275" href="#Nt_275"><sup>[275]</sup></a> + Mr. Tegetmeier, who has carefully attended to poultry of all breeds, + says<a name="NtA_276" href="#Nt_276"><sup>[276]</sup></a> that Dorking + hens, allowed to run with Houdan or Crevecœur cocks, "produce in + the early spring chickens that for size, hardihood, early maturity, and + fitness for the market, surpass those of any pure breed that we have ever + raised." Mr. Hewitt gives it as a general rule with fowls, that crossing + the breed increases their size. He makes this remark after stating that + hybrids from the pheasant and fowl are considerably larger than either + progenitor: so again, hybrids from the male golden pheasant and hen + common pheasant "are of far larger size than either parent-bird."<a + name="NtA_277" href="#Nt_277"><sup>[277]</sup></a> To this subject of the + increased size of hybrids I shall presently return.</p> + + <p>With <i>Pigeons</i>, breeders are unanimous, as previously stated, + that it is absolutely indispensable, notwithstanding the trouble and + expense thus caused, occasionally to cross their much-prized birds with + individuals of another strain, but belonging, of course, to the same + variety. It deserves <!-- Page 126 --><span class="pagenum"><a + name="page126"></a>{126}</span>notice that, when large size is one of the + desired characters, as with pouters,<a name="NtA_278" + href="#Nt_278"><sup>[278]</sup></a> the evil effects of close + interbreeding are much sooner perceived than when small birds, such as + short-faced tumblers, are valued. The extreme delicacy of the high fancy + breeds, such as these tumblers and improved English carriers, is + remarkable; they are liable to many diseases, and often die in the egg or + during the first moult; and their eggs have generally to be hatched under + foster-mothers. Although these highly-prized birds have invariably been + subjected to much close interbreeding, yet their extreme delicacy of + constitution cannot perhaps be thus fully explained. Mr. Yarrell informed + me that Sir J. Sebright continued closely interbreeding some owl-pigeons, + until from their extreme sterility he as nearly as possible lost the + whole family. Mr. Brent<a name="NtA_279" + href="#Nt_279"><sup>[279]</sup></a> tried to raise a breed of trumpeters, + by crossing a common pigeon, and recrossing the daughter, granddaughter, + great-granddaughter, and great-great-granddaughter, with the same male + trumpeter, until he obtained a bird with <sup>15</sup>/<sub>16</sub>ths + of trumpeter's blood; but then the experiment failed, for "breeding so + close stopped reproduction." The experienced Neumeister<a name="NtA_280" + href="#Nt_280"><sup>[280]</sup></a> also asserts that the offspring from + dovecotes and various other breeds are "generally very fertile and hardy + birds:" so again, MM. Boitard and Corbié,<a name="NtA_281" + href="#Nt_281"><sup>[281]</sup></a> after forty-five years' experience, + recommend persons to cross their breeds for amusement; for, if they fail + to make interesting birds, they will succeed under an economical point of + view, "as it is found that mongrels are more fertile than pigeons of pure + race."</p> + + <p>I will refer only to one other animal, namely, the Hive-bee, because a + distinguished entomologist has advanced this as a case of inevitable + close interbreeding. As the hive is tenanted by a single female, it might + have been thought that her male and female offspring would always have + bred together, more especially as bees of different hives are hostile to + each other; a strange worker being almost always attacked when trying to + enter another hive. But Mr. Tegetmeier has shown<a name="NtA_282" + href="#Nt_282"><sup>[282]</sup></a> that this instinct does not apply to + drones, which are permitted to enter any hive; so that there is no <i>à + priori</i> improbability of a queen receiving a foreign drone. The fact + of the union invariably and necessarily taking place on the wing, during + the queen's nuptial flight, seems to be a special provision against + continued interbreeding. However this may be, experience has shown, since + the introduction of the yellow-banded Ligurian race into Germany and + England, that bees freely cross: Mr. Woodbury, who introduced Ligurian + bees into Devonshire, found during a single season that three stocks, at + distances of from one to two miles from his hives, were crossed by his + drones. In one case the Ligurian drones must have flown over the city of + Exeter, and over several intermediate hives. On another occasion several + common black queens were crossed by Ligurian drones at a distance of from + one to three and a half miles.<a name="NtA_283" + href="#Nt_283"><sup>[283]</sup></a></p> + +</blockquote> + +<p><!-- Page 127 --><span class="pagenum"><a name="page127"></a>{127}</span></p> + +<p class="cenhead"><i>Plants.</i></p> + +<blockquote class="b1n"> + + <p>When a single plant of a new species is introduced into any country, + if propagated by seed, many individuals will soon be raised, so that if + the proper insects be present there will be crossing. With + newly-introduced trees or other plants not propagated by seed we are not + here concerned. With old-established plants it is an almost universal + practice occasionally to make exchanges of seed, by which means + individuals which have been exposed to different conditions of + life,—and this, as we have seen, diminishes the evil from close + interbreeding,—will occasionally be introduced into each + district.</p> + + <p>Experiments have not been tried on the effects of fertilising flowers + with their own pollen during <i>several</i> generations. But we shall + presently see that certain plants, either normally or abnormally, are + more or less sterile, even in the first generation, when fertilised by + their own pollen. Although nothing is directly known on the evil effects + of long-continued close interbreeding with plants, the converse + proposition that great good is derived from crossing is well + established.</p> + + <p>With respect to the crossing of individuals belonging to the same + sub-variety, Gärtner, whose accuracy and experience exceeded that of all + other hybridisers, states<a name="NtA_284" + href="#Nt_284"><sup>[284]</sup></a> that he has many times observed good + effects from this step, especially with exotic genera, of which the + fertility is somewhat impaired, such as Passiflora, Lobelia, and Fuchsia. + Herbert also says,<a name="NtA_285" href="#Nt_285"><sup>[285]</sup></a> + "I am inclined to think that I have derived advantage from impregnating + the flower from which I wished to obtain seed with pollen from another + individual of the same variety, or at least from another flower, rather + than with its own." Again, Professor Lecoq asserts that he has + ascertained that crossed offspring are more vigorous and robust than + their parents.<a name="NtA_286" href="#Nt_286"><sup>[286]</sup></a></p> + + <p>General statements of this kind, however, can seldom be fully trusted; + consequently I have begun a series of experiments, which, if they + continue to give the same results as hitherto, will for ever settle the + question of the good effects of crossing two distinct plants of the same + variety, and of the evil effects of self-fertilisation. A clear light + will thus also be thrown on the fact that flowers are invariably + constructed so as to permit, or favour, or necessitate the union of two + individuals. We shall clearly understand why monœcious and + diœcious,—why dimorphic and trimorphic plants exist, and many + other such cases. The plan which I have followed in my experiments is to + grow plants in the same pot, or in pots of the same size, or close + together in the open ground; to carefully exclude insects; and then to + fertilise some of the flowers with pollen from the same flower, and + others on the same plant with pollen from a distinct but adjoining plant. + In many, but not all, of these experiments, the crossed plants yielded + much more seed than the self-fertilised plants; and I have never seen the + <!-- Page 128 --><span class="pagenum"><a + name="page128"></a>{128}</span>reversed case. The self-fertilised and + crossed seeds thus obtained were allowed to germinate in the same glass + vessel on damp sand; and as the seeds successively germinated, they were + planted in pairs on opposite sides of the same pot, with a superficial + partition between them, and were placed so as to be equally exposed to + the light. In other cases the self-fertilised and crossed seeds were + simply sown on opposite sides of the same small pot. I have, in short, + followed different plans, but in every case have taken all the + precautions which I could think of, so that the two lots should be + equally favoured. Now, I have carefully observed the growth of plants + raised from crossed and self-fertilised seed, from their germination to + maturity, in species of the following genera, namely, Brassica, Lathyrus, + Lupinus, Lobelia, Lactuca, Dianthus, Myosotis, Petunia, Linaria, + Calceolaria, Mimulus, and Ipomœa, and the difference in their + powers of growth, and of withstanding in certain cases unfavourable + conditions, was most manifest and strongly marked. It is of importance + that the two lots of seed should be sown or planted on opposite sides of + the same pot, so that the seedlings may struggle against each other; for + if sown separately in ample and good soil, there is often but little + difference in their growth.</p> + + <p>I will briefly describe the two most striking cases as yet observed by + me. Six crossed and six self-fertilised seeds of <i>Ipomœa + purpurea</i>, from plants treated in the manner above described, were + planted as soon as they had germinated, in pairs on opposite sides of two + pots, and rods of equal thickness were given them to twine up. Five of + the crossed plants grew from the first more quickly than the opposed + self-fertilised plants; the sixth, however, was weakly and was for a time + beaten, but at last its sounder constitution prevailed and it shot ahead + of its antagonist. As soon as each crossed plant reached the top of its + seven-foot rod its fellow was measured, and the result was that, when the + crossed plants were seven feet high, the self-fertilised had attained the + average height of only five feet four and a half inches. The crossed + plants flowered a little before, and more profusely than the + self-fertilised plants. On opposite sides of another <i>small</i> pot a + large number of crossed and self-fertilised seeds were sown, so that they + had to struggle for bare existence; a single rod was given to each lot: + here again the crossed plants showed from the first their advantage; they + never quite reached the summit of the seven-foot rod, but relatively to + the self-fertilised plants their average height was as seven feet to five + feet two inches. The experiment was repeated in the two following + generations with plants raised from the self-fertilised and crossed + plants, treated in exactly the same manner, and with nearly the same + result. In the second generation, the crossed plants, which were again + crossed, produced 121 seed-capsules, whilst the self-fertilised plants, + again self-fertilised, produced only 84 capsules.</p> + + <p>Some flowers of the <i>Mimulus luteus</i> were fertilised with their + own pollen, and others were crossed with pollen from distinct plants + growing in the same pot. The seeds after germinating were thickly planted + on opposite sides of a pot. The seedlings were at first equal in height; + but when the young crossed plants were exactly half an inch, the <!-- + Page 129 --><span class="pagenum"><a + name="page129"></a>{129}</span>self-fertilised plants were only a quarter + of an inch high. But this inequality did not continue, for, when the + crossed plants were four and a half inches high, the self-fertilised were + three inches; and they retained the same relative difference till their + growth was complete. The crossed plants looked far more vigorous than the + uncrossed, and flowered before them; they produced also a far greater + number of flowers, which yielded capsules (judging, however, from only a + few) containing more seeds. As in the former case, the experiment was + repeated in the same manner during the next two generations, and with + exactly the same result. Had I not watched these plants of the Mimulus + and Ipomœa during their whole growth, I could not have believed it + possible, that a difference apparently so slight, as that of the pollen + being taken from the same flower, and from a distinct plant growing in + the same small pot, could have made so wonderful a difference in the + growth and vigour of the plants thus produced. This, under a + physiological point of view, is a most remarkable phenomenon.</p> + +<hr class="short" /> + + <p>With respect to the benefit derived from crossing distinct varieties, + plenty of evidence has been published. Sageret<a name="NtA_287" + href="#Nt_287"><sup>[287]</sup></a> repeatedly speaks in strong terms of + the vigour of melons raised by crossing different varieties, and adds + that they are more easily fertilised than common melons, and produce + numerous good seed. Here follows the evidence of an English gardener:<a + name="NtA_288" href="#Nt_288"><sup>[288]</sup></a> "I have this summer + met with better success in my cultivation of melons, in an unprotected + state, from the seeds of hybrids (<i>i.e.</i> mongrels) obtained by cross + impregnation, than with old varieties. The offspring of three different + hybridisations (one more especially, of which the parents were the two + most dissimilar varieties I could select) each yielded more ample and + finer produce than any one of between twenty and thirty established + varieties."</p> + + <p>Andrew Knight<a name="NtA_289" href="#Nt_289"><sup>[289]</sup></a> + believed that his seedlings from crossed varieties of the apple exhibited + increased vigour and luxuriance; and M. Chevreul<a name="NtA_290" + href="#Nt_290"><sup>[290]</sup></a> alludes to the extreme vigour of some + of the crossed fruit-trees raised by Sageret.</p> + + <p>By crossing reciprocally the tallest and shortest peas, Knight<a + name="NtA_291" href="#Nt_291"><sup>[291]</sup></a> says, "I had in this + experiment a striking instance of the stimulative effects of crossing the + breeds; for the smallest variety, whose height rarely exceeded two feet, + was increased to six feet; whilst the height of the large and luxuriant + kind was very little diminished." Mr. Laxton gave me seed-peas produced + from crosses between four distinct kinds; and the plants thus raised were + extraordinarily vigorous, being in each case from one to two or three + feet taller than the parent-forms growing close alongside them.</p> + +<p><!-- Page 130 --><span class="pagenum"><a name="page130"></a>{130}</span></p> + + <p>Wiegmann<a name="NtA_292" href="#Nt_292"><sup>[292]</sup></a> made + many crosses between several varieties of cabbage; and he speaks with + astonishment of the vigour and height of the mongrels, which excited the + amazement of all the gardeners who beheld them. Mr. Chaundy raised a + great number of mongrels by planting together six distinct varieties of + cabbage. These mongrels displayed an infinite diversity of character; + "But the most remarkable circumstance was, that, while all the other + cabbages and borecoles in the nursery were destroyed by a severe winter, + these hybrids were little injured, and supplied the kitchen when there + was no other cabbage to be had."</p> + + <p>Mr. Maund exhibited before the Royal Agricultural Society<a + name="NtA_293" href="#Nt_293"><sup>[293]</sup></a> specimens of crossed + wheat, together with their parent varieties; and the editor states that + they were intermediate in character, "united with that greater vigour of + growth, which it appears, in the vegetable as in the animal world, is the + result of a first cross." Knight also crossed several varieties of + wheat,<a name="NtA_294" href="#Nt_294"><sup>[294]</sup></a> and he says + "that in the years 1795 and 1796, when almost the whole crop of corn in + the island was blighted, the varieties thus obtained, and these only, + escaped in this neighbourhood, though sown in several different soils and + situations."</p> + + <p>Here is a remarkable case: M. Clotzsch<a name="NtA_295" + href="#Nt_295"><sup>[295]</sup></a> crossed <i>Pinus sylvestris</i> and + <i>nigricans</i>, <i>Quercus robur</i> and <i>pedunculata, Alnus + glutinosa</i> and <i>incana</i>, <i>Ulmus campestris</i> and + <i>effusa</i>; and the cross-fertilised seeds, as well as seeds of the + pure parent-trees, were all sown at the same time and in the same place. + The result was, that after an interval of eight years, the hybrids were + one-third taller than the pure trees!</p> + +<hr class="short" /> + + <p>The facts above given refer to undoubted varieties, excepting the + trees crossed by Clotzsch, which are ranked by various botanists as + strongly-marked races, sub-species, or species. That true hybrids raised + from entirely distinct species, though they lose in fertility, often gain + in size and constitutional vigour, is certain. It would be superfluous to + quote any facts; for all experimenters, Kölreuter, Gärtner, Herbert, + Sageret, Lecoq, and Naudin, have been struck with the wonderful vigour, + height, size, tenacity of life, precocity, and hardiness of their hybrid + productions. Gärtner<a name="NtA_296" href="#Nt_296"><sup>[296]</sup></a> + sums up his conviction on this head in the strongest terms. Kölreuter<a + name="NtA_297" href="#Nt_297"><sup>[297]</sup></a> gives numerous precise + measurements of the weight and height of his hybrids in comparison with + measurements of both parent-forms; and speaks with astonishment of their + "<i>statura portentosa</i>," their "<i>ambitus vastissimus ac altitudo + valde conspicua</i>." Some exceptions to the rule in the case of very + sterile hybrids have, however, been noticed by Gärtner and <!-- Page 131 + --><span class="pagenum"><a name="page131"></a>{131}</span>Herbert; but + the most striking exceptions are given by Max Wichura,<a name="NtA_298" + href="#Nt_298"><sup>[298]</sup></a> who found that hybrid willows were + generally tender in constitution, dwarf, and short-lived.</p> + + <p>Kölreuter explains the vast increase in the size of the roots, stems, + &c., of his hybrids, as the result of a sort of compensation due to + their sterility, in the same way as many emasculated animals are larger + than the perfect males. This view seems at first sight extremely + probable, and has been accepted by various authors;<a name="NtA_299" + href="#Nt_299"><sup>[299]</sup></a> but Gärtner<a name="NtA_300" + href="#Nt_300"><sup>[300]</sup></a> has well remarked that there is much + difficulty in fully admitting it; for with many hybrids there is no + parallelism between the degree of their sterility and their increased + size and vigour. The most striking instances of luxuriant growth have + been observed with hybrids which were not sterile in any extreme degree. + In the genus Mirabilis, certain hybrids are unusually fertile, and their + extraordinary luxuriance of growth, together with their enormous roots,<a + name="NtA_301" href="#Nt_301"><sup>[301]</sup></a> have been transmitted + to their progeny. The increased size of the hybrids produced between the + fowl and pheasant, and between the distinct species of pheasants, has + been already noticed. The result in all cases is probably in part due to + the saving of nutriment and vital force through the sexual organs not + acting, or acting imperfectly, but more especially to the general law of + good being derived from a cross. For it deserves especial attention that + mongrel animals and plants, which are so far from being sterile that + their fertility is often actually augmented, have, as previously shown, + their size, hardiness, and constitutional vigour generally increased. It + is not a little remarkable that an accession of vigour and size should + thus arise under the opposite contingencies of increased and diminished + fertility.</p> + + <p>It is a perfectly well ascertained fact<a name="NtA_302" + href="#Nt_302"><sup>[302]</sup></a> that hybrids will invariably breed + more readily with either pure parent, and not rarely with a distinct + species, than with each other. Herbert is inclined to explain even this + fact by the advantage derived from a cross; but Gärtner more justly + accounts for it by the pollen of the hybrid, and probably its ovules, + being in some degree vitiated, whereas the pollen and ovules of both pure + parents and of any third species are sound. Nevertheless there are some + well-ascertained and remarkable facts, which, as we shall immediately + see, show that the act of crossing in itself undoubtedly tends to + increase or re-establish the fertility of hybrids.</p> + +</blockquote> + +<p class="cenhead"><i>On certain Hermaphrodite Plants which, either normally or abnormally, +require to be fertilised by pollen from a distinct individual +or species.</i></p> + + <p>The facts now to be given differ from those hitherto detailed, as the + self-sterility does not here result from long-continued, <!-- Page 132 + --><span class="pagenum"><a name="page132"></a>{132}</span>close + interbreeding. These facts are, however, connected with our present + subject, because a cross with a distinct individual is shown to be either + necessary or advantageous. Dimorphic and trimorphic plants, though they + are hermaphrodites, must be reciprocally crossed, one set of forms by the + other, in order to be fully fertile, and in some cases to be fertile in + any degree. But I should not have noticed these plants, had it not been + for the following cases given by Dr. Hildebrand:<a name="NtA_303" + href="#Nt_303"><sup>[303]</sup></a>—</p> + +<blockquote class="b1n"> + + <p><i>Primula sinensis</i> is a reciprocally dimorphic species: Dr. + Hildebrand fertilised twenty-eight flowers of both forms, each by pollen + of the other form, and obtained the full number of capsules containing on + an average 42.7 seed per capsule; here we have complete and normal + fertility. He then fertilised forty-two flowers of both forms with pollen + of the same form, but taken from a distinct plant, and all produced + capsules containing on an average only 19.6 seed. Lastly, and here we + come to our more immediate point, he fertilised forty-eight flowers of + both forms with pollen of the same form, taken from the same flower, and + now he obtained only thirty-two capsules, and these contained on an + average 18.6 seed, or one less per capsule than in the former case. So + that, with these illegitimate unions, the act of impregnation is less + assured, and the fertility slightly less, when the pollen and ovules + belong to the same flower, than when belonging to two distinct + individuals of the same form. Dr. Hildebrand has recently made analogous + experiments on the long-styled form of <i>Oxalis rosea</i>, with the same + result.<a name="NtA_304" href="#Nt_304"><sup>[304]</sup></a></p> + +</blockquote> + + <p>It has recently been discovered that certain plants, whilst growing in + their native country under natural conditions, cannot be fertilised with + pollen from the same plant. They are sometimes so utterly self-impotent, + that, though they can readily be fertilised by the pollen of a distinct + species or even distinct genus, yet, wonderful as the fact is, they never + produce a single seed by their own pollen. In some cases, moreover, the + plant's own pollen and stigma mutually act on each other in a deleterious + manner. Most of the facts to be given relate to Orchids, but I will + commence with a plant belonging to a widely different family.</p> + +<blockquote class="b1n"> + + <p>Sixty-three flowers of <i>Corydalis cava</i>, borne on distinct + plants, were fertilised by Dr. Hildebrand<a name="NtA_305" + href="#Nt_305"><sup>[305]</sup></a> with pollen from other plants of the + same species; and fifty-eight capsules were obtained, including on an + average <!-- Page 133 --><span class="pagenum"><a + name="page133"></a>{133}</span>4.5 seed in each. He then fertilised + sixteen flowers produced by the same raceme, one with another, but + obtained only three capsules, one of which alone contained any good + seeds, namely, two in number. Lastly, he fertilised twenty-seven flowers, + each with its own pollen; he left also fifty-seven flowers to be + spontaneously fertilised, and this would certainly have ensued if it had + been possible, for the anthers not only touch the stigma, but the + pollen-tubes were seen by Dr. Hildebrand to penetrate it; nevertheless + these eighty-four flowers did not produce a single seed-capsule! This + whole case is highly instructive, as it shows how widely different the + action of the same pollen is, according as it is placed on the stigma of + the same flower, or on that of another flower on the same raceme, or on + that of a distinct plant.</p> + + <p>With exotic Orchids several analogous cases have been observed, + chiefly by Mr. John Scott.<a name="NtA_306" + href="#Nt_306"><sup>[306]</sup></a> <i>Oncidium sphacelatum</i> has + effective pollen, for with it Mr. Scott fertilised two distinct species; + its ovules are likewise capable of impregnation, for they were readily + fertilised by the pollen of <i>O. divaricatum</i>; nevertheless, between + one and two hundred flowers fertilised by their own pollen did not + produce a single capsule, though the stigmas were penetrated by the + pollen-tubes. Mr. Robinson Munro, of the Royal Botanic Gardens of + Edinburgh, also informs me (1864) that a hundred and twenty flowers of + this same species were fertilised by him with their own pollen, and did + not produce a capsule, but eight flowers fertilised by the pollen of + <i>O. divaricatum</i> produced four fine capsules: again, between two and + three hundred flowers of <i>O. divaricatum</i>, fertilised by their own + pollen, did not set a capsule, but twelve flowers fertilised by <i>O. + flexuosum</i> produced eight fine capsules: so that here we have three + utterly self-impotent species, with their male and female organs perfect, + as shown by their mutual fertilisation. In these cases fertilisation was + effected only by the aid of a distinct species. But, as we shall + presently see, distinct plants, raised from seed, of <i>Oncidium + flexuosum</i>, and probably of the other species, would have been + perfectly capable of fertilising each other, for this is the natural + process. Again, Mr. Scott found that the pollen of a plant of <i>O. + microchilum</i> was good, for with it he fertilised two distinct species; + he found its ovules good, for they could be fertilised by the pollen of + one of these species, and by the pollen of a distinct plant of <i>O. + microchilum</i>; but they could not be fertilised by pollen of the same + plant, though the pollen-tubes penetrated the stigma. An analogous case + has been recorded by M. Rivière,<a name="NtA_307" + href="#Nt_307"><sup>[307]</sup></a> with two plants of <i>O. + Cavendishianum</i>, which were both self-sterile, but reciprocally + fertilised each other. All these cases refer to the genus Oncidium, but + Mr. Scott found that <i>Maxillaria atro-rubens</i> was "totally + insusceptible of fertilisation with its own pollen," but fertilised, and + was fertilised by, a widely distinct species, viz. <i>M. + squalens</i>.</p> + + <p>As these orchids had grown under unnatural conditions, in <!-- Page + 134 --><span class="pagenum"><a + name="page134"></a>{134}</span>hot-houses, I concluded without hesitation + that their self-sterility was due to this cause. But Fritz Müller informs + me that at Desterro, in Brazil, he fertilised above one hundred flowers + of the above-mentioned <i>Oncidium flexuosum</i>, which is there endemic, + with its own pollen, and with that taken from distinct plants; all the + former were sterile, whilst those fertilised by pollen from any <i>other + plant</i> of the same species were fertile. During the first three days + there was no difference in the action of the two kinds of pollen: that + placed on the stigma of the same plant separated in the usual manner into + grains, and emitted tubes which penetrated the column, and the stigmatic + chamber shut itself; but the flowers alone which had been fertilised by + pollen taken from a distinct plant produced seed-capsules. On a + subsequent occasion these experiments were repeated on a large scale with + the same result. Fritz Müller found that four other endemic species of + Oncidium were in like manner utterly sterile with their own pollen, but + fertile with that from any other plant: some of them likewise produced + seed-capsules when impregnated with pollen of widely distinct genera, + such as Leptotes, Cyrtopodium, and Rodriguezia! <i>Oncidium crispum</i>, + however, differs from the foregoing species in varying much in its + self-sterility; some plants producing fine pods with their own pollen, + others failing to do so; in two or three instances, Fritz Müller observed + that the pods produced by pollen taken from a distinct flower on the same + plant, were larger than those produced by the flower's own pollen. In + <i>Epidendrum cinnabarinum</i>, an orchid belonging to another division + of the family, fine pods were produced by the plant's own pollen, but + they contained by weight only about half as much seed as the capsules + which had been fertilized by pollen from a distinct plant, and in one + instance from a distinct species; moreover, a very large proportion, and + in some cases nearly all the seed produced by the plant's own pollen, was + embryonless and worthless. Some self-fertilized capsules of a Maxillaria + were in a similar state.</p> + + <p>Another observation made by Fritz Müller is highly remarkable, namely, + that with various orchids the plant's own pollen not only fails to + impregnate the flower, but acts on the stigma, and is acted on, in an + injurious or poisonous manner. This is shown by the surface of the stigma + in contact with the pollen, and by the pollen itself, becoming in from + three to five days dark brown, and then decaying. The discolouration and + decay are not caused by parasitic cryptogams, which were observed by + Fritz Müller in only a single instance. These changes are well shown by + placing on the same stigma, at the same time, the plant's own pollen and + that from a distinct plant of the same species, or of another species, or + even of another and widely remote genus. Thus, on the stigma of + <i>Oncidium flexuosum</i>, the plant's own pollen and that from a + distinct plant were placed side by side, and in five days' time the + latter was perfectly fresh, whilst the plant's own pollen was brown. On + the other hand, when the pollen of a distinct plant of the <i>Oncidium + flexuosum</i>, and of the <i>Epidendrum zebra</i> (<i>nov. spec.?</i>), + were placed together on the same stigma, they behaved in exactly the same + manner, the grains separating, emitting tubes, and penetrating the + stigma, so that the two <!-- Page 135 --><span class="pagenum"><a + name="page135"></a>{135}</span>pollen-masses, after an interval of eleven + days, could not be distinguished except by the difference of their + caudicles, which, of course, undergo no change. Fritz Müller has, + moreover, made a large number of crosses between orchids belonging to + distinct species and genera, and he finds that in all cases when the + flowers are not fertilised their footstalks first begin to wither; and + the withering slowly spreads upwards until the germens fall off, after an + interval of one or two weeks, and in one instance of between six and + seven weeks; but even in this latter case, and in most other cases, the + pollen and stigma remained in appearance fresh. Occasionally, however, + the pollen becomes brownish, generally on the external surface, and not + in contact with the stigma, as is invariably the case when the plant's + own pollen is applied.</p> + + <p>Fritz Müller observed the poisonous action of the plant's own pollen + in the above-mentioned <i>Oncidium flexuosum</i>, <i>O. unicorne, + pubes</i> (<i>?</i>), and in two other unnamed species. Also in two + species of Rodriguezia, in two of Notylia, in one of Burlingtonia, and of + a fourth genus in the same group. In all these cases, except the last, it + was proved that the flowers were, as might have been expected, fertile + with pollen from a distinct plant of the same species. Numerous flowers + of one species of Notylia were fertilized with pollen from the same + raceme; in two days' time they all withered, the germens began to shrink, + the pollen-masses became dark brown, and not one pollen-grain emitted a + tube. So that in this orchid the injurious action of the plant's own + pollen is more rapid than with <i>Oncidium flexuosum</i>. Eight other + flowers on the same raceme were fertilized with pollen from a distinct + plant of the same species: two of these were dissected, and their stigmas + were found to be penetrated by numberless pollen-tubes; and the germens + of the other six flowers became well developed. On a subsequent occasion + many other flowers were fertilized with their own pollen, and all fell + off dead in a few days; whilst some flowers on the same raceme which had + been left simply unfertilised adhered and long remained fresh. We have + seen that in cross-unions between extremely distinct orchids the pollen + long remains undecayed; but Notylia behaved in this respect differently; + for when its pollen was placed on the stigma of <i>Oncidium + flexuosum</i>, both the stigma and pollen quickly became dark brown, in + the same manner as if the plant's own pollen had been applied.</p> + + <p>Fritz Müller suggests that, as in all these cases the plant's own + pollen is not only impotent (thus effectually preventing + self-fertilization), but likewise prevents, as was ascertained in the + case of the Notylia and <i>Oncidium flexuosum</i>, the action of + subsequently applied pollen from a distinct individual, it would be an + advantage to the plant to have its own pollen rendered more and more + deleterious; for the germens would thus quickly be killed, and, dropping + off, there would be no further waste in nourishing a part which + ultimately could be of no avail. Fritz Müller's discovery that a plant's + own pollen and stigma in some cases act on each other as if mutually + poisonous, is certainly most remarkable.</p> + +</blockquote> + + <p>We now come to cases closely analogous with those just <!-- Page 136 + --><span class="pagenum"><a name="page136"></a>{136}</span>given, but + different, inasmuch as individual plants alone of the species are + self-impotent. This self-impotence does not depend on the pollen or + ovules being in a state unfit for fertilisation, for both have been found + effective in union with other plants of the same or of a distinct + species. The fact of these plants having spontaneously acquired so + peculiar a constitution, that they can be fertilised more readily by the + pollen of a distinct species than by their own, is remarkable. These + abnormal cases, as well as the foregoing normal cases, in which certain + orchids, for instance, can be much more easily fertilised by the pollen + of a distinct species than by their own, are exactly the reverse of what + occurs with all ordinary species. For in these latter the two sexual + elements of the same individual plant are capable of freely acting on + each other; but are so constituted that they are more or less impotent + when brought into union with the sexual elements of a distinct species, + and produce more or less sterile hybrids. It would appear that the pollen + or ovules, or both, of the individual plants which are in this abnormal + state, have been affected in some strange manner by the conditions to + which they themselves or their parents have been exposed; but whilst thus + rendered self-sterile, they have retained the capacity common to most + species of partially fertilizing and being partially fertilized by allied + forms. However this may be, the subject, to a certain extent, is related + to our general conclusion that good is derived from the act of + crossing.</p> + +<blockquote class="b1n"> + + <p>Gärtner experimented on two plants of <i>Lobelia fulgens</i>, brought + from separate places, and found<a name="NtA_308" + href="#Nt_308"><sup>[308]</sup></a> that their pollen was good, for he + fertilised with it <i>L. cardinalis</i> and <i>syphilitica</i>; their + ovules were likewise good, for they were fertilised by the pollen of + these same two species; but these two plants of <i>L. fulgens</i> could + not be fertilised by their own pollen, as can generally be effected with + perfect ease with this species. Again, the pollen of a plant of + <i>Verbascum nigrum</i> grown in a pot was found by Gärtner<a + name="NtA_309" href="#Nt_309"><sup>[309]</sup></a> capable of fertilising + <i>V. lychnitis</i> and <i>V. Austriacum</i>; the ovules could be + fertilised by the pollen of <i>V. thapsus</i>; but the flowers could not + be fertilised by their own pollen. Kölreuter, also,<a name="NtA_310" + href="#Nt_310"><sup>[310]</sup></a> gives the case of three <!-- Page 137 + --><span class="pagenum"><a name="page137"></a>{137}</span>garden plants + of <i>Verbascum phœniceum</i>, which bore during two years many + flowers; these he successfully fertilised by the pollen of no less than + four distinct species, but they produced not a seed with their own + apparently good pollen; subsequently these same plants, and others raised + from seed, assumed a strangely fluctuating condition, being temporarily + sterile on the male or female side, or on both sides, and sometimes + fertile on both sides; but two of the plants were perfectly fertile + throughout the summer.</p> + + <p>It appears<a name="NtA_311" href="#Nt_311"><sup>[311]</sup></a> that + certain flowers on certain plants of <i>Lilium candidum</i> can be + fertilised more easily by pollen from a distinct individual than by their + own. So, again, with the varieties of the potato. Tinzmann,<a + name="NtA_312" href="#Nt_312"><sup>[312]</sup></a> who made many trials + with this plant, says that pollen from another variety sometimes "exerts + a powerful influence, and I have found sorts of potatoes which would not + bear seed from impregnation with the pollen of their own flowers, would + bear it when impregnated with other pollen." It does not, however, appear + to have been proved that the pollen which failed to act on the flower's + own stigma was in itself good.</p> + + <p>In the genus Passiflora it has long been known that several species do + not produce fruit, unless fertilised by pollen taken from distinct + species: thus, Mr. Mowbray<a name="NtA_313" + href="#Nt_313"><sup>[313]</sup></a> found that he could not get fruit + from <i>P. alata</i> and <i>racemosa</i> except by reciprocally + fertilising them with each other's pollen. Similar facts have been + observed in Germany and France;<a name="NtA_314" + href="#Nt_314"><sup>[314]</sup></a> and I have received two authentic + accounts of <i>P. quadrangularis</i>, which never produced fruit with its + own pollen, but would do so freely when fertilised in one case with the + pollen of <i>P. cœrulea</i>, and in another case with that of <i>P. + edulis</i>. So again, with respect to <i>P. laurifolia</i>, a cultivator + of much experience has recently remarked<a name="NtA_315" + href="#Nt_315"><sup>[315]</sup></a> that the flowers "must be fertilised + with the pollen of <i>P. cœrulea</i>, or of some other common kind, + as their own pollen will not fertilise them." But the fullest details on + this subject have been given by Mr. Scott:<a name="NtA_316" + href="#Nt_316"><sup>[316]</sup></a> plants of <i>Passiflora racemosa</i>, + <i>cœrulea</i>, and <i>alata</i> flowered profusely during many + years in the Botanic Gardens of Edinburgh, and, though repeatedly + fertilised by Mr. Scott and by others with their own pollen, never + produced any seed; yet this occurred at once with all three species when + they were crossed together in various ways. But in the case of <i>P. + cœrulea</i>, three plants, two of which grew in the Botanic + Gardens, were all rendered fertile, merely by impregnating the one with + pollen of the other. The same result was attained in the same manner with + <i>P. alata</i>, but only with one plant out of three. As so many + self-sterile species have been mentioned, it may be stated that in the + case of <i>P. gracilis</i>, which is an annual, the flowers are nearly as + fertile with their own pollen as with that from a distinct plant; thus + sixteen flowers <!-- Page 138 --><span class="pagenum"><a + name="page138"></a>{138}</span>spontaneously self-fertilised produced + fruit, each containing on an average 21.3 seed, whilst fruit from + fourteen crossed flowers contained 24.1 seed.</p> + + <p>Returning to <i>P. alata</i>, I have received (1866) some interesting + details from Mr. Robinson Munro. Three plants, including one in England, + have already been mentioned which were inveterately self-sterile, and Mr. + Munro informs me of several others which, after repeated trials during + many years, have been found in the same predicament. At some other + places, however, this species fruits readily when fertilised with its own + pollen. At Taymouth Castle there is a plant which was formerly grafted by + Mr. Donaldson on a distinct species, name unknown, and ever since the + operation it has produced fruit in abundance by its own pollen; so that + this small and unnatural change in the state of this plant has restored + its self-fertility! Some of the seedlings from the Taymouth Castle plant + were found to be not only sterile with their own pollen, but with each + other's pollen, and with the pollen of distinct species. Pollen from the + Taymouth plant failed to fertilise certain plants of the same species, + but was successful on one plant in the Edinburgh Botanic Gardens. + Seedlings were raised from this latter union, and some of their flowers + were fertilised by Mr. Munro with their own pollen; but they were found + to be as self-impotent as the mother-plant had always proved, except when + fertilised by the grafted Taymouth plant, and except, as we shall see, + when fertilised by her own seedlings. For Mr. Munro fertilised eighteen + flowers on the self-impotent mother-plant with pollen from these her own + self-impotent seedlings, and obtained, remarkable as the fact is, + eighteen fine capsules full of excellent seed! I have met with no case in + regard to plants which shows so well as this of <i>P. alata</i>, on what + small and mysterious causes complete fertility or complete sterility + depends.</p> + +</blockquote> + + <p>The facts hitherto given relate to the much-lessened or completely + destroyed fertility of pure species when impregnated with their own + pollen, in comparison with their fertility when impregnated by distinct + individuals or distinct species; but closely analogous facts have been + observed with hybrids.</p> + +<blockquote class="b1n"> + + <p>Herbert states<a name="NtA_317" href="#Nt_317"><sup>[317]</sup></a> + that having in flower at the same time nine hybrid Hippeastrums, of + complicated origin, descended from several species, he found that "almost + every flower touched with pollen from another cross produced seed + abundantly, and those which were touched with their own pollen either + failed entirely, or formed slowly a pod of inferior size, with fewer + seeds." In the 'Horticultural Journal' he adds that, "the admission of + the pollen of another cross-bred Hippeastrum (however complicated the + cross) to any <i>one</i> flower of the number, is almost sure to check + the fructification of the others." In a letter written to me in 1839, Dr. + Herbert says that he had already tried these experiments during five + consecutive years, and he subsequently repeated them, with the same + invariable result. <!-- Page 139 --><span class="pagenum"><a + name="page139"></a>{139}</span>He was thus led to make an analogous trial + on a pure species, namely, on the <i>Hippeastrum aulicum</i>, which he + had lately imported from Brazil: this bulb produced four flowers, three + of which were fertilised by their own pollen, and the fourth by the + pollen of a triple cross between <i>H. bulbulosum</i>, <i>reginæ</i>, and + <i>vittatum</i>; the result was, that "the ovaries of the three first + flowers soon ceased to grow, and after a few days perished entirely: + whereas the pod impregnated by the hybrid made vigorous and rapid + progress to maturity, and bore good seed, which vegetated freely." This + is, indeed, as Herbert remarks, "a strange truth," but not so strange as + it then appeared.</p> + + <p>As a confirmation of these statements, I may add that Mr. M. Mayes,<a + name="NtA_318" href="#Nt_318"><sup>[318]</sup></a> after much experience + in crossing the species of Amaryllis (Hippeastrum), says, "neither the + species nor the hybrids will, we are well aware, produce seed so + abundantly from their own pollen as from that of others." So, again, Mr. + Bidwell, in New South Wales,<a name="NtA_319" + href="#Nt_319"><sup>[319]</sup></a> asserts that <i>Amaryllis + belladonna</i> bears many more seeds when fertilised by the pollen of + <i>Brunswigia</i> (<i>Amaryllis</i> of some authors) <i>Josephinæ</i> or + of <i>B. multiflora</i>, than when fertilised by its own pollen. Mr. + Beaton dusted four flowers of a Cyrtanthus with their own pollen, and + four with the pollen of <i>Vallota</i> (<i>Amaryllis</i>) + <i>purpurea</i>; on the seventh day "those which received their own + pollen slackened their growth, and ultimately perished; those which were + crossed with the Vallota held on."<a name="NtA_320" + href="#Nt_320"><sup>[320]</sup></a> These latter cases, however, relate + to uncrossed species, like those before given with respect to Passiflora, + Orchids, &c., and are here referred to only because the plants belong + to the same group of Amaryllidaceæ.</p> + + <p>In the experiments on the hybrid Hippeastrums, if Herbert had found + that the pollen of two or three kinds alone had been more efficient on + certain kinds than their own pollen, it might have been argued that + these, from their mixed parentage, had a closer mutual affinity than the + others; but this explanation is inadmissible, for the trials were made + reciprocally backwards and forwards on nine different hybrids; and a + cross, whichever way taken, always proved highly beneficial. I can add a + striking and analogous case from experiments made by the Rev. A. Rawson, + of Bromley Common, with some complex hybrids of Gladiolus. This skilful + horticulturist possessed a number of French varieties, differing from + each other only in the colour and size of the flowers, all descended from + Gandavensis, a well-known old hybrid, said to be descended from <i>G. + Natalensis</i> by the pollen of <i>G. oppositiflorus</i>.<a + name="NtA_321" href="#Nt_321"><sup>[321]</sup></a> Mr. Rawson, after + repeated trials, found that none of the varieties would set seed with + their own pollen, although <!-- Page 140 --><span class="pagenum"><a + name="page140"></a>{140}</span>taken from distinct plants of the same + variety, which had, of course, been propagated by bulbs, but that they + all seeded freely with pollen from any other variety. To give two + examples: Ophir did not produce a capsule with its own pollen, but when + fertilised with that of Janire, Brenchleyensis, Vulcain, and Linné, it + produced ten fine capsules; but the pollen of Ophir was good, for when + Linné was fertilised by it seven capsules were produced. This later + variety, on the other hand, was utterly barren with its own pollen, which + we have seen was perfectly efficient on Ophir. Altogether, Mr. Rawson, in + the year 1861, fertilised twenty-six flowers borne by four varieties with + pollen taken from other varieties, and every single flower produced a + fine seed-capsule; whereas fifty-two flowers on the same plants, + fertilised at the same time with their own pollen, did not yield a single + seed-capsule. Mr. Rawson fertilised, in some cases, the alternate + flowers, and in other cases all those down one side of the spike, with + pollen of other varieties, and the remaining flowers with their own + pollen; I saw these plants when the capsules were nearly mature, and + their curious arrangement at once brought full conviction to the mind + that an immense advantage had been derived from crossing these + hybrids.</p> + + <p>Lastly, I have heard from Dr. E. Bornet, of Antibes, who has made + numerous experiments in crossing the species of Cistus, but as not yet + published the results, that, when any of these hybrids are fertile, they + may be said to be, in regard to function, diœcious; "for the + flowers are always sterile when the pistil is fertilised by pollen taken + from the same flower or from flowers on the same plant. But they are + often fertile if pollen be employed from a distinct individual of the + same hybrid nature, or from a hybrid made by a reciprocal cross."</p> + +</blockquote> + + <p><i>Conclusion.</i>—The facts just given, which show that certain + plants are self-sterile, although both sexual elements are in a fit state + for reproduction when united with distinct individuals of the same or + other species, appear at first sight opposed to all analogy. The sexual + elements of the same flower have become, as already remarked, + differentiated in relation to each other, almost like those of two + distinct species.</p> + + <p>With respect to the species which, whilst living under their natural + conditions, have their reproductive organs in this peculiar state, we may + conclude that it has been naturally acquired for the sake of effectually + preventing self-fertilisation. The case is closely analous with dimorphic + and trimorphic plants, which can be fully fertilised only by plants + belong to the opposite form, and not, as in the foregoing cases, in + differently by any other plant. Some of these dimorphic plants are + completely sterile with pollen taken from the same plant or from the same + <!-- Page 141 --><span class="pagenum"><a + name="page141"></a>{141}</span>form. It is interesting to observe the + graduated series from plants which, when fertilised by their own pollen, + yield the full number of seed, but with the seedlings a little dwarfed in + stature—to plants which when self-fertilised yield few + seeds—to those with yield none—and, lastly, to those in which + the plant's own pollen and stigma act on each other like poison. This + peculiar state of the reproductive organs, when occurring in certain + individuals alone, is evidently abnormal; and as it chiefly affects + exotic plants, or indigenous plants cultivated in pots, we may attribute + it to some change in the conditions of life, acting on the plants + themselves or on their parents. The self-impotent <i>Passiflora + alata</i>, which recovered its self-fertility after having been grafted + on a distinct stock, shows how small a change is sufficient to act + powerfully on the reproductive system. The possibility of a plant + becoming under culture self-impotent is interesting as throwing light on + the occurrence of this same condition in natural species. A cultivated + plant in this state generally remains so during its whole life; and from + this fact we may infer that the state is probably congenital.</p> + + <p>Kölreuter, however, has described some plants of Verbascum which + varied in this respect even during the same season. As in all the normal + cases, and in many, probably in most, of the abnormal cases, any two + self-impotent plants can reciprocally fertilize each other, we may infer + that a very slight difference in the nature of their sexual elements + suffices to give fertility; but in other instances, as with some + Passifloras and the hybrid Gladioli, a greater degree of differentiation + appears to be necessary, for with these plants fertility is gained only + by the union of distinct species, or of hybrids of distinct parentage. + These facts all point to the same general conclusion, namely, that good + is derived from a cross between individuals, which either innately, or + from exposure to dissimilar conditions, have come to differ in sexual + constitution.</p> + + <p>Exotic animals confined in menageries are sometimes in nearly the same + state as the above-described self-impotent plants; for, as we shall see + in the following chapter, certain monkeys, the larger carnivora, several + finches, geese, and pheasants, cross together, quite as freely as, or + even more freely than, the individuals of the same species breed + together. Cases will, <!-- Page 142 --><span class="pagenum"><a + name="page142"></a>{142}</span>also, be given of sexual incompatibility + between certain male and female domesticated animals, which, + nevertheless, are fertile when matched with any other individual of the + same kind.</p> + + <p>In the early part of this chapter it was shown that the crossing of + distinct forms, whether closely or distantly allied, gives increased size + and constitutional vigour, and, except in the case of crossed species, + increased fertility, to the offspring. The evidence rests on the + universal testimony of breeders (for it should be observed that I am not + here speaking of the evil results of close interbreeding), and is + practically exemplified in the higher value of cross-bred animals for + immediate consumption. The good results of crossing have also been + demonstrated, in the case of some animals and of numerous plants, by + actual weight and measurement. Although animals of pure blood will + obviously be deteriorated by crossing, as far as their characteristic + qualities are concerned, there seems to be no exception to the rule that + advantages of the kind just mentioned are thus gained, even when there + has not been any previous close interbreeding. The rule applies to all + animals, even to cattle and sheep, which can long resist breeding + in-and-in between the nearest blood-relations. It applies to individuals + of the same sub-variety but of distinct families, to varieties or races, + to sub-species, as well as to quite distinct species.</p> + + <p>In this latter case, however, whilst size, vigour, precocity, and + hardiness are, with rare exceptions, gained, fertility, in a greater or + less degree, is lost; but the gain cannot be exclusively attributed to + the principle of compensation; for there is no close parallelism between + the increased size and vigour of the offspring and their sterility. + Moreover it has been clearly proved that mongrels which are perfectly + fertile gain these same advantages as well as sterile hybrids.</p> + + <p>The evil consequences of long-continued close interbreeding are not so + easily recognised as the good effects from crossing, for the + deterioration is gradual. Nevertheless it is the general opinion of those + who have had most experience, especially with animals which propagate + quickly, that evil does inevitably follow sooner or later, but at + different rates with different animals. No doubt a false belief may + widely prevail like a superstition; yet it is difficult to suppose that + so many acute and original <!-- Page 143 --><span class="pagenum"><a + name="page143"></a>{143}</span>observers have all been deceived at the + expense of much cost and trouble. A male animal may sometimes be paired + with his daughter, granddaughter, and so on, even for seven generations, + without any manifest bad result; but the experiment has never been tried + of matching brothers and sisters, which is considered the closest form of + interbreeding, for an equal number of generations. There is good reason + to believe that by keeping the members of the same family in distinct + bodies, especially if exposed to somewhat different conditions of life, + and by occasionally crossing these families, the evil results may be much + diminished, or quite eliminated. These results are loss of constitutional + vigour, size, and fertility; but there is no necessary deterioration in + the general form of the body, or in other good qualities. We have seen + that with pigs first-rate animals have been produced after long-continued + close interbreeding, though they had become extremely infertile when + paired with their near relations. The loss of fertility, when it occurs, + seems never to be absolute, but only relative to animals of the same + blood; so that this sterility is to a certain extent analogous with that + of self-impotent plants which cannot be fertilised by their own pollen, + but are perfectly fertile with pollen of any other plant of the same + species. The fact of infertility of this peculiar nature being one of the + results of long-continued interbreeding, shows that interbreeding does + not act merely by combining and augmenting various morbid tendencies + common to both parents; for animals with such tendencies, if not at the + time actually ill, can generally propagate their kind. Although offspring + descended from the nearest blood-relations are not necessarily + deteriorated in structure, yet some authors<a name="NtA_322" + href="#Nt_322"><sup>[322]</sup></a> believe that they are eminently + liable to malformations; and this is not improbable, as everything which + lessens the vital powers acts in this manner. Instances of this kind have + been recorded in the case of pigs, bloodhounds, and some other + animals.</p> + + <p>Finally, when we consider the various facts now given which plainly + show that good follows from crossing, and less plainly <!-- Page 144 + --><span class="pagenum"><a name="page144"></a>{144}</span>that evil + follows from close interbreeding, and when we bear in mind that + throughout the whole organic world elaborate provision has been made for + the occasional union of distinct individuals, the existence of a great + law of nature is, if not proved, at least rendered in the highest degree + probable; namely, that the crossing of animals and plants which are not + closely related to beach other is highly beneficial or even necessary, + and that interbreeding prolonged during many generations is highly + injurious.</p> + +<hr class="full" /> + +<p><!-- Page 145 --><span class="pagenum"><a name="page145"></a>{145}</span></p> + +<h3>CHAPTER XVIII.</h3> + +<p class="cenhead">ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED +CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES.</p> + +<blockquote class="b1n"> + + <p><span class="scac">ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE + CONDITIONS OF LIFE</span>—<span class="scac">STERILITY FROM CHANGED + CONDITIONS, IN ANIMALS, IN THEIR NATIVE COUNTRY AND IN + MENAGERIES</span>—<span class="scac">MAMMALS, BIRDS, AND + INSECTS</span>—<span class="scac">LOSS OF SECONDARY SEXUAL + CHARACTERS AND OF INSTINCTS</span>—<span class="scac">CAUSES OF + STERILITY</span>—<span class="scac">STERILITY OF DOMESTICATED + ANIMALS FROM CHANGED CONDITIONS</span>—<span class="scac">SEXUAL + INCOMPATIBILITY OF INDIVIDUAL ANIMALS</span>—<span + class="scac">STERILITY OF PLANTS FROM CHANGED CONDITIONS OF + LIFE</span>—<span class="scac">CONTABESCENCE OF THE + ANTHERS</span>—<span class="scac">MONSTROSITIES AS A CAUSE OF + STERILITY</span>—<span class="scac">DOUBLE + FLOWERS</span>—<span class="scac">SEEDLESS FRUIT</span>—<span + class="scac">STERILITY FROM THE EXCESSIVE DEVELOPMENT OF THE ORGANS OF + VEGETATION</span>—<span class="scac">FROM LONG-CONTINUED + PROPAGATION BY BUDS</span>—<span class="scac">INCIPIENT STERILITY + THE PRIMARY CAUSE OF DOUBLE FLOWERS AND SEEDLESS FRUIT.</span></p> + +</blockquote> + + <p><i>On the Good derived from slight Changes in the Conditions of + Life.</i>—In considering whether any facts were known which might + throw light on the conclusion arrived at in the last chapter, namely, + that benefits ensue from crossing, and that it is a law of nature that + all organic beings should occasionally cross, it appeared to me probable + that the good derived from slight changes in the conditions of life, from + being an analogous phenomenon, might serve this purpose. No two + individuals, and still less no two varieties, are absolutely alike in + constitution and structure; and when the germ of one is fertilised by the + male element of another, we may believe that it is acted on in a somewhat + similar manner as an individual when exposed to slightly changed + conditions. Now, every one must have observed the remarkable influence on + convalescents of a change of residence, and no medical man doubts the + truth of this fact. Small farmers who hold but little land are convinced + that their cattle derive great benefit from a change of pasture. In the + case of plants, the evidence is strong that a great advantage is derived + from exchanging seeds, tubers, bulbs, and cuttings from one soil or place + to another as different as possible. <!-- Page 146 --><span + class="pagenum"><a name="page146"></a>{146}</span></p> + +<blockquote class="b1n"> + + <p>The belief that plants are thus benefited, whether or not well + founded, has been firmly maintained from the time of Columella, who wrote + shortly after the Christian era, to the present day; and it now prevails + in England, France, and Germany.<a name="NtA_323" + href="#Nt_323"><sup>[323]</sup></a> A sagacious observer, Bradley, + writing in 1724,<a name="NtA_324" href="#Nt_324"><sup>[324]</sup></a> + says, "When we once become Masters of a good Sort of Seed, we should at + least put it into Two or Three Hands, where the Soils and Situations are + as different as possible; and every Year the Parties should change with + one another; by which Means, I find the Goodness of the Seed will be + maintained for several Years. For Want of this Use many Farmers have + failed in their Crops and been great Losers." He then gives his own + practical experience on this head. A modern writer<a name="NtA_325" + href="#Nt_325"><sup>[325]</sup></a> asserts, "Nothing can be more clearly + established in agriculture than that the continual growth of any one + variety in the same district makes it liable to deterioration either in + quality or quantity." Another writer states that he sowed close together + in the same field two lots of wheat-seed, the product of the same + original stock, one of which had been grown on the same land, and the + other at a distance, and the difference in favour of the crop from the + latter seed was remarkable. A gentleman in Surrey who has long made it + his business to raise wheat to sell for seed, and who has constantly + realised in the market higher prices than others, assures me that he + finds it indispensable continually to change his seed; and that for this + purpose he keeps two farms differing much in soil and elevation.</p> + + <p>With respect to the tubers of the potato, I find that at the present + day the practice of exchanging sets is almost everywhere followed. The + great growers of potatoes in Lancashire formerly used to get tubers from + Scotland, but they found that "a change from the moss-lands, and <i>vice + versâ</i>, was generally sufficient." In former times in France the crop + of potatoes in the Vosges had become reduced in the course of fifty or + sixty years in the proportion from 120-150 to 30-40 bushels; and the + famous Oberlin attributed the surprising good which he effected in large + part to changing the sets.<a name="NtA_326" + href="#Nt_326"><sup>[326]</sup></a></p> + + <p>A well-known practical gardener, Mr. Robson<a name="NtA_327" + href="#Nt_327"><sup>[327]</sup></a> positively states that he has himself + witnessed decided advantage from obtaining bulbs of the onion, tubers of + the potato, and various seeds, all of the same kind, from different soils + and distant parts of England. He further states that with <!-- Page 147 + --><span class="pagenum"><a name="page147"></a>{147}</span>plants + propagated by cuttings, as with the Pelargonium, and especially the + Dahlia, manifest advantage is derived from getting plans of the same + variety, which have been cultivated in another place; or, "where the + extent of the place allows, to take cuttings from one description of soil + to plant on another, so as to afford the change that seems so necessary + to the well-being of the plants." He maintains that after a time an + exchange of this nature is "forced on the grower, whether he be prepared + for it or not." Similar remarks have been made by another excellent + gardener, Mr. Fish, namely, that cuttings of the same variety of + Calceolaria, which he obtained from a neighbour, "showed much greater + vigour than some of his own that were treated in exactly the same + manner," and he attributed this solely to his own plants having become + "to a certain extent worn out or tired of their quarters." Something of + this kind apparently occurs in grafting and budding fruit-trees; for, + according to Mr. Abbey, grafts or buds generally take on a distinct + variety or even species, or on a stock previously grafted, with greater + facility than on stocks raised from seeds of the variety which is to be + grafted; and he believes this cannot be altogether explained by the + stocks in question being better adapted to the soil and climate of the + place. It should, however, be added, that varieties grafted or budded on + very distinct kinds, though they may take more readily and grow at first + more vigorously than when grafted on closely allied stocks, afterwards + often become unhealthy.</p> + + <p>I have studied M. Tessier's careful and elaborate experiments,<a + name="NtA_328" href="#Nt_328"><sup>[328]</sup></a> made to disprove the + common belief that good is derived from a change of seed; and he + certainly shows that the same seed may with care be cultivated on the + same farm (it is not stated whether on exactly the same soil) for ten + consecutive years without loss. Another excellent observer, Colonel Le + Couteur,<a name="NtA_329" href="#Nt_329"><sup>[329]</sup></a> has come to + the same conclusion; but then he expressly adds, if the same seed be + used, "that which is grown on land manured from the mixen one year + becomes seed for land prepared with lime, and that again becomes seed for + land dressed with ashes, then for land dressed with mixed manure, and so + on." But this in effect is a systematic exchange of seed, within the + limits of the same farm.</p> + +</blockquote> + + <p>On the whole the belief, which has long been held by many skilful + cultivators, that good follows from exchanging seed, tubers, &c., + seems to be fairly well founded. Considering the small size of most + seeds, it seems hardly credible that the advantage thus derived can be + due to the seeds obtaining in one soil some chemical element deficient in + the other soil. As plants after once germinating naturally become fixed + to the same spot, it might have been anticipated that they would show the + good effects of a change more plainly than animals, which continually + wander about; and this apparently is the <!-- Page 148 --><span + class="pagenum"><a name="page148"></a>{148}</span>case. Life depending + on, or consisting in, an incessant play of the most complex forces, it + would appear that their action is in some way stimulated by slight + changes in the circumstances to which each organism is exposed. All + forces throughout nature, as Mr. Herbert Spencer<a name="NtA_330" + href="#Nt_330"><sup>[330]</sup></a> remarks, tend towards an equilibrium, + and for the life of each being it is necessary that this tendency should + be checked. If these views and the foregoing facts can be trusted, they + probably throw light, on the one hand, on the good effects of crossing + the breed, for the germ will be thus slightly modified or acted on by new + forces; and on the other hand, on the evil effects of close interbreeding + prolonged during many generations, during which the germ will be acted on + by a male having almost identically the same constitution.</p> + +<p class="cenhead"><i>Sterility from changed Conditions of Life.</i></p> + + <p>I will now attempt to show that animals and plants, when removed from + their natural conditions, are often rendered in some degree infertile or + completely barren; and this occurs even when the conditions have not been + greatly changed. This conclusion is not necessarily opposed to that at + which we have just arrived, namely, that lesser changes of other kinds + are advantageous to organic beings. Our present subject is of some + importance, from having an intimate connexion with the causes of + variability. Indirectly it perhaps bears on the sterility of species when + crossed: for as, on the one hand, slight changes in the conditions of + life are favourable to plants and animals, and the crossing of varieties + adds to the size, vigour, and fertility of their offspring; so, on the + other hand, certain other changes in the conditions of life cause + sterility; and as this likewise ensues from crossing much-modified forms + or species, we have a parallel and double series of facts, which + apparently stand in close relation to each other.</p> + + <p>It is notorious that many animals, though perfectly tamed, <!-- Page + 149 --><span class="pagenum"><a name="page149"></a>{149}</span>refuse to + breed in captivity. Isidore Geoffroy St. Hilaire<a name="NtA_331" + href="#Nt_331"><sup>[331]</sup></a> consequently has drawn a broad + distinction between tamed animals which will not breed under captivity, + and truly domesticated animals which breed freely—generally more + freely, as shown in the sixteenth chapter, than in a state of nature. It + is possible and generally easy to tame most animals; but experience has + shown that it is difficult to get them to breed regularly, or even at + all. I shall discuss this subject in detail; but will give only those + cases which seem most illustrative. My materials are derived from notices + scattered through various works, and especially from a Report, drawn up + for me by the kindness of the officers of the Zoological Society of + London, which has especial value, as it records all the cases, during + nine years from 1838-46, in which the animals were seen to couple but + produced no offspring, as well as the cases in which they never, as far + as known, coupled. This MS. Report I have corrected by the annual Reports + subsequently published. Many facts are given on the breeding of the + animals in that magnificent work, 'Gleanings from the Menageries of + Knowsley Hall,' by Dr. Gray. I made, also, particular inquiries from the + experienced keeper of the birds in the old Surrey Zoological Gardens. I + should premise that a slight change in the treatment of animals sometimes + makes a great difference in their fertility; and it is probable that the + results observed in different menageries would differ. Indeed some + animals in our Zoological Gardens have become more productive since the + year 1846. It is, also, manifest from F. Cuvier's account of the Jardin + des Plantes,<a name="NtA_332" href="#Nt_332"><sup>[332]</sup></a> that + the animals formerly bred much less freely there than with us; for + instance, in the Duck tribe, which is highly prolific, only one species + had at that period produced young.</p> + +<blockquote class="b1n"> + + <p>The most remarkable cases, however, are afforded by animals kept in + their native country, which, though perfectly tamed, quite healthy, and + allowed some freedom, are absolutely incapable of breeding. Rengger,<a + name="NtA_333" href="#Nt_333"><sup>[333]</sup></a> who in Paraguay + particularly attended to this subject, specifies six quadrupeds in this + condition; and he mentions two or three others which most rarely <!-- + Page 150 --><span class="pagenum"><a + name="page150"></a>{150}</span>breed. Mr. Bates, in his admirable work on + the Amazons, strongly insists on similar cases;<a name="NtA_334" + href="#Nt_334"><sup>[334]</sup></a> and he remarks, that the fact of + thoroughly tamed native mammals and birds not breeding when kept by the + Indians, cannot be wholly accounted for by their negligence or + indifference, for the turkey is valued by them, and the fowl has been + adopted by the remotest tribes. In almost every part of the + world—for instance, in the interior of Africa, and in several of + the Polynesian islands—the natives are extremely fond of taming the + indigenous quadrupeds and birds; but they rarely or never succeed in + getting them to breed.</p> + + <p>The most notorious case of an animal not breeding in captivity is that + of the elephant. Elephants are kept in large numbers in their native + Indian home, live to old age, and are vigorous enough for the severest + labour; yet, with one or two exceptions, they have never been known even + to couple, though both males and females have their proper periodical + seasons. If, however, we proceed a little eastward to Ava, we hear from + Mr. Crawfurd<a name="NtA_335" href="#Nt_335"><sup>[335]</sup></a> that + their "breeding in the domestic state, or at least in the half-domestic + state in which the female elephants are generally kept, is of every-day + occurrence;" and Mr. Crawfurd informs me that he believes that the + difference must be attributed solely to the females being allowed to roam + the forests with some degree of freedom. The captive rhinoceros, on the + other hand, seems from Bishop Heber's account<a name="NtA_336" + href="#Nt_336"><sup>[336]</sup></a> to breed in India far more readily + than the elephant. Four wild species of the horse genus have bred in + Europe, though here exposed to a great change in their natural habits of + life; but the species have generally been crossed one with another. Most + of the members of the pig family breed readily in our menageries: even + the Red River hog (<i>Potamochœrus penicillatus</i>), from the + sweltering plains of West Africa, has bred twice in the Zoological + Gardens. Here also the Peccary (<i>Dicotyles torquatus</i>) has bred + several times; but another species, the <i>D. labiatus</i>, though + rendered so tame as to be half-domesticated, breeds so rarely in its + native country of Paraguay, that according to Rengger<a name="NtA_337" + href="#Nt_337"><sup>[337]</sup></a> the fact requires confirmation. Mr. + Bates remarks that the tapir, though often kept tame in Amazonia by the + Indians, never breeds.</p> + + <p>Ruminants generally breed quite freely in England, though brought from + widely different climates, as may be seen in the Annual Reports of the + Zoological Gardens, and in the Gleanings from Lord Derby's menagerie.</p> + + <p>The Carnivora, with the exception of the Plantigrade division, + generally breed (though with capricious exceptions) almost as freely as + ruminants. Many species of Felidæ have bred in various menageries, + although imported from various climates and closely confined. Mr. + Bartlett, the present superintendent of the Zoological Gardens,<a + name="NtA_338" href="#Nt_338"><sup>[338]</sup></a> remarks that the lion + appears to breed more frequently and to bring forth more young at a birth + than any other species of the family. He adds that the tiger has rarely + bred; <!-- Page 151 --><span class="pagenum"><a + name="page151"></a>{151}</span>"but there are several well-authenticated + instances of the female tiger breeding with the lion." Strange as the + fact may appear, many animals under confinement unite with distinct + species and produce hybrids quite as freely as, or even more freely than, + with their own species. On inquiring from Dr. Falconer and others, it + appears that the tiger when confined in India does not breed, though it + has been known to couple. The cheetah (<i>Felis jubata</i>) has never + been known by Mr. Bartlett to breed in England, but it has bred at + Frankfort; nor does it breed in India, where it is kept in large numbers + for hunting; but no pains would be taken to make them breed, as only + those animals which have hunted for themselves in a state of nature are + serviceable and worth training.<a name="NtA_339" + href="#Nt_339"><sup>[339]</sup></a> According to Rengger, two species of + wild cats in Paraguay, though thoroughly tamed, have never bred. Although + so many of the Felidæ breed readily in the Zoological Gardens, yet + conception by no means always follows union: in the nine-year Report, + various species are specified which were observed to couple seventy-three + times, and no doubt this must have passed many times unnoticed; yet from + the seventy-three unions only fifteen births ensued. The Carnivora in the + Zoological Gardens were formerly less freely exposed to the air and cold + than at present, and this change of treatment, as I was assured by the + former superintendent, Mr. Miller, greatly increased their fertility. Mr. + Bartlett, and there cannot be a more capable judge, says, "it is + remarkable that lions breed more freely in travelling collections than in + the Zoological Gardens; probably the constant excitement and irritation + produced by moving from place to place, or change of air, may have + considerable influence in the matter."</p> + + <p>Many members of the Dog family breed readily when confined. The Dhole + is one of the most untameable animals in India, yet a pair kept there by + Dr. Falconer produced young. Foxes, on the other hand, rarely breed, and + I have never heard of such an occurrence with the European fox: the + silver fox of North America (<i>Canis argentatus</i>), however, has bred + several times in the Zoological Gardens. Even the otter has bred there. + Every one knows how readily the semi-domesticated ferret breeds, though + shut up in miserably small cages; but other species of Viverra and + Paradoxurus absolutely refuse to breed in the Zoological Gardens. The + Genetta has bred both here and in the Jardin des Plantes, and produced + hybrids. The <i>Herpestes fasciatus</i> has likewise bred; but I was + formerly assured that the <i>H. griseus</i>, though many were kept in the + Gardens, never bred.</p> + + <p>The Plantigrade Carnivora breed under confinement much less freely, + without our being able to assign any reason, than other members of the + group. In the nine-year Report it is stated that the bears had been seen + in the Zoological Gardens to couple freely, but previously to 1848 had + most rarely conceived. In the Reports published since this date three + species have produced young (hybrids in one case), and, wonderful to + relate, the white Polar bear has produced young. The badger (<i>Meles + taxus</i>) has bred several times in the Gardens; but I have not heard of + this <!-- Page 152 --><span class="pagenum"><a + name="page152"></a>{152}</span>occurring elsewhere in England, and the + event must be very rare, for an instance in Germany has been thought + worth recording.<a name="NtA_340" href="#Nt_340"><sup>[340]</sup></a> In + Paraguay the native Nasua, though kept in pairs during many years and + perfectly tamed, has never been known, according to Rengger, to breed or + show any sexual passion; nor, as I hear from Mr. Bates, does this animal, + or the Cercoleptes, breed in the region of the Amazons. Two other + plantigrade genera, Procyon and Gulo, though often kept tame in Paraguay, + never breed there. In the Zoological Gardens species of Nasua and Procyon + have been seen to couple; but they did not produce young.</p> + + <p>As domesticated rabbits, guinea-pigs, and white mice breed so + abundantly when closely confined under various climates, it might have + been thought that most other members of the Rodent order would have bred + in captivity, but this is not the case. It deserves notice, as showing + how the capacity to breed sometimes goes by affinity, that the one native + rodent of Paraguay, which there breeds <i>freely</i> and has yielded + successive generations, is the <i>Cavia aperea</i>; and this animal is so + closely allied to the guinea-pig, that it has been erroneously thought to + be the parent-form.<a name="NtA_341" href="#Nt_341"><sup>[341]</sup></a> + In the Zoological Gardens, some rodents have coupled, but have never + produced young; some have neither coupled nor bred; but a few have bred, + as the porcupine more than once, the Barbary mouse, lemming, chinchilla, + and the agouti (<i>Dasyprocta aguti</i>), several times. This latter + animal has also produced young in Paraguay, though they were born dead + and ill-formed; but in Amazonia, according to Mr. Bates, it never breeds, + though often kept tame about the houses. Nor does the paca + (<i>Cœlogenys paca</i>) breed there. The common hare when confined + has, I believe, never bred in Europe;<a name="NtA_342" + href="#Nt_342"><sup>[342]</sup></a> though, according to a recent + statement, it has crossed with the rabbit. I have never heard of the + dormouse breeding in confinement. But squirrels offer a more curious + case: with one exception, no species has ever bred in the Zoological + Gardens, yet as many as fourteen individuals of <i>S. palmarum</i> were + kept together during several years. The <i>S. cinerea</i> has been seen + to couple, but it did not produce young; nor has this species, when + rendered extremely tame in its native country, North America, been ever + known to breed.<a name="NtA_343" href="#Nt_343"><sup>[343]</sup></a> At + Lord Derby's menagerie squirrels of many kinds were kept in numbers, but + Mr. Thompson, the superintendent, told me that none had ever bred there, + or elsewhere as far as he knew. I have never heard of the English + squirrel breeding in confinement. But the species which has bred more + than once in the Zoological Gardens is the one which perhaps might have + been least expected, namely, the flying squirrel (<i>Sciuropterus + volucella</i>): it has, also, bred several times <!-- Page 153 --><span + class="pagenum"><a name="page153"></a>{153}</span>near Birmingham; but + the female never produced more than two young at a birth, whereas in its + native American home she bears from three to six young.<a name="NtA_344" + href="#Nt_344"><sup>[344]</sup></a></p> + + <p>Monkeys, in the nine-year Report from the Zoological Gardens, are + stated to unite most freely, but during this period, though many + individuals were kept, there were only seven births. I have heard of one + American monkey alone, the Ouistiti, breeding in Europe.<a name="NtA_345" + href="#Nt_345"><sup>[345]</sup></a> A Macacus, according to Flourens, + bred in Paris; and more than one species of this genus has produced young + in London, especially the <i>Macacus rhesus</i>, which everywhere shows a + special capacity to breed under confinement. Hybrids have been produced + both in Paris and London from this same genus. The Arabian baboon, or + <i>Cynocephalus hamadryas</i>,<a name="NtA_346" + href="#Nt_346"><sup>[346]</sup></a> and a Cercopithecus have bred in the + Zoological Gardens, and the latter species at the Duke of + Northumberland's. Several members of the family of Lemurs have produced + hybrids in the Zoological Gardens. It is much more remarkable that + monkeys very rarely breed when confined in their native country; thus the + Cay (<i>Cebus azaræ</i>) is frequently and completely tamed in Paraguay, + but Rengger<a name="NtA_347" href="#Nt_347"><sup>[347]</sup></a> says + that it breeds so rarely, that he never saw more than two females which + had produced young. A similar observation has been made with respect to + the monkeys which are frequently tamed by the aborigines in Brazil.<a + name="NtA_348" href="#Nt_348"><sup>[348]</sup></a> In the region of the + Amazons, these animals are so often kept in a tame state, that Mr. Bates + in walking through the streets of Parà counted thirteen species; but, as + he asserts, they have never been known to breed in captivity.<a + name="NtA_349" href="#Nt_349"><sup>[349]</sup></a></p> + +</blockquote> + +<p class="cenhead"><i>Birds.</i></p> + +<blockquote class="b1n"> + + <p>Birds offer in some respects better evidence than quadrupeds, from + their breeding more rapidly and being kept in greater numbers. We have + seen that carnivorous animals are more fertile under confinement than + most other mammals. The reverse holds good with carnivorous birds. It is + said<a name="NtA_350" href="#Nt_350"><sup>[350]</sup></a> that as many as + eighteen species have been used in Europe for hawking, and several others + in Persia and India;<a name="NtA_351" href="#Nt_351"><sup>[351]</sup></a> + they have been kept in their native country in the finest condition, and + have been flown during six, eight, or nine years;<a name="NtA_352" + href="#Nt_352"><sup>[352]</sup></a> yet there is no record of their + having ever produced young. As these birds were formerly caught whilst + young, at great expense, being imported from Iceland, Norway, and Sweden, + there can <!-- Page 154 --><span class="pagenum"><a + name="page154"></a>{154}</span>be little doubt that, if possible, they + would have been propagated. In the Jardin des Plantes, no bird of prey + has been known to couple.<a name="NtA_353" + href="#Nt_353"><sup>[353]</sup></a> No hawk, vulture, or owl has ever + produced fertile eggs in the Zoological Gardens, or in the old Surrey + Gardens, with the exception, in the former place on one occasion, of a + condor and a kite (<i>Milvus niger</i>). Yet several species, namely, the + <i>Aquila fusca</i>, <i>Haliætus leucocephalus</i>, <i>Falco + tinnunculus</i>, <i>F. subbuteo</i>, and <i>Buteo vulgaris</i>, have been + seen to couple in the Zoological Gardens. Mr. Morris<a name="NtA_354" + href="#Nt_354"><sup>[354]</sup></a> mentions as a unique fact that a + kestrel (<i>Falco tinnunculus</i>) bred in an aviary. The one kind of owl + which has been known to couple in the Zoological Gardens was the Eagle + Owl (<i>Bubo maximus</i>); and this species shows a special inclination + to breed in captivity; for a pair at Arundel Castle, kept more nearly in + a state of nature "than ever fell to the lot of an animal deprived of its + liberty,"<a name="NtA_355" href="#Nt_355"><sup>[355]</sup></a> actually + reared their young. Mr. Gurney has given another instance of this same + owl breeding in confinement; and he records the case of a second species + of owl, the <i>Strix passerina</i>, breeding in captivity.<a + name="NtA_356" href="#Nt_356"><sup>[356]</sup></a></p> + + <p>Of the smaller graminivorous birds, many kinds have been kept tame in + their native countries, and have lived long; yet, as the highest + authority on cage-birds<a name="NtA_357" + href="#Nt_357"><sup>[357]</sup></a> remarks, their propagation is + "uncommonly difficult." The canary-bird shows that there is no inherent + difficulty in these birds breeding freely in confinement; and Audubon + says<a name="NtA_358" href="#Nt_358"><sup>[358]</sup></a> that the + <i>Fringilla</i> (<i>Spiza</i>) <i>ciris</i> of North America breeds as + perfectly as the canary. The difficulty with the many finches which have + been kept in confinement is all the more remarkable as more than a dozen + species could be named which have yielded hybrids with the canary; but + hardly any of these, with the exception of the siskin (<i>Fringilla + spinus</i>), have reproduced their own kind. Even the bullfinch (<i>Loxia + pyrrhula</i>) has bred as frequently with the canary, though belonging to + a distinct genus, as with its own species.<a name="NtA_359" + href="#Nt_359"><sup>[359]</sup></a> With respect to the skylark + (<i>Alauda arvensis</i>), I have heard of birds living for seven years in + an aviary, which never produced young; and a great London bird-fancier + assured me that he had never known an instance of their breeding; + nevertheless one case has been recorded.<a name="NtA_360" + href="#Nt_360"><sup>[360]</sup></a> In the nine-year Report from the + Zoological Society, twenty-four incessorial species are enumerated which + had not bred, and of these only four were known to have coupled.</p> + + <p>Parrots are singularly long-lived birds; and Humboldt mentions the + curious fact of a parrot in South America, which spoke the language of + <!-- Page 155 --><span class="pagenum"><a + name="page155"></a>{155}</span>an extinct Indian tribe, so that this bird + preserved the sole relic of a lost language. Even in this country there + is reason to believe<a name="NtA_361" href="#Nt_361"><sup>[361]</sup></a> + that parrots have lived to the age of nearly one hundred years; yet, + though many have been kept in Europe, they breed so rarely that the event + has been thought worth recording in the gravest publications.<a + name="NtA_362" href="#Nt_362"><sup>[362]</sup></a> According to + Bechstein<a name="NtA_363" href="#Nt_363"><sup>[363]</sup></a> the + African <i>Psittacus erithacus</i> breeds oftener than any other species: + the <i>P. macoa</i> occasionally lays fertile eggs, but rarely succeeds + in hatching them; this bird, however, has the instinct of incubation + sometimes so strongly developed, that it will hatch the eggs of fowls or + pigeons. In the Zoological Gardens and in the old Surrey Gardens some few + species have coupled, but, with the exception of three species of + parrakeets, none have bred. It is a much more remarkable fact that in + Guiana parrots of two kinds, as I am informed by Sir E. Schomburgk, are + often taken from the nests by the Indians and reared in large numbers; + they are so tame that they fly freely about the houses, and come when + called to be fed, like pigeons; yet he has never heard of a single + instance of their breeding.<a name="NtA_364" + href="#Nt_364"><sup>[364]</sup></a> In Jamaica, a resident naturalist, + Mr. R. Hill,<a name="NtA_365" href="#Nt_365"><sup>[365]</sup></a> says, + "no birds more readily submit to human dependence than the parrot-tribe, + but no instance of a parrot breeding in this tame life has been known + yet." Mr. Hill specifies a number of other native birds kept tame in the + West Indies, which never breed in this state.</p> + + <p>The great pigeon family offers a striking contrast with parrots: in + the nine-year Report thirteen species are recorded as having bred, and, + what is more noticeable, only two were seen to couple without any result. + Since the above date every annual Report gives many cases of various + pigeons breeding. The two magnificent crowned pigeons (<i>Goura + coronata</i> and <i>Victoriæ</i>) produced hybrids; nevertheless, of the + former species more than a dozen birds were kept, as I am informed by Mr. + Crawfurd, in a park at Penang, under a perfectly well-adapted climate, + but never once bred. The <i>Columba migratoria</i> in its native country, + North America, invariably lays two eggs, but in Lord Derby's menagerie + never more than one. The same fact has been observed with the <i>C. + leucocephala</i>.<a name="NtA_366" + href="#Nt_366"><sup>[366]</sup></a></p> + + <p>Gallinaceous birds of many genera likewise show an eminent capacity + for breeding under captivity. This is particularly the case with + pheasants; yet our English species seldom lays more than ten eggs in + confinement; whilst from eighteen to twenty is the usual number in the + wild state.<a name="NtA_367" href="#Nt_367"><sup>[367]</sup></a> With the + Gallinaceæ, as with all other orders, there are marked and <!-- Page 156 + --><span class="pagenum"><a name="page156"></a>{156}</span>inexplicable + exceptions in regard to the fertility of certain species and genera under + confinement. Although many trials have been made with the common + partridge, it has rarely bred, even when reared in large aviaries; and + the hen will never hatch her own eggs.<a name="NtA_368" + href="#Nt_368"><sup>[368]</sup></a> The American tribe of Guans or + Cracidæ are tamed with remarkable ease, but are very shy breeders in this + country;<a name="NtA_369" href="#Nt_369"><sup>[369]</sup></a> but with + care various species were formerly made to breed rather freely in + Holland.<a name="NtA_370" href="#Nt_370"><sup>[370]</sup></a> Birds of + this tribe are often kept in a perfectly tamed condition in their native + country by the Indians, but they never breed.<a name="NtA_371" + href="#Nt_371"><sup>[371]</sup></a> It might have been expected that + grouse from their habits of life would not have bred in captivity, more + especially as they are said soon to languish and die.<a name="NtA_372" + href="#Nt_372"><sup>[372]</sup></a> But many cases are recorded of their + breeding: the capercailzie (<i>Tetrao urogallus</i>) has bred in the + Zoological Gardens; it breeds without much difficulty when confined in + Norway, and in Russia five successive generations have been reared: + <i>Tetrao tetrix</i> has likewise bred in Norway; <i>T. Scoticus</i> in + Ireland; <i>T. umbellus</i> at Lord Derby's; and <i>T. cupido</i> in + North America.</p> + + <p>It is scarcely possible to imagine a greater change in habits than + that which the members of the ostrich family must suffer, when cooped up + in small enclosures under a temperate climate, after freely roaming over + desert and tropical plains or entangled forests. Yet almost all the + kinds, even the mooruk (<i><span class="correction" title="Original reads `Casuarinus', corrected by errata, page viii." + >Casuarius</span> Bennettii</i>) from New Ireland, has frequently + produced young in the various European menageries. The African ostrich, + though perfectly healthy and living long in the South of France, never + lays more than from twelve to fifteen eggs, though in its native country + it lays from twenty-five to thirty.<a name="NtA_373" + href="#Nt_373"><sup>[373]</sup></a> Here we have another instance of + fertility impaired, but not lost, under confinement, as with the flying + squirrel, the hen-pheasant, and two species of American pigeons.</p> + + <p>Most Waders can be tamed, as the Rev. E. S. Dixon informs me, with + remarkable facility; but several of them are short-lived under + confinement, so that their sterility in this state is not surprising. The + cranes breed more readily than other genera: <i>Grus montigresia</i> has + bred several times in Paris and in the Zoological Gardens, as has <i>G. + <span class="correction" title="Original reads `cineria', corrected by errata, page viii." + >cinerea</span></i> at the latter place, and <i>G. antigone</i> at + Calcutta. Of other members of this great order, <i>Tetrapteryx + paradisea</i> has bred at Knowsley, a Porphyrio in Sicily, and the + <i>Gallinula chloropus</i> in the Zoological Gardens. On the other hand, + several <!-- Page 157 --><span class="pagenum"><a + name="page157"></a>{157}</span>birds belonging to this order will not + breed in their native country, Jamaica; and the Psophia, though often + kept by the Indians of Guiana about their houses, "is seldom or never + known to breed."<a name="NtA_374" href="#Nt_374"><sup>[374]</sup></a></p> + + <p>No birds breed with such complete facility under confinement as the + members of the great Duck family; yet, considering their aquatic and + wandering habits, and the nature of their food, this could not have been + anticipated. Even some time ago above two dozen species had bred in the + Zoological Gardens; and M. Selys-Longchamps has recorded the production + of hybrids from forty-four different members of the family; and to these + Professor Newton has added a few more cases.<a name="NtA_375" + href="#Nt_375"><sup>[375]</sup></a> "There is not," says Mr. Dixon,<a + name="NtA_376" href="#Nt_376"><sup>[376]</sup></a> "in the wide world, a + goose which is not in the strict sense of the word domesticable;" that + is, capable of breeding under confinement; but this statement is probably + too bold. The capacity to breed sometimes varies in individuals of the + same species; thus Audubon<a name="NtA_377" + href="#Nt_377"><sup>[377]</sup></a> kept for more than eight years some + wild geese (<i>Anser Canadensis</i>), but they would not mate; whilst + other individuals of the same species produced young during the second + year. I know of but one instance in the whole family of a species which + absolutely refuses to breed in captivity, namely, the <i>Dendrocygna + viduata</i>, although, according to Sir R. Schomburgk,<a name="NtA_378" + href="#Nt_378"><sup>[378]</sup></a> it is easily tamed, and is frequently + kept by the Indians of Guiana. Lastly, with respect to Gulls, though many + have been kept in the Zoological Gardens and in the old Surrey Gardens, + no instance was known before the year 1848 of their coupling or breeding; + but since that period the herring gull (<i>Larus argentatus</i>) has bred + many times in the Zoological Gardens and at Knowsley.</p> + + <p>There is reason to believe that insects are affected by confinement + like the higher animals. It is well known that the Sphingidæ rarely breed + when thus treated. An entomologist<a name="NtA_379" + href="#Nt_379"><sup>[379]</sup></a> in Paris kept twenty-five specimens + of <i>Saturnia pyri</i>, but did not succeed in getting a single fertile + egg. A number of females of <i>Orthosia munda</i> and of <i>Mamestra + suasa</i> reared in confinement were unattractive to the males.<a + name="NtA_380" href="#Nt_380"><sup>[380]</sup></a> Mr. Newport kept + nearly a hundred individuals of two species of Vanessa, but not one + paired; this, however, might have been due to their habit of coupling on + the wing.<a name="NtA_381" href="#Nt_381"><sup>[381]</sup></a> Mr. + Atkinson could never succeed in India in making the Tarroo silk-moth + breed in confinement.<a name="NtA_382" + href="#Nt_382"><sup>[382]</sup></a> It appears that a number of moths, + especially the Sphingidæ, when hatched in the autumn out of their proper + season, <!-- Page 158 --><span class="pagenum"><a + name="page158"></a>{158}</span>are completely barren; but this latter + case is still involved in some obscurity.<a name="NtA_383" + href="#Nt_383"><sup>[383]</sup></a></p> + +</blockquote> + + <p>Independently of the fact of many animals under confinement not + coupling, or, if they couple, not producing young, there is evidence of + another kind, that their sexual functions are thus disturbed. For many + cases have been recorded of the loss by male birds when confined of their + characteristic plumage. Thus the common linnet (<i>Linota cannabina</i>) + when caged does not acquire the fine crimson colour on its breast, and + one of the buntings (<i>Emberiza passerina</i>) loses the black on its + head. A Pyrrhula and an Oriolus have been observed to assume the quiet + plumage of the hen-bird; and the <i>Falco albidus</i> returned to the + dress of an earlier age.<a name="NtA_384" + href="#Nt_384"><sup>[384]</sup></a> Mr. Thomson, the superintendent of + the Knowsley menagerie, informed me that he had often observed analogous + facts. The horns of a male deer (<i>Cervus Canadensis</i>) during the + voyage from America were badly developed; but subsequently in Paris + perfect horns were produced.</p> + + <p>When conception takes place under confinement, the young are often + born dead, or die soon, or are ill-formed. This frequently occurs in the + Zoological Gardens, and, according to Rengger, with native animals + confined in Paraguay. The mother's milk often fails. We may also + attribute to the disturbance of the sexual functions the frequent + occurrence of that monstrous instinct which leads the mother to devour + her own offspring,—a mysterious case of perversion, as it at first + appears.</p> + + <p>Sufficient evidence has now been advanced to prove that animals when + first confined are eminently liable to suffer in their reproductive + systems. We feel at first naturally inclined to attribute the result to + loss of health, or at least to loss of vigour; but this view can hardly + be admitted when we reflect how healthy, long-lived, and vigorous many + animals are under <!-- Page 159 --><span class="pagenum"><a + name="page159"></a>{159}</span>captivity, such as parrots, and hawks when + used for hawking, chetahs when used for hunting, and elephants. The + reproductive organs themselves are not diseased; and the diseases, from + which animals in menageries usually perish, are not those which in any + way affect their fertility. No domestic animal is more subject too + disease than the sheep, yet it is remarkably prolific. The failure of + animals to breed under confinement has been sometimes attributed + exclusively to a failure in their sexual instincts: this may occasionally + come into play, but there is no obvious reason why this instinct should + be especially liable to be affected with perfectly tamed animals, except + indeed indirectly through the reproductive system itself being disturbed. + Moreover, numerous cases have been given of various animals which couple + freely under confinement, but never conceive; or, if they conceive and + produce young, these are fewer in number than is natural to the species. + In the vegetable kingdom instinct of course can play no part; and we + shall presently see that plants when removed from their natural + conditions are affected in nearly the same manner as animals. Change of + climate cannot be the cause of the loss of fertility, for, whilst many + animals imported into Europe from extremely different climates breed + freely, many others when confined in their native land are completely + sterile. Change of food cannot be the chief cause; for ostriches, ducks, + and many other animals, which must have undergone a great change in this + respect, breed freely. Carnivorous birds when confined are extremely + sterile; whilst most carnivorous mammals, except plantigrades, are + moderately fertile. Nor can the amount of food be the cause; for a + sufficient supply will certainly be given to valuable animals; and there + is no reason to suppose that much more food would be given to them, than + to our choice domestic productions which retain their full fertility. + Lastly, we may infer from the case of the elephant, chetah, various + hawks, and of many animals which are allowed to lead an almost free life + in their native land, that want of exercise is not the sole cause.</p> + + <p>It would appear that any change in the habits of life, whatever these + habits may be, if great enough, tends to affect in an inexplicable manner + the powers of reproduction. The result <!-- Page 160 --><span + class="pagenum"><a name="page160"></a>{160}</span>depends more on the + constitution of the species than on the nature of the change; for certain + whole groups are affected more than others; but exceptions always occur, + for some species in the most fertile groups refuse to breed, and some in + the most sterile groups breed freely. Those animals which usually breed + freely under confinement, rarely breed, as I was assured, in the + Zoological Gardens, within a year or two after their first importation. + When an animal which is generally sterile under confinement happens to + breed, the young apparently do not inherit this power; for had this been + the case, various quadrupeds and birds, which are valuable for + exhibition, would have become common. Dr. Broca even affirms<a + name="NtA_385" href="#Nt_385"><sup>[385]</sup></a> that many animals in + the Jardin des Plantes, after having produced young for three or four + successive generations, become sterile; but this may be the result of too + close interbreeding. It is a remarkable circumstance that many mammals + and birds have produced hybrids under confinement quite as readily as, or + even more readily than, they have procreated their own kind. Of this fact + many instances have been given;<a name="NtA_386" + href="#Nt_386"><sup>[386]</sup></a> and we are thus reminded of those + plants which when cultivated refuse to be fertilised by their own pollen, + but can easily be fertilised by that of a distinct species. Finally, we + must conclude, limited as the conclusion is, that changed conditions of + life have an especial power of acting injuriously on the reproductive + system. The whole case is quite peculiar, for these organs, though not + diseased, are thus rendered incapable of performing their proper + functions, or perform them imperfectly.</p> + +<blockquote class="b1n"> + + <p><i>Sterility of Domesticated Animals from changed + conditions.</i>—With respect to domesticated animals, as their + domestication mainly depends on the accident of their breeding freely + under captivity, we ought not to expect that their reproductive system + would be affected by any moderate degree of change. Those orders of + quadrupeds and birds, of which the wild species breed most readily in our + menageries, have afforded us the greatest number of domesticated + productions. Savages in most parts of the world are fond of taming + animals;<a name="NtA_387" href="#Nt_387"><sup>[387]</sup></a> and if any + of these regularly produced <!-- Page 161 --><span class="pagenum"><a + name="page161"></a>{161}</span>young, and were at the same time useful, + they would be at once domesticated. If, when their masters migrated into + other countries, they were in addition found capable of withstanding + various climates, they would be still more valuable; and it appears that + the animals which breed readily in captivity can generally withstand + different climates. Some few domesticated animals, such as the reindeer + and camel, offer an exception to this rule. Many of our domesticated + animals can bear with undiminished fertility the most unnatural + conditions; for instance, rabbits, guinea-pigs, and ferrets breed in + miserably confined hutches. Few European dogs of any kind withstand + without degeneration the climate of India; but as long as they survive, + they retain, as I hear from Mr. Falconer, their fertility; so it is, + according to Dr. Daniell, with English dogs taken to Sierra Leone. The + fowl, a native of the hot jungles of India, becomes more fertile than its + parent-stock in every quarter of the world, until we advance as far north + as Greenland and Northern Siberia, where this bird will not breed. Both + fowls and pigeons, which I received during the autumn direct from Sierra + Leone, were at once ready to couple.<a name="NtA_388" + href="#Nt_388"><sup>[388]</sup></a> I have, also, seen pigeons breeding + as freely as the common kinds within a year after their importation from + the Upper Nile. The guinea-fowl, an aboriginal of the hot and dry deserts + of Africa, whilst living under our damp and cool climate, produces a + large supply of eggs.</p> + + <p>Nevertheless, our domesticated animals under new conditions + occasionally show signs of lessened fertility. Roulin asserts that in the + hot valleys of the equatorial Cordillera sheep are not fully fecund;<a + name="NtA_389" href="#Nt_389"><sup>[389]</sup></a> and according to Lord + Somerville,<a name="NtA_390" href="#Nt_390"><sup>[390]</sup></a> the + merino-sheep which he imported from Spain were not at first perfectly + fertile. It is said<a name="NtA_391" href="#Nt_391"><sup>[391]</sup></a> + that mares brought up on dry food in the stable, and turned out to grass, + do not at first breed. The peahen, as we have seen, is said not to lay so + many eggs in England as in India. It was long before the canary-bird was + fully fertile, and even now first-rate breeding birds are not common.<a + name="NtA_392" href="#Nt_392"><sup>[392]</sup></a> In the hot and dry + province of Delhi, the eggs of the turkey, as I hear from Dr. Falconer, + though placed under a hen, are extremely liable to fail. According to + Roulin, geese taken within a recent period to the lofty plateau of + Bogota, at first laid seldom, and then only a few eggs; of these scarcely + a fourth were hatched, and half the young birds died: in the second + generation they were more fertile; and when Roulin wrote they were + becoming as <!-- Page 162 --><span class="pagenum"><a + name="page162"></a>{162}</span>fertile as our geese in Europe. In the + Philippine Archipelago the goose, it is asserted, will not breed or even + lay eggs.<a name="NtA_393" href="#Nt_393"><sup>[393]</sup></a> A more + curious case is that of the fowl, which, according to Roulin, when first + introduced would not breed at Cusco in Bolivia, but subsequently became + quite fertile; and the English Game fowl, lately introduced, had not as + yet arrived a its full fertility, for to raise two or three chickens from + a nest of eggs was thought fortunate. In Europe close confinement has a + marked effect on the fertility of the fowl: it has been found in France + that with fowls allowed considerable freedom only twenty per cent. of the + eggs failed; when allowed less freedom forty per cent. failed; and in + close confinement sixty out of the hundred were not hatched.<a + name="NtA_394" href="#Nt_394"><sup>[394]</sup></a> So we see that + unnatural and changed conditions of life produce some effect on the + fertility of our most thoroughly domesticated animals, in the same + manner, though in a far less degree, as with captive wild animals.</p> + + <p>It is by no means rare to find certain males and females which will + not breed together, though both are known to be perfectly fertile with + other males and females. We have no reason to suppose that this is caused + by these animals having been subjected to any change in their habits of + life; therefore such cases are hardly related to our present subject. The + cause apparently lies in an innate sexual incompatibility of the pair + which are matched. Several instances have been communicated to me by Mr. + W. C. Spooner (well known for his essay on Cross-breeding), by Mr. Eyton + of Eyton, by Mr. Wicksted and othe breeders, and especially by Mr. Waring + of Chelsfield, in relation to horses, cattle, pigs, foxhounds, other + dogs, and pigeons.<a name="NtA_395" href="#Nt_395"><sup>[395]</sup></a> + In these cases, females, which either previously or subsequently were + proved to be fertile, failed to breed with certain males, with whom it + was particularly desired to match them. A change in the constitution of + the female may sometimes have occurred before she was put to the second + male; but in other cases this explanation is hardly tenable, for a + female, known not to be barren, has been unsuccessfully paired seven or + eight times with the same male likewise known to be perfectly fertile. + With cart-mares, which sometimes will not breed with stallions of pure + blood, but subsequently have bred with cart-stallions, Mr. Spooner is + inclined to attribute the failure to the lesser sexual power of the + race-horse. But I have heard from the greatest breeder of race-horses at + the present day, through Mr. Waring, that "it frequently occurs with a + mare to be put several times during one or two seasons to a particular + stallion of acknowledged power, and yet prove barren; the mare afterwards + breeding at once with some other horse." These facts are worth recording, + as they show, like so many previous facts, on what slight constitutional + differences the fertility of an animal often depends.</p> + +</blockquote> + +<p><!-- Page 163 --><span class="pagenum"><a name="page163"></a>{163}</span></p> + +<p class="cenhead"><i>Sterility of Plants from changed Conditions of Life, and from +other causes.</i></p> + + <p>In the vegetable kingdom cases of sterility frequently occur, + analogous with those previously given in the animal kingdom. But the + subject is obscured by several circumstances, presently to be discussed, + namely, the contabescence of the anthers, as Gärtner has named a certain + affection—monstrosities—doubleness of the + flower—much-enlarged fruit—and long-continued or excessive + propagation by buds.</p> + +<blockquote class="b1n"> + + <p>It is notorious that many plants in our gardens and hot-houses, though + preserved in the most perfect health, rarely or never produce seed. I do + not allude to plants which run to leaves, from being kept too damp, or + too warm, or too much manured; for these do not produce the reproductive + individual or flower, and the case may be wholly different. Nor do I + allude to fruit not ripening from want of heat, or rotting from too much + moisture. But many exotic plants, with their ovules and pollen appearing + perfectly sound, will not set any seed. The sterility in many cases, as I + know from my own observation, is simply due to the absence of the proper + insects for carrying the pollen to the stigma. But after excluding the + several cases just specified, there are many plants in which the + reproductive system has been seriously affected by the altered conditions + of life to which they have been subjected.</p> + + <p>It would be tedious to enter on many details. Linnæus long ago + observed<a name="NtA_396" href="#Nt_396"><sup>[396]</sup></a> that Alpine + plants, although naturally laded with seed, produce either few or none + when cultivated in gardens. But exceptions often occur: the <i>Draba + sylvestris</i>, one of our most thoroughly Alpine plants, multiplies + itself by seed in Mr. H. C. Watson's garden, near London; and Kerner, who + has particularly attended to the cultivation of Alpine plants, found that + various kinds, when cultivated, spontaneously sowed themselves.<a + name="NtA_397" href="#Nt_397"><sup>[397]</sup></a> Many plants which + naturally grow in peat-earth are entirely sterile in our gardens. I have + noticed the same fact with several liliaceous plants, which nevertheless + grew vigorously.</p> + + <p>Too much manure renders some kinds utterly sterile, as I have myself + observed. The tendency to sterility from this cause runs in families; + thus, according to Gärtner,<a name="NtA_398" + href="#Nt_398"><sup>[398]</sup></a> it is hardly possible to give too + much manure to most Gramineæ, Cruciferæ, and Leguminosæ, whilst succulent + and bulbous-rooted plants are easily affected. Extreme poverty of soil is + less <!-- Page 164 --><span class="pagenum"><a + name="page164"></a>{164}</span>apt to induce sterility; but dwarfed + plants of <i>Trifolium minus</i> and <i>repens</i>, growing on a lawn + often mown and never manured, did not produce any seed. The temperature + of the soil, and the season at which plants are watered, often have a + marked effect on their fertility, as was observed by Kölreuter in the + case of Mirabilis.<a name="NtA_399" href="#Nt_399"><sup>[399]</sup></a> + Mr. Scott in the Botanic Gardens of Edinburgh observed that <i>Oncidium + divaricatum</i> would not set seed when grown in a basket in which it + throve, but was capable of fertilisation in a pot where it was a little + damper. <i>Pelargonium fulgidum</i>, for many years after its + introduction, seeded freely; it then became sterile; now it is fertile<a + name="NtA_400" href="#Nt_400"><sup>[400]</sup></a> if kept in a dry stove + during the winter. Other varieties of pelargonium are sterile and others + fertile without our being able to assign any cause. Very slight changes + in the position of a plant, whether planted on a bank or at its base, + sometimes make all the difference in its producing seed. Temperature + apparently has a much more powerful influence on the fertility of plants + than on that of animals. Nevertheless it is wonderful what changes some + few plants will withstand with undiminished fertility: thus the + <i>Zephyranthes candida</i>, a native of the moderately warm banks of the + Plata, sows itself in the hot dry country near Lima, and in Yorkshire + resists the severest frosts, and I have seen seeds gathered from pods + which had been covered with snow during three weeks.<a name="NtA_401" + href="#Nt_401"><sup>[401]</sup></a> <i>Berberis Wallichii</i>, from the + hot Khasia range in India, is uninjured by our sharpest frosts, and + ripens its fruit under our cool summers. Nevertheless I presume we must + attribute to change of climate the sterility of many foreign plants; thus + the Persian and Chinese lilacs (<i>Syringa Persica</i> and + <i>Chinensis</i>), though perfectly hardly, never here produce a seed; + the common lilac (<i>S. vulgaris</i>) seeds with us moderately well, but + in parts of Germany the capsules never contain seed.<a name="NtA_402" + href="#Nt_402"><sup>[402]</sup></a></p> + + <p>Some of the cases, given in the last chapter, of self-impotent plants, + which are fertile both on the male and female side when united with + distinct individuals or species, might have been here introduced; for as + this peculiar form of sterility generally occurs with exotic plants or + with endemic plants cultivated in pots, and as it disappeared in the + <i>Passiflora alata</i> when grafted, we may conclude that in these cases + it is the result of the treatment to which the plants or their parents + have been exposed.</p> + + <p>The liability of plants to be affected in their fertility by slightly + changed conditions is the more remarkable, as the pollen when once in + process of formation is not easily injured; a plant may be transplanted, + or a branch with flower-buds be cut off and placed in water, and the + pollen will be matured. Pollen, also, when once mature, may be kept for + weeks or even months.<a name="NtA_403" + href="#Nt_403"><sup>[403]</sup></a> The female organs are more sensitive, + for Gärtner<a name="NtA_404" href="#Nt_404"><sup>[404]</sup></a> found + that dicotyledonous plants, when carefully removed so that they did not + in the least flag, could seldom be fertilised; this occurred even with + potted <!-- Page 165 --><span class="pagenum"><a + name="page165"></a>{165}</span>plants if the roots had grown out of the + hole at the bottom. In some few cases, however, as with Digitalis, + transplantation did not prevent fertilisation; and according to the + testimony of Mawz, <i>Brassica rapa</i>, when pulled up by its roots and + placed in water, ripened its seed. Flower-stems of several + monocotyledonous plants when cut off and placed in water likewise produce + seed. But in these cases I presume that the flowers had been already + fertilised, for Herbert<a name="NtA_405" + href="#Nt_405"><sup>[405]</sup></a> found with the Crocus that the plants + might be removed or mutilated after the act of fertilisation, and would + still perfect their seeds; but that, if transplanted before being + fertilised, the application of pollen was powerless.</p> + + <p>Plants which have been long cultivated can generally endure with + undiminished fertility various and great changes; but not in most cases + so great a change of climate as domesticated animals. It is remarkable + that many plants under these circumstances are so much affected that the + proportions and the nature of their chemical ingredients are modified, + yet their fertility is unimpaired. Thus, as Dr. Falconer informs me, + there is a great difference in the character of the fibre in hemp, in the + quantity of oil in the seed of the Linum, in the proportion of narcotin + to morphine in the poppy, in gluten to starch in wheat, when these plants + are cultivated on the plains and on the mountains of India; nevertheless, + they all remain fully fertile.</p> + + <p><i>Contabescence.</i>—Gärtner has designated by this term a + peculiar condition of the anthers in certain plants, in which they are + shrivelled, or become brown and tough, and contain no good pollen. When + in this state they exactly resemble the anthers of the most sterile + hybrids. Gärtner,<a name="NtA_406" href="#Nt_406"><sup>[406]</sup></a> in + his discussion on this subject, has shown that plants of many orders are + occasionally thus affected; but the Caryophyllaceæ and Liliaceæ suffer + most, and to these orders, I think, the Ericaceæ may be added. + Contabescence varies in degree, but on the same plant all the flowers are + generally affected to nearly the same extent. The anthers are affected at + a very early period in the flower-bud, and remain in the same state (with + one recorded exception) during the life of the plant. The affection + cannot be cured by any change of treatment, and is propagated by layers, + cuttings, &c., and perhaps even by seed. In contabescent plants the + female organs are seldom affected, or merely become precocious in their + development. The cause of this affection is doubtful, and is different in + different cases. Until I read Gärtner's discussion I attributed it, as + apparently did Herbert, to the unnatural treatment of the plants; but its + permanence under changed conditions, and the female organs not being + affected, seem incompatible with this view. The fact of several endemic + plants becoming contabescent in our gardens seems, at first sight, + equally incompatible with this view; but Kölreuter believes that this is + the result of their transplantation. The contabescent plants of Dianthus + and Verbascum, found wild by Wiegmann, grew on a dry and sterile bank. + The fact that exotic <!-- Page 166 --><span class="pagenum"><a + name="page166"></a>{166}</span>plants are eminently liable to this + affection also seems to show that it is in some manner caused by their + unnatural treatment. In some instances, as with Silene, Gärtner's view + seems the most probable, namely, that it is caused by an inherent + tendency in the species to become diœcious. I can add another + cause, namely, the illegitimate unions of reciprocally dimorphic or + trimorphic plants, for I have observed seedlings of three species of + Primula and of <i>Lythrum salicaria</i>, which had been raised from + plants illegitimately fertilised by their own-form pollen, with some or + all their anthers in a contabescent state. There is perhaps an additional + cause, namely, self-fertilisation; for many plants of Dianthus and + Lobelia, which had been raised from self-fertilised seeds, had their + anthers in this state; but these instances are not conclusive, as both + genera are liable from other causes to this affection.</p> + + <p>Cases of an opposite nature likewise occur, namely, plants with the + female organs struck with sterility, whilst the male organs remain + perfect. <i>Dianthus Japonicus</i>, a Passiflora, and Nicotiana, have + been described by Gärtner<a name="NtA_407" + href="#Nt_407"><sup>[407]</sup></a> as being in this unusual + condition.</p> + + <p><i>Monstrosities as a cause of Sterility.</i>—Great deviations + of structure, even when the reproductive organs themselves are not + seriously affected, sometimes cause plants to become sterile. But in + other cases plants may become monstrous to an extreme degree and yet + retain their full fertility. Gallesio, who certainly had great + experience,<a name="NtA_408" href="#Nt_408"><sup>[408]</sup></a> often + attributes sterility to this cause; but it may be suspected that in some + of his cases sterility was the cause, and not the result, of the + monstrous growths. The curious St. Valery apple, although it bears fruit, + rarely produces seed. The wonderfully anomalous flowers of <i>Begonia + frigida</i>, formerly described, though they appear fit for + fructification, are sterile.<a name="NtA_409" + href="#Nt_409"><sup>[409]</sup></a> Species of Primulæ, in which the + calyx is brightly coloured, are said<a name="NtA_410" + href="#Nt_410"><sup>[410]</sup></a> to be often sterile, though I have + known them to be fertile. On the other hand, Verlot gives several cases + of proliferous flowers which can be propagated by seed. This was the case + with a poppy, which had become monopetalous by the union of its petals.<a + name="NtA_411" href="#Nt_411"><sup>[411]</sup></a> Another extraordinary + poppy, with the stamens replaced by numerous small supplementary + capsules, likewise reproduces itself by seed. This has also occurred with + a plant of <i>Saxifraga geum</i>, in which a series of adventitious + carpels, bearing ovules on their margins, had been developed between the + stamens and the normal carpels.<a name="NtA_412" + href="#Nt_412"><sup>[412]</sup></a> Lastly, with respect to peloric + flowers, which depart wonderfully from the natural structure,—those + of <i>Linaria vulgaris</i> seem generally to be more or less sterile, + whilst those before described of <i>Antirrhinum majus</i>, when + artificially fertilised with their own pollen, are perfectly <!-- Page + 167 --><span class="pagenum"><a name="page167"></a>{167}</span>fertile, + though sterile when left to themselves, for bees are unable to crawl into + the narrow tubular flower. The peloric flowers of <i>Corydalis + solida</i>, according to Godron,<a name="NtA_413" + href="#Nt_413"><sup>[413]</sup></a> are barren; whilst those of Gloxinia + are well known to yield plenty of seed. In our greenhouse Pelargoniums, + the central flower of the truss is often peloric, and Mr. Masters informs + me that he tried in vain during several years to get seed from these + flowers. I likewise made many vain attempts, but sometimes succeeded in + fertilising them with pollen from a normal flower of another variety; and + conversely I several times fertilised ordinary flowers with peloric + pollen. Only once I succeeded in raising a plant from a peloric flower + fertilised by pollen from a peloric flower borne by another variety; but + the plant, it may be added, presented nothing particular in its + structure. Hence we may conclude that no general rule can be laid down; + but any great deviation from the normal structure, even when the + reproductive organs themselves are not seriously affected, certainly + often leads to sexual impotence.</p> + + <p><i>Double Flowers.</i>—When the stamens are converted into + petals, the plant becomes on the male side sterile; when both stamens and + pistils are thus changed, the plant becomes completely barren. + Symmetrical flowers having numerous stamens and petals are the most + liable to become double, as perhaps follows from all multiple organs + being the most subject to variability. But flowers furnished with only a + few stamens, and others which are asymmetrical in structure, sometimes + become double, as we see with the double gorse or Ulex, Petunia, and + Antirrhinum. The Compositæ bear what are called double flowers by the + abnormal development of the corolla of their central florets. Doubleness + is sometimes connected with prolification,<a name="NtA_414" + href="#Nt_414"><sup>[414]</sup></a> or the continued growth of the axis + of the flower. Doubleness is strongly inherited. No one has produced, as + Lindley remarks,<a name="NtA_415" href="#Nt_415"><sup>[415]</sup></a> + double flowers by promoting the perfect health of the plant. On the + contrary, unnatural conditions of life favour their production. There is + some reason to believe that seeds kept during many years, and seeds + believed to be imperfectly fertilised, yield double flowers more freely + than fresh and perfectly fertilised seed.<a name="NtA_416" + href="#Nt_416"><sup>[416]</sup></a> Long-continued cultivation in rich + soil seems to be the commonest exciting cause. A double narcissus and a + double <i>Anthemis nobilis</i>, transplanted into very poor soil, have + been observed to become single;<a name="NtA_417" + href="#Nt_417"><sup>[417]</sup></a> and I have seen a completely double + white primrose rendered permanently single by being divided and + transplanted whilst in full flower. It has been observed by Professor + Morren that doubleness of the flowers and variegation of the leaves are + antagonistic states; but so many exceptions to the rule have lately been + recorded,<a name="NtA_418" href="#Nt_418"><sup>[418]</sup></a> that, + though general, it cannot be looked at as invariable. <!-- Page 168 + --><span class="pagenum"><a name="page168"></a>{168}</span>Variegation + seems generally to result from a feeble or atrophied condition of the + plant, and a large proportion of the seedlings raised from parents both + of which are variegated usually perish at an early age; hence we may + perhaps infer that doubleness, which is the antagonistic state, commonly + arises from a plethoric condition. On the other hand, extremely poor soil + sometimes, though rarely, appears to cause doubleness: I formerly + described<a name="NtA_419" href="#Nt_419"><sup>[419]</sup></a> some + completely double, bud-like, flowers produced in large numbers by stunted + wild plants of <i>Gentiana amarella</i> growing on a poor chalky bank. I + have also noticed a distinct tendency to doubleness in the flowers of a + Ranunculus, Horse-chesnut, and Bladder-nut (<i>Ranunculus repens</i>, + <i><span class="correction" title="Original reads `Œsculus', corrected by errata, page viii." + >Æsculus</span> pavia</i>, and <i>Staphylea</i>), growing under very + unfavourable conditions. Professor Lehman<a name="NtA_420" + href="#Nt_420"><sup>[420]</sup></a> found several wild plants growing + near a hot spring with double flowers. With respect to the cause of + doubleness, which arises, as we see, under widely different + circumstances, I shall presently attempt to show that the most probable + view is that unnatural conditions first give a tendency to sterility, and + that then, on the principle of compensation, as the reproductive organs + do not perform their proper functions, they either become developed into + petals, or additional petals are formed. This view has lately been + supported by Mr. Laxton,<a name="NtA_421" + href="#Nt_421"><sup>[421]</sup></a> who advances the case of some common + peas, which, after long-continued heavy rain, flowered a second time, and + produced double flowers.</p> + + <p><i>Seedless Fruit.</i>—Many of our most valuable fruits, + although consisting in a homological sense of widely different organs, + are either quite sterile, or produce extremely few seeds. This is + notoriously the case with our best pears, grapes, and figs, with the + pine-apple, banana, bread-fruit, pomegranate, azarole, date-palms, and + some members of the orange-tribe. Poorer varieties of these same fruits + either habitually or occasionally yield seed.<a name="NtA_422" + href="#Nt_422"><sup>[422]</sup></a> Most horticulturists look at the + great size and anomalous development of the fruit as the cause, and + sterility as the result; but the opposite view, as we shall presently + see, is more probable.</p> + + <p><i>Sterility from the excessive development of the Organs of Growth or + Vegetation.</i>—Plants which from any cause grow too luxuriantly, + and produce leaves, stems, runners, suckers, tubers, bulbs, &c., in + excess, sometimes do not flower, or if they flower do not yield seed. To + make European vegetables under the hot climate of India yield seed, it is + necessary to check their growth; and, when one-third grown, they are + taken up, and their stems and <!-- Page 169 --><span class="pagenum"><a + name="page169"></a>{169}</span>tap-roots are cut or mutilated.<a + name="NtA_423" href="#Nt_423"><sup>[423]</sup></a> So it is with hybrids; + for instance, Prof. Lecoq<a name="NtA_424" + href="#Nt_424"><sup>[424]</sup></a> had three plants of Mirabilis, which, + though they grew luxuriantly and flowered, were quite sterile; but after + beating one with a stick until a few branches alone were left, these at + once yielded good seed. The sugar-cane, which grows vigorously and + produces a large supply of succulent stems, never, according to various + observers, bears seed in the West Indies, Malaga, India, Cochin China, or + the Malay Archipelago.<a name="NtA_425" + href="#Nt_425"><sup>[425]</sup></a> Plants which produce a large number + of tubers are apt to be sterile, as occurs, to a certain extent, with the + common potato; and Mr. Fortune informs me that the sweet potato + (<i>Convolvulus batatas</i>) in China never, as far as he has seen, + yields seed. Dr. Royle remarks<a name="NtA_426" + href="#Nt_426"><sup>[426]</sup></a> that in India the <i>Agave + vivipara</i>, when grown in rich soil, invariably produces bulbs, but no + seeds; whilst a poor soil and dry climate leads to an opposite result. In + China, according to Mr. Fortune, an extraordinary number of little bulbs + are developed in the axils of the leaves of the yam, and this plant does + not bear seed. Whether in these cases, as in those of double flowers and + seedless fruit, sexual sterility from changed conditions of life is the + primary cause which leads to the excessive development of the organs of + vegetation, is doubtful; though some evidence might be advanced in favour + of this view. It is perhaps a more probable view that plants which + propagate themselves largely by one method, namely by buds, have not + sufficient vital power or organised matter for the other method of sexual + generation.</p> + + <p>Several distinguished botanists and good practical judges believe that + long-continued propagation by cuttings, runners, tubers, bulbs, &c., + independently of any excessive development of these parts, is the cause + of many plants failing to produce flowers and of others failing to + produce fertile flowers,—it is as if they had lost the habit of + sexual generation.<a name="NtA_427" href="#Nt_427"><sup>[427]</sup></a> + That many plants when thus propagated are sterile there can be no doubt, + but whether the long continuance of this form of propagation is the + actual cause of their sterility, I will not venture, from the want of + sufficient evidence, to express an opinion.</p> + + <p>That plants may be propagated for long periods by buds, without the + aid of sexual generation, we may safely infer from this being the case + with many plants which must have long survived in a state of nature. As I + have had occasion before to allude to this subject, I will here give such + cases as I have collected. Many alpine plants ascend mountains beyond the + height at which they can produce seed.<a name="NtA_428" + href="#Nt_428"><sup>[428]</sup></a> Certain species of <!-- Page 170 + --><span class="pagenum"><a name="page170"></a>{170}</span>Poa and + Festuca, when growing on mountain-pastures, propagate themselves, as I + hear from Mr. Bentham, almost exclusively by bulblets. Kalm gives a more + curious instance<a name="NtA_429" href="#Nt_429"><sup>[429]</sup></a> of + several American trees, which grow so plentifully in marshes or in thick + woods, that they are certainly well adapted for these stations, yet + scarcely ever produce seeds; but when accidentally growing on the outside + of the marsh or wood, are loaded with seed. The common ivy is found in + Northern Sweden and Russia, but flowers and fruits only in the southern + provinces. The <i>Acorus calamus</i> extends over a large portion of the + globe, but so rarely perfects its fruit that this has been seen but by + few botanists.<a name="NtA_430" href="#Nt_430"><sup>[430]</sup></a> The + <i>Hypericum calycinum</i>, which propagates itself so freely in our + shrubberies by rhizomas and is naturalised in Ireland, blossoms + profusely, but sets no seed; nor did it set any when fertilised in my + garden by pollen from plants growing at a distance. The <i>Lysimachia + nummularia</i>, which is furnished with long runners, so seldom produces + seed-capsules, that Prof. Decaisne,<a name="NtA_431" + href="#Nt_431"><sup>[431]</sup></a> who has especially attended to this + plant, has never seen it in fruit. The <i>Carex rigida</i> often fails to + perfect its seed in Scotland, Lapland, Greenland, Germany, and New + Hampshire in the United States.<a name="NtA_432" + href="#Nt_432"><sup>[432]</sup></a> The periwinkle (<i>Vinca minor</i>), + which spreads largely by runners, is said scarcely ever to produce fruit + in England;<a name="NtA_433" href="#Nt_433"><sup>[433]</sup></a> but this + plant requires insect-aid for its fertilisation, and the proper insects + may be absent or rare. The <i>Jussiæa grandiflora</i> has become + naturalised in Southern France, and has spread by its rhizomas so + extensively as to impede the navigation of the waters, but never produces + fertile seed.<a name="NtA_434" href="#Nt_434"><sup>[434]</sup></a> The + horse-radish (<i>Cochlearia armoracia</i>) spreads pertinaciously and is + naturalised in various parts of Europe; though it bears flowers, these + rarely produce capsules: Professor Caspary also informs me that he has + watched this plant since 1851, but has never seen its fruit; nor is this + surprising, as he finds scarcely a grain of good pollen. The common + little <i>Ranunculus ficaria</i> rarely, and some say never, bears seed + in England, France, or Switzerland; but in 1863 I observed seeds on + several plants growing near my house. According to M. Chatin, there are + two forms of this Ranunculus; and it is the bulbiferous form which does + not yield seed from producing no pollen.<a name="NtA_435" + href="#Nt_435"><sup>[435]</sup></a> Other cases <!-- Page 171 --><span + class="pagenum"><a name="page171"></a>{171}</span>analogous with the + foregoing could be given; for instance, some kinds of mosses and lichens + have never been seen to fructify in France.</p> + + <p>Some of these endemic and naturalised plants are probably rendered + sterile from excessive multiplication by buds, and their consequent + incapacity to produce and nourish seed. But the sterility of others more + probably depends on the peculiar conditions under which they live, as in + the case of the ivy in the northern parts of Europe, and of the trees in + the swamps of the United States; yet these plants must be in some + respects eminently well adapted for the stations which they occupy, for + they hold their places against a host of competitors.</p> + +</blockquote> + + <p>Finally, when we reflect on the sterility which accompanies the + doubling of flowers,—the excessive development of fruit,—and + a great increase in the organs of vegetation, we must bear in mind that + the whole effect has seldom been caused at once. An incipient tendency is + observed, and continued selection completes the work, as is known to be + the case with our double flowers and best fruits. The view which seems + the most probable, and which connects together all the foregoing facts + and brings them within our present subject, is, that changed and + unnatural conditions of life first give a tendency to sterility; and in + consequence of this, the organs of reproduction being no longer able + fully to perform their proper functions, a supply of organised matter, + not required for the development of the seed, flows either into these + same organs and renders them foliaceous, or into the fruit, stems, + tubers, &c., increasing their size and succulency. But I am far from + wishing to deny that there exists, independently of any incipient + sterility, an antagonism between the two forms of reproduction, namely, + by seed and by buds, when either is carried to an extreme degree. That + incipient sterility plays an important part in the doubling of flowers, + and in the other cases just specified, I infer chiefly from the following + facts. When fertility is lost from a wholly different cause, namely, from + hybridism, there is a strong tendency, as Gärtner<a name="NtA_436" + href="#Nt_436"><sup>[436]</sup></a> affirms, for flowers to become + double, and this tendency is inherited. Moreover it is notorious that + with hybrids the male organs become sterile before the female organs, and + with double flowers the stamens first become <!-- Page 172 --><span + class="pagenum"><a name="page172"></a>{172}</span>foliaceous. This latter + fact is well shown by the male flowers of diœcious plants, which, + according to Gallesio,<a name="NtA_437" + href="#Nt_437"><sup>[437]</sup></a> first become double. Again, Gärtner<a + name="NtA_438" href="#Nt_438"><sup>[438]</sup></a> often insists that the + flowers of even utterly sterile hybrids, which do not produce any seed, + generally yield perfect capsules or fruit,—a fact which has + likewise been repeatedly observed by Naudin with the Cucurbitaceæ; so + that the production of fruit by plants rendered sterile through any other + and distinct cause is intelligible. Kölreuter has also expressed his + unbounded astonishment at the size and development of the tubers in + certain hybrids; and all experimentalists<a name="NtA_439" + href="#Nt_439"><sup>[439]</sup></a> have remarked on the strong tendency + in hybrids to increase by roots, runners, and suckers. Seeing that hybrid + plants, which from their nature are more or less sterile, thus tend to + produce double flowers; that they have the parts including the seed, that + is the fruit, perfectly developed, even when containing no seed; that + they sometimes yield gigantic roots; that they almost invariably tend to + increase largely by suckers and other such means;—seeing this, and + knowing, from the many facts given in the earlier parts of this chapter, + that almost all organic beings when exposed to unnatural conditions tend + to become more or less sterile, it seems much the most probable view that + with cultivated plants sterility is the exciting cause, and double + flowers, rich seedless fruit, and in some cases largely-developed organs + of vegetation, &c., are the indirect results—these results + having been in most cases largely increased through continued selection + by man.</p> + +<hr class="full" /> + +<p><!-- Page 173 --><span class="pagenum"><a name="page173"></a>{173}</span></p> + +<h3>CHAPTER XIX.</h3> + +<p class="cenhead">SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS +ON HYBRIDISM.</p> + +<blockquote class="b1n"> + + <p><span class="scac">ON THE EFFECTS OF CROSSING</span>—<span + class="scac">THE INFLUENCE OF DOMESTICATION ON + FERTILITY</span>—<span class="scac">CLOSE + INTERBREEDING</span>—<span class="scac">GOOD AND EVIL RESULTS FROM + CHANGED CONDITIONS OF LIFE</span>—<span class="scac">VARIETIES WHEN + CROSSED NOT INVARIABLY FERTILE</span>—<span class="scac">ON THE + DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND + VARIETIES</span>—<span class="scac">CONCLUSIONS WITH RESPECT TO + HYBRIDISM</span>—<span class="scac">LIGHT THROWN ON HYBRIDISM BY + THE ILLEGITIMATE PROGENY OF DIMORPHIC AND TRIMORPHIC + PLANTS</span>—<span class="scac">STERILITY OF CROSSED SPECIES DUE + TO DIFFERENCES CONFINED TO THE REPRODUCTIVE SYSTEM</span>—<span + class="scac">NOT ACCUMULATED THROUGH NATURAL SELECTION</span>—<span + class="scac">REASONS WHY DOMESTIC VARIETIES ARE NOT MUTUALLY + STERILE</span>—<span class="scac">TOO MUCH STRESS HAS BEEN LAID ON + THE DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED + VARIETIES</span>—<span class="scac">CONCLUSION.</span></p> + +</blockquote> + + <p>It was shown in the fifteenth chapter that when individuals of the + same variety, or even of a distinct variety, are allowed freely to + intercross, uniformity of character is ultimately acquired. Some few + characters, however, are incapable of fusion, but these are unimportant, + as they are almost always of a semi-monstrous nature, and have suddenly + appeared. Hence, to preserve our domesticated breeds true, or to improve + them by methodical selection, it is obviously necessary that they should + be kept separate. Nevertheless, through unconscious selection, a whole + body of individuals may be slowly modified, as we shall see in a future + chapter, without separating them into distinct lots. Domestic races have + often been intentionally modified by one or two crosses, made with some + allied race, and occasionally even by repeated crosses with very distinct + races; but in almost all such cases, long-continued and careful selection + has been absolutely necessary, owing to the excessive variability of the + crossed offspring, due to the principle of reversion. In a few instances, + however, mongrels have retained a uniform character from their first + production.</p> + + <p>When two varieties are allowed to cross freely, and one is <!-- Page + 174 --><span class="pagenum"><a name="page174"></a>{174}</span>much more + numerous than the other, the former will ultimately absorb the latter. + Should both varieties exist in nearly equal numbers, it is probable that + a considerable period would elapse before the acquirement of a uniform + character; and the character ultimately acquired would largely depend on + prepotency of transmission, and on the conditions of life; for the nature + of these conditions would generally favour one variety more than another, + so that a kind of natural selection would come into play. Unless the + crossed offspring were slaughtered by man without the least + discrimination, some degree of unmethodical selection would likewise come + into action. From these several considerations we may infer, that when + two or more closely allied species first came into the possession of the + same tribe, their crossing will not have influenced, in so great a degree + as has often been supposed, the character of the offspring in future + times; although in some cases it probably has had a considerable + effect.</p> + + <p>Domestication, as a general rule, increases the prolificness of + animals and plants. It eliminates the tendency to sterility which is + common to species when first taken from a state of nature and crossed. On + this latter head we have no direct evidence; but as our races of dogs, + cattle, pigs, &c., are almost certainly descended from aboriginally + distinct stocks, and as these races are now fully fertile together, or at + least incomparably more fertile than most species when crossed, we may + with much confidence accept this conclusion.</p> + + <p>Abundant evidence has been given that crossing adds to the size, + vigour, and fertility of the offspring. This holds good when there has + been no previous close interbreeding. It applies to the individuals of + the same variety but belonging to different families, to distinct + varieties, sub-species, and partially even to species. In the latter + case, though size is often gained, fertility is lost; but the increased + size, vigour, and hardiness of many hybrids cannot be accounted for + solely on the principle of compensation from the inaction of the + reproductive system. Certain plants, both of pure and hybrid origin, + though perfectly healthy, have become self-impotent, apparently from the + unnatural conditions to which they have been exposed; and such plants, as + well as others in their normal state, can be stimulated to <!-- Page 175 + --><span class="pagenum"><a name="page175"></a>{175}</span>fertility only + by crossing them with other individuals of the same species or even of a + distinct species.</p> + + <p>On the other hand, long-continued close interbreeding between the + nearest relations diminishes the constitutional vigour, size, and + fertility of the offspring; and occasionally leads to malformations, but + not necessarily to general deterioration of form or structure. This + failure of fertility shows that the evil results of interbreeding are + independent of the augmentation of morbid tendencies common to both + parents, though this augmentation no doubt is often highly injurious. Our + belief that evil follows from close interbreeding rests to a large extent + on the experience of practical breeders, especially of those who have + reared many animals of the kinds which can be propagated quickly; but it + likewise rests on several carefully recorded experiments. With some + animals close interbreeding may be carried on for a long period with + impunity by the selection of the most vigorous and healthy individuals; + but sooner or later evil follows. The evil, however, comes on so slowly + and gradually that it easily escapes observation, but can be recognised + by the almost instantaneous manner in which size, constitutional vigour, + and fertility are regained when animals that have long been interbred are + crossed with a distinct family.</p> + + <p>These two great classes of facts, namely, the good derived from + crossing, and the evil from close interbreeding, with the consideration + of the innumerable adaptations throughout nature for compelling, or + favouring, or at least permitting, the occasional union of distinct + individuals, taken together, lead to the conclusion that it is a law of + nature that organic beings shall not fertilise themselves for perpetuity. + This law was first plainly hinted at in 1799, with respect to plants, by + Andrew Knight,<a name="NtA_440" href="#Nt_440"><sup>[440]</sup></a> and, + not long afterwards, that sagacious observer Kölreuter, after showing how + well the Malvaceæ are adapted for <!-- Page 176 --><span + class="pagenum"><a name="page176"></a>{176}</span>crossing, asks, "an id + aliquid in recessu habeat, quod hujuscemodi flores nunquam proprio suo + pulvere, sed semper eo aliarum suæ speciei impregnentur, merito quæritur? + Certe natura nil facit frustra." Although we may demur to Kölreuter's + saying that nature does nothing in vain, seeing how many organic beings + retain rudimentary and useless organs, yet undoubtedly the argument from + the innumerable contrivances, which favour the crossing of distinct + individuals of the same species, is of the greatest weight. The most + important result of this law is that it leads to uniformity of character + in the individuals of the same species. In the case of certain + hermaphrodites, which probably intercross only at long intervals of time, + and with unisexual animals inhabiting somewhat separated localities, + which can only occasionally come into contact and pair, the greater + vigour and fertility of the crossed offspring will ultimately prevail in + giving uniformity of character to the individuals of the same species. + But when we go beyond the limits of the same species, free intercrossing + is barred by the law of sterility.</p> + + <p>In searching for facts which might throw light on the cause of the + good effects from crossing, and of the evil effects from close + interbreeding, we have seen that, on the one hand, it is a widely + prevalent and ancient belief that animals and plants profit from slight + changes in their condition of life; and it would appear that the germ, in + a somewhat analogous manner, is more effectually stimulated by the male + element, when taken from a distinct individual, and therefore slightly + modified in nature, than when taken from a male having the same identical + constitution. On the other hand, numerous facts have been given, showing + that when animals are first subjected to captivity, even in their native + land, and although allowed much liberty, their reproductive functions are + often greatly impaired or quite annulled. Some groups of animals are more + affected than others, but with apparently capricious exceptions in every + group. Some animals never or rarely couple: some couple freely, but never + or rarely conceive. The secondary male characters, the maternal functions + and instincts, are occasionally affected. With plants, when first + subjected to cultivation, analogous facts have been observed. We probably + owe our double flowers, rich seedless <!-- Page 177 --><span + class="pagenum"><a name="page177"></a>{177}</span>fruits, and in some + cases greatly developed tubers, &c., to incipient sterility of the + above nature combined with a copious supply of nutriment. Animals which + have long been domesticated, and plants which have long been cultivated, + can generally withstand with unimpaired fertility great changes in their + conditions of life; though both are sometimes slightly affected. With + animals the somewhat rare capacity of breeding freely under confinement + has mainly determined, together with their utility, the kinds which have + been domesticated.</p> + + <p>We can in no case precisely say what is the cause of the diminished + fertility of an animal when first captured, or of a plant when first + cultivated; we can only infer that it is caused by a change of some kind + in the natural conditions of life. The remarkable susceptibility of the + reproductive system to such changes,—a susceptibility not common to + any other organ,—apparently has an important bearing on + Variability, as we shall see in a future chapter.</p> + + <p>It is impossible not to be struck with the double parallelism between + the two classes of facts just alluded to. On the one hand, slight changes + in the conditions of life, and crosses between slightly modified forms or + varieties, are beneficial as far as prolificness and constitutional + vigour are concerned. On the other hand, changes in the conditions + greater in degree, or of a different nature, and crosses between forms + which have been slowly and greatly modified by natural means,—in + other words, between species,—are highly injurious, as far as the + reproductive system is concerned, and in some few instances as far as + constitutional vigour is concerned. Can this parallelism be accidental? + Does it not rather indicate some real bond of connection? As a fire goes + out unless it be stirred up, so the vital forces are always tending, + according to Mr. Herbert Spencer, to a state of equilibrium, unless + disturbed and renovated through the action of other forces.</p> + + <p>In some few cases varieties tend to keep distinct, by breeding at + different periods, by great differences in size, or by sexual + preference,—in this latter respect more especially resembling + species in a state of nature. But the actual crossing of varieties, far + from diminishing, generally adds to the fertility of both the first union + and the mongrel offspring. Whether all <!-- Page 178 --><span + class="pagenum"><a name="page178"></a>{178}</span>the most widely + distinct domestic varieties are invariably quite fertile when crossed, we + do not positively know; much time and trouble would be requisite for the + necessary experiments, and many difficulties occur, such as the descent + of the various races from aboriginally distinct species, and the doubts + whether certain forms ought to be ranked as species or varieties. + Nevertheless, the wide experience of practical breeders proves that the + great majority of varieties, even if some should hereafter prove not to + be indefinitely fertile <i>inter se</i>, are far more fertile when + crossed, than the vast majority of closely allied natural species. A few + remarkable cases have, however, been given on the authority of excellent + observers, showing that with plants certain forms, which undoubtedly must + be ranked as varieties, yield fewer seeds when crossed than is natural to + the parent-species. Other varieties have had their reproductive powers so + far modified that they are either more or less fertile than are their + parents, when crossed with a distinct species.</p> + + <p>Nevertheless, the fact remains indisputable that domesticated + varieties of animals and of plants, which differ greatly from each other + in structure, but which are certainly descended from the same aboriginal + species, such as the races of the fowl, pigeon, many vegetables, and a + host of other productions, are extremely fertile when crossed; and this + seems to make a broad and impassable barrier between domestic varieties + and natural species. But, as I will now attempt to show, the distinction + is not so great and overwhelmingly important as it at first appears.</p> + +<p class="cenhead"><i>On the Difference in Fertility between Varieties and Species when +crossed.</i></p> + + <p>This work is not the proper place for fully treating the subject of + hybridism, and I have already given in my 'Origin of Species' a + moderately full abstract. I will here merely enumerate the general + conclusions which may be relied on, and which bear on our present + point.</p> + + <p><i>Firstly</i>, the laws governing the production of hybrids are + identical, or nearly identical, in the animal and vegetable kingdoms.</p> + + <p><i>Secondly</i>, the sterility of distinct species when first united, + <!-- Page 179 --><span class="pagenum"><a + name="page179"></a>{179}</span>and that of their hybrid offspring, + graduates, by an almost infinite number of steps, from zero, when the + ovule is never impregnated and a seed-capsule is never formed, up to + complete fertility. We can only escape the conclusion that some species + are fully fertile when crossed, by determining to designate as varieties + all the forms which are quite fertile. This high degree of fertility is, + however, rare. Nevertheless plants, which have been exposed to unnatural + conditions, sometimes become modified in so peculiar a manner, that they + are much more fertile when crossed by a distinct species than when + fertilised by their own pollen. Success in effecting a first union + between two species, and the fertility of their hybrids, depends in an + eminent degree on the conditions of life being favourable. The innate + sterility of hybrids of the same parentage and raised from the same + seed-capsule often differs much in degree.</p> + + <p><i>Thirdly</i>, the degree of sterility of a first cross between two + species does not always run strictly parallel with that of their hybrid + offspring. Many cases are known of species which can be crossed with + ease, but yield hybrids excessively sterile; and conversely some which + can be crossed with great difficulty, but produce fairly fertile hybrids. + This is an inexplicable fact, on the view that species have been + specially endowed with mutual sterility in order to keep them + distinct.</p> + + <p><i>Fourthly</i>, the degree of sterility often differs greatly in two + species when reciprocally crossed; for the first will readily fertilise + the second; but the latter is incapable, after hundreds of trials, of + fertilising the former. Hybrids produced from reciprocal crosses between + the same two species, likewise sometimes differ in their degree of + sterility. These cases also are utterly inexplicable on the view of + sterility being a special endowment.</p> + + <p><i>Fifthly</i>, the degree of sterility of first crosses and of + hybrids runs, to a certain extent, parallel with the general or + systematic affinity of the forms which are united. For species belonging + to distinct genera can rarely, and those belonging to distinct families + can never, be crossed. The parallelism, however, is far from complete; + for a multitude of closely allied species will not unite, or unite with + extreme difficulty, whilst other species, widely different from each + other, can be crossed with perfect facility. Nor does the difficulty + depend on ordinary <!-- Page 180 --><span class="pagenum"><a + name="page180"></a>{180}</span>constitutional differences, for annual and + perennial plants, deciduous and evergreen trees, plants flowering at + different seasons, inhabiting different stations, and naturally living + under the most opposite climates, can often be crossed with ease. The + difficulty or facility apparently depends exclusively on the sexual + constitution of the species which are crossed; or on their sexual + elective affinity, <i>i. e.</i> <i>Wahlverwandtschaft</i> of Gärtner. As + species rarely or never become modified in one character, without being + at the same time modified in many, and as systematic affinity includes + all visible resemblances and dissimilarities, any difference in sexual + constitution between two species would naturally stand in more or less + close relation with their systematic position.</p> + + <p><i>Sixthly</i>, the sterility of species when first crossed, and that + of hybrids, may possibly depend to a certain extent on distinct causes. + With pure species the reproductive organs are in a perfect condition, + whilst with hybrids they are often plainly deteriorated. A hybrid embryo + which partakes of the constitution of its father and mother is exposed to + unnatural conditions, as long as it is nourished within the womb, or egg, + or seed of the mother-form; and as we know that unnatural conditions + often induce sterility, the reproductive organs of the hybrid might at + this early age be permanently affected. But this cause has no bearing on + the infertility of first unions. The diminished number of the offspring + from first unions may often result, as is certainly sometimes the case, + from the premature death of most of the hybrid embryos. But we shall + immediately see that a law of an unknown nature apparently exists, which + causes the offspring from unions, which are infertile, to be themselves + more or less infertile; and this at present is all that can be said.</p> + + <p><i>Seventhly</i>, hybrids and mongrels present, with the one great + exception of fertility, the most striking accordance in all other + respects; namely, in the laws of their resemblance to their two parents, + in their tendency to reversion, in their variability, and in being + absorbed through repeated crosses by either parent-form.</p> + + <p>Since arriving at the foregoing conclusions, condensed from my former + work, I have been led to investigate a subject which throws considerable + light on hybridism, namely, the fertility of <!-- Page 181 --><span + class="pagenum"><a name="page181"></a>{181}</span>reciprocally dimorphic + and trimorphic plants, when illegitimately united. I have had occasion + several times to allude to these plants, and I may here give a brief + abstract<a name="NtA_441" href="#Nt_441"><sup>[441]</sup></a> of my + observations. Several plants belonging to distinct orders present two + forms, which exist in about equal numbers, and which differ in no respect + except in their reproductive organs; one form having a long pistil with + short stamens, the other a short pistil with long stamens; both with + differently sized pollen-grains. With trimorphic plants there are three + forms likewise differing in the lengths of their pistils and stamens, in + the size and colour of the pollen-grains, and in some other respects; and + as in each of the three forms there are two sets of stamens, there are + altogether six sets of stamens and three kinds of pistils. These organs + are so proportioned in length to each other that, in any two of the + forms, half the stamens in each stand on a level with the stigma of the + third form. Now I have shown, and the result has been confirmed by other + observers, that, in order to obtain full fertility with these plants, it + is necessary that the stigma of the one form should be fertilised by + pollen taken from the stamens of corresponding height in the other form. + So that with dimorphic species two unions, which may be called + legitimate, are fully fertile, and two, which may be called illegitimate, + are more or less infertile. With trimorphic species six unions are + legitimate or fully fertile, and twelve are illegitimate or more or less + infertile.</p> + + <p>The infertility which may be observed in various dimorphic and + trimorphic plants, when they are illegitimately fertilised, that is, by + pollen taken from stamens not corresponding in height with the pistil, + differs much in degree, up to absolute and utter sterility; just in the + same manner as occurs in crossing distinct species. As the degree of + sterility in the latter case depends in an eminent degree on the + conditions of life being more or less favourable, so I have found it with + illegitimate unions. It is well known that if pollen of a distinct + species be placed on the stigma of a flower, and its own pollen be + afterwards, even <!-- Page 182 --><span class="pagenum"><a + name="page182"></a>{182}</span>after a considerable interval of time, + placed on the same stigma, its action is so strongly prepotent that it + generally annihilates the effect of the foreign pollen; so it is with the + pollen of the several forms of the same species, for legitimate pollen is + strongly prepotent over illegitimate pollen, when both are placed on the + same stigma. I ascertained this by fertilising several flowers, first + illegitimately, and twenty-four hours afterwards legitimately, with + pollen taken from a peculiarly coloured variety, and all the seedlings + were similarly coloured; this shows that the legitimate pollen, though + applied twenty-four hours subsequently, had wholly destroyed or prevented + the action of the previously applied illegitimate pollen. Again, as, in + making reciprocal crosses between the same two species, there is + occasionally a great difference in the result, so something analogous + occurs with dimorphic plants; for a short-styled cowslip (<i>P. + veris</i>) yields more seed when fertilised by the long-styled form, and + less seed when fertilised by its own form, compared with a long-styled + cowslip when fertilised in the two corresponding methods.</p> + + <p>In all these respects the forms of the same undoubted species, when + illegitimately united, behave in exactly the same manner as do two + distinct species when crossed. This led me carefully to observe during + four years many seedlings, raised from several illegitimate unions. The + chief result is that these illegitimate plants, as they may be called, + are not fully fertile. It is possible to raise from dimorphic species, + both long-styled and short-styled illegitimate plants, and from + trimorphic plants all three illegitimate forms. These can then be + properly united in a legitimate manner. When this is done, there is no + apparent reason why they should not yield as many seeds as did their + parents when legitimately fertilised. But such is not the case; they are + all infertile, but in various degrees; some being so utterly and + incurably sterile that they did not yield during four seasons a single + seed or even seed-capsule. These illegitimate plants, which are so + sterile, although united with each other in a legitimate manner, may be + strictly compared with hybrids when crossed <i>inter se</i>, and it is + well known how sterile these latter generally are. When, on the other + hand, a hybrid is crossed with either pure parent-species, the sterility + is usually much lessened: and so it is when an illegitimate plant is + fertilised by <!-- Page 183 --><span class="pagenum"><a + name="page183"></a>{183}</span>a legitimate plant. In the same manner as + the sterility of hybrids does not always run parallel with the difficulty + of making the first cross between the two parent species, so the + sterility of certain illegitimate plants was unusually great, whilst the + sterility of the union from which they were derived was by no means + great. With hybrids raised from the same seed-capsule the degree of + sterility is innately variable, so it is in a marked manner with + illegitimate plants. Lastly, many hybrids are profuse and persistent + flowerers, whilst other and more sterile hybrids produce few flowers, and + are weak, miserable dwarfs; exactly similar cases occur with the + illegitimate offspring of various dimorphic and trimorphic plants.</p> + + <p>Altogether there is the closest identity in character and behaviour + between illegitimate plants and hybrids. It is hardly an exaggeration to + maintain that the former are hybrids, but produced within the limits of + the same species by the improper union of certain forms, whilst ordinary + hybrids are produced from an improper union between so-called distinct + species. We have already seen that there is the closest similarity in all + respects between first illegitimate unions, and first crosses between + distinct species. This will perhaps be made more fully apparent by an + illustration: we may suppose that a botanist found two well-marked + varieties (and such occur) of the long-styled form of the trimorphic + <i>Lythrum salicaria</i>, and that he determined to try by crossing + whether they were specifically distinct. He would find that they yielded + only about one-fifth of the proper number of seed, and that they behaved + in all the other above-specified respects as if they had been two + distinct species. But to make the case sure, he would raise plants from + his supposed hybridised seed, and he would find that the seedlings were + miserably dwarfed and utterly sterile, and that they behaved in all other + respects like ordinary hybrids. He might then maintain that he had + actually proved, in accordance with the common view, that his two + varieties were as good and as distinct species as any in the world; but + he would be completely mistaken.</p> + + <p>The facts now given on dimorphic and trimorphic plants are important, + because they show us, firstly, that the physiological <!-- Page 184 + --><span class="pagenum"><a name="page184"></a>{184}</span>test of + lessened fertility, both in first crosses and in hybrids, is no safe + criterion of specific distinction; secondly, because we may conclude that + there must be some unknown law or bond connecting the infertility of + illegitimate unions with that of their illegitimate offspring, and we are + thus led to extend this view to first crosses and hybrids; thirdly, + because we find, and this seems to me of especial importance, that with + trimorphic plants three forms of the same species exist, which when + crossed in a particular manner are infertile, and yet these forms differ + in no respect from each other, except in their reproductive + organs,—as in the relative length of the stamens and pistils, in + the size, form, and colour of the pollen-grains, in the structure of the + stigma, and in, the number and size of the seeds. With these differences + and no others, either in organisation or constitution, we find that the + illegitimate unions and the illegitimate progeny of these three forms are + more or less sterile, and closely resemble in a whole series of relations + the first unions and hybrid offspring of distinct species. From this we + may infer that the sterility of species when crossed and of their hybrid + progeny is likewise in all probability exclusively due to differences + confined to the reproductive system. We have indeed been brought to a + similar conclusion by observing that the sterility of crossed species + does not strictly coincide with their systematic affinity, that is, with + the sum of their external resemblances; nor does it coincide with their + similarity in general constitution. But we are more especially led to + this same conclusion by considering reciprocal crosses, in which the male + of one species cannot be united, or can be united with extreme + difficulty, with the female of a second species, whilst the converse + cross can be effected with perfect facility; for this difference in the + facility of making reciprocal crosses, and in the fertility of their + offspring, must be attributed either to the male or female element in the + first species having been differentiated with reference to the sexual + element of the second species in a higher degree than in the converse + case. In so complex a subject as Hybridism it is of considerable + importance thus to arrive at a definitive conclusion, namely, that the + sterility which almost invariably follows the union of distinct <!-- Page + 185 --><span class="pagenum"><a name="page185"></a>{185}</span>species + depends exclusively on differences in their sexual constitution.</p> + +<hr class="short" /> + + <p>On the principle which makes it necessary for man, whilst he is + selecting and improving his domestic varieties, to keep them separate, it + would clearly be advantageous to varieties in a state of nature, that is + to incipient species, if they could be kept from blending, either through + sexual aversion, or by becoming mutually sterile. Hence it at one time + appeared to me probable, as it has to others, that this sterility might + have been acquired through natural selection. On this view we must + suppose that a shade of lessened fertility first spontaneously appeared, + like any other modification, in certain individuals of a species when + crossed with other individuals of the same species; and that successive + slight degrees of infertility, from being advantageous, were slowly + accumulated. This appears all the more probable, if we admit that the + structural differences between the forms of dimorphic and trimorphic + plants, as the length and curvature of the pistil, &c., have been + co-adapted through natural selection; for if this be admitted, we can + hardly avoid extending the same conclusion to their mutual infertility. + Sterility moreover has been acquired through natural selection for other + and widely different purposes, as with neuter insects in reference to + their social economy. In the case of plants, the flowers on the + circumference of the truss in the guelder-rose (<i>Viburnum opulus</i>) + and those on the summit of the spike in the feather-hyacinth (<i>Muscari + comosum</i>) have been rendered conspicuous, and apparently in + consequence sterile, in order that insects might easily discover and + visit the other flowers. But when we endeavour to apply the principle of + natural selection to the acquirement by distinct species of mutual + sterility, we meet with great difficulties. In the first place, it may be + remarked that separate regions are often inhabited by groups of species + or by single species, which when brought together and crossed are found + to be more or less sterile; now it could clearly have been of no + advantage to such separated species to have been rendered mutually + sterile, and consequently this could not have been effected through + natural selection; but it may perhaps be argued, that, if a species were + rendered sterile with <!-- Page 186 --><span class="pagenum"><a + name="page186"></a>{186}</span>some one compatriot, sterility with other + species would follow as a necessary consequence. In the second place, it + is as much opposed to the theory of natural selection, as to the theory + of special creation, that in reciprocal crosses the male element of one + form should have been rendered utterly impotent on a second form, whilst + at the same time the male element of this second form is enabled freely + to fertilise the first form; for this peculiar state of the reproductive + system could not possibly be advantageous to either species.</p> + + <p>In considering the probability of natural selection having come into + action in rendering species mutually sterile, one great difficulty will + be found to lie in the existence of many graduated steps from slightly + lessened fertility to absolute sterility. It may be admitted, on the + principle above explained, that it would profit an incipient species if + it were rendered in some slight degree sterile when crossed with its + parent-form or with some other variety; for thus fewer bastardised and + deteriorated offspring would be produced to commingle their blood with + the new species in process of formation. But he who will take the trouble + to reflect on the steps by which this first degree of sterility could be + increased through natural selection to that higher degree which is common + to so many species, and which is universal with species which have been + differentiated to a generic or family rank, will find the subject + extraordinarily complex. After mature reflection it seems to me that this + could not have been effected through natural selection; for it could have + been of no direct advantage to an individual animal to breed badly with + another individual of a different variety, and thus leave few offspring; + consequently such individuals could not have been preserved or selected. + Or take the case of two species which in their present state, when + crossed, produce few and sterile offspring; now, what is there which + could favour the survival of those individuals which happened to be + endowed in a slightly higher degree with mutual infertility and which + thus approached by one small step towards absolute sterility? yet an + advance of this kind, if the theory of natural selection be brought to + bear, must have incessantly occurred with many species, for a multitude + are mutually quite barren. With sterile neuter insects we have reason to + <!-- Page 187 --><span class="pagenum"><a + name="page187"></a>{187}</span>believe that modifications in their + structure have been slowly accumulated by natural selection, from an + advantage having been thus indirectly given to the community to which + they belonged over other communities of the same species; but an + individual animal, if rendered slightly sterile when crossed with some + other variety, would not thus in itself gain any advantage, or indirectly + give any advantage to its nearest relatives or to other individuals of + the same variety, leading to their preservation. I infer from these + considerations that, as far as animals are concerned, the various degrees + of lessened fertility which occur with species when crossed cannot have + been slowly accumulated by means of natural selection.</p> + + <p>With plants, it is possible that the case may be somewhat different. + With many kinds, insects constantly carry pollen from neighbouring plants + to the stigmas of each flower; and with some species this is effected by + the wind. Now, if the pollen of a variety, when deposited on the stigma + of the same variety, should become by spontaneous variation in ever so + slight a degree prepotent over the pollen of other varieties, this would + certainly be an advantage to the variety; for its own pollen would thus + obliterate the effects of the pollen of other varieties, and prevent + deterioration of character. And the more prepotent the variety's own + pollen could be rendered through natural selection, the greater the + advantage would be. We know from the researches of Gärtner that, with + species which are mutually sterile, the pollen of each is always + prepotent on its own stigma over that of the other species; but we do not + know whether this prepotency is a consequence of the mutual sterility, or + the sterility a consequence of the prepotency. If the latter view be + correct, as the prepotency became stronger through natural selection, + from being advantageous to a species in process of formation, so the + sterility consequent on prepotency would at the same time be augmented; + and the final result would be various degrees of sterility, such as + occurs with existing species. This view might be extended to animals, if + the female before each birth received several males, so that the sexual + element of the prepotent male of her own variety obliterated the effects + of the access of previous males belonging to other varieties; but we have + no reason to believe, at least <!-- Page 188 --><span class="pagenum"><a + name="page188"></a>{188}</span>with terrestrial animals, that this is the + ease; as most males and females pair for each birth, and some few for + life.</p> + + <p>On the whole we may conclude that with animals the sterility of + crossed species has not been slowly augmented through natural selection; + and as this sterility follows the same general laws in the vegetable as + in the animal kingdom, it is improbable, though apparently possible, that + with plants crossed species should have been rendered sterile by a + different process. From this consideration, and remembering that species + which have never co-existed in the same country, and which therefore + could not have received any advantage from having been rendered mutually + infertile, yet are generally sterile when crossed; and bearing in mind + that in reciprocal crosses between the same two species there is + sometimes the widest difference in their sterility, we must give up the + belief that natural selection has come into play.</p> + + <p>As species have not been rendered mutually infertile through the + accumulative action of natural selection, and as we may safely conclude, + from the previous as well as from other and more general considerations, + that they have not been endowed through an act of creation with this + quality, we must infer that it has arisen incidentally during their slow + formation in connection with other and unknown changes in their + organisation. By a quality arising incidentally, I refer to such cases as + different species of animals and plants being differently affected by + poisons to which they are not naturally exposed; and this difference in + susceptibility is clearly incidental on other and unknown differences in + their organisation. So again the capacity in different kinds of trees to + be grafted on each other, or on a third species, differs much, and is of + no advantage to these trees, but is incidental on structural or + functional differences in their woody tissues. We need not feel surprise + at sterility incidentally resulting from crosses between distinct + species,—the modified descendants of a common + progenitor,—when we bear in mind how easily the reproductive system + is affected by various causes—often by extremely slight changes in + the conditions of life, by too close interbreeding, and by other + agencies. It is well to bear in mind such cases, as that of the + <i>Passiflora alata</i>, which recovered its self-fertility from <!-- + Page 189 --><span class="pagenum"><a name="page189"></a>{189}</span>being + grafted on a distinct species—the cases of plants which normally or + abnormally are self-impotent, but can readily be fertilised by the pollen + of a distinct species—and lastly the cases of individual + domesticated animals which evince towards each other sexual + incompatibility.</p> + +<hr class="short" /> + + <p>We now at last come to the immediate point under discussion: how is it + that, with some few exceptions in the case of plants, domesticated + varieties, such as those of the dog, fowl, pigeon, several fruit-trees, + and culinary vegetables, which differ from each other in external + characters more than many species, are perfectly fertile when crossed, or + even fertile in excess, whilst closely allied species are almost + invariably in some degree sterile? We can, to a certain extent, give a + satisfactory answer to this question. Passing over the fact that the + amount of external difference between two species is no sure guide to + their degree of mutual sterility, so that similar differences in the case + of varieties would be no sure guide, we know that with species the cause + lies exclusively in differences in their sexual constitution. Now the + conditions to which domesticated animals and cultivated plants have been + subjected, have had so little tendency towards modifying the reproductive + system in a manner leading to mutual sterility, that we have good grounds + for admitting the directly opposite doctrine of Pallas, namely, that such + conditions generally eliminate this tendency; so that the domesticated + descendants of species, which in their natural state would have been in + some degree sterile when crossed, become perfectly fertile together. With + plants, so far is cultivation from giving a tendency towards mutual + sterility, that in several well-authenticated cases, already often + alluded to, certain species have been affected in a very different + manner, for they have become self-impotent, whilst still retaining the + capacity of fertilising, and being fertilised by, distinct species. If + the Pallasian doctrine of the elimination of sterility through + long-continued domestication be admitted, and it can hardly be rejected, + it becomes in the highest degree improbable that similar circumstances + should commonly both induce and eliminate the same tendency; though in + certain cases, with species having a peculiar constitution, sterility + might occasionally be thus <!-- Page 190 --><span class="pagenum"><a + name="page190"></a>{190}</span>induced. Thus, as I believe, we can + understand why with domesticated animals varieties have not been produced + which are mutually sterile; and why with plants only a few such cases + have been observed, namely, by Gärtner, with certain varieties of maize + and verbascum, by other experimentalists with varieties of the gourd and + melon, and by Kölreuter with one kind of tobacco.</p> + + <p>With respect to varieties which have originated in a state of nature, + it is almost hopeless to expect to prove by direct evidence that they + have been rendered mutually sterile; for if even a trace of sterility + could be detected, such varieties would at once be raised by almost every + naturalist to the rank of distinct species. If, for instance, Gärtner's + statement were fully confirmed, that the blue and red-flowered forms of + the pimpernel (<i>Anagallis arvensis</i>) are sterile when crossed, I + presume that all the botanists who now maintain on various grounds that + these two forms are merely fleeting varieties, would at once admit that + they were specifically distinct.</p> + + <p>The real difficulty in our present subject is not, as it appears to + me, why domestic varieties have not become mutually infertile when + crossed, but why this has so generally occurred with natural varieties as + soon as they have been modified in a sufficient and permanent degree to + take rank as species. We are far from precisely knowing the cause; nor is + this surprising, seeing how profoundly ignorant we are in regard to the + normal and abnormal action of the reproductive system. But we can see + that species, owing to their struggle for life with numerous competitors, + must have been exposed to more uniform conditions during long periods of + time, than have been domestic varieties; and this may well make a wide + difference in the result. For we know how commonly wild animals and + plants, when taken from their natural conditions and subjected to + captivity, are rendered sterile; and the reproductive functions of + organic beings which have always lived and been slowly modified under + natural conditions would probably in like manner be eminently sensitive + to the influence of an unnatural cross. Domesticated productions, on the + other hand, which, as shown by the mere fact of their domestication, were + not originally highly sensitive to changes in their conditions of life, + and which can now generally resist <!-- Page 191 --><span + class="pagenum"><a name="page191"></a>{191}</span>with undiminished + fertility repeated changes of conditions, might be expected to produce + varieties, which would be little liable to have their reproductive powers + injuriously affected by the act of crossing with other varieties which + had originated in a like manner.</p> + + <p>Certain naturalists have recently laid too great stress, as it appears + to me, on the difference in fertility between varieties and species when + crossed. Some allied species of trees cannot be grafted on each + other,—all varieties can be so grafted. Some allied animals are + affected in a very different manner by the same poison, but with + varieties no such case until recently was known, but now it has been + proved that immunity from certain poisons stands in some cases in + correlation with the colour of the hair. The period of gestation + generally differs much with distinct species, but with varieties until + lately no such difference had been observed. The time required for the + germination of seeds differs in an analogous manner, and I am not aware + that any difference in this respect has as yet been detected with + varieties. Here we have various physiological differences, and no doubt + others could be added, between one species and another of the same genus, + which do not occur, or occur with extreme rarity, in the case of + varieties; and these differences are apparently wholly or in chief part + incidental on other constitutional differences, just in the same manner + as the sterility of crossed species is incidental on differences confined + to the sexual system. Why, then, should these latter differences, however + serviceable they may indirectly be in keeping the inhabitants of the same + country distinct, be thought of such paramount importance, in comparison + with other incidental and functional differences? No sufficient answer to + this question can be given. Hence the fact that the most distinct + domestic varieties are, with rare exceptions, perfectly fertile when + crossed, and produce fertile offspring, whilst closely allied species + are, with rare exceptions, more or less sterile, is not nearly so + formidable an objection as it appears at first to the theory of the + common descent of allied species.</p> + +<hr class="full" /> + +<p><!-- Page 192 --><span class="pagenum"><a name="page192"></a>{192}</span></p> + +<h3>CHAPTER XX.</h3> + +<p class="cenhead">SELECTION BY MAN.</p> + +<blockquote class="b1n"> + + <p><span class="scac">SELECTION A DIFFICULT ART</span>—<span + class="scac">METHODICAL, UNCONSCIOUS, AND NATURAL + SELECTION</span>—<span class="scac">RESULTS OF METHODICAL + SELECTION</span>—<span class="scac">CARE TAKEN IN + SELECTION</span>—<span class="scac">SELECTION WITH + PLANTS</span>—<span class="scac">SELECTION CARRIED ON BY THE + ANCIENTS, AND BY SEMI-CIVILIZED PEOPLE</span>—<span + class="scac">UNIMPORTANT CHARACTERS OFTEN ATTENDED TO</span>—<span + class="scac">UNCONSCIOUS SELECTION</span>—<span class="scac">AS + CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR DOMESTICATED ANIMALS CHANGED + THROUGH THE ACTION OF UNCONSCIOUS SELECTION</span>—<span + class="scac">INFLUENCE OF DIFFERENT BREEDERS ON THE SAME + SUB-VARIETY</span>—<span class="scac">PLANTS AS AFFECTED BY + UNCONSCIOUS SELECTION</span>—<span class="scac">EFFECTS OF + SELECTION AS SHOWN BY THE GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST + VALUED BY MAN.</span></p> + +</blockquote> + + <p>The power of Selection, whether exercised by man, or brought into play + under nature through the struggle for existence and the consequent + survival of the fittest, absolutely depends on the variability of organic + beings. Without variability nothing can be effected; slight individual + differences, however, suffice for the work, and are probably the sole + differences which are effective in the production of new species. Hence + our discussion on the causes and laws of variability ought in strict + order to have preceded our present subject, as well as the previous + subjects of inheritance, crossing, &c.; but practically the present + arrangement has been found the most convenient. Man does not attempt to + cause variability; though he unintentionally effects this by exposing + organisms to new conditions of life, and by crossing breeds already + formed. But variability being granted, he works wonders. Unless some + degree of selection be exercised, the free commingling of the individuals + of the same variety soon obliterates, as we have previously seen, the + slight differences which may arise, and gives to the whole body of + individuals uniformity of character. In separated districts, + long-continued exposure to different conditions of life may perhaps + produce new races without the aid of selection; but to this difficult + subject <!-- Page 193 --><span class="pagenum"><a + name="page193"></a>{193}</span>of the direct action of the conditions of + life we shall in a future chapter recur.</p> + + <p>When animals or plants are born with some conspicuous and firmly + inherited new character, selection is reduced to the preservation of such + individuals, and to the subsequent prevention of crosses; so that nothing + more need be said on the subject. But in the great majority of cases a + new character, or some superiority in an old character, is at first + faintly pronounced, and is not strongly inherited; and then the full + difficulty of selection is experienced. Indomitable patience, the finest + powers of discrimination, and sound judgment must be exercised during + many years. A clearly predetermined object must be kept steadily in view. + Few men are endowed with all these qualities, especially with that of + discriminating very slight differences; judgment can be acquired only by + long experience; but if any of these qualities be wanting, the labour of + a life may be thrown away. I have been astonished when celebrated + breeders, whose skill and judgment have been proved by their success at + exhibitions, have shown me their animals, which appeared all alike, and + have assigned their reasons for matching this and that individual. The + importance of the great principle of Selection mainly lies in this power + of selecting scarcely appreciable differences, which nevertheless are + found to be transmissible, and which can be accumulated until the result + is made manifest to the eyes of every beholder.</p> + + <p>The principle of selection may be conveniently divided into three + kinds. <i>Methodical selection</i> is that which guides a man who + systematically endeavours to modify a breed according to some + predetermined standard. <i>Unconscious selection</i> is that which + follows from men naturally preserving the most valued and destroying the + less valued individuals, without any thought of altering the breed; and + undoubtedly this process slowly works great changes. Unconscious + selection graduates into methodical, and only extreme cases can be + distinctly separated; for he who preserves a useful or perfect animal + will generally breed from it with the hope of getting offspring of the + same character; but as long as he has not a predetermined purpose to + improve the breed, he may be said to be selecting <!-- Page 194 --><span + class="pagenum"><a name="page194"></a>{194}</span>unconsciously.<a + name="NtA_442" href="#Nt_442"><sup>[442]</sup></a> Lastly, we have + <i>Natural selection</i>, which implies that the individuals which are + best fitted for the complex, and in the course of ages changing + conditions to which they are exposed, generally survive and procreate + their kind. With domestic productions, with which alone we are here + strictly concerned, natural selection comes to a certain extent into + action, independently of, and even in opposition to, the will of man.</p> + +<hr class="short" /> + + <p><i>Methodical Selection.</i>—What man has effected within recent + times in England by methodical selection is clearly shown by our + exhibitions of improved quadrupeds and fancy birds. With respect to + cattle, sheep, and pigs, we owe their great improvement to a long series + of well-known names—Bakewell, Colling, Ellman, Bates, Jonas Webb, + Lords Leicester and Western, Fisher Hobbs, and others. Agricultural + writers are unanimous on the power of selection: any number of statements + to this effect could be quoted; a few will suffice. Youatt, a sagacious + and experienced observer, writes,<a name="NtA_443" + href="#Nt_443"><sup>[443]</sup></a> the principle of selection is "that + which enables the agriculturist, not only to modify the character of his + flock, but to change it altogether." A great breeder of shorthorns<a + name="NtA_444" href="#Nt_444"><sup>[444]</sup></a> says, "In the anatomy + of the shoulder modern breeders have made great improvements on the + Ketton shorthorns by correcting the defect in the knuckle or + shoulder-joint, and by laying the top of the shoulder more snugly into + the crop, and thereby filling up the hollow behind it.... The eye has its + fashion at different periods: at one time the eye high and outstanding + from the head, and at another time the sleepy eye sunk into the head; but + these extremes have merged into the medium of a full, clear, and + prominent eye with a placid look."</p> + + <p>Again, hear what an excellent judge of pigs<a name="NtA_445" + href="#Nt_445"><sup>[445]</sup></a> says: "The legs <!-- Page 195 + --><span class="pagenum"><a name="page195"></a>{195}</span>should be no + longer than just to prevent the animal's belly from trailing on the + ground. The leg is the least profitable portion of the hog, and we + therefore require no more of it than is absolutely necessary for the + support of the rest." Let any one compare the wild-boar with any improved + breed, and he will see how effectually the legs have been shortened.</p> + + <p>Few persons, except breeders, are aware of the systematic care taken + in selecting animals, and of the necessity of having a clear and almost + prophetic vision into futurity. Lord Spencer's skill and judgment were + well known; and he writes,<a name="NtA_446" + href="#Nt_446"><sup>[446]</sup></a> "It is therefore very desirable, + before any man commences to breed either cattle or sheep, that he should + make up his mind to the shape and qualities he wishes to obtain, and + steadily pursue this object." Lord Somerville, in speaking of the + marvellous improvement of the New Leicester sheep, effected by Bakewell + and his successors, says, "It would seem as if they had first drawn a + perfect form, and then given it life." Youatt<a name="NtA_447" + href="#Nt_447"><sup>[447]</sup></a> urges the necessity of annually + drafting each flock, as many animals will certainly degenerate "from the + standard of excellence, which the breeder has established in his own + mind." Even with a bird of such little importance as the canary, long ago + (1780-1790) rules were established, and a standard of perfection was + fixed, according to which the London fanciers tried to breed the several + sub-varieties.<a name="NtA_448" href="#Nt_448"><sup>[448]</sup></a> A + great winner of prizes at the Pigeon-shows,<a name="NtA_449" + href="#Nt_449"><sup>[449]</sup></a> in describing the Short-faced Almond + Tumbler, says, "There are many first-rate fanciers who are particularly + partial to what is called the goldfinch-beak, which is very beautiful; + others say, take a full-size round cherry, then take a barley-corn, and + judiciously placing and thrusting it into the cherry, form as it were + your beak; and that is not all, for it will form a good head and beak, + provided, as I said before, it is judiciously done; others take an oat; + but as I think the goldfinch-beak the handsomest, I would advise the + inexperienced fancier to get the head of a goldfinch, and keep it by him + for his observation." Wonderfully different as is the beak of the + rock-pigeon and goldfinch, undoubtedly, as far as <!-- Page 196 --><span + class="pagenum"><a name="page196"></a>{196}</span>external shape and + proportions are concerned, the end has been nearly gained.</p> + + <p>Not only should our animals be examined with the greatest care whilst + alive, but, as Anderson remarks,<a name="NtA_450" + href="#Nt_450"><sup>[450]</sup></a> their carcases should be scrutinised, + "so as to breed from the descendants of such only as, in the language of + the butcher, cut up well." The "grain of the meat" in cattle, and its + being well marbled with fat,<a name="NtA_451" + href="#Nt_451"><sup>[451]</sup></a> and the greater or less accumulation + of fat in the abdomen of our sheep, have been attended to with success. + So with poultry, a writer,<a name="NtA_452" + href="#Nt_452"><sup>[452]</sup></a> speaking of Cochin-China fowls, which + are said to differ much in the quality of their flesh, says, "the best + mode is to purchase two young brother-cocks, kill, dress, and serve up + one; if he be indifferent, similarly dispose of the other, and try again; + if, however, he be fine and well-flavoured, his brother will not be amiss + for breeding purposes for the table."</p> + + <p>The great principle of the division of labour has been brought to bear + on selection. In certain districts<a name="NtA_453" + href="#Nt_453"><sup>[453]</sup></a> "the breeding of bulls is confined to + a very limited number of persons, who by devoting their whole attention + to this department, are able from year to year to furnish a class of + bulls which are steadily improving the general breed of the district." + The rearing and letting of choice rams has long been, as is well known, a + chief source of profit to several eminent breeders. In parts of Germany + this principle is carried with merino sheep to an extreme point.<a + name="NtA_454" href="#Nt_454"><sup>[454]</sup></a> "So important is the + proper selection of breeding animals considered, that the best + flock-masters do not trust to their own judgment, or to that of their + shepherds, but employ persons called 'sheep-classifiers,' who make it + their special business to attend to this part of the management of + several flocks, and thus to preserve, or if possible to improve, the best + qualities of both parents in the lambs." In Saxony, "when the lambs are + weaned, each in his turn is placed upon a table that his wool and form + may be minutely observed. <!-- Page 197 --><span class="pagenum"><a + name="page197"></a>{197}</span>The finest are selected for breeding and + receive a first mark. When they are one year old, and prior to shearing + them, another close examination of those previously marked takes place: + those in which no defect can be found receive a second mark, and the rest + are condemned. A few months afterwards a third and last scrutiny is made; + the prime rams and ewes receive a third and final mark, but the slightest + blemish is sufficient to cause the rejection of the animal." These sheep + are bred and valued almost exclusively for the fineness of their wool; + and the result corresponds with the labour bestowed on their selection. + Instruments have been invented to measure accurately the thickness of the + fibres; and "an Austrian fleece has been produced of which twelve hairs + equalled in thickness one from a Leicester sheep."</p> + + <p>Throughout the world, wherever silk is produced, the greatest care is + bestowed on selecting the cocoons from which the moths for breeding are + to be reared. A careful cultivator<a name="NtA_455" + href="#Nt_455"><sup>[455]</sup></a> likewise examines the moths + themselves, and destroys those that are not perfect. But what more + immediately concerns us is that certain families in France devote + themselves to raising eggs for sale.<a name="NtA_456" + href="#Nt_456"><sup>[456]</sup></a> In China, near Shanghai, the + inhabitants of two small districts have the privilege of raising eggs for + the whole surrounding country, and that they may give up their whole time + to this business, they are interdicted by law from producing silk.<a + name="NtA_457" href="#Nt_457"><sup>[457]</sup></a></p> + + <p>The care which successful breeders take in matching their birds is + surprising. Sir John Sebright, whose fame is perpetuated by the "Sebright + Bantam," used to spend "two and three days in examining, consulting, and + disputing with a friend which were the best of five or six birds."<a + name="NtA_458" href="#Nt_458"><sup>[458]</sup></a> Mr. Bult, whose + pouter-pigeons won so many prizes and were exported to North America + under the charge of a man sent on purpose, told me that he always + deliberated for several days before he matched each pair. Hence we can + understand the advice of an eminent fancier, who writes,<a name="NtA_459" + href="#Nt_459"><sup>[459]</sup></a> "I would here particularly guard <!-- + Page 198 --><span class="pagenum"><a name="page198"></a>{198}</span>you + against having too great a variety of pigeons, otherwise you will know a + little of all, but nothing about one as it ought to be known." Apparently + it transcends the power of the human intellect to breed all kinds: "it is + possible that there may be a few fanciers that have a good general + knowledge of fancy pigeons; but there are many more who labour under the + delusion of supposing they know what they do not." The excellence of one + sub-variety, the Almond Tumbler, lies in the plumage, carriage, head, + beak, and eye; but it is too presumptuous in the beginner to try for all + these points. The great judge above quoted says, "there are some young + fanciers who are over-covetous, who go for all the above five properties + at once; they have their reward by getting nothing." We thus see that + breeding even fancy pigeons is no simple art: we may smile at the + solemnity of these precepts, but he who laughs will win no prizes.</p> + + <p>What methodical selection has effected for our animals is sufficiently + proved, as already remarked, by our Exhibitions. So greatly were the + sheep belonging to some of the earlier breeders, such as Bakewell and + Lord Western, changed, that many persons could not be persuaded that they + had not been crossed. Our pigs, as Mr. Corringham remarks,<a + name="NtA_460" href="#Nt_460"><sup>[460]</sup></a> during the last twenty + years have undergone, through rigorous selection together with crossing, + a complete metamorphosis. The first exhibition for poultry was held in + the Zoological Gardens in 1845; and the improvement effected since that + time has been great. As Mr. Baily, the great judge, remarked to me, it + was formerly ordered that the comb of the Spanish cock should be upright, + and in four or five years all good birds had upright combs; it was + ordered that the Polish cock should have no comb or wattles, and now a + bird thus furnished would be at once disqualified; beards were ordered, + and out of fifty-seven pens lately (1860) exhibited at the Crystal + Palace, all had beards. So it has been in many other cases. But in all + cases the judges order only what is occasionally produced and what can be + improved and rendered constant by selection. The steady increase of + weight during the last few years in our <!-- Page 199 --><span + class="pagenum"><a name="page199"></a>{199}</span>fowls, turkeys, ducks, + and geese is notorious; "six-pound ducks are now common, whereas four + pounds was formerly the average." As the actual time required to make a + change has not often been recorded, it may be worth mentioning that it + took Mr. Wicking thirteen years to put a clean white head on an almond + tumbler's body, "a triumph," says another fancier, "of which he may be + justly proud."<a name="NtA_461" href="#Nt_461"><sup>[461]</sup></a></p> + + <p>Mr. Tollet, of Betley Hall, selected cows, and especially bulls, + descended from good milkers, for the sole purpose of improving his cattle + for the production of cheese; he steadily tested the milk with the + lactometer, and in eight years he increased, as I was informed by him, + the product in the proportion of four to three. Here is a curious case<a + name="NtA_462" href="#Nt_462"><sup>[462]</sup></a> of steady but slow + progress, with the end not as yet fully attained: in 1784 a race of + silkworms was introduced into France, in which one hundred out of the + thousand failed to produce white cocoons; but now, after careful + selection during sixty-five generations, the proportion of yellow cocoons + has been reduced to thirty-five in the thousand.</p> + + <p>With plants selection has been followed with the same good results as + with animals. But the process is simpler, for plants in the great + majority of cases bear both sexes. Nevertheless, with most kinds it is + necessary to take as much care to prevent crosses as with animals or + unisexual plants; but with some plants, such as peas, this care does not + seem to be necessary. With all improved plants, excepting of course those + which are propagated by buds, cuttings, &c., it is almost + indispensable to examine the seedlings and destroy those which depart + from the proper type. This is called "roguing," and is, in fact, a form + of selection, like the rejection of inferior animals. Experienced + horticulturists and agriculturists incessantly urge every one to preserve + the finest plants for the production of seed.</p> + + <p>Although plants often present much more conspicuous variations than + animals, yet the closest attention is generally requisite to detect each + slight and favourable change. Mr. Masters relates<a name="NtA_463" + href="#Nt_463"><sup>[463]</sup></a> how "many a patient hour was + devoted," whilst he was <!-- Page 200 --><span class="pagenum"><a + name="page200"></a>{200}</span>young, to the detection of differences in + peas intended for seed. Mr. Barnet<a name="NtA_464" + href="#Nt_464"><sup>[464]</sup></a> remarks that the old scarlet American + strawberry was cultivated for more than a century without producing a + single variety; and another writer observes how singular it was that when + gardeners first began to attend to this fruit it began to vary; the truth + no doubt being that it had always varied, but that, until slight + varieties were selected and propagated by seed, no conspicuous result was + obtained. The finest shades of difference in wheat have been + discriminated and selected with almost as much care, as we see in Colonel + Le Couteur's works, as in the case of the higher animals; but with our + cereals the process of selection has seldom or never been long + continued.</p> + + <p>It may be worth while to give a few examples of methodical selection + with plants; but in fact the great improvement of all our anciently + cultivated plants may be attributed to selection long carried on, in part + methodically, and in part unconsciously. I have shown in a former chapter + how the weight of the gooseberry has been increased by systematic + selection and culture. The flowers of the Heartsease have been similarly + increased in size and regularity of outline. With the Cineraria, Mr. + Glenny<a name="NtA_465" href="#Nt_465"><sup>[465]</sup></a> "was bold + enough, when the flowers were ragged and starry and ill defined in + colour, to fix a standard which was then considered outrageously high and + impossible, and which, even if reached, it was said, we should be no + gainers by, as it would spoil the beauty of the flowers. He maintained + that he was right; and the event has proved it to be so." The doubling of + flowers has several times been effected by careful selection: the Rev. W. + Williamson,<a name="NtA_466" href="#Nt_466"><sup>[466]</sup></a> after + sowing during several years seed of <i>Anemone coronaria</i>, found a + plant with one additional petal; he sowed the seed of this, and by + perseverance in the same course obtained several varieties with six or + seven rows of petals. The single Scotch rose was doubled, and yielded + eight good varieties in nine or ten years.<a name="NtA_467" + href="#Nt_467"><sup>[467]</sup></a> The Canterbury bell (<i>Campanula + medium</i>) was doubled by careful selection in four generations.<a + name="NtA_468" href="#Nt_468"><sup>[468]</sup></a> In four years Mr. + Buckman,<a name="NtA_469" href="#Nt_469"><sup>[469]</sup></a> by culture + and <!-- Page 201 --><span class="pagenum"><a + name="page201"></a>{201}</span>careful selection, converted parsnips, + raised from wild seed, into a new and good variety. By selection during a + long course of years, the early maturity of peas has been hastened from + ten to twenty-one days.<a name="NtA_470" + href="#Nt_470"><sup>[470]</sup></a> A more curious case is offered by the + beet-plant, which, since its cultivation in France, has almost exactly + doubled its yield of sugar. This has been effected by the most careful + selection; the specific gravity of the roots being regularly tested, and + the best roots saved for the production of seed.<a name="NtA_471" + href="#Nt_471"><sup>[471]</sup></a></p> + +<p class="cenhead"><i>Selection by Ancient and Semi-civilised People.</i></p> + + <p>In attributing so much importance to the selection of animals and + plants, it may be objected that methodical selection would not have been + carried on during ancient times. A distinguished naturalist considers it + as absurd to suppose that semi-civilised people should have practised + selection of any kind. Undoubtedly the principle has been systematically + acknowledged and followed to a far greater extent within the last hundred + years than at any former period, and a corresponding result has been + gained; but it would be a great error to suppose, as we shall immediately + see, that its importance was not recognised and acted on during the most + ancient times, and by semi-civilised people. I should premise that many + facts now to be given only show that care was taken in breeding; but when + this is the case, selection is almost sure to be practised to a certain + extent. We shall hereafter be enabled better to judge how far selection, + when only occasionally carried on, by a few of the inhabitants of a + country, will slowly produce a great effect.</p> + + <p>In a well-known passage in the thirtieth chapter of Genesis, rules are + given for influencing, as was then thought possible, the colour of sheep; + and speckled and dark breeds are spoken of as being kept separate. By the + time of David the fleece was likened to snow. Youatt,<a name="NtA_472" + href="#Nt_472"><sup>[472]</sup></a> who has discussed all the passages in + relation to breeding in the Old Testament, concludes that <!-- Page 202 + --><span class="pagenum"><a name="page202"></a>{202}</span>at this early + period "some of the best principles of breeding must have been steadily + and long pursued." It was ordered, according to Moses, that "Thou shalt + not let thy cattle gender with a diverse kind;" but mules were + purchased,<a name="NtA_473" href="#Nt_473"><sup>[473]</sup></a> so that + at this early period other nations must have crossed the horse and ass. + It is said<a name="NtA_474" href="#Nt_474"><sup>[474]</sup></a> that + Erichthonius, some generations before the Trojan war, had many + brood-mares, "which by his care and judgment in the choice of stallions + produced a breed of horses superior to any in the surrounding countries." + Homer (Book v.) speaks of Æneas's horses as bred from mares which were + put to the steeds of Laomedon. Plato, in his 'Republic,' says to Glaucus, + "I see that you raise at your house a great many dogs for the chase. Do + you take care about breeding and pairing them? Among animals of good + blood, are there not always some which are superior to the rest?" To + which Glaucus answers in the affirmative.<a name="NtA_475" + href="#Nt_475"><sup>[475]</sup></a> Alexander the Great selected the + finest Indian cattle to send to Macedonia to improve the breed.<a + name="NtA_476" href="#Nt_476"><sup>[476]</sup></a> According to Pliny,<a + name="NtA_477" href="#Nt_477"><sup>[477]</sup></a> King Pyrrhus had an + especially valuable breed of oxen; and he did not suffer the bulls and + cows to come together till four years old, that the breed might not + degenerate. Virgil, in his Georgics (lib. iii.), gives as strong advice + as any modern agriculturist could do, carefully to select the breeding + stock; "to note the tribe, the lineage, and the sire; whom to reserve for + husband of the herd;"—to brand the progeny;—to select sheep + of the purest white, and to examine if their tongues are swarthy. We have + seen that the Romans kept pedigrees of their pigeons, and this would have + been a senseless proceeding had not great care been taken in breeding + them. Columella gives detailed instructions about breeding fowls: "Let + the breeding hens therefore be of a choice colour, a robust body, + square-built, full-breasted, with large heads, with upright and + bright-red combs. Those are believed to be the best bred which have five + toes."<a name="NtA_478" href="#Nt_478"><sup>[478]</sup></a> According to + Tacitus, the Celts attended to the races of their domestic animals; <!-- + Page 203 --><span class="pagenum"><a name="page203"></a>{203}</span>and + Cæsar states that they paid high prices to merchants for fine imported + horses.<a name="NtA_479" href="#Nt_479"><sup>[479]</sup></a> In regard to + plants, Virgil speaks of yearly culling the largest seeds; and Celsus + says, "where the corn and crop is but small, we must pick out the best + ears of corn, and of them lay up our seed separately by itself."<a + name="NtA_480" href="#Nt_480"><sup>[480]</sup></a></p> + + <p>Coming down the stream of time, we may be brief. At about the + beginning of the ninth century Charlemagne expressly ordered his officers + to take great care of his stallions; and if any proved bad or old, to + forewarn him in good time before they were put to the mares.<a + name="NtA_481" href="#Nt_481"><sup>[481]</sup></a> Even in a country so + little civilised as Ireland during the ninth century, it would appear + from some ancient verses,<a name="NtA_482" + href="#Nt_482"><sup>[482]</sup></a> describing a ransom demanded by + Cormac, that animals from particular places, or having a particular + character, were valued. Thus it is said,—</p> + + <div class="poem"> + <div class="stanza"> + <p>Two pigs of the pigs of Mac Lir,</p> + <p>A ram and ewe both round and red,</p> + <p>I brought with me from Aengus.</p> + <p>I brought with me a stallion and a mare</p> + <p>From the beautiful stud of Manannan,</p> + <p>A bull and a white cow from Druim Cain.</p> + </div> + </div> + + <p>Athelstan, in 930, received as a present from Germany, running-horses; + and he prohibited the exportation of English horses. King John imported + "one hundred chosen stallions from Flanders."<a name="NtA_483" + href="#Nt_483"><sup>[483]</sup></a> On June 16th, 1305, the Prince of + Wales wrote to the Archbishop of Canterbury, begging for the loan of any + choice stallion, and promising its return at the end of the season.<a + name="NtA_484" href="#Nt_484"><sup>[484]</sup></a> There are numerous + records at ancient periods in English history of the importation of + choice animals of various kinds, and of foolish laws against their + exportation. In the reigns of Henry VII. and VIII. it was ordered that + the magistrates, at Michaelmas, should scour the heaths and commons, and + destroy all mares beneath a certain size.<a name="NtA_485" + href="#Nt_485"><sup>[485]</sup></a> Some of our earlier kings passed laws + against the slaughtering rams of any good breed before they were seven + years old, so that they <!-- Page 204 --><span class="pagenum"><a + name="page204"></a>{204}</span>might have time to breed. In Spain + Cardinal Ximenes issued, in 1509, regulations on the <i>selection</i> of + good rams for breeding.<a name="NtA_486" + href="#Nt_486"><sup>[486]</sup></a></p> + + <p>The Emperor Akbar Khan before the year 1600 is said to have + "wonderfully improved" his pigeons by crossing the breeds; and this + necessarily implies careful selection. About the same period the Dutch + attended with the greatest care to the breeding of these birds. Belon in + 1555 says that good managers in France examined the colour of their + goslings in order to get geese of a white colour and better kinds. + Markham in 1631 tells the breeder "to elect the largest and goodliest + conies," and enters into minute details. Even with respect to seeds of + plants for the flower-garden, Sir J. Hanmer writing about the year 1660<a + name="NtA_487" href="#Nt_487"><sup>[487]</sup></a> says, in "choosing + seed, the best seed is the most weighty, and is had from the lustiest and + most vigorous stems;" and he then gives rules about leaving only a few + flowers on plants for seed; so that even such details were attended to in + our flower-gardens two hundred years ago. In order to show that selection + has been silently carried on in places where it would not have been + expected, I may add that in the middle of the last century, in a remote + part of North America, Mr. Cooper improved by careful selection all his + vegetables, "so that they were greatly superior to those of any other + person. When his radishes, for instance, are fit for use, he takes ten or + twelve that he most approves, and plants them at least 100 yards from + others that blossom at the same time. In the same manner he treats all + his other plants, varying the circumstances according to their nature."<a + name="NtA_488" href="#Nt_488"><sup>[488]</sup></a></p> + + <p>In the great work on China published in the last century by the + Jesuits, and which is chiefly compiled from ancient Chinese + encyclopædias, it is said that with sheep "improving the breed consists + in choosing with particular care the lambs which are destined for + propagation, in nourishing them well, and in keeping the flocks + separate." The same principles were applied by the Chinese to various + plants and fruit-trees.<a name="NtA_489" + href="#Nt_489"><sup>[489]</sup></a> An <!-- Page 205 --><span + class="pagenum"><a name="page205"></a>{205}</span>imperial edict + recommends the choice of seed of remarkable size; and selection was + practised even by imperial hands, for it is said that the Ya-mi, or + imperial rice, was noticed at an ancient period in a field by the Emperor + Khang-hi, was saved and cultivated in his garden, and has since become + valuable from being the only kind which will grow north of the Great + Wall.<a name="NtA_490" href="#Nt_490"><sup>[490]</sup></a> Even with + flowers, the tree pæony (<i>P. moutan</i>) has been cultivated, according + to Chinese traditions, for 1400 years; between 200 and 300 varieties have + been raised, which are cherished like tulips formerly were by the + Dutch.<a name="NtA_491" href="#Nt_491"><sup>[491]</sup></a></p> + + <p>Turning now to semi-civilised people and to savages: it occurred to + me, from what I had seen of several parts of South America, where fences + do not exist, and where the animals are of little value, that there would + be absolutely no care in breeding or selecting them; and this to a large + extent is true. Roulin,<a name="NtA_492" + href="#Nt_492"><sup>[492]</sup></a> however, describes in Colombia a + naked race of cattle, which are not allowed to increase, on account of + their delicate constitution. According to Azara<a name="NtA_493" + href="#Nt_493"><sup>[493]</sup></a> horses are often born in Paraguay + with curly hair; but, as the natives do not like them, they are + destroyed. On the other hand, Azara states that a hornless bull, born in + 1770, was preserved and propagated its race. I was informed of the + existence in Banda Oriental of a breed with reversed hair; and the + extraordinary niata cattle first appeared and have since been kept + distinct in La Plata. Hence certain conspicuous variations have been + preserved, and others have been habitually destroyed, in these countries, + which are so little favourable for careful selection. We have also seen + that the inhabitants sometimes introduce cattle on their estates to + prevent the evil effects of close interbreeding. On the other hand, I + have heard on reliable authority that the Gauchos of the Pampas never + take any pains in selecting the best bulls or stallions for breeding; and + this probably accounts for the cattle and horses being remarkably uniform + in character throughout the immense range of the Argentine republic.</p> + + <p>Looking to the Old World, in the Sahara Desert "The Touareg is as + careful in the selection of his breeding Mahari <!-- Page 206 --><span + class="pagenum"><a name="page206"></a>{206}</span>(a fine race of the + dromedary) as the Arab is in that of his horse. The pedigrees are handed + down, and many a dromedary can boast a genealogy far longer than the + descendants of the Darley Arabian."<a name="NtA_494" + href="#Nt_494"><sup>[494]</sup></a> According to Pallas the Mongolians + endeavour to breed the Yaks or horse-tailed buffaloes with white tails, + for these are sold to the Chinese mandarins as fly-flappers; and + Moorcroft, about seventy years after Pallas, found that white-tailed + animals were still selected for breeding.<a name="NtA_495" + href="#Nt_495"><sup>[495]</sup></a></p> + + <p>We have seen in the chapter on the Dog that savages in different parts + of North America and in Guiana cross their dogs with wild Canidæ, as did + the ancient Gauls, according to Pliny. This was done to give their dogs + strength and vigour, in the same way as the keepers in large warrens now + sometimes cross their ferrets (as I have been informed by Mr. Yarrell) + with the wild polecat, "to give them more devil." According to Varro, the + wild ass was formerly caught and crossed with the tame animal to improve + the breed, in the same manner as at the present day the natives of Java + sometimes drive their cattle into the forests to cross with the wild + Banteng (<i>Bos sondaicus</i>).<a name="NtA_496" + href="#Nt_496"><sup>[496]</sup></a> In Northern Siberia, among the + Ostyaks the dogs vary in markings in different districts, but in each + place they are spotted black and white in a remarkably uniform manner;<a + name="NtA_497" href="#Nt_497"><sup>[497]</sup></a> and from this fact + alone we may infer careful breeding, more especially as the dogs of one + locality are famed throughout the country for their superiority. I have + heard of certain tribes of Esquimaux who take pride in their teams of + dogs being uniformly coloured. In Guiana, as Sir R. Schomburgk informs + me,<a name="NtA_498" href="#Nt_498"><sup>[498]</sup></a> the dogs of the + Turuma Indians are highly valued and extensively bartered: the price of a + good one is the same as that given for a wife: they are kept in a sort of + cage, and the Indians "take great care when the female is in season to + prevent her uniting with a dog of an inferior description." The Indians + told Sir Robert that, if a dog proved bad or useless, <!-- Page 207 + --><span class="pagenum"><a name="page207"></a>{207}</span>he was not + killed, but was left to die from sheer neglect. Hardly any nation is more + barbarous than the Fuegians, but I hear from Mr. Bridges, the Catechist + to the Mission, that, "when these savages have a large, strong, and + active bitch, they take care to put her to a fine dog, and even take care + to feed her well, that her young may be strong and well favoured."</p> + + <p>In the interior of Africa, negroes, who have not associated with white + men, show great anxiety to improve their animals: they "always choose the + larger and stronger males for stock:" the Malakolo were much pleased at + Livingstone's promise to send them a bull, and some Bakalolo carried a + live cock all the way from Loanda into the interior.<a name="NtA_499" + href="#Nt_499"><sup>[499]</sup></a> Further south on the same continent, + Andersson states that he has known a Damara give two fine oxen for a dog + which struck his fancy. The Damaras take great delight in having whole + droves of cattle of the same colour, and they prize their oxen in + proportion to the size of their horns. "The Namaquas have a perfect mania + for a uniform team; and almost all the people of Southern Africa value + their cattle next to their women, and take a pride in possessing animals + that look high-bred." "They rarely or never make use of a handsome animal + as a beast of burden."<a name="NtA_500" + href="#Nt_500"><sup>[500]</sup></a> The power of discrimination which + these savages possess is wonderful, and they can recognise to which tribe + any cattle belong. Mr. Andersson further informs me that the natives + frequently match a particular bull with a particular cow.</p> + + <p>The most curious case of selection by semi-civilised people, or indeed + by any people, which I have found recorded, is that given by Garcilazo de + la Vega, a descendant of the Incas, as having been practised in Peru + before the country was subjugated by the Spaniards.<a name="NtA_501" + href="#Nt_501"><sup>[501]</sup></a> The Incas annually held great hunts, + when all the wild animals were driven from an immense circuit to a + central point. The beasts of prey were first destroyed as injurious. The + wild Guanacos and Vicunas were sheared; the old males and females killed, + and the others set at liberty. The various kinds of deer were examined; + the old males and females <!-- Page 208 --><span class="pagenum"><a + name="page208"></a>{208}</span>were likewise killed; "but the young + females, with a certain number of males, selected from the most beautiful + and strong," were given their freedom. Here, then, we have selection by + man aiding natural selection. So that the Incas followed exactly the + reverse system of that which our Scottish sportsmen are accused of + following, namely, of steadily killing the finest stags, thus causing the + whole race to degenerate.<a name="NtA_502" + href="#Nt_502"><sup>[502]</sup></a> In regard to the domesticated llamas + and alpacas, they were separated in the time of the Incas according to + colour; and if by chance one in a flock was born of the wrong colour, it + was eventually put into another flock.</p> + + <p>In the genus Auchenia there are four forms,—the Guanaco and + Vicuna, found wild and undoubtedly distinct species; the Llama and + Alpaca, known only in a domesticated condition. These four animals appear + so different, that most professed naturalists, especially those who have + studied these animals in their native country, maintain that they are + specifically distinct, notwithstanding that no one pretends to have seen + a wild llama or alpaca. Mr. Ledger, however, who has closely studied + these animals both in Peru and during their exportation to Australia, and + who has made many experiments on their propagation, adduces arguments<a + name="NtA_503" href="#Nt_503"><sup>[503]</sup></a> which seem to me + conclusive, that the llama is the domesticated descendant of the guanaco, + and the alpaca of the vicuna. And now that we know that these animals + many centuries ago were systematically bred and selected, there is + nothing surprising in the great amount of change which they have + undergone.</p> + + <p>It appeared to me at one time probable that, though ancient and + semi-civilised people might have attended to the improvement of their + more useful animals in essential points, yet that they would have + disregarded unimportant characters. But human nature is the same + throughout the world: fashion everywhere reigns supreme, and man is apt + to value whatever he may chance to possess. We have seen that in South + America the niata cattle, which certainly are not made useful by their + shortened faces and upturned nostrils, have been preserved. The Damaras + of South Africa value their cattle for uniformity <!-- Page 209 --><span + class="pagenum"><a name="page209"></a>{209}</span>of colour and + enormously long horns. The Mongolians value their yaks for their white + tails. And I shall now show that there is hardly any peculiarity in our + most useful animals which, from fashion, superstition, or some other + motive, has not been valued, and consequently preserved. With respect to + cattle, "an early record," according to Youatt,<a name="NtA_504" + href="#Nt_504"><sup>[504]</sup></a> "speaks of a hundred white cows with + red ears being demanded as a compensation by the princes of North and + South Wales. If the cattle were of a dark or black colour, 150 were to be + presented." So that colour was attended to in Wales before its + subjugation by England. In Central Africa, an ox that beats the ground + with its tail is killed; and in South Africa some of the Damaras will not + eat the flesh of a spotted ox. The Kaffirs value an animal with a musical + voice; and "at a sale in British Kaffraria the low of a heifer excited so + much admiration that a sharp competition sprung up for her possession, + and she realised a considerable price."<a name="NtA_505" + href="#Nt_505"><sup>[505]</sup></a> With respect to sheep, the Chinese + prefer rams without horns; the Tartars prefer them with spirally wound + horns, because the hornless are thought to lose courage.<a name="NtA_506" + href="#Nt_506"><sup>[506]</sup></a> Some of the Damaras will not eat the + flesh of hornless sheep. In regard to horses, at the end of the fifteenth + century animals of the colour described as <i>liart pommé</i> were most + valued in France. The Arabs have a proverb, "Never buy a horse with four + white feet, for he carries his shroud with him;"<a name="NtA_507" + href="#Nt_507"><sup>[507]</sup></a> the Arabs also, as we have seen, + despise dun-coloured horses. So with dogs, Xenophon and others at an + ancient period were prejudiced in favour of certain colours; and "white + or slate-coloured hunting dogs were not esteemed."<a name="NtA_508" + href="#Nt_508"><sup>[508]</sup></a></p> + + <p>Turning to poultry, the old Roman gourmands thought that the liver of + a white goose was the most savoury. In Paraguay black-skinned fowls are + kept because they are thought to be more productive, and their flesh the + most proper for invalids.<a name="NtA_509" + href="#Nt_509"><sup>[509]</sup></a> In Guiana, as I am informed by Sir R. + Schomburgk, the aborigines will not eat the flesh or eggs of the fowl, + but two <!-- Page 210 --><span class="pagenum"><a + name="page210"></a>{210}</span>races are kept distinct merely for + ornament. In the Philippines, no less than nine sub-varieties of the game + cock are kept and named, so that they must be separately bred.</p> + + <p>At the present time in Europe, the smallest peculiarities are + carefully attended to in our most useful animals, either from fashion, or + as a mark of purity of blood. Many examples could be given, two will + suffice. "In the Western counties of England the prejudice against a + white pig is nearly as strong as against a black one in Yorkshire." In + one of the Berkshire sub-breeds, it is said, "the white should be + confined to four white feet, a white spot between the eyes, and a few + white hairs behind each shoulder." Mr. Saddler possessed "three hundred + pigs, every one of which was marked in this manner."<a name="NtA_510" + href="#Nt_510"><sup>[510]</sup></a> Marshall, towards the close of the + last century, in speaking of a change in one of the Yorkshire breeds of + cattle, says the horns have been considerably modified, as "a clean, + small, sharp horn has been <i>fashionable</i> for the last twenty + years."<a name="NtA_511" href="#Nt_511"><sup>[511]</sup></a> In a part of + Germany the cattle of the Race de Gfoehl are valued for many good + qualities, but they must have horns of a particular curvature and tint, + so much so that mechanical means are applied if they take a wrong + direction; but the inhabitants "consider it of the highest importance + that the nostrils of the bull should be flesh-coloured, and the eyelashes + light; this is an indispensable condition. A calf with blue nostrils + would not be purchased, or purchased at a very low price."<a + name="NtA_512" href="#Nt_512"><sup>[512]</sup></a> Therefore let no man + say that any point or character is too trifling to be methodically + attended to and selected by breeders.</p> + +<hr class="short" /> + + <p><i>Unconscious Selection.</i>—By this term I mean, as already + more than once explained, the preservation by man of the most valued, and + the destruction of the least valued individuals, without any conscious + intention on his part of altering the breed. It is difficult to offer + direct proofs of the results which follow from this kind of selection; + but the indirect evidence is abundant. In fact, except that in the one + case man acts intentionally, and in the other unintentionally, there is + little difference between <!-- Page 211 --><span class="pagenum"><a + name="page211"></a>{211}</span>methodical and unconscious selection. In + both cases man preserves the animals which are most useful or pleasing to + him, and destroys or neglects the others. But no doubt a far more rapid + result follows from methodical than from unconscious selection. The + "roguing" of plants by gardeners, and the destruction by law in Henry + VIII.'s reign of all under-sized mares, are instances of a process the + reverse of selection in the ordinary sense of the word, but leading to + the same general result. The influence of the destruction of individuals + having a particular character is well shown by the necessity of killing + every lamb with a trace of black about it, in order to keep the flock + white; or again, by the effects on the average height of the men of + France of the destructive wars of Napoleon, by which many tall men were + killed, the short ones being left to be the fathers of families. This at + least is the conclusion of those who have closely studied the subject of + the conscription; and it is certain that since Napoleon's time the + standard for the army has been lowered two or three times.</p> + + <p>Unconscious selection so blends into methodical that it is scarcely + possible to separate them. When a fancier long ago first happened to + notice a pigeon with an unusually short beak, or one with the + tail-feathers unusually developed, although he bred from these birds with + the distinct intention of propagating the variety, yet he could not have + intended to make a short-faced tumbler or a fantail, and was far from + knowing that he had made the first step towards this end. If he could + have seen the final result, he would have been struck with astonishment, + but, from what we know of the habits of fanciers, probably not with + admiration. Our English carriers, barbs, and short-faced tumblers have + been greatly modified in the same manner, as we may infer both from the + historical evidence given in the chapters on the Pigeon, and from the + comparison of birds brought from distant countries.</p> + + <p>So it has been with dogs; our present fox-hounds differ from the old + English hound; our greyhounds have become lighter; the wolf-dog, which + belonged to the greyhound class, has become extinct; the Scotch + deer-hound has been modified, and is now rare. Our bulldogs differ from + those which were formerly used for baiting bulls. Our pointers and + Newfoundlands do not <!-- Page 212 --><span class="pagenum"><a + name="page212"></a>{212}</span>closely resemble any native dog now found + in the countries whence they were brought, These changes have been + effected partly by crosses; but in every case the result has been + governed by the strictest selection. Nevertheless there is no reason to + suppose that man intentionally and methodically made the breeds exactly + what they now are. As our horses became fleeter, and the country more + cultivated and smoother, fleeter fox-hounds were desired and produced, + but probably without any one distinctly foreseeing what they would + become. Our pointers and setters, the latter almost certainly descended + from large spaniels, have been greatly modified in accordance with + fashion and the desire for increased speed. Wolves have become extinct, + deer have become rarer, bulls are no longer baited, and the corresponding + breeds of the dog have answered to the change. But we may feel almost + sure that when, for instance, bulls were no longer baited, no man said to + himself, I will now breed my dogs of smaller size, and thus create the + present race. As circumstances changed, men unconsciously and slowly + modified their course of selection.</p> + + <p>With race-horses selection for swiftness has been followed + methodically, and our horses can now easily beat their progenitors. The + increased size and different appearance of the English race-horse led a + good observer in India to ask, "Could any one in this year of 1856, + looking at our race-horses, conceive that they were the result of the + union of the Arab horse and the African mare?"<a name="NtA_513" + href="#Nt_513"><sup>[513]</sup></a> This change has, it is probable, been + largely effected through unconscious selection, that is, by the general + wish to breed as fine horses as possible in each generation, combined + with training and high feeding, but without any intention to give to them + their present appearance. According to Youatt,<a name="NtA_514" + href="#Nt_514"><sup>[514]</sup></a> the introduction in Oliver Cromwell's + time of three celebrated Eastern stallions speedily affected the English + breed; "so that Lord Harleigh, one of the old school, complained that the + great horse was fast disappearing." This is an excellent proof how + carefully selection must have been attended to; for without such care, + all traces of so small an infusion of Eastern blood would soon have been + absorbed and <!-- Page 213 --><span class="pagenum"><a + name="page213"></a>{213}</span>lost. Notwithstanding that the climate of + England has never been esteemed particularly favourable to the horse, yet + long-continued selection, both methodical and unconscious, together with + that practised by the Arabs during a still longer and earlier period, has + ended in giving us the best breed of horses in the world. Macaulay<a + name="NtA_515" href="#Nt_515"><sup>[515]</sup></a> remarks, "Two men + whose authority on such subjects was held in great esteem, the Duke of + Newcastle and Sir John Fenwick, pronounced that the meanest hack ever + imported from Tangier would produce a finer progeny than could be + expected from the best sire of our native breed. They would not readily + have believed that a time would come when the princes and nobles of + neighbouring lands would be as eager to obtain horses from England as + ever the English had been to obtain horses from Barbary."</p> + + <p>The London dray-horse, which differs so much in appearance from any + natural species, and which from its size has so astonished many Eastern + princes, was probably formed by the heaviest and most powerful animals + having been selected during many generations in Flanders and England, but + without the least intention or expectation of creating a horse such as we + now see. If we go back to an early period of history, we behold in the + antique Greek statues, as Schaaffhausen has remarked,<a name="NtA_516" + href="#Nt_516"><sup>[516]</sup></a> a horse equally unlike a race or dray + horse, and differing from any existing breed.</p> + + <p>The results of unconscious selection, in an early stage, are well + shown in the difference between the flocks descended from the same stock, + but separately reared by careful breeders. Youatt gives an excellent + instance of this fact in the sheep belonging to Messrs. Buckley and + Burgess, which "have been purely bred from the original stock of Mr. + Bakewell for upwards of fifty years. There is not a suspicion existing in + the mind of any one at all acquainted with the subject that the owner of + either flock has deviated in any one instance from the pure blood of Mr. + Bakewell's flock; yet the difference between the sheep possessed by these + two gentlemen is so great, that they have the appearance of being quite + different varieties."<a name="NtA_517" + href="#Nt_517"><sup>[517]</sup></a> I have seen several analogous and + <!-- Page 214 --><span class="pagenum"><a + name="page214"></a>{214}</span>well-marked cases with pigeons: for + instance, I had a family of barbs, descended from those long bred by Sir + J. Sebright, and another family long bred by another fancier, and the two + families plainly differed from each other. Nathusius—and a more + competent witness could not be cited—observes that, though the + Shorthorns are remarkably uniform inn appearance (except in colouring), + yet that the individual character and wishes of each breeder become + impressed on his cattle, so that different herds differ slightly from + each other.<a name="NtA_518" href="#Nt_518"><sup>[518]</sup></a> The + Hereford cattle assumed their present well-marked character soon after + the year 1769, through careful selection by Mr. Tomkins,<a name="NtA_519" + href="#Nt_519"><sup>[519]</sup></a> and the breed has lately split into + two strains—one strain having a white face, and differing slightly, + it is said,<a name="NtA_520" href="#Nt_520"><sup>[520]</sup></a> in some + other points; but there is no reason to believe that this split, the + origin of which is unknown, was intentionally made; it may with much more + probability be attributed to different breeders having attended to + different points. So again, the Berkshire breed of swine in the year 1810 + had greatly changed from what it had been in 1780; and since 1810 at + least two distinct sub-breeds have borne this same name.<a name="NtA_521" + href="#Nt_521"><sup>[521]</sup></a> When we bear in mind how rapidly all + animals increase, and that some must be annually slaughtered and some + saved for breeding, then, if the same breeder during a long course of + years deliberately settles which shall be saved and which shall be + killed, it is almost inevitable that his individual frame of mind will + influence the character of his stock, without his having had any + intention to modify the breed or form a new strain.</p> + + <p>Unconscious selection in the strictest sense of the word, that is, the + saving of the more useful animals and the neglect or slaughter of the + less useful, without any thought of the future, must have gone on + occasionally from the remotest period and amongst the most barbarous + nations. Savages often suffer from famines, and are sometimes expelled by + war from their own homes. In such cases it can hardly be doubted that + they would save their most useful animals. When the Fuegians <!-- Page + 215 --><span class="pagenum"><a name="page215"></a>{215}</span>are hard + pressed by want, they kill their old women for food rather than their + dogs; for, as we were assured, "old women no use—dogs catch + otters." The same sound sense would surely lead them to preserve their + more useful dogs when still harder pressed by famine. Mr. Oldfield, who + has seen so much of the aborigines of Australia, informs me that "they + are all very glad to get a European kangaroo dog, and several instances + have been known of the father killing his own infant that the mother + might suckle the much-prized puppy." Different kinds of dogs would be + useful to the Australian for hunting opossums and kangaroos, and to the + Fuegian for catching fish and otters; and the occasional preservation in + the two countries of the most useful animals would ultimately lead to the + formation of two widely distinct breeds.</p> + +<hr class="short" /> + + <p>With plants, from the earliest dawn of civilisation, the best variety + which at each period was known would generally have been cultivated and + its seeds occasionally sown; so that there will have been some selection + from an extremely remote period, but without any prefixed standard of + excellence or thought of the future. We at the present day profit by a + course of selection occasionally and unconsciously carried on during + thousands of years. This is proved in an interesting manner by Oswald + Heer's researches on the lake-inhabitants of Switzerland, as given in a + former chapter; for he shows that the grain and seed of our present + varieties of wheat, barley, oats, peas, beans, lentils, and poppy, exceed + in size those which were cultivated in Switzerland during the Neolithic + and Bronze periods. These ancient people, during the Neolithic period, + possessed also a crab considerably larger than that now growing wild on + the Jura.<a name="NtA_522" href="#Nt_522"><sup>[522]</sup></a> The pears + described by Pliny were evidently extremely inferior in quality to our + present pears. We can realise the effects of long-continued selection and + cultivation in another way, for would any one in his senses expect to + raise a first-rate apple from the seed of a truly wild crab, or a + luscious melting pear from the wild pear? Alphonse De Candolle informs me + that he has lately seen on an ancient mosaic at Rome a representation of + <!-- Page 216 --><span class="pagenum"><a + name="page216"></a>{216}</span>the melon; and as the Romans, who were + such gourmands, are silent on this fruit, he infers that the melon has + been greatly ameliorated since the classical period.</p> + + <p>Coming to later times, Buffon,<a name="NtA_523" + href="#Nt_523"><sup>[523]</sup></a> on comparing the flowers, fruit, and + vegetables which were then cultivated, with some excellent drawings made + a hundred and fifty years previously, was struck with surprise at the + great improvement which had been effected; and remarks that these ancient + flowers and vegetables would now be rejected, not only by a florist but + by a village gardener. Since the time of Buffon the work of improvement + has steadily and rapidly gone on. Every florist who compares our present + flowers with those figured in books published not long since, is + astonished at the change. A well-known amateur,<a name="NtA_524" + href="#Nt_524"><sup>[524]</sup></a> in speaking of the varieties of + Pelargonium raised by Mr. Garth only twenty-two years before, remarks, + "what a rage they excited: surely we had attained perfection, it was + said; and now not one of the flowers of those days will be looked at. But + none the less is the debt of gratitude which we owe to those who saw what + was to be done, and did it." Mr. Paul, the well-known horticulturist, in + writing of the same flower,<a name="NtA_525" + href="#Nt_525"><sup>[525]</sup></a> says he remembers when young being + delighted with the portraits in Sweet's work; "but what are they in point + of beauty compared with the Pelargoniums of this day? Here again nature + did not advance by leaps; the improvement was gradual, and, if we had + neglected those very gradual advances, we must have foregone the present + grand results." How well this practical horticulturist appreciates and + illustrates the gradual and accumulative force of selection! The Dahlia + has advanced in beauty in a like manner; the line of improvement being + guided by fashion, and by the successive modifications which the flower + slowly underwent.<a name="NtA_526" href="#Nt_526"><sup>[526]</sup></a> A + steady and gradual change has been noticed in many other flowers: thus an + old florist,<a name="NtA_527" href="#Nt_527"><sup>[527]</sup></a> after + describing the leading varieties of the Pink which were grown in 1813, + adds, "the pinks of those days would now be scarcely grown as + border-flowers." The improvement of <!-- Page 217 --><span + class="pagenum"><a name="page217"></a>{217}</span>so many flowers and the + number of the varieties which have been raised is all the more striking + when we hear that the earliest known flower-garden in Europe, namely at + Padua, dates only from the year 1545.<a name="NtA_528" + href="#Nt_528"><sup>[528]</sup></a></p> + +<hr class="short" /> + + <p><i>Effects of Selection, as shown by the parts most valued by man + presenting the greatest amount of Difference.</i>—The power of + long-continued selection, whether methodical or unconscious, or both + combined, is well shown in a general way, namely, by the comparison of + the differences between the varieties of distinct species, which are + valued for different parts, such as for the leaves, or stems, or tubers, + the seed, or fruit, or flowers. Whatever part man values most, that part + will be found to present the greatest amount of difference. With trees + cultivated for their fruit, Sageret remarks that the fruit is larger than + in the parent-species, whilst with those cultivated for the seed, as with + nuts, walnuts, almonds, chesnuts, &c., it is the seed itself which is + larger; and he accounts for this fact by the fruit in the one case, and + by the seed in the other, having been carefully attended to and selected + during many ages. Gallesio has made the same observation. Godron insists + on the diversity of the tuber in the potato, of the bulb in the onion, + and of the fruit in the melon; and on the close similarity in these same + plants of the other parts.<a name="NtA_529" + href="#Nt_529"><sup>[529]</sup></a></p> + + <p>In order to judge how far my own impression on this subject was + correct, I cultivated numerous varieties of the same species close to + each other. The comparison of the amount of difference between widely + different organs is necessarily vague; I will therefore give the results + in only a few cases. We have previously seen in the ninth chapter how + greatly the varieties of the cabbage differ in their foliage and stems, + which are the selected parts, and how closely they resembled each other + in their flowers, capsules, and seeds. In seven varieties of the radish, + the roots differed greatly in colour and shape, but no difference <!-- + Page 218 --><span class="pagenum"><a + name="page218"></a>{218}</span>whatever could be detected in their + foliage, flowers, or seeds. Now what a contrast is presented, if we + compare the flowers of the varieties of these two plants with those of + any species cultivated in our flower-gardens for ornament; or if we + compare their seeds with those of the varieties of maize, peas, beans, + &c., which are valued and cultivated for their seeds. In the ninth + chapter it was shown that the varieties of the pea differ but little + except in the tallness of the plant, moderately in the shape of the pod, + and greatly in the pea itself, and these are all selected points. The + varieties, however, of the <i>Pois sans parchemin</i> differ much more in + their pods, and these are eaten and valued. I cultivated twelve varieties + of the common bean; one alone, the Dwarf Fan, differed considerably in + general appearance; two differed in the colour of their flowers, one + being an albino, and the other being wholly instead of partially purple; + several differed considerably in the shape and size of the pod, but far + more in the bean itself, and this is the valued and selected part. + Toker's bean, for instance, is twice-and-a-half as long and broad as the + horse-bean, and is much thinner and of a different shape.</p> + + <p>The varieties of the gooseberry, as formerly described, differ much in + their fruit, but hardly perceptibly in their flowers or organs of + vegetation. With the plum, the differences likewise appear to be greater + in the fruit than in the flowers or leaves. On the other hand, the seed + of the strawberry, which corresponds with the fruit of the plum, differs + hardly at all; whilst every one knows how greatly the fruit—that + is, the enlarged receptacle—differs in the several varieties. In + apples, pears, and peaches the flowers and leaves differ considerably, + but not, as far as I can judge, in proportion with the fruit. The Chinese + double-flowering peaches, on the other hand, show that varieties of this + tree have been formed, which differ more in the flower than in fruit. If, + as is highly probable, the peach is the modified descendant of the + almond, a surprising amount of change has been effected in the same + species, in the fleshy covering of the former and in the kernels of the + latter.</p> + + <p>When parts stand in such close relation to each other as the fleshy + covering of the fruit (whatever its homological nature may be) and the + seed, when one part is modified, so generally is the other, but by no + means necessarily in the same degree. With <!-- Page 219 --><span + class="pagenum"><a name="page219"></a>{219}</span>the plum-tree, for + instance, some varieties produce plums which are nearly alike, but + include stones extremely dissimilar in shape; whilst conversely other + varieties produce dissimilar fruit with barely distinguishable stones; + and generally the stones, though they have never been subjected to + selection, differ greatly in the several varieties of the plum. In other + cases organs which are not manifestly related, through some unknown bond + vary together, and are consequently liable, without any intention on + man's part, to be simultaneously acted on by selection. Thus the + varieties of the stock (Matthiola) have been selected solely for the + beauty of their flowers, but the seeds differ greatly in colour and + somewhat in size. Varieties of the lettuce have been selected solely on + account of their leaves, yet produce seeds which likewise differ in + colour. Generally, through the law of correlation, when a variety differs + greatly from its fellow-varieties in any one character, it differs to a + certain extent in several other characters. I observed this fact when I + cultivated together many varieties of the same species, for I used first + to make a list of the varieties which differed most from each other in + their foliage and manner of growth, afterwards of those that differed + most in their flowers, then in their seed-capsules, and lastly in their + mature seed; and I found that the same names generally occurred in two, + three, or four of the successive lists. Nevertheless the greatest amount + of difference between the varieties was always exhibited, as far as I + could judge, by that part or organ for which the plant was + cultivated.</p> + + <p>When we bear in mind that each plant was at first cultivated because + useful to man, and that its variation was a subsequent, often a long + subsequent, event, we cannot explain the greater amount of diversity in + the valuable parts by supposing that species endowed with an especial + tendency to vary in any particular manner, were originally chosen. We + must attribute the result to the variations in these parts having been + successively preserved, and thus continually augmented; whilst other + variations, excepting such as inevitably appeared through correlation, + were neglected and lost. Hence we may infer that most plants might be + made, through long-continued selection, to yield races as different from + each other in any character <!-- Page 220 --><span class="pagenum"><a + name="page220"></a>{220}</span>as they now are in those parts for which + they are valued and cultivated.</p> + + <p>With animals we see something of the same kind; but they have not been + domesticated in sufficient number or yielded sufficient varieties for a + fair comparison. Sheep are valued for their wool, and the wool differs + much more in the several races than the hair in cattle. Neither sheep, + goats, European cattle, nor pigs are valued for their fleetness or + strength; and we do not possess breeds differing in these respects like + the race-horse and dray-horse. But fleetness and strength are valued in + camels and dogs; and we have with the former the swift dromedary and + heavy camel; with the latter the greyhound and mastiff. But dogs are + valued even in a higher degree for their mental qualities and senses; and + every one knows how greatly the races differ in these respects. On the + other hand, where the dog is valued solely to serve for food, as in the + Polynesian islands and China, it is described as an extremely stupid + animal.<a name="NtA_530" href="#Nt_530"><sup>[530]</sup></a> Blumenbach + remarks that "many dogs, such as the badger-dog, have a build so marked + and so appropriate for particular purposes, that I should find it very + difficult to persuade myself that this astonishing figure was an + accidental consequence of degeneration."<a name="NtA_531" + href="#Nt_531"><sup>[531]</sup></a> But had Blumenbach reflected on the + great principle of selection, he would not have used the term + degeneration, and he would not have been astonished that dogs and other + animals should become excellently adapted for the service of man.</p> + + <p>On the whole we may conclude that whatever part or character is most + valued—whether the leaves, stems, tubers, bulbs, flowers, fruit, or + seed of plants, or the size, strength, fleetness, hairy covering, or + intellect of animals—that character will almost invariably be found + to present the greatest amount of difference both in kind and degree. And + this result may be safely attributed to man having preserved during a + long course of generations the variations which were useful to him, and + neglected the others.</p> + + <p>I will conclude this chapter by some remarks on an important subject. + With animals such as the giraffe, of which <!-- Page 221 --><span + class="pagenum"><a name="page221"></a>{221}</span>the whole structure is + admirably co-ordinated for certain purposes, it has been supposed that + all the parts must have been simultaneously modified; and it has been + argued that, on the principle of natural selection, this is scarcely + possible. But in thus arguing, it has been tacitly assumed that the + variations must have been abrupt and great. No doubt, if the neck of a + ruminant were suddenly to become greatly elongated, the fore limbs and + back would have to be simultaneously strengthened and modified; but it + cannot be denied that an animal might have its neck, or head, or tongue, + or fore-limbs elongated a very little without any corresponding + modification in other parts of the body; and animals thus slightly + modified would, during a dearth, have a slight advantage, and be enabled + to browse on higher twigs, and thus survive. A few mouthfuls more or less + every day would make all the difference between life and death. By the + repetition of the same process, and by the occasional intercrossing of + the survivors, there would be some progress, slow and fluctuating though + it would be, towards the admirably co-ordinated structure of the giraffe. + If the short-faced tumbler-pigeon, with its small conical beak, globular + head, rounded body, short wings, and small feet—characters which + appear all in harmony—had been a natural species, its whole + structure would have been viewed as well fitted for its life; but in this + case we know that inexperienced breeders are urged to attend to point + after point, and not to attempt improving the whole structure at the same + time. Look at the greyhound, that perfect image of grace, symmetry, and + vigour; no natural species can boast of a more admirably co-ordinated + structure, with its tapering head, slim body, deep chest, tucked-up + abdomen, rat-like tail, and long muscular limbs, all adapted for extreme + fleetness, and for running down weak prey. Now, from what we see of the + variability of animals, and from what we know of the method which + different men follow in improving their stock—some chiefly + attending to one point, others to another point, others again correcting + defects by crosses, and so forth—we may feel assured that if we + could see the long line of ancestors of a first-rate greyhound, up to its + wild wolf-like progenitor, we should behold an infinite number of the + finest gradations, sometimes in one character and sometimes in another, + but all leading towards our <!-- Page 222 --><span class="pagenum"><a + name="page222"></a>{222}</span>present perfect type. By small and + doubtful steps such as these, nature, as we may confidently believe, has + progressed on her grand march of improvement and development.</p> + + <p>A similar line of reasoning is as applicable to separate organs as to + the whole organisation. A writer<a name="NtA_532" + href="#Nt_532"><sup>[532]</sup></a> has recently maintained that "it is + probably no exaggeration to suppose that, in order to improve such an + organ as the eye at all, it must be improved in ten different ways at + once. And the improbability of any complex organ being produced and + brought to perfection in any such way is an improbability of the same + kind and degree as that of producing a poem or a mathematical + demonstration by throwing letters at random on a table." If the eye were + abruptly and greatly modified, no doubt many parts would have to be + simultaneously altered, in order that the organ should remain + serviceable.</p> + + <p>But is this the case with smaller changes? There are persons who can + see distinctly only in a dull light, and this condition depends, I + believe, on the abnormal sensitiveness of the retina, and is known to be + inherited. Now, if a bird, for instance, received some great advantage + from seeing well in the twilight, all the individuals with the most + sensitive retina would succeed best and be the most likely to survive; + and why should not all those which happened to have the eye itself a + little larger, or the pupil capable of greater dilatation, be likewise + preserved, whether or not these modifications were strictly simultaneous? + These individuals would subsequently intercross and blend their + respective advantages. By such slight successive changes, the eye of a + diurnal bird would be brought into the condition of that of an owl, which + has often been advanced as an excellent instance of adaptation. + Short-sight, which is often inherited, permits a person to see distinctly + a minute object at so near a distance that it would be indistinct to + ordinary eyes; and here we have a capacity which might be serviceable + under certain conditions, abruptly gained. The Fuegians on board the <!-- + Page 223 --><span class="pagenum"><a + name="page223"></a>{223}</span>Beagle could certainly see distant objects + more distinctly than our sailors with all their long practice; I do not + know whether this depends on nervous sensitiveness or on the power of + adjustment in the focus; but this capacity for distant vision might, it + is probable, be slightly augmented by successive modifications of either + kind. Amphibious animals, which are enabled to see both in the water and + in the air, require and possess, as M. Plateau has shown,<a + name="NtA_533" href="#Nt_533"><sup>[533]</sup></a> eyes constructed on + the following plan: "the cornea is always flat, or at least much + flattened in front of the crystalline and over a space equal to the + diameter of that lens, whilst the lateral portions may be much curved." + The crystalline is very nearly a sphere, and the humours have nearly the + same density as water. Now, as a terrestrial animal slowly became more + and more aquatic in its habits, very slight changes, first in the + curvature of the cornea or crystalline, and then in the density of the + humours, or conversely, might successively occur, and would be + advantageous to the animal whilst under water, without serious detriment + to its power of vision in the air. It is of course impossible to + conjecture by what steps the fundamental structure of the eye in the + Vertebrata was originally acquired, for we know absolutely nothing about + this organ in the first progenitors of the class. With respect to the + lowest animals in the scale, the transitional states through which the + eye at first probably passed, can by the aid of analogy be indicated, as + I have attempted to show in my 'Origin of Species.'<a name="NtA_534" + href="#Nt_534"><sup>[534]</sup></a></p> + +<hr class="full" /> + +<p><!-- Page 224 --><span class="pagenum"><a name="page224"></a>{224}</span></p> + +<h3>CHAPTER XXI.</h3> + +<p class="cenhead">SELECTION, <i>continued</i>.</p> + +<blockquote class="b1n"> + + <p><span class="scac">NATURAL SELECTION AS AFFECTING DOMESTIC + PRODUCTIONS</span>—<span class="scac">CHARACTERS WHICH APPEAR OF + TRIFLING VALUE OFTEN OF REAL IMPORTANCE</span>—<span + class="scac">CIRCUMSTANCES FAVOURABLE TO SELECTION BY + MAN</span>—<span class="scac">FACILITY IN PREVENTING CROSSES, AND + THE NATURE OF THE CONDITIONS</span>—<span class="scac">CLOSE + ATTENTION AND PERSEVERANCE INDISPENSABLE</span>—<span + class="scac">THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS ESPECIALLY + FAVOURABLE</span>—<span class="scac">WHEN NO SELECTION IS APPLIED, + DISTINCT RACES ARE NOT FORMED</span>—<span class="scac">HIGHLY-BRED + ANIMALS LIABLE TO DEGENERATION</span>—<span class="scac">TENDENCY + IN MAN TO CARRY THE SELECTION OF EACH CHARACTER TO AN EXTREME POINT, + LEADING TO DIVERGENCE OF CHARACTER, RARELY TO + CONVERGENCE</span>—<span class="scac">CHARACTERS CONTINUING TO VARY + IN THE SAME DIRECTION IN WHICH THEY HAVE ALREADY + VARIED</span>—<span class="scac">DIVERGENCE OF CHARACTER, WITH THE + EXTINCTION OF INTERMEDIATE VARIETIES, LEADS TO DISTINCTNESS IN OUR + DOMESTIC RACES</span>—<span class="scac">LIMIT TO THE POWER OF + SELECTION</span>—<span class="scac">LAPSE OF TIME + IMPORTANT</span>—<span class="scac">MANNER IN WHICH DOMESTIC RACES + HAVE ORIGINATED</span>—<span class="scac">SUMMARY.</span></p> + +</blockquote> + + <p><i>Natural Selection, or the Survival of the Fittest, as affecting + domestic productions.</i>—We know little on this head. But as + animals kept by savages have to provide their own food, either entirely + or to a large extent, throughout the year, it can hardly be doubted that, + in different countries, varieties differing in constitution and in + various characters would succeed best, and so be naturally selected. + Hence perhaps it is that the few domesticated animals kept by savages + partake, as has been remarked by more than one writer, of the wild + appearance of their masters, and likewise resemble natural species. Even + in long-civilised countries, at least in the wilder parts, natural + selection must act on our domestic races. It is obvious that varieties, + having very different habits, constitution, and structure, would succeed + best on mountains and on rich lowland pastures. For example, the improved + Leicester sheep were formerly taken to the Lammermuir Hills; but an + intelligent sheep-master reported that "our coarse lean pastures were + unequal to the task of supporting such heavy-bodied sheep; and they + gradually dwindled away into less and less bulk: <!-- Page 225 --><span + class="pagenum"><a name="page225"></a>{225}</span>each generation was + inferior to the preceding one; and when the spring was severe, seldom + more than two-thirds of the lambs survived the ravages of the storms."<a + name="NtA_535" href="#Nt_535"><sup>[535]</sup></a> So with the mountain + cattle of North Wales and the Hebrides, it has been found that they could + not withstand being crossed with the larger and more delicate lowland + breeds. Two French naturalists, in describing the horses of Circassia, + remark that, subjected as they are to extreme vicissitudes of climate, + having to search for scanty pasture, and exposed to constant danger from + wolves, the strongest and most vigorous alone survive.<a name="NtA_536" + href="#Nt_536"><sup>[536]</sup></a></p> + + <p>Every one must have been struck with the surpassing grace, strength, + and vigour of the Game-cock, with its bold and confident air, its long, + yet firm neck, compact body, powerful and closely pressed wings, muscular + thighs, strong beak massive at the base, dense and sharp spurs set low on + the legs for delivering the fatal blow, and its compact, glossy, and + mail-like plumage serving as a defence. Now the English game-cock has not + only been improved during many years by man's careful selection, but in + addition, as Mr. Tegetmeier has remarked,<a name="NtA_537" + href="#Nt_537"><sup>[537]</sup></a> by a kind of natural selection, for + the strongest, most active and courageous birds have stricken down their + antagonists in the cockpit, generation after generation, and have + subsequently served as the progenitors of their kind.</p> + + <p>In Great Britain, in former times, almost every district had its own + breed of cattle and sheep; "they were indigenous to the soil, climate, + and pasturage of the locality on which they grazed: they seemed to have + been formed for it and by it."<a name="NtA_538" + href="#Nt_538"><sup>[538]</sup></a> But in this case we are quite unable + to disentangle the effects of the direct action of the conditions of + life,—of use or habit—of natural selection—and of that + kind of selection which we have seen is occasionally and unconsciously + followed by man even during the rudest periods of history.</p> + + <p>Let us now look to the action of natural selection on special + characters. Although nature is difficult to resist, yet man often strives + against her power, and sometimes, as we shall see, with <!-- Page 226 + --><span class="pagenum"><a name="page226"></a>{226}</span>success. From + the facts to be given, it will also be seen that natural selection would + powerfully affect many of our domestic productions if left unprotected. + This is a point of much interest, for we thus learn that differences + apparently of very slight importance would certainly determine the + survival of a form when forced to struggle for its own existence. It may + have occurred to some naturalists, as it formerly did to me, that, though + selection acting under natural conditions would determine the structure + of all important organs, yet that it could not affect characters which + are esteemed by us of little importance; but this is an error to which we + are eminently liable, from our ignorance of what characters are of real + value to each living creature.</p> + + <p>When man attempts to breed an animal with some serious defect in + structure, or in the mutual relation of parts, he will either partially + or completely fail, or encounter much difficulty; and this is in fact a + form of natural selection. We have seen that the attempt was once made in + Yorkshire to breed cattle with enormous buttocks, but the cows perished + so often in bringing forth their calves, that the attempt had to be given + up. In rearing short-faced tumblers, Mr. Eaton says,<a name="NtA_539" + href="#Nt_539"><sup>[539]</sup></a> "I am convinced that better head and + beak birds have perished in the shell than ever were hatched; the reason + being that the amazingly short-faced bird cannot reach and break the + shell with its beak, and so perishes." Here is a more curious case, in + which natural selection comes into play only at long intervals of time: + during ordinary seasons the Niata cattle can graze as well as others, but + occasionally, as from 1827 to 1830, the plains of La Plata suffer from + long-continued droughts and the pasture is burnt up; at such times common + cattle and horses perish by the thousand, but many survive by browsing on + twigs, reeds, &c.; this the Niata cattle cannot so well effect from + their upturned jaws and the shape of their lips; consequently, if not + attended to, they perish before the other cattle. In Colombia, according + to Roulin, there is a breed of nearly hairless cattle, called Pelones; + these succeed in their native hot district, but are found too tender for + the Cordillera; in this case, natural selection <!-- Page 227 --><span + class="pagenum"><a name="page227"></a>{227}</span>determines only the + range of the variety. It is obvious that a host of artificial races could + never survive in a state of nature;—such as Italian + greyhounds,—hairless and almost toothless Turkish + dogs,—fantail pigeons, which cannot fly well against a strong + wind,—barbs with their vision impeded by their + eye-wattle,—Polish fowls with their vision impeded by their great + topknots,—hornless bulls and rams which consequently cannot cope + with other males, and thus have a poor chance of leaving + offspring,—seedless plants, and many other such cases.</p> + + <p>Colour is generally esteemed by the systematic naturalist as + unimportant: let us, therefore, see how far it indirectly affects our + domestic productions, and how far it would affect them if they were left + exposed to the full force of natural selection. In a future chapter I + shall have to show that constitutional peculiarities of the strangest + kind, entailing liability to the action of certain poisons, are + correlated with the colour of the skin. I will here give a single case, + on the high authority of Professor Wyman; he informs me that, being + surprised at all the pigs in a part of Virginia being black, he made + inquiries, and ascertained that these animals feed on the roots of the + <i>Lachnanthes tinctoria</i>, which colours their bones pink, and, + excepting in the case of the black varieties, causes the hoofs to drop + off. Hence, as one of the squatters remarked, "we select the black + members of the litter for raising, as they alone have a good chance of + living." So that here we have artificial and natural selection working + hand in hand. I may add that in the Tarentino the inhabitants keep black + sheep alone, because the <i>Hypericum crispum</i> abounds there; and this + plant does not injure black sheep, but kills the white ones in about a + fortnight's time.<a name="NtA_540" + href="#Nt_540"><sup>[540]</sup></a></p> + + <p>Complexion, and liability to certain diseases, are believed to run + together in man and the lower animals. Thus white terriers suffer more + than terriers of any other colour from the fatal Distemper.<a + name="NtA_541" href="#Nt_541"><sup>[541]</sup></a> In North America + plum-trees are liable to a disease which Downing<a name="NtA_542" + href="#Nt_542"><sup>[542]</sup></a> believes is not caused by insects; + the kinds bearing purple fruit are most affected, "and we have never + known the green or yellow fruited varieties infected <!-- Page 228 + --><span class="pagenum"><a name="page228"></a>{228}</span>until the + other sorts had first become filled with the knots." On the other hand, + peaches in North America suffer much from a disease called the + <i>yellows</i>, which seems to be peculiar to that continent, and "more + than nine-tenths of the victims, when the disease first appeared, were + the yellow-fleshed peaches. The white-fleshed kinds are much more rarely + attacked; in some parts of the country never." In Mauritius, the white + sugar-canes have of late years been so severely attacked by a disease, + that many planters have been compelled to give up growing this variety + (although fresh plants were imported from China for trial), and cultivate + only red canes.<a name="NtA_543" href="#Nt_543"><sup>[543]</sup></a> Now, + if these plants had been forced to struggle with other competing plants + and enemies, there cannot be a doubt that the colour of the flesh or skin + of the fruit, unimportant as these characters are considered, would have + rigorously determined their existence.</p> + + <p>Liability to the attacks of parasites is also connected with colour. + It appears that white chickens are certainly more subject than + dark-coloured chickens to the <i>gapes</i>, which is caused by a + parasitic worm in the trachea.<a name="NtA_544" + href="#Nt_544"><sup>[544]</sup></a> On the other hand, experience has + shown that in France the caterpillars which produce white cocoons resist + the deadly fungus better than those producing yellow cocoons.<a + name="NtA_545" href="#Nt_545"><sup>[545]</sup></a> Analogous facts have + been observed with plants: a new and beautiful white onion, imported from + France, though planted close to other kinds, was alone attacked by a + parasitic fungus.<a name="NtA_546" href="#Nt_546"><sup>[546]</sup></a> + White verbenas are especially liable to mildew.<a name="NtA_547" + href="#Nt_547"><sup>[547]</sup></a> Near Malaga, during an early period + of the vine-disease, the green sorts suffered most; "and red and black + grapes, even when interwoven with the sick plants, suffered not at all." + In France whole groups of varieties were comparatively free, and others, + such as the Chasselas, did not afford a single fortunate exception; but I + do not know whether any correlation between colour and liability to + disease was here observed.<a name="NtA_548" + href="#Nt_548"><sup>[548]</sup></a> In a former chapter it was shown how + curiously liable one variety of the strawberry is to mildew.</p> + +<p><!-- Page 229 --><span class="pagenum"><a name="page229"></a>{229}</span></p> + + <p>It is certain that insects regulate in many cases the range and even + the existence of the higher animals, whilst living under their natural + conditions. Under domestication light-coloured animals suffer most: in + Thuringia<a name="NtA_549" href="#Nt_549"><sup>[549]</sup></a> the + inhabitants do not like grey, white, or pale cattle, because they are + much more troubled by various kinds of flies than the brown, red, or + black cattle. An Albino negro, it has been remarked,<a name="NtA_550" + href="#Nt_550"><sup>[550]</sup></a> was peculiarly sensitive to the bites + of insects. In the West Indies<a name="NtA_551" + href="#Nt_551"><sup>[551]</sup></a> it is said that "the only horned + cattle fit for work are those which have a good deal of black in them. + The white are terribly tormented by the insects; and they are weak and + sluggish in proportion to the white."</p> + + <p>In Devonshire there is a prejudice against white pigs, because it is + believed that the sun blisters them when turned out;<a name="NtA_552" + href="#Nt_552"><sup>[552]</sup></a> and I knew a man who would not keep + white pigs in Kent, for the same reason. The scorching of flowers by the + sun seems likewise to depend much on colour; thus, dark pelargoniums + suffer most; and from various accounts it is clear that the cloth-of-gold + variety will not withstand a degree of exposure to sunshine which other + varieties enjoy. Another amateur asserts that not only all dark-coloured + verbenas, but likewise scarlets, suffer from the sun; "the paler kinds + stand better, and pale blue is perhaps the best of all." So again with + the heartsease (<i>Viola tricolor</i>); hot weather suits the blotched + sorts, whilst it destroys the beautiful markings of some other kinds.<a + name="NtA_553" href="#Nt_553"><sup>[553]</sup></a> During one extremely + cold season in Holland all red-flowered hyacinths were observed to be + very inferior in quality. It is believed by many agriculturists that red + wheat is hardier in northern climates than white wheat.<a name="NtA_554" + href="#Nt_554"><sup>[554]</sup></a></p> + + <p>With animals, white varieties from being conspicuous are the most + liable to be attacked by beasts and birds of prey. In parts of France and + Germany where hawks abound, persons are advised not to keep white + pigeons; for, as Parmentier says, "it <!-- Page 230 --><span + class="pagenum"><a name="page230"></a>{230}</span>is certain that in a + flock the white always first fall victims to the kite." In Belgium, where + so many societies have been established for the flight of + carrier-pigeons, white is the one colour which for the same reason is + disliked.<a name="NtA_555" href="#Nt_555"><sup>[555]</sup></a> On the + other hand, it is said that the sea-eagle (<i>Falco ossifragus</i>, + Linn.) on the west coast of Ireland picks out the black fowls, so that + "the villagers avoid as much as possible rearing birds of that colour." + M. Daudin,<a name="NtA_556" href="#Nt_556"><sup>[556]</sup></a> speaking + of white rabbits kept in warrens in Russia, remarks that their colour is + a great disadvantage, as they are thus more exposed to attack, and can be + seen during bright nights from a distance. A gentleman in Kent, who + failed to stock his woods with a nearly white and hardy kind of rabbit, + accounted in the same manner for their early disappearance. Any one who + will watch a white cat prowling after her prey will soon perceive under + what a disadvantage she lies.</p> + + <p>The white Tartarian cherry, "owing either to its colour being so much + like that of the leaves, or to the fruit always appearing from a distance + unripe," is not so readily attacked by birds as other sorts. The + yellow-fruited raspberry, which generally comes nearly true by seed, "is + very little molested by birds, who evidently are not fond of it; so that + nets may be dispensed with in places where nothing else will protect the + red fruit."<a name="NtA_557" href="#Nt_557"><sup>[557]</sup></a> This + immunity, though a benefit to the gardener, would be a disadvantage in a + state of nature both to the cherry and raspberry, as their dissemination + depends on birds. I noticed during several winters that some trees of the + yellow-berried holly, which were raised from seed from a wild tree found + by my father, remained covered with fruit, whilst not a scarlet berry + could be seen on the adjoining trees of the common kind. A friend informs + me that a mountain-ash (<i>Pyrus aucuparia</i>) growing in his garden + bears berries which, though not differently coloured, are always devoured + by birds before those on the other trees. This variety of the + mountain-ash would thus be more freely disseminated, and the + yellow-berried variety of the holly less freely, than the common + varieties of these two trees.</p> + +<p><!-- Page 231 --><span class="pagenum"><a name="page231"></a>{231}</span></p> + + <p>Independently of colour, other trifling differences are sometimes + found to be of importance to plants under cultivation, and would be of + paramount importance if they had to fight their own battle and to + struggle with many competitors. The thin-shelled peas, called <i>pois + sans parchemin</i>, are attacked by birds<a name="NtA_558" + href="#Nt_558"><sup>[558]</sup></a> much more than common peas. On the + other hand, the purple-podded pea, which has a hard shell, escaped the + attacks of tomtits (<i>Parus major</i>) in my garden far better than any + other kind. The thin-shelled walnut likewise suffers greatly from the + tomtit.<a name="NtA_559" href="#Nt_559"><sup>[559]</sup></a> These same + birds have been observed to pass over and thus favour the filbert, + destroying only the other kinds of nuts which grew in the same orchard.<a + name="NtA_560" href="#Nt_560"><sup>[560]</sup></a></p> + + <p>Certain varieties of the pear have soft bark, and these suffer + severely from boring wood-beetles; whilst other varieties are known to + resist their attacks much better.<a name="NtA_561" + href="#Nt_561"><sup>[561]</sup></a> In North America the smoothness, or + absence of down on the fruit, makes a great difference in the attacks of + the weevil, "which is the uncompromising foe of all smooth stone-fruits;" + and the cultivator "has the frequent mortification of seeing nearly all, + or indeed often the whole crop, fall from the trees when half or + two-thirds grown." Hence the nectarine suffers more than the peach. A + particular variety of the Morello cherry, raised in North America, is + without any assignable cause more liable to be injured by this same + insect than other cherry-trees.<a name="NtA_562" + href="#Nt_562"><sup>[562]</sup></a> From some unknown cause, the Winter + Majetin apple enjoys the great advantage of not being infested by the + coccus. On the other hand, a particular case has been recorded in which + aphides confined themselves to the Winter Nelis pear, and touched no + other kind in an extensive orchard.<a name="NtA_563" + href="#Nt_563"><sup>[563]</sup></a> The existence of minute glands on the + leaves of peaches, nectarines, and apricots, would not be esteemed by + botanists as a character of the least importance, for they are present or + absent in closely related sub-varieties, descended from the same + parent-tree; yet there is good evidence<a name="NtA_564" + href="#Nt_564"><sup>[564]</sup></a> that the <!-- Page 232 --><span + class="pagenum"><a name="page232"></a>{232}</span>absence of glands leads + to mildew, which is highly injurious to these trees.</p> + + <p>A difference either in flavour or in the amount of nutriment in + certain varieties causes them to be more eagerly attacked by various + enemies than other varieties of the same species. Bullfinches + (<i>Pyrrhula vulgaris</i>) injure our fruit-trees by devouring the + flower-buds, and a pair of these birds have been seen "to denude a large + plum-tree in a couple of days of almost every bud;" but certain + varieties<a name="NtA_565" href="#Nt_565"><sup>[565]</sup></a> of the + apple and thorn (<i>Cratægus <span class="correction" title="Original reads `oxycantha', corrected by errata, page viii." + >oxyacantha</span></i>) are more especially liable to be attacked. A + striking instance of this was observed in Mr. Rivers's garden, in which + two rows of a particular variety of plum<a name="NtA_566" + href="#Nt_566"><sup>[566]</sup></a> had to be carefully protected, as + they were usually stripped of all their buds during the winter, whilst + other sorts growing near them escaped. The root (or enlarged stem) of + Laing's Swedish turnip is preferred by hares, and therefore suffers more + than other varieties. Hares and rabbits eat down common rye before St. + John's-day-rye, when both grow together.<a name="NtA_567" + href="#Nt_567"><sup>[567]</sup></a> In the South of France, when an + orchard of almond-trees is formed, the nuts of the bitter variety are + sown, "in order that they may not be devoured by field-mice;"<a + name="NtA_568" href="#Nt_568"><sup>[568]</sup></a> so we see the use of + the bitter principle in almonds.</p> + + <p>Other slight differences, which would be thought quite unimportant, + are no doubt sometimes of great service both to plants and animals. The + Whitesmith's gooseberry, as formerly stated, produces its leaves later + than other varieties, and, as the flowers are thus left unprotected, the + fruit often fails. In one variety of the cherry, according to Mr. + Rivers,<a name="NtA_569" href="#Nt_569"><sup>[569]</sup></a> the petals + are much curled backwards, and in consequence of this the stigmas were + observed to be killed by a severe frost; whilst at the same time, in + another variety with incurved petals, the stigmas were not in the least + injured. The straw of the Fenton wheat is remarkably unequal in height; + and a competent observer believes that this variety is highly productive, + partly because the ears, from being distributed at various heights above + the ground, <!-- Page 233 --><span class="pagenum"><a + name="page233"></a>{233}</span>are less crowded together. The same + observer maintains that in the upright varieties the divergent awns are + serviceable by breaking the shocks when the ears are dashed together by + the wind.<a name="NtA_570" href="#Nt_570"><sup>[570]</sup></a> If several + varieties of a plant are grown together, and the seed is indiscriminately + harvested, it is clear that the hardier and more productive kinds will, + by a sort of natural selection, gradually prevail over the others; this + takes place, as Colonel Le Couteur believes,<a name="NtA_571" + href="#Nt_571"><sup>[571]</sup></a> in our wheat-fields, for, as formerly + shown, no variety is quite uniform in character. The same thing, as I am + assured by nurserymen, would take place in our flower-gardens, if the + seed of the different varieties were not separately saved. When the eggs + of the wild and tame duck are hatched together, the young wild ducks + almost invariably perish, from being of smaller size and not getting + their fair share of food.<a name="NtA_572" + href="#Nt_572"><sup>[572]</sup></a></p> + + <p>Facts in sufficient number have now been given showing that natural + selection often checks, but occasionally favours, man's power of + selection. These facts teach us, in addition, a valuable lesson, namely, + that we ought to be extremely cautious in judging what characters are of + importance in a state of nature to animals and plants, which have to + struggle from the hour of their birth to that of their death for + existence,—their existence depending on conditions, about which we + are profoundly ignorant.</p> + +<p class="cenhead"><i>Circumstances favourable to Selection by Man.</i></p> + + <p>The possibility of selection rests on variability, and this, as we + shall see in the following chapters, mainly depends on changed conditions + of life, but is governed by infinitely complex, and, to a great extent, + unknown laws. Domestication, even when long continued, occasionally + causes but a small amount of variability, as in the case of the goose and + turkey. The slight differences, however, which characterise each + individual animal and plant would in most, probably in all cases, suffice + for the production of distinct races through careful and prolonged + selection. We see what selection, though acting on mere individual + differences, can effect when families of cattle, sheep, <!-- Page 234 + --><span class="pagenum"><a name="page234"></a>{234}</span>pigeons, + &c., of the same race, have been separately bred during a number of + years by different men without any wish on their part to modify the + breed. We see the same fact in the difference between hounds bred for + hunting in different districts,<a name="NtA_573" + href="#Nt_573"><sup>[573]</sup></a> and in many other such cases.</p> + + <p>In order that selection should produce any result, it is manifest that + the crossing of distinct races must be prevented; hence facility in + pairing, as with the pigeon, is highly favourable for the work; and + difficulty in pairing, as with cats, prevents the formation of distinct + breeds. On nearly the same principle the cattle of the small island of + Jersey have been improved in their milking qualities "with a rapidity + that could not have been obtained in a widely extended country like + France."<a name="NtA_574" href="#Nt_574"><sup>[574]</sup></a> Although + free crossing is a danger on the one side which every one can see, too + close interbreeding is a hidden danger on the other side. Unfavourable + conditions of life overrule the power of selection. Our improved heavy + breeds of cattle and sheep could not have been formed on mountainous + pastures; nor could dray-horses have been raised on a barren and + inhospitable land, such as the Falkland islands, where even the light + horses of La Plata rapidly decrease in size. Nor could the wool of sheep + have been much increased in length within the Tropics; yet selection has + kept Merino sheep nearly true under diversified and unfavourable + conditions of life. The power of selection is so great, that breeds of + the dog, sheep, and poultry, of the largest and least size, long and + short beaked pigeons, and other breeds with opposite characters, have had + their characteristic qualities augmented, though treated in every way + alike, being exposed to the same climate and fed on the same food. + Selection, however, is either checked or favoured by the effects of use + or habit. Our wonderfully-improved pigs could never have been formed if + they had been forced to search for their own food; the English racehorse + and greyhound could not have been improved up to their present high + standard of excellence without constant training.</p> + + <p>As conspicuous deviations of structure occur rarely, the improvement + of each breed is generally the result, as already <!-- Page 235 --><span + class="pagenum"><a name="page235"></a>{235}</span>remarked, of the + selection of slight individual differences. Hence the closest attention, + the sharpest powers of observation, and indomitable perseverance, are + indispensable. It is, also, highly important that many individuals of the + breed which is to be improved should be raised; for thus there will be a + better chance of the appearance of variations in the right direction, and + individuals varying in an unfavourable manner may be freely rejected or + destroyed. But that a large number of individuals should be raised, it is + necessary that the conditions of life should favour the propagation of + the species. Had the peacock been bred as easily as the fowl, we should + probably ere this have had many distinct races. We see the importance of + a large number of plants, from the fact of nursery gardeners almost + always beating amateurs in the exhibition of new varieties. In 1845 it + was estimated<a name="NtA_575" href="#Nt_575"><sup>[575]</sup></a> that + between 4000 and 5000 pelargoniums were annually raised from seed in + England, yet a decidedly improved variety is rarely obtained. At Messrs. + Carter's grounds, in Essex, where such flowers as the Lobelia, Nemophila, + Mignonette, &c., are grown by the acre for seed, "scarcely a season + passes without some new kinds being raised, or some improvement affected + on old kinds."<a name="NtA_576" href="#Nt_576"><sup>[576]</sup></a> At + Kew, as Mr. Beaton remarks, where many seedlings of common plants are + raised, "you see new forms of Laburnums, Spiræas, and other shrubs."<a + name="NtA_577" href="#Nt_577"><sup>[577]</sup></a> So with animals: + Marshall,<a name="NtA_578" href="#Nt_578"><sup>[578]</sup></a> in + speaking of the sheep in one part of Yorkshire, remarks, "as they belong + to poor people, and are mostly in small lots, they never can be + improved." Lord Rivers, when asked how he succeeded in always having + first-rate greyhounds, answered, "I breed many, and hang many." This, as + another man remarks, "was the secret of his success; and the same will be + found in exhibiting fowls,—successful competitors breed largely, + and keep the best."<a name="NtA_579" + href="#Nt_579"><sup>[579]</sup></a></p> + + <p>It follows from this that the capacity of breeding at an early age and + at short successive intervals, as with pigeons, rabbits, &c., + facilitates selection; for the result is thus soon made visible, and + perseverance in the work is encouraged. It can hardly be <!-- Page 236 + --><span class="pagenum"><a name="page236"></a>{236}</span>accidental + that the great majority of the culinary and agricultural plants which + have yielded numerous races are annuals or biennials, which therefore are + capable of rapid propagation and thus of improvement. Sea-kale, + asparagus, common and Jerusalem artichokes, potatoes, and onions, alone + are perennials. Onions are propagated like annuals, and of the other + plants just specified, none, with the exception of the potato, have + yielded more than one or two varieties. No doubt fruit-trees, which + cannot be propagated quickly by seed, have yielded a host of varieties, + though not permanent races; but these, judging from pre-historic remains, + were produced at a later and more civilised epoch than the races of + culinary and agricultural plants.</p> + + <p>A species may be highly variable, but distinct races will not be + formed, if from any cause selection be not applied. The carp is highly + variable, but it would be extremely difficult to select slight variations + in fishes whilst living in their natural state, and distinct races have + not been formed;<a name="NtA_580" href="#Nt_580"><sup>[580]</sup></a> on + the other hand, a closely allied species, the gold-fish, from being + reared in glass or open vessels, and from having been carefully attended + to by the Chinese, has yielded many races. Neither the bee, which has + been semi-domesticated from an extremely remote period, nor the cochineal + insect, which was cultivated by the aboriginal Mexicans, has yielded + races; and it would be impossible to match the queen-bee with any + particular drone, and most difficult to match cochineal insects. + Silk-moths, on the other hand, have been subjected to rigorous selection, + and have produced a host of races. Cats, which from their nocturnal + habits cannot be selected for breeding, do not, as formerly remarked, + yield distinct races in the same country. The ass in England varies much + in colour and size; but it is an animal of little value, bred by poor + people; consequently there has been no selection, and distinct races have + not been formed. We must not attribute the inferiority of our asses to + climate, for in India they are of even smaller size than in Europe. But + when selection is brought to bear on the ass, all is changed. Near + Cordova, as I am informed (Feb. 1860) by Mr. W. E. Webb, C.E., they are + carefully bred, as much as 200<i>l.</i> having been paid for a stallion + ass, <!-- Page 237 --><span class="pagenum"><a + name="page237"></a>{237}</span>and they have been immensely improved. In + Kentucky, asses have been imported (for breeding mules) from Spain, + Malta, and France; these "seldom averaged more than fourteen hands high; + but the Kentuckians, by great care, have raised them up to fifteen hands, + and sometimes even to sixteen. The prices paid for these splendid + animals, for such they really are, will prove how much they are in + request. One male, of great celebrity, was sold for upwards of one + thousand pounds sterling." These choice asses are sent to cattle-shows, + one day being given to their exhibition.<a name="NtA_581" + href="#Nt_581"><sup>[581]</sup></a></p> + + <p>Analogous facts have been observed with plants: the nutmeg-tree in the + Malay archipelago is highly variable, but there has been no selection, + and there are no distinct races.<a name="NtA_582" + href="#Nt_582"><sup>[582]</sup></a> The common mignonette (<i>Reseda + odorata</i>), from bearing inconspicuous flowers, valued solely for their + fragrance, "remains in the same unimproved condition as when first + introduced."<a name="NtA_583" href="#Nt_583"><sup>[583]</sup></a> Our + common forest-trees are very variable, as may be seen in every extensive + nursery-ground; but as they are not valued like fruit-trees, and as they + seed late in life, no selection has been applied to them; consequently, + as Mr. Patrick Matthews remarks,<a name="NtA_584" + href="#Nt_584"><sup>[584]</sup></a> they have not yielded distinct races, + leafing at different periods, growing to different sizes, and producing + timber fit for different purposes. We have gained only some fanciful and + semi-monstrous varieties, which no doubt appeared suddenly as we now see + them.</p> + + <p>Some botanists have argued that plants cannot have so strong a + tendency to vary as is generally supposed, because many species long + grown in botanic gardens, or unintentionally cultivated year after year + mingled with our corn crops, have not produced distinct races; but this + is accounted for by slight variations not having been selected and + propagated. Let a plant which is now grown in a botanic garden, or any + common weed, be cultivated on a large scale, and let a sharp-sighted + gardener look out for each slight variety and sow the seed, and then, if + distinct races are not produced, the argument will be valid.</p> + +<p><!-- Page 238 --><span class="pagenum"><a name="page238"></a>{238}</span></p> + + <p>The importance of selection is likewise shown by considering special + characters. For instance, with most breeds of fowls the form of the comb + and the colour of the plumage have been attended to, and are eminently + characteristic of each race; but in Dorkings, fashion has never demanded + uniformity of comb or colour; and the utmost diversity in these respects + prevails. Rose-combs, double-combs, cup-combs, &c., and colours of + all kinds, may be seen in purely-bred and closely related Dorking fowls, + whilst other points, such as the general form of body, and the presence + of an additional toe, have been attended to, and are invariably present. + It has also been ascertained that colour can be fixed in this breed, as + well as in any other.<a name="NtA_585" + href="#Nt_585"><sup>[585]</sup></a></p> + +<hr class="short" /> + + <p>During the formation or improvement of a breed, its members will + always be found to vary much in those characters to which especial + attention is directed, and of which each slight improvement is eagerly + sought and selected. Thus with short-faced tumbler-pigeons, the shortness + of the beak, shape of head and plumage,—with carriers, the length + of the beak and wattle,—with fantails, the tail and + carriage,—with Spanish fowls, the white face and comb,—with + long-eared rabbits, the length of ear, are all points which are eminently + variable. So it is in every case, and the large price paid for first-rate + animals proves the difficulty of breeding them up to the highest standard + of excellence. This subject has been discussed by fanciers,<a + name="NtA_586" href="#Nt_586"><sup>[586]</sup></a> and the greater prizes + given for highly improved breeds, in comparison with those given for old + breeds which are not now undergoing rapid improvement, has been fully + justified. Nathusius makes<a name="NtA_587" + href="#Nt_587"><sup>[587]</sup></a> a similar remark when discussing the + less uniform character of improved Shorthorn cattle and of the English + horse, in comparison, for example, with the unennobled cattle of Hungary, + or with the horses of the Asiatic steppes. This want of uniformity in the + parts which at the time are undergoing selection, chiefly depends on the + strength of the principle of reversion but it likewise depends to a + certain extent on the continued <!-- Page 239 --><span class="pagenum"><a + name="page239"></a>{239}</span>variability of the parts which have + recently varied. That the same parts do continue varying in the same + manner we must admit, for, if it were not so, there could be no + improvement beyond an early standard of excellence, and we know that such + improvement is not only possible, but is of general occurrence.</p> + + <p>As a consequence of continued variability, and more especially of + reversion, all highly improved races, if neglected or not subjected to + incessant selection, soon degenerate. Youatt gives a curious instance of + this in some cattle formerly kept in Glamorganshire; but in this case the + cattle were not fed with sufficient care. Mr. Baker, in his memoir on the + Horse, sums up: "It must have been observed in the preceding pages that, + whenever there has been neglect, the breed has proportionally + deteriorated."<a name="NtA_588" href="#Nt_588"><sup>[588]</sup></a> If a + considerable number of improved cattle, sheep, or other animals of the + same race, were allowed to breed freely together, with no selection, but + with no change in their condition of life, there can be no doubt that + after a score or hundred generations they would be very far from + excellent of their kind; but, from what we see of the many common races + of dogs, cattle, fowls, pigeons, &c., which without any particular + care have long retained nearly the same character, we have no grounds for + believing that they would altogether depart from their type.</p> + + <p>It is a general belief amongst breeders that characters of all kinds + become fixed by long-continued inheritance. But I have attempted to show + in the fourteenth chapter that this belief apparently resolves itself + into the following proposition, namely, that all characters whatever, + whether recently acquired or ancient, tend to be transmitted, but that + those which have already long withstood all counteracting influences, + will, as a general rule, continue to withstand them, and consequently be + faithfully transmitted.</p> + +<p class="cenhead"><i>Tendency in Man to carry the practice of Selection to an extreme +point.</i></p> + + <p>It is an important principle that in the process of selection man + almost invariably wishes to go to an extreme point. Thus, in useful + qualities, there is no limit to his desire to breed certain <!-- Page 240 + --><span class="pagenum"><a name="page240"></a>{240}</span>horses and + dogs as fleet as possible, and others as strong as possible; certain + kinds of sheep for extreme fineness, and others for extreme length of + wool; and he wishes to produce fruit, grain, tubers, and other useful + parts of plants, as large and excellent as possible. With animals bred + for amusement, the same principle is even more powerful; for fashion, as + we see even in our dress, always runs to extremes. This view has been + expressly admitted by fanciers. Instances were given in the chapters on + the pigeon, but here is another: Mr. Eaton, after describing a + comparatively new variety, namely, the Archangel, remarks, "What fanciers + intend doing with this bird I am at a loss to know, whether they intend + to breed it down to the tumbler's head and beak, or carry it out to the + carrier's head and beak; leaving it as they found it, is not + progressing." Ferguson, speaking of fowls, says, "their peculiarities, + whatever they may be, must necessarily be fully developed: a little + peculiarity forms nought but ugliness, seeing it violates the existing + laws of symmetry." So Mr. Brent, in discussing the merits of the + sub-varieties of the Belgian canary-bird, remarks, "Fanciers always go to + extremes; they do not admire indefinite properties."<a name="NtA_589" + href="#Nt_589"><sup>[589]</sup></a></p> + + <p>This principle, which necessarily leads to divergence of character, + explains the present state of various domestic races. We can thus see how + it is that race-horses and dray-horses, greyhounds and mastiffs, which + are opposed to each other in every character,—how varieties so + distinct as Cochin-China fowls and bantams, or carrier-pigeons with very + long beaks, and tumblers with excessively short beaks, have been derived + from the same stock. As each breed is slowly improved, the inferior + varieties are first neglected and finally lost. In a few cases, by the + aid of old records, or from intermediate varieties still existing in + countries where other fashions have prevailed, we are enabled partially + to trace the graduated changes through which certain breeds have passed. + Selection, whether methodical or unconscious, always tending towards an + extreme point, together with the neglect and slow extinction of the + intermediate and less-valued forms, is the key which unlocks the mystery + how man has produced such wonderful results.</p> + +<p><!-- Page 241 --><span class="pagenum"><a name="page241"></a>{241}</span></p> + + <p>In a few instances selection, guided by utility for a single purpose, + has led to convergence of character. All the improved and different races + of the pig, as Nathusius has well shown,<a name="NtA_590" + href="#Nt_590"><sup>[590]</sup></a> closely approach each other in + character, in their shortened legs and muzzles, their almost hairless, + large, rounded bodies, and small tusks. We see some degree of convergence + in the similar outline of the body in well-bred cattle belonging to + distinct races.<a name="NtA_591" href="#Nt_591"><sup>[591]</sup></a> I + know of no other such cases.</p> + + <p>Continued divergence of character depends on, and is indeed a clear + proof, as previously remarked, of the same parts continuing to vary in + the same direction. The tendency to mere general variability or + plasticity of organisation can certainly be inherited, even from one + parent, as has been shown by Gärtner and Kölreuter, in the production of + varying hybrids from two species, of which one alone was variable. It is + in itself probable that, when an organ has varied in any manner, it will + again vary in the same manner, if the conditions which first caused the + being to vary remain, as far as can be judged, the same. This is either + tacitly or expressly admitted by all horticulturists: if a gardener + observes one or two additional petals in a flower, he feels confident + that in a few generations he will be able to raise a double flower, + crowded with petals. Some of the seedlings from the weeping Moccas oak + were so prostrate that they only crawled along the ground. A seedling + from the fastigate or upright Irish yew is described as differing greatly + from the parent-form "by the exaggeration of the fastigate habit of its + branches."<a name="NtA_592" href="#Nt_592"><sup>[592]</sup></a> Mr. + Sheriff, who has been more successful than any other man in raising new + kinds of wheat, remarks, "A good variety may safely be regarded as the + forerunner of a better one."<a name="NtA_593" + href="#Nt_593"><sup>[593]</sup></a> A great rose-grower, Mr. Rivers, has + made the same remark with respect to roses. Sageret,<a name="NtA_594" + href="#Nt_594"><sup>[594]</sup></a> who had large experience, in speaking + of the future progress of fruit-trees, observes that the most important + principle is "that the more plants have departed from their original + type, the more they tend to depart from it." There is apparently much + truth in this <!-- Page 242 --><span class="pagenum"><a + name="page242"></a>{242}</span>remark; for we can in no other way + understand the surprising amount of difference between varieties in the + parts or qualities which are valued, whilst other parts retain nearly + their original character.</p> + + <p>The foregoing discussion naturally leads to the question, what is the + limit to the possible amount of variation in any part or quality, and, + consequently, is there any limit to what selection can effect? Will a + race-horse ever be reared fleeter than Eclipse? Can our prize-cattle and + sheep be still further improved? Will a gooseberry ever weigh more than + that produced by "London" in 1852? Will the beet-root in France yield a + greater percentage of sugar? Will future varieties of wheat and other + grain produce heavier crops than our present varieties? These questions + cannot be positively answered; but it is certain that we ought to be + cautious in answering by a negative. In some lines of variation the limit + has probably been reached. Youatt believes that the reduction of bone in + some of our sheep has already been carried so far that it entails great + delicacy of constitution.<a name="NtA_595" + href="#Nt_595"><sup>[595]</sup></a> But seeing the great improvement + within recent times in our cattle and sheep, and especially in our pigs; + seeing the wonderful increase in weight in our poultry of all kinds + during the last few years; he would be a bold man who would assert that + perfection has been reached. Eclipse perhaps may never be beaten until + all our race-horses have been rendered swifter, through the selection of + the best horses during many generations; and then the old Eclipse may + possibly be eclipsed; but, as Mr. Wallace has remarked, there must be an + ultimate limit to the fleetness of every animal, whether under nature or + domestication; and with the horse this limit has perhaps been reached. + Until our fields are better manured, it may be impossible for a new + variety of wheat to yield a heavier crop. But in many cases those who are + best qualified to judge do not believe that the extreme point has as yet + been reached even with respect to characters which have already been + carried to a high standard of perfection. For instance, the short-faced + tumbler-pigeon has been greatly modified; nevertheless, according to Mr. + Eaton,<a name="NtA_596" href="#Nt_596"><sup>[596]</sup></a> "the field is + still as open for fresh competitors as it was one hundred years ago." + Over and over again it has been said that <!-- Page 243 --><span + class="pagenum"><a name="page243"></a>{243}</span>perfection had been + attained with our flowers, but a higher standard has soon been reached. + Hardly any fruit has been more improved than the strawberry, yet a great + authority remarks,<a name="NtA_597" href="#Nt_597"><sup>[597]</sup></a> + "it must not be concealed that we are far from the extreme limits at + which we may arrive."</p> + + <p>Time is an important element in the formation of our domestic races, + as it <span class="correction" title="Original reads `permitts'." + >permits</span> innumerable individuals to be born, and these when + exposed to diversified conditions are rendered variable. Methodical + selection has been occasionally practised from an ancient period to the + present day, even by semi-civilised people, and during former times will + have produced some effect. Unconscious selection will have been still + more effective; for during a lengthened period the more valuable + individual animals will occasionally have been saved, and the less + valuable neglected. In the course, also, of time, different varieties, + especially in the less civilised countries, will have been more or less + modified through natural selection. It is generally believed, though on + this head we have little or no evidence, that new characters in time + become fixed; and after having long remained fixed it seems possible that + under new conditions they might again be rendered variable.</p> + + <p>How great the lapse of time has been since man first domesticated + animals and cultivated plants, we begin dimly to see. When the + lake-buildings of Switzerland were inhabited during the Neolithic period, + several animals were already domesticated and various plants cultivated. + If we may judge from what we now see of the habits of savages, it is + probable that the men of the earlier Stone period—when many great + quadrupeds were living which are now extinct, and when the face of the + country was widely different from what it now is—possessed at least + some few domesticated animals, although their remains have not as yet + been discovered. If the science of language can be trusted, the art of + ploughing and sowing the land was followed, and the chief animals had + been already domesticated, at an epoch so immensely remote, that the + Sanskrit, Greek, Latin, Gothic, Celtic, and Sclavonic languages had not + as yet diverged from their common parent-tongue.<a name="NtA_598" + href="#Nt_598"><sup>[598]</sup></a></p> + +<p><!-- Page 244 --><span class="pagenum"><a name="page244"></a>{244}</span></p> + + <p>It is scarcely possible to overrate the effects of selection + occasionally carried on in various ways and places during thousands of + generations. All that we know, and, in a still stronger degree, all that + we do not know,<a name="NtA_599" href="#Nt_599"><sup>[599]</sup></a> of + the history of the great majority of our breeds, even of our more modern + breeds, agrees with the view that their production, through the action of + unconscious and methodical selection, has been almost insensibly slow. + When a man attends rather more closely than is usual to the breeding of + his animals, he is almost sure to improve them to a slight extent. They + are in consequence valued in his immediate neighbourhood, and are bred by + others; and their characteristic features, whatever these may be, will + then slowly but steadily be increased, sometimes by methodical and almost + always by unconscious selection. At last a strain, deserving to be called + a sub-variety, becomes a little more widely known, receives a local name, + and spreads. The spreading will have been extremely slow during ancient + and less civilised times, but now is rapid. By the time that the new + breed had assumed a somewhat distinct character, its history, hardly + noticed at the time, will have been completely forgotten; for, as Low + remarks,<a name="NtA_600" href="#Nt_600"><sup>[600]</sup></a> "we know + how quickly the memory of such events is effaced."</p> + + <p>As soon as a new breed is thus formed, it is liable through the same + process to break up into new strains and sub-varieties. For different + varieties are suited for, and are valued under, different circumstances. + Fashion changes, but, should a fashion last for even a moderate length of + time, so strong is the principle of inheritance, that some effect will + probably be impressed on the breed. Thus varieties go on increasing in + number, and history shows us how wonderfully they have increased since + the earliest records.<a name="NtA_601" + href="#Nt_601"><sup>[601]</sup></a> As each new variety is produced, the + earlier, intermediate, and less valuable forms will be neglected, and + perish. When a breed, from not being valued, is kept in small numbers, + its extinction almost inevitably follows sooner or later, either from + accidental causes of destruction or from close interbreeding; and this is + an event which, in the case of well-marked breeds, excites attention. The + birth or production of a new domestic race is so slow a process that it + <!-- Page 245 --><span class="pagenum"><a + name="page245"></a>{245}</span>escapes notice; its death or destruction + is comparatively sudden, is often recorded, and when too late sometimes + regretted.</p> + + <p>Several authors have drawn a wide distinction between artificial and + natural races. The latter are more uniform in character, possessing in a + high degree the character of natural species, and are of ancient origin. + They are generally found in less civilised countries, and have probably + been largely modified by natural selection, and only to a small extent by + man's unconscious and methodical selection. They have, also, during a + long period, been directly acted on by the physical conditions of the + countries which they inhabit. The so-called artificial races, on the + other hand, are not so uniform in character; some have a semi-monstrous + character, such as "the wry-legged terriers so useful in + rabbit-shooting,"<a name="NtA_602" href="#Nt_602"><sup>[602]</sup></a> + turnspit dogs, ancon sheep, niata oxen, Polish fowls, fantail-pigeons, + &c.; their characteristic features have generally been acquired + suddenly, though subsequently increased in many cases by careful + selection. Other races, which certainly must be called artificial, for + they have been largely modified by methodical selection and by crossing, + as the English race-horse, terrier-dogs, the English game-cock, Antwerp + carrier-pigeons, &c., nevertheless cannot be said to have an + unnatural appearance; and no distinct line, as it seems to me, can be + drawn between natural and artificial races.</p> + + <p>It is not surprising that domestic races should generally present a + different aspect from natural species. Man selects and propagates + modifications solely for his own use or fancy, and not for the creature's + own good. His attention is struck by strongly marked modifications, which + have appeared suddenly, due to some great disturbing cause in the + organisation. He attends almost exclusively to external characters; and + when he succeeds in modifying internal organs,—when for instance he + reduces the bones and offal, or loads the viscera with fat, or gives + early maturity, &c.,—the chances are strong that he will at the + same time weaken the constitution. On the other hand, when an animal has + to struggle throughout its life with many competitors and enemies, under + circumstances inconceivably complex and liable to change, modifications + of the most varied nature—in the internal organs as well as in + external characters, in the <!-- Page 246 --><span class="pagenum"><a + name="page246"></a>{246}</span>functions and mutual relations of + parts—will be rigorously tested, preserved, or rejected. Natural + selection often checks man's comparatively feeble and capricious attempts + at improvement; and if this were not so, the result of his work, and of + nature's work, would be even still more different. Nevertheless, we must + not overrate the amount of difference between natural species and + domestic races; the most experienced naturalists have often disputed + whether the latter are descended from one or from several aboriginal + stocks, and this clearly shows that there is no palpable difference + between species and races.</p> + + <p>Domestic races propagate their kind far more truly, and endure for + much longer periods, than most naturalists are willing to admit. Breeders + feel no doubt on this head; ask a man who has long reared Shorthorn or + Hereford cattle, Leicester or Southdown sheep, Spanish or Game poultry, + tumbler or carrier-pigeons, whether these races may not have been derived + from common progenitors, and he will probably laugh you to scorn. The + breeder admits that he may hope to produce sheep with finer or longer + wool and with better carcases, or handsomer fowls, or carrier-pigeons + with beaks just perceptibly longer to the practised eye, and thus be + successful at an exhibition. Thus far he will go, but no farther. He does + not reflect on what follows from adding up during a long course of time + many, slight, successive modifications; nor does he reflect on the former + existence of numerous varieties, connecting the links in each divergent + line of descent. He concludes, as was shown in the earlier chapters, that + all the chief breeds to which he has long attended are aboriginal + productions. The systematic naturalist, on the other hand, who generally + knows nothing of the art of breeding, who does not pretend to know how + and when the several domestic races were formed, who cannot have seen the + intermediate gradations, for they do not now exist, nevertheless feels no + doubt that these races are sprung from a single source. But ask him + whether the closely allied natural species which he has studied may not + have descended from a common progenitor, and he in his turn will perhaps + reject the notion with scorn. Thus the naturalist and breeder may + mutually learn a useful lesson from each other.</p> + +<hr class="short" /> + + <p><i>Summary on Selection by Man.</i>—There can be no doubt that + <!-- Page 247 --><span class="pagenum"><a + name="page247"></a>{247}</span>methodical selection has effected and will + effect wonderful results. It was occasionally practised in ancient times, + and is still practised by semi-civilised people. Characters of the + highest importance, and others of trifling value, have been attended to, + and modified. I need not here repeat what has been so often said on the + part which unconscious selection has played: we see its power in the + difference between flocks which have been separately bred, and in the + slow changes, as circumstances have slowly changed, which many animals + have undergone in the same country, or when transported into a foreign + land. We see the combined effects of methodical and unconscious selection + in the great amount of difference between varieties in those parts or + qualities which are valued by man, in comparison with those which are not + valued, and consequently have not been attended to. Natural selection + often determines man's power of selection. We sometimes err in imagining + that characters, which are considered as unimportant by the systematic + naturalist, could not be affected by the struggle for existence, and + therefore be acted on by natural selection; but striking cases have been + given, showing how great an error this is.</p> + + <p>The possibility of selection coming into action rests on variability; + and this is mainly caused, as we shall hereafter see, by changes in the + conditions of life. Selection is sometimes rendered difficult, or even + impossible, by the conditions being opposed to the desired character or + quality. It is sometimes checked by the lessened fertility and weakened + constitution which follow from long-continued close interbreeding. That + methodical selection may be successful, the closest attention and + discernment, combined with unwearied patience, are absolutely necessary; + and these same qualities, though not indispensable, are highly + serviceable in the case of unconscious selection. It is almost necessary + that a large number of individuals should be reared; for thus there will + be a fair chance of variations of the desired nature arising, and every + individual with the slightest blemish or in any degree inferior may be + freely rejected. Hence length of time is an important element of success. + Thus, also, propagation at an early age and at short intervals favours + the work. Facility in pairing animals, or their inhabiting a confined + area, is advantageous as a check to free crossing. Whenever and <!-- Page + 248 --><span class="pagenum"><a name="page248"></a>{248}</span>wherever + selection is not practised, distinct races are not formed. When any one + part of the body or quality is not attended to, it remains either + unchanged or varies in a fluctuating manner, whilst at the same time + other parts and other qualities may become permanently and greatly + modified. But from the tendency to reversion and to continued + variability, those parts or organs which are now undergoing rapid + improvement through selection, are likewise found to vary much. + Consequently highly-bred animals, when neglected, soon degenerate; but we + have no reason to believe that the effects of long-continued selection + would, if the conditions of life remained the same, be soon and + completely lost.</p> + + <p>Man always tends to go to an extreme point in the selection, whether + methodical or unconscious, of all useful and pleasing qualities. This is + an important principle, as it leads to continued divergence, and in some + rare cases to convergence of character. The possibility of continued + divergence rests on the tendency in each part or organ to go on varying + in the same manner in which it has already varied; and that this occurs, + is proved by the steady and gradual improvement of many animals and + plants during lengthened periods. The principle of divergence of + character, combined with the neglect and final extinction of all + previous, less-valued, and intermediate varieties, explains the amount of + difference and the distinctness of our several races. Although we may + have reached the utmost limit to which certain characters can be + modified, yet we are far from having reached, as we have good reason to + believe, the limit in the majority of cases. Finally, from the difference + between selection as carried on by man and by nature, we can understand + how it is that domestic races often, though by no means always, differ in + general aspect from closely allied natural species.</p> + + <p>Throughout this chapter and elsewhere I have spoken of selection as + the paramount power, yet its action absolutely depends on what we in our + ignorance call spontaneous or accidental variability. Let an architect be + compelled to build an edifice with uncut stones, fallen from a precipice. + The shape of each fragment may be called accidental; yet the shape of + each has been determined by the force of gravity, the nature <!-- Page + 249 --><span class="pagenum"><a name="page249"></a>{249}</span>of the + rock, and the slope of the precipice,—events and circumstances, all + of which depend on natural laws; but there is no relation between these + laws and the purpose for which each fragment is used by the builder. In + the same manner the variations of each creature are determined by fixed + and immutable laws; but these bear no relation to the living structure + which is slowly built up through the power of selection, whether this be + natural or artificial selection.</p> + + <p>If our architect succeeded in rearing a noble edifice, using the rough + wedge-shaped fragments for the arches, the longer stones for the lintels, + and so forth, we should admire his skill even in a higher degree than if + he had used stones shaped for the purpose. So it is with selection, + whether applied by man or by nature; for though variability is + indispensably necessary, yet, when we look at some highly complex and + excellently adapted organism, variability sinks to a quite subordinate + position in importance in comparison with selection, in the same manner + as the shape of each fragment used by our supposed architect is + unimportant in comparison with his skill.</p> + +<hr class="full" /> + +<p><!-- Page 250 --><span class="pagenum"><a name="page250"></a>{250}</span></p> + +<h3>CHAPTER XXII.</h3> + +<p class="cenhead">CAUSES OF VARIABILITY.</p> + +<blockquote class="b1n"> + + <p><span class="scac">VARIABILITY DOES NOT NECESSARILY ACCOMPANY + REPRODUCTION</span>—<span class="scac">CAUSES ASSIGNED BY VARIOUS + AUTHORS</span>—<span class="scac">INDIVIDUAL + DIFFERENCES</span>—<span class="scac">VARIABILITY OF EVERY KIND DUE + TO CHANGED CONDITIONS OF LIFE</span>—<span class="scac">ON THE + NATURE OF SUCH CHANGES</span>—<span class="scac">CLIMATE, FOOD, + EXCESS OF NUTRIMENT</span>—<span class="scac">SLIGHT CHANGES + SUFFICIENT</span>—<span class="scac">EFFECTS OF GRAFTING ON THE + VARIABILITY OF SEEDLING-TREES</span>—<span class="scac">DOMESTIC + PRODUCTIONS BECOME HABITUATED TO CHANGED CONDITIONS</span>—<span + class="scac">ON THE ACCUMULATIVE ACTION OF CHANGED + CONDITIONS</span>—<span class="scac">CLOSE INTERBREEDING AND THE + IMAGINATION OF THE MOTHER SUPPOSED TO CAUSE + VARIABILITY</span>—<span class="scac">CROSSING AS A CAUSE OF THE + APPEARANCE OF NEW CHARACTERS</span>—<span class="scac">VARIABILITY + FROM THE COMMINGLING OF CHARACTERS AND FROM REVERSION</span>—<span + class="scac">ON THE MANNER AND PERIOD OF ACTION OF THE CAUSES WHICH + EITHER DIRECTLY, OR INDIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE + VARIABILITY.</span></p> + +</blockquote> + + <p>We will now consider, as far as we can, the causes of the almost + universal variability of our domesticated productions. The subject is an + obscure one; but it may be useful to probe our ignorance. Some authors, + for instance Dr. Prosper Lucas, look at variability as a necessary + contingent on reproduction, and as much an aboriginal law, as growth or + inheritance. Others have of late encouraged, perhaps unintentionally, + this view by speaking of inheritance and variability as equal and + antagonistic principles. Pallas maintained, and he has had some + followers, that variability depends exclusively on the crossing of + primordially distinct forms. Other authors attribute the tendency to + variability to an excess of food, and with animals to an excess + relatively to the amount of exercise taken, or again to the effects of a + more genial climate. That these causes are all effective is highly + probable. But we must, I think, take a broader view, and conclude that + organic beings, when subjected during several generations to any change + whatever in their conditions, tend to vary; the kind of variation which + ensues depending in a far higher degree on the nature or constitution of + the being, than on the nature of the changed conditions. <!-- Page 251 + --><span class="pagenum"><a name="page251"></a>{251}</span></p> + + <p>Those authors who believe that it is a law of nature that each + individual should differ in some slight degree from every other, may + maintain, apparently with truth, that this is the fact, not only with all + domesticated animals and cultivated plants, but likewise with all organic + beings in a state of nature. The Laplander by long practice knows and + gives a name to each reindeer, though, as Linnæus remarks, "to + distinguish one from another among such multitudes was beyond my + comprehension, for they were like ants on an ant-hill." In Germany + shepherds have won wagers by recognising each sheep in a flock of a + hundred, which they had never seen until the previous fortnight. This + power of discrimination, however, is as nothing compared to that which + some florists have acquired. Verlot mentions a gardener who could + distinguish 150 kinds of camellia, when not in flower; and it has been + positively asserted that the famous old Dutch florist Voorhelm, who kept + above 1200 varieties of the hyacinth, was hardly ever deceived in knowing + each variety by the bulb alone. Hence we must conclude that the bulbs of + the hyacinth and the branches and leaves of the camellia, though + appearing to an unpractised eye absolutely undistinguishable, yet really + differ.<a name="NtA_603" href="#Nt_603"><sup>[603]</sup></a></p> + + <p>As Linnæus has compared the reindeer in number to ants, I may add that + each ant knows its fellow of the same community. Several times I carried + ants of the same species (<i>Formica rufa</i>) from one ant-hill to + another, inhabited apparently by tens of thousands of ants; but the + strangers were instantly detected and killed. I then put some ants taken + from a very large nest into a bottle strongly perfumed with + assafœtida, and after an interval of twenty-four hours returned + them to their home; they were at first threatened by their fellows, but + were soon recognised and allowed to pass. Hence each ant certainly + recognises, independently of odour, its fellow; and if all the ants of + the same community have not some countersign or watchword, they must + present to each other's senses some distinguishable character.</p> + +<p><!-- Page 252 --><span class="pagenum"><a name="page252"></a>{252}</span></p> + + <p>The dissimilarity of brothers or sisters of the same family, and of + seedlings from the same capsule, may be in part accounted for by the + unequal blending of the characters of the two parents, and by the more or + less complete recovery through reversion of ancestral characters on + either side; but we thus only push the difficulty further back in time, + for what made the parents or their progenitors different? Hence the + belief<a name="NtA_604" href="#Nt_604"><sup>[604]</sup></a> that an + innate tendency to vary exists, independently of external conditions, + seems at first sight probable. But even the seeds nurtured in the same + capsule are not subjected to absolutely uniform conditions, as they draw + their nourishment from different points; and we shall see in a future + chapter that this difference sometimes suffices greatly to affect the + character of the future plant. The less close similarity of the + successive children of the same family in comparison with human twins, + which often resemble each other in external appearance, mental + disposition, and constitution, in so extraordinary a manner, apparently + proves that the state of the parents at the exact period of conception, + or the nature of the subsequent embryonic development, has a direct and + powerful influence on the character of the offspring. Nevertheless, when + we reflect on the <!-- Page 253 --><span class="pagenum"><a + name="page253"></a>{253}</span>individual differences between organic + beings in a state of nature, as shown by every wild animal knowing its + mate; and when we reflect on the infinite diversity of the many varieties + of our domesticated productions, we may well be inclined to exclaim, + though falsely as I believe, that Variability must be looked at as an + ultimate fact, necessarily contingent on reproduction.</p> + + <p>Those authors who adopt this latter view would probably deny that each + separate variation has its own proper exciting cause. Although we can + seldom trace the precise relation between cause and effect, yet the + considerations presently to be given lead to the conclusion that each + modification must have its own distinct cause. When we hear of an infant + born, for instance, with a crooked finger, a misplaced tooth, or other + slight deviation of structure, it is difficult to bring the conviction + home to the mind that such abnormal cases are the result of fixed laws, + and not of what we blindly call accident. Under this point of view the + following case, which has been carefully examined and communicated to me + by Dr. William Ogle, is highly instructive. Two girls, born as twins, and + in all respects extremely alike, had their little fingers on both hands + crooked; and in both children the second bicuspid tooth in the upper jaw, + of the second dentition, was misplaced; for these teeth, instead of + standing in a line with the others, grew from the roof of the mouth + behind the first bicuspids. Neither the parents nor any other member of + the family had exhibited any similar peculiarity. Now, as both these + children were affected in exactly the same manner by both deviations of + structure, the idea of accident is at once excluded; and we are compelled + to admit that there must have existed some precise and sufficient cause + which, if it had occurred a hundred times, would have affected a hundred + children.</p> + + <p>We will now consider the general arguments, which appear to me to have + great weight, in favour of the view that variations of all kinds and + degrees are directly or indirectly caused by the conditions of life to + which each being, and more especially its ancestors, have been + exposed.</p> + + <p>No one doubts that domesticated productions are more variable than + organic beings which have never been removed from their <!-- Page 254 + --><span class="pagenum"><a name="page254"></a>{254}</span>natural + conditions. Monstrosities graduate so insensibly into mere variations + that it is impossible to separate them; and all those who have studied + monstrosities believe that they are far commoner with domesticated than + with wild animals and plants;<a name="NtA_605" + href="#Nt_605"><sup>[605]</sup></a> and in the case of plants, + monstrosities would be equally noticeable in the natural as in the + cultivated state. Under nature, the individuals of the same species are + exposed to nearly uniform conditions, for they are rigorously kept to + their proper places by a host of competing animals and plants; they have, + also, long been habituated to their conditions of life; but it cannot be + said that they are subject to quite uniform conditions, and they are + liable to a certain amount of variation. The circumstances under which + our domestic productions are reared are widely different: they are + protected from competition; they have not only been removed from their + natural conditions and often from their native land, but they are + frequently carried from district to district, where they are treated + differently, so that they never remain during a considerable length of + time exposed to closely similar conditions. In conformity with this, all + our domesticated productions, with the rarest exceptions, vary far more + than natural species. The hive-bee, which feeds itself and follows in + most respects its natural habits of life, is the least variable of all + domesticated animals, and probably the goose is the next least variable; + but even the goose varies more than almost any wild bird, so that it + cannot be affiliated with perfect certainty to any natural species. + Hardly a single plant can be named, which has long been cultivated and + propagated by seed, that is not highly variable; common rye (<i>Secale + cereale</i>) has afforded fewer and less marked varieties than almost any + other cultivated plant;<a name="NtA_606" + href="#Nt_606"><sup>[606]</sup></a> but it may be doubted whether the + variations of this, the least valuable of all our cereals, have been + closely observed.</p> + + <p>Bud-variation, which was fully discussed in a former chapter, shows us + that variability may be quite independent of seminal reproduction, and + likewise of reversion to long-lost ancestral characters. No one will + maintain that the sudden appearance <!-- Page 255 --><span + class="pagenum"><a name="page255"></a>{255}</span>of a moss-rose on a + Provence-rose is a return to a former state, for mossiness of the calyx + has been observed in no natural species; the same argument is applicable + to variegated and laciniated leaves; nor can the appearance of nectarines + on peach-trees be accounted for with any probability on the principle of + reversion. But bud-variations more immediately concern us, as they occur + far more frequently on plants which have been highly cultivated during a + length of time, than on other and less highly cultivated plants; and very + few well-marked instances have been observed with plants growing under + strictly natural conditions. I have given one instance of an ash-tree + growing in a gentleman's pleasure-grounds; and occasionally there may be + seen, on beech and other trees, twigs leafing at a different period from + the other branches. But our forest trees in England can hardly be + considered as living under strictly natural conditions; the seedlings are + raised and protected in nursery-grounds, and must often be transplanted + into places where wild trees of the kind would not naturally grow. It + would be esteemed a prodigy if a dog-rose growing in a hedge produced by + bud-variation a moss-rose, or a wild bullace or wild cherry-tree yielded + a branch bearing fruit of a different shape and colour from the ordinary + fruit. The prodigy would be enhanced if these varying branches were found + capable of propagation, not only by grafts, but sometimes by seed; yet + analogous cases have occurred with many of our highly cultivated trees + and herbs.</p> + + <p>These several considerations alone render it probable that variability + of every kind is directly or indirectly caused by changed conditions of + life. Or, to put the case under another point of view, if it were + possible to expose all the individuals of a species during many + generations to absolutely uniform conditions of life, there would be no + variability.</p> + +<p class="cenhead"><i>On the Nature of the Changes in the Conditions of Life which +induce Variability.</i></p> + + <p>From a remote period to the present day, under climates and + circumstances as different as it is possible to conceive, organic beings + of all kinds, when domesticated or cultivated, have <!-- Page 256 + --><span class="pagenum"><a name="page256"></a>{256}</span>varied. We see + this with the many domestic races of quadrupeds and birds belonging to + different orders, with gold-fish and silkworms, with plants of many + kinds, raised in various quarters of the world. In the deserts of + northern Africa the date-palm has yielded thirty-eight varieties; in the + fertile plains of India it is notorious how many varieties of rice and of + a host of other plants exist; in a single Polynesian island, twenty-four + varieties of the bread-fruit, the same number of the banana, and + twenty-two varieties of the arum, are cultivated by the natives; the + mulberry-tree in India and Europe has yielded many varieties serving as + food for the silkworm; and in China sixty-three varieties of the bamboo + are used for various domestic purposes.<a name="NtA_607" + href="#Nt_607"><sup>[607]</sup></a> These facts alone, and innumerable + others could be added, indicate that a change of almost any kind in the + conditions of life suffices to cause variability—different changes + acting on different organisms.</p> + + <p>Andrew Knight<a name="NtA_608" href="#Nt_608"><sup>[608]</sup></a> + attributed the variation of both animals and plants to a more abundant + supply of nourishment, or to a more favourable climate, than that natural + to the species. A more genial climate, however, is far from necessary; + the kidney-bean, which is often injured by our spring frosts, and + peaches, which require the protection of a wall, have varied much in + England, as has the orange-tree in northern Italy, where it is barely + able to exist.<a name="NtA_609" href="#Nt_609"><sup>[609]</sup></a> Nor + can we overlook the fact, though not immediately connected with our + present subject, that the plants and shells of the arctic regions are + eminently variable.<a name="NtA_610" href="#Nt_610"><sup>[610]</sup></a> + Moreover, it does not appear that a change of climate, whether more or + less genial, is one of the most potent causes of variability; for in + regard to plants Alph. De Candolle, in his 'Géographie <!-- Page 257 + --><span class="pagenum"><a name="page257"></a>{257}</span>Botanique,' + repeatedly shows that the native country of a plant, where in most cases + it has been longest cultivated, is that where it has yielded the greatest + number of varieties.</p> + + <p>It is doubtful whether a change in the nature of the food is a potent + cause of variability. Scarcely any domesticated animal has varied more + than the pigeon or the fowl, but their food, especially that of + highly-bred pigeons, is generally the same. Nor can our cattle and sheep + have been subjected to any great change in this respect. But in all these + cases the food probably is much less varied in kind than that which was + consumed by the species in its natural state.<a name="NtA_611" + href="#Nt_611"><sup>[611]</sup></a></p> + + <p>Of all the causes which induce variability, excess of food, whether or + not changed in nature, is probably the most powerful. This view was held + with regard to plants by Andrew Knight, and is now held by Schleiden, + more especially in reference to the inorganic elements of the food.<a + name="NtA_612" href="#Nt_612"><sup>[612]</sup></a> In order to give a + plant more food it suffices in most cases to grow it separately, and thus + prevent other plants robbing its roots. It is surprising, as I have often + seen, how vigorously our common wild plants flourish when planted by + themselves, though not in highly manured land. Growing plants separately + is, in fact, the first step in cultivation. We see the converse of the + belief that excess of food induces variability in the following statement + by a great raiser of seeds of all kinds.<a name="NtA_613" + href="#Nt_613"><sup>[613]</sup></a> "It is a rule invariably with us, + when we desire to keep a true stock of any one kind of seed, to grow it + on poor land without dung; but when we grow for quantity, we act + contrary, and sometimes have dearly to repent of it."</p> + + <p>In the case of animals the want of a proper amount of exercise, as + Bechstein has remarked, has perhaps played, independently of the direct + effects of the disuse of any particular organ, an important part in + causing variability. We can see in a vague manner that, when the + organised and nutrient fluids of the body are not used during growth, or + by the wear and tear of the tissues, <!-- Page 258 --><span + class="pagenum"><a name="page258"></a>{258}</span>they will be in excess; + and as growth, nutrition, and reproduction are intimately allied + processes, this superfluity might disturb the due and proper action of + the reproductive organs, and consequently affect the character of the + future offspring. But it may be argued that neither an excess of food nor + a superfluity in the organised fluids of the body necessarily induces + variability. The goose and the turkey have been well fed for many + generations, yet have varied very little. Our fruit-trees and culinary + plants, which are so variable, have been cultivated from an ancient + period, and, though they probably still receive more nutriment than in + their natural state, yet they must have received during many generations + nearly the same amount; and it might be thought that they would have + become habituated to the excess. Nevertheless, on the whole, Knight's + view, that excess of food is one of the most potent causes of + variability, appears, as far as I can judge, probable.</p> + + <p>Whether or not our various cultivated plants have received nutriment + in excess, all have been exposed to changes of various kinds. Fruit-trees + are grafted on different stocks, and grown in various soils. The seeds of + culinary and agricultural plants are carried from place to place; and + during the last century the rotation of our crops and the manures used + have been greatly changed.</p> + + <p>Slight changes of treatment often suffice to induce variability. The + simple fact of almost all our cultivated plants and domesticated animals + having varied in all places and at all times, leads to this conclusion. + Seeds taken from common English forest-trees, grown under their native + climate, not highly manured or otherwise artificially treated, yield + seedlings which vary much, as may be seen in every extensive seed-bed. I + have shown in a former chapter what a number of well marked and singular + varieties the thorn (<i>Cratægus <span class="correction" title="Original reads `oxycantha', corrected by errata, page viii." + >oxyacantha</span></i>) has produced; yet this tree has been subjected to + hardly any cultivation. In Staffordshire I carefully examined a large + number of two British plants, namely, <i>Geranium phæum</i> and + <i>Pyrenaicum</i>, which have never been highly cultivated. These plants + had spread spontaneously by seed from a common garden into an open + plantation; and the seedlings varied in almost every single character, + both in their flowers and foliage, to a degree which <!-- Page 259 + --><span class="pagenum"><a name="page259"></a>{259}</span>I have never + seen exceeded; yet they could not have been exposed to any great change + in their conditions.</p> + + <p>With respect to animals, Azara has remarked with much surprise,<a + name="NtA_614" href="#Nt_614"><sup>[614]</sup></a> that, whilst the feral + horses on the Pampas are always of one of three colours, and the cattle + always of a uniform colour, yet these animals, when bred on the + unenclosed estancias, though kept in a state which can hardly be called + domesticated, and apparently exposed to almost identically the same + conditions as when they are feral, nevertheless display a great diversity + of colour. So again in India several species of fresh-water fish are only + so far treated artificially, that they are reared in great tanks; but + this small change is sufficient to induce much variability.<a + name="NtA_615" href="#Nt_615"><sup>[615]</sup></a></p> + + <p>Some facts on the effects of grafting, in regard to the variability of + trees, deserve attention. Cabanis asserts that when certain pears are + grafted on the quince, their seeds yield more varieties than do the seeds + of the same variety of pear when grafted on the wild pear.<a + name="NtA_616" href="#Nt_616"><sup>[616]</sup></a> But as the pear and + quince are distinct species, though so closely related that the one can + be readily grafted and succeeds admirably on the other, the fact of + variability being thus caused is not surprising; we are, however, here + enabled to see the cause, namely, the different nature of the stock with + its roots and the rest of the tree. Several North American varieties of + the plum and peach are well known to reproduce themselves truly by seed; + but Downing asserts,<a name="NtA_617" href="#Nt_617"><sup>[617]</sup></a> + "that when a graft is taken from one of these trees and placed upon + another stock, this grafted tree is found to lose its singular property + of producing the same variety by seed, and becomes like all other worked + trees;"—that is, its seedlings become highly variable. Another case + is worth giving: the Lalande variety of the walnut-tree leafs between + April 20th and May 15th, and its seedlings invariably inherit the same + habit; whilst several other varieties of the walnut leaf in June. Now, if + seedlings are raised from the May-leafing Lalande variety, grafted on + another May-leafing variety, though both stock and graft have the same + early habit of leafing, yet the seedlings leaf at various times, <!-- + Page 260 --><span class="pagenum"><a name="page260"></a>{260}</span>even + as late as the 5th of June.<a name="NtA_618" + href="#Nt_618"><sup>[618]</sup></a> Such facts as these are well fitted + to show, on what obscure and slight causes variability rests.</p> + +<blockquote class="b1n"> + + <p>I may here just allude to the appearance of new and valuable varieties + of fruit-trees and of wheat in woods and waste places, which at first + sight seems a most anomalous circumstance. In France a considerable + number of the best pears have been discovered in woods; and this has + occurred so frequently, that Poiteau asserts that "improved varieties of + our cultivated fruits rarely originate with nurserymen."<a name="NtA_619" + href="#Nt_619"><sup>[619]</sup></a> In England, on the other hand, no + instance of a good pear having been found wild has been recorded; and Mr. + Rivers informs me that he knows of only one instance with apples, namely, + the Bess Poole, which was discovered in a wood in Nottinghamshire. This + difference between the two countries may be in part accounted for by the + more favourable climate of France, but chiefly from the great number of + seedlings which spring up there in the woods. I infer that this is the + case from a remark made by a French gardener,<a name="NtA_620" + href="#Nt_620"><sup>[620]</sup></a> who regards it as a national calamity + that such a number of pear-trees are periodically cut down for firewood, + before they have borne fruit. The new varieties which thus spring up in + the woods, though they cannot have received any excess of nutriment, will + have been exposed to abruptly changed conditions, but whether this is the + cause of their production is very doubtful. These varieties, however, are + probably all descended<a name="NtA_621" + href="#Nt_621"><sup>[621]</sup></a> from old cultivated kinds growing in + adjoining orchards,—a circumstance which will account for their + variability; and out of a vast number of varying trees there will always + be a good chance of the appearance of a valuable kind. In North America, + where fruit-trees frequently spring up in waste places, the Washington + pear was found in a hedge, and the Emperor peach in a wood.<a + name="NtA_622" href="#Nt_622"><sup>[622]</sup></a></p> + + <p>With respect to wheat, some writers have spoken<a name="NtA_623" + href="#Nt_623"><sup>[623]</sup></a> as if it were an ordinary event for + new varieties to be found in waste places; the Fenton wheat was certainly + discovered growing on a pile of basaltic detritus in a quarry, but in + such a situation the plant would probably receive a sufficient amount + <!-- Page 261 --><span class="pagenum"><a + name="page261"></a>{261}</span>of nutriment. The Chidham wheat was raised + from an ear found <i>on</i> a hedge; and Hunter's wheat was discovered + <i>by</i> the roadside in Scotland, but it is not said that this latter + variety grew where it was found.<a name="NtA_624" + href="#Nt_624"><sup>[624]</sup></a></p> + +</blockquote> + + <p>Whether our domestic productions would ever become so completely + habituated to the conditions under which they now live, as to cease + varying, we have no sufficient means for judging. But, in fact, our + domestic productions are never exposed for a great length of time to + uniform conditions, and it is certain that our most anciently cultivated + plants, as well as animals, still go on varying, for all have recently + undergone marked improvement. In some few cases, however, plants have + become habituated to new conditions. Thus Metzger, who cultivated in + Germany during many years numerous varieties of wheat, brought from + different countries,<a name="NtA_625" href="#Nt_625"><sup>[625]</sup></a> + states that some kinds were at first extremely variable, but gradually, + in one instance after an interval of twenty-five years, became constant; + and it does not appear that this resulted from the selection of the more + constant forms.</p> + +<hr class="short" /> + + <p><i>On the Accumulative Action of changed Conditions of + Life.</i>—We have good grounds for believing that the influence of + changed conditions accumulates, so that no effect is produced on a + species until it has been exposed during several generations to continued + cultivation or domestication. Universal experience shows us that when new + flowers are first introduced into our gardens they do not vary; but + ultimately all, with the rarest exceptions, vary to a greater or less + extent. In a few cases the requisite number of generations, as well as + the successive steps in the progress of variation, have been recorded, as + in the often-quoted instance of the Dahlia.<a name="NtA_626" + href="#Nt_626"><sup>[626]</sup></a> After several years' culture the + Zinnia has only lately (1860) begun to vary in any great degree. "In the + first seven or eight years of high cultivation the Swan River daisy + (<i>Brachycome iberidifolia</i>) kept to its original colour; it then + varied into lilac and purple and other minor shades."<a name="NtA_627" + href="#Nt_627"><sup>[627]</sup></a> Analogous facts have been recorded + with the Scotch rose. In discussing the variability of plants several + experienced horticulturists have spoken to the <!-- Page 262 --><span + class="pagenum"><a name="page262"></a>{262}</span>same general effect. + Mr. Salter<a name="NtA_628" href="#Nt_628"><sup>[628]</sup></a> remarks, + "Every one knows that the chief difficulty is in breaking through the + original form and colour of the species, and every one will be on the + look-out for any natural sport, either from seed or branch; that being + once obtained, however trifling the change may be, the result depends + upon himself." M. de Jonghe, who has had so much success in raising new + varieties of pears and strawberries,<a name="NtA_629" + href="#Nt_629"><sup>[629]</sup></a> remarks with respect to the former, + "There is another principle, namely, that the more a type has entered + into a state of variation, the greater is its tendency to continue doing + so; and the more it has varied from the original type, the more it is + disposed to vary still farther." We have, indeed, already discussed this + latter point when treating of the power which man possesses, through + selection, of continually augmenting in the same direction each + modification; for this power depends on continued variability of the same + general kind. The most celebrated horticulturist in France, namely, + Vilmorin,<a name="NtA_630" href="#Nt_630"><sup>[630]</sup></a> even + maintains that, when any particular variation is desired, the first step + is to get the plant to vary in any manner whatever, and to go on + selecting the most variable individuals, even though they vary in the + wrong direction; for the fixed character of the species being once + broken, the desired variation will sooner or later appear.</p> + + <p>As nearly all our animals were domesticated at an extremely remote + epoch, we cannot, of course, say whether they varied quickly or slowly + when first subjected to new conditions. But Dr. Bachman<a name="NtA_631" + href="#Nt_631"><sup>[631]</sup></a> states that he has seen turkeys + raised from the eggs of the wild species lose their metallic tints and + become spotted with white in the third generation. Mr. Yarrell many years + ago informed me that the wild ducks bred on the ponds in St. James's + Park, which had never been crossed, as it is believed, with domestic + ducks, lost their true plumage after a few generations. An excellent + observer,<a name="NtA_632" href="#Nt_632"><sup>[632]</sup></a> who has + often reared birds from the eggs of the wild duck, and who took + precautions <!-- Page 263 --><span class="pagenum"><a + name="page263"></a>{263}</span>that there should be no crossing with + domestic breeds, has given, as previously stated, full details on the + changes which they gradually undergo. He found that he could not breed + these wild ducks true for more than five or six generations, "as they + then proved so much less beautiful. The white collar round the neck of + the mallard became much broader and more irregular, and white feathers + appeared in the ducklings' wings." They increased also in size of body; + their legs became less fine, and they lost their elegant carriage. Fresh + eggs were then procured from wild birds; but again the same result + followed. In these cases of the duck and turkey we see that animals, like + plants, do not depart from their primitive type until they have been + subjected during several generations to domestication. On the other hand, + Mr. Yarrell informed me that the Australian dingos, bred in the + Zoological Gardens, almost invariably produced in the first generation + puppies marked with white and other colours; but these introduced dingos + had probably been procured from the natives, who keep them in a + semi-domesticated state. It is certainly a remarkable fact that changed + conditions should at first produce, as far as we can see, absolutely no + effect; but that they should subsequently cause the character of the + species to change. In the chapter on pangenesis I shall attempt to throw + a little light on this fact.</p> + +<hr class="short" /> + + <p>Returning now to the causes which are supposed to induce variability. + Some authors<a name="NtA_633" href="#Nt_633"><sup>[633]</sup></a> believe + that close interbreeding gives this tendency, and leads to the production + of monstrosities. In the seventeenth chapter some few facts were + advanced, showing that monstrosities are, as it appears, occasionally + thus caused; and there can be no doubt that close interbreeding induces + lessened fertility and a weakened constitution; hence it may lead to + variability: but I have not sufficient evidence on this head. On the + other hand, close interbreeding, if not carried to an injurious extreme, + far from causing variability, tends to fix the character of each + breed.</p> + + <p>It was formerly a common belief, still held by some persons, that the + imagination of the mother affects the child in <!-- Page 264 --><span + class="pagenum"><a name="page264"></a>{264}</span>the womb.<a + name="NtA_634" href="#Nt_634"><sup>[634]</sup></a> This view is evidently + not applicable to the lower animals, which lay unimpregnated eggs, or to + plants. Dr. William Hunter, in the last century, told my father that + during many years every woman in a large London Lying-in Hospital was + asked before her confinement whether anything had specially affected her + mind, and the answer was written down; and it so happened that in no one + instance could a coincidence be detected between the woman's answer and + any abnormal structure; but when she knew the nature of the structure, + she frequently suggested some fresh cause. The belief in the power of the + mother's imagination may perhaps have arisen from the children of a + second marriage resembling the previous father, as certainly sometimes + occurs, in accordance with the facts given in the eleventh chapter.</p> + +<hr class="short" /> + + <p><i>Crossing as a Cause of Variability.</i>—In an early part of + this chapter it was stated that Pallas<a name="NtA_635" + href="#Nt_635"><sup>[635]</sup></a> and a few other naturalists maintain + that variability is wholly due to crossing. If this means that new + characters never spontaneously appear in our domestic races, but that + they are all directly derived from certain aboriginal species, the + doctrine is little less than absurd; for it implies that animals like + Italian greyhounds, pug-dogs, bull-dogs, pouter and fantail pigeons, + &c., were able to exist in a state of nature. But the doctrine may + mean something widely different, namely, that the crossing of distinct + species is the sole cause of the first appearance of new characters, and + that without this aid man could not have formed his various breeds. As, + however, new characters have appeared in certain cases by bud-variation, + we may conclude with certainty that crossing is not necessary for + variability. It is, moreover, almost certain that the breeds of various + animals, such as of the rabbit, pigeon, duck, &c., and the varieties + of several plants, are the modified descendants of a single wild species. + Nevertheless, it is probable that the crossing of two forms, when one or + both have long been domesticated or cultivated, adds to the variability + of the offspring, independently of the commingling of the characters + derived from the two parent-forms; and this implies <!-- Page 265 + --><span class="pagenum"><a name="page265"></a>{265}</span>that new + characters actually arise. But we must not forget the facts advanced in + the thirteenth chapter, which clearly prove that the act of crossing + often leads to the reappearance or reversion of long-lost characters; and + in most cases it would be impossible to distinguish between the + reappearance of ancient characters and the first appearance of new + characters. Practically, whether new or old, they would be new to the + breed in which they reappeared.</p> + +<blockquote class="b1n"> + + <p>Gärtner declares,<a name="NtA_636" href="#Nt_636"><sup>[636]</sup></a> + and his experience is of the highest value on such a point, that, when he + crossed native plants which had not been cultivated, he never once saw in + the offspring any new character; but that from the odd manner in which + the characters derived from the parents were combined, they sometimes + appeared as if new. When, on the other hand, he crossed cultivated + plants, he admits that new characters occasionally appeared, but he is + strongly inclined to attribute their appearance to ordinary variability, + not in any way to the cross. An opposite conclusion, however, appears to + me the more probable. According to Kölreuter, hybrids in the genus + Mirabilis vary almost infinitely, and he describes new and singular + characters in the form of the seeds, in the colour of the anthers, in the + cotyledons being of immense size, in new and highly peculiar odours, in + the flowers expanding early in the season, and in their closing at night. + With respect to one lot of these hybrids, he remarks that they presented + characters exactly the reverse of what might have been expected from + their parentage.<a name="NtA_637" href="#Nt_637"><sup>[637]</sup></a></p> + + <p>Prof. Lecoq<a name="NtA_638" href="#Nt_638"><sup>[638]</sup></a> + speaks strongly to the same effect in regard to this same genus, and + asserts that many of the hybrids from <i>Mirabilis jalapa</i> and + <i>multiflora</i> might easily be mistaken for distinct species, and adds + that they differed in a greater degree, than the other species of the + genus, from <i>M. jalapa</i>. Herbert, also, has described<a + name="NtA_639" href="#Nt_639"><sup>[639]</sup></a> the offspring from a + hybrid Rhododendron as being "as <i>unlike all others</i> in foliage, as + if they had been a separate species." The common experience of + floriculturists proves that the crossing and recrossing of distinct but + allied plants, such as the species of Petunia, Calceolaria, Fuchsia, + Verbena, &c., induces excessive variability; hence the appearance of + quite new characters is probable. M. Carrière<a name="NtA_640" + href="#Nt_640"><sup>[640]</sup></a> has lately discussed this subject: he + states that <i>Erythrina cristagalli</i> had been multiplied by seed for + many years, but had not yielded any varieties: it was then crossed with + the allied <i>E. herbacea</i>, and "the resistance was now overcome, and + varieties were produced with flowers of extremely different size, form, + and colour."</p> + + <p>From the general and apparently well-founded belief that the crossing + <!-- Page 266 --><span class="pagenum"><a + name="page266"></a>{266}</span>of distinct species, besides commingling + their characters, adds greatly to their variability, it has probably + arisen that some botanists have gone so far as to maintain<a + name="NtA_641" href="#Nt_641"><sup>[641]</sup></a> that, when a genus + includes only a single species, this when cultivated never varies. The + proposition made so broadly cannot be admitted; but it is probably true + that the variability of cultivated monotypic genera is much less than + that of genera including numerous species, and this quite independently + of the effects of crossing. I have stated in my 'Origin of Species,' and + in a future work shall more fully show, that the species belonging to + small genera generally yield a less number of varieties in a state of + nature than those belonging to large genera. Hence the species of small + genera would, it is probable, produce fewer varieties under cultivation + than the already variable species of larger genera.</p> + + <p>Although we have not at present sufficient evidence that the crossing + of species, which have never been cultivated, leads to the appearance of + new characters, this apparently does occur with species which have been + already rendered in some degree variable through cultivation. Hence + crossing, like any other change in the conditions of life, seems to be an + element, probably a potent one, in causing variability. But we seldom + have the means of distinguishing, as previously remarked, between the + appearance of really new characters and the reappearance of long-lost + characters, evoked through the act of crossing. I will give an instance + of the difficulty in distinguishing such cases. The species of Datura may + be divided into two sections, those having white flowers with green + stems, and those having purple flowers with brown stems: now Naudin<a + name="NtA_642" href="#Nt_642"><sup>[642]</sup></a> crossed <i>Datura + lævis</i> and <i>ferox</i>, both of which belong to the white section, + and raised from them 205 hybrids. Of these hybrids, every one had brown + stems and bore purple flowers; so that they resembled the species of the + other section of the genus, and not their own two parents. Naudin was so + much astonished at this fact, that he was led carefully to observe both + parent-species, and he discovered that the pure seedlings of <i>D. + ferox</i>, immediately after germination, had dark purple stems, + extending from the young roots up to the cotyledons, and that this tint + remained ever afterwards as a ring round the base of the stem of the + plant when old. Now I have shown in the thirteenth chapter that the + retention or exaggeration of an early character is so intimately related + to reversion, that it evidently comes under the same principle. Hence + probably we ought to look at the purple flowers and brown stems of these + hybrids, not as new characters due to variability, but as a return to the + former state of some ancient progenitor.</p> + + <p>Independently of the appearance of new characters from crossing, a few + words may be added to what has been said in former chapters on the + unequal combination and transmission of the characters proper to the two + parent-forms. When two species or races are crossed, the offspring of + <!-- Page 267 --><span class="pagenum"><a + name="page267"></a>{267}</span>the first generation are generally + uniform, but subsequently they display an almost infinite diversity of + character. He who wishes, says Kölreuter,<a name="NtA_643" + href="#Nt_643"><sup>[643]</sup></a> to obtain an endless number of + varieties from hybrids should cross and recross them. There is also much + variability when hybrids or mongrels are reduced or absorbed by repeated + crosses with either pure parent-form; and a still higher degree of + variability when three distinct species, and most of all when four + species, are blended together by successive crosses. Beyond this point + Gärtner,<a name="NtA_644" href="#Nt_644"><sup>[644]</sup></a> on whose + authority the foregoing statements are made, never succeeded in effecting + a union; but Max Wichura<a name="NtA_645" + href="#Nt_645"><sup>[645]</sup></a> united six distinct species of + willows into a single hybrid. The sex of the parent-species affects in an + inexplicable manner the degree of variability of hybrids; for Gärtner<a + name="NtA_646" href="#Nt_646"><sup>[646]</sup></a> repeatedly found that + when a hybrid was used as the father, and either one of the pure + parent-species, or a third species, was used as the mother, the offspring + were more variable than when the same hybrid was used as the mother, and + either pure parent or the same third species as the father: thus + seedlings from <i>Dianthus barbatus</i> crossed by the hybrid <i>D. + chinensi-barbatus</i> were more variable than those raised from this + latter hybrid fertilised by the pure <i>D. barbatus</i>. Max Wichura<a + name="NtA_647" href="#Nt_647"><sup>[647]</sup></a> insists strongly on an + analogous result with his hybrid willows. Again Gärtner<a name="NtA_648" + href="#Nt_648"><sup>[648]</sup></a> asserts that the degree of + variability sometimes differs in hybrids raised from reciprocal crosses + between the same two species; and here the sole difference is, that the + one species is first used as the father and then as the mother. On the + whole we see that, independently of the appearance of new characters, the + variability of successive crossed generations is extremely complex, + partly from the offspring partaking unequally of the characters of the + two parent-forms, and more especially from their unequal tendency to + revert to these same characters or to those of more ancient + progenitors.</p> + +</blockquote> + +<hr class="short" /> + + <p><i>On the Manner and on the Period of Action of the Causes which + induce Variability.</i>—This is an extremely obscure subject, and + we need here only briefly consider, firstly, whether inherited variations + are caused by the organisation being directly acted on, or indirectly + through the reproductive system; and secondly, at what period of life or + growth they are primarily caused. We shall see in the two following + chapters that various agencies, such as an abundant supply of food, + exposure to a different climate, increased use or disuse of parts, + &c., prolonged during several generations, certainly modify either + the whole organisation or certain organs. This direct action of changed + conditions perhaps comes into play much more frequently than can be + proved, and it is at least clear that in all cases of <!-- Page 268 + --><span class="pagenum"><a name="page268"></a>{268}</span>bud-variation + the action cannot have been through the reproductive system.</p> + +<blockquote class="b1n"> + + <p>With respect to the part which the reproductive system takes in + causing variability, we have seen in the eighteenth chapter that even + slight changes in the conditions of life have a remarkable power in + causing a greater or less degree of sterility. Hence it seems not + improbable that being generated though a system so easily affected should + themselves be affected, or should fail to inherit, or inherit in excess, + characters proper to their parents. We know that certain groups of + organic beings, but with exceptions in each group, have their + reproductive systems much more easily affected by changed conditions than + other groups; for instance, carnivorous birds more readily than + carnivorous mammals, and parrots more readily than pigeons; and this fact + harmonizes with the apparently capricious manner and degree in which + various groups of animals and plants vary under domestication.</p> + + <p>Kölreuter<a name="NtA_649" href="#Nt_649"><sup>[649]</sup></a> was + struck with the parallelism between the excessive variability of hybrids + when crossed and recrossed in various ways,—these hybrids having + their reproductive powers more or less affected,—and the + variability of anciently cultivated plants. Max Wichura<a name="NtA_650" + href="#Nt_650"><sup>[650]</sup></a> has gone one step farther, and shows + that with many of our highly cultivated plants, such as the hyacinth, + tulip, auricula, snapdragon, potato, cabbage, &c., which there is no + reason to believe have been hybridized, the anthers contain many + irregular pollen-grains, in the same state as in hybrids. He finds also + in certain wild forms, the same coincidence between the state of the + pollen and a high degree of variability, as in many species of Rubus; but + in <i>R. cæsius</i> and <i>idæus</i>, which are not highly variable + species, the pollen is sound. It is also notorious that many cultivated + plants, such as the banana, pine-apple, breadfruit, and others previously + mentioned, have their reproductive organs so seriously affected as to be + generally quite sterile; and when they do yield seed, the seedlings, + judging from the large number of cultivated races which exist, must be + variable in an extreme degree. These facts indicate that there is some + relation between the state of the reproductive organs and a tendency to + variability; but we must not conclude that the relation is strict. + Although many of our highly cultivated plants may have their pollen in a + deteriorated condition, yet, as we have previously seen, they yield more + seed, and our anciently domesticated animals are more prolific, than the + corresponding species in a state of nature. The peacock is almost the + only bird which is believed to be less fertile under domestication than + in its native state, and it has varied in a remarkably small degree. From + these considerations it would seem that changes in the conditions of life + lead either to sterility or to variability, or to both; and not that + sterility induces variability. On the whole it is probable that any cause + affecting the organs of reproduction would likewise affect their + product,—that is, the offspring thus generated.</p> + +<p><!-- Page 269 --><span class="pagenum"><a name="page269"></a>{269}</span></p> + + <p>The period of life at which the causes that induce variability act, is + another obscure subject, which has been discussed by various authors.<a + name="NtA_651" href="#Nt_651"><sup>[651]</sup></a> In some of the cases, + to be given in the following chapter, of modifications from the direct + action of changed conditions, which are inherited, there can be no doubt + that the causes have acted on the mature or nearly mature animal. On the + other hand, monstrosities, which cannot be distinctly separated from + lesser variations, are often caused by the embryo being injured whilst in + the mother's womb or in the egg. Thus I. Geoffroy St. Hilaire<a + name="NtA_652" href="#Nt_652"><sup>[652]</sup></a> asserts that poor + women who work hard during their pregnancy, and the mothers of + illegitimate children troubled in their minds and forced to conceal their + state, are far more liable to give birth to monsters than women in easy + circumstances. The eggs of the fowl when placed upright or otherwise + treated unnaturally frequently produce monstrous chickens. It would, + however, appear that complex monstrosities are induced more frequently + during a rather late than during a very early period of embryonic life; + but this may partly result from some one part, which has been injured + during an early period, affecting by its abnormal growth other parts + subsequently developed; and this would be less likely to occur with parts + injured at a later period.<a name="NtA_653" + href="#Nt_653"><sup>[653]</sup></a> When any part or organ becomes + monstrous through abortion, a rudiment is generally left, and this + likewise indicates that its development had already commenced.</p> + + <p>Insects sometimes have their antennæ or legs in a monstrous condition, + and yet the larvæ from which they are metamorphosed do not possess either + antennæ or legs; and in those cases, as Quatrefages<a name="NtA_654" + href="#Nt_654"><sup>[654]</sup></a> believes, we are enabled to see the + precise period at which the normal progress of development has been + troubled. But the nature of the food given to a caterpillar sometimes + affects the colours of the moth, without the caterpillar itself being + affected; therefore it seems possible that other characters in the mature + insect might be indirectly modified through the larvæ. There is no reason + to suppose that organs which have been rendered monstrous have always + been acted on during their development; the cause may have acted on the + organisation at a much earlier stage. It is even probable that either the + male or female sexual elements, or both, before their union, may be + affected in such a manner as to lead to modifications in organs developed + at a late period of life; in nearly the same manner as a child may + inherit from his father a disease which does not appear until old + age.</p> + + <p>In accordance with the facts above given, which prove that in many + cases a close relation exists between variability and the sterility + following from changed conditions, we may conclude that the exciting + cause often acts at the earliest possible period, namely, on the sexual + elements, before impregnation has taken place. That an affection of the + female sexual element may induce variability we may likewise infer as + probable from the occurrence of bud-variations; for a bud seems to be the + analogue of an ovule. But the male element is apparently much oftener + affected by changed <!-- Page 270 --><span class="pagenum"><a + name="page270"></a>{270}</span>conditions, at least in a visible manner, + than the female element or ovule; and we know from Gärtner's and + Wichura's statements that a hybrid used as the father and crossed with a + pure species gives a greater degree of variability to the offspring, than + does the same hybrid when used as the mother. Lastly, it is certain that + variability may be transmitted through either sexual element, whether or + not originally excited in them, for Kölreuter and Gärtner<a + name="NtA_655" href="#Nt_655"><sup>[655]</sup></a> found that when two + species were crossed, if either one was variable, the offspring were + rendered variable.</p> + +</blockquote> + +<hr class="short" /> + + <p><i>Summary.</i>—From the facts given in this chapter, we may + conclude that the variability of organic beings under domestication, + although so general, is not an inevitable contingent on growth and + reproduction, but results from the conditions to which the parents have + been exposed. Changes of any kind in the conditions of life, even + extremely slight changes, often suffice to cause variability. Excess of + nutriment is perhaps the most efficient single exciting cause. Animals + and plants continue to be variable for an immense period after their + first domestication; but the conditions to which they are exposed never + long remain quite constant. In the course of time they can be habituated + to certain changes, so as to become less variable; and it is possible + that when first domesticated they may have been even more variable than + at present. There is good evidence that the power of changed conditions + accumulates; so that two, three, or more generations must be exposed to + new conditions before any effect is visible. The crossing of distinct + forms, which have already become variable, increases in the offspring the + tendency to further variability, by the unequal commingling of the + characters of the two parents, by the reappearance of long-lost + characters, and by the appearance of absolutely new characters. Some + variations are induced by the direct action of the surrounding conditions + on the whole organisation, or on certain parts alone, and other + variations are induced indirectly through the reproductive system being + affected in the same manner as is so common with organic beings when + removed from their natural conditions. The causes which induce + variability act on the mature organism, on the embryo, and, as we have + good reason to believe, on both sexual elements before impregnation has + been effected.</p> + +<hr class="full" /> + +<p><!-- Page 271 --><span class="pagenum"><a name="page271"></a>{271}</span></p> + +<h3>CHAPTER XXIII.</h3> + +<p class="cenhead">DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS +OF LIFE.</p> + +<blockquote class="b1n"> + + <p><span class="scac">SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE + ACTION OF CHANGED CONDITIONS IN SIZE, COLOUR, CHEMICAL PROPERTIES, AND IN + THE STATE OF THE TISSUES</span>—<span class="scac">LOCAL + DISEASES</span>—<span class="scac">CONSPICUOUS MODIFICATIONS FROM + CHANGED CLIMATE OR FOOD, ETC.</span>—<span class="scac">PLUMAGE OF + BIRDS AFFECTED BY PECULIAR NUTRIMENT, AND BY THE INOCULATION OF + POISON</span>—<span class="scac">LAND-SHELLS</span>—<span + class="scac">MODIFICATIONS OF ORGANIC BEINGS IN A STATE OF NATURE THROUGH + THE DEFINITE ACTION OF EXTERNAL CONDITIONS</span>—<span + class="scac">COMPARISON OF AMERICAN AND EUROPEAN TREES</span>—<span + class="scac">GALLS</span>—<span class="scac">EFFECTS OF PARASITIC + FUNGI</span>—<span class="scac">CONSIDERATIONS OPPOSED TO THE + BELIEF IN THE POTENT INFLUENCE OF CHANGED EXTERNAL + CONDITIONS</span>—<span class="scac">PARALLEL SERIES OF + VARIETIES</span>—<span class="scac">AMOUNT OF VARIATION DOES NOT + CORRESPOND WITH THE DEGREE OF CHANGE IN THE CONDITIONS</span>—<span + class="scac">BUD-VARIATION</span>—<span class="scac">MONSTROSITIES + PRODUCED BY UNNATURAL TREATMENT</span>—<span + class="scac">SUMMARY.</span></p> + +</blockquote> + + <p>If we ask ourselves why this or that character has been modified under + domestication, we are, in most cases lost in utter darkness. Many + naturalists, especially of the French school, attribute every + modification to the "monde ambiant," that is, to changed climate, with + all its diversities of heat and cold, dampness and dryness, light and + electricity, to the nature of the soil, and to varied kinds and amount of + food. By the term definite action, as used in this chapter, I mean an + action of such a nature that, when many individuals of the same variety + are exposed during several generations to any change in their physical + conditions of life, all, or nearly all the individuals, are modified in + the same manner. A new sub-variety would thus be produced without the aid + of selection.</p> + + <p>I do not include under the term of definite action the effects of + habit or of the increased use and disuse of various organs. Modifications + of this nature, no doubt, are definitely caused by the conditions to + which the beings are subjected; but they depend much less on the nature + of the conditions than on the laws of growth; hence they are included + under a distinct head in the <!-- Page 272 --><span class="pagenum"><a + name="page272"></a>{272}</span>following chapter. We know, however, far + too little of the causes and laws of variation to make a sound + classification. The direct action of the conditions of life, whether + leading to definite or indefinite results, is a totally distinct + consideration from the effects of natural selection; for natural + selection depends on the survival under various and complex circumstances + of the best-fitted individuals, but has no relation whatever to the + primary cause of any modification of structure.</p> + + <p>I will first give in detail all the facts which I have been able to + collect, rendering it probable that climate, food, &c., have acted so + definitely and powerfully on the organisation of our domesticated + productions, that they have sufficed to form new sub-varieties or races, + without the aid of selection by man or of natural selection. I will then + give the facts and considerations opposed to this conclusion, and finally + we will weigh, as fairly as we can, the evidence on both sides.</p> + + <p>When we reflect that distinct races of almost all our domesticated + animals exist in each kingdom of Europe, and formerly even in each + district of England, we are at first strongly inclined to attribute their + origin to the definite action of the physical conditions of each country; + and this has been the conclusion of many authors. But we should bear in + mind that man annually has to choose which animals shall be preserved for + breeding, and which shall be slaughtered. We have also seen that both + methodical and unconscious selection were formerly practised, and are now + occasionally practised by the most barbarous races, to a much greater + extent than might have been anticipated. Hence it is very difficult to + judge how far the difference in conditions between, for instance, the + several districts in England, could have sufficed without the aid of + selection to modify the breeds which have been reared in each. It may be + argued that, as numerous wild animals and plants have ranged during many + ages throughout Great Britain, and still retain the same character, the + difference in conditions between the several districts could not have + modified in so marked a manner the various native races of cattle, sheep, + pigs, and horses. The same difficulty of distinguishing between selection + and the definite effects of the conditions of life, is encountered in a + still higher degree when we compare closely allied natural <!-- Page 273 + --><span class="pagenum"><a name="page273"></a>{273}</span>forms, + inhabiting two countries, such as North America and Europe, which do not + differ greatly in climate, nature of soil, &c., for in this case + natural selection will inevitably and rigorously have acted during a long + succession of ages.</p> + +<blockquote class="b1n"> + + <p>From the importance of the difficulty just alluded to, it will be + advisable to give as large a body of facts as possible, showing that + extremely slight differences in treatment, either in different parts of + the same country, or during different seasons, certainly cause an + appreciable effect, at least on varieties which are already in an + unstable condition. Ornamental flowers are good for this purpose, as they + are highly variable, and are carefully observed. All floriculturists are + unanimous that certain varieties are affected by very slight differences + in the nature of the artificial compost in which they are grown, and by + the natural soil of the district, and by the season. Thus, a skilful + judge, in writing on Carnations and Picotees,<a name="NtA_656" + href="#Nt_656"><sup>[656]</sup></a> asks "where can Admiral Curzon be + seen possessing the colour, size, and strength which it has in + Derbyshire? Where can Flora's Garland be found equal to those at Slough? + Where do high-coloured flowers revel better than at Woolwich and + Birmingham? Yet in no two of these districts do the same varieties attain + an equal degree of excellence, although each may be receiving the + attention of the most skilful cultivators." The same writer then + recommends every cultivator to keep five different kinds of soil and + manure, "and to endeavour to suit the respective appetites of the plants + you are dealing with, for without such attention all hope of general + success will be vain." So it is with the Dahlia:<a name="NtA_657" + href="#Nt_657"><sup>[657]</sup></a> the Lady Cooper rarely succeeds near + London, but does admirably in other districts; the reverse holds good + with other varieties; and again, there are others which succeed equally + well in various situations. A skilful gardener<a name="NtA_658" + href="#Nt_658"><sup>[658]</sup></a> states that he procured cuttings of + an old and well-known variety (pulchella) of Verbena, which from having + been propagated in a different situation presented a slightly different + shade of colour; the two varieties were afterwards multiplied by + cuttings, being carefully kept distinct; but in the second year they + could hardly be distinguished, and in the third year no one could + distinguish them.</p> + + <p>The nature of the season has an especial influence on certain + varieties of the Dahlia: in 1841 two varieties were pre-eminently good, + and the next year these same two were pre-eminently bad. A famous + amateur<a name="NtA_659" href="#Nt_659"><sup>[659]</sup></a> asserts that + in 1861 many varieties of the Rose came so untrue in character, "that it + was hardly possible to recognise them, and the thought was not seldom + entertained that the grower had lost his tally." The same amateur<a + name="NtA_660" href="#Nt_660"><sup>[660]</sup></a> states that in 1862 + two-thirds of his Auriculas produced central trusses of flowers, and + these are remarkable from not keeping true; <!-- Page 274 --><span + class="pagenum"><a name="page274"></a>{274}</span>and he adds that in + some seasons certain varieties of this plant all prove good, and the next + season all prove bad; whilst exactly the reverse happens with other + varieties. In 1845 the editor of the 'Gardener's Chronicle'<a + name="NtA_661" href="#Nt_661"><sup>[661]</sup></a> remarked how singular + it was that this year many Calceolarias tended to assume a tubular form. + With Heartsease<a name="NtA_662" href="#Nt_662"><sup>[662]</sup></a> the + blotched sorts do not acquire their proper character until hot weather + sets in; whilst other varieties lose their beautiful marks as soon as + this occurs.</p> + + <p>Analogous facts have been observed with leaves: Mr. Beaton asserts<a + name="NtA_663" href="#Nt_663"><sup>[663]</sup></a> that he raised at + Shrubland, during six years, twenty thousand seedlings from the Punch + Pelargonium, and not one had variegated leaves; but at Surbiton, in + Surrey, one-third, or even a greater proportion, of the seedlings from + this same variety were more or less variegated. The soil of another + district in Surrey has a strong tendency to cause variegation, as appears + from information given me by Sir F. Pollock. Verlot<a name="NtA_664" + href="#Nt_664"><sup>[664]</sup></a> states that the variegated strawberry + retains its character as long as grown in a dryish soil, but soon loses + it when planted in fresh and humid soil. Mr. Salter, who is well known + for his success in cultivating variegated plants, informs me that rows of + strawberries were planted in his garden in 1859, in the usual way; and at + various distances in one row, several plants simultaneously became + variegated, and what made the case more extraordinary, all were + variegated in precisely the same manner. These plants were removed, but + during the three succeeding years other plants in the same row became + variegated, and in no instance were the plants in any adjoining row + affected.</p> + + <p>The chemical qualities, odours, and tissues of plants are often + modified by a change which seems to us slight. The Hemlock is said not to + yield conicine in Scotland. The root of the <i>Aconitum napellus</i> + becomes innocuous in frigid climates. The medicinal properties of the + Digitalis are easily affected by culture. The Rhubarb flourishes in + England, but does not produce the medicinal substance which makes the + plant so valuable in Chinese Tartary. As the <i>Pistacia lentiscus</i> + grows abundantly in the South of France, the climate must suit it, but it + yields no mastic. The <i>Laurus sassafras</i> in Europe loses the odour + proper to it in North America.<a name="NtA_665" + href="#Nt_665"><sup>[665]</sup></a> Many similar facts could be given, + and they are remarkable because it might have been thought that definite + chemical compounds would have been little liable to change either in + quality or quantity.</p> + + <p>The wood of the American Locust-tree (<i>Robinia</i>) when grown in + England is nearly worthless, as is that of the Oak-tree when grown at the + Cape of Good Hope.<a name="NtA_666" href="#Nt_666"><sup>[666]</sup></a> + Hemp and flax, as I hear from Dr. Falconer, flourish and yield plenty of + seed on the plains of India, but their fibres are brittle <!-- Page 275 + --><span class="pagenum"><a name="page275"></a>{275}</span>and useless. + Hemp, on the other hand, fails to produce in England that resinous matter + which is so largely used in India as an intoxicating drug.</p> + + <p>The fruit of the Melon is greatly influenced by slight differences in + culture and climate. Hence it is generally a better plan, according to + Naudin, to improve an old kind than to introduce a new one into any + locality. The seed of the Persian Melon produces near Paris fruit + inferior to the poorest market kinds, but at Bordeaux yields delicious + fruit.<a name="NtA_667" href="#Nt_667"><sup>[667]</sup></a> Seed is + annually brought from Thibet to Kashmir,<a name="NtA_668" + href="#Nt_668"><sup>[668]</sup></a> and produces fruit weighing from four + to ten pounds, but plants raised from seed saved in Kashmir next year + give fruit weighing only from two to three pounds. It is well known that + American varieties of the Apple produce in their native land magnificent + and brightly-coloured fruit, but in England of poor quality and a dull + colour. In Hungary there are many varieties of the Kidney-bean, + remarkable for the beauty of their seeds, but the Rev. M. J. Berkeley<a + name="NtA_669" href="#Nt_669"><sup>[669]</sup></a> found that their + beauty could hardly ever be preserved in England, and in some cases the + colour was greatly changed. We have seen in the ninth chapter, with + respect to wheat, what a remarkable effect transportal from the North to + the South of France, and reversely, produced on the weight of the + grain.</p> + +</blockquote> + + <p>When man can perceive no change in plants or animals which have been + exposed to a new climate or to different treatment, insects can sometimes + perceive a marked change. The same species of cactus has been carried to + India from Canton, Manilla, Mauritius, and from the hot-houses of Kew, + and there is likewise a so-called native kind, formerly introduced from + South America; all these plants are alike in appearance, but the + cochineal insect flourishes only on the native kind, on which it thrives + prodigiously.<a name="NtA_670" href="#Nt_670"><sup>[670]</sup></a> + Humboldt remarks<a name="NtA_671" href="#Nt_671"><sup>[671]</sup></a> + that white men "born in the torrid zone walk barefoot with impunity in + the same apartment where a European, recently landed, is exposed to the + attacks of the <i>Pulex penetrans</i>." This insect, the too well-known + chigoe, must therefore be able to distinguish what the most delicate + chemical analysis fails to distinguish, namely, a difference between the + blood or tissues of a European and those of a white man born in the + country. But the discernment of the chigoe is not so surprising as it at + first appears; for <!-- Page 276 --><span class="pagenum"><a + name="page276"></a>{276}</span>according to Liebig<a name="NtA_672" + href="#Nt_672"><sup>[672]</sup></a> the blood of men with different + complexions, though inhabiting the same country, emits a different + odour.</p> + +<blockquote class="b1n"> + + <p>Diseases peculiar to certain localities, heights, or climates, may be + here briefly noticed, as showing the influence of external circumstances + on the human body. Diseases confined to certain races of man do not + concern us, for the constitution of the race may play the more important + part, and this may have been determined by unknown causes. The Plica + Polonica stands, in this respect, in a nearly intermediate position; for + it rarely affects Germans, who inhabit the neighbourhood of the Vistula, + where so many Poles are grievously affected; and on the other hand, it + does not affect Russians, who are said to belong to the same original + stock with the Poles.<a name="NtA_673" + href="#Nt_673"><sup>[673]</sup></a> The elevation of a district often + governs the appearance of diseases; in Mexico the yellow fever does not + extend above 924 mètres; and in Peru, people are affected with the + <i>verugas</i> only between 600 and 1600 mètres above the sea; many other + such cases could be given. A peculiar cutaneous complaint, called the + <i>Bouton d'Alep</i>, affects in Aleppo and some neighbouring districts + almost every native infant, and some few strangers; and it seems fairly + well established that this singular complaint depends on drinking certain + waters. In the healthy little island of St. Helena the scarlet-fever is + dreaded like the Plague; analogous facts have been observed in Chili and + Mexico.<a name="NtA_674" href="#Nt_674"><sup>[674]</sup></a> Even in the + different departments of France it is found that the various infirmities + which render the conscript unfit for serving in the army, prevail with + remarkable inequality, revealing, as Boudin observes, that many of them + are endemic, which otherwise would never have been suspected.<a + name="NtA_675" href="#Nt_675"><sup>[675]</sup></a> Any one who will study + the distribution of disease will be struck with surprise at what slight + differences in the surrounding circumstances govern the nature and + severity of the complaints by which man is at least temporarily + affected.</p> + +</blockquote> + + <p>The modifications as yet referred to have been extremely slight, and + in most cases have been caused, as far as we can judge, by equally slight + changes in the conditions. But can it be safely maintained that such + changed conditions, if acting during a long series of generations, would + not produce a marked effect? It is commonly believed that the people of + the United States differ in appearance from the parent Anglo-Saxon race; + and selection cannot have come into action within so short a period. A + good observer<a name="NtA_676" href="#Nt_676"><sup>[676]</sup></a> states + that a general absence of fat, <!-- Page 277 --><span class="pagenum"><a + name="page277"></a>{277}</span>a thin and elongated neck, stiff and lank + hair, are the chief characteristics. The change in the nature of the hair + is supposed to be caused by the dryness of the atmosphere. If immigration + into the United States were now stopped, who can say that the character + of the whole people would not be greatly modified in the course of two or + three thousand years?</p> + +<blockquote class="b1n"> + + <p>The direct and definite action of changed conditions, in + contradistinction to the accumulation of indefinite variations, seems to + me so important that I will give a large additional body of miscellaneous + facts. With plants, a considerable change of climate sometimes produces a + conspicuous result. I have given in detail in the ninth chapter the most + remarkable case known to me, namely, that in Germany several varieties of + maize brought from the hotter parts of America were transformed in the + course of only two or three generations. Dr. Falconer informs me that he + has seen the English Ribston-pippin apple, a Himalayan oak, Prunus and + Pyrus, all assume in the hotter parts of India a fastigate or pyramidal + habit; and this fact is the more interesting, as a Chinese tropical + species of Pyrus naturally has this habit of growth. Although in these + cases the changed manner of growth seems to have been directly caused by + the great heat, we know that many fastigate trees have originated in + their temperate homes. In the Botanic Gardens of Ceylon the apple-tree<a + name="NtA_677" href="#Nt_677"><sup>[677]</sup></a> "sends out numerous + runners under ground, which continually rise into small stems, and form a + growth around the parent-tree." The varieties of the cabbage which + produce heads in Europe fail to do so in certain tropical countries.<a + name="NtA_678" href="#Nt_678"><sup>[678]</sup></a> The <i>Rhododendron + ciliatum</i> produced at Kew flowers so much larger and paler-coloured + than those which it bears on its native Himalayan mountain, that Dr. + Hooker<a name="NtA_679" href="#Nt_679"><sup>[679]</sup></a> would hardly + have recognised the species by the flowers alone. Many similar facts with + respect to the colour and size of flowers could be given.</p> + + <p>The experiments of Vilmorin and Buckman on carrots and parsnips prove + that abundant nutriment produces a definite and inheritable effect on the + so-called roots, with scarcely any change in other parts of the plant. + Alum directly influences the colour of the flowers of the Hydrangea.<a + name="NtA_680" href="#Nt_680"><sup>[680]</sup></a> Dryness seems + generally to favour the hairyness or villosity of plants. Gärtner found + that hybrid Verbascums became extremely woolly when grown in pots. Mr. + Masters, on the other hand, states that the <i>Opuntia leucotricha</i> + "is well clothed with beautiful white hairs when grown in a damp heat; + but in a dry heat exhibits none of this peculiarity."<a name="NtA_681" + href="#Nt_681"><sup>[681]</sup></a> Slight variations of many kinds, not + worth specifying in detail, are retained only as <!-- Page 278 --><span + class="pagenum"><a name="page278"></a>{278}</span>long as plants are + grown in certain soils, of which Sageret<a name="NtA_682" + href="#Nt_682"><sup>[682]</sup></a> gives from his own experience some + instances. Odart, who insists strongly on the permanence of the varieties + of the grape, admits<a name="NtA_683" href="#Nt_683"><sup>[683]</sup></a> + that some varieties, when grown under a different climate or treated + differently, vary in an extremely slight degree, as in the tint of the + fruit and in the period of ripening. Some authors have denied that + grafting causes even the slightest difference in the scion; but there is + sufficient evidence that the fruit is sometimes slightly affected in size + and flavour, the leaves in duration, and the flowers in appearance.<a + name="NtA_684" href="#Nt_684"><sup>[684]</sup></a></p> + + <p>With animals there can be no doubt, from the facts given in the first + chapter, that European dogs deteriorate in India, not only in their + instincts but in structure; but the changes which they undergo are of + such a nature, that they may be partly due to reversion to a primitive + form, as in the case of feral animals. In parts of India the turkey + becomes reduced in size, "with the pendulous appendage over the beak + enormously developed."<a name="NtA_685" + href="#Nt_685"><sup>[685]</sup></a> We have seen how soon the wild duck, + when domesticated, loses its true character, from the effects of abundant + or changed food, or from taking little exercise. From the direct action + of a humid climate and poor pasture the horse rapidly decreases in size + in the Falkland Islands. From information which I have received, this + seems likewise to be the case to a certain extent with sheep in + Australia.</p> + + <p>Climate definitely influences the hairy covering of animals; in the + West Indies a great change is produced in the fleece of sheep, in about + three generations. Dr. Falconer states<a name="NtA_686" + href="#Nt_686"><sup>[686]</sup></a> that the Thibet mastiff and goat, + when brought down from the Himalaya to Kashmir, lose their fine wool. At + Angora not only goats, but shepherd-dogs and cats, have fine fleecy hair, + and Mr. Ainsworth<a name="NtA_687" href="#Nt_687"><sup>[687]</sup></a> + attributes the thickness of the fleece to the severe winters, and its + silky lustre to the hot summers. Burnes states positively<a + name="NtA_688" href="#Nt_688"><sup>[688]</sup></a> that the Karakool + sheep lose their peculiar black curled fleeces when removed into any + other country. Even within the limits of England, I have been assured + that with two breeds of sheep the wool was slightly changed by the flocks + being pastured in different localities.<a name="NtA_689" + href="#Nt_689"><sup>[689]</sup></a> It has been asserted on good + authority<a name="NtA_690" href="#Nt_690"><sup>[690]</sup></a> that + horses kept during several years in the deep coal-mines of Belgium become + covered with velvety hair, almost like that on the mole. These cases + probably stand in close relation to the natural change of coat in winter + and summer. Naked varieties of several domestic animals have occasionally + appeared; but there is no reason to <!-- Page 279 --><span + class="pagenum"><a name="page279"></a>{279}</span>believe that this is in + any way related to the nature of the climate to which they have been + exposed.<a name="NtA_691" href="#Nt_691"><sup>[691]</sup></a></p> + + <p>It appears at first sight probable that the increased size, the + tendency to fatten, the early maturity and altered forms of our improved + cattle, sheep, and pigs, have directly resulted from their abundant + supply of food. This is the opinion of many competent judges, and + probably is to a great extent true. But as far as form is concerned, we + must not overlook the equal or more potent influence of lessened use on + the limbs and lungs. We see, moreover, as far as size is concerned, that + selection is apparently a more powerful agent than a large supply of + food, for we can thus only account for the existence, as remarked to me + by Mr. Blyth, of the largest and smallest breeds of sheep in the same + country, of Cochin-China fowls and Bantams, of small Tumbler and large + Runt pigeons, all kept together and supplied with abundant nourishment. + Nevertheless there can be little doubt that our domesticated animals have + been modified, independently of the increased or lessened use of parts, + by the conditions to which they have been subjected, without the aid of + selection. For instance, Prof. Rütimeyer<a name="NtA_692" + href="#Nt_692"><sup>[692]</sup></a> shows that the bones of all + domesticated quadrupeds can be distinguished from those of wild animals + by the state of their surface and general appearance. It is scarcely + possible to read Nathusius's excellent 'Vorstudien,'<a name="NtA_693" + href="#Nt_693"><sup>[693]</sup></a> and doubt that, with the highly + improved races of the pig, abundant food has produced a conspicuous + effect on the general form of the body, on the breadth of the head and + face, and even on the teeth. Nathusius rests much on the case of a purely + bred Berkshire pig, which when two months old became diseased in its + digestive organs, and was preserved for observation until nineteen months + old; at this age it had lost several characteristic features of the + breed, and had acquired a long, narrow head, of large size relatively to + its small body, and elongated legs. But in this case and in some others + we ought not to assume that, because certain characters are lost, perhaps + through reversion, under one course of treatment, therefore that they had + been at first directly produced by an opposite course.</p> + + <p>In the case of the rabbit, which has become feral on the island of + Porto Santo, we are at first strongly tempted to attribute the whole + change—the greatly reduced size, the altered tints of the fur, and + the loss of certain characteristic marks—to the definite action of + the new conditions to which it has been exposed. But in all such cases we + have to consider in addition the tendency to reversion to progenitors + more or less remote, and the natural selection of the finest shades of + difference.</p> + + <p>The nature of the food sometimes either definitely induces certain + peculiarities, or stands in some close relation with them. Pallas long + ago asserted that the fat-tailed sheep of Siberia degenerated and lost + their enormous tails when removed from certain saline pastures; and + recently <!-- Page 280 --><span class="pagenum"><a + name="page280"></a>{280}</span>Erman<a name="NtA_694" + href="#Nt_694"><sup>[694]</sup></a> states that this occurs with the + Kirgisian sheep when brought to Orenburgh.</p> + + <p>It is well known that hemp-seed causes bullfinches and certain other + birds to become black. Mr. Wallace has communicated to me some much more + remarkable facts of the same nature. The natives of the Amazonian region + feed the common green parrot (<i>Chrysotis festiva</i>, Linn.) with the + fat of large Siluroid fishes, and the birds thus treated become + beautifully variegated with red and yellow feathers. In the Malayan + archipelago, the natives of Gilolo alter in an analogous manner the + colours of another parrot, namely, the <i>Lorius garrulus</i>, Linn., and + thus produce the <i>Lori rajah</i> or King-Lory. These parrots in the + Malay Islands and South America, when fed by the natives on natural + vegetable food, such as rice and plantains, retain their proper colours. + Mr. Wallace has, also, recorded<a name="NtA_695" + href="#Nt_695"><sup>[695]</sup></a> a still more singular fact. "The + Indians (of S. America) have a curious art by which they change the + colours of the feathers of many birds. They pluck out those from the part + they wish to paint, and inoculate the fresh wound with the milky + secretion from the skin of a small toad. The feathers grow of a brilliant + yellow colour, and on being plucked out, it is said, grow again of the + same colour without any fresh operation."</p> + + <p>Bechstein<a name="NtA_696" href="#Nt_696"><sup>[696]</sup></a> does + not entertain any doubt that seclusion from light affects, at least + temporarily, the colours of cage-birds.</p> + + <p>It is well known that the shells of land-mollusca are affected by the + abundance of lime in different districts. Isidore Geoffroy St. Hilaire<a + name="NtA_697" href="#Nt_697"><sup>[697]</sup></a> gives the case of + <i>Helix lactea</i>, which has recently been carried from Spain to the + South of France and to the Rio Plata, and in both these countries now + presents a distinct appearance, but whether this has resulted from food + or climate is not known. With respect to the common oyster, Mr. F. + Buckland informs me that he can generally distinguish the shells from + different districts; young oysters brought from Wales and laid down in + beds where "<i>natives</i>" are indigenous, in the short space of two + months begin to assume the "native" character. M. Costa<a name="NtA_698" + href="#Nt_698"><sup>[698]</sup></a> has recorded a much more remarkable + case of the same nature, namely, that young shells taken from the shores + of England and placed in the Mediterranean, at once altered their manner + of growth and formed prominent diverging rays, like those on the shells + of the proper Mediterranean oyster. The same individual shell, showing + both forms of growth, was exhibited before a society in Paris. Lastly, it + is well known that caterpillars fed on different food sometimes either + themselves acquire a different colour or produce moths different in + colour.<a name="NtA_699" href="#Nt_699"><sup>[699]</sup></a></p> + +<p><!-- Page 281 --><span class="pagenum"><a name="page281"></a>{281}</span></p> + + <p>It would be travelling beyond my proper limits here to discuss how far + organic beings in a state of nature are definitely modified by changed + conditions. In my 'Origin of Species' I have given a brief abstract of + the facts bearing on this point, and have shown the influence of light on + the colours of birds, and of residence near the sea on the lurid tints of + insects, and on the succulency of plants. Mr. Herbert Spencer<a + name="NtA_700" href="#Nt_700"><sup>[700]</sup></a> has recently discussed + with much ability this whole subject on broad and general grounds. He + argues, for instance, that with all animals the external and internal + tissues are differently acted on by the surrounding conditions, and they + invariably differ in intimate structure. So again the upper and lower + surfaces of true leaves, as well as of stems and petioles, when these + assume the function and occupy the position of leaves, are differently + circumstanced with respect to light, &c., and apparently in + consequence differ in structure. But, as Mr. Herbert Spencer admits, it + is most difficult in all such cases to distinguish between the effects of + the definite action of physical conditions and the accumulation through + natural selection of inherited variations which are serviceable to the + organism, and which have arisen independently of the definite action of + these conditions.</p> + +</blockquote> + + <p>Although we are not here concerned with organic beings in a state of + nature, yet I may call attention to one case. Mr. Meehan,<a + name="NtA_701" href="#Nt_701"><sup>[701]</sup></a> in a remarkable paper, + compares twenty-nine kinds of American trees, belonging to various + orders, with their nearest European allies, all grown in close proximity + in the same garden and under as nearly as possible the same conditions. + In the American species Mr. Meehan finds, with the rarest exceptions, + that the leaves fall earlier in the season, and assume before falling a + brighter tint; that they are less deeply toothed or serrated; that the + buds are smaller; that the trees are more diffuse in growth and have + fewer branchlets; and, lastly, that the seeds are smaller—all in + comparison with the corresponding European species. Now, considering that + these trees belong to distinct orders, it is out of the question that the + peculiarities just specified should have been inherited in the one + continent from one progenitor, and in the other from another progenitor; + and considering that the trees inhabit widely different stations, these + peculiarities can hardly be supposed to be of any special <!-- Page 282 + --><span class="pagenum"><a name="page282"></a>{282}</span>service to the + two series in the Old and New Worlds; therefore these peculiarities + cannot have been naturally selected. Hence we are led to infer that they + have been definitely caused by the long-continued action of the different + climate of the two continents on the trees.</p> + + <p><i>Galls.</i>—Another class of facts, not relating to cultivated + plants, deserves attention. I allude to the production of galls. Every + one knows the curious, bright-red, hairy productions on the wild + rose-tree, and the various different galls produced by the oak. Some of + the latter resemble fruit, with one face as rosy as the rosiest apple. + These bright colours can be of no service either to the gall-forming + insect or to the tree, and probably are the direct result of the action + of the light, in the same manner as the apples of Nova Scotia or Canada + are brighter coloured than English apples. The strongest upholder of the + doctrine that organic beings are created beautiful to please mankind + would not, I presume, extend this view to galls. According to Osten + Sacken's latest revision, no less than fifty-eight kinds of galls are + produced on the several species of oak, by Cynips with its sub-genera; + and Mr. B. D. Walsh<a name="NtA_702" href="#Nt_702"><sup>[702]</sup></a> + states that he can add many others to the list. One American species of + willow, the <i>Salix humilis</i>, bears ten distinct kinds of galls. The + leaves which spring from the galls of various English willows differ + completely in shape from the natural leaves. The young shoots of junipers + and firs, when punctured by certain insects, yield monstrous growths like + flowers and cones; and the flowers of some plants become from the same + cause wholly changed in appearance. Galls are produced in every quarter + of the world; of several sent to me by Mr. Thwaites from Ceylon, some + were as symmetrical as a composite flower when in bud, others smooth and + spherical like a berry; some protected by long spines, others clothed + with yellow wool formed of long cellular hairs, others with regularly + tufted hairs. In some galls the internal structure is simple, but in + others it is highly complex; thus M. Lucaze-Duthiers<a name="NtA_703" + href="#Nt_703"><sup>[703]</sup></a> has figured in the common ink-gall no + less than seven concentric layers, composed of distinct tissue, <!-- Page + 283 --><span class="pagenum"><a name="page283"></a>{283}</span>namely, + the epidermic, sub-epidermic, spongy, intermediate, and the hard + protective layer formed of curiously thickened woody cells, and, lastly, + the central mass abounding with starch-granules on which the larvæ + feed.</p> + + <p>Galls are produced by insects of various orders, but the greater + number by species of Cynips. It is impossible to read M. Lucaze-Duthier's + discussion and doubt that the poisonous secretion of the insect causes + the growth of the gall, and every one knows how virulent is the poison + secreted by wasps and bees, which belong to the same order with Cynips. + Galls grow with extraordinary rapidity, and it is said that they attain + their full size in a few days;<a name="NtA_704" + href="#Nt_704"><sup>[704]</sup></a> it is certain that they are almost + completely developed before the larvæ are hatched. Considering that many + gall-insects are extremely small, the drop of secreted poison must be + excessively minute; it probably acts on one or two cells alone, which, + being abnormally stimulated, rapidly increase by a process of + self-division. Galls, as Mr. Walsh<a name="NtA_705" + href="#Nt_705"><sup>[705]</sup></a> remarks, afford good, constant, and + definite characters, each kind keeping as true to form as does any + independent organic being. This fact becomes still more remarkable when + we hear that, for instance, seven out of the ten different kinds of galls + produced on <i>Salix humilis</i> are formed by gall-gnats + (<i>Cecidomyidæ</i>) which, "though essentially distinct species, yet + resemble one another so closely that in almost all cases it is difficult, + and in some cases impossible, to distinguish the full-grown insects one + from the other."<a name="NtA_706" href="#Nt_706"><sup>[706]</sup></a> For + in accordance with a wide-spread analogy we may safely infer that the + poison secreted by insects so closely allied would not differ much in + nature; yet this slight difference is sufficient to induce widely + different results. In some few cases the same species of gall-gnat + produces on distinct species of willows galls which cannot be + distinguished; the <i>Cynips fecundatrix</i>, also, has been known to + produce on the Turkish oak, to which it is not properly attached, exactly + the same kind of gall as on the European oak.<a name="NtA_707" + href="#Nt_707"><sup>[707]</sup></a> These latter facts apparently prove + that the nature of the poison is a much more powerful <!-- Page 284 + --><span class="pagenum"><a name="page284"></a>{284}</span>agent in + determining the form of the gall than the specific character of the tree + which is acted on.</p> + + <p>As the poisonous secretion of insects belonging to various orders has + the special power of affecting the growth of various plants;—as a + slight difference in the nature of the poison suffices to produce widely + different results;—and lastly, as we know that the chemical + compounds secreted by plants are eminently liable to be modified by + changed conditions of life, we may believe it possible that various parts + of a plant might be modified through the agency of its own altered + secretions. Compare, for instance, the mossy and viscid calyx of a + moss-rose, which suddenly appears through bud-variation on a + Provence-rose, with the gall of red moss growing from the inoculated leaf + of a wild rose, with each filament symmetrically branched like a + microscopical spruce-fir, bearing a glandular tip and secreting + odoriferous gummy matter.<a name="NtA_708" + href="#Nt_708"><sup>[708]</sup></a> Or compare, on the one hand, the + fruit of the peach, with its hairy skin, fleshy covering, hard shell and + kernel, and on the other hand one of the more complex galls with its + epidermic, spongy, and woody layers, surrounding tissue loaded with + starch granules. These normal and abnormal structures manifestly present + a certain degree of resemblance. Or, again, reflect on the cases above + given of parrots which have had their plumage brightly decorated through + some change in their blood, caused by having been fed on certain fishes, + or locally inoculated with the poison of a toad. I am far from wishing to + maintain that the moss-rose or the hard shell of the peach-stone or the + bright colours of birds are actually due to any chemical change in the + sap or blood; but these cases of galls and of parrots are excellently + adapted to show us how powerfully and singularly external agencies may + affect structure. With such facts before us, we need feel no surprise at + the appearance of any modification in any organic being.</p> + +<blockquote class="b1n"> + + <p>I may, also, here allude to the remarkable effects which parasitic + fungi sometimes produce on plants. Reissek<a name="NtA_709" + href="#Nt_709"><sup>[709]</sup></a> has described a Thesium, affected by + an Œcidium, which was greatly modified, and assumed some of the + <!-- Page 285 --><span class="pagenum"><a + name="page285"></a>{285}</span>characteristic features of certain allied + species, or even genera. Suppose, says Reissek, "the condition originally + caused by the fungus to become constant in the course of time, the plant + would, if found growing wild, be considered as a distinct species or even + as belonging to a new genus." I quote this remark to show how profoundly, + yet in how natural a manner, this plant must have been modified by the + parasitic fungus.</p> + +</blockquote> + +<p class="cenhead"><i>Facts and Considerations opposed to the belief that the Conditions +of Life act in a potent manner in causing definite Modifications +of Structure.</i></p> + + <p>I have alluded to the slight differences in species when naturally + living in distinct countries under different conditions; and such + differences we feel at first inclined, probably to a limited extent with + justice, to attribute to the definite action of the surrounding + conditions. But it must be borne in mind that there are a far greater + number of animals and plants which range widely and have been exposed to + great diversities of conditions, yet remain nearly uniform in character. + Some authors, as previously remarked, account for the varieties of our + culinary and agricultural plants by the definite action of the conditions + to which they have been exposed in the different parts of Great Britain; + but there are about 200 plants<a name="NtA_710" + href="#Nt_710"><sup>[710]</sup></a> which are found in every single + English county; these plants must have been exposed for an immense period + to considerable differences of climate and soil, yet do not differ. So, + again, some birds, insects, other animals, and plants range over large + portions of the world, yet retain the same character.</p> + +<blockquote class="b1n"> + + <p>Notwithstanding the facts previously given on the occurrence of highly + peculiar local diseases and on the strange modifications of structure in + plants caused by the inoculated poison of insects, and other analogous + cases; still there are a multitude of variations—such as the + modified skull of the niata ox and bulldog, the long horns of Caffre + cattle, the conjoined toes of the solid-hoofed swine, the immense crest + and protuberant skull of Polish fowls, the crop of the pouter-pigeon, and + a host of other such cases—which we can hardly attribute to the + definite action, in the sense before specified, of the external + conditions of life. No doubt in every case there must have been some + exciting cause; but as we see innumerable individuals exposed to nearly + the same conditions, and one alone is affected, we may conclude that the + constitution of the individual is of far higher <!-- Page 286 --><span + class="pagenum"><a name="page286"></a>{286}</span>importance than the + conditions to which it has been exposed. It seems, indeed, to be a + general rule that conspicuous variations occur rarely, and in one + individual alone out of many thousands, though all may have been exposed, + as far as we can judge, to nearly the same conditions. As the most + strongly marked variations graduate insensibly into the most trifling, we + are led by the same train of thought to attribute each slight variation + much more to innate differences of constitution, however caused, than to + the definite action of the surrounding conditions.</p> + + <p>We are led to the same conclusion by considering the cases, formerly + alluded to, of fowls and pigeons, which have varied and will no doubt go + on varying in directly opposite ways, though kept during many generations + under nearly the same conditions. Some, for instance, are born with their + beaks, wings, tails, legs, &c., a little longer, and others with + these same parts a little shorter. By the long-continued selection of + such slight individual differences, which occur in birds kept in the same + aviary, widely different races could certainly be formed; and + long-continued selection, important as is the result, does nothing but + preserve the variations which appear to us to arise spontaneously.</p> + + <p>In these cases we see that domesticated animals vary in an indefinite + number of particulars, though treated as uniformly as is possible. On the + other hand, there are instances of animals and plants, which, though + exposed to very different conditions, both under nature and + domestication, have varied in nearly the same manner. Mr. Layard informs + me that he has observed amongst the Caffres of South Africa a dog + singularly like an arctic Esquimaux dog. Pigeons in India present nearly + the same wide diversities of colour as in Europe; and I have seen + chequered and simply barred pigeons, and pigeons with blue and white + loins, from Sierra Leone, Madeira, England, and India. New varieties of + flowers are continually raised in different parts of Great Britain, but + many of these are found by the judges at our exhibitions to be almost + identical with old varieties. A vast number of new fruit-trees and + culinary vegetables have been produced in North America: these differ + from European varieties in the same general manner as the several + varieties raised in Europe differ from each other; and no one has ever + pretended that the climate of America has given to the many American + varieties any general character by which they can be recognised. + Nevertheless, from the facts previously advanced on the authority of Mr. + Meehan with respect to American and European forest-trees, it would be + rash to affirm that varieties raised in the two countries would not in + the course of ages assume a distinctive character. Mr. Masters has + recorded a striking fact<a name="NtA_711" + href="#Nt_711"><sup>[711]</sup></a> bearing on this subject: he raised + numerous plants of <i>Hybiscus Syriacus</i> from seed collected in South + Carolina and the Holy Land, where the parent-plants must have been + exposed to considerably different conditions; yet the seedlings from both + localities broke into two similar strains, one with obtuse leaves and + purple or crimson flowers, and the other with elongated leaves and more + or less pink flowers.</p> + +<p><!-- Page 287 --><span class="pagenum"><a name="page287"></a>{287}</span></p> + + <p>We may, also, infer the prepotent influence of the constitution of the + organism over the definite action of the conditions of life, from the + several cases given in the earlier chapters of parallel series of + varieties,—an important subject, hereafter to be more fully + discussed. Sub-varieties of the several kinds of wheat, gourds, peaches, + and other plants, and to a certain limited extent sub-varieties of the + fowl, pigeon, and dog, have been shown either to resemble or to differ + from each other in a closely corresponding and parallel manner. In other + cases, a variety of one species resembles a distinct species; or the + varieties of two distinct species resemble each other. Although these + parallel resemblances no doubt often result from reversion to the former + characters of a common progenitor; yet in other cases, when new + characters first appear, the resemblance must be attributed to the + inheritance of a similar constitution, and consequently to a tendency to + vary in the same manner. We see something of a similar kind in the same + monstrosity appearing and reappearing many times in the same animal, and, + as Dr. Maxwell Masters has remarked to me, in the same plant.</p> + +</blockquote> + + <p>We may at least conclude thus far, that the amount of modification + which animals and plants have undergone under domestication, does not + correspond with the degree to which they have been subjected to changed + circumstances. As we know the parentage of domesticated birds far better + than of most quadrupeds, we will glance through the list. The pigeon has + varied in Europe more than almost any other bird; yet it is a native + species, and has not been exposed to any extraordinary change of + conditions. The fowl has varied equally, or almost equally, with the + pigeon, and is a native of the hot jungles of India. Neither the peacock, + a native of the same country, nor the guinea-fowl, an inhabitant of the + dry deserts of Africa, has varied at all, or only in colour. The turkey, + from Mexico, has varied but little. The duck, on the other hand, a native + of Europe, has yielded some well-marked races; and as this is an aquatic + bird, it must have been subjected to a far more serious change in its + habits than the pigeon or even the fowl, which nevertheless have varied + in a much higher degree. The goose, a native of Europe and aquatic like + the duck, has varied less than any other domesticated bird, except the + peacock.</p> + + <p>Bud-variation is, also, important under our present point of view. In + some few cases, as when all the eyes or buds on the same tuber of the + potato, or all the fruit on the same plum-tree, or all the flowers on the + same plant, have suddenly varied in the same manner, it might be argued + that the <!-- Page 288 --><span class="pagenum"><a + name="page288"></a>{288}</span>variation had been definitely caused by + some change in the conditions to which the plants had been exposed; yet, + in other cases, such an admission is extremely difficult. As new + characters sometimes appear by bud-variation, which do not occur in the + parent-species or in any allied species, we may reject, at least in these + cases, the idea that they are due to reversion. Now it is well worth + while to reflect maturely on some striking case of bud-variation, for + instance that of the peach. This tree has been cultivated by the million + in various parts of the world, has been treated differently, grown on its + own roots and grafted on various stocks, planted as a standard, against a + wall, and under glass; yet each bud of each sub-variety keeps true to its + kind. But occasionally, at long intervals of time, a tree in England, or + under the widely-different climate of Virginia, produces a single bud, + and this yields a branch which ever afterwards bears nectarines. + Nectarines differ, as every one knows, from peaches in their smoothness, + size, and flavour; and the difference is so great, that some botanists + have maintained that they are specifically distinct. So permanent are the + characters thus suddenly acquired, that a nectarine produced by + bud-variation has propagated itself by seed. To guard against the + supposition that there is some fundamental distinction between bud and + seminal variation, it is well to bear in mind that nectarines have + likewise been produced from the stone of the peach; and, reversely, + peaches from the stone of the nectarine. Now is it possible to conceive + external conditions more closely alike than those to which the buds on + the same tree are exposed? Yet one bud alone, out of the many thousands + borne by the same tree, has suddenly without any apparent cause produced + a nectarine. But the case is even stronger than this, for the same + flower-bud has yielded a fruit, one-half or one-quarter a nectarine, and + the other half or three-quarters a peach. Again, seven or eight varieties + of the peach have yielded by bud-variation nectarines: the nectarines + thus produced, no doubt, differ a little from each other; but still they + are nectarines. Of course there must be some cause, internal or external, + to excite the peach-bud to change its nature; but I cannot imagine a + class of facts better adapted to force on our minds the conviction that + what we call the external conditions of life are quite insignificant in + <!-- Page 289 --><span class="pagenum"><a + name="page289"></a>{289}</span>relation to any particular variation, in + comparison with the organisation or constitution of the being which + varies.</p> + + <p>It is known from the labours of Geoffroy St. Hilaire, and recently + from those of Dareste and others, that eggs of the fowl, if shaken, + placed upright, perforated, covered in part with varnish, &c., + produce monstrous chickens. Now these monstrosities may be said to be + directly caused by such unnatural conditions, but the modifications thus + induced are not of a definite nature. An excellent observer, M. Camille + Dareste,<a name="NtA_712" href="#Nt_712"><sup>[712]</sup></a> remarks + "that the various species of monstrosities are not determined by specific + causes; the external agencies which modify the development of the embryo + act solely in causing a perturbation—a perversion in the normal + course of development." He compares the result to what we see in illness: + a sudden chill, for instance, affects one individual alone out of many, + causing either a cold, or sore-throat, rheumatism, or inflammation of the + lungs or pleura. Contagious matter acts in an analogous manner.<a + name="NtA_713" href="#Nt_713"><sup>[713]</sup></a> We may take a still + more specific instance: seven pigeons were struck by rattle-snakes;<a + name="NtA_714" href="#Nt_714"><sup>[714]</sup></a> some suffered from + convulsions; some had their blood coagulated, in others it was perfectly + fluid; some showed ecchymosed spots on the heart, others on the + intestines, &c.; others again showed no visible lesion in any organ. + It is well known that excess in drinking causes different diseases in + different men; but men living under a cold and tropical climate are + differently affected:<a name="NtA_715" + href="#Nt_715"><sup>[715]</sup></a> and in this case we see the definite + influence of opposite conditions. The foregoing facts apparently give us + as good an idea as we are likely for a long time to obtain, how in many + cases external conditions act directly, though not definitely, in causing + modifications of structure.</p> + +<hr class="short" /> + + <p><i>Summary.</i>—There can be no doubt, from the facts given in + the early part of this chapter, that extremely slight changes in <!-- + Page 290 --><span class="pagenum"><a name="page290"></a>{290}</span>the + conditions of life sometimes act in a definite manner on our already + variable domesticated productions; and, as the action of changed + conditions in causing general or indefinite variability is accumulative, + so it may be with their definite action. Hence it is possible that great + and definite modifications of structure may result from altered + conditions acting during a long series of generations. In some few + instances a marked effect has been produced quickly on all, or nearly + all, the individuals which have been exposed to some considerable change + of climate, food, or other circumstance. This has occurred, and is now + occurring, with European men in the United States, with European dogs in + India, with horses in the Falkland Islands, apparently with various + animals at Angora, with foreign oysters in the Mediterranean, and with + maize grown in Europe from tropical seed. We have seen that the chemical + compounds secreted by plants and the state of their tissues are readily + affected by changed conditions. In some cases a relation apparently + exists between certain characters and certain conditions, so that if the + latter be changed the character is lost—as with cultivated flowers, + with some few culinary plants, with the fruit of the melon, with + fat-tailed sheep, and other sheep having peculiar fleeces.</p> + + <p>The production of galls, and the change of plumage in parrots when fed + on peculiar food or when inoculated by the poison of a toad, prove to us + what great and mysterious changes in structure and colour may be the + definite result of chemical changes in the nutrient fluids or + tissues.</p> + + <p>We have also reason to believe that organic beings in a state of + nature may be modified in various definite ways by the conditions to + which they have been long exposed, as in the case of American trees in + comparison with their representatives in Europe. But in all such cases it + is most difficult to distinguish between the definite results of changed + conditions, and the accumulation through natural selection of serviceable + variations which have arisen independently of the nature of the + conditions. If, for instance, a plant had to be modified so as to become + fitted to inhabit a humid instead of an arid station, we have no reason + to believe that variations of the right kind would occur more frequently + if the parent-plant inhabited a station a little more <!-- Page 291 + --><span class="pagenum"><a name="page291"></a>{291}</span>humid than + usual. Whether the station was unusually dry or humid, variations + adapting the plant in a slight degree for directly opposite habits of + life would occasionally arise, as we have reason to believe from what we + know in other cases.</p> + + <p>In most, perhaps in all cases, the organisation or constitution of the + being which is acted on, is a much more important element than the nature + of the changed conditions, in determining the nature of the variation. We + have evidence of this in the appearance of nearly similar modifications + under different conditions, and of different modifications under + apparently nearly the same conditions. We have still better evidence of + this in closely parallel varieties being frequently produced from + distinct races, or even distinct species, and in the frequent recurrence + of the same monstrosity in the same species. We have also seen that the + degree to which domesticated birds have varied, does not stand in any + close relation with the amount of change to which they have been + subjected.</p> + + <p>To recur once again to bud-variations. When we reflect on the millions + of buds which many trees have produced, before some one bud has varied, + we are lost in wonder what the precise cause of each variation can be. + Let us recall the case given by Andrew Knight of the forty-year-old tree + of the yellow magnum bonum plum, an old variety which has been propagated + by grafts on various stocks for a very long period throughout Europe and + North America, and on which a single bud suddenly produced the red magnum + bonum. We should also bear in mind that distinct varieties, and even + distinct species,—as in the case of peaches, nectarines, and + apricots,—of certain roses and camellias,—although separated + by a vast number of generations from any progenitor in common, and + although cultivated under diversified conditions, have yielded by + bud-variation closely analogous varieties. When we reflect on these facts + we become deeply impressed with the conviction that in such cases the + nature of the variation depends but little on the conditions to which the + plant has been exposed, and not in any especial manner on its individual + character, but much more on the general nature or constitution, inherited + from some remote progenitor, of the whole group of allied beings to which + the plant belongs. We are thus driven to conclude that in most <!-- Page + 292 --><span class="pagenum"><a name="page292"></a>{292}</span>cases the + conditions of life play a subordinate part in causing any particular + modification; like that which a spark plays, when a mass of combustibles + bursts into flame—the nature of the flame depending on the + combustible matter, and not on the spark.</p> + + <p>No doubt each slight variation must have its efficient cause; but it + is as hopeless an attempt to discover the cause of each as to say why a + chill or a poison affects one man differently from another. Even with + modifications resulting from the definite action of the conditions of + life, when all or nearly all the individuals, which have been similarly + exposed, are similarly affected, we can rarely see the precise relation + between cause and effect. In the next chapter it will be shown that the + increased use or disuse of various organs, produces an inherited effect. + It will further be seen that certain variations are bound together by + correlation and other laws. Beyond this we cannot at present explain + either the causes or manner of action of Variation.</p> + + <p>Finally, as indefinite and almost illimitable variability is the usual + result of domestication and cultivation, with the same part or organ + varying in different individuals in different or even in directly + opposite ways; and as the same variation, if strongly pronounced, usually + recurs only after long intervals of time, any particular variation would + generally be lost by crossing, reversion, and the accidental destruction + of the varying individuals, unless carefully preserved by man. Hence, + although it must be admitted that new conditions of life do sometimes + definitely affect organic beings, it may be doubted whether well-marked + races have often been produced by the direct action of changed conditions + without the aid of selection either by man or nature.</p> + +<hr class="full" /> + +<p><!-- Page 293 --><span class="pagenum"><a name="page293"></a>{293}</span></p> + +<h3>CHAPTER XXIV.</h3> + +<p class="cenhead">LAWS OF VARIATION—USE AND DISUSE, ETC.</p> + +<blockquote class="b1n"> + + <p><span class="scac">NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE + ORGANISATION</span>—<span class="scac">ON THE EFFECTS OF THE + INCREASED USE AND DISUSE OF ORGANS</span>—<span + class="scac">CHANGED HABITS OF LIFE</span>—<span + class="scac">ACCLIMATISATION WITH ANIMALS AND PLANTS</span>—<span + class="scac">VARIOUS METHODS BY WHICH THIS CAN BE + EFFECTED</span>—<span class="scac">ARRESTS OF + DEVELOPMENT</span>—<span class="scac">RUDIMENTARY + ORGANS.</span></p> + +</blockquote> + + <p>In this and the two following chapters I shall discuss, as well as the + difficulty of the subject permits, the several laws which govern + Variability. These may be grouped under the effects of use and disuse, + including changed habits and acclimatisation—arrests of + development—correlated variation—the cohesion of homologous + parts—the variability of multiple parts—compensation of + growth—the position of buds with respect to the axis of the + plant—and lastly, analogous variation. These several subjects so + graduate into each other that their distinction is often arbitrary.</p> + + <p>It may be convenient first briefly to discuss that co-ordinating and + reparative power which is common, in a higher or lower degree, to all + organic beings, and which was formerly designated by physiologists as the + <i>nisus formativus</i>.</p> + +<blockquote class="b1n"> + + <p>Blumenbach and others<a name="NtA_716" + href="#Nt_716"><sup>[716]</sup></a> have insisted that the principle + which permits a Hydra, when cut into fragments, to develop itself into + two or more perfect animals, is the same with that which causes a wound + in the higher animals to heal by a cicatrice. Such cases as that of the + Hydra are evidently analogous with the spontaneous division or + fissiparous generation of the lowest animals, and likewise with the + budding of plants. Between these extreme cases and that of a mere + cicatrice we have every gradation. Spallanzani,<a name="NtA_717" + href="#Nt_717"><sup>[717]</sup></a> by cutting off the legs and tail of a + Salamander, got in the course of three months six crops of these members; + so that 687 perfect bones were reproduced by one animal during one + season. At whatever <!-- Page 294 --><span class="pagenum"><a + name="page294"></a>{294}</span>point the limb was cut off, the deficient + part, and no more, was exactly reproduced. Even with man, as we have seen + in the twelfth chapter, when treating of polydactylism, the entire limb + whilst in an embryonic state, and supernumerary digits, are occasionally, + though imperfectly, reproduced after amputation. When a diseased bone has + been removed, a new one sometimes "gradually assumes the regular form, + and all the attachments of muscles, ligaments, &c., become as + complete as before."<a name="NtA_718" + href="#Nt_718"><sup>[718]</sup></a></p> + + <p>This power of regrowth does not, however, always act perfectly: the + reproduced tail of a lizard differs in the forms of the scales from the + normal tail: with certain Orthopterous insects the large hind legs are + reproduced of smaller size:<a name="NtA_719" + href="#Nt_719"><sup>[719]</sup></a> the white cicatrice which in the + higher animals unites the edges of a deep wound is not formed of perfect + skin, for elastic tissue is not produced till long afterwards.<a + name="NtA_720" href="#Nt_720"><sup>[720]</sup></a> "The activity of the + <i>nisus formativus</i>," says Blumenbach, "is in an inverse ratio to the + age of the organised body." To this may be added that its power is + greater in animals the lower they are in the scale of organisation; and + animals low in the scale correspond with the embryos of higher animals + belonging to the same class. Newport's observations<a name="NtA_721" + href="#Nt_721"><sup>[721]</sup></a> afford a good illustration of this + fact, for he found that "myriapods, whose highest development scarcely + carries them beyond the larvæ of perfect insects, can regenerate limbs + and antennæ up to the time of their last moult;" and so can the larvæ of + true insects, but not the mature insect. Salamanders correspond in + development with the tadpoles or larvæ of the tailless Batrachians, and + both possess to a large extent the power of regrowth; but not so the + mature tailless Batrachians.</p> + + <p>Absorption often plays an important part in the repairs of injuries. + When a bone is broken, and does not unite, the ends are absorbed and + rounded, so that a false joint is formed; or if the ends unite, but + overlap, the projecting parts are removed.<a name="NtA_722" + href="#Nt_722"><sup>[722]</sup></a> But absorption comes into action, as + Virchow remarks, during the normal growth of bones; parts which are solid + during youth become hollowed out for the medullary tissue as the bone + increases in size. In trying to understand the many well-adapted cases of + regrowth when aided by absorption, we should remember that most parts of + the organisation, even whilst retaining the same form, undergo constant + renewal; so that a part which was not renewed would naturally be liable + to complete <span class="correction" title="Original reads `absortion'." + >absorption</span>.</p> + + <p>Some cases, usually classed under the so-called <i>nisus + formativus</i>, at first appear to come under a distinct head; for not + only are old structures reproduced, but structures which appear new are + formed. Thus, after inflammation "false membranes," furnished with + blood-vessels, lymphatics, and nerves, are developed; or a fœtus + escapes from the Fallopian tubes, and falls into the abdomen, "nature + pours out a quantity of plastic lymph, which forms itself into organised + membrane, richly supplied with blood-vessels," and the fœtus is + nourished for a time. In certain cases of <!-- Page 295 --><span + class="pagenum"><a name="page295"></a>{295}</span>hydrocephalus the open + and dangerous spaces in the skull are filled up with new bones, which + interlock by perfect serrated sutures.<a name="NtA_723" + href="#Nt_723"><sup>[723]</sup></a> But most physiologists, especially on + the Continent, have now given up the belief in plastic lymph or blastema, + and Virchow<a name="NtA_724" href="#Nt_724"><sup>[724]</sup></a> + maintains that every structure, new or old, is formed by the + proliferation of pre-existing cells. On this view false membranes, like + cancerous or other tumours, are merely abnormal developments of normal + growths; and we can thus understand how it is that they resemble + adjoining structures; for instance, that "false membrane in the serous + cavities acquires a covering of epithelium exactly like that which covers + the original serous membrane; adhesions of the iris may become black + apparently from the production of pigment-cells like those of the + uvea."<a name="NtA_725" href="#Nt_725"><sup>[725]</sup></a></p> + + <p>No doubt the power of reparation, though not always quite perfect, is + an admirable provision, ready for various emergencies, even for those + which occur only at long intervals of time.<a name="NtA_726" + href="#Nt_726"><sup>[726]</sup></a> Yet this power is not more wonderful + than the growth and development of every single creature, more especially + of those which are propagated by fissiparous generation. This subject has + been here noticed, because we may infer that, when any part or organ is + either greatly increased in size or wholly suppressed through variation + and continued selection, the co-ordinating power of the organisation will + continually tend to bring all the parts again into harmony with each + other.</p> + +</blockquote> + +<p class="cenhead"><i>On the Effects of the Increased Use and Disuse of Organs.</i></p> + + <p>It is notorious, and we shall immediately adduce proofs, that + increased use or action strengthens muscles, glands, sense-organs, + &c.; and that disuse, on the other hand, weakens them. I have not met + with any clear explanation of this fact in works on Physiology. Mr. + Herbert Spencer<a name="NtA_727" href="#Nt_727"><sup>[727]</sup></a> + maintains that when muscles are much used, or when intermittent pressure + is applied to the epidermis, an excess of nutritive matter exudes from + the vessels, and that this gives additional development to the adjoining + parts. That an increased flow of blood towards an organ leads to its + greater development is probable, if not certain. Mr. Paget<a + name="NtA_728" href="#Nt_728"><sup>[728]</sup></a> thus accounts for the + long, thick, and dark-coloured hair which occasionally grows, even in + young children, near old-standing inflamed surfaces or fractured bones. + When Hunter <!-- Page 296 --><span class="pagenum"><a + name="page296"></a>{296}</span>inserted the spur of a cock into the comb, + which is well supplied with blood-vessels, it grew in one case in a + spiral direction to a length of six inches, and in another case forward, + like a horn, so that the bird could not touch the ground with its beak. + But whether Mr. Herbert Spencer's view of the exudation of nutritive + matter due to increased movement and pressure, will fully account for the + augmented size of bones, ligaments, and especially of internal glands and + nerves, seems doubtful. According to the interesting observations of M. + Sedillot,<a name="NtA_729" href="#Nt_729"><sup>[729]</sup></a> when a + portion of one bone of the leg or fore-arm of an animal is removed and is + not replaced by growth, the associated bone enlarges till it attains a + bulk equal to that of the two bones, of which it has to perform the + functions. This is best exhibited in dogs in which the tibia has been + removed; the companion bone, which is naturally almost filiform and not + one-fifth the size of the other, soon acquires a size equal to or greater + than the tibia. Now, it is at first difficult to believe that increased + weight acting on a straight bone could, by alternately increased and + diminished pressure, cause nutritive matter to exude from the vessels + which permeate the periosteum. Nevertheless, the observations adduced by + Mr. Spencer,<a name="NtA_730" href="#Nt_730"><sup>[730]</sup></a> on the + strengthening of the bowed bones of rickety children, along their concave + sides, leads to the belief that this is possible.</p> + + <p>Mr. H. Spencer has also shown that the ascent of the sap in trees is + aided by the rocking movement caused by the wind; and the sap strengthens + the trunk "in proportion to the stress to be borne; since the more severe + and the more repeated the strains, the greater must be the exudation from + the vessels into the surrounding tissue, and the greater the thickening + of this tissue by secondary deposits."<a name="NtA_731" + href="#Nt_731"><sup>[731]</sup></a> But woody trunks may be formed of + hard tissue without their having been subjected to any movement, as we + see with ivy closely attached to old walls. In all these cases, it is + very difficult to disentangle the effects of long-continued selection + from those consequent on the increased action or movement of the part. + Mr. H. Spencer<a name="NtA_732" href="#Nt_732"><sup>[732]</sup></a> + acknowledges this difficulty, and gives as an instance the spines <!-- + Page 297 --><span class="pagenum"><a name="page297"></a>{297}</span>or + thorns of trees, and the shells of nuts. Here we have extremely hard + woody tissue without the possibility of any movement to cause exudation, + and without, as far as we can see, any other directly exciting cause; and + as the hardness of these parts is of manifest service to the plant, we + may look at the result as probably due to the selection of so-called + spontaneous variations. Every one knows that hard work thickens the + epidermis on the hands; and when we hear that with infants long before + their birth the epidermis is thicker on the palms and soles of the feet + than on any other part of the body, as was observed with admiration by + Albinus,<a name="NtA_733" href="#Nt_733"><sup>[733]</sup></a> we are + naturally inclined to attribute this to the inherited effects of + long-continued use or pressure. We are tempted to extend the same view + even to the hoofs of quadrupeds; but who will pretend to determine how + far natural selection may have aided in the formation of structures of + such obvious importance to the animal?</p> + +<blockquote class="b1n"> + + <p>That use strengthens the muscles may be seen in the limbs of artisans + who follow different trades; and when a muscle is strengthened, the + tendons, and the crests of bone to which they are attached, become + enlarged; and this must likewise be the case with the blood-vessels and + nerves. On the other hand, when a limb is not used, as by Eastern + fanatics, or when the nerve supplying it with nervous power is + effectually destroyed, the muscles wither. So again, when the eye is + destroyed the optic nerve becomes atrophied, sometimes even in the course + of a few months.<a name="NtA_734" href="#Nt_734"><sup>[734]</sup></a> The + Proteus is furnished with branchiæ as well as with lungs: and + Schreibers<a name="NtA_735" href="#Nt_735"><sup>[735]</sup></a> found + <span class="correction" title="Original reads `than'.">that</span> when + the animal was compelled to live in deep water the branchiæ were + developed to thrice their ordinary size, and the lungs were partially + atrophied. When, on the other hand, the animal was compelled to live in + shallow water, the lungs became larger and more vascular, whilst the + branchiæ disappeared in a more or less complete degree. Such + modifications as these are, however, of comparatively little value for + us, as we do not actually know that they tend to be inherited.</p> + + <p>In many cases there is reason to believe that the lessened use of + various organs has affected the corresponding parts in the offspring. But + there is no good evidence that this ever follows in the course of a + single generation. It appears, as in the case of general or indefinite + variability, that several generations must be subjected to changed habits + for any appreciable result. Our domestic fowls, ducks, and geese have + almost lost, not <!-- Page 298 --><span class="pagenum"><a + name="page298"></a>{298}</span>only in the individual but in the race, + their power of flight; for we do not see a chicken, when frightened, take + flight like a young pheasant. Hence I was led carefully to compare the + limb-bones of fowls, ducks, pigeons, and rabbits, with the same bones in + the wild parent-species. As the measurements and weights were fully given + in the earlier chapters, I need here only recapitulate the results. With + domestic pigeons, the length of the sternum, the prominence of its crest, + the length of the scapulæ and furcula, the length of the wings as + measured from tip to tip of the radius, are all reduced relatively to the + same parts in the wild pigeon. The wing and tail feathers, however, are + increased in length, but this may have as little connection with the use + of the wings or tail, as the lengthened hair on a dog with the amount of + exercise which the breed has habitually taken. The feet of pigeons, + except in the long-beaked races, are reduced in size. With fowls the + crest of the sternum is less prominent, and is often distorted or + monstrous; the wing-bones have become lighter relatively to the + leg-bones, and are apparently a little shorter in comparison with those + of the parent-form, the <i>Gallus bankiva</i>. With ducks, the crest of + the sternum is affected in the same manner as in the foregoing cases: the + furcula, coracoids, and scapulæ are all reduced in weight relatively to + the whole skeleton: the bones of the wings are shorter and lighter, and + the bones of the legs longer and heavier, relatively to each other, and + relatively to the whole skeleton, in comparison with the same bones in + the wild-duck. The decreased weight and size of the bones, in the + foregoing cases, is probably the indirect result of the reaction of the + weakened muscles on the bones. I failed to compare the feathers of the + wings of the tame and wild duck; but Gloger<a name="NtA_736" + href="#Nt_736"><sup>[736]</sup></a> asserts that in the wild duck the + tips of the wing-feathers reach almost to the end of the tail, whilst in + the domestic duck they often hardly reach to its base. He remarks, also, + on the greater thickness of the legs, and says that the swimming membrane + between the toes is reduced; but I was not able to detect this latter + difference.</p> + + <p>With the domesticated rabbit the body, together with the whole + skeleton, is generally larger and heavier than in the wild animal, and + the leg-bones are heavier in due proportion; but whatever standard of + comparison be taken, neither the leg-bones nor the scapulæ have increased + in length proportionally with the increased dimensions of the rest of the + skeleton. The skull has become in a marked manner narrower, and, from the + measurements of its capacity formerly given, we may conclude, that this + narrowness results from the decreased size of the brain, consequent on + the mentally inactive life led by these closely-confined animals.</p> + + <p>We have seen in the eighth chapter that silk-moths, which have been + kept during many centuries closely confined, emerge from their cocoons + with their wings distorted, incapable of flight, often greatly reduced in + size, or even, according to Quatrefages, quite rudimentary. This + condition of the wings may be largely owing to the same kind of + monstrosity which often affects wild Lepidoptera when artificially reared + from the cocoon; or it may <!-- Page 299 --><span class="pagenum"><a + name="page299"></a>{299}</span>be in part due to an inherent tendency, + which is common to the females of many Bombycidæ, to have their wings in + a more or less rudimentary state; but part of the effect may probably be + attributed to long-continued disuse.</p> + +</blockquote> + + <p>From the foregoing facts there can be no doubt that certain parts of + the skeleton in our anciently domesticated animals, have been modified in + length and weight by the effects of decreased or increased use; but they + have not been modified, as shown in the earlier chapters, in shape or + structure. We must, however, be cautious in extending this latter + conclusion to animals living a free life; for these will occasionally be + exposed during successive generations to the severest competition. With + wild animals it would be an advantage in the struggle for life that every + superfluous and useless detail of structure should be removed or + absorbed; and thus the reduced bones might ultimately become changed in + structure. With highly-fed domesticated animals, on the other hand, there + is no economy of growth; nor any tendency to the elimination of trifling + and superfluous details of structure.</p> + + <p>Turning now to more general observations, Nathusius has shown that, + with the improved races of the pig, the shortened legs and snout, the + form of the articular condyles of the occiput, and the position of the + jaws with the upper canine teeth projecting in a most anomalous manner in + front of the lower canines, may be attributed to these parts not having + been fully exercised. For the highly-cultivated races do not travel in + search of food, nor root up the ground with their ringed muzzles. These + modifications of structure, which are all strictly inherited, + characterise several improved breeds, so that they cannot have been + derived from any single domestic or wild stock.<a name="NtA_737" + href="#Nt_737"><sup>[737]</sup></a> With respect to cattle, Professor + Tanner has remarked that the lungs and liver in the improved breeds "are + found to be considerably reduced in size when compared with those + possessed by animals having perfect liberty;"<a name="NtA_738" + href="#Nt_738"><sup>[738]</sup></a> and the reduction of these organs + affects the general shape of the body. The cause of the reduced lungs in + highly-bred animals which take little exercise is <!-- Page 300 --><span + class="pagenum"><a name="page300"></a>{300}</span>obvious; and perhaps + the liver may be affected by the nutritious and artificial food on which + they largely subsist.</p> + +<blockquote class="b1n"> + + <p>It is well known that, when an artery is tied, the <span + class="correction" title="Original reads `anastomising', corrected by errata, page viii." + >anastomosing</span> branches, from being forced to transmit more blood, + increase in diameter; and this increase cannot be accounted for by mere + extension, as their coats gain in strength. Mr. Herbert Spencer<a + name="NtA_739" href="#Nt_739"><sup>[739]</sup></a> has argued that with + plants the flow of sap from the point of supply to the growing part first + elongates the cells in this line; and that the cells then become + confluent, thus forming the ducts; so that, on this view, the vessels in + plants are formed by the mutual reaction of the flowing sap and cellular + tissue. Dr. W. Turner has remarked,<a name="NtA_740" + href="#Nt_740"><sup>[740]</sup></a> with respect to the branches of + arteries, and likewise to a certain extent with nerves, that the great + principle of compensation frequently comes into play; for "when two + nerves pass to adjacent cutaneous areas, an inverse relation as regards + size may subsist between them; a deficiency in one may be supplied by an + increase in the other, and thus the area of the former may be trespassed + on by the latter nerve." But how far in these cases the difference in + size in the nerves and arteries is due to original variation, and how far + to increased use or action, is not clear.</p> + + <p>In reference to glands, Mr. Paget observes that "when one kidney is + destroyed the other often becomes much larger, and does double work."<a + name="NtA_741" href="#Nt_741"><sup>[741]</sup></a> If we compare the size + of the udders and their power of secretion in cows which have been long + domesticated, and in certain goats in which the udders nearly touch the + ground, with the size and power of secretion of these organs in wild or + half-domesticated animals, the difference is great. A good cow with us + daily yields more than five gallons, or forty pints of milk, whilst a + first-rate animal, kept, for instance, by the Damaras of South Africa,<a + name="NtA_742" href="#Nt_742"><sup>[742]</sup></a> "rarely gives more + than two or three pints of milk daily, and, should her calf be taken from + her, she absolutely refuses to give any." We may attribute the excellence + of our cows, and of certain goats, partly to the continued selection of + the best milking animals, and partly to the inherited effects of the + increased action, through man's art, of the secreting glands.</p> + + <p>It is notorious, as was remarked in the twelfth chapter, that + short-sight is inherited; and if we compare watchmakers or engravers + with, for instance, sailors, we can hardly doubt that vision continually + directed towards a near object permanently affects the structure of the + eye.</p> + + <p>Veterinarians are unanimous that horses become affected with spavins, + splints, ringbones, &c., from being shod, and from travelling on hard + roads, and they are almost equally unanimous that these injuries are + transmitted. Formerly horses were not shod in North Carolina, and it has + been asserted that they did not then suffer from these diseases of the + legs and feet.<a name="NtA_743" href="#Nt_743"><sup>[743]</sup></a></p> + +</blockquote> + +<p><!-- Page 301 --><span class="pagenum"><a name="page301"></a>{301}</span></p> + + <p>Our domesticated quadrupeds are all descended, as far as is known, + from species having erect ears; yet few kinds can be named, of which at + least one race has not drooping ears. Cats in China, horses in parts of + Russia, sheep in Italy and elsewhere, the guinea-pig in Germany, goats + and cattle in India, rabbits, pigs, and dogs in all long-civilised + countries, have dependent ears. With wild animals, which constantly use + their ears like funnels to catch every passing sound, and especially to + ascertain the direction whence it comes, there is not, as Mr. Blyth has + remarked, any species with drooping ears except the elephant. Hence the + incapacity to erect the ears is certainly in some manner the result of + domestication; and this incapacity has been attributed by various + authors<a name="NtA_744" href="#Nt_744"><sup>[744]</sup></a> to disuse, + for animals protected by man are not compelled habitually to use their + ears. Col. Hamilton Smith<a name="NtA_745" + href="#Nt_745"><sup>[745]</sup></a> states that in ancient effigies of + the dog, "with the exception of one Egyptian instance, no sculpture of + the earlier Grecian era produces representations of hounds with + completely drooping ears; those with them half pendulous are missing in + the most ancient; and this character increases, by degrees, in the works + of the Roman period." Godron also has remarked that "the pigs of the + ancient Egyptians had not their ears enlarged and pendent."<a + name="NtA_746" href="#Nt_746"><sup>[746]</sup></a> But it is remarkable + that the drooping of the ears, though probably the effect of disuse, is + not accompanied by any decrease in size; on the contrary, when we + remember that animals so different as fancy rabbits, certain Indian + breeds of the goat, our petted spaniels, bloodhounds, and other dogs, + have enormously elongated ears, it would appear as if disuse actually + caused an increase in length. With rabbits, the drooping of the much + elongated ears has affected even the structure of the skull.</p> + + <p>The tail of no wild animal, as remarked to me by Mr. Blyth, is curled; + whereas pigs and some races of dogs have their tails much curled. This + deformity, therefore, appears to be the result of domestication, but + whether in any way connected with the lessened use of the tail is + doubtful.</p> + +<p><!-- Page 302 --><span class="pagenum"><a name="page302"></a>{302}</span></p> + + <p>The epidermis on our hands is easily thickened, as every one knows, by + hard work. In a district of Ceylon the sheep have "horny callosities that + defend their knees, and which arise from their habit of kneeling down to + crop the short herbage, and this distinguishes the Jaffna flocks from + those of other portions of the island;" but it is not stated whether this + peculiarity is inherited.<a name="NtA_747" + href="#Nt_747"><sup>[747]</sup></a></p> + + <p>The mucous membrane which lines the stomach is continuous with the + external skin of the body; therefore it is not surprising that its + texture should be affected by the nature of the food consumed, but other + and more interesting changes likewise follow. Hunter long ago observed + that the muscular coat of the stomach of a gull (<i>Larus + tridactylus</i>) which had been fed for a year chiefly on grain was + thickened; and, according to Dr. Edmondston, a similar change + periodically occurs in the Shetland Islands in the stomach of the + <i>Larus argentatus</i>, which in the spring frequents the corn-fields + and feeds on the seed. The same careful observer has noticed a great + change in the stomach of a raven which had been long fed on vegetable + food. In the case of an owl (<i>Strix grallaria</i>) similarly treated, + Menetries states that the form of the stomach was changed, the inner coat + became leathery, and the liver increased in size. Whether these + modifications in the digestive organs would in the course of generations + become inherited is not known.<a name="NtA_748" + href="#Nt_748"><sup>[748]</sup></a></p> + + <p>The increased or diminished length of the intestines, which apparently + results from changed diet, is a more remarkable case, because it is + characteristic of certain animals in their domesticated condition, and + therefore must be inherited. The complex absorbent system, the + blood-vessels, nerves, and muscles, are necessarily all modified together + with the intestines. According to Daubenton, the intestines of the + domestic cat are one-third longer than those of the wild cat of Europe; + and although this species is not the parent-stock of the domestic animal, + yet, as Isidore Geoffroy has remarked, the several species <!-- Page 303 + --><span class="pagenum"><a name="page303"></a>{303}</span>of cats are so + closely allied that the comparison is probably a fair one. The increased + length appears to be due to the domestic cat being less strictly + carnivorous in its diet than any wild feline species; I have seen a + French kitten eating vegetables as readily as meat. According to Cuvier, + the intestines of the domesticated pig exceed greatly in proportionate + length those of the wild boar. In the tame and wild rabbit the change is + of an opposite nature, and probably results from the nutritious food + given to the tame rabbit.<a name="NtA_749" + href="#Nt_749"><sup>[749]</sup></a></p> + +<hr class="short" /> + + <p><i>Changed Habits of Life, independently of the Use or Disuse of + particular Organs.</i>—This subject, as far as the mental powers of + animals are concerned, so blends into instinct, on which I shall treat in + a future work, that I will here only remind the reader of the many cases + which occur under domestication, and which are familiar to every + one—for instance the tameness of our animals—the pointing or + retrieving of dogs—their not attacking the smaller animals kept by + man—and so forth. How much of these changes ought to be attributed + to inherited habit, and how much to the selection of individuals which + have varied in the desired manner, irrespectively of the special + circumstances under which they have been kept, can seldom be told. We + have already seen that animals may be habituated to a changed diet; but a + few additional instances may here be given.</p> + + <p>In the Polynesian Islands and in China the dog is fed exclusively on + vegetable matter, and the taste for this kind of food is to a certain + extent inherited.<a name="NtA_750" href="#Nt_750"><sup>[750]</sup></a> + Our sporting dogs will not touch the bones of game birds, whilst other + dogs devour them with greediness. In some parts of the world sheep have + been largely fed on fish. The domestic hog is fond of barley, the wild + boar is said to disdain it; and the disdain is partially inherited, for + some young wild pigs bred in captivity showed an aversion for this grain, + whilst others of the same brood relished it.<a name="NtA_751" + href="#Nt_751"><sup>[751]</sup></a> One of my relations bred some young + pigs from <!-- Page 304 --><span class="pagenum"><a + name="page304"></a>{304}</span>a Chinese sow by a wild Alpine boar; they + lived free in the park, and were so tame that they came to the house to + be fed; but they would not touch swill, which was devoured by the other + pigs. An animal when once accustomed to an unnatural diet, which can + generally be effected only during youth, dislikes its proper food, as + Spallanzani found to be the case with a pigeon which had been long fed on + meat. Individuals of the same species take to new food with different + degrees of readiness; one horse, it is stated, soon learned to eat meat, + whilst another would have perished from hunger rather than have partaken + of it.<a name="NtA_752" href="#Nt_752"><sup>[752]</sup></a></p> + + <p>The caterpillars of the <i>Bombyx hesperus</i> feed in a state of + nature on the leaves of the <i>Café diable</i>, but, after having been + reared on the Ailanthus, they would not touch the <i>Café diable</i>, and + actually died of hunger.<a name="NtA_753" + href="#Nt_753"><sup>[753]</sup></a></p> + + <p>It has been found possible to accustom marine fish to live in fresh + water; but as such changes in fish, and other marine animals, have been + chiefly observed in a state of nature, they do not properly belong to our + present subject. The period of gestation and of maturity, as shown in the + earlier chapters,—the season and the frequency of the act of + breeding,—have all been greatly modified under domestication. With + the Egyptian goose the rate of change in the season has been recorded.<a + name="NtA_754" href="#Nt_754"><sup>[754]</sup></a> The wild drake pairs + with one female, the domestic drake is polygamous. Certain breeds of + fowls have lost the habit of incubation. The paces of the horse, and the + manner of flight in certain breeds of the pigeon, have been modified, and + are inherited. The voice differs much in certain fowls and pigeons. Some + breeds are clamorous and others silent, as in the Call and common duck, + or in the Spitz and pointer dog. Every one knows how dogs differ from + each other in their manner of hunting, and in their ardour after + different kinds of game or vermin.</p> + + <p>With plants the period of vegetation is easily changed and is + inherited, as in the case of summer and winter wheat, barley, <!-- Page + 305 --><span class="pagenum"><a name="page305"></a>{305}</span>and + vetches; but to this subject we shall immediately return under + acclimatisation. Annual plants sometimes become perennial under a new + climate, as I hear from Dr. Hooker is the case with the stock and + mignonette in Tasmania. On the other hand, perennials sometimes become + annuals, as with the Ricinus in England, and as, according to Captain + Mangles, with many varieties of the heartsease. Von Berg<a name="NtA_755" + href="#Nt_755"><sup>[755]</sup></a> raised from seed of <i>Verbascum + phœnicium</i>, which is usually a biennial, both annual and + perennial varieties. Some deciduous bushes become evergreen in hot + countries.<a name="NtA_756" href="#Nt_756"><sup>[756]</sup></a> Rice + requires much water, but there is one variety in India which can be grown + without irrigation.<a name="NtA_757" href="#Nt_757"><sup>[757]</sup></a> + Certain varieties of the oat and of our other cereals are best fitted for + certain soils.<a name="NtA_758" href="#Nt_758"><sup>[758]</sup></a> + Endless similar facts could be given in the animal and vegetable + kingdoms. They are noticed here because they illustrate analogous + differences in closely allied natural species, and because such changed + habits of life, whether due to use and disuse, or to the direct action of + external conditions, or to so-called spontaneous variation, would be apt + to lead to modifications of structure.</p> + +<hr class="short" /> + + <p><i>Acclimatisation.</i>—From the previous remarks we are + naturally led to the much disputed subject of acclimatisation. There are + two distinct questions: Do varieties descended from the same species + differ in their power of living under different climates? And secondly, + if they so differ, how have they become thus adapted? We have seen that + European dogs do not succeed well in India, and it is asserted,<a + name="NtA_759" href="#Nt_759"><sup>[759]</sup></a> that no one has + succeeded in there keeping the Newfoundland long alive; but then it may + be argued, probably with truth, that these northern breeds are + specifically distinct from the native dogs which flourish in India. The + same remark may be made with respect to different breeds of sheep, of + which, according to Youatt,<a name="NtA_760" + href="#Nt_760"><sup>[760]</sup></a> not one brought "from a torrid + climate lasts out the second year," in the Zoological Gardens. But sheep + are capable of some degree of acclimatisation, for Merino sheep bred at + the Cape of Good Hope have been found <!-- Page 306 --><span + class="pagenum"><a name="page306"></a>{306}</span>far better adapted for + India than those imported from England.<a name="NtA_761" + href="#Nt_761"><sup>[761]</sup></a> It is almost certain that the breeds + of the fowl are descended from the same species; but the Spanish breed, + which there is good reason to believe originated near the + Mediterranean,<a name="NtA_762" href="#Nt_762"><sup>[762]</sup></a> + though so fine and vigorous in England, suffers more from frost than any + other breed. The Arrindy silk-moth introduced from Bengal, and the + Ailanthus moth from the temperate province of Shan Tung, in China, belong + to the same species, as we may infer from their identity in the + caterpillar, cocoon, and mature states;<a name="NtA_763" + href="#Nt_763"><sup>[763]</sup></a> yet they differ much in constitution: + the Indian form "will flourish only in warm latitudes," the other is + quite hardy and withstands cold and rain.</p> + +<blockquote class="b1n"> + + <p>Plants are more strictly adapted to climate than are animals. The + latter when domesticated withstand such great diversities of climate, + that we find nearly the same species in tropical and temperate countries; + whilst the cultivated plants are widely dissimilar. Hence a larger field + is open for inquiry in regard to the acclimatisation of plants than of + animals. It is no exaggeration to say that with almost every plant which + has long been cultivated varieties exist, which are endowed with + constitutions fitted for very different climates; I will select only a + few of the more striking cases, as it would be tedious to give all. In + North America numerous fruit-trees have been raised, and in horticultural + publications,—for instance, in Downing,—lists are given of + the varieties which are best able to withstand the severe climate of the + northern States and Canada. Many American varieties of the pear, plum, + and peach are excellent in their own country, but until recently hardly + one was known that succeeded in England; and with apples,<a + name="NtA_764" href="#Nt_764"><sup>[764]</sup></a> not one succeeds. + Though the American varieties can withstand a severer winter than ours, + the summer here is not hot enough. Fruit-trees have originated in Europe + as in America with different constitutions, but they are not here much + noticed, as the same nurserymen do not supply a wide area. The Forelle + pear flowers early, and when the flowers have just set, and this is the + critical period, they have been observed, both in France and England, to + withstand with complete impunity a frost of 18° and even 14° Fahr., which + killed the flowers, whether fully expanded or in bud, of all other kinds + of pears.<a name="NtA_765" href="#Nt_765"><sup>[765]</sup></a> This power + in the flower of resisting cold and afterwards producing fruit does not + invariably depend, as we know on good authority,<a name="NtA_766" + href="#Nt_766"><sup>[766]</sup></a> on general constitutional vigour.</p> + +<p><!-- Page 307 --><span class="pagenum"><a name="page307"></a>{307}</span></p> + + <p>In proceeding northward, the number of varieties which are enabled to + resist the climate rapidly decreases, as may be seen in the list of the + varieties of the cherry, apple, and pear, which can be cultivated in the + neighbourhood of Stockholm.<a name="NtA_767" + href="#Nt_767"><sup>[767]</sup></a> Near Moscow, Prince Troubetzkoy + planted for experiment in the open ground several varieties of the pear, + but one alone, the <i>Poire sans Pepins</i>, withstood the cold of + winter.<a name="NtA_768" href="#Nt_768"><sup>[768]</sup></a> We thus see + that our fruit-trees, like distinct species of the same genus, certainly + differ from each other in their constitutional adaptation to different + climates.</p> + + <p>With the varieties of many plants, the adaptation to climate is often + very close. Thus it has been proved by repeated trials "that few if any + of the English varieties of wheat are adapted for cultivation in + Scotland;"<a name="NtA_769" href="#Nt_769"><sup>[769]</sup></a> but the + failure in this case is at first only in the quantity, though ultimately + in the quality, of the grain produced. The Rev. J. M. Berkeley sowed + wheat-seed from India, and got "the most meagre ears," on land which + would certainly have yielded a good crop from English wheat.<a + name="NtA_770" href="#Nt_770"><sup>[770]</sup></a> In these cases + varieties have been carried from a warmer to a cooler climate; in the + reverse case, as "when wheat was imported directly from France into the + West Indian Islands, it produced either wholly barren spikes or furnished + with only two or three miserable seeds, while West Indian seed by its + side yielded an enormous harvest."<a name="NtA_771" + href="#Nt_771"><sup>[771]</sup></a> Here is another case of close + adaptation to a slightly cooler climate; a kind of wheat which in England + may be used indifferently either as a winter or summer variety, when sown + under the warmer climate of Grignan, in France, behaved exactly as if it + had been a true winter wheat.<a name="NtA_772" + href="#Nt_772"><sup>[772]</sup></a></p> + + <p>Botanists believe that all the varieties of maize belong to the same + species; and we have seen that in North America, in proceeding northward, + the varieties cultivated in each zone produce their flowers and ripen + their seed within shorter and shorter periods. So that the tall, slowly + maturing southern varieties do not succeed in New England, and the New + English varieties do not succeed in Canada. I have not met with any + statement that the southern varieties are actually injured or killed by a + degree of cold which the northern varieties withstand with impunity, + though this is probable; but the production of early flowering and early + seeding varieties deserves to be considered as one form of + acclimatisation. Hence it has been found possible, according to Kalm, to + cultivate maize further and further northwards in America. In Europe, + also, as we learn from the evidence given by Alph. De Candolle, the + culture of maize has extended since the end of the last century thirty + leagues north of its former boundary.<a name="NtA_773" + href="#Nt_773"><sup>[773]</sup></a> On the authority of the great + Linnæus,<a name="NtA_774" href="#Nt_774"><sup>[774]</sup></a> I may quote + an <!-- Page 308 --><span class="pagenum"><a + name="page308"></a>{308}</span>analogous case, namely, that in Sweden + tobacco raised from home-grown seed ripens its seed a month sooner and is + less liable to miscarry than plants raised from foreign seed.</p> + + <p>With the Vine, differently from the maize, the line of practical + culture has retreated a little southward since the middle ages;<a + name="NtA_775" href="#Nt_775"><sup>[775]</sup></a> but this seems due to + commerce, including that of wine, being now freer or more easy. + Nevertheless the fact of the vine not having spread northward shows that + acclimatisation has made no progress during several centuries. There is, + however, a marked difference in the constitution of the several + varieties,—some being hardy, whilst others, like the muscat of + Alexandria, require a very high temperature to come to perfection. + According to Labat,<a name="NtA_776" href="#Nt_776"><sup>[776]</sup></a> + vines taken from France to the West Indies succeed with extreme + difficulty, whilst those imported from Madeira, or the Canary Islands, + thrive admirably.</p> + + <p>Gallesio gives a curious account of the naturalisation of the Orange + in Italy. Daring many centuries the sweet orange was propagated + exclusively by grafts, and so often suffered from frosts that it required + protection. After the severe frost of 1709, and more especially after + that of 1763, so many trees were destroyed that seedlings from the sweet + orange were raised, and, to the surprise of the inhabitants, their fruit + was found to be sweet. The trees thus raised were larger, more + productive, and hardier than the former kinds; and seedlings are now + continually raised. Hence Gallesio concludes that much more was effected + for the naturalisation of the orange in Italy by the accidental + production of new kinds during a period of about sixty years, than had + been effected by grafting old varieties during many ages.<a + name="NtA_777" href="#Nt_777"><sup>[777]</sup></a> I may add that Risso<a + name="NtA_778" href="#Nt_778"><sup>[778]</sup></a> describes some + Portuguese varieties of the orange as extremely sensitive to cold, and as + much tenderer than certain other varieties.</p> + + <p>The peach was known to Theophrastus, 322 <span + class="scac">B.C.</span><a name="NtA_779" + href="#Nt_779"><sup>[779]</sup></a> According to the authorities quoted + by Dr. F. Rolle,<a name="NtA_780" href="#Nt_780"><sup>[780]</sup></a> it + was tender when first introduced into Greece, and even in the island of + Rhodes only occasionally bore fruit. If this be correct, the peach, in + spreading during the last two thousand years over the middle parts of + Europe, must have become much hardier. At the present day different + varieties differ much in hardiness: some French varieties will not + succeed in England; and near Paris, the <i>Pavie de Bonneuil</i> does not + ripen its fruit till very late, even when grown on a wall; "it is, + therefore, only fit for a very hot southern climate."<a name="NtA_781" + href="#Nt_781"><sup>[781]</sup></a></p> + + <p>I will briefly give a few other cases. A variety of <i>Magnolia + grandiflora</i>, raised by M. Roy, withstands cold several degrees lower + than that which any other variety can resist. With camellias there is + much difference in hardiness. One particular variety of Noisette rose + withstood the severe frost of 1860 "untouched and hale amidst a universal + destruction of other <!-- Page 309 --><span class="pagenum"><a + name="page309"></a>{309}</span>Noisettes." In New York the "Irish yew is + quite hardy, but the common yew is liable to be cut down." I may add that + there are varieties of the sweet potato (<i>Convolvulus batatas</i>) + which are suited for warmer, as well as for colder, climates.<a + name="NtA_782" href="#Nt_782"><sup>[782]</sup></a></p> + +</blockquote> + + <p>The plants as yet mentioned have been found capable of resisting an + unusual degree of cold or heat, when fully grown. The following cases + refer to plants whilst young. In a large bed of young Araucarias of the + same age, growing close together and equally exposed, it was observed,<a + name="NtA_783" href="#Nt_783"><sup>[783]</sup></a> after the unusually + severe winter of 1860-61, that, "in the midst of the dying, numerous + individuals remained on which the frost had absolutely made no kind of + impression." Dr. Lindley, after alluding to this and other similar cases, + remarks, "Among the lessons which the late formidable winter has taught + us, is that, even in their power of resisting cold, individuals of the + same species of plants are remarkably different." Near Salisbury, there + was a sharp frost on the night of May 24th, 1836, and all the French + beans (<i>Phaseolus vulgaris</i>) in a bed were killed except about one + in thirty, which completely escaped.<a name="NtA_784" + href="#Nt_784"><sup>[784]</sup></a> On the same day of the month, but in + the year 1864, there was a severe frost in Kent, and two rows of + scarlet-runners (<i>P. multiflorus</i>) in my garden, containing 390 + plants of the same age and equally exposed, were all blackened and killed + except about a dozen plants. In an adjoining row of "Fulmer's dwarf bean" + (<i>P. vulgaris</i>), one single plant escaped. A still more severe frost + occurred four days afterwards, and of the dozen plants which had + previously escaped only three survived; these were not taller or more + vigorous than the other young plants, but they escaped completely, with + not even the tips of their leaves browned. It was impossible to behold + these three plants, with their blackened, withered, and dead brethren all + round them, and not see at a glance that they differed widely in + constitutional power of resisting frost.</p> + + <p>This work is not the proper place to show that wild plants <!-- Page + 310 --><span class="pagenum"><a name="page310"></a>{310}</span>of the + same species, naturally growing at different altitudes or under different + latitudes, become to a certain extent acclimatised, as is proved by the + different behaviour of their seedlings when raised in England. In my + 'Origin of Species' I have alluded to some cases, and I could add others. + One instance must suffice: Mr. Grigor, of Forres,<a name="NtA_785" + href="#Nt_785"><sup>[785]</sup></a> states that seedlings of the Scotch + fir (<i>Pinus sylvestris</i>), raised from seed from the Continent and + from the forests of Scotland, differ much. "The difference is perceptible + in one-year-old, and more so in two-year-old seedlings; but the effects + of the winter on the second year's growth almost uniformly makes those + from the Continent quite brown, and so damaged, that by the month of + March they are quite unsaleable, while the plants from the native Scotch + pine, under the same treatment, and standing alongside, although + considerably shorter, are rather stouter and quite green, so that the + beds of the one can be known from the other when seen from the distance + of a mile." Closely similar facts have been observed with seedling + larches.</p> + +<blockquote class="b1n"> + + <p>Hardy varieties would alone be valued or noticed in Europe; whilst + tender varieties, requiring more warmth, would generally be neglected; + but such occasionally arise. Thus Loudon<a name="NtA_786" + href="#Nt_786"><sup>[786]</sup></a> describes a Cornish variety of the + elm which is almost an evergreen, and of which the shoots are often + killed by the autumnal frosts, so that its timber is of little value. + Horticulturists know that some varieties are much more tender than + others: thus all the varieties of the broccoli are more tender than + cabbages; but there is much difference in this respect in the + sub-varieties of the broccoli; the pink and purple kinds are a little + hardier than the white Cape broccoli, "but they are not to be depended on + after the thermometer falls below 24° Fahr.:" the Walcheren broccoli is + less tender than the Cape, and there are several varieties which will + stand much severer cold than the Walcheren.<a name="NtA_787" + href="#Nt_787"><sup>[787]</sup></a> Cauliflowers seed more freely in + India than cabbages.<a name="NtA_788" href="#Nt_788"><sup>[788]</sup></a> + To give one instance with flowers: eleven plants raised from a hollyhock, + called the <i>Queen of the Whites</i>,<a name="NtA_789" + href="#Nt_789"><sup>[789]</sup></a> were found to be much more tender + than various other seedlings. It may be presumed that all tender + varieties would succeed better under a climate warmer than ours. With + fruit-trees, it is well known that certain varieties, for instance of the + peach, stand forcing in a hot-house better than others; and this shows + <!-- Page 311 --><span class="pagenum"><a + name="page311"></a>{311}</span>either pliability of organisation or some + constitutional difference. The same individual cherry-tree, when forced, + has been observed during successive years gradually to change its period + of vegetation.<a name="NtA_790" href="#Nt_790"><sup>[790]</sup></a> Few + pelargoniums can resist the heat of a stove, but <i>Alba multiflora</i> + will, as a most skilful gardener asserts, "stand pine-apple top and + bottom heat the whole winter, without looking any more drawn than if it + had stood in a common greenhouse; and <i>Blanche Fleur</i> seems as if it + had been made on purpose for growing in winter, like many bulbs, and to + rest all summer."<a name="NtA_791" href="#Nt_791"><sup>[791]</sup></a> + There can hardly be a doubt that the <i>Alba multiflora</i> pelargonium + must have a widely different constitution from that of most other + varieties of this plant; it would probably withstand even an equatorial + climate.</p> + + <p>We have seen that according to Labat the vine and wheat require + acclimatisation in order to succeed in the West Indies. Similar facts + have been observed at Madras: "two parcels of mignonette-seed, one direct + from Europe, the other saved at Bangalore (of which the mean temperature + is much below that of Madras) were sown at the same time: they both + vegetated equally favourably, but the former all died off a few days + after they appeared above ground; the latter still survive, and are + vigorous healthy plants." So again, "turnip and carrot seed saved at + Hyderabad are found to answer better at Madras than seed from Europe or + from the Cape of Good Hope."<a name="NtA_792" + href="#Nt_792"><sup>[792]</sup></a> Mr. J. Scott, of the Calcutta Botanic + Gardens, informs me that seeds of the sweet-pea (<i>Lathyrus + odoratus</i>) imported from England produce plants, with thick, rigid + stems and small leaves, which rarely blossom and never yield seed; plants + raised from French seed blossom sparingly, but all the flowers are + sterile; on the other hand, plants raised from sweet-peas grown near + Darjeeling in Upper India, but originally derived from England, can be + successfully cultivated on the plains of India; for they flower and seed + profusely, and their stems are lax and scandent. In some of the foregoing + cases, as Dr. Hooker has remarked to me, the greater success may perhaps + be attributed to the seeds having been more fully ripened under a more + favourable climate; but this view can hardly be extended to so many + cases, including plants, which, from being cultivated under a climate + hotter than their native one, become fitted for a still hotter climate. + We may therefore safely conclude that plants can to a certain extent + become accustomed to a climate either hotter or colder than their own; + although these latter cases have been more frequently observed.</p> + +</blockquote> + + <p>We will now consider the means by which acclimatisation may be + effected, namely, through the spontaneous appearance of varieties having + a different constitution, and through the effects of use or habit. In + regard to the first process, there is no evidence that a change in the + constitution of the <!-- Page 312 --><span class="pagenum"><a + name="page312"></a>{312}</span>offspring necessarily stands in any direct + relation with the nature of the climate inhabited by the parents. On the + contrary, it is certain that hardy and tender varieties of the same + species appear in the same country. New varieties thus spontaneously + arising become fitted to slightly different climates in two different + ways; firstly, they may have the power, either as seedlings or when + full-grown, of resisting intense cold, as with the Moscow pear, or of + resisting intense heat, as with some kinds of Pelargonium, or the flowers + may withstand severe frost, as with the Forelle pear. Secondly, plants + may become adapted to climates widely different from their own, from + flowering and fruiting either earlier or later in the season. In both + these cases the power of acclimatisation by man consists simply in the + selection and preservation of new varieties. But without any direct + intention on his part of securing a hardier variety, acclimatisation may + be unconsciously effected by merely raising tender plants from seed, and + by occasionally attempting their cultivation further and further + northwards, as in the case of maize, the orange, and the peach.</p> + + <p>How much influence ought to be attributed to inherited habit or custom + in the acclimatisation of animals and plants is a much more difficult + question. In many cases natural selection can hardly have failed to have + come into play and complicated the result. It is notorious that mountain + sheep resist severe weather and storms of snow which would destroy + lowland breeds; but then mountain sheep have been thus exposed from time + immemorial, and all delicate individuals will have been destroyed, and + the hardiest preserved. So with the Arrindy silk-moths of China and + India; who can tell how far natural selection may have taken a share in + the formation of the two races, which are now fitted for such widely + different climates? It seems at first probable that the many fruit-trees, + which are so well fitted for the hot summers and cold winters of North + America, in contrast with their poor success under our climate, have + become adapted through habit; but when we reflect on the multitude of + seedlings annually raised in that country, and that none would succeed + unless born with a fitting constitution, it is possible that mere habit + may have done nothing towards their acclimatisation. On the other hand, + when we <!-- Page 313 --><span class="pagenum"><a + name="page313"></a>{313}</span>hear that Merino sheep, bred during no + great number of generations at the Cape of Good Hope—that some + European plants raised during only a few generations in the cooler parts + of India, withstand the hotter parts of that country much better than the + sheep or seeds imported directly from England, we must attribute some + influence to habit. We are led to the same conclusion when we hear from + Naudin<a name="NtA_793" href="#Nt_793"><sup>[793]</sup></a> that the + races of melons, squashes, and gourds, which have long been cultivated in + Northern Europe, are comparatively more precocious, and need much less + heat for maturing their fruit, than the varieties of the same species + recently brought from tropical regions. In the reciprocal conversion of + summer and winter wheat, barley, and vetches into each other, habit + produces a marked effect in the course of a very few generations. The + same thing apparently occurs with the varieties of maize, which, when + carried from the Southern to the Northern States of America, or into + Germany, soon become accustomed to their new homes. With vine-plants + taken to the West Indies from Madeira, which are said to succeed better + than plants brought directly from France, we have some degree of + acclimatisation in the individual, independently of the production of new + varieties by seed.</p> + + <p>The common experience of agriculturists is of some value, and they + often advise persons to be cautious in trying in one country the + productions of another. The ancient agricultural writers of China + recommend the preservation and cultivation of the varieties peculiar to + each country. During the classical period, Columella wrote, "Vernaculum + pecus peregrino longe præstantius est."<a name="NtA_794" + href="#Nt_794"><sup>[794]</sup></a></p> + + <p>I am aware that the attempt to acclimatise either animals or plants + has been called a vain chimæra. No doubt the attempt in most cases + deserves to be thus called, if made independently of the production of + new varieties endowed with a different constitution. Habit, however much + prolonged, rarely produces any effect on a plant propagated by buds; it + apparently acts only through successive seminal generations. <!-- Page + 314 --><span class="pagenum"><a name="page314"></a>{314}</span>The + laurel, bay, laurestinus, &c., and the Jerusalem artichoke, which are + propagated by cuttings or tubers, are probably now as tender in England + as when first introduced; and this appears to be the case with the + potato, which until recently was seldom multiplied by seed. With plants + propagated by seed, and with animals, there will be little or no + acclimatisation unless the hardier individuals are either intentionally + or unconsciously preserved. The kidney-bean has often been advanced as an + instance of a plant which has not become hardier since its first + introduction into Britain. We hear, however, on excellent authority,<a + name="NtA_795" href="#Nt_795"><sup>[795]</sup></a> that some very fine + seed, imported from abroad, produced plants "which blossomed most + profusely, but were nearly all but abortive, whilst plants grown + alongside from English seed podded abundantly;" and this apparently shows + some degree of acclimatisation in our English plants. We have also seen + that seedlings of the kidney-bean occasionally appear with a marked power + of resisting frost; but no one, as far as I can hear, has ever separated + such hardy seedlings, so as to prevent accidental crossing, and then + gathered their seed, and repeated the process year after year. It may, + however, be objected with truth that natural selection ought to have had + a decided effect on the hardiness of our kidney-beans; for the tenderest + individuals must have been killed during every severe spring, and the + hardier preserved. But it should be borne in mind that the result of + increased hardiness would simply be that gardeners, who are always + anxious for as early a crop as possible, would sow their seed a few days + earlier than formerly. Now, as the period of sowing depends much on the + soil and elevation of each district, and varies with the season; and as + new varieties have often been imported from abroad, can we feel sure that + our kidney-beans are not somewhat hardier? I have not been able, by + searching old horticultural works, to answer this question + satisfactorily.</p> + + <p>On the whole the facts now given show that, though habit does + something towards acclimatisation, yet that the spontaneous appearance of + constitutionally different individuals is a far more effective agent. As + no single instance has been recorded, either with animals or plants, of + hardier individuals <!-- Page 315 --><span class="pagenum"><a + name="page315"></a>{315}</span>having been long and steadily selected, + though such selection is admitted to be indispensable for the improvement + of any other character, it is not surprising that man has done little in + the acclimatisation of domesticated animals and cultivated plants. We + need not, however, doubt that under nature new races and new species + would become adapted to widely different climates, by spontaneous + variation, aided by habit, and regulated by natural selection.</p> + +<p class="cenhead"><i>Arrests of Development: Rudimentary and Aborted Organs.</i></p> + +<blockquote class="b1n"> + + <p>These subjects are here introduced because there is reason to believe + that rudimentary organs are in many cases the result of disuse. + Modifications of structure from arrested development, so great or so + serious as to deserve to be called monstrosities, are of common + occurrence, but, as they differ much from any normal structure, they + require here only a passing notice. When a part or organ is arrested + during its embryonic growth, a rudiment is generally left. Thus the whole + head may be represented by a soft nipple-like projection, and the limbs + by mere papillæ. These rudiments of limbs are sometimes inherited, as has + been observed in a dog.<a name="NtA_796" + href="#Nt_796"><sup>[796]</sup></a></p> + + <p>Many lesser anomalies in our domesticated animals appear to be due to + arrested development. What the cause of the arrest may be, we seldom + know, except in the case of direct injury to the embryo within the egg or + womb. That the cause does not generally act at a very early embryonic + period we may infer from the affected organ seldom being wholly + aborted,—a rudiment being generally preserved. The external ears + are represented by mere vestiges in a Chinese breed of sheep; and in + another breed, the tail is reduced "to a little button, suffocated, in a + manner, by fat."<a name="NtA_797" href="#Nt_797"><sup>[797]</sup></a> In + tailless dogs and cats a stump is left; but I do not know whether it + includes at an early embryonic age rudiments of all the caudal vertebræ. + In certain breeds of fowls the comb and wattles are reduced to rudiments; + in the Cochin-China breed scarcely more than rudiments of spurs exist. + With polled Suffolk cattle, "rudiments of horns can often be felt at an + early age;"<a name="NtA_798" href="#Nt_798"><sup>[798]</sup></a> and with + species in a state of nature, the relatively greater development of + rudimentary organs at an early period of life is highly characteristic of + such organs. With hornless breeds of cattle and sheep; another and + singular kind of rudiment has been observed, namely, minute dangling + horns attached to the skin alone, and which are often shed and grow + again. With hornless goats, according to Desmarest,<a name="NtA_799" + href="#Nt_799"><sup>[799]</sup></a> <!-- Page 316 --><span + class="pagenum"><a name="page316"></a>{316}</span>the bony protuberances + which properly support the horns exist as mere rudiments.</p> + + <p>With cultivated plants it is far from rare to find the petals, + stamens, and pistils represented by rudiments, like those observed in + natural species. So it is with the whole seed in many fruits; thus near + Astrakhan there is a grape with mere traces of seeds, "so small and lying + so near the stalk that they are not perceived in eating the grape."<a + name="NtA_800" href="#Nt_800"><sup>[800]</sup></a> In certain varieties + of the gourd, the tendrils, according to Naudin, are represented by + rudiments or by various monstrous growths. In the broccoli and + cauliflower the greater number of the flowers are incapable of expansion, + and include rudimentary organs. In the Feather hyacinth (<i>Muscari + comosum</i>) the upper and central flowers are brightly coloured but + rudimentary; under cultivation the tendency to abortion travels downwards + and outwards, and all the flowers become rudimentary; but the abortive + stamens and pistils are not so small in the lower as in the upper + flowers. In the <i>Viburnum opulus</i>, on the other hand, the outer + flowers naturally have their organs of fructification in a rudimentary + state, and the corolla is of large size; under cultivation, the change + spreads to the centre, and all the flowers become affected; thus the + well-known Snow-ball bush is produced. In the Compositæ, the so-called + doubling of the flowers consists in the greater development of the + corolla of the central florets, generally accompanied with some degree of + sterility; and it has been observed<a name="NtA_801" + href="#Nt_801"><sup>[801]</sup></a> that the progressive doubling + invariably spreads from the circumference to the centre,—that is, + from the ray florets, which so often include rudimentary organs, to those + of the disc. I may add, as bearing on this subject, that, with Asters, + seeds taken from the florets of the circumference have been found to + yield the greatest number of double flowers.<a name="NtA_802" + href="#Nt_802"><sup>[802]</sup></a> In these several cases we have a + natural tendency in certain parts to become rudimentary, and this under + culture spreads either to, or from, the axis of the plant. It deserves + notice, as showing how the same laws govern the changes which natural + species and artificial varieties undergo, that in a series of species in + the genus Carthamus, one of the Compositæ, a tendency in the seeds to the + abortion of the pappus may be traced extending from the circumference to + the centre of the disc: thus, according to A. de Jussieu,<a + name="NtA_803" href="#Nt_803"><sup>[803]</sup></a> the abortion is only + partial in <i>Carthamus creticus</i>, but more extended in <i>C. + lanatus</i>; for in this species two or three alone of the central seeds + are furnished with a pappus, the surrounding seeds being either quite + naked or furnished with a few hairs; and lastly, in <i>C. tinctorius</i>, + even the central seeds are destitute of pappus, and the abortion is + complete.</p> + + <p>With animals and plants under domestication, when an organ disappears, + leaving only a rudiment, the loss has generally been sudden, as with + hornless and tailless breeds; and such cases may be ranked as inherited + monstrosities. But in some few cases the loss has been gradual, and <!-- + Page 317 --><span class="pagenum"><a name="page317"></a>{317}</span>has + been partly effected by selection, as with the rudimentary combs and + wattles of certain fowls. We have also seen that the wings of some + domesticated birds have been slightly reduced by disuse, and the great + reduction of the wings in certain silk-moths, with mere rudiments left, + has probably been aided by disuse.</p> + + <p>With species in a state of nature, rudimentary organs are so extremely + common that scarcely one can be named which is wholly free from a blemish + of this nature. Such organs are generally variable, as several + naturalists have observed; for, being useless, they are not regulated by + natural selection, and they are more or less liable to reversion. The + same rule certainly holds good with parts which have become rudimentary + under domestication. We do not know through what steps under nature + rudimentary organs have passed in being reduced to their present + condition; but we so incessantly see in species of the same group the + finest gradations between an organ in a rudimentary and perfect state, + that we are led to believe that the passage must have been extremely + gradual. It may be doubted whether a change of structure so abrupt as the + sudden loss of an organ would ever be of service to a species in a state + of nature; for the conditions to which all organisms are closely adapted + usually change very slowly. Even if an organ did suddenly disappear in + some one individual by an arrest of development, intercrossing with the + other individuals of the same species would cause it to reappear in a + more or less perfect manner, so that its final reduction could only be + effected by the slow process of continued disuse or natural selection. It + is much more probable that, from changed habits of life, organs first + become of less and less use, and ultimately superfluous; or their place + may be supplied by some other organ; and then disuse, acting on the + offspring through inheritance at corresponding periods of life, would go + on reducing the organ; but as most organs could be of no use at an early + embryonic period, they would not be affected by disuse; consequently they + would be preserved at this stage of growth, and would remain as + rudiments. In addition to the effects of disuse, the principle of economy + of growth, already alluded to in this chapter, would lead to the still + further reduction of all superfluous parts. With respect to the final and + total suppression or abortion of any organ, another and distinct + principle, which will be discussed in the chapter on pangenesis, probably + takes a share in the work.</p> + + <p>With animals and plants reared by man there is no severe or recurrent + struggle for existence, and the principle of economy will not come into + action. So far, indeed, is this from being the case, that in some + instances organs, which are naturally rudimentary in the parent-species, + become partially redeveloped in the domesticated descendants. Thus cows, + like most other ruminants, properly have four active and two rudimentary + mammæ; but in our domesticated animals, the latter occasionally become + considerably developed and yield milk. The atrophied mammæ, which, in + male domesticated animals, including man, have in some rare cases grown + to full size and secreted milk, perhaps offer an analogous case. The hind + feet of dogs include rudiments of a fifth toe, and in certain large + breeds these toes, though still rudimentary, become considerably + developed <!-- Page 318 --><span class="pagenum"><a + name="page318"></a>{318}</span>and are furnished with claws. In the + common Hen, the spurs and comb are rudimentary, but in certain breeds + these become, independently of age or disease of the ovaria, well + developed. The stallion has canine teeth, but the mare has only traces of + the alveoli, which, as I am informed by the eminent veterinary Mr. G. T. + Brown, frequently contain minute irregular nodules of bone. These + nodules, however, sometimes become developed into imperfect teeth, + protruding through the gums and coated with enamel; and occasionally they + grow to a third or even a fourth of the length of the canines in the + stallion. With plants I do not know whether the redevelopment of + rudimentary organs occurs more frequently under culture than under + nature. Perhaps the pear-tree may be a case in point, for when wild it + bears thorns, which though useful as a protection are formed of branches + in a <span class="correction" title="Original reads `rudimentry'." + >rudimentary</span> condition, but, when the tree is cultivated, the + thorns are reconverted into branches.</p> + +</blockquote> + + <p>Finally, though organs which must be classed as rudimentary frequently + occur in our domesticated animals and cultivated plants, these have + generally been formed suddenly, through an arrest of development. They + usually differ in appearance from the rudiments which so frequently + characterise natural species. In the latter, rudimentary organs have been + slowly formed through continued disuse, acting by inheritance at a + corresponding age, aided by the principle of the economy of growth, all + under the control of natural selection. With domesticated animals, on the + other hand, the principle of economy is far from coming into action, and + their organs, although often slightly reduced by disuse, are not thus + almost obliterated with mere rudiments left.</p> + +<hr class="full" /> + +<p><!-- Page 319 --><span class="pagenum"><a name="page319"></a>{319}</span></p> + +<h3>CHAPTER XXV.</h3> + +<p class="cenhead">LAWS OF VARIATION, <i>continued</i>—CORRELATED VARIABILITY.</p> + +<blockquote class="b1n"> + + <p><span class="scac">EXPLANATION OF TERM</span>—<span + class="scac">CORRELATION AS CONNECTED WITH DEVELOPMENT</span>—<span + class="scac">MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED + SIZE OF PARTS</span>—<span class="scac">CORRELATED VARIATION OF + HOMOLOGOUS PARTS</span>—<span class="scac">FEATHERED FEET IN BIRDS + ASSUMING THE STRUCTURE OF THE WINGS</span>—<span + class="scac">CORRELATION BETWEEN THE HEAD AND THE + EXTREMITIES</span>—<span class="scac">BETWEEN THE SKIN AND DERMAL + APPENDAGES</span>—<span class="scac">BETWEEN THE ORGANS OF SIGHT + AND HEARING</span>—<span class="scac">CORRELATED MODIFICATIONS IN + THE ORGANS OF PLANTS</span>—<span class="scac">CORRELATED + MONSTROSITIES</span>—<span class="scac">CORRELATION BETWEEN THE + SKULL AND EARS</span>—<span class="scac">SKULL AND CREST OF + FEATHERS</span>—<span class="scac">SKULL AND + HORNS</span>—<span class="scac">CORRELATION OF GROWTH COMPLICATED + BY THE ACCUMULATED EFFECTS OF NATURAL SELECTION</span>—<span + class="scac">COLOUR AS CORRELATED WITH CONSTITUTIONAL + PECULIARITIES.</span></p> + +</blockquote> + + <p>All the parts of the organisation are to a certain extent connected or + correlated together; but the connexion may be so slight that it hardly + exists, as with compound animals or the buds on the same tree. Even in + the higher animals various parts are not at all closely related; for one + part may be wholly suppressed or rendered monstrous without any other + part of the body being affected. But in some cases, when one part varies, + certain other parts always, or nearly always, simultaneously vary; they + are then subject to the law of correlated variation. Formerly I used the + somewhat vague expression of correlation of growth, which may be applied + to many large classes of facts. Thus, all the parts of the body are + admirably coordinated for the peculiar habits of life of each organic + being, and they may be said, as the Duke of Argyll insists in his 'Reign + of Law,' to be correlated for this purpose. Again, in large groups of + animals certain structures always co-exist; for instance, a peculiar form + of stomach with teeth of peculiar form, and such structures may in one + sense be said to be correlated. But these cases have no necessary + connexion with the law to be discussed in the present chapter; for we do + not know that <!-- Page 320 --><span class="pagenum"><a + name="page320"></a>{320}</span>the initial or primary variations of the + several parts were in any way related; slight modifications or individual + differences may have been preserved, first in one and then in another + part, until the final and perfectly co-adapted structure was acquired; + but to this subject I shall presently recur. Again, in many groups of + animals the males alone are furnished with weapons, or are ornamented + with gay colours; and these characters manifestly stand in some sort of + correlation with the male reproductive organs, for when the latter are + destroyed these characters disappear. But it was shown in the twelfth + chapter that the very same peculiarity may become attached at any age to + either sex, and afterwards be exclusively transmitted by the same sex at + a corresponding age. In these cases we have inheritance limited by, or + correlated with, both sex and age; but we have no reason for supposing + that the original cause of the variation was necessarily connected with + the reproductive organs, or with the age of the affected being.</p> + + <p>In cases of true correlated variation, we are sometimes able to see + the nature of the connexion; but in most cases the bond is hidden from + us, and certainly differs in different cases. We can seldom say which of + two correlated parts first varies, and induces a change in the other; or + whether the two are simultaneously produced by some distinct cause. + Correlated variation is an important subject for us; for when one part is + modified through continued selection, either by man or under nature, + other parts of the organisation will be unavoidably modified. From this + correlation it apparently follows that, with our domesticated animals and + plants, varieties rarely or never differ from each other by some single + character alone.</p> + + <p>One of the simplest cases of correlation is that a modification which + arises during an early stage of growth tends to influence the subsequent + development of the same part, as well as of other and intimately + connected parts. Isidore Geoffroy St. Hilaire states<a name="NtA_804" + href="#Nt_804"><sup>[804]</sup></a> that this may constantly be observed + with monstrosities <!-- Page 321 --><span class="pagenum"><a + name="page321"></a>{321}</span>in the animal kingdom; and Moquin-Tandon<a + name="NtA_805" href="#Nt_805"><sup>[805]</sup></a> remarks, that, as with + plants the axis cannot become monstrous without in some way affecting the + organs subsequently produced from it, so axial anomalies are almost + always accompanied by deviations of structure in the appended parts. We + shall presently see that with short-muzzled races of the dog certain + histological changes in the basal elements of the bones arrest their + development and shorten them, and this affects the position of the + subsequently developed molar teeth. It is probable that certain + modifications in the larvæ of insects would affect the structure of the + mature insects. But we must be very careful not to extend this view too + far, for, during the normal course of development, certain members in the + same group of animals are known to pass through an extraordinary course + of change, whilst other and closely allied members arrive at maturity + with little change of structure.</p> + + <p>Another simple case of correlation is that with the increased or + decreased dimensions of the whole body, or of any particular part, + certain organs are increased or diminished in number, or are otherwise + modified. Thus pigeon-fanciers have gone on selecting pouters for length + of body, and we have seen that their vertebræ are generally increased in + number, and their ribs in breadth. Tumblers have been selected for their + small bodies, and their ribs and primary wing-feathers are generally + lessened in number. Fantails have been selected for their large, + widely-expanded tails, with numerous tail-feathers, and the caudal + vertebræ are increased in size and number. Carriers have been selected + for length of beak, and their tongues have become longer, but not in + strict accordance with the length of beak. In this latter breed and in + others having large feet, the number of the scutellæ on the toes is + greater than in the breeds with small feet. Many similar cases could be + given. In Germany it has been observed that the period of gestation is + longer in large-sized than in small-sized breeds of cattle. With our + highly-improved animals of all kinds the period of maturity has advanced, + both with respect to the full growth of the body and the period of + reproduction; and, in correspondence with this, the teeth are now + developed earlier than formerly, so that, <!-- Page 322 --><span + class="pagenum"><a name="page322"></a>{322}</span>to the surprise of + agriculturists, the ancient rules for judging the age of an animal by the + state of its teeth are no longer trustworthy.<a name="NtA_806" + href="#Nt_806"><sup>[806]</sup></a></p> + + <p><i>Correlated Variation of Homologous Parts.</i>—Parts which are + homologous tend to vary in the same manner; and this is what might have + been expected, for such parts are identical in form and structure during + an early period of embryonic development, and are exposed in the egg or + womb to similar conditions. The symmetry, in most kinds of animals, of + the corresponding or homologous organs on the right and left sides of the + body, is the simplest case in point; but this symmetry sometimes fails, + as with rabbits having only one ear, or stags with one horn, or with + many-horned sheep which sometimes carry an additional horn on one side of + their heads. With flowers which have regular corollas, the petals + generally vary in the same manner, as we see in the same complicated and + elegant pattern, on the flowers of the Chinese pink; but with irregular + flowers, though the petals are of course homologous, this symmetry often + fails, as with the varieties of the <i>Antirrhinum</i> or snapdragon, or + that variety of the kidney-bean (<i>Phaseolus multiflorus</i>) which has + a white standard-petal.</p> + + <p>In the vertebrata the front and hind limbs are homologous, and they + tend to vary in the same manner, as we see in long and short-legged, or + in thick and thin-legged races of the horse and dog. Isidore Geoffroy<a + name="NtA_807" href="#Nt_807"><sup>[807]</sup></a> has remarked on the + tendency of supernumerary digits in man to appear, not only on the right + and left sides, but on the upper and lower extremities. Meckel has + insisted<a name="NtA_808" href="#Nt_808"><sup>[808]</sup></a> that, when + the muscles of the arm depart in number or arrangement from their proper + type, they almost always imitate those of the leg; and so conversely the + varying muscles of the leg imitate the normal muscles of the arm.</p> + + <p>In several distinct breeds of the pigeon and fowl, the legs and the + two outer toes are heavily feathered, so that in the trumpeter pigeon + they appear like little wings. In the feather-legged bantam the "boots" + or feathers, which grow from the outside of the leg and generally from + the two outer toes, have, <!-- Page 323 --><span class="pagenum"><a + name="page323"></a>{323}</span>according to the excellent authority of + Mr. Hewitt,<a name="NtA_809" href="#Nt_809"><sup>[809]</sup></a> been + seen to exceed the wing-feathers in length, and in one case were actually + nine and a half inches in length! As Mr. Blyth has remarked to me, these + leg-feathers resemble the primary wing-feathers, and are totally unlike + the fine down which naturally grows on the legs of some birds, such as + grouse and owls. Hence it may be suspected that excess of food has first + given redundancy to the plumage, and then that the law of homologous + variation has led to the development of feathers on the legs, in a + position corresponding with those on the wing, namely, on the outside of + the tarsi and toes. I am strengthened in this belief by the following + curious case of correlation, which for a long time seemed to me utterly + inexplicable, namely, that in pigeons of any breed, if the legs are + feathered, the two outer toes are partially connected by skin. These two + outer toes correspond with our third and fourth toes. Now, in the wing of + the pigeon or any other bird, the first and fifth digits are wholly + aborted; the second is rudimentary and carries the so-called + "bastard-wing;" whilst the third and fourth digits are completely united + and enclosed by skin, together forming the extremity of the wing. So that + in feather-footed pigeons, not only does the exterior surface support a + row of long feathers, like wing-feathers, but the very same digits which + in the wing are completely united by skin become partially united by skin + in the feet; and thus by the law of the correlated variation of + homologous parts we can understand the curious connection of feathered + legs and membrane between the two outer toes.</p> + + <p>Andrew Knight<a name="NtA_810" href="#Nt_810"><sup>[810]</sup></a> has + remarked that the face or head and the limbs vary together in general + proportions. Compare, for instance, the head and limbs of a dray and + race-horse, or of a greyhound and mastiff. What a monster a greyhound + would appear with the head of a mastiff! The <i>modern</i> bulldog, + however, has fine limbs, but this is a recently-selected character. From + the measurements given in the sixth chapter, we clearly see that in all + the breeds of the pigeon the length of the beak and the size of the feet + are correlated. The view which, as before explained, seems the most + probable is, that disuse in all cases tends <!-- Page 324 --><span + class="pagenum"><a name="page324"></a>{324}</span>to diminish the feet, + the beak becoming at the same time through correlation shorter; but that + in those few breeds in which length of beak has been a selected point, + the feet, notwithstanding disuse, have through correlation increased in + size.</p> + + <p>With the increased length of the beak in pigeons, not only the tongue + increases in length, but likewise the orifice of the nostrils. But the + increased length of the orifice of the nostrils perhaps stands in closer + correlation with the development of the corrugated skin or wattle at the + base of the beak; for when there is much wattle round the eyes, the + eyelids are greatly increased or even doubled in length.</p> + + <p>There is apparently some correlation even in colour between the head + and the extremities. Thus with horses a large white star or blaze on the + forehead is generally accompanied by white feet.<a name="NtA_811" + href="#Nt_811"><sup>[811]</sup></a> With white rabbits and cattle, dark + marks often co-exist on the tips of the ears and on the feet. In black + and tan dogs of different breeds, tan-coloured spots over the eyes and + tan-coloured feet almost invariably go together. These latter cases of + connected colouring may be due either to reversion or to analogous + variation,—subjects to which we shall hereafter return,—but + this does not necessarily determine the question of their original + correlation. If those naturalists are correct who maintain that the + jaw-bones are homologous with the limb-bones, then we can understand why + the head and limbs tend to vary together in shape and even in colour; but + several highly competent judges dispute the correctness of this view.</p> + + <p>The lopping forwards and downwards of the immense ears of fancy + rabbits is in part due to the disuse of the muscles, and in part to the + weight and length of the ears, which have been increased by selection + during many generations. Now, with the increased size and changed + direction of the ears, not only has the bony auditory meatus become + changed in outline, direction, and greatly in size, but the whole skull + has been slightly modified. This could be clearly seen in + "half-lops"—that is, in rabbits with one ear alone lopping + forward—for the opposite sides of their skulls were not strictly + symmetrical. This seems to me a curious instance of correlation, between + hard <!-- Page 325 --><span class="pagenum"><a + name="page325"></a>{325}</span>bones and organs so soft and flexible, as + well as so unimportant under a physiological point of view, as the + external ears. The result no doubt is largely due to mere mechanical + action, that is, to the weight of the ears, on the same principle that + the skull of a human infant is easily modified by pressure.</p> + + <p>The skin and the appendages of hair, feathers, hoofs, horns, and + teeth, are homologous over the whole body. Every one knows that the + colour of the skin and that of the hair usually vary together; so that + Virgil advises the shepherd to look whether the mouth and tongue of the + ram are black, lest the lambs should not be purely white. With poultry + and certain ducks we have seen that the colour of the plumage stands in + some connexion with the colour of the shell of the egg,—that is, + with the mucous membrane which secretes the shell. The colour of the skin + and hair, and the odour emitted by the glands of the skin, are said<a + name="NtA_812" href="#Nt_812"><sup>[812]</sup></a> to be connected, even + in the same race of men. Generally the hair varies in the same way all + over the body in length, fineness, and curliness. The same rule holds + good with feathers, as we see with the laced and frizzled breeds both of + fowls and pigeons. In the common cock the feathers on the neck and loins + are always of a particular shape, called hackles: now in the Polish + breed, both sexes are characterised by a tuft of feathers on the head; + but through correlation these feathers in the male always assume the form + of hackles. The wing and tail-feathers, though arising from parts not + homologous, vary in length together; so that long or short winged pigeons + generally have long or short tails. The case of the Jacobin-pigeon is + more curious, for the wing and tail feathers are remarkably long; and + this apparently has arisen in correlation with the elongated and reversed + feathers on the back of the neck, which form the hood.</p> + + <p>The hoofs and hair are homologous appendages; and a careful observer, + namely Azara,<a name="NtA_813" href="#Nt_813"><sup>[813]</sup></a> states + that in Paraguay horses of various colours are often born with their hair + curled and twisted like that on the head of a negro. This peculiarity is + strongly inherited. But what is remarkable is that the hoofs of these + horses "are absolutely like those of a mule." The hair also of the mane + and tail is invariably much shorter than usual, being only from four <!-- + Page 326 --><span class="pagenum"><a name="page326"></a>{326}</span>to + twelve inches in length; so that curliness and shortness of the hair are + here, as with the negro, apparently correlated.</p> + + <p>With respect to the horns of sheep, Youatt<a name="NtA_814" + href="#Nt_814"><sup>[814]</sup></a> remarks that "multiplicity of horns + is not found in any breed of much value: it is generally accompanied by + great length and coarseness of the fleece." Several tropical breeds of + sheep, which are clothed with hair instead of wool, have horns almost + like those of a goat. Sturm<a name="NtA_815" + href="#Nt_815"><sup>[815]</sup></a> expressly declares that in different + races the more the wool is curled the more the horns are spirally + twisted. We have seen in the third chapter, where other analogous facts + have been given, that the parent of the Mauchamp breed, so famous for its + fleece, had peculiarly shaped horns. The inhabitants of Angora assert<a + name="NtA_816" href="#Nt_816"><sup>[816]</sup></a> that "only the white + goats which have horns wear the fleece in the long curly locks that are + so much admired; those which are not horned having a comparatively close + coat." From these cases we may conclude that the hair or wool and the + horns vary in a correlated manner. Those who have tried hydropathy are + aware that the frequent application of cold water stimulates the skin; + and whatever stimulates the skin tends to increase the growth of the + hair, as is well shown in the abnormal growth of hair near old inflamed + surfaces. Now, Professor Low<a name="NtA_817" + href="#Nt_817"><sup>[817]</sup></a> is convinced that with the different + races of British cattle thick skin and long hair depend on the humidity + of the climate which they inhabit. We can thus see how a humid climate + might act on the horns—in the first place directly on the skin and + hair, and secondly by correlation on the horns. The presence or absence + of horns, moreover, both in the case of sheep and cattle, acts, as will + presently be shown, by some sort of correlation on the skull.</p> + + <p>With respect to hair and teeth, Mr. Yarrell<a name="NtA_818" + href="#Nt_818"><sup>[818]</sup></a> found many of the teeth deficient in + three hairless "<i>Ægyptian</i>" dogs, and in a hairless terrier. The + incisors, canines, and premolars suffered most, but in one case all the + teeth, except the large tubercular molar on each side, were deficient. + With man several striking cases have been recorded<a name="NtA_819" + href="#Nt_819"><sup>[819]</sup></a> of inherited baldness with <!-- Page + 327 --><span class="pagenum"><a name="page327"></a>{327}</span>inherited + deficiency, either complete or partial, of the teeth. We see the same + connexion in those rare cases in which the hair has been renewed in old + age, for this has "usually been accompanied by a renewal of the teeth." I + have remarked in a former part of this volume that the great reduction in + the size of the tusks in domestic boars probably stands in close relation + with their diminished bristles, due to a certain amount of protection; + and that the reappearance of the tusks in boars, which have become feral + and are fully exposed to the weather, probably depends on the + reappearance of the bristles. I may add, though not strictly connected + with our present point, that an agriculturist<a name="NtA_820" + href="#Nt_820"><sup>[820]</sup></a> asserts that "pigs with little hair + on their bodies are most liable to lose their tails, showing a weakness + of the tegumental structure. It may be prevented by crossing with a more + hairy breed."</p> + + <p>In the previous cases deficient hair, and teeth deficient in number or + size, are apparently connected. In the following cases abnormally + redundant hair, and teeth either deficient or redundant, are likewise + connected. Mr. Crawfurd<a name="NtA_821" + href="#Nt_821"><sup>[821]</sup></a> saw at the Burmese Court a man, + thirty years old, with his whole body, except the hands and feet, covered + with straight silky hair, which on the shoulders and spine was five + inches in length. At birth the ears alone were covered. He did not arrive + at puberty, or shed his milk teeth, until twenty years old; and at this + period he acquired five teeth in the upper jaw, namely four incisors and + one canine, and four incisor teeth in the lower jaw; all the teeth were + small. This man had a daughter, who was born with hair within her ears; + and the hair soon extended over her body. When Captain Yule<a + name="NtA_822" href="#Nt_822"><sup>[822]</sup></a> visited the Court, he + found this girl grown up; and she presented a strange appearance with + even her nose densely covered with soft hair. Like her father, she was + furnished with incisor teeth alone. The King had with difficulty bribed a + man to marry her, and of her two children, one, a boy fourteen months + old, had hair growing out of his ears, with a beard and moustache. This + strange peculiarity had, therefore, been inherited for three generations, + with the molar teeth deficient in the grandfather and mother; whether + <!-- Page 328 --><span class="pagenum"><a + name="page328"></a>{328}</span>these teeth would likewise fail in the + infant could not be told. Here is another case communicated to me by Mr. + Wallace on the authority of Dr. Purland, a dentist: Julia Pastrana, a + Spanish dancer, was a remarkably fine woman, but she had a thick + masculine beard and a hairy forehead; she was photographed, and her + stuffed skin was exhibited as a show; but what concerns us is, that she + had in both the upper and lower jaw an irregular double set of teeth, one + row being placed within the other, of which Dr. Purland took a cast. From + the redundancy of the teeth her mouth projected, and her face had a + gorilla-like appearance. These cases and those of the hairless dogs + forcibly call to mind the fact, that the two orders of + mammals—namely, the Edentata and Cetacea—which are the most + abnormal in their dermal covering, are likewise the most abnormal either + by deficiency or redundancy of teeth.</p> + + <p>The organs of sight and hearing are generally admitted to be + homologous, both with each other and with the various dermal appendages; + hence these parts are liable to be abnormally affected in conjunction. + Mr. White Cowper says "that in all cases of double microphthalmia brought + under his notice he has at the same time met with defective development + of the dental system." Certain forms of blindness seem to be associated + with the colour of the hair; a man with black hair and a woman with + light-coloured hair, both of sound constitution, married and had nine + children, all of whom were born blind; of these children, five "with dark + hair and brown iris were afflicted with amaurosis; the four others, with + light-coloured hair and blue iris, had amaurosis and cataract conjoined." + Several cases could be given, showing that some relation exists between + various affections of the eyes and ears; thus Liebreich states that out + of 241 deaf-mutes in Berlin, no less than fourteen suffered from the rare + disease called pigmentary retinitis. Mr. White Cowper and Dr. Earle have + remarked that inability to distinguish different colours, or + colour-blindness, "is often associated with a corresponding inability to + distinguish musical sounds."<a name="NtA_823" + href="#Nt_823"><sup>[823]</sup></a></p> + +<p><!-- Page 329 --><span class="pagenum"><a name="page329"></a>{329}</span></p> + + <p>Here is a more curious case: white cats, if they have blue eyes, are + almost always deaf. I formerly thought that the rule was invariable, but + I have heard of a few authentic exceptions. The first two notices were + published in 1829, and relate to English and Persian cats: of the latter, + the Rev. W. T. Bree possessed a female, and he states "that of the + offspring produced at one and the same birth, such as, like the mother, + were entirely white (with blue eyes) were, like her, invariably deaf; + while those that had the least speck of colour on their fur, as + invariably possessed the usual faculty of hearing."<a name="NtA_824" + href="#Nt_824"><sup>[824]</sup></a> The Rev. W. Darwin Fox informs me + that he has seen more than a dozen instances of this correlation in + English, Persian, and Danish cats; but he adds "that, if one eye, as I + have several times observed, be not blue, the cat hears. On the other + hand, I have never seen a white cat with eyes of the common colour that + was deaf." In France Dr. Sichel<a name="NtA_825" + href="#Nt_825"><sup>[825]</sup></a> has observed during twenty years + similar facts; he adds the remarkable case of the iris beginning, at the + end of four months, to grow dark-coloured, and then the cat first began + to hear.</p> + + <p>This case of correlation in cats has struck many persons as + marvellous. There is nothing unusual in the relation between blue eyes + and white fur; and we have already seen that the organs of sight and + hearing are often simultaneously affected. In the present instance the + cause probably lies in a slight arrest of development in the nervous + system in connection with the sense-organs. Kittens during the first nine + days, whilst their eyes are closed, appear to be completely deaf; I have + made a great clanging noise with a poker and shovel close to their heads, + both when they were asleep and awake, without producing any effect. The + trial must not be made by shouting close to their ears, for they are, + even when asleep, extremely sensitive to a breath of air. Now, as long as + the eyes continue closed, the iris is no doubt blue, for in all the + kittens which I have seen this colour remains for some time after the + eyelids open. Hence, if we suppose the development of the organs of sight + and hearing to be arrested at the stage of the closed eyelids, the eyes + would <!-- Page 330 --><span class="pagenum"><a + name="page330"></a>{330}</span>remain permanently blue and the ears would + be incapable of perceiving sound; and we should thus understand this + curious case. As, however, the colour of the fur is determined long + before birth, and as the blueness of the eyes and the whiteness of the + fur are obviously connected, we must believe that some primary cause acts + at an early period.</p> + + <p>The instances of correlated variability hitherto given have been + chiefly drawn from the animal kingdom, and we will now turn to plants. + Leaves, sepals, petals, stamens, and pistils are all homologous. In + double flowers we see that the stamens and pistils vary in the same + manner, and assume the form and colour of the petals. In the double + columbine (<i>Aquilegia vulgaris</i>), the successive whorls of stamens + are converted into cornucopias, which are enclosed within each other and + resemble the petals. In hose-and-hose flowers the sepals mock the petals. + In some cases the flowers and leaves vary together in tint: in all the + varieties of the common pea, which have purple flowers, a purple mark may + be seen on the stipules. In other cases the leaves and fruit and seeds + vary together in colour, as in a curious pale-leaved variety of the + sycamore, which has recently been described in France,<a name="NtA_826" + href="#Nt_826"><sup>[826]</sup></a> and as in the purple-leaved hazel, in + which the leaves, the husk of the nut, and the pellicle round the kernel + are all coloured purple.<a name="NtA_827" + href="#Nt_827"><sup>[827]</sup></a> Pomologists can predict to a certain + extent, from the size and appearance of the leaves of their seedlings, + the probable nature of the fruit; for, as Van Mons remarks,<a + name="NtA_828" href="#Nt_828"><sup>[828]</sup></a> variations in the + leaves are generally accompanied by some modification in the flower, and + consequently in the fruit. In the Serpent melon, which has a narrow + tortuous fruit above a yard in length, the stem of the plant, the + peduncle of the female flower, and the middle lobe of the leaf, are all + elongated in a remarkable manner. On the other hand, several varieties of + Cucurbita, which have dwarfed stems, all produce, as Naudin remarks with + surprise, leaves of the same peculiar shape. Mr. G. Maw informs me that + all the varieties of the scarlet Pelargoniums which have contracted or + imperfect leaves have contracted flowers: the difference between <!-- + Page 331 --><span class="pagenum"><a + name="page331"></a>{331}</span>"Brilliant" and its parent "Tom Thumb" is + a good instance of this. It may be suspected that the curious case + described by Risso,<a name="NtA_829" href="#Nt_829"><sup>[829]</sup></a> + of a variety of the Orange which produces on the young shoots rounded + leaves with winged petioles, and afterwards elongated leaves on long but + wingless petioles, is connected with the remarkable change in form and + nature which the fruit undergoes during its development.</p> + + <p>In the following instance we have the colour and form of the petals + apparently correlated, and both dependent on the nature of the season. An + observer, skilled in the subject, writes,<a name="NtA_830" + href="#Nt_830"><sup>[830]</sup></a> "I noticed, during the year 1842, + that every Dahlia, of which the colour had any tendency to scarlet, was + deeply notched—indeed to so great an extent as to give the petals + the appearance of a saw; the indentures were, in some instances, more + than a quarter of an inch deep." Again, Dahlias which have their petals + tipped with a different colour from the rest are very inconstant, and + during certain years some, or even all the flowers, become uniformly + coloured; and it has been observed with several varieties,<a + name="NtA_831" href="#Nt_831"><sup>[831]</sup></a> that when this happens + the petals grow much elongated and lose their proper shape. This, + however, may be due to reversion, both in colour and form, to the + aboriginal species.</p> + +<hr class="short" /> + + <p>In this discussion on correlation, we have hitherto treated of cases + in which we can partly understand the bond of connexion; but I will now + give cases in which we cannot even conjecture, or can only very obscurely + see, what is the nature of the bond. Isidore Geoffroy St. Hilaire, in his + work on Monstrosities, insists,<a name="NtA_832" + href="#Nt_832"><sup>[832]</sup></a> "que certaines anomalies coexistent + rarement entr'elles, d'autres fréquemment, d'autres enfin presque + constamment, malgré la différence très-grande de leur nature, et + quoiqu'elles puissent paraître <i>complètement indépendantes</i> les unes + des autres." We see something analogous in certain diseases: thus I hear + from Mr. Paget that in a rare affection of the <!-- Page 332 --><span + class="pagenum"><a name="page332"></a>{332}</span>renal capsules (of + which the functions are unknown), the skin becomes bronzed; and in + hereditary syphilis, both the milk and the second teeth assume a peculiar + and characteristic form. Professor Rolleston, also, informs me that the + incisor teeth are sometimes furnished with a vascular rim in correlation + with intra-pulmonary deposition of tubercles. In other cases of phthisis + and of cyanosis the nails and finger-ends become clubbed like acorns. I + believe that no explanation has been offered of these and of many other + cases of correlated disease.</p> + + <p>What can be more curious and less intelligible than the fact + previously given, on the authority of Mr. Tegetmeier, that young pigeons + of all breeds, which when mature have white, yellow, silver-blue, or + dun-coloured plumage, come out of the egg almost naked; whereas pigeons + of other colours when first born are clothed with plenty of down? White + Pea-fowls, as has been observed both in England and France,<a + name="NtA_833" href="#Nt_833"><sup>[833]</sup></a> and as I have myself + seen, are inferior in size to the common coloured kind; and this cannot + be accounted for by the belief that albinism is always accompanied by + constitutional weakness; for white or albino moles are generally larger + than the common kind.</p> + + <p>To turn to more important characters: the niata cattle of the Pampas + are remarkable from their short foreheads, upturned muzzles, and curved + lower jaws. In the skull the nasal and premaxillary bones are much + shortened, the maxillaries are excluded from any junction with the + nasals, and all the bones are slightly modified, even to the plane of the + occiput. From the analogical case of the dog, hereafter to be given, it + is probable that the shortening of the nasal and adjoining bones is the + proximate cause of the other modifications in the skull, including the + upward curvature of the lower jaw, though we cannot follow out the steps + by which these changes have been effected.</p> + + <p>Polish fowls have a large tuft of feathers on their heads; and their + skulls are perforated by numerous holes, so that a pin can be driven into + the brain without touching any bone. That this deficiency of bone is in + some way connected with the tuft of feathers is clear from tufted ducks + and geese likewise having <!-- Page 333 --><span class="pagenum"><a + name="page333"></a>{333}</span>perforated skulls. The case would probably + be considered by some authors as one of balancement or compensation. In + the chapter on Fowls, I have shown that with Polish fowls the tuft of + feathers was probably at first small; by continued selection it became + larger, and then rested on a fleshy or fibrous mass; and finally, as it + became still larger, the skull itself became more and more protuberant + until it acquired its present extraordinary structure. Through + correlation with the protuberance of the skull, the shape and even the + relative connexion of the premaxillary and nasal bones, the shape of the + orifice of the nostrils, the breadth of the frontal bone, the shape of + the post-lateral processes of the frontal and squamosal bones, and the + direction of the bony cavity of the ear, have all been modified. The + internal configuration of the skull and the whole shape of the brain have + likewise been altered in a truly marvellous manner.</p> + + <p>After this case of the Polish fowl it would be superfluous to do more + than refer to the details previously given on the manner in which the + changed form of the comb, in various breeds of the fowl, has affected the + skull, causing by correlation crests, protuberances, and depressions on + its surface.</p> + + <p>With our cattle and sheep the horns stand in close connexion with the + size of the skull, and with the shape of the frontal bones; thus Cline<a + name="NtA_834" href="#Nt_834"><sup>[834]</sup></a> found that the skull + of a horned ram weighed five times as much as that of a hornless ram of + the same age. When cattle become hornless, the frontal bones are + "materially diminished in breadth towards the poll;" and the cavities + between the bony plates "are not so deep, nor do they extend beyond the + frontals."<a name="NtA_835" href="#Nt_835"><sup>[835]</sup></a></p> + +<hr class="short" /> + + <p>It may be well here to pause and observe how the effects of correlated + variability, of the increased use of parts, and of the accumulation + through natural selection of so-called spontaneous variations, are in + many cases inextricably commingled. We may borrow an illustration from + Mr. Herbert Spencer, who remarks that, when the Irish elk acquired its + gigantic horns, weighing above one hundred pounds, numerous co-ordinated + <!-- Page 334 --><span class="pagenum"><a + name="page334"></a>{334}</span>changes of structure would have been + indispensable,—namely, a thickened skull to carry the horns; + strengthened cervical vertebræ, with strengthened ligaments; enlarged + dorsal vertebræ to support the neck, with powerful fore-legs and feet; + all these parts being supplied with proper muscles, blood-vessels, and + nerves. How then could these admirably co-ordinated modifications of + structure have been acquired? According to the doctrine which I maintain, + the horns of the male elk were slowly gained through sexual + selection,—that is, by the best-armed males conquering the + worse-armed, and leaving a greater number of descendants. But it is not + at all necessary that the several parts of the body should have + simultaneously varied. Each stag presents individual differences, and in + the same district those which had slightly heavier horns, or stronger + necks, or stronger bodies, or were the most courageous, would secure the + greater number of does, and consequently leave a greater number of + offspring. The offspring would inherit, in a greater or less degree, + these same qualities, would occasionally intercross with each other, or + with other individuals varying in some favourable manner; and of their + offspring, those which were the best endowed in any respect would + continue multiplying; and so onwards, always progressing, sometimes in + one direction, and sometimes in another, towards the present excellently + co-ordinated structure of the male elk. To make this clear, let us + reflect on the probable steps, as shown in the twentieth chapter, by + which our race and dray-horses have arrived at their present state of + excellence; if we could view the whole series of intermediate forms + between one of these animals and an early unimproved progenitor, we + should behold a vast number of animals, not equally improved in each + generation throughout their entire structure, but sometimes a little more + in one point, and sometimes in another, yet on the whole gradually + approaching in character to our present race or dray-horses, which are so + admirably fitted in the one case for fleetness and in the other for + draught.</p> + + <p>Although natural selection would thus<a name="NtA_836" + href="#Nt_836"><sup>[836]</sup></a> tend to give to the <!-- Page 335 + --><span class="pagenum"><a name="page335"></a>{335}</span>male elk its + present structure, yet it is probable that the inherited influence of use + has played an equal or more important part. As the horns gradually + increased in weight, the muscles of the neck, with the bones to which + they are attached, would increase in size and strength; and these parts + would react on the body and legs. Nor must we overlook the fact that + certain parts of the skull and the extremities would, judging by analogy, + tend from the first to vary in a correlated manner. The increased weight + of the horns would also act directly on the skull, in the same manner as, + when one bone is removed in the leg of a dog, the other bone, which has + to carry the whole weight of the body, increases in thickness. But from + the facts given with respect to horned and hornless cattle, it is + probable that the horns and skull would immediately act on each other + through the principle of correlation. Lastly, the growth and subsequent + wear and tear of the augmented muscles and bones would require an + increased supply of blood, and consequently an increased supply of food; + and this again would require increased powers of mastication, digestion, + respiration, and excretion.</p> + +<p class="cenhead"><i>Colour as Correlated with Constitutional Peculiarities.</i></p> + + <p>It is an old belief that with man there is a connexion between + complexion and constitution; and I find that some of the best authorities + believe in this to the present day.<a name="NtA_837" + href="#Nt_837"><sup>[837]</sup></a> Thus Dr. Beddoe by his tables shows<a + name="NtA_838" href="#Nt_838"><sup>[838]</sup></a> that a relation exists + between liability to consumption and the colour of the hair, eyes, and + skin. It has been affirmed<a name="NtA_839" + href="#Nt_839"><sup>[839]</sup></a> that, in the French army which + invaded Russia, soldiers having a dark complexion, from the <!-- Page 336 + --><span class="pagenum"><a name="page336"></a>{336}</span>southern parts + of Europe, withstood the intense cold better than those with lighter + complexions from the north; but no doubt such statements are liable to + error.</p> + + <p>In the second chapter on Selection I have given several cases proving + that with animals and plants differences in colour are correlated with + constitutional differences, as shown by greater or less immunity from + certain diseases, from the attacks of parasitic plants and animals, from + burning by the sun, and from the action of certain poisons. When all the + individuals of any one variety possess an immunity of this nature, we + cannot feel sure that it stands in any sort of correlation with their + colour; but when several varieties of the same species, which are + similarly coloured, are thus characterised, whilst other coloured + varieties are not thus favoured, we must believe in the existence of a + correlation of this kind. Thus in the United States purple-fruited plums + of many kinds are far more affected by a certain disease than green or + yellow-fruited varieties. On the other hand, yellow-fleshed peaches of + various kinds suffer from another disease much more than the + white-fleshed varieties. In the Mauritius red sugar-canes are much less + affected by a particular disease than the white canes. White onions and + verbenas are the most liable to mildew; and in Spain the green-fruited + grapes suffered from the vine-disease more than other coloured varieties. + Dark-coloured pelargoniums and verbenas are more scorched by the sun than + varieties of other colours. Red wheats are believed to be hardier than + white; whilst red-flowered hyacinths were more injured during one + particular winter in Holland than other coloured varieties. With animals, + white terriers suffer most from the distemper, white chickens from a + parasitic worm in their tracheæ, white pigs from scorching by the sun, + and white cattle from flies; but the caterpillars of the silk-moth which + yield white cocoons suffered in France less from the deadly parasitic + fungus than those producing yellow silk.</p> + + <p>The cases of immunity from the action of certain vegetable poisons, in + connexion with colour, are more interesting, and are at present wholly + inexplicable. I have already given a remarkable instance, on the + authority of Professor Wyman, of all the hogs, excepting those of a black + colour, suffering severely in Virginia from eating the root of the + <i>Lachnanthes tinctoria</i>. <!-- Page 337 --><span class="pagenum"><a + name="page337"></a>{337}</span>According to Spinola and others,<a + name="NtA_840" href="#Nt_840"><sup>[840]</sup></a> buckwheat + (<i>Polygonum fagopyrum</i>), when in flower, is highly injurious to + white or white-spotted pigs, if they are exposed to the heat of the sun, + but is quite innocuous to black pigs. By two accounts, the <i>Hypericum + crispum</i> in Sicily is poisonous to white sheep alone; their heads + swell, their wool falls off, and they often die; but this plant, + according to Lecce, is poisonous only when it grows in swamps; nor is + this improbable, as we know how readily the poisonous principle in plants + is influenced by the conditions under which they grow.</p> + + <p>Three accounts have been published in Eastern Prussia, of white and + white-spotted horses being greatly injured by eating mildewed and + honeydewed vetches; every spot of skin bearing white hairs becoming + inflamed and gangrenous. The Rev. J. Rodwell informs me that his father + turned out about fifteen cart-horses into a field of tares which in parts + swarmed with black aphides, and which no doubt were honeydewed, and + probably mildewed; the horses, with two exceptions, were chesnuts and + bays with white marks on their faces and pasterns, and the white parts + alone swelled and became angry scabs. The two bay horses with no white + marks entirely escaped all injury. In Guernsey, when horses eat fools' + parsley (<i>Æthusa cynapium</i>) they are sometimes violently purged; and + this plant "has a peculiar effect on the nose and lips, causing deep + cracks and ulcers, particularly on horses with white muzzles."<a + name="NtA_841" href="#Nt_841"><sup>[841]</sup></a> With cattle, + independently of the action of any poison, cases have been published by + Youatt and Erdt of cutaneous diseases with much constitutional + disturbance (in one instance after exposure to a hot sun) affecting every + single point which bore a white hair, but completely passing over other + parts of the body. Similar cases have been observed with horses.<a + name="NtA_842" href="#Nt_842"><sup>[842]</sup></a></p> + + <p>We thus see that not only do those parts of the skin which bear white + hair differ in a remarkable manner from those bearing <!-- Page 338 + --><span class="pagenum"><a name="page338"></a>{338}</span>hair of any + other colour, but that in addition some great, constitutional difference + must stand in correlation with the colour of the hair; for in the + above-mentioned cases, vegetable poisons caused fever, swelling of the + head, as well as other symptoms, and even death, to all the white or + white-spotted animals.</p> + +<hr class="full" /> + +<p><!-- Page 339 --><span class="pagenum"><a name="page339"></a>{339}</span></p> + +<h3>CHAPTER XXVI.</h3> + +<p class="cenhead">LAWS OF VARIATION, <i>continued</i>—SUMMARY.</p> + +<blockquote class="b1n"> + + <p><span class="scac">ON THE AFFINITY AND COHESION OF HOMOLOGOUS + PARTS</span>—<span class="scac">ON THE VARIABILITY OF MULTIPLE AND + HOMOLOGOUS PARTS</span>—<span class="scac">COMPENSATION OF + GROWTH</span>—<span class="scac">MECHANICAL + PRESSURE</span>—<span class="scac">RELATIVE POSITION OF FLOWERS + WITH RESPECT TO THE AXIS OF THE PLANT, AND OF SEEDS IN THE CAPSULE, AS + INDUCING VARIATION</span>—<span class="scac">ANALOGOUS OR PARALLEL + VARIETIES</span>—<span class="scac">SUMMARY OF THE THREE LAST + CHAPTERS.</span></p> + +</blockquote> + + <p><i>On the Affinity of Homologous Parts.</i>—This law was first + generalised by Geoffroy Saint Hilaire, under the expression of <i>La loi + de l'affinité de soi pour soi</i>. It has been fully discussed and + illustrated by his son, Isidore Geoffroy, with respect to monsters in the + animal kingdom,<a name="NtA_843" href="#Nt_843"><sup>[843]</sup></a> and + by Moquin-Tandon, with respect to monstrous plants. When similar or + homologous parts, whether belonging to the same embryo or to two distinct + embryos, are brought during an early stage of development into contact, + they often blend into a single part or organ; and this complete fusion + indicates some mutual affinity between the parts, otherwise they would + simply cohere. Whether any power exists which tends to bring homologous + parts into contact seems more doubtful. The tendency to complete fusion + is not a rare or exceptional fact. It is exhibited in the most striking + manner by double monsters. Nothing can be more extraordinary than the + manner, as shown in various published plates, in which the corresponding + parts of two embryos become intimately fused together. This is perhaps + best seen in monsters with two heads, which are united, summit to summit, + or face to face, or, Janus-like, back to back, or obliquely side to side. + In one instance of two heads united almost face to face, but a little + obliquely, four ears were developed, and on one side a perfect face, + which was manifestly formed by the union of two <!-- Page 340 --><span + class="pagenum"><a name="page340"></a>{340}</span>half-faces. Whenever + two bodies or two heads are united, each bone, muscle, vessel, and nerve + on the line of junction seems to seek out its fellow, and becomes + completely fused with it. Lereboullet,<a name="NtA_844" + href="#Nt_844"><sup>[844]</sup></a> who carefully studied the development + of double monsters in fishes, observed in fifteen instances the steps by + which two heads gradually became fused into one. In this and other such + cases, no one, I presume, supposes that the two already formed heads + actually blend together, but that the corresponding parts of each head + grow into one during the further progress of development, accompanied as + it always is with incessant absorption and renovation. Double monsters + were formerly thought to be formed by the union of two originally + distinct embryos developed upon distinct vitelli; but now it is admitted + that "their production is due to the spontaneous divarication of the + embryonic mass into two halves;"<a name="NtA_845" + href="#Nt_845"><sup>[845]</sup></a> this, however, is effected by + different methods. But the belief that double monsters originate from the + division of one germ, does not necessarily affect the question of + subsequent fusion, or render less true the law of the affinity of + homologous parts.</p> + + <p>The cautious and sagacious J. Müller,<a name="NtA_846" + href="#Nt_846"><sup>[846]</sup></a> when speaking of Janus-like monsters, + says, that "without the supposition that some kind of affinity or + attraction is exerted between corresponding parts, unions of this kind + are inexplicable." On the other hand, Vrolik, and he is followed by + others, disputes this conclusion, and argues from the existence of a + whole series of monstrosities, graduating from a perfectly double monster + to a mere rudiment of an additional digit, that "an excess of formative + power" is the cause and origin of every monstrous duplicity. That there + are two distinct classes of cases, and that parts may be doubled + independently of the existence of two embryos, is certain; for a single + embryo, or even a single adult animal, may produce doubled organs. Thus + Valentin, as quoted by Vrolik, injured the caudal extremity of an embryo, + and three days afterwards it produced rudiments of a double pelvis and of + double hind limbs. <!-- Page 341 --><span class="pagenum"><a + name="page341"></a>{341}</span>Hunter and others have observed lizards + with their tails reproduced and doubled. When Bonnet divided + longitudinally the foot of the salamander, several additional digits were + occasionally formed. But neither these cases, nor the perfect series from + a double monster to an additional digit, seem to me opposed to the belief + that corresponding parts have a mutual affinity, and consequently tend to + fuse together. A part may be doubled and remain in this state, or the two + parts thus formed may afterwards through the law of affinity become + blended; or two homologous parts in two separate embryos may, through the + same principle, unite and form a single part.</p> + + <p>The law of the affinity and fusion of similar parts applies to the + homologous organs of the same individual animal, as well as to double + monsters. Isidore Geoffroy gives a number of instances of two or more + digits, of two whole legs, of two kidneys, and of several teeth becoming + symmetrically fused together in a more or less perfect manner. Even the + two eyes have been known to unite into a single eye, forming a cyclopean + monster, as have the two ears, though naturally standing so far apart. As + Geoffroy remarks, these facts illustrate in an admirable manner the + normal fusion of various organs which during an early embryonic period + are double, but which afterwards always unite into a single median organ. + Organs of this nature are generally found in a permanently double + condition in other members of the same class. These cases of normal + fusion appear to me to afford the strongest support in favour of the + present law. Adjoining parts which are not homologous sometimes cohere; + but this cohesion appears to result from mere juxtaposition, and not from + mutual affinity.</p> + + <p>In the vegetable kingdom Moquin-Tandon<a name="NtA_847" + href="#Nt_847"><sup>[847]</sup></a> gives a long list of cases, showing + how frequently homologous parts, such as leaves, petals, stamens, and + pistils, as well as aggregates of homologous parts, such as buds, + flowers, and fruit, become blended into each other with perfect symmetry. + It is interesting to examine a compound flower of this nature, formed of + exactly double the proper number of sepals, petals, stamens, and pistils, + with each whorl of organs circular, and with no trace left of the <!-- + Page 342 --><span class="pagenum"><a + name="page342"></a>{342}</span>process of fusion. The tendency in + homologous parts to unite during their early development, Moquin-Tandon + considers as one of the most striking laws governing the production of + monsters. It apparently explains a multitude of cases, both in the animal + and vegetable kingdoms; it throws a clear light on many normal structures + which have evidently been formed by the union of originally distinct + parts, and it possesses, as we shall see in a future chapter, much + theoretical interest.</p> + +<hr class="short" /> + + <p><i>On the Variability of Multiple and Homologous + Parts.</i>—Isidore Geoffroy<a name="NtA_848" + href="#Nt_848"><sup>[848]</sup></a> insists that, when any part or organ + is repeated many times in the same animal, it is particularly liable to + vary both in number and structure. With respect to number, the + proposition may, I think, be considered as fully established; but the + evidence is chiefly derived from organic beings living under their + natural conditions, with which we are not here concerned. When the + vertebræ, or teeth, or rays in the fins of fishes, or feathers in the + tails of birds, or petals, stamens, pistils, and seeds in plants, are + very numerous, the number is generally variable. The explanation of this + simple fact is by no means obvious. With respect to the variability in + structure of multiple parts, the evidence is not so decisive; but the + fact, as far as it may be trusted, probably depends on multiple parts + being of less physiological importance than single parts; consequently + their perfect standard of structure has been less rigorously enforced by + natural selection.</p> + +<hr class="short" /> + + <p><i>Compensation of Growth, or Balancement.</i>—This law, as + applied to natural species, was propounded by Goethe and Geoffroy St. + Hilaire at nearly the same time. It implies that, when much organised + matter is used in building up some one part, other parts are starved and + become reduced. Several authors, especially botanists, believe in this + law; others reject it. As far as I can judge, it occasionally holds good; + but its importance has probably been exaggerated. It is scarcely possible + to distinguish between the supposed effects of such compensation of + growth, and the effects of long-continued selection, which <!-- Page 343 + --><span class="pagenum"><a name="page343"></a>{343}</span>may at the + same time lead to the augmentation of one part and the diminution of + another. There can be no doubt that an organ may be greatly increased + without any corresponding diminution in the adjoining parts. To recur to + our former illustration of the Irish elk, it may be asked what part has + suffered in consequence of the immense development of the horns?</p> + + <p>It has already been observed that the struggle for existence does not + bear hard on our domesticated productions; consequently the principle of + economy of growth will seldom affect them, and we ought not to expect to + find frequent evidence of compensation. We have, however, some such + cases. Moquin-Tandon describes a monstrous bean,<a name="NtA_849" + href="#Nt_849"><sup>[849]</sup></a> in which the stipules were enormously + developed, and the leaflets apparently in consequence completely aborted; + this case is interesting, as it represents the natural condition of + <i>Lathyrus aphaca</i>, with its stipules of great size, and its leaves + reduced to mere threads, which act as tendrils. De Candolle<a + name="NtA_850" href="#Nt_850"><sup>[850]</sup></a> has remarked that the + varieties of <i>Raphanus sativus</i> which have small roots yield + numerous seed, valuable from containing oil, whilst those with large + roots are not productive in this latter respect; and so it is with + <i>Brassica asperifolia</i>. The varieties of the potato which produce + tubers very early in the season rarely bear flowers; but Andrew Knight,<a + name="NtA_851" href="#Nt_851"><sup>[851]</sup></a> by checking the growth + of the tubers, forced the plants to flower. The varieties of <i>Cucurbita + pepo</i> which produce large fruit yield, according to Naudin, few in + number; whilst those producing small fruit yield a vast number. Lastly, I + have endeavoured to show in the eighteenth chapter that with many + cultivated plants unnatural treatment checks the full and proper action + of the reproductive organs, and they are thus rendered more or less + sterile; consequently, in the way of compensation, the fruit becomes + greatly enlarged, and, in double flowers, the petals are greatly + increased in number.</p> + + <p>With animals, it has been found difficult to produce cows which should + first yield much milk, and afterwards be capable of <!-- Page 344 + --><span class="pagenum"><a name="page344"></a>{344}</span>fattening + well. With fowls which have large topknots and beards the comb and + wattles are generally much reduced in size. Perhaps the entire absence of + the oil-gland in fantail pigeons may be connected with the great + development of their tails.</p> + +<hr class="short" /> + + <p><i>Mechanical Pressure as a Cause of Modifications.</i>—In some + few cases there is reason to believe that mere mechanical pressure has + affected certain structures. Every one knows that savages alter the shape + of their infants' skulls by pressure at an early age; but there is no + reason to believe that the result is ever inherited. Nevertheless Vrolik + and Weber<a name="NtA_852" href="#Nt_852"><sup>[852]</sup></a> maintain + that the shape of the human head is influenced by the shape of the + mother's pelvis. The kidneys in different birds differ much in form, and + St. Ange<a name="NtA_853" href="#Nt_853"><sup>[853]</sup></a> believes + that this is determined by the form of the pelvis, which again, no doubt, + stands in close relation with their various habits of locomotion. In + snakes, the viscera are curiously displaced, in comparison with their + position in other vertebrates; and this has been attributed by some + authors to the elongation of their bodies; but here, as in so many + previous cases, it is impossible to disentangle any direct result of this + kind from that consequent on natural selection. Godron has argued<a + name="NtA_854" href="#Nt_854"><sup>[854]</sup></a> that the normal + abortion of the spur on the inner side of the flower in Corydalis, is + caused by the buds being closely pressed at a very early period of + growth, whilst under ground, against each other and against the stem. + Some botanists believe that the singular difference in the shape both of + the seed and corolla, in the interior and exterior florets in certain + compositous and umbelliferous plants, is due to the pressure to which the + inner florets are subjected; but this conclusion is doubtful.</p> + + <p>The facts just given do not relate to domesticated productions, and + therefore do not strictly concern us. But here is a more appropriate + case: H. Müller<a name="NtA_855" href="#Nt_855"><sup>[855]</sup></a> has + shown that in <!-- Page 345 --><span class="pagenum"><a + name="page345"></a>{345}</span>short-faced races of the dog some of the + molar teeth are placed in a slightly different position from that which + they occupy in other dogs, especially in those having elongated muzzles; + and as he remarks, any inherited change in the arrangement of the teeth + deserves notice, considering their classificatory importance. This + difference in position is due to the shortening of certain facial bones, + and the consequent want of space; and the shortening results from a + peculiar and abnormal state of the basal cartilages of the bones.</p> + +<p class="cenhead"><i>Relative Position of Flowers with respect to the Axis, and of Seeds +in the Capsule, as inducing Variation.</i></p> + +<blockquote class="b1n"> + + <p>In the thirteenth chapter various peloric flowers were described, and + their production was shown to be due either to arrested development, or + to reversion to a primordial condition. Moquin-Tandon has remarked that + the flowers which stand on the summit of the main stem or of a lateral + branch are more liable to become peloric than those on the sides;<a + name="NtA_856" href="#Nt_856"><sup>[856]</sup></a> and he adduces, + amongst other instances, that of <i>Teucrium campanulatum</i>. In another + Labiate plant grown by me, viz. the <i>Galeobdolon luteum</i>, the + peloric flowers were always produced on the summit of the stem, where + flowers are not usually borne. In Pelargonium, a <i>single</i> flower in + the truss is frequently peloric, and when this occurs I have during + several years invariably observed it to be the central flower. This is of + such frequent occurrence that one observer<a name="NtA_857" + href="#Nt_857"><sup>[857]</sup></a> gives the names of ten varieties + flowering at the same time, in every one of which the central flower was + peloric. Occasionally more than one flower in the truss is peloric, and + then of course the additional ones must be lateral. These flowers are + interesting as showing how the whole structure is correlated. In the + common Pelargonium the upper sepal is produced into a nectary which + coheres with the flower-peduncle; the two upper petals differ a little in + shape from the three lower ones, and are marked with dark shades of + colour; the stamens are graduated in length and upturned. In the peloric + flowers, the nectary aborts; all the petals become alike both in shape + and colour; the stamens are generally reduced in number and become + straight, so that the whole flower resembles that of the allied genus + Erodium. The correlation between these changes is well shown when one of + the two upper petals alone loses its dark mark, for in this case the + nectary does not entirely abort, but is usually much reduced in length.<a + name="NtA_858" href="#Nt_858"><sup>[858]</sup></a></p> + +<p><!-- Page 346 --><span class="pagenum"><a name="page346"></a>{346}</span></p> + + <p>Morren has described<a name="NtA_859" + href="#Nt_859"><sup>[859]</sup></a> a marvellous flask-shaped flower of + the Calceolaria, nearly four inches in length, which was almost + completely peloric; it grew on the summit of the plant, with a normal + flower on each side; Prof. Westwood also has described<a name="NtA_860" + href="#Nt_860"><sup>[860]</sup></a> three similar peloric flowers, which + all occupied a central position on the flower-branches. In the Orchideous + genus, Phalænopsis, the terminal flower has been seen to become + peloric.</p> + + <p>In a Laburnum-tree I observed that about a fourth part of the racemes + produced terminal flowers which had lost their papilionaceous structure. + These were produced after almost all the other flowers on the same + racemes had withered. The most perfectly pelorised examples had six + petals, each marked with black striæ like those on the standard-petal. + The keel seemed to resist the change more than the other petals. + Dutrochet has described<a name="NtA_861" + href="#Nt_861"><sup>[861]</sup></a> an exactly similar case in France, + and I believe these are the only two instances of pelorism in the + laburnum which have been recorded. Dutrochet remarks that the racemes on + this tree do not properly produce a terminal flower, so that, as in the + case of the Galeobdolon, their position as well as their structure are + both anomalies, which no doubt are in some manner related. Dr. Masters + has briefly described another leguminous plant,<a name="NtA_862" + href="#Nt_862"><sup>[862]</sup></a> namely, a species of clover, in which + the uppermost and central flowers were regular or had lost their + papilionaceous structure. In some of these plants the flower-heads were + also proliferous.</p> + + <p>Lastly, Linaria produces two kinds of peloric flowers, one having + simple petals, and the other having them all spurred. The two forms, as + Naudin remarks,<a name="NtA_863" href="#Nt_863"><sup>[863]</sup></a> not + rarely occur on the same plant, but in this case the spurred form almost + invariably stands on the summit of the spike.</p> + + <p>The tendency in the terminal or central flower to become peloric more + frequently than other flowers, probably results from "the bud which + stands on the end of a shoot receiving the most sap; it grows out into a + stronger shoot than those situated lower down."<a name="NtA_864" + href="#Nt_864"><sup>[864]</sup></a> I have discussed the connection + between pelorism and a central position, partly because some few plants + are known normally to produce a terminal flower different in structure + from the lateral ones; but chiefly on account of the following case, in + which we see a tendency to variability or to reversion connected with the + same position. A great judge of Auriculas<a name="NtA_865" + href="#Nt_865"><sup>[865]</sup></a> states that when an Auricula throws + up a side bloom it is pretty sure to keep its character; but that if it + grows from the centre or heart of the plant, whatever the colour of the + edging ought to be, "it is just as likely to come in any other class as + in the one to which it properly belongs." This is so notorious a <!-- + Page 347 --><span class="pagenum"><a name="page347"></a>{347}</span>fact, + that some florists regularly pinch off the central trusses of flowers. + Whether in the highly improved varieties the departure of the central + trusses from their proper type is due to reversion, I do not know. Mr. + Dombrain insists that, whatever may be the commonest kind of imperfection + in each variety, this is generally exaggerated in the central truss. Thus + one variety "sometimes has the fault of producing a little green floret + in the centre of the flower," and in central blooms these become + excessive in size. In some central blooms, sent to me by Mr. Dombrain, + all the organs of the flower were rudimentary in structure, of minute + size, and of a green colour, so that by a little further change all would + have been converted into small leaves. In this case we clearly see a + tendency to prolification—a term which, I may explain to those who + have never attended to botany, means the production of a branch or + flower, or head of flowers, out of another flower. Now Dr. Masters<a + name="NtA_866" href="#Nt_866"><sup>[866]</sup></a> states that the + central or uppermost flower on a plant is generally the most liable to + prolification. Thus, in the varieties of the Auricula, the loss of their + proper character and a tendency to prolification, and in other plants a + tendency to prolification and pelorism, are all connected together, and + are due either to arrested development, or to reversion to a former + condition.</p> + + <p>The following is a more interesting case; Metzger<a name="NtA_867" + href="#Nt_867"><sup>[867]</sup></a> cultivated in Germany several kinds + of maize brought from the hotter parts of America, and he found, as has + been previously described, that in two or three generations the grains + became greatly changed in form, size, and colour; and with respect to two + races he expressly states that in the first generation, whilst the lower + grains on each head retained their proper character, the uppermost grains + already began to assume that character which in the third generation all + the grains acquired. As we do not know the aboriginal parent of the + maize, we cannot tell whether these changes are in any way connected with + reversion.</p> + + <p>In the two following cases, reversion, as influenced by the position + of the seed in the capsule, evidently acts. The Blue Imperial pea is the + offspring of the Blue Prussian, and has larger seed and broader pods than + its parent. Now Mr. Masters, of Canterbury, a careful observer and a + raiser of new varieties of the pea, states<a name="NtA_868" + href="#Nt_868"><sup>[868]</sup></a> that the Blue Imperial always has a + strong tendency to revert to its parent-stock, and the reversion "occurs + in this manner: the last (or uppermost) pea in the pod is frequently much + smaller than the rest; and if these small peas are carefully collected + and sown separately, very many more, in proportion, will revert to their + origin, than those taken from the other parts of the pod." Again M. + Chaté<a name="NtA_869" href="#Nt_869"><sup>[869]</sup></a> says that in + raising seedling stocks he succeeds in getting eighty per cent. to bear + double flowers, by leaving only a few of the secondary branches to seed; + but in addition to this, "at the time of extracting the seeds, the upper + portion of the pod is separated and <!-- Page 348 --><span + class="pagenum"><a name="page348"></a>{348}</span>placed aside, because + it has been ascertained that the plants coming from the seeds situated in + this portion of the pod, give eighty per cent. of single flowers." Now + the production of single-flowering plants from the seed of + double-flowering plants is clearly a case of reversion. These latter + facts, as well as the connection between a central position and pelorism + and prolification, show in an interesting manner how small a + difference—namely a little greater freedom in the flow of sap + towards one part of the same plant—determines important changes of + structure.</p> + +</blockquote> + +<hr class="short" /> + + <p><i>Analogous or Parallel Variation.</i>—By this term I wish to + express that similar characters occasionally make their appearance in the + several varieties or races descended from the same species, and more + rarely in the offspring of widely distinct species. We are here + concerned, not as hitherto with the causes of variation, but with the + results; but this discussion could not have been more conveniently + introduced elsewhere. The cases of analogous variation, as far as their + origin is concerned, may be grouped, disregarding minor subdivisions, + under two main heads; firstly, those due to unknown causes having acted + on organic beings with nearly the same constitution, and which + consequently vary in an analogous manner; and secondly, those due to the + reappearance of characters which were possessed by a more or less remote + progenitor. But these two main divisions can often be only conjecturally + separated, and graduate, as we shall presently see, into each other.</p> + +<blockquote class="b1n"> + + <p>Under the first head of analogous variations, not due to reversion, we + have the many cases of trees belonging to quite different orders which + have produced pendulous and fastigate varieties. The beech, hazel, and + barberry have given rise to purple-leaved varieties; and as Bernhardi has + remarked,<a name="NtA_870" href="#Nt_870"><sup>[870]</sup></a> a + multitude of plants, as distinct as possible, have yielded varieties with + deeply-cut or laciniated leaves. Varieties descended from three distinct + species of Brassica have their stems, or so-called roots, enlarged into + globular masses. The nectarine is the offspring of the peach; and the + varieties of both these trees offer a remarkable parallelism in the fruit + being white, red, or yellow fleshed—in being clingstones or + freestones—in the flowers being large or small—in the leaves + being serrated or crenated, furnished with globose or reniform glands, or + quite destitute of glands. It should be remarked that each variety of the + nectarine has not derived its character from a corresponding variety of + the peach. The several varieties also of a closely allied genus, namely + the apricot, differ from each other in nearly the same parallel manner. + There is no reason <!-- Page 349 --><span class="pagenum"><a + name="page349"></a>{349}</span>to believe that in any of these cases + long-lost characters have reappeared, and in most of them this certainly + has not occurred.</p> + + <p>Three species of Cucurbita have yielded a multitude of races, which + correspond so closely in character that, as Naudin insists, they may be + arranged in an almost strictly parallel series. Several varieties of the + melon are interesting from resembling in important characters other + species, either of the same genus or of allied genera; thus, one variety + has fruit so like, both externally and internally, the fruit of a + perfectly distinct species, namely, the cucumber, as hardly to be + distinguished from it; another has long cylindrical fruit twisting about + like a serpent; in another the seeds adhere to portions of the pulp; in + another the fruit, when ripe, suddenly cracks and falls into pieces; and + all these highly remarkable peculiarities are characteristic of species + belonging to allied genera. We can hardly account for the appearance of + so many unusual characters by reversion to a single ancient form; but we + must believe that all the members of the family have inherited a nearly + similar constitution from an early progenitor. Our cereal and many other + plants offer similar cases.</p> + + <p>With animals we have fewer cases of analogous variation, independently + of direct reversion. We see something of the kind in the resemblance + between the short-muzzled races of the dog, such as the pug and bulldog; + in feather-footed races of the fowl, pigeon, and canary-bird; in horses + of the most different races presenting the same range of colour; in all + black-and-tan dogs having tan-coloured eye-spots and feet, but in this + latter case reversion may possibly have played a part. Low has remarked<a + name="NtA_871" href="#Nt_871"><sup>[871]</sup></a> that several breeds of + cattle are "sheeted,"—that is, have a broad band of white passing + round their bodies like a sheet; this character is strongly inherited and + sometimes originates from a cross; it may be the first step in reversion + to an original or early type, for, as was shown in the third chapter, + white cattle with dark ears, feet, and tip of tail formerly existed, and + now exist in a feral or semi-feral condition in several quarters of the + world.</p> + + <p>Under our second main division, namely, of analogous variations due to + reversion, the best cases are afforded by animals, and by none better + than by pigeons. In all the most distinct breeds sub-varieties + occasionally appear coloured exactly like the parent rock-pigeon, with + black wing-bars, white loins, banded tail, &c.; and no one can doubt + that these characters are simply due to reversion. So with minor details; + turbits properly have white tails, but occasionally a bird is born with a + dark-coloured and banded tail; pouters properly have white primary + wing-feathers, but not rarely a "sword-flighted" bird, that is, one with + the few first primaries dark-coloured, appears; and in these cases we + have characters proper to the rock-pigeon, but new to the breed, + evidently appearing from reversion. In some domestic varieties the + wing-bars, instead of being simply black, as in the rock-pigeon, are + beautifully edged with different zones of colour, and they then present a + striking analogy with the wing-bars in certain natural species of the + same family, such as <i>Phaps chalcoptera</i>; and this may probably be + accounted for by <!-- Page 350 --><span class="pagenum"><a + name="page350"></a>{350}</span>all the forms descended from the same + remote progenitor having a tendency to vary in the same manner. Thus also + we can perhaps understand the fact of some Laugher-pigeons cooing almost + like turtle-doves, and of several races having peculiarities in their + flight, for certain natural species (viz. <i>C. torquatrix</i> and + <i>palumbus</i>) display singular vagaries in this respect. In other + cases a race, instead of imitating in character a distinct species, + resembles some other race; thus certain runts tremble and slightly + elevate their tails, like fantails; and turbits inflate the upper part of + their œsophagus, like pouter-pigeons.</p> + + <p>It is a common circumstance to find certain coloured marks + persistently characterising all the species of a genus, but differing + much in tint; and the same thing occurs with the varieties of the pigeon: + thus, instead of the general plumage being blue with the wing-bars black, + there are snow-white varieties with red bars, and black varieties with + white bars; in other varieties the wing-bars, as we have seen, are + elegantly zoned with different tints. The Spot pigeon is characterised by + the whole plumage being white, excepting the tail and a spot on the + forehead; but these parts may be red, yellow, or black. In the + rock-pigeon and in many varieties the tail is blue, with the outer edges + of the outer feathers white; but in one sub-variety of the monk-pigeon we + have a reversed variation, for the tail is white, except the outer edges + of the outer feathers, which are black.<a name="NtA_872" + href="#Nt_872"><sup>[872]</sup></a></p> + + <p>With some species of birds, for instance with gulls, certain coloured + parts appear as if almost washed out, and I have observed exactly the + same appearance in the terminal dark tail-bar in certain pigeons, and in + the whole plumage of certain varieties of the duck. Analogous facts in + the vegetable kingdom could be given.</p> + + <p>Many sub-varieties of the pigeon have reversed and somewhat lengthened + feathers on the back part of their heads, and this is certainly not due + to reversion to the parent-species, which shows no trace of such + structure; but when we remember that sub-varieties of the fowl, turkey, + canary-bird, duck, and goose, all have topknots or reversed feathers on + their heads; and when we remember that scarcely a single large natural + group of birds can be named, in which some members have not a tuft of + feathers on their heads, we may suspect that reversion to some extremely + remote form has come into action.</p> + + <p>Several breeds of the fowl have either spangled or pencilled feathers; + and these cannot be derived from the parent-species, the <i>Gallus + bankiva</i>; though of course it is possible that an early progenitor of + this species may have been spangled, and a still earlier or a later + progenitor may have been pencilled. But as many gallinaceous birds are + spangled or pencilled, it is a more probable view that the several + domestic breeds of the fowl have acquired this kind of plumage from all + the members of the family inheriting a tendency to vary in a like manner. + The same principle may account for the ewes in certain breeds of sheep + being hornless, like the females of some other hollow-horned ruminants; + it may account for certain domestic cats having slightly-tufted ears, + like those of the lynx; and for the skulls of domestic rabbits often + differing from each <!-- Page 351 --><span class="pagenum"><a + name="page351"></a>{351}</span>other in the same characters by which the + skulls of the various species of the genus Lepus differ.</p> + + <p>I will only allude to one other case, already discussed. Now that we + know that the wild parent of the ass has striped legs, we may feel + confident that the occasional appearance of stripes on the legs of the + domestic ass is due to direct reversion; but this will not account for + the lower end of the shoulder-stripe being sometimes angularly bent or + slightly forked. So, again, when we see dun and other coloured horses + with stripes on the spine, shoulders, and legs, we are led, from reasons + formerly given, to believe that they reappear from direct reversion to + the wild parent-horse. But when horses have two or three shoulder-stripes + with one of them occasionally forked at the lower end, or when they have + stripes on their faces, or as foals are faintly striped over nearly their + whole bodies, with the stripes angularly bent one under the other on the + forehead, or irregularly branched in other parts, it would be rash to + attribute such diversified characters to the reappearance of those proper + to the aboriginal wild horse. As three African species of the genus are + much striped, and as we have seen that the crossing of the unstriped + species often leads to the hybrid offspring being conspicuously + striped—bearing also in mind that the act of crossing certainly + causes the reappearance of long-lost characters—it is a more + probable view that the above-specified stripes are due to reversion, not + to the immediate wild parent-horse, but to the striped progenitor of the + whole genus.</p> + +</blockquote> + + <p>I have discussed this subject of analogous variation at considerable + length, because, in a future work on natural species, it will be shown + that the varieties of one species frequently mock distinct + species—a fact in perfect harmony with the foregoing cases, and + explicable only on the theory of descent. Secondly, because these facts + are important from showing, as remarked in a former chapter, that each + trifling variation is governed by law, and is determined in a much higher + degree by the nature of the organisation, than by the nature of the + conditions to which the varying being has been exposed. Thirdly, because + these facts are to a certain extent related to a more general law, + namely, that which Mr. B. D. Walsh<a name="NtA_873" + href="#Nt_873"><sup>[873]</sup></a> has called the "Law of <i>Equable + Variability</i>," or, as he explains it, "if any given character is very + variable in one species of a group, it will tend to be variable in allied + species; and if any given character is perfectly constant in one species + of a group, it will tend to be constant in allied species."</p> + + <p>This leads me to recall a discussion in the chapter on Selection, in + which it was shown that with domestic races, which are <!-- Page 352 + --><span class="pagenum"><a name="page352"></a>{352}</span>now undergoing + rapid improvement, those parts or characters which are the most valued + vary the most. This naturally follows from recently selected characters + continually tending to revert to their former less improved standard, and + from their being still acted on by the same agencies, whatever these may + be, which first caused the characters in question to vary. The same + principle is applicable to natural species, for, as stated in my 'Origin + of Species,' generic characters are less variable than specific + characters; and the latter are those which have been modified by + variation and natural selection, since the period when all the species + belonging to the same genus branched off from a common progenitor, whilst + generic characters are those which have remained unaltered from a much + more remote epoch, and accordingly are now less variable. This statement + makes a near approach to Mr. Walsh's law of Equable Variability. + Secondary sexual characters, it may be added, rarely serve to + characterise distinct genera, for they usually differ much in the species + of the same genus, and are highly variable in the individuals of the same + species; we have also seen in the earlier chapters of this work how + variable secondary sexual characters become under domestication.</p> + +<p class="cenhead"><i>Summary of the three previous Chapters, on the Laws of Variation.</i></p> + + <p>In the twenty-third chapter we have seen that changed conditions + occasionally act in a definite manner on the organisation, so that all, + or nearly all, the individuals thus exposed become modified in the same + manner. But a far more frequent result of changed conditions, whether + acting directly on the organisation or indirectly through the + reproductive system being affected is indefinite and fluctuating + variability. In the three latter chapters we have endeavoured to trace + some of the laws by which such variability is regulated.</p> + + <p>Increased use adds the size of a muscle, together with the + blood-vessels, nerves, ligaments, the crests of bone to which these are + attached, the whole bone and other connected bones. So it is with various + glands. Increased functional activity strengthens the sense-organs. + Increased and intermittent pressure thickens the epidermis; and a change + in the nature of the food sometimes modifies the coats of the stomach, + and increases or <!-- Page 353 --><span class="pagenum"><a + name="page353"></a>{353}</span>decreases the length of the intestines. + Continued disuse, on the other hand, weakens and diminishes all parts of + the organisation. Animals which during many generations have taken but + little exercise, have their lungs reduced in size, and as a consequence + the bony fabric of the chest, and the whole form of the body, become + modified. With our anciently domesticated birds, the wings have been + little used, and they are slightly reduced; with their decrease, the + crest of the sternum, the scapulæ, coracoids, and furcula, have all been + reduced.</p> + + <p>With domesticated animals, the reduction of a part from disuse is + never carried so far that a mere rudiment is left, but we have good + reason to believe that this has often occurred under nature. The cause of + this difference probably is that with domestic animals not only + sufficient time has not been granted for so profound a change, but that, + from not being exposed to a severe struggle for life, the principle of + the economy of organisation does not come into action. On the contrary, + we sometimes see that structures which are rudimentary in the + parent-species become partially redeveloped in their domesticated + progeny. When rudiments are formed or left under domestication, they are + the result of a sudden arrest of development, and not of long-continued + disuse with the absorption of all superfluous parts; nevertheless they + are of interest, as showing that rudiments are the relics of organs once + perfectly developed.</p> + + <p>Corporeal, periodical, and mental habits, though the latter have been + almost passed over in this work, become changed under domestication, and + the changes are often inherited. Such changed habits in any organic + being, especially when living a free life, would often lead to the + augmented or diminished use of various organs, and consequently to their + modification. From long-continued habit, and more especially from the + occasional birth of individuals with a slightly different constitution, + domestic animals and cultivated plants become to a certain extent + acclimatised, or adapted to a climate different from that proper to the + parent-species.</p> + + <p>Through the principle of correlated variability, when one part varies + other parts vary,—either simultaneously, or one after the other. + Thus an organ modified during an early embryonic period affects other + parts subsequently developed. When an <!-- Page 354 --><span + class="pagenum"><a name="page354"></a>{354}</span>organ, such as the + beak, increases or decreases in length, adjoining or correlated parts, as + the tongue and the orifice of the nostrils, tend to vary in the same + manner. When the whole body increases or decreases in size, various parts + become modified; thus with pigeons the ribs increase or decrease in + number and breadth. Homologous parts, which are identical during their + early development and are exposed to similar conditions, tend to vary in + the same or in some connected manner,—as in the case of the right + and left sides of the body, of the front and hind limbs, and even of the + head and limbs. So it is with the organs of sight and hearing; for + instance, white cats with blue eyes are almost always deaf. There is a + manifest relation throughout the body between the skin and its various + appendages of hair, feathers, hoofs, horns, and teeth. In Paraguay, + horses with curly hair have hoofs like those of a mule; the wool and the + horns of sheep vary together; hairless dogs are deficient in their teeth; + men with redundant hair have abnormal teeth, either deficient or in + excess. Birds with long wing-feathers usually have long tail-feathers. + When long feathers grow from the outside of the legs and toes of pigeons, + the two outer toes are connected by membrane; for the whole leg tends to + assume the structure of the wing. There is a manifest relation between a + crest of feathers on the head and a marvellous amount of change in the + skull of various fowls; and in a lesser degree, between the greatly + elongated, lopping ears of rabbits and the structure of their skulls. + With plants, the leaves, various parts of the flower, and the fruit, + often vary together in a correlated manner.</p> + + <p>In some cases we find correlation without being able even to + conjecture what is the nature of the connexion, as with various + correlated monstrosities and diseases. This is likewise the case with the + colour of the adult pigeon, in connexion with the presence of down on the + young bird. Numerous curious instances have been given of peculiarities + of constitution, in correlation with colour, as shown by the immunity of + individuals of some one colour from certain diseases, from the attacks of + parasites, and from the action of certain vegetable poisons.</p> + + <p>Correlation is an important subject; for with species, and in a lesser + degree with domestic races, we continually find that <!-- Page 355 + --><span class="pagenum"><a name="page355"></a>{355}</span>certain parts + have been greatly modified to serve some useful purpose; but we almost + invariably find that other parts have likewise been more or less + modified, without our being able to discover any advantage in the change. + No doubt great caution is necessary in coming to this conclusion, for it + is difficult to overrate our ignorance on the use of various parts of the + organisation; but from what we have now seen, we may believe that many + modifications are of no direct service, having arisen in correlation with + other and useful changes.</p> + + <p>Homologous parts during their early development evince an affinity for + each other,—that is, they tend to cohere and fuse together much + more readily than other parts. This tendency to fusion explains a + multitude of normal structures. Multiple and homologous organs are + especially liable to vary in number and probably in form. As the supply + of organised matter is not unlimited, the principle of compensation + sometimes comes into action; so that, when one part is greatly developed, + adjoining parts or functions are apt to be reduced; but this principle is + probably of much less importance than the more general one of the economy + of growth. Through mere mechanical pressure hard parts occasionally + affect soft adjoining parts. With plants the position of the flowers on + the axis, and of the seeds in the capsule, sometimes leads, through a + freer flow of sap, to changes of structure; but these changes are often + due to reversion. Modifications, in whatever manner caused, will be to a + certain extent regulated by that co-ordinating power or <i>nisus + formativus</i>, which is in fact a remnant of one of the forms of + reproduction, displayed by many lowly organised beings in their power of + fissiparous generation and budding. Finally, the effects of the laws, + which directly or indirectly govern variability, may be largely + influenced by man's selection, and will so far be determined by natural + selection that changes advantageous to any race will be favoured and + disadvantageous changes checked.</p> + + <p>Domestic races descended from the same species, or from two or more + allied species, are liable to revert to characters derived from their + common progenitor, and, as they have much in common in their + constitutions, they are also liable under changed conditions to vary in + the same manner; from these <!-- Page 356 --><span class="pagenum"><a + name="page356"></a>{356}</span>two causes analogous varieties often + arise. When we reflect on the several foregoing laws, imperfectly as we + understand them, and when we bear in mind how much remains to be + discovered, we need not be surprised at the extremely intricate manner in + which our domestic productions have varied, and still go on varying.</p> + +<hr class="full" /> + +<p><!-- Page 357 --><span class="pagenum"><a name="page357"></a>{357}</span></p> + +<h3>CHAPTER XXVII.</h3> + +<p class="cenhead">PROVISIONAL HYPOTHESIS OF PANGENESIS.</p> + +<blockquote class="b1n"> + + <p><span class="scac">PRELIMINARY REMARKS.</span>—<span + class="scac">FIRST PART:</span>—<span class="scac">THE FACTS TO BE + CONNECTED UNDER A SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF + REPRODUCTION</span>—<span class="scac">THE DIRECT ACTION OF THE + MALE ELEMENT ON THE FEMALE</span>—<span + class="scac">DEVELOPMENT</span>—<span class="scac">THE FUNCTIONAL + INDEPENDENCE OF THE ELEMENTS OR UNITS OF THE BODY</span>—<span + class="scac">VARIABILITY</span>—<span + class="scac">INHERITANCE</span>—<span + class="scac">REVERSION.</span></p> + + <p><span class="scac">SECOND PART:</span>—<span + class="scac">STATEMENT OF THE HYPOTHESIS</span>—<span + class="scac">HOW FAR THE NECESSARY ASSUMPTIONS ARE + IMPROBABLE</span>—<span class="scac">EXPLANATION BY AID OF THE + HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST + PART</span>—<span class="scac">CONCLUSION.</span></p> + +</blockquote> + + <p>In the previous chapters large classes of facts, such as those bearing + on bud-variation, the various forms of inheritance, the causes and laws + of variation, have been discussed; and it is obvious that these subjects, + as well as the several modes of reproduction, stand in some sort of + relation to each other. I have been led, or rather forced, to form a view + which to a certain extent connects these facts by a tangible method. + Every one would wish to explain to himself, even in an imperfect manner, + how it is possible for a character possessed by some remote ancestor + suddenly to reappear in the offspring; how the effects of increased or + decreased use of a limb can be transmitted to the child; how the male + sexual element can act not solely on the ovule, but occasionally on the + mother-form; how a limb can be reproduced on the exact line of + amputation, with neither too much nor too little added; how the various + modes of reproduction are connected, and so forth. I am aware that my + view is merely a provisional hypothesis or speculation; but until a + better one be advanced, it may be serviceable by bringing together a + multitude of facts which are at present left disconnected by any + efficient cause. As Whewell, the historian of the inductive sciences, + remarks:—"Hypotheses may often be of service to science, when they + involve a certain portion of incompleteness, and even of error." Under + this point of view I venture to advance the hypothesis of Pangenesis, + which <!-- Page 358 --><span class="pagenum"><a + name="page358"></a>{358}</span>implies that the whole organisation, in + the sense of every separate atom or unit, reproduces itself. Hence ovules + and pollen-grains,—the fertilised seed or egg, as well as + buds,—include and consist of a multitude of germs thrown off from + each separate atom of the organism.</p> + + <p>In the First Part I will enumerate as briefly as I can the groups of + facts which seem to demand connection; but certain subjects, not hitherto + discussed, must be treated at disproportionate length. In the Second Part + the hypothesis will be given; and we shall see, after considering how far + the necessary assumptions are in themselves improbable, whether it serves + to bring under a single point of view the various facts.</p> + +<p class="cenhead"><span class="sc">Part I.</span></p> + + <p>Reproduction may be divided into two main classes, namely, sexual and + asexual. The latter is effected in many ways—by gemmation, that is + by the formation of buds of various kinds, and by fissiparous generation, + that is by spontaneous or artificial division. It is notorious that some + of the lower animals, when cut into many pieces, reproduce so many + perfect individuals: Lyonnet cut a Nais or freshwater worm into nearly + forty pieces, and these all reproduced perfect animals.<a name="NtA_874" + href="#Nt_874"><sup>[874]</sup></a> It is probable that segmentation + could be carried much further in some of the protozoa, and with some of + the lowest plants each cell will reproduce the parent-form. Johannes + Müller thought that there was an important distinction between gemmation + and fission; for in the latter case the divided portion, however small, + is more perfectly organised; but most physiologists are now convinced + that the two processes are essentially alike.<a name="NtA_875" + href="#Nt_875"><sup>[875]</sup></a> Prof. Huxley remarks, "fission is + little more than a peculiar <!-- Page 359 --><span class="pagenum"><a + name="page359"></a>{359}</span>mode of budding," and Prof. H. J. Clark, + who has especially attended to this subject, shows in detail that there + is sometimes "a compromise between self-division and budding." When a + limb is amputated, or when the whole body is bisected, the cut + extremities are said to bud forth; and as the papilla, which is first + formed, consists of undeveloped cellular tissue like that forming an + ordinary bud, the expression is apparently correct. We see the connection + of the two processes in another way; for Trembley observed that with the + hydra the reproduction of the head after amputation was checked as soon + as the animal began to bud.<a name="NtA_876" + href="#Nt_876"><sup>[876]</sup></a></p> + + <p>Between the production, by fissiparous generation, of two or more + complete individuals, and the repair of even a very slight injury, we + have, as remarked in a former chapter, so perfect and insensible a + gradation, that it is impossible to doubt that they are connected + processes. Between the power which repairs a trifling injury in any part, + and the power which previously "was occupied in its maintenance by the + continued mutation of its particles," there cannot be any great + difference; and we may follow Mr. Paget in believing them to be the + selfsame power. As at each stage of growth an amputated part is replaced + by one in the same state of development, we must likewise follow Mr. + Paget in admitting "that the powers of development from the embryo are + identical with those exercised for the restoration from injuries: in + other words, that the powers are the same by which perfection is first + achieved, and by which, when lost, it is recovered."<a name="NtA_877" + href="#Nt_877"><sup>[877]</sup></a> Finally, we may conclude that the + several forms of gemmation, and of fissiparous generation, the repair of + injuries, the maintenance of each part in its proper state, and the + growth or progressive development of the whole structure of the embryo, + are all essentially the results of one and the same great power.</p> + + <p><i>Sexual Generation.</i>—The union of the two sexual elements + seems to make a broad distinction between sexual and asexual + reproduction. But the well-ascertained cases of Parthenogenesis prove + that the distinction is not really so great as it at first appears; for + ovules occasionally, and even in some cases <!-- Page 360 --><span + class="pagenum"><a name="page360"></a>{360}</span>frequently, become + developed into perfect beings, without the concourse of the male element. + J. Müller and others admit that ovules and buds have the same essential + nature. Certain bodies, which during their early development cannot be + distinguished by any external character from true ovules, nevertheless + must be classed as buds, for though formed within the ovarium they are + incapable of fertilisation. This is the case with the germ-balls of the + Cecidomyide larvæ, as described by Leuckart.<a name="NtA_878" + href="#Nt_878"><sup>[878]</sup></a> Ovules and the male element, before + they become united, have, like buds, an independent existence.<a + name="NtA_879" href="#Nt_879"><sup>[879]</sup></a> Both have the power of + transmitting every single character possessed by the parent-form. We see + this clearly when hybrids are paired <i>inter se</i>, for the characters + of either grandparent often reappear, either perfectly or by segments, in + the progeny. It is an error to suppose that the male transmits certain + characters and the female other characters; though no doubt, from unknown + causes, one sex sometimes has a stronger power of transmission than the + other.</p> + + <p>It has been maintained by some authors that a bud differs essentially + from a fertilised germ, by always reproducing the perfect character of + the parent-stock; whilst fertilised germs become developed into beings + which differ, in a greater or less degree, from each other and from their + parents. But there is no such broad distinction as this. In the eleventh + chapter, numerous cases were given showing that buds occasionally grow + into plants having new and strongly marked characters; and varieties thus + produced can be propagated for a length of time by buds, and occasionally + by seed. Nevertheless, it must be admitted that beings produced sexually + are much more liable to vary than those produced asexually; and of this + fact a partial explanation will hereafter be attempted. The variability + in both cases is determined by the same general causes, and is governed + by the same laws. Hence new varieties arising from buds cannot be + distinguished from those arising from seed. Although bud-varieties + usually retain their character during <!-- Page 361 --><span + class="pagenum"><a name="page361"></a>{361}</span>successive + bud-generations, yet they occasionally revert, even after a long series + of bud-generations, to their former character. This tendency to reversion + in buds is one of the most remarkable of the several points of agreement + between the offspring from bud and seminal reproduction.</p> + + <p>There is, however, one difference between beings produced sexually and + asexually, which is very general. The former usually pass in the course + of their development from a lower to a higher grade, as we see in the + metamorphoses of insects and in the concealed metamorphoses of the + vertebrata; but this passage from a lower to a higher grade cannot be + considered as a necessary accompaniment of sexual reproduction, for + hardly anything of the kind occurs in the development of Aphis amongst + insects, or with certain crustaceans, cephalopods, or with any of the + higher vascular plants. Animals propagated asexually by buds or fission + are on the other hand never known to undergo a retrogressive + metamorphosis; that is, they do not first sink to a lower, before passing + on to their higher and final stage of development. But during the act of + asexual production or subsequently to it, they often advance in + organisation, as we see in the many cases of "alternate generation." In + thus speaking of alternate generation, I follow those naturalists who + look at the process as essentially one of internal budding or of + fissiparous generation. Some of the lower plants, however, such as mosses + and certain algæ, according to Dr. L. Radlkofer,<a name="NtA_880" + href="#Nt_880"><sup>[880]</sup></a> when propagated asexually, do undergo + a retrogressive metamorphosis. We can to a certain extent understand, as + far as the final cause is concerned, why beings propagated by buds should + so rarely retrogress during development; for with each organism the + structure acquired at each stage of development must be adapted to its + peculiar habits. Now, with beings produced by gemmation,—and this, + differently from sexual reproduction, may occur at any period of + growth,—if there were places for the support of many individuals at + some one stage of development, the simplest plan would be that they + should be multiplied by gemmation at that stage, and not that they should + first retrograde in their development to an earlier or simpler structure, + which might not be fitted for the surrounding conditions.</p> + +<p><!-- Page 362 --><span class="pagenum"><a name="page362"></a>{362}</span></p> + + <p>From the several foregoing considerations we may conclude that the + difference between sexual and asexual generation is not nearly so great + as it at first appears; and we have already seen that there is the + closest agreement between gemmation, fissiparous generation, the repair + of injuries, and ordinary growth or development. The capacity of + fertilisation by the male element seems to be the chief distinction + between an ovule and a bud; and this capacity is not invariably brought + into action, as in the cases of parthenogenetic reproduction. We are here + naturally led to inquire what the final cause can be of the necessity in + ordinary generation for the concourse of the two sexual elements.</p> + + <p>Seeds and ova are often highly serviceable as the means of + disseminating plants and animals, and of preserving them during one or + more seasons in a dormant state; but unimpregnated seeds or ova, and + detached buds, would be equally serviceable for both purposes. We can, + however, indicate two important advantages gained by the concourse of the + two sexes, or rather of two individuals belonging to opposite sexes; for, + as I have shown in a former chapter, the structure of every organism + appears to be especially adapted for the concurrence, at least + occasionally, of two individuals. In nearly the same manner as it is + admitted by naturalists that hybridism, from inducing sterility, is of + service in keeping the forms of life distinct and fitted for their proper + places; so, when species are rendered highly variable by changed + conditions of life, the free intercrossing of the varying individuals + will tend to keep each form fitted for its proper place in nature; and + crossing can be effected only by sexual generation, but whether the end + thus gained is of sufficient importance to account for the first origin + of sexual intercourse is very doubtful. Secondly, I have shown, from the + consideration of a large body of facts, that, as a slight change in the + conditions of life is beneficial to each creature, so, in an analogous + manner, is the change effected in the germ by sexual union with a + distinct individual; and I have been led, from observing the many + widely-extended provisions throughout nature for this purpose, and from + the greater vigour of crossed organisms of all kinds, as proved by direct + experiments, as well as from the evil effects of close interbreeding when + long <!-- Page 363 --><span class="pagenum"><a + name="page363"></a>{363}</span>continued, to believe that the advantage + thus gained is very great. Besides these two important ends, there may, + of course, be others, as yet unknown to us, gained by the concourse of + the two sexes.</p> + + <p>Why the germ, which before impregnation undergoes a certain amount of + development, ceases to progress and perishes, unless it be acted on by + the male element; and why conversely the male element, which is enabled + to keep alive for even four or five years within the spermatheca of a + female insect, likewise perishes, unless it acts on or unites with the + germ, are questions which cannot be answered with any certainty. It is, + however, possible that both sexual elements perish, unless brought into + union, simply from including too little formative matter for independent + existence and development; for certainly they do not in ordinary cases + differ in their power of giving character to the embryo. This view of the + importance of the quantity of formative matter seems probable from the + following considerations. There is no reason to suspect that the + spermatozoa or pollen-grains of the same individual animal or plant + differ from each other; yet Quatrefages has shown in the case of the + Teredo,<a name="NtA_881" href="#Nt_881"><sup>[881]</sup></a> as did + formerly Prevost and Dumas with other animals, that more than one + spermatozoon is requisite to fertilise an ovule. This has likewise been + clearly proved by Newport,<a name="NtA_882" + href="#Nt_882"><sup>[882]</sup></a> who adds the important fact, + established by numerous experiments, that, when a very small number of + spermatozoa are applied to the ova of Batrachians, they are only + partially impregnated and the embryo is never fully developed: the first + step, however, towards development, namely, the partial segmentation of + the yelk, does occur to a greater or less extent, but is never completed + up to granulation. The rate of the segmentation is likewise determined by + the number of the spermatozoa. With respect to plants, nearly the same + results were obtained by Kölreuter and Gärtner. This last careful + observer found,<a name="NtA_883" href="#Nt_883"><sup>[883]</sup></a> + after making successive trials on a Malva with more and more + pollen-grains, that even thirty grains did not fertilise a single seed; + but when forty grains were applied to the <!-- Page 364 --><span + class="pagenum"><a name="page364"></a>{364}</span>stigma, a few seeds of + small size were formed. The pollen-grains of Mirabilis are + extraordinarily large, and the ovarium contains only a single ovule; and + these circumstances led Naudin<a name="NtA_884" + href="#Nt_884"><sup>[884]</sup></a> to make the following interesting + experiments: a flower was fertilised by three grains and succeeded + perfectly; twelve flowers were fertilised by two grains, and seventeen + flowers by a single grain, and of these one flower alone in each lot + perfected its seed; and it deserves especial notice that the plants + produced by these two seeds never attained their proper dimensions, and + bore flowers of remarkably small size. From these facts we clearly see + that the quantity of the peculiar formative matter which is contained + within the spermatozoa and pollen-grains is an all-important element in + the act of fertilisation, not only in the full development of the seed, + but in the vigour of the plant produced from such seed. We see something + of the same kind in certain cases of parthenogenesis, that is, when the + male element is wholly excluded; for M. Jourdan<a name="NtA_885" + href="#Nt_885"><sup>[885]</sup></a> found that, out of about 58,000 eggs + laid by unimpregnated silk-moths, many passed through their early + embryonic stages, showing that they were capable of self-development, but + only twenty-nine out of the whole number produced caterpillars. Therefore + it is not an improbable view that deficient bulk or quantity in the + formative matter, contained within the sexual elements, is the main cause + of their not having the capacity of prolonged separate existence and + development. The belief that it is the function of the spermatozoa to + communicate life to the ovule seems a strange one, seeing that the + unimpregnated ovule is already alive and continues for a considerable + time alive. We shall hereafter see that it is probable that the sexual + elements, or possibly only the female element, include certain primordial + cells, that is, such as have undergone no differentiation, and which are + not present in an active state in buds.</p> + + <p><i>Graft-hybrids.</i>—When discussing in the eleventh chapter + the curious case of the <i>Cytisus adami</i>, facts were given which + render it to a certain degree probable, in accordance with the belief of + some distinguished botanists, that, when the tissues of two plants <!-- + Page 365 --><span class="pagenum"><a + name="page365"></a>{365}</span>belonging to distinct species or varieties + are intimately united, buds are afterwards occasionally produced which, + like hybrids, combine the characters of the two united forms. It is + certain that when trees with variegated leaves are grafted or budded on a + common stock, the latter sometimes produces buds bearing variegated + leaves; but this may perhaps be looked at as a case of inoculated + disease. Should it ever be proved that hybridised buds can be formed by + the union of two distinct vegetative tissues, the essential identity of + sexual and asexual reproduction would be shown in the most interesting + manner; for the power of combining in the offspring the characters of + both parents, is the most striking of all the functions of sexual + generation.</p> + + <p><i>Direct Action of the Male Element on the Female.</i>—In the + chapter just referred to, I have given abundant proofs that foreign + pollen occasionally affects the mother-plant in a direct manner. Thus, + when Gallesio fertilised an orange-flower with pollen from the lemon, the + fruit bore stripes of perfectly characterised lemon-peel: with peas, + several observers have seen the colour of the seed-coats and even of the + pod directly affected by the pollen of a distinct variety; so it has been + with the fruit of the apple, which consists of the modified calyx and + upper part of the flower-stalk. These parts in ordinary cases are wholly + formed by the mother-plant. We here see the male element affecting and + hybridising not that part which it is properly adapted to affect, namely + the ovule, but the partially developed tissues of a distinct individual. + We are thus brought half-way towards a graft-hybrid, in which the + cellular tissue of one form, instead of its pollen, is believed to + hybridise the tissues of a distinct form. I formerly assigned reasons for + rejecting the belief that the mother-plant is affected through the + intervention of the hybridised embryo; but even if this view were + admitted, the case would become one of graft-hybridism, for the + fertilised embryo and the mother-plant must be looked at as distinct + individuals.</p> + + <p>With animals which do not breed until nearly mature, and of which all + the parts are then fully developed, it is hardly possible that the male + element should directly affect the female. But we have the analogous and + perfectly well-ascertained case of the male element of a distinct form, + as with the <!-- Page 366 --><span class="pagenum"><a + name="page366"></a>{366}</span>quagga and Lord Morton's mare, affecting + the ovarium of the female, so that the ovules and offspring subsequently + produced by her when impregnated by other males are plainly affected and + hybridised by the first male.</p> + + <p><i>Development.</i>—The fertilised germ reaches maturity by a + vast number of changes: these are either slight and slowly effected, as + when the child grows into the man, or are great and sudden, as with the + metamorphoses of most insects. Between these extremes we have, even + within the same class, every gradation: thus, as Sir J. Lubbock has + shown,<a name="NtA_886" href="#Nt_886"><sup>[886]</sup></a> there is an + Ephemerous insect which moults above twenty times, undergoing each time a + slight but decided change of structure; and these changes, as he further + remarks, probably reveal to us the normal stages of development which are + concealed and hurried through, or suppressed, in most other insects. In + ordinary metamorphoses, the parts and organs appear to become changed + into the corresponding parts in the next stage of development; but there + is another form of development, which has been called by Professor Owen + metagenesis. In this case "the new parts are not moulded upon the inner + surface of the old ones. The plastic force has changed its course of + operation. The outer case, and all that gave form and character to the + precedent individual, perish and are cast off; they are not changed into + the corresponding parts of the new individual. These are due to a new and + distinct developmental process," &c.<a name="NtA_887" + href="#Nt_887"><sup>[887]</sup></a> Metamorphosis, however, graduates so + insensibly into metagenesis, that the two processes cannot be distinctly + separated. For instance, in the last change which Cirripedes undergo, the + alimentary canal and some other organs are moulded on pre-existing parts; + but the eyes of the old and the young animal are developed in entirely + different parts of the body; the tips of the mature limbs are formed + within the larval limbs, and may be said to be metamorphosed from them; + but their basal portions and the whole thorax are developed in a plane + actually at right angles to the limbs and thorax of the larva; and this + <!-- Page 367 --><span class="pagenum"><a + name="page367"></a>{367}</span>may be called metagenesis. The metagenetic + process is carried to an extreme degree in the development of some + Echinoderms, for the animal in the second stage of development is formed + almost like a bud within the animal of the first stage, the latter being + then cast off like an old vestment, yet sometimes still maintaining for a + short period an independent vitality.<a name="NtA_888" + href="#Nt_888"><sup>[888]</sup></a></p> + + <p>If, instead of a single individual, several were to be thus developed + metagenetically within a pre-existing form, the process would be called + one of alternate generation. The young thus developed may either closely + resemble the encasing parent-form, as with the larvæ of Cecidomyia, or + may differ to an astonishing degree, as with many parasitic worms and + with jelly-fishes; but this does not make any essential difference in the + process, any more than the greatness or abruptness of the change in the + metamorphoses of insects.</p> + + <p>The whole question of development is of great importance for our + present subject. When an organ, the eye for instance, is metagenetically + formed in a part of the body where during the previous stage of + development no eye existed, we must look at it as a new and independent + growth. The absolute independence of new and old structures, which + correspond in structure and function, is still more obvious when several + individuals are formed within a previous encasing form, as in the cases + of alternate generation. The same important principle probably comes + largely into play even in the case of continuous growth, as we shall see + when we consider the inheritance of modifications at corresponding + ages.</p> + + <p>We are led to the same conclusion, namely, the independence of parts + successively developed, by another and quite distinct group of facts. It + is well known that many animals belonging to the same class, and + therefore not differing widely from each other, pass through an extremely + different course of development. Thus certain beetles, not in any way + remarkably different from others of the same order, undergo what has been + called a hyper-metamorphosis—that is, they pass through an early + stage wholly different from the ordinary grub-like larva. In the same + sub-order of crabs, namely, the Macroura, as Fritz <!-- Page 368 --><span + class="pagenum"><a name="page368"></a>{368}</span>Müller remarks, the + river cray-fish is hatched under the same form which it ever afterwards + retains; the young lobster has divided legs, like a Mysis; the Palæmon + appears under the form of a Zoea, and Peneus under the Nauplius-form; and + how wonderfully these larval forms differ from each other, is known to + every naturalist.<a name="NtA_889" href="#Nt_889"><sup>[889]</sup></a> + Some other crustaceans, as the same author observes, start from the same + point and arrive at nearly the same end, but in the middle of their + development are widely different from each other. Still more striking + cases could be given with respect to the Echinodermata. With the Medusæ + or jelly-fishes Professor Allman observes, "the classification of the + Hydroida would be a comparatively simple task if, as has been erroneously + asserted, generically-identical medusoids always arose from + generically-identical polypoids; and on the other hand, that + generically-identical polypoids always gave origin to + generically-identical medusoids." So, again, Dr. Strethill Wright + remarks, "in the life-history of the Hydroidæ any phase, planuloid, + polypoid, or medusoid, may be absent."<a name="NtA_890" + href="#Nt_890"><sup>[890]</sup></a></p> + + <p>According to the belief now generally accepted by our best + naturalists, all the members of the same order or class, the Macrourous + crustaceans for instance, are descended from a common progenitor. During + their descent they have diverged much in structure, but have retained + much in common; and this divergence and retention of character has been + effected, though they have passed and still pass through marvellously + different metamorphoses. This fact well illustrates how independent each + structure must be from that which precedes and follows it in the course + of development.</p> + + <p><i>The Functional Independence of the Elements or Units of the + Body.</i>—Physiologists agree that the whole organism consists of a + multitude of elemental parts, which are to a great extent independent of + each other. Each organ, says Claude Bernard,<a name="NtA_891" + href="#Nt_891"><sup>[891]</sup></a> <!-- Page 369 --><span + class="pagenum"><a name="page369"></a>{369}</span>has its proper life, + its autonomy; it can develop and reproduce itself independently of the + adjoining tissues. The great German authority, Virchow,<a name="NtA_892" + href="#Nt_892"><sup>[892]</sup></a> asserts still more emphatically that + each system, as the nervous or osseous system, or the blood, consists of + an "enormous mass of minute centres of action.... Every element has its + own special action, and even though it derive its stimulus to activity + from other parts, yet alone effects the actual performance of its + duties.... Every single epithelial and muscular fibre-cell leads a sort + of parasitical existence in relation to the rest of the body.... Every + single bone-corpuscle really possesses conditions of nutrition peculiar + to itself." Each element, as Mr. Paget remarks, lives its appointed time, + and then dies, and, after being cast off or absorbed, is replaced.<a + name="NtA_893" href="#Nt_893"><sup>[893]</sup></a> I presume that no + physiologist doubts that, for instance, each bone-corpuscle of the finger + differs from the corresponding corpuscle in the corresponding joint of + the toe; and there can hardly be a doubt that even those on the + corresponding sides of the body differ, though almost identical in + nature. This near approach to identity is curiously shown in many + diseases in which the same exact points on the right and left sides of + the body are similarly affected; thus Mr. Paget<a name="NtA_894" + href="#Nt_894"><sup>[894]</sup></a> gives a drawing of a diseased pelvis, + in which the bone has grown into a most complicated pattern, but "there + is not one spot or line on one side which is not represented, as exactly + as it would be in a mirror, on the other."</p> + + <p>Many facts support this view of the independent life of each minute + element of the body. Virchow insists that a single bone-corpuscle or a + single cell in the skin may become diseased. The spur of a cock, after + being inserted into the eye of an ox, lived for eight years, and acquired + a weight of 306 grammes, or nearly fourteen ounces.<a name="NtA_895" + href="#Nt_895"><sup>[895]</sup></a> The tail of a pig has been grafted + into the middle of its back, and reacquired sensibility. Dr. Ollier<a + name="NtA_896" href="#Nt_896"><sup>[896]</sup></a> inserted a piece of + periosteum from the bone of a young dog under the skin of a rabbit, and + true bone was developed. A multitude of similar facts could be given. The + <!-- Page 370 --><span class="pagenum"><a + name="page370"></a>{370}</span>frequent presence of hairs and of + perfectly developed teeth, even teeth of the second dentition, in ovarian + tumours,<a name="NtA_897" href="#Nt_897"><sup>[897]</sup></a> are facts + leading to the same conclusion.</p> + + <p>Whether each of the innumerable autonomous elements of the body is a + cell or the modified product of a cell, is a more doubtful question, even + if so wide a definition be given to the term, as to include cell-like + bodies without walls and without nuclei.<a name="NtA_898" + href="#Nt_898"><sup>[898]</sup></a> Professor Lionel Beale uses the term + "germinal matter" for the contents of cells, taken in this wide + acceptation, and he draws a broad distinction between germinal matter and + "formed material" or the various products of cells.<a name="NtA_899" + href="#Nt_899"><sup>[899]</sup></a> But the doctrine of <i>omnis cellula + e cellulâ</i> is admitted for plants, and is a widely prevalent belief + with respect to animals.<a name="NtA_900" + href="#Nt_900"><sup>[900]</sup></a> Thus Virchow, the great supporter of + the cellular theory, whilst allowing that difficulties exist, maintains + that every atom of tissue is derived from cells, and these from + pre-existing cells, and these primarily from the egg, which he regards as + a great cell. That cells, still retaining the same nature, increase by + self-division or proliferation, is admitted by almost every one. But when + an organism undergoes a great change of structure during development, the + cells, which at each stage are supposed to be directly derived from + previously-existing cells, must likewise be greatly changed in nature; + this change is apparently attributed by the supporters of the cellular + doctrine to some inherent power which the cells possess, and not to any + external agency.</p> + + <p>Another school maintains that cells and tissues of all kinds may be + formed, independently of pre-existing cells, from plastic lymph or + blastema; and this it is thought is well exhibited in the repair of + wounds. As I have not especially attended to histology, it would be + presumptuous in me to express an opinion on the two opposed doctrines. + But every one appears to admit that the body consists of a multitude of + "organic units,"<a name="NtA_901" href="#Nt_901"><sup>[901]</sup></a> + <!-- Page 371 --><span class="pagenum"><a + name="page371"></a>{371}</span>each of which possesses its own proper + attributes, and is to a certain extent independent of all others. Hence + it will be convenient to use indifferently the terms cells or organic + units or simply units.</p> + + <p><i>Variability and Inheritance.</i>—We have seen in the + twenty-second chapter that variability is not a principle co-ordinate + with life or reproduction, but results from special causes, generally + from changed conditions acting during successive generations. Part of the + fluctuating variability thus induced is apparently due to the sexual + system being easily affected by changed conditions, so that it is often + rendered impotent; and when not so seriously affected, it often fails in + its proper function of transmitting truly the characters of the parents + to the offspring. But variability is not necessarily connected with the + sexual system, as we see from the cases of bud-variation; and although we + may not be able to trace the nature of the connexion, it is probable that + many deviations of structure which appear in sexual offspring result from + changed conditions acting directly on the organisation, independently of + the reproductive organs. In some instances we may feel sure of this, when + all, or nearly all the individuals which have been similarly exposed are + similarly and definitely affected—as in the dwarfed and otherwise + changed maize brought from hot countries when cultivated in Germany; in + the change of the fleece in sheep within the tropics; to a certain extent + in the increased size and early maturity of our highly-improved + domesticated animals; in inherited gout from intemperance; and in many + other such cases. Now, as such changed conditions do not especially + affect the reproductive organs, it seems mysterious on any ordinary view + why their product, the new organic being, should be similarly + affected.</p> + + <p>How, again, can we explain to ourselves the inherited effects of the + use or disuse of particular organs? The domesticated duck flies less and + walks more than the wild duck, and its limb-bones have become in a + corresponding manner diminished and increased in comparison with those of + the wild duck. A horse is trained to certain paces, and the colt inherits + similar consensual movements. The domesticated rabbit becomes tame from + close confinement; the dog intelligent from associating with man; the + retriever is taught to fetch and carry: and these <!-- Page 372 --><span + class="pagenum"><a name="page372"></a>{372}</span>mental endowments and + bodily powers are all inherited. Nothing in the whole circuit of + physiology is more wonderful. How can the use or disuse of a particular + limb or of the brain affect a small aggregate of reproductive cells, + seated in a distant part of the body, in such a manner that the being + developed from these cells inherits the characters of either one or both + parents? Even an imperfect answer to this question would be + satisfactory.</p> + + <p>Sexual reproduction does not essentially differ, as we have seen, from + budding or self-division, and these processes graduate through the repair + of injuries into ordinary development and growth; it might therefore be + expected that every character would be as regularly transmitted by all + the methods of reproduction as by continued growth. In the chapters + devoted to inheritance it was shown that a multitude of newly-acquired + characters, whether injurious or beneficial, whether of the lowest or + highest vital importance, are often faithfully + transmitted—frequently even when one parent alone possesses some + new peculiarity. It deserves especial attention that characters appearing + at any age tend to reappear at a corresponding age. We may on the whole + conclude that in all cases inheritance is the rule, and non-inheritance + the anomaly. In some instances a character is not inherited, from the + conditions of life being directly opposed to its development; in many + instances, from the conditions incessantly inducing fresh variability, as + with grafted fruit-trees and highly cultivated flowers. In the remaining + cases the failure may be attributed to reversion, by which the child + resembles its grandparents or more remote progenitors, instead of its + parents.</p> + + <p>This principle of Reversion is the most wonderful of all the + attributes of Inheritance. It proves to us that the transmission of a + character and its development, which ordinarily go together and thus + escape discrimination, are distinct powers; and these powers in some + cases are even antagonistic, for each acts alternately in successive + generations. Reversion is not a rare event, depending on some unusual or + favourable combination of circumstances, but occurs so regularly with + crossed animals and plants, and so frequently with uncrossed breeds, that + it is evidently an essential part of the principle of inheritance. We + know that <!-- Page 373 --><span class="pagenum"><a + name="page373"></a>{373}</span>changed conditions have the power of + evoking long-lost characters, as in the case of some feral animals. The + act of crossing in itself possesses this power in a high degree. What can + be more wonderful than that characters, which have disappeared during + scores, or hundreds, or even thousands of generations, should suddenly + reappear perfectly developed, as in the case of pigeons and fowls when + purely bred, and especially when crossed; or as with the zebrine stripes + on dun-coloured horses, and other such cases? Many monstrosities come + under this same head, as when rudimentary organs are redeveloped, or when + an organ which we must believe was possessed by an early progenitor, but + of which not even a rudiment is left, suddenly reappears, as with the + fifth stamen in some Scrophulariaceæ. We have already seen that reversion + acts in bud-reproduction; and we know that it occasionally acts during + the growth of the same individual animal, especially, but not + exclusively, when of crossed parentage,—as in the rare cases + described of individual fowls, pigeons, cattle, and rabbits, which have + reverted as they advanced in years to the colours of one of their parents + or ancestors.</p> + + <p>We are led to believe, as formerly explained, that every character + which occasionally reappears is present in a latent form in each + generation, in nearly the same manner as in male and female animals + secondary characters of the opposite sex lie latent, ready to be evolved + when the reproductive organs are injured. This comparison of the + secondary sexual characters which are latent in both sexes, with other + latent characters, is the more appropriate from the case recorded of the + Hen, which assumed some of the masculine characters, not of her own race, + but of an early progenitor; she thus exhibited at the same time the + redevelopment of latent characters of both kinds and connected both + classes. In every living creature we may feel assured that a host of lost + characters lie ready to be evolved under proper conditions. How can we + make intelligible, and connect with other facts, this wonderful and + common capacity of reversion,—this power of calling back to life + long-lost characters? <!-- Page 374 --><span class="pagenum"><a + name="page374"></a>{374}</span></p> + +<p class="cenhead"><span class="sc">Part II.</span></p> + + <p>I have now enumerated the chief facts which every one would desire to + connect by some intelligible bond. This can be done, as it seems to me, + if we make the following assumptions; if the first and chief one be not + rejected, the others, from being supported by various physiological + considerations, will not appear very improbable. It is almost universally + admitted that cells, or the units of the body, propagate themselves by + self-division or proliferation, retaining the same nature, and ultimately + becoming converted into the various tissues and substances of the body. + But besides this means of increase I assume that cells, before their + conversion into completely passive or "formed material," throw off minute + granules or atoms, which circulate freely throughout the system, and when + supplied with proper nutriment multiply by self-division, subsequently + becoming developed into cells like those from which they were derived. + These granules for the sake of distinctness may be called cell-gemmules, + or, as the cellular theory is not fully established, simply gemmules. + They are supposed to be transmitted from the parents to the offspring, + and are generally developed in the generation which immediately succeeds, + but are often transmitted in a dormant state during many generations and + are then developed. Their development is supposed to depend on their + union with other partially developed cells or gemmules which precede them + in the regular course of growth. Why I use the term union, will be seen + when we discuss the direct action of pollen on the tissues of the + mother-plant. Gemmules are supposed to be thrown off by every cell or + unit, not only during the adult state, but during all the stages of + development. Lastly, I assume that the gemmules in their dormant state + have a mutual affinity for each other, leading to their aggregation + either into buds or into the sexual elements. Hence, speaking strictly, + it is not the reproductive elements, nor the buds, which generate new + organisms, but the cells themselves throughout the body. These + assumptions constitute the provisional hypothesis which I have called + Pangenesis. Nearly <!-- Page 375 --><span class="pagenum"><a + name="page375"></a>{375}</span>similar views have been propounded, as I + find, by other authors, more especially by Mr. Herbert Spencer;<a + name="NtA_902" href="#Nt_902"><sup>[902]</sup></a> but they are here + modified and amplified.</p> + +<p><!-- Page 376 --><span class="pagenum"><a name="page376"></a>{376}</span></p> + + <p>Before proceeding to show, firstly, how far these assumptions are in + themselves probable, and secondly, how far they connect and explain the + various groups of facts with which we are concerned, it may be useful to + give an illustration of the hypothesis. If one of the simplest Protozoa + be formed, as appears under the microscope, of a small mass of + homogeneous gelatinous matter, a minute atom thrown off from any part and + nourished under favourable circumstances would naturally reproduce the + whole; but if the upper and lower surfaces were to differ in texture from + the central portion, then all three parts would have to throw off atoms + or gemmules, which when aggregated by mutual affinity would form either + buds or the sexual elements. Precisely the same view may be extended to + one of the higher animals; although in this case many thousand gemmules + must be thrown off from the various parts of the body. Now, when the leg, + for instance, of a salamander is cut off, a slight crust forms over the + wound, and beneath this crust the uninjured cells or units of bone, + muscle, nerves, &c., are supposed to unite with the diffused gemmules + of those cells which in the perfect leg come next in order; and these as + they become slightly developed unite with others, and so on until a + papilla of soft cellular tissue, the "budding leg," is formed, and in + time a perfect leg.<a name="NtA_903" href="#Nt_903"><sup>[903]</sup></a> + Thus, that portion of the leg which had <!-- Page 377 --><span + class="pagenum"><a name="page377"></a>{377}</span>been cut off, neither + more nor less, would be reproduced. If the tail or leg of a young animal + had been cut off, a young tail or leg would have been reproduced, as + actually occurs with the amputated tail of the tadpole; for gemmules of + all the units which compose the tail are diffused throughout the body at + all ages. But during the adult state the gemmules of the larval tail + would remain dormant, for they would not meet with pre-existing cells in + a proper state of development with which to unite. If from changed + conditions or any other cause any part of the body should become + permanently modified, the gemmules, which are merely minute portions of + the contents of the cells forming the part, would naturally reproduce the + same modification. But gemmules previously derived from the same part + before it had undergone any change, would still be diffused throughout + the organisation, and would be transmitted from generation to generation, + so that under favourable circumstances they might be redeveloped, and + then the new modification would be for a time or for ever lost. The + aggregation of gemmules derived from every part of the body, through + their mutual affinity, would form buds, and their aggregation in some + special manner, apparently in small quantity, together probably with the + presence of gemmules of certain primordial cells, would constitute the + sexual elements. By means of these illustrations the hypothesis of + pangenesis has, I hope, been rendered intelligible.</p> + +<hr class="short" /> + + <p>Physiologists maintain, as we have seen, that each cell, though to a + large extent dependent on others, is likewise, to a certain extent, + independent or autonomous. I go one small step further, and assume that + each cell casts off a free gemmule, which is capable of reproducing a + similar cell. There is some analogy between this view and what we see in + compound animals and in the flower-buds on the same tree; for these are + distinct individuals capable of true or seminal reproduction, yet have + parts in common and are dependent on each other; thus <!-- Page 378 + --><span class="pagenum"><a name="page378"></a>{378}</span>the tree has + its bark and trunk, and certain corals, as the Virgularia, have not only + parts, but movements in common.</p> + + <p>The existence of free gemmules is a gratuitous assumption, yet can + hardly be considered as very improbable, seeing that cells have the power + of multiplication through the self-division of their contents. Gemmules + differ from true ovules or buds inasmuch as they are supposed to be + capable of multiplication in their undeveloped state. No one probably + will object to this capacity as improbable. The blastema within the egg + has been known to divide and give birth to two embryos; and Thuret<a + name="NtA_904" href="#Nt_904"><sup>[904]</sup></a> has seen the zoospore + of an alga divide itself, and both halves germinate. An atom of small-pox + matter, so minute as to be borne by the wind, must multiply itself many + thousand-fold in a person thus inoculated.<a name="NtA_905" + href="#Nt_905"><sup>[905]</sup></a> It has recently been ascertained<a + name="NtA_906" href="#Nt_906"><sup>[906]</sup></a> that a minute portion + of the mucous discharge from an animal affected with rinderpest, if + placed in the blood of a healthy ox, increases so fast that in a short + space of time "the whole mass of blood, weighing many pounds, is + infected, and every small particle of that blood contains enough poison + to give, within less than forty-eight hours, the disease to another + animal."</p> + + <p>The retention of free and undeveloped gemmules in the same body from + early youth to old age may appear improbable, but we should remember how + long seeds lie dormant in the earth and buds in the bark of a tree. Their + transmission from generation to generation may appear still more + improbable; but here again we should remember that many rudimentary and + useless organs are transmitted and have been transmitted during an + indefinite number of generations. We shall presently see how well the + long-continued transmission of undeveloped gemmules explains many + facts.</p> + + <p>As each unit, or group of similar units throughout the body, casts off + its gemmules, and as all are contained within the smallest egg or seed, + and within each spermatozoon or pollen-grain, their number and minuteness + must be something <!-- Page 379 --><span class="pagenum"><a + name="page379"></a>{379}</span>inconceivable. I shall hereafter recur to + this objection, which at first appears so formidable; but it may here be + remarked that a cod-fish has been found to produce 4,872,000 eggs, a + single Ascaris about 64,000,000 eggs, and a single Orchidaceous plant + probably as many million seeds.<a name="NtA_907" + href="#Nt_907"><sup>[907]</sup></a> In these several cases, the + spermatozoa and pollen-grains must exist in considerably larger numbers. + Now, when we have to deal with numbers such as these, which the human + intellect cannot grasp, there is no good reason for rejecting our present + hypothesis on account of the assumed existence of cell-gemmules a few + thousand times more numerous.</p> + + <p>The gemmules in each organism must be thoroughly diffused; nor does + this seem improbable considering their minuteness, and the steady + circulation of fluids throughout the body. So it must be with the + gemmules of plants, for with certain kinds even a minute fragment of a + leaf will reproduce the whole. But a difficulty here occurs; it would + appear that with plants, and probably with compound animals, such as + corals, the gemmules do not spread from bud to bud, but only through the + tissues developed from each separate bud. We are led to this conclusion + from the stock being rarely affected by the insertion of a bud or graft + from a distinct variety. This non-diffusion of the gemmules is still more + plainly shown in the case of ferns; for Mr. Bridgman<a name="NtA_908" + href="#Nt_908"><sup>[908]</sup></a> has proved that, when spores (which + it should be remembered are of the nature of buds) are taken from a + monstrous part of a frond, and others from an ordinary part, <!-- Page + 380 --><span class="pagenum"><a name="page380"></a>{380}</span>each + reproduces the form of the part whence derived. But this non-diffusion of + the gemmules from bud to bud may be only apparent, depending, as we shall + hereafter see, on the nature of the first-formed cells in the buds.</p> + + <p>The assumed elective affinity of each gemmule for that particular cell + which precedes it in the order of development is supported by many + analogies. In all ordinary cases of sexual reproduction the male and + female elements have a mutual affinity for each other: thus, it is + believed that about ten thousand species of Compositæ exist, and there + can be no doubt that if the pollen of all these species could be, + simultaneously or successively, placed on the stigma of any one species, + this one would elect with unerring certainty its own pollen. This + elective capacity is all the more wonderful, as it must have been + acquired since the many species of this great group of plants branched + off from a common progenitor. On any view of the nature of sexual + reproduction, the protoplasm contained within the ovules and within the + sperm-cells (or the "spermatic force" of the latter, if so vague a term + be preferred) must act on each other by some law of special affinity, + either during or subsequently to impregnation, so that corresponding + parts alone affect each other; thus, a calf produced from a short-horned + cow by a long-horned bull has its horns and not its horny hoofs affected + by the union of the two forms, and the offspring from two birds with + differently coloured tails have their tails and not their whole plumage + affected.</p> + + <p>The various tissues of the body plainly show, as many physiologists + have insisted,<a name="NtA_909" href="#Nt_909"><sup>[909]</sup></a> an + affinity for special organic substances, whether natural or foreign to + the body. We see this in the cells of the kidneys attracting urea from + the blood; in the worrara poison affecting the nerves; upas and digitalis + the muscles; the Lytta vesicatoria the kidneys; and in the poisonous + matter of many diseases, as small-pox, scarlet-fever, hooping-cough, + glanders, cancer, and hydrophobia, affecting certain definite parts of + the body or certain tissues or glands.</p> + + <p>The affinity of various parts of the body for each other during <!-- + Page 381 --><span class="pagenum"><a name="page381"></a>{381}</span>their + early development was shown in the last chapter, when discussing the + tendency to fusion in homologous parts. This affinity displays itself in + the normal fusion of organs which are separate at an early embryonic age, + and still more plainly in those marvellous cases of double monsters in + which each bone, muscle, vessel, and nerve in the one embryo, blends with + the corresponding part in the other. The affinity between homologous + organs may come into action with single parts, or with the entire + individual, as in the case of flowers or fruits which are symmetrically + blended together with all their parts doubled, but without any other + trace of fusion.</p> + + <p>It has also been assumed that the development of each gemmule depends + on its union with another cell or unit which has just commenced its + development, and which, from preceding it in order of growth, is of a + somewhat different nature. Nor is it a very improbable assumption that + the development of a gemmule is determined by its union with a cell + slightly different in nature, for abundant evidence was given in the + seventeenth chapter, showing that a slight degree of differentiation in + the male and female sexual elements favours in a marked manner their + union and subsequent development. But what determines the development of + the gemmules of the first-formed or primordial cell in the unimpregnated + ovule, is beyond conjecture.</p> + + <p>It must also be admitted that analogy fails to guide us towards any + determination on several other points: for instance, whether cells, + derived from the same parent-cell, may, in the regular course of growth, + become developed into different structures, from absorbing peculiar kinds + of nutriment, independently of their union with distinct gemmules. We + shall appreciate this difficulty if we call to mind, what complex yet + symmetrical growths the cells of plants yield when they are inoculated by + the poison of a gall-insect. With animals various polypoid excrescences + and tumours are now generally admitted<a name="NtA_910" + href="#Nt_910"><sup>[910]</sup></a> to be the direct product, through + proliferation, of normal cells which have become abnormal. In the regular + growth and repair of bones, the tissues undergo, as Virchow remarks,<a + name="NtA_911" href="#Nt_911"><sup>[911]</sup></a> a whole series of + permutations and substitutions. "The cartilage-cells may be <!-- Page 382 + --><span class="pagenum"><a name="page382"></a>{382}</span>converted by a + direct transformation into marrow-cells, and continue as such; or they + may first be converted into osseous and then into medullary tissue; or + lastly, they may first be converted into marrow and then into bone. So + variable are the permutations of these tissues, in themselves so nearly + allied, and yet in their external appearance so completely distinct." But + as these tissues thus change their nature at any age, without any obvious + change in their nutrition, we must suppose in accordance with our + hypothesis that gemmules derived from one kind of tissue combine with the + cells of another kind, and cause the successive modifications.</p> + + <p>It is useless to speculate at what period of development each organic + unit casts off its gemmules; for the whole subject of the development of + the various elemental tissues is as yet involved in much doubt. Some + physiologists, for instance, maintain that muscle or nerve-fibres are + developed from cells, which are afterwards nourished by their own proper + powers of absorption; whilst other physiologists deny their cellular + origin; and Beale maintains that such fibres are renovated exclusively by + the conversion of fresh germinal matter (that is the so-called nuclei) + into "formed material." However this may be, it appears probable that all + external agencies, such as changed nutrition, increased use or disuse, + &c., which induced any permanent modification in a structure, would + at the same time or previously act on the cells, nuclei, germinal or + formative matter, from which the structures in question were developed, + and consequently would act on the gemmules or cast-off atoms.</p> + + <p>There is another point on which it is useless to speculate, namely, + whether all gemmules are free and separate, or whether some are from the + first united into small aggregates. A feather, for instance, is a complex + structure, and, as each separate part is liable to inherited variations, + I conclude that each feather certainly generates a large number of + gemmules; but it is possible that these may be aggregated into a compound + gemmule. The same remark applies to the petals of a flower, which in some + cases are highly complex, with each ridge and hollow contrived for + special purposes, so that each part must have been separately modified, + and the modifications transmitted; consequently, separate gemmules, + according to our hypothesis, <!-- Page 383 --><span class="pagenum"><a + name="page383"></a>{383}</span>must have been thrown off from each cell + or part. But, as we sometimes see half an anther or a small portion of a + filament becoming petaliform, or parts or mere stripes of the calyx + assuming the colour and texture of the corolla, it is probable that with + petals the gemmules of each cell are not aggregated together into a + compound gemmule, but are freely and separately diffused.</p> + +<hr class="short" /> + + <p>Having now endeavoured to show that the several foregoing assumptions + are to a certain extent supported by analogous facts, and having + discussed some of the most doubtful points, we will consider how far the + hypothesis brings under a single point of view the various cases + enumerated in the First Part. All the forms of reproduction graduate into + each other and agree in their product; for it is impossible to + distinguish between organisms produced from buds, from self-division, or + from fertilised germs; such organisms are liable to variations of the + same nature and to reversion of character; and as we now see that all the + forms of reproduction depend on the aggregation of gemmules derived from + the whole body, we can understand this general agreement. It is + satisfactory to find that sexual and asexual generation, by both of which + widely different processes the same living creature is habitually + produced, are fundamentally the same. Parthenogenesis is no longer + wonderful; in fact, the wonder is that it should not oftener occur. We + see that the reproductive organs do not actually create the sexual + elements; they merely determine or permit the aggregation of the gemmules + in a special manner. These organs, together with their accessory parts, + have, however, high functions to perform; they give to both elements a + special affinity for each other, independently of the contents of the + male and female cells, as is shown in the case of plants by the mutual + reaction of the stigma and pollen-grains; they adapt one or both elements + for independent temporary existence, and for mutual union. The + contrivances for these purposes are sometimes wonderfully complex, as + with the spermatophores of the Cephalopoda. The male element sometimes + possesses attributes which, if observed in an independent animal, would + be put down to instinct guided by sense-organs, as when the <!-- Page 384 + --><span class="pagenum"><a name="page384"></a>{384}</span>spermatozoon + of an insect finds its way into the minute micropyle of the egg, or as + when the antherozoids of certain algæ swim by the aid of their ciliæ to + the female plant, and force themselves <span class="correction" + title="Originally printed on following line, after `must'.">into</span> a + minute orifice. In these latter cases, however, we must believe that the + male element has acquired its powers, on the same principle with the + larvæ of animals, namely by successive modifications developed at + corresponding periods of life: we can hardly avoid in these cases looking + at the male element as a sort of premature larva, which unites, or, like + one of the lower algæ, conjugates, with the female element. What + determines the aggregation of the gemmules within the sexual organs we do + not in the least know; nor do we know why buds are formed in certain + definite places, leading to the symmetrical growth of trees and corals, + nor why adventitious buds may be formed almost anywhere, even on a petal, + and frequently upon healed wounds.<a name="NtA_912" + href="#Nt_912"><sup>[912]</sup></a> As soon as the gemmules have + aggregated themselves, development apparently commences, but in the case + of buds is often afterwards suspended, and in the case of the sexual + elements soon ceases, unless the elements of the opposite sexes combine; + even after this has occurred, the fertilised germ, as with seeds buried + in the ground, may remain during a lengthened period in a dormant + state.</p> + + <p>The antagonism which has long been observed,<a name="NtA_913" + href="#Nt_913"><sup>[913]</sup></a> though exceptions occur,<a + name="NtA_914" href="#Nt_914"><sup>[914]</sup></a> between active growth + and the power of sexual reproduction—between the repair of injuries + and gemmation—and with plants, between rapid increase by buds, + rhizomes, &c., and the production of seed, is partly explained by the + gemmules not existing in sufficient numbers for both processes. <!-- Page + 385 --><span class="pagenum"><a name="page385"></a>{385}</span>But this + explanation hardly applies to those plants which naturally produce a + multitude of seeds, but which, through a comparatively small increase in + the number of the buds on their rhizomes or offsets, yield few or no + seed. As, however, we shall presently see that buds probably include + tissue which has already been to a certain extent developed or + differentiated, some additional organised matter will thus have been + expended.</p> + + <p>From one of the forms of Reproduction, namely, spontaneous + self-division, we are led by insensible steps to the repair of the + slightest injury; and the existence of gemmules, derived from every cell + or unit throughout the body and everywhere diffused, explains all such + cases,—even the wonderful fact that, when the limbs of the + salamander were cut off many times successively by Spallanzani and + Bonnet, they were exactly and completely reproduced. I have heard this + process compared with the recrystallisation which occurs when the angles + of a broken crystal are repaired; and the two processes have this much in + common, that in the one case the polarity of the molecules is the + efficient cause, and in the other the affinity of the gemmules for + particular nascent cells.</p> + + <p>Pangenesis does not throw much light on Hybridism, but agrees well + with most of the ascertained facts. We may conclude from the fact of a + single spermatozoon or pollen-grain being insufficient for impregnation, + that a certain number of gemmules derived from each cell or unit are + required for the development of each part. From the occurrence of + parthenogenesis, more especially in the case of the silk-moth, in which + the embryo is often partially formed, we may also infer that the female + element includes nearly sufficient gemmules of all kinds for independent + development, so that when united with the male element the gemmules must + be superabundant. Now, as a general rule, when two species or races are + crossed reciprocally, the offspring do not differ, and this shows that + both sexual elements agree in power, in accordance with the view that + they include the same gemmules. Hybrids and mongrels are generally + intermediate in character between the two parent-forms, yet occasionally + they closely resemble one parent in one part and the other parent in + another part, or even in their whole structure: nor is this difficult to + understand on <!-- Page 386 --><span class="pagenum"><a + name="page386"></a>{386}</span>the admission that the gemmules in the + fertilised germ are superabundant in number, and that those derived from + one parent have some advantage in number, affinity, or vigour over those + derived from the other parent. Crossed forms sometimes exhibit the colour + or other characters of either parent in stripes or blotches; and this may + occur in the first generation, or through reversion in succeeding bud and + seminal generations, as in the several instances given in the eleventh + chapter. In these cases we must follow Naudin,<a name="NtA_915" + href="#Nt_915"><sup>[915]</sup></a> and admit that the "essence" or + "element" of the two species, which terms I should translate into the + gemmules, have an affinity for their own kind, and thus separate + themselves into distinct stripes or blotches; and reasons were given, + when discussing in the fifteenth chapter the incompatibility of certain + characters to unite, for believing in such mutual affinity. When two + forms are crossed, one is not rarely found to be prepotent in the + transmission of character over the other; and this we can explain only by + again assuming that the one form has some advantage in the number, + vigour, or affinity of its gemmules, except in those cases, where certain + characters are present in the one form and latent in the other. For + instance, there is a latent tendency in all pigeons to become blue, and, + when a blue pigeon is crossed with one of any other colour, the blue tint + is generally prepotent. When we consider latent characters, the + explanation of this form of prepotency will be obvious.</p> + + <p>When one species is crossed with another it is notorious that they do + not yield the full or proper number of offspring; and we can only say on + this head that, as the development of each organism depends on such + nicely-balanced affinities between a host of gemmules and developing + cells or units, we need not feel at all surprised that the commixture of + gemmules derived from two distinct species should lead to a partial or + complete failure of development. With respect to the sterility of hybrids + produced from the union of two distinct species, it was shown in the + nineteenth chapter that this depends exclusively on the reproductive + organs being specially affected; but why these organs should be thus + affected we do not know, any more than <!-- Page 387 --><span + class="pagenum"><a name="page387"></a>{387}</span>why unnatural + conditions of life, though compatible with health, should cause + sterility; or why continued close interbreeding, or the illegitimate + unions of dimorphic and trimorphic plants, induce the same result. The + conclusion that the reproductive organs alone are affected, and not the + whole organisation, agrees perfectly with the unimpaired or even + increased capacity in hybrid plants for propagation by buds; for this + implies, according to our hypothesis, that the cells of the hybrids throw + off hybridised cell-gemmules, which become aggregated into buds, but fail + to become aggregated within the reproductive organs, so as to form the + sexual elements. In a similar manner many plants, when placed under + unnatural conditions, fail to produce seed, but can readily be propagated + by buds. We shall presently see that pangenesis agrees well with the + strong tendency to reversion exhibited by all crossed animals and + plants.</p> + + <p>It was shown in the discussion on graft-hybrids that there is some + reason to believe that portions of cellular tissue taken from distinct + plants become so intimately united, as afterwards occasionally to produce + crossed or hybridised buds. If this fact were fully established, it + would, by the aid of our hypothesis, connect gemmation and sexual + reproduction in the closest manner.</p> + + <p>Abundant evidence has been advanced proving that pollen taken from one + species or variety and applied to the stigma of another sometimes + directly affects the tissues of the mother-plant. It is probable that + this occurs with many plants during fertilisation, but can only be + detected when distinct forms are crossed. On any ordinary theory of + reproduction this is a most anomalous circumstance, for the pollen-grains + are manifestly adapted to act on the ovule, but in these cases they act + on the colour, texture, and form of the coats of the seeds, on the + ovarium itself, which is a modified leaf, and even on the calyx and upper + part of the flower-peduncle. In accordance with the hypothesis of + pangenesis pollen includes gemmules, derived from every part of the + organisation, which diffuse themselves and multiply by self-division; + hence it is not surprising that gemmules within the pollen, which are + derived from the parts near the reproductive organs, should sometimes be + able to affect the same parts, whilst still undergoing development, in + the mother-plant. <!-- Page 388 --><span class="pagenum"><a + name="page388"></a>{388}</span></p> + + <p>As, during all the stages of development, the tissues of plants + consist of cells, and as new cells are not known to be formed between, or + independently of, pre-existing cells, we must conclude that the gemmules + derived from the foreign pollen do not become developed merely in contact + with pre-existing cells, but actually penetrate the nascent cells of the + mother-plant. This process may be compared with the ordinary act of + fertilisation, during which the contents of the pollen-tubes penetrate + the closed embryonic sack within the ovule, and determine the development + of the embryo. According to this view, the cells of the mother-plant may + almost literally be said to be fertilised by the gemmules derived from + the foreign pollen. With all organisms, as we shall presently see, the + cells or organic units of the embryo during the successive stages of + development may in like manner be said to be fertilised by the gemmules + of the cells, which come next in the order of formation.</p> + + <p>Animals, when capable of sexual reproduction, are fully developed, and + it is scarcely possible that the male element should affect the tissues + of the mother in the same direct manner as with plants; nevertheless it + is certain that her ovaria are sometimes affected by a previous + impregnation, so that the ovules subsequently fertilised by a distinct + male are plainly influenced in character; and this, as in the case of + foreign pollen, is intelligible through the diffusion, retention, and + action of the gemmules included within the spermatozoa of the previous + male.</p> + + <p>Each organism reaches maturity through a longer or shorter course of + development. The changes may be small and insensibly slow, as when a + child grows into a man, or many, abrupt, and slight, as in the + metamorphoses of certain ephemerous insects, or again few and strongly + marked, as with most other insects. Each part may be moulded within a + previously existing and corresponding part, and in this case it will + appear, falsely as I believe, to be formed from the old part; or it may + be developed within a wholly distinct part of the body, as in the extreme + cases of metagenesis. An eye, for instance, may be developed at a spot + where no eye previously existed. We have also seen that allied organic + beings in the course of their metamorphoses sometimes attain nearly the + same structure after passing <!-- Page 389 --><span class="pagenum"><a + name="page389"></a>{389}</span>through widely different forms; or + conversely, after passing through nearly the same early forms, arrive at + a widely different termination. In these cases it is very difficult to + believe that the early cells or units possess the inherent power, + independently of any external agent, of producing new structures wholly + different in form, position, and function. But these cases become plain + on the hypothesis of pangenesis. The organic units, during each stage of + development, throw off gemmules, which, multiplying, are transmitted to + the offspring. In the offspring, as soon as any particular cell or unit + in the proper order of development becomes partially developed, it unites + with (or to speak metaphorically is fertilised by) the gemmule of the + next succeeding cell, and so onwards. Now, supposing that at any stage of + development, certain cells or aggregates of cells had been slightly + modified by the action of some disturbing cause, the cast-off gemmules or + atoms of the cell-contents could hardly fail to be similarly affected, + and consequently would reproduce the same modification. This process + might be repeated until the structure of the part at this particular + stage of development became greatly changed, but this would not + necessarily affect other parts whether previously or subsequently + developed. In this manner we can understand the remarkable independence + of structure in the successive metamorphoses, and especially in the + successive metageneses of many animals.</p> + + <p>The term growth ought strictly to be confined to mere increase of + size, and development to change of structure.<a name="NtA_916" + href="#Nt_916"><sup>[916]</sup></a> Now, a child is said to grow into a + man, and a foal into a horse, but, as in these cases there is much change + of structure, the process properly belongs to the order of development. + We have indirect evidence of this in many variations and diseases + supervening during so-called growth at a particular period, and being + inherited at a corresponding period. In the case, however, of diseases + which supervene during old age, subsequently to the ordinary period of + procreation, and which nevertheless are sometimes inherited, as occurs + with brain and heart complaints, we <!-- Page 390 --><span + class="pagenum"><a name="page390"></a>{390}</span>must suppose that the + organs were in fact affected at an earlier age and threw off at this + period affected gemmules; but that the affection became visible or + injurious only after the prolonged growth of the part in the strict sense + of the word. In all the changes of structure which regularly supervene + during old age, we see the effects of deteriorated growth, and not of + true development.</p> + + <p>In the so-called process of <i>alternate generation</i> many + individuals are generated asexually during very early or later stages of + development. These individuals may closely resemble the preceding larval + form, but generally are wonderfully dissimilar. To understand this + process we must suppose that at a certain stage of development the + gemmules are multiplied at an unusual rate, and become aggregated by + mutual affinity at many centres of attraction, or buds. These buds, it + may be remarked, must include gemmules not only of all the succeeding but + likewise of all the preceding stages of development; for when mature they + have the power of transmitting by sexual generation gemmules of all the + stages, however numerous these may be. It was shown in the First Part, at + least in regard to animals, that the new beings which are thus at any + period asexually generated do not retrograde in development—that + is, they do not pass through those earlier stages, through which the + fertilised germ of the same animal has to pass; and an explanation of + this fact was attempted as far as the final or teleological cause is + concerned. We can likewise understand the proximate cause, if we assume, + and the assumption is far from improbable, that buds, like chopped-up + fragments of a hydra, are formed of tissue which has already passed + through several of the earlier stages of development; for in this case + their component cells or units would not unite with the gemmules derived + from the earlier-formed cells, but only with those which came next in the + order of development. On the other hand, we must believe that, in the + sexual elements, or probably in the female alone, gemmules of certain + primordial cells are present; and these, as soon as their development + commences, unite in due succession with the gemmules of every part of the + body, from the first to the last period of life.</p> + + <p>The principle of the independent formation of each part, in <!-- Page + 391 --><span class="pagenum"><a name="page391"></a>{391}</span>so far as + its development depends on the union of the proper gemmules with certain + nascent cells, together with the superabundance of the gemmules derived + from both parents and self-multiplied, throws light on a widely different + group of facts, which on any ordinary view of development appears very + strange. I allude to organs which are abnormally multiplied or + transposed. Thus gold-fish often have supernumerary fins placed on + various parts of their bodies. We have seen that, when the tail of a + lizard is broken off, a double tail is sometimes reproduced, and when the + foot of the salamander is divided longitudinally, additional digits are + occasionally formed. When frogs, toads, &c., are born with their + limbs doubled, as sometimes occurs, the doubling, as Gervais remarks,<a + name="NtA_917" href="#Nt_917"><sup>[917]</sup></a> cannot be due to the + complete fusion of two embryos, with the exception of the limbs, for the + larvæ are limbless. The same argument is applicable<a name="NtA_918" + href="#Nt_918"><sup>[918]</sup></a> to certain insects produced with + multiple legs or antennæ, for these are metamorphosed from apodal or + antennæless larvæ. Alphonse Milne-Edwards<a name="NtA_919" + href="#Nt_919"><sup>[919]</sup></a> has described the curious case of a + crustacean in which one eye-peduncle supported, instead of a complete + eye, only an imperfect cornea, out of the centre of which a portion of an + antenna was developed. A case has been recorded<a name="NtA_920" + href="#Nt_920"><sup>[920]</sup></a> of a man who had during both + dentitions a double tooth in place of the left second incisor, and he + inherited this peculiarity from his paternal grandfather. Several cases + are known<a name="NtA_921" href="#Nt_921"><sup>[921]</sup></a> of + additional teeth having been developed in the palate, more especially + with horses, and in the orbit of the eye. Certain breeds of sheep bear a + whole crowd of horns on their foreheads. Hairs occasionally appear in + strange situations, as within the ears of the Siamese hairy family; and + hairs "quite natural in structure" have been observed "within the + substance of the brain."<a name="NtA_922" + href="#Nt_922"><sup>[922]</sup></a> As many as five spurs have been seen + on both legs in certain Game-fowls. In the Polish fowl the male is + ornamented with a topknot of hackles <!-- Page 392 --><span + class="pagenum"><a name="page392"></a>{392}</span>like those on his neck, + whilst the female has one of common feathers. In feather-footed pigeons + and fowls, feathers like those on the wing arise from the outer side of + the legs and toes. Even the elemental parts of the same feather may be + transposed; for in the Sebastopol goose, barbules are developed on the + divided filaments of the shaft.</p> + + <p>Analogous cases are of such frequent occurrence with plants that they + do not strike us with sufficient surprise. Supernumerary petals, stamens, + and pistils, are often produced. I have seen a leaflet low down in the + compound leaf of <i>Vicia sativa</i> converted into a tendril, and a + tendril possesses many peculiar properties, such as spontaneous movement + and irritability. The calyx sometimes assumes, either wholly or by + stripes, the colour and texture of the corolla. Stamens are so frequently + converted, more or less completely, into petals, that such cases are + passed over as not deserving notice; but as petals have special functions + to perform, namely, to protect the included organs, to attract insects, + and in not a few cases to guide their entrance by well-adapted + contrivances, we can hardly account for the conversion of stamens into + petals merely by unnatural or superfluous nourishment. Again, the edge of + a petal may occasionally be found including one of the highest products + of the plant, namely the pollen; for instance, I have seen in an Ophrys a + pollen-mass with its curious structure of little packets, united together + and to the caudicle by elastic threads, formed between the edges of an + upper petal. The segments of the calyx of the common pea have been + observed partially converted into carpels, including ovules, and with + their tips converted into stigmas. Numerous analogous facts could be + given.<a name="NtA_923" href="#Nt_923"><sup>[923]</sup></a></p> + + <p>I do not know how physiologists look at such facts as the foregoing. + According to the doctrine of pangenesis, the free and superabundant + gemmules of the transposed organs are developed in the wrong place, from + uniting with wrong cells or aggregates of cells during their nascent + state; and this would follow from a slight modification in the elective + affinity of such cells, or possibly of certain gemmules. Nor ought we to + feel much surprise at the affinities of cells and gemmules varying <!-- + Page 393 --><span class="pagenum"><a name="page393"></a>{393}</span>under + domestication, when we remember the many curious cases given, in the + seventeenth chapter, of cultivated plants which absolutely refuse to be + fertilised by their own pollen or by that of the same species, but are + abundantly fertile with pollen of a distinct species; for this implies + that their sexual elective affinities—and this is the term used by + Gärtner—have been modified. As the cells of adjoining or homologous + parts will have nearly the same nature, they will be liable to acquire by + variation each other's elective affinities; and we can thus to a certain + extent understand such cases as a crowd of horns on the heads in certain + sheep, of several spurs on the leg, and of hackles on the head of the + fowl, and with the pigeon the occurrence of wing-feathers on their legs + and of membrane between their toes; for the leg is the homologue of the + wing. As all the organs of plants are homologous and spring from a common + axis, it is natural that they should be eminently liable to + transposition. It ought to be observed that when any compound part, such + as an additional limb or an antenna, springs from a false position, it is + only necessary that the few first gemmules should be wrongly attached; + for these whilst developing would attract others in due succession, as in + the regrowth of an amputated limb. When parts which are homologous and + similar in structure, as the vertebræ in snakes or the stamens in + polyandrous flowers, &c., are repeated many times in the same + organism, closely allied gemmules must be extremely numerous, as well as + the points to which they ought to become united; and, in accordance with + the foregoing views, we can to a certain extent understand Isid. Geoffroy + St. Hilaire's law, namely, that parts, which are already multiple, are + extremely liable to vary in number.</p> + + <p>The same general principles apply to the fusion of homologous parts; + and with respect to mere cohesion there is probably always some degree of + fusion, at least near the surface. When two embryos during their early + development come into close contact, as both include corresponding + gemmules, which must be in all respects almost identical in nature, it is + not surprising that some derived from one embryo and some from the other + should unite at the point of contact with a single nascent cell or + aggregate of cells, and thus give rise to a single part or organ. For + instance, two embryos might thus come to have on their <!-- Page 394 + --><span class="pagenum"><a name="page394"></a>{394}</span>adjoining + sides a single symmetrical arm, which in one sense will have been formed + by the fusion of the bones, muscles, &c., belonging to the arms of + both embryos. In the case of the fish described by Lereboullet, in which + a double head was seen gradually to fuse into a single one, the same + process must have taken place, together with the absorption of all the + parts which had been already formed. These cases are exactly the reverse + of those in which a part is doubled either spontaneously or after an + injury; for in the case of doubling, the superabundant gemmules of the + same part are separately developed in union with adjoining points; whilst + in the case of fusion the gemmules derived from two homologous parts + become mingled and form a single part; or it may be that the gemmules + from one of two adjoining embryos alone become developed.</p> + +<hr class="short" /> + + <p>Variability often depends, as I have attempted to show, on the + reproductive organs being injuriously affected by changed conditions; and + in this case the gemmules derived from the various parts of the body are + probably aggregated in an irregular manner, some superfluous and others + deficient. Whether a superabundance of gemmules, together with fusion + during development, would lead to the increased size of any part cannot + be told; but we can see that their partial deficiency, without + necessarily leading to the entire abortion of the part, might cause + considerable modifications; for in the same manner as a plant, if its own + pollen be excluded, is easily hybridised, so, in the case of a cell, if + the properly succeeding gemmules were absent, it would probably combine + easily with other and allied gemmules. We see this in the case of + imperfect nails growing on the stumps of amputated fingers,<a + name="NtA_924" href="#Nt_924"><sup>[924]</sup></a> for the gemmules of + the nails have manifestly been developed at the nearest point.</p> + + <p>In variations caused by the direct action of changed conditions, + whether of a definite or indefinite nature, as with the fleeces of sheep + in hot countries, with maize grown in cold countries, with inherited + gout, &c., the tissues of the body, according to the doctrine of + pangenesis, are directly affected by the new conditions, and consequently + throw off modified gemmules, which are transmitted with their newly + acquired peculiarities to the offspring. On any ordinary view it is + unintelligible how changed <!-- Page 395 --><span class="pagenum"><a + name="page395"></a>{395}</span>conditions, whether acting on the embryo, + the young or adult animal, can cause inherited modifications. It is + equally or even more unintelligible on any ordinary view, how the effects + of the long-continued use or disuse of any part, or of changed habits of + body or mind, can be inherited. A more perplexing problem can hardly be + proposed; but on our view we have only to suppose that certain cells + become at last not only functionally but structurally modified; and that + these throw off similarly modified gemmules. This may occur at any period + of development, and the modification will be inherited at a corresponding + period; for the modified gemmules will unite in all ordinary cases with + the proper preceding cells, and they will consequently be developed at + the same period at which the modification first arose. With respect to + mental habits or instincts, we are so profoundly ignorant on the relation + between the brain and the power of thought that we do not know whether an + inveterate habit or trick induces any change in the nervous system; but + when any habit or other mental attribute, or insanity, is inherited, we + must believe that some actual modification is transmitted;<a + name="NtA_925" href="#Nt_925"><sup>[925]</sup></a> and this implies, + according to our hypothesis, that gemmules derived from modified + nerve-cells are transmitted to the offspring.</p> + + <p>It is generally, perhaps always, necessary that an organism should be + exposed during several generations to changed conditions or habits, in + order that any modification in the structure of the offspring should + ensue. This may be partly due to the changes not being at first marked + enough to catch the attention, but this explanation is insufficient; and + I can account for the fact, only by the assumption, which we shall see + under the head of reversion is strongly supported, that gemmules derived + from each cell before it had undergone the least modification are + transmitted in large numbers to successive generations, but that the + gemmules derived from the same cells after modification, naturally go on + increasing under the same favouring conditions, until at last they become + sufficiently numerous to overpower and supplant the old gemmules.</p> + + <p>Another difficulty may be here noticed; we have seen that <!-- Page + 396 --><span class="pagenum"><a name="page396"></a>{396}</span>there is + an important difference in the frequency, though not in the nature, of + the variations in plants propagated by sexual and asexual generation. As + far as variability depends on the imperfect action of the reproductive + organs under changed conditions, we can at once see why seedlings should + be far more variable than plants propagated by buds. We know that + extremely slight causes,—for instance, whether a tree has been + grafted or grows on its own stock, the position of the seeds within the + capsule, and of the flowers on the spike,—sometimes suffice to + determine the variation of a plant, when raised from seed. Now, it is + probable, as explained when discussing alternate generation, that a bud + is formed of a portion of already differentiated tissue; consequently an + organism thus formed does not pass through the earlier phases of + development, and cannot be so freely exposed, at the age when its + structure would be most readily modified, to the various causes inducing + variability; but it is very doubtful whether this is a sufficient + explanation of the difficulty.</p> + + <p>With respect to the tendency to reversion, there is a similar + difference between plants propagated from buds and seed. Many varieties, + whether originally produced from seed or buds, can be securely propagated + by buds, but generally or invariably revert by seed. So, also, hybridised + plants can be multiplied to any extent by buds, but are continually + liable to reversion by seed,—that is, to the loss of their hybrid + or intermediate character. I can offer no satisfactory explanation of + this fact. Here is a still more perplexing case: certain plants with + variegated leaves, phloxes with striped flowers, barberries with seedless + fruit, can all be securely propagated by the buds on cuttings; but the + buds developed from the roots of these cuttings almost invariably lose + their character and revert to their former condition.</p> + + <p>Finally, we can see on the hypothesis of pangenesis that variability + depends on at least two distinct groups of causes. Firstly, on the + deficiency, superabundance, fusion, and transposition of gemmules, and on + the redevelopment of those which have long been dormant. In these cases + the gemmules themselves have undergone no modification; but the mutations + in the above respects will amply account for much fluctuating <!-- Page + 397 --><span class="pagenum"><a + name="page397"></a>{397}</span>variability. Secondly, in the cases in + which the organisation has been modified by changed conditions, the + increased use or disuse of parts, or any other cause, the gemmules cast + off from the modified units of the body will be themselves modified, and, + when sufficiently multiplied, will be developed into new and changed + structures.</p> + +<hr class="short" /> + + <p>Turning now to Inheritance: if we suppose a homogeneous gelatinous + protozoon to vary and assume a reddish colour, a minute separated atom we + aid naturally, as it grew to full size, retain the same colour; and we + should have the simplest form of inheritance.<a name="NtA_926" + href="#Nt_926"><sup>[926]</sup></a> Precisely the same view may be + extended to the infinitely numerous and diversified units of which the + whole body in one of the higher animals is composed; and the separated + atoms are our gemmules. We have already sufficiently discussed the + inheritance of the direct effects of changed conditions, and of increased + use or disuse of parts, and, by implication, the important principle of + inheritance at corresponding ages. These groups of facts are to a large + extent intelligible on the hypothesis of pangenesis, and on no other + hypothesis as yet advanced.</p> + + <p>A few words must be added on the complete abortion or suppression of + organs. When a part becomes diminished by disuse prolonged during many + generations, the principle of economy of growth, as previously explained, + will tend to reduce it still further; but this will not account for the + complete or almost complete obliteration of, for instance, a minute + papilla of cellular tissue representing a pistil, or of a microscopically + minute nodule of bone representing a tooth. In certain cases of + suppression not yet completed, in which a rudiment occasionally reappears + through reversion, diffused gemmules derived from this part must, + according to our view, still exist; hence we must suppose that the cells, + in union with which the rudiment was formerly developed, in these cases + fail in their affinity for such gemmules. But in the cases of complete + and final abortion the gemmules themselves no doubt have perished; nor is + this <!-- Page 398 --><span class="pagenum"><a + name="page398"></a>{398}</span>in any way improbable, for, though a vast + number of active and long-dormant gemmules are diffused and nourished in + each living creature, yet there must be some limit to their number; and + it appears natural that gemmules derived from an enfeebled and useless + rudiment would be more liable to perish than those derived from other + parts which are still in full functional activity.</p> + + <p>With respect to mutilations, it is certain that a part may be removed + or injured during many generations, and no inherited result follow; and + this is an apparent objection to the hypothesis which will occur to every + one. But, in the first place, a being can hardly be intentionally + mutilated during its early stages of growth whilst in the womb or egg; + and such mutilations, when naturally caused, would appear like congenital + deficiencies, which are occasionally inherited. In the second place, + according to our hypothesis, gemmules multiply by self-division and are + transmitted from generation to generation; so that during a long period + they would be present and ready to reproduce a part which was repeatedly + amputated. Nevertheless it appears, from the facts given in the twelfth + chapter, that in some rare cases mutilations have been inherited, but in + most of these the mutilated surface became diseased. In this case it may + be conjectured that the gemmules of the lost part were gradually all + attracted by the partially diseased surface, and thus perished. Although + this would occur in the injured individual alone, and therefore in only + one parent, yet this might suffice for the inheritance of a mutilation, + on the same principle that a hornless animal of either sex, when crossed + with a perfect animal of the opposite sex, often transmits its + deficiency.</p> + + <p>The last subject that need here be discussed, namely Reversion, rests + on the principle that transmission and development, though generally + acting in conjunction, are distinct powers; and the transmission of + gemmules and their subsequent development show us how the existence of + these two distinct powers is possible. We plainly see this distinction in + the many cases in which a grandfather transmits to his grandson, through + his daughter, characters which she does not, or cannot, possess. Why the + development of certain characters, not necessarily in any way connected + with the reproductive organs, should be confined to one sex + alone—that is, why certain cells in one sex <!-- Page 399 --><span + class="pagenum"><a name="page399"></a>{399}</span>should unite with and + cause the development of certain gemmules—we do not in the least + know; but it is the common attribute of most organic beings in which the + sexes are separate.</p> + + <p>The distinction between transmission and development is likewise seen + in all ordinary cases of Reversion; but before discussing this subject it + may be advisable to say a few words on those characters which I have + called latent, and which would not be classed under Reversion in its + usual sense. Most, or perhaps all, the secondary characters, which + appertain to one sex, lie dormant in the other sex; that is, gemmules + capable of development into the secondary male sexual characters are + included within the female; and conversely female characters in the male. + Why in the female, when her ovaria become diseased or fail to act, + certain masculine gemmules become developed, we do not clearly know, any + more than why when a young bull is castrated his horns continue growing + until they almost resemble those of a cow; or why, when a stag is + castrated, the gemmules derived from the antlers of his progenitors quite + fail to be developed. But in many cases, with variable organic beings, + the mutual affinities of the cells and gemmules become modified, so that + parts are transposed or multiplied; and it would appear that a slight + change in the constitution of an animal, in connection with the state of + the reproductive organs, leads to changed affinities in the tissues of + various parts of the body. Thus, when male animals first arrive at + puberty, and subsequently during each recurrent season, certain cells or + parts acquire an affinity for certain gemmules, which become developed + into the secondary masculine characters; but if the reproductive organs + be destroyed, or even temporarily disturbed by changed conditions, these + affinities are not excited. Nevertheless, the male, before he arrives at + puberty, and during the season when the species does not breed, must + include the proper gemmules in a latent state. The curious case formerly + given of a Hen which assumed the masculine characters, not of her own + breed but of a remote progenitor, illustrates the connexion between + latent sexual characters and ordinary reversion. With those animals and + plants which habitually produce several forms, as with certain + butterflies described by Mr. Wallace, in which three female forms and + <!-- Page 400 --><span class="pagenum"><a + name="page400"></a>{400}</span>the male exist, or as with the trimorphic + species of Lythrum and Oxalis, gemmules capable of reproducing several + widely-different forms must be latent in each individual.</p> + + <p>The same principle of the latency of certain characters, combined with + the transposition of organs, may be applied to those singular cases of + butterflies and other insects, in which exactly one half or one quarter + of the body resembles the male, and the other half or three quarters the + female; and when this occurs the opposite sides of the body, separated + from each other by a distinct line, sometimes differ in the most + conspicuous manner. Again, these same principles apply to the cases given + in the thirteenth chapter, in which the right and left sides of the body + differ to an extraordinary degree, as in the spiral winding of certain + shells, and as in the genus Verruca among cirripedes; for in these cases + it is known that either side indifferently may undergo the same + remarkable change of development.</p> + + <p>Reversion, in the ordinary sense of the word, comes into action so + incessantly, that it evidently forms an essential part of the general law + of inheritance. It occurs with beings, however propagated, whether by + buds or seminal generation, and sometimes may even be observed in the + same individual as it advances in age. The tendency to reversion is often + induced by a change of conditions, and in the plainest manner by the act + of crossing. Crossed forms are generally at first nearly intermediate in + character between their two parents; but in the next generation the + offspring generally revert to one or both of their grandparents, and + occasionally to more remote ancestors. How can we account for these + facts? Each organic unit in a hybrid must throw off, according to the + doctrine of pangenesis, an abundance of hybridised gemmules, for crossed + plants can be readily and largely propagated by buds; but by the same + hypothesis there will likewise be present dormant gemmules derived from + both pure parent-forms; and as these latter retain their normal + condition, they would, it is probable, be enabled to multiply largely + during the lifetime of each hybrid. Consequently the sexual elements of a + hybrid will include both pure and hybridised gemmules; and when two + hybrids pair, the combination of pure gemmules derived from the one + hybrid with the pure gemmules of the same parts derived from the other + would <!-- Page 401 --><span class="pagenum"><a + name="page401"></a>{401}</span>necessarily lead to complete reversion of + character; and it is, perhaps, not too bold a supposition that unmodified + and undeteriorated gemmules of the same nature would be especially apt to + combine. Pure gemmules in combination with hybridised gemmules would lead + to partial reversion. And lastly, hybridised gemmules derived from both + parent-hybrids would simply reproduce the original hybrid form.<a + name="NtA_927" href="#Nt_927"><sup>[927]</sup></a> All these cases and + degrees of reversion incessantly occur.</p> + + <p>It was shown in the fifteenth chapter that certain characters are + antagonistic to each other or do not readily blend together; hence, when + two animals with antagonistic characters are crossed, it might well + happen that a sufficiency of gemmules in the male alone for the + reproduction of his peculiar characters, and in the female alone for the + reproduction of her peculiar characters, would not be present; and in + this case dormant gemmules derived from some remote progenitor might + easily gain the ascendency, and cause the reappearance of long-lost + characters. For instance, when black and white pigeons, or black and + white fowls, are crossed,—colours which do not readily + blend,—blue plumage in the one case, evidently derived from the + rock-pigeon, and red plumage in the other case, derived from the wild + jungle-cock, occasionally reappear. With uncrossed breeds the same result + would follow, under conditions which favoured the multiplication and + development of certain dormant gemmules, as when animals become feral and + revert to their pristine character. A certain number of gemmules being + requisite for the development of each character, as is known to be the + case from several spermatozoa or pollen-grains being necessary for + fertilisation, and time favouring their multiplication, will together + account for the curious cases, insisted on by Mr. Sedgwick, of certain + diseases regularly appearing in alternate generations. This likewise + holds good, more or less strictly, with other weakly inherited + modifications. Hence, as I have heard it remarked, certain diseases + appear actually to gain strength by the intermission of a generation. The + transmission of dormant gemmules during many successive generations is + hardly in itself more improbable, as <!-- Page 402 --><span + class="pagenum"><a name="page402"></a>{402}</span>previously remarked, + than the retention during many ages of rudimentary organs, or even only + of a tendency to the production of a rudiment; but there is no reason to + suppose that all dormant gemmules would be transmitted and propagated for + ever. Excessively minute and numerous as they are believed to be, an + infinite number derived, during a long course of modification and + descent, from each cell of each progenitor, could not be supported or + nourished by the organism. On the other hand, it does not seem improbable + that certain gemmules, under favourable conditions, should be retained + and go on multiplying for a longer period than others. Finally, on the + views here given, we certainly gain some clear insight into the wonderful + fact that the child may depart from the type of both its parents, and + resemble its grandparents, or ancestors removed by many generations.</p> + +<p class="cenhead"><i>Conclusion.</i></p> + + <p>The hypothesis of Pangenesis, as applied to the several great classes + of facts just discussed, no doubt is extremely complex; but so assuredly + are the facts. The assumptions, however, on which the hypothesis rests + cannot be considered as complex in any extreme degree—namely, that + all organic units, besides having the power, as is generally admitted, of + growing by self-division, throw off free and minute atoms of their + contents, that is gemmules. These multiply and aggregate themselves into + buds and the sexual elements; their development depends on their union + with other nascent cells or units; and they are capable of transmission + in a dormant state to successive generations.</p> + + <p>In a highly organised and complex animal, the gemmules thrown off from + each different cell or unit throughout the body must be inconceivably + numerous and minute. Each unit of each part, as it changes during + development, and we know that some insects undergo at least twenty + metamorphoses, must throw off its gemmules. All organic beings, moreover, + include many dormant gemmules derived from their grandparents and more + remote progenitors, but not from all their progenitors. These almost + infinitely numerous and minute gemmules must be included in each bud, + ovule, spermatozoon, and pollen-grain. Such an admission will be declared + impossible; but, as previously <!-- Page 403 --><span class="pagenum"><a + name="page403"></a>{403}</span>remarked, number and size are only + relative difficulties, and the eggs or seeds produced by certain animals + or plants are so numerous that they cannot be grasped by the + intellect.</p> + + <p>The organic particles with which the wind is tainted over miles of + space by certain offensive animals must be infinitely minute and + numerous; yet they strongly affect the olfactory nerves. An analogy more + appropriate is afforded by the contagious particles of certain diseases, + which are so minute that they float in the atmosphere and adhere to + smooth paper; yet we know how largely they increase within the human + body, and how powerfully they act. Independent organisms exist which are + barely visible under the highest powers of our recently-improved + microscopes, and which probably are fully as large as the cells or units + in one of the higher animals; yet these organisms no doubt reproduce + themselves by germs of extreme minuteness, relatively to their own minute + size. Hence the difficulty, which at first appears insurmountable, of + believing in the existence of gemmules so numerous and so small as they + must be according to our hypothesis, has really little weight.</p> + + <p>The cells or units of the body are generally admitted by physiologists + to be autonomous, like the buds on a tree, but in a less degree. I go one + step further and assume that they throw off reproductive gemmules. Thus + an animal does not, as a whole, generate its kind through the sole agency + of the reproductive system, but each separate cell generates its kind. It + has often been said by naturalists that each cell of a plant has the + actual or potential capacity of reproducing the whole plant; but it has + this power only in virtue of containing gemmules derived from every part. + If our hypothesis be provisionally accepted, we must look at all the + forms of asexual reproduction, whether occurring at maturity or as in the + case of alternate generation during youth, as fundamentally the same, and + dependent on the mutual aggregation and multiplication of the gemmules. + The regrowth of an amputated limb or the healing of a wound is the same + process partially carried out. Sexual generation differs in some + important respects, chiefly, as it would appear, in an insufficient + number of gemmules being aggregated within the separate sexual elements, + and probably in the presence of certain primordial cells. The development + of each being, including all the <!-- Page 404 --><span + class="pagenum"><a name="page404"></a>{404}</span>forms of metamorphosis + and metagenesis, as well as the so-called growth of the higher animals, + in which structure changes though not in a striking manner, depends on + the presence of gemmules thrown off at each period of life, and on their + development, at a corresponding period, in union with preceding cells. + Such cells may be said to be fertilised by the gemmules which come next + in the order of development. Thus the ordinary act of impregnation and + the development of each being are closely analogous processes. The child, + strictly speaking, does not grow into the man, but includes germs which + slowly and successively become developed and form the man. In the child, + as well as in the adult, each part generates the same part for the next + generation. Inheritance must be looked at as merely a form of growth, + like the self-division of a lowly-organised unicellular plant. Reversion + depends on the transmission from the forefather to his descendants of + dormant gemmules, which occasionally become developed under certain known + or unknown conditions. Each animal and plant may be compared to a bed of + mould full of seeds, most of which soon germinate, some lie for a period + dormant, whilst others perish. When we hear it said that a man carries in + his constitution the seeds of an inherited disease, there is much literal + truth in the expression. Finally, the power of propagation possessed by + each separate cell, using the term in its largest sense, determines the + reproduction, the variability, the development and renovation of each + living organism. No other attempt, as far as I am aware, has been made, + imperfect as this confessedly is, to connect under one point of view + these several grand classes of facts. We cannot fathom the marvellous + complexity of an organic being; but on the hypothesis here advanced this + complexity is much increased. Each living creature must be looked at as a + microcosm—a little universe, formed of a host of self-propagating + organisms, inconceivably minute and as numerous as the stars in + heaven.</p> + +<hr class="full" /> + +<p><!-- Page 405 --><span class="pagenum"><a name="page405"></a>{405}</span></p> + +<h3>CHAPTER XXVIII.</h3> + +<p class="cenhead">CONCLUDING REMARKS.</p> + +<blockquote class="b1n"> + + <p><span class="scac">DOMESTICATION</span>—<span + class="scac">NATURE AND CAUSES OF VARIABILITY</span>—<span + class="scac">SELECTION</span>—<span class="scac">DIVERGENCE AND + DISTINCTNESS OF CHARACTER</span>—<span class="scac">EXTINCTION OF + RACES</span>—<span class="scac">CIRCUMSTANCES FAVOURABLE TO + SELECTION BY MAN</span>—<span class="scac">ANTIQUITY OF CERTAIN + RACES</span>—<span class="scac">THE QUESTION WHETHER EACH + PARTICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED.</span></p> + +</blockquote> + + <p>As summaries have been added to nearly all the chapters, and as, in + the chapter on pangenesis, various subjects, such as the forms of + reproduction, inheritance, reversion, the causes and laws of variability, + &c., have been recently discussed, I will here only make a few + general remarks on the more important conclusions which may be deduced + from the multifarious details given throughout this work.</p> + + <p>Savages in all parts of the world easily succeed in taming wild + animals; and those inhabiting any country or island, when first invaded + by man, would probably have been still more easily tamed. Complete + subjugation generally depends on an animal being social in its habits, + and on receiving man as the chief of the herd or family. Domestication + implies almost complete fertility under new and changed conditions of + life, and this is far from being invariably the case. An animal would not + have been worth the labour of domestication, at least during early times, + unless of service to man. From these circumstances the number of + domesticated animals has never been large. With respect to plants, I have + shown in the ninth chapter how their varied uses were probably first + discovered, and the early steps in their cultivation. Man could not have + known, when he first domesticated an animal or plant, whether it would + flourish and multiply when transported to other countries, therefore he + could not have been thus influenced in his choice. We see that the close + adaptation of the reindeer and camel to extremely cold and hot countries + has not prevented their domestication. Still less <!-- Page 406 --><span + class="pagenum"><a name="page406"></a>{406}</span>could man have foreseen + whether his animals and plants would vary in succeeding generations and + thus give birth to new races; and the small capacity of variability in + the goose and ass has not prevented their domestication from the remotest + epoch.</p> + + <p>With extremely few exceptions, all animals and plants which have been + long domesticated, have varied greatly. It matters not under what + climate, or for what purpose, they are kept, whether as food for man or + beast, for draught or hunting, for clothing or mere pleasure,—under + all these circumstances domesticated animals and plants have varied to a + much greater extent than the forms which in a state of nature are ranked + as one species. Why certain animals and plants have varied more under + domestication than others we do not know, any more than why some are + rendered more sterile than others under changed conditions of life. But + we frequently judge of the amount of variation by the production of + numerous and diversified races, and we can clearly see why in many cases + this has not occurred, namely, because slight successive variations have + not been steadily accumulated; and such variations will never be + accumulated when an animal or plant is not closely observed, or much + valued, or kept in large numbers.</p> + + <p>The fluctuating, and, as far as we can judge, never-ending variability + of our domesticated productions,—the plasticity of their whole + organisation,—is one of the most important facts which we learn + from the numerous details given in the earlier chapters of this work. Yet + domesticated animals and plants can hardly have been exposed to greater + changes in their conditions than have many natural species during the + incessant geological, geographical, and climatal changes of the whole + world. The former will, however, commonly have been exposed to more + sudden changes and to less continuously uniform conditions. As man has + domesticated so many animals and plants belonging to widely different + classes, and as he certainly did not with prophetic instinct choose those + species which would vary most, we may infer that all natural species, if + subjected to analogous conditions, would, on an average, vary to the same + degree. Few men at the present day will maintain that animals and plants + were created with a tendency to vary, which long remained dormant, in + order that fanciers in after ages might <!-- Page 407 --><span + class="pagenum"><a name="page407"></a>{407}</span>rear, for instance, + curious breeds of the fowl, pigeon, or canary-bird.</p> + + <p>From several causes it is difficult to judge of the amount of + modification which our domestic productions have undergone. In some cases + the primitive parent-stock has become extinct, or cannot be recognised + with certainty owing to its supposed descendants having been so much + modified. In other cases two or more closely allied forms, after being + domesticated, have crossed; and then it is difficult to estimate how much + of the change ought to be attributed to variation. But the degree to + which our domestic breeds have been modified by the crossing of distinct + natural forms has probably been exaggerated by some authors. A few + individuals of one form would seldom permanently affect another form + existing in much greater numbers; for, without careful selection, the + stain of the foreign blood would soon be obliterated, and during early + and barbarous times, when our animals were first domesticated, such care + would seldom have been taken.</p> + + <p>There is good reason to believe that several of the breeds of the dog, + ox, pig, and of some other animals, are respectively descended from + distinct wild prototypes; nevertheless the belief in the multiple origin + of our domesticated animals has been extended by some few naturalists and + by many breeders to an unauthorised extent. Breeders refuse to look at + the whole subject under a single point of view; I have heard one, who + maintained that our fowls were the descendants of at least half-a-dozen + aboriginal species, protest that he was in no way concerned with the + origin of pigeons, ducks, rabbits, horses, or any other animal. They + overlook the improbability of many species having been domesticated at an + early and barbarous period. They do not consider the improbability of + species having existed in a state of nature which, if like our present + domestic breeds, would have been highly abnormal in comparison with all + their congeners. They maintain that certain species, which formerly + existed, have become extinct or unknown, although the world is now so + much better known. The assumption of so much recent extinction is no + difficulty in their eyes; for they do not judge of its probability by the + facility or difficulty of the extinction of other closely allied wild + forms. Lastly, <!-- Page 408 --><span class="pagenum"><a + name="page408"></a>{408}</span>they often ignore the whole subject of + geographical distribution as completely as if its laws were the result of + chance.</p> + + <p>Although from the reasons just assigned it is often difficult to judge + accurately of the amount of change which our domesticated productions + have undergone, yet this can be ascertained in the cases in which we know + that all the breeds are descended from a single species, as with the + pigeon, duck, rabbit, and almost certainly with the fowl; and by the aid + of analogy this is to a certain extent possible in the case of animals + descended from several wild stocks. It is impossible to read the details + given in the earlier chapters, and in many published works, or to visit + our various exhibitions, without being deeply impressed with the extreme + variability of our domesticated animals and cultivated plants. I have in + many instances purposely given details on new and strange peculiarities + which have arisen. No part of the organisation escapes the tendency to + vary. The variations generally affect parts of small vital or + physiological importance, but so it is with the differences which exist + between closely allied species. In these unimportant characters there is + often a greater difference between the breeds of the same species than + between the natural species of the same genus, as Isidore Geoffroy has + shown to be the case with size, and as is often the case with the colour, + texture, form, &c., of the hair, feathers, horns, and other dermal + appendages.</p> + + <p>It has often been asserted that important parts never vary under + domestication, but this is a complete error. Look at the skull of the pig + in any one of the highly improved breeds, with the occipital condyles and + other parts greatly modified; or look at that of the niata ox. Or again, + in the several breeds of the rabbit, observe the elongated skull, with + the differently shaped occipital foramen, atlas, and other cervical + vertebræ. The whole shape of the brain, together with the skull, has been + modified in Polish fowls; in other breeds of the fowl the number of the + vertebræ and the forms of the cervical vertebræ have been changed. In + certain pigeons the shape of the lower jaw, the relative length of the + tongue, the size of the nostrils and eyelids, the number and shape of the + ribs, the form and size of the œsophagus, have all varied. In + certain quadrupeds the length of the intestines has been much increased + or <!-- Page 409 --><span class="pagenum"><a + name="page409"></a>{409}</span>diminished. With plants we see wonderful + differences in the stones of various fruits. In the Cucurbitaceæ several + highly important characters have varied, such as the sessile position of + the stigmas on the ovarium, the position of the carpels within the + ovarium, and its projection out of the receptacle. But it would be + useless to run through the many facts given in the earlier chapters.</p> + + <p>It is notorious how greatly the mental disposition, tastes, habits, + consensual movements, loquacity or silence, and the tone of voice have + varied and been inherited with our domesticated animals. The dog offers + the most striking instance of changed mental attributes, and these + differences cannot be accounted for by descent from distinct wild types. + New mental characters have certainly often been acquired, and natural + ones lost, under domestication.</p> + + <p>New characters may appear and disappear at any stage of growth, and be + inherited at a corresponding period. We see this in the difference + between the eggs of various breeds of the fowl, and in the down on + chickens; and still more plainly in the differences between the + caterpillars and cocoons of various breeds of the silk-moth. These facts, + simple as they appear, throw light on the characters which distinguish + the larval and adult states of natural species, and on the whole great + subject of embryology. New characters are liable to become attached + exclusively to that sex in which they first appeared, or they may be + developed in a much higher degree in the one than the other sex; or + again, after having become attached to one sex, they may be partially + transferred to the opposite sex. These facts, and more especially the + circumstance that new characters seem to be particularly liable, from + some unknown cause, to become attached to the male sex, have an important + bearing on the acquirement by animals in a state of nature of secondary + sexual characters.</p> + + <p>It has sometimes been said that our domestic productions do not differ + in constitutional peculiarities, but this cannot be maintained. In our + improved cattle, pigs, &c., the period of maturity, including that of + the second dentition, has been much hastened. The period of gestation + varies much, but has been modified in a fixed manner in only one or two + cases. In <!-- Page 410 --><span class="pagenum"><a + name="page410"></a>{410}</span>our poultry and pigeons the acquirement of + down and of the first plumage by the young, and of the secondary sexual + characters by the males, differ. The number of moults through which the + larvæ of silk-moths pass, varies. The tendency to fatten, to yield much + milk, to produce many young or eggs at a birth or during life, differs in + different breeds. We find different degrees of adaptation to climate, and + different tendencies to certain diseases, to the attacks of parasites, + and to the action of certain vegetable poisons. With plants, adaptation + to certain soils, as with some kinds of plums, the power of resisting + frost, the period of flowering and fruiting, the duration of life, the + period of shedding the leaves and of retaining them throughout the + winter, the proportion and nature of certain chemical compounds in the + tissues or seeds, all vary.</p> + + <p>There is, however, one important constitutional difference between + domestic races and species; I refer to the sterility which almost + invariably follows, in a greater or less degree, when species are + crossed, and to the perfect fertility of the most distinct domestic + races, with the exception of a very few plants, when similarly crossed. + It certainly appears a remarkable fact that many closely allied species + which in appearance differ extremely little should yield when united only + a few, more or less sterile offspring, or none at all; whilst domestic + races which differ conspicuously from each other, are when united + remarkably fertile, and yield perfectly fertile offspring. But this fact + is not in reality so inexplicable as it at first appears. In the first + place, it was clearly shown in the nineteenth chapter that the sterility + of crossed species does not closely depend on differences in their + external structure or general constitution, but results exclusively from + differences in the reproductive system, analogous with those which cause + the lessened fertility of the illegitimate unions and illegitimate + offspring of dimorphic and trimorphic plants. In the second place, the + Pallasian doctrine, that species after having been long domesticated lose + their natural tendency to sterility when crossed, has been shown to be + highly probable; we can scarcely avoid this conclusion when we reflect on + the parentage and present fertility of the several breeds of the dog, of + Indian and European cattle, sheep, and pigs. Hence it would be + unreasonable to expect that races formed under domestication <!-- Page + 411 --><span class="pagenum"><a name="page411"></a>{411}</span>should + acquire sterility when crossed, whilst at the same time we admit that + domestication eliminates the normal sterility of crossed species. Why + with closely allied species their reproductive systems should almost + invariably have been modified in so peculiar a manner as to be mutually + incapable of acting on each other—though in unequal degrees in the + two sexes, as shown by the difference in fertility between reciprocal + crosses in the same species—we do not know, but may with much + probability infer the cause to be as follows. Most natural species have + been habituated to nearly uniform conditions of life for an incomparably + longer period of time than have domestic races; and we positively know + that changed conditions exert an especial and powerful influence on the + reproductive system. Hence this difference in habituation may well + account for the different action of the reproductive organs when domestic + races and when species are crossed. It is a nearly analogous fact, that + most domestic races may be suddenly transported from one climate to + another, or be placed under widely different conditions, and yet retain + their fertility unimpaired; whilst a multitude of species subjected to + lesser changes are rendered incapable of breeding.</p> + + <p>With the exception of fertility, domestic varieties resemble species + when crossed in transmitting their characters in the same unequal manner + to their offspring, in being subject to the prepotency of one form over + the other, and in their liability to reversion. By repeated crosses a + variety or a species may be made completely to absorb another. Varieties, + as we shall see when we treat of their antiquity, sometimes inherit their + new characters almost, or even quite, as firmly as species. With both, + the conditions leading to variability and the laws governing its nature + appear to be the same. Domestic varieties can be classed in groups under + groups, like species under genera, and these under families and orders; + and the classification may be either artificial,—that is, founded + on any arbitrary character,—or natural. With varieties a natural + classification is certainly founded, and with species is apparently + founded, on community of descent, together with the amount of + modification which the forms have undergone. The characters by which + domestic varieties differ from each other are more <!-- Page 412 --><span + class="pagenum"><a name="page412"></a>{412}</span>variable than those + distinguishing species, though hardly more so than with certain protean + species; but this greater degree of variability is not surprising, as + varieties have generally been exposed within recent times to fluctuating + conditions of life, are much more liable to have been crossed, and are + still in many cases undergoing, or have recently undergone, modification + by man's methodical or unconscious selection.</p> + + <p>Domestic varieties as a general rule certainly differ from each other + in less important parts of their organisation than do species; and when + important differences occur, they are seldom firmly fixed; but this fact + is intelligible if we consider man's method of selection. In the living + animal or plant he cannot observe internal modifications in the more + important organs; nor does he regard them as long as they are compatible + with health and life. What does the breeder care about any slight change + in the molar teeth of his pigs, or for an additional molar tooth in the + dog; or for any change in the intestinal canal or other internal organ? + The breeder cares for the flesh of his cattle being well marbled with + fat, and for an accumulation of fat within the abdomen of his sheep, and + this he has effected. What would the floriculturist care for any change + in the structure of the ovarium or of the ovules? As important internal + organs are certainly liable to numerous slight variations, and as these + would probably be inherited, for many strange monstrosities are + transmitted, man could undoubtedly effect a certain amount of change in + these organs. When he has produced any modification in an important part, + it has generally been unintentionally in correlation with some other + conspicuous part, as when he has given ridges and protuberances to the + skulls of fowls, by attending to the form of the comb, and in the case of + the Polish fowl to the plume of feathers on the head. By attending to the + external form of the pouter-pigeon, he has enormously increased the size + of the œsophagus, and has added to the number of the ribs, and + given them greater breadth. With the carrier-pigeon, by increasing, + through steady selection, the wattles on the upper mandible, he has + greatly modified the form of the lower mandible; and so in many other + cases. Natural species, on the other hand, have been modified exclusively + for their own good, to fit them for infinitely <!-- Page 413 --><span + class="pagenum"><a name="page413"></a>{413}</span>diversified conditions + of life, to avoid enemies of all kinds, and to struggle against a host of + competitors. Hence, under such complex conditions, it would often happen + that modifications of the most varied kinds, in important as well as in + unimportant parts, would be advantageous or even necessary; and they + would slowly but surely be acquired through the survival of the fittest. + Various indirect modifications would likewise arise through the law of + correlated variation.</p> + + <p>Domestic breeds often have an abnormal or semi-monstrous character, as + the Italian greyhound, bulldog, Blenheim spaniel, and bloodhound amongst + dogs,—some breeds of cattle and pigs, several breeds of the fowl, + and the chief breeds of the pigeon. The differences between such abnormal + breeds occur in parts which in closely-allied natural species differ but + slightly or not at all. This may be accounted for by man's often + selecting, especially at first, conspicuous and semi-monstrous deviations + of structure. We should, however, be cautious in deciding what deviations + ought to be called monstrous: there can hardly be a doubt that, if the + brush of horse-like hair on the breast of the turkey-cock had first + appeared on the domesticated bird, it would have been considered a + monstrosity; the great plume of feathers on the head of the Polish cock + has been thus designated, though plumes are common with many kinds of + birds; we might call the wattle or corrugated skin round the base of the + beak of the English carrier-pigeon a monstrosity, but we do not thus + speak of the globular fleshy excrescence at the base of the beak of the + male <i>Carpophaga oceanica</i>.</p> + + <p>Some authors have drawn a wide distinction between artificial and + natural breeds; although in extreme cases the distinction is plain, in + many other cases an arbitrary line has to be drawn. The difference + depends chiefly on the kind of selection which has been applied. + Artificial breeds are those which have been intentionally improved by + man; they frequently have an unnatural appearance, and are especially + liable to loss of excellence through reversion and continued variability. + The so-called natural breeds, on the other hand, are those which are now + found in semi-civilised countries, and which formerly inhabited separate + districts in nearly all the European kingdoms. They have been rarely + acted on by man's <!-- Page 414 --><span class="pagenum"><a + name="page414"></a>{414}</span>intentional selection; more frequently, it + is probable, by unconscious selection, and partly by natural selection, + for animals kept in semi-civilised countries have to provide largely for + their own wants. Such natural breeds will also, it may be presumed, have + been directly acted on to some extent by the differences, though slight, + in the surrounding physical conditions.</p> + + <p>It is a much more important distinction that some breeds have been + from their first origin modified in so slow and insensible a manner, that + if we could see their early progenitors we should hardly be able to say + when or how the breed first arose; whilst other breeds have originated + from a strongly-marked or semi-monstrous deviation of structure, which, + however, may subsequently have been augmented by selection. From what we + know of the history of the racehorse, greyhound, gamecock, &c., and + from their general appearance, we may feel nearly confident that they + were formed by a slow process of improvement: and with the + carrier-pigeon, as well as with some other pigeons, we know that this has + been the case. On the other hand, it is certain that the ancon and + mauchamp breeds of sheep, and almost certain that the niata cattle, + turnspit and pug-dogs, jumper and frizzled fowls, short-faced tumbler + pigeons, hook-billed ducks, &c., and with plants a multitude of + varieties, suddenly appeared in nearly the same state as we now see them. + The frequency of these cases is likely to lead to the false belief that + natural species have often originated in the same abrupt manner. But we + have no evidence of the appearance, or at least of the continued + procreation, under nature, of abrupt modifications of structure; and + various general reasons could be assigned against such a belief: for + instance, without separation a single monstrous variation would almost + certainly be soon obliterated by crossing.</p> + + <p>On the other hand, we have abundant evidence of the constant + occurrence under nature of slight individual differences of the most + diversified kinds; and thus we are led to conclude that species have + generally originated by the natural selection, not of abrupt + modifications, but of extremely slight differences. This process may be + strictly compared with the slow and gradual improvement of the racehorse, + greyhound, and gamecock. As every detail of structure in each species is + closely adapted to its general <!-- Page 415 --><span class="pagenum"><a + name="page415"></a>{415}</span>habits of life, it will rarely happen that + one part alone will be modified; but the co-adapted modifications, as + formerly shown, need not be absolutely simultaneous. Many variations, + however, are from the first connected by the law of correlation. Hence it + follows that even closely-allied species rarely or never differ from each + other by some one character alone; and this same remark applies to a + certain extent to domestic races; for these, if they differ much, + generally differ in many respects.</p> + + <p>Some naturalists boldly insist<a name="NtA_928" + href="#Nt_928"><sup>[928]</sup></a> that species are absolutely distinct + productions, never passing by intermediate links into each other; whilst + they maintain that domestic varieties can always be connected either with + each other or with their parent-forms. But if we could always find the + links between the several breeds of the dog, horse, cattle, sheep, pigs, + &c., the incessant doubts whether they are descended from one or + several species would not have arisen. The greyhound genus, if such a + term may be used, cannot be closely connected with any other breed, + unless, perhaps, we go back to the ancient Egyptian monuments. Our + English bulldog also forms a very distinct breed. In all these cases + crossed breeds must of course be excluded, for the most distinct natural + species can thus be connected. By what links can the Cochin fowl be + closely united with others? By searching for breeds still preserved in + distant lands, and by going back to historical records, tumbler-pigeons, + carriers, and barbs can be closely connected with the parent rock-pigeon; + but we cannot thus connect the turbit or the pouter. The degree of + distinctness between the various domestic breeds depends on the amount of + modification which they have undergone, and especially on the neglect and + final extinction of the linking, intermediate, and less valued forms.</p> + + <p>It has often been argued that no light is thrown, from the admitted + changes of domestic races, on the changes which natural species are + believed to undergo, as the former are said to be mere temporary + productions, always reverting, as soon as they become feral, to their + pristine form. This argument has been well combated by Mr. Wallace;<a + name="NtA_929" href="#Nt_929"><sup>[929]</sup></a> and full details were + given in the thirteenth chapter, showing that the tendency to reversion + in feral <!-- Page 416 --><span class="pagenum"><a + name="page416"></a>{416}</span>animals and plants has been greatly + exaggerated, though no doubt to a certain extent it exists. It would be + opposed to all the principles inculcated in this work, if domestic + animals, when exposed to new conditions and compelled to struggle for + their own wants against a host of foreign competitors, were not in the + course of time in some manner modified. It should also be remembered that + many characters lie latent in all organic beings ready to be evolved + under fitting conditions; and in breeds modified within recent times the + tendency to reversion is particularly strong. But the antiquity of + various breeds clearly proves that they remain nearly constant as long as + their conditions of life remain the same.</p> + + <p>It has been boldly maintained by some authors that the amount of + variation to which our domestic productions are liable is strictly + limited; but this is an assertion resting on little evidence. Whether or + not the amount in any particular direction is fixed, the tendency to + general variability seems unlimited. Cattle, sheep, and pigs have been + domesticated and have varied from the remotest period, as shown by the + researches of Rütimeyer and others, yet these animals have, within quite + recent times, been improved in an unparalleled degree; and this implies + continued variability of structure. Wheat, as we know from the remains + found in the Swiss lake-habitations, is one of the most anciently + cultivated plants, yet at the present day new and better varieties + occasionally arise. It may be that an ox will never be produced of larger + size or finer proportions than our present animals, or a race-horse + fleeter than Eclipse, or a gooseberry larger than the London variety; but + he would be a bold man who would assert that the extreme limit in these + respects has been finally attained. With flowers and fruit it has + repeatedly been asserted that perfection has been reached, but the + standard has soon been excelled. A breed of pigeons may never be produced + with a beak shorter than that of the present short-faced tumbler, or with + one longer than that of the English carrier, for these birds have weak + constitutions and are bad breeders; but the shortness and length of the + beak are the points which have been steadily improved during at least the + last 150 years; and some of the best judges deny that the goal has yet + been reached. We may, also, reasonably suspect, from what <!-- Page 417 + --><span class="pagenum"><a name="page417"></a>{417}</span>we see in + natural species of the variability of extremely modified parts, that any + structure, after remaining constant during a long series of generations, + would, under new and changed conditions of life, recommence its course of + variability, and might again be acted on by selection. Nevertheless, as + Mr. Wallace<a name="NtA_930" href="#Nt_930"><sup>[930]</sup></a> has + recently remarked with much force and truth, there must be both with + natural and domestic productions a limit to change in certain directions; + for instance, there must be a limit to the fleetness of any terrestrial + animal, as this will be determined by the friction to be overcome, the + weight to be carried, and the power of contraction in the muscular + fibres. The English racehorse may have reached this limit; but it already + surpasses in fleetness its own wild progenitor, and all other equine + species.</p> + + <p>It is not surprising, seeing the great difference between many + domestic breeds, that some few naturalists have concluded that all are + descended from distinct aboriginal stocks, more especially as the + principle of selection has been ignored, and the high antiquity of man, + as a breeder of animals, has only recently become known. Most + naturalists, however, freely admit that various extremely dissimilar + breeds are descended from a single stock, although they do not know much + about the art of breeding, cannot show the connecting links, nor say + where and when the breeds arose. Yet these same naturalists will declare, + with an air of philosophical caution, that they can never admit that one + natural species has given birth to another until they behold all the + transitional steps. But fanciers have used exactly the same language with + respect to domestic breeds; thus an author of an excellent treatise says + he will never allow that carrier and fantail pigeons are the descendants + of the wild rock-pigeon, until the transitions have "actually been + observed, and can be repeated whenever man chooses to set about the + task." No doubt it is difficult to realise that slight changes added up + during long centuries can produce such results; but he who wishes to + understand the origin of domestic breeds or natural species must overcome + this difficulty.</p> + + <p>The causes inducing and the laws governing variability have been so + lately discussed, that I need here only enumerate the leading points. As + domesticated organisms are much more <!-- Page 418 --><span + class="pagenum"><a name="page418"></a>{418}</span>liable to slight + deviations of structure and to monstrosities, than species living under + their natural conditions, and as widely-ranging species vary more than + those which inhabit restricted areas, we may infer that variability + mainly depends on changed conditions of life. We must not overlook the + effects of the unequal combination of the characters derived from both + parents, nor reversion to former progenitors. Changed conditions have an + especial tendency to render the reproductive organs more or less + impotent, as shown in the chapter devoted to this subject; and these + organs consequently often fail to transmit faithfully the parental + characters. Changed conditions also act directly and definitely on the + organisation, so that all or nearly all the individuals of the same + species thus exposed become modified in the same manner; but why this or + that part is especially affected we can seldom or never say. In most + cases, however, of the direct action of changed conditions, independently + of the indirect variability caused by the reproductive organs being + affected, indefinite modifications are the result; in nearly the same + manner as exposure to cold or the absorption of the same poison affects + different individuals in various ways. We have reason to suspect that an + habitual excess of highly nutritious food, or an excess relatively to the + wear and tear of the organisation from exercise, is a powerful exciting + cause of variability. When we see the symmetrical and complex outgrowths, + caused by a minute atom of the poison of a gall-insect, we may believe + that slight changes in the chemical nature of the sap or blood would lead + to extraordinary modifications of structure.</p> + + <p>The increased use of a muscle with its various attached parts, and the + increased activity of a gland or other organ, lead to their increased + development. Disuse has a contrary effect. With domesticated productions + organs sometimes become rudimentary through abortion; but we have no + reason to suppose that this has ever followed from mere disuse. With + natural species, on the contrary, many organs appear to have been + rendered rudimentary through disuse, aided by the principle of the + economy of growth, and by the hypothetical principle discussed in the + last chapter, namely, the final destruction of the germs or gemmules of + such useless parts. This difference may be partly <!-- Page 419 --><span + class="pagenum"><a name="page419"></a>{419}</span>accounted for by disuse + having acted on domestic forms for an insufficient length of time, and + partly from their exemption from any severe struggle for existence, + entailing rigid economy in the development of each part, to which all + species under nature are subjected. Nevertheless the law of compensation + or balancement apparently affects, to a certain extent, our domesticated + productions.</p> + + <p>We must not exaggerate the importance of the definite action of + changed conditions in modifying all the individuals of the same species + in the same manner, or of use and disuse. As every part of the + organisation is highly variable, and as variations are so easily + selected, both consciously and unconsciously, it is very difficult to + distinguish between the effects of the selection of indefinite + variations, and the direct action of the conditions of life. For + instance, it is possible that the feet of our water-dogs, and of the + American dogs which have to travel much over the snow, may have become + partially webbed from the stimulus of widely extending their toes; but it + is far more probable that the webbing, like the membrane between the toes + of certain pigeons, spontaneously appeared and was afterwards increased + by the best swimmers and the best snow-travellers being preserved during + many generations. A fancier who wished to decrease the size of his + bantams or tumbler-pigeons would never think of starving them, but would + select the smallest individuals which spontaneously appeared. Quadrupeds + are sometimes born destitute of hair, and hairless breeds have been + formed, but there is no reason to believe that this is caused by a hot + climate. Within the tropics heat often causes sheep to lose their + fleeces, and on the other hand wet and cold act as a direct stimulus to + the growth of hair; it is, however, possible that these changes may + merely be an exaggeration of the regular yearly change of coat; and who + will pretend to decide how far this yearly change, or the thick fur of + arctic animals, or as I may add their white colour, is due to the direct + action of a severe climate, and how far to the preservation of the best + protected individuals during a long succession of generations?</p> + + <p>Of all the laws governing variability, that of correlation is the most + important. In many cases of slight deviations of structure as well as of + grave monstrosities, we cannot even <!-- Page 420 --><span + class="pagenum"><a name="page420"></a>{420}</span>conjecture what is the + nature of the bond of connexion. But between homologous + parts—between the fore and hind limbs—between the hair, + hoofs, horns, and teeth—we can see that parts which are closely + similar during their early development, and which are exposed to similar + conditions, would be liable to be modified in the same manner. Homologous + parts, from having the same nature, are apt to blend together and, when + many exist, to vary in number.</p> + + <p>Although every variation is either directly or indirectly caused by + some change in the surrounding conditions, we must never forget that the + nature of the organisation which is acted on essentially governs the + result. Distinct organisms, when placed under similar conditions, vary in + different manners, whilst closely-allied organisms under dissimilar + conditions often vary in nearly the same manner. We see this in the same + modification frequently reappearing at long intervals of time in the same + variety, and likewise in the several striking cases given of analogous or + parallel varieties. Although some of these latter cases are simply due to + reversion, others cannot thus be accounted for.</p> + + <p>From the indirect action of changed conditions on the organisation, + through the impaired state of the reproductive organs—from the + direct action of such conditions (and this will cause the individuals of + the same species either to vary in the same manner, or differently in + accordance with slight differences in their constitution)—from the + effects of the increased or decreased use of parts,—and from + correlation,—the variability of our domesticated productions is + complicated in an extreme degree. The whole organisation becomes slightly + plastic. Although each modification must have its proper exciting cause, + and though each is subjected to law, yet we can so rarely trace the + precise relation between cause and effect, that we are tempted to speak + of variations as if they spontaneously arose. We may even call them + accidental, but this must be only in the sense in which we say that a + fragment of rock dropped from a height owes its shape to accident.</p> + +<hr class="short" /> + + <p>It may be worth while briefly to consider the results of the exposure + to unnatural conditions of a large number of animals of the same species, + allowed to cross freely, with no selection of any <!-- Page 421 --><span + class="pagenum"><a name="page421"></a>{421}</span>kind; and afterwards to + consider the results when selection is brought into play. Let us suppose + that 500 wild rock-pigeons were confined in their native land in an + aviary, and fed in the same manner as pigeons usually are; and that they + were not allowed to increase in number. As pigeons propagate so rapidly, + I suppose that a thousand or fifteen hundred birds would have to be + annually killed by mere chance. After several generations had been thus + reared, we may feel sure that some of the young birds would vary, and the + variations would tend to be inherited; for at the present day slight + deviations of structure often occur, but, as most breeds are already well + established, these modifications are rejected as blemishes. It would be + tedious even to enumerate the multitude of points which still go on + varying or have recently varied. Many variations would occur in + correlation, as the length of the wing and tail feathers—the number + of the primary wing-feathers, as well as the number and breadth of the + ribs, in correlation with the size and form of the body—the number + of the scutellæ, with the size of the feet—the length of the + tongue, with the length of the beak—the size of the nostrils and + eyelids and the form of lower jaw in correlation with the development of + wattle—the nakedness of the young with the future colour of the + plumage—the size of the feet and beak, and other such points. + Lastly, as our birds are supposed to be confined in an aviary, they would + use their wings and legs but little, and certain parts of the skeleton, + such as the sternum and scapulæ and the feet, would in consequence become + slightly reduced in size.</p> + + <p>As in our assumed case many birds have to be indiscriminately killed + every year, the chances are against any new variety surviving long enough + to breed. And as the variations which arise are of an extremely + diversified nature, the chances are very great against two birds pairing + which have varied in the same manner; nevertheless, a varying bird even + when not thus paired would occasionally transmit its character to its + young; and these would not only be exposed to the same conditions which + first caused the variation in question to appear, but would in addition + inherit from their one modified parent a tendency again to vary in the + same manner. So that, if the conditions decidedly tended to induce some + particular variation, all the birds might <!-- Page 422 --><span + class="pagenum"><a name="page422"></a>{422}</span>in the course of time + become similarly modified. But a far commoner result would be, that one + bird would vary in one way and another bird in another way; one would be + born with a little longer beak, and another with a shorter beak; one + would gain some black feathers, another some white or red feathers. And + as these birds would be continually intercrossing, the final result would + be a body of individuals differing from each other slightly in many ways, + yet far more than did the original rock-pigeons. But there would not be + the least tendency to the formation of distinct breeds.</p> + + <p>If two separate lots of pigeons were to be treated in the manner just + described, one in England and the other in a tropical country, the two + lots being supplied with different food, would they, after many + generations had passed, differ? When we reflect on the cases given in the + twenty-third chapter, and on such facts as the difference in former times + between the breeds of cattle, sheep, &c., in almost every district of + Europe, we are strongly inclined to admit that the two lots would be + differently modified through the influence of climate and food. But the + evidence on the definite action of changed conditions is in most cases + insufficient; and, with respect to pigeons, I have had the opportunity of + examining a large collection of domesticated birds, sent to me by Sir W. + Elliot from India, and they varied in a remarkably similar manner with + our European birds.</p> + + <p>If two distinct breeds were to be confined together in equal numbers, + there is reason to suspect that they would to a certain extent prefer + pairing with their own kind; but they would likewise intercross. From the + greater vigour and fertility of the crossed offspring, the whole body + would by this means become interblended sooner than would otherwise have + occurred. From certain breeds being prepotent over others, it does not + follow that the interblended progeny would be strictly intermediate in + character. I have, also, proved that the act of crossing in itself gives + a strong tendency to reversion, so that the crossed offspring would tend + to revert to the state of the aboriginal rock-pigeon. In the course of + time they would probably be not much more heterogeneous in character than + in our first case, when birds of the same breed were confined together. + <!-- Page 423 --><span class="pagenum"><a + name="page423"></a>{423}</span></p> + + <p>I have just said that the crossed offspring would gain in vigour and + fertility. From the facts given in the seventeenth chapter there can be + no doubt of this; and there can be little doubt, though the evidence on + this head is not so easily acquired, that long-continued close + interbreeding leads to evil results. With hermaphrodites of all kinds, if + the sexual elements of the same individual habitually acted on each + other, the closest possible interbreeding would be perpetual. Therefore + we should bear in mind that with all hermaphrodite animals, as far as I + can learn, their structure permits and frequently necessitates a cross + with a distinct individual. With hermaphrodite plants we incessantly meet + with elaborate and perfect contrivances for this same end. It is no + exaggeration to assert that, if the use of the talons and tusks of a + carnivorous animal, or the use of the viscid threads of a spider's web, + or of the plumes and hooks on a seed may be safely inferred from their + structure, we may with equal safety infer that many flowers are + constructed for the express purpose of ensuring a cross with a distinct + plant. From these various considerations, the conclusion arrived at in + the chapter just referred to—namely, that great good of some kind + is derived from the sexual concourse of distinct individuals—must + be admitted.</p> + + <p>To return to our illustration: we have hitherto assumed that the birds + were kept down to the same number by indiscriminate slaughter; but if the + least choice be permitted in their preservation and slaughter, the whole + result will be changed. Should the owner observe any slight variation in + one of his birds, and wish to obtain a breed thus characterised, he would + succeed in a surprisingly short time by carefully selecting and pairing + the young. As any part which has once varied generally goes on varying in + the same direction, it is easy, by continually preserving the most + strongly marked individuals, to increase the amount of difference up to a + high, predetermined standard of excellence. This is methodical + selection.</p> + + <p>If the owner of the aviary, without any thought of making a new breed, + simply admired, for instance, short-beaked more than long-beaked birds, + he would, when he had to reduce the number, generally kill the latter; + and there can be no doubt that he would thus in the course of time + sensibly modify his <!-- Page 424 --><span class="pagenum"><a + name="page424"></a>{424}</span>stock. It is improbable, if two men were + to keep pigeons and act in this manner, that they would prefer exactly + the same characters; they would, as we know, often prefer directly + opposite characters, and the two lots would ultimately come to differ. + This has actually occurred with strains or families of cattle, sheep, and + pigeons, which have been long kept and carefully attended to by different + breeders without any wish on their part to form new and distinct + sub-breeds. This unconscious kind of selection will more especially come + into action with animals which are highly serviceable to man; for every + one tries to get the best dog, horse, cow, or sheep, and these animals + will transmit more or less surely their good qualities to their + offspring. Hardly any one is so careless as to breed from his worst + animals. Even savages, when compelled from extreme want to kill some of + their animals, would destroy the worst and preserve the best. With + animals kept for use and not for mere amusement, different fashions + prevail in different districts, leading to the preservation, and + consequently to the transmission, of all sorts of trifling peculiarities + of character. The same process will have been pursued with our + fruit-trees and vegetables, for the best will always have been the most + largely cultivated, and will occasionally have yielded seedlings better + than their parents.</p> + + <p>The different strains, just alluded to, which have been raised by + different breeders without any wish for such a result, and the + unintentional modification of foreign breeds in their new homes, both + afford excellent evidence of the power of unconscious selection. This + form of selection has probably led to far more important results than + methodical selection, and is likewise more important under a theoretical + point of view from closely resembling natural selection. For during this + process the best or most valued individuals are not separated and + prevented crossing with others of the same breed, but are simply + preferred and preserved; but this inevitably leads during a long + succession of generations to their increase in number and to their + gradual improvement; so that finally they prevail to the exclusion of the + old parent-form.</p> + + <p>With our domesticated animals natural selection checks the production + of races with any injurious deviation of <!-- Page 425 --><span + class="pagenum"><a name="page425"></a>{425}</span>structure. In the case + of animals kept by savages and semi-civilised people, which have to + provide largely for their own wants under different circumstances, + natural selection will probably play a more important part. Hence such + animals often closely resemble natural species.</p> + + <p>As there is no limit to man's desire to possess animals and plants + more and more useful in any respect, and as the fancier always wishes, + from fashion running into extremes, to produce each character more and + more strongly pronounced, there is a constant tendency in every breed, + through the prolonged action of methodical and unconscious selection, to + become more and more different from its parent-stock; and when several + breeds have been produced and are valued for different qualities, to + differ more and more from each other. This leads to Divergence of + Character. As improved sub-varieties and races are slowly formed, the + older and less improved breeds are neglected and decrease in number. When + few individuals of any breed exist within the same locality, close + interbreeding, by lessening their vigour and fertility, aids in their + final extinction. Thus the intermediate links are lost, and breeds which + have already diverged gain Distinctness of Character.</p> + + <p>In the chapters on the Pigeon, it was proved by historical details and + by the existence of connecting sub-varieties in distant lands that + several breeds have steadily diverged in character, and that many old and + intermediate sub-breeds have become extinct. Other cases could be adduced + of the extinction of domestic breeds, as of the Irish wolf-dog, the old + English hound, and of two breeds in France, one of which was formerly + highly valued.<a name="NtA_931" href="#Nt_931"><sup>[931]</sup></a> Mr. + Pickering remarks<a name="NtA_932" href="#Nt_932"><sup>[932]</sup></a> + that "the sheep figured on the most ancient Egyptian monuments is unknown + at the present day; and at least one variety of the bullock, formerly + known in Egypt, has in like manner become extinct." So it has been with + some animals, and with several plants cultivated by the ancient + inhabitants of Europe during the neolithic period. In Peru, Von Tschudi<a + name="NtA_933" href="#Nt_933"><sup>[933]</sup></a> found in certain + tombs, apparently prior to the dynasty of the Incas, two kinds of maize + not now known in the country. With our flowers and culinary vegetables, + <!-- Page 426 --><span class="pagenum"><a + name="page426"></a>{426}</span>the production of new varieties and their + extinction has incessantly recurred. At the present time improved breeds + sometimes displace at an extraordinarily rapid rate older breeds; as has + recently occurred throughout England with pigs. The Long-horn cattle in + their native home were "suddenly swept away as if by some murderous + pestilence," by the introduction of Short-horns.<a name="NtA_934" + href="#Nt_934"><sup>[934]</sup></a></p> + + <p>What grand results have followed from the long-continued action of + methodical and unconscious selection, checked and regulated to a certain + extent by natural selection, is seen on every side of us. Compare the + many animals and plants which are displayed at our exhibitions with their + parent-forms when these are known, or consult old historical records with + respect to their former state. Almost all our domesticated animals have + given rise to numerous and distinct races, excepting those which cannot + be easily subjected to selection—such as cats, the cochineal + insect, and the hive-bee,—and excepting those animals which are not + much valued. In accordance with what we know of the process of selection, + the formation of our many races has been slow and gradual. The man who + first observed and preserved a pigeon with its œsophagus a little + enlarged, its beak a little longer, or its tail a little more expanded + than usual, never dreamed that he had made the first step in the creation + of the pouter, carrier, and fantail-pigeon. Man can create not only + anomalous breeds, but others with their whole structure admirably + co-ordinated for certain purposes, such as the race-horse and dray-horse, + or the greyhound. It is by no means necessary that each small change of + structure throughout the body, leading towards excellence, should + simultaneously arise and be selected. Although man seldom attends to + differences in organs which are important under a physiological point of + view, yet he has so profoundly modified some breeds, that assuredly, if + found wild, they would be ranked under distinct genera.</p> + + <p>The best proof of what selection has effected is perhaps afforded by + the fact that whatever part or quality in any animal, and more especially + in any plant, is most valued by man, that part or quality differs most in + the several races. This result is well seen by comparing the amount of + difference <!-- Page 427 --><span class="pagenum"><a + name="page427"></a>{427}</span>between the fruits produced by the + varieties of the same fruit-tree, between the flowers of the varieties in + our flower-garden, between the seeds, roots, or leaves of our culinary + and agricultural plants, in comparison with the other and not valued + parts of the same plants. Striking evidence of a different kind is + afforded by the fact ascertained by Oswald Heer,<a name="NtA_935" + href="#Nt_935"><sup>[935]</sup></a> namely, that the seeds of a large + number of plants,—wheat, barley, oats, peas, beans, lentils, + poppies,—cultivated for their seed by the ancient Lake-inhabitants + of Switzerland, were all smaller than the seeds of our existing + varieties. Rütimeyer has shown that the sheep and cattle which were kept + by the earlier Lake-inhabitants were likewise smaller than our present + breeds. In the middens of Denmark, the earliest dog of which the remains + have been found was the weakest; this was succeeded during the Bronze age + by a stronger kind, and this again during the Iron age by one still + stronger. The sheep of Denmark during the Bronze period had + extraordinarily slender limbs, and the horse was smaller than our present + animal.<a name="NtA_936" href="#Nt_936"><sup>[936]</sup></a> No doubt in + these cases the new and larger breeds were generally introduced from + foreign lands by the immigration of new hordes of men. But it is not + probable that each larger breed, which in the course of time supplanted a + previous and smaller breed, was the descendant of a distinct and larger + species; it is far more probable that the domestic races of our various + animals were gradually improved in different parts of the great + Europæo-Asiatic continent, and thence spread to other countries. This + fact of the gradual increase in size of our domestic animals is all the + more striking as certain wild or half-wild animals, such as red-deer, + aurochs, park-cattle, and boars,<a name="NtA_937" + href="#Nt_937"><sup>[937]</sup></a> have within nearly the same period + decreased in size.</p> + + <p>The conditions favourable to selection by man are,—the closest + attention being paid to every character,—long-continued + perseverance,—facility in matching or separating animals,—and + especially a large number being kept, so that the inferior individuals + may be freely rejected or destroyed, and the better ones preserved. When + many are kept there will also be a <!-- Page 428 --><span + class="pagenum"><a name="page428"></a>{428}</span>greater chance of the + occurrence of well-marked deviations of structure. Length of time is + all-important; for as each character, in order to become strongly + pronounced, has to be augmented by the selection of successive variations + of the same nature, this can only be effected during a long series of + generations. Length of time will, also, allow any new feature to become + fixed by the continued rejection of those individuals which revert or + vary, and the preservation of those which inherit the new character. + Hence, although some few animals have varied rapidly in certain respects + under new conditions of life, as dogs in India and sheep in the West + Indies, yet all the animals and plants which have produced strongly + marked races were domesticated at an extremely remote epoch, often before + the dawn of history. As a consequence of this, no record has been + preserved of the origin of our chief domestic breeds. Even at the present + day new strains or sub-breeds are formed so slowly that their first + appearance passes unnoticed. A man attends to some particular character, + or merely matches his animals with unusual care, and after a time a + slight difference is perceived by his neighbours;—the difference + goes on being augmented by unconscious and methodical selection, until at + last a new sub-breed is formed, receives a local name, and spreads; but, + by this time, its history is almost forgotten. When the new breed has + spread widely, it gives rise to new strains and sub-breeds, and the best + of these succeed and spread, supplanting other and older breeds; and so + always onwards in the march of improvement.</p> + + <p>When a well-marked breed has once been established, if not supplanted + by still improving sub-breeds, and if not exposed to greatly changed + conditions of life, inducing further variability or reversion to + long-lost characters, it may apparently last for an enormous period. We + may infer that this is the case from the high antiquity of certain races; + but some caution is necessary on this head, for the same variation may + appear independently after long intervals of time, or in distant places. + We may safely assume that this has occurred with the turnspit-dog which + is figured on the ancient Egyptian monuments, with the solid-hoofed + swine<a name="NtA_938" href="#Nt_938"><sup>[938]</sup></a> mentioned by + Aristotle, with five-toed fowls <!-- Page 429 --><span class="pagenum"><a + name="page429"></a>{429}</span>described by Columella, and certainly with + the nectarine. The dogs represented on the Egyptian monuments, about 2000 + <span class="scac">B.C.</span>, show us that some of the chief breeds + then existed, but it is extremely doubtful whether any are identically + the same with our present breeds. A great mastiff sculptured on an + Assyrian tomb, 640 <span class="scac">B.C.</span>, is said to be the same + with the dog still imported into the same region from Thibet. The true + greyhound existed during the Roman classical period. Coming down to a + later period, we have seen that, though most of the chief breeds of the + pigeon existed between two and three centuries ago, they have not all + retained to the present day exactly the same character; but this has + occurred in certain cases in which improvement was not desired, for + instance in the case of the Spot or the Indian ground-tumbler.</p> + + <p>De Candolle<a name="NtA_939" href="#Nt_939"><sup>[939]</sup></a> has + fully discussed the antiquity of various races of plants; he states that + the black-seeded poppy was known in the time of Homer, the white-seeded + sesamum by the ancient Egyptians, and almonds with sweet and bitter + kernels by the Hebrews; but it does not seem improbable that some of + these varieties may have been lost and reappeared. One variety of barley + and apparently one of wheat, both of which were cultivated at an + immensely remote period by the Lake-inhabitants of Switzerland, still + exist. It is said<a name="NtA_940" href="#Nt_940"><sup>[940]</sup></a> + that "specimens of a small variety of gourd which is still common in the + market of Lima were exhumed from an ancient cemetery in Peru." De + Candolle remarks that, in the books and drawings of the sixteenth + century, the principal races of the cabbage, turnip, and gourd can be + recognised; this might have been expected at so late a period, but + whether any of these plants are absolutely identical with our present + sub-varieties is not certain. It is, however, said that the Brussels + sprout, a variety which in some places is liable to degeneration, has + remained genuine for more than four centuries in the district where it is + believed to have originated.<a name="NtA_941" + href="#Nt_941"><sup>[941]</sup></a></p> + +<hr class="short" /> + + <p>In accordance with the views maintained by me in this work and + elsewhere, not only the various domestic races, but the <!-- Page 430 + --><span class="pagenum"><a name="page430"></a>{430}</span>most distinct + genera and orders within the same great class,—for instance, + whales, mice, birds, and fishes—are all the descendants of one + common progenitor, and we must admit that the whole vast amount of + difference between these forms of life has primarily arisen from simple + variability. To consider the subject under this point of view is enough + to strike one dumb with amazement. But our amazement ought to be lessened + when we reflect that beings, almost infinite in number, during an almost + infinite lapse of time, have often had their whole organisation rendered + in some degree plastic, and that each slight modification of structure + which was in any way beneficial under excessively complex conditions of + life, will have been preserved, whilst each which was in any way + injurious will have been rigorously destroyed. And the long-continued + accumulation of beneficial variations will infallibly lead to structures + as diversified, as beautifully adapted for various purposes, and as + excellently co-ordinated, as we see in the animals and plants all around + us. Hence I have spoken of selection as the paramount power, whether + applied by man to the formation of domestic breeds, or by nature to the + production of species. I may recur to the metaphor given in a former + chapter: if an architect were to rear a noble and commodious edifice, + without the use of cut stone, by selecting from the fragments at the base + of a precipice wedge-formed stones for his arches, elongated stones for + his lintels, and flat stones for his roof, we should admire his skill and + regard him as the paramount power. Now, the fragments of stone, though + indispensable to the architect, bear to the edifice built by him the same + relation which the fluctuating variations of each organic being bear to + the varied and admirable structures ultimately acquired by its modified + descendants.</p> + + <p>Some authors have declared that natural selection explains nothing, + unless the precise cause of each slight individual difference be made + clear. Now, if it were explained to a savage utterly ignorant of the art + of building, how the edifice had been raised stone upon stone, and why + wedge-formed fragments were used for the arches, flat stones for the + roof, &c.; and if the use of each part and of the whole building were + pointed out, it would be unreasonable if he declared that nothing had + been <!-- Page 431 --><span class="pagenum"><a + name="page431"></a>{431}</span>made clear to him, because the precise + cause of the shape of each fragment could not be given. But this is a + nearly parallel case with the objection that selection explains nothing, + because we know not the cause of each individual difference in the + structure of each being.</p> + + <p>The shape of the fragments of stone at the base of our precipice may + be called accidental, but this is not strictly correct; for the shape of + each depends on a long sequence of events, all obeying natural laws; on + the nature of the rock, on the lines of deposition or cleavage, on the + form of the mountain which depends on its upheaval and subsequent + denudation, and lastly on the storm or earthquake which threw down the + fragments. But in regard to the use to which the fragments may be put, + their shape may be strictly said to be accidental. And here we are led to + face a great difficulty, in alluding to which I am aware that I am + travelling beyond my proper province. An omniscient Creator must have + foreseen every consequence which results from the laws imposed by Him. + But can it be reasonably maintained that the Creator intentionally + ordered, if we use the words in any ordinary sense, that certain + fragments of rock should assume certain shapes so that the builder might + erect his edifice? If the various laws which have determined the shape of + each fragment were not predetermined for the builder's sake, can it with + any greater probability be maintained that He specially ordained for the + sake of the breeder each of the innumerable variations in our domestic + animals and plants;—many of these variations being of no service to + man, and not beneficial, far more often injurious, to the creatures + themselves? Did He ordain that the crop and tail-feathers of the pigeon + should vary in order that the fancier might make his grotesque pouter and + fantail breeds? Did He cause the frame and mental qualities of the dog to + vary in order that a breed might be formed of indomitable ferocity, with + jaws fitted to pin down the bull for man's brutal sport? But if we give + up the principle in one case,—if we do not admit that the + variations of the primeval dog were intentionally guided in order that + the greyhound, for instance, that perfect image of symmetry and vigour, + might be formed,—no shadow of reason can be assigned for the belief + that variations, alike in nature and the result <!-- Page 432 --><span + class="pagenum"><a name="page432"></a>{432}</span>of the same general + laws, which have been the groundwork through natural selection of the + formation of the most perfectly adapted animals in the world, man + included, were intentionally and specially guided. However much we may + wish it, we can hardly follow Professor Asa Gray in his belief "that + variation has been led along certain beneficial lines," like a stream + "along definite and useful lines of irrigation." If we assume that each + particular variation was from the beginning of all time preordained, the + plasticity of organisation, which leads to many injurious deviations of + structure, as well as that redundant power of reproduction which + inevitably leads to a struggle for existence, and, as a consequence, to + the natural selection or survival of the fittest, must appear to us + superfluous laws of nature. On the other hand, an omnipotent and + omniscient Creator ordains everything and foresees everything. Thus we + are brought face to face with a difficulty as insoluble as is that of + free will and predestination.</p> + +<hr class="full" /> + +<p><!-- Page 433 --><span class="pagenum"><a name="page433"></a>{433}</span></p> + + <div class="poem"> + <div class="stanza"> + <p class="i16">INDEX.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Abbas</span> Pacha, a fancier of fantailed pigeons, i. 206.</p> + <p><span class="sc">Abbey</span>, Mr., on grafting, ii. <a href="#page147">147</a>;</p> + <p class="i2">on mignonette, ii. <a href="#page237">237</a>.</p> + <p><span class="sc">Abbott</span>, Mr. Keith, on the Persian tumbler pigeon, i. 150.</p> + <p><span class="sc">Abbreviation</span> of the facial bones, i. 73.</p> + <p><span class="sc">Abortion</span> of organs, ii. <a href="#page315">315</a>-<a href="#page318">318</a>, <a href="#page397">397</a>.</p> + <p><span class="sc">Absorption</span> of minority in crossed races, ii. <a href="#page87">87</a>-<a href="#page89">89</a>, <a href="#page174">174</a>.</p> + <p><span class="sc">Acclimatisation</span>, ii. <a href="#page305">305</a>-<a href="#page315">315</a>;</p> + <p class="i2">of maize, i. 322.</p> + <p><span class="sc">Acerbi</span>, on the fertility of domestic animals in Lapland, ii. <a href="#page112">112</a>.</p> + <p><i>Achatinella</i>, ii. <a href="#page53">53</a>.</p> + <p><i>Achillea millefolium</i>, bud variation in, i. 408.</p> + <p><i>Aconitum napellus</i>, roots of, innocuous in cold climates, ii. <a href="#page274">274</a>.</p> + <p><i>Acorus calamus</i>, sterility of, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Acosta</span>, on fowls in South America at its discovery, i. 237.</p> + <p><i>Acropera</i>, number of seeds in, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Adam</span>, Mr., origin of <i>Cytisus Adami</i>, i. 390.</p> + <p><span class="sc">Adam</span>, W., on consanguineous marriages, ii. <a href="#page123">123</a>.</p> + <p><span class="sc">Adams</span>, Mr., on hereditary diseases, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Advancement</span> in scale of organisation, i. 8.</p> + <p><i>Ægilops triticoides</i>, observations of Fabre and Godron on, i. 313;</p> + <p class="i2">increasing fertility of hybrids of, with wheat, ii. <a href="#page110">110</a>.</p> + <p><i>Æsculus flava</i> and <i>rubicunda</i>, i. 392.</p> + <p><i>Æsculus pavia</i>, tendency of, to become double, ii. <a href="#page168">168</a>.</p> + <p><i>Æthusa cynapium</i>, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Affinity</span>, sexual elective, ii. <a href="#page180">180</a>.</p> + <p><span class="sc">Africa</span>, white bull from, i. 91;</p> + <p class="i2">feral cattle in, i. 85;</p> + <p class="i2">food-plants of savages of, i. 307-309;</p> + <p class="i2">South, diversity of breeds of cattle in, i. 80;</p> + <p class="i2">West, change in fleece of sheep in, i. 98.</p> + <p><i>Agave vivipara</i>, seeding of, in poor soil, ii. <a href="#page169">169</a>.</p> + <p><span class="sc">Age</span>, changes in trees, dependent on, i. 387.</p> + <p><span class="sc">Agouti</span>, fertility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Agriculture</span>, antiquity of, ii. <a href="#page243">243</a>.</p> + <p><i>Agrostis</i>, seeds of, used as food, i. 309.</p> + <p><span class="sc">Aguara</span>, i. 26.</p> + <p><span class="sc">Ainsworth</span>, Mr., on the change in the hair of animals at Angora, ii. <a href="#page278">278</a>.</p> + <p><span class="sc">Akbar</span> Khan, his fondness for pigeons, i. 205; ii. <a href="#page204">204</a>.</p> + <p><i>Alauda arvensis</i>, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Albin</span>, on "Golden Hamburgh" fowls, i. 247;</p> + <p class="i2">figure of the hook-billed duck, i. 277.</p> + <p><span class="sc">Albinism</span>, i. 111, ii. <a href="#page17">17</a>.</p> + <p><span class="sc">Albino</span>, negro, attacked by insects, ii. <a href="#page229">229</a>.</p> + <p><span class="sc">Albinoes</span>, heredity of, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">Albinus</span>, thickness of the epidermis on the palms of the hands in man, ii. <a href="#page297">297</a>.</p> + <p><span class="sc">Alco</span>, i. 31, ii. <a href="#page102">102</a>.</p> + <p><span class="sc">Aldrovandi</span>, on rabbits, i. 104;</p> + <p class="i2">description of the nun pigeon, i. 156;</p> + <p class="i2">on the fondness of the Dutch for pigeons in the seventeenth century, i. 205;</p> + <p class="i2">notice of several varieties of pigeons, i. 207-210;</p> + <p class="i2">on the breeds of fowls, i. 247;</p> + <p class="i2">on the origin of the domestic duck, i. 278.</p> + <p><span class="sc">Alefield</span>, Dr., on the varieties of peas and their specific unity, i. 326;</p> + <p class="i2">on the varieties of beans, i. 330.</p> + <p><span class="sc">Alexander</span> the Great, his selection of Indian cattle, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Algæ</span>, retrogressive metamorphosis in, ii. <a href="#page361">361</a>;</p> + <p class="i2">division of zoospores of, ii. <a href="#page378">378</a>.</p> + <p><span class="sc">Allen</span>, W., on feral fowls, i. 237; ii. <a href="#page33">33</a>.</p> + <p><span class="sc">Allman</span>, Professor, on a monstrous <i>Saxifraga geum</i>, ii. <a href="#page166">166</a>;</p> + <p class="i2">on the development of the Hydroida, ii. <a href="#page368">368</a>.</p> + <p><span class="sc">Almond</span>, i. 337;</p> + <p class="i2">antiquity of, ii. <a href="#page429">429</a>;</p> + <p class="i2">bitter, not eaten by mice, ii. <a href="#page232">232</a>.</p> + <p><i>Alnus glutinosa</i> and <i>incana</i>, hybrids of, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Alpaca</span>, selection of, ii. <a href="#page208">208</a>.</p> + <p><i>Althæa rosea</i>, i. 378, ii. <a href="#page107">107</a>.</p> + <p><i>Amaryllis</i>, ii. <a href="#page139">139</a>.</p> + <p><i>Amaryllis vittata</i>, effect of foreign pollen on, i. 400.</p> + <p><span class="sc">Amaurosis</span>, hereditary, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">America</span>, limits within which no useful plants have been furnished by, i. 310;</p> + <p class="i2">colours of feral horses in, i. 60-61;</p> + <p class="i2">North, native cultivated plants of, i. 312;</p> + <p class="i2">skin of feral pig from, i. 77;</p> + <p class="i2">South, variations in cattle of, i. 88, 92.</p> + <p><i>Amygdalus persica</i>, i. 336-344, 374.</p> +<!-- Page 434 --><span class="pagenum"><a name="page434"></a>{434}</span> + <p><span class="sc">Ammon</span>, on the persistency of colour in horses, ii. <a href="#page21">21</a>.</p> + <p><i>Anagallis arvensis</i>, ii. <a href="#page190">190</a>.</p> + <p><span class="sc">Analogous</span> variation, i. 409, ii. <a href="#page348">348</a>-<a href="#page352">352</a>;</p> + <p class="i2">in horses, i. 55;</p> + <p class="i2">in the horse and ass, i. 64;</p> + <p class="i2">in fowls, i. 243-246.</p> + <p><i>Anas boschas</i>, i. 277, ii. <a href="#page40">40</a>;</p> + <p class="i2">skull of, figured, i. 282.</p> + <p><i>Anas moschata</i>, ii. <a href="#page40">40</a>.</p> + <p>"<span class="sc">Ancon</span>" sheep of Massachusetts, i. 100, ii. <a href="#page103">103</a>.</p> + <p><span class="sc">Andalusian</span> fowls, i. 227.</p> + <p><span class="sc">Andalusian</span> rabbits, i. 105.</p> + <p><span class="sc">Anderson, J.</span>, on the origin of British sheep, i. 94;</p> + <p class="i2">on the selection of qualities in cattle, ii. <a href="#page196">196</a>;</p> + <p class="i2">on a one-eared breed of rabbits, i. 108;</p> + <p class="i2">on the inheritance of characters from a one-eared rabbit and three-legged bitch, ii. <a href="#page12">12</a>;</p> + <p class="i2">on the persistency of varieties of peas, i. 329;</p> + <p class="i2">on the production of early peas by selection, ii. <a href="#page201">201</a>;</p> + <p class="i2">on the varieties of the potato, i. 330-331;</p> + <p class="i2">on crossing varieties of the melon, i. 399;</p> + <p class="i2">on reversion in the barberry, i. 384.</p> + <p><span class="sc">Anderson</span>, Mr., on the reproduction of the weeping ash by seed, ii. <a href="#page19">19</a>;</p> + <p class="i2">on the cultivation of the tree pæony in China, ii. <a href="#page205">205</a>.</p> + <p><span class="sc">Andersson</span>, Mr., on the Damara, Bechuana, and Namaqua cattle, i. 88;</p> + <p class="i2">on the cows of the Damaras, ii. <a href="#page300">300</a>;</p> + <p class="i2">selection practised by the Damaras and Namaquas, ii. <a href="#page207">207</a>;</p> + <p class="i2">on the use of grass-seeds and the roots of reeds as food in South Africa, i. 309.</p> + <p><i>Anemone coronaria</i>, doubled by selection, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Angina</span> pectoris, hereditary, occurring at a certain age, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Anglesea</span>, cattle of, i. 80.</p> + <p><span class="sc">Angola</span> sheep, i. 95.</p> + <p><span class="sc">Angora</span>, change in hair of animals at, ii. <a href="#page278">278</a>;</p> + <p class="i2">cats of, i. 45, 47;</p> + <p class="i2">rabbits of, i. 106, 120.</p> + <p><span class="sc">Animals</span>, domestication of, facilitated by fearlessness of man, i. 20;</p> + <p class="i2">refusal of wild, to breed in captivity, ii. <a href="#page149">149</a>;</p> + <p class="i2">compound, individual peculiarities of, reproduced by budding, i. 374;</p> + <p class="i2">variation by selection in useful qualities of, ii. <a href="#page220">220</a>.</p> + <p><span class="sc">Annual</span> plants, rarity of bud-variation in, i. 408.</p> + <p><span class="sc">Anomalies</span> in the osteology of the horse, i. 50.</p> + <p><span class="sc">Anomalous</span> breeds of pigs, i. 75;</p> + <p class="i2">of cattle, i. 89.</p> + <p><i>Anser albifrons</i>, characters of, reproduced in domestic geese, i. 288.</p> + <p><i>Anser ægyptiacus</i>, i. 282; ii. <a href="#page68">68</a>.</p> + <p><i>Anser canadensis</i>, ii. <a href="#page157">157</a>.</p> + <p><i>Anser cygnoides</i>, i. 237.</p> + <p><i>Anser ferus</i>, the original of the domestic goose, i. 287;</p> + <p class="i2">fertility of cross of, with domestic goose, i. 288.</p> + <p><span class="sc">Anson</span>, on feral fowls in the Ladrones, i. 238.</p> + <p><span class="sc">Antagonism</span> between growth and reproduction, ii. <a href="#page384">384</a>.</p> + <p><i>Anthemis nobilis</i>, bud-variation in flowers of, i. 379;</p> + <p class="i2">becomes single in poor soil, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Antherozoids</span>, apparent independence of, in algæ, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Anthers</span>, contabescence of, ii. <a href="#page165">165</a>-<a href="#page166">166</a>.</p> + <p><span class="sc">Antigua</span>, cats of, i. 46;</p> + <p class="i2">changed fleece of sheep in, i. 98.</p> + <p><i>Antirrhinum majus</i>, peloric, i. 365; ii. <a href="#page59">59</a>, <a href="#page70">70</a>, <a href="#page166">166</a>;</p> + <p class="i2">double-flowered, ii. <a href="#page167">167</a>;</p> + <p class="i2">bud-variation in, i. 381.</p> + <p><span class="sc">Ants</span>, individual recognition of, ii. <a href="#page251">251</a>.</p> + <p><span class="sc">Apes</span>, anthropomorphous, ii. <a href="#page123">123</a>.</p> + <p><span class="sc">Aphides</span>, attacking pear-trees, ii. <a href="#page231">231</a>;</p> + <p class="i2">development of, ii. <a href="#page361">361</a>-<a href="#page362">362</a>.</p> + <p><span class="sc">Apoplexy</span>, hereditary, occurring at a certain age, ii. <a href="#page78">78</a>.</p> + <p><span class="sc">Apple</span>, i. 348-350;</p> + <p class="i2">fruit of, in Swiss lake-dwellings, i. 317;</p> + <p class="i2">rendered fastigate by heat in India, i. 361;</p> + <p class="i2">bud-variation in the, i. 376;</p> + <p class="i2">with dimidiate fruit, i. 392-393;</p> + <p class="i2">with two kinds of fruit on the same branch, i. 392;</p> + <p class="i2">artificial fecundation of, i. 401;</p> + <p class="i2">St. Valéry, i. 401; ii. <a href="#page166">166</a>;</p> + <p class="i2">reversion in seedlings of, ii. <a href="#page31">31</a>;</p> + <p class="i2">crossing of varieties of, ii. <a href="#page129">129</a>;</p> + <p class="i2">growth of the, in Ceylon, ii. <a href="#page277">277</a>;</p> + <p class="i2">Winter Majetin, not attacked by <i>coccus</i>, ii. <a href="#page231">231</a>;</p> + <p class="i2">flower-buds of, attacked by bullfinches, ii. <a href="#page232">232</a>;</p> + <p class="i2">American, change of when grown in England, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Apricot</span>, i. 344-345;</p> + <p class="i2">glands on the leaves of, ii. <a href="#page231">231</a>;</p> + <p class="i2">analogous variation in the, ii. <a href="#page348">348</a>.</p> + <p><i>Aquila fusca</i>, copulating in captivity, ii. <a href="#page154">154</a>.</p> + <p><i>Aquilegia vulgaris</i>, i. 365; ii. <a href="#page330">330</a>.</p> + <p><span class="sc">Arab</span> boarhound, described by Harcourt, i. 17.</p> + <p><i>Arabis blepharophylla</i> and <i>A. Soyeri,</i> effects of crossing, i. 400.</p> + <p><i>Aralia trifoliata</i>, bud-variation in leaves of, i. 382.</p> + <p><span class="sc">Araucarias</span>, young, variable resistance of, to frost, ii. <a href="#page309">309</a>.</p> + <p><span class="sc">Archangel</span> pigeon, ii. <a href="#page240">240</a>.</p> + <p><span class="sc">Arctic</span> regions, variability of plants and shells of, ii. <a href="#page256">256</a>.</p> + <p><i>Aria vestita</i>, grafted on thorns, i. 387.</p> + <p><span class="sc">Aristophanes</span>, fowls mentioned by, i. 246.</p> + <p><span class="sc">Aristotle</span>, on solid-hoofed pigs, i. 75;</p> + <p class="i2">domestic duck unknown to, i. 277;</p> + <p class="i2">on the assumption of male characters by old hens, ii. <a href="#page51">51</a>.</p> +<!-- Page 435 --><span class="pagenum"><a name="page435"></a>{435}</span> + <p><span class="sc">Arni</span>, domestication of the, i. 82.</p> + <p><span class="sc">Arrest</span> of development, ii. <a href="#page315">315</a>-<a href="#page318">318</a>.</p> + <p><span class="sc">Arteries</span>, increase of anastomosing branches of, when tied, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Aru</span> islands, wild pig of, i. 67.</p> + <p><span class="sc">Arum</span>, Polynesian varieties of, ii. <a href="#page256">256</a>.</p> + <p><i>Ascaris</i>, number of eggs of, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Ash</span>, varieties of the, i. 360;</p> + <p class="i2">weeping, i. 361;</p> + <p class="i2">simple-leaved, i. 362;</p> + <p class="i2">bud-variation in, i. 382;</p> + <p class="i2">effects of graft upon the stock in the, i. 394;</p> + <p class="i2">production of the blotched Breadalbane, <i>ibid.</i>;</p> + <p class="i2">weeping, capricious reproduction of, by seed, ii. <a href="#page19">19</a>.</p> + <p><i>Asinus Burchellii</i>, i. 64.</p> + <p><i>Asinus hemionus</i>, ii. <a href="#page43">43</a>.</p> + <p><i>Asinus indicus</i>, ii. <a href="#page42">42</a>-<a href="#page43">43</a>, <a href="#page48">48</a>.</p> + <p><i>Asinus quagga</i>, i. 64.</p> + <p><i>Asinus tæniopus</i>, ii. <a href="#page41">41</a>;</p> + <p class="i2">the original of the domestic ass, i. 62.</p> + <p><span class="sc">Asparagus</span>, increased fertility of cultivated, ii. <a href="#page113">113</a>.</p> + <p><span class="sc">Ass</span>, early domestication of the, i. 62;</p> + <p class="i2">breeds of, <i>ibid.</i>;</p> + <p class="i2">small size of, in India, <i>ibid.</i>;</p> + <p class="i2">stripes of, i. 62-63; ii. <a href="#page351">351</a>;</p> + <p class="i2">dislike of to cross water, i. 181;</p> + <p class="i2">reversion in, ii. <a href="#page41">41</a>-<a href="#page43">43</a>, <a href="#page47">47</a>;</p> + <p class="i2">hybrid of the, with mare and zebra, ii. <a href="#page42">42</a>;</p> + <p class="i2">prepotency of the, over the horse, ii. <a href="#page67">67</a>-<a href="#page68">68</a>;</p> + <p class="i2">crossed with wild ass, ii. <a href="#page206">206</a>;</p> + <p class="i2">variation and selection of the, ii. <a href="#page236">236</a>.</p> + <p><span class="sc">Assyrian</span> sculpture of a mastiff, i. 17.</p> + <p><span class="sc">Asters</span>, ii. <a href="#page20">20</a>, <a href="#page316">316</a>.</p> + <p><span class="sc">Asthma</span>, hereditary, ii. <a href="#page8">8</a>, <a href="#page79">79</a>.</p> + <p><span class="sc">Atavism</span>. <i>See</i> Reversion.</p> + <p><span class="sc">Athelstan</span>, his care of horses, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Atkinson</span>, Mr., on the sterility of the Tarroo silk-moth in confinement, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Aubergine</span>, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Audubon</span>, on feral hybrid ducks, i. 190; ii. <a href="#page46">46</a>;</p> + <p class="i2">on the domestication of wild ducks on the Mississippi, i. 278;</p> + <p class="i2">on the wild cock turkey visiting domestic hens, i. 292;</p> + <p class="i2">fertility of <i>Fringilla ciris</i> in captivity, ii. <a href="#page154">154</a>;</p> + <p class="i2">fertility of <i>Columba migratoria</i> and <i>leucocephala</i> in captivity, ii. <a href="#page155">155</a>;</p> + <p class="i2">breeding of <i>Anser canadensis</i> in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Audubon</span> and Bachman, on the change of coat in <i>Ovis montana</i>, i. 99;</p> + <p class="i2">sterility of <i>Sciurus cinerea</i> in confinement, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Auricula</span>, effect of seasonal conditions on the, ii. <a href="#page273">273</a>;</p> + <p class="i2">blooming of, ii. <a href="#page346">346</a>.</p> + <p><span class="sc">Australia</span>, no generally useful plants derived from, i. 310;</p> + <p class="i2">useful plants of, enumerated by Hooker, i. 311.</p> + <p><span class="sc">Austria</span>, heredity of character in emperors of, ii. <a href="#page65">65</a>.</p> + <p><span class="sc">Autenrieth</span>, on persistency of colour in horses, ii. <a href="#page21">21</a>.</p> + <p><span class="sc">Ava</span>, horses of, i. 53.</p> + <p><i>Avena fatua</i>, cultivability of, i. 313.</p> + <p><span class="sc">Ayeen</span> Akbery, pigeons mentioned in the, i. 150, 155, 185, 205, 207, 208.</p> + <p><span class="sc">Ayres, W. P.</span>, on bud-variation in pelargoniums, i. 378.</p> + <p><i>Azalea indica</i>, bud-variation in, i. 377.</p> + <p><span class="sc">Azara</span>, on the feral dogs of La Plata, i. 27;</p> + <p class="i2">on the crossing of domestic with wild cats in Paraguay, i. 45;</p> + <p class="i2">on hornlike processes in horses, i. 50;</p> + <p class="i2">on curled hair in horses, i. 54; ii. <a href="#page205">205</a>, <a href="#page325">325</a>;</p> + <p class="i2">on the colours of feral horses, i. 60, 61; ii. <a href="#page259">259</a>;</p> + <p class="i2">on the cattle of Paraguay and La Plata, i. 82, 86, 89; ii. <a href="#page250">250</a>;</p> + <p class="i2">on a hornless bull, ii. <a href="#page205">205</a>;</p> + <p class="i2">on the increase of cattle in South America, ii. <a href="#page119">119</a>;</p> + <p class="i2">on the growth of horns in the hornless cattle of Corrientes, ii. <a href="#page39">39</a>;</p> + <p class="i2">on the "Niata" cattle, i. 90;</p> + <p class="i2">on naked quadrupeds, ii. <a href="#page279">279</a>;</p> + <p class="i2">on a race of black-skinned fowls in South America, i. 258; ii. <a href="#page209">209</a>;</p> + <p class="i2">on a variety of maize, i. 321.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Babington, C. C.</span>, on the origin of the plum, i. 345;</p> + <p class="i2">British species of the genus <i>Rosa</i>, i. 366;</p> + <p class="i2">distinctness of <i>Viola lutea</i> and <i>tricolor</i>, i. 368.</p> + <p><span class="sc">Bachmann</span>, Mr., on the turkey, ii. <a href="#page262">262</a>.</p> + <p class="i2"><i>See also</i> Audubon.</p> + <p><span class="sc">Badger</span>, breeding in confinement, ii. <a href="#page151">151</a>.</p> + <p>"<span class="sc">Bagadotten-Taube</span>," i. 141.</p> + <p><span class="sc">Baily</span>, Mr., on the effect of selection on fowls, ii. <a href="#page198">198</a>;</p> + <p class="i2">on Dorking fowls, ii. <a href="#page238">238</a>.</p> + <p><span class="sc">Baird, S.</span>, on the origin of the turkey, i. 292.</p> + <p><span class="sc">Baker</span>, Mr., on heredity in the horse, ii. <a href="#page11">11</a>;</p> + <p class="i2">on the degeneration of the horse by neglect, ii. <a href="#page239">239</a>;</p> + <p class="i2">orders of Henrys VII. and VIII. for the destruction of undersized mares, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Bakewell</span>, change in the sheep effected by, ii. <a href="#page198">198</a>.</p> + <p><span class="sc">Balancement</span>, ii. <a href="#page342">342</a>-<a href="#page344">344</a>;</p> + <p class="i2">of growth, law of, i. 274.</p> + <p><span class="sc">Baldhead</span>, pigeon, i. 151.</p> + <p><span class="sc">Baldness</span>, in man, inherited, ii. <a href="#page73">73</a>-<a href="#page74">74</a>;</p> + <p class="i2">with deficiency in teeth, ii. <a href="#page326">326</a>-<a href="#page327">327</a>.</p> + <p><span class="sc">Ballance</span>, Mr., on the effects of interbreeding on fowls, ii. <a href="#page125">125</a>;</p> + <p class="i2">on variation in the eggs of fowls, i. 248.</p> + <p><i>Ballota nigra</i>, transmission of variegated leaves in, i. 383.</p> + <p><span class="sc">Bamboo</span>, varieties of the, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Banana</span>, variation of the, i. 372; ii. <a href="#page256">256</a>, <a href="#page258">258</a>;</p> + <p class="i2">bud-variation in the, i. 377;</p> + <p class="i2">sterility of the, ii. <a href="#page268">268</a>.</p> + <p><span class="sc">Bantam</span> fowls, i. 230;</p> + <p class="i2">Sebright, origin of, ii. <a href="#page96">96</a>;</p> + <p class="i2">sterility of, ii. <a href="#page101">101</a>.</p> + <p><span class="sc">Barb</span> (Pigeon), i. 144-146, 210; ii. <a href="#page227">227</a>;</p> +<!-- Page 436 --><span class="pagenum"><a name="page436"></a>{436}</span> + <p class="i2">figure of, i. 145;</p> + <p class="i2">figure of lower jaw of, i. 164.</p> + <p><span class="sc">Barbs</span>, of wheat, i. 314.</p> + <p><span class="sc">Barberry</span>, dark or red-leaved variety, i. 362; ii. <a href="#page19">19</a>;</p> + <p class="i2">reversion in suckers of seedless variety, i. 384.</p> + <p><span class="sc">Barbut, J.</span>, on the dogs of Guinea, i. 25;</p> + <p class="i2">on the domestic pigeons in Guinea, i. 186;</p> + <p class="i2">fowls not native in Guinea, i. 237.</p> + <p><span class="sc">Barking</span>, acquisition of the habit of, by various dogs, i. 27.</p> + <p><span class="sc">Barley</span>, wild, i. 313;</p> + <p class="i2">of the lake-dwellings, i. 317-318;</p> + <p class="i2">ancient variety of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Barnes</span>, Mr., production of early peas by selection, ii. <a href="#page201">201</a>.</p> + <p><span class="sc">Barnet</span>, Mr., on the intercrossing of strawberries, i. 351;</p> + <p class="i2">diœciousness of the Hautbois strawberry, i. 353;</p> + <p class="i2">on the scarlet American strawberry, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Barth</span>, Dr., use of grass-seeds as food in Central Africa, i. 308.</p> + <p><span class="sc">Bartlett, A. D.</span>, on the origin of "Himalayan" rabbits by intercrossing, i. 109;</p> + <p class="i2">on the feral rabbits of Porto Santo, i. 114;</p> + <p class="i2">on geese with reversed feathers on the head and neck, i. 288;</p> + <p class="i2">on the young of the black-shouldered peacock, i. 290;</p> + <p class="i2">on the breeding of the Felidæ in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Bartram</span>, on the black wolf-dog of Florida, i. 22.</p> + <p><span class="sc">Bates, H. W.</span>, refusal of wild animals to breed in captivity, ii. <a href="#page150">150</a>, <a href="#page152">152</a>;</p> + <p class="i2">sterility of American monkeys in captivity, ii. <a href="#page153">153</a>;</p> + <p class="i2">sterility of tamed guans, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Batrachia</span>, regeneration of lost parts in, ii. <a href="#page15">15</a>.</p> + <p><span class="sc">Beach</span>, raised, in Peru, containing heads of maize, i. 320.</p> + <p><span class="sc">Beak</span>, variability of, in fowls, i. 258;</p> + <p class="i2">individual differences of, in pigeons, i. 160;</p> + <p class="i2">correlation of, with the feet in pigeons, i. 171-174.</p> + <p><span class="sc">Beale</span>, Lionel, on the contents of cells, ii. <a href="#page370">370</a>;</p> + <p class="i2">on the multiplication of infectious atoms, ii. <a href="#page378">378</a>;</p> + <p class="i2">on the origin of fibres, ii. <a href="#page382">382</a>.</p> + <p><span class="sc">Beans</span>, i. 330;</p> + <p class="i2">of Swiss lake-dwellings, i. 319;</p> + <p class="i2">varieties of, produced by selection, ii. <a href="#page218">218</a>;</p> + <p class="i2">French and scarlet, variable resistance of to frost, ii. <a href="#page309">309</a>, <a href="#page314">314</a>;</p> + <p class="i2">superiority of native seed of, ii. <a href="#page314">314</a>;</p> + <p class="i2">a symmetrical variation of scarlet, ii. <a href="#page322">322</a>;</p> + <p class="i2">experiments on kidney, i. 330;</p> + <p class="i2">with monstrous stipules and abortive leaflets, ii. <a href="#page343">343</a>.</p> + <p><span class="sc">Beard</span>, pigeon, i. 151.</p> + <p><span class="sc">Bears</span>, breeding in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Beasley, J.</span>, reversion in crossed cattle, ii. <a href="#page41">41</a>.</p> + <p><span class="sc">Beaton, D.</span>, effect of soil upon strawberries, i. 353;</p> + <p class="i2">on varieties of pelargonium, i. 364, ii. <a href="#page274">274</a>, <a href="#page311">311</a>;</p> + <p class="i2">bud-variation in <i>Gladiolus colvillii</i>, i. 382;</p> + <p class="i2">cross between Scotch kail and cabbage, ii. <a href="#page98">98</a>;</p> + <p class="i2">hybrid gladiolus, ii. <a href="#page139">139</a>;</p> + <p class="i2">constant occurrence of new forms among seedlings, ii. <a href="#page235">235</a>;</p> + <p class="i2">on the doubling of the compositæ, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Bechuana</span> cattle, i. 88.</p> + <p><span class="sc">Beck</span>, Mr., constitutional differences in pelargoniums, i. 364.</p> + <p><span class="sc">Beckmann</span>, on changes in the odours of plants, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Beckstein</span>, on the burrowing of wolves, i. 27;</p> + <p class="i2">"Spitz" dog, i. 31;</p> + <p class="i2">origin of the Newfoundland dog, i. 42;</p> + <p class="i2">crossing of domestic and wild swine, i. 66;</p> + <p class="i2">on the Jacobin pigeon, i. 154, 209;</p> + <p class="i2">notice of swallow-pigeons, i. 156;</p> + <p class="i2">on a fork-tailed pigeon, i. 157;</p> + <p class="i2">variations in the colour of the croup in pigeons, i. 184;</p> + <p class="i2">on the German dove-cot pigeon, i. 185;</p> + <p class="i2">fertility of mongrel pigeons, i. 192;</p> + <p class="i2">on hybrid turtle-doves, i. 193;</p> + <p class="i2">on crossing the pigeon with <i>Columba œnas</i>, <i>C. palumbus</i>, <i>Turtur risoria</i>, and <i>T. vulgaris</i>, i. 193;</p> + <p class="i2">development of spurs in the silk-hen, i. 256;</p> + <p class="i2">on Polish fowls, i. 257, 264;</p> + <p class="i2">on crested birds, i. 257;</p> + <p class="i2">on the Canary-bird, i. 295, ii. <a href="#page22">22</a>, <a href="#page161">161</a>;</p> + <p class="i2">German superstition about the turkey, i. 293;</p> + <p class="i2">occurrence of horns in hornless breeds of sheep, ii. <a href="#page30">30</a>;</p> + <p class="i2">hybrids of the horse and ass, ii. <a href="#page68">68</a>;</p> + <p class="i2">crosses of tailless fowls, ii. <a href="#page92">92</a>;</p> + <p class="i2">difficulty of pairing dove-cot and fancy pigeons, ii. <a href="#page103">103</a>;</p> + <p class="i2">fertility of tame ferrets and rabbits, ii. <a href="#page112">112</a>;</p> + <p class="i2">fertility of wild sow, <i>ibid.</i>;</p> + <p class="i2">difficulty of breeding caged birds, ii. <a href="#page154">154</a>;</p> + <p class="i2">comparative fertility of <i>Psittacus erithacus</i> in captivity, ii. <a href="#page155">155</a>;</p> + <p class="i2">on changes of plumage in captivity, ii. <a href="#page158">158</a>;</p> + <p class="i2">liability of light-coloured cattle to the attacks of flies, ii. <a href="#page229">229</a>;</p> + <p class="i2">want of exercise a cause of variability, ii. <a href="#page257">257</a>;</p> + <p class="i2">effect of privation of light upon the plumage of birds, ii. <a href="#page280">280</a>;</p> + <p class="i2">on a sub-variety of the monk-pigeon, ii. <a href="#page350">350</a>.</p> + <p><span class="sc">Beddoe</span>, Dr., correlation of complexion with consumption, ii. <a href="#page335">335</a>.</p> + <p><span class="sc">Bedeguar</span> gall, ii. <a href="#page284">284</a>.</p> + <p><span class="sc">Bee</span>, persistency of character of, ii. <a href="#page236">236</a>, <a href="#page254">254</a>;</p> + <p class="i2">intercrossing, ii. <a href="#page126">126</a>;</p> + <p class="i2">conveyance, of pollen of peas by, i. 329.</p> + <p><span class="sc">Bee-Ophrys</span>, self-fertilisation of, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Beech</span>, dark-leaved, i. 362, ii. <a href="#page19">19</a>;</p> + <p class="i2">fern-leaved, reversion of, i. 382;</p> + <p class="i2">weeping, non-production of by seed, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Beechey</span>, horses of Loochoo Islands, i. 53.</p> + <p><span class="sc">Beet</span>, i. 326;</p> + <p class="i2">increase of sugar in, by selection, ii. <a href="#page201">201</a>.</p> +<!-- Page 437 --><span class="pagenum"><a name="page437"></a>{437}</span> + <p><i>Begonia frigida</i>, singular variety of, i. 365;</p> + <p class="i2">sterility of, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Belgian</span> rabbit, i. 106.</p> + <p><span class="sc">Bell, T.</span>, statement that white cattle have coloured ears, i. 85.</p> + <p><span class="sc">Bell, W.</span>, bud-variation in <i>Cistus tricuspis</i>, i. 377.</p> + <p><span class="sc">Bellingeri</span>, observations on gestation in the dog, i. 30;</p> + <p class="i2">on the fertility of dogs and cats, ii. <a href="#page112">112</a>.</p> + <p><span class="sc">Belon</span>, on high-flying pigeons in Paphlagonia, i. 209;</p> + <p class="i2">varieties of the goose, i. 289.</p> + <p><span class="sc">Benguela</span>, cattle of, i. 88.</p> + <p><span class="sc">Bennett</span>, Dr. G., pigs of the Pacific islands, i. 70, 87;</p> + <p class="i2">dogs of the Pacific islands, i. 87;</p> + <p class="i2">varieties of cultivated plants in Tahiti, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Bennett</span>, Mr., on the fallow deer, ii. <a href="#page103">103</a>.</p> + <p><span class="sc">Bentham, G.</span>, number and origin of cultivated plants, i. 306;</p> + <p class="i2">cereals all cultivated varieties, i. 312;</p> + <p class="i2">species of the orange group, i. 334-335;</p> + <p class="i2">distinctions of almond and peach, i. 338;</p> + <p class="i2">British species of <i>Rosa</i>, i. 366;</p> + <p class="i2">identity of <i>Viola lutea</i> and <i>tricolor</i>, i. 368.</p> + <p><i>Berberis vulgaris</i>, i. 384, ii. <a href="#page19">19</a>.</p> + <p><i>Berberis Wallichii</i>, indifference of, to climate, ii. <a href="#page164">164</a>.</p> + <p><span class="sc">Berjean</span>, on the history of the dog, i. 16, 18.</p> + <p><span class="sc">Berkeley, G. F.</span>, production of hen-cocks in a strain of game-fowls, i. 253.</p> + <p><span class="sc">Berkeley, M. J.</span>, crossing of varieties of the pea, i. 397;</p> + <p class="i2">effect of foreign pollen on grapes, i. 400;</p> + <p class="i2">on hybrid plants, ii. <a href="#page131">131</a>;</p> + <p class="i2">analogy between pollen of highly-cultivated plants and hybrids, ii. <a href="#page268">268</a>;</p> + <p class="i2">on Hungarian kidney-beans, ii. <a href="#page275">275</a>;</p> + <p class="i2">failure of Indian wheat in England, ii. <a href="#page307">307</a>;</p> + <p class="i2">bud developed on the petal of a <i>Clarkia</i>, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Bernard</span>, inheritance of disease in the horse, ii. <a href="#page10">10</a>.</p> + <p><span class="sc">Bernard, C.</span>, independence of the organs of the body, ii. <a href="#page368">368</a>-<a href="#page369">369</a>;</p> + <p class="i2">special affinities of the tissues, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Bernhardi</span>, varieties of plants with laciniated leaves, ii. <a href="#page348">348</a>.</p> + <p><i>Bernicla antarctica</i>, i. 288.</p> + <p><span class="sc">Bertero</span>, on feral pigeons in Juan Fernandez, i. 190.</p> + <p><i>Betula alba</i>, ii. <a href="#page18">18</a>.</p> + <p><span class="sc">Bewick</span>, on the British wild cattle, i. 84.</p> + <p><span class="sc">Bible</span>, reference to breeding studs of horses in, i. 54;</p> + <p class="i2">references to domestic pigeons in the, i. 205;</p> + <p class="i2">indications of selection of sheep in the, ii. <a href="#page201">201</a>;</p> + <p class="i2">notice of mules in the, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Bidwell</span>, Mr., on self-impotence in <i>Amaryllis</i>, ii. <a href="#page139">139</a>.</p> + <p><span class="sc">Birch</span>, weeping, i. 387, ii. <a href="#page18">18</a>.</p> + <p><span class="sc">Birch</span>, Dr. S., on the ancient domestication of the pigeon in Egypt, i. 205;</p> + <p class="i2">notice of bantam fowls in a Japanese encyclopædia, i. 230, 247.</p> + <p><span class="sc">Birch</span>, Wyrley, on silver-grey rabbits, i. 109-110.</p> + <p><span class="sc">Birds</span>, sterility caused in, by change of conditions, ii. <a href="#page153">153</a>-<a href="#page157">157</a>.</p> + <p><span class="sc">Bladder-nut</span>, tendency of the, to become double, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Blaine</span>, Mr., on wry-legged terriers, ii. <a href="#page245">245</a>.</p> + <p><span class="sc">Blainville</span>, origin and history of the dog, i. 15-16;</p> + <p class="i2">variations in the number of teeth in dogs, i. 34;</p> + <p class="i2">variations in the number of toes in dogs, i. 35;</p> + <p class="i2">on mummies of cats, i. 43;</p> + <p class="i2">on the osteology of solid-hoofed pigs, i. 75;</p> + <p class="i2">on feral Patagonian and N. American pigs, i. 77.</p> + <p>"<span class="sc">Blass-Taube</span>," i. 156.</p> + <p><span class="sc">Bleeding</span>, hereditary, ii. <a href="#page7">7</a>, <a href="#page8">8</a>;</p> + <p class="i2">sexual limitation of excessive, ii. <a href="#page73">73</a>.</p> + <p><span class="sc">Blending</span> of crossed races, time occupied by the, ii. <a href="#page87">87</a>.</p> + <p><span class="sc">Blindness</span>, hereditary, ii. <a href="#page9">9</a>;</p> + <p class="i2">at a certain age, ii. <a href="#page78">78</a>;</p> + <p class="i2">associated with colour of hair, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Bloodhounds</span>, degeneration of, caused by interbreeding, ii. <a href="#page121">121</a>.</p> + <p><span class="sc">Blumenbach</span>, on the protuberance of the skull in Polish fowls, i. 257;</p> + <p class="i2">on the effect of circumcision, ii. <a href="#page23">23</a>;</p> + <p class="i2">inheritance of a crooked finger, ii. <a href="#page23">23</a>;</p> + <p class="i2">on badger-dogs and other varieties of the dog, ii. <a href="#page220">220</a>;</p> + <p class="i2">on <i>Hydra</i>, ii. <a href="#page293">293</a>;</p> + <p class="i2">on the "nisus formativus," ii. <a href="#page294">294</a>.</p> + <p><span class="sc">Blyth, E.</span>, on the Pariah dog, i. 24;</p> + <p class="i2">hybrids of dog and jackal, i. 32;</p> + <p class="i2">early domestication of cats in India, i. 43;</p> + <p class="i2">origin of domestic cat, <i>ib.</i>;</p> + <p class="i2">crossing of domestic and wild cats, i. 44;</p> + <p class="i2">on Indian cats resembling <i>Felis chaus</i>, i. 45;</p> + <p class="i2">on striped Burmese ponies, i. 58;</p> + <p class="i2">on the stripes of the ass, i. 63;</p> + <p class="i2">on Indian wild pigs, i. 66;</p> + <p class="i2">on humped cattle, i. 79, 80;</p> + <p class="i2">occurrence of <i>Bos frontosus</i> in Irish crannoges, i. 81;</p> + <p class="i2">fertile crossing of zebus and common cattle, i. 83;</p> + <p class="i2">on the species of sheep, i. 94;</p> + <p class="i2">on the fat-tailed Indian sheep, i. 96;</p> + <p class="i2">origin of the goat, i. 101;</p> + <p class="i2">on rabbits breeding in India, i. 112;</p> + <p class="i2">number of tail-feathers in fantails, i. 146;</p> + <p class="i2">Lotan tumbler pigeons, i. 150;</p> + <p class="i2">number of tail-feathers in <i>Ectopistes</i>, i. 159;</p> + <p class="i2">on <i>Columba affinis</i>, i. 183;</p> + <p class="i2">pigeons roosting in trees, i. 181;</p> + <p class="i2">on <i>Columba leuconota</i>, i. 182;</p> + <p class="i2">on <i>Columba intermedia</i> of Strickland, i. 184;</p> + <p class="i2">variation in colour of croup in pigeons, i. 184-185, 197;</p> + <p class="i2">voluntary domestication of rock-pigeons in India, i. 185;</p> + <p class="i2">feral pigeons on the Hudson, i. 190;</p> +<!-- Page 438 --><span class="pagenum"><a name="page438"></a>{438}</span> + <p class="i2">occurrence of sub-species of pigeons, i. 204;</p> + <p class="i2">notice of pigeon-fanciers in Delhi, &c., i. 206;</p> + <p class="i2">hybrids of <i>Gallus Sonneratii</i> and the domestic hen, i. 234;</p> + <p class="i2">supposed hybridity of <i>Gallus Temminckii</i>, i. 235;</p> + <p class="i2">variations and domestication of <i>Gallus bankiva</i>, i. 235-236, 237;</p> + <p class="i2">crossing of wild and tame fowls in Burmah, i. 236;</p> + <p class="i2">restricted range of the larger gallinaceous birds, i. 237;</p> + <p class="i2">feral fowls in the Nicobar islands, i. 238;</p> + <p class="i2">black-skinned fowls occurring near Calcutta, i. 256;</p> + <p class="i2">weight of <i>Gallus bankiva</i>, i. 272;</p> + <p class="i2">degeneration of the turkey in India, i. 294, ii. <a href="#page278">278</a>;</p> + <p class="i2">on the colour of gold-fish, i. 296;</p> + <p class="i2">on the Ghor-Khur (<i>Asinus indicus</i>), ii. <a href="#page42">42</a>;</p> + <p class="i2">on <i>Asinus hemionus</i>, ii. <a href="#page43">43</a>;</p> + <p class="i2">number of eggs of <i>Gallus bankiva</i>, ii. <a href="#page112">112</a>;</p> + <p class="i2">on the breeding of birds in captivity, ii. <a href="#page157">157</a>;</p> + <p class="i2">co-existence of large and small breeds in the same country, ii. <a href="#page279">279</a>;</p> + <p class="i2">on the drooping ears of the elephant, ii. <a href="#page301">301</a>;</p> + <p class="i2">homology of leg and wing feathers, ii. <a href="#page323">323</a>.</p> + <p><span class="sc">Boethius</span> on Scotch wild cattle, i. 85.</p> + <p><span class="sc">Boitard</span> and Corbié, on the breeds of pigeons, i. 132;</p> + <p class="i2">Lille pouter pigeon, i. 138;</p> + <p class="i2">notice of a gliding pigeon, i. 156;</p> + <p class="i2">variety of the pouter pigeon, i. 162;</p> + <p class="i2">dove-cot pigeon, i. 185;</p> + <p class="i2">crossing pigeons, i. 192-193, ii. <a href="#page97">97</a>, <a href="#page126">126</a>;</p> + <p class="i2">sterility of hybrids of turtle-doves, i. 193;</p> + <p class="i2">reversion of crossed pigeons, i. 197, ii. <a href="#page40">40</a>;</p> + <p class="i2">on the fantail, i. 208, ii. <a href="#page66">66</a>;</p> + <p class="i2">on the trumpeter, ii. <a href="#page66">66</a>;</p> + <p class="i2">prepotency of transmission in silky fantail, ii. <a href="#page67">67</a>, <a href="#page69">69</a>;</p> + <p class="i2">secondary sexual characters in pigeons, ii. <a href="#page74">74</a>;</p> + <p class="i2">crossing of white and coloured turtle-doves, ii. <a href="#page92">92</a>;</p> + <p class="i2">fertility of pigeons, ii. <a href="#page112">112</a>.</p> + <p><span class="sc">Bombycidæ</span>, wingless females of, ii. <a href="#page299">299</a>.</p> + <p><i>Bombyx hesperus</i>, ii. <a href="#page304">304</a>.</p> + <p><i>Bombyx Huttoni</i>, i. 302.</p> + <p><i>Bombyx mori</i>, i. 300-304.</p> + <p><span class="sc">Bonafous</span>, on maize, i. 320, 321.</p> + <p><span class="sc">Bonaparte</span>, number of species of Columbidæ, i. 133;</p> + <p class="i2">number of tail-feathers in pigeons, i. 158;</p> + <p class="i2">size of the feet in Columbidæ, i. 174;</p> + <p class="i2">on <i>Columba guinea</i>, i. 182;</p> + <p class="i2"><i>Columba turricola</i>, <i>rupestris</i>, and <i>Schimperi</i>, i. 184.</p> + <p><i>Bonatea speciosa</i>, development of ovary of, i. 403.</p> + <p><span class="sc">Bonavia</span>, Dr., growth of cauliflowers in India, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Bones</span>, removal of portions of, ii. <a href="#page296">296</a>;</p> + <p class="i2">regeneration of, ii. <a href="#page294">294</a>;</p> + <p class="i2">growth and repair of, ii. <a href="#page381">381</a>-<a href="#page382">382</a>.</p> + <p><span class="sc">Bonnet</span>, on the salamander, ii. <a href="#page15">15</a>, <a href="#page341">341</a>, <a href="#page358">358</a>, <a href="#page385">385</a>;</p> + <p class="i2">theory of reproduction, ii. <a href="#page385">385</a>.</p> + <p><span class="sc">Borchmeyer</span>, experiments with the seeds of the weeping ash, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Borecole</span>, i. 323.</p> + <p><span class="sc">Borelli</span>, on Polish fowls, i. 247.</p> + <p><span class="sc">Borneo</span>, fowls of, with tail-bands, i. 235.</p> + <p><span class="sc">Bornet, E.</span>, condition of the ovary in hybrid <i>Cisti</i>, i. 389;</p> + <p class="i2">self-impotence of hybrid <i>Cisti</i>, ii. <a href="#page140">140</a>.</p> + <p><span class="sc">Borrow, G.</span>, on pointers, i. 42.</p> + <p><span class="sc">Bory</span> de Saint-Vincent, on gold-fish, i. 297.</p> + <p><i>Bos</i>, probable origin of European domestic cattle from three species of, i. 83.</p> + <p><i>Bos frontosus</i>, i. 79, 81-82.</p> + <p><i>Bos indicus</i>, i. 79.</p> + <p><i>Bos longifrons</i>, i. 79, 81.</p> + <p><i>Bos primigenius</i>, i. 79-81, 119.</p> + <p><i>Bos sondaicus</i>, ii. <a href="#page206">206</a>.</p> + <p><i>Bos taurus</i>, i. 79.</p> + <p><i>Bos trochoceros</i>, i. 81.</p> + <p><span class="sc">Bosc</span>, heredity in foliage-varieties of the elm, i. 362.</p> + <p><span class="sc">Bosse</span>, production of double flowers from old seed, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Bossi</span>, on breeding dark-coloured silkworms, i. 302.</p> + <p><span class="sc">Bouchardat</span>, on the vine disease, i. 334.</p> + <p><span class="sc">Boudin</span>, on local diseases, ii. <a href="#page276">276</a>;</p> + <p class="i2">resistance to cold of dark-complexioned men, ii. <a href="#page335">335</a>.</p> + <p>"<span class="sc">Boulans</span>," i. 137.</p> + <p>"<span class="sc">Bouton</span> d'Alep," ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Bowen</span>, Prof., doubts as to the importance of inheritance, ii. <a href="#page3">3</a>.</p> + <p><span class="sc">Bowman</span>, Mr., hereditary peculiarities in the human eye, ii. <a href="#page8">8</a>-<a href="#page10">10</a>;</p> + <p class="i2">hereditary cataract, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Brace</span>, Mr., on Hungarian cattle, i. 80.</p> + <p><i>Brachycome iberidifolia</i>, ii. <a href="#page261">261</a>.</p> + <p><span class="sc">Bracts</span>, unusual development of, in gooseberries, i. 355.</p> + <p><span class="sc">Bradley</span>, Mr., effect of grafts upon the stock in the ash, i. 394;</p> + <p class="i2">effect of foreign pollen upon apples, i. 401;</p> + <p class="i2">on change of soil, ii. <a href="#page146">146</a>.</p> + <p>"<span class="sc">Brahma</span> Pootras," a new breed of fowls, i. 245.</p> + <p><span class="sc">Brain</span>, proportion of, in hares and rabbits, i. 126-129.</p> + <p><span class="sc">Brandt</span>, origin of the goat, i. 101.</p> + <p><i>Brassica</i>, varieties of, with enlarged stems, ii. <a href="#page348">348</a>.</p> + <p><i>Brassica asperifolia</i>, ii. <a href="#page343">343</a>.</p> + <p><i>Brassica napus</i>, i. 325.</p> + <p><i>Brassica oleracea</i>, i. 323.</p> + <p><i>Brassica rapa</i>, i. 325, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Braun, A.</span>, bud-variation in the vine, i. 375;</p> + <p class="i2">in the currant, i. 376;</p> + <p class="i2">in <i>Mirabilis jalapa</i>, i. 382;</p> + <p class="i2">in <i>Cytisus adami</i>, i. 388;</p> + <p class="i2">on reversion in the foliage of trees, i. 382;</p> + <p class="i2">spontaneous production of <i>Cytisus purpureo-elongatus</i>, i. 390;</p> + <p class="i2">reversion of flowers by stripes and blotches, ii. <a href="#page37">37</a>;</p> + <p class="i2">excess of nourishment a source of variability, ii. <a href="#page257">257</a>.</p> +<!-- Page 439 --><span class="pagenum"><a name="page439"></a>{439}</span> + <p><span class="sc">Brazil</span>, cattle of, i. 88.</p> + <p><span class="sc">Bread-fruit</span>, varieties of, ii. <a href="#page256">256</a>;</p> + <p class="i2">sterility and variability of, ii. <a href="#page262">262</a>.</p> + <p><span class="sc">Bree, W. T.</span>, bud-variation in <i>Geranium pratense</i> and <i>Centaurea cyanus</i>, i. 379;</p> + <p class="i2">by tubers in the dahlia, i. 385;</p> + <p class="i2">on the deafness of white cats with blue eyes, ii. <a href="#page329">329</a>.</p> + <p><span class="sc">Breeding</span>, high, dependent on inheritance, ii. <a href="#page3">3</a>-<a href="#page4">4</a>.</p> + <p><span class="sc">Breeds</span>, domestic, persistency of, ii. <a href="#page246">246</a>, <a href="#page428">428</a>-<a href="#page429">429</a>;</p> + <p class="i2">artificial and natural, ii. <a href="#page413">413</a>-<a href="#page414">414</a>;</p> + <p class="i2">extinction of, ii. <a href="#page425">425</a>;</p> + <p class="i2">of domestic cats, i. 45-47;</p> + <p class="i2">of pigs produced by crossing, i. 78;</p> + <p class="i2">of cattle, i. 86-87, 91-93;</p> + <p class="i2">of goats, i. 101.</p> + <p><span class="sc">Brehm</span>, on <i>Columba amaliæ</i>, i. 183.</p> + <p><span class="sc">Brent, B. P.</span>, number of mammæ in rabbits, i. 106;</p> + <p class="i2">habits of the tumbler pigeon, i. 151;</p> + <p class="i2">Laugher pigeon, i. 155;</p> + <p class="i2">colouring of the kite tumbler, i. 160;</p> + <p class="i2">crossing of the pigeon with <i>Columba œnas</i>, i. 193;</p> + <p class="i2">mongrels of the trumpeter pigeon, ii. <a href="#page66">66</a>;</p> + <p class="i2">close interbreeding of pigeons, ii. <a href="#page126">126</a>;</p> + <p class="i2">opinion on Aldrovandi's fowls, i. 247;</p> + <p class="i2">on stripes in chickens, i. 249-250;</p> + <p class="i2">on the combs of fowls, i. 253;</p> + <p class="i2">double-spurred Dorking fowls, i. 255;</p> + <p class="i2">effect of crossing on colour of plumage in fowls, i. 258;</p> + <p class="i2">incubatory instinct of mongrels between non-sitting varieties of fowls, ii. <a href="#page44">44</a>;</p> + <p class="i2">origin of the domestic duck, i. 277;</p> + <p class="i2">fertility of the hook-billed duck, <i>ibid.</i>;</p> + <p class="i2">occurrence of the plumage of the wild duck in domestic breeds, i. 280;</p> + <p class="i2">voice of ducks, i. 281;</p> + <p class="i2">occurrence of a short upper mandible in crosses of hook-billed and common ducks, i. 281;</p> + <p class="i2">reversion in ducks produced by crossing, ii. <a href="#page40">40</a>;</p> + <p class="i2">variation of the canary-bird, i. 295;</p> + <p class="i2">fashion in the canary, ii. <a href="#page240">240</a>;</p> + <p class="i2">hybrids of canary and finches, ii. <a href="#page45">45</a>.</p> + <p><span class="sc">Brickell</span>, on raising nectarines from seed, i. 340;</p> + <p class="i2">on the horses of North Carolina, ii. <a href="#page300">300</a>.</p> + <p><span class="sc">Bridges</span>, Mr., on the dogs of Tierra del Fuego, i. 39;</p> + <p class="i2">on the selection of dogs by the Fuegians, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Bridgman, W. K.</span>, reproduction of abnormal ferns, i. 383, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Briggs, J. J.</span>, regeneration of portions of the fins of fishes, ii. <a href="#page15">15</a>.</p> + <p><span class="sc">Broca, P.</span>, on the intercrossing of dogs, i. 31-32;</p> + <p class="i2">on hybrids of hare and rabbit, i. 105;</p> + <p class="i2">on the rumpless fowl, i. 259;</p> + <p class="i2">on the character of half-castes, ii. <a href="#page47">47</a>;</p> + <p class="i2">degree of fertility of mongrels, ii. <a href="#page100">100</a>;</p> + <p class="i2">sterility of descendants of wild animals bred in captivity, ii. <a href="#page160">160</a>.</p> + <p><span class="sc">Broccoli</span>, i. 323;</p> + <p class="i2">rudimentary flowers in, ii. <a href="#page316">316</a>;</p> + <p class="i2">tenderness of, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Bromehead, W.</span>, doubling of the Canterbury bell by selection, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Bromfield</span>, Dr., sterility of the ivy and <i>Acorus calamus</i>, ii. <a href="#page170">170</a>.</p> + <p><i>Bromus secalinus</i>, i. 314.</p> + <p><span class="sc">Bronn, H. G.</span>, bud-variation in <i>Anthemis</i>, i. 379;</p> + <p class="i2">effects of cross-breeding on the female, i. 404;</p> + <p class="i2">on heredity in a one-horned cow, ii. <a href="#page12">12</a>, <a href="#page13">13</a>;</p> + <p class="i2">propagation of a pendulous peach by seed, ii. <a href="#page18">18</a>;</p> + <p class="i2">absorption of the minority in crossed races, ii. <a href="#page88">88</a>;</p> + <p class="i2">on the crossing of horses, ii. <a href="#page92">92</a>;</p> + <p class="i2">fertility of tame rabbits and sheep, ii. <a href="#page112">112</a>;</p> + <p class="i2">changes of plumage in captivity, ii. <a href="#page158">158</a>;</p> + <p class="i2">on the dahlia, ii. <a href="#page261">261</a>.</p> + <p><span class="sc">Bronze</span> period, dog of, i. 18.</p> + <p><span class="sc">Brown, G.</span>, variations in the dentition of the horse, i. 50.</p> + <p><span class="sc">Brown-Séquard</span>, Dr., inheritance of artificially-produced epilepsy in the guinea-pig, ii. <a href="#page24">24</a>.</p> + <p><i>Brunswigia</i>, ii. <a href="#page139">139</a>.</p> + <p><span class="sc">Brussels</span> Sprouts, i. 323, ii. <a href="#page429">429</a>.</p> + <p><i>Bubo maximus</i>, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Buckland, F.</span>, on oysters, ii. <a href="#page280">280</a>;</p> + <p class="i2">number of eggs in a codfish, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Buckle</span>, Mr., doubts as to the importance of inheritance, ii. <a href="#page3">3</a>.</p> + <p><span class="sc">Buckley</span>, Miss, carrier-pigeons roosting in trees, i. 181.</p> + <p><span class="sc">Buckman</span>, Prof., cultivation of <i>Avena fatua</i>, i. 313;</p> + <p class="i2">cultivation of the wild parsnip, i. 326, ii. <a href="#page201">201</a>, <a href="#page277">277</a>;</p> + <p class="i2">reversion in the parsnip, ii. <a href="#page31">31</a>.</p> + <p><span class="sc">Buckwheat</span>, injurious to white pigs, when in flower, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Bud</span> and seed, close analogy of, i. 411.</p> + <p><span class="sc">Bud-reversion</span>, ii. <a href="#page37">37</a>.</p> + <p><span class="sc">Buds</span>, adventitious, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Bud-variation</span>, i. 373-411, ii. <a href="#page254">254</a>, <a href="#page287">287</a>-<a href="#page288">288</a>, <a href="#page291">291</a>;</p> + <p class="i2">contrasted with seminal reproduction, i. 373;</p> + <p class="i2">peculiar to plants, i. 374;</p> + <p class="i2">in the peach, i. 340, 374;</p> + <p class="i2">in plums, i. 375;</p> + <p class="i2">in the cherry, <i>ibid.</i>;</p> + <p class="i2">in grapes, <i>ibid.</i>;</p> + <p class="i2">in the gooseberry, currant, pear, and apple, i. 376;</p> + <p class="i2">in the banana, camellia, hawthorn, <i>Azalea indica</i>, and <i>Cistus tricuspis</i>, i. 377;</p> + <p class="i2">in the hollyhock and pelargonium, i. 378;</p> + <p class="i2">in <i>Geranium pratense</i> and the chrysanthemum, i. 379;</p> + <p class="i2">in roses, i. 367, 379-381;</p> + <p class="i2">in sweet williams, carnations, pinks, stocks, and snapdragons, i. 381;</p> + <p class="i2">in wall-flowers, cyclamen, <i>Œnothera biennis</i>, <i>Gladiolus colvillii</i>, fuchsias, and <i>Mirabilis jalapa</i>, i. 382;</p> + <p class="i2">in foliage of various trees, i. 382-384;</p> + <p class="i2">in cryptogamic plants, i. 383;</p> + <p class="i2">by suckers in <i>Phlox</i> and barberry, i. 384;</p> + <p class="i2">by tubers in the potato, <i>ibid.</i>;</p> + <p class="i2">in the dahlia, i. 385;</p> + <p class="i2">by bulbs in hyacinths, <i>Imatophyllum miniatum</i>, and tulips, i. 385;</p> + <p class="i2">in <i>Tigridia conchiflora</i>, i. 386;</p> +<!-- Page 440 --><span class="pagenum"><a name="page440"></a>{440}</span> + <p class="i2">in <i>Hemerocallis</i>, <i>ibid.</i>;</p> + <p class="i2">doubtful cases, i. 386-387;</p> + <p class="i2">in <i>Cytisus Adami</i>, i. 387-394;</p> + <p class="i2">probable in <i>Æsculus rubicunda</i>, i. 392;</p> + <p class="i2">summary of observations on, 406.</p> + <p><span class="sc">Buffon</span>, on crossing the wolf and dog, i. 32;</p> + <p class="i2">increase of fertility by domestication, ii. <a href="#page111">111</a>;</p> + <p class="i2">improvement of plants by unconscious selection, ii. <a href="#page216">216</a>;</p> + <p class="i2">theory of reproduction, ii. <a href="#page375">375</a>.</p> + <p><i>Bulimus</i>, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Bull</span>, apparent influence of, on offspring, ii. <a href="#page68">68</a>.</p> + <p><span class="sc">Bullace</span>, i. 345.</p> + <p><span class="sc">Bulldog</span>, recent modifications of, i. 42.</p> + <p><span class="sc">Bullfinch</span>, breeding in captivity, ii. <a href="#page154">154</a>;</p> + <p class="i2">attacking flower-buds, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Bult</span>, Mr., selection of pouter pigeons, ii. <a href="#page197">197</a>.</p> + <p>"<span class="sc">Bündtnerschwein</span>," i. 67.</p> + <p><span class="sc">Bunting</span>, reed, in captivity, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Burdach</span>, crossing of domestic and wild animals, i. 66;</p> + <p class="i2">aversion of the wild boar to barley, ii. <a href="#page303">303</a>.</p> + <p><span class="sc">Burke</span>, Mr., inheritance in the horse, ii. <a href="#page10">10</a>.</p> + <p><i>Burlingtonia</i>, ii. <a href="#page135">135</a>.</p> + <p><span class="sc">Burmah</span>, cats of, i. 47.</p> + <p><span class="sc">Burmese</span> ponies, striped, i. 58, 59.</p> + <p><span class="sc">Burnes</span>, Sir A., on the Karakool sheep, i. 98, ii. <a href="#page278">278</a>;</p> + <p class="i2">varieties of the vine in Cabool, i. 333;</p> + <p class="i2">hawks, trained in Scinde, ii. <a href="#page153">153</a>;</p> + <p class="i2">pomegranates producing seed, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Burton</span> Constable, wild cattle at, i. 84.</p> + <p>"<span class="sc">Burzel-Tauben</span>," i. 150.</p> + <p><span class="sc">Bussorah</span> carrier, i. 141.</p> + <p><i>Buteo vulgaris</i>, copulation of, in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Butterflies</span>, polymorphic, ii. <a href="#page399">399</a>-<a href="#page400">400</a>.</p> + <p><span class="sc">Buzareingues</span>, Girou de, inheritance of tricks, ii. <a href="#page6">6</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Cabanis</span>, pears grafted on the quince, ii. <a href="#page239">239</a>.</p> + <p><span class="sc">Cabbage</span>, i. 323-326;</p> + <p class="i2">varieties of, i. 323;</p> + <p class="i2">unity of character in flowers and seeds of, i. 323-324;</p> + <p class="i2">cultivated by ancient Celts, i. 324;</p> + <p class="i2">classification of varieties of, <i>ibid.</i>;</p> + <p class="i2">ready crossing of, <i>ibid.</i>, ii. <a href="#page90">90</a>, <a href="#page91">91</a>, <a href="#page98">98</a>, <a href="#page130">130</a>;</p> + <p class="i2">origin of, i. 325;</p> + <p class="i2">increased fertility of, when cultivated, ii. <a href="#page113">113</a>;</p> + <p class="i2">growth of, in tropical countries, ii. <a href="#page277">277</a>.</p> + <p><span class="sc">Cabool</span>, vines of, i. 333.</p> + <p><span class="sc">Cabral</span>, on early cultivation in Brazil, i. 311.</p> + <p><span class="sc">Cactus</span>, growth of cochineal on, in India, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Cæsar</span>, <i>Bos primigenius</i> wild in Europe in the time of, i. 81;</p> + <p class="i2">notice of fowls in Britain, i. 246;</p> + <p class="i2">notice of the importation of horses by the Celts, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Caffre</span> fowls, i. 230.</p> + <p><span class="sc">Caffres</span>, different kinds of cattle possessed by the, i. 88.</p> + <p>"<span class="sc">Cágias</span>," a breed of sheep, i. 95.</p> + <p><span class="sc">Calceolarias</span>, i. 364; ii. <a href="#page147">147</a>;</p> + <p class="i2">effects of seasonal conditions on, ii. <a href="#page274">274</a>;</p> + <p class="i2">peloric flowers in, ii. <a href="#page346">346</a>.</p> + <p>"<span class="sc">Calongos</span>," a Columbian breed of cattle, i. 88.</p> + <p><span class="sc">Calver</span>, Mr., on a seedling peach producing both peaches and nectarines, i. 341.</p> + <p><span class="sc">Calyx</span>, segments of the, converted into carpels, ii. <a href="#page392">392</a>.</p> + <p><span class="sc">Camel</span>, its dislike to crossing water, i. 181.</p> + <p><i>Camellia</i>, bud-variations in, i. 377;</p> + <p class="i2">recognition of varieties of, ii. <a href="#page251">251</a>;</p> + <p class="i2">variety in, hardiness of, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Cameron, D.</span>, on the cultivation of Alpine plants, ii. <a href="#page163">163</a>.</p> + <p><span class="sc">Cameronn</span>, Baron, value of English blood in race-horses, ii. <a href="#page11">11</a>.</p> + <p><i>Campanula medium</i>, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Canary-bird</span>, i. 295;</p> + <p class="i2">conditions of inheritance in, ii. <a href="#page22">22</a>;</p> + <p class="i2">hybrids of, ii. <a href="#page45">45</a>;</p> + <p class="i2">period of perfect plumage in, ii. <a href="#page77">77</a>;</p> + <p class="i2">diminished fertility of, ii. <a href="#page161">161</a>;</p> + <p class="i2">standard of perfection in, ii. <a href="#page195">195</a>;</p> + <p class="i2">analogous variation in, ii. <a href="#page349">349</a>.</p> + <p><span class="sc">Cancer</span>, heredity of, ii. <a href="#page7">7</a>, <a href="#page8">8</a>, <a href="#page79">79</a>.</p> + <p><span class="sc">Canine</span> teeth, development of the, in mares, ii. <a href="#page318">318</a>.</p> + <p><i>Canis alopex</i>, i. 29.</p> + <p><i>Canis antarcticus</i>, i. 20.</p> + <p><i>Canis argentatus</i>, ii. <a href="#page151">151</a>.</p> + <p><i>Canis aureus</i>, i. 29.</p> + <p><i>Canis cancrivorus</i>, domesticated and crossed in Guiana, i. 23.</p> + <p><i>Canis cinereo-variegatus</i>, i. 29.</p> + <p><i>Canis fulvus</i>, i. 29.</p> + <p><i>Canis Ingæ</i>, the naked Peruvian dog, i. 23.</p> + <p><i>Canis latrans</i>, resemblance of, to the Hare Indian dog, i. 22;</p> + <p class="i2">one of the original stocks, i. 26.</p> + <p><i>Canis lupaster</i>, i. 25.</p> + <p><i>Canis lupus</i>, var. <i>occidentalis</i>, resemblance of, to North American dogs, i. 21;</p> + <p class="i2">crossed with dogs, i. 22;</p> + <p class="i2">one of the original stocks, i. 26.</p> + <p><i>Canis mesomelas</i>, i. 25, 29.</p> + <p><i>Canis primævus</i>, tamed by Mr. Hodgson, i. 26.</p> + <p><i>Canis sabbar</i>, i. 25.</p> + <p><i>Canis simensis</i>, possible original of greyhounds, i. 33.</p> + <p><i>Canis thaleb</i>, i. 29.</p> + <p><i>Canis variegatus</i>, i. 29.</p> + <p><span class="sc">Canterbury</span> Bell, doubled by selection, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Cape</span> of Good Hope, different kinds of cattle at the, i. 88;</p> +<!-- Page 441 --><span class="pagenum"><a name="page441"></a>{441}</span> + <p class="i2">no useful plants derived from the, i. 310.</p> + <p><span class="sc">Capercailzie</span>, breeding in captivity, ii. <a href="#page156">156</a>.</p> + <p><i>Capra ægagrus</i> and <i>C. Falconeri</i>, probable parents of domestic goat, i. 101.</p> + <p><span class="sc">Capsicum</span>, i. 371.</p> + <p><span class="sc">Cardan</span>, on a variety of the walnut, i. 356;</p> + <p class="i2">on grafted walnuts, ii. <a href="#page259">259</a>-<a href="#page260">260</a>.</p> + <p><span class="sc">Cardoon</span>, ii. <a href="#page34">34</a>.</p> + <p><i>Carex rigida</i>, local sterility of the, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Carlier</span>, early selection of sheep, ii. <a href="#page204">204</a>.</p> + <p><span class="sc">Carlisle</span>, Sir A., inheritance of peculiarities, ii. <a href="#page6">6</a>, <a href="#page8">8</a>;</p> + <p class="i2">of polydactylism, ii. <a href="#page13">13</a>.</p> + <p>"<span class="sc">Carme</span>" pigeon, i. 156.</p> + <p><span class="sc">Carnation</span>, bud-variation in, i. 381;</p> + <p class="i2">variability of, i. 370;</p> + <p class="i2">striped, produced by crossing red and white, i. 393;</p> + <p class="i2">effect of conditions of life on the, ii. <a href="#page273">273</a>.</p> + <p><span class="sc">Carnivora</span>, general fertility of, in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Caroline</span> Archipelago, cats of, i. 47.</p> + <p><span class="sc">Carp</span>, ii. <a href="#page236">236</a>.</p> + <p><span class="sc">Carpels</span>, variation of, in cultivated cucurbitaceæ, i. 359.</p> + <p><span class="sc">Carpenter, W. B.</span>, regeneration of bone, ii. <a href="#page294">294</a>;</p> + <p class="i2">production of double monsters, ii. <a href="#page340">340</a>;</p> + <p class="i2">number of eggs in an <i>Ascaris</i>, ii. <a href="#page379">379</a>.</p> + <p><i>Carpinus betulus</i>, i. 362.</p> + <p><i>Carpophaga littoralis</i> and <i>luctuosa</i>, i. 182.</p> + <p><span class="sc">Carrier</span> pigeon, i. 139-142;</p> + <p class="i2">English, i. 139-141;</p> + <p class="i2">figured, i. 140;</p> + <p class="i2">skull figured, i. 163;</p> + <p class="i2">history of the, i. 211;</p> + <p class="i2">Persian, i. 141;</p> + <p class="i2">Bussorah, <i>ibid.</i>;</p> + <p class="i2">Bagadotten, skull figured, i. 163;</p> + <p class="i2">lower jaw figured, i. 165.</p> + <p><span class="sc">Carrière</span>, cultivation of the wild carrot, i. 326;</p> + <p class="i2">intermediate form between the almond and the peach, i. 338;</p> + <p class="i2">glands of peach-leaves, i. 343;</p> + <p class="i2">bud-variation in the vine, i. 375;</p> + <p class="i2">grafts of <i>Aria vestita</i> upon thorns, i. 387;</p> + <p class="i2">variability of hybrids of <i>Erythrina</i>, ii. <a href="#page265">265</a>.</p> + <p><span class="sc">Carrot</span>, wild, effects of cultivation on the, i. 326;</p> + <p class="i2">reversion in the, ii. <a href="#page31">31</a>;</p> + <p class="i2">run wild, ii. <a href="#page33">33</a>;</p> + <p class="i2">increased fertility of cultivated, ii. <a href="#page113">113</a>;</p> + <p class="i2">experiments on the, ii. <a href="#page277">277</a>;</p> + <p class="i2">acclimatisation of the, in India, ii. <a href="#page311">311</a>.</p> + <p><i>Carthamus</i>, abortion of the pappus in, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Cartier</span>, cultivation of native plants in Canada, i. 312.</p> + <p><span class="sc">Caryophyllaceæ</span>, frequency of contabescence in the, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Caspary</span>, bud-variation in the moss-rose, i. 380;</p> + <p class="i2">on the ovules and pollen of <i>Cytisus</i>, i. 388-389;</p> + <p class="i2">crossing of <i>Cytisus purpureus</i> and <i>C. laburnum</i>, i. 389;</p> + <p class="i2">trifacial orange, i. 391;</p> + <p class="i2">differently-coloured flowers in the wild <i>Viola lutea,</i> i. 408;</p> + <p class="i2">sterility of the horse-radish, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Castelnau</span>, on Brazilian cattle, i. 88.</p> + <p><span class="sc">Castration</span>, assumption of female characters caused by, ii. <a href="#page51">51</a>-<a href="#page52">52</a>.</p> + <p><i>Casuarius bennettii</i>, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Cat</span>, domestic, i. 43-48;</p> + <p class="i2">early domestication and probable origin of the, i. 43-44;</p> + <p class="i2">intercrossing of with wild species, i. 44-45;</p> + <p class="i2">variations of, i. 45-48;</p> + <p class="i2">feral, i. 47, ii. <a href="#page33">33</a>;</p> + <p class="i2">anomalous, i. 48;</p> + <p class="i2">polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">black, indications of stripes in young, ii. <a href="#page55">55</a>;</p> + <p class="i2">tortoiseshell, ii. <a href="#page73">73</a>;</p> + <p class="i2">effects of crossing in, ii. <a href="#page86">86</a>;</p> + <p class="i2">fertility of, ii. <a href="#page111">111</a>;</p> + <p class="i2">difficulty of selection in, ii. <a href="#page234">234</a>, <a href="#page236">236</a>;</p> + <p class="i2">length of intestines in, ii. <a href="#page302">302</a>;</p> + <p class="i2">white with blue eyes, deafness of, ii. <a href="#page329">329</a>;</p> + <p class="i2">with tufted ears, ii. <a href="#page350">350</a>.</p> + <p><span class="sc">Cataract</span>, hereditary, ii. <a href="#page9">9</a>, <a href="#page79">79</a>.</p> + <p><span class="sc">Caterpillars</span>, effect of changed food on, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Catlin, G.</span>, colour of feral horses in North America, i. 61.</p> + <p><span class="sc">Cattle</span>, European, their probable origin from three original species, i. 79-82;</p> + <p class="i2">humped, or Zebus, i. 79-80;</p> + <p class="i2">intercrossing of, i. 83, 91-93;</p> + <p class="i2">wild, of Chillingham, Hamilton, Chartley, Burton Constable, and Gisburne, i. 84, ii. <a href="#page119">119</a>;</p> + <p class="i2">colour of feral, i. 84-85, ii. <a href="#page102">102</a>;</p> + <p class="i2">British breeds of, i. 86-87;</p> + <p class="i2">South African breeds of, i. 88;</p> + <p class="i2">South American breeds of, i. 89, ii. <a href="#page205">205</a>;</p> + <p class="i2">Niata, i. 89-91, ii. <a href="#page205">205</a>, <a href="#page208">208</a>, <a href="#page332">332</a>;</p> + <p class="i2">effects of food and climate on, i. 91-92;</p> + <p class="i2">effects of selection on, i. 92-93;</p> + <p class="i2">Dutch-buttocked, ii. <a href="#page8">8</a>;</p> + <p class="i2">hornless, production of horns in, ii. <a href="#page29">29</a>-<a href="#page30">30</a>, <a href="#page39">39</a>;</p> + <p class="i2">reversion in, when crossed, ii. <a href="#page41">41</a>;</p> + <p class="i2">wildness of hybrid, ii. <a href="#page45">45</a>;</p> + <p class="i2">short-horned, prepotency of, ii. <a href="#page65">65</a>;</p> + <p class="i2">wild, influence of crossing and segregation on, ii. <a href="#page86">86</a>;</p> + <p class="i2">crosses of, ii. <a href="#page96">96</a>, <a href="#page104">104</a>, <a href="#page118">118</a>;</p> + <p class="i2">of Falkland islands, ii. <a href="#page102">102</a>;</p> + <p class="i2">mutual fertility of all varieties of, ii. <a href="#page110">110</a>;</p> + <p class="i2">effects of interbreeding on, ii. <a href="#page117">117</a>-<a href="#page119">119</a>;</p> + <p class="i2">effects of careful selection on, ii. <a href="#page194">194</a>, <a href="#page199">199</a>;</p> + <p class="i2">naked, of Columbia, ii. <a href="#page205">205</a>;</p> + <p class="i2">crossed with wild banteng in Java, ii. <a href="#page206">206</a>;</p> + <p class="i2">with reversed hair in Banda Oriental, ii. <a href="#page205">205</a>;</p> + <p class="i2">selection of trifling characters in, ii. <a href="#page209">209</a>;</p> + <p class="i2">fashion in, ii. <a href="#page210">210</a>;</p> + <p class="i2">similarity of best races of, ii. <a href="#page241">241</a>;</p> + <p class="i2">unconscious selection in, ii. <a href="#page214">214</a>;</p> + <p class="i2">effects of natural selection on anomalous breeds of, ii. <a href="#page226">226</a>-<a href="#page227">227</a>;</p> + <p class="i2">light-coloured, attacked by flies, ii. <a href="#page229">229</a>, <a href="#page336">336</a>;</p> + <p class="i2">Jersey, rapid improvement of, ii. <a href="#page234">234</a>;</p> + <p class="i2">effects of disuse of parts in, ii. <a href="#page299">299</a>;</p> + <p class="i2">rudimentary horns in, ii. <a href="#page315">315</a>;</p> + <p class="i2">supposed influence of humidity on the hair of, ii. <a href="#page326">326</a>;</p> +<!-- Page 442 --><span class="pagenum"><a name="page442"></a>{442}</span> + <p class="i2">white spots of, liable to disease, ii. <a href="#page337">337</a>;</p> + <p class="i2">supposed analogous variation in, ii. <a href="#page349">349</a>;</p> + <p class="i2">displacement of long-horned by short-horned, ii. <a href="#page426">426</a>.</p> + <p><span class="sc">Cauliflower</span>, i. 323;</p> + <p class="i2">free-seeding of, in India, ii. <a href="#page310">310</a>;</p> + <p class="i2">rudimentary flowers in, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Cavalier</span> pigeon, ii. <a href="#page97">97</a>.</p> + <p><i>Cavia aperea</i>, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Cay</span> (<i>Cebus azaræ</i>), sterility of, in confinement, ii. <a href="#page153">153</a>.</p> + <p><i>Cebus azaræ</i>, ii. <a href="#page153">153</a>.</p> + <p><i>Cecidomyia</i>, larval development of, ii. <a href="#page283">283</a>, <a href="#page360">360</a>, <a href="#page367">367</a>;</p> + <p class="i2">and <i>Misocampus</i>, i. 5.</p> + <p><span class="sc">Cedars</span> of Lebanon and Atlas, i. 364.</p> + <p><span class="sc">Celery</span>, turnip-rooted, i. 336;</p> + <p class="i2">run wild, ii. <a href="#page33">33</a>.</p> + <p><span class="sc">Cell-theory</span>, ii. <a href="#page370">370</a>.</p> + <p><i>Celosia cristata</i>, i. 365.</p> + <p><span class="sc">Celsus</span>, on the selection of seed-corn, i. 318, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Celts</span>, early cultivation of the cabbage by the, i. 324;</p> + <p class="i2">selection of cattle and horses by the, ii. <a href="#page202">202</a>-<a href="#page203">203</a>.</p> + <p><i>Cenchrus</i>, seeds of a, used as food, i. 309.</p> + <p><i>Centaurea cyanus</i>, bud-variation in, i. 379.</p> + <p><span class="sc">Cephalopoda</span>, spermatophores of, ii. <a href="#page383">383</a>.</p> + <p><i>Cerasus padus</i>, yellow-fruited, ii. <a href="#page19">19</a>.</p> + <p><i>Cercoleptes</i>, sterility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><i>Cercopithecus</i>, breeding of a species of, in captivity, ii. <a href="#page153">153</a>.</p> + <p><span class="sc">Cereals</span>, i. 312-313;</p> + <p class="i2">of the Neolithic period in Switzerland, i. 317;</p> + <p class="i2">adaptation of, to soils, ii. <a href="#page305">305</a>.</p> + <p><i>Cereus</i>, ii. <a href="#page38">38</a>.</p> + <p><i>Cereus speciosissimus</i> and <i>phyllanthus</i>, reversion in hybrids of, i. 392.</p> + <p><i>Cervus canadensis</i>, ii. <a href="#page158">158</a>.</p> + <p><i>Cervus dama</i>, ii. <a href="#page120">120</a>.</p> + <p><span class="sc">Cetacea</span>, correlation of dermal system and teeth in the, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Ceylon</span>, cats of, i. 46;</p> + <p class="i2">pigeon-fancying in, i. 206.</p> + <p><i>Chamærops humilis</i>, crossed with date palm, i. 399.</p> + <p><span class="sc">Chamisso</span>, on seeding bread-fruit, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Channel</span> islands, breeds of cattle in, i. 80.</p> + <p><span class="sc">Chapman</span>, Professor, peach-trees producing nectarines, i. 341.</p> + <p><span class="sc">Chapuis, F.</span>, sexual peculiarities in pigeons, i. 162, ii. <a href="#page74">74</a>;</p> + <p class="i2">effect produced by first male upon the subsequent progeny of the female, i. 405;</p> + <p class="i2">sterility of the union of some pigeons, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Characters</span>, fixity of, ii. <a href="#page239">239</a>;</p> + <p class="i2">latent, ii. <a href="#page51">51</a>-<a href="#page56">56</a>, <a href="#page399">399</a>-<a href="#page400">400</a>;</p> + <p class="i2">continued divergence of, ii. <a href="#page241">241</a>;</p> + <p class="i2">antagonistic, ii. <a href="#page401">401</a>.</p> + <p><span class="sc">Chardin</span>, abundance of pigeons in Persia, i. 205.</p> + <p><span class="sc">Charlemagne</span>, orders as to the selection of stallions, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Chartley</span>, wild cattle of, i. 84.</p> + <p><span class="sc">Chaté</span>, reversion of the upper seeds in the pods of stocks, ii. <a href="#page347">347</a>-<a href="#page348">348</a>.</p> + <p><span class="sc">Chatin</span>, on <i>Ranunculus ficaria</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Chaundy</span>, Mr., crossed varieties of cabbage, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Cheetah</span>, general sterility of, in captivity, ii. <a href="#page151">151</a>.</p> + <p><i>Cheiranthus cheiri</i>, i. 382.</p> + <p><span class="sc">Cherries</span>, i. 347-348;</p> + <p class="i2">bud-variation in, i. 375;</p> + <p class="i2">white Tartarian, ii. <a href="#page230">230</a>;</p> + <p class="i2">variety of, with curled petals, ii. <a href="#page232">232</a>;</p> + <p class="i2">period of vegetation of, changed by forcing, ii. <a href="#page311">311</a>.</p> + <p><span class="sc">Chevreul</span>, on crossing fruit-trees, ii. <a href="#page129">129</a>.</p> + <p><span class="sc">Chickens</span>, differences in characters of, i. 249-250;</p> + <p class="i2">white, liable to gapes, ii. <a href="#page228">228</a>, <a href="#page336">336</a>.</p> + <p><span class="sc">Chigoe</span>, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Chile</span>, sheep of, i. 95.</p> + <p><span class="sc">Chillingham</span> cattle, identical with <i>Bos primigenius</i>, i. 81;</p> + <p class="i2">characters of, i. 83-84.</p> + <p><span class="sc">Chiloe</span>, half-castes of, ii. <a href="#page46">46</a>.</p> + <p><span class="sc">China</span>, cats of, with drooping ears, i. 47;</p> + <p class="i2">horses of, i. 53;</p> + <p class="i2">striped ponies of, i. 59;</p> + <p class="i2">asses of, i. 62;</p> + <p class="i2">notice of rabbits in, by Confucius, i. 103;</p> + <p class="i2">breeds of pigeons reared in, i. 206;</p> + <p class="i2">breeds of fowls of, in fifteenth century, i. 232, 247;</p> + <p class="i2">goose of, i. 237.</p> + <p><span class="sc">Chinchilla</span>, fertility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Chinese</span>, selection practised by the, ii. <a href="#page204">204</a>-<a href="#page205">205</a>;</p> + <p class="i2">preference of the, for hornless rams, ii. <a href="#page209">209</a>;</p> + <p class="i2">recognition of the value of native breeds by the, ii. <a href="#page313">313</a>.</p> + <p><span class="sc">Chinese</span>, or Himalayan rabbit, i. 108.</p> + <p>"<span class="sc">Chivos</span>," a breed of cattle in Paraguay, i. 89.</p> + <p><span class="sc">Choux-raves</span>, i. 323.</p> + <p><span class="sc">Christ, H.</span>, on the plants of the Swiss Lake-dwellings, i. 309, 318;</p> + <p class="i2">intermediate forms between <i>Pinus sylvestris</i> and <i>montana</i>, i. 363.</p> + <p><span class="sc">Chrysanthemum</span>, i. 379.</p> + <p><i>Chrysotis festiva</i>, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Cineraria</span>, effects of selection on the, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Circassia</span>, horses of, ii. <a href="#page102">102</a>.</p> + <p><span class="sc">Circumcision</span>, ii. <a href="#page23">23</a>.</p> + <p><span class="sc">Cirripedes</span>, metagenesis in, ii. <a href="#page366">366</a>.</p> + <p><i>Cistus</i>, intercrossing and hybrids of, i. 336, 389, ii. <a href="#page140">140</a>.</p> + <p><i>Cistus tricuspis</i>, bud-variation in, i. 377.</p> + <p><span class="sc">Citrons</span>, i. 334-335.</p> + <p>"<i>Citrus aurantium fructu variabili</i>," i. 336.</p> + <p><i>Citrus decumana</i>, i. 335.</p> + <p><i>Citrus lemonum</i>, i. 336.</p> +<!-- Page 443 --><span class="pagenum"><a name="page443"></a>{443}</span> + <p><i>Citrus medica</i>, i. 335-336.</p> + <p><span class="sc">Cleft</span> palate, inheritance of, ii. <a href="#page24">24</a>.</p> + <p><span class="sc">Clemente</span>, on wild vines in Spain, i. 332.</p> + <p><span class="sc">Clermont-Tonnerre</span>, on the St. Valery apple, i. 401.</p> + <p><span class="sc">Clapham, A.</span>, bud-variation in the hawthorn, i. 377.</p> + <p>"<span class="sc">Claquant</span>," i. 138.</p> + <p>"<span class="sc">Claquers</span>" (pigeons), i. 156.</p> + <p><span class="sc">Clark, G.</span>, on the wild dogs of Juan de Nova, i. 27;</p> + <p class="i2">on striped Burmese and Javanese ponies, i. 59;</p> + <p class="i2">breeds of goats imported into the Mauritius, i. 101;</p> + <p class="i2">variations in the mammæ of goats, i. 102;</p> + <p class="i2">bilobed scrotum of Muscat goat, <i>ibid.</i></p> + <p><span class="sc">Clark, H. J.</span>, on fission and gemmation, ii. <a href="#page359">359</a>.</p> + <p><span class="sc">Clarke, R. T.</span>, intercrossing of strawberries, i. 352.</p> + <p><span class="sc">Clarke, T.</span>, hybridisation of stocks, i. 399, ii. <a href="#page93">93</a>.</p> + <p><span class="sc">Clarkson</span>, Mr., prize-cultivation of the gooseberry, i. 355.</p> + <p><span class="sc">Classification</span>, explained by the theory of natural selection, i. 11.</p> + <p><span class="sc">Climate</span>, effect of, upon breeds of dogs, i. 37;</p> + <p class="i2">on horses, i. 52, 53;</p> + <p class="i2">on cattle, i. 91, 92;</p> + <p class="i2">on the fleece of sheep, i. 98, 99;</p> + <p class="i2">on seeds of wheat, i. 316;</p> + <p class="i2">on cultivated cabbages, i. 325;</p> + <p class="i2">adaptation of maize to, i. 322.</p> + <p><span class="sc">Climate</span> and pasture, adaptation of breeds of sheep to, i. 96-97.</p> + <p><span class="sc">Climate</span> and soil, effects of, upon strawberries, i. 353.</p> + <p><span class="sc">Cline</span>, Mr., on the skull in horned and hornless rams, ii. <a href="#page333">333</a>.</p> + <p><span class="sc">Clos</span>, on sterility in <i>Ranunculus ficaria</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Clotzsch</span>, hybrids of various trees, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Clover</span>, pelorism in, ii. <a href="#page340">340</a>.</p> + <p><span class="sc">Coate</span>, Mr., on interbreeding pigs, ii. <a href="#page122">122</a>.</p> + <p><span class="sc">Coccus</span> of apple trees, ii. <a href="#page231">231</a>.</p> + <p><span class="sc">Cochin</span> fowls, i. 227, 250, 252, 260-261;</p> + <p class="i2">occipital foramen of, figured, i. 261;</p> + <p class="i2">section of skull of, figured, i. 263;</p> + <p class="i2">cervical vertebra of, figured, i. 267.</p> + <p><span class="sc">Cochineal</span>, persistence of, ii. <a href="#page236">236</a>;</p> + <p class="i2">preference of, for a particular cactus, ii. <a href="#page275">275</a>.</p> + <p><i>Cochlearia armoracia</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Cock</span>, game, natural selection in, ii. <a href="#page225">225</a>;</p> + <p class="i2">spur of, grafted on the comb, ii. <a href="#page296">296</a>;</p> + <p class="i2">spur of, inserted into the eye of an ox, ii. <a href="#page369">369</a>;</p> + <p class="i2">effect of castration upon the, ii. <a href="#page51">51</a>-<a href="#page52">52</a>.</p> + <p><span class="sc">Cock's-comb</span>, varieties of the, i. 365.</p> + <p><span class="sc">Cocoons</span>, of silkworms, variations in, i. 302-303.</p> + <p><span class="sc">Codfish</span>, bulldog, i. 89;</p> + <p class="i2">number of eggs in the, ii. <a href="#page379">379</a>.</p> + <p><i>Cœlogenys paca</i>, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Colin</span>, prepotency of the ass over the horse, ii. <a href="#page67">67</a>-<a href="#page68">68</a>;</p> + <p class="i2">on cross-breeding, ii. <a href="#page97">97</a>;</p> + <p class="i2">on change of diet, ii. <a href="#page304">304</a>.</p> + <p><span class="sc">Collinson</span>, Peter, peach-tree producing a nectarine, i. 340.</p> + <p><span class="sc">Coloration</span>, in pigeons, an evidence of unity of descent, i. 195-197.</p> + <p><span class="sc">Colour</span>, correlation of, in dogs, i. 28-29;</p> + <p class="i2">persistence of, in horses, i. 50;</p> + <p class="i2">inheritance and diversity of, in horses, i. 55;</p> + <p class="i2">variations of, in the ass, i. 62-63;</p> + <p class="i2">of wild or feral cattle, i. 85;</p> + <p class="i2">transmission of, in rabbits, i. 107;</p> + <p class="i2">peculiarities of, in Himalayan rabbits, i. 111;</p> + <p class="i2">influence of, ii. <a href="#page227">227</a>-<a href="#page230">230</a>;</p> + <p class="i2">correlation of, in head and limbs, ii. <a href="#page324">324</a>;</p> + <p class="i2">correlated with constitutional peculiarities, ii. <a href="#page335">335</a>-<a href="#page338">338</a>.</p> + <p><span class="sc">Colour</span> and odour, correlation of, ii. <a href="#page325">325</a>.</p> + <p><span class="sc">Colour-blindness</span>, hereditary, ii. <a href="#page9">9</a>;</p> + <p class="i2">more common in men than in women, ii. <a href="#page72">72</a>-<a href="#page73">73</a>;</p> + <p class="i2">associated with inability to distinguish musical sounds, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Colours</span>, sometimes not blended by crossing, ii. <a href="#page92">92</a>.</p> + <p><i>Columba affinis</i>, Blyth, a variety of <i>C. livia</i>, i. 183.</p> + <p><i>Columba amaliæ</i>, Brehm, a variety of <i>C. livia</i>, i. 183.</p> + <p><i>Columba guinea</i>, i. 182.</p> + <p><i>Columba gymnocyclus</i>, Gray, a form of <i>C. livia</i>, i. 184.</p> + <p><i>Columba gymnophthalmos</i>, hybrids of, with <i>C. œnas</i>, i. 193;</p> + <p class="i2">with <i>C. maculosa</i>, i. 194.</p> + <p><i>Columba intermedia</i>, Strickland, a variety of <i>C. livia</i>, i. 184.</p> + <p><i>Columba leucocephala</i>, ii. <a href="#page155">155</a>.</p> + <p><i>Columba leuconota</i>, i. 182, 195.</p> + <p><i>Columba littoralis</i>, i. 182.</p> + <p><i>Columba livia</i>, ii. <a href="#page29">29</a>, <a href="#page40">40</a>;</p> + <p class="i2">the parent of domestic breeds of pigeons, i. 183;</p> + <p class="i2">measurements of, i. 134;</p> + <p class="i2">figured, i. 135;</p> + <p class="i2">skull figured, i. 163;</p> + <p class="i2">lower jaw figured, i. 164, 168;</p> + <p class="i2">scapula figured, i. 167.</p> + <p><i>Columba luctuosa</i>, i. 182.</p> + <p><i>Columba migratoria</i> and <i>leucocephala</i>, diminished fertility of, in captivity, ii. <a href="#page155">155</a>.</p> + <p><i>Columba œnas</i>, i. 183;</p> + <p class="i2">crossed with common pigeon and <i>C. gymnophthalmos</i>, i. 193.</p> + <p><i>Columba palumbus</i>, i. 193, ii. <a href="#page350">350</a>.</p> + <p><i>Columba rupestris</i>, i. 182, 184, 195.</p> + <p><i>Columba Schimperi</i>, i. 184.</p> + <p><i>Columba torquatrix</i>, ii. <a href="#page350">350</a>.</p> + <p><i>Columba turricola</i>, i. 184.</p> + <p><span class="sc">Columbia</span>, cattle of, i. 88.</p> + <p><span class="sc">Columbine</span>, double, i. 365, ii. <a href="#page330">330</a>.</p> +<!-- Page 444 --><span class="pagenum"><a name="page444"></a>{444}</span> + <p><span class="sc">Columbus</span>, on West Indian dogs, i. 23.</p> + <p><span class="sc">Columella</span>, on Italian shepherd's dogs, i. 23;</p> + <p class="i2">on domestic fowls, i. 231, 247, ii. <a href="#page202">202</a>, <a href="#page429">429</a>;</p> + <p class="i2">on the keeping of ducks, i. 277;</p> + <p class="i2">on the selection of seed-corn, i. 318;</p> + <p class="i2">on the benefits of change of soil to plants, ii. <a href="#page146">146</a>;</p> + <p class="i2">on the value of native breeds, ii. <a href="#page313">313</a>.</p> + <p><span class="sc">Colza</span>, i. 325.</p> + <p><span class="sc">Comb</span>, in fowls, variations of, i. 253-254;</p> + <p class="i2">sometimes rudimentary, ii. <a href="#page315">315</a>.</p> + <p><span class="sc">Compensation</span>, law of, i. 274.</p> + <p><span class="sc">Compensation</span> of growth, ii. <a href="#page342">342</a>-<a href="#page344">344</a>.</p> + <p><span class="sc">Complexion</span>, connexion of, with constitution, ii. <a href="#page335">335</a>.</p> + <p><span class="sc">Compositæ</span>, double flowers of, i. 365, ii. <a href="#page167">167</a>, <a href="#page316">316</a>.</p> + <p><span class="sc">Conception</span>, earlier in Alderney and Zetland cows than in other breeds, i. 87.</p> + <p><span class="sc">Conditions</span> of life, changed, effect of, ii. <a href="#page418">418</a>-<a href="#page419">419</a>;</p> + <p class="i2">on horses, i. 52;</p> + <p class="i2">upon variation in pigeons, i. 212-213;</p> + <p class="i2">upon wheat, i. 315-316;</p> + <p class="i2">upon trees, i. 361;</p> + <p class="i2">in producing bud-variation, i. 408;</p> + <p class="i2">advantages of, ii. <a href="#page145">145</a>-<a href="#page148">148</a>, <a href="#page176">176</a>-<a href="#page177">177</a>;</p> + <p class="i2">sterility caused by, ii. <a href="#page148">148</a>-<a href="#page165">165</a>;</p> + <p class="i2">conducive to variability, ii. <a href="#page255">255</a>-<a href="#page261">261</a>, <a href="#page394">394</a>;</p> + <p class="i2">accumulative action of, ii. <a href="#page261">261</a>-<a href="#page263">263</a>;</p> + <p class="i2">direct action of, ii. <a href="#page271">271</a>-<a href="#page292">292</a>.</p> + <p><span class="sc">Condor</span>, breeding in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Confinement</span>, effect of, upon the cock, ii. <a href="#page52">52</a>.</p> + <p><span class="sc">Confucius</span>, on the breeding of rabbits in China, i. 103.</p> + <p><span class="sc">Conolly</span>, Mr., on Angora goats, ii. <a href="#page326">326</a>.</p> + <p><span class="sc">Constitutional</span> differences in sheep, i. 96-97;</p> + <p class="i2">in varieties of apples, i. 349-350;</p> + <p class="i2">in pelargoniums, i. 364;</p> + <p class="i2">in dahlias, i. 370.</p> + <p><span class="sc">Constitutional</span> peculiarities in strawberries, i. 353;</p> + <p class="i2">in roses, i. 367.</p> + <p><span class="sc">Consumption</span>, hereditary, ii. <a href="#page8">8</a>;</p> + <p class="i2">period of appearance of, ii. <a href="#page77">77</a>;</p> + <p class="i2">correlated with complexion, ii. <a href="#page335">335</a>.</p> + <p><span class="sc">Contabescence</span>, ii. <a href="#page165">165</a>-<a href="#page166">166</a>.</p> + <p><i>Convolvulus batatas</i>, ii. <a href="#page169">169</a>, <a href="#page309">309</a>.</p> + <p><i>Convolvulus tricolor</i>, bud-variation in, i. 408.</p> + <p><span class="sc">Cooper</span>, Mr., improvement of vegetables by selection, ii. <a href="#page204">204</a>.</p> + <p><span class="sc">Cooper</span>, White, hereditary peculiarities of vision, ii. <a href="#page9">9</a>;</p> + <p class="i2">association of affections of the eyes with those of other systems, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Corals</span>, bud-variation in, i. 374;</p> + <p class="i2">non-diffusion of cell-gemmules in, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Corbié</span>. <i>See</i> Boitard.</p> + <p><span class="sc">Cornea</span>, opacity of, inherited, ii. <a href="#page9">9</a>.</p> + <p><i>Cornus mascula</i>, yellow-fruited, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Correlation</span>, ii. <a href="#page319">319</a>;</p> + <p class="i2">of neighbouring parts, ii. <a href="#page320">320</a>;</p> + <p class="i2">of change in the whole body and in some of its parts, ii. <a href="#page321">321</a>;</p> + <p class="i2">of homologous parts, ii. <a href="#page322">322</a>-<a href="#page331">331</a>;</p> + <p class="i2">inexplicable, ii. <a href="#page331">331</a>-<a href="#page333">333</a>;</p> + <p class="i2">commingling of, with the effects of other agencies, ii. <a href="#page333">333</a>-<a href="#page335">335</a>.</p> + <p><span class="sc">Correlation</span> of skull and limbs in swine, i. 73;</p> + <p class="i2">of tusks and bristles in swine, i. 76;</p> + <p class="i2">of multiplicity of horns and coarseness of wool in sheep, i. 95;</p> + <p class="i2">of beak and feet in pigeons, i. 172-173;</p> + <p class="i2">between nestling down and colour of plumage in pigeons, i. 194;</p> + <p class="i2">of changes in silkworms, i. 304;</p> + <p class="i2">in plants, ii. <a href="#page219">219</a>;</p> + <p class="i2">in maize, i. 323;</p> + <p class="i2">in pigeons, i. 167-171, 218;</p> + <p class="i2">in fowls, i. 274-275.</p> + <p><span class="sc">Corresponding</span> periods, inheritance at, ii. <a href="#page75">75</a>-<a href="#page80">80</a>.</p> + <p><span class="sc">Corrientes</span>, dwarf cattle of, i. 89.</p> + <p><span class="sc">Corringham</span>, Mr., influence of selection on pigs, ii. <a href="#page198">198</a>.</p> + <p><span class="sc">Corsica</span>, ponies of, i. 52.</p> + <p>"<span class="sc">Cortbeck</span>" (pigeon) of Aldrovandi, i. 209.</p> + <p><i>Corvus corone</i> and <i>C. cornix</i>, hybrids of, ii. <a href="#page94">94</a>.</p> + <p><i>Corydalis</i>, flower of, ii. <a href="#page304">304</a>.</p> + <p><i>Corydalis cava</i>, ii. <a href="#page132">132</a>-<a href="#page133">133</a>.</p> + <p><i>Corydalis solida</i>, sterile when peloric, ii. <a href="#page167">167</a>.</p> + <p><i>Corydalis tuberosa</i>, peloric by reversion, ii. <a href="#page58">58</a>-<a href="#page59">59</a>.</p> + <p><i>Corylus avellana</i>, i. 357.</p> + <p><span class="sc">Costa, A.</span>, on shells transferred from England to the Mediterranean, ii. <a href="#page280">280</a>.</p> + <p>"<span class="sc">Couve Tronchuda</span>," i. 323.</p> + <p><span class="sc">Cow</span>, inheritance of loss of one horn in the, ii. <a href="#page12">12</a>, <a href="#page23">23</a>;</p> + <p class="i2">amount of milk furnished by the, ii. <a href="#page300">300</a>;</p> + <p class="i2">development of six mammæ in, ii. <a href="#page317">317</a>.</p> + <p><span class="sc">Cowslip</span>, ii. <a href="#page21">21</a>, <a href="#page182">182</a>.</p> + <p><span class="sc">Cracidæ</span>, sterility of the, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Cranes</span>, fertility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><i>Cratægus oxyacantha</i>, i. 363, ii. <a href="#page18">18</a>, <a href="#page232">232</a>, <a href="#page258">258</a>, <a href="#page377">377</a>.</p> + <p><i>Cratægus monogyna</i>, i. 364.</p> + <p><i>Cratægus sibirica</i>, i. 364.</p> + <p><span class="sc">Crawfurd, J.</span>, Malasian cats, i. 47;</p> + <p class="i2">horses of the Malay Archipelago, i. 49;</p> + <p class="i2">horses of Japan, i. 53;</p> + <p class="i2">occurrence of stripes in young wild pigs of Malacca, i. 76;</p> + <p class="i2">on a Burmese hairy family with deficient teeth, ii. <a href="#page77">77</a>, <a href="#page327">327</a>;</p> + <p class="i2">Japanese origin of the bantam, i. 230;</p> + <p class="i2">game fowls of the Philippine islands, i. 232;</p> + <p class="i2">hybrids of <i>Gallus varius</i> and domestic fowl, i. 234;</p> + <p class="i2">domestication of <i>Gallus bankiva</i>, i. 236;</p> + <p class="i2">feral fowls in the Pellew islands, i. 238;</p> + <p class="i2">history of the fowl, i. 246;</p> + <p class="i2">history of the domestic duck, i. 277;</p> + <p class="i2">domestication of the goose, i. 287;</p> + <p class="i2">cultivated plants of New Zealand, i. 312;</p> +<!-- Page 445 --><span class="pagenum"><a name="page445"></a>{445}</span> + <p class="i2">breeding of tame elephants in Ava, ii. <a href="#page150">150</a>;</p> + <p class="i2">sterility of <i>Goura coronata</i> in confinement, ii. <a href="#page155">155</a>;</p> + <p class="i2">geese of the Philippine islands, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Creepers</span>, a breed of fowls, i. 230.</p> + <p><span class="sc">Crested</span> fowl, i. 227;</p> + <p class="i2">figured, i. 229.</p> + <p>"<span class="sc">Crève-cœur</span>," a French sub-breed of fowls, i. 229.</p> + <p><span class="sc">Crisp</span>, Dr., on the brains of the hare and rabbit, i. 126.</p> + <p><span class="sc">Crocker, C. W.</span>, singular form of <i>Begonia frigida</i>, i. 365-366, ii. <a href="#page166">166</a>;</p> + <p class="i2">sterility in <i>Ranunculus ficaria</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Crocus</span>, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Cross-breeding</span>, permanent effect of, on the female, i. 404.</p> + <p><span class="sc">Crossing</span>, ii. <a href="#page85">85</a>-<a href="#page144">144</a>, <a href="#page173">173</a>-<a href="#page192">192</a>;</p> + <p class="i2">a cause of uniformity, ii. <a href="#page85">85</a>-<a href="#page90">90</a>, <a href="#page173">173</a>;</p> + <p class="i2">occurs in all organised beings, ii. <a href="#page90">90</a>-<a href="#page92">92</a>;</p> + <p class="i2">some characters not blended by, ii. <a href="#page92">92</a>-<a href="#page95">95</a>, <a href="#page173">173</a>;</p> + <p class="i2">modifications and new races produced by, ii. <a href="#page95">95</a>-<a href="#page99">99</a>;</p> + <p class="i2">causes which check, ii. <a href="#page100">100</a>-<a href="#page109">109</a>;</p> + <p class="i2">domestication and cultivation favourable to, ii. <a href="#page109">109</a>-<a href="#page113">113</a>, <a href="#page189">189</a>;</p> + <p class="i2">beneficial effects of, ii. <a href="#page114">114</a>-<a href="#page131">131</a>, <a href="#page174">174</a>-<a href="#page176">176</a>;</p> + <p class="i2">necessary in some plants, ii. <a href="#page131">131</a>-<a href="#page140">140</a>, <a href="#page175">175</a>-<a href="#page176">176</a>, <a href="#page423">423</a>;</p> + <p class="i2">summary of subject of, ii. <a href="#page140">140</a>-<a href="#page144">144</a>;</p> + <p class="i2">of dogs with wolves in North America, i. 21-22;</p> + <p class="i2">with <i>Canis cancrivorus</i> in Guiana, i. 23;</p> + <p class="i2">of dog with wolf, described by Pliny and others, i. 24;</p> + <p class="i2">characters furnished by, brought out by reversion in the progeny, ii. <a href="#page34">34</a>-<a href="#page36">36</a>;</p> + <p class="i2">a direct cause of reversion, ii. <a href="#page39">39</a>-<a href="#page47">47</a>, <a href="#page48">48</a>;</p> + <p class="i2">a cause of variability, ii. <a href="#page264">264</a>-<a href="#page267">267</a>.</p> + <p><span class="sc">Crustacea</span>, macrourous, differences in the development of the, ii. <a href="#page368">368</a>.</p> + <p><span class="sc">Crustacean</span> with an antenna-like development of the eye-peduncle, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Cryptogamic</span> plants, bud-variation in, i. 383.</p> + <p><span class="sc">Cuba</span>, wild dogs of, i. 27.</p> + <p>"<span class="sc">Cuckoo</span>," sub-breeds of fowls, i. 244.</p> + <p><span class="sc">Cucumber</span>, variation in number of carpels of, i. 359;</p> + <p class="i2">supposed crossing of varieties of the, i. 400.</p> + <p><i>Cucumis momordica</i>, i. 360.</p> + <p><i>Cucumis sativa</i>, i. 359.</p> + <p><i>Cucurbita</i>, dwarf, correlation of leaves in, ii. <a href="#page330">330</a>.</p> + <p><i>Cucurbita maxima</i>, i. 357, 359.</p> + <p><i>Cucurbita moschata</i>, i. 357, 359.</p> + <p><i>Cucurbita pepo</i>, i. 357, ii. <a href="#page108">108</a>;</p> + <p class="i2">varieties of, i. 358;</p> + <p class="i2">relation in size and number of fruit of, ii. <a href="#page343">343</a>.</p> + <p><span class="sc">Cucurbitaceæ</span>, i. 357-360;</p> + <p class="i2">supposed crossing of, i. 399;</p> + <p class="i2">Naudin's observations on hybrids of, ii. <a href="#page172">172</a>;</p> + <p class="i2">acclimatisation of, ii. <a href="#page313">313</a>.</p> + <p>"<span class="sc">Culbutants</span>" (pigeons), i. 150.</p> + <p><span class="sc">Cultivation</span> of plants, origin of, among savages, i. 309-310;</p> + <p class="i2">fertility increased by, ii. <a href="#page111">111</a>-<a href="#page113">113</a>.</p> + <p><span class="sc">Cunier</span>, on hereditary night-blindness, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">Currants</span>, of Tierra del Fuego, i. 309;</p> + <p class="i2">bud-variation in, i. 376.</p> + <p><span class="sc">Curtis</span>, Mr., bud-variation in the rose, i. 381.</p> + <p><span class="sc">Cuvier</span>, on the gestation of the wolf, i. 29;</p> + <p class="i2">the odour of the jackal, an obstacle to domestication, i. 30;</p> + <p class="i2">differences of the skull in dogs, i. 34;</p> + <p class="i2">external characters of dogs, i. 35;</p> + <p class="i2">elongation of the intestines in domestic pigs, i. 73, ii. <a href="#page303">303</a>;</p> + <p class="i2">fertility of the hook-billed duck, i. 277;</p> + <p class="i2">number of digits, ii. <a href="#page13">13</a>;</p> + <p class="i2">hybrid of ass and zebra, ii. <a href="#page42">42</a>;</p> + <p class="i2">breeding of animals in the Jardin des Plantes, ii. <a href="#page149">149</a>;</p> + <p class="i2">sterility of predaceous birds in captivity, ii. <a href="#page154">154</a>;</p> + <p class="i2">facility of hybridisation in confinement, ii. <a href="#page160">160</a>.</p> + <p><span class="sc">Cyanosis</span>, affection of fingers in, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Cyclamen</span>, bud-variation in, i. 382.</p> + <p><i>Cynara cardunculus</i>, ii. <a href="#page34">34</a>.</p> + <p><i>Cynips fecundatrix</i>, ii. <a href="#page283">283</a>.</p> + <p><i>Cynocephalus hamadryas</i>, ii. <a href="#page153">153</a>.</p> + <p><i>Cyprinus auratus</i>, i. 296-297.</p> + <p><i>Cyrtanthus</i>, ii. <a href="#page139">139</a>.</p> + <p><i>Cyrtopodium</i>, ii. <a href="#page134">134</a>.</p> + <p><i>Cytisus Adami</i>, ii. <a href="#page364">364</a>;</p> + <p class="i2">its bud-variation, i. 387-389, 406, ii. <a href="#page37">37</a>;</p> + <p class="i2">seedlings from, i. 388;</p> + <p class="i2">different views of its origin, i. 389-390;</p> + <p class="i2">experiments in crossing <i>C. purpureus</i> and <i>laburnum</i> to produce, i. 389;</p> + <p class="i2">its production by M. Adam, i. 390;</p> + <p class="i2">discussion of origin of, i. 396.</p> + <p><i>Cytisus alpino-laburnum</i>, ovules and pollen of, i. 389;</p> + <p class="i2">origin of, i. 390.</p> + <p><i>Cytisus alpinus</i>, i. 388.</p> + <p><i>Cytisus laburnum</i>, i. 387, 389, 390, 396.</p> + <p><i>Cytisus purpureo-elongatus</i>, ovules and pollen of, i. 389;</p> + <p class="i2">production of, i. 390.</p> + <p><i>Cytisus purpureus</i>, i. 387, 388, 389, 390, 396.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Dahlbom</span>, effects of food on hymenoptera, ii. <a href="#page281">281</a>.</p> + <p><span class="sc">Dahlia</span>, i. 369-370, ii. <a href="#page147">147</a>;</p> + <p class="i2">bud-variation by tubers in the, i. 385;</p> + <p class="i2">improvement of, by selection, ii. <a href="#page216">216</a>;</p> + <p class="i2">steps in cultivation of, ii. <a href="#page261">261</a>;</p> + <p class="i2">effect of conditions of life on, ii. <a href="#page273">273</a>;</p> + <p class="i2">correlation of form and colour in, ii. <a href="#page331">331</a>.</p> + <p><span class="sc">Daisy</span>, hen and chicken, i. 365;</p> + <p class="i2">Swan River, ii. <a href="#page261">261</a>.</p> + <p><span class="sc">Dalbret</span>, varieties of wheat, i. 314.</p> + <p><span class="sc">Dalibert</span>, changes in the odours of plants, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Dally</span>, Dr., on consanguineous marriages, ii. <a href="#page122">122</a>.</p> + <p><span class="sc">Daltonism</span>, hereditary, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">Damaras</span>, cattle of, i. 88, ii. <a href="#page207">207</a>-<a href="#page208">208</a>.</p> +<!-- Page 446 --><span class="pagenum"><a name="page446"></a>{446}</span> + <p><span class="sc">Damson</span>, i. 347.</p> + <p><span class="sc">Dandolo</span>, Count, on silkworms, i. 301.</p> + <p><span class="sc">Daniell</span>, fertility of English dogs in Sierra Leone, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Danish</span> Middens, remains of dogs in, i. 18.</p> + <p><span class="sc">Dappling</span> in horses, asses, and hybrids, i. 55.</p> + <p><span class="sc">Dareste. C.</span>, on the skull of the Polish fowl, i. 262;</p> + <p class="i2">on the production of monstrous chickens, ii. <a href="#page289">289</a>;</p> + <p class="i2">co-existence of anomalies, ii. <a href="#page331">331</a>;</p> + <p class="i2">production of double monsters, ii. <a href="#page340">340</a>.</p> + <p><span class="sc">Darvill</span>, Mr., heredity of good qualities in horses, ii. <a href="#page11">11</a>.</p> + <p><span class="sc">Darwin, C.</span>, on <i>Lepus magellanicus</i>, i. 112;</p> + <p class="i2">on the wild potato, i. 330;</p> + <p class="i2">dimorphism in the polyanthus and primrose, ii. <a href="#page21">21</a>.</p> + <p><span class="sc">Darwin</span>, Dr., improvement of vegetables by selection, ii. <a href="#page204">204</a>.</p> + <p><span class="sc">Darwin</span>, Sir F., wildness of crossed pigs, ii. <a href="#page45">45</a>.</p> + <p><span class="sc">D'Asso</span>, monogynous condition of the hawthorn in Spain, i. 364.</p> + <p><i>Dasyprocta aguti</i>, ii. <a href="#page152">152</a>.</p> + <p>Date-palm, varieties of the, ii. <a href="#page256">256</a>;</p> + <p class="i2">effect of pollen of, upon the fruit of <i>Chamærops</i>, i. 299.</p> + <p><i>Datura</i>, ii. <a href="#page38">38</a>;</p> + <p class="i2">variability in, ii. <a href="#page266">266</a>.</p> + <p><i>Datura lævis</i> and <i>stramonium</i>, reversion in hybrids of, i. 392.</p> + <p><i>Datura stramonium</i>, ii. <a href="#page67">67</a>.</p> + <p><span class="sc">Daubenton</span>, variations in the number of mammæ in dogs, i. 35;</p> + <p class="i2">proportions of intestines in wild and domestic cats, i. 48, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Daudin</span>, on white rabbits, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Davy</span>, Dr., on sheep in the West Indies, i. 98.</p> + <p><span class="sc">Dawkins</span> and Sandford, early domestication of <i>Bos longifrons</i> in Britain, i. 81.</p> + <p><span class="sc">Deaf-mutes</span>, non-heredity of, ii. <a href="#page22">22</a>.</p> + <p><span class="sc">Deafness</span>, inheritance of, ii. <a href="#page78">78</a>.</p> + <p><span class="sc">Deby</span>, wild hybrids of common and musk ducks, ii. <a href="#page46">46</a>.</p> + <p><span class="sc">De Candolle</span>, Alph., number and origin of cultivated plants, i. 306-307, 371;</p> + <p class="i2">regions which have furnished no useful plants, i. 310;</p> + <p class="i2">wild wheat, i. 312-313;</p> + <p class="i2">wild rye and oats, i. 313;</p> + <p class="i2">antiquity of varieties of wheat, i. 316;</p> + <p class="i2">apparent inefficacy of selection in wheat, i. 318;</p> + <p class="i2">origin and cultivation of maize, i. 320, ii. <a href="#page307">307</a>;</p> + <p class="i2">colours of seeds of maize, i. 321;</p> + <p class="i2">varieties and origin of the cabbage, i. 324-325;</p> + <p class="i2">origin of the garden-pea, i. 326;</p> + <p class="i2">on the vine, i. 332, ii. <a href="#page308">308</a>;</p> + <p class="i2">cultivated species of the orange group, i. 335;</p> + <p class="i2">probable Chinese origin of the peach, i. 337;</p> + <p class="i2">on the peach and nectarine, i. 340, 342;</p> + <p class="i2">varieties of the peach, i. 342;</p> + <p class="i2">origin of the apricot, i. 344;</p> + <p class="i2">origin and varieties of the plum, i. 345;</p> + <p class="i2">origin of the cherry, i. 347;</p> + <p class="i2">varieties of the gooseberry, i. 354;</p> + <p class="i2">selection practised with forest-trees, i. 361;</p> + <p class="i2">wild fastigate oak, i. 361;</p> + <p class="i2">dark-leaved varieties of trees, i. 362;</p> + <p class="i2">conversion of stamens into pistils in the poppy, i. 365;</p> + <p class="i2">variegated foliage, i. 366;</p> + <p class="i2">heredity of white hyacinths, i. 371, ii. <a href="#page20">20</a>;</p> + <p class="i2">changes in oaks dependent on age, i. 387;</p> + <p class="i2">inheritance of anomalous characters, ii. <a href="#page19">19</a>;</p> + <p class="i2">variation of plants in their native countries, ii. <a href="#page256">256</a>;</p> + <p class="i2">deciduous bushes becoming evergreen in hot climates, ii. <a href="#page305">305</a>;</p> + <p class="i2">antiquity of races of plants, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">De Candolle, P.</span>, non-variability of monotypic genera, ii. <a href="#page266">266</a>;</p> + <p class="i2">relative development of root and seed in <i>Raphanus sativus</i>, ii. <a href="#page343">343</a>.</p> + <p><span class="sc">Decaisne</span>, on the cultivation of the wild carrot, i. 326;</p> + <p class="i2">varieties of the pear, i. 350;</p> + <p class="i2">inter-crossing of strawberries, i. 351;</p> + <p class="i2">fruit of the apple, i. 401;</p> + <p class="i2">sterility of <i>Lysimachia nummularia</i>, ii. <a href="#page170">170</a>;</p> + <p class="i2">tender variety of the peach, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Deer</span>, assumption of horns by female, ii. <a href="#page51">51</a>;</p> + <p class="i2">imperfect development of horns in a, on a voyage, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Deer</span>, fallow, ii. <a href="#page103">103</a>.</p> + <p><span class="sc">Deerhound</span>. Scotch, difference in size of the sexes of, ii. <a href="#page73">73</a>;</p> + <p class="i2">deterioration of, ii. <a href="#page121">121</a>.</p> + <p><span class="sc">Degeneration</span> of high-bred races, under neglect, ii. <a href="#page239">239</a>.</p> + <p><span class="sc">De Jonghe, J.</span>, on strawberries, i. 352, ii. <a href="#page243">243</a>;</p> + <p class="i2">soft-barked pears, ii. <a href="#page231">231</a>;</p> + <p class="i2">on accumulative variation, ii. <a href="#page262">262</a>;</p> + <p class="i2">resistance of blossoms to frost, ii. <a href="#page306">306</a>.</p> + <p><span class="sc">Delamer, E. S.</span>, on rabbits, i. 107, 112.</p> + <p><i>Delphinium ajacis</i>, ii. <a href="#page21">21</a>.</p> + <p><i>Delphinium consolida</i>, ii. <a href="#page20">20</a>-<a href="#page21">21</a>.</p> + <p><i>Dendrocygna viduata</i>, i. 182, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Dentition</span>, variations of, in the horse, i. 50.</p> + <p><span class="sc">Deodar</span>, i. 364.</p> + <p><span class="sc">Desmarest</span>, distribution of white on dogs, i. 29;</p> + <p class="i2">cat from the Cape of Good Hope, i. 47;</p> + <p class="i2">cats of Madagascar, i. 47;</p> + <p class="i2">occurrence of striped young in Turkish pigs, i. 76;</p> + <p class="i2">French breeds of cattle, i. 80;</p> + <p class="i2">horns of goats, i. 102;</p> + <p class="i2">on hornless goats, ii. <a href="#page315">315</a>.</p> + <p><span class="sc">Desor, E.</span>, on the Anglo-Saxon race in America, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Desportes</span>, number of varieties of roses, i. 367.</p> + <p><span class="sc">Devay</span>, Dr., singular case of albinism, ii. <a href="#page17">17</a>;</p> + <p class="i2">on the marriage of cousins, ii. <a href="#page122">122</a>;</p> + <p class="i2">on the effects of close interbreeding, ii. <a href="#page143">143</a>, <a href="#page263">263</a>.</p> + <p><span class="sc">Development</span> and metamorphosis, ii. <a href="#page388">388</a>-<a href="#page389">389</a>.</p> + <p><span class="sc">Development</span>, arrests of, ii. <a href="#page315">315</a>-<a href="#page318">318</a>.</p> + <p><span class="sc">Development</span>, embryonic, ii. <a href="#page366">366</a>-<a href="#page368">368</a>.</p> +<!-- Page 447 --><span class="pagenum"><a name="page447"></a>{447}</span> + <p><span class="sc">D'Hervey</span>-Saint-Denys, L., on the ya-mi, or imperial rice of the Chinese, ii. <a href="#page205">205</a>.</p> + <p><span class="sc">Dhole</span>, fertility of the, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Diabetes</span>, occurrence of, in three brothers, ii. <a href="#page17">17</a>.</p> + <p><i>Dianthus</i>, contabescent plants of, ii. <a href="#page165">165</a>-<a href="#page166">166</a>;</p> + <p class="i2">hybrid varieties of, ii. <a href="#page267">267</a>.</p> + <p><i>Dianthus armeria</i> and <i>deltoides</i>, hybrids of, ii. <a href="#page98">98</a>.</p> + <p><i>Dianthus barbatus</i>, i. 381.</p> + <p><i>Dianthus caryophyllus</i>, i. 381.</p> + <p><i>Dianthus japonicus</i>, contabescence of female organs in, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Dichogamous</span> plants, ii. <a href="#page90">90</a>.</p> + <p><span class="sc">Dickson</span>, Mr., on "running" in carnations, i. 381;</p> + <p class="i2">on the colours of tulips, i. 386.</p> + <p><i>Dicotyles torquatus</i> and <i>labiatus</i>, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Dieffenbach</span>, dog of New Zealand, i. 26;</p> + <p class="i2">feral cats in New Zealand, i. 47;</p> + <p class="i2">polydactylism in Polynesia, ii. <a href="#page14">14</a>.</p> + <p><i>Dielytra</i>, ii. <a href="#page59">59</a>.</p> + <p><span class="sc">Diet</span>, change of, ii. <a href="#page303">303</a>-<a href="#page304">304</a>.</p> + <p><i>Digitalis</i>, properties of, affected by culture, ii. <a href="#page274">274</a>;</p> + <p class="i2">poison of, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Digits</span>, supernumerary, ii. <a href="#page57">57</a>;</p> + <p class="i2">analogy of, with embryonic conditions, ii. <a href="#page16">16</a>;</p> + <p class="i2">fusion of, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Dimorphic</span> plants, ii. <a href="#page166">166</a>;</p> + <p class="i2">conditions of reproduction in, ii. <a href="#page181">181</a>-<a href="#page184">184</a>.</p> + <p><span class="sc">Dimorphism</span>, reciprocal, ii. <a href="#page90">90</a>.</p> + <p><span class="sc">Dingo</span>, i. 25;</p> + <p class="i2">variation of, in colour, i. 28;</p> + <p class="i2">half-bred, attempting to burrow, i. 28;</p> + <p class="i2">attraction of foxes by a female, i. 31;</p> + <p class="i2">variations of, in confinement, ii. <a href="#page263">263</a>.</p> + <p><span class="sc">Diœciousness</span> of strawberries, i. 353.</p> + <p><span class="sc">Diseases</span>, inheritance of, ii. <a href="#page7">7</a>-<a href="#page8">8</a>;</p> + <p class="i2">family uniformity of, ii. <a href="#page57">57</a>;</p> + <p class="i2">inherited at corresponding periods of life, ii. <a href="#page77">77</a>-<a href="#page80">80</a>;</p> + <p class="i2">peculiar to localities and climates, ii. <a href="#page276">276</a>;</p> + <p class="i2">obscure correlations in, ii. <a href="#page331">331</a>-<a href="#page332">332</a>;</p> + <p class="i2">affecting certain parts of the body, ii. <a href="#page380">380</a>;</p> + <p class="i2">occurring in alternate generations, ii. <a href="#page401">401</a>.</p> + <p><span class="sc">Distemper</span>, fatal to white terriers, ii. <a href="#page227">227</a>.</p> + <p><span class="sc">Disuse</span> and use of parts, effects of, ii. <a href="#page295">295</a>-<a href="#page303">303</a>, <a href="#page352">352</a>-<a href="#page353">353</a>, <a href="#page418">418</a>-<a href="#page419">419</a>;</p> + <p class="i2">in the skeleton of rabbits, i. 124-128;</p> + <p class="i2">in pigeons, i. 171-177;</p> + <p class="i2">in fowls, i. 270-274;</p> + <p class="i2">in ducks, i. 284-286;</p> + <p class="i2">in the silk-moth, i. 300-304.</p> + <p><span class="sc">Divergence</span>, influence of, in producing breeds of pigeons, i. 220.</p> + <p><span class="sc">Dixon, E. S.</span>, on the musk duck, i. 182;</p> + <p class="i2">on feral ducks, i. 190;</p> + <p class="i2">on feral pigeons in Norfolk Island, i. 190;</p> + <p class="i2">crossing of pigeons, i. 192;</p> + <p class="i2">origin of domestic fowls, i. 230;</p> + <p class="i2">crossing of <i>Gallus Sonneratii</i> and common fowl, i. 234;</p> + <p class="i2">occurrence of white in the young chicks of black fowls, i. 244;</p> + <p class="i2">Paduan fowl of Aldrovandi, i. 247;</p> + <p class="i2">peculiarities of the eggs of fowls, i. 248;</p> + <p class="i2">chickens, i. 249-250;</p> + <p class="i2">late development of the tail in Cochin cocks, i. 250;</p> + <p class="i2">comb of lark-crested fowls, i. 256;</p> + <p class="i2">development of webs in Polish fowls, i. 259;</p> + <p class="i2">on the voice of fowls, i. 259;</p> + <p class="i2">origin of the duck, i. 277;</p> + <p class="i2">ducks kept by the Romans, i. 278;</p> + <p class="i2">domestication of the goose, i. 287;</p> + <p class="i2">gander frequently white, i. 288;</p> + <p class="i2">breeds of turkeys, i. 293;</p> + <p class="i2">incubatory instinct of mongrels of non-sitting races of fowls, ii. <a href="#page44">44</a>;</p> + <p class="i2">aversion of the dove-cot pigeon to pair with fancy birds, ii. <a href="#page103">103</a>;</p> + <p class="i2">fertility of the goose, ii. <a href="#page112">112</a>;</p> + <p class="i2">general sterility of the guans in captivity, ii. <a href="#page156">156</a>;</p> + <p class="i2">fertility of geese in captivity, ii. <a href="#page157">157</a>;</p> + <p class="i2">white peafowl, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Dobell, H.</span>, inheritance of anomalies of the extremities, ii. <a href="#page14">14</a>;</p> + <p class="i2">non-reversion to a malformation, ii. <a href="#page36">36</a>.</p> + <p><span class="sc">Dobrizhoffer</span>, abhorrence of incest by the Abipones, ii. <a href="#page123">123</a>.</p> + <p><span class="sc">Dogs</span>, origin of, i. 15;</p> + <p class="i2">ancient breeds of, i. 17, ii. <a href="#page429">429</a>;</p> + <p class="i2">of neolithic, bronze and iron periods in Europe, i. 18-19, ii. <a href="#page427">427</a>;</p> + <p class="i2">resemblance of to various species of canidæ, i. 21;</p> + <p class="i2">of North America compared with wolves, i. 21-22;</p> + <p class="i2">of the West Indies, South America, and Mexico, i. 23, 31;</p> + <p class="i2">of Guiana, i. 23;</p> + <p class="i2">naked dogs of Paraguay and Peru, <i>ibid.</i> and 31;</p> + <p class="i2">dumb, on Juan Fernandez, i. 27;</p> + <p class="i2">of Juan de Nova, i. 27;</p> + <p class="i2">of La Plata, i. 27;</p> + <p class="i2">of Cuba, i. 27;</p> + <p class="i2">of St. Domingo, i. 28;</p> + <p class="i2">correlation of colour in, i. 28-29;</p> + <p class="i2">gestation of, i. 29-30;</p> + <p class="i2">hairless Turkish, i. 30, ii. <a href="#page227">227</a>;</p> + <p class="i2">inter-crossing of different breeds of, i. 31;</p> + <p class="i2">characters of different breeds of, discussed, i. 34-37;</p> + <p class="i2">degeneration of European, in warm climates, i. 36, 38; ii. <a href="#page278">278</a>, <a href="#page305">305</a>;</p> + <p class="i2">liability to certain diseases in different breeds of, i. 36 and <i>note</i>;</p> + <p class="i2">causes of differences of breeds discussed, i. 37-43;</p> + <p class="i2">catching fish and crabs in New Guinea and Tierra del Fuego, i. 39;</p> + <p class="i2">webbing of the feet in, i. 39;</p> + <p class="i2">influence of selection in producing different breeds of, i. 39, 43;</p> + <p class="i2">retention of original habits by, i. 182;</p> + <p class="i2">inheritance of polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">feral, ii. <a href="#page33">33</a>;</p> + <p class="i2">reversion in fourth generation of, ii. <a href="#page34">34</a>;</p> + <p class="i2">of the Pacific Islands, ii. <a href="#page87">87</a>, <a href="#page220">220</a>, <a href="#page303">303</a>;</p> + <p class="i2">mongrel, ii. <a href="#page92">92</a>-<a href="#page93">93</a>;</p> + <p class="i2">comparative facility of crossing different breeds of, ii. <a href="#page102">102</a>;</p> + <p class="i2">fertility of, ii. <a href="#page111">111</a>, <a href="#page151">151</a>;</p> + <p class="i2">inter-breeding of, ii. <a href="#page120">120</a>-<a href="#page121">121</a>;</p> + <p class="i2">selection of, among the Greeks, ii. <a href="#page202">202</a>, <a href="#page209">209</a>;</p> + <p class="i2">among savages, ii. <a href="#page206">206</a>-<a href="#page207">207</a>;</p> + <p class="i2">unconscious selection of, ii. <a href="#page211">211</a>-<a href="#page212">212</a>;</p> + <p class="i2">valued by the Fuegians, ii. <a href="#page215">215</a>;</p> + <p class="i2">climatal changes in hair of, ii. <a href="#page278">278</a>;</p> + <p class="i2">production of drooping ears in, ii. <a href="#page301">301</a>;</p> +<!-- Page 448 --><span class="pagenum"><a name="page448"></a>{448}</span> + <p class="i2">rejection of bones of game by, ii. <a href="#page303">303</a>;</p> + <p class="i2">inheritance of rudiments of limbs in, ii. <a href="#page315">315</a>;</p> + <p class="i2">development of fifth toe in, ii. <a href="#page317">317</a>;</p> + <p class="i2">hairless, deficiency of teeth in, ii. <a href="#page326">326</a>;</p> + <p class="i2">short-faced, teeth of, ii. <a href="#page345">345</a>;</p> + <p class="i2">probable analogous variation in, ii. <a href="#page349">349</a>;</p> + <p class="i2">extinction of breeds of, ii. <a href="#page425">425</a>.</p> + <p><span class="sc">Dombrain, H. H.</span>, on the auricula, ii. <a href="#page346">346</a>-<a href="#page347">347</a>.</p> + <p><span class="sc">Domestication</span>, essential points in, ii. <a href="#page405">405</a>-<a href="#page406">406</a>;</p> + <p class="i2">favourable to crossing, ii. <a href="#page109">109</a>-<a href="#page110">110</a>;</p> + <p class="i2">fertility increased by, ii. <a href="#page111">111</a>-<a href="#page113">113</a>, <a href="#page174">174</a>.</p> + <p><span class="sc">Domesticated</span> animals, origin of, ii. <a href="#page160">160</a>-<a href="#page161">161</a>;</p> + <p class="i2">occasional sterility of, under changed conditions, ii. <a href="#page161">161</a>-<a href="#page162">162</a>.</p> + <p><span class="sc">Donders</span>, Dr., hereditary hypermetropia, ii. <a href="#page8">8</a>.</p> + <p><span class="sc">Dorking</span> fowl, i. 227, 261;</p> + <p class="i2">furcula of, figured, i. 268.</p> + <p><span class="sc">Dormouse</span>, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Double flowers</span>, ii. <a href="#page167">167</a>-<a href="#page168">168</a>, <a href="#page171">171</a>-<a href="#page172">172</a>;</p> + <p class="i2">produced by selection, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Doubleday, H.</span>, cultivation of the filbert pine strawberry, i. 354.</p> + <p><span class="sc">Douglas, J.</span>, crossing of white and black game-fowls, ii. <a href="#page92">92</a>.</p> + <p><span class="sc">Downing</span>, Mr., wild varieties of the hickory, i. 310;</p> + <p class="i2">peaches and nectarines from seed, i. 339-340;</p> + <p class="i2">origin of the Boston nectarine, i. 340;</p> + <p class="i2">American varieties of the peach, i. 343;</p> + <p class="i2">North American apricot, i. 344;</p> + <p class="i2">varieties of the plum, i. 346;</p> + <p class="i2">origin and varieties of the cherry, i. 347-348;</p> + <p class="i2">"twin cluster pippins," i. 349;</p> + <p class="i2">varieties of the apple, i. 350;</p> + <p class="i2">on strawberries, i. 351, 353;</p> + <p class="i2">fruit of the wild gooseberry, i. 355;</p> + <p class="i2">effects of grafting upon the seed, ii. <a href="#page26">26</a>;</p> + <p class="i2">diseases of plum and peach trees, ii. <a href="#page227">227</a>-<a href="#page228">228</a>;</p> + <p class="i2">injury done to stone fruit in America by the "weevil," ii. <a href="#page231">231</a>;</p> + <p class="i2">grafts of the plum and peach, ii. <a href="#page259">259</a>;</p> + <p class="i2">wild varieties of pears, ii. <a href="#page260">260</a>;</p> + <p class="i2">varieties of fruit-trees suitable to different climates, ii. <a href="#page306">306</a>.</p> + <p><i>Draba sylvestris</i>, ii. <a href="#page163">163</a>.</p> + <p><span class="sc">Dragon</span>, pigeon, i. 139, 141.</p> + <p>"<span class="sc">Draijer</span>" (pigeon), i. 156.</p> + <p><span class="sc">Drinking</span>, effects of, in different climates, ii. <a href="#page289">289</a>.</p> + <p><span class="sc">Dromedary</span>, selection of, ii. <a href="#page205">205</a>-<a href="#page206">206</a>.</p> + <p><span class="sc">Druce</span>, Mr., inter-breeding of pigs, ii. <a href="#page121">121</a>.</p> + <p><span class="sc">Du Chaillu</span>, fruit-trees in West Africa, i. 309.</p> + <p><span class="sc">Duchesne</span> on <i>Fragaria vesca</i>, i. 351, 352, 353.</p> + <p><span class="sc">Dufour</span>, Léon, on <i>Cecidomyia</i> and <i>Misocampus</i>, i. 5.</p> + <p><span class="sc">Duck</span>, musk, retention of perching habit by the, i. 182;</p> + <p class="i2">feral hybrid of, i. 190.</p> + <p><span class="sc">Duck</span>, penguin, hybrid of, with Egyptian goose, ii. <a href="#page68">68</a>.</p> + <p><span class="sc">Duck</span>, wild, difficulty of rearing, ii. <a href="#page233">233</a>;</p> + <p class="i2">effects of domestication on, ii. <a href="#page278">278</a>.</p> + <p><span class="sc">Ducks</span>, breeds of, i. 276-277;</p> + <p class="i2">origin of, i. 277;</p> + <p class="i2">history of, <i>ibid.</i>;</p> + <p class="i2">wild, easily tamed, i. 278-279;</p> + <p class="i2">fertility of breeds of, when crossed, i. 279;</p> + <p class="i2">with the plumage of <i>Anas boschas</i>, i. 280;</p> + <p class="i2">Malayan penguin, identical in plumage with English, i. 280;</p> + <p class="i2">characters of the breeds of, i. 281-284;</p> + <p class="i2">eggs of, i. 281;</p> + <p class="i2">effects of use and disuse in, i. 284-286, ii. <a href="#page298">298</a>;</p> + <p class="i2">feral, in Norfolk, i. 190;</p> + <p class="i2">Aylesbury, inheritance of early hatching by, ii. <a href="#page25">25</a>;</p> + <p class="i2">reversion in, produced by crossing, ii. <a href="#page40">40</a>;</p> + <p class="i2">wildness of half-bred wild, ii. <a href="#page45">45</a>;</p> + <p class="i2">hybrids of, with the musk duck, ii. <a href="#page45">45</a>-<a href="#page46">46</a>;</p> + <p class="i2">assumption of male plumage by, ii. <a href="#page51">51</a>;</p> + <p class="i2">crossing of Labrador and penguin, ii. <a href="#page97">97</a>;</p> + <p class="i2">increased fertility of, by domestication, ii. <a href="#page112">112</a>;</p> + <p class="i2">general fertility of, in confinement, ii. <a href="#page157">157</a>;</p> + <p class="i2">increase of size of, by care in breeding, ii. <a href="#page199">199</a>;</p> + <p class="i2">change produced by domestication in, ii. <a href="#page262">262</a>.</p> + <p><span class="sc">Duméril</span>, Aug., breeding of <i>Siredon</i> in the branchiferous stage, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Dun</span>-coloured horses, origin of, i. 59.</p> + <p><span class="sc">Dureau</span> de la Malle, feral pigs in Louisiana, ii. <a href="#page33">33</a>;</p> + <p class="i2">feral fowls in Africa, <i>ibid.</i>;</p> + <p class="i2">bud-variation in the pear, i. 376;</p> + <p class="i2">production of mules among the Romans, ii. <a href="#page110">110</a>.</p> + <p><i>Dusicyon sylvestris</i>, i. 23.</p> + <p><span class="sc">Dutch</span> rabbit, i. 107.</p> + <p><span class="sc">Dutch</span> roller pigeon, i. 151.</p> + <p><span class="sc">Dutrochet</span>, pelorism in the laburnum, ii. <a href="#page346">346</a>.</p> + <p><span class="sc">Duval</span>, growth of pears in woods in France, ii. <a href="#page260">260</a>.</p> + <p><span class="sc">Duval</span>-Jouve, on <i>Leersia oryzoides</i>, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Duvernoy</span>, self-impotence in <i>Lilium candidum</i>, ii. <a href="#page137">137</a>.</p> + <p><span class="sc">Dzierzon</span>, variability in the characters and habits of bees, i. 298.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Earle</span>, Dr., on colour-blindness, ii. <a href="#page72">72</a>, <a href="#page328">328</a>.</p> + <p><span class="sc">Ears</span>, of fancy rabbits, i. 106;</p> + <p class="i2">deficiency of, in breeds of rabbits, i. 108;</p> + <p class="i2">rudimentary, in Chinese sheep, ii. <a href="#page315">315</a>;</p> + <p class="i2">drooping, ii. <a href="#page301">301</a>;</p> + <p class="i2">fusion of, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Eaton, J. M.</span>, on fancy pigeons, i. 148, 153;</p> + <p class="i2">variability of characters in breeds of pigeons, i. 161;</p> + <p class="i2">reversion of crossed pigeons to coloration of <i>Columba livia</i>, i. 198;</p> + <p class="i2">on pigeon-fancying, i. 206, 215-216;</p> + <p class="i2">on tumbler-pigeons, i. 209, ii. <a href="#page242">242</a>;</p> + <p class="i2">carrier-pigeon, i. 211;</p> + <p class="i2">effects of interbreeding on pigeons, ii. <a href="#page126">126</a>;</p> + <p class="i2">properties of pigeons, ii. <a href="#page197">197</a>-<a href="#page198">198</a>;</p> + <p class="i2">death of short-faced tumblers in the egg, ii. <a href="#page226">226</a>;</p> +<!-- Page 449 --><span class="pagenum"><a name="page449"></a>{449}</span> + <p class="i2">Archangel pigeon, ii. <a href="#page240">240</a>.</p> + <p><span class="sc">Echinodermata</span>, metagenesis in, ii. <a href="#page367">367</a>.</p> + <p><i>Ectopistes</i>, specific difference in number of tail-feathers in, i. 159.</p> + <p><i>Ectopistes migratorius</i>, sterile hybrids of, with <i>Turtur vulgaris</i>, i. 193.</p> + <p><span class="sc">Edentata</span>, correlation of dermal system and teeth in the, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Edgeworth</span>, Mr., use of grass-seeds as food in the Punjab, i. 309.</p> + <p><span class="sc">Edmonston</span>, Dr., on the stomach in <i>Larus argentatus</i> and the raven, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Edwards</span> and <span class="sc">Colin</span>, on English wheat in France, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Edwards</span>, W. F., absorption of the minority in crossed races, ii. <a href="#page87">87</a>.</p> + <p><span class="sc">Edwards</span>, W. W., occurrence of stripes in a nearly thoroughbred horse, i. 57;</p> + <p class="i2">in foals of racehorses, i. 59.</p> + <p><span class="sc">Eggs</span>, of fowls, characters of, i. 248;</p> + <p class="i2">variations of, in ducks, i. 281;</p> + <p class="i2">of the silkmoth, i. 301.</p> + <p><span class="sc">Egypt</span>, ancient dogs of, i. 17-18;</p> + <p class="i2">ancient domestication of the pigeon in, i. 204;</p> + <p class="i2">absence of the fowl in ancient, i. 246.</p> + <p><span class="sc">Egyptian</span> goose, hybrids of, with penguin duck, i. 282.</p> + <p><span class="sc">Ehrenberg</span>, Prof., multiple origin of the dog, i. 16;</p> + <p class="i2">dogs of Lower Egypt, i. 25;</p> + <p class="i2">mummies of <i>Felis maniculata</i>, i. 43.</p> + <p><span class="sc">Element</span>, male, compared to a premature larva, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Elements</span> of the body, functional independence of the, ii. <a href="#page368">368</a>-<a href="#page371">371</a>.</p> + <p><span class="sc">Elephant</span>, its sterility in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Elk</span>, Irish, correlations in the, ii. <a href="#page333">333</a>-<a href="#page334">334</a>.</p> + <p><span class="sc">Elliot</span>, Sir Walter, on striped horses, i. 58;</p> + <p class="i2">Indian domestic and wild swine, i. 66;</p> + <p class="i2">pigeons from Cairo and Constantinople, i. 132;</p> + <p class="i2">fantail pigeons, i. 146;</p> + <p class="i2">Lotan tumbler pigeons, i. 150;</p> + <p class="i2">a pigeon uttering the sound <i>Yahu</i>, i. 155;</p> + <p class="i2"><i>Gallus bankiva</i> in Pegu, i. 236.</p> + <p><span class="sc">Ellis</span>, Mr., varieties of cultivated plants in Tahiti, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Elm</span>, nearly evergreen Cornish variety of the, i. 363, ii. <a href="#page310">310</a>;</p> + <p class="i2">foliage-varieties of the, i. 362.</p> + <p><span class="sc">Elm</span>, weeping, i. 361;</p> + <p class="i2">not reproduced by seed, ii. <a href="#page19">19</a>.</p> + <p><i>Emberiza passerina</i>, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Embryos</span>, similarity of, i. 12;</p> + <p class="i2">fusion of, ii. <a href="#page339">339</a>.</p> + <p><span class="sc">Engel</span>, on <i>Laurus sassafras</i>, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">England</span>, domestication of <i>Bos longifrons</i> in, i. 81;</p> + <p class="i2">selection of horses in, in mediæval times, ii. <a href="#page203">203</a>;</p> + <p class="i2">laws against the early slaughter of rams in, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Ephemeridæ</span>, development of the, ii. <a href="#page366">366</a>.</p> + <p><i>Epidendrum cinnabarinum</i> and <i>E. zebra</i>, ii. <a href="#page134">134</a>.</p> + <p><span class="sc">Epilepsy</span>, hereditary, ii. <a href="#page8">8</a>, <a href="#page78">78</a>.</p> + <p><span class="sc">Erdt</span>, disease of the white parts of cattle, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Ericaceæ</span>, frequency of contabescence in the, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Erichthonius</span>, an improver of horses by selection, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Erman</span>, on the fat-tailed Kirghisian sheep, i. 98, ii. <a href="#page280">280</a>;</p> + <p class="i2">on the dogs of the Ostyaks, ii. <a href="#page206">206</a>.</p> + <p><i>Erodium</i>, ii. <a href="#page59">59</a>.</p> + <p><i>Erythrina Crista-galli</i> and <i>E. herbacea</i>, hybrids of, ii. <a href="#page265">265</a>.</p> + <p><span class="sc">Esquilant</span>, Mr., on the naked young of dun-coloured pigeons, i. 170.</p> + <p><span class="sc">Esquimaux</span> dogs, their resemblance to wolves, i. 21;</p> + <p class="i2">selection of, ii. <a href="#page206">206</a>.</p> + <p><span class="sc">Eudes-Deslongchamps</span>, on appendages under the jaw of pigs, i. 75-76.</p> + <p><i>Euonymus Japonicus</i>, i. 383.</p> + <p><span class="sc">European</span> cultivated plants, still wild in Europe, i. 307.</p> + <p><span class="sc">Evans</span>, Mr., on the Lotan tumbler pigeon, i. 150.</p> + <p><span class="sc">Evelyn</span>, pansies grown in his garden, i. 368.</p> + <p><span class="sc">Everest, R.</span>, on the Newfoundland dog in India, i. 36, ii. <a href="#page305">305</a>;</p> + <p class="i2">degeneration of setters in India, i. 38;</p> + <p class="i2">Indian wild boars, i. 66.</p> + <p><span class="sc">Ewes</span>, hornless, ii. <a href="#page350">350</a>.</p> + <p><span class="sc">Extinction</span> of domestic races, i. 221.</p> + <p><span class="sc">Eyes</span>, hereditary peculiarities of the, ii. <a href="#page8">8</a>-<a href="#page10">10</a>;</p> + <p class="i2">loss of, causing microphthalmia in children, ii. <a href="#page24">24</a>;</p> + <p class="i2">modification of the structure of, by natural selection, ii. <a href="#page222">222</a>-<a href="#page223">223</a>;</p> + <p class="i2">fusion of, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Eyebrows</span>, hereditary elongation of hairs in, ii. <a href="#page8">8</a>.</p> + <p><span class="sc">Eyelids</span>, inherited peculiarities of the, ii. <a href="#page8">8</a>.</p> + <p><span class="sc">Eyton</span>, Mr., on gestation in the dog, i. 30;</p> + <p class="i2">variability in number of vertebræ in the pig, i. 74;</p> + <p class="i2">individual sterility, ii. <a href="#page162">162</a>.</p> + </div> + + <div class="stanza"> + <p><i>Faba vulgaris</i>, i. 330.</p> + <p><span class="sc">Fabre</span>, observations on <i>Ægilops triticoides,</i> i. 313.</p> + <p><i>Fagus sylvatica</i>, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Fairweather</span>, Mr., production of double flowers from old seed, ii. <a href="#page167">167</a>.</p> + <p><i>Falco albidus</i>, resumption of young plumage by, in captivity, ii. <a href="#page158">158</a>.</p> + <p><i>Falco ossifragus</i>, ii. <a href="#page230">230</a>.</p> + <p><i>Falco subbuteo</i>, copulating in captivity, ii. <a href="#page154">154</a>.</p> + <p><i>Falco tinnunculus</i>, breeding in captivity, ii. <a href="#page154">154</a>.</p> +<!-- Page 450 --><span class="pagenum"><a name="page450"></a>{450}</span> + <p><span class="sc">Falconer</span>, Dr., sterility of English bulldogs in India, i, 38;</p> + <p class="i2">resemblance between <i>Sivatherium</i> and Niata cattle, i. 89;</p> + <p class="i2">selection of the silkworm in India, i. 301;</p> + <p class="i2">fastigate apple-trees in Calcutta, i. 361;</p> + <p class="i2">reproduction of a supernumerary thumb after amputation, ii. <a href="#page14">14</a>;</p> + <p class="i2">fertility of the dhole in captivity, ii. <a href="#page151">151</a>;</p> + <p class="i2">fertility of English dogs in India, ii. <a href="#page161">161</a>;</p> + <p class="i2">sterility of the tiger in captivity, ii. <a href="#page151">151</a>;</p> + <p class="i2">turkeys at Delhi, ii. <a href="#page161">161</a>;</p> + <p class="i2">on Indian cultivated plants, ii. <a href="#page165">165</a>;</p> + <p class="i2">Thibet mastiff and goat, ii. <a href="#page278">278</a>.</p> + <p><span class="sc">Falcons</span>, sterility of, in captivity, ii. <a href="#page153">153</a>.</p> + <p><span class="sc">Falkland</span> Islands, horses of the, i. 52-53, 61;</p> + <p class="i2">feral pigs of the, i. 77;</p> + <p class="i2">feral cattle of the, i. 82, 86;</p> + <p class="i2">feral rabbits of the, i. 112.</p> + <p><span class="sc">Fallow</span> deer, ii. <a href="#page103">103</a>, <a href="#page120">120</a>.</p> + <p><span class="sc">Fantail</span> pigeons, i. 146-148, ii. <a href="#page227">227</a>;</p> + <p class="i2">figured, i. 147;</p> + <p class="i2">furcula of, figured, i. 167;</p> + <p class="i2">history of, i. 208;</p> + <p class="i2">absence of oil-gland in, ii. <a href="#page344">344</a>.</p> + <p><span class="sc">Faroe</span> Islands, pigeons of the, i. 183.</p> + <p><span class="sc">Fashion</span>, influence of, in breeding, ii. <a href="#page240">240</a>.</p> + <p><span class="sc">Fastigate</span> trees, ii. <a href="#page277">277</a>, <a href="#page348">348</a>.</p> + <p><span class="sc">Faunas</span>, geographical differences, of, i. 10.</p> + <p>"<span class="sc">Favourite</span>" bull, ii. <a href="#page65">65</a>, <a href="#page118">118</a>.</p> + <p><span class="sc">Feathers</span>, homologous variation in, ii. <a href="#page325">325</a>.</p> + <p><span class="sc">Feet</span>, of pigeons, individual differences of, i. 160;</p> + <p class="i2">correlations of external characters in, i. 170-171.</p> + <p><span class="sc">Feet</span> and beak, correlation of, in pigeons, i. 171-174.</p> + <p><span class="sc">Felidæ</span>, fertility of, in captivity, ii. <a href="#page150">150</a>.</p> + <p><i>Felis bubastes</i>, i. 43.</p> + <p><i>Felis caffra</i>, i. 44.</p> + <p><i>Felis caligulata</i>, i. 43.</p> + <p><i>Felis chaus</i>, i. 43-44.</p> + <p><i>Felis jubata</i>, ii. <a href="#page151">151</a>.</p> + <p><i>Felis lybica</i>, i. 44.</p> + <p><i>Felis maniculata</i>, i. 43.</p> + <p><i>Felis manul</i>, i. 45.</p> + <p><i>Felis ornata</i>, i. 45.</p> + <p><i>Felis sylvestris</i>, i. 44.</p> + <p><i>Felis torquata</i>, i. 45.</p> + <p><span class="sc">Female</span>, affected by male element, ii. <a href="#page365">365</a>, <a href="#page387">387</a>-<a href="#page388">388</a>.</p> + <p><span class="sc">Female</span> flowers, in male panicle of maize, i. 321.</p> + <p><span class="sc">Fennel</span>, Italian variety of, i. 326.</p> + <p><span class="sc">Feral</span> cats, i. 47;</p> + <p class="i2">cattle, i. 86;</p> + <p class="i2">rabbits, i. 111-115;</p> + <p class="i2">Guinea fowl, i. 294;</p> + <p class="i2">animals and plants, reversion in, ii. <a href="#page32">32</a>-<a href="#page34">34</a>, <a href="#page47">47</a>.</p> + <p><span class="sc">Ferguson</span>, Mr., supposed plurality of origin of domestic fowls, i. 231;</p> + <p class="i2">chickens of black game-fowls, i. 244;</p> + <p class="i2">relative size of eggs of fowls, i. 248;</p> + <p class="i2">yolk of eggs of game-fowls, i. 249;</p> + <p class="i2">early pugnacity of game-cocks, i. 250;</p> + <p class="i2">voice of the Malay fowl, i. 259;</p> + <p class="i2">effects of interbreeding on fowls, ii. <a href="#page124">124</a>;</p> + <p class="i2">selection in Cochin China fowls, ii. <a href="#page196">196</a>;</p> + <p class="i2">on fashion in poultry, ii. <a href="#page240">240</a>.</p> + <p><span class="sc">Fernandez</span>, on Mexican dogs, i. 23.</p> + <p><span class="sc">Ferns</span>, reproduction of abnormal forms of, by spores, i. 383;</p> + <p class="i2">non-diffusion of cell-gemmules in, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Ferrets</span>, ii. <a href="#page111">111</a>, <a href="#page151">151</a>, <a href="#page206">206</a>.</p> + <p><span class="sc">Fertilisation</span>, artificial, of the St. Valery apple, i. 350.</p> + <p><span class="sc">Fertility</span>, various degrees of, in sheep, i. 97;</p> + <p class="i2">unlimited mutual, of breeds of pigeons, i. 192-194;</p> + <p class="i2">comparative of mongrels and hybrids, ii. <a href="#page100">100</a>-<a href="#page101">101</a>, <a href="#page178">178</a>-<a href="#page180">180</a>;</p> + <p class="i2">influence of nourishment on, ii. <a href="#page111">111</a>;</p> + <p class="i2">diminished by close interbreeding, ii. <a href="#page118">118</a>, <a href="#page175">175</a>;</p> + <p class="i2">reduced, of Chillingham wild cattle, ii. <a href="#page119">119</a>;</p> + <p class="i2">of domesticated varieties when crossed, ii. <a href="#page189">189</a>.</p> + <p><i>Festuca</i>, species of, propagated by bulblets, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Filberts</span>, spared by tomtits, ii. <a href="#page231">231</a>.</p> + <p><span class="sc">Filippi</span>, on the breeding of branchiferous tritons, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Finches</span>, general sterility of, in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Finnikin</span> (pigeon), i. 156.</p> + <p><span class="sc">Finnochio</span>, i. 326.</p> + <p><span class="sc">Fir</span>, Scotch, acclimatisation of, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Fish</span>, Mr., advantage of change of soil to plants, ii. <a href="#page147">147</a>.</p> + <p><span class="sc">Fishes</span>, regeneration of portions of fins of, ii. <a href="#page15">15</a>;</p> + <p class="i2">variability of, when kept in tanks, ii. <a href="#page259">259</a>;</p> + <p class="i2">marine, living in fresh water, ii. <a href="#page304">304</a>;</p> + <p class="i2">double monsters of, ii. <a href="#page340">340</a>.</p> + <p><span class="sc">Fission</span> and gemmation, ii. <a href="#page358">358</a>.</p> + <p><span class="sc">Fitch</span>, Mr., persistency of a variety of the pea, i. 329.</p> + <p><span class="sc">Fittest</span>, survival of the, i. 6.</p> + <p><span class="sc">Fitzinger</span>, origin of sheep, i. 94;</p> + <p class="i2">African maned sheep, i. 96.</p> + <p><span class="sc">Fixedness</span> of character, conditions of, discussed, ii. <a href="#page62">62</a>-<a href="#page64">64</a>.</p> + <p><span class="sc">Flax</span>, found in the Swiss lake-dwellings, i. 317;</p> + <p class="i2">climatal difference in products of, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Fleece</span>, fineness of, in Austrian merinos, ii. <a href="#page197">197</a>.</p> + <p><span class="sc">Fleischmann</span>, on German sheep crossed with merinos, ii. <a href="#page88">88</a>-<a href="#page89">89</a>.</p> + <p>"<span class="sc">Florentiner-Taube</span>," i. 142-143.</p> + <p><span class="sc">Flounder</span>, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Flourens</span>, crossing of wolf and dog, i. 32;</p> + <p class="i2">prepotency of the jackal over the dog, ii. <a href="#page67">67</a>;</p> + <p class="i2">hybrids of the horse and ass, ii. <a href="#page68">68</a>;</p> + <p class="i2">breeding of monkeys in Europe, ii. <a href="#page153">153</a>.</p> +<!-- Page 451 --><span class="pagenum"><a name="page451"></a>{451}</span> + <p><span class="sc">Flower-garden</span>, earliest known, in Europe, ii. <a href="#page217">217</a>.</p> + <p><span class="sc">Flowers</span>, capricious transmission of colour-varieties in, ii. <a href="#page20">20</a>-<a href="#page21">21</a>;</p> + <p class="i2">tendency to uniformity in striped, ii. <a href="#page70">70</a>;</p> + <p class="i2">scorching of, dependent on colour, ii. <a href="#page229">229</a>;</p> + <p class="i2">change in, caused by conditions of life, ii. <a href="#page273">273</a>;</p> + <p class="i2">rudimentary, ii. <a href="#page316">316</a>;</p> + <p class="i2">relative position of, to the axis, ii. <a href="#page345">345</a>.</p> + <p><span class="sc">Fœtation</span>, abdominal, ii. <a href="#page294">294</a>.</p> + <p><span class="sc">Foley</span>, Mr., wild varieties of pears, ii. <a href="#page260">260</a>.</p> + <p><span class="sc">Foliage</span>, inherited peculiarities of, i. 362;</p> + <p class="i2">variegation, of, i. 366;</p> + <p class="i2">bud-variation in, i. 382-384.</p> + <p><span class="sc">Food</span>, influence of, on the pig, i. 72;</p> + <p class="i2">on cattle, i. 91;</p> + <p class="i2">excess of, a cause of variability, ii. <a href="#page257">257</a>.</p> + <p><span class="sc">Forbes, D.</span>, on Chilian sheep, i. 95;</p> + <p class="i2">on the horses of Spain, Chili, and the Pampas, i. 52.</p> + <p><i>Formica rufa</i>, ii. <a href="#page251">251</a>.</p> + <p><span class="sc">Fortune, R.</span>, sterility of the sweet potato in China, ii. <a href="#page169">169</a>;</p> + <p class="i2">development of axillary bulbs in the yam, <i>ibid.</i></p> + <p><span class="sc">Fowl</span>, common, breeds of, i. 225-230;</p> + <p class="i2">supposed plurality of origin, i. 230;</p> + <p class="i2">early history of, i. 231-233;</p> + <p class="i2">causes of production of breeds of, i. 233;</p> + <p class="i2">origin of from <i>Gallus bankiva</i>, i. 236-239, 245;</p> + <p class="i2">feral, notices of, i. 237-238;</p> + <p class="i2">reversion and analogous variation in, i. 239-246, ii. <a href="#page35">35</a>, <a href="#page38">38</a>, <a href="#page39">39</a>, <a href="#page40">40</a>, <a href="#page349">349</a>, <a href="#page350">350</a>;</p> + <p class="i2">"cuckoo" sub-breeds of, i. 244;</p> + <p class="i2">history of, i. 246-247;</p> + <p class="i2">structural characters of, i. 247-250;</p> + <p class="i2">sexual peculiarities of, i. 251-257, ii. <a href="#page74">74</a>;</p> + <p class="i2">external differences of, i. 257-260;</p> + <p class="i2">differences of breeds of, from <i>G. bankiva</i>, i. 260;</p> + <p class="i2">osteological characters of, i. 260-270;</p> + <p class="i2">effects of disuse of parts in, i. 270-274, ii. <a href="#page298">298</a>;</p> + <p class="i2">feral, i. 190, ii. <a href="#page33">33</a>;</p> + <p class="i2">polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">fertility of, increased by domestication, ii. <a href="#page112">112</a>, <a href="#page167">167</a>;</p> + <p class="i2">sterility of, under certain conditions, ii. <a href="#page162">162</a>;</p> + <p class="i2">influence of selection on, ii. <a href="#page196">196</a>, <a href="#page198">198</a>, <a href="#page209">209</a>, <a href="#page210">210</a>;</p> + <p class="i2">evils of close interbreeding of, ii. <a href="#page124">124</a>-<a href="#page125">125</a>;</p> + <p class="i2">crossing of, ii. <a href="#page95">95</a>, <a href="#page96">96</a>, <a href="#page97">97</a>;</p> + <p class="i2">prepotency of transmission in, ii. <a href="#page67">67</a>;</p> + <p class="i2">rudimentary organs in, ii. <a href="#page315">315</a>;</p> + <p class="i2">crossing of non-sitting varieties of, ii. <a href="#page43">43</a>-<a href="#page44">44</a>;</p> + <p class="i2">homology of wing and leg feathers in, ii. <a href="#page323">323</a>;</p> + <p class="i2">hybrids of, with pheasants and <i>Gallus Sonneratii</i>, ii. <a href="#page45">45</a>;</p> + <p class="i2">black-skinned, ii. <a href="#page209">209</a>-<a href="#page210">210</a>;</p> + <p class="i2">black, preyed upon by the osprey in Iceland, ii. <a href="#page230">230</a>;</p> + <p class="i2">five-toed, mentioned by Columella, ii. <a href="#page429">429</a>;</p> + <p class="i2">rumpless, tailed chickens produced by, ii. <a href="#page31">31</a>;</p> + <p class="i2">Dorking, crosses of, ii. <a href="#page93">93</a>;</p> + <p class="i2">form of comb and colour of plumage in, ii. <a href="#page238">238</a>;</p> + <p class="i2">game, crossing of white and black, ii. <a href="#page92">92</a>;</p> + <p class="i2">five-spurred, ii. <a href="#page391">391</a>;</p> + <p class="i2">Spanish, liable to suffer from frost, ii. <a href="#page306">306</a>;</p> + <p class="i2">Polish, peculiarities of skull of, ii. <a href="#page332">332</a>-<a href="#page333">333</a>.</p> + <p><span class="sc">Fox</span>, sterility of, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Fox</span>, S. Bevan, races of bees, i. 298.</p> + <p><span class="sc">Fox</span>, W. Darwin, gestation of the dog, i. 30;</p> + <p class="i2">"Negro" cat, i. 46;</p> + <p class="i2">reversion of sheep in colour, ii. <a href="#page30">30</a>;</p> + <p class="i2">period of gestation in the pig, i. 74;</p> + <p class="i2">young of the Himalayan rabbit, i. 109;</p> + <p class="i2">crossing of wild and domestic turkeys, i. 292;</p> + <p class="i2">reversion in crossed musk ducks, ii. <a href="#page40">40</a>;</p> + <p class="i2">spontaneous segregation of varieties of geese, ii. <a href="#page104">104</a>;</p> + <p class="i2">effects of close interbreeding upon bloodhounds, ii. <a href="#page121">121</a>;</p> + <p class="i2">deafness of white cats with blue eyes, ii. <a href="#page329">329</a>.</p> + <p><span class="sc">Foxhounds</span>, i. 40, ii. <a href="#page120">120</a>.</p> + <p><i>Fragaria chiloensis</i>, i. 351.</p> + <p><i>Fragaria collina</i>, i. 351.</p> + <p><i>Fragaria dioica</i> of Duchesne, i. 353.</p> + <p><i>Fragaria elatior</i>, i. 351.</p> + <p><i>Fragaria grandiflora</i>, i. 351.</p> + <p><i>Fragaria vesca</i>, i. 351.</p> + <p><i>Fragaria virginiana</i>, i. 351.</p> + <p><i>Fraxinus excelsior</i>, i. 360, 362, ii. <a href="#page19">19</a>.</p> + <p><i>Fraxinus lentiscifolia</i>, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Friesland</span> cattle, probably descended from <i>Bos primigenius</i>, i. 81.</p> + <p><span class="sc">Frillback</span> (pigeon), i. 155;</p> + <p class="i2">Indian, i. 153.</p> + <p><i>Fringilla ciris</i>, ii. <a href="#page154">154</a>.</p> + <p><i>Fringilla spinus</i>, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Frizzled</span> fowls, i. 230;</p> + <p class="i2">horses, i. 54.</p> + <p><span class="sc">Frog</span>, polydactylism in the, ii. <a href="#page14">14</a>.</p> + <p><span class="sc">Fruit</span>, seedless, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Fruit-trees</span>, varieties of, occurring wild, i. 310.</p> + <p><span class="sc">Fry</span>, Mr., on fertile hybrid cats, i. 44;</p> + <p class="i2">on feral fowls in Ascension, i. 238.</p> + <p><span class="sc">Fuchsias</span>, origin of, i. 364;</p> + <p class="i2">bud-variation in, i. 382.</p> + <p><i>Fuchsia coccinea</i> and <i>fulgens</i>, twin seed produced by crossing, i. 391.</p> + <p><span class="sc">Fuegians</span>, their superstition about killing young water-fowl, i. 310;</p> + <p class="i2">selection of dogs by the, ii. <a href="#page207">207</a>;</p> + <p class="i2">their comparative estimation of dogs and old women, ii. <a href="#page215">215</a>;</p> + <p class="i2">their power of distant vision, ii. <a href="#page223">223</a>.</p> + <p><span class="sc">Fungi</span>, parasitic, ii. <a href="#page284">284</a>-<a href="#page285">285</a>.</p> + <p><span class="sc">Furcula</span>, characters and variations of the, in pigeons, i. 167;</p> + <p class="i2">alteration of, by disuse, in pigeons, i. 175;</p> + <p class="i2">characters of, in fowls, i. 268.</p> + <p><span class="sc">Fusion</span> of homologous parts, ii. <a href="#page393">393</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Gait</span>, inheritance of peculiarities of, ii. <a href="#page6">6</a>.</p> + <p><span class="sc">Galapagos</span> Archipelago, its peculiar fauna and flora, i. 9.</p> + <p><i>Galeobdolon luteum</i>, pelorism in, ii. <a href="#page59">59</a>, <a href="#page345">345</a>.</p> +<!-- Page 452 --><span class="pagenum"><a name="page452"></a>{452}</span> + <p><span class="sc">Galls</span>, ii. <a href="#page282">282</a>-<a href="#page284">284</a>.</p> + <p><span class="sc">Gall-gnats</span>, ii. <a href="#page283">283</a>.</p> + <p><span class="sc">Gall-like</span> excrescences not inherited, ii. <a href="#page23">23</a>.</p> + <p><span class="sc">Gallinaceous</span> birds, restricted range of large, i. 237;</p> + <p class="i2">general fertility of in captivity, ii. <a href="#page155">155</a>.</p> + <p><i>Gallinula chloropus</i>, ii. <a href="#page156">156</a>.</p> + <p><i>Gallinula nesiotis</i>, i. 287.</p> + <p><span class="sc">Galton</span>, Mr., fondness of savages for taming animals, i. 20, ii. <a href="#page160">160</a>;</p> + <p class="i2">cattle of Benguela, i. 88;</p> + <p class="i2">on hereditary talent, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Gallesio</span>, species of oranges, i. 334, 335, 336;</p> + <p class="i2">hybridisation of oranges, i. 336;</p> + <p class="i2">persistency of races in the peach, i. 339;</p> + <p class="i2">supposed specific distinctions of peach and nectarine, i. 340;</p> + <p class="i2">Bizzaria orange, i. 391;</p> + <p class="i2">crossing of red and white carnations, i. 393;</p> + <p class="i2">crossing of the orange and lemon, i. 399, ii. <a href="#page365">365</a>;</p> + <p class="i2">effect of foreign pollen on maize, i. 400;</p> + <p class="i2">spontaneous crossing of oranges, ii. <a href="#page91">91</a>;</p> + <p class="i2">monstrosities a cause of sterility in plants, ii. <a href="#page166">166</a>;</p> + <p class="i2">seeding of ordinarily seedless fruits, ii. <a href="#page168">168</a>;</p> + <p class="i2">sterility of the sugar cane, ii. <a href="#page169">169</a>;</p> + <p class="i2">tendency of male flowers to become double, ii. <a href="#page171">171</a>;</p> + <p class="i2">effects of selection in enlarging fruit, &c., ii. <a href="#page217">217</a>;</p> + <p class="i2">variation of the orange tree in North Italy, ii. <a href="#page256">256</a>;</p> + <p class="i2">naturalisation of the orange in Italy, ii. <a href="#page309">309</a>.</p> + <p><i>Gallus æneus</i>, a hybrid of <i>G. varius</i> and the domestic fowl, i. 235.</p> + <p><i>Gallus bankiva</i>, probable original of domestic fowls, i. 233, 236-239, 245;</p> + <p class="i2">game-fowl, nearest to, i. 226;</p> + <p class="i2">crossed with <i>G. Sonneratii</i>, i. 234;</p> + <p class="i2">its character and habits, i. 235-236, ii. <a href="#page109">109</a>;</p> + <p class="i2">differences of various breeds of fowls from, i. 260;</p> + <p class="i2">occipital foramen of, figured, i. 261;</p> + <p class="i2">skull of, figured, i. 262;</p> + <p class="i2">cervical vertebra of, figured, i. 267;</p> + <p class="i2">furcula of, figured, i. 268;</p> + <p class="i2">reversion to, in crossed fowls, ii. <a href="#page39">39</a>-<a href="#page40">40</a>;</p> + <p class="i2">hybrid of, with <i>G. varius</i>, i. 235, ii. <a href="#page40">40</a>;</p> + <p class="i2">number of eggs of, ii. <a href="#page112">112</a>.</p> + <p><i>Gallus ferrugineus</i>, i. 226.</p> + <p><i>Gallus furcatus</i>, i. 234.</p> + <p><i>Gallus giganteus</i>, i. 235.</p> + <p><i>Gallus Sonneratii</i>, characters and habits of, i. 233;</p> + <p class="i2">hybrids of, i. 234, ii. <a href="#page45">45</a>.</p> + <p><i>Gallus Stanleyi</i>, hybrids of, i. 234.</p> + <p><i>Gallus Temminckii</i>, probably a hybrid, i. 235.</p> + <p><i>Gallus varius</i>, character and habits of, i. 234;</p> + <p class="i2">hybrids and probable hybrids of, i. 234-235.</p> + <p><span class="sc">Gambier</span>, Lord, his early cultivation of the pansy, i. 368.</p> + <p><span class="sc">Game-fowl</span>, i. 226, 250, 251, 252.</p> + <p><span class="sc">Gapes</span>, ii. <a href="#page228">228</a>.</p> + <p><span class="sc">Garcilazo</span> de la Vega, annual hunts of the Peruvian Incas, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Garnett</span>, Mr., migratory propensities of hybrid ducks, ii. <a href="#page45">45</a>.</p> + <p><span class="sc">Garrod</span>, Dr., on hereditary gout, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Gasparini</span>, a genus of pumpkins, founded on stigmatic characters, i. 359.</p> + <p><span class="sc">Gaudichaud</span>, bud-variation in the pear, i. 376;</p> + <p class="i2">apple tree with two kinds of fruit on branch, i. 392.</p> + <p><span class="sc">Gaudry</span>, anomalous structure in the feet of horses, i. 50.</p> + <p><span class="sc">Gay</span>, on <i>Fragaria grandiflora</i>, i. 351;</p> + <p class="i2">on <i>Viola lutea</i> and <i>tricolor</i>, i. 368;</p> + <p class="i2">on the nectary of <i>Viola grandiflora</i>, i. 369.</p> + <p><span class="sc">Gayal</span>, domestication of the, i. 82.</p> + <p><span class="sc">Gayot</span>, <i>see</i> Moll.</p> + <p><span class="sc">Gärtner</span>, on the sterility of hybrids, i. 192, ii. <a href="#page101">101</a>;</p> + <p class="i2">acquired sterility of varieties of plants when crossed, i. 358;</p> + <p class="i2">sterility in transplanted plants, and in the lilac in Germany, ii. <a href="#page164">164</a>;</p> + <p class="i2">mutual sterility of blue and red flowers of the pimpernel, ii. <a href="#page190">190</a>;</p> + <p class="i2">supposed rules of transmission in crossing plants, ii. <a href="#page68">68</a>;</p> + <p class="i2">on crossing plants, ii. <a href="#page98">98</a>, <a href="#page127">127</a>, <a href="#page130">130</a>, <a href="#page131">131</a>;</p> + <p class="i2">on repeated crossing, ii. <a href="#page267">267</a>;</p> + <p class="i2">absorption of one species by another, when crossed, ii. <a href="#page88">88</a>;</p> + <p class="i2">crossing of varieties of the pea, i. 397;</p> + <p class="i2">crossing maize, ii. <a href="#page105">105</a>;</p> + <p class="i2">crossing of species of <i>Verbascum</i>, ii. <a href="#page93">93</a>, <a href="#page105">105</a>;</p> + <p class="i2">reversion in hybrids, ii. <a href="#page36">36</a>, <a href="#page49">49</a>, <a href="#page50">50</a>;</p> + <p class="i2">of <i>Cereus</i>, i. 392;</p> + <p class="i2">of <i>Tropæolum majus</i> and <i>minus</i>, i. 392;</p> + <p class="i2">variability of hybrids, ii. <a href="#page265">265</a>;</p> + <p class="i2">variable hybrids from one variable parent, ii. <a href="#page270">270</a>;</p> + <p class="i2">graft hybrid produced by inosculation in the vine, i. 395;</p> + <p class="i2">effect produced by grafts on the stock, i. 394, ii. <a href="#page278">278</a>;</p> + <p class="i2">tendency of hybrid plants to produce double flowers, ii. <a href="#page171">171</a>;</p> + <p class="i2">production of perfect fruit by sterile hybrids, ii. <a href="#page172">172</a>;</p> + <p class="i2">sexual elective affinity, ii. <a href="#page180">180</a>;</p> + <p class="i2">self-impotence in <i>Lobelia</i>, <i>Verbascum</i>, <i>Lilium</i>, and <i>Passiflora</i>, ii. <a href="#page136">136</a>-<a href="#page137">137</a>;</p> + <p class="i2">on the action of pollen, ii. <a href="#page108">108</a>;</p> + <p class="i2">fertilisation of <i>Malva</i>, i. 402-403, ii. <a href="#page363">363</a>;</p> + <p class="i2">prepotency of pollen, ii. <a href="#page187">187</a>;</p> + <p class="i2">prepotency of transmission in species of <i>Nicotiana</i>, ii. <a href="#page67">67</a>;</p> + <p class="i2">bud-variation in <i>Pelargonium zonale</i>, i. 375;</p> + <p class="i2">in <i>Œnothera biennis</i>, i. 382;</p> + <p class="i2">in <i>Achillæa millefolium</i>, i. 408;</p> + <p class="i2">effect of manure on the fertility of plants, ii. <a href="#page163">163</a>;</p> + <p class="i2">on contabescence, ii. <a href="#page165">165</a>-<a href="#page166">166</a>;</p> + <p class="i2">inheritance of plasticity, ii. <a href="#page241">241</a>;</p> + <p class="i2">villosity of plants, ii. <a href="#page277">277</a>.</p> + <p><span class="sc">Geese</span> (<i>anseres</i>) general fertility of, in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Gegenbaur</span>, on the number of digits, ii. <a href="#page13">13</a>.</p> + <p><span class="sc">Gemmation</span> and fission, ii. <a href="#page358">358</a>.</p> +<!-- Page 453 --><span class="pagenum"><a name="page453"></a>{453}</span> + <p><span class="sc">Gemmules</span>, or cell-gemmules, ii. <a href="#page374">374</a>, <a href="#page378">378</a>-<a href="#page381">381</a>, <a href="#page384">384</a>.</p> + <p><span class="sc">Genet</span>, fertility of the, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Generation</span>, alternate, ii. <a href="#page361">361</a>, <a href="#page367">367</a>, <a href="#page390">390</a>.</p> + <p><span class="sc">Generation</span>, sexual, ii. <a href="#page359">359</a>-<a href="#page364">364</a>.</p> + <p><span class="sc">Genius</span>, inheritance of, ii. <a href="#page7">7</a>.</p> + <p><i>Gentiana amarella</i>, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Geoffroy</span> Saint-Hilaire, production of monstrous chickens, ii. <a href="#page289">289</a>;</p> + <p class="i2">"<i>Loi de l'affinité de soi pour soi</i>," ii. <a href="#page339">339</a>;</p> + <p class="i2">compensation of growth, ii. <a href="#page342">342</a>.</p> + <p><span class="sc">Geoffroy</span> Saint-Hilaire, Isid., origin of the dog, i. 66;</p> + <p class="i2">barking of a jackal, i. 27;</p> + <p class="i2">period of gestation and odour of the jackal, i. 30;</p> + <p class="i2">anomalies in the teeth of dogs, i. 34;</p> + <p class="i2">variations in the proportions of dogs, i. 35;</p> + <p class="i2">webbed feet of Newfoundland dogs, i. 39;</p> + <p class="i2">crossing of domestic and wild cats, i. 44;</p> + <p class="i2">domestication of the arni, i. 82;</p> + <p class="i2">supposed introduction of cattle into Europe from the East, <i>ibid.</i>;</p> + <p class="i2">absence of interdigital pits in sheep, i. 95;</p> + <p class="i2">origin of the goat, i. 101;</p> + <p class="i2">feral geese, i. 190;</p> + <p class="i2">ancient history of the fowl, i. 246;</p> + <p class="i2">skull of the Polish fowl, i. 262;</p> + <p class="i2">preference of the Romans for the liver of white geese, i. 289;</p> + <p class="i2">polydactylism, ii. <a href="#page12">12</a>;</p> + <p class="i2">assumption of male characters by female birds, ii. <a href="#page51">51</a>;</p> + <p class="i2">supernumerary mammæ in women, ii. <a href="#page58">58</a>;</p> + <p class="i2">development of a proboscis in the pig, <i>ibid.</i>;</p> + <p class="i2">transmission and blending of characters in hybrids, ii. <a href="#page94">94</a>;</p> + <p class="i2">refusal of animals to breed in captivity, ii. <a href="#page149">149</a>;</p> + <p class="i2">on the Guinea pig, ii. <a href="#page152">152</a>;</p> + <p class="i2">silkworms producing white cocoons, ii. <a href="#page199">199</a>;</p> + <p class="i2">on the carp, ii. <a href="#page236">236</a>;</p> + <p class="i2">on <i>Helix lactea</i>, ii. <a href="#page280">280</a>;</p> + <p class="i2">on monstrosities, ii. <a href="#page254">254</a>;</p> + <p class="i2">injury to the embryo a cause of monstrosity, ii. <a href="#page269">269</a>;</p> + <p class="i2">alteration in the coat of horses in coal mines, ii. <a href="#page278">278</a>;</p> + <p class="i2">length of the intestines in wild and tame animals, ii. <a href="#page302">302</a>-<a href="#page303">303</a>;</p> + <p class="i2">inheritance of rudimentary limbs in the dog, ii. <a href="#page315">315</a>;</p> + <p class="i2">correlation in monstrosities, ii. <a href="#page320">320</a>;</p> + <p class="i2">supernumerary digits in man, ii. <a href="#page322">322</a>;</p> + <p class="i2">co-existence of anomalies, ii. <a href="#page331">331</a>;</p> + <p class="i2">fusion of homologous parts, ii. <a href="#page341">341</a>-<a href="#page342">342</a>;</p> + <p class="i2">presence of hairs and teeth in ovarian tumours, ii. <a href="#page370">370</a>;</p> + <p class="i2">development of teeth on the palate in the horse, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Geographical</span> differences of faunas, i. 10.</p> + <p><span class="sc">Geological</span> succession of organisms, i. 11.</p> + <p><i>Geranium</i>, ii. <a href="#page59">59</a>.</p> + <p><i>Geranium phæum</i> and <i>pyrenaicum</i>, ii. <a href="#page258">258</a>.</p> + <p><i>Geranium pratense</i>, i. 379.</p> + <p><span class="sc">Gerard</span>, asserted climatal change in Burgundian bees, i. 297.</p> + <p><span class="sc">Gerarde</span>, on varieties of the hyacinth, i. 370.</p> + <p><span class="sc">Gerstäcker</span>, on hive-bees, i. 299.</p> + <p><span class="sc">Gervais</span>, Prof., origin of the dog, i. 16;</p> + <p class="i2">resemblance of dogs and jackals, i. 24;</p> + <p class="i2">taming of the jackal, i. 26;</p> + <p class="i2">number of teeth in dogs, i. 34;</p> + <p class="i2">breeds of dogs, i. 36;</p> + <p class="i2">on tertiary horses, i. 51;</p> + <p class="i2">biblical notices of horses, i. 55;</p> + <p class="i2">species of <i>Ovis</i>, i. 94;</p> + <p class="i2">wild and domestic rabbits, i. 103;</p> + <p class="i2">rabbits from Mount Sinai and Algeria, i. 105;</p> + <p class="i2">earless rabbits, i. 108;</p> + <p class="i2">batrachia with doubled limbs, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Gestation</span>, period of, in the dog, wolf, &c, i. 29-30;</p> + <p class="i2">in the pig, i. 74;</p> + <p class="i2">in cattle, i. 87, ii. <a href="#page321">321</a>;</p> + <p class="i2">in sheep, i. 97.</p> + <p><span class="sc">Gestures</span>, inheritance of peculiarities in, ii. <a href="#page6">6</a>.</p> + <p>"<span class="sc">Ghoondooks</span>" a sub-breed of fowls, i. 229.</p> + <p><span class="sc">Ghor-Khur</span>, ii. <a href="#page42">42</a>.</p> + <p><span class="sc">Giles</span>, Mr., effect of cross-breeding in the pig, i. 404.</p> + <p><span class="sc">Giraffe</span>, co-ordination of structure of, ii. <a href="#page221">221</a>.</p> + <p><span class="sc">Girard</span>, period of appearance of permanent teeth in dogs, i. 35.</p> + <p><span class="sc">Girou</span> de Buzareingues, inheritance in the horse, ii. <a href="#page10">10</a>;</p> + <p class="i2">reversion by age in cattle, ii. <a href="#page38">38</a>;</p> + <p class="i2">prepotency of transmission of character in sheep and cattle, ii. <a href="#page66">66</a>;</p> + <p class="i2">on crossing gourds, ii. <a href="#page108">108</a>.</p> + <p><span class="sc">Gisburne</span>, wild cattle at, i. 84.</p> + <p><i>Gladiolus</i>, i. 364;</p> + <p class="i2">self-impotence of hybrids of, ii. <a href="#page139">139</a>.</p> + <p><i>Gladiolus colvillii</i>, bud-variation in, i. 382.</p> + <p><span class="sc">Glands</span>, compensatory development of, ii. <a href="#page300">300</a>.</p> + <p><span class="sc">Glastonbury</span> thorn, i. 364.</p> + <p><span class="sc">Glenny</span>, Mr., on the <i>Cineraria</i>, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Gloede</span>, F., on strawberries, i. 353.</p> + <p><span class="sc">Gloger</span>, on the wings of ducks, ii. <a href="#page298">298</a>.</p> + <p>"<span class="sc">Glouglou</span>" (pigeon), i. 154.</p> + <p><i>Gloxiniæ</i>, peloric, i. 365, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Gmelin</span>, on red cats, at Tobolsk, i. 47.</p> + <p><span class="sc">Goat</span>, i. 101-102, ii. <a href="#page33">33</a>;</p> + <p class="i2">polydactylism in the, ii. <a href="#page14">14</a>;</p> + <p class="i2">sexual differences in horns of, ii. <a href="#page73">73</a>;</p> + <p class="i2">valued by South Africans, ii. <a href="#page207">207</a>;</p> + <p class="i2">Thibet, ii. <a href="#page278">278</a>;</p> + <p class="i2">amount of milk and development of udders in the, ii. <a href="#page300">300</a>;</p> + <p class="i2">hornless, rudimentary bony cores in, ii. <a href="#page316">316</a>;</p> + <p class="i2">Angora, ii. <a href="#page326">326</a>.</p> + <p><span class="sc">Godron</span>, odour of the hairless Turkish dog, i. 30;</p> + <p class="i2">differences in the skull of dogs, i. 34;</p> + <p class="i2">increase of breeds of horses, i. 51;</p> + <p class="i2">crossing of domestic and wild swine, i. 66;</p> + <p class="i2">on goats, i. 101-102;</p> + <p class="i2">colour of the skin in fowls, i. 258;</p> + <p class="i2">bees of north and south of France, i. 297;</p> + <p class="i2">introduction of the silkworm into Europe, i. 300;</p> + <p class="i2">variability in the silkworm, i. 304;</p> + <p class="i2">supposed species of wheat, i. 312-314;</p> + <p class="i2">on <i>Ægilops triticoides</i>, i. 313;</p> + <p class="i2">variable presence of barbs in grasses, i. 314;</p> +<!-- Page 454 --><span class="pagenum"><a name="page454"></a>{454}</span> + <p class="i2">colours of the seeds of maize, i. 321;</p> + <p class="i2">unity of character in cabbages, i. 323;</p> + <p class="i2">correlation of colour and odour, i. 325;</p> + <p class="i2">effect of heat and moisture on the cabbage, i. 325;</p> + <p class="i2">on the cultivated species of <i>Brassica</i>, i. 325;</p> + <p class="i2">on the Rouncival and sugar peas, i. 327;</p> + <p class="i2">variation in the numbers of peas in the same pod, i. 328;</p> + <p class="i2">wild vines in Spain, i. 332;</p> + <p class="i2">on raising peaches from seed, i. 339;</p> + <p class="i2">supposed specific distinctness of peach and nectarine, i. 340;</p> + <p class="i2">nectarine producing peaches, i. 341;</p> + <p class="i2">on the flower of <i>Corydalis</i>, i. 344;</p> + <p class="i2">origin and variations of the plum, i. 345;</p> + <p class="i2">origin of the cherry, i. 347;</p> + <p class="i2">reversion of single-leaved strawberries, i. 353;</p> + <p class="i2">five-leaved variety of <i>Fragaria collina</i>, i. 353;</p> + <p class="i2">supposed immutability of specific characters, i. 358-359;</p> + <p class="i2">varieties of <i>Robinia</i>, i. 361;</p> + <p class="i2">permanency of the simple-leaved ash, i. 362;</p> + <p class="i2">non-inheritance of certain mutilations, ii. <a href="#page23">23</a>;</p> + <p class="i2">wild turnips, carrots, and celery, ii. <a href="#page33">33</a>;</p> + <p class="i2">pre-potency of a goat-like ram, ii. <a href="#page66">66</a>;</p> + <p class="i2">benefit of change of soil to plants, ii. <a href="#page146">146</a>;</p> + <p class="i2">fertility of peloric flowers of <i>Corydalis solida</i>, ii. <a href="#page167">167</a>;</p> + <p class="i2">seeding of ordinarily seedless fruit, ii. <a href="#page168">168</a>;</p> + <p class="i2">sexual sterility of plants propagated by buds, &c., ii. <a href="#page169">169</a>;</p> + <p class="i2">increase of sugar in beet-root, ii. <a href="#page201">201</a>;</p> + <p class="i2">effects of selection in enlarging particular parts of plants, ii. <a href="#page217">217</a>;</p> + <p class="i2">growth of the cabbage in the tropics, ii. <a href="#page277">277</a>;</p> + <p class="i2">rejection of bitter almonds by mice, ii. <a href="#page232">232</a>;</p> + <p class="i2">influence of marshy pasture on the fleece of sheep, ii. <a href="#page278">278</a>;</p> + <p class="i2">on the ears of ancient Egyptian pigs, ii. <a href="#page301">301</a>;</p> + <p class="i2">primitive distinctness of species, ii. <a href="#page415">415</a>;</p> + <p class="i2">solid hoofed swine, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Goethe</span>, on compensation of growth, ii. <a href="#page342">342</a>.</p> + <p><span class="sc">Goldfish</span>, i. 296-297, ii. <a href="#page236">236</a>.</p> + <p><span class="sc">Gomara</span>, on South American cats, i. 46.</p> + <p><span class="sc">Gongora</span>, number of seeds in the, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Goose</span>, ancient domestication of, i. 287;</p> + <p class="i2">sacred to Juno in Rome, <i>ibid.</i>;</p> + <p class="i2">inflexibility of organisation of, i. 288;</p> + <p class="i2">skull perforated in tufted, i. 288;</p> + <p class="i2">characters of breeds and sub-breeds of, i. 288-289;</p> + <p class="i2">variety of, from Sebastopol, i. 289, ii. <a href="#page392">392</a>;</p> + <p class="i2">feral in La Plata, i. 190;</p> + <p class="i2">Egyptian, hybrid of, with penguin duck, ii. <a href="#page68">68</a>;</p> + <p class="i2">spontaneous segregation of varieties of, ii. <a href="#page104">104</a>;</p> + <p class="i2">fertility of, increased by domestication, ii. <a href="#page112">112</a>;</p> + <p class="i2">decreased fertility of, in Bogota, ii. <a href="#page161">161</a>;</p> + <p class="i2">sterility of, in the Philippine Islands, ii. <a href="#page162">162</a>;</p> + <p class="i2">selection of, ii. <a href="#page204">204</a>;</p> + <p class="i2">white, preference of the Romans for the liver of, ii. <a href="#page209">209</a>;</p> + <p class="i2">persistency of character in, ii. <a href="#page254">254</a>;</p> + <p class="i2">Egyptian, change in breeding season of, ii. <a href="#page304">304</a>.</p> + <p><span class="sc">Gooseberry</span>, i. 354-356;</p> + <p class="i2">bud-variation in the, i. 376;</p> + <p class="i2">Whitesmith's, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Göppert</span>, on monstrous poppies, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Gosse</span>, P. H., feral dogs in Jamaica, i. 28;</p> + <p class="i2">feral pigs of Jamaica, i. 77-78;</p> + <p class="i2">feral rabbits of Jamaica, i. 112;</p> + <p class="i2">on <i>Columba leucocephala</i>, i. 183;</p> + <p class="i2">feral Guinea fowl in Jamaica, i. 190;</p> + <p class="i2">reproduction of individual peculiarities by gemmation in a coral, i. 374;</p> + <p class="i2">frequency of striped legs in mules, ii. <a href="#page42">42</a>.</p> + <p><span class="sc">Gould</span>, Dr., on hereditary hæmorrhage, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Gould</span>, John, origin of the turkey, i. 292.</p> + <p><i>Goura coronata</i> and <i>Victoriæ</i>, hybrids of, i. 194, ii. <a href="#page155">155</a>.</p> + <p><span class="sc">Gourds</span>, i. 357;</p> + <p class="i2">crossing of varieties of, ii. <a href="#page108">108</a>;</p> + <p class="i2">ancient Peruvian variety of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Gout</span>, inheritance of, ii. <a href="#page7">7</a>;</p> + <p class="i2">period of appearance of, ii. <a href="#page77">77</a>.</p> + <p><span class="sc">Graba</span>, on the pigeon of the Faroe islands, i. 183.</p> + <p><span class="sc">Grafting</span>, ii. <a href="#page147">147</a>;</p> + <p class="i2">effects of, ii. <a href="#page259">259</a>, <a href="#page278">278</a>;</p> + <p class="i2">upon the stock, i. 394-395;</p> + <p class="i2">upon the variability of trees, ii. <a href="#page259">259</a>;</p> + <p class="i2">changes analogous to bud-variation produced by, i. 387, 389.</p> + <p><span class="sc">Graft-hybrids</span>, i. 390-391, 394-397, ii. <a href="#page364">364</a>-<a href="#page365">365</a>.</p> + <p><span class="sc">Grapes</span>, bud-variation in, i. 375;</p> + <p class="i2">cross of white and purple, i. 393;</p> + <p class="i2">green, liable to disease, ii. <a href="#page336">336</a>;</p> + <p class="i2">effect of foreign pollen on, i. 400.</p> + <p><span class="sc">Grasses</span>, seeds of, used as food by savages, i. 307-309.</p> + <p><span class="sc">Gray</span>, Asa, superior wild varieties of fruit-trees, i. 310;</p> + <p class="i2">cultivated native plants of North America, i. 312, 357;</p> + <p class="i2">non-variation of weeds, i. 317;</p> + <p class="i2">supposed spontaneous crossing of pumpkins, i. 399;</p> + <p class="i2">pre-ordination of variation, ii. <a href="#page432">432</a>;</p> + <p class="i2">progeny of husked form of maize, i. 320;</p> + <p class="i2">wild intermediate forms of strawberries, i. 352.</p> + <p><span class="sc">Gray</span>, G. R., on <i>Columba gymnocyclus</i>, i. 184.</p> + <p><span class="sc">Gray</span>, J. E., on <i>Sus pliciceps</i>, i. 70;</p> + <p class="i2">on a variety of the gold-fish, i. 297;</p> + <p class="i2">hybrids of the ass and zebra, ii. <a href="#page42">42</a>-<a href="#page43">43</a>;</p> + <p class="i2">on the breeding of animals at Knowsley, ii. <a href="#page149">149</a>;</p> + <p class="i2">on the breeding of birds in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Greene</span>, J. Reay, on the development of the echinodermata, ii. <a href="#page367">367</a>.</p> + <p><span class="sc">Greenhow</span>, Mr., on a Canadian web-footed dog, i. 39.</p> + <p><span class="sc">Greening</span>, Mr., experiments on <i>Abraxas grossulariata</i>, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Gregson</span>, Mr., experiments on <i>Abraxas grossulariata</i>, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Grey</span>, Sir George, preservation of seed-bearing plants by the Australian savages, i. 310;</p> +<!-- Page 455 --><span class="pagenum"><a name="page455"></a>{455}</span> + <p class="i2">detestation of incest by Australian savages, ii. <a href="#page123">123</a>.</p> + <p><span class="sc">Greyhounds</span>, sculptured on Egyptian monuments, and in the Villa of Antoninus, i. 17;</p> + <p class="i2">modern breed of, i. 41;</p> + <p class="i2">crossed with the bulldog, by Lord Orford, ii. <a href="#page95">95</a>;</p> + <p class="i2">co-ordination of structure of, due to selection, ii. <a href="#page221">221</a>-<a href="#page222">222</a>;</p> + <p class="i2">Italian, ii. <a href="#page227">227</a>.</p> + <p><span class="sc">Greyness</span>, inherited at corresponding periods of life, ii. <a href="#page77">77</a>.</p> + <p><span class="sc">Grieve</span>, Mr., on early-flowering dahlias, i. 370.</p> + <p><span class="sc">Grigor</span>, Mr., acclimatisation of the Scotch fir, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Groom-Napier</span>, C. O., on the webbed feet of the otter-hound, i. 40.</p> + <p>"<span class="sc">Grosses-gorges</span>" (pigeons), i. 137.</p> + <p><span class="sc">Ground-tumbler</span>, Indian, i. 150.</p> + <p><span class="sc">Grouse</span>, fertility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Grönland</span>, hybrids of <i>Ægilops</i> and wheat, ii. <a href="#page110">110</a>.</p> + <p><i>Grus montigresia</i>, <i>cinerea</i>, and <i>Antigone</i>, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Guanacos</span>, selection of, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Guans</span>, general fertility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Guelder-rose</span>, ii. <a href="#page185">185</a>.</p> + <p><span class="sc">Guelderland</span> fowls, i. 230.</p> + <p><span class="sc">Guiana</span>, selection of dogs by the Indians of, ii. <a href="#page206">206</a>.</p> + <p><span class="sc">Guinea fowl</span>, i. 294;</p> + <p class="i2">feral in Ascension, and Jamaica, i. 190, ii. <a href="#page33">33</a>;</p> + <p class="i2">indifference of to change of climate, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Guinea</span> pig, ii. <a href="#page24">24</a>, <a href="#page152">152</a>.</p> + <p><span class="sc">Güldenstadt</span>, on the jackal, i. 25.</p> + <p><span class="sc">Gull</span>, herring, breeding in confinement, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Gulls</span>, general sterility of, in captivity, ii. <a href="#page157">157</a>.</p> + <p><i>Gulo</i>, sterility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Günther</span>, A., on tufted ducks and geese, i. 274;</p> + <p class="i2">on the regeneration of lost parts in batrachia, ii. <a href="#page15">15</a>.</p> + <p><span class="sc">Gurney</span>, Mr., owls breeding in captivity, ii. <a href="#page154">154</a>;</p> + <p class="i2">appearance of "black-shouldered" among ordinary peacocks, i. 291.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Habit</span>, influence of, in acclimatisation, ii. <a href="#page312">312</a>-<a href="#page315">315</a>.</p> + <p><span class="sc">Habits</span>, inheritance of, ii. <a href="#page395">395</a>.</p> + <p><span class="sc">Häckel</span>, on cells, ii. <a href="#page370">370</a>;</p> + <p class="i2">on the double reproduction of medusæ, ii. <a href="#page384">384</a>;</p> + <p class="i2">on inheritance, ii. <a href="#page397">397</a>.</p> + <p><span class="sc">Hackles</span>, peculiarities of, in fowls, i. 254.</p> + <p><span class="sc">Hair</span>, on the face, inheritance of, in man, ii. <a href="#page4">4</a>;</p> + <p class="i2">peculiar lock of, inherited, ii. <a href="#page5">5</a>;</p> + <p class="i2">growth of, under stimulation of skin, ii. <a href="#page326">326</a>;</p> + <p class="i2">homologous variation of, ii. <a href="#page325">325</a>;</p> + <p class="i2">development of, within the ears and in the brain, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Hair</span> and teeth, correlation of, ii. <a href="#page326">326</a>-<a href="#page328">328</a>.</p> + <p><span class="sc">Hairy</span> family, corresponding period of inheritance in, ii. <a href="#page77">77</a>.</p> + <p><span class="sc">Half-castes</span>, character of, ii. <a href="#page46">46</a>.</p> + <p><span class="sc">Half-lop</span> rabbits, figured and described, i. 107-108;</p> + <p class="i2">skull of, i. 119.</p> + <p><i>Haliætus leucocephalus</i>, copulating in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Hallam</span>, Col., on a two-legged race of pigs, ii. <a href="#page4">4</a>.</p> + <p><span class="sc">Hamburgh</span> fowl, i. 227, 261;</p> + <p class="i2">figured, i. 228.</p> + <p><span class="sc">Hamilton</span>, wild cattle of, i. 84.</p> + <p><span class="sc">Hamilton</span>, Dr., on the assumption of male plumage by the hen pheasant, ii. <a href="#page51">51</a>.</p> + <p><span class="sc">Hamilton</span>, F. Buchanan, on the shaddock, i. 335;</p> + <p class="i2">varieties of Indian cultivated plants, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Hancock</span>, Mr., sterility of tamed birds, ii. <a href="#page155">155</a>-<a href="#page157">157</a>.</p> + <p><span class="sc">Handwriting</span>, inheritance of peculiarities in, ii. <a href="#page6">6</a>.</p> + <p><span class="sc">Hanmer</span>, Sir J., on selection of flower seeds, ii. <a href="#page204">204</a>.</p> + <p><span class="sc">Hansell</span>, Mr., inheritance of dark yolks in duck's eggs, i. 281.</p> + <p><span class="sc">Harcourt</span>, E. V., on the Arab boar-hound, i. 17;</p> + <p class="i2">aversion of the Arabs to dun-coloured horses, i. 55.</p> + <p><span class="sc">Hardy</span>, Mr., effect of excess of nourishment on plants, ii. <a href="#page257">257</a>.</p> + <p><span class="sc">Hare</span>, hybrids of, with rabbit, i. 105;</p> + <p class="i2">sterility of the, in confinement, ii. <a href="#page152">152</a>;</p> + <p class="i2">preference of, for particular plants, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Hare-lip</span>, inheritance of, ii. <a href="#page24">24</a>.</p> + <p><span class="sc">Harlan</span>, Dr., on hereditary diseases, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Harmer</span>, Mr., on the number of eggs in a codfish, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Harvey</span>, Mr., monstrous red and white African bull, i. 91.</p> + <p><span class="sc">Harvey</span>, Prof., singular form of <i>Begonia frigida</i>, i. 365-366;</p> + <p class="i2">effects of cross-breeding on the female, i. 404;</p> + <p class="i2">monstrous saxifrage, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Hasora</span> wheat, i. 313.</p> + <p><span class="sc">Hautbois</span> strawberry, i. 353.</p> + <p><span class="sc">Hawker</span>, Col., on call or decoy ducks, i. 281.</p> + <p><span class="sc">Hawthorn</span>, varieties of, i. 360-364;</p> + <p class="i2">pyramidal, i. 361;</p> + <p class="i2">pendulous hybridised, ii. <a href="#page18">18</a>;</p> + <p class="i2">changes of, by age, i. 364, 387;</p> + <p class="i2">bud-variation in the, i. 377;</p> + <p class="i2">flower buds of, attacked by bullfinches, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Hayes</span>, Dr., character of Esquimaux dogs, i. 21-22.</p> + <p><span class="sc">Haywood</span>, W., on the feral rabbits of Porto Santo, i. 114.</p> + <p><span class="sc">Hazel</span>, purple-leaved, i. 362, 395, ii. <a href="#page330">330</a>.</p> + <p><span class="sc">Head</span> of wild boar and Yorkshire pig, figured, i. 72.</p> +<!-- Page 456 --><span class="pagenum"><a name="page456"></a>{456}</span> + <p><span class="sc">Head</span> and limbs, correlated variability of, ii. <a href="#page323">323</a>.</p> + <p><span class="sc">Headache</span>, inheritance of, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Heartsease</span>, i. 368-369;</p> + <p class="i2">change produced in the, by transplantation, i. 386;</p> + <p class="i2">reversion in, ii. <a href="#page31">31</a>, <a href="#page47">47</a>;</p> + <p class="i2">effects of selection on, ii. <a href="#page200">200</a>;</p> + <p class="i2">scorching of, ii. <a href="#page229">229</a>;</p> + <p class="i2">effects of seasonal conditions on the, ii. <a href="#page274">274</a>;</p> + <p class="i2">annual varieties of the, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Heat</span>, effect of, upon the fleece of sheep, i. 98.</p> + <p><span class="sc">Heber</span>, Bishop, on the breeding of the rhinoceros in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Hebrides</span>, cattle of the, i. 80;</p> + <p class="i2">pigeons of the, i. 183.</p> + <p><span class="sc">Heer</span>, O., on the plants of the Swiss lake-dwellings, i. 309, ii. <a href="#page215">215</a>, <a href="#page427">427</a>;</p> + <p class="i2">on the cereals, i. 317-319;</p> + <p class="i2">on the peas, i. 326;</p> + <p class="i2">on the vine growing in Italy in the bronze age, i. 332.</p> + <p><i>Helix lactea</i>, ii. <a href="#page280">280</a>.</p> + <p><i>Hemerocallis fulva</i> and <i>flava</i>, interchanging by bud-variation, i. 386.</p> + <p><span class="sc">Hemlock</span> yields no conicine in Scotland, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Hemp</span>, differences of, in various parts of India, ii. <a href="#page165">165</a>;</p> + <p class="i2">climatal difference in products of, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Hempseed</span>, effect of, upon the colour of birds, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Hermaphrodite</span> flowers, occurrence of, in Maize, i. 321.</p> + <p><span class="sc">Hen</span>, assumption of male characters by the, ii. <a href="#page51">51</a>, <a href="#page54">54</a>;</p> + <p class="i2">development of spurs in the, ii. <a href="#page318">318</a>.</p> + <p>"<span class="sc">Hennies</span>," or hen-like male fowls, i. 252.</p> + <p><span class="sc">Henry</span>, T. A., a variety of the ash produced by grafting, i. 394;</p> + <p class="i2">crossing of species of <i>Rhododendron</i> and <i>Arabis</i>, i. 400.</p> + <p><span class="sc">Henslow</span>, Prof., individual variation in wheat, i. 314;</p> + <p class="i2">bud-variation in the Austrian bramble rose, i. 381;</p> + <p class="i2">partial reproduction of the weeping ash by seed, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Hepatica</span>, changed by transplantation, i. 386.</p> + <p><span class="sc">Herbert</span>, Dr., variations of <i>Viola grandiflora</i>, i. 368;</p> + <p class="i2">bud-variation in camellias, i. 377;</p> + <p class="i2">seedlings from reverted <i>Cytisus Adami</i>, i. 388;</p> + <p class="i2">crosses of Swedish and other turnips, ii. <a href="#page93">93</a>;</p> + <p class="i2">on hollyhocks, ii. <a href="#page107">107</a>;</p> + <p class="i2">breeding of hybrids, ii. <a href="#page131">131</a>;</p> + <p class="i2">self-impotence in hybrid hippeastrums, ii. <a href="#page138">138</a>-<a href="#page139">139</a>;</p> + <p class="i2">hybrid <i>Gladiolus</i>, ii. <a href="#page139">139</a>;</p> + <p class="i2">on <i>Zephyranthes candida</i>, ii. <a href="#page164">164</a>;</p> + <p class="i2">fertility of the crocus, ii. <a href="#page165">165</a>;</p> + <p class="i2">on contabescence, ii. <a href="#page165">165</a>;</p> + <p class="i2">hybrid <i>Rhododendron</i>, ii. <a href="#page265">265</a>.</p> + <p><span class="sc">Herculaneum</span>, figure of a pig found in, i. 67.</p> + <p><span class="sc">Heron</span>, Sir R., appearance of "black-shouldered" among ordinary peacocks, i. 290-291;</p> + <p class="i2">non-inheritance of monstrous characters by goldfish, i. 296;</p> + <p class="i2">crossing of white and coloured Angora rabbits, ii. <a href="#page92">92</a>;</p> + <p class="i2">crosses of solid-hoofed pigs, ii. <a href="#page93">93</a>.</p> + <p><i>Herpestes fasciatus</i> and <i>griseus</i>, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Heusinger</span>, on the sheep of the Tarentino, ii. <a href="#page227">227</a>;</p> + <p class="i2">on correlated constitutional peculiarities, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Hewitt</span>, Mr., reversion in bantam cocks, i. 240;</p> + <p class="i2">degeneration of silk fowls, i. 243;</p> + <p class="i2">partial sterility of hen-like male fowls, i. 252;</p> + <p class="i2">production of tailed chickens by rumpless fowls, i. 259;</p> + <p class="i2">on taming and rearing wild ducks, i. 278-279, ii. <a href="#page233">233</a>, <a href="#page262">262</a>-<a href="#page263">263</a>;</p> + <p class="i2">conditions of inheritance in laced Sebright bantams, ii. <a href="#page22">22</a>;</p> + <p class="i2">reversion in rumpless fowls, ii. <a href="#page31">31</a>;</p> + <p class="i2">reversion in fowls by age, ii. <a href="#page39">39</a>;</p> + <p class="i2">hybrids of pheasant and fowl, ii. <a href="#page45">45</a>, <a href="#page68">68</a>;</p> + <p class="i2">assumption of male characters by female pheasants, ii. <a href="#page51">51</a>;</p> + <p class="i2">development of latent characters in a barren bantam hen, ii. <a href="#page54">54</a>;</p> + <p class="i2">mongrels from the silk-fowl, ii. <a href="#page67">67</a>;</p> + <p class="i2">effects of close interbreeding on fowls, ii. <a href="#page124">124</a>-<a href="#page125">125</a>;</p> + <p class="i2">on feathered-legged bantams, ii. <a href="#page323">323</a>.</p> + <p><span class="sc">Hibbert</span>, Mr., on the pigs of the Shetland Islands, i. 70.</p> + <p><span class="sc">Highland</span> cattle, descended from <i>Bos longifrons</i>, i. 81.</p> + <p><span class="sc">Hildebrand</span>, Dr., on the fertilisation of <i>Orchideæ</i>, i. 402-403;</p> + <p class="i2">occasional necessary crossing of plants, ii. <a href="#page90">90</a>;</p> + <p class="i2">on <i>Primula sinensis</i> and <i>Oxalis rosea</i>, ii. <a href="#page132">132</a>;</p> + <p class="i2">on <i>Corydalis cava</i>, ii. <a href="#page132">132</a>-<a href="#page133">133</a>.</p> + <p><span class="sc">Hill</span>, R., on the Alco, i. 31;</p> + <p class="i2">feral rabbits in Jamaica, i. 112;</p> + <p class="i2">feral peacocks in Jamaica, i. 190;</p> + <p class="i2">variation of the Guinea fowl in Jamaica, i. 294;</p> + <p class="i2">sterility of tamed birds in Jamaica, ii. <a href="#page155">155</a>, <a href="#page157">157</a>.</p> + <p><span class="sc">Himalaya</span>, range of gallinaceous birds in the, i. 237.</p> + <p><span class="sc">Himalayan</span> rabbit, i. 107, 108-111;</p> + <p class="i2">skull of, i. 120.</p> + <p><span class="sc">Himalayan</span> sheep, i. 95.</p> + <p><span class="sc">Hindmarsh</span>, Mr., on Chillingham cattle, i. 84.</p> + <p>"<span class="sc">Hinkel-Taube</span>," i. 142-143.</p> + <p><span class="sc">Hinny</span> and mule, difference of, ii. <a href="#page67">67</a>-<a href="#page68">68</a>.</p> + <p><i>Hipparion</i>, anomalous resemblance to in horses, i. 50.</p> + <p><i>Hippeastrum</i>, hybrids of, ii. <a href="#page138">138</a>-<a href="#page139">139</a>.</p> + <p><span class="sc">Hive-bees</span>, ancient domestication of, i. 297;</p> + <p class="i2">breeds of, i. 298;</p> + <p class="i2">smaller when produced in old combs, i. 297;</p> + <p class="i2">variability in, i. 298;</p> + <p class="i2">crossing of Ligurian and common, i. 299.</p> + <p>"<span class="sc">Hocker-Taube</span>," i. 141.</p> + <p><span class="sc">Hobbs</span>, Fisher, on interbreeding pigs, ii. <a href="#page121">121</a>.</p> + <p><span class="sc">Hodgkin</span>, Dr., on the attraction of foxes by a female Dingo, i. 31;</p> +<!-- Page 457 --><span class="pagenum"><a name="page457"></a>{457}</span> + <p class="i2">origin of the Newfoundland dog, i. 42;</p> + <p class="i2">transmission of a peculiar lock of hair, ii. <a href="#page5">5</a>.</p> + <p><span class="sc">Hodgson</span>, Mr., domestication of <i>Canis primævus</i>, i. 26;</p> + <p class="i2">development of a fifth digit in Thibet mastiffs, i. 35;</p> + <p class="i2">number of ribs in humped cattle, i. 79;</p> + <p class="i2">on the sheep of the Himalaya, i. 95;</p> + <p class="i2">presence of four mammæ in sheep, <i>ibid.</i>;</p> + <p class="i2">arched nose in sheep, i. 96;</p> + <p class="i2">measurements of the intestines of goats, i. 102;</p> + <p class="i2">presence of interdigital pits in goats, <i>ibid.</i>;</p> + <p class="i2">disuse a cause of drooping ears, ii. <a href="#page301">301</a>.</p> + <p><span class="sc">Hofacker</span>, persistency of colour in horses, i. 51, ii. <a href="#page21">21</a>;</p> + <p class="i2">production of dun horses from parents of different colours, i. 59;</p> + <p class="i2">inheritance of peculiarities in handwriting, ii. <a href="#page6">6</a>;</p> + <p class="i2">heredity in a one-horned stag, ii. <a href="#page12">12</a>;</p> + <p class="i2">on consanguineous marriages, ii. <a href="#page123">123</a>.</p> + <p><span class="sc">Hog</span>, Red River, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Hogg</span>, Mr., retardation of breeding in cows by hard living, ii. <a href="#page112">112</a>.</p> + <p><span class="sc">Holland</span>, Sir H., necessity of inheritance, ii. <a href="#page2">2</a>;</p> + <p class="i2">on hereditary diseases, ii. <a href="#page7">7</a>;</p> + <p class="i2">hereditary peculiarity in the eyelid, ii. <a href="#page8">8</a>;</p> + <p class="i2">morbid uniformity in the same family, ii. <a href="#page17">17</a>;</p> + <p class="i2">transmission of hydrocele through the female, ii. <a href="#page52">52</a>;</p> + <p class="i2">inheritance of habits and tricks, ii. <a href="#page395">395</a>.</p> + <p><span class="sc">Holly</span>, varieties of the, i. 360, 362;</p> + <p class="i2">bud-reversion in, i. 384;</p> + <p class="i2">yellow-berried, ii. <a href="#page19">19</a>, <a href="#page230">230</a>.</p> + <p><span class="sc">Hollyhock</span>, bud-variation in, i. 378;</p> + <p class="i2">non-crossing of double varieties of, ii. <a href="#page107">107</a>;</p> + <p class="i2">tender variety of the, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Homer</span>, notice of Geese, i. 287;</p> + <p class="i2">breeding of the horses of Æneas, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Homologous</span> parts, correlated variability of, ii. <a href="#page322">322</a>-<a href="#page331">331</a>, <a href="#page354">354</a>-<a href="#page355">355</a>;</p> + <p class="i2">fusion of, ii. <a href="#page393">393</a>;</p> + <p class="i2">affinity of, ii. <a href="#page339">339</a>-<a href="#page342">342</a>.</p> + <p><span class="sc">Hoofs</span>, correlated with hair in variation, ii. <a href="#page325">325</a>.</p> + <p><span class="sc">Hook-billed duck</span>, skull figured, i. 282.</p> + <p><span class="sc">Hooker</span>, Dr. J. D., forked shoulder-stripe in Syrian asses, i. 63;</p> + <p class="i2">voice of the cock in Sikkim, i. 259;</p> + <p class="i2">use of Arum-roots as food, i. 307;</p> + <p class="i2">native useful plants of Australia, i. 311;</p> + <p class="i2">wild walnut of the Himalayas, i. 356;</p> + <p class="i2">variety of the plane tree, i. 362;</p> + <p class="i2">production of <i>Thuja orientalis</i> from seeds of <i>T. pendula</i>, i. 362;</p> + <p class="i2">singular form of <i>Begonia frigida</i>, i. 365;</p> + <p class="i2">reversion in plants run wild, ii. <a href="#page33">33</a>;</p> + <p class="i2">on the sugar-cane, ii. <a href="#page169">169</a>;</p> + <p class="i2">on Arctic plants, ii. <a href="#page256">256</a>;</p> + <p class="i2">on the oak grown at the Cape of Good Hope, ii. <a href="#page274">274</a>;</p> + <p class="i2">on <i>Rhododendron ciliatum</i>, ii. <a href="#page277">277</a>;</p> + <p class="i2">stock and mignonette, perennial in Tasmania, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Hopkirk</span>, Mr., bud-variation in the rose, i. 381;</p> + <p class="i2">in <i>Mirabilis jalapa</i>, i. 382;</p> + <p class="i2">in <i>Convolvulus tricolor</i>, i. 408.</p> + <p><span class="sc">Hornbeam</span>, heterophyllous, i. 362.</p> + <p><span class="sc">Horned</span> fowl, i. 229;</p> + <p class="i2">skull figured, i. 265.</p> + <p><span class="sc">Hornless</span> cattle in Paraguay, i. 89.</p> + <p><span class="sc">Horns</span> of sheep, i. 95;</p> + <p class="i2">correlation of, with fleece in sheep, ii. <a href="#page326">326</a>;</p> + <p class="i2">correlation of, with the skull, ii. <a href="#page333">333</a>;</p> + <p class="i2">rudimentary in young polled cattle, ii. <a href="#page315">315</a>;</p> + <p class="i2">of goats, i. 102.</p> + <p><span class="sc">Horses</span>, in Swiss lake-dwellings, i. 49;</p> + <p class="i2">different breeds of, in Malay Archipelago, i. 49;</p> + <p class="i2">anomalies in osteology and dentition of, i. 50;</p> + <p class="i2">mutual fertility of different breeds, i. 51;</p> + <p class="i2">feral, i. 51;</p> + <p class="i2">habit of scraping away snow, i. 53;</p> + <p class="i2">mode of production of breeds of, i. 54;</p> + <p class="i2">inheritance and diversity of colour in, i. 55;</p> + <p class="i2">dark stripes in, i. 56-61, ii. <a href="#page351">351</a>;</p> + <p class="i2">dun-coloured, origin of, i. 59;</p> + <p class="i2">colours of feral, i. 60-61;</p> + <p class="i2">effect of fecundation by a Quagga on the subsequent progeny of, i. 403-404;</p> + <p class="i2">inheritance of peculiarities in, ii. <a href="#page10">10</a>-<a href="#page11">11</a>;</p> + <p class="i2">polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">inheritance of colour in, ii. <a href="#page21">21</a>;</p> + <p class="i2">inheritance of exostoses in legs of, ii. <a href="#page23">23</a>;</p> + <p class="i2">reversion in, ii. <a href="#page33">33</a>, <a href="#page41">41</a>;</p> + <p class="i2">hybrids of, with ass and zebra, ii. <a href="#page42">42</a>;</p> + <p class="i2">prepotency of transmission in the sexes of, ii. <a href="#page65">65</a>;</p> + <p class="i2">segregation of, in Paraguay, ii. <a href="#page102">102</a>;</p> + <p class="i2">wild species of, breeding in captivity, ii. <a href="#page150">150</a>;</p> + <p class="i2">curly, in Paraguay, ii. <a href="#page205">205</a>, <a href="#page325">325</a>;</p> + <p class="i2">selection of, for trifling characters, ii. <a href="#page209">209</a>;</p> + <p class="i2">unconscious selection of, ii. <a href="#page212">212</a>-<a href="#page213">213</a>;</p> + <p class="i2">natural selection in Circassia, ii. <a href="#page225">225</a>;</p> + <p class="i2">alteration of coat of, in coal-mines, ii. <a href="#page278">278</a>;</p> + <p class="i2">degeneration of, in the Falkland Islands, ii. <a href="#page278">278</a>;</p> + <p class="i2">diseases of, caused by shoeing, ii. <a href="#page300">300</a>;</p> + <p class="i2">feeding on meat, ii. <a href="#page305">305</a>;</p> + <p class="i2">white and white-spotted, poisoned by mildewed vetches, ii. <a href="#page337">337</a>;</p> + <p class="i2">analogous variations in the colour of, ii. <a href="#page349">349</a>;</p> + <p class="i2">teeth developed on palate of, ii. <a href="#page391">391</a>;</p> + <p class="i2">of bronze period in Denmark, ii. <a href="#page427">427</a>.</p> + <p><span class="sc">Horse-chesnut</span>, early, at the Tuileries, i. 362;</p> + <p class="i2">tendency to doubleness in, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Horse-radish</span>, general sterility of the, ii. <a href="#page170">170</a>.</p> + <p>"<span class="sc">Houdan</span>," a French sub-breed of fowls, i. 229.</p> + <p><span class="sc">Howard</span>, C., on an Egyptian monument, i. 17;</p> + <p class="i2">on crossing sheep, ii. <a href="#page95">95</a>, <a href="#page120">120</a>.</p> + <p><span class="sc">Huc</span>, on the Emperor Khang-hi, ii. <a href="#page205">205</a>;</p> + <p class="i2">Chinese varieties of the bamboo, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Humboldt</span>, A., character of the Zambos, ii. <a href="#page47">47</a>;</p> + <p class="i2">parrot speaking the language of an extinct tribe, ii. <a href="#page154">154</a>;</p> + <p class="i2">on <i>Pulex penetrans</i>, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Humidity</span>, injurious effect of, upon horses, i. 53.</p> + <p><span class="sc">Humphreys</span>, Col., on Ancon sheep, i. 100.</p> + <p><span class="sc">Hungarian</span> cattle, i. 80.</p> +<!-- Page 458 --><span class="pagenum"><a name="page458"></a>{458}</span> + <p><span class="sc">Hunter</span>, John, period of gestation in the dog, i. 29;</p> + <p class="i2">on secondary sexual characters, i. 179;</p> + <p class="i2">fertile crossing of <i>Anser ferus</i> and the domestic goose, i. 288;</p> + <p class="i2">inheritance of peculiarities in gestures, voice, &c., ii. <a href="#page6">6</a>;</p> + <p class="i2">assumption of male characters by the human female, ii. <a href="#page51">51</a>;</p> + <p class="i2">period of appearance of hereditary diseases, ii. <a href="#page78">78</a>;</p> + <p class="i2">graft of the spur of a cock upon its comb, ii. <a href="#page296">296</a>;</p> + <p class="i2">on the stomach of <i>Larus tridentatus</i>, ii. <a href="#page302">302</a>;</p> + <p class="i2">double-tailed lizards, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Hunter</span>, W., evidence against the influence of imagination upon the offspring, ii. <a href="#page264">264</a>.</p> + <p><span class="sc">Hutton</span>, Capt., on the variability of the silk moth, i. 303;</p> + <p class="i2">on the number of species of silkworms, i. 300;</p> + <p class="i2">markings of silkworms, i. 302;</p> + <p class="i2">domestication of the rock-pigeon in India, i. 185;</p> + <p class="i2">domestication and crossing of <i>Gallus bankiva</i>, i. 236.</p> + <p><span class="sc">Hutchinson</span>, Col., liability of dogs to distemper, i. 35.</p> + <p><span class="sc">Huxley</span>, Prof., on the transmission of polydactylism, ii. <a href="#page13">13</a>;</p> + <p class="i2">on unconscious selection, ii. <a href="#page194">194</a>;</p> + <p class="i2">on correlation in the mollusca, ii. <a href="#page320">320</a>;</p> + <p class="i2">on gemmation and fission, ii. <a href="#page359">359</a>;</p> + <p class="i2">development of star-fishes, ii. <a href="#page366">366</a>.</p> + <p><span class="sc">Hyacinths</span>, i. 370-371;</p> + <p class="i2">bud-variation in, i. 385;</p> + <p class="i2">graft-hybrid by union of half bulbs of, i. 395;</p> + <p class="i2">white, reproduced by seed, ii. <a href="#page20">20</a>;</p> + <p class="i2">red, ii. <a href="#page229">229</a>, <a href="#page336">336</a>;</p> + <p class="i2">varieties of, recognisable by the bulb, ii. <a href="#page251">251</a>.</p> + <p><span class="sc">Hyacinth</span>, feather, ii. <a href="#page185">185</a>, <a href="#page316">316</a>.</p> + <p><i>Hyacinthus orientalis</i>, i. 370.</p> + <p><i>Hybiscus syriacus</i>, ii. <a href="#page286">286</a>.</p> + <p><span class="sc">Hybrids</span>, of hare and rabbit, i. 105;</p> + <p class="i2">of various species of <i>Gallus</i>, i. 234-236;</p> + <p class="i2">of almond, peach, and nectarine, i. 339;</p> + <p class="i2">naturally produced, of species of <i>Cytisus</i>, i. 390;</p> + <p class="i2">from twin-seed of <i>Fuchsia coccinea</i> and <i>fulgens</i>, i. 391;</p> + <p class="i2">reversion of, i. 392-394, ii. <a href="#page36">36</a>, <a href="#page48">48</a>-<a href="#page50">50</a>;</p> + <p class="i2">from mare, ass, and zebra, ii. <a href="#page42">42</a>;</p> + <p class="i2">of tame animals, wildness of, ii. <a href="#page44">44</a>-<a href="#page46">46</a>;</p> + <p class="i2">female instincts of sterile male, ii. <a href="#page52">52</a>;</p> + <p class="i2">transmission and blending of characters in, ii. <a href="#page92">92</a>-<a href="#page95">95</a>;</p> + <p class="i2">breed better with parent species than with each other, ii. <a href="#page131">131</a>;</p> + <p class="i2">self-impotence in, ii. <a href="#page138">138</a>-<a href="#page140">140</a>;</p> + <p class="i2">readily produced in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Hybridisation</span>, singular effects of, in oranges, i. 336;</p> + <p class="i2">of cherries, i. 347;</p> + <p class="i2">difficulty of, in <i>Cucurbitæ</i>, i. 358;</p> + <p class="i2">of roses, i. 366.</p> + <p><span class="sc">Hybridism</span>, ii. <a href="#page178">178</a>-<a href="#page191">191</a>;</p> + <p class="i2">the cause of a tendency to double flowers, ii. <a href="#page171">171</a>;</p> + <p class="i2">in relation to pangenesis, ii. <a href="#page385">385</a>.</p> + <p><span class="sc">Hybridity</span> in cats, i. 44-45;</p> + <p class="i2">supposed of peach and nectarine, i. 342.</p> + <p><i>Hydra</i>, i. 374, ii. <a href="#page293">293</a>, <a href="#page359">359</a>.</p> + <p><span class="sc">Hydrangea</span>, colour of flowers of, influenced by alum, ii. <a href="#page277">277</a>.</p> + <p><span class="sc">Hydrocele</span>, ii. <a href="#page52">52</a>.</p> + <p><span class="sc">Hydrocephalus</span>, ii. <a href="#page295">295</a>.</p> + <p><i>Hypericum calycinum</i>, ii. <a href="#page170">170</a>.</p> + <p><i>Hypericum crispum</i>, ii. <a href="#page227">227</a>, <a href="#page337">337</a>.</p> + <p><span class="sc">Hypermetamorphosis</span>, ii. <a href="#page367">367</a>.</p> + <p><span class="sc">Hypermetropia</span>, hereditary, ii. <a href="#page8">8</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Ichthyopterygia</span>, number of digits in the, ii. <a href="#page16">16</a>.</p> + <p><i>Ilex aquifolium</i>, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Imagination</span>, supposed effect of, on offspring, ii. <a href="#page263">263</a>.</p> + <p><i>Imatophyllum miniatum</i>, bud-variation in, i. 385.</p> + <p><span class="sc">Incest</span>, abhorred by savages, ii. <a href="#page123">123</a>-<a href="#page124">124</a>.</p> + <p><span class="sc">Incubation</span>, by crossed fowls of non-sitting varieties, ii. <a href="#page43">43</a>-<a href="#page44">44</a>.</p> + <p><span class="sc">India</span>, striped horses of, i. 58;</p> + <p class="i2">pigs of, i. 66, 67, 76;</p> + <p class="i2">breeding of rabbits in, i. 112;</p> + <p class="i2">cultivation of pigeons in, i. 205-206.</p> + <p><span class="sc">Individual</span> variability in pigeons, i. 158-160.</p> + <p><span class="sc">Ingledew</span>, Mr., cultivation of European vegetables in India, ii. <a href="#page169">169</a>.</p> + <p>"<span class="sc">Indische</span> Taube," ii. <a href="#page144">144</a>.</p> + <p><span class="sc">Inheritance</span>, ii. <a href="#page1">1</a>-<a href="#page84">84</a>, <a href="#page371">371</a>-<a href="#page373">373</a>, <a href="#page395">395</a>, <a href="#page397">397</a>-<a href="#page402">402</a>;</p> + <p class="i2">doubts entertained of by some writers, ii. <a href="#page3">3</a>;</p> + <p class="i2">importance of to breeders, <a href="#page3">3</a>-<a href="#page4">4</a>;</p> + <p class="i2">evidence of, derived from statistics of chances, <a href="#page5">5</a>;</p> + <p class="i2">of peculiarities in man, <a href="#page5">5</a>-<a href="#page7">7</a>, <a href="#page12">12</a>-<a href="#page16">16</a>;</p> + <p class="i2">of disease, <a href="#page7">7</a>-<a href="#page8">8</a>, <a href="#page17">17</a>;</p> + <p class="i2">of peculiarities in the eye, <a href="#page8">8</a>-<a href="#page10">10</a>;</p> + <p class="i2">of deviations from symmetry, <a href="#page12">12</a>;</p> + <p class="i2">of polydactylism, <a href="#page12">12</a>-<a href="#page16">16</a>;</p> + <p class="i2">capriciousness of, <a href="#page17">17</a>-<a href="#page22">22</a>, <a href="#page27">27</a>;</p> + <p class="i2">of mutilations, <a href="#page22">22</a>-<a href="#page24">24</a>;</p> + <p class="i2">of congenital monstrosities, <a href="#page24">24</a>;</p> + <p class="i2">causes of absence of, <a href="#page24">24</a>-<a href="#page26">26</a>;</p> + <p class="i2">by reversion or atavism, <a href="#page28">28</a>-<a href="#page61">61</a>;</p> + <p class="i2">its connexion with fixedness of character, <a href="#page62">62</a>-<a href="#page64">64</a>;</p> + <p class="i2">affected by prepotency of transmission of character, <a href="#page65">65</a>-<a href="#page71">71</a>;</p> + <p class="i2">limited by sex, <a href="#page71">71</a>-<a href="#page75">75</a>;</p> + <p class="i2">at corresponding periods of life, <a href="#page75">75</a>-<a href="#page80">80</a>;</p> + <p class="i2">summary of the subject of, <a href="#page80">80</a>-<a href="#page84">84</a>;</p> + <p class="i2">laws of, the same in seminal and bud varieties, i. 409;</p> + <p class="i2">of characters in the horse, i. 10-11;</p> + <p class="i2">in cattle, i. 87;</p> + <p class="i2">in rabbits, i. 107;</p> + <p class="i2">in the peach, i. 339;</p> + <p class="i2">in the nectarine, i. 340;</p> + <p class="i2">in plums, i. 347;</p> + <p class="i2">in apples, i. 350;</p> + <p class="i2">in pears, i. 351;</p> + <p class="i2">in the pansy, i. 369;</p> + <p class="i2">of primary characters of <i>Columba livia</i> in crossed pigeons, i. 201;</p> + <p class="i2">of peculiarities of plumage in pigeons, i. 160-161;</p> + <p class="i2">of peculiarities of foliage in trees, i. 362;</p> + <p class="i2">effects of, in varieties of the cabbage, i. 325.</p> + <p><span class="sc">Insanity</span>, inheritance of, ii. <a href="#page7">7</a>, <a href="#page78">78</a>.</p> + <p><span class="sc">Insects</span>, regeneration of lost parts in, ii. <a href="#page15">15</a>, <a href="#page294">294</a>;</p> + <p class="i2">agency of, in fecundation of larkspurs, ii. <a href="#page21">21</a>;</p> + <p class="i2">effect of changed conditions upon, ii. <a href="#page157">157</a>;</p> + <p class="i2">sterile neuter, ii. <a href="#page186">186</a>-<a href="#page187">187</a>;</p> +<!-- Page 459 --><span class="pagenum"><a name="page459"></a>{459}</span> + <p class="i2">monstrosities in, ii. <a href="#page269">269</a>, <a href="#page391">391</a>.</p> + <p><span class="sc">Instincts</span>, defective, of silkworms, i. 304.</p> + <p><span class="sc">Interbreeding</span>, close, ill effects of, ii. <a href="#page114">114</a>-<a href="#page131">131</a>, <a href="#page175">175</a>.</p> + <p><span class="sc">Intercrossing</span>, of species, as a cause of variation, i. 188;</p> + <p class="i2">natural, of plants, i. 336;</p> + <p class="i2">of species of Canidæ and breeds of dogs, i. 31-33;</p> + <p class="i2">of domestic and wild cats, i. 44-45;</p> + <p class="i2">of breeds of pigs, i. 71, 78;</p> + <p class="i2">of cattle, i. 83;</p> + <p class="i2">of varieties of cabbage, i. 324;</p> + <p class="i2">of peas, i. 326, 329-330;</p> + <p class="i2">of varieties of orange, i. 336;</p> + <p class="i2">of species of strawberries, i. 351-352;</p> + <p class="i2">of <i>Cucurbitæ</i>, i. 357-358;</p> + <p class="i2">of flowering plants, i. 364;</p> + <p class="i2">of pansies, i. 368.</p> + <p><span class="sc">Interdigital</span> pits, in goats, i. 102.</p> + <p><span class="sc">Intermarriages</span>, close, ii. <a href="#page122">122</a>-<a href="#page123">123</a>.</p> + <p><span class="sc">Intestines</span>, elongation of, in pigs, i. 73;</p> + <p class="i2">relative measurements of parts of, in goats, i. 102;</p> + <p class="i2">effects of changed diet on, ii. <a href="#page302">302</a>.</p> + <p><i>Ipomœa purpurea</i>, ii. <a href="#page128">128</a>.</p> + <p><span class="sc">Ireland</span>, remains of <i>Bos frontosus</i> and <i>longifrons</i> found in, i. 81.</p> + <p><span class="sc">Iris</span>, hereditary absence of the, ii. <a href="#page9">9</a>;</p> + <p class="i2">hereditary peculiarities of colour of the, ii. <a href="#page9">9</a>-<a href="#page10">10</a>.</p> + <p><span class="sc">Irish</span>, ancient, selection practised by the, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Iron</span> period, in Europe, dog of, i. 18.</p> + <p><span class="sc">Islands</span>, oceanic, scarcity of useful plants on, i. 311.</p> + <p><span class="sc">Islay</span>, pigeons of, i. 183.</p> + <p><span class="sc">Isolation</span>, effect of, in favour of selection, ii. <a href="#page233">233</a>-<a href="#page234">234</a>.</p> + <p><span class="sc">Italy</span>, vine growing in, during the bronze period, i. 332.</p> + <p><span class="sc">Ivy</span>, sterility of, in the north of Europe, ii. <a href="#page170">170</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Jack</span>, Mr., effect of foreign pollen on grapes, i. 400.</p> + <p><span class="sc">Jackal</span>, i. 24, 27, 30;</p> + <p class="i2">hybrids of, with the dog, i. 32;</p> + <p class="i2">prepotency of, over the dog, ii. <a href="#page67">67</a>.</p> + <p><span class="sc">Jacobin</span> pigeon, i. 154, 208.</p> + <p><span class="sc">Jacquemet-Bonnefort</span>, on the mulberry, i. 334.</p> + <p><span class="sc">Jaguar</span>, with crooked legs, i. 17.</p> + <p><span class="sc">Jamaica</span>, feral dogs of, i. 28;</p> + <p class="i2">feral pigs of, i. 77;</p> + <p class="i2">feral rabbits of, i. 112.</p> + <p><span class="sc">Japan</span>, horses of, i. 53.</p> + <p><span class="sc">Japanese</span> pig (figured), i. 69.</p> + <p><span class="sc">Jardine</span>, Sir W., crossing of domestic and wild cats, i. 44.</p> + <p><span class="sc">Jarves</span>, J., silkworm in the Sandwich islands, i. 301.</p> + <p><span class="sc">Java</span>, Fantail pigeon in, i. 148.</p> + <p><span class="sc">Javanese</span> ponies, i. 53, 59.</p> + <p><span class="sc">Jemmy Button</span>, i. 309.</p> + <p><span class="sc">Jenyns</span>, L., whiteness of ganders, i. 288;</p> + <p class="i2">sunfish-like variety of the goldfish, i. 297.</p> + <p><span class="sc">Jerdon</span>, J. C., number of eggs laid by the pea-hen, ii. <a href="#page112">112</a>;</p> + <p class="i2">origin of domestic fowl, i. 237.</p> + <p><span class="sc">Jersey</span>, arborescent cabbages of, i. 323.</p> + <p><span class="sc">Jessamine</span>, i. 394.</p> + <p><span class="sc">Jeitteles</span>, Hungarian sheep-dogs, i. 24;</p> + <p class="i2">crossing of domestic and wild cats, i. 44.</p> + <p><span class="sc">John</span>, King, importation of stallions from Flanders by, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Johnson</span>, D., occurrence of stripes on young wild pigs in India, i. 76.</p> + <p><span class="sc">Jordan</span>, A., on Vibert's experiments on the vine, i. 332;</p> + <p class="i2">origin of varieties of the apple, i. 350;</p> + <p class="i2">varieties of pears found wild in woods, ii. <a href="#page260">260</a>.</p> + <p><span class="sc">Jourdan</span>, parthenogenesis in the silk moth, ii. <a href="#page364">364</a>.</p> + <p><span class="sc">Juan de Nova</span>, wild dogs on, i. 27.</p> + <p><span class="sc">Juan Fernandez</span>, dumb dogs on, i. 27.</p> + <p><i>Juglans regia</i>, i. 356-357.</p> + <p><span class="sc">Jukes</span>, Prof., origin of the Newfoundland dog, i. 42.</p> + <p><span class="sc">Julien</span>, Stanislas, early domestication of pigs in China, i. 68;</p> + <p class="i2">antiquity of the domestication of the silk-worm in China, i. 300.</p> + <p><span class="sc">Jumpers</span>, a breed of fowls, i. 230.</p> + <p><span class="sc">Juniper</span>, variations of the, i. 361, 364.</p> + <p><i>Juniperus suecica</i>, i. 361.</p> + <p><i>Jussiæa grandiflora</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Jussieu</span>, A. de, structure of the pappus in <i>Carthamus</i>, ii. <a href="#page316">316</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Kail</span>, Scotch, reversion in, ii. <a href="#page32">32</a>.</p> + <p>"<span class="sc">Kala-par</span>" pigeon, i. 142.</p> + <p><span class="sc">Kales</span>, i. 323.</p> + <p><span class="sc">Kalm</span>, P., on maize, i. 322, ii. <a href="#page307">307</a>;</p> + <p class="i2">introduction of wheat into Canada, i. 315;</p> + <p class="i2">sterility of trees growing in marshes and dense woods, ii. <a href="#page170">170</a>.</p> + <p>"<span class="sc">Kalmi</span> Lotan," tumbler pigeon, i. 151.</p> + <p><span class="sc">Kane</span>, Dr., on Esquimaux dogs, i. 21.</p> + <p><span class="sc">Karakool</span> sheep, i. 98.</p> + <p><span class="sc">Karkeek</span>, on inheritance in the horse, ii. <a href="#page10">10</a>.</p> + <p>"<span class="sc">Karmeliten</span> Taube," i. 156.</p> + <p><span class="sc">Karsten</span> on <i>Pulex penetrans</i>, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Kattywar</span> horses, i. 58.</p> + <p><span class="sc">Keeley</span>, R., pelorism in <i>Galeobdolon luteum</i>, ii. <a href="#page59">59</a>.</p> + <p><span class="sc">Kerner</span> on the culture of Alpine plants, ii. <a href="#page163">163</a>.</p> + <p><span class="sc">Kestrel</span>, breeding in captivity, ii. <a href="#page154">154</a>.</p> + <p>"<span class="sc">Khandési</span>," i. 141.</p> + <p><span class="sc">Khang-hi</span>, selection of a variety of rice by, ii. <a href="#page205">205</a>.</p> + <p><span class="sc">Kiang</span>, ii. <a href="#page43">43</a>.</p> + <p><span class="sc">Kidd</span>, on the canary bird, i. 77, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Kidney</span> Bean, i. 371;</p> + <p class="i2">varieties of, ii. <a href="#page256">256</a>, <a href="#page275">275</a>.</p> +<!-- Page 460 --><span class="pagenum"><a name="page460"></a>{460}</span> + <p><span class="sc">Kidneys</span>, compensatory development of the, ii. <a href="#page300">300</a>;</p> + <p class="i2">fusion of the, ii. <a href="#page341">341</a>;</p> + <p class="i2">shape of, in birds, influenced by the form of the pelvis, ii. <a href="#page344">344</a>.</p> + <p><span class="sc">King</span>, Col., domestication of rock doves from the Orkneys, i. 184, 185.</p> + <p><span class="sc">King</span>, P. S., on the Dingo, i. 21, 28.</p> + <p><span class="sc">Kirby</span> and Spence, on the growth of galls, ii. <a href="#page283">283</a>.</p> + <p><span class="sc">Kirghisian</span> sheep, i. 98.</p> + <p><span class="sc">Kite</span>, breeding in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Kleine</span>, variability of bees, i. 298.</p> + <p><span class="sc">Knight</span>, Andrew, on crossing horses of different breeds, i. 51;</p> + <p class="i2">crossing varieties of peas, i. 326, ii. <a href="#page129">129</a>;</p> + <p class="i2">persistency of varieties of peas, i. 329;</p> + <p class="i2">origin of the peach, i. 338;</p> + <p class="i2">hybridisation of the morello by the Elton cherry, i. 347;</p> + <p class="i2">on seedling cherries, <i>ibid.</i>;</p> + <p class="i2">variety of the apple not attacked by coccus, i. 349;</p> + <p class="i2">intercrossing of strawberries, i, 351, 352;</p> + <p class="i2">broad variety of the cock's comb, i. 365;</p> + <p class="i2">bud variation in the cherry and plum, i. 375;</p> + <p class="i2">crossing of white and purple grapes, i. 393;</p> + <p class="i2">experiments in crossing apples, i. 402, ii. <a href="#page129">129</a>;</p> + <p class="i2">hereditary disease in plants, ii. <a href="#page11">11</a>;</p> + <p class="i2">on interbreeding, ii. <a href="#page116">116</a>;</p> + <p class="i2">crossed varieties of wheat, ii. <a href="#page130">130</a>;</p> + <p class="i2">necessity of intercrossing in plants, ii. <a href="#page175">175</a>;</p> + <p class="i2">on variation, ii. <a href="#page256">256</a>, <a href="#page257">257</a>;</p> + <p class="i2">effects of grafting, i. 387, ii. <a href="#page278">278</a>;</p> + <p class="i2">bud-variation in a plum, ii. <a href="#page289">289</a>;</p> + <p class="i2">compulsory flowering of early potatoes, ii. <a href="#page343">343</a>;</p> + <p class="i2">correlated variation of head and limbs, ii. <a href="#page323">323</a>.</p> + <p><span class="sc">Knox</span>, Mr., breeding of the eagle owl in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Koch</span>, degeneracy in the turnip, i. 325.</p> + <p><span class="sc">Kohlrabi</span>, i. 323.</p> + <p><span class="sc">Kölreuter</span>, reversion in hybrids, i. 392, ii. <a href="#page36">36</a>;</p> + <p class="i2">acquired sterility of crossed varieties of plants, i. 358, ii. <a href="#page101">101</a>;</p> + <p class="i2">absorption of <i>Mirabilis vulgaris</i> by <i>M. longiflora</i>, ii. <a href="#page88">88</a>;</p> + <p class="i2">crosses of species of <i>Verbascum</i>, ii. <a href="#page93">93</a>, <a href="#page107">107</a>;</p> + <p class="i2">on the hollyhock, ii. <a href="#page107">107</a>;</p> + <p class="i2">crossing varieties of tobacco, ii. <a href="#page108">108</a>;</p> + <p class="i2">benefits of crossing plants, ii. <a href="#page130">130</a>, <a href="#page131">131</a>, <a href="#page175">175</a>-<a href="#page176">176</a>;</p> + <p class="i2">self-impotence in <i>Verbascum</i>, ii. <a href="#page136">136</a>, <a href="#page141">141</a>;</p> + <p class="i2">effects of conditions of growth upon fertility in <i>Mirabilis</i>, ii. <a href="#page164">164</a>;</p> + <p class="i2">great development of tubers in hybrid plants, ii. <a href="#page172">172</a>;</p> + <p class="i2">inheritance of plasticity, ii. <a href="#page241">241</a>;</p> + <p class="i2">variability of hybrids of <i>Mirabilis</i>, ii. <a href="#page265">265</a>;</p> + <p class="i2">repeated crossing a cause of variation, ii. <a href="#page267">267</a>-<a href="#page268">268</a>;</p> + <p class="i2">number of pollen-grains necessary for fertilization, ii. <a href="#page363">363</a>.</p> + <p>"<span class="sc">Krauseschwein</span>," i. 67.</p> + <p><span class="sc">Krohn</span>, on the double reproduction of Medusæ, ii. <a href="#page384">384</a>.</p> + <p>"<span class="sc">Kropf-Tauben</span>," i. 137.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Labat</span>, on the tusks of feral bears in the West Indies, i. 77;</p> + <p class="i2">on French wheat grown in the West Indies, ii. <a href="#page307">307</a>;</p> + <p class="i2">on the culture of the vine in the West Indies, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Laburnum</span>, Adam's, see <i>Cytisus Adami</i>;</p> + <p class="i2">oak-leaved, reversion of, i. 382;</p> + <p class="i2">pelorism in the, ii. <a href="#page346">346</a>;</p> + <p class="i2">Waterer's, i. 390.</p> + <p><span class="sc">Lachmann</span>, on gemmation and fission, ii. <a href="#page358">358</a>.</p> + <p><i>Lachnanthes tinctoria</i>, ii. <a href="#page227">227</a>, <a href="#page336">336</a>.</p> + <p><span class="sc">Lactation</span>, imperfect, hereditary, ii. <a href="#page8">8</a>;</p> + <p class="i2">deficient, of wild animals in captivity, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Ladrone</span> islands, cattle of, i. 86.</p> + <p><span class="sc">Laing</span>, Mr., resemblance of Norwegian and Devonshire cattle, i. 82.</p> + <p><span class="sc">Lake-dwellings</span>, sheep of, i. 94, ii. <a href="#page427">427</a>;</p> + <p class="i2">cattle of, ii. <a href="#page427">427</a>;</p> + <p class="i2">absence of the fowl in, i. 246;</p> + <p class="i2">cultivated plants of, i. 309, ii. <a href="#page427">427</a>, <a href="#page429">429</a>;</p> + <p class="i2">cereals of, i. 317-319;</p> + <p class="i2">peas found in, i. 326;</p> + <p class="i2">beans found in, i. 330.</p> + <p><span class="sc">Lamare-Piquot</span>, observations on half-bred North American wolves, i. 22.</p> + <p><span class="sc">Lambert</span>, A. B., on <i>Thuja pendula</i> or <i>filiformis</i>, i. 362.</p> + <p><span class="sc">Lambert</span> family, ii. <a href="#page4">4</a>, <a href="#page76">76</a>.</p> + <p><span class="sc">Lambertye</span> on strawberries, i. 351, 352;</p> + <p class="i2">five-leaved variety of <i>Fragaria collina</i>, i. 353.</p> + <p><span class="sc">Landt</span>, L., on sheep in the Faroe islands, ii. <a href="#page103">103</a>.</p> + <p><span class="sc">La Plata</span>, wild dogs of, i. 27;</p> + <p class="i2">feral cat from, i. 47.</p> + <p><span class="sc">Larch</span>, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Larkspurs</span>, insect agency necessary for the full fecundation of, ii. <a href="#page21">21</a>.</p> + <p><i>Larus argentatus</i>, ii. <a href="#page157">157</a>.</p> + <p><i>Larus tridactylus</i>, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Lasterye</span>, merino sheep in different countries, i. 99.</p> + <p><span class="sc">Latent</span> characters, ii. <a href="#page51">51</a>-<a href="#page56">56</a>.</p> + <p><span class="sc">Latham</span>, on the fowl not breeding in the extreme north, ii. <a href="#page161">161</a>.</p> + <p><i>Lathyrus</i>, ii. <a href="#page38">38</a>.</p> + <p><i>Lathyrus aphaca</i>, ii. <a href="#page343">343</a>.</p> + <p><i>Lathyrus odoratus</i>, ii. <a href="#page20">20</a>, <a href="#page91">91</a>, <a href="#page93">93</a>, <a href="#page311">311</a>, <a href="#page393">393</a>.</p> + <p><span class="sc">La Touche</span>, J. D., on a Canadian apple with dimidiate fruit, i. 392-393.</p> + <p>"<span class="sc">Latz-Taube</span>," i. 154.</p> + <p><span class="sc">Laugher</span> pigeon, i. 155, 207.</p> + <p><i>Laurus sassafras</i>, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Lawrence</span>, J., production of a new breed of fox-hounds, i. 40;</p> + <p class="i2">occurrence of canines in mares, i. 50;</p> + <p class="i2">on three-parts-bred horses, i. 54;</p> + <p class="i2">on inheritance in the horse, ii. <a href="#page10">10</a>-<a href="#page11">11</a>.</p> + <p><span class="sc">Lawson</span>, Mr., varieties of the potato, i. 330.</p> + <p><span class="sc">Laxton</span>, Mr., bud-variation in the gooseberry, i. 376;</p> + <p class="i2">crossing of varieties of the pea, i. 397-398;</p> +<!-- Page 461 --><span class="pagenum"><a name="page461"></a>{461}</span> + <p class="i2">double-flowered peas, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Layard</span>, E. L., resemblance of a Caffre dog to the Esquimaux breed, i. 25, ii. <a href="#page286">286</a>;</p> + <p class="i2">crossing of the domestic cat with <i>Felis Caffra</i>, i. 44;</p> + <p class="i2">feral pigeons in Ascension, i. 190;</p> + <p class="i2">domestic pigeons of Ceylon, i. 206;</p> + <p class="i2">on <i>Gallus Stanleyi</i>, i. 234;</p> + <p class="i2">on black-skinned Ceylonese fowls, i. 256.</p> + <p><span class="sc">Le Compte</span> family, blindness inherited in, ii. <a href="#page78">78</a>.</p> + <p><span class="sc">Lecoq</span>, bud-variation in <i>Mirabilis jalapa</i>, i. 382;</p> + <p class="i2">hybrids of <i>Mirabilis</i>, i. 393, ii. <a href="#page169">169</a>, <a href="#page265">265</a>;</p> + <p class="i2">crossing in plants, ii. <a href="#page127">127</a>;</p> + <p class="i2">fecundation of <i>Passiflora</i>, ii. <a href="#page137">137</a>;</p> + <p class="i2">hybrid <i>Gladiolus</i>, ii. <a href="#page139">139</a>;</p> + <p class="i2">sterility of <i>Ranunculus ficaria</i>, ii. <a href="#page170">170</a>;</p> + <p class="i2">villosity in plants, ii. <a href="#page277">277</a>;</p> + <p class="i2">double asters, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Le Couteur</span>, J., varieties of wheat, i. 313-315;</p> + <p class="i2">acclimatisation of exotic wheat in Europe, i. 315;</p> + <p class="i2">adaptation of wheat to soil and climate, i. 316;</p> + <p class="i2">selection of seed-corn, i. 318;</p> + <p class="i2">on change of soil, ii. <a href="#page147">147</a>;</p> + <p class="i2">selection of wheat, ii. <a href="#page200">200</a>;</p> + <p class="i2">natural selection in wheat, ii. <a href="#page233">233</a>;</p> + <p class="i2">cattle of Jersey, ii. <a href="#page234">234</a>.</p> + <p><span class="sc">Ledger</span>, Mr., on the Llama and Alpaca, ii. <a href="#page208">208</a>.</p> + <p><span class="sc">Lee</span>, Mr., his early culture of the pansy, i. 368.</p> + <p><i>Leersia oryzoides</i>, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Lefour</span>, period of gestation in cattle, i. 87.</p> + <p><span class="sc">Legs</span>, of fowls, effects of disuse on, i. 270-272;</p> + <p class="i2">characters and variations of, in ducks, i. 284-288;</p> + <p class="i2">fusion of, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Leguat</span>, cattle of the Cape of Good Hope, i. 88.</p> + <p><span class="sc">Lehmann</span>, occurrence of wild double-flowered plants near a hot spring, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Leighton</span>, W. A., propagation of a weeping yew by seed, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Leitner</span>, effects of the removal of anthers, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Lemming</span>, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Lemoine</span>, variegated <i>Symphytum</i> and <i>Phlox</i>, i. 384.</p> + <p><span class="sc">Lemon</span>, i. 334, 335;</p> + <p class="i2">orange fecundated by pollen of the, i. 399.</p> + <p><span class="sc">Lemurs</span>, hybrid, ii. <a href="#page153">153</a>.</p> + <p><span class="sc">Leporides</span>, ii. <a href="#page98">98</a>-<a href="#page99">99</a>, <a href="#page152">152</a>.</p> + <p><span class="sc">Lepsius</span>, figures of ancient Egyptian dogs, i. 17;</p> + <p class="i2">domestication of pigeons in ancient Egypt, i. 204.</p> + <p><i>Leptotes</i>, ii. <a href="#page134">134</a>.</p> + <p><i>Lepus glacialis</i>, i. 111.</p> + <p><i>Lepus magellanicus</i>, i. 112.</p> + <p><i>Lepus nigripes</i>, i. 108.</p> + <p><i>Lepus tibetanus</i>, i. 111.</p> + <p><i>Lepus variabilis</i>, i. 111.</p> + <p><span class="sc">Lereboullet</span>, double monsters of fishes, ii. <a href="#page340">340</a>.</p> + <p><span class="sc">Leslie</span>, on Scotch wild cattle, i. 85.</p> + <p><span class="sc">Lesson</span>, on <i>Lepus magellanicus</i>, i. 112.</p> + <p><span class="sc">Leuckart</span> on the larva of Cecidomyidæ, ii. <a href="#page360">360</a>.</p> + <p><span class="sc">Lewis</span>, G., cattle of the West Indies, ii. <a href="#page229">229</a>.</p> + <p><span class="sc">Lherbette</span> and Quatrefages, on the horses of Circassia, ii. <a href="#page102">102</a>, <a href="#page225">225</a>.</p> + <p><span class="sc">Liebig</span>, differences in human blood, according to complexion, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Liebreich</span>, occurrence of pigmentary retinitis in deaf-mutes, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Lichens</span>, sterility in, ii. <a href="#page171">171</a>.</p> + <p><span class="sc">Lichtenstein</span>, resemblance of Bosjesman's dogs to <i>Canis mesomelas</i>, i. 25;</p> + <p class="i2">Newfoundland dog at the Cape of Good Hope, i. 36.</p> + <p><span class="sc">Lilacs</span>, ii. <a href="#page164">164</a>.</p> + <p><span class="sc">Liliaceæ</span>, contabescence in, ii. <a href="#page165">165</a>.</p> + <p><i>Lilium candidum</i>, ii. <a href="#page137">137</a>.</p> + <p><span class="sc">Limbs</span>, regeneration of, ii. <a href="#page376">376</a>-<a href="#page377">377</a>.</p> + <p><span class="sc">Limbs</span> and head, correlated variation of, ii. <a href="#page323">323</a>.</p> + <p><span class="sc">Lime</span>, effect of, upon shells of the mollusca, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Lime</span> tree, changes of by age, i. 364, 387.</p> + <p><span class="sc">Limitation</span>, sexual, ii. <a href="#page71">71</a>-<a href="#page75">75</a>.</p> + <p><span class="sc">Limitation</span>, supposed, of variation, ii. <a href="#page416">416</a>.</p> + <p><i>Linaria</i>, pelorism in, ii. <a href="#page58">58</a>, <a href="#page61">61</a>, <a href="#page346">346</a>;</p> + <p class="i2">peloric, crossed with the normal form, ii. <a href="#page70">70</a>;</p> + <p class="i2">sterility of, ii. <a href="#page166">166</a>.</p> + <p><i>Linaria vulgaris</i> and <i>purpurea</i>, hybrids of, ii. <a href="#page94">94</a>.</p> + <p><span class="sc">Lindley</span>, John, classification of varieties of cabbages, i. 324;</p> + <p class="i2">origin of the peach, i. 338;</p> + <p class="i2">influence of soil on peaches and nectarines, i. 340;</p> + <p class="i2">varieties of the peach and nectarine, i. 343;</p> + <p class="i2">on the New Town pippin, i. 349;</p> + <p class="i2">freedom of the Winter Majetin apple from coccus, i. 349;</p> + <p class="i2">production of monœcious Hautbois strawberries by bud-selection, i. 353;</p> + <p class="i2">origin of the large tawny nectarine, i. 375;</p> + <p class="i2">bud-variation in the gooseberry, i. 376;</p> + <p class="i2">hereditary disease in plants, ii. <a href="#page11">11</a>;</p> + <p class="i2">on double flowers, ii. <a href="#page167">167</a>;</p> + <p class="i2">seeding of ordinarily seedless fruits, ii. <a href="#page168">168</a>;</p> + <p class="i2">sterility of <i>Acorus calamus</i>, ii. <a href="#page170">170</a>;</p> + <p class="i2">resistance of individual plants to cold, ii. <a href="#page309">309</a>.</p> + <p><span class="sc">Linnæus</span>, summer and winter wheat regarded as distinct species by, i. 315;</p> + <p class="i2">on the single-leaved strawberry, i. 353;</p> + <p class="i2">sterility of Alpine plants in gardens, ii. <a href="#page163">163</a>;</p> + <p class="i2">recognition of individual reindeer by the Laplanders, ii. <a href="#page251">251</a>;</p> + <p class="i2">growth of tobacco in Sweden, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Linnet</span>, ii. <a href="#page158">158</a>.</p> + <p><i>Linota cannabina</i>, ii. <a href="#page158">158</a>.</p> +<!-- Page 462 --><span class="pagenum"><a name="page462"></a>{462}</span> + <p><span class="sc">Linum</span>, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Lion</span>, fertility of, in captivity, ii. <a href="#page150">150</a>, <a href="#page151">151</a>.</p> + <p><span class="sc">Lipari</span>, feral rabbits of, i. 113.</p> + <p><span class="sc">Livingstone</span>, Dr., striped young pigs on the Zambesi, i. 77;</p> + <p class="i2">domestic rabbits at Loanda, i. 112;</p> + <p class="i2">use of grass-seeds as food in Africa, i. 308;</p> + <p class="i2">planting of fruit-trees by the Batokas, i. 309;</p> + <p class="i2">character of half-castes, ii. <a href="#page46">46</a>;</p> + <p class="i2">taming of animals among the Barotse, ii. <a href="#page160">160</a>;</p> + <p class="i2">selection practised in South Africa, ii. <a href="#page207">207</a>, <a href="#page209">209</a>.</p> + <p><span class="sc">Livingstone</span>, Mr., disuse a cause of drooping ears, ii. <a href="#page301">301</a>.</p> + <p><span class="sc">Lizards</span>, reproduction of tail in, ii. <a href="#page294">294</a>;</p> + <p class="i2">with a double tail, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Llama</span>, selection of, ii. <a href="#page208">208</a>.</p> + <p><span class="sc">Lloyd</span>, Mr., taming of the wolf, i. 26;</p> + <p class="i2">English dogs in northern Europe, i. 36;</p> + <p class="i2">fertility of the goose increased by domestication, i. 288;</p> + <p class="i2">number of eggs laid by the wild goose, ii. <a href="#page112">112</a>;</p> + <p class="i2">breeding of the capercailzie in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Loanda</span>, domestic rabbits at, i. 112.</p> + <p><i>Loasa</i>, hybrid of two species of, ii. <a href="#page98">98</a>.</p> + <p><i>Lobelia</i>, reversion in hybrids of, ii. <a href="#page392">392</a>;</p> + <p class="i2">contabescence in, ii. <a href="#page166">166</a>.</p> + <p><i>Lobelia fulgens</i>, <i>cardinalis</i>, and <i>syphilitica</i>, ii. <a href="#page136">136</a>.</p> + <p><span class="sc">Lockhart</span>, Dr., on Chinese pigeons, i. 206.</p> + <p><span class="sc">Locust-tree</span>, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Loiseleur-Deslongchamps</span>, originals of cultivated plants, i. 307;</p> + <p class="i2">Mongolian varieties of wheat, i. 313;</p> + <p class="i2">characters of the ear in wheat, i. 314;</p> + <p class="i2">acclimatisation of exotic wheat in Europe, i. 315;</p> + <p class="i2">effect of change of climate on wheat, i. 316;</p> + <p class="i2">on the supposed necessity of the coincident variation of weeds and cultivated plants, i. 317;</p> + <p class="i2">advantage of change of soil to plants, ii. <a href="#page146">146</a>.</p> + <p><i>Lolium temulentum</i>, variable presence of barbs in, i. 314.</p> + <p><span class="sc">Long-tailed</span> sheep, i. 94, 95.</p> + <p><span class="sc">Loochoo</span> islands, horses of, i. 53.</p> + <p><span class="sc">Lord</span>, J. K., on Canis latrans, i. 22.</p> + <p>"<span class="sc">Lori rajah</span>," how produced, ii. <a href="#page280">280</a>.</p> + <p><i>Lorius garrulus</i>, ii. <a href="#page280">280</a>.</p> + <p>"<span class="sc">Lotan</span>," tumbler pigeon, i. 150.</p> + <p><span class="sc">Loudon</span>, J. W., varieties of the carrot, i. 326;</p> + <p class="i2">short duration of varieties of peas, i. 329;</p> + <p class="i2">on the glands of peach-leaves, i. 343;</p> + <p class="i2">presence of bloom on Russian apples, i. 349;</p> + <p class="i2">origin of varieties of the apple, i. 350;</p> + <p class="i2">varieties of the gooseberry, i. 354;</p> + <p class="i2">on the nut tree, i. 357;</p> + <p class="i2">varieties of the ash, i. 360;</p> + <p class="i2">fastigate juniper (<i>J. suecica</i>), i. 361;</p> + <p class="i2">on <i>Ilex aquifolium ferox</i>, i. 362;</p> + <p class="i2">varieties of the Scotch fir, i. 363;</p> + <p class="i2">varieties of the hawthorn, <i>ibid.</i>;</p> + <p class="i2">variation in the persistency of leaves on the elm and Turkish oak, i. 363;</p> + <p class="i2">importance of cultivated varieties, <i>ibid.</i>;</p> + <p class="i2">varieties of <i>Rosa spinosissima</i>, i. 367;</p> + <p class="i2">variation of dahlias from the same seed, i. 370;</p> + <p class="i2">production of Provence roses from seeds of the moss rose, i. 380;</p> + <p class="i2">effect of grafting the purple-leaved upon the common hazel, i. 395;</p> + <p class="i2">nearly evergreen Cornish variety of the elm, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Low</span>, G., on the pigs of the Orkney islands, i. 70.</p> + <p><span class="sc">Low</span>, Prof., pedigrees of greyhounds, ii. <a href="#page3">3</a>;</p> + <p class="i2">origin of the dog, i. 10;</p> + <p class="i2">burrowing instinct of a half-bred Dingo, i. 28;</p> + <p class="i2">inheritance of qualities in horses, i. 51;</p> + <p class="i2">comparative powers of English race-horses, Arabs, &c., i. 54;</p> + <p class="i2">British breeds of cattle, i. 80;</p> + <p class="i2">wild cattle of Chartley, i. 84;</p> + <p class="i2">effect of abundance of food on the size of cattle, i. 91;</p> + <p class="i2">effects of climate on the skin of cattle, i. 92, ii. <a href="#page326">326</a>;</p> + <p class="i2">on interbreeding, ii. <a href="#page116">116</a>;</p> + <p class="i2">selection in Hereford cattle, ii. <a href="#page214">214</a>;</p> + <p class="i2">formation of new breeds, ii. <a href="#page244">244</a>;</p> + <p class="i2">on "sheeted" cattle, ii. <a href="#page349">349</a>.</p> + <p><span class="sc">Lowe</span>, Mr., on hive bees, i. 299.</p> + <p><span class="sc">Lowe, Rev</span>. Mr., on the range of <i>Pyrus malus</i> and <i>P. acerba</i>, i. 348.</p> + <p>"<span class="sc">Lowtan</span>" tumbler pigeon, i. 150.</p> + <p><i>Loxia pyrrhula</i>, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Lubbock</span>, Sir J., developments of the Ephemeridæ, ii. <a href="#page366">366</a>.</p> + <p><span class="sc">Lucas</span>, P., effects of cross-breeding on the female, i. 404;</p> + <p class="i2">hereditary diseases, ii. <a href="#page7">7</a>, <a href="#page78">78</a>-<a href="#page79">79</a>;</p> + <p class="i2">hereditary affections of the eye, ii. <a href="#page9">9</a>-<a href="#page10">10</a>;</p> + <p class="i2">inheritance of anomalies in the human eye and in that of the horse, ii. <a href="#page10">10</a>, <a href="#page11">11</a>;</p> + <p class="i2">inheritance of polydactylism, ii. <a href="#page13">13</a>;</p> + <p class="i2">morbid uniformity in the same family, ii. <a href="#page17">17</a>;</p> + <p class="i2">inheritance of mutilations, ii. <a href="#page23">23</a>;</p> + <p class="i2">persistency of cross-reversion, ii. <a href="#page35">35</a>;</p> + <p class="i2">persistency of character in breeds of animals in wild countries, ii. <a href="#page64">64</a>;</p> + <p class="i2">prepotency of transmission, ii. <a href="#page65">65</a>, <a href="#page68">68</a>;</p> + <p class="i2">supposed rules of transmission in crossing animals, ii. <a href="#page68">68</a>;</p> + <p class="i2">sexual limitations of transmission of peculiarities, ii. <a href="#page72">72</a>-<a href="#page73">73</a>;</p> + <p class="i2">absorption of the minority in crossed races, ii. <a href="#page88">88</a>;</p> + <p class="i2">crosses without blending of certain characters, ii. <a href="#page92">92</a>;</p> + <p class="i2">on interbreeding, ii. <a href="#page116">116</a>;</p> + <p class="i2">variability dependent on reproduction, ii. <a href="#page250">250</a>;</p> + <p class="i2">period of action of variability, ii. <a href="#page260">260</a>;</p> + <p class="i2">inheritance of deafness in cats, ii. <a href="#page329">329</a>;</p> + <p class="i2">complexion and constitution, ii. <a href="#page335">335</a>.</p> + <p><span class="sc">Lucaze-Duthiers</span>, structure and growth of galls, ii. <a href="#page282">282</a>-<a href="#page284">284</a>.</p> + <p><span class="sc">Luizet</span>, grafting of a peach-almond on a peach, i. 338.</p> +<!-- Page 463 --><span class="pagenum"><a name="page463"></a>{463}</span> + <p><span class="sc">Lütke</span>, cats of the Caroline Archipelago, i. 47.</p> + <p><span class="sc">Luxuriance</span>, of vegetative organs, a cause of sterility in plants, ii. <a href="#page168">168</a>-<a href="#page171">171</a>.</p> + <p><span class="sc">Lyonnet</span>, on the scission of <i>Nais</i>, ii. <a href="#page358">358</a>.</p> + <p><i>Lysimachia nummularia</i>, sterility of, ii. <a href="#page170">170</a>.</p> + <p><i>Lythrum</i>, trimorphic species of, ii. <a href="#page400">400</a>.</p> + <p><i>Lythrum salicaria</i>, ii. <a href="#page183">183</a>;</p> + <p class="i2">contabescence in, ii. <a href="#page166">166</a>.</p> + <p><i>Lytta vesicatoria</i>, affecting the kidneys, ii. <a href="#page380">380</a>.</p> + </div> + + <div class="stanza"> + <p><i>Macacus</i>, species of, bred in captivity, ii. <a href="#page153">153</a>.</p> + <p><span class="sc">Macaulay</span>, Lord, improvement of the English horse, ii. <a href="#page213">213</a>.</p> + <p><span class="sc">M<sup>c</sup>Clelland</span>, Dr., variability of fresh-water fishes in India, ii. <a href="#page259">259</a>.</p> + <p><span class="sc">M<sup>c</sup>Coy</span>, Prof., on the dingo, i. 26.</p> + <p><span class="sc">Macfayden</span>, influence of soil in producing sweet or bitter oranges from the same seed, i. 335.</p> + <p><span class="sc">Macgillivray</span>, domestication of the rock-dove, i. 185;</p> + <p class="i2">feral pigeons in Scotland, i. 190;</p> + <p class="i2">number of vertebræ in birds, i. 266;</p> + <p class="i2">on wild geese, i. 287;</p> + <p class="i2">number of eggs of wild and tame ducks, ii. <a href="#page112">112</a>.</p> + <p><span class="sc">Mackenzie</span>, Sir G., peculiar variety of the potato, i. 330.</p> + <p><span class="sc">Mackenzie</span>, P., bud-variation in the currant, i. 376.</p> + <p><span class="sc">Mackinnon</span>, Mr., horses of the Falkland islands, i. 52;</p> + <p class="i2">feral cattle of the Falkland islands, i. 86.</p> + <p><span class="sc">MacKnight</span>, C., on interbreeding cattle, ii. <a href="#page118">118</a>.</p> + <p><span class="sc">MacNab</span>, Mr., on seedling weeping birches, ii. <a href="#page18">18</a>;</p> + <p class="i2">non-production of the weeping beech by seed, ii. <a href="#page19">19</a>.</p> + <p><span class="sc">Madagascar</span>, cats of, i. 47.</p> + <p><span class="sc">Madden</span>, H., on interbreeding cattle, ii. <a href="#page118">118</a>.</p> + <p><span class="sc">Madeira</span>, rock pigeon of, i. 184.</p> + <p><i>Magnolia grandiflora</i>, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Maize</span>, its unity of origin, i. 320;</p> + <p class="i2">antiquity of, <i>ibid.</i>;</p> + <p class="i2">with husked grains said to grow wild, <i>ibid.</i>;</p> + <p class="i2">variation of, i. 321;</p> + <p class="i2">irregularities in the flowers of, i. 321;</p> + <p class="i2">persistence of varieties, <i>ibid.</i>;</p> + <p class="i2">adaptation of to climate, i. 322, ii. <a href="#page307">307</a>;</p> + <p class="i2">acclimatisation of, ii. <a href="#page313">313</a>, <a href="#page347">347</a>;</p> + <p class="i2">crossing of, i. 400, ii. <a href="#page104">104</a>-<a href="#page105">105</a>;</p> + <p class="i2">extinct Peruvian varieties of, ii. <a href="#page425">425</a>.</p> + <p><span class="sc">Malay</span> fowl, i. 227.</p> + <p><span class="sc">Malay</span> Archipelago, horses of, i. 53;</p> + <p class="i2">short-tailed cats of, i. 47;</p> + <p class="i2">striped young wild pigs of, i. 76;</p> + <p class="i2">ducks of, i. 280.</p> + <p><span class="sc">Male</span>, influence of, on the fecundated female, i. 397-406;</p> + <p class="i2">supposed influence of, on offspring, ii. <a href="#page68">68</a>.</p> + <p><span class="sc">Male</span> flowers, appearance of, among female flowers in maize, i. 321.</p> + <p><span class="sc">Malformations</span>, hereditary, ii. <a href="#page79">79</a>.</p> + <p><i>Malva</i>, fertilisation of, i. 402, ii. <a href="#page363">363</a>.</p> + <p><i>Mamestra suasa</i>, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Mammæ</span>, variable in number in the pig, i. 74;</p> + <p class="i2">rudimentary, occasional full development of, in cows, i. 87, ii. <a href="#page317">317</a>;</p> + <p class="i2">four present in some sheep, i. 95;</p> + <p class="i2">variable in number in rabbits, i. 106;</p> + <p class="i2">latent functions of, in male animals, ii. <a href="#page52">52</a>, <a href="#page317">317</a>;</p> + <p class="i2">supernumerary and inguinal, in women, ii. <a href="#page57">57</a>.</p> + <p><span class="sc">Mangles</span>, Mr., annual varieties of the heartsease, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Mantell</span>, Mr., taming of birds by the New Zealanders, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Manu</span>, domestic fowl noticed in the Institutes of, i. 246.</p> + <p><span class="sc">Manure</span>, effect of, on the fertility of plants, ii. <a href="#page163">163</a>.</p> + <p><span class="sc">Manx</span> cats, i. 46, ii. <a href="#page66">66</a>.</p> + <p><span class="sc">Marcel</span> de Serres, fertility of the ostrich, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Marianne</span> islands, varieties of <i>Pandanus</i> in, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Markham</span>, Gervase, on rabbits, i. 104, ii. <a href="#page204">204</a>.</p> + <p><span class="sc">Markhor</span>, probably one of the parents of the goat, i. 101.</p> + <p><span class="sc">Marquand</span>, cattle of the channel islands, i. 80.</p> + <p><span class="sc">Marrimpoey</span>, inheritance in the horse, ii. <a href="#page10">10</a>.</p> + <p><span class="sc">Marrow</span>, vegetable, i. 357.</p> + <p><span class="sc">Marryatt</span>, Capt., breeding of asses in Kentucky, ii. <a href="#page237">237</a>.</p> + <p><span class="sc">Marsden</span>, notice of <i>Gallus giganteus</i>, i. 235.</p> + <p><span class="sc">Marshall</span>, Mr., voluntary selection of pasture by sheep, i. 96;</p> + <p class="i2">adaptation of wheats to soil and climate, i. 316;</p> + <p class="i2">"Dutch-buttocked" cattle, ii. <a href="#page8">8</a>;</p> + <p class="i2">segregation of herds of sheep, ii. <a href="#page103">103</a>;</p> + <p class="i2">advantage of change of soil to wheat and potatoes, ii. <a href="#page146">146</a>;</p> + <p class="i2">fashionable change in the horns of cattle, ii. <a href="#page210">210</a>;</p> + <p class="i2">sheep in Yorkshire, ii. <a href="#page235">235</a>.</p> + <p><span class="sc">Marshall</span>, Prof., growth of the brain in microcephalous idiots, ii. <a href="#page389">389</a>.</p> + <p><span class="sc">Martens</span>, E. Von, on <i>Achatinella</i>, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Martin</span>, W. C. L., origin of the dog, i. 16;</p> + <p class="i2">Egyptian dogs, i. 18;</p> + <p class="i2">barking of a Mackenzie River dog, i. 27;</p> + <p class="i2">African hounds in the Tower menagerie, i. 32;</p> + <p class="i2">on dun horses and dappled asses, i. 55;</p> + <p class="i2">breeds of the horse, i. 49;</p> + <p class="i2">wild horses, i. 51;</p> + <p class="i2">Syrian breeds of asses, i. 62;</p> + <p class="i2">asses without stripes, i. 63;</p> + <p class="i2">effects of cross-breeding on the female in dogs, i. 404;</p> + <p class="i2">striped legs of mules, ii. <a href="#page42">42</a>.</p> + <p><span class="sc">Martins</span>, defective instincts of silkworms, i. 304.</p> + <p><span class="sc">Martins</span>, C., fruit trees of Stockholm, ii. <a href="#page307">307</a>.</p> +<!-- Page 464 --><span class="pagenum"><a name="page464"></a>{464}</span> + <p><span class="sc">Mason</span>, W., bud-variation in the ash, i. 382.</p> + <p><span class="sc">Masters</span>, Dr., reversion in the spiral-leaved weeping willow, i. 383;</p> + <p class="i2">on peloric flowers, ii. <a href="#page58">58</a>;</p> + <p class="i2">pelorism in a clover, ii. <a href="#page346">346</a>;</p> + <p class="i2">position as a cause of pelorism, ii. <a href="#page345">345</a>, <a href="#page347">347</a>.</p> + <p><span class="sc">Masters</span>, Mr., persistence of varieties of peas, i. 329;</p> + <p class="i2">reproduction of colour in hyacinths, ii. <a href="#page20">20</a>;</p> + <p class="i2">on hollyhocks, ii. <a href="#page107">107</a>;</p> + <p class="i2">selection of peas for seed, ii. <a href="#page199">199</a>-<a href="#page200">200</a>;</p> + <p class="i2">on <i>Opuntia leucotricha</i>, ii. <a href="#page286">286</a>;</p> + <p class="i2">reversion by the terminal pea in the pod, ii. <a href="#page347">347</a>.</p> + <p><span class="sc">Mastiff</span>, sculptured on an Assyrian monument, i. 17, ii. <a href="#page429">429</a>;</p> + <p class="i2">Tibetan, i. 35-36, ii. <a href="#page278">278</a>.</p> + <p><span class="sc">Matthews</span>, Patrick, on forest trees, ii. <a href="#page237">237</a>.</p> + <p><i>Matthiola annua</i>, i. 399, ii. <a href="#page20">20</a>.</p> + <p><i>Matthiola incana</i>, i. 381, 399.</p> + <p><span class="sc">Mauchamp</span>, merino sheep, i. 100.</p> + <p><span class="sc">Mauduyt</span>, crossing of wolves and dogs in the Pyrenees, i. 24.</p> + <p><span class="sc">Maund</span>, Mr. crossed varieties of wheat, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Maupertuis</span>, axiom of "least action," i. 12.</p> + <p><span class="sc">Mauritius</span>, importation of goats into, i. 101.</p> + <p><span class="sc">Maw</span>, G., correlation of contracted leaves and flowers in pelargoniums, ii. <a href="#page330">330</a>, <a href="#page331">331</a>.</p> + <p><span class="sc">Mawz</span>, fertility of <i>Brassica rapa</i>, ii. <a href="#page165">165</a>.</p> + <p><i>Maxillaria</i>, self-fertilised capsules of, ii. <a href="#page134">134</a>;</p> + <p class="i2">number of seeds in, ii. <a href="#page379">379</a>.</p> + <p><i>Maxillaria atro-rubens</i>, fertilisation of, by <i>M. squalens</i>, ii. <a href="#page133">133</a>.</p> + <p><span class="sc">Mayes</span>, M., self-impotence in <i>Amaryllis</i>, ii. <a href="#page139">139</a>.</p> + <p><span class="sc">Meckel</span>, on the number of digits, ii. <a href="#page13">13</a>;</p> + <p class="i2">correlation of abnormal muscles in the leg and arm, ii. <a href="#page322">322</a>.</p> + <p><span class="sc">Medusæ</span>, development of, ii. <a href="#page368">368</a>, <a href="#page384">384</a>.</p> + <p><span class="sc">Meehan</span>, Mr., comparison of European and American trees, ii. <a href="#page281">281</a>.</p> + <p><i>Meleagris mexicana</i>, i. 292.</p> + <p><i>Meles taxus</i>, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Melons</span>, i. 359-360;</p> + <p class="i2">mongrel, supposed to be produced from a twin-seed, i. 391;</p> + <p class="i2">crossing of varieties of, i. 399, ii. <a href="#page108">108</a>, <a href="#page129">129</a>;</p> + <p class="i2">inferiority of, in Roman times, ii. <a href="#page216">216</a>;</p> + <p class="i2">changes in, by culture and climate, ii. <a href="#page275">275</a>;</p> + <p class="i2">serpent, correlation of variations in, ii. <a href="#page330">330</a>;</p> + <p class="i2">analogous variations in, ii. <a href="#page349">349</a>.</p> + <p><span class="sc">Membranes</span>, false, ii. <a href="#page294">294</a>-<a href="#page295">295</a>.</p> + <p><span class="sc">Ménétries</span>, on the stomach of <i>Strix grallaria</i>, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Meningitis</span>, tubercular, inherited, ii. <a href="#page78">78</a>.</p> + <p><span class="sc">Metagenesis</span>, ii. <a href="#page366">366</a>.</p> + <p><span class="sc">Metamorphosis</span>, ii. <a href="#page366">366</a>.</p> + <p><span class="sc">Metamorphosis</span> and development, ii. <a href="#page388">388</a>, <a href="#page389">389</a>.</p> + <p><span class="sc">Metzger</span>, on the supposed species of wheat, i. 312-313;</p> + <p class="i2">tendency of wheat to vary, i. 315;</p> + <p class="i2">variation of maize, i. 321-322;</p> + <p class="i2">cultivation of American maize in Europe, i. 322, ii. <a href="#page347">347</a>;</p> + <p class="i2">on cabbages, i. 323-325;</p> + <p class="i2">acclimatisation of Spanish wheat in Germany, ii. <a href="#page26">26</a>;</p> + <p class="i2">advantage of change of soil to plants, ii. <a href="#page146">146</a>;</p> + <p class="i2">on rye, ii. <a href="#page254">254</a>;</p> + <p class="i2">cultivation of different kinds of wheat, ii. <a href="#page261">261</a>.</p> + <p><span class="sc">Mexico</span>, dog from, with tan spots on the eyes, i. 29;</p> + <p class="i2">colours of feral horses in, i. 61.</p> + <p><span class="sc">Meyen</span>, on sending of bananas, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Mice</span>, grey and white, colours of, not blended by crossing, ii. <a href="#page92">92</a>;</p> + <p class="i2">rejection of bitter almonds by, ii. <a href="#page232">232</a>;</p> + <p class="i2">naked, ii. <a href="#page279">279</a>.</p> + <p><span class="sc">Michaux</span>, F., roan-coloured feral horses of Mexico, i. 61;</p> + <p class="i2">origin of domestic turkey, i. 292;</p> + <p class="i2">on raising peaches from seed, i. 339.</p> + <p><span class="sc">Michel</span>, F., selection of horses in mediæval times, ii. <a href="#page203">203</a>;</p> + <p class="i2">horses preferred on account of slight characters, ii. <a href="#page209">209</a>.</p> + <p><span class="sc">Michely</span>, effects of food on caterpillars, ii. <a href="#page280">280</a>;</p> + <p class="i2">on <i>Bombyx hesperus</i>, ii. <a href="#page304">304</a>.</p> + <p><span class="sc">Microphthalmia</span>, associated with defective teeth, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Middens</span>, Danish, remains of dogs in, i. 18, ii. <a href="#page427">427</a>.</p> + <p><span class="sc">Mignonette</span>, ii. <a href="#page237">237</a>, <a href="#page311">311</a>.</p> + <p><span class="sc">Millet</span>, i. 371.</p> + <p><span class="sc">Mills</span>, J., diminished fertility of mares when first turned out to grass, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Milne-Edwards</span>, on the development of the crustacea, ii. <a href="#page368">368</a>.</p> + <p><span class="sc">Milne-Edwards</span>, A., on a crustacean with a monstrous eye-peduncle, ii. <a href="#page391">391</a>.</p> + <p><i>Milvus niger</i>, ii. <a href="#page154">154</a>.</p> + <p><i>Mimulus luteus</i>, ii. <a href="#page128">128</a>.</p> + <p><span class="sc">Minor</span>, W. C., gemmation and fission in the Annelida, ii. <a href="#page358">358</a>.</p> + <p><i>Mirabilis</i>, fertilisation of, ii. <a href="#page363">363</a>;</p> + <p class="i2">hybrids of, ii. <a href="#page131">131</a>, <a href="#page169">169</a>, <a href="#page265">265</a>.</p> + <p><i>Mirabilis jalapa</i>, i. 382, 393.</p> + <p><i>Mirabilis longiflora</i>, ii. <a href="#page88">88</a>.</p> + <p><i>Mirabilis vulgaris</i>, ii. <a href="#page88">88</a>.</p> + <p><i>Misocampus</i> and <i>Cecidomyia</i>, i. 5.</p> + <p><span class="sc">Mitchell</span>, Dr., effects of the poison of the rattlesnake, ii. <a href="#page289">289</a>.</p> + <p><span class="sc">Mitford</span>, Mr., notice of the breeding of horses by Erichthonius, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Moccas</span> Court, weeping oak at, ii. <a href="#page18">18</a>.</p> + <p><span class="sc">Mogford</span>, horses poisoned by fool's parsley, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Möller</span>, L., effects of food on insects, ii. <a href="#page281">281</a>.</p> + <p><span class="sc">Moquin-Tandon</span>, original form of maize, i. 320;</p> + <p class="i2">variety of the double columbine, i. 365;</p> +<!-- Page 465 --><span class="pagenum"><a name="page465"></a>{465}</span> + <p class="i2">peloric flowers, ii. <a href="#page58">58</a>-<a href="#page59">59</a>, <a href="#page61">61</a>;</p> + <p class="i2">position as a cause of pelorism in flowers, ii. <a href="#page345">345</a>;</p> + <p class="i2">tendency of peloric flowers to become irregular, ii. <a href="#page70">70</a>;</p> + <p class="i2">on monstrosities, ii. <a href="#page254">254</a>;</p> + <p class="i2">correlation in the axis and appendages of plants, ii. <a href="#page321">321</a>;</p> + <p class="i2">fusion of homologous parts in plants, ii. <a href="#page339">339</a>, <a href="#page341">341</a>-<a href="#page342">342</a>;</p> + <p class="i2">on a bean with monstrous stipules and abortive leaflets, ii. <a href="#page343">343</a>;</p> + <p class="i2">conversion of parts of flowers, ii. <a href="#page392">392</a>.</p> + <p><span class="sc">Mole</span>, white, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Moll</span> and Gayot, on cattle, i. 80, ii. <a href="#page96">96</a>, <a href="#page210">210</a>.</p> + <p><span class="sc">Mollusca</span>, change in shells of, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Monke</span>, Lady, culture of the pansy by, i. 368.</p> + <p><span class="sc">Monkeys</span>, rarely fertile in captivity, ii. <a href="#page153">153</a>.</p> + <p><span class="sc">Monnier</span>, identity of summer and winter wheat, i. 315.</p> + <p><span class="sc">Monster</span>, cyclopean, ii. <a href="#page341">341</a>.</p> + <p><span class="sc">Monsters</span>, double, ii. <a href="#page339">339</a>-<a href="#page340">340</a>.</p> + <p><span class="sc">Monstrosities</span>, occurrence of, in domesticated animals and cultivated plants, i. 366, ii. <a href="#page254">254</a>;</p> + <p class="i2">due to persistence of embryonic conditions, ii. <a href="#page57">57</a>;</p> + <p class="i2">occurring by reversion, ii. <a href="#page57">57</a>-<a href="#page60">60</a>;</p> + <p class="i2">a cause of sterility, ii. <a href="#page166">166</a>-<a href="#page167">167</a>;</p> + <p class="i2">caused by injury to the embryo, ii. <a href="#page269">269</a>.</p> + <p><span class="sc">Montegazza</span>, growth of a cock's-spur inserted into the eye of an ox, ii. <a href="#page369">369</a>.</p> + <p><span class="sc">Montgomery</span>, E., formation of cells, ii. <a href="#page370">370</a>.</p> + <p><span class="sc">Moor</span>, J. H., deterioration of the horse in Malasia, i. 53.</p> + <p><span class="sc">Moorcroft</span>, Mr., on Hasora wheat, i. 313;</p> + <p class="i2">selection of white-tailed yaks, ii. <a href="#page206">206</a>;</p> + <p class="i2">melon of Kaschmir, ii. <a href="#page275">275</a>;</p> + <p class="i2">varieties of the apricot cultivated in Ladakh, i. 345;</p> + <p class="i2">varieties of the walnut cultivated in Kaschmir, i. 356.</p> + <p><span class="sc">Moore</span>, Mr., on breeds of pigeons, i. 148, 156, 208, 209, 211.</p> + <p><span class="sc">Mooruk</span>, fertility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Morlot</span>, dogs of the Danish Middens, i. 18;</p> + <p class="i2">sheep and horse of the bronze period, ii. <a href="#page427">427</a>.</p> + <p><i>Mormodes ignea</i>, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Morocco</span>, estimation of pigeons in, i. 205.</p> + <p><span class="sc">Morren</span>, C., on pelorism, ii. <a href="#page58">58</a>;</p> + <p class="i2">in <i>Calceolaria</i>, ii. <a href="#page346">346</a>;</p> + <p class="i2">non-coincidence of double flowers and variegated leaves, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Morris</span>, Mr., breeding of the Kestrel in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Morton</span>, Lord, effect of fecundation by a quagga on an Arab mare, i. 403-404.</p> + <p><span class="sc">Morton</span>, Dr., origin of the dog, i. 16;</p> + <p class="i2">hybrid of zebra and mare, ii. <a href="#page42">42</a>.</p> + <p><i>Morus alba</i>, i. 334.</p> + <p><span class="sc">Moscow</span>, rabbits of, i. 106, 120;</p> + <p class="i2">effects of cold on pear-trees at, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Mosses</span>, sterility in, ii. <a href="#page171">171</a>;</p> + <p class="i2">retrogressive metamorphosis in, ii. <a href="#page361">361</a>.</p> + <p><span class="sc">Moss-rose</span>, probable origin of, from <i>Rosa centifolia</i>, i. 379;</p> + <p class="i2">Provence roses produced from seeds of, i. 380.</p> + <p><span class="sc">Mosto</span>, Cada, on the introduction of rabbits into Porto Santo, i. 113.</p> + <p><span class="sc">Mottling</span> of fruits and flowers, i. 400.</p> + <p><span class="sc">Moufflon</span>, i. 94.</p> + <p><span class="sc">Mountain-ash</span>, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Mouse</span>, Barbary, ii. <a href="#page152">152</a>.</p> + <p>"<span class="sc">Möven-taube</span>," i. 148.</p> + <p><span class="sc">Mowbray</span>, Mr., on the eggs of game fowls, i. 248;</p> + <p class="i2">early pugnacity of game cocks, i. 251;</p> + <p class="i2">diminished fecundity of the pheasant in captivity, ii. <a href="#page155">155</a>.</p> + <p><span class="sc">Mowbray</span>, Mr., reciprocal fecundation of <i>Passiflora alata</i> and <i>racemosa</i>, ii. <a href="#page137">137</a>.</p> + <p><span class="sc">Mulattos</span>, character of, ii. <a href="#page46">46</a>.</p> + <p><span class="sc">Mulberry</span>, i. 334, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Mule</span> and hinny, differences in the, ii. <a href="#page67">67</a>-<a href="#page68">68</a>.</p> + <p><span class="sc">Mules</span><span class="scac"></span>, striped colouring of, ii. <a href="#page42">42</a>;</p> + <p class="i2">obstinacy of, ii. <a href="#page45">45</a>;</p> + <p class="i2">production of, among the Romans, ii. <a href="#page110">110</a>;</p> + <p class="i2">noticed in the Bible, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Müller</span>, Fritz, reproduction of orchids, ii. <a href="#page134">134</a>-<a href="#page135">135</a>;</p> + <p class="i2">development of crustacea, ii. <a href="#page368">368</a>;</p> + <p class="i2">number of seeds in a <i>maxillaria</i>, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Müller</span>, H., on the face and teeth in dogs, i. 34, 73, ii. <a href="#page345">345</a>.</p> + <p><span class="sc">Müller</span>, J., production of imperfect nails after partial amputation of the fingers, ii. <a href="#page15">15</a>;</p> + <p class="i2">tendency to variation, ii. <a href="#page252">252</a>;</p> + <p class="i2">atrophy of the optic nerve consequent on destruction of the eye, ii. <a href="#page297">297</a>;</p> + <p class="i2">on Janus-like monsters, ii. <a href="#page340">340</a>;</p> + <p class="i2">on gemmation and fission, ii. <a href="#page358">358</a>;</p> + <p class="i2">identity of ovules and buds, ii. <a href="#page360">360</a>;</p> + <p class="i2">special affinities of the tissues, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Müller</span>, Max, antiquity of agriculture, ii. <a href="#page243">243</a>.</p> + <p><span class="sc">Multiplicity</span> of origin of pigeons, hypotheses of, discussed, i. 188-194.</p> + <p><span class="sc">Muniz</span>, F., on Niata cattle, i. 90.</p> + <p><span class="sc">Munro</span>, R., on the fertilisation of orchids, ii. <a href="#page133">133</a>;</p> + <p class="i2">reproduction of <i>Passiflora alata</i>, ii. <a href="#page138">138</a>.</p> + <p>"<span class="sc">Murassa</span>" pigeon, i. 144.</p> + <p><span class="sc">Murphy</span>, J. J., the structure of the eye not producible by selection, ii. <a href="#page222">222</a>.</p> + <p><i>Mus alexandrinus</i>, ii. <a href="#page87">87</a>-<a href="#page88">88</a>.</p> + <p><i>Musa sapientum</i>, <i>Chinensis</i> and <i>Cavendishii</i>, i. 377.</p> + <p><i>Muscari comosum</i>, ii. <a href="#page185">185</a>, <a href="#page316">316</a>.</p> + <p><span class="sc">Muscles</span>, effects of use on, ii. <a href="#page297">297</a>.</p> + <p><span class="sc">Musk</span> duck, feral hybrid of, with the common duck, i. 190.</p> +<!-- Page 466 --><span class="pagenum"><a name="page466"></a>{466}</span> + <p><span class="sc">Musmon</span>, female, sometimes hornless, i. 95.</p> + <p><span class="sc">Mutilations</span>, inheritance or non-inheritance of, ii. <a href="#page22">22</a>-<a href="#page24">24</a>, <a href="#page397">397</a>.</p> + <p><span class="sc">Myatt</span>, on a five-leaved variety of the strawberry, i. 353.</p> + <p><span class="sc">Myopia</span>, hereditary, ii. <a href="#page8">8</a>.</p> + <p><span class="sc">Myriapoda</span>, regeneration of lost parts in, ii. <a href="#page15">15</a>, <a href="#page294">294</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Nails</span>, growing on stumps of fingers, ii. <a href="#page394">394</a>.</p> + <p><span class="sc">Nais</span>, scission of, ii. <a href="#page358">358</a>.</p> + <p><span class="sc">Namaquas</span>, cattle of the, i. 88, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Narcissus</span>, double, becoming single in poor soil, ii. <a href="#page167">167</a>.</p> + <p><span class="sc">Narvaez</span>, on the cultivation of native plants in Florida, i. 312.</p> + <p><i>Nasua</i>, sterility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p>"<span class="sc">Natas</span>," or Niatas, a South American breed of cattle, i. 89-91.</p> + <p><span class="sc">Nathusius</span>, H. von, on the pigs of the Swiss lake-dwellings, i. 68;</p> + <p class="i2">on the races of pigs, i. 65-68;</p> + <p class="i2">convergence of character in highly-bred pigs, i. 73, ii. <a href="#page241">241</a>;</p> + <p class="i2">causes of changes in the form of the pig's skull, i. 72-73;</p> + <p class="i2">changes in breeds of pigs by crossing, i. 78;</p> + <p class="i2">change of form in the pig, ii. <a href="#page279">279</a>;</p> + <p class="i2">effects of disuse of parts in the pig, ii. <a href="#page299">299</a>;</p> + <p class="i2">period of gestation in the pig, i. 74;</p> + <p class="i2">appendages to the jaw in pigs, i. 76;</p> + <p class="i2">on <i>Sus pliciceps</i>, i. 70;</p> + <p class="i2">period of gestation in sheep, i. 97;</p> + <p class="i2">on Niata cattle, i. 89;</p> + <p class="i2">on short-horn cattle, ii. <a href="#page118">118</a>;</p> + <p class="i2">on interbreeding, ii. <a href="#page116">116</a>;</p> + <p class="i2">in the sheep, ii. <a href="#page120">120</a>;</p> + <p class="i2">in pigs, ii. <a href="#page122">122</a>;</p> + <p class="i2">unconscious selection in cattle and pigs, ii. <a href="#page214">214</a>;</p> + <p class="i2">variability of highly selected races, ii. <a href="#page238">238</a>.</p> + <p><span class="sc">Nato</span>, P., on the Bizzaria orange, i. 391.</p> + <p><span class="sc">Natural</span> selection, its general principles, i. 2-14.</p> + <p><span class="sc">Nature</span>, sense in which the term is employed, i. 6.</p> + <p><span class="sc">Naudin</span>, supposed rules of transmission in crossing plants, ii. <a href="#page68">68</a>;</p> + <p class="i2">on the nature of hybrids, ii. <a href="#page48">48</a>-<a href="#page49">49</a>;</p> + <p class="i2">essences of the species in hybrids, ii. <a href="#page386">386</a>, <a href="#page401">401</a>;</p> + <p class="i2">reversion of hybrids, ii. <a href="#page36">36</a>, <a href="#page49">49</a>-<a href="#page50">50</a>;</p> + <p class="i2">reversion in flowers by stripes and blotches, ii. <a href="#page37">37</a>;</p> + <p class="i2">hybrids of <i>Linaria vulgaris</i> and <i>purpurea</i>, ii. <a href="#page94">94</a>;</p> + <p class="i2">pelorism in <i>Linaria</i>, ii. <a href="#page58">58</a>, <a href="#page346">346</a>;</p> + <p class="i2">crossing of peloric <i>Linaria</i> with the normal form, ii. <a href="#page70">70</a>;</p> + <p class="i2">variability in <i>Datura</i>, ii. <a href="#page266">266</a>;</p> + <p class="i2">hybrids of <i>Datura lævis</i> and <i>stramonium</i>, i. 392;</p> + <p class="i2">prepotency of transmission of <i>Datura stramonium</i> when crossed, ii. <a href="#page67">67</a>;</p> + <p class="i2">on the pollen of <i>Mirabilis</i> and of hybrids, i. 389;</p> + <p class="i2">fertilisation of <i>Mirabilis</i>, ii. <a href="#page363">363</a>;</p> + <p class="i2">crossing of <i>Chamærops humilis</i> and the date palm, i. 399;</p> + <p class="i2">cultivated Cucurbitaceæ, i. 357-360, ii. <a href="#page108">108</a>;</p> + <p class="i2">rudimentary tendrils in gourds, ii. <a href="#page316">316</a>;</p> + <p class="i2">dwarf <i>Cucurbitæ</i>, ii. <a href="#page330">330</a>;</p> + <p class="i2">relation between the size and number of the fruit in <i>Cucurbita pepo</i>, ii. <a href="#page343">343</a>;</p> + <p class="i2">analogous variation in <i>Cucurbitæ</i>, ii. <a href="#page349">349</a>;</p> + <p class="i2">acclimatisation of Cucurbitaceæ, ii. <a href="#page313">313</a>;</p> + <p class="i2">production of fruit by sterile hybrid Cucurbitaceæ, ii. <a href="#page172">172</a>;</p> + <p class="i2">on the melon, i. 360, ii. <a href="#page108">108</a>, <a href="#page275">275</a>;</p> + <p class="i2">incapacity of the cucumber to cross with other species, i. 359.</p> + <p><span class="sc">Nectarine</span>, i. 336-344;</p> + <p class="i2">derived from the peach, i. 337, 339-342;</p> + <p class="i2">hybrids of, i. 339;</p> + <p class="i2">persistency of characters in seedling, i. 340;</p> + <p class="i2">origin of, <i>ibid.</i>;</p> + <p class="i2">produced on peach trees, i. 340-341;</p> + <p class="i2">producing peaches, i. 341;</p> + <p class="i2">variation in, i. 342-343;</p> + <p class="i2">bud-variation in, i. 374;</p> + <p class="i2">glands in the leaves of the, ii. <a href="#page231">231</a>;</p> + <p class="i2">analogous variation in, ii. <a href="#page348">348</a>.</p> + <p><span class="sc">Nectary</span>, variations of, in pansies, i. 369.</p> + <p><span class="sc">Nees</span>, on changes in the odour of plants, ii. <a href="#page274">274</a>.</p> + <p>"<span class="sc">Negro</span>" cat, i. 46.</p> + <p><span class="sc">Negroes</span>, polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">selection of cattle practised by, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Neolithic</span> period, domestication of <i>Bos longifrons</i> and <i>primigenius</i> in the, i. 81;</p> + <p class="i2">cattle of the, distinct from the original species, i. 87;</p> + <p class="i2">domestic goat in the, i. 101;</p> + <p class="i2">cereals of the, i. 317.</p> + <p><span class="sc">Nerve</span>, optic, atrophy of the, ii. <a href="#page297">297</a>.</p> + <p><span class="sc">Neumeister</span>, on the Dutch and German pouter pigeons, i. 138;</p> + <p class="i2">on the Jacobin pigeon, i. 154;</p> + <p class="i2">duplication of the middle flight feather in pigeons, i. 159;</p> + <p class="i2">on a peculiarly coloured breed of pigeons, "Staarhalsige Taube," i. 161;</p> + <p class="i2">fertility of hybrid pigeons, i. 192;</p> + <p class="i2">mongrels of the trumpeter pigeon, ii. <a href="#page66">66</a>;</p> + <p class="i2">period of perfect plumage in pigeons, ii. <a href="#page77">77</a>;</p> + <p class="i2">advantage of crossing pigeons, ii. <a href="#page126">126</a>.</p> + <p><span class="sc">Neuralgia</span>, hereditary, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">New Zealand</span>, feral cats of, i. 47;</p> + <p class="i2">cultivated plants of, i. 311.</p> + <p><span class="sc">Newfoundland</span> dog, modification of, in England, i. 42.</p> + <p><span class="sc">Newman</span>, E., sterility of Sphingidæ under certain conditions, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Newport</span>, G., non-copulation of <i>Vanessæ</i> in confinement, ii. <a href="#page157">157</a>;</p> + <p class="i2">regeneration of limbs in myriapoda, ii. <a href="#page294">294</a>;</p> + <p class="i2">fertilisation of the ovule in batrachia, ii. <a href="#page363">363</a>.</p> + <p><span class="sc">Newt</span>, polydactylism in the, ii. <a href="#page14">14</a>.</p> + <p><span class="sc">Newton</span>, A., absence of sexual distinctions in the Columbidæ, i. 162;</p> + <p class="i2">production of a "black-shouldered" pea-hen among the ordinary kind, i. 291;</p> + <p class="i2">on hybrid ducks, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Ngami</span>, Lake, cattle of, i. 88.</p> + <p>"<span class="sc">Niata</span>" cattle, i. 89-91;</p> + <p class="i2">resemblance of to <i>Sivatherium</i>, i. 89;</p> +<!-- Page 467 --><span class="pagenum"><a name="page467"></a>{467}</span> + <p class="i2">prepotency of transmission of character by, ii. <a href="#page66">66</a>.</p> + <p>"<span class="sc">Nicard</span>" rabbit, i. 107.</p> + <p><span class="sc">Nicholson</span>, Dr., on the cats of Antigua, i. 46;</p> + <p class="i2">on the sheep of Antigua, i. 98.</p> + <p><i>Nicotiana</i>, crossing of varieties and species of, ii. <a href="#page108">108</a>;</p> + <p class="i2">prepotency of transmission of characters in species of, ii. <a href="#page67">67</a>;</p> + <p class="i2">contabescence of female organs in, ii. <a href="#page166">166</a>.</p> + <p><i>Nicotiana glutinosa</i>, ii. <a href="#page108">108</a>.</p> + <p><span class="sc">Niebuhr</span>, on the heredity of mental characteristics in some Roman families, ii. <a href="#page65">65</a>.</p> + <p><span class="sc">Night-blindness</span>, non-reversion to, ii. <a href="#page36">36</a>.</p> + <p><span class="sc">Nilsson</span>, Prof., on the barking of a young wolf, i. 27;</p> + <p class="i2">parentage of European breeds of cattle, i. 80, 81;</p> + <p class="i2">on <i>Bos frontosus</i> in Scania, i. 81.</p> + <p><span class="sc">Nind</span>, Mr., on the dingo, i. 39.</p> + <p>"<span class="sc">Nisus</span> formativus," i. 293, 294, 355.</p> + <p><span class="sc">Nitzsch</span>, on the absence of the oil-gland in certain Columbæ, i. 147.</p> + <p><span class="sc">Non-inheritance</span>, causes of, ii. <a href="#page24">24</a>-<a href="#page26">26</a>.</p> + <p>"<span class="sc">Nonnain</span>" pigeon, i. 154.</p> + <p><span class="sc">Nordmann</span>, dogs of Awhasie, i. 25.</p> + <p><span class="sc">Normandy</span>, pigs of, with appendages under the jaw, i. 75.</p> + <p><span class="sc">Norway</span>, striped ponies of, i. 58.</p> + <p><span class="sc">Nott</span> and Gliddon, on the origin of the dog, i. 16;</p> + <p class="i2">mastiff represented on an Assyrian tomb, i. 17;</p> + <p class="i2">on Egyptian dogs, i. 18;</p> + <p class="i2">on the Hare-Indian dog, i. 22.</p> + <p><i>Notylia</i>, ii. <a href="#page135">135</a>.</p> + <p><span class="sc">Nourishment</span>, excess of, a cause of variability, ii. <a href="#page257">257</a>.</p> + <p><span class="sc">Number</span>, importance of, in selection, ii. <a href="#page235">235</a>.</p> + <p><i>Numida ptilorhyncha</i>, the original of the Guinea-fowl, i. 294.</p> + <p><span class="sc">Nun</span> pigeon, i. 155;</p> + <p class="i2">known to Aldrovandi, i. 207.</p> + <p><span class="sc">Nutmeg</span> tree, ii. <a href="#page237">237</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Oak</span>, weeping, i. 361, ii. <a href="#page18">18</a>, <a href="#page241">241</a>;</p> + <p class="i2">pyramidal, i. 361;</p> + <p class="i2">Hessian, i. 361;</p> + <p class="i2">late-leaved, i. 363;</p> + <p class="i2">variation in persistency of leaves of, i. 363;</p> + <p class="i2">valueless as timber at the Cape of Good Hope, ii. <a href="#page274">274</a>;</p> + <p class="i2">changes in, dependent on age, i. 387;</p> + <p class="i2">galls of the, ii. <a href="#page282">282</a>.</p> + <p><span class="sc">Oats</span>, wild, i. 313;</p> + <p class="i2">in the Swiss lake-dwellings, i. 319.</p> + <p><span class="sc">Oberlin</span>, change of soil beneficial to the potato, ii. <a href="#page146">146</a>.</p> + <p><span class="sc">Odart</span>, Count, varieties of the vine, i. 333, ii. <a href="#page278">278</a>;</p> + <p class="i2">bud-variation in the vine, i. 375.</p> + <p><span class="sc">Odour</span> and colour, correlation of, ii. <a href="#page325">325</a>.</p> + <p><i>Œcidium</i>, ii. <a href="#page284">284</a>.</p> + <p><i>Œnothera biennis</i>, bud-variation in, i. 382.</p> + <p><span class="sc">Ogle</span>, W., resemblance of twins, ii. <a href="#page252">252</a>.</p> + <p><span class="sc">Oil-gland</span>, absence of, in fantail pigeons, i. 147, 160.</p> + <p><span class="sc">Oldfield</span>, Mr., estimation of European dogs among the natives of Australia, ii. <a href="#page215">215</a>.</p> + <p><span class="sc">Oleander</span>, stock affected by grafting in the, i. 394.</p> + <p><span class="sc">Ollier</span>, Dr., insertion of the periosteum of a dog beneath the skin of a rabbit, ii. <a href="#page369">369</a>.</p> + <p><i>Oncidium</i>, reproduction of, ii. <a href="#page133">133</a>-<a href="#page135">135</a>, <a href="#page164">164</a>.</p> + <p><span class="sc">Onions</span>, crossing of, ii. <a href="#page90">90</a>;</p> + <p class="i2">white, liable to the attacks of fungi and disease, ii. <a href="#page228">228</a>, <a href="#page336">336</a>.</p> + <p><i>Ophrys apifera</i>, self-fertilisation of, ii. <a href="#page91">91</a>;</p> + <p class="i2">formation of pollen by a petal in, ii. <a href="#page392">392</a>.</p> + <p><i>Opuntia leucotricha</i>, ii. <a href="#page277">277</a>.</p> + <p><span class="sc">Orange</span>, i. 334-336;</p> + <p class="i2">crossing of, ii. <a href="#page91">91</a>;</p> + <p class="i2">with the lemon, i. 399, ii. <a href="#page365">365</a>;</p> + <p class="i2">naturalisation of, in Italy, ii. <a href="#page308">308</a>;</p> + <p class="i2">variation of, in North Italy, ii. <a href="#page256">256</a>;</p> + <p class="i2">peculiar variety of, ii. <a href="#page331">331</a>;</p> + <p class="i2">Bizzaria, i. 391;</p> + <p class="i2">trifacial, <i>ibid.</i></p> + <p><span class="sc">Orchids</span>, reproduction of, i. 402, 403; ii. <a href="#page133">133</a>-<a href="#page135">135</a>.</p> + <p><span class="sc">Orford</span>, Lord, crossing greyhounds with the bulldog, i. 41.</p> + <p><span class="sc">Organisms</span>, origin of, i. 13.</p> + <p><span class="sc">Organisation</span>, advancement in, i. 8.</p> + <p><span class="sc">Organs</span>, rudimentary and aborted, ii. <a href="#page315">315</a>-<a href="#page318">318</a>;</p> + <p class="i2">multiplication of abnormal, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Oriole</span>, assumption of hen-plumage by a male in confinement, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Orkney</span> islands, pigs of, i. 70;</p> + <p class="i2">pigeons of, i. 184.</p> + <p><span class="sc">Orthoptera</span>, regeneration of hind legs in the, ii. <a href="#page294">294</a>.</p> + <p><i>Orthosia munda</i>, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Orton</span>, R., on the effects of cross-breeding on the female, i. 404;</p> + <p class="i2">on the Manx cat, ii. <a href="#page66">66</a>;</p> + <p class="i2">on mongrels from the silk-fowl, ii. <a href="#page67">67</a>.</p> + <p><span class="sc">Osborne</span>, Dr., inherited mottling of the iris, ii. <a href="#page10">10</a>.</p> + <p><span class="sc">Osprey</span>, preying on Black-fowls, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Osten-Sacken</span>, Baron, on American oak galls, ii. <a href="#page282">282</a>.</p> + <p><span class="sc">Osteological</span> characters of pigs, i. 66, 67, 71-74;</p> + <p class="i2">of rabbits, i. 115-130;</p> + <p class="i2">of pigeons, i. 162-167;</p> + <p class="i2">of ducks, i. 282-284.</p> + <p><span class="sc">Ostrich</span>, diminished fertility of the, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Ostyaks</span>, selection of dogs by the, ii. <a href="#page206">206</a>.</p> + <p><span class="sc">Otter</span>, ii. <a href="#page151">151</a>.</p> + <p>"<span class="sc">Otter</span>" sheep of Massachusetts, i. 100.</p> + <p><span class="sc">Oude</span>, feral humped cattle in, i. 79.</p> + <p><span class="sc">Ouistiti</span>, breed in Europe, ii. <a href="#page153">153</a>.</p> +<!-- Page 468 --><span class="pagenum"><a name="page468"></a>{468}</span> + <p><span class="sc">Ovary</span>, variation of, in <i>Cucurbita moschata</i>, i. 359;</p> + <p class="i2">development of, independently of pollen, i. 403.</p> + <p><i>Ovis montana</i>, i. 99.</p> + <p><span class="sc">Ovules</span> and buds, identity of nature of, ii. <a href="#page360">360</a>.</p> + <p><span class="sc">Owen</span>, Capt., on stiff-haired cats at Mombas, i. 46.</p> + <p><span class="sc">Owen</span>, Prof. R., palæontological evidence as to the origin of dogs, i. 15;</p> + <p class="i2">on <i>Bos longifrons</i>, i. 81;</p> + <p class="i2">on the skull of the "Niata" cattle, i. 89, 90;</p> + <p class="i2">on fossil remains of rabbits, i. 104;</p> + <p class="i2">on the significance of the brain, i. 124;</p> + <p class="i2">on the number of digits in the Ichthyopterygia, ii. <a href="#page16">16</a>;</p> + <p class="i2">on metagenesis, ii. <a href="#page366">366</a>;</p> + <p class="i2">theory of reproduction and parthenogenesis, ii. <a href="#page375">375</a>.</p> + <p><span class="sc">Owl</span>, eagle, breeding in captivity, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Owl</span> pigeon, i. 148;</p> + <p class="i2">African, figured, i. 149;</p> + <p class="i2">known in 1735, i. 209.</p> + <p><i>Oxalis</i>, trimorphic species of, ii. <a href="#page400">400</a>.</p> + <p><i>Oxalis rosea</i>, ii. <a href="#page132">132</a>.</p> + <p><span class="sc">Oxley</span>, Mr., on the nutmeg tree, ii. <a href="#page237">237</a>.</p> + <p><span class="sc">Oysters</span>, differences in the shells of, ii. <a href="#page280">280</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Paca</span>, sterility of the, in confinement, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Pacific</span> islands, pigs of the, i. 70.</p> + <p><span class="sc">Padua</span>, earliest known flower garden at, ii. <a href="#page217">217</a>.</p> + <p><span class="sc">Paduan</span> fowl of Aldrovandi, i. 247.</p> + <p><i>Pæonia moutan</i>, ii. <a href="#page205">205</a>.</p> + <p><span class="sc">Pæony</span>, tree, ancient cultivation of, in China, ii. <a href="#page205">205</a>.</p> + <p><span class="sc">Pampas</span>, feral cattle on the, i. 85.</p> + <p><i>Pandanus</i>, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Pangenesis</span>, hypothesis of, ii. <a href="#page357">357</a>-<a href="#page404">404</a>.</p> + <p><i>Panicum</i>, seeds of, used as food, i. 309;</p> + <p class="i2">found in the Swiss lake-dwellings, i. 317.</p> + <p><span class="sc">Pansy</span>, i. 368-370.</p> + <p><span class="sc">Pappus</span>, abortion of the, in <i>Carthamus</i>, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Paget</span>, on the Hungarian sheep dog, i. 24.</p> + <p><span class="sc">Paget</span>, inheritance of cancer, ii. <a href="#page7">7</a>;</p> + <p class="i2">hereditary elongation of hairs in the eyebrow, ii. <a href="#page8">8</a>;</p> + <p class="i2">period of inheritance of cancer, ii. <a href="#page79">79</a>-<a href="#page80">80</a>;</p> + <p class="i2">on <i>Hydra</i>, ii. <a href="#page293">293</a>;</p> + <p class="i2">on the healing of wounds, ii. <a href="#page294">294</a>;</p> + <p class="i2">on the reparation of bones, <i>ibid.</i>;</p> + <p class="i2">growth of hair near inflamed surfaces or fractures, ii. <a href="#page295">295</a>;</p> + <p class="i2">on false membranes, <i>ibid.</i>;</p> + <p class="i2">compensatory development of the kidney, ii. <a href="#page300">300</a>;</p> + <p class="i2">bronzed skin in disease of supra-renal capsules, ii. <a href="#page331">331</a>;</p> + <p class="i2">unity of growth and gemmation, ii. <a href="#page359">359</a>;</p> + <p class="i2">independence of the elements of the body, ii. <a href="#page369">369</a>;</p> + <p class="i2">affinity of the tissues for special organic substances, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Pallas</span>, on the influence of domestication upon the sterility of intercrossed species, i. 31, 83, 193, ii. <a href="#page109">109</a>;</p> + <p class="i2">hypothesis that variability is wholly due to crossing, i. 188, 374, ii. <a href="#page250">250</a>, <a href="#page264">264</a>;</p> + <p class="i2">on the origin of the dog, i. 16;</p> + <p class="i2">variation in dogs, i. 33;</p> + <p class="i2">crossing of dog and jackal, i. 25;</p> + <p class="i2">origin of domestic cats, i. 43;</p> + <p class="i2">origin of Angora cat, i. 45;</p> + <p class="i2">on wild horses, i. 52, 60;</p> + <p class="i2">on Persian sheep, i. 94;</p> + <p class="i2">on Siberian fat-tailed sheep, ii. <a href="#page279">279</a>;</p> + <p class="i2">on Chinese sheep, ii. <a href="#page315">315</a>;</p> + <p class="i2">on Crimean varieties of the vine, i. 333;</p> + <p class="i2">on a grape with rudimentary seeds, ii. <a href="#page316">316</a>;</p> + <p class="i2">on feral musk-ducks, ii. <a href="#page46">46</a>;</p> + <p class="i2">sterility of Alpine plants in gardens, ii. <a href="#page163">163</a>;</p> + <p class="i2">selection of white-tailed yaks, ii. <a href="#page206">206</a>.</p> + <p><i>Paradoxurus</i>, sterility of species of, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Paraguay</span>, cats of, i. 46;</p> + <p class="i2">cattle of, i. 89;</p> + <p class="i2">horses of, ii. <a href="#page102">102</a>;</p> + <p class="i2">dogs of, ii. <a href="#page102">102</a>;</p> + <p class="i2">black-skinned domestic fowl of, i. 232.</p> + <p><span class="sc">Parallel</span> variation, ii. <a href="#page348">348</a>-<a href="#page352">352</a>.</p> + <p><span class="sc">Paramos</span>, woolly pigs of, i. 78.</p> + <p><span class="sc">Parasites</span>, liability to attacks of, dependent on colour, ii. <a href="#page228">228</a>.</p> + <p><span class="sc">Pariah</span> dog, with crooked legs, i. 17;</p> + <p class="i2">resembling the Indian wolf, i. 24.</p> + <p><span class="sc">Pariset</span>, inheritance of handwriting, ii. <a href="#page6">6</a>.</p> + <p><span class="sc">Parker</span>, W. K., number of vertebræ in fowls, i. 266.</p> + <p><span class="sc">Parkinson</span>, Mr., varieties of the hyacinth, i. 370.</p> + <p><span class="sc">Parkyns</span>, Mansfield, on <i>Columba guinea</i>, i. 183.</p> + <p><span class="sc">Parmentier</span>, differences in the nidification of pigeons, i. 178;</p> + <p class="i2">on white pigeons, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Parrots</span>, general sterility of, in confinement, ii. <a href="#page155">155</a>;</p> + <p class="i2">alteration of plumage of, ii. <a href="#page280">280</a>.</p> + <p><span class="sc">Parsnip</span>, reversion in, ii. <a href="#page31">31</a>;</p> + <p class="i2">influence of selection on, ii. <a href="#page201">201</a>;</p> + <p class="i2">experiments on, ii. <a href="#page277">277</a>;</p> + <p class="i2">wild, enlargement of roots of, by cultivation, i. 326.</p> + <p><span class="sc">Parthenogenesis</span>, ii. <a href="#page359">359</a>, <a href="#page364">364</a>.</p> + <p><span class="sc">Partridge</span>, sterility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Parturition</span>, difficult, hereditary, ii. <a href="#page8">8</a>.</p> + <p><i>Parus major</i>, ii. <a href="#page231">231</a>.</p> + <p><i>Passiflora</i>, self-impotence in species of, ii. <a href="#page137">137</a>-<a href="#page138">138</a>;</p> + <p class="i2">contabescence of female organs in, ii. <a href="#page166">166</a>.</p> + <p><i>Passiflora alata</i>, fertility of, when grafted, ii. <a href="#page188">188</a>.</p> + <p><span class="sc">Pasture</span> and climate, adaptation of breeds of sheep to, i. 96, 97.</p> + <p><span class="sc">Pastrana</span>, Julia, peculiarities in the hair and teeth of, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Patagonia</span>, crania of pigs from, i. 77.</p> + <p><span class="sc">Patagonian</span> rabbit, i. 105.</p> +<!-- Page 469 --><span class="pagenum"><a name="page469"></a>{469}</span> + <p><span class="sc">Paterson</span>, R., on the Arrindy silk moth, ii. <a href="#page306">306</a>.</p> + <p><span class="sc">Paul</span>, W., on the hyacinth, i. 370;</p> + <p class="i2">varieties of pelargoniums, i. 378;</p> + <p class="i2">improvement of pelargoniums, ii. <a href="#page216">216</a>.</p> + <p><i>Pavo cristatus</i> and <i>muticus</i>, hybrids of, i. 290.</p> + <p><i>Pavo nigripennis</i>, i. 290-291.</p> + <p>"<span class="sc">Pavodotten-Taube</span>," i. 141.</p> + <p><span class="sc">Peach</span>, i. 336-344;</p> + <p class="i2">derived from the almond, i. 337;</p> + <p class="i2">stones of, figured, <i>ibid.</i>;</p> + <p class="i2">contrasted with almonds, i. 338;</p> + <p class="i2">double-flowering, i. 338-339, 343;</p> + <p class="i2">hybrids of, i. 339;</p> + <p class="i2">persistency of races of, <i>ibid.</i>;</p> + <p class="i2">trees producing nectarines, i. 340-341;</p> + <p class="i2">variation in, i. 342-343, ii. <a href="#page256">256</a>;</p> + <p class="i2">bud-variation in, i. 374;</p> + <p class="i2">pendulous, ii. <a href="#page18">18</a>;</p> + <p class="i2">variation by selection in, ii. <a href="#page218">218</a>;</p> + <p class="i2">peculiar disease of the, ii. <a href="#page228">228</a>;</p> + <p class="i2">glands on the leaves of the, ii. <a href="#page231">231</a>;</p> + <p class="i2">antiquity of the, ii. <a href="#page308">308</a>;</p> + <p class="i2">increased hardiness of the, <i>ibid.</i>;</p> + <p class="i2">varieties of, adapted for forcing, ii. <a href="#page310">310</a>;</p> + <p class="i2">yellow-fleshed, liable to certain diseases, ii. <a href="#page336">336</a>.</p> + <p><span class="sc">Peach-almond</span>, i. 338.</p> + <p><span class="sc">Peafowl</span>, origin of, i. 290;</p> + <p class="i2">japanned or black-shouldered, i. 290-291;</p> + <p class="i2">feral, in Jamaica, i. 190;</p> + <p class="i2">comparative fertility of, in wild and tame states, ii. <a href="#page112">112</a>, <a href="#page268">268</a>;</p> + <p class="i2">white, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Pears</span>, i. 350;</p> + <p class="i2">bud-variation in, i. 376;</p> + <p class="i2">reversion in seedling, ii. <a href="#page31">31</a>;</p> + <p class="i2">inferiority of, in Pliny's time, ii. <a href="#page215">215</a>;</p> + <p class="i2">winter nelis, attacked by aphides, ii. <a href="#page231">231</a>;</p> + <p class="i2">soft-barked varieties of, attacked by wood-boring beetles, ii. <a href="#page231">231</a>;</p> + <p class="i2">origination of good varieties of, in woods, ii. <a href="#page260">260</a>;</p> + <p class="i2">Forelle, resistance of, to frost, ii. <a href="#page306">306</a>.</p> + <p><span class="sc">Peas</span>, i. 326-330;</p> + <p class="i2">origin of, 326;</p> + <p class="i2">varieties of, 326-329;</p> + <p class="i2">found in Swiss lake-dwellings, i. 317, 319, 326-329;</p> + <p class="i2">fruit and seeds figured, i. 328;</p> + <p class="i2">persistency of varieties, i. 329;</p> + <p class="i2">intercrossing of varieties, i. 330, 397, ii. <a href="#page129">129</a>;</p> + <p class="i2">effect of crossing on the female organs in, i. 398;</p> + <p class="i2">double-flowered, ii. <a href="#page168">168</a>;</p> + <p class="i2">maturity of, accelerated by selection, ii. <a href="#page201">201</a>;</p> + <p class="i2">varieties of, produced by selection, ii. <a href="#page218">218</a>;</p> + <p class="i2">thin-shelled, liable to the attacks of birds, ii. <a href="#page231">231</a>;</p> + <p class="i2">reversion of, by the terminal seed in the pod, ii. <a href="#page347">347</a>.</p> + <p><span class="sc">Peccary</span>, breeding of the, in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Pedigrees</span> of horses, cattle, greyhounds, game-cocks, and pigs, ii. <a href="#page3">3</a>.</p> + <p><span class="sc">Pegu</span>, cats of, i. 47;</p> + <p class="i2">horses of, i. 53.</p> + <p><span class="sc">Pelargoniums</span>, multiple origin of, i. 364;</p> + <p class="i2">zones of, i. 366;</p> + <p class="i2">bud-variation in, i. 378;</p> + <p class="i2">variegation in, accompanied by dwarfing, i. 384;</p> + <p class="i2">pelorism in, ii. <a href="#page167">167</a>, <a href="#page345">345</a>;</p> + <p class="i2">by reversion, ii. <a href="#page59">59</a>;</p> + <p class="i2">advantage of change of soil to, ii. <a href="#page147">147</a>;</p> + <p class="i2">improvement of, by selection, ii. <a href="#page216">216</a>;</p> + <p class="i2">scorching of, ii. <a href="#page229">229</a>;</p> + <p class="i2">numbers of, raised from seed, ii. <a href="#page235">235</a>;</p> + <p class="i2">effects of conditions of life on, ii. <a href="#page274">274</a>;</p> + <p class="i2">stove-variety of, ii. <a href="#page311">311</a>;</p> + <p class="i2">correlation of contracted leaves and flowers in, ii. <a href="#page330">330</a>-<a href="#page331">331</a>.</p> + <p><i>Pelargonium fulgidum</i>, conditions of fertility in, ii. <a href="#page164">164</a>.</p> + <p>"<span class="sc">Pelones</span>," a Columbian breed of cattle, i. 88.</p> + <p><span class="sc">Peloric</span> flowers, tendency of, to acquire the normal form, ii. <a href="#page70">70</a>;</p> + <p class="i2">fertility or sterility of, ii. <a href="#page166">166</a>-<a href="#page167">167</a>.</p> + <p><span class="sc">Peloric</span> races of <i>Gloxinia speciosa</i> and <i>Antirrhinum majus</i>, i. 365.</p> + <p><span class="sc">Pelorism</span>, ii. <a href="#page58">58</a>-<a href="#page60">60</a>, <a href="#page345">345</a>-<a href="#page346">346</a>.</p> + <p><span class="sc">Pelvis</span>, characters of, in rabbits, i. 122-123;</p> + <p class="i2">in pigeons, i. 166;</p> + <p class="i2">in fowls, i. 268;</p> + <p class="i2">in ducks, i. 284.</p> + <p><span class="sc">Pembroke</span> cattle, i. 81.</p> + <p><span class="sc">Pendulous</span> trees, i. 361, ii. <a href="#page348">348</a>;</p> + <p class="i2">uncertainty of transmission of, ii. <a href="#page18">18</a>-<a href="#page19">19</a>.</p> + <p><span class="sc">Penguin</span> ducks, i. 280, 282;</p> + <p class="i2">hybrid of the, with the Egyptian goose, i. 282.</p> + <p><span class="sc">Pennant</span>, production of wolf-like curs at Fochabers, i. 37;</p> + <p class="i2">on the Duke of Queensberry's wild cattle, i. 84.</p> + <p><i>Pennisetum</i>, seeds of, used as food in the Punjab, i. 309.</p> + <p><i>Pennisetum distichum</i>, seeds of, used as food in Central Africa, i. 308.</p> + <p><span class="sc">Percival</span>, Mr., on inheritance in horses, ii. <a href="#page10">10</a>;</p> + <p class="i2">on horn-like processes in horses, i. 50.</p> + <p><i>Perdix rubra</i>, occasional fertility of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Period</span> of action of causes of variability, ii. <a href="#page269">269</a>.</p> + <p><span class="sc">Periosteum</span> of a dog, producing bone in a rabbit, ii. <a href="#page369">369</a>.</p> + <p><span class="sc">Periwinkle</span>, sterility of, in England, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Persia</span>, estimation of pigeons in, i. 205;</p> + <p class="i2">carrier pigeon of, i. 141;</p> + <p class="i2">tumbler pigeon of, i. 150;</p> + <p class="i2">cats of, i. 45-47;</p> + <p class="i2">sheep of, i. 94.</p> + <p><i>Persica intermedia</i>, i. 338.</p> + <p><span class="sc">Persistence</span> of colour in horses, i. 50;</p> + <p class="i2">of generic peculiarities, i. 111.</p> + <p><span class="sc">Peru</span>, antiquity of maize in, i. 320;</p> + <p class="i2">peculiar potato from, i. 331;</p> + <p class="i2">selection of wild animals practised by the Incas of, ii. <a href="#page207">207</a>-<a href="#page208">208</a>.</p> + <p>"<span class="sc">Perücken-Taube</span>," i. 154.</p> + <p><span class="sc">Petals</span>, rudimentary, in cultivated plants, ii. <a href="#page316">316</a>;</p> + <p class="i2">producing pollen, ii. <a href="#page392">392</a>.</p> + <p><span class="sc">Petunias</span>, multiple origin of, i. 364;</p> + <p class="i2">double-flowered, ii. <a href="#page167">167</a>.</p> + <p>"<span class="sc">Pfauen-Taube</span>," i. 146.</p> + <p><i>Phacochœrus Africanus</i>, i. 76.</p> + <p><i>Phalænopsis</i>, pelorism in, ii. <a href="#page346">346</a>.</p> + <p><span class="sc">Phalanges</span>, deficiency of, ii. <a href="#page73">73</a>.</p> +<!-- Page 470 --><span class="pagenum"><a name="page470"></a>{470}</span> + <p><i>Phaps chalcoptera</i>, ii. <a href="#page349">349</a>.</p> + <p><i>Phaseolus multiflorus</i>, ii. <a href="#page309">309</a>, <a href="#page322">322</a>.</p> + <p><i>Phaseolus vulgaris</i>, ii. <a href="#page309">309</a>.</p> + <p><i>Phasianus pictus</i>, i. 275.</p> + <p><i>Phasianus Amherstiæ</i>, i. 275.</p> + <p><span class="sc">Pheasant</span>, assumption of male plumage by the hen, ii. <a href="#page51">51</a>;</p> + <p class="i2">wildness of hybrids of, with the common fowl, ii. <a href="#page45">45</a>;</p> + <p class="i2">prepotency of the, over the fowl, ii. <a href="#page68">68</a>;</p> + <p class="i2">diminished fecundity of the, in captivity, ii. <a href="#page155">155</a>.</p> + <p><span class="sc">Pheasants</span>, golden and Lady Amherst's, i. 275.</p> + <p><span class="sc">Pheasant-fowls</span>, i. 244.</p> + <p><span class="sc">Philipeaux</span>, regeneration of limbs in the salamander, ii. <a href="#page376">376</a>.</p> + <p><span class="sc">Philippar</span>, on the varieties of wheat, i. 314.</p> + <p><span class="sc">Philippine</span> Islands, named breeds of game fowl in the, i. 232.</p> + <p><span class="sc">Phillips</span>, Mr., on bud-variation in the potato, i. 385.</p> + <p><i>Phlox</i>, bud-variation by suckers in, i. 384.</p> + <p><span class="sc">Phthisis</span>, affection of the fingers in, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Pickering</span>, Mr., on the grunting voice of humped cattle, i. 79;</p> + <p class="i2">occurrence of the head of a fowl in an ancient Egyptian procession, i. 246;</p> + <p class="i2">seeding of ordinarily seedless fruits, ii. <a href="#page168">168</a>;</p> + <p class="i2">extinction of ancient Egyptian breeds of sheep and oxen, ii. <a href="#page425">425</a>;</p> + <p class="i2">on an ancient Peruvian gourd, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Picotees</span>, effect of conditions of life on, ii. <a href="#page273">273</a>.</p> + <p><span class="sc">Pictet</span>, A., oriental names of the pigeon, i. 205.</p> + <p><span class="sc">Pictet</span>, Prof., origin of the dog, i. 15;</p> + <p class="i2">on fossil oxen, i. 81.</p> + <p><span class="sc">Piebalds</span>, probably due to reversion, ii. <a href="#page37">37</a>.</p> + <p><span class="sc">Pigeaux</span>, hybrids of the hare and rabbit, ii. <a href="#page99">99</a>, <a href="#page152">152</a>.</p> + <p><span class="sc">Pigeon</span> à cravate, i. 148.</p> + <p><span class="sc">Pigeon</span> Bagadais, i. 142, 143.</p> + <p><span class="sc">Pigeon</span> coquille, i. 155.</p> + <p><span class="sc">Pigeon</span> cygne, i. 143.</p> + <p><span class="sc">Pigeon</span> heurté, i. 156.</p> + <p><span class="sc">Pigeon</span> Patu plongeur, i. 156.</p> + <p><span class="sc">Pigeon</span> Polonais, i. 144.</p> + <p><span class="sc">Pigeon</span> Romain, i. 142, 144.</p> + <p><span class="sc">Pigeon</span> tambour, i. 154.</p> + <p><span class="sc">Pigeon</span> Turc, i. 139.</p> + <p><span class="sc">Pigeons</span>, origin of, i. 131-134, 180-204;</p> + <p class="i2">classified table of breeds of, i. 136;</p> + <p class="i2">pouter, i. 137-139;</p> + <p class="i2">carrier, i. 139-142;</p> + <p class="i2">runt, i. 142-144;</p> + <p class="i2">barbs, i. 144-146;</p> + <p class="i2">fantail, i. 146-148;</p> + <p class="i2">turbit and owl, i. 148-149;</p> + <p class="i2">tumbler, i. 150-153;</p> + <p class="i2">Indian frill-back, i. 153;</p> + <p class="i2">Jacobin, i. 154;</p> + <p class="i2">trumpeter, i. 154;</p> + <p class="i2">other breeds of, i. 155-157;</p> + <p class="i2">differences of, equal to generic, i. 157-158;</p> + <p class="i2">individual variations of, i. 158-160;</p> + <p class="i2">variability of peculiarities characteristic of breeds in, i. 161;</p> + <p class="i2">sexual variability in, i. 161-162;</p> + <p class="i2">osteology of, i. 162-167;</p> + <p class="i2">correlation of growth in, i. 167-171, ii. <a href="#page321">321</a>;</p> + <p class="i2">young of some varieties naked when hatched, i. 170, ii. <a href="#page332">332</a>;</p> + <p class="i2">effects of disuse in, i. 172-177;</p> + <p class="i2">settling and roosting in trees, i. 181;</p> + <p class="i2">floating in the Nile to drink, i. 181;</p> + <p class="i2">Dovecot, i. 185-186;</p> + <p class="i2">arguments for unity of origin of, i. 188-204;</p> + <p class="i2">feral in various places, i. 190, ii. <a href="#page33">33</a>;</p> + <p class="i2">unity of coloration in, i. 195-197;</p> + <p class="i2">reversion of mongrel, to coloration of, <i>C. livia</i>, i. 197-202;</p> + <p class="i2">history of the cultivation of, i. 205-207;</p> + <p class="i2">history of the principal races of, i. 207-212;</p> + <p class="i2">mode of production of races of, i. 212-224;</p> + <p class="i2">reversion in, ii. <a href="#page29">29</a>, <a href="#page47">47</a>;</p> + <p class="i2">by age, ii. <a href="#page38">38</a>;</p> + <p class="i2">produced by crossing in, ii. <a href="#page40">40</a>, <a href="#page48">48</a>;</p> + <p class="i2">prepotency of transmission of character in breeds of, ii. <a href="#page66">66</a>-<a href="#page67">67</a>;</p> + <p class="i2">sexual differences in some varieties of, ii. <a href="#page74">74</a>;</p> + <p class="i2">period of perfect plumage in, ii. <a href="#page77">77</a>;</p> + <p class="i2">effect of segregation on, ii. <a href="#page86">86</a>;</p> + <p class="i2">preferent pairing of, within the same breed, ii. <a href="#page103">103</a>;</p> + <p class="i2">fertility of, increased by domestication, ii. <a href="#page112">112</a>, <a href="#page155">155</a>;</p> + <p class="i2">effects of interbreeding and necessity of crossing, ii. <a href="#page125">125</a>-126;</p> + <p class="i2">indifference of, to change of climate, ii. <a href="#page161">161</a>;</p> + <p class="i2">selection of, ii. <a href="#page195">195</a>, <a href="#page199">199</a>, <a href="#page204">204</a>;</p> + <p class="i2">among the Romans, ii. <a href="#page202">202</a>;</p> + <p class="i2">unconscious selection of, ii. <a href="#page211">211</a>, <a href="#page214">214</a>;</p> + <p class="i2">facility of selection of, ii. <a href="#page234">234</a>;</p> + <p class="i2">white, liable to the attacks of hawks, ii. <a href="#page230">230</a>;</p> + <p class="i2">effects of disuse of parts in, ii. <a href="#page298">298</a>;</p> + <p class="i2">fed upon meat, ii. <a href="#page304">304</a>;</p> + <p class="i2">effect of first male upon the subsequent progeny of the female, i. 405;</p> + <p class="i2">homology of the leg and wing feathers in, ii. <a href="#page323">323</a>;</p> + <p class="i2">union of two outer toes in feather-legged, <i>ibid.</i>;</p> + <p class="i2">correlation of beak, limbs, tongue, and nostrils in, ii. <a href="#page324">324</a>;</p> + <p class="i2">analogous variation in, ii. <a href="#page349">349</a>-<a href="#page350">350</a>;</p> + <p class="i2">permanence of breeds of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Pigs</span>, of Swiss lake-dwellings, i. 67-68;</p> + <p class="i2">types of, derived from <i>Sus scrofa</i> and <i>Sus indica</i>, i. 66-67;</p> + <p class="i2">Japanese (<i>Sus pliciceps</i>, Gray), figured, i. 69;</p> + <p class="i2">of Pacific islands, i. 70, ii. <a href="#page87">87</a>;</p> + <p class="i2">modifications, of skull in, i. 71-73;</p> + <p class="i2">length of intestines in, i. 73, ii. <a href="#page303">303</a>;</p> + <p class="i2">period of gestation of, i. 74;</p> + <p class="i2">number of vertebræ and ribs in, i. 74;</p> + <p class="i2">anomalous forms, i. 75-76;</p> + <p class="i2">development of tusks and bristles in, i. 76;</p> + <p class="i2">striped young of, i. 76-77;</p> + <p class="i2">reversion of feral, to wild type, i. 77-78, ii. <a href="#page33">33</a>, <a href="#page47">47</a>;</p> + <p class="i2">production and changes of breeds of, by intercrossing, i. 78;</p> + <p class="i2">effects produced by the first male upon the subsequent progeny of the female, i. 404;</p> + <p class="i2">two-legged race of, ii. <a href="#page4">4</a>;</p> +<!-- Page 471 --><span class="pagenum"><a name="page471"></a>{471}</span> + <p class="i2">polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">cross-reversion in, ii. <a href="#page35">35</a>;</p> + <p class="i2">hybrid, wildness of, ii. <a href="#page45">45</a>;</p> + <p class="i2">monstrous development of a proboscis in, ii. <a href="#page57">57</a>;</p> + <p class="i2">disappearance of tusks in male under domestication, ii, 74;</p> + <p class="i2">solid hoofed, ii. <a href="#page429">429</a>;</p> + <p class="i2">crosses of, ii. <a href="#page93">93</a>, <a href="#page95">95</a>;</p> + <p class="i2">mutual fertility of all varieties of, ii. <a href="#page110">110</a>;</p> + <p class="i2">increased fertility by domestication, ii. <a href="#page111">111</a>;</p> + <p class="i2">ill effects of close interbreeding in, ii. <a href="#page121">121</a>-<a href="#page122">122</a>;</p> + <p class="i2">influence of selection on, ii. <a href="#page198">198</a>;</p> + <p class="i2">prejudice against certain colours in, ii. <a href="#page210">210</a>, <a href="#page229">229</a>, <a href="#page336">336</a>;</p> + <p class="i2">unconscious selection of, ii. <a href="#page214">214</a>;</p> + <p class="i2">black Virginian, ii. <a href="#page227">227</a>, <a href="#page336">336</a>;</p> + <p class="i2">similarity of the best breeds of, ii. <a href="#page241">241</a>;</p> + <p class="i2">change of form in, ii. <a href="#page279">279</a>;</p> + <p class="i2">effects of disuse of parts in, ii. <a href="#page299">299</a>;</p> + <p class="i2">ears of, ii. <a href="#page301">301</a>;</p> + <p class="i2">correlations in, ii. <a href="#page327">327</a>;</p> + <p class="i2">white, buck-wheat injurious to, ii. <a href="#page337">337</a>;</p> + <p class="i2">tail of, grafted upon the back, ii. <a href="#page369">369</a>;</p> + <p class="i2">extinction of the older races of, ii. <a href="#page426">426</a>.</p> + <p><span class="sc">Pimenta</span>, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Pimpernel</span>, ii. <a href="#page190">190</a>.</p> + <p><span class="sc">Pine-apple</span>, sterility and variability of the, ii. <a href="#page262">262</a>.</p> + <p><span class="sc">Pink</span>, Chinese. 322.</p> + <p><span class="sc">Pinks</span>, bud-variation in, i. 381;</p> + <p class="i2">improvement of, ii. <a href="#page216">216</a>.</p> + <p><i>Pinus pumilio</i>, <i>Mughus</i>, and <i>nana</i>, varieties of <i>P. sylvestris</i>, i. 363.</p> + <p><i>Pinus sylvestris</i>, i. 363, ii. <a href="#page310">310</a>;</p> + <p class="i2">hybrids of, with <i>P. nigricans</i>, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Piorry</span>, on hereditary disease, ii. <a href="#page7">7</a>, <a href="#page78">78</a>.</p> + <p><i>Pistacia lentiscus</i>, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Pistils</span>, rudimentary, in cultivated plants, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Pistor</span>, sterility of some mongrel pigeons, i. 192;</p> + <p class="i2">fertility of pigeons, ii. <a href="#page112">112</a>.</p> + <p><i>Pisum arvense</i> and <i>sativum</i>, i. 326.</p> + <p><span class="sc">Pityriasis</span> versicolor, inheritance of, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Planchon</span>, G., on a fossil vine, i. 332;</p> + <p class="i2">sterility of <i>Jussiæa grandifiora</i> in France, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Plane</span> tree, variety of the, i. 362.</p> + <p><span class="sc">Plantigrade</span> carnivora, general sterility of the, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Plants</span>, progress of cultivation of, i. 305-312;</p> + <p class="i2">cultivated, their geographical derivation, i. 311;</p> + <p class="i2">crossing of, ii. <a href="#page98">98</a>, <a href="#page99">99</a>, <a href="#page127">127</a>;</p> + <p class="i2">comparative fertility of wild and cultivated, ii. <a href="#page112">112</a>-<a href="#page113">113</a>;</p> + <p class="i2">self-impotent, ii. <a href="#page131">131</a>-<a href="#page140">140</a>;</p> + <p class="i2">dimorphic and trimorphic, ii. <a href="#page132">132</a>, <a href="#page140">140</a>;</p> + <p class="i2">sterility of, from changed conditions, ii. <a href="#page163">163</a>-<a href="#page165">165</a>;</p> + <p class="i2">from contabescence of anthers, ii. <a href="#page165">165</a>-<a href="#page166">166</a>;</p> + <p class="i2">from monstrosities, ii. <a href="#page166">166</a>-<a href="#page167">167</a>;</p> + <p class="i2">from doubling of the flowers, ii. <a href="#page167">167</a>-<a href="#page168">168</a>;</p> + <p class="i2">from seedless fruit, ii. <a href="#page168">168</a>;</p> + <p class="i2">from excessive development of vegetative organs, ii. <a href="#page168">168</a>-<a href="#page171">171</a>;</p> + <p class="i2">influence of selection on, ii. <a href="#page199">199</a>-<a href="#page201">201</a>;</p> + <p class="i2">variation by selection, in useful parts of, ii. <a href="#page217">217</a>-<a href="#page219">219</a>;</p> + <p class="i2">variability of, ii. <a href="#page237">237</a>;</p> + <p class="i2">variability of, induced by crossing, ii. <a href="#page265">265</a>;</p> + <p class="i2">direct action of change of climate on, ii. <a href="#page277">277</a>;</p> + <p class="i2">change of period of vegetation in, ii. <a href="#page304">304</a>-<a href="#page305">305</a>;</p> + <p class="i2">varieties of, suitable to different climates, ii. <a href="#page306">306</a>;</p> + <p class="i2">correlated variability of, ii. <a href="#page330">330</a>-<a href="#page331">331</a>;</p> + <p class="i2">antiquity of races of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Plasticity</span>, inheritance of, ii. <a href="#page241">241</a>.</p> + <p><span class="sc">Plateau</span>, F., on the vision of amphibious animals, ii. <a href="#page223">223</a>.</p> + <p><i>Platessa flesus</i>, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Plato</span>, notice of selection in breeding dogs by, ii. <a href="#page212">212</a>.</p> + <p><span class="sc">Plica</span> polonica, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Pliny</span>, on the crossing of shepherd's dogs with the wolf, i. 24;</p> + <p class="i2">on Pyrrhus' breed of cattle, ii. <a href="#page202">202</a>;</p> + <p class="i2">on the estimation of pigeons among the Romans, i. 205;</p> + <p class="i2">pears described by, ii. <a href="#page215">215</a>.</p> + <p><span class="sc">Plum</span>, i. 345-347;</p> + <p class="i2">stones figured, i. 345;</p> + <p class="i2">varieties of the, i. 345-346, ii. <a href="#page219">219</a>;</p> + <p class="i2">bud-variation in the, i. 375;</p> + <p class="i2">peculiar disease of the, ii. <a href="#page227">227</a>;</p> + <p class="i2">flower-buds of, destroyed by bullfinches, ii. <a href="#page232">232</a>;</p> + <p class="i2">purple-fruited, liable to certain diseases, ii. <a href="#page336">336</a>.</p> + <p><span class="sc">Plumage</span>, inherited peculiarities of, in pigeons, i. 160-161;</p> + <p class="i2">sexual peculiarities of, in fowls, i. 251-255.</p> + <p><span class="sc">Plurality</span> of races, Pouchet's views on, i. 2.</p> + <p><i>Poa</i>, seeds of, used as food, i. 308;</p> + <p class="i2">species of, propagated by bulblets, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Podolian</span> cattle, i. 80.</p> + <p><span class="sc">Pointers</span>, modification of, i. 42;</p> + <p class="i2">crossed with the foxhound, ii. <a href="#page95">95</a>.</p> + <p><span class="sc">Pois</span> sans parchemin, ii. <a href="#page231">231</a>.</p> + <p><span class="sc">Poiteau</span>, origin of <i>Cytisus Adami</i>, i. 390;</p> + <p class="i2">origin of cultivated varieties of fruit-trees, ii. <a href="#page260">260</a>.</p> + <p><span class="sc">Polish</span> fowl, i. 227, 250, 254, 256-257, 262;</p> + <p class="i2">skull figured, i. 262;</p> + <p class="i2">section of skull figured, i. 263;</p> + <p class="i2">development of protuberance of skull, i. 250;</p> + <p class="i2">furcula figured, i. 268.</p> + <p><span class="sc">Polish</span>, or Himalayan rabbit, i. 108.</p> + <p><span class="sc">Pollen</span>, ii. <a href="#page363">363</a>-<a href="#page364">364</a>;</p> + <p class="i2">action of, ii. <a href="#page108">108</a>;</p> + <p class="i2">injurious action of, in some orchids, ii. <a href="#page134">134</a>-<a href="#page135">135</a>;</p> + <p class="i2">resistance of, to injurious treatment, ii. <a href="#page164">164</a>;</p> + <p class="i2">prepotency of, ii. <a href="#page187">187</a>.</p> + <p><span class="sc">Pollock</span>, Sir F., transmission of variegated leaves in <i>Ballota nigra</i>, i. 383;</p> + <p class="i2">on local tendency to variegation, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Polyanthus</span>, ii. <a href="#page21">21</a>.</p> + <p><span class="sc">Polydactylism</span>, inheritance of, ii. <a href="#page12">12</a>-<a href="#page16">16</a>;</p> + <p class="i2">significance of, ii. <a href="#page16">16</a>-<a href="#page17">17</a>.</p> + <p><i>Polyplectron</i>, i. 255.</p> + <p><span class="sc">Ponies</span>, most frequent on islands and mountains, i. 52;</p> + <p class="i2">Javanese, i. 53.</p> + <p><span class="sc">Poole</span>, Col., on striped Indian horses, i. 58, 59;</p> +<!-- Page 472 --><span class="pagenum"><a name="page472"></a>{472}</span> + <p class="i2">on the young of <i>Asinus indicus</i>, ii. <a href="#page43">43</a>.</p> + <p><span class="sc">Poplar</span>, Lombardy, i. 361.</p> + <p><span class="sc">Pöppig</span>, on Cuban wild dogs, i. 27.</p> + <p><span class="sc">Poppy</span>, found in the Swiss lake-dwellings, i. 317, 319;</p> + <p class="i2">with the stamens converted into pistils, i. 365;</p> + <p class="i2">differences of the, in different parts of India, ii. <a href="#page165">165</a>;</p> + <p class="i2">monstrous, fertility of, ii. <a href="#page166">166</a>;</p> + <p class="i2">black-seeded, antiquity of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Porcupine</span>, breeding of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Porcupine</span> family, ii. <a href="#page4">4</a>, <a href="#page76">76</a>.</p> + <p><i>Porphyrio</i>, breeding of a species of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Portal</span>, on a peculiar hereditary affection of the eye, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">Porto</span> Santo, feral rabbits of, i. 112.</p> + <p><i>Potamochœrus penicillatus</i>, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Potato</span>, i. 330-331;</p> + <p class="i2">bud-variation by tubers in the, i. 384-385;</p> + <p class="i2">graft-hybrid of, by union of half-tubers, i. 395;</p> + <p class="i2">individual self-impotence in the, ii. <a href="#page137">137</a>;</p> + <p class="i2">sterility of, ii. <a href="#page169">169</a>;</p> + <p class="i2">advantage of change of soil to the, ii. <a href="#page146">146</a>;</p> + <p class="i2">relation of tubers and flowers in the, ii. <a href="#page343">343</a>.</p> + <p><span class="sc">Potato</span>, sweet, sterility of the, in China, ii. <a href="#page169">169</a>;</p> + <p class="i2">varieties of the, suited to different climates, ii. <a href="#page309">309</a>.</p> + <p><span class="sc">Pouchet</span>, M., his views on plurality of races, i. 2.</p> + <p><span class="sc">Pouter</span> pigeons, i. 137-139;</p> + <p class="i2">furcula figured, i. 167;</p> + <p class="i2">history of, i. 207.</p> + <p><span class="sc">Powis</span>, Lord, experiments in crossing humped and English cattle, i. 83, ii. <a href="#page45">45</a>.</p> + <p><span class="sc">Poynter</span>, Mr., on a graft-hybrid rose, i. 396.</p> + <p><span class="sc">Prairie</span> wolf, i. 22.</p> + <p><span class="sc">Precocity</span> of highly-improved breeds, ii. <a href="#page321">321</a>.</p> + <p><span class="sc">Prepotency</span> of pollen, ii. <a href="#page187">187</a>.</p> + <p><span class="sc">Prepotency</span> of transmission of character, ii. <a href="#page65">65</a>, <a href="#page174">174</a>;</p> + <p class="i2">in the Austrian emperors and some Roman families, ii. <a href="#page65">65</a>;</p> + <p class="i2">in cattle, ii. <a href="#page65">65</a>-<a href="#page66">66</a>;</p> + <p class="i2">in sheep, ii. <a href="#page66">66</a>;</p> + <p class="i2">in cats, <i>ibid.</i>;</p> + <p class="i2">in pigeons, ii. <a href="#page66">66</a>-<a href="#page67">67</a>;</p> + <p class="i2">in fowls, ii. <a href="#page67">67</a>;</p> + <p class="i2">in plants, <i>ibid.</i>;</p> + <p class="i2">in a variety of the pumpkin, i. 358;</p> + <p class="i2">in the jackal over the dog, ii. <a href="#page67">67</a>;</p> + <p class="i2">in the ass over the horse, <i>ibid.</i>;</p> + <p class="i2">in the pheasant over the fowl, ii. <a href="#page68">68</a>;</p> + <p class="i2">in the penguin duck over the Egyptian goose, <i>ibid.</i>;</p> + <p class="i2">discussion of the phenomena of, ii. <a href="#page69">69</a>-<a href="#page71">71</a>.</p> + <p><span class="sc">Prescott</span>, Mr., on the earliest known European flower-garden, ii. <a href="#page217">217</a>.</p> + <p><span class="sc">Pressure</span>, mechanical, a cause of modification, ii. <a href="#page344">344</a>-<a href="#page345">345</a>.</p> + <p><span class="sc">Prevost</span> and Dumas, on the employment of several spermatozoids to fertilise one ovule, ii. <a href="#page363">363</a>.</p> + <p><span class="sc">Price</span>, Mr., variations in the structure of the feet in horses, i. 50.</p> + <p><span class="sc">Prichard</span>, Dr., on polydactylism in the negro, ii. <a href="#page14">14</a>;</p> + <p class="i2">on the Lambert family, ii. <a href="#page77">77</a>;</p> + <p class="i2">on an albino negro, ii. <a href="#page229">229</a>;</p> + <p class="i2">on Plica polonica, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Primrose</span>, ii. <a href="#page21">21</a>;</p> + <p class="i2">double, rendered single by transplantation, ii. <a href="#page167">167</a>.</p> + <p><i>Primula</i>, intercrossing of species of, i. 336;</p> + <p class="i2">contabescence in, ii. <a href="#page166">166</a>;</p> + <p class="i2">hose and hose, i. 365;</p> + <p class="i2">with coloured calyces, sterility of, ii. <a href="#page166">166</a>.</p> + <p><i>Primula sinensis</i>, reciprocally dimorphic, ii. <a href="#page132">132</a>.</p> + <p><i>Primula veris</i>, ii. <a href="#page21">21</a>, <a href="#page109">109</a>, <a href="#page182">182</a>.</p> + <p><i>Primula vulgaris</i>, ii. <a href="#page21">21</a>, <a href="#page109">109</a>.</p> + <p><span class="sc">Prince</span>, Mr., on the intercrossing of strawberries, i. 352.</p> + <p><i>Procyon</i>, sterility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Prolificacy</span>, increased by domestication, ii. <a href="#page174">174</a>.</p> + <p><span class="sc">Propagation</span>, rapidity of, favourable to selection, ii. <a href="#page297">297</a>.</p> + <p><span class="sc">Protozoa</span>, reproduction of the, ii. <a href="#page376">376</a>.</p> + <p><i>Prunus armeniaca</i>, i. 344-345.</p> + <p><i>Prunus avium</i>, i. 347.</p> + <p><i>Prunus cerasus</i>, i. 347, 375.</p> + <p><i>Prunus domestica</i>, i. 345.</p> + <p><i>Prunus insititia</i>, i. 345-347.</p> + <p><i>Prunus spinosa</i>, i. 345.</p> + <p><span class="sc">Prussia</span>, wild horses in, i. 60.</p> + <p><i>Psittacus erithacus</i>, ii. <a href="#page155">155</a>.</p> + <p><i>Psittacus macoa</i>, ii. <a href="#page155">155</a>.</p> + <p><i>Psophia</i>, general sterility of, in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Ptarmigan</span> fowls, i. 228.</p> + <p><i>Pulex penetrans</i>, ii. <a href="#page275">275</a>.</p> + <p><span class="sc">Pumpkins</span>, i. 357.</p> + <p><span class="sc">Puno</span> ponies of the Cordillera, i. 52.</p> + <p><span class="sc">Purser</span>, Mr. on <i>Cytisus Adami</i>, i. 389.</p> + <p><span class="sc">Pusey</span>, Mr., preference of hares and rabbits for common rye, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Putsche</span> and Vertuch, varieties of the potato, i. 330.</p> + <p><span class="sc">Puvis</span>, effects of foreign pollen on apples, i. 401;</p> + <p class="i2">supposed non-variability of monotypic genera, ii. <a href="#page266">266</a>.</p> + <p><i>Pyrrhula vulgaris</i>, ii. <a href="#page232">232</a>;</p> + <p class="i2">assumption of the hen-plumage by the male, in confinement, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Pyrrhus</span>, his breed of cattle, ii. <a href="#page202">202</a>.</p> + <p><i>Pyrus</i>, fastigate Chinese species of, ii. <a href="#page277">277</a>.</p> + <p><i>Pyrus acerba</i>, i. 348.</p> + <p><i>Pyrus aucuparia</i>, ii. <a href="#page230">230</a>.</p> + <p><i>Pyrus communis</i>, i. 350, 376.</p> + <p><i>Pyrus malus</i>, i. 348, 376.</p> + <p><i>Pyrus paradisiaca</i>, i. 348.</p> + <p><i>Pyrus præcox</i>, i. 348.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Quagga</span>, effect of fecundation by, on the subsequent progeny of a mare, i. 403-404.</p> + <p><span class="sc">Quatrefages</span>, A. de, on the burrowing of a bitch to litter, i. 77;</p> +<!-- Page 473 --><span class="pagenum"><a name="page473"></a>{473}</span> + <p class="i2">selection in the silkworm, i. 301;</p> + <p class="i2">development of the wings in the silkmoth, i. 303, ii. <a href="#page298">298</a>;</p> + <p class="i2">on varieties of the mulberry, i. 334;</p> + <p class="i2">special raising of eggs of the silkmoth, ii. <a href="#page197">197</a>;</p> + <p class="i2">on disease of the silkworm, ii. <a href="#page228">228</a>;</p> + <p class="i2">on monstrosities in insects, ii. <a href="#page269">269</a>, <a href="#page391">391</a>;</p> + <p class="i2">on the Anglo-Saxon race in America, ii. <a href="#page276">276</a>;</p> + <p class="i2">on a change in the breeding season of the Egyptian goose, ii. <a href="#page304">304</a>;</p> + <p class="i2">fertilisation of the <i>Teredo</i>, ii. <a href="#page363">363</a>;</p> + <p class="i2">tendency to similarity in the best races, ii. <a href="#page241">241</a>;</p> + <p class="i2">on his "<i>tourbillon vital</i>," ii. <a href="#page61">61</a>;</p> + <p class="i2">on the independent existence of the sexual elements, ii. <a href="#page360">360</a>.</p> + <p><i>Quercus cerris</i>, i. 363.</p> + <p><i>Quercus robur</i> and <i>pedunculata</i>, hybrids of, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Quince</span>, pears grafted on the, ii. <a href="#page259">259</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Rabbits</span>, domestic, their origin, i. 103-105;</p> + <p class="i2">of Mount Sinai and Algeria, i. 105;</p> + <p class="i2">breeds of, i. 105-111;</p> + <p class="i2">Himalayan, Chinese, Polish, or Russian, i. 108-111, ii. <a href="#page97">97</a>;</p> + <p class="i2">feral, i. 111-115;</p> + <p class="i2">of Jamaica, i. 112;</p> + <p class="i2">of the Falkland islands, i. 112;</p> + <p class="i2">of Porto Santo, i. 112-115, ii. <a href="#page103">103</a>, <a href="#page279">279</a>;</p> + <p class="i2">osteological characters of, i. 115-129;</p> + <p class="i2">discussion of modifications in, i. 129-130;</p> + <p class="i2">one-eared, transmission of peculiarity of, ii. <a href="#page12">12</a>;</p> + <p class="i2">reversion in feral, ii. <a href="#page33">33</a>;</p> + <p class="i2">in the Himalayan, ii. <a href="#page41">41</a>;</p> + <p class="i2">crossing of white and coloured Angora, ii. <a href="#page92">92</a>;</p> + <p class="i2">comparative fertility of wild and tame, ii. <a href="#page111">111</a>;</p> + <p class="i2">high-bred, often bad breeders, ii. <a href="#page121">121</a>;</p> + <p class="i2">selection of, ii. <a href="#page204">204</a>;</p> + <p class="i2">white, liable to destruction, ii. <a href="#page230">230</a>;</p> + <p class="i2">effects of disuse of parts in, ii. <a href="#page298">298</a>;</p> + <p class="i2">skull of, affected by drooping ears, ii. <a href="#page301">301</a>;</p> + <p class="i2">length of intestines in, ii. <a href="#page303">303</a>;</p> + <p class="i2">correlation of ears and skull in, ii. <a href="#page324">324</a>-<a href="#page325">325</a>;</p> + <p class="i2">variations in skull of, ii. <a href="#page350">350</a>;</p> + <p class="i2">periosteum of a dog producing bone in, ii. <a href="#page369">369</a>.</p> + <p><span class="sc">Race-horse</span>, origin of, i. 54.</p> + <p><span class="sc">Races</span>, modification and formation of, by crossing, ii. <a href="#page95">95</a>-<a href="#page99">99</a>;</p> + <p class="i2">natural and artificial, ii. <a href="#page245">245</a>;</p> + <p class="i2">Pouchet's views on plurality of, i. 2;</p> + <p class="i2">of pigeons, i. 207-212.</p> + <p><span class="sc">Radishes</span>, i. 326; crossing of, ii. <a href="#page90">90</a>;</p> + <p class="i2">varieties of, ii. <a href="#page217">217</a>-<a href="#page218">218</a>.</p> + <p><span class="sc">Radclyffe</span>, W. F., effect of climate and soil on strawberries, i. 354;</p> + <p class="i2">constitutional differences in roses, i. 367.</p> + <p><span class="sc">Radlkofer</span>, retrogressive metamorphosis in mosses and algæ, ii. <a href="#page361">361</a>.</p> + <p><span class="sc">Raffles</span>, Sir Stamford, on the crossing of Javanese cattle with <i>Bos sondaicus</i>, ii. <a href="#page206">206</a>.</p> + <p><span class="sc">Ram</span>, goat-like, from the Cape of Good Hope, ii. <a href="#page66">66</a>.</p> + <p><span class="sc">Ranchin</span>, heredity of diseases, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Range</span> of gallinaceous birds on the Himalaya, i. 237.</p> + <p><i>Ranunculus ficaria</i>, ii. <a href="#page170">170</a>.</p> + <p><i>Ranunculus repens</i>, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Rape</span>, i. 325.</p> + <p><i>Raphanus sativus</i>, ii. <a href="#page343">343</a>.</p> + <p><span class="sc">Raspberry</span>, yellow-fruited, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Rattlesnake</span>, experiments with poison of the, ii. <a href="#page289">289</a>.</p> + <p><span class="sc">Raven</span>, stomach of, affected by vegetable diet, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Rawson</span>, A., self-impotence in hybrids of <i>Gladiolus</i>, ii. <a href="#page139">139</a>-<a href="#page140">140</a>.</p> + <p><span class="sc">Ré</span>, Le Compte, on the assumption of a yellow colour by all varieties of maize, i. 321.</p> + <p><span class="sc">Réaumur</span>, effect of confinement upon the cock, ii. <a href="#page52">52</a>;</p> + <p class="i2">fertility of fowls in most climates, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Reed</span>, Mr., atrophy of the limbs of rabbits, consequent on the destruction of their nerves, ii. <a href="#page297">297</a>.</p> + <p><span class="sc">Regeneration</span> of amputated parts in man, ii. <a href="#page14">14</a>;</p> + <p class="i2">in the human embryo, ii. <a href="#page15">15</a>;</p> + <p class="i2">in the lower vertebrata, insects, and myriapoda, <i>ibid.</i></p> + <p><span class="sc">Reindeer</span>, individuals recognised by the Laplanders, ii. <a href="#page251">251</a>.</p> + <p><span class="sc">Regnier</span>, early cultivation of the cabbage by the Celts, i. 324.</p> + <p><span class="sc">Reissek</span>, experiments in crossing <i>Cytisus purpureus</i> and <i>laburnum</i>, i. 389;</p> + <p class="i2">modification of a <i>Thesium</i> by <i>Œcidium</i>, ii. <a href="#page284">284</a>.</p> + <p><span class="sc">Relations</span>, characters of, reproduced in children, ii. <a href="#page34">34</a>.</p> + <p><span class="sc">Rengger</span>, occurrence of jaguars with crooked legs in Paraguay, i. 17;</p> + <p class="i2">naked dogs of Paraguay, i. 23, 31, ii. <a href="#page93">93</a>, <a href="#page102">102</a>;</p> + <p class="i2">feral dogs of La Plata, i. 27;</p> + <p class="i2">on the aguara, i. 26;</p> + <p class="i2">cats of Paraguay, i. 46, ii. <a href="#page86">86</a>, <a href="#page151">151</a>;</p> + <p class="i2">dogs of Paraguay, ii. <a href="#page87">87</a>;</p> + <p class="i2">feral pigs of Buenos Ayres, i. 77;</p> + <p class="i2">on the refusal of wild animals to breed in captivity, ii. <a href="#page149">149</a>;</p> + <p class="i2">on <i>Dicotyles labiatus</i>, ii. <a href="#page150">150</a>;</p> + <p class="i2">sterility of plantigrade carnivora in captivity, ii. <a href="#page152">152</a>;</p> + <p class="i2">on <i>Cavia aperea</i>, ii. <a href="#page152">152</a>;</p> + <p class="i2">sterility of <i>Cebus azaræ</i> in captivity, ii. <a href="#page153">153</a>;</p> + <p class="i2">abortions produced by wild animals in captivity, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Reproduction</span>, sexual and asexual, contrasted, ii. <a href="#page361">361</a>;</p> + <p class="i2">unity of forms of, ii. <a href="#page383">383</a>;</p> + <p class="i2">antagonism of, to growth, ii. <a href="#page384">384</a>.</p> + <p><i>Reseda odorata</i>, ii. <a href="#page237">237</a>.</p> + <p><span class="sc">Retinitis</span>, pigmentary, in deaf-mutes, ii. <a href="#page328">328</a>.</p> + <p><span class="sc">Reversion</span>, ii. <a href="#page28">28</a>-<a href="#page29">29</a>, <a href="#page372">372</a>-<a href="#page373">373</a>, <a href="#page396">396</a>, <a href="#page398">398</a>-<a href="#page402">402</a>;</p> + <p class="i2">in pigeons, ii. <a href="#page29">29</a>;</p> + <p class="i2">in cattle, ii. <a href="#page29">29</a>-<a href="#page30">30</a>;</p> + <p class="i2">in sheep, ii. <a href="#page30">30</a>;</p> + <p class="i2">in fowls, ii. <a href="#page31">31</a>;</p> + <p class="i2">in the heartsease, <i>ibid.</i>;</p> + <p class="i2">in vegetables, <i>ibid.</i>;</p> + <p class="i2">in feral animals and plants, ii. <a href="#page32">32</a>-<a href="#page34">34</a>;</p> + <p class="i2">to characters derived from a previous cross in man, dogs, pigeons, pigs, and fowls, ii. <a href="#page34">34</a>-<a href="#page35">35</a>;</p> +<!-- Page 474 --><span class="pagenum"><a name="page474"></a>{474}</span> + <p class="i2">in hybrids, ii. <a href="#page36">36</a>;</p> + <p class="i2">by bud-propagation in plants, ii. <a href="#page36">36</a>-<a href="#page38">38</a>;</p> + <p class="i2">by age in fowls, cattle, &c., ii. <a href="#page38">38</a>-<a href="#page39">39</a>;</p> + <p class="i2">caused by crossing, ii. <a href="#page39">39</a>-<a href="#page51">51</a>;</p> + <p class="i2">explained by latent characters, ii. <a href="#page51">51</a>-<a href="#page56">56</a>;</p> + <p class="i2">producing monstrosities, ii. <a href="#page57">57</a>;</p> + <p class="i2">producing peloric flowers, ii. <a href="#page58">58</a>-<a href="#page60">60</a>;</p> + <p class="i2">of feral pigs to the wild type, i. 77-78;</p> + <p class="i2">of supposed feral rabbits to the wild type, i. 104, 111, 115;</p> + <p class="i2">of pigeons, in coloration, when crossed, i. 197-202;</p> + <p class="i2">in fowls, i. 239-246;</p> + <p class="i2">in the silkworm, i. 302;</p> + <p class="i2">in the pansy, i. 369;</p> + <p class="i2">in a pelargonium, i. 378;</p> + <p class="i2">in Chrysanthemums, i. 379;</p> + <p class="i2">of varieties of the China rose in St. Domingo, i. 380;</p> + <p class="i2">by buds in pinks and carnations, i. 381;</p> + <p class="i2">of laciniated varieties of trees to the normal form, i. 382;</p> + <p class="i2">in variegated leaves of plants, i. 383-384;</p> + <p class="i2">in tulips, i. 386;</p> + <p class="i2">of suckers of the seedless barberry to the common form, i. 384;</p> + <p class="i2">by buds in hybrids of <i>Tropæolum</i>, i. 392;</p> + <p class="i2">in plants, i. 409;</p> + <p class="i2">of crossed peloric snapdragons, ii. <a href="#page71">71</a>;</p> + <p class="i2">analogous variations due to, ii. <a href="#page349">349</a>-<a href="#page351">351</a>.</p> + <p><span class="sc">Reynier</span>, selection practised by the Celts, ii. <a href="#page202">202</a>-<a href="#page203">203</a>.</p> + <p><span class="sc">Rhinoceros</span>, breeding in captivity in India, ii. <a href="#page150">150</a>.</p> + <p><i>Rhododendron</i>, hybrid, ii. <a href="#page265">265</a>.</p> + <p><i>Rhododendron ciliatum</i>, ii. <a href="#page277">277</a>.</p> + <p><i>Rhododendron Dalhousiæ</i>, effect of pollen of <i>R. Nuttallii</i> upon, i. 400.</p> + <p><span class="sc">Rhubarb</span>, not medicinal when grown in England, ii. <a href="#page274">274</a>.</p> + <p><i>Ribes grossularia</i>, i. 354-356, 376.</p> + <p><i>Ribes rubrum</i>, i. 376.</p> + <p><span class="sc">Ribs</span>, number and characters of, in fowls, i. 267;</p> + <p class="i2">characters of, in ducks, i. 283-284.</p> + <p><span class="sc">Rice</span>, Imperial, of China, ii. <a href="#page205">205</a>;</p> + <p class="i2">Indian varieties of, ii. <a href="#page256">256</a>;</p> + <p class="i2">variety of, not requiring water, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Richardson</span>, H. D., on jaw-appendages in Irish pigs, i. 76;</p> + <p class="i2">management of pigs in China, i. 68;</p> + <p class="i2">occurrence of striped young in Westphalian pigs, i. 76;</p> + <p class="i2">on crossing pigs, ii. <a href="#page95">95</a>;</p> + <p class="i2">on interbreeding pigs, ii. <a href="#page122">122</a>;</p> + <p class="i2">on selection in pigs, ii. <a href="#page194">194</a>.</p> + <p><span class="sc">Richardson</span>, Sir John, observations on the resemblance between North American dogs and wolves, i. 21-22;</p> + <p class="i2">on the burrowing of wolves, i. 27;</p> + <p class="i2">on the broad feet of dogs, wolves, and foxes in North America, i. 40;</p> + <p class="i2">on North American horses scraping away the snow, i. 53.</p> + <p><i>Ricinus</i>, annual in England, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Riedel</span>, on the "Bagadotte" pigeon, i. 141;</p> + <p class="i2">on the Jacobin pigeon, i. 154;</p> + <p class="i2">fertility of hybrid pigeons, i. 192.</p> + <p><span class="sc">Rinderpest</span>, ii. <a href="#page378">378</a>.</p> + <p><span class="sc">Risso</span>, on varieties of the orange, i. 336, ii. <a href="#page308">308</a>, <a href="#page331">331</a>.</p> + <p><span class="sc">Rivers</span>, Lord, on the selection of greyhounds, ii. <a href="#page235">235</a>.</p> + <p><span class="sc">Rivers</span>, Mr., persistency of characters in seedling potatoes, i. 331;</p> + <p class="i2">on the peach, i. 338, 339;</p> + <p class="i2">persistency of races in the peach and nectarine, i. 339, 340;</p> + <p class="i2">connexion between the peach and the nectarine, i. 340;</p> + <p class="i2">persistency of character in seedling apricots, i. 344;</p> + <p class="i2">origin of the plum, i. 345;</p> + <p class="i2">seedling varieties of the plum, i. 346;</p> + <p class="i2">persistency of character in seedling plums, i. 347;</p> + <p class="i2">bud-variation in the plum, i. 375;</p> + <p class="i2">plum, attacked by bullfinches, ii. <a href="#page232">232</a>;</p> + <p class="i2">seedling apples with surface-roots, i. 349;</p> + <p class="i2">variety of the apple found in a wood, ii. <a href="#page260">260</a>;</p> + <p class="i2">on roses, i. 366-367;</p> + <p class="i2">bud-variation in roses, i. 379-381;</p> + <p class="i2">production of Provence roses from seeds of the moss-rose, i. 380;</p> + <p class="i2">effect produced by grafting on the stock in jessamine, i. 394;</p> + <p class="i2">in the ash, i. 394;</p> + <p class="i2">on grafted hazels, i. 395;</p> + <p class="i2">hybridisation of a weeping thorn, ii. <a href="#page18">18</a>;</p> + <p class="i2">experiments with the seed of the weeping elm and ash, ii. <a href="#page19">19</a>;</p> + <p class="i2">variety of the cherry with curled petals, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Rivière</span>, reproduction of <i>Oncidium Cavendishianum</i>, ii. <a href="#page133">133</a>.</p> + <p><span class="sc">Roberts</span>, Mr., on inheritance in the horse, ii. <a href="#page10">10</a>.</p> + <p><span class="sc">Robertson</span>, Mr., on glandular-leaved peaches, i. 343.</p> + <p><span class="sc">Robinet</span>, on the silkworm, i. 301-304, ii. <a href="#page197">197</a>.</p> + <p><i>Robinia</i>, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Robson</span>, Mr., deficiencies of half-bred horses, ii. <a href="#page11">11</a>.</p> + <p><span class="sc">Robson</span>, Mr., on the advantage of change of soil to plants, ii. <a href="#page146">146</a>-<a href="#page147">147</a>;</p> + <p class="i2">on the growth of the verbena, ii. <a href="#page273">273</a>;</p> + <p class="i2">on broccoli, ii. <a href="#page310">310</a>.</p> + <p><span class="sc">Rock</span> pigeon, measurements of the, i. 134;</p> + <p class="i2">figured, i. 135.</p> + <p><span class="sc">Rodents</span>, sterility of, in captivity, ii. <a href="#page152">152</a>.</p> + <p><i>Rodriguezia</i>, ii. <a href="#page134">134</a>, <a href="#page135">135</a>.</p> + <p><span class="sc">Rodwell</span>, J., poisoning of horses by mildewed tares, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Rohilcund</span>, feral humped cattle in, i. 79.</p> + <p><span class="sc">Rolle</span>, F., on the history of the peach, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Roller-pigeons</span>, Dutch, i. 151.</p> + <p><span class="sc">Rolleston</span>, Prof., incisor teeth affected in form in cases of pulmonary tubercle, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Romans</span>, estimation of pigeons by, i. 205;</p> + <p class="i2">breeds of fowls possessed by, i. 231, 247.</p> +<!-- Page 475 --><span class="pagenum"><a name="page475"></a>{475}</span> + <p><span class="sc">Rooks</span>, pied, ii. <a href="#page77">77</a>.</p> + <p><i>Rosa</i>, cultivated species of, i. 366.</p> + <p><i>Rosa devoniensis</i>, graft-hybrid produced by, on the white Banksian rose, i. 396.</p> + <p><i>Rosa indica</i> and <i>centifolia</i>, fertile hybrids of, i. 366.</p> + <p><i>Rosa spinosissima</i>, history of the culture of, i. 367.</p> + <p><span class="sc">Rosellini</span>, on Egyptian dogs, i. 17.</p> + <p><span class="sc">Roses</span>, i. 366-367;</p> + <p class="i2">origin of, i. 364;</p> + <p class="i2">bud-variation in, i. 379-381;</p> + <p class="i2">Scotch, doubled by selection, ii. <a href="#page200">200</a>;</p> + <p class="i2">continuous variation of, ii. <a href="#page241">241</a>;</p> + <p class="i2">effect of seasonal conditions on, ii. <a href="#page273">273</a>;</p> + <p class="i2">noisette, ii. <a href="#page308">308</a>;</p> + <p class="i2">galls of, ii. <a href="#page284">284</a>.</p> + <p><span class="sc">Rouennais</span> rabbit, i. 105.</p> + <p><span class="sc">Roulin</span>, on the dogs of Juan Fernandez, i. 27;</p> + <p class="i2">on South American cats, i. 46;</p> + <p class="i2">striped young pigs, i. 77;</p> + <p class="i2">feral pigs in South America, i. 78, ii. <a href="#page33">33</a>;</p> + <p class="i2">on Columbian cattle, i. 88, ii. <a href="#page205">205</a>, <a href="#page226">226</a>;</p> + <p class="i2">effects of heat on the hides of cattle in South America, i. 92;</p> + <p class="i2">fleece of sheep in the hot valleys of the Cordilleras, i. 98;</p> + <p class="i2">diminished fertility of these sheep, ii. <a href="#page161">161</a>;</p> + <p class="i2">on black-boned South American fowls, i. 258;</p> + <p class="i2">variation of the guinea-fowl in tropical America, i. 294;</p> + <p class="i2">frequency of striped legs in mules, ii. <a href="#page42">42</a>;</p> + <p class="i2">geese in Bogota, ii. <a href="#page161">161</a>;</p> + <p class="i2">sterility of fowls introduced into Bolivia, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Roy</span>, M., on a variety of <i>Magnolia grandiflora</i>, ii. <a href="#page308">308</a>.</p> + <p><span class="sc">Royle</span>, Dr., Indian varieties of the mulberry, i. 334;</p> + <p class="i2">on <i>Agave vivipara</i>, ii. <a href="#page169">169</a>;</p> + <p class="i2">variety of rice not requiring irrigation, ii. <a href="#page305">305</a>;</p> + <p class="i2">sheep from the Cape in India, ii. <a href="#page306">306</a>.</p> + <p><i>Rubus</i>, pollen of, ii. <a href="#page268">268</a>.</p> + <p><span class="sc">Rudimentary</span> organs, i. 12, ii. <a href="#page315">315</a>-<a href="#page318">318</a>.</p> + <p><span class="sc">Rufz</span> de Lavison, extinction of breeds of dogs in France, ii. <a href="#page425">425</a>.</p> + <p><span class="sc">Ruminants</span>, general fertility of, in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Rumpless</span> fowls, i. 230.</p> + <p><span class="sc">Runts</span>, i. 142-144;</p> + <p class="i2">history of, i. 210;</p> + <p class="i2">lower jaws and skull figured, i. 164-165.</p> + <p><span class="sc">Russian</span> or Himalayan rabbit, i. 108.</p> + <p><span class="sc">Rütimeyer</span>, Prof., dogs of the Neolithic period, i. 19;</p> + <p class="i2">horses of Swiss lake-dwellings, i. 49;</p> + <p class="i2">diversity of early domesticated horses i. 51;</p> + <p class="i2">pigs of the Swiss lake-dwellings, i. 65, 67-68;</p> + <p class="i2">on humped cattle, i. 80;</p> + <p class="i2">parentage of European breeds of cattle, i. 80, 81, ii. <a href="#page427">427</a>;</p> + <p class="i2">on "Niata" cattle, i. 89;</p> + <p class="i2">sheep of the Swiss lake-dwellings, i. 94, ii. <a href="#page427">427</a>;</p> + <p class="i2">goats of the Swiss lake-dwellings, i. 101;</p> + <p class="i2">absence of fowls in the Swiss lake-dwellings, i. 246;</p> + <p class="i2">on crossing cattle, ii. <a href="#page98">98</a>;</p> + <p class="i2">differences in the bones of wild and domesticated animals, ii. <a href="#page279">279</a>;</p> + <p class="i2">decrease in size of wild European animals, ii. <a href="#page427">427</a>.</p> + <p><span class="sc">Rye</span>, wild, De Candolle's observations on, i. 313;</p> + <p class="i2">found in the Swiss lake-dwellings, i. 319;</p> + <p class="i2">common, preferred by hares and rabbits, ii. <a href="#page232">232</a>;</p> + <p class="i2">less variable than other cultivated plants, ii. <a href="#page254">254</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Sabine</span>, Mr., on the cultivation of <i>Rosa spinosissima</i>, i. 367;</p> + <p class="i2">on the cultivation of the dahlia, i. 369-370, ii. <a href="#page261">261</a>;</p> + <p class="i2">effect of foreign pollen on the seed-vessel in <i>Amaryllis vittata</i>, i. 400.</p> + <p><span class="sc">St. Ange</span>, influence of the pelvis on the shape of the kidneys in birds, ii. <a href="#page344">344</a>.</p> + <p><span class="sc">St. Domingo</span>, wild dogs of, i. 28;</p> + <p class="i2">bud-variation of dahlias in, i. 385.</p> + <p><span class="sc">St. Hilaire</span>, Aug., milk furnished by cows in South America, ii. <a href="#page300">300</a>;</p> + <p class="i2">husked form of maize, i. 320.</p> + <p><span class="sc">St. John</span>, C., feral cats in Scotland, i. 47;</p> + <p class="i2">taming of wild ducks, i. 278.</p> + <p><span class="sc">St. Valery</span> apple, singular structure of the, i. 350;</p> + <p class="i2">artificial fecundation of the, i. 401.</p> + <p><span class="sc">St. Vitus'</span> Dance, period of appearance of, ii. <a href="#page77">77</a>.</p> + <p><span class="sc">Sageret</span>, origin and varieties of the cherry, i. 347-348;</p> + <p class="i2">origin of varieties of the apple, i. 350;</p> + <p class="i2">incapacity of the cucumber for crossing with other species, i. 359;</p> + <p class="i2">varieties of the melon, i. 360;</p> + <p class="i2">supposed twin-mongrel melon, i. 391;</p> + <p class="i2">crossing melons, ii. <a href="#page108">108</a>, <a href="#page129">129</a>;</p> + <p class="i2">on gourds, ii. <a href="#page108">108</a>;</p> + <p class="i2">effects of selection in enlarging fruit, ii. <a href="#page217">217</a>;</p> + <p class="i2">on the tendency to depart from type, ii. <a href="#page241">241</a>;</p> + <p class="i2">variation of plants in particular soils, ii. <a href="#page278">278</a>.</p> + <p><span class="sc">Salamander</span>, experiments on the, ii. <a href="#page293">293</a>, <a href="#page341">341</a>;</p> + <p class="i2">regeneration of lost parts in the, ii. <a href="#page15">15</a>, <a href="#page376">376</a>, <a href="#page385">385</a>.</p> + <p><i>Salamandra cristata</i>, polydactylism in, ii. <a href="#page14">14</a>.</p> + <p><span class="sc">Salisbury</span>, Mr., on the production of nectarines by peach-trees, i. 341;</p> + <p class="i2">on the dahlia, i. 369-370.</p> + <p><i>Salix</i>, intercrossing of species of, i. 336.</p> + <p><i>Salix humilis</i>, galls of, ii. <a href="#page282">282</a>, <a href="#page283">283</a>.</p> + <p><span class="sc">Sallé</span>, feral guinea-fowl in St. Domingo, i. 294.</p> + <p><span class="sc">Salmon</span>, early breeding of male, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Salter</span>, Mr., on bud-variation in pelargoniums, i. 378;</p> + <p class="i2">in the Chrysanthemum, i. 379;</p> + <p class="i2">transmission of variegated leaves by seed, i. 383;</p> + <p class="i2">bud-variation by suckers in <i>Phlox</i>, i. 384;</p> + <p class="i2">application of selection to bud-varieties of plants, i. 411;</p> + <p class="i2">accumulative effect of changed conditions of life, ii. <a href="#page262">262</a>;</p> + <p class="i2">on the variegation of strawberry leaves, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Salter</span>, S. J., hybrids of <i>Gallus Sonneratii</i> and the common fowl, i. 234, ii. <a href="#page45">45</a>;</p> +<!-- Page 476 --><span class="pagenum"><a name="page476"></a>{476}</span> + <p class="i2">crossing of races or species of rats, ii. <a href="#page87">87</a>-<a href="#page88">88</a>.</p> + <p><span class="sc">Samesreuther</span>, on inheritance in cattle, ii. <a href="#page10">10</a>.</p> + <p><span class="sc">Sandford</span>. <i>See</i> <span class="sc">Dawkins</span>.</p> + <p><span class="sc">Sap</span>, ascent of the, ii. <a href="#page296">296</a>.</p> + <p><i>Saponaria calabrica</i>, ii. <a href="#page20">20</a>.</p> + <p><span class="sc">Sardinia</span>, ponies of, i. 52.</p> + <p><span class="sc">Sars</span>, on the development of the hydroida, ii. <a href="#page368">368</a>.</p> + <p><span class="sc">Satiation</span> of the stigma, i. 402-403.</p> + <p><i>Saturnia pyri</i>, sterility of, in confinement, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Saul</span>, on the management of prize gooseberries, i. 356.</p> + <p><span class="sc">Sauvigny</span>, varieties of the goldfish, i. 296.</p> + <p><span class="sc">Savages</span>, their indiscriminate use of plants as food, i. 307-310;</p> + <p class="i2">fondness of, for taming animals, ii. <a href="#page160">160</a>.</p> + <p><span class="sc">Savi</span>, effect of foreign pollen on maize, i. 400.</p> + <p><i>Saxifraga geum</i>, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Sayzid Mohammed Musari</span>, on carrier-pigeons, i. 141;</p> + <p class="i2">on a pigeon which utters the sound "Yahu," i. 155.</p> + <p><span class="sc">Scanderoons</span> (pigeons), i. 142, 143.</p> + <p><span class="sc">Scania</span>, remains of <i>Bos frontosus</i> found in, i. 81.</p> + <p><span class="sc">Scapula</span>, characters of, in rabbits, i. 123;</p> + <p class="i2">in fowls, i. 268;</p> + <p class="i2">in pigeons, i. 167;</p> + <p class="i2">alteration of, by disuse, in pigeons, i. 175.</p> + <p><span class="sc">Scarlet</span> fever, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Schaaffhausen</span>, on the horses represented in Greek statues, ii. <a href="#page213">213</a>.</p> + <p><span class="sc">Schacht</span>, H., on adventitious buds, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Schleiden</span>, excess of nourishment a cause of variability, ii. <a href="#page257">257</a>.</p> + <p><span class="sc">Schomburgk</span>, Sir R., on the dogs of the Indians of Guiana, i. 19, 23, ii. <a href="#page206">206</a>;</p> + <p class="i2">on the musk duck, i. 182;</p> + <p class="i2">bud-variation in the Banana, i. 377;</p> + <p class="i2">reversion of varieties of the China rose in St. Domingo, i. 380;</p> + <p class="i2">sterility of tame parrots in Guiana, ii. <a href="#page155">155</a>;</p> + <p class="i2">on <i>Dendrocygna viduata</i>, ii. <a href="#page157">157</a>;</p> + <p class="i2">selection of fowls in Guiana, ii. <a href="#page209">209</a>.</p> + <p><span class="sc">Schreibers</span>, on <i>Proteus</i>, ii. <a href="#page297">297</a>.</p> + <p><i>Sciuropterus volucella</i>, ii. <a href="#page152">152</a>.</p> + <p><i>Sciurus palmarum</i> and <i>cinerea</i>, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Sclater</span>, P. L., on <i>Asinus tæniopus</i>, i. 62, ii. <a href="#page41">41</a>;</p> + <p class="i2">on <i>Asinus indicus</i>, ii. <a href="#page42">42</a>;</p> + <p class="i2">striped character of young wild pigs, i. 70;</p> + <p class="i2">osteology of <i>Gallinula nesiotis</i>, i. 287;</p> + <p class="i2">on the black-shouldered peacock, i. 290;</p> + <p class="i2">on the breeding of birds in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Schmerling</span>, Dr., varieties of the dog, found in a cave, i. 19.</p> + <p><span class="sc">Scotch</span> fir, local variation of, i. 363.</p> + <p><span class="sc">Scotch</span> kail and cabbage, cross between, ii. <a href="#page98">98</a>.</p> + <p><span class="sc">Scott</span>, John, irregularities in the sex of the flowers of Maize, i. 321;</p> + <p class="i2">bud-variation in <i>Imatophyllum miniatum</i>, i. 385;</p> + <p class="i2">crossing of species of <i>Verbascum</i>, ii. <a href="#page106">106</a>-<a href="#page107">107</a>;</p> + <p class="i2">experiments on crossing <i>Primulæ</i>, ii. <a href="#page109">109</a>;</p> + <p class="i2">reproduction of orchids, ii. <a href="#page133">133</a>;</p> + <p class="i2">fertility of <i>Oncidium divaricatum</i>, ii. <a href="#page164">164</a>;</p> + <p class="i2">acclimatisation of the sweet pea in India, ii. <a href="#page311">311</a>;</p> + <p class="i2">number of seeds in <i>Acropera</i> and <i>Gongora</i>, ii. <a href="#page379">379</a>.</p> + <p><span class="sc">Scott</span>, Sir W., former range of wild cattle in Britain, i. 85.</p> + <p><span class="sc">Scrope</span>, on the Scotch deerhound, ii. <a href="#page73">73</a>, <a href="#page121">121</a>.</p> + <p><span class="sc">Sebright</span>, Sir John, effects of close interbreeding in dogs, ii. <a href="#page121">121</a>;</p> + <p class="i2">care taken by, in selection of fowls, ii. <a href="#page197">197</a>.</p> + <p><i>Secale cereale</i>, ii. <a href="#page254">254</a>.</p> + <p><span class="sc">Sedgwick, W.</span>, effects of crossing on the female, i. 404;</p> + <p class="i2">on the "Porcupine-man," ii. <a href="#page4">4</a>;</p> + <p class="i2">on hereditary diseases, ii. <a href="#page7">7</a>;</p> + <p class="i2">hereditary affections of the eye, ii. <a href="#page9">9</a>, <a href="#page78">78</a>-<a href="#page79">79</a>;</p> + <p class="i2">inheritance of polydactylism and anomalies of the extremities, ii. <a href="#page13">13</a>-<a href="#page14">14</a>;</p> + <p class="i2">morbid uniformity in the same family, ii. <a href="#page17">17</a>;</p> + <p class="i2">on deaf-mutes, ii. <a href="#page22">22</a>;</p> + <p class="i2">inheritance of injury to the eye, ii. <a href="#page24">24</a>;</p> + <p class="i2">atavism in diseases and anomalies of structure, ii. <a href="#page34">34</a>;</p> + <p class="i2">non-reversion to night-blindness, ii. <a href="#page36">36</a>;</p> + <p class="i2">sexual limitation of the transmission of peculiarities in man, ii. <a href="#page72">72</a>-<a href="#page73">73</a>;</p> + <p class="i2">on the effects of hard-drinking, ii. <a href="#page289">289</a>;</p> + <p class="i2">inherited baldness with deficiency of teeth, ii. <a href="#page326">326</a>-<a href="#page327">327</a>;</p> + <p class="i2">occurrence of a molar tooth in place of an incisor, ii. <a href="#page391">391</a>;</p> + <p class="i2">diseases occurring in alternate generations, ii. <a href="#page401">401</a>.</p> + <p><span class="sc">Sedillot</span>, on the removal of portions of bone, ii. <a href="#page296">296</a>.</p> + <p><span class="sc">Seeds</span>, early selection of, ii. <a href="#page204">204</a>;</p> + <p class="i2">rudimentary, in grapes, ii. <a href="#page316">316</a>;</p> + <p class="i2">relative position of, in the capsule, ii. <a href="#page345">345</a>.</p> + <p><span class="sc">Seeds</span> and buds, close analogies of, i. 411.</p> + <p><span class="sc">Seemann, B.</span>, crossing of the wolf and Esquimaux dog, i. 22.</p> + <p><span class="sc">Selby, P. J.</span>, on the bud-destroying habits of the bullfinch, ii. <a href="#page232">232</a>.</p> + <p><span class="sc">Selection</span>, ii. <a href="#page192">192</a>-<a href="#page249">249</a>;</p> + <p class="i2">methodical, i. 214, ii. <a href="#page194">194</a>-<a href="#page210">210</a>;</p> + <p class="i2">by the ancients and semi-civilised people, ii. <a href="#page201">201</a>-<a href="#page210">210</a>;</p> + <p class="i2">of trifling characters, ii. <a href="#page208">208</a>-<a href="#page210">210</a>;</p> + <p class="i2">unconscious, i. 214, 217, ii. <a href="#page174">174</a>, <a href="#page210">210</a>-<a href="#page217">217</a>;</p> + <p class="i2">effects of, shown by differences in most valued parts, ii. <a href="#page217">217</a>-<a href="#page220">220</a>;</p> + <p class="i2">produced by accumulation of variability, ii. <a href="#page220">220</a>-<a href="#page223">223</a>;</p> + <p class="i2">natural, as affecting domestic productions, ii. <a href="#page185">185</a>-<a href="#page189">189</a>, <a href="#page224">224</a>-<a href="#page233">233</a>;</p> + <p class="i2">as the origin of species, genera and other groups, ii. <a href="#page429">429</a>-<a href="#page432">432</a>;</p> + <p class="i2">circumstances favourable to, ii. <a href="#page233">233</a>-<a href="#page239">239</a>;</p> + <p class="i2">tendency of towards extremes, ii. <a href="#page239">239</a>-<a href="#page242">242</a>;</p> +<!-- Page 477 --><span class="pagenum"><a name="page477"></a>{477}</span> + <p class="i2">possible limit of, ii. <a href="#page242">242</a>;</p> + <p class="i2">influence of time on, ii. <a href="#page243">243</a>-<a href="#page244">244</a>;</p> + <p class="i2">summary of subject, ii. <a href="#page246">246</a>-<a href="#page249">249</a>;</p> + <p class="i2">effects of, in modifying breeds of cattle, i. 92, 93;</p> + <p class="i2">in preserving the purity of breeds of sheep, i. 99-100;</p> + <p class="i2">in producing varieties of pigeons, i. 213-218;</p> + <p class="i2">in breeding fowls, i. 232-233;</p> + <p class="i2">in the goose, i. 289;</p> + <p class="i2">in the canary, i. 295;</p> + <p class="i2">in the goldfish, i. 296;</p> + <p class="i2">in the silkworm, i. 300-301;</p> + <p class="i2">contrasted in cabbages and cereals, i. 323;</p> + <p class="i2">in the white mulberry, i. 334;</p> + <p class="i2">on gooseberries, i. 356;</p> + <p class="i2">applied to wheat, i. 317-318;</p> + <p class="i2">exemplified in carrots, &c., i. 326;</p> + <p class="i2">in the potato, i. 331;</p> + <p class="i2">in the melon, i. 360;</p> + <p class="i2">in flowering plants, i. 365;</p> + <p class="i2">in the hyacinth, i. 371;</p> + <p class="i2">applied to bud-varieties of plants, i. 411;</p> + <p class="i2">illustrations of, ii. <a href="#page421">421</a>-<a href="#page428">428</a>.</p> + <p><span class="sc">Selection</span>, sexual, ii. <a href="#page75">75</a>.</p> + <p><span class="sc">Self-impotence</span> in plants, ii. <a href="#page131">131</a>-<a href="#page140">140</a>;</p> + <p class="i2">in individual plants, ii. <a href="#page136">136</a>-<a href="#page138">138</a>;</p> + <p class="i2">of hybrids, ii. <a href="#page174">174</a>.</p> + <p><span class="sc">Selwyn</span>, Mr., on the Dingo, i. 26.</p> + <p><span class="sc">Selys-Longchamps</span>, on hybrid ducks, i. 190, ii. <a href="#page46">46</a>, <a href="#page157">157</a>;</p> + <p class="i2">hybrid of the hook-billed duck and Egyptian goose, i. 282.</p> + <p><span class="sc">Seringe</span>, on the St. Valery apple, i. 350.</p> + <p><span class="sc">Serpent</span> Melon, i. 360.</p> + <p><span class="sc">Serres</span>, Olivier de, wild poultry in Guiana, i. 237.</p> + <p><span class="sc">Sesamum</span>, white-seeded, antiquity of the, ii. <a href="#page429">429</a>.</p> + <p><i>Setaria</i>, found in the Swiss lake-dwellings, i. 317.</p> + <p><span class="sc">Setters</span>, degeneration of, in India, i. 38;</p> + <p class="i2">Youatt's remarks on, i. 41.</p> + <p><span class="sc">Sex</span>, secondary characters of, latent, ii. <a href="#page51">51</a>-<a href="#page52">52</a>;</p> + <p class="i2">of parents, influence of, on hybrids, ii. <a href="#page267">267</a>.</p> + <p><span class="sc">Sexual</span> characters, sometimes lost in domestication, ii. <a href="#page74">74</a>.</p> + <p><span class="sc">Sexual</span> limitation of characters, ii. <a href="#page71">71</a>-<a href="#page75">75</a>.</p> + <p><span class="sc">Sexual</span> peculiarities, induced by domestication in sheep, i. 95;</p> + <p class="i2">in fowls, i. 251-257;</p> + <p class="i2">transfer of, i. 255-257.</p> + <p><span class="sc">Sexual</span> variability in pigeons, i. 161-162.</p> + <p><span class="sc">Sexual</span> selection, ii. <a href="#page75">75</a>.</p> + <p><span class="sc">Shaddock</span>, i. 335.</p> + <p><span class="sc">Shailer</span>, Mr., on the moss-rose, i. 379-380.</p> + <p><span class="sc">Shanghai</span> fowls, i. 227.</p> + <p><span class="sc">Shanghai</span> sheep, their fecundity, i. 97.</p> + <p><span class="sc">Shan</span> ponies, striped, i. 58.</p> + <p><span class="sc">Sheep</span>, disputed origin of, i. 94;</p> + <p class="i2">early domestication of, i. 94;</p> + <p class="i2">large-tailed, i. 94, 95, 98, ii. <a href="#page279">279</a>;</p> + <p class="i2">variations in horns, mammæ and other characters of, i. 95;</p> + <p class="i2">sexual characters of, induced by domestication, i. 95, 96;</p> + <p class="i2">adaptation of, to climate and pasture, i. 96, 97;</p> + <p class="i2">periods of gestation of, i. 97;</p> + <p class="i2">effect of heat on the fleece of, i. 98-99, ii. <a href="#page278">278</a>;</p> + <p class="i2">effect of selection on, i. 99-101;</p> + <p class="i2">"ancon" or "otter" breeds of, i. 17, 92, 100;</p> + <p class="i2">"Mauchamp-merino," i. 100-101;</p> + <p class="i2">cross of German and merino, ii. <a href="#page85">85</a>-<a href="#page89">89</a>;</p> + <p class="i2">black, of the Tarentino, ii. <a href="#page227">227</a>;</p> + <p class="i2">Karakool, ii. <a href="#page278">278</a>;</p> + <p class="i2">Jaffna, with callosities on the knees, ii. <a href="#page302">302</a>;</p> + <p class="i2">Chinese, ii. <a href="#page315">315</a>;</p> + <p class="i2">Danish, of the bronze period, ii. <a href="#page427">427</a>;</p> + <p class="i2">polydactylism in, ii. <a href="#page14">14</a>;</p> + <p class="i2">occasional production of horns in hornless breeds of, ii. <a href="#page30">30</a>;</p> + <p class="i2">reversion of colour in, ii. <a href="#page30">30</a>;</p> + <p class="i2">influence of male, on offspring, ii. <a href="#page68">68</a>;</p> + <p class="i2">sexual differences in, ii. <a href="#page73">73</a>;</p> + <p class="i2">influence of crossing or segregation on, ii. <a href="#page86">86</a>, <a href="#page95">95</a>-<a href="#page96">96</a>, <a href="#page102">102</a>-<a href="#page103">103</a>;</p> + <p class="i2">interbreeding of, ii. <a href="#page119">119</a>-<a href="#page120">120</a>;</p> + <p class="i2">effect of nourishment on the fertility of, ii. <a href="#page111">111</a>-<a href="#page112">112</a>;</p> + <p class="i2">diminished fertility of, under certain conditions, ii. <a href="#page161">161</a>;</p> + <p class="i2">unconscious selection of, ii. <a href="#page213">213</a>;</p> + <p class="i2">natural selection in breeds of, ii. <a href="#page224">224</a>, <a href="#page225">225</a>, <a href="#page227">227</a>;</p> + <p class="i2">reduction of bones in, ii. <a href="#page242">242</a>;</p> + <p class="i2">individual differences of, ii. <a href="#page251">251</a>;</p> + <p class="i2">local changes in the fleece of, in England, ii. <a href="#page278">278</a>;</p> + <p class="i2">partial degeneration of, in Australia, ii. <a href="#page278">278</a>;</p> + <p class="i2">with numerous horns, ii. <a href="#page291">291</a>;</p> + <p class="i2">correlation of horns and fleece in, ii. <a href="#page326">326</a>;</p> + <p class="i2">feeding on flesh, ii. <a href="#page303">303</a>;</p> + <p class="i2">acclimatisation of, ii. <a href="#page305">305</a>-<a href="#page306">306</a>;</p> + <p class="i2">mountain, resistance of, to severe weather, ii. <a href="#page312">312</a>;</p> + <p class="i2">white, poisoned by <i>Hypericum crispum</i>, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Sheep</span> dogs resembling wolves, i. 24.</p> + <p><span class="sc">Shells</span>, sinistral and dextral, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Sheriff</span>, Mr. new varieties of wheat, i. 315, 317;</p> + <p class="i2">on crossing wheat, ii. <a href="#page104">104</a>-<a href="#page105">105</a>;</p> + <p class="i2">continuous variation of wheat, ii. <a href="#page241">241</a>.</p> + <p><span class="sc">Siam</span>, cats of, i. 47; horses of, i. 53.</p> + <p><span class="sc">Shirley</span>, E. P., on the fallow-deer, ii. <a href="#page103">103</a>, <a href="#page120">120</a>.</p> + <p><span class="sc">Short</span>, D., hybrids of the domestic cat and <i>Felis ornata</i>, i, 45.</p> + <p><span class="sc">Siberia</span>, northern range of wild horses in, i. 52.</p> + <p><span class="sc">Sichel</span>, J., on the deafness of white cats with blue eyes, ii. <a href="#page329">329</a>.</p> + <p><span class="sc">Sidney</span>, S., on the pedigrees of pigs, ii. <a href="#page3">3</a>;</p> + <p class="i2">on cross-reversion in pigs, ii. <a href="#page35">35</a>;</p> + <p class="i2">period of gestation in the pig, i. 74;</p> + <p class="i2">production of breeds of pigs by intercrossing, i. 78, 95;</p> + <p class="i2">fertility of the pig, ii. <a href="#page112">112</a>;</p> + <p class="i2">effects of interbreeding on pigs, ii. <a href="#page121">121</a>-<a href="#page122">122</a>;</p> + <p class="i2">on the colours of pigs, ii. <a href="#page210">210</a>, <a href="#page229">229</a>.</p> + <p><span class="sc">Siebold</span>, on the sweet potato, ii. <a href="#page309">309</a>.</p> + <p><span class="sc">Siebold</span>, von Carl, on parthenogenesis, ii. <a href="#page364">364</a>.</p> + <p><i>Silene</i>, contabescence in, ii. <a href="#page166">166</a>.</p> + <p><span class="sc">Silk-fowls</span>, i. 230, ii. <a href="#page67">67</a>, <a href="#page69">69</a>.</p> +<!-- Page 478 --><span class="pagenum"><a name="page478"></a>{478}</span> + <p><span class="sc">Silk-moth</span>, Arrindy, ii. <a href="#page306">306</a>, <a href="#page312">312</a>;</p> + <p class="i2">Tarroo, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Silk-moths</span>, i. 300-304;</p> + <p class="i2">domesticated species of, i. 300;</p> + <p class="i2">history of, <i>ibid.</i>;</p> + <p class="i2">causes of modification in, i. 300-301;</p> + <p class="i2">differences presented by, i. 301-304;</p> + <p class="i2">crossing of, ii. <a href="#page98">98</a>;</p> + <p class="i2">disease in, ii. <a href="#page228">228</a>;</p> + <p class="i2">effects of disuse of parts in, ii. <a href="#page298">298</a>;</p> + <p class="i2">selection practised with, ii. <a href="#page197">197</a>, <a href="#page199">199</a>;</p> + <p class="i2">variation of, ii. <a href="#page236">236</a>;</p> + <p class="i2">parthenogenesis in, ii. <a href="#page364">364</a>.</p> + <p><span class="sc">Silkworms</span>, variations of, i. 301-302;</p> + <p class="i2">yielding white cocoons, less liable to disease, ii. <a href="#page336">336</a>.</p> + <p><span class="sc">Silver-Grey</span> rabbit, i. 108, 111, 120.</p> + <p><span class="sc">Simonds</span>, J. B., period of maturity in various breeds of cattle, i. 87;</p> + <p class="i2">differences in the periods of dentition in sheep, i. 96;</p> + <p class="i2">on the teeth in cattle, sheep, &c., ii. <a href="#page322">322</a>;</p> + <p class="i2">on the breeding of superior rams, ii. <a href="#page196">196</a>.</p> + <p><span class="sc">Simon</span>, on the raising of eggs of the silk-moth in China, ii. <a href="#page197">197</a>.</p> + <p><span class="sc">Simpson</span>, Sir J., regenerative power of the human embryo, ii. <a href="#page15">15</a>.</p> + <p><i>Siredon</i>, breeding in the branchiferous stage, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Siskin</span>, breeding in captivity, ii. <a href="#page154">154</a>.</p> + <p><i>Sivatherium</i>, resemblance of the, to Niata cattle, i. 89.</p> + <p><span class="sc">Size</span>, difference of, an obstacle to crossing, ii. <a href="#page101">101</a>.</p> + <p><span class="sc">Skin</span>, and its appendages, homologous, ii. <a href="#page325">325</a>;</p> + <p class="i2">hereditary affections of the, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Skirving</span>, R. S., on pigeons settling on trees in Egypt, i. 181.</p> + <p><span class="sc">Skull</span>, characters of the, in breeds of dogs, i. 34;</p> + <p class="i2">in breeds of pigs, i. 71;</p> + <p class="i2">in rabbits, i. 116-120, 127;</p> + <p class="i2">in breeds of pigeons, i. 163-165;</p> + <p class="i2">in breeds of fowls, i. 260-266;</p> + <p class="i2">in ducks, i. 282-283.</p> + <p><span class="sc">Skull</span> and horns, correlation of the, ii. <a href="#page333">333</a>.</p> + <p><span class="sc">Skylark</span>, ii. <a href="#page154">154</a>.</p> + <p><span class="sc">Sleeman</span>, on the Cheetah, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Sloe</span>, i. 345.</p> + <p><span class="sc">Small-pox</span>, ii. <a href="#page378">378</a>.</p> + <p><span class="sc">Smiter</span> (pigeon), i. 156.</p> + <p><span class="sc">Smith</span>, Sir A., on Caffrarian cattle, i. 88;</p> + <p class="i2">on the use of numerous plants as food in South Africa, i. 307.</p> + <p><span class="sc">Smith</span>, Colonel Hamilton, on the odour of the jackal, i. 30;</p> + <p class="i2">on the origin of the dog, i. 16;</p> + <p class="i2">wild dogs in St. Domingo, i. 28;</p> + <p class="i2">on the Thibet mastiff and the alco, i. 28-29;</p> + <p class="i2">development of the fifth toe in the hind feet of mastiffs, i. 35;</p> + <p class="i2">differences in the skull of dogs, i. 34;</p> + <p class="i2">history of the pointer, i. 42;</p> + <p class="i2">on the ears of the dog, ii. <a href="#page301">301</a>;</p> + <p class="i2">on the breeds of horses, i. 49;</p> + <p class="i2">origin of the horse, i. 51;</p> + <p class="i2">dappling of horses, i. 55;</p> + <p class="i2">striped horses in Spain, i. 58;</p> + <p class="i2">original colour of the horse, i. 60;</p> + <p class="i2">on horses scraping away snow, i. 52;</p> + <p class="i2">on <i>Asinus hemionus</i>, ii. <a href="#page43">43</a>;</p> + <p class="i2">feral pigs of Jamaica, i. 77-78.</p> + <p><span class="sc">Smith</span>, Sir J. E., production of nectarines and peaches by the same tree, i. 340;</p> + <p class="i2">on <i>Viola amœna</i>, i. 368;</p> + <p class="i2">sterility of <i>Vinca minor</i> in England, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Smith</span>, J., development of the ovary in <i>Bonatea speciosa</i>, by irritation of the stigma, i. 403.</p> + <p><span class="sc">Smith</span>, N. H., influence of the bull "Favourite" on the breed of Short-horn cattle, ii. <a href="#page65">65</a>.</p> + <p><span class="sc">Smith</span>, W., on the inter-crossing of strawberries, i. 352.</p> + <p><span class="sc">Snake-rat</span>, ii. <a href="#page87">87</a>, <a href="#page88">88</a>.</p> + <p><span class="sc">Snakes</span>, form of the viscera in, ii. <a href="#page344">344</a>.</p> + <p><span class="sc">Snapdragon</span>, bud-variation in, i. 381;</p> + <p class="i2">non-inheritance of colour in, ii. <a href="#page21">21</a>;</p> + <p class="i2">peloric, crossed with the normal form, ii. <a href="#page70">70</a>, <a href="#page93">93</a>;</p> + <p class="i2">asymmetrical variation of the, ii. <a href="#page322">322</a>.</p> + <p><span class="sc">Soil</span>, adaptation of plums to, i. 346;</p> + <p class="i2">influence of, on the zones of pelargoniums, i. 366;</p> + <p class="i2">on roses, i. 367;</p> + <p class="i2">on the variegation of leaves, i. 383;</p> + <p class="i2">advantages of change of, ii. <a href="#page146">146</a>-<a href="#page148">148</a>.</p> + <p><span class="sc">Soil</span> and climate, effects of, on strawberries, i. 353.</p> + <p><i>Solanum</i>, non-intercrossing of species of, ii. <a href="#page91">91</a>.</p> + <p><i>Solanum tuberosum</i>, i. 330-331.</p> + <p><span class="sc">Solid-hoofed</span> pigs, i. 75.</p> + <p><span class="sc">Solomon</span>, his stud of horses, i. 55.</p> + <p><span class="sc">Somerville</span>, Lord, on the fleece of Merino sheep, i. 99;</p> + <p class="i2">on crossing sheep, ii. <a href="#page120">120</a>;</p> + <p class="i2">on selection of sheep, ii. <a href="#page195">195</a>;</p> + <p class="i2">diminished fertility of Merino sheep brought from Spain, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Sooty</span> fowls, i. 230, 256.</p> + <p><span class="sc">Soto</span>, Ferdinand de, on the cultivation of native plants in Florida, i. 312.</p> + <p><i>Sorghum</i>, i. 371.</p> + <p><span class="sc">Spain</span>, hawthorn monogynous in, i. 364.</p> + <p><span class="sc">Spallanzani</span>, on feral rabbits in Lipari, i. 113;</p> + <p class="i2">experiments on salamanders, ii. <a href="#page15">15</a>, <a href="#page293">293</a>, <a href="#page385">385</a>;</p> + <p class="i2">experiments in feeding a pigeon with meat, ii. <a href="#page304">304</a>.</p> + <p><span class="sc">Spaniels</span>, in India, i. 38;</p> + <p class="i2">King Charles's, i. 41;</p> + <p class="i2">degeneration of, caused by interbreeding, ii. <a href="#page121">121</a>.</p> + <p><span class="sc">Spanish</span> fowls, i. 227, 250, 253;</p> + <p class="i2">figured, i. 226;</p> + <p class="i2">early development of sexual characters in, i. 250, 251;</p> + <p class="i2">furcula of, figured, i. 268.</p> + <p><span class="sc">Species</span>, difficulty of distinguishing from varieties, i. 4;</p> + <p class="i2">conversion of varieties into, i. 5;</p> + <p class="i2">origin of, by natural selection, ii. <a href="#page414">414</a>-<a href="#page415">415</a>;</p> + <p class="i2">by mutual sterility of varieties, ii. <a href="#page185">185</a>-<a href="#page189">189</a>.</p> +<!-- Page 479 --><span class="pagenum"><a name="page479"></a>{479}</span> + <p><span class="sc">Spencer</span>, Lord, on selection in breeding, ii. <a href="#page195">195</a>.</p> + <p><span class="sc">Spencer</span>, Herbert, on the "survival of the fittest," i. 6;</p> + <p class="i2">increase of fertility by domestication, ii. <a href="#page111">111</a>;</p> + <p class="i2">on life, ii. <a href="#page148">148</a>, <a href="#page177">177</a>;</p> + <p class="i2">changes produced by external conditions, ii. <a href="#page281">281</a>;</p> + <p class="i2">effects of use on organs, ii. <a href="#page295">295</a>, <a href="#page296">296</a>;</p> + <p class="i2">ascent of the sap in trees, ii. <a href="#page296">296</a>;</p> + <p class="i2">correlation exemplified in the Irish elk, ii. <a href="#page333">333</a>-<a href="#page334">334</a>;</p> + <p class="i2">on "physiological units," ii. <a href="#page375">375</a>;</p> + <p class="i2">antagonism of growth and reproduction, ii. <a href="#page384">384</a>;</p> + <p class="i2">formation of ducts in plants, ii. <a href="#page300">300</a>.</p> + <p><span class="sc">Spermatophores</span> of the cephalopoda, ii. <a href="#page383">383</a>.</p> + <p><span class="sc">Spermatozoids</span>, ii. <a href="#page363">363</a>-<a href="#page364">364</a>;</p> + <p class="i2">apparent independence of, in insects, ii. <a href="#page384">384</a>.</p> + <p><span class="sc">Sphingidæ</span>, sterility of, in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Spinola</span>, on the injurious effect produced by flowering buckwheat on white pigs, ii. <a href="#page337">337</a>.</p> + <p><span class="sc">Spitz</span> dog, i. 31.</p> + <p><span class="sc">Spooner</span>, W. C., cross-breeding of sheep, i. 100, ii. <a href="#page95">95</a>-<a href="#page96">96</a>, <a href="#page120">120</a>;</p> + <p class="i2">on the effects of crossing, ii. <a href="#page96">96</a>-<a href="#page97">97</a>;</p> + <p class="i2">on crossing cattle, ii. <a href="#page118">118</a>;</p> + <p class="i2">individual sterility, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Spores</span>, reproduction of abnormal forms by, i. 383.</p> + <p><span class="sc">Sports</span>, i. 373; in pigeons, i. 213.</p> + <p><span class="sc">Spot</span> pigeon, i. 156, 207.</p> + <p><span class="sc">Sprengel</span>, C. K., on dichogamous plants, ii. <a href="#page90">90</a>;</p> + <p class="i2">on the hollyhock, ii. <a href="#page107">107</a>;</p> + <p class="i2">on the functions of flowers, ii. <a href="#page175">175</a>.</p> + <p><span class="sc">Sproule</span>, Mr., inheritance of cleft-palate and hare-lip, ii. <a href="#page24">24</a>.</p> + <p><span class="sc">Spurs</span>, of fowls, i. 255;</p> + <p class="i2">development of, in hens, ii. <a href="#page318">318</a>.</p> + <p><span class="sc">Squashes</span>, i. 357.</p> + <p><span class="sc">Squinting</span>, hereditary, ii. <a href="#page9">9</a>.</p> + <p><span class="sc">Squirrels</span>, generally sterile in captivity, ii. <a href="#page152">152</a>.</p> + <p><span class="sc">Squirrels</span>, flying, breeding in confinement, ii. <a href="#page152">152</a>.</p> + <p>"<span class="sc">Staarhalsige</span> Taube," i. 161.</p> + <p><span class="sc">Stag</span>, one-horned, supposed heredity of character in, ii. <a href="#page12">12</a>;</p> + <p class="i2">degeneracy of, in the Highlands, ii. <a href="#page208">208</a>.</p> + <p><span class="sc">Stamens</span>, occurrence of rudimentary, ii. <a href="#page316">316</a>;</p> + <p class="i2">conversion of, into pistils, i. 365;</p> + <p class="i2">into petals, ii. <a href="#page392">392</a>.</p> + <p><i>Staphylea</i>, ii. <a href="#page168">168</a>.</p> + <p><span class="sc">Steenstrup</span>, Prof., on the dog of the Danish Middens, i. 18;</p> + <p class="i2">on the obliquity of flounders, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Steinan</span>, J., on hereditary diseases, ii. <a href="#page7">7</a>, <a href="#page79">79</a>.</p> + <p><span class="sc">Sterility</span>, in dogs, consequent on close confinement, i. 32;</p> + <p class="i2">comparative, of crosses, ii. <a href="#page103">103</a>, <a href="#page104">104</a>;</p> + <p class="i2">from changed conditions of life, ii. <a href="#page148">148</a>-<a href="#page165">165</a>;</p> + <p class="i2">occurring in the descendants of wild animals bred in captivity, ii. <a href="#page160">160</a>;</p> + <p class="i2">individual, ii. <a href="#page162">162</a>;</p> + <p class="i2">resulting from propagation by buds, cuttings, bulbs, &c., ii. <a href="#page169">169</a>;</p> + <p class="i2">in hybrids, ii. <a href="#page178">178</a>-<a href="#page180">180</a>, <a href="#page386">386</a>, <a href="#page410">410</a>-<a href="#page411">411</a>;</p> + <p class="i2">in specific hybrids of pigeons, i. 193;</p> + <p class="i2">as connected with natural selection, ii. <a href="#page185">185</a>-<a href="#page189">189</a>.</p> + <p><span class="sc">Sternum</span>, characters of the, in rabbits, i. 123;</p> + <p class="i2">in pigeons, i. 167, 174-175;</p> + <p class="i2">in fowls, i. 268, 273;</p> + <p class="i2">effects of disuse on the, i. 174-175, 273.</p> + <p><span class="sc">Stephens</span>, J. F., on the habits of the Bombycidæ, i. 303.</p> + <p><span class="sc">Stewart</span>, H., on hereditary disease, ii. <a href="#page79">79</a>.</p> + <p><span class="sc">Stigma</span>, variation of the, in cultivated Cucurbitaceæ, i. 359;</p> + <p class="i2">satiation of the, i. 402-403.</p> + <p><span class="sc">Stocks</span>, bud-variation in, i. 381;</p> + <p class="i2">effect of crossing upon the colour of the seed of, i. 398-399;</p> + <p class="i2">true by seed, ii. <a href="#page20">20</a>;</p> + <p class="i2">crosses of, ii. <a href="#page93">93</a>;</p> + <p class="i2">varieties of, produced by selection, ii. <a href="#page219">219</a>;</p> + <p class="i2">reversion by the upper seeds in the pods of, ii. <a href="#page347">347</a>-<a href="#page348">348</a>.</p> + <p><span class="sc">Stockholm</span>, fruit-trees of, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Stokes</span>, Prof., calculation of the chance of transmission of abnormal peculiarities in man, ii. <a href="#page5">5</a>.</p> + <p><span class="sc">Stolons</span>, variations in the production of, by strawberries, i. 353.</p> + <p><span class="sc">Stomach</span>, structure of the, affected by food, ii. <a href="#page302">302</a>.</p> + <p><span class="sc">Stone</span> in the bladder, hereditary, ii. <a href="#page8">8</a>, <a href="#page79">79</a>.</p> + <p><span class="sc">Strawberries</span>, i. 351-354;</p> + <p class="i2">remarkable varieties of, i. 352-353;</p> + <p class="i2">hautbois, diœcious, i. 353;</p> + <p class="i2">selection in, ii. <a href="#page200">200</a>;</p> + <p class="i2">mildew of, ii. <a href="#page228">228</a>;</p> + <p class="i2">probable further modification of, ii. <a href="#page243">243</a>;</p> + <p class="i2">variegated, effects of soil on, ii. <a href="#page274">274</a>.</p> + <p><span class="sc">Strickland</span>, A., on the domestication of <i>Anser ferus</i>, i. 287;</p> + <p class="i2">on the colour of the bill and legs in geese, i. 288.</p> + <p><i>Strictœnas</i>, i. 183.</p> + <p><span class="sc">Stripes</span> on young of wild swine, i. 76;</p> + <p class="i2">of domestic pigs of Turkey, Westphalia, and the Zambesi, i. 76-77;</p> + <p class="i2">of feral swine of Jamaica and New Granada, i. 77;</p> + <p class="i2">of fruit and flowers, i. 400, ii. <a href="#page37">37</a>;</p> + <p class="i2">in horses, i. 56-60;</p> + <p class="i2">in the ass, i. 62-63;</p> + <p class="i2">production of, by crossing species of Equidæ, ii. <a href="#page42">42</a>-<a href="#page43">43</a>.</p> + <p><i>Strix grallaria</i>, ii. <a href="#page302">302</a>.</p> + <p><i>Strix passerina</i>, ii. <a href="#page154">154</a>.</p> + <p>"<span class="sc">Strupp-Taube</span>," i. 155.</p> + <p><span class="sc">Struthers</span>, Mr., osteology of the feet in solid-hoofed pigs, i. 75;</p> + <p class="i2">on polydactylism, ii. <a href="#page13">13</a>-<a href="#page14">14</a>.</p> + <p><span class="sc">Sturm</span>, prepotency of transmission of characters in sheep and cattle, ii. <a href="#page66">66</a>;</p> + <p class="i2">absorption of the minority in crossed races, ii. <a href="#page88">88</a>;</p> + <p class="i2">correlation of twisted horns and curled wool in sheep, ii. <a href="#page326">326</a>.</p> +<!-- Page 480 --><span class="pagenum"><a name="page480"></a>{480}</span> + <p><span class="sc">Sub-species</span>, wild, of <i>Columba livia</i> and other pigeons, i. 204.</p> + <p><span class="sc">Succession</span>, geological, of organisms, i. 11.</p> + <p><span class="sc">Suckers</span>, bud-variation by, i. 384.</p> + <p><span class="sc">Sugar</span> cane, sterility of, in various countries, ii. <a href="#page169">169</a>;</p> + <p class="i2">white, liability of, to disease, ii. <a href="#page228">228</a>, <a href="#page336">336</a>.</p> + <p><span class="sc">Suicide</span>, hereditary tendency to, ii. <a href="#page7">7</a>, <a href="#page78">78</a>.</p> + <p><span class="sc">Sulivan</span>, Admiral, on the horses of the Falkland Islands, i. 53;</p> + <p class="i2">wild pigs of the Falkland Islands, i. 77;</p> + <p class="i2">feral cattle of the Falkland Islands, i. 86, 102;</p> + <p class="i2">feral rabbits of the Falkland Islands, i. 112.</p> + <p><span class="sc">Sultan</span> fowl, i. 228, 255.</p> + <p><i>Sus indica</i>, i. 65, 67-70, ii. <a href="#page110">110</a>.</p> + <p><i>Sus pliciceps</i>, i. 69 (figured).</p> + <p><i>Sus scrofa</i>, i. 65, 66, ii. <a href="#page110">110</a>.</p> + <p><i>Sus scrofa palustris</i>, i. 68.</p> + <p><i>Sus vittatus</i>, i. 67.</p> + <p><span class="sc">Swallows</span>, a breed of pigeons, i. 156.</p> + <p><span class="sc">Swayne</span>, Mr., on artificial crossing of varieties of the pea, i. 397.</p> + <p><span class="sc">Sweet</span> Peas, ii. <a href="#page91">91</a>;</p> + <p class="i2">crosses of, ii. <a href="#page93">93</a>, <a href="#page94">94</a>;</p> + <p class="i2">varieties of, coming true by seed, ii. <a href="#page20">20</a>;</p> + <p class="i2">acclimatisation of, in India, ii. <a href="#page311">311</a>.</p> + <p><span class="sc">Sweet</span> William, bud-variation in, i. 381.</p> + <p><span class="sc">Swinhoe</span>, R., on Chinese pigeons, i. 28, 206;</p> + <p class="i2">on striped Chinese horses, i. 59.</p> + <p><span class="sc">Switzerland</span>, ancient dogs of, i. 19;</p> + <p class="i2">pigs of, in the Neolithic period, i. 67-68;</p> + <p class="i2">goats of, i. 101.</p> + <p><span class="sc">Sycamore</span>, pale-leaved variety of the, ii. <a href="#page330">330</a>.</p> + <p><span class="sc">Sykes</span>, Colonel, on a Pariah dog with crooked legs, i. 17;</p> + <p class="i2">on small Indian asses, i. 62;</p> + <p class="i2">on <i>Gallus Sonneratii</i>, i. 233;</p> + <p class="i2">on the voice of the Indian Kulm cock, i. 259;</p> + <p class="i2">fertility of the fowl in most climates, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Symmetry</span>, hereditary departures from, ii. <a href="#page12">12</a>.</p> + <p><i>Symphytum</i>, variegated, i. 384.</p> + <p><span class="sc">Syphilis</span>, hereditary, ii. <a href="#page332">332</a>.</p> + <p><span class="sc">Syria</span>, asses of, i. 62.</p> + <p><i>Syringa persica</i>, <i>chinensis</i>, and <i>vulgaris</i>, ii. <a href="#page164">164</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Tacitus</span>, on the care taken by the Celts in breeding animals, ii. <a href="#page202">202</a>.</p> + <p><i>Tagetes signata</i>, dwarf variety of, ii. <a href="#page20">20</a>.</p> + <p><span class="sc">Tahiti</span>, varieties of cultivated plants in, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Tail</span>, occasional development of, in man, ii. <a href="#page57">57</a>;</p> + <p class="i2">never curled in wild animals, ii. <a href="#page301">301</a>;</p> + <p class="i2">rudimentary in Chinese sheep, ii. <a href="#page315">315</a>.</p> + <p><span class="sc">Tail-feathers</span>, numbers of, in breeds of pigeons, i. 158-159;</p> + <p class="i2">peculiarities of, in cocks, i. 254-255;</p> + <p class="i2">variability of, in fowls, i. 258;</p> + <p class="i2">curled, in <i>Anas boschas</i>, and tame drakes, i. 280.</p> + <p><span class="sc">Talent</span>, hereditary, ii. <a href="#page7">7</a>.</p> + <p><span class="sc">Tankerville</span>, Earl of, on Chillingham cattle, i. 84, ii. <a href="#page119">119</a>.</p> + <p><span class="sc">Tanner</span>, Prof., effects of disuse of parts in cattle, ii. <a href="#page299">299</a>.</p> + <p><span class="sc">Tapir</span>, sterility of the, in captivity, ii. <a href="#page150">150</a>.</p> + <p><span class="sc">Targioni-Tozzetti</span>, on cultivated plants, i. 306;</p> + <p class="i2">on the vine, i. 332;</p> + <p class="i2">varieties of the peach, i. 342;</p> + <p class="i2">origin and varieties of the plum, i. 345;</p> + <p class="i2">origin of the cherry, i. 347;</p> + <p class="i2">origin of roses, i. 366.</p> + <p><span class="sc">Tarsus</span>, variability of the, in fowls, i. 259;</p> + <p class="i2">reproduction of the, in a thrush, ii. <a href="#page15">15</a>.</p> + <p><span class="sc">Tartars</span>, their preference for spiral-horned sheep, ii. <a href="#page209">209</a>.</p> + <p><span class="sc">Tavernier</span>, abundance of pigeons in Persia, i. 205.</p> + <p><i>Taxus baccata</i>, ii. <a href="#page18">18</a>.</p> + <p><span class="sc">Teebay</span>, Mr., reversion in fowls, ii. <a href="#page38">38</a>.</p> + <p><span class="sc">Teeth</span>, number and position of, in dogs, i. 34;</p> + <p class="i2">deficiency of, in naked Turkish dogs, i. 35;</p> + <p class="i2">period of appearance of, in breeds of dogs, i. 35;</p> + <p class="i2">precocity of, in highly bred animals, ii. <a href="#page322">322</a>;</p> + <p class="i2">correlation of, with hair, ii. <a href="#page326">326</a>;</p> + <p class="i2">double row of, with redundant hair, in Julia Pastrana, ii. <a href="#page328">328</a>;</p> + <p class="i2">affected in form by hereditary syphilis and by pulmonary tubercle, ii. <a href="#page332">332</a>;</p> + <p class="i2">fusion of, ii. <a href="#page341">341</a>;</p> + <p class="i2">developed on the palate, ii. <a href="#page391">391</a>.</p> + <p><span class="sc">Tegetmeier</span>, Mr., on a cat with monstrous teeth, i. 48;</p> + <p class="i2">on a swift-like pigeon, i. 157;</p> + <p class="i2">naked young of some pigeons, i. 170;</p> + <p class="i2">fertility of hybrid pigeons, i. 192;</p> + <p class="i2">on white pigeons, ii. <a href="#page230">230</a>;</p> + <p class="i2">reversion in crossed breeds of fowls, i. 239-244;</p> + <p class="i2">chicks of the white silk-fowl, i. 249;</p> + <p class="i2">development of the cranial protuberance in Polish fowls, i. 250;</p> + <p class="i2">on the skull in the Polish fowl, i. 257, 262;</p> + <p class="i2">on the intelligence of Polish fowls, i. 264;</p> + <p class="i2">correlation of the cranial protuberance and crest in Polish fowls, i. 274;</p> + <p class="i2">development of the web in the feet of Polish fowls, i. 259;</p> + <p class="i2">early development of several peculiarities in Spanish cocks, i. 250;</p> + <p class="i2">on the comb in Spanish fowls, i. 253;</p> + <p class="i2">on the Spanish fowl, ii. <a href="#page306">306</a>;</p> + <p class="i2">varieties of game-fowls, i. 252;</p> + <p class="i2">pedigrees of game-fowls, ii. <a href="#page3">3</a>;</p> + <p class="i2">assumption of female plumage by a game cock, i. 253;</p> + <p class="i2">natural selection in the game cock, ii. <a href="#page225">225</a>;</p> + <p class="i2">pugnacity of game hens, i. 256;</p> + <p class="i2">length of the middle toe in Cochin fowls, i. 259;</p> + <p class="i2">origin of the Sebright bantam, ii. <a href="#page54">54</a>;</p> + <p class="i2">differences in the size of fowls, i. 257;</p> + <p class="i2">effect of crossing in fowls, i. 258, ii. <a href="#page96">96</a>;</p> + <p class="i2">effects of interbreeding in fowls, ii. <a href="#page124">124</a>-<a href="#page125">125</a>;</p> + <p class="i2">incubation by mongrels of non-sitting races of fowls, ii. <a href="#page44">44</a>;</p> + <p class="i2">inverse correlation of crest and comb in fowls, i. 274;</p> +<!-- Page 481 --><span class="pagenum"><a name="page481"></a>{481}</span> + <p class="i2">occurrence of pencilled feathers in fowls, ii. <a href="#page40">40</a>;</p> + <p class="i2">on a variety of the goose from Sebastopol, i. 289;</p> + <p class="i2">on the fertility of the peahen, ii. <a href="#page112">112</a>;</p> + <p class="i2">on the intercrossing of bees, ii. <a href="#page126">126</a>.</p> + <p><span class="sc">Temminck</span>, origin of domestic cats, i. 43;</p> + <p class="i2">origin of domestic pigeons, i. 180;</p> + <p class="i2">on <i>Columba guinea</i>, i. 182;</p> + <p class="i2">on <i>Columba leucocephala</i>, i. 183;</p> + <p class="i2">asserted reluctance of some breeds of pigeons to cross, i. 192;</p> + <p class="i2">sterility of hybrid turtle-doves, i. 193;</p> + <p class="i2">variations of <i>Gallus bankiva</i>, i. 235;</p> + <p class="i2">on a buff-coloured breed of Turkeys, i. 293;</p> + <p class="i2">number of eggs laid by the peahen, ii. <a href="#page112">112</a>;</p> + <p class="i2">breeding of Guans in captivity, ii. <a href="#page156">156</a>;</p> + <p class="i2">behaviour of grouse in captivity, <i>ibid.</i>;</p> + <p class="i2">sterility of the partridge in captivity, <i>ibid.</i></p> + <p><span class="sc">Tendrils</span> in Cucurbitaceæ, i. 358, ii. <a href="#page316">316</a>.</p> + <p><span class="sc">Tennent</span>, Sir J. E., on the goose, i. 287;</p> + <p class="i2">on the growth of the apple in Ceylon, ii. <a href="#page277">277</a>;</p> + <p class="i2">on the Jaffna sheep, ii. <a href="#page302">302</a>.</p> + <p><i>Teredo</i>, fertilisation in, ii. <a href="#page363">363</a>.</p> + <p><span class="sc">Terriers</span>, wry-legged, ii. <a href="#page245">245</a>;</p> + <p class="i2">white, subject to distemper, ii. <a href="#page336">336</a>.</p> + <p><span class="sc">Teschemacher</span>, on a husked form of maize, i. 320.</p> + <p><span class="sc">Tessier</span>, on the period of gestation of the dog, i. 29;</p> + <p class="i2">of the pig, i. 74;</p> + <p class="i2">in cattle, i. 87;</p> + <p class="i2">experiments on change of soil, ii. <a href="#page147">147</a>.</p> + <p><i>Tetrao</i>, breeding of species of, in captivity, ii. <a href="#page156">156</a>.</p> + <p><i>Tetrapteryx paradisea</i>, ii. <a href="#page156">156</a>.</p> + <p><i>Teucrium campanulatum</i>, pelorism in, ii. <a href="#page345">345</a>.</p> + <p><span class="sc">Texas</span>, feral cattle in, i. 85.</p> + <p><span class="sc">Theognis</span>, his notice of the domestic fowl, i. 246.</p> + <p><span class="sc">Theophrastus</span>, his notice of the peach, ii. <a href="#page308">308</a>.</p> + <p><i>Thesium</i>, ii. <a href="#page284">284</a>.</p> + <p><span class="sc">Thompson</span>, Mr., on the peach and nectarine, i. 342;</p> + <p class="i2">on the varieties of the apricot, i. 344;</p> + <p class="i2">classification of varieties of cherries, i. 347-348;</p> + <p class="i2">on the "Sister ribston-pippin," i. 350;</p> + <p class="i2">on the varieties of the gooseberry, i. 354, 355.</p> + <p><span class="sc">Thompson</span>, William, on the pigeons of Islay, i. 184;</p> + <p class="i2">feral pigeons in Scotland, i. 190;</p> + <p class="i2">colour of the bill and legs in geese, i. 288;</p> + <p class="i2">breeding of <i>Tetrao scotius</i> in captivity, ii. <a href="#page156">156</a>;</p> + <p class="i2">destruction of black-fowls by the osprey, ii. <a href="#page230">230</a>.</p> + <p><span class="sc">Thompson</span>, Prof. W., on the obliquity of the flounder, ii. <a href="#page53">53</a>.</p> + <p><span class="sc">Thorns</span>, reconversion of, into branches, in pear trees, ii. <a href="#page318">318</a>.</p> + <p><span class="sc">Thorn</span>, grafting of early and late, i. 363;</p> + <p class="i2">Glastonbury, i. 364.</p> + <p><span class="sc">Thrush</span>, asserted reproduction of the tarsus in a, ii. <a href="#page15">15</a>.</p> + <p><i>Thuja pendula</i> or <i>filiformis</i>, a variety of <i>T. orientalis</i>, i. 362.</p> + <p><span class="sc">Thuret</span>, on the division of the zoospores of an alga, ii. <a href="#page378">378</a>.</p> + <p><span class="sc">Thwaites</span>, G. H., on the cats of Ceylon, i. 46;</p> + <p class="i2">on a twin seed of <i>Fuchsia coccinea</i> and <i>fulgens</i>, i. 391.</p> + <p><span class="sc">Tiburtius</span>, experiments in rearing wild ducks, i. 278.</p> + <p><span class="sc">Tiger</span>, rarely fertile in captivity, ii. <a href="#page150">150</a>, <a href="#page151">151</a>.</p> + <p><i>Tigridia conchiflora</i>, bud-variation in, i. 386.</p> + <p><span class="sc">Time</span>, importance of, in the production of races, ii. <a href="#page243">243</a>.</p> + <p><span class="sc">Tinzmann</span>, self-impotence in the potato, ii. <a href="#page137">137</a>.</p> + <p><span class="sc">Tissues</span>, affinity of, for special organic substances, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Titmice</span>, destructive to thin-shelled walnuts, i. 356;</p> + <p class="i2">attacking nuts, i. 357;</p> + <p class="i2">attacking peas, ii. <a href="#page231">231</a>.</p> + <p><span class="sc">Tobacco</span>, crossing of varieties of, ii. <a href="#page108">108</a>;</p> + <p class="i2">cultivation of in Sweden, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Tobolsk</span>, red-coloured cats of, i. 47.</p> + <p><span class="sc">Toes</span>, relative length of, in fowls, i. 259;</p> + <p class="i2">development of fifth in dogs, ii. <a href="#page317">317</a>.</p> + <p><span class="sc">Tollet</span>, Mr., his selection of cattle, ii. <a href="#page199">199</a>.</p> + <p><span class="sc">Tomato</span>, ii. <a href="#page91">91</a>.</p> + <p><span class="sc">Tomtits</span>. See <i>Titmice</i>.</p> + <p><span class="sc">Tongue</span>, relation of, to the beak in pigeons, i. 168.</p> + <p><span class="sc">Tooth</span>, occurrence of a molar, in place of an incisor, ii. <a href="#page391">391</a>.</p> + <p>"<span class="sc">Torfschwein</span>," i. 68.</p> + <p><span class="sc">Trail</span>, R., on the union of half-tubers of different kinds of potatoes, i. 395.</p> + <p><span class="sc">Trees</span>, varieties of, suddenly produced, i. 361;</p> + <p class="i2">weeping or pendulous, i. 361;</p> + <p class="i2">fastigate or pyramidal, i. 361;</p> + <p class="i2">with variegated or changed foliage, i. 362;</p> + <p class="i2">early or late in leaf, i. 362-363;</p> + <p class="i2">forest, non-application of selection to, ii. <a href="#page237">237</a>.</p> + <p>"<span class="sc">Trembleur</span>" (pigeons), i. 146.</p> + <p><span class="sc">Trembley</span>, on reproduction in Hydra, ii. <a href="#page359">359</a>.</p> + <p>"<span class="sc">Trevoltini</span>" silkworms, i. 301-302.</p> + <p><i>Trichosanthes anguina</i>, i. 360.</p> + <p><span class="sc">Tricks</span>, inheritance of, ii. <a href="#page6">6</a>-<a href="#page7">7</a>, <a href="#page395">395</a>.</p> + <p><i>Trifolium minus</i> and <i>repens</i>, ii. <a href="#page164">164</a>.</p> + <p><span class="sc">Trimorphic</span> plants, conditions of reproduction in, ii. <a href="#page181">181</a>-<a href="#page184">184</a>.</p> + <p><span class="sc">Tristram</span>, H. B., selection of the dromedary, ii. <a href="#page205">205</a>-<a href="#page206">206</a>.</p> + <p><i>Triticum dicoccum</i>, i. 319.</p> + <p><i>Triticum monococcum</i>, i. 319.</p> + <p><i>Triticum spelta</i>, i. 319.</p> + <p><i>Triticum turgidum</i>, i. 319.</p> + <p><i>Triticum vulgare</i>, wild in Asia, i. 312.</p> +<!-- Page 482 --><span class="pagenum"><a name="page482"></a>{482}</span> + <p><span class="sc">Triton</span>, breeding in the branchiferous stage, ii. <a href="#page384">384</a>.</p> + <p>"<span class="sc">Trommel-Taube</span>," i. 154.</p> + <p>"<span class="sc">Tronfo</span>" pigeon, i. 144.</p> + <p><i>Tropæolum</i>, ii. <a href="#page38">38</a>.</p> + <p><i>Tropæolum minus</i> and <i>majus</i>, reversion in hybrids of, i. 392.</p> + <p><span class="sc">Troubetzkoy</span>, Prince, experiments with pear-trees at Moscow, ii. <a href="#page307">307</a>.</p> + <p><span class="sc">Trousseau</span>, Prof., pathological resemblance of twins, ii. <a href="#page252">252</a>.</p> + <p><span class="sc">Trumpeter</span> pigeon, i. 154;</p> + <p class="i2">known in 1735, i. 207.</p> + <p><span class="sc">Tscharner</span>, H. A. de, graft-hybrid produced by inosculation in the vine, i. 395.</p> + <p><span class="sc">Tschudi</span>, on the naked Peruvian dog, i. 23;</p> + <p class="i2">extinct varieties of maize from Peruvian tombs, i. 320, ii. <a href="#page425">425</a>.</p> + <p><span class="sc">Tubers</span>, bud-variation by, i. 384-385.</p> + <p><span class="sc">Tuckerman</span>, Mr., sterility of <i>Carex rigida</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Tufted</span> ducks, i. 281.</p> + <p><span class="sc">Tulips</span>, variability of, i. 370;</p> + <p class="i2">bud-variation in, i. 385-386;</p> + <p class="i2">influence of soil in "breaking," i. 385.</p> + <p><span class="sc">Tumbler</span> pigeon, i. 150-153;</p> + <p class="i2">short-faced, figured, i. 152;</p> + <p class="i2">skull figured, i. 163;</p> + <p class="i2">lower jaw figured, i. 165;</p> + <p class="i2">scapula and furcula figured, i. 167;</p> + <p class="i2">early known in India, i. 207;</p> + <p class="i2">history of, i. 209;</p> + <p class="i2">sub-breeds of, i. 220;</p> + <p class="i2">young unable to break the egg-shell, ii. <a href="#page226">226</a>;</p> + <p class="i2">probable further modification of, ii. <a href="#page242">242</a>.</p> + <p>"<span class="sc">Tümmler</span>" (pigeons), i. 150.</p> + <p><span class="sc">Tumours</span>, ovarian, occurrence of hairs and teeth in, ii. <a href="#page370">370</a>;</p> + <p class="i2">polypoid, origin of, ii. <a href="#page381">381</a>.</p> + <p>"<span class="sc">Türkische Taube</span>," i. 139.</p> + <p><span class="sc">Turbit</span> (pigeon), i. 148.</p> + <p><span class="sc">Turkey</span>, domestic, origin of, i. 292-293;</p> + <p class="i2">crossing of with North American wild Turkey, i. 292-293;</p> + <p class="i2">breeds of, i. 293;</p> + <p class="i2">crested white cock, i. 293;</p> + <p class="i2">wild, characters of, i. 293-294;</p> + <p class="i2">degeneration of, in India, i. 294, ii. <a href="#page278">278</a>;</p> + <p class="i2">failure of eggs of, in Delhi, ii. <a href="#page161">161</a>;</p> + <p class="i2">feral on the Parana, i. 190;</p> + <p class="i2">change produced in by domestication, ii. <a href="#page262">262</a>.</p> + <p><span class="sc">Turkey</span>, striped young pigs in, i. 76.</p> + <p><span class="sc">Turner</span> (pigeon), i. 156.</p> + <p><span class="sc">Turner</span>, W., on compensation in arteries and veins, ii. <a href="#page300">300</a>;</p> + <p class="i2">on cells, ii. <a href="#page370">370</a>.</p> + <p><span class="sc">Turnips</span>, origin of, i. 325;</p> + <p class="i2">reversion in, ii. <a href="#page31">31</a>;</p> + <p class="i2">run wild, ii. <a href="#page33">33</a>;</p> + <p class="i2">crosses of, ii. <a href="#page93">93</a>, <a href="#page96">96</a>;</p> + <p class="i2">Swedish, preferred by hares, ii. <a href="#page232">232</a>;</p> + <p class="i2">acclimatisation of, in India, ii. <a href="#page311">311</a>.</p> + <p><span class="sc">Turnspit</span>, on an Egyptian monument, i. 17;</p> + <p class="i2">crosses of the, ii. <a href="#page92">92</a>.</p> + <p><span class="sc">Turtle-dove</span>, white and coloured, crossing of, ii. <a href="#page92">92</a>.</p> + <p><i>Turtur auritus</i>, hybrids of, with <i>T. cambayensis</i> and <i>T. suratensis</i>, i. 194.</p> + <p><i>Turtur risorius</i>, crossing of, with the common pigeon, i. 193;</p> + <p class="i2">hybrid of, with <i>T. vulgaris</i>, <i>ibid.</i></p> + <p><i>Turtur suratensis</i>, sterile hybrids of, with <i>T. vulgaris</i>, i. 193;</p> + <p class="i2">hybrids of, with <i>T. auritus</i>, i. 194.</p> + <p><i>Turtur vulgaris</i>, crossing of, with the common pigeon, i. 193;</p> + <p class="i2">hybrid of, with <i>T. risorius</i>, <i>ibid.</i>;</p> + <p class="i2">sterile hybrids of, with <i>T. suratensis</i> and <i>Ectopistes migratorius</i>, <i>ibid.</i></p> + <p><span class="sc">Tusks</span> of wild and domesticated pigs, i. 76, 77.</p> + <p><i>Tussilago farfara</i>, variegated, i. 384.</p> + <p><span class="sc">Twin-seed</span> <i>Fuchsia coccinea</i> and <i>fulgens</i>, i. 391.</p> + <p><span class="sc">Tyerman</span>, B., on the pigs of the Pacific islands, i. 70, ii. <a href="#page87">87</a>;</p> + <p class="i2">on the dogs of the Pacific islands, ii. <a href="#page87">87</a>.</p> + <p><span class="sc">Tylor</span>, Mr., on the prohibition of consanguineous marriages, ii. <a href="#page122">122</a>-<a href="#page123">123</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Udders</span>, development of the, ii. <a href="#page300">300</a>.</p> + <p><i>Ulex</i>, double-flowered, ii. <a href="#page167">167</a>.</p> + <p><i>Ulmus campestris</i> and <i>effusa</i>, hybrids of, ii. <a href="#page130">130</a>.</p> + <p><span class="sc">Uniformity</span> of character, maintained by crossing, ii. <a href="#page85">85</a>-<a href="#page90">90</a>.</p> + <p><span class="sc">Units</span> of the body, functional independence of the, ii. <a href="#page368">368</a>-<a href="#page371">371</a>.</p> + <p><span class="sc">Unity</span> or plurality of origin of organisms, i. 13.</p> + <p><span class="sc">Upas</span> poison, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Urea</span>, secretion of, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Use</span> and disuse of parts, effects of, ii. <a href="#page295">295</a>-<a href="#page303">303</a>, <a href="#page352">352</a>-<a href="#page353">353</a>, <a href="#page418">418</a>-<a href="#page419">419</a>;</p> + <p class="i2">in rabbits, i. 124-128;</p> + <p class="i2">in ducks, i. 284-286.</p> + <p><span class="sc">Utility</span>, considerations of, leading to uniformity, ii. <a href="#page241">241</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Valentin</span>, experimental production of double monsters by, ii. <a href="#page340">340</a>.</p> + <p><i>Vallota</i>, ii. <a href="#page139">139</a>.</p> + <p><span class="sc">Van Beck</span>, Barbara, a hairy-faced woman, ii. <a href="#page4">4</a>.</p> + <p><span class="sc">Van Mons</span> on wild fruit-trees, i. 312, ii. <a href="#page260">260</a>;</p> + <p class="i2">production of varieties of the vine, i. 333;</p> + <p class="i2">correlated variability in fruit-trees, ii. <a href="#page330">330</a>;</p> + <p class="i2">production of almond-like fruit by peach-seedlings, i. 339.</p> + <p><i>Vanessa</i>, species of, not copulating in captivity, ii. <a href="#page157">157</a>.</p> + <p><span class="sc">Variability</span>, i. 4, ii. <a href="#page371">371</a>-<a href="#page373">373</a>, <a href="#page394">394</a>-<a href="#page397">397</a>, <a href="#page406">406</a>-<a href="#page420">420</a>;</p> + <p class="i2">causes of, ii. <a href="#page250">250</a>-<a href="#page270">270</a>;</p> + <p class="i2">correlated, ii. <a href="#page319">319</a>-<a href="#page338">338</a>, <a href="#page353">353</a>-<a href="#page355">355</a>, <a href="#page419">419</a>-<a href="#page420">420</a>;</p> + <p class="i2">law of equable, ii. <a href="#page351">351</a>-<a href="#page352">352</a>;</p> + <p class="i2">necessity of, for selection, ii. <a href="#page192">192</a>;</p> + <p class="i2">of selected characters, ii. <a href="#page238">238</a>-<a href="#page239">239</a>;</p> + <p class="i2">of multiple homologous parts, ii. <a href="#page342">342</a>.</p> +<!-- Page 483 --><span class="pagenum"><a name="page483"></a>{483}</span> + <p><span class="sc">Variation</span>, laws of, ii. <a href="#page293">293</a>-<a href="#page356">356</a>;</p> + <p class="i2">continuity of, ii. <a href="#page241">241</a>;</p> + <p class="i2">possible limitation of, ii. <a href="#page242">242</a>, <a href="#page416">416</a>-<a href="#page417">417</a>;</p> + <p class="i2">in domestic cats, i. 45-48;</p> + <p class="i2">origin of breeds of cattle by, i. 88;</p> + <p class="i2">in osteological characters of rabbits, i. 115-130;</p> + <p class="i2">of important organs, i. 359;</p> + <p class="i2">analogous or parallel, i. 348-352;</p> + <p class="i2">in horses, i. 55;</p> + <p class="i2">in the horse and ass, i. 64;</p> + <p class="i2">in fowls, i. 243-246;</p> + <p class="i2">in geese, i. 288;</p> + <p class="i2">exemplified in the production of fleshy stems in cabbages, &c., i. 326;</p> + <p class="i2">in the peach, nectarine, and apricot, i. 342, 344;</p> + <p class="i2">individual, in wheat, i. 314.</p> + <p><span class="sc">Variegation</span> of foliage, i. 383, ii. <a href="#page167">167</a>-<a href="#page168">168</a>.</p> + <p><span class="sc">Varieties</span> and species, resemblance of, i. 4, ii. <a href="#page411">411</a>-<a href="#page413">413</a>;</p> + <p class="i2">conversion of, into species, i. 5;</p> + <p class="i2">abnormal, ii. <a href="#page413">413</a>;</p> + <p class="i2">domestic, gradually produced, ii. <a href="#page414">414</a>.</p> + <p><span class="sc">Varro</span>, on domestic ducks, i. 277;</p> + <p class="i2">on feral fowls, ii. <a href="#page33">33</a>;</p> + <p class="i2">crossing of the wild and domestic ass, ii. <a href="#page206">206</a>.</p> + <p><span class="sc">Vasey</span>, Mr., on the number of sacral vertebræ in ordinary and humped cattle, i. 79;</p> + <p class="i2">on Hungarian cattle, i. 80.</p> + <p><span class="sc">Vaucher</span>, sterility of <i>Ranunculus ficaria</i> and <i>Acorus calamus</i>, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Vegetables</span>, cultivated, reversion in, ii. <a href="#page31">31</a>-<a href="#page32">32</a>;</p> + <p class="i2">European, culture of, in India, ii. <a href="#page168">168</a>-<a href="#page169">169</a>.</p> + <p><span class="sc">Veith</span>, Mr., on breeds of horses, i. 49.</p> + <p><i>Verbascum</i>, intercrossing of species of, i. 336, ii. <a href="#page93">93</a>, <a href="#page105">105</a>-<a href="#page107">107</a>;</p> + <p class="i2">reversion in hybrids of, i. 392;</p> + <p class="i2">contabescent, wild plants of, ii. <a href="#page165">165</a>;</p> + <p class="i2">villosity in, ii. <a href="#page277">277</a>.</p> + <p><i>Verbascum austriacum</i>, ii. <a href="#page136">136</a>.</p> + <p><i>Verbascum blattaria</i>, ii. <a href="#page105">105</a>-<a href="#page106">106</a>.</p> + <p><i>Verbascum lychnitis</i>, ii. <a href="#page105">105</a>-<a href="#page106">106</a>, <a href="#page136">136</a>.</p> + <p><i>Verbascum nigrum</i>, ii. <a href="#page136">136</a>.</p> + <p><i>Verbascum phœniceum</i>, ii. <a href="#page107">107</a>, <a href="#page137">137</a>;</p> + <p class="i2">variable duration of, ii. <a href="#page305">305</a>.</p> + <p><i>Verbascum thapsus</i>, ii. <a href="#page106">106</a>.</p> + <p><span class="sc">Verbenas</span>, origin of, i. 364;</p> + <p class="i2">white, liability of, to mildew, ii. <a href="#page228">228</a>, <a href="#page336">336</a>;</p> + <p class="i2">scorching of dark, ii. <a href="#page229">229</a>, <a href="#page336">336</a>;</p> + <p class="i2">effect of changed conditions of life on, ii. <a href="#page273">273</a>.</p> + <p><span class="sc">Verlot</span>, on the darkleaved Barberry, i. 362;</p> + <p class="i2">inheritance of peculiarities of foliage in trees, i. 362;</p> + <p class="i2">production of <i>Rosa cannabifolia</i> by bud-variation from <i>R. alba</i>, i. 381;</p> + <p class="i2">bud-variation in <i>Aralia trifoliata</i>, i. 382;</p> + <p class="i2">variegation of leaves, i. 383;</p> + <p class="i2">colours of tulips, i. 386;</p> + <p class="i2">uncertainty of inheritance, ii. <a href="#page18">18</a>;</p> + <p class="i2">persistency of white flowers, ii. <a href="#page20">20</a>;</p> + <p class="i2">peloric flowers of <i>Linaria</i>, ii. <a href="#page58">58</a>;</p> + <p class="i2">tendency of striped flowers to uniformity of colour, ii. <a href="#page70">70</a>;</p> + <p class="i2">non-intercrossing of certain allied plants, ii. <a href="#page91">91</a>;</p> + <p class="i2">sterility of <i>Primulæ</i> with coloured calyces, ii. <a href="#page166">166</a>;</p> + <p class="i2">on fertile proliferous flowers, <i>ibid.</i>;</p> + <p class="i2">on the Irish yew, ii. <a href="#page241">241</a>;</p> + <p class="i2">differences in the <i>Camellia</i>, ii. <a href="#page251">251</a>;</p> + <p class="i2">effect of soil on the variegated strawberry, ii. <a href="#page274">274</a>;</p> + <p class="i2">correlated variability in plants, ii. <a href="#page330">330</a>.</p> + <p><i>Verruca</i>, ii. <a href="#page53">53</a>, <a href="#page400">400</a>.</p> + <p><span class="sc">Vertebræ</span>, characters of, in rabbits, i. 120-122;</p> + <p class="i2">in ducks, i. 283-284;</p> + <p class="i2">number and variations of, in pigeons, i. 165-166;</p> + <p class="i2">number and characters of, in fowls, i. 266-268;</p> + <p class="i2">variability of number of, in the pig, i. 74.</p> + <p><span class="sc">Vertuch</span>, see Putsche.</p> + <p>"<span class="sc">Verugas</span>," ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Vespucius</span>, early cultivation in Brazil, i. 311.</p> + <p><span class="sc">Vibert's</span> experiments on the cultivation of the vine from seed, i. 332.</p> + <p><i>Viburnum opulus</i>, ii. <a href="#page185">185</a>, <a href="#page316">316</a>.</p> + <p><i>Vicia sativa</i>, leaflet converted into a tendril in, ii. <a href="#page392">392</a>.</p> + <p><span class="sc">Vicunas</span>, selection of, ii. <a href="#page207">207</a>.</p> + <p><span class="sc">Villosity</span> of plants, influenced by dryness, ii. <a href="#page277">277</a>.</p> + <p><span class="sc">Vilmorin</span>, cultivation of the wild carrot, i. 326, ii. <a href="#page217">217</a>;</p> + <p class="i2">colours of tulips, i. 386;</p> + <p class="i2">uncertainty of inheritance in balsams and roses, ii. <a href="#page18">18</a>;</p> + <p class="i2">experiments with dwarf varieties of <i>Saponaria calabrica</i> and <i>Tagetes signata</i>, ii. <a href="#page20">20</a>;</p> + <p class="i2">reversion of flowers by stripes and blotches, ii. <a href="#page37">37</a>;</p> + <p class="i2">on variability, ii. <a href="#page262">262</a>.</p> + <p><i>Vinca minor</i>, sterility in, ii. <a href="#page170">170</a>.</p> + <p><span class="sc">Vine</span>, i. 332-334;</p> + <p class="i2">parsley-leaved, reversion of, i. 382;</p> + <p class="i2">graft-hybrid produced by inosculation in the, i. 395;</p> + <p class="i2">disease of, influenced by colour of grapes, ii. <a href="#page228">228</a>;</p> + <p class="i2">influence of climate, &c., on varieties of the, ii. <a href="#page278">278</a>;</p> + <p class="i2">diminished extent of cultivation of the, ii. <a href="#page308">308</a>;</p> + <p class="i2">acclimatisation of the, in the West Indies, ii. <a href="#page313">313</a>.</p> + <p><i>Viola</i>, species of, i. 368.</p> + <p><i>Viola lutea</i>, different coloured flowers in, i. 408.</p> + <p><i>Viola tricolor</i>, reversion in, ii. <a href="#page31">31</a>, <a href="#page47">47</a>.</p> + <p><span class="sc">Virchow</span>, Prof., blindness occurring in the offspring of consanguineous marriages, ii. <a href="#page143">143</a>;</p> + <p class="i2">on the growth of bones, ii. <a href="#page294">294</a>, <a href="#page381">381</a>;</p> + <p class="i2">on cellular prolification, ii. <a href="#page295">295</a>;</p> + <p class="i2">independence of the elements of the body, ii. <a href="#page369">369</a>;</p> + <p class="i2">on the cell-theory, ii. <a href="#page370">370</a>;</p> + <p class="i2">presence of hairs and teeth in ovarian tumours, ii. <a href="#page370">370</a>;</p> + <p class="i2">of hairs in the brain, ii. <a href="#page391">391</a>;</p> + <p class="i2">special affinities of the tissues, ii. <a href="#page380">380</a>;</p> + <p class="i2">origin of polypoid excrescences and tumours, ii. <a href="#page381">381</a>.</p> + <p><span class="sc">Virgil</span> on the selection of seed-corn, i. 318, ii. <a href="#page203">203</a>;</p> + <p class="i2">of cattle and sheep, ii. <a href="#page202">202</a>.</p> + <p><span class="sc">Virginian</span> islands, ponies of, i. 52.</p> + <p><i>Virgularia</i>, ii. <a href="#page378">378</a>.</p> + <p><span class="sc">Vision</span>, hereditary peculiarities of, ii. <a href="#page8">8</a>-<a href="#page9">9</a>;</p> +<!-- Page 484 --><span class="pagenum"><a name="page484"></a>{484}</span> + <p class="i2">in amphibious animals, ii. <a href="#page223">223</a>;</p> + <p class="i2">varieties of, ii. <a href="#page300">300</a>;</p> + <p class="i2">affections of organs of, correlated with other peculiarities, ii. <a href="#page328">328</a>.</p> + <p><i>Vitis vinifera</i>, i. 332-334, 375.</p> + <p><i>Viverra</i>, sterility of species of, in captivity, ii. <a href="#page151">151</a>.</p> + <p><span class="sc">Vogel</span>, varieties of the date palm, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Vogt</span>, on the indications of stripes on black kittens, ii. <a href="#page55">55</a>.</p> + <p><span class="sc">Voice</span>, differences of, in fowls, i. 259;</p> + <p class="i2">peculiarities of, in ducks, i. 281;</p> + <p class="i2">inheritance of peculiarities of, ii. <a href="#page6">6</a>.</p> + <p><span class="sc">Volz</span>, on the history of the dog, i. 16;</p> + <p class="i2">ancient history of the fowl, i. 246;</p> + <p class="i2">domestic ducks unknown to Aristotle, i. 277;</p> + <p class="i2">Indian cattle sent to Macedonia by Alexander, ii. <a href="#page202">202</a>;</p> + <p class="i2">mention of mules in the Bible, ii. <a href="#page202">202</a>;</p> + <p class="i2">history of the increase of breeds, ii. <a href="#page244">244</a>.</p> + <p><span class="sc">Von Berg</span> on <i>Verbascum phœniceum</i>, ii. <a href="#page305">305</a>.</p> + <p><span class="sc">Voorhelm</span>, G., his knowledge of hyacinths, i. 371, ii. <a href="#page251">251</a>.</p> + <p><span class="sc">Vrolik</span>, Prof., on polydactylism, ii. <a href="#page12">12</a>;</p> + <p class="i2">on double monsters, ii. <a href="#page340">340</a>;</p> + <p class="i2">influence of the shape of the mother's pelvis on her child's head, ii. <a href="#page344">344</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Waders</span>, behaviour of, in confinement, ii. <a href="#page156">156</a>.</p> + <p><span class="sc">Wahlenberg</span>, on the propagation of Alpine plants by buds, runners, bulbs, &c., ii. <a href="#page169">169</a>.</p> + <p>"<span class="sc">Wahlverwandtschaft</span>" of Gärtner, ii. <a href="#page180">180</a>.</p> + <p><span class="sc">Wales</span>, white cattle of, in the 10th century, i. 85.</p> + <p><span class="sc">Walker</span>, A., on intermarriage, i. 404;</p> + <p class="i2">on the inheritance of polydactylism, ii. <a href="#page13">13</a>.</p> + <p><span class="sc">Walker</span>, D., advantage of change of soil to wheat, ii. <a href="#page146">146</a>.</p> + <p><span class="sc">Wallace</span>, A. R., on a striped Javanese horse, i. 59;</p> + <p class="i2">on the conditions of life of feral animals, ii. <a href="#page32">32</a>;</p> + <p class="i2">artificial alteration of the plumage of birds, ii. <a href="#page280">280</a>;</p> + <p class="i2">on polymorphic butterflies, ii. <a href="#page399">399</a>-<a href="#page400">400</a>;</p> + <p class="i2">on reversion, ii. <a href="#page415">415</a>;</p> + <p class="i2">on the limit of change, ii. <a href="#page417">417</a>.</p> + <p><span class="sc">Wallace</span>, Dr., on the sterility of Sphingidæ hatched in autumn, ii. <a href="#page158">158</a>.</p> + <p><span class="sc">Wallachian</span> sheep, sexual peculiarities in the horns of, i. 96.</p> + <p><span class="sc">Wallflower</span>, bud-variation in, i. 382.</p> + <p><span class="sc">Wallich</span>, Dr., on <i>Thuja pendula</i> or <i>filiformis</i>, i. 362.</p> + <p><span class="sc">Walnuts</span>, i. 356-357;</p> + <p class="i2">thin-shelled, attacked by tomtits, ii. <a href="#page231">231</a>;</p> + <p class="i2">grafting of, ii. <a href="#page259">259</a>.</p> + <p><span class="sc">Walsh</span>, B. D., on galls, ii. <a href="#page282">282</a>, <a href="#page283">283</a>;</p> + <p class="i2">his "Law of equable variability," ii. <a href="#page351">351</a>-<a href="#page352">352</a>.</p> + <p><span class="sc">Walther</span>, F. L., on the history of the dog, i. 16;</p> + <p class="i2">on the intercrossing of the zebu and ordinary cattle, i. 83.</p> + <p><span class="sc">Waring</span>, Mr., on individual sterility, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Wart</span> hog, i. 76.</p> + <p><span class="sc">Waterer</span>, Mr., spontaneous production of <i>Cytisus alpino-laburnum</i>, i. 390.</p> + <p><span class="sc">Water</span> melon, i. 357.</p> + <p><span class="sc">Waterhouse</span>, G. R., on the winter-colouring of <i>Lepus variabilis</i>, i. 111.</p> + <p><span class="sc">Waterton</span>, C., production of tailless foals, i. 53;</p> + <p class="i2">on taming wild ducks, i. 278;</p> + <p class="i2">on the wildness of half-bred wild ducks, ii. <a href="#page45">45</a>;</p> + <p class="i2">assumption of male characters by a hen, ii. <a href="#page51">51</a>.</p> + <p><span class="sc">Watson</span>, H. C., on British wild fruit-trees, i. 312;</p> + <p class="i2">on the non-variation of weeds, i. 317;</p> + <p class="i2">origin of the plum, i. 345;</p> + <p class="i2">variation in <i>Pyrus malus</i>, i. 348;</p> + <p class="i2">on <i>Viola amœna</i> and <i>tricolor</i>, i. 368;</p> + <p class="i2">on reversion in Scotch kail, ii. <a href="#page32">32</a>;</p> + <p class="i2">fertility of <i>Draba sylvestris</i> when cultivated, ii. <a href="#page163">163</a>;</p> + <p class="i2">on generally distributed British plants, ii. <a href="#page285">285</a>.</p> + <p><span class="sc">Wattles</span>, rudimentary, in some fowls, ii. <a href="#page315">315</a>.</p> + <p><span class="sc">Watts</span>, Miss, on Sultan fowls, i. 228.</p> + <p><span class="sc">Webb</span>, James, interbreeding of sheep, ii. <a href="#page120">120</a>.</p> + <p><span class="sc">Weber</span>, effect of the shape of the mother's pelvis on her child's head, ii. <a href="#page344">344</a>.</p> + <p><span class="sc">Weeds</span>, supposed necessity for their modification, coincidently with cultivated plants, i. 317.</p> + <p><span class="sc">Weeping</span> varieties of trees, i. 361.</p> + <p><span class="sc">Weeping</span> habit of trees, capricious inheritance of, ii. <a href="#page18">18</a>-<a href="#page19">19</a>.</p> + <p><span class="sc">Weevil</span>, injury done to stone-fruit by, in North America, ii. <a href="#page231">231</a>.</p> + <p><span class="sc">Welsh</span> cattle, descended from <i>Bos longifrons</i>, i. 81.</p> + <p><span class="sc">West</span> Indies, feral pigs of, i. 77;</p> + <p class="i2">effect of climate of, upon sheep, i. 98.</p> + <p><span class="sc">Western</span>, Lord, change effected by, in the sheep, ii. <a href="#page198">198</a>.</p> + <p><span class="sc">Westphalia</span>, striped young pigs in, i. 76.</p> + <p><span class="sc">Westwood</span>, J. O., on peloric flowers of <i>Calceolaria</i>, ii. <a href="#page346">346</a>.</p> + <p><span class="sc">Whately</span>, Archbishop, on grafting early and late thorns, i. 363.</p> + <p><span class="sc">Wheat</span>, specific unity or diversity of, i. 312-313, 316-317;</p> + <p class="i2">Hasora, i. 313;</p> + <p class="i2">presence or absence of barbs in, i. 314;</p> + <p class="i2">Godron on variations in, <i>ibid.</i>;</p> + <p class="i2">varieties of, i. 314-315;</p> + <p class="i2">effects of soil and climate on, i. 316;</p> + <p class="i2">deterioration of, <i>ibid.</i>;</p> + <p class="i2">crossing of varieties of, <i>ibid.</i>, ii. <a href="#page96">96</a>, <a href="#page104">104</a>-<a href="#page105">105</a>, <a href="#page130">130</a>;</p> + <p class="i2">in the Swiss lake-dwellings, i. 317-319;</p> + <p class="i2">selection applied to, i. 318, ii. <a href="#page200">200</a>;</p> + <p class="i2">increased fertility of hybrids of, with <i>Ægilops</i>, ii. <a href="#page110">110</a>;</p> + <p class="i2">advantage of change of soil to, ii. <a href="#page146">146</a>;</p> +<!-- Page 485 --><span class="pagenum"><a name="page485"></a>{485}</span> + <p class="i2">differences of, in various parts of India, ii. <a href="#page165">165</a>;</p> + <p class="i2">continuous variation in, ii. <a href="#page200">200</a>;</p> + <p class="i2">red, hardiness of, ii. <a href="#page229">229</a>, <a href="#page336">336</a>;</p> + <p class="i2">Fenton, ii. <a href="#page232">232</a>;</p> + <p class="i2">natural selection in, ii. <a href="#page233">233</a>;</p> + <p class="i2">varieties of, found wild, ii. <a href="#page260">260</a>;</p> + <p class="i2">effects of change of climate on, ii. <a href="#page307">307</a>;</p> + <p class="i2">ancient variety of, ii. <a href="#page429">429</a>.</p> + <p><span class="sc">Whitby</span>, Mrs., on the markings of silkworms, i. 302;</p> + <p class="i2">on the silkmoth, i. 303.</p> + <p><span class="sc">White</span>, Mr., reproduction of supernumerary digits after amputation, ii. <a href="#page14">14</a>;</p> + <p class="i2">time occupied in the blending of crossed races, ii. <a href="#page87">87</a>.</p> + <p><span class="sc">White</span>, Gilbert, vegetable diet of dogs, ii. <a href="#page303">303</a>.</p> + <p><span class="sc">White</span> and white-spotted animals, liability of, to disease, ii. <a href="#page336">336</a>-<a href="#page337">337</a>.</p> + <p><span class="sc">White</span> flowers, most truly reproduced by seed, ii. <a href="#page20">20</a>.</p> + <p><span class="sc">Wichura</span>, Max, on hybrid willows, ii. <a href="#page50">50</a>, <a href="#page131">131</a>, <a href="#page267">267</a>;</p> + <p class="i2">analogy between the pollen of old-cultivated plants, and of hybrids, ii. <a href="#page268">268</a>.</p> + <p><span class="sc">Wicking</span>, Mr., inheritance of the primary characters of <i>Columba livia</i> in cross-bred pigeons, i. 201;</p> + <p class="i2">production of a white head in almond tumblers, ii. <a href="#page199">199</a>.</p> + <p><span class="sc">Wicksted</span>, Mr., on cases of individual sterility, ii. <a href="#page162">162</a>.</p> + <p><span class="sc">Wiegmann</span>, spontaneous crossing of blue and white peas, i. 397;</p> + <p class="i2">crossing of varieties of cabbage, ii. <a href="#page130">130</a>;</p> + <p class="i2">on contabescence, ii. <a href="#page165">165</a>.</p> + <p><span class="sc">Wight</span>, Dr., sexual sterility of plants propagated by buds, &c., ii. <a href="#page169">169</a>.</p> + <p><span class="sc">Wilde</span>, Sir W. R., occurrence of <i>Bos frontosus</i> and <i>longifrons</i> in Irish crannoges, i. 81;</p> + <p class="i2">attention paid to breeds of animals by the ancient Irish, ii. <a href="#page203">203</a>.</p> + <p><span class="sc">Wildman</span>, on the dahlia, ii. <a href="#page216">216</a>, <a href="#page273">273</a>.</p> + <p><span class="sc">Wildness</span> of the progeny of crossed tame animals, ii. <a href="#page44">44</a>-<a href="#page46">46</a>.</p> + <p><span class="sc">Wilkes</span>, Capt., on the taming of pigeons among the Polynesians, ii. <a href="#page161">161</a>.</p> + <p><span class="sc">Wilkinson</span>, J., on crossed cattle, ii. <a href="#page104">104</a>.</p> + <p><span class="sc">Williams</span>, Mr., change of plumage in a Hamburgh hen, i. 258.</p> + <p><span class="sc">Williams</span>, Mr., intercrossing of strawberries, i. 352.</p> + <p><span class="sc">Williamson</span>, Capt., degeneration of dogs in India, i. 37;</p> + <p class="i2">on small Indian asses, i. 62.</p> + <p><span class="sc">Williamson</span>, Rev. W., doubling of <i>Anemone coronaria</i> by selection, ii. <a href="#page200">200</a>.</p> + <p><span class="sc">Willows</span>, weeping, i. 361;</p> + <p class="i2">reversion of spiral-leaved weeping, i. 383;</p> + <p class="i2">hybrids of, ii. <a href="#page267">267</a>;</p> + <p class="i2">galls of, ii. <a href="#page282">282</a>-<a href="#page283">283</a>.</p> + <p><span class="sc">Willoughby</span>, F., notice of spot pigeons, i. 156;</p> + <p class="i2">on a fantail pigeon, i. 208;</p> + <p class="i2">on tumbler pigeons, i. 209;</p> + <p class="i2">on the turbit, i. 209;</p> + <p class="i2">on the barb and carrier pigeons, i. 211;</p> + <p class="i2">on the hook-billed duck, i. 277.</p> + <p><span class="sc">Wilmot</span>, Mr., on a crested white Turkey cock, i. 293;</p> + <p class="i2">reversion of sheep in colour, ii. <a href="#page30">30</a>.</p> + <p><span class="sc">Wilson</span>, B. O., fertility of hybrids of humped and ordinary cattle in Tasmania, i. 83.</p> + <p><span class="sc">Wilson</span>, Dr., prepotency of the Manx over the common cat, ii. <a href="#page66">66</a>.</p> + <p><span class="sc">Wilson</span>, James, origin of dogs, i. 16.</p> + <p><span class="sc">Wilson</span>, Mr., on prepotency of transmission in sheep, ii. <a href="#page69">69</a>;</p> + <p class="i2">on the breeding of bulls, ii. <a href="#page196">196</a>.</p> + <p><span class="sc">Wings</span>, proportionate length of, in different breeds of pigeons, i. 175-176;</p> + <p class="i2">of fowls, effects of disuse on, i. 270-272;</p> + <p class="i2">characters and variations of, in ducks, i. 284-286;</p> + <p class="i2">diminution of, in birds of small islands, i. 286-287.</p> + <p><span class="sc">Wing-feathers</span>, number of, in pigeons, i. 159;</p> + <p class="i2">variability of, in fowls, i. 258.</p> + <p><span class="sc">Wolf</span>, recent existence of, in Ireland, i. 16;</p> + <p class="i2">barking of young, i. 27;</p> + <p class="i2">hybrids of, with the dog, i. 32.</p> + <p><span class="sc">Wolf-dog</span>, black, of Florida, i. 22.</p> + <p><span class="sc">Wolves</span>, North American, their resemblance to dogs of the same region, i. 21-22;</p> + <p class="i2">burrowing of, i. 27.</p> + <p><span class="sc">Woodbury</span>, Mr., crossing of the Ligurian and common hive bees, i. 299, ii. <a href="#page126">126</a>;</p> + <p class="i2">variability of bees, i. 298.</p> + <p><span class="sc">Woodward</span>, S. P., on Arctic Mollusca, ii. <a href="#page256">256</a>.</p> + <p><span class="sc">Wood</span>, Willoughby, on Mr. Bates' cattle, ii. <a href="#page118">118</a>.</p> + <p><span class="sc">Wooler</span>, W. A., on the young of the Himalayan rabbit, i. 109;</p> + <p class="i2">persistency of the coloured calyx in a crossed Polyanthus, i. 365.</p> + <p><span class="sc">Worrara</span> poison, ii. <a href="#page380">380</a>.</p> + <p><span class="sc">Wounds</span>, healing of, ii. <a href="#page294">294</a>.</p> + <p><span class="sc">Wright</span>, J., production of crippled calves by shorthorned cattle, ii. <a href="#page118">118</a>;</p> + <p class="i2">on selection in cattle, ii. <a href="#page194">194</a>;</p> + <p class="i2">effect of close interbreeding on pigs, ii. <a href="#page121">121</a>-<a href="#page122">122</a>;</p> + <p class="i2">deterioration of game cocks by close interbreeding, ii. <a href="#page124">124</a>.</p> + <p><span class="sc">Wright</span>, Strethill, on the development of the hydroida, ii. <a href="#page368">368</a>.</p> + <p><span class="sc">Wyman</span>, Dr., on Niata cattle, and on a similar malformation in the codfish, i. 89;</p> + <p class="i2">on Virginian pigs, ii. <a href="#page227">227</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Xenophon</span>, on the colours of hunting dogs, ii. <a href="#page209">209</a>.</p> + <p><span class="sc">Ximenes</span>, Cardinal, regulations for the selection of rams, ii. <a href="#page204">204</a>.</p> + </div> + + <div class="stanza"> + <p>"<span class="sc">Yahoo</span>," the name of the pigeon in Persia, i. 155.</p> + <p><span class="sc">Yaks</span>, domestication of, i. 82;</p> + <p class="i2">selection of white-tailed, ii. <a href="#page206">206</a>, <a href="#page209">209</a>.</p> +<!-- Page 486 --><span class="pagenum"><a name="page486"></a>{486}</span> + <p><span class="sc">Yam</span>, development of axillary bulbs in the, ii. <a href="#page169">169</a>.</p> + <p><span class="sc">Yarrell</span>, Mr., deficiency of teeth in hairless dogs, i. 34, ii. <a href="#page326">326</a>;</p> + <p class="i2">on ducks, i. 279, ii. <a href="#page262">262</a>;</p> + <p class="i2">characters of domestic goose, resembling those of <i>Anser albifrons</i>, i. 288;</p> + <p class="i2">whiteness of ganders, i. 288;</p> + <p class="i2">variations in goldfish, i. 296-297;</p> + <p class="i2">assumption of male plumage by the hen-pheasant, ii. <a href="#page51">51</a>;</p> + <p class="i2">effect of castration upon the cock, ii. <a href="#page51">51</a>-<a href="#page52">52</a>;</p> + <p class="i2">breeding of the skylark in captivity, ii. <a href="#page154">154</a>;</p> + <p class="i2">plumage of the male linnet in confinement, ii. <a href="#page158">158</a>;</p> + <p class="i2">on the dingo, ii. <a href="#page263">263</a>.</p> + <p><span class="sc">Yellow</span> fever, in Mexico, ii. <a href="#page276">276</a>.</p> + <p><span class="sc">Yew</span>, fastigate, ii. <a href="#page241">241</a>.</p> + <p><span class="sc">Yew</span>, Irish, hardy in New York, ii. <a href="#page309">309</a>.</p> + <p><span class="sc">Yew</span>, weeping, i. 361;</p> + <p class="i2">propagation of, by seed, ii. <a href="#page18">18</a>-<a href="#page19">19</a>.</p> + <p><span class="sc">Yolk</span>, variations of, in the eggs of ducks, i. 281.</p> + <p><span class="sc">Youatt</span>, Mr., history of the dog, i. 16-17;</p> + <p class="i2">variations of the pulse in breeds of dogs, i. 35;</p> + <p class="i2">liability to disease in dogs, i. 35, ii. <a href="#page227">227</a>;</p> + <p class="i2">inheritance of goître in dogs, ii. <a href="#page10">10</a>;</p> + <p class="i2">on the greyhound, i. 34, 41;</p> + <p class="i2">on King Charles' spaniels, i. 41;</p> + <p class="i2">on the setter, i. 41;</p> + <p class="i2">on breeds of horses, i. 49;</p> + <p class="i2">variation in the number of ribs in the horse, i. 50;</p> + <p class="i2">inheritance of diseases in the horse, ii. <a href="#page10">10</a>, <a href="#page11">11</a>;</p> + <p class="i2">introduction of Eastern blood into English horses, ii. <a href="#page212">212</a>-<a href="#page213">213</a>;</p> + <p class="i2">on white Welsh cattle, i. 85, ii. <a href="#page209">209</a>;</p> + <p class="i2">improvement of British breeds of cattle, i. 93;</p> + <p class="i2">rudiments of horns in young hornless cattle, ii. <a href="#page55">55</a>, <a href="#page315">315</a>;</p> + <p class="i2">on crossed cattle, ii. <a href="#page104">104</a>, <a href="#page119">119</a>;</p> + <p class="i2">on Bakewell's long-horned cattle, ii. <a href="#page118">118</a>;</p> + <p class="i2">selection of qualities in cattle, ii. <a href="#page196">196</a>;</p> + <p class="i2">degeneration of cattle by neglect, ii. <a href="#page239">239</a>;</p> + <p class="i2">on the skull in hornless cattle, ii. <a href="#page333">333</a>;</p> + <p class="i2">disease of white parts of cattle, ii. <a href="#page337">337</a>;</p> + <p class="i2">displacement of long-horned by short-horned cattle, ii. <a href="#page426">426</a>;</p> + <p class="i2">on Angola sheep, i. 95;</p> + <p class="i2">on the fleece of sheep, i. 99;</p> + <p class="i2">correlation of horns and fleece in sheep, i. 95;</p> + <p class="i2">adaptation of breeds of sheep to climate and pasture, i. 96;</p> + <p class="i2">horns of Wallachian sheep, i. 96;</p> + <p class="i2">exotic sheep in the Zoological Gardens, i. 96-97, ii. <a href="#page305">305</a>;</p> + <p class="i2">occurrence of horns in hornless breeds of sheep, ii. <a href="#page30">30</a>;</p> + <p class="i2">on the colour of sheep, ii. <a href="#page30">30</a>;</p> + <p class="i2">on interbreeding sheep, ii. <a href="#page120">120</a>;</p> + <p class="i2">on Merino rams in Germany, ii. <a href="#page196">196</a>;</p> + <p class="i2">effect of unconscious selection on sheep, ii. <a href="#page213">213</a>;</p> + <p class="i2">reversion of Leicester sheep on the Lammermuir Hills, ii. <a href="#page224">224</a>;</p> + <p class="i2">on many-horned sheep, ii. <a href="#page326">326</a>;</p> + <p class="i2">reduction of bone in sheep, ii. <a href="#page242">242</a>;</p> + <p class="i2">persistency of character in breeds of animals in mountainous countries, ii. <a href="#page64">64</a>;</p> + <p class="i2">on interbreeding, ii. <a href="#page116">116</a>;</p> + <p class="i2">on the power of selection, ii. <a href="#page194">194</a>-<a href="#page195">195</a>;</p> + <p class="i2">slowness of production of breeds, ii. <a href="#page244">244</a>;</p> + <p class="i2">passages in the Bible relating to the breeding of animals, ii. <a href="#page201">201</a>-<a href="#page202">202</a>.</p> + <p><span class="sc">Young</span>, J., on the Belgian rabbit, i. 106.</p> + <p><span class="sc">Yule</span>, Capt., on a Burmese hairy family, ii. <a href="#page77">77</a>, <a href="#page327">327</a>.</p> + </div> + + <div class="stanza"> + <p><span class="sc">Zambesi</span>, striped young pigs on the, i. 77.</p> + <p><span class="sc">Zambos</span>, character of the, ii. <a href="#page47">47</a>.</p> + <p><span class="sc">Zano</span>, J. G., introduction of rabbits into Porto Santo by, i. 112.</p> + <p><i>Zea Mays</i>, i. 320.</p> + <p><span class="sc">Zebu</span>, i. 79;</p> + <p class="i2">domestication of the, i. 82;</p> + <p class="i2">fertile crossing of, with European cattle, i. 83, ii. <a href="#page110">110</a>.</p> + <p><span class="sc">Zebra</span>, hybrids of, with the ass and mare, ii. <a href="#page42">42</a>.</p> + <p><i>Zephyranthes candida</i>, ii. <a href="#page164">164</a>.</p> + <p><i>Zinnia</i>, cultivation of, ii. <a href="#page261">261</a>.</p> + <p><span class="sc">Zollinger</span> on Malayan penguin ducks, i. 280.</p> + <p><span class="sc">Zoospore</span>, division of, in Algæ, ii. <a href="#page378">378</a>.</p> + <p>"<span class="sc">Zopf-Taube</span>," i. 154.</p> + </div> + </div> + +<p class="cenhead">THE END.</p> + +<p class="cenhead"><span class="scac">LONDON: PRINTED BY W. CLOWES AND SONS, DUKE STREET, STAMFORD STREET, AND CHARING CROSS.</span></p> + +<hr class="full" /> + +<h2>NOTES</h2> + +<div class="note"> + <p><a name="Nt_1" href="#NtA_1">[1]</a> 'Medical Notes and Reflections,' + 3rd edit., 1855, p. 267.</p> + + <p><a name="Nt_2" href="#NtA_2">[2]</a> Mr. Buckle, in his grand work on + 'Civilisation,' expresses doubts on the subject owing to the want of + statistics. <i>See</i> also Mr. Bowen, Professor of Moral Philosophy, in + 'Proc. American Acad. of Sciences,' vol. v. p. 102</p> + + <p><a name="Nt_3" href="#NtA_3">[3]</a> For greyhounds, <i>see</i> Low's + 'Domest. Animals of the British Islands,' 1845, p. 721. For game-fowls, + <i>see</i> 'The Poultry Book,' by Mr. Tegetmeier, 1866, p. 123. For pigs, + <i>see</i> Mr. Sidney's edit. of 'Youatt on the Pig,' 1860, pp. 11, + 22.</p> + + <p><a name="Nt_4" href="#NtA_4">[4]</a> 'The Stud Farm,' by Cecil, p. + 39.</p> + + <p><a name="Nt_5" href="#NtA_5">[5]</a> 'Philosophical Transactions,' + 1755, p. 23. I have seen only second-hand accounts of the two grandsons. + Mr. Sedgwick, in a paper to which I shall hereafter often refer, states + that <i>four</i> generations were affected, and in each the males + alone.</p> + + <p><a name="Nt_6" href="#NtA_6">[6]</a> Barbara Van Beck, figured, as I + am informed by the Rev. W. D. Fox, in Woodburn's 'Gallery of Rare + Portraits,' 1816, vol. ii.</p> + + <p><a name="Nt_7" href="#NtA_7">[7]</a> 'Proc. Zoolog. Soc.,' 1833, p. + 16</p> + + <p><a name="Nt_8" href="#NtA_8">[8]</a> Hofacker, 'Ueber die + Eigenschaften,' &c., 1828, s. 34. Report by Pariset in 'Comptes + Rendus,' 1847, p. 592.</p> + + <p><a name="Nt_9" href="#NtA_9">[9]</a> Hunter, as quoted in Harlan's + 'Med. Researches,' p. 530. Sir A. Carlisle, 'Phil. Transact.,' 1814, p. + 94.</p> + + <p><a name="Nt_10" href="#NtA_10">[10]</a> Girou de Buzareignues, 'De la + Génération,' p. 282.</p> + + <p><a name="Nt_11" href="#NtA_11">[11]</a> 'Macmillan's Magazine,' July + and August, 1865.</p> + + <p><a name="Nt_12" href="#NtA_12">[12]</a> The works which I have read + and found most useful are Dr. Prosper Lucas's great work, 'Traité de + l'Hérédité Naturelle,' 1847. Mr. W. Sedgwick, in 'British and Foreign + Medico-Chirurg. Review,' April and July, 1861, and April and July, 1863: + Dr. Garrod on Gout is quoted in these articles. Sir Henry Holland, + 'Medical Notes and Reflections,' 3rd edit., 1855. Piorry, 'De l'Hérédité + dans les Maladies,' 1840. Adams, 'A Philosophical Treatise on Hereditary + Peculiarities,' 2nd edit., 1815. Essay on 'Hereditary Diseases,' by Dr. + J. Steinan, 1843. <i>See</i> Paget, in 'Medical Times,' 1857, p. 192, on + the Inheritance of Cancer; Dr. Gould, in 'Proc. of American Acad. of + Sciences,' Nov. 8, 1853, gives a curious case of hereditary bleeding in + four generations. Harlan, 'Medical Researches,' p. 593.</p> + + <p><a name="Nt_13" href="#NtA_13">[13]</a> Marshall, quoted by Youatt in + his work on Cattle, p. 284.</p> + + <p><a name="Nt_14" href="#NtA_14">[14]</a> 'Philosoph. Transact.,' 1814, + p. 94.</p> + + <p><a name="Nt_15" href="#NtA_15">[15]</a> 'Medical Notes and + Reflections,' 3rd edit., p. 33.</p> + + <p><a name="Nt_16" href="#NtA_16">[16]</a> This affection, as I hear from + Mr. Bowman, has been ably described and spoken of as hereditary by Dr. + Dondera, of Utrecht, whose work was published in English by the Sydenham + Society in 1864.</p> + + <p><a name="Nt_17" href="#NtA_17">[17]</a> Quoted by Mr. Herbert Spencer, + 'Principles of Biology,' vol. i. p. 244.</p> + + <p><a name="Nt_18" href="#NtA_18">[18]</a> 'British and Foreign + Medico-Chirurg. Review, 'April, 1861, p. 482-6; 'l'Héréd. Nat.,' tom. i. + pp. 391-408.</p> + + <p><a name="Nt_19" href="#NtA_19">[19]</a> Dr. Osborne, Pres. of Royal + College of Phys. in Ireland, published this case in the 'Dublin Medical + Journal' for 1835.</p> + + <p><a name="Nt_20" href="#NtA_20">[20]</a> These various statements are + taken from the following works and papers:—Youatt on 'The Horse,' + pp. 35, 220. Lawrence, 'The Horse,' p. 30. Karkeek, in an excellent paper + in 'Gard. Chronicle,' 1853, p. 92. Mr. Burke, in 'Journal of R. Agricul. + Soc. of England,' vol. v. p. 511. 'Encyclop. of Rural Sports,' p. 279. + Girou de Buzareignues, 'Philosoph. Phys.,' p. 215. <i>See</i> following + papers in 'The Veterinary:' Roberts, in vol. ii. p. 144; M. Marrimpoey, + vol. ii. p. 387; Mr. Karkeek, vol. iv. p. 5; Youatt on Goître in Dogs, + vol. v. p. 483; Youatt, in vol. vi. pp. 66, 348, 412; M. Bernard, vol. + xi. p. 539; Dr. Samesreuther, on Cattle, in vol. xii. p. 181; Percivall, + in vol. xiii. p. 47. With respect to blindness in horses, <i>see</i> also + a whole row of authorities in Dr. P. Lucas's great work, tom. i. p. 399. + Mr. Baker, in 'The Veterinary,' vol. xiii. p. 721, gives a strong case of + hereditary imperfect vision and of jibbing.</p> + + <p><a name="Nt_21" href="#NtA_21">[21]</a> Knight on 'The Culture of the + Apple and Pear,' p. 31. Lindley's 'Horticulture,' p. 180.</p> + + <p><a name="Nt_22" href="#NtA_22">[22]</a> These statements are taken + from the following works in order:—Youatt on 'The Horse,' p. 48; + Mr. Darvill, in 'The Veterinary,' vol. viii. p. 50. With respect to + Robson, <i>see</i> 'The Veterinary,' vol. iii. p. 580; Mr. Lawrence on + 'The Horse,' 1829, p. 9; 'The Stud Farm,' by Cecil, 1851; Baron Cameronn, + quoted in 'The Veterinary,' vol x. p. 500.</p> + + <p><a name="Nt_23" href="#NtA_23">[23]</a> 'Recreations in Agriculture + and Nat. Hist.,' vol. i. p. 68.</p> + + <p><a name="Nt_24" href="#NtA_24">[24]</a> 'Ueber die Eigenschaften,' + &c., 1828, s. 107.</p> + + <p><a name="Nt_25" href="#NtA_25">[25]</a> Bronn's 'Geschichte der + Natur,' band ii. s. 132.</p> + + <p><a name="Nt_26" href="#NtA_26">[26]</a> Vrolik has discussed this + point at full length in a work published in Dutch, from which Mr. Paget + has kindly translated for me passages. <i>See</i>, also, Isidore Geoffroy + St. Hilaire's 'Hist. des Anomalies,' 1832, tom. i. p. 684.</p> + + <p><a name="Nt_27" href="#NtA_27">[27]</a> 'Edinburgh New Phil. Journal,' + July, 1863.</p> + + <p><a name="Nt_28" href="#NtA_28">[28]</a> Some great anatomists, as + Cuvier and Meckel, believe that the tubercle one side of the hinder foot + of the tailless Batrachians represents a sixth digit. Certainly, when the + hinder foot of a toad, as soon as it first sprouts from the tadpole, is + dissected, the partially ossified cartilage of this tubercle resembles + under the microscope, in a remarkable manner, a digit. But the highest + authority on such subjects, Gegenbaur (Untersuchung. zur vergleich. anat. + der Wirbelthiere: Carpus et Tarsus, 1864, s. 63), concludes that this + resemblance is not real, only superficial.</p> + + <p><a name="Nt_29" href="#NtA_29">[29]</a> For these several statements, + <i>see</i> Dr. Struthers, in work cited, especially on intermissions in + the line of descent. Prof. Huxley, 'Lectures on our Knowledge of Organic + Nature,' 1863, p. 97. With respect to inheritance, <i>see</i> Dr. Prosper + Lucas, 'L'Hérédité Nat.,' tom. i. p. 325. Isid. Geoffroy, 'Anom.,' tom. + i. p. 701. Sir A. Carlisle, in 'Phil. Transact.,' 1814, p. 94. A. Walker, + on 'Intermarriage,' 1838, p. 140, gives a case of five generations; as + does Mr. Sedgwick, in 'Brit. and Foreign Medico-Chirurg. Review,' April, + 1863, p. 462. On the inheritance of other anomalies in the extremities, + <i>see</i> Dr. H. Dobell, in vol. xlvi. of 'Medico-Chirurg. + Transactions,' 1863; also Mr. Sedgwick, in op. cit., April, 1863, p. 460. + With respect to additional digits in the negro, <i>see</i> Prichard, + 'Physical History of Mankind.' Dr. Dieffenbach ('Journ. Royal Geograph. + Soc.,' 1841, p. 208) says this anomaly is not uncommon with the + Polynesians of the Chatham Islands.</p> + + <p><a name="Nt_30" href="#NtA_30">[30]</a> 'The Poultry Chronicle,' 1854, + p. 559.</p> + + <p><a name="Nt_31" href="#NtA_31">[31]</a> The statements in this + paragraph are taken from Isidore Geoffroy St. Hilaire, 'Hist. des + Anomalies,' tom. i. pp. 688-693.</p> + + <p><a name="Nt_32" href="#NtA_32">[32]</a> As quoted by Carpenter, + 'Princ. of Comp. Physiology,' 1854, p. 480.</p> + + <p><a name="Nt_33" href="#NtA_33">[33]</a> Müller's 'Phys.,' Eng. + translat., vol. i. 1838, p. 407. A thrush, however, was exhibited before + the British Association at Hull, in 1853, which had lost its tarsus, and + this member, it was asserted, had been thrice reproduced: I presume it + was lost each time by disease.</p> + + <p><a name="Nt_34" href="#NtA_34">[34]</a> 'Monthly Journal of Medical + Science,' Edinburgh, 1848, new series, vol. ii. p. 890.</p> + + <p><a name="Nt_35" href="#NtA_35">[35]</a> 'An Essay on Animal + Reproduction,' trans. by Dr. Maty, 1769, p. 79.</p> + + <p><a name="Nt_36" href="#NtA_36">[36]</a> Bonnet, 'Œuvres d'Hist. + Nat.,' tom. v., part i., 4to. edit., 1781, pp. 343, 350, 353.</p> + + <p><a name="Nt_37" href="#NtA_37">[37]</a> So with insects, the larvæ + reproduce lost limbs, but, except in one order, the mature insect has no + such power. But the Myriapoda, which apparently represent the larvæ of + true insects, have, as Newport has shown, this power until their last + moult. <i>See</i> an excellent discussion on this whole subject by Dr. + Carpenter in his 'Princ. Comp. Phys.,' 1854, p. 479.</p> + + <p><a name="Nt_38" href="#NtA_38">[38]</a> Dr. Günther, in Owen's + 'Anatomy of Vertebrates,' vol. i., 1866, p. 567. Spallanzani has made + similar observations.</p> + + <p><a name="Nt_39" href="#NtA_39">[39]</a> 'On the Anatomy of + Vertebrates,' 1866, p. 170: with respect to the pectoral fins of fishes, + pp. 166-168.</p> + + <p><a name="Nt_40" href="#NtA_40">[40]</a> 'Medical Notes and + Reflections,' 1839, pp. 24, 34. <i>See</i>, also, Dr. P. Lucas, 'l'Héréd. + Nat.,' tom. ii. p. 33.</p> + + <p><a name="Nt_41" href="#NtA_41">[41]</a> 'Du Danger des Mariages + Consanguins,' 2nd edit., 1862, p. 103.</p> + + <p><a name="Nt_42" href="#NtA_42">[42]</a> 'British and Foreign + Medico-Chirurg. Review,' July, 1863, pp. 183, 189.</p> + + <p><a name="Nt_43" href="#NtA_43">[43]</a> Verlot, 'La Production des + Variétés,' 1865, p. 32.</p> + + <p><a name="Nt_44" href="#NtA_44">[44]</a> Loudon's 'Gard. Mag.,' vol. + xii., 1836, p. 368.</p> + + <p><a name="Nt_45" href="#NtA_45">[45]</a> Verlot, 'La Product. des + Variétés,' 1865, p. 94.</p> + + <p><a name="Nt_46" href="#NtA_46">[46]</a> Bronn's 'Geschichte der + Natur,' b. ii. s. 121.</p> + + <p><a name="Nt_47" href="#NtA_47">[47]</a> Rev. W. A. Leighton, 'Flora of + Shropshire,' p. 497; and Charlesworth's 'Mag. of Nat. Hist.,' vol. i, + 1837, p. 30.</p> + + <p><a name="Nt_48" href="#NtA_48">[48]</a> Verlot, op. cit., p. 93.</p> + + <p><a name="Nt_49" href="#NtA_49">[49]</a> For these several statements, + <i>see</i> Loudon's 'Gard. Magazine,' vol. x., 1834, pp. 408, 180; and + vol. ix., 1833, p. 597.</p> + + <p><a name="Nt_50" href="#NtA_50">[50]</a> These statements are taken + from Alph. De Candolle, 'Bot. Géograph.,' p. 1083.</p> + + <p><a name="Nt_51" href="#NtA_51">[51]</a> Verlot, op. cit., p. 38.</p> + + <p><a name="Nt_52" href="#NtA_52">[52]</a> Op. cit., p. 59.</p> + + <p><a name="Nt_53" href="#NtA_53">[53]</a> Alph. De Candolle, 'Géograph. + Bot.,' p. 1082.</p> + + <p><a name="Nt_54" href="#NtA_54">[54]</a> <i>See</i> 'Cottage Gardener,' + April 10, 1860, p. 18, and Sept. 10, 1861, p. 456; 'Gard. Chron.,' 1845, + p. 102.</p> + + <p><a name="Nt_55" href="#NtA_55">[55]</a> Darwin, in 'Journal of Proc. + Linn. Soc. Bot.,' 1862, p. 94.</p> + + <p><a name="Nt_56" href="#NtA_56">[56]</a> Hofacker, 'Ueber die + Eigenschaften,' &c., s. 10.</p> + + <p><a name="Nt_57" href="#NtA_57">[57]</a> Bechstein, 'Naturgesch. + Deutschlands,' b. iv. s. 462. Mr. Brent, a great breeder of canaries, + informs me that he believes that these statements are correct.</p> + + <p><a name="Nt_58" href="#NtA_58">[58]</a> 'The Poultry Book,' by W. B. + Tegetmeier, 1866, p. 245.</p> + + <p><a name="Nt_59" href="#NtA_59">[59]</a> 'British and Foreign + Med.-Chirurg. Review,' July, 1861, pp. 200-204. Mr. Sedgwick has given + such full details on this subject, with ample references, that I need + refer to no other authorities.</p> + + <p><a name="Nt_60" href="#NtA_60">[60]</a> 'De l'Espèce,' tom. ii., 1859, + p. 299.</p> + + <p><a name="Nt_61" href="#NtA_61">[61]</a> 'Philosoph. Magazine,' vol. + iv., 1799, p. 5.</p> + + <p><a name="Nt_62" href="#NtA_62">[62]</a> This last case is quoted by + Mr. Sedgwick in 'British and Foreign Medico-Chirurg. Review,' April, + 1861, p. 484. For Blumenbach, <i>see</i> above-cited paper. <i>See</i>, + also, Dr. P. Lucas, 'Traité de l'Héréd. Nat.,' tom. ii. p. 492. Also + 'Transact. Lin. Soc.,' vol. ix. p. 323. Some curious cases are given by + Mr. Baker in 'The Veterinary,' vol. xiii. p. 723. Another curious case is + given in the 'Annales des Scienc. Nat.,' 1st series, tom. xi. p. 324.</p> + + <p><a name="Nt_63" href="#NtA_63">[63]</a> 'Proc. Royal Soc.,' vol. x. p. + 297.</p> + + <p><a name="Nt_64" href="#NtA_64">[64]</a> Mr. Sproule, in 'British + Medical Journal,' April 18, 1863.</p> + + <p><a name="Nt_65" href="#NtA_65">[65]</a> Downing, 'Fruits of America,' + p. 5; Sageret, 'Pom. Phys.,' pp. 43, 72.</p> + + <p><a name="Nt_66" href="#NtA_66">[66]</a> Youatt on Sheep, pp. 20, 234. + The same fact of loose horns occasionally appearing in hornless breeds + has been observed in Germany: Bechstein, 'Naturgesch. Deutschlands,' b. + i. s. 362.</p> + + <p><a name="Nt_67" href="#NtA_67">[67]</a> Youatt on Cattle, pp. 155, + 174.</p> + + <p><a name="Nt_68" href="#NtA_68">[68]</a> Youatt on Sheep, 1838, pp. 17, + 145.</p> + + <p><a name="Nt_69" href="#NtA_69">[69]</a> I have been informed of this + fact through the Rev. W. D. Fox, on the excellent authority of Mr. + Wilmot: <i>see</i>, also, remarks on this subject in an original article + in the 'Quarterly Review,' 1849, p. 395.</p> + + <p><a name="Nt_70" href="#NtA_70">[70]</a> Youatt, pp. 19, 234.</p> + + <p><a name="Nt_71" href="#NtA_71">[71]</a> 'The Poultry Book,' by Mr. + Tegetmeier, 1866, p. 231.</p> + + <p><a name="Nt_72" href="#NtA_72">[72]</a> Loudon's 'Gard. Mag.,' vol. + x., 1834, p. 396: a nurseryman, with much experience on this subject, has + likewise assured me that this sometimes occurs.</p> + + <p><a name="Nt_73" href="#NtA_73">[73]</a> 'Gardener's Chron.,' 1855, p. + 777.</p> + + <p><a name="Nt_74" href="#NtA_74">[74]</a> Ibid., 1862, p. 721.</p> + + <p><a name="Nt_75" href="#NtA_75">[75]</a> <i>See</i> some excellent + remarks on this subject by Mr. Wallace, 'Journal Proc. Linn. Soc.,' 1858, + vol. iii. p. 60.</p> + + <p><a name="Nt_76" href="#NtA_76">[76]</a> Dureau de la Malle, in + 'Comptes Rendus,' tom. xli., 1855, p. 807. From the statements above + given, the author concludes that the wild pigs of Louisiana are not + descended from the European <i>Sus scrofa</i>.</p> + + <p><a name="Nt_77" href="#NtA_77">[77]</a> Capt. W. Allen, in his + 'Expedition to the Niger,' states that fowls have run wild on the island + of Annobon, and have become modified in form and voice. The account is so + meagre and vague that it did not appear to me worth copying; but I now + find that Dureau de la Malle ('Comptes Rendus,' tom. xli., 1855, p. 690) + advances this as a good instance of reversion to the primitive stock, and + as confirmatory of a still more vague statement in classical times by + Varro.</p> + + <p><a name="Nt_78" href="#NtA_78">[78]</a> 'Flora of Australia,' 1859, + Introduct., p. ix.</p> + + <p><a name="Nt_79" href="#NtA_79">[79]</a> 'De l'Espèce,' tom. ii. pp. + 54, 58, 60.</p> + + <p><a name="Nt_80" href="#NtA_80">[80]</a> Mr. Sedgwick gives many + instances in the 'British and Foreign Med.-Chirurg. Review,' April and + July, 1863, pp. 448, 188.</p> + + <p><a name="Nt_81" href="#NtA_81">[81]</a> In his edit. of 'Youatt on the + Pig,' 1860, p. 27.</p> + + <p><a name="Nt_82" href="#NtA_82">[82]</a> Dr. P. Lucas, 'Héréd. Nat.,' + tom. ii. pp. 314, 892: <i>see</i> a good practical article on this + subject in 'Gard. Chronicle,' 1856, p. 620. I could add a vast number of + references, but they would be superfluous.</p> + + <p><a name="Nt_83" href="#NtA_83">[83]</a> Kölreuter gives cases in his + 'Dritte Fortsetzung,' 1766, s. 53, 59; and in his well-known 'Memoirs on + Lavatera and Jalapa.' Gärtner, 'Bastarderzeugung,' s. 437, 441, &c. + Naudin, in his 'Recherches sur l'Hybridité, Nouvelles Archives du + Muséum,' tom. i. p. 25.</p> + + <p><a name="Nt_84" href="#NtA_84">[84]</a> Quoted by Mr. Sedgwick in + 'Med.-Chirurg. Review,' April, 1861, p. 485. Dr. H. Dobell, in + 'Med.-Chirurg. Transactions,' vol. xlvi., gives an analogous case, in + which, in a large family, fingers with thickened joints were transmitted + to several members during five generations; but when the blemish once + disappeared it never reappeared.</p> + + <p><a name="Nt_85" href="#NtA_85">[85]</a> Verlot, 'Des Variétés,' 1865, + p. 63.</p> + + <p><a name="Nt_86" href="#NtA_86">[86]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 25. Alex. Braun (in his 'Rejuvenescence,' Ray Soc., + 1853, p. 315) apparently holds a similar opinion.</p> + + <p><a name="Nt_87" href="#NtA_87">[87]</a> Mr. Teebay, in 'The Poultry + Book,' by Mr. Tegetmeier, 1866, p. 72.</p> + + <p><a name="Nt_88" href="#NtA_88">[88]</a> Quoted by Hofacker, 'Ueber die + Eigenschaften,' &c., s. 98.</p> + + <p><a name="Nt_89" href="#NtA_89">[89]</a> 'Essais Hist. Nat. du + Paraguay,' tom. ii. 1801, p. 372.</p> + + <p><a name="Nt_90" href="#NtA_90">[90]</a> These facts are given on the + high authority of Mr. Hewitt, in 'The Poultry Book,' by Mr. Tegetmeier, + 1866, p. 248.</p> + + <p><a name="Nt_91" href="#NtA_91">[91]</a> 'The Poultry Book,' by + Tegetmeier, 1866, p. 97.</p> + + <p><a name="Nt_92" href="#NtA_92">[92]</a> 'Gardener's Chron. and + Agricultural Gazette,' 1866, p. 528.</p> + + <p><a name="Nt_93" href="#NtA_93">[93]</a> Ibid., 1860, p. 343.</p> + + <p><a name="Nt_94" href="#NtA_94">[94]</a> Sclater, in 'Proc. Zoolog. + Soc.,' 1862, p. 163.</p> + + <p><a name="Nt_95" href="#NtA_95">[95]</a> 'History of the Horse,' p. + 212.</p> + + <p><a name="Nt_96" href="#NtA_96">[96]</a> 'Mém. présentés par divers + Savans à l'Acad. Royale,' tom. vi. 1835, p. 338.</p> + + <p><a name="Nt_97" href="#NtA_97">[97]</a> 'Letters from Alabama,' 1859, + p. 280.</p> + + <p><a name="Nt_98" href="#NtA_98">[98]</a> 'Hist. Nat. des Mammifères,' + 1820, tom. i.</p> + + <p><a name="Nt_99" href="#NtA_99">[99]</a> 'Philosoph. Transact.,' 1821, + p. 20.</p> + + <p><a name="Nt_100" href="#NtA_100">[100]</a> Sclater, in 'Proc. Zoolog. + Soc.,' 1862, p. 163: this species is the Ghor-Khur of N.W. India, and has + often been called the Hemionus of Pallas. <i>See</i>, also, Mr. Blyth's + excellent paper in 'Journ. of Asiatic Soc. of Bengal,' vol. xxviii., + 1860, p. 229.</p> + + <p><a name="Nt_101" href="#NtA_101">[101]</a> Another species of wild + ass, the true <i>A. hemionus</i> or <i>Kiang</i>, which ordinarily has no + shoulder-stripes, is said occasionally to have them; and these, as with + the horse and ass, are sometimes double: <i>see</i> Mr. Blyth, in the + paper just quoted, and in 'Indian Sporting Review,' 1856, p. 320; and + Col. Hamilton Smith, in 'Nat. Library, Horses,' p. 318; and 'Dict. Class. + d'Hist. Nat.,' tom. iii. p. 563.</p> + + <p><a name="Nt_102" href="#NtA_102">[102]</a> Figured in the 'Gleanings + from the Knowsley Menageries,' by Dr. J. E. Gray.</p> + + <p><a name="Nt_103" href="#NtA_103">[103]</a> Cases of both Spanish and + Polish hens sitting are given in the 'Poultry Chronicle,' 1855, vol. iii. + p. 477.</p> + + <p><a name="Nt_104" href="#NtA_104">[104]</a> 'The Poultry Book,' by Mr. + Tegetmeier, 1866, pp. 119, 163. The author, who remarks on the two + negatives ('Journ. of Hort.,' 1862, p. 325), states that two broods were + raised from a Spanish cock and Silver-pencilled Hamburgh hen, neither of + which are incubators, and no less than seven out of eight hens in these + two broods "showed a perfect obstinacy in sitting." The Rev. E. S. Dixon + ('Ornamental Poultry,' 1848, p. 200) says that chickens reared from a + cross between Golden and Black Polish fowls, are "good and steady birds + to sit." Mr. B. P. Brent informs me that he raised some good sitting hens + by crossing Pencilled Hamburgh and Polish breeds. A cross-bred bird from + a Spanish non-incubating cock and Cochin incubating hen is mentioned in + the 'Poultry Chronicle,' vol. iii. p. 13, as an "exemplary mother." On + the other hand, an exceptional case is given in the 'Cottage Gardener,' + 1860, p. 388, of a hen raised from a Spanish cock and black Polish hen + which did not incubate.</p> + + <p><a name="Nt_105" href="#NtA_105">[105]</a> 'The Poultry Book,' by + Tegetmeier, 1866, pp. 165, 167.</p> + + <p><a name="Nt_106" href="#NtA_106">[106]</a> 'Natural History Review,' + 1863, April, p. 277.</p> + + <p><a name="Nt_107" href="#NtA_107">[107]</a> 'Essays on Natural + History,' p. 197.</p> + + <p><a name="Nt_108" href="#NtA_108">[108]</a> As stated by Mr. Orton, in + his 'Physiology of Breeding,' p. 12.</p> + + <p><a name="Nt_109" href="#NtA_109">[109]</a> M. E. de Selys-Longchamps + refers ('Bulletin Acad. Roy. de Bruxelles,' tom. xii. No. 10) to more + than seven of these hybrids shot in Switzerland and France. M. Deby + asserts ('Zoologist,' vol. v., 1845-46, p. 1254) that several have been + shot in various parts of Belgium and Northern France. Audubon + ('Ornitholog. Biography,' vol. iii. p. 168), speaking of these hybrids, + says that, in North America, they "now and then wander off and become + quite wild."</p> + + <p><a name="Nt_110" href="#NtA_110">[110]</a> 'Journal of Researches,' + 1845, p. 71.</p> + + <p><a name="Nt_111" href="#NtA_111">[111]</a> 'Expedition to the + Zambesi,' 1865, pp. 25, 150.</p> + + <p><a name="Nt_112" href="#NtA_112">[112]</a> Dr. P. Broca, on 'Hybridity + in the Genus Homo,' Eng. translat., 1864, p. 39.</p> + + <p><a name="Nt_113" href="#NtA_113">[113]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 151.</p> + + <p><a name="Nt_114" href="#NtA_114">[114]</a> 'Bastarderzeugung,' s. 582, + 438, &c.</p> + + <p><a name="Nt_115" href="#NtA_115">[115]</a> 'Die Bastardbefruchtung ... + der Weiden,' 1865, s. 23. For Gärtner's remarks on this head, <i>see</i> + 'Bastarderzeugung,' s. 474, 582.</p> + + <p><a name="Nt_116" href="#NtA_116">[116]</a> Yarrell, 'Phil. Transact.,' + 1827, p. 268; Dr. Hamilton, in 'Proc. Zoolog. Soc.,' 1862, p. 23.</p> + + <p><a name="Nt_117" href="#NtA_117">[117]</a> 'Archiv. Skand. Beiträge + zur Naturgesch.,' viii. s. 397-413.</p> + + <p><a name="Nt_118" href="#NtA_118">[118]</a> In his 'Essays on Nat. + Hist.,' 1838. Mr. Hewitt gives analogous cases with hen-pheasants in + 'Journal of Horticulture,' July 12, 1864, p. 37. Isidore Geoffroy Saint + Hilaire, in his 'Essais de Zoolog. Gén.' (suites à Buffon, 1842, pp. + 496-513), has collected such cases in ten different kinds of birds. It + appears that Aristotle was well aware of the change in mental disposition + in old hens. The case of the female deer acquiring horns is given at p. + 513.</p> + + <p><a name="Nt_119" href="#NtA_119">[119]</a> 'Cottage Gardener,' 1860, + p. 379.</p> + + <p><a name="Nt_120" href="#NtA_120">[120]</a> 'Art de faire Eclorre,' + &c., 1749, tom. ii. p. 8.</p> + + <p><a name="Nt_121" href="#NtA_121">[121]</a> Sir H. Holland, 'Medical + Notes and Reflections,' 3rd edit., 1855, p. 31.</p> + + <p><a name="Nt_122" href="#NtA_122">[122]</a> Prof. Thomson on + Steenstrup's Views on the Obliquity of Flounders: 'Annals and Mag. of + Nat. Hist.,' May, 1865, p. 361.</p> + + <p><a name="Nt_123" href="#NtA_123">[123]</a> Dr. E. von Martens, in + 'Annals and Mag. of Nat. Hist.,' March, 1866, p. 209.</p> + + <p><a name="Nt_124" href="#NtA_124">[124]</a> Darwin, 'Balanidæ,' Ray + Soc., 1854, p. 499: <i>see</i> also the appended remarks on the + apparently capricious development of the thoracic limbs on the right and + left sides in the higher crustaceans.</p> + + <p><a name="Nt_125" href="#NtA_125">[125]</a> Mormodes ignea: Darwin, + 'Fertilization of Orchids,' 1862, p. 251.</p> + + <p><a name="Nt_126" href="#NtA_126">[126]</a> 'Journal of Horticulture,' + July, 1864, p. 38. I have had the opportunity of examining these + remarkable feathers through the kindness of Mr. Tegetmeier.</p> + + <p><a name="Nt_127" href="#NtA_127">[127]</a> 'The Poultry Book,' by Mr. + Tegetmeier, 1866, p. 241.</p> + + <p><a name="Nt_128" href="#NtA_128">[128]</a> Carl Vogt, 'Lectures on + Man,' Eng. translat., 1864, p. 411.</p> + + <p><a name="Nt_129" href="#NtA_129">[129]</a> On Cattle, p. 174.</p> + + <p><a name="Nt_130" href="#NtA_130">[130]</a> Isid. Geoffroy St. Hilaire, + 'Des Anomalies,' tom. iii. p. 353. With respect to the mammæ in women, + <i>see</i> tom. i. p. 710.</p> + + <p><a name="Nt_131" href="#NtA_131">[131]</a> 'Natural Hist. Review,' + April, 1863, p. 258. <i>See</i> also his Lecture, Royal Institution, + March 16, 1860. On same subject, <i>see</i> Moquin-Tandon, 'Eléments de + Tératologie,' 1841, pp. 184, 352.</p> + + <p><a name="Nt_132" href="#NtA_132">[132]</a> Verlot, 'Des Variétés,' + 1865, p. 89; Naudin, 'Nouvelles Archives du Muséum,' tom. i. p. 137.</p> + + <p><a name="Nt_133" href="#NtA_133">[133]</a> In his discussion on some + curious peloric calceolarias, quoted in 'Journal of Horticulture,' Feb. + 24, 1863, p. 152.</p> + + <p><a name="Nt_134" href="#NtA_134">[134]</a> For other cases of six + divisions in peloric flowers of the Labiatæ and Scrophulariaceæ, + <i>see</i> Moquin-Tandon, 'Tératologie,' p. 192.</p> + + <p><a name="Nt_135" href="#NtA_135">[135]</a> Moquin-Tandon, + 'Tératologie,' p. 186.</p> + + <p><a name="Nt_136" href="#NtA_136">[136]</a> <i>See</i> Youatt on + Cattle, pp. 92, 69, 78, 88, 163: also Youatt on Sheep, p. 325. Also Dr. + Lucas, 'L'Héréd. Nat.,' tom. ii. p. 310.</p> + + <p><a name="Nt_137" href="#NtA_137">[137]</a> 'Héréd. Nat.,' tom. ii. pp. + 112-120.</p> + + <p><a name="Nt_138" href="#NtA_138">[138]</a> Sir H. Holland, 'Chapters + on Mental Physiology,' 1852, p. 234.</p> + + <p><a name="Nt_139" href="#NtA_139">[139]</a> 'Gardener's Chronicle,' + 1860, p. 270.</p> + + <p><a name="Nt_140" href="#NtA_140">[140]</a> Mr. N. H. Smith, + Observations on Breeding, quoted in 'Encyclop. of Rural Sports,' p. + 278.</p> + + <p><a name="Nt_141" href="#NtA_141">[141]</a> Quoted by Bronn, + 'Geschichte der Natur,' b. ii. s. 170. <i>See</i> Sturm, 'Ueber Racen,' + 1825, s. 104-107. For the niata cattle, <i>see</i> my 'Journal of + Researches,' 1845, p. 146.</p> + + <p><a name="Nt_142" href="#NtA_142">[142]</a> Lucas, 'l'Hérédité Nat.,' + tom. ii. p. 112.</p> + + <p><a name="Nt_143" href="#NtA_143">[143]</a> Mr. Orton, 'Physiology of + Breeding,' 1855, p. 9.</p> + + <p><a name="Nt_144" href="#NtA_144">[144]</a> Boitard and Corbié, 'Les + Pigeons,' 1824, p. 224.</p> + + <p><a name="Nt_145" href="#NtA_145">[145]</a> 'Les Pigeons, pp. 168, + 198.</p> + + <p><a name="Nt_146" href="#NtA_146">[146]</a> 'Das Ganze,' &c., 1837, + s. 39.</p> + + <p><a name="Nt_147" href="#NtA_147">[147]</a> 'The Pigeon Book,' p. + 46.</p> + + <p><a name="Nt_148" href="#NtA_148">[148]</a> 'Physiology of Breeding,' + p.22; Mr. Hewitt, in 'The Poultry Book,' by Tegetmeier, 1866, p. 224.</p> + + <p><a name="Nt_149" href="#NtA_149">[149]</a> Boitard and Corbié, 'Les + Pigeons,' 1824, p. 226.</p> + + <p><a name="Nt_150" href="#NtA_150">[150]</a> 'Bastarderzeugung,' s. 256, + 290, &c. Naudin ('Nouvelles Archives du Muséum,' tom. i. p. 149) + gives a striking instance of prepotency in <i>Datura stramonium</i> when + crossed with two other species.</p> + + <p><a name="Nt_151" href="#NtA_151">[151]</a> Flourens, 'Longévité + Humaine,' p. 144, on crossed jackals. With respect to the difference + between the mule and the hinny, I am aware that this has generally been + attributed to the sire and dam transmitting their characters differently; + but Colin, who has given in his 'Traité Phys. Comp.,' tom. ii. pp. + 537-539, the fullest description which I have met with of these + reciprocal hybrids, is strongly of opinion that the ass preponderates in + both crosses, but in an unequal degree. This is likewise the conclusion + of Flourens, and of Bechstein in his 'Naturgeschichte Deutschlands,' b. + i. s. 294. The tail of the hinny is much more like that of the horse than + is the tail of the mule, and this is generally accounted for by the males + of both species transmitting with greater power this part of their + structure; but a compound hybrid which I saw in the Zoological Gardens, + from a mare by a hybrid ass-zebra, closely resembled its mother in its + tail.</p> + + <p><a name="Nt_152" href="#NtA_152">[152]</a> Mr. Hewitt, who has had + such great experience in raising these hybrids, says ('Poultry Book,' by + Mr. Tegetmeier, 1866, pp. 165-167) that in all, the head was destitute of + wattles, comb, and ear-lappets; and all closely resembled the pheasant in + the shape of the tail and general contour of the body. These hybrids were + raised from hens of several breeds by a cock-pheasant; but another + hybrid, described by Mr. Hewitt, was raised from a hen-pheasant by a + silver-laced Bantam cock, and this possessed a rudimental comb and + wattles.</p> + + <p><a name="Nt_153" href="#NtA_153">[153]</a> 'L'Héréd. Nat.,' tom. ii. + book ii. ch. i.</p> + + <p><a name="Nt_154" href="#NtA_154">[154]</a> 'Bastarderzeugung,' s. + 264-266. Naudin ('Nouvelles Archives du Muséum,' tom. i. p. 148) has + arrived at a similar conclusion.</p> + + <p><a name="Nt_155" href="#NtA_155">[155]</a> 'Cottage Gardener,' 1856, + pp. 101, 137.</p> + + <p><a name="Nt_156" href="#NtA_156">[156]</a> <i>See</i> some remarks on + this head with respect to sheep by Mr. Wilson, in 'Gardener's Chronicle,' + 1863, p. 15.</p> + + <p><a name="Nt_157" href="#NtA_157">[157]</a> Verlot, 'Des Variétés,' + 1865, p. 66.</p> + + <p><a name="Nt_158" href="#NtA_158">[158]</a> Moquin-Tandon, + 'Tératologie,' p. 191.</p> + + <p><a name="Nt_159" href="#NtA_159">[159]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 137.</p> + + <p><a name="Nt_160" href="#NtA_160">[160]</a> 'L'Héréd. Nat.,' tom. ii. + pp. 137-165. <i>See</i>, also, Mr. Sedgwick's four memoirs, immediately + to be referred to.</p> + + <p><a name="Nt_161" href="#NtA_161">[161]</a> On Sexual Limitation in + Hereditary Diseases, 'Brit. and For. Med.-Chirurg. Review,' April, 1861, + p. 477; July, p. 198; April, 1863, p. 44; and July, p. 159.</p> + + <p><a name="Nt_162" href="#NtA_162">[162]</a> W. Scrope, 'Art of Deer + Stalking,' p. 354.</p> + + <p><a name="Nt_163" href="#NtA_163">[163]</a> Boitard and Corbié, 'Les + Pigeons,' p. 173; Dr. F. Chapuis, 'Le Pigeon Voyageur Belge,' 1865, p. + 87.</p> + + <p><a name="Nt_164" href="#NtA_164">[164]</a> Prichard, 'Phys. Hist. of + Mankind,' 1851, vol. i. p. 349.</p> + + <p><a name="Nt_165" href="#NtA_165">[165]</a> 'Embassy to the Court of + Ava,' vol. i. p. 320. The third generation is described by Capt. Yule in + his 'Narrative of the Mission to the Court of Ava,' 1855, p. 94.</p> + + <p><a name="Nt_166" href="#NtA_166">[166]</a> 'Das Ganze der + Taubenzucht,' 1837, s. 21, tab. i., fig. 4; s. 24, tab. iv., fig. 2.</p> + + <p><a name="Nt_167" href="#NtA_167">[167]</a> Kidd's 'Treatise on the + Canary,' p. 18.</p> + + <p><a name="Nt_168" href="#NtA_168">[168]</a> Charlesworth, 'Mag. of Nat. + Hist.,' vol. i., 1837, p. 167.</p> + + <p><a name="Nt_169" href="#NtA_169">[169]</a> Dr. Prosper Lucas, 'Héréd. + Nat.,' tom. ii. p. 713.</p> + + <p><a name="Nt_170" href="#NtA_170">[170]</a> 'L'Héréd. dans les + Maladies,' 1840, p. 135. For Hunter, <i>see</i> Harlan's 'Med. + Researches,' p. 530.</p> + + <p><a name="Nt_171" href="#NtA_171">[171]</a> 'L'Héréd. Nat.,' tom. ii. + p. 850.</p> + + <p><a name="Nt_172" href="#NtA_172">[172]</a> Sedgwick, 'Brit. and For. + Med.-Chirurg. Review,' April 1861, p. 485. I have seen three accounts, + all taken from the same original authority (which I have not been able to + consult), and all differ in the details! but as they agree in the main + facts, I have ventured to quote this case.</p> + + <p><a name="Nt_173" href="#NtA_173">[173]</a> Prosper Lucas, 'Héréd. + Nat.,' tom. i. p. 400.</p> + + <p><a name="Nt_174" href="#NtA_174">[174]</a> Sedgwick, idem, July, 1861, + p. 202.</p> + + <p><a name="Nt_175" href="#NtA_175">[175]</a> Piorry, p. 109; Prosper + Lucas, tom. ii. p. 759.</p> + + <p><a name="Nt_176" href="#NtA_176">[176]</a> Prosper Lucas, tom. ii. p. + 748.</p> + + <p><a name="Nt_177" href="#NtA_177">[177]</a> Prosper Lucas, tom. ii. pp. + 678, 700, 702; Sedgwick, idem, April, 1863, p. 449, and July, 1863, p. + 162; Dr. J. Steinan, 'Essay on Hereditary Disease,' 1843, pp. 27, 34.</p> + + <p><a name="Nt_178" href="#NtA_178">[178]</a> These cases are given by + Mr. Sedgwick, on the authority of Dr. H. Stewart, in 'Med.-Chirurg. + Review,' April, 1863, pp. 449, 477.</p> + + <p><a name="Nt_179" href="#NtA_179">[179]</a> 'Héréd. Nat.,' tom. ii. p. + 852.</p> + + <p><a name="Nt_180" href="#NtA_180">[180]</a> Communications to the Board + of Agriculture, vol. i. p. 367.</p> + + <p><a name="Nt_181" href="#NtA_181">[181]</a> 'Review of Reports, North + of England,' 1808, p. 200.</p> + + <p><a name="Nt_182" href="#NtA_182">[182]</a> 'Säugethiere von Paraguay,' + 1830, s. 212.</p> + + <p><a name="Nt_183" href="#NtA_183">[183]</a> Rengger, 'Säugethiere,' + &c., s. 154.</p> + + <p><a name="Nt_184" href="#NtA_184">[184]</a> White, 'Regular Gradation + in Man,' p. 146.</p> + + <p><a name="Nt_185" href="#NtA_185">[185]</a> Dr. W. F. Edwards, in his + 'Charactères Physiolog. des Races Humaines,' p. 23, first called + attention to this subject, and ably discussed it.</p> + + <p><a name="Nt_186" href="#NtA_186">[186]</a> Rev. D. Tyerman, and + Bennett, 'Journal of Voyages,' 1821-1829, vol. i. p. 300.</p> + + <p><a name="Nt_187" href="#NtA_187">[187]</a> Mr. S. J. Salter, 'Journal + Linn. Soc.,' vol. vi., 1862, p. 71.</p> + + <p><a name="Nt_188" href="#NtA_188">[188]</a> Sturm, 'Ueber Racen, + &c.,' 1825, s. 107. Bronn, 'Geschichte der Natur.,' b. ii. s. 170, + gives a table of the proportions of blood after successive crosses. Dr. + P. Lucas, 'l'Hérédité Nat.,' tom. ii. p. 308.</p> + + <p><a name="Nt_189" href="#NtA_189">[189]</a> 'Bastarderzeugung,' s. 463, + 470.</p> + + <p><a name="Nt_190" href="#NtA_190">[190]</a> 'Nova Acta Petrop.,' 1794, + p. 393: <i>see</i> also previous volume.</p> + + <p><a name="Nt_191" href="#NtA_191">[191]</a> As quoted in the 'True + Principles of Breeding,' by C. H. Macknight and Dr. H. Madden, 1865, p. + 11.</p> + + <p><a name="Nt_192" href="#NtA_192">[192]</a> With respect to plants, an + admirable essay on this subject (Die Geschlechter-Vertheilung bei den + Pflanzen: 1867) has lately been published by Dr. Hildebrand, who arrives + at the same general conclusions as I have done.</p> + + <p><a name="Nt_193" href="#NtA_193">[193]</a> 'Teoria della Riproduzione + Vegetal,' 1816, p. 12.</p> + + <p><a name="Nt_194" href="#NtA_194">[194]</a> Verlot, 'Des Variétés,' + 1865, p. 72.</p> + + <p><a name="Nt_195" href="#NtA_195">[195]</a> Duval-Jouve, 'Bull. Soc. + Bot. de France,' tom. x., 1863, p. 194.</p> + + <p><a name="Nt_196" href="#NtA_196">[196]</a> Extract of a letter from + Sir R. Heron, 1838, given me by Mr. Yarrell. With respect to mice, + <i>see</i> 'Annal. des Sc. Nat.,' tom. i. p. 180; and I have heard of + other similar cases. For turtle-doves, Boitard and Corbié, 'Les Pigeons,' + &c., p. 238. For the Game fowl, 'The Poultry Book,' 1866, p. 128. For + crosses of tailless fowls, <i>see</i> Bechstein, 'Naturges. Deutsch.' b. + iii. s. 403. Bronn, 'Geschichte der Natur,' b. ii. s. 170, gives + analogous facts with horses. On the hairless condition of crossed South + American dogs, <i>see</i> Rengger, 'Säugethiere von Paraguay,' s. 152: + but I saw in the Zoological Gardens mongrels, from a similar cross, which + were hairless, quite hairy, or hairy in patches, that is, piebald with + hair. For crosses of Dorking and other fowls, <i>see</i> 'Poultry + Chronicle,' vol. ii. p. 355. About the crossed pigs, extract of letter + from Sir R. Heron to Mr. Yarrell. For other cases, <i>see</i> P. Lucas, + 'Héréd. Nat.,' tom. i. p. 212.</p> + + <p><a name="Nt_197" href="#NtA_197">[197]</a> 'Internat. Hort. and Bot. + Congress of London,' 1866.</p> + + <p><a name="Nt_198" href="#NtA_198">[198]</a> 'Bastarderzeugung,' s. 307. + Kölreuter ('Dritte Fortsetszung,' s. 34, 39), however, obtained + intermediate tints from similar crosses in the genus Verbascum. With + respect to the turnips, <i>see</i> Herbert's 'Amaryllidaceæ,' 1837, p. + 370.</p> + + <p><a name="Nt_199" href="#NtA_199">[199]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 100.</p> + + <p><a name="Nt_200" href="#NtA_200">[200]</a> Richardson, 'Pigs,' 1847, + pp. 37, 42; S. Sidney's edition of 'Youatt on the Pig,' 1860, p. 3.</p> + + <p><a name="Nt_201" href="#NtA_201">[201]</a> <i>See</i> Mr. W. C. + Spooner's excellent paper on Cross-Breeding, 'Journal Royal Agricult. + Soc.,' vol. xx., part ii.: <i>see</i> also an equally good article by Mr. + Ch. Howard, in 'Gardener's Chronicle,' 1860, p. 320.</p> + + <p><a name="Nt_202" href="#NtA_202">[202]</a> 'Gardener's Chronicle,' + 1857, pp. 649, 652.</p> + + <p><a name="Nt_203" href="#NtA_203">[203]</a> 'Bulletin de la Soc. + d'Acclimat.,' 1862, tom. ix. p. 463. <i>See</i> also, for other cases, + MM. Moll and Gayot, 'Du Bœuf,' 1860, p. xxxii.</p> + + <p><a name="Nt_204" href="#NtA_204">[204]</a> 'Poultry Chronicle,' vol. + ii., 1854, p. 36.</p> + + <p><a name="Nt_205" href="#NtA_205">[205]</a> 'The Poultry Book,' by W. + B. Tegetmeier, 1866, p. 58.</p> + + <p><a name="Nt_206" href="#NtA_206">[206]</a> 'Gardener's Chronicle,' + 1852, p. 765.</p> + + <p><a name="Nt_207" href="#NtA_207">[207]</a> Spooner, in 'Journal Royal + Agricult. Soc.,' vol. xx., part ii.</p> + + <p><a name="Nt_208" href="#NtA_208">[208]</a> <i>See</i> Colin's 'Traité + de Phys. Comp. des Animaux Domestiques,' tom. ii. p. 536, where this + subject is well treated.</p> + + <p><a name="Nt_209" href="#NtA_209">[209]</a> 'Les Pigeons,' p. 37.</p> + + <p><a name="Nt_210" href="#NtA_210">[210]</a> Vol. i., 1854, p. 101.</p> + + <p><a name="Nt_211" href="#NtA_211">[211]</a> 'Cottage Gardener,' 1856, + p. 110.</p> + + <p><a name="Nt_212" href="#NtA_212">[212]</a> 'Bastarderzeugung,' s. + 553.</p> + + <p><a name="Nt_213" href="#NtA_213">[213]</a> Dr. Pigeaux, in 'Bull. Soc. + d'Acclimat.,' tom. iii., July 1866, as quoted in 'Annals and Mag. of Nat. + Hist.,' 1867, vol. xx. p. 75.</p> + + <p><a name="Nt_214" href="#NtA_214">[214]</a> 'Journal de Physiolog.,' + tom. ii., 1859, p. 385.</p> + + <p><a name="Nt_215" href="#NtA_215">[215]</a> Dec. 1863, p. 484.</p> + + <p><a name="Nt_216" href="#NtA_216">[216]</a> On the Varieties of Wheat, + p. 66.</p> + + <p><a name="Nt_217" href="#NtA_217">[217]</a> Rengger, 'Säugethiere von + Paraguay,' s. 336.</p> + + <p><a name="Nt_218" href="#NtA_218">[218]</a> <i>See</i> a memoir by MM. + Lherbette and De Quatrefages, in 'Bull. Soc. d'Acclimat.,' tom. viii., + July, 1861, p. 312.</p> + + <p><a name="Nt_219" href="#NtA_219">[219]</a> For the Norfolk sheep, + <i>see</i> Marshall's 'Rural Economy of Norfolk,' vol. ii. p. 133. + <i>See</i> Rev. L. Landt's 'Description of Faroe,' p. 66. For the ancon + sheep, <i>see</i> 'Phil. Transact.,' 1813, p. 90.</p> + + <p><a name="Nt_220" href="#NtA_220">[220]</a> White's 'Nat. Hist. of + Selbourne,' edited by Bennett, p. 39. With respect to the origin of the + dark-coloured deer, <i>see</i> 'Some Account of English Deer Parks,' by + E. P. Shirley, Esq.</p> + + <p><a name="Nt_221" href="#NtA_221">[221]</a> 'The Dovecote,' by the Rev. + E. S. Dixon, p. 155; Bechstein, 'Naturgesch. Deutschlands,' Band iv., + 1795, s. 17.</p> + + <p><a name="Nt_222" href="#NtA_222">[222]</a> 'Cattle,' p. 202.</p> + + <p><a name="Nt_223" href="#NtA_223">[223]</a> Mr. J. Wilkinson, in + 'Remarks addressed to Sir J. Sebright,' 1820, p. 38.</p> + + <p><a name="Nt_224" href="#NtA_224">[224]</a> 'Gardener's Chronicle,' + 1858, p. 771.</p> + + <p><a name="Nt_225" href="#NtA_225">[225]</a> 'Bastarderzeugung,' s. 87, + 169. <i>See</i> also the Table at the end of volume.</p> + + <p><a name="Nt_226" href="#NtA_226">[226]</a> 'Bastarderzeugung,' s. 87, + 577.</p> + + <p><a name="Nt_227" href="#NtA_227">[227]</a> 'Kenntniss der + Befruchtung,' s. 137; 'Bastarderzeugung,' s. 92, 181. On raising the two + varieties from seed <i>see</i> s. 307.</p> + + <p><a name="Nt_228" href="#NtA_228">[228]</a> 'Bastarderzeugung,' s. + 216.</p> + + <p><a name="Nt_229" href="#NtA_229">[229]</a> The following facts, given + by Kölreuter in his 'Dritte Fortsetzung,' s. 34, 39, appear at first + sight strongly to confirm Mr. Scott's and Gärtner's statements; and to a + certain limited extent they do so. Kölreuter asserts, from innumerable + observations, that insects incessantly carry pollen from one species and + variety of Verbascum to another; and I can confirm this assertion; yet he + found that the white and yellow varieties of <i>Verbascum lychnitis</i> + often grew wild mingled together: moreover, he cultivated these two + varieties in considerable numbers during four years in his garden, and + they kept true by seed; but when he crossed them, they produced flowers + of an intermediate tint. Hence it might have thought that both varieties + must have a stronger elective affinity for the pollen of their own + variety than for that of the other; this elective affinity, I may add, of + each species for its own pollen (Kölreuter, 'Dritte Forts.,' s. 39, and + Gärtner, 'Bastarderz.,' <i>passim</i>) being a perfectly well-ascertained + power. But the force of the foregoing facts is much lessened by Gärtner's + numerous experiments, for, differently from Kölreuter, he never once got + ('Bastarderz.,' s. 307) an intermediate tint when he crossed the yellow + and white flowered varieties of Verbascum. So that the fact of the white + and yellow varieties keeping true to their colour by seed does not prove + that they were not mutually fertilised by the pollen carried by insects + from one to the other.</p> + + <p><a name="Nt_230" href="#NtA_230">[230]</a> 'Amaryllidaceæ,' 1837, p. + 366. Gärtner has made a similar observation.</p> + + <p><a name="Nt_231" href="#NtA_231">[231]</a> Kölreuter first observed + this fact. 'Mém. de l'Acad. St. Petersburg,' vol. iii. p. 197. <i>See</i> + also C. K. Sprengel, 'Das Entdeckte Geheimniss,' s. 345.</p> + + <p><a name="Nt_232" href="#NtA_232">[232]</a> Namely, Barbarines, + Pastissons, Giraumous: 'Annal. des Sc. Nat.,' tom. xxx., 1833, pp. 398 + and 405.</p> + + <p><a name="Nt_233" href="#NtA_233">[233]</a> 'Mémoire sur les + Cucurbitaceæ,' 1826, pp. 46, 55.</p> + + <p><a name="Nt_234" href="#NtA_234">[234]</a> 'Annales des Se. Nat.,' 4th + series, tom. vi. M. Naudin considers these forms as undoubtedly varieties + of <i>Cucurbita pepo</i>.</p> + + <p><a name="Nt_235" href="#NtA_235">[235]</a> 'Mém. Cucurb.,' p. 8.</p> + + <p><a name="Nt_236" href="#NtA_236">[236]</a> 'Zweite Forts.,' s. 53, + namely, Nicotiana major vulgaris; (2) perennis; (3) Transylvanica; (4) a + sub-var. of the last; (5) major latifol. fl. alb.</p> + + <p><a name="Nt_237" href="#NtA_237">[237]</a> Kölreuter was so much + struck with this fact that he suspected that a little pollen of <i>N. + glutinosa</i> in one of his experiments might have accidentally got + mingled with that of <i>var. perennis</i>, and thus aided its fertilising + power. But we now know conclusively from Gärtner ('Bastarderz.,' s. 34, + 431) that two kinds of pollen never act <i>conjointly</i> on a third + species; still less will the pollen of a distinct species, mingled with a + plant's own pollen, if the latter be present in sufficient quantity, have + any effect. The sole effect of mingling two kinds of pollen is to produce + in the same capsule seeds which yield plants, some taking after the one + and some after the other parent.</p> + + <p><a name="Nt_238" href="#NtA_238">[238]</a> Mr. Scott has made some + observations on the absolute sterility of a purple and white primrose + (<i>Primula vulgaris</i>) when fertilised by pollen from the primrose + ('Journal of Proc. of Linn. Soc.,' vol. viii., 1864, p. 98); but these + observations require confirmation. I raised a number of purple-flowered + long-styled seedlings from seed kindly sent me by Mr. Scott, and, though + they were all some degree sterile, they were much more fertile with + pollen taken from the common primrose than with their own pollen. Mr. + Scott has likewise described a red equal-styled cowslip (<i>P. veris</i>, + idem, p. 106), which was found by him to be highly sterile when crossed + with the common cowslip; but this was not the case with several + equal-styled red seedlings raised by me from his plant. This variety of + the cowslip presents the remarkable peculiarity of combining male organs + in every respect like those of the short-styled form, with female organs + resembling in function and partly in structure those of the long-styled + form; so that we have the singular anomaly of the two forms combined in + the same flower. Hence it is not surprising that these flowers should be + spontaneously self-infertile in a high degree.</p> + + <p><a name="Nt_239" href="#NtA_239">[239]</a> 'Act. Acad. St. + Petersburg,' 1780, part ii., pp. 84, 100.</p> + + <p><a name="Nt_240" href="#NtA_240">[240]</a> 'Annales des Sc. Nat.,' + tom. xxi. (1st series), p. 61.</p> + + <p><a name="Nt_241" href="#NtA_241">[241]</a> 'Bull. Bot. Soc. de + France,' Dec. 27th, 1861, tom. viii. p. 612.</p> + + <p><a name="Nt_242" href="#NtA_242">[242]</a> Quoted by Isid. Geoffroy + St. Hilaire, 'Hist. Naturelle Générale,' tom. iii. p. 476. Since this MS. + has been sent to press a full discussion on the present subject has + appeared in Mr. Herbert Spencer's 'Principles of Biology,' vol. ii. 1867, + p. 457 <i>et seq.</i></p> + + <p><a name="Nt_243" href="#NtA_243">[243]</a> For cats and dogs, &c., + <i>see</i> Bellingeri, in 'Annal. des Sc. Nat.,' 2nd series, Zoolog., + tom. xii. p. 155. For ferrets, Bechstein, 'Naturgeschichte Deutschlands,' + Band i., 1801, s. 786, 795. For rabbits, ditto, s. 1123, 1131; and + Bronn's 'Geschichte der Natur,' B. ii. s. 99. For mountain sheep, ditto, + s. 102. For the fertility of the wild sow, <i>see</i> Bechstein's + 'Naturgesch. Deutschlands,' B. i., 1801, s. 534; for the domestic pig, + Sidney's edit. of Youatt on the Pig, 1860, p. 62. With respect to + Lapland, <i>see</i> Acerbi's 'Travels to the North Cape,' Eng. translat., + vol. ii. p. 222. About the Highland cows, <i>see</i> Hogg on Sheep, p. + 263.</p> + + <p><a name="Nt_244" href="#NtA_244">[244]</a> For the eggs of <i>Gallus + bankiva</i>, <i>see</i> Blyth, in 'Annals and Mag. of Nat. Hist., 2nd + series, vol. i., 1848, p. 456. For wild and tame ducks, Macgillivray, + 'British Birds,' vol. v. p. 37; and 'Die Enten,' s. 87. For wild geese, + L. Lloyd, 'Scandinavian Adventures,' vol. ii. 1854, p. 413; and for tame + geese, 'Ornamental Poultry,' by Rev. E. S. Dixon, p. 139. On the breeding + of pigeons, Pistor, 'Das Ganze der Taubenzucht,' 1831, s. 46; and Boitard + and Corbié, 'Les Pigeons,' p. 158. With respect to peacocks, according to + Temminck ('Hist. Nat. Gén. des Pigeons,' &c., 1813, tom. ii. p. 41), + the hen lays in India even as many as twenty eggs; but according to + Jerdon and another writer (quoted in Tegetmeier's 'Poultry Book,' 1866, + pp. 280, 282), she there lays only from four to nine or ten eggs: in + England she is said, in the 'Poultry Book,' to lay five or six, but + another writer says from eight to twelve eggs.</p> + + <p><a name="Nt_245" href="#NtA_245">[245]</a> 'The Art of Improving the + Breed, &c.,' 1809, p. 16.</p> + + <p><a name="Nt_246" href="#NtA_246">[246]</a> For Andrew Knight, + <i>see</i> A. Walker, on 'Intermarriage,' 1838, p. 227. Sir J. Sebright's + Treatise has just been quoted.</p> + + <p><a name="Nt_247" href="#NtA_247">[247]</a> 'Cattle,' p. 199.</p> + + <p><a name="Nt_248" href="#NtA_248">[248]</a> Nathusius, 'Ueber Shorthorn + Rindvieh,' 1857, s. 71: <i>see</i> also 'Gardener's Chronicle,' 1860, p. + 270. Many analogous cases are given in a pamphlet recently published by + Mr. C. Macknight and Dr. H. Madden, 'On the True Principles of Breeding;' + Melbourne, Australia, 1865.</p> + + <p><a name="Nt_249" href="#NtA_249">[249]</a> Mr. Willoughby Wood, in + 'Gardener's Chronicle,' 1855, p. 411; and 1860, p. 270. <i>See</i> the + very clear tables and pedigrees given in Nathusius' 'Rindvieh,' s. + 72-77.</p> + + <p><a name="Nt_250" href="#NtA_250">[250]</a> Mr. Wright, 'Journal of + Royal Agricult. Soc.,' vol. vii., 1846, p. 204.</p> + + <p><a name="Nt_251" href="#NtA_251">[251]</a> Youatt on Cattle, p. + 202.</p> + + <p><a name="Nt_252" href="#NtA_252">[252]</a> Report British Assoc., + Zoolog. Sect., 1838.</p> + + <p><a name="Nt_253" href="#NtA_253">[253]</a> Azara, 'Quadrupèdes du + Paraguay,' tom. ii. pp. 354, 368.</p> + + <p><a name="Nt_254" href="#NtA_254">[254]</a> For the case of the Messrs. + Brown, <i>see</i> 'Gard. Chronicle,' 1855, p. 26. For the Foscote flock, + 'Gard. Chron.,' 1860, p. 416. For the Naz flock, 'Bull. de la Soc. + d'Acclimat.,' 1860, p. 477.</p> + + <p><a name="Nt_255" href="#NtA_255">[255]</a> Nathusius, 'Rindvieh,' s. + 65; Youatt on Sheep, p. 495.</p> + + <p><a name="Nt_256" href="#NtA_256">[256]</a> 'Gard. Chronicle,' 1861, p. + 631.</p> + + <p><a name="Nt_257" href="#NtA_257">[257]</a> Lord Somerville, 'Facts on + Sheep and Husbandry,' p. 6. Mr. Spooner, in 'Journal of Royal Agricult. + Soc. of England,' vol. xx., part ii. <i>See</i> also an excellent paper + on the same subject in 'Gard. Chronicle,' 1860, p. 321, by Mr. Charles + Howard.</p> + + <p><a name="Nt_258" href="#NtA_258">[258]</a> 'Some Account of English + Deer Parks,' by Evelyn P. Shirley, 1867.</p> + + <p><a name="Nt_259" href="#NtA_259">[259]</a> 'The Art of Improving the + Breed,' &c., p. 13. With respect to Scotch deer-hounds, <i>see</i> + Scrope's 'Art of Deer Stalking,' pp. 350-353.</p> + + <p><a name="Nt_260" href="#NtA_260">[260]</a> 'Cottage Gardener,' 1861, + p. 327.</p> + + <p><a name="Nt_261" href="#NtA_261">[261]</a> Sidney's edit. of Youatt on + the Pig, 1860, p. 30; p. 33, quotation from Mr. Druce; p. 29, on Lord + Western's case.</p> + + <p><a name="Nt_262" href="#NtA_262">[262]</a> 'Journal, Royal Agricult. + Soc. of England,' 1846, vol. vii. p. 205.</p> + + <p><a name="Nt_263" href="#NtA_263">[263]</a> 'Ueber Rindvieh,' &c., + s. 78.</p> + + <p><a name="Nt_264" href="#NtA_264">[264]</a> Sidney on the Pig, p. 36. + <i>See</i> also note, p. 34. Also Richardson on the Pig, 1847, p. 26.</p> + + <p><a name="Nt_265" href="#NtA_265">[265]</a> Dr. Dally has published an + excellent article (translated in the 'Anthropolog. Review,' May, 1864, p. + 65), criticising all writers who have maintained that evil follows from + consanguineous marriages. No doubt on this side of the question many + advocates have injured their cause by inaccuracies: thus it has been + stated (Devay, 'Du Danger des Mariages,' &c., 1862, p. 141) that the + marriages of cousins have been prohibited by the legislature of Ohio; but + I have been assured, in answer to inquiries made in the United States, + that this statement is a mere fable.</p> + + <p><a name="Nt_266" href="#NtA_266">[266]</a> <i>See</i> his most + interesting work on the 'Early History of Man,' 1865, chap. x.</p> + + <p><a name="Nt_267" href="#NtA_267">[267]</a> On Consanguinity in + Marriage, in the 'Fortnightly Review,' 1865, p. 710; Hofacker, 'Ueber die + Eigenschaften,' &c.</p> + + <p><a name="Nt_268" href="#NtA_268">[268]</a> Sir G. Grey's 'Journal of + Expeditions into Australia,' vol. ii. p. 243; and Dobrizhoffer, 'On the + Abipones of South America.'</p> + + <p><a name="Nt_269" href="#NtA_269">[269]</a> 'The Art of Improving the + Breed,' p. 13.</p> + + <p><a name="Nt_270" href="#NtA_270">[270]</a> 'The Poultry Book,' by W. + B. Tegetmeier, 1866, p. 245.</p> + + <p><a name="Nt_271" href="#NtA_271">[271]</a> 'Journal Royal Agricult. + Soc.' 1846, vol. vii. p. 205; <i>see</i> also Ferguson on the Fowl, pp. + 83, 317; <i>see</i> also 'The Poultry Book,' by Tegetmeier, 1866, p. 135, + with respect to the extent to which cock-fighters found that they could + venture to breed in-and-in, viz., occasionally a hen with her own son; + "but they were cautious not to repeat the in-and-in breeding."</p> + + <p><a name="Nt_272" href="#NtA_272">[272]</a> 'The Poultry Book,' by W. + B. Tegetmeier, 1866, p. 79.</p> + + <p><a name="Nt_273" href="#NtA_273">[273]</a> 'The Poultry Chronicle,' + 1854, vol. i. p. 43.</p> + + <p><a name="Nt_274" href="#NtA_274">[274]</a> 'The Poultry Book,' by W. + B. Tegetmeier, 1866, p. 79.</p> + + <p><a name="Nt_275" href="#NtA_275">[275]</a> 'The Poultry Chronicle,' + vol. i. p. 89.</p> + + <p><a name="Nt_276" href="#NtA_276">[276]</a> 'The Poultry Book,' 1866, + p. 210.</p> + + <p><a name="Nt_277" href="#NtA_277">[277]</a> Ibid, 1866, p. 167; and + 'Poultry Chronicle,' vol. iii., 1855, p. 15.</p> + + <p><a name="Nt_278" href="#NtA_278">[278]</a> 'A Treatise on Fancy + Pigeons,' by J. M. Eaton, p. 56.</p> + + <p><a name="Nt_279" href="#NtA_279">[279]</a> 'The Pigeon Book,' p. + 46.</p> + + <p><a name="Nt_280" href="#NtA_280">[280]</a> 'Das Ganze der + Taubenzucht,' 1837, s. 18.</p> + + <p><a name="Nt_281" href="#NtA_281">[281]</a> 'Les Pigeons,' 1824, p. + 35.</p> + + <p><a name="Nt_282" href="#NtA_282">[282]</a> 'Proc. Entomolog. Soc.,' + Aug. 6th, 1860, p. 126.</p> + + <p><a name="Nt_283" href="#NtA_283">[283]</a> 'Journal of Horticulture,' + 1861, pp. 39, 77, 158; and 1864, p. 206.</p> + + <p><a name="Nt_284" href="#NtA_284">[284]</a> 'Beiträge zur Kenntniss der + Befruchtung,' 1844, s. 366.</p> + + <p><a name="Nt_285" href="#NtA_285">[285]</a> 'Amaryllidaceæ,' p. + 371.</p> + + <p><a name="Nt_286" href="#NtA_286">[286]</a> 'De la Fécondation,' 2nd + edit., 1862, p. 79.</p> + + <p><a name="Nt_287" href="#NtA_287">[287]</a> 'Mémoire sur les + Cucurbitacées,' pp. 36, 28, 30.</p> + + <p><a name="Nt_288" href="#NtA_288">[288]</a> Loudon's 'Gard. Mag.,' vol. + viii., 1832, p. 52.</p> + + <p><a name="Nt_289" href="#NtA_289">[289]</a> 'Transact. Hort. Soc.,' + vol. i. p. 25.</p> + + <p><a name="Nt_290" href="#NtA_290">[290]</a> 'Annal. des Sc. Nat.,' 3rd + series, Bot., tom. vi. p. 189.</p> + + <p><a name="Nt_291" href="#NtA_291">[291]</a> 'Philosophical + Transactions,' 1799, p. 200.</p> + + <p><a name="Nt_292" href="#NtA_292">[292]</a> 'Ueber die + Bastarderzeugung,' 1828, s. 32, 33. For Mr. Chaundy's case, <i>see</i> + Loudon's 'Gard. Mag.,' vol. vii., 1831, p. 696.</p> + + <p><a name="Nt_293" href="#NtA_293">[293]</a> 'Gardener's Chron.,' 1846, + p. 601.</p> + + <p><a name="Nt_294" href="#NtA_294">[294]</a> 'Philosoph. Transact.,' + 1799, p. 201.</p> + + <p><a name="Nt_295" href="#NtA_295">[295]</a> Quoted in 'Bull. Bot. Soc. + France,' vol. ii., 1855, p. 327.</p> + + <p><a name="Nt_296" href="#NtA_296">[296]</a> Gärtner, + 'Bastarderzeugung,' s. 259, 518, 526 <i>et seq.</i></p> + + <p><a name="Nt_297" href="#NtA_297">[297]</a> 'Fortsetzung,' 1763, s. 29; + 'Dritte Fortsetzung,' s. 44, 96; 'Act. Acad. St. Petersburg,' 1782, part + ii., p. 251; 'Nova Acta,' 1793, pp. 391, 394; 'Nova Acta,' 1795, pp. 316, + 323.</p> + + <p><a name="Nt_298" href="#NtA_298">[298]</a> 'Die Bastardbefruchtung,' + &c., 1865, s. 31, 41, 42.</p> + + <p><a name="Nt_299" href="#NtA_299">[299]</a> Max Wichura fully accepts + this view ('Bastardbefruchtung,' s. 43), as does the Rev. M. J. Berkeley, + in 'Journal of Hort. Soc.,' Jan. 1866, p. 70.</p> + + <p><a name="Nt_300" href="#NtA_300">[300]</a> 'Bastarderzeugung,' s. 394, + 526, 528.</p> + + <p><a name="Nt_301" href="#NtA_301">[301]</a> Kölreuter,' Nova Acta,' + 1795, p. 316.</p> + + <p><a name="Nt_302" href="#NtA_302">[302]</a> Gärtner, + 'Bastarderzeugung,' s. 430.</p> + + <p><a name="Nt_303" href="#NtA_303">[303]</a> 'Botanische Zeitung,' Jan. + 1864, s. 3.</p> + + <p><a name="Nt_304" href="#NtA_304">[304]</a> 'Monatsbericht Akad. + Wissen,' Berlin, 1866, s. 372.</p> + + <p><a name="Nt_305" href="#NtA_305">[305]</a> International Hort. + Congress, London, 1866.</p> + + <p><a name="Nt_306" href="#NtA_306">[306]</a> 'Proc. Bot. Soc. of + Edinburgh,' May, 1863: these observations are given in abstract, and + others are added, in the 'Journal of Proc. of Linn. Soc.,' vol. viii. + Bot., 1864, p. 162.</p> + + <p><a name="Nt_307" href="#NtA_307">[307]</a> Prof. Lecoq, 'De la + Fécondation,' 2nd edit., 1862, p. 76.</p> + + <p><a name="Nt_308" href="#NtA_308">[308]</a> 'Bastarderzeugung,' s. 64, + 357.</p> + + <p><a name="Nt_309" href="#NtA_309">[309]</a> Idem, s. 357.</p> + + <p><a name="Nt_310" href="#NtA_310">[310]</a> 'Zweite Fortsetzung,' s. + 10; 'Dritte Fort.,' s. 40.</p> + + <p><a name="Nt_311" href="#NtA_311">[311]</a> Duvernoy, quoted by + Gärtner, 'Bastarderzeugung,' s. 334.</p> + + <p><a name="Nt_312" href="#NtA_312">[312]</a> 'Gardner's Chronicle,' + 1846, p. 183.</p> + + <p><a name="Nt_313" href="#NtA_313">[313]</a> 'Transact. Hort. Soc.,' + vol. vii., 1830, p. 95.</p> + + <p><a name="Nt_314" href="#NtA_314">[314]</a> Prof. Lecoq, 'De la + Fécondation,' 1845, p. 70; Gärtner, 'Bastarderzeugung,' s. 64.</p> + + <p><a name="Nt_315" href="#NtA_315">[315]</a> 'Gardener's Chron.' 1866, + p. 1068.</p> + + <p><a name="Nt_316" href="#NtA_316">[316]</a> 'Journal of Proc. of Linn. + Soc.,' vol. viii., 1864, p. 168.</p> + + <p><a name="Nt_317" href="#NtA_317">[317]</a> 'Amaryllidaceæ,' 1837, p. + 371; 'Journal of Hort. Soc.,' vol. ii., 1847, p. 19.</p> + + <p><a name="Nt_318" href="#NtA_318">[318]</a> Loudon's 'Gardener's + Magazine,' vol. xi., 1835, p. 260.</p> + + <p><a name="Nt_319" href="#NtA_319">[319]</a> 'Gardener's Chronicle,' + 1850, p. 470.</p> + + <p><a name="Nt_320" href="#NtA_320">[320]</a> 'Journal Hort. Soc., vol. + v. p. 135. The seedlings thus raised were given to the Hort. Soc.; but I + find, on inquiry, that they unfortunately died the following winter.</p> + + <p><a name="Nt_321" href="#NtA_321">[321]</a> Mr. D. Beaton, in 'Journal + of Hort.,' 1861, p. 453. Lecoq, however ('De la Fécond.,' 1862, p. 369), + states that this hybrid is descended from <i>G. psittacinus</i> and + <i>cardinalis</i>; but this is opposed to Herbert's experience, who found + that the former species could not be crossed.</p> + + <p><a name="Nt_322" href="#NtA_322">[322]</a> This is the conclusion of + Prof. Devay, 'Du Danger des Mariages Consang.,' 1862, p. 97. Virchow + quotes, in the 'Deutsche Jahrbücher,' 1863, s. 354, some curious evidence + on half the cases of a peculiar form of blindness occurring in the + offspring from near relations.</p> + + <p><a name="Nt_323" href="#NtA_323">[323]</a> For England, <i>see</i> + below. For Germany, <i>see</i> Metzger, 'Getreidearten,' 1841, s. 63. For + France, Loiseleur-Deslongchamps ('Consid. sur les Céreales,' 1843, p. + 200) gives numerous references on this subject. For Southern France, + <i>see</i> Godron, 'Florula Juvenalis,' 1854, p. 28.</p> + + <p><a name="Nt_324" href="#NtA_324">[324]</a> 'A general Treatise of + Husbandry,' vol. iii. p. 58.</p> + + <p><a name="Nt_325" href="#NtA_325">[325]</a> 'Gardener's Chronicle and + Agricult. Gazette,' 1858, p. 247; and for the second statement, idem, + 1850, p. 702. On this same subject, <i>see</i> also Rev. D. Walker's + 'Prize Essay of Highland Agricult. Soc.,' vol. ii. p. 200. Also + Marshall's 'Minutes of Agriculture,' November, 1775.</p> + + <p><a name="Nt_326" href="#NtA_326">[326]</a> Oberlin's 'Memoirs,' Eng. + translat., p. 73. For Lancashire, <i>see</i> Marshall's 'Review of + Reports,' 1808, p. 295.</p> + + <p><a name="Nt_327" href="#NtA_327">[327]</a> 'Cottage Gardener,' 1856, + p. 186. For Mr. Robson's subsequent statements, <i>see</i> 'Journal of + Horticulture,' Feb. 18, 1866, p. 121. For Mr. Abbey's remarks on + grafting, &c., idem, July 18, 1865, p. 44.</p> + + <p><a name="Nt_328" href="#NtA_328">[328]</a> 'Mém. de l'Acad. des + Sciences,' 1790, p. 209.</p> + + <p><a name="Nt_329" href="#NtA_329">[329]</a> 'On the Varieties of + Wheat,' p. 52.</p> + + <p><a name="Nt_330" href="#NtA_330">[330]</a> Mr. Spencer has fully and + ably discussed this whole subject in his 'Principles of Biology,' 1864, + vol. ii. ch. x. In the first edition of my 'Origin of Species,' 1859, p. + 267, I spoke of the good effects from slight changes in the conditions of + life and from cross-breeding, and of the evil effects from great changes + in the conditions and from crossing widely distinct forms, as a series of + facts "connected together by some common but unknown bond, which is + essentially related to the principle of life."</p> + + <p><a name="Nt_331" href="#NtA_331">[331]</a> 'Essais de Zoologie + Générale,' 1841, p. 256.</p> + + <p><a name="Nt_332" href="#NtA_332">[332]</a> Du Rut, 'Annales du + Muséum,' 1807, tom. ix. p. 120.</p> + + <p><a name="Nt_333" href="#NtA_333">[333]</a> 'Säugethiere von Paraguay,' + 1830, s. 49, 106, 118, 124, 201, 208, 249, 265, 327.</p> + + <p><a name="Nt_334" href="#NtA_334">[334]</a> 'The Naturalist on the + Amazons,' 1863, vol. i. pp. 99, 193; vol. ii. p. 113.</p> + + <p><a name="Nt_335" href="#NtA_335">[335]</a> 'Embassy to the Court of + Ava,' vol. i. p. 534.</p> + + <p><a name="Nt_336" href="#NtA_336">[336]</a> 'Journal,' vol. i. p. + 213.</p> + + <p><a name="Nt_337" href="#NtA_337">[337]</a> 'Säugethiere,' s. 327.</p> + + <p><a name="Nt_338" href="#NtA_338">[338]</a> On the Breeding of the + larger Felidæ, 'Proc. Zoolog. Soc.,' 1861, p. 140.</p> + + <p><a name="Nt_339" href="#NtA_339">[339]</a> Sleeman's 'Rambles in + India,' vol. ii. p. 10.</p> + + <p><a name="Nt_340" href="#NtA_340">[340]</a> Wiegmann's 'Archif für + Naturgesch.,' 1837, s. 162.</p> + + <p><a name="Nt_341" href="#NtA_341">[341]</a> Rengger, 'Säugethiere,' + &c., s. 276. On the parentage of the guinea-pig, <i>see</i> also + Isid. Geoffroy St. Hilaire, 'Hist. Nat. Gén.'</p> + + <p><a name="Nt_342" href="#NtA_342">[342]</a> Although the existence of + the <i>Leporides</i>, as described by Dr. Broca ('Journal de Phys.,' tom. + ii. p. 370), is now positively denied, yet Dr. Pigeaux ('Annals and Mag. + of Nat. Hist.,' vol. xx., 1867, p. 75) affirms that the hare and rabbit + have produced hybrids.</p> + + <p><a name="Nt_343" href="#NtA_343">[343]</a> 'Quadrupeds of North + America,' by Audubon and Bachman, 1846, p. 268.</p> + + <p><a name="Nt_344" href="#NtA_344">[344]</a> Loudon's 'Mag. of Nat. + Hist.,' vol. ix., 1836, p. 571; Audubon and Bachman's 'Quadrupeds of + North America,' p. 221.</p> + + <p><a name="Nt_345" href="#NtA_345">[345]</a> Flourens, 'De l'Instinct,' + &c., 1845, p. 88.</p> + + <p><a name="Nt_346" href="#NtA_346">[346]</a> <i>See</i> 'Annual Reports + Zoolog. Soc.,' 1855, 1858, 1863, 1864; 'Times' newspaper, Aug. 10th, + 1847; Flourens, 'De l'Instinct,' p. 85.</p> + + <p><a name="Nt_347" href="#NtA_347">[347]</a> 'Säugethiere,' &c., s. + 34, 49.</p> + + <p><a name="Nt_348" href="#NtA_348">[348]</a> Art. Brazil, 'Penny + Cyclop.,' p. 363.</p> + + <p><a name="Nt_349" href="#NtA_349">[349]</a> 'The Naturalist on the + River Amazon,' vol. i. p. 99.</p> + + <p><a name="Nt_350" href="#NtA_350">[350]</a> 'Encyclop. of Rural + Sports,' p. 691.</p> + + <p><a name="Nt_351" href="#NtA_351">[351]</a> According to Sir A. Burnes + ('Cabool,' &c., p. 51), eight species are used for hawking in + Scinde.</p> + + <p><a name="Nt_352" href="#NtA_352">[352]</a> Loudon's 'Mag. of Nat. + Hist.,' vol. vi., 1833, p. 110.</p> + + <p><a name="Nt_353" href="#NtA_353">[353]</a> F. Cuvier, 'Annal. du + Muséum,' tom. ix. p. 128.</p> + + <p><a name="Nt_354" href="#NtA_354">[354]</a> 'The Zoologist,' vol. + vii.-viii., 1849-50, p. 2648.</p> + + <p><a name="Nt_355" href="#NtA_355">[355]</a> Knox, 'Ornithological + Rambles in Sussex,' p. 91.</p> + + <p><a name="Nt_356" href="#NtA_356">[356]</a> 'The Zoologist,' vol. + vii.-viii., 1849-50, p. 2566; vol. ix.-x., 1851-2, p. 3207.</p> + + <p><a name="Nt_357" href="#NtA_357">[357]</a> Bechstein, 'Naturgesch. der + Stubenvögel,' 1840, s. 20.</p> + + <p><a name="Nt_358" href="#NtA_358">[358]</a> 'Ornithological Biography,' + vol. v. p. 517.</p> + + <p><a name="Nt_359" href="#NtA_359">[359]</a> A case is recorded in 'The + Zoologist,' vol. i.-ii., 1843-45, p. 453. For the siskin breeding, vol. + iii.-iv., 1845-46, p. 1075. Bechstein, 'Stubenvögel,' s. 139, speaks of + bullfinches making nests, but rarely producing young.</p> + + <p><a name="Nt_360" href="#NtA_360">[360]</a> Yarrell's 'Hist. British + Birds,' 1839, vol. i. p. 412.</p> + + <p><a name="Nt_361" href="#NtA_361">[361]</a> Loudon's 'Mag. of Nat. + History,' vol. ix., 1836, p. 347.</p> + + <p><a name="Nt_362" href="#NtA_362">[362]</a> 'Mémoires du Muséum d'Hist. + Nat.,' tom. x. p. 314: five cases of parrots breeding in France are here + recorded. <i>See</i>, also, 'Report Brit. Assoc. Zoolog.,' 1843.</p> + + <p><a name="Nt_363" href="#NtA_363">[363]</a> 'Stubenvögel,' s. 105, + 83.</p> + + <p><a name="Nt_364" href="#NtA_364">[364]</a> Dr. Hancock remarks + ('Charlesworth's Mag. of Nat. Hist.,' vol. ii., 1838, p. 492), "it is + singular that, amongst the numerous useful birds that are indigenous to + Guiana, none are found to propagate among the Indians; yet the common + fowl is reared in abundance throughout the country."</p> + + <p><a name="Nt_365" href="#NtA_365">[365]</a> 'A Week at Port Royal,' + 1855, p. 7.</p> + + <p><a name="Nt_366" href="#NtA_366">[366]</a> Audubon, 'American + Ornithology,' vol. v. pp. 552, 557.</p> + + <p><a name="Nt_367" href="#NtA_367">[367]</a> Moubray on Poultry, 7th + edit., p. 133.</p> + + <p><a name="Nt_368" href="#NtA_368">[368]</a> Temminck, 'Hist. Nat. Gén. + des Pigeons,' &c., 1813, tom. iii. pp. 288, 382; 'Annals and Mag. of + Nat. Hist.,' vol. xii., 1843, p. 453. Other species of partridge have + occasionally bred; as the red-legged (<i>P. rubra</i>), when kept in a + large court in France (<i>see</i> 'Journal de Physique,' tom. xxv. p. + 294), and in the Zoological Gardens in 1856.</p> + + <p><a name="Nt_369" href="#NtA_369">[369]</a> Rev. E. S. Dixon, 'The + Dovecote,' 1851, pp. 243-252.</p> + + <p><a name="Nt_370" href="#NtA_370">[370]</a> Temminck, 'Hist. Nat. Gén. + des Pigeons,' &c., tom. ii. pp. 456, 458; tom. iii. pp. 2, 13, + 47.</p> + + <p><a name="Nt_371" href="#NtA_371">[371]</a> Bates, 'The Naturalist on + the Amazons,' vol. i. p. 193; vol. ii. p. 112.</p> + + <p><a name="Nt_372" href="#NtA_372">[372]</a> Temminck, 'Hist. Nat. + Gén.,' &c., tom. iii. p. 125. For <i>Tetrao urogallus</i>, <i>see</i> + L. Lloyd, 'Field Sports of North of Europe,' vol. i. pp. 287, 314; and + 'Bull. de la Soc. d'Acclimat.,' tom. vii., 1860, p. 600. For <i>T. + Scoticus</i>, Thompson, 'Nat. Hist. of Ireland,' vol. ii., 1850, p. 49. + For <i>T. cupido</i>, 'Boston Journal of Nat. Hist.,' vol. iii. p. + 199.</p> + + <p><a name="Nt_373" href="#NtA_373">[373]</a> Marcel de Serres, 'Annales + des Sci. Nat.,' 2nd series, Zoolog., tom. xiii. p. 175.</p> + + <p><a name="Nt_374" href="#NtA_374">[374]</a> Dr. Hancock, in + 'Charlesworth's Mag. of Nat. Hist.' vol. ii., 1838, p. 491; R. Hill, 'A + Week at Port Royal,' p. 8; 'Guide to the Zoological Gardens,' by P. L. + Sclater, 1859, pp. 11, 12; 'The Knowsley Menagerie,' by Dr. Gray, 1846, + pl. xiv.; E. Blyth, 'Report Asiatic Soc. of Bengal,' May, 1855.</p> + + <p><a name="Nt_375" href="#NtA_375">[375]</a> Prof. Newton, in 'Proc. + Zoolog. Soc.,' 1860, p. 336.</p> + + <p><a name="Nt_376" href="#NtA_376">[376]</a> 'The Dovecote and Aviary,' + p. 428.</p> + + <p><a name="Nt_377" href="#NtA_377">[377]</a> 'Ornithological Biography,' + vol. iii. p. 9.</p> + + <p><a name="Nt_378" href="#NtA_378">[378]</a> 'Geograph. Journal,' vol. + xiii., 1844, p. 32.</p> + + <p><a name="Nt_379" href="#NtA_379">[379]</a> Loudon's 'Mag. of Nat. + Hist.,' vol. v., 1832, p. 153.</p> + + <p><a name="Nt_380" href="#NtA_380">[380]</a> 'Zoologist,' vols. v.-vi., + 1847-48, p. 1660.</p> + + <p><a name="Nt_381" href="#NtA_381">[381]</a> 'Transact. Entomolog. + Soc.,' vol. iv., 1845, p. 60.</p> + + <p><a name="Nt_382" href="#NtA_382">[382]</a> 'Transact. Linn. Soc.,' + vol. vii. p. 40.</p> + + <p><a name="Nt_383" href="#NtA_383">[383]</a> <i>See</i> an interesting + paper by Mr. Newman, in the 'Zoologist,' 1857, p. 5764; and Dr. Wallace, + in 'Proc. Entomolog. Soc.,' June 4th, 1860, p. 119.</p> + + <p><a name="Nt_384" href="#NtA_384">[384]</a> Yarrell's 'British Birds,' + vol. i. p. 506; Bechstein, 'Stubenvögel,' s. 185; 'Philosoph. Transact.,' + 1772, p. 271. Bronn ('Geschichte der Natur,' Band ii. s. 96) has + collected a number of cases. For the case of the deer, <i>see</i> 'Penny + Cyclop.,' vol. viii. p. 350.</p> + + <p><a name="Nt_385" href="#NtA_385">[385]</a> 'Journal de Physiologie,' + tom. ii. p. 347.</p> + + <p><a name="Nt_386" href="#NtA_386">[386]</a> For additional evidence on + this subject, <i>see</i> F. Cuvier, in 'Annales du Muséum,' tom. xii. p. + 119.</p> + + <p><a name="Nt_387" href="#NtA_387">[387]</a> Numerous instances could be + given. Thus Livingstone ('Travels,' p. 217) states that the King of the + Barotse, an inland tribe which never had any communication with white + men, was extremely fond of taming animals, and every young antelope was + brought to him. Mr. Galton informs me that the Damaras are likewise fond + of keeping pets. The Indians of South America follow the same habit. + Capt. Wilkes states that the Polynesians of the Samoan Islands tamed + pigeons; and the New Zealanders, as Mr. Mantell informs me, kept various + kinds of birds.</p> + + <p><a name="Nt_388" href="#NtA_388">[388]</a> For analogous cases with + the fowl, <i>see</i> Réaumur, 'Art de faire Eclorre,' &c., 1749, p. + 243; and Col. Sykes, in 'Proc. Zoolog. Soc.,' 1832, &c. With respect + to the fowl not breeding in northern regions, <i>see</i> Latham's 'Hist. + of Birds,' vol. viii., 1823, p. 169.</p> + + <p><a name="Nt_389" href="#NtA_389">[389]</a> 'Mém. par divers Savans, + Acad. des Sciences,' tom. vi., 1835, p. 347.</p> + + <p><a name="Nt_390" href="#NtA_390">[390]</a> Youatt on Sheep, p. + 181.</p> + + <p><a name="Nt_391" href="#NtA_391">[391]</a> J. Mills, 'Treatise on + Cattle,' 1776, p. 72.</p> + + <p><a name="Nt_392" href="#NtA_392">[392]</a> Bechstein, 'Stubenvögel,' + s. 242.</p> + + <p><a name="Nt_393" href="#NtA_393">[393]</a> Crawfurd's 'Descriptive + Dict. of the Indian Islands,' 1856, p. 145.</p> + + <p><a name="Nt_394" href="#NtA_394">[394]</a> 'Bull. de la Soc. + Acclimat., tom. ix., 1862, pp. 380, 384.</p> + + <p><a name="Nt_395" href="#NtA_395">[395]</a> For pigeons, <i>see</i> Dr. + Chapuis, 'Le Pigeon Voyageur Belge,' 1865, p. 66.</p> + + <p><a name="Nt_396" href="#NtA_396">[396]</a> 'Swedish Acts,' vol. i., + 1739, p. 3. Pallas makes the same remark in his Travels (Eng. translat.), + vol. i. p. 292.</p> + + <p><a name="Nt_397" href="#NtA_397">[397]</a> A. Kerner, 'Die Cultur der + Alpenflanzen,' 1864, s. 139; Watson's 'Cybele Britannica,' vol. i. p. + 131; Mr. D. Cameron, also, has written on the culture of Alpine plants in + 'Gard. Chronicle,' 1848, pp. 253, 268, and mentions a few which seed.</p> + + <p><a name="Nt_398" href="#NtA_398">[398]</a> 'Beiträge zur Kenntniss der + Befruchtung,' 1844, s. 333.</p> + + <p><a name="Nt_399" href="#NtA_399">[399]</a> 'Nova Acta Petrop.,' 1793, + p. 391.</p> + + <p><a name="Nt_400" href="#NtA_400">[400]</a> 'Cottage Gardener,' 1856, + pp. 44, 109.</p> + + <p><a name="Nt_401" href="#NtA_401">[401]</a> Dr. Herbert, + 'Amaryllidaceæ,' p. 176.</p> + + <p><a name="Nt_402" href="#NtA_402">[402]</a> Gärtner, 'Beiträge zur + Kenntniss,' &c., s. 560, 564.</p> + + <p><a name="Nt_403" href="#NtA_403">[403]</a> 'Gardener's Chronicle,' + 1844, p. 215; 1850, p. 470.</p> + + <p><a name="Nt_404" href="#NtA_404">[404]</a> 'Beiträge zur Kenntniss,' + &c., s. 252, 333.</p> + + <p><a name="Nt_405" href="#NtA_405">[405]</a> 'Journal of Hort. Soc.,' + vol. ii. 1847, p. 83.</p> + + <p><a name="Nt_406" href="#NtA_406">[406]</a> 'Beiträge zur Kenntniss,' + &c., s. 117 <i>et seq.</i>; Kölreuter, 'Zweite Fortsetzung,' s. 10, + 121; 'Dritte Fortsetzung,' s. 57. Herbert, 'Amaryllidaceæ,' p. 355. + Wiegmann, 'Ueber die Bastarderzeugung,' s. 27.</p> + + <p><a name="Nt_407" href="#NtA_407">[407]</a> 'Bastarderzeugung,' s. + 356.</p> + + <p><a name="Nt_408" href="#NtA_408">[408]</a> 'Teoria della + Riproduzione,' 1816, p. 84; 'Traité du Citrus,' 1811, p. 67.</p> + + <p><a name="Nt_409" href="#NtA_409">[409]</a> Mr. C. W. Crocker, in + 'Gard. Chronicle,' 1861, p. 1092.</p> + + <p><a name="Nt_410" href="#NtA_410">[410]</a> Verlot, 'Des Variétés,' + 1865, p. 80.</p> + + <p><a name="Nt_411" href="#NtA_411">[411]</a> Verlot, idem, p. 88.</p> + + <p><a name="Nt_412" href="#NtA_412">[412]</a> Prof. Allman, Brit. Assoc., + quoted in the 'Phytologist,' vol. ii. p. 483. Prof. Harvey, on the + authority of Mr. Andrews, who discovered the plant, informed me that this + monstrosity could be propagated by seed. With respect to the poppy, + <i>see</i> Prof. Goeppert, as quoted in 'Journal of Horticulture,' July + 1st, 1863, p. 171.</p> + + <p><a name="Nt_413" href="#NtA_413">[413]</a> 'Comptes Rendus,' Dec. + 19th, 1864, p. 1039.</p> + + <p><a name="Nt_414" href="#NtA_414">[414]</a> 'Gardener's Chronicle,' + 1866, p. 681.</p> + + <p><a name="Nt_415" href="#NtA_415">[415]</a> 'Theory of Horticulture,' + p. 333.</p> + + <p><a name="Nt_416" href="#NtA_416">[416]</a> Mr. Fairweather, in + 'Transact. Hort. Soc.,' vol. iii. p. 406; Bosse, quoted by Bronn, + 'Geschichte der Natur,' B. ii. s. 77. On the effects of the removal of + the anthers, <i>see</i> Mr. Leitner, in Silliman's 'North American Journ. + of Science,' vol. xxiii. p. 47; and Verlot, 'Des Variétés,' 1865, p. + 84.</p> + + <p><a name="Nt_417" href="#NtA_417">[417]</a> Lindley's 'Theory of + Horticulture,' p. 333.</p> + + <p><a name="Nt_418" href="#NtA_418">[418]</a> 'Gardener's Chronicle,' + 1865, p. 626; 1866, pp. 290, 730; and Verlot, 'Des Variétés,' p. 75.</p> + + <p><a name="Nt_419" href="#NtA_419">[419]</a> 'Gardener's Chronicle,' + 1843, p. 628. In this article I suggested the following theory on the + doubleness of flowers.</p> + + <p><a name="Nt_420" href="#NtA_420">[420]</a> Quoted by Gärtner, + 'Bastarderzeugung,' s. 567.</p> + + <p><a name="Nt_421" href="#NtA_421">[421]</a> 'Gardener's Chronicle,' + 1866, p. 901.</p> + + <p><a name="Nt_422" href="#NtA_422">[422]</a> Lindley, 'Theory of + Horticulture,' p. 175-179; Godron, 'De l'Espèce,' tom. i. p. 106: + Pickering, 'Races of Man;' Gallesio, 'Teoria della Riproduzione,' 1816, + p. 101-110. Meyen ('Reise um Erde,' Th. ii. s. 214) states that at + Manilla one variety of the banana is full of seeds; and Chamisso + (Hooker's 'Bot. Misc.,' vol. i. p. 310) describes a variety of the + bread-fruit in the Mariana Islands with small fruit, containing seeds + which are frequently perfect. Burnes, in his 'Travels in Bokhara,' + remarks on the pomegranate seeding in Mazenderan, as a remarkable + peculiarity.</p> + + <p><a name="Nt_423" href="#NtA_423">[423]</a> Ingledew, in 'Transact. of + Agricult. and Hort. Soc. of India,' vol. ii.</p> + + <p><a name="Nt_424" href="#NtA_424">[424]</a> 'De la Fécondation,' 1862, + p. 308.</p> + + <p><a name="Nt_425" href="#NtA_425">[425]</a> Hooker's 'Bot. Misc.,' vol. + i. p. 99; Gallesio, 'Teoria della Riproduzione,' p. 110.</p> + + <p><a name="Nt_426" href="#NtA_426">[426]</a> 'Transact. Linn. Soc.,' + vol. xvii. p. 563.</p> + + <p><a name="Nt_427" href="#NtA_427">[427]</a> Godron, 'De l'Espèce,' tom. + ii. p. 106; Herbert on Crocus, in 'Journal of Hort. Soc.,' vol. i., 1846, + p. 254.—Dr. Wight, from what he has seen in India, believes in this + view; 'Madras Journal of Lit. and Science,' vol. iv., 1836, p. 61.</p> + + <p><a name="Nt_428" href="#NtA_428">[428]</a> Wahlenberg specifies eight + species in this state on the Lapland Alps: <i>see</i> Appendix to + Linnæus' 'Tour in Lapland,' translated by Sir J. E. Smith, vol. ii. pp. + 274-280.</p> + + <p><a name="Nt_429" href="#NtA_429">[429]</a> 'Travels in North America,' + Eng. translat., vol. iii. p. 175.</p> + + <p><a name="Nt_430" href="#NtA_430">[430]</a> With respect to the ivy and + Acorus, <i>see</i> Dr. Bromfield in the 'Phytologist,' vol. iii. p. 376. + <i>See</i> also Lindley and Vaucher on the Acorus.</p> + + <p><a name="Nt_431" href="#NtA_431">[431]</a> 'Annal. des Sc. Nat.,' 3rd + series, Zool., tom. iv. p. 280. Prof. Decaisne refers also to analogous + cases with mosses and lichens near Paris.</p> + + <p><a name="Nt_432" href="#NtA_432">[432]</a> Mr. Tuckerman, in + Silliman's 'American Journal of Science,' vol. xlv. p. 41.</p> + + <p><a name="Nt_433" href="#NtA_433">[433]</a> Sir J. E. Smith, 'English + Flora,' vol. i. p. 339.</p> + + <p><a name="Nt_434" href="#NtA_434">[434]</a> G. Planchon, 'Flora de + Montpellier,' 1864, p. 20.</p> + + <p><a name="Nt_435" href="#NtA_435">[435]</a> On the non-production of + seeds in England <i>see</i> Mr. Crocker, in 'Gardener's Weekly Magazine,' + 1852, p. 70; Vaucher, 'Hist. Phys. Plantes d'Europe,' tom. i. p. 33; + Lecoq, 'Géograph. Bot. de l'Europe,' tom. iv. p. 466; Dr. D. Clos, in + 'Annal. des Sc. Nat.,' 3rd series, Bot., tom. xvii., 1852, p. 129: this + latter author refers to other analogous cases. On the non-production of + pollen by this Ranunculus <i>see</i> Chatin, in 'Comptes Rendus,' June + 11th, 1866.</p> + + <p><a name="Nt_436" href="#NtA_436">[436]</a> 'Bastarderzeugung,' s. 565. + Kölreuter ('Dritte Fortsetzung,' s. 73, 87, 119) also shows that when two + species, one single and the other double, are crossed, the hybrids are + apt to be extremely double.</p> + + <p><a name="Nt_437" href="#NtA_437">[437]</a> 'Teoria della Riproduzione + Veg.,' 1816, p. 73.</p> + + <p><a name="Nt_438" href="#NtA_438">[438]</a> 'Bastarderzeugung,' s. + 573.</p> + + <p><a name="Nt_439" href="#NtA_439">[439]</a> Ibid., s. 527.</p> + + <p><a name="Nt_440" href="#NtA_440">[440]</a> 'Transactions Phil. Soc.,' + 1799, p. 202. For Kölreuter, <i>see</i> 'Mém. de l'Acad. de St. + Pétersbourg,' tom. iii., 1809 (published 1811), p. 197. In reading C. K. + Sprengel's remarkable work, 'Das entdeckte Geheimniss,' &c., 1793, it + is curious to observe how often this wonderfully acute observer failed to + understand the full meaning of the structure of the flowers which he has + so well described, from not always having before his mind the key to the + problem, namely, the good derived from the crossing of distinct + individual plants.</p> + + <p><a name="Nt_441" href="#NtA_441">[441]</a> This abstract was published + in the fourth edition (1866) of my 'Origin of Species;' but as this + edition will be in the hands of but few persons, and as my original + observations on this point have not as yet been published in detail, I + have ventured here to reprint the abstract.</p> + + <p><a name="Nt_442" href="#NtA_442">[442]</a> The term <i>unconscious + selection</i> has been objected to as a contradiction: but <i>see</i> + some excellent observations on this head by Prof. Huxley ('Nat. Hist. + Review,' Oct. 1864, p. 578), who remarks that when the wind heaps up + sand-dunes it sifts and <i>unconsciously selects</i> from the gravel on + the beach grains of sand of equal size.</p> + + <p><a name="Nt_443" href="#NtA_443">[443]</a> Sheep, 1838, p. 60.</p> + + <p><a name="Nt_444" href="#NtA_444">[444]</a> Mr. J. Wright on Shorthorn + Cattle, in 'Journal of Royal Agricult. Soc.,' vol. vii. pp. 208, 209.</p> + + <p><a name="Nt_445" href="#NtA_445">[445]</a> H. D. Richardson on Pigs, + 1817, p. 44.</p> + + <p><a name="Nt_446" href="#NtA_446">[446]</a> 'Journal of R. Agricult. + Soc.,' vol. i. p. 24.</p> + + <p><a name="Nt_447" href="#NtA_447">[447]</a> Sheep, pp. 520, 319.</p> + + <p><a name="Nt_448" href="#NtA_448">[448]</a> Loudon's 'Mag. of Nat. + Hist.,' vol. viii., 1835, p. 618.</p> + + <p><a name="Nt_449" href="#NtA_449">[449]</a> 'A Treatise on the Art of + Breeding the Almond Tumbler,' 1851, p. 9.</p> + + <p><a name="Nt_450" href="#NtA_450">[450]</a> 'Recreations in + Agriculture,' vol. ii. p. 409.</p> + + <p><a name="Nt_451" href="#NtA_451">[451]</a> Youatt on Cattle, pp. 191, + 227.</p> + + <p><a name="Nt_452" href="#NtA_452">[452]</a> Ferguson, 'Prize Poultry,' + 1854, p. 208.</p> + + <p><a name="Nt_453" href="#NtA_453">[453]</a> Wilson, in 'Transact. + Highland Agricult. Soc.,' quoted in 'Gard. Chronicle,' 1844, p. 29.</p> + + <p><a name="Nt_454" href="#NtA_454">[454]</a> Simmonds, quoted in 'Gard. + Chronicle,' 1855, p. 637. And for the second quotation, <i>see</i> Youatt + on Sheep, p. 171.</p> + + <p><a name="Nt_455" href="#NtA_455">[455]</a> Robinet, 'Vers à Soie,' + 1848, p. 271.</p> + + <p><a name="Nt_456" href="#NtA_456">[456]</a> Quatrefages, 'Les Maladies + du Ver à Soie,' 1859, p. 101.</p> + + <p><a name="Nt_457" href="#NtA_457">[457]</a> M. Simon, in 'Bull. de la + Soc. d'Acclimat.,' tom. ix., 1862, p. 221.</p> + + <p><a name="Nt_458" href="#NtA_458">[458]</a> 'The Poultry Chronicle,' + vol. i., 1854, p. 607.</p> + + <p><a name="Nt_459" href="#NtA_459">[459]</a> J. M. Eaton, 'A Treatise on + Fancy Pigeons,' 1852, p. xiv., and 'A Treatise on the Almond Tumbler,' + 1851, p. 11.</p> + + <p><a name="Nt_460" href="#NtA_460">[460]</a> 'Journal Royal Agricultural + Soc.,' vol. vi. p. 22.</p> + + <p><a name="Nt_461" href="#NtA_461">[461]</a> 'Poultry Chronicle,' vol. + ii., 1855, p. 596.</p> + + <p><a name="Nt_462" href="#NtA_462">[462]</a> Isid. Geoffroy St. Hilaire, + 'Hist. Nat. Gén.,' tom. iii. p. 254.</p> + + <p><a name="Nt_463" href="#NtA_463">[463]</a> 'Gardener's Chronicle,' + 1850, p. 198.</p> + + <p><a name="Nt_464" href="#NtA_464">[464]</a> 'Transact. Hort. Soc.,' + vol. vi. p. 152.</p> + + <p><a name="Nt_465" href="#NtA_465">[465]</a> 'Journal of Horticulture,' + 1862, p. 369.</p> + + <p><a name="Nt_466" href="#NtA_466">[466]</a> 'Transact. Hort. Soc.,' + vol. iv. p. 381.</p> + + <p><a name="Nt_467" href="#NtA_467">[467]</a> 'Transact. Hort. Soc.,' + vol. iv. p. 285.</p> + + <p><a name="Nt_468" href="#NtA_468">[468]</a> Rev. W. Bromehead, in + 'Gard. Chronicle,' 1857, p. 550.</p> + + <p><a name="Nt_469" href="#NtA_469">[469]</a> 'Gard. Chronicle,' 1862, p. + 721.</p> + + <p><a name="Nt_470" href="#NtA_470">[470]</a> Dr. Anderson, in 'The Bee,' + vol. vi. p. 96; Mr. Barnes, in 'Gard. Chronicle,' 1844, p. 476.</p> + + <p><a name="Nt_471" href="#NtA_471">[471]</a> Godron, 'De l'Espèce,' + 1859, tom. ii. p. 69; 'Gard. Chronicle,' 1854, p. 258.</p> + + <p><a name="Nt_472" href="#NtA_472">[472]</a> On Sheep, p. 18.</p> + + <p><a name="Nt_473" href="#NtA_473">[473]</a> Volz, 'Beiträge zur + Kulturgeschichte,' 1852, s. 47.</p> + + <p><a name="Nt_474" href="#NtA_474">[474]</a> Mitford's 'History of + Greece,' vol. i. p. 73.</p> + + <p><a name="Nt_475" href="#NtA_475">[475]</a> Dr. Dally, translated in + 'Anthropological Review,' May 1864, p. 101.</p> + + <p><a name="Nt_476" href="#NtA_476">[476]</a> Volz, 'Beiträge,' &c., + 1852, s. 80.</p> + + <p><a name="Nt_477" href="#NtA_477">[477]</a> 'History of the World,' ch. + 45.</p> + + <p><a name="Nt_478" href="#NtA_478">[478]</a> 'Gardener's Chronicle,' + 1848, p. 323.</p> + + <p><a name="Nt_479" href="#NtA_479">[479]</a> Reynier, 'De l'Economie des + Celtes,' 1818, pp. 487, 503.</p> + + <p><a name="Nt_480" href="#NtA_480">[480]</a> Le Couteur on Wheat, p. + 15.</p> + + <p><a name="Nt_481" href="#NtA_481">[481]</a> Michel, 'Des Haras,' 1861, + p. 84.</p> + + <p><a name="Nt_482" href="#NtA_482">[482]</a> Sir W. Wilde, an 'Essay on + Unmanufactured Animal Remains,' &c., 1860, p. 11.</p> + + <p><a name="Nt_483" href="#NtA_483">[483]</a> Col. Hamilton Smith, 'Nat. + Library,' vol. xii., Horses, pp. 135, 140.</p> + + <p><a name="Nt_484" href="#NtA_484">[484]</a> Michel, 'Des Haras,' p. + 90.</p> + + <p><a name="Nt_485" href="#NtA_485">[485]</a> Mr. Baker, 'History of the + Horse,' Veterinary, vol. xiii. p. 423.</p> + + <p><a name="Nt_486" href="#NtA_486">[486]</a> M. l'Abbé Carlier, in + 'Journal de Physique,' vol. xxiv., 1784, p. 181: this memoir contains + much information on the ancient selection of sheep; and is my authority + for rams not being killed young in England.</p> + + <p><a name="Nt_487" href="#NtA_487">[487]</a> 'Gardener's Chronicle,' + 1843, p. 389.</p> + + <p><a name="Nt_488" href="#NtA_488">[488]</a> Communications to Board of + Agriculture, quoted in Dr. Darwin's 'Phytologia,' 1800, p. 451.</p> + + <p><a name="Nt_489" href="#NtA_489">[489]</a> 'Mémoire sur les Chinois,' + 1786, tom. xi. p. 55; tom. v. p. 507.</p> + + <p><a name="Nt_490" href="#NtA_490">[490]</a> 'Recherches sur + l'Agriculture des Chinois,' par L. D'Hervey-Saint-Denys, 1850, p. 229. + With respect to Khang-hi, <i>see</i> Huc's 'Chinese Empire,' p. 311.</p> + + <p><a name="Nt_491" href="#NtA_491">[491]</a> Anderson, in 'Linn. + Transact.,' vol. xii. p. 253.</p> + + <p><a name="Nt_492" href="#NtA_492">[492]</a> 'Mém. de l'Acad.' (divers + savans), tom. vi., 1835, p. 333.</p> + + <p><a name="Nt_493" href="#NtA_493">[493]</a> 'Des Quadrupèdes du + Paraguay,' 1801, tom. ii. p. 333, 371.</p> + + <p><a name="Nt_494" href="#NtA_494">[494]</a> 'The Great Sahara,' by the + Rev. H. B. Tristram, 1860, p. 238.</p> + + <p><a name="Nt_495" href="#NtA_495">[495]</a> Pallas, 'Act. Acad. St. + Petersburg,' 1777, p. 249; Moorcroft and Trebeck, 'Travels in the + Himalayan Provinces,' 1841.</p> + + <p><a name="Nt_496" href="#NtA_496">[496]</a> Quoted from Raffles, in the + 'Indian Field,' 1859, p. 196; for Varro, <i>see</i> Pallas, <i>ut + supra</i>.</p> + + <p><a name="Nt_497" href="#NtA_497">[497]</a> Erman's 'Travels in + Siberia,' Eng. translat., vol. i. p. 453.</p> + + <p><a name="Nt_498" href="#NtA_498">[498]</a> <i>See</i> also 'Journal of + R. Geograph. Soc.,' vol. xiii. part i. p. 65.</p> + + <p><a name="Nt_499" href="#NtA_499">[499]</a> Livingstone's 'First + Travels,' pp. 191, 439, 565; <i>see</i> also 'Expedition to the Zambesi,' + 1865, p. 465, for an analogous case respecting a good breed of goats.</p> + + <p><a name="Nt_500" href="#NtA_500">[500]</a> Andersson's 'Travels in + South Africa,' pp. 232, 318, 319.</p> + + <p><a name="Nt_501" href="#NtA_501">[501]</a> Dr. Vavasseur, in 'Bull. de + la Soc. d'Acclimat.,' tom. viii., 1861, p. 136.</p> + + <p><a name="Nt_502" href="#NtA_502">[502]</a> 'The Natural History of Dee + Side,' 1855, p. 476.</p> + + <p><a name="Nt_503" href="#NtA_503">[503]</a> 'Bull. de la Soc. + d'Acclimat.,' tom. vii., 1860, p. 457.</p> + + <p><a name="Nt_504" href="#NtA_504">[504]</a> 'Cattle,' p. 48.</p> + + <p><a name="Nt_505" href="#NtA_505">[505]</a> Livingstone's Travels, p. + 576; Andersson, 'Lake Ngami,' 1856, p. 222. With respect to the sale in + Kaffraria, <i>see</i> 'Quarterly Review,' 1860, p. 139.</p> + + <p><a name="Nt_506" href="#NtA_506">[506]</a> 'Mémoire sur les Chinois' + (by the Jesuits), 1786, tom. xi. p. 57.</p> + + <p><a name="Nt_507" href="#NtA_507">[507]</a> F. Michel, 'Des Haras,' pp. + 47, 50.</p> + + <p><a name="Nt_508" href="#NtA_508">[508]</a> Col. Hamilton Smith, Dogs, + in 'Nat. Lib.,' vol. x. p. 103.</p> + + <p><a name="Nt_509" href="#NtA_509">[509]</a> Azara, 'Quadrupèdes du + Paraguay,' tom. ii. p. 324.</p> + + <p><a name="Nt_510" href="#NtA_510">[510]</a> Sidney's edit. of Youatt, + 1860, pp. 24, 25.</p> + + <p><a name="Nt_511" href="#NtA_511">[511]</a> 'Rural Economy of + Yorkshire,' vol. ii. p. 182.</p> + + <p><a name="Nt_512" href="#NtA_512">[512]</a> Moll et Gayot, 'Du + Bœuf,' 1860, p. 547.</p> + + <p><a name="Nt_513" href="#NtA_513">[513]</a> 'The India Sporting + Review,' vol. ii. p. 181; 'The Stud Farm,' by Cecil, p. 58.</p> + + <p><a name="Nt_514" href="#NtA_514">[514]</a> 'The Horse,' p. 22.</p> + + <p><a name="Nt_515" href="#NtA_515">[515]</a> 'History of England,' vol. + i. p. 316.</p> + + <p><a name="Nt_516" href="#NtA_516">[516]</a> 'Uber Beständigkeit der + Arten.'</p> + + <p><a name="Nt_517" href="#NtA_517">[517]</a> Youatt on Sheep, p. + 315.</p> + + <p><a name="Nt_518" href="#NtA_518">[518]</a> 'Ueber Shorthorn Rindvieh,' + 1857, s. 51.</p> + + <p><a name="Nt_519" href="#NtA_519">[519]</a> Low, 'Domesticated + Animals,' 1845, p. 363.</p> + + <p><a name="Nt_520" href="#NtA_520">[520]</a> 'Quarterly Review,' 1849, + p. 392.</p> + + <p><a name="Nt_521" href="#NtA_521">[521]</a> H. von Nathusius, + 'Vorstudien ... Schweineschædel,' 1864, s. 140.</p> + + <p><a name="Nt_522" href="#NtA_522">[522]</a> <i>See</i> also Dr. Christ, + in 'Rütimeyer's Pfahlbauten,' 1861, s. 226.</p> + + <p><a name="Nt_523" href="#NtA_523">[523]</a> The passage is given 'Bull. + Soc. d'Acclimat.,' 1858, p. 11.</p> + + <p><a name="Nt_524" href="#NtA_524">[524]</a> 'Journal of Horticulture,' + 1862, p. 394.</p> + + <p><a name="Nt_525" href="#NtA_525">[525]</a> 'Gardener's Chronicle,' + 1857, p. 85.</p> + + <p><a name="Nt_526" href="#NtA_526">[526]</a> <i>See</i> Mr. Wildman's + address to the Floricult. Soc., in 'Gardener's Chronicle,' 1843, p. + 86.</p> + + <p><a name="Nt_527" href="#NtA_527">[527]</a> 'Journal of Horticulture,' + Oct. 24th, 1865, p. 239.</p> + + <p><a name="Nt_528" href="#NtA_528">[528]</a> Prescott's 'Hist. of + Mexico,' vol. ii. p. 61.</p> + + <p><a name="Nt_529" href="#NtA_529">[529]</a> Sageret, 'Pomologie + Physiologique,' 1830, p. 47; Gallesio, 'Teoria della Riproduzione,' 1816, + p. 88; Godron, 'De l'Espèce,' 1859, tom. ii. pp. 63, 67, 70. In my tenth + and eleventh chapters I have given details on the potato; and I can + confirm similar remarks with respect to the onion. I have also shown how + far Naudin concurs in regard to the varieties of the melon.</p> + + <p><a name="Nt_530" href="#NtA_530">[530]</a> Godron, 'De l'Espèce,' tom. + ii. p. 27.</p> + + <p><a name="Nt_531" href="#NtA_531">[531]</a> 'The Anthropological + Treatises of Blumenbach,' 1865, p. 292.</p> + + <p><a name="Nt_532" href="#NtA_532">[532]</a> Mr. J. J. Murphy in his + opening address to the Belfast Nat. Hist. Soc., as given in the Belfast + Northern Whig, Nov. 19, 1866. Mr. Murphy here follows the line of + argument against my views previously and more cautiously given by the + Rev. C. Pritchard, Pres. Royal Astronomical Soc., in his sermon + (Appendix, p. 33) preached before the British Association at Nottingham, + 1866.</p> + + <p><a name="Nt_533" href="#NtA_533">[533]</a> On the Vision of Fishes and + Amphibia, translated in 'Annals and Mag. of Nat. Hist.,' vol. xviii., + 1866, p. 469.</p> + + <p><a name="Nt_534" href="#NtA_534">[534]</a> Fourth edition, 1866, p. + 215.</p> + + <p><a name="Nt_535" href="#NtA_535">[535]</a> Quoted by Youatt on Sheep, + p. 325. <i>See</i> also Youatt on Cattle, pp. 62, 69.</p> + + <p><a name="Nt_536" href="#NtA_536">[536]</a> MM. Lherbette and De + Quatrefages, in 'Bull. Soc. Acclimat.,' tom. viii., 1861, p. 311.</p> + + <p><a name="Nt_537" href="#NtA_537">[537]</a> 'The Poultry Book,' 1866, + p. 123.</p> + + <p><a name="Nt_538" href="#NtA_538">[538]</a> Youatt on Sheep, p. + 312.</p> + + <p><a name="Nt_539" href="#NtA_539">[539]</a> 'Treatise on the Almond + Tumbler,' 1851, p. 33.</p> + + <p><a name="Nt_540" href="#NtA_540">[540]</a> Dr. Heusinger, + 'Wochenschrift für die Heilkunde,' Berlin, 1846, s. 279.</p> + + <p><a name="Nt_541" href="#NtA_541">[541]</a> Youatt on the Dog, p. + 232.</p> + + <p><a name="Nt_542" href="#NtA_542">[542]</a> 'The Fruit-trees of + America,' 1845, p. 270: for peaches, p. 466.</p> + + <p><a name="Nt_543" href="#NtA_543">[543]</a> 'Proc. Royal Soc. of Arts + and Sciences of Mauritius,' 1852, p. cxxxv.</p> + + <p><a name="Nt_544" href="#NtA_544">[544]</a> 'Gardener's Chronicle,' + 1856, p. 379.</p> + + <p><a name="Nt_545" href="#NtA_545">[545]</a> Quatrefages, 'Maladies + Actuelles du Ver à Soie,' 1859, pp. 12, 214.</p> + + <p><a name="Nt_546" href="#NtA_546">[546]</a> 'Gardener's Chronicle,' + 1851, p. 595.</p> + + <p><a name="Nt_547" href="#NtA_547">[547]</a> 'Journal of Horticulture,' + 1862, p. 476.</p> + + <p><a name="Nt_548" href="#NtA_548">[548]</a> 'Gardener's Chronicle,' + 1852, pp. 435, 691.</p> + + <p><a name="Nt_549" href="#NtA_549">[549]</a> Bechstein, 'Naturgesch. + Deutschlands,' 1801, B. i. s. 310.</p> + + <p><a name="Nt_550" href="#NtA_550">[550]</a> Prichard, 'Phys. Hist. of + Mankind,' 1851, vol. i. p. 224.</p> + + <p><a name="Nt_551" href="#NtA_551">[551]</a> G. Lewis's 'Journal of + Residence in West Indies,' 'Home and Col. Library,' p. 100.</p> + + <p><a name="Nt_552" href="#NtA_552">[552]</a> Sidney's edit. of Youatt on + the Pig, p.24.</p> + + <p><a name="Nt_553" href="#NtA_553">[553]</a> 'Journal of Horticulture,' + 1862, pp. 476, 498; 1865, p. 460. With respect to the heartsease, + 'Gardener's Chronicle,' 1863, p. 628.</p> + + <p><a name="Nt_554" href="#NtA_554">[554]</a> 'Des Jacinthes, de leur + Culture,' 1768, p. 53: on wheat, 'Gardener's Chronicle,' 1846, p. + 653.</p> + + <p><a name="Nt_555" href="#NtA_555">[555]</a> W. B. Tegetmeier, 'The + Field,' Feb. 25, 1865. With respect to black fowls, <i>see</i> a + quotation in Thompson's 'Nat. Hist. of Ireland,' 1849, vol. i. p. 22.</p> + + <p><a name="Nt_556" href="#NtA_556">[556]</a> 'Bull. de la Soc. + d'Acclimat.,' tom. vii. 1860, p. 359.</p> + + <p><a name="Nt_557" href="#NtA_557">[557]</a> 'Transact. Hort. Soc.,' + vol. i. 2nd series, 1835, p. 275. For raspberries, <i>see</i> 'Gard. + Chronicle,' 1855, p. 154, and 1863, p. 245.</p> + + <p><a name="Nt_558" href="#NtA_558">[558]</a> 'Gardener's Chronicle,' + 1843, p. 806.</p> + + <p><a name="Nt_559" href="#NtA_559">[559]</a> Ibid., 1850, p. 732.</p> + + <p><a name="Nt_560" href="#NtA_560">[560]</a> Ibid., 1860, p. 956.</p> + + <p><a name="Nt_561" href="#NtA_561">[561]</a> J. De Jonghe, in 'Gard. + Chronicle,' 1860, p. 120.</p> + + <p><a name="Nt_562" href="#NtA_562">[562]</a> Downing, 'Fruit-trees of + North America,' pp. 266, 501: in regard to the cherry, p. 198.</p> + + <p><a name="Nt_563" href="#NtA_563">[563]</a> 'Gardener's Chronicle,' + 1849, p. 755.</p> + + <p><a name="Nt_564" href="#NtA_564">[564]</a> 'Journal of Horticulture,' + Sept. 26th, 1865, p. 254; <i>see</i> other references given in chap. + x.</p> + + <p><a name="Nt_565" href="#NtA_565">[565]</a> Mr. Selby, in 'Mag. of + Zoology and Botany,' Edinburgh, vol. ii., 1838, p. 393.</p> + + <p><a name="Nt_566" href="#NtA_566">[566]</a> The Reine Claude de Bavay, + 'Journal of Horticulture,' Dec. 27, 1864, p. 511.</p> + + <p><a name="Nt_567" href="#NtA_567">[567]</a> Mr. Pusey, in 'Journal of + R. Agricult. Soc., vol. vi. p. 179. For Swedish turnips, <i>see</i> + 'Gard. Chron.,' 1847, p. 91.</p> + + <p><a name="Nt_568" href="#NtA_568">[568]</a> Godron, 'De l'Espèce,' tom. + ii. p. 98.</p> + + <p><a name="Nt_569" href="#NtA_569">[569]</a> 'Gardener's Chron.,' 1866, + p. 732.</p> + + <p><a name="Nt_570" href="#NtA_570">[570]</a> 'Gardener's Chronicle,' + 1862, pp. 820, 821.</p> + + <p><a name="Nt_571" href="#NtA_571">[571]</a> 'On the Varieties of + Wheat,' p. 59.</p> + + <p><a name="Nt_572" href="#NtA_572">[572]</a> Mr. Hewitt and others, in + 'Journal of Hort.,' 1862, p. 773.</p> + + <p><a name="Nt_573" href="#NtA_573">[573]</a> 'Encyclop. of Rural + Sports,' p. 405.</p> + + <p><a name="Nt_574" href="#NtA_574">[574]</a> Col. Le Couteur, 'Journal + Roy. Agricult. Soc.,' vol. iv. p. 43.</p> + + <p><a name="Nt_575" href="#NtA_575">[575]</a> 'Gardener's Chronicle,' + 1845, p. 273.</p> + + <p><a name="Nt_576" href="#NtA_576">[576]</a> 'Journal of Horticulture,' + 1862, p. 157.</p> + + <p><a name="Nt_577" href="#NtA_577">[577]</a> 'Cottage Gardener,' 1860, + p. 368.</p> + + <p><a name="Nt_578" href="#NtA_578">[578]</a> 'A Review of Reports,' + 1808, p. 406.</p> + + <p><a name="Nt_579" href="#NtA_579">[579]</a> 'Gardener's Chronicle,' + 1853, p. 45.</p> + + <p><a name="Nt_580" href="#NtA_580">[580]</a> Isidore Geoffroy St. + Hilaire, 'Hist. Nat. Gén.,' tom. iii. p. 49. On the Cochineal Insect, p. + 46.</p> + + <p><a name="Nt_581" href="#NtA_581">[581]</a> Capt. Marryat, quoted by + Blyth in 'Journ. Asiatic Soc. of Bengal,' vol. xxviii. p. 229.</p> + + <p><a name="Nt_582" href="#NtA_582">[582]</a> Mr. Oxley, 'Journal of the + Indian Archipelago,' vol. ii., 1848, p. 645.</p> + + <p><a name="Nt_583" href="#NtA_583">[583]</a> Mr. Abbey, in 'Journal of + Horticulture,' Dec. 1, 1863, p. 430.</p> + + <p><a name="Nt_584" href="#NtA_584">[584]</a> 'On Naval Timber,' 1831, p. + 107.</p> + + <p><a name="Nt_585" href="#NtA_585">[585]</a> Mr. Baily, in 'The Poultry + Chronicle,' vol. ii., 1854, p. 150. Also vol. i. p. 342; vol. iii. p. + 245.</p> + + <p><a name="Nt_586" href="#NtA_586">[586]</a> 'Cottage Gardener,' 1855, + December, p. 171; 1856, January, pp. 248, 323.</p> + + <p><a name="Nt_587" href="#NtA_587">[587]</a> 'Ueber Shorthorn Rindvieh,' + 1857, s. 51.</p> + + <p><a name="Nt_588" href="#NtA_588">[588]</a> 'The Veterinary,' vol. + xiii. p. 720. For the Glamorganshire cattle, <i>see</i> Youatt on Cattle, + p. 51.</p> + + <p><a name="Nt_589" href="#NtA_589">[589]</a> J. M. Eaton, 'A Treatise on + Fancy Pigeons,' p. 82; Ferguson, on 'Rare and Prize Poultry,' p. 162; Mr. + Brent, in 'Cottage Gardener,' Oct. 1860. p. 13.</p> + + <p><a name="Nt_590" href="#NtA_590">[590]</a> 'Die Racen des Schweines,' + 1860, s. 48.</p> + + <p><a name="Nt_591" href="#NtA_591">[591]</a> <i>See</i> some good + remarks on this head by M. de Quatrefages, 'Unité de l'Espèce Humaine,' + 1861, p. 119.</p> + + <p><a name="Nt_592" href="#NtA_592">[592]</a> Verlot, 'Des Variétés,' + 1865, p. 94.</p> + + <p><a name="Nt_593" href="#NtA_593">[593]</a> Mr. Patrick Sheriff, in + 'Gard. Chronicle,' 1858, p. 771.</p> + + <p><a name="Nt_594" href="#NtA_594">[594]</a> 'Pomologie Physiolog.,' + 1830, p. 106.</p> + + <p><a name="Nt_595" href="#NtA_595">[595]</a> Youatt on Sheep, p. + 521.</p> + + <p><a name="Nt_596" href="#NtA_596">[596]</a> 'A Treatise on the Almond + Tumbler,' p. i.</p> + + <p><a name="Nt_597" href="#NtA_597">[597]</a> M. J. de Jonghe, in 'Gard. + Chron.,' 1858, p. 173.</p> + + <p><a name="Nt_598" href="#NtA_598">[598]</a> Max. Müller, 'Science of + Language,' 1861, p. 223.</p> + + <p><a name="Nt_599" href="#NtA_599">[599]</a> Youatt on Cattle, pp. 116, + 128.</p> + + <p><a name="Nt_600" href="#NtA_600">[600]</a> 'Domesticated Animals,' p. + 188.</p> + + <p><a name="Nt_601" href="#NtA_601">[601]</a> Volz, 'Beiträge zur + Kulturgeschichte,' 1852, s. 99 <i>et passim</i>.</p> + + <p><a name="Nt_602" href="#NtA_602">[602]</a> Blaine, 'Encyclop. of Rural + Sports,' p. 213.</p> + + <p><a name="Nt_603" href="#NtA_603">[603]</a> 'Des Jacinthes,' &c., + Amsterdam, 1768, p. 43; Verlot, 'Des Variétés,' &c., p. 86. On the + reindeer, <i>see</i> Linnæus, 'Tour in Lapland,' translated by Sir J. E. + Smith, vol. i. p. 314. The statement in regard to German shepherds is + given on the authority of Dr. Weinland.</p> + + <p><a name="Nt_604" href="#NtA_604">[604]</a> Müller's 'Physiology,' Eng. + translation, vol. ii. p. 1662. With respect to the similarity of twins in + constitution, Dr. William Ogle has given me the following extract from + Professor Trousseau's Lectures ('Clinique Médicale,' tom. i. p. 523), in + which a curious case is recorded:—"J'ai donné mes soins à deux + frères jumeaux, tous deux si extraordinairement ressemblants qu'il + m'était impossible de les reconnaître, à moins de les voir l'un à côté de + l'autre. Cette ressemblance physique s'étendait plus loin: ils avaient, + permettez-moi l'expression, une similitude pathologique plus remarquable + encore. Ainsi l'un d'eux que je voyais aux néothermes à Paris malade + d'une ophthalmie rhumatismale me disait, 'En ce moment mon frère doit + avoir une ophthalmie comme la mienne;' et comme je m'étais récrié, il me + montrait quelques jours après une lettre qu'il venait de recevoir de ce + frère alors à Vienne, et qui lui écrivait en effet—'J'ai mon + ophthalmie, tu dois avoir la tienne.' Quelque singulier que ceci puisse + paraître, le fait non est pas moins exact: on ne me l'a pas raconté, je + l'ai vu, et j'en ai vu d'autres analogues dans ma pratique. Ces deux + jumeaux étaient aussi tous deux asthmatiques, et asthmatiques à un + effroyable degré. Originaires de Marseille, ils n'ont jamais pu demeurer + dans cette ville, où leurs intérêts les appelaient souvent, sans être + pris de leurs accès; jamais ils n'en éprouvaient à Paris. Bien mieux, il + leur suffisait de gagner Toulon pour être guéris de leurs attaques de + Marseilles. Voyageant sans cesse et dans tous pays pour leurs affaires, + ils avaient remarqué que certaines localités leur étaient funestes, que + dans d'autres ils étaient exempts de tout phénomène d'oppression."</p> + + <p><a name="Nt_605" href="#NtA_605">[605]</a> Isid. Geoffroy St. Hilaire, + 'Hist. des Anomalies,' tom. iii. p. 352; Moquin Tandon, 'Tératologie + Végétale,' 1841, p. 115.</p> + + <p><a name="Nt_606" href="#NtA_606">[606]</a> Metzger, 'Die + Getreidearten,' 1841, s. 39.</p> + + <p><a name="Nt_607" href="#NtA_607">[607]</a> On the date-palm, + <i>see</i> Vogel, 'Annals and Mag. of Nat. Hist.,' 1854, p. 460. On + Indian varieties, Dr. F. Hamilton, 'Transact. Linn. Soc.,' vol. xiv. p. + 296. On the varieties cultivated in Tahiti, <i>see</i> Dr. Bennett, in + Loudon's 'Mag. of N. Hist.,' vol. v., 1832, p. 484. Also Ellis, + 'Polynesian Researches,' vol. i. pp. 375, 370. On twenty varieties of the + Pandanus and other trees in the Marianne Island, <i>see</i> 'Hooker's + Miscellany,' vol. i. p. 308. On the bamboo in China, <i>see</i> Huc's + 'Chinese Empire,' vol. ii. p. 307.</p> + + <p><a name="Nt_608" href="#NtA_608">[608]</a> 'Treatise on the Culture of + the Apple,' &c., p. 3.</p> + + <p><a name="Nt_609" href="#NtA_609">[609]</a> Gallesio, 'Teoria della + Riproduzione Veg.,' p. 125.</p> + + <p><a name="Nt_610" href="#NtA_610">[610]</a> <i>See</i> Dr. Hooker's + Memoir on Arctic Plants in 'Linn. Transact.,' vol. xxiii, part ii. Mr. + Woodward, and a higher authority cannot be quoted, speaks of the Arctic + mollusca (in his 'Rudimentary Treatise,' 1856, p. 355) as remarkably + subject to variation.</p> + + <p><a name="Nt_611" href="#NtA_611">[611]</a> Bechstein, in his + 'Naturgeschichte der Stubenvögel,' 1840, s. 238, has some good remarks on + this subject. He states that his canary-birds varied in colour, though + kept on uniform food.</p> + + <p><a name="Nt_612" href="#NtA_612">[612]</a> 'The Plant,' by Schleiden, + translated by Henfrey, 1848, p. 169. <i>See</i> also Alex. Braun, in + 'Bot. Memoirs,' Ray. Soc., 1853, p. 313.</p> + + <p><a name="Nt_613" href="#NtA_613">[613]</a> Messrs. Hardy and Son, of + Maldon, in 'Gard. Chronicle,' 1856, p. 458.</p> + + <p><a name="Nt_614" href="#NtA_614">[614]</a> 'Quadrupèdes du Paraguay,' + 1801, tom. ii. p. 319.</p> + + <p><a name="Nt_615" href="#NtA_615">[615]</a> M<sup>c</sup>Clelland on + Indian Cyprinidæ, 'Asiatic Researches,' vol. xix. part ii., 1839, pp. + 266, 268, 313.</p> + + <p><a name="Nt_616" href="#NtA_616">[616]</a> Quoted by Sageret, 'Pom. + Phys.,' 1830, p. 43.</p> + + <p><a name="Nt_617" href="#NtA_617">[617]</a> 'The Fruits of America,' + 1845, p. 5.</p> + + <p><a name="Nt_618" href="#NtA_618">[618]</a> M. Cardan, in 'Comptes + Rendus,' Dec. 1848, quoted in 'Gard. Chronicle,' 1849, p. 101.</p> + + <p><a name="Nt_619" href="#NtA_619">[619]</a> M. Alexis Jordan mentions + four excellent pears found in woods in France, and alludes to others + ('Mém. Acad. de Lyon,' tom. ii. 1852, p. 159). Poiteau's remark is quoted + in 'Gardener's Mag.,' vol. iv., 1828, p. 385. <i>See</i> 'Gard. + Chronicle,' 1862, p. 335, for another case of a new variety of the pear + found in a hedge in France. Also for another case, <i>see</i> Loudon's + 'Encyclop. of Gardening,' p. 901. Mr. Rivers has given me similar + information.</p> + + <p><a name="Nt_620" href="#NtA_620">[620]</a> Duval, 'Hist. du Poirier,' + 1849, p. 2.</p> + + <p><a name="Nt_621" href="#NtA_621">[621]</a> I infer that this is the + fact from Van Mons' statement ('Arbres Fruitiers,' 1835, tom. i. p. 446) + that he finds in the woods seedlings resembling all the chief cultivated + races of both the pear and apple. Van Mons, however, looked at these wild + varieties as aboriginal species.</p> + + <p><a name="Nt_622" href="#NtA_622">[622]</a> Downing, 'Fruit-trees of + North America,' p. 422; Foley, in 'Transact. Hort. Soc.,' vol. vi. p. + 412.</p> + + <p><a name="Nt_623" href="#NtA_623">[623]</a> 'Gard. Chronicle,' 1847, p. + 244.</p> + + <p><a name="Nt_624" href="#NtA_624">[624]</a> 'Gardener's Chronicle,' + 1841, p. 383; 1850, p. 700; 1854, p. 650.</p> + + <p><a name="Nt_625" href="#NtA_625">[625]</a> 'Die Getreidearten,' 1843, + s. 66, 116, 117.</p> + + <p><a name="Nt_626" href="#NtA_626">[626]</a> Sabine, in 'Hort. + Transact.,' vol. iii. p. 225; Bronn, 'Geschichte der Natur,' b. ii. s. + 119.</p> + + <p><a name="Nt_627" href="#NtA_627">[627]</a> 'Journal of Horticulture,' + 1861, p. 112; on Zinnia, 'Gardener's Chronicle,' 1860, p. 852.</p> + + <p><a name="Nt_628" href="#NtA_628">[628]</a> 'The Chrysanthemum, its + History, &c.,' 1865, p. 3.</p> + + <p><a name="Nt_629" href="#NtA_629">[629]</a> 'Gardener's Chron.,' 1855, + p. 54; 'Journal of Horticulture,' May 9, 1865, p. 363.</p> + + <p><a name="Nt_630" href="#NtA_630">[630]</a> Quoted by Verlot, 'Des + Variétés,' &c., 1865, p. 28.</p> + + <p><a name="Nt_631" href="#NtA_631">[631]</a> 'Examination of the + Characteristics of Genera and Species:' Charleston, 1855, p. 14.</p> + + <p><a name="Nt_632" href="#NtA_632">[632]</a> Mr Hewitt, 'Journal of + Hort.,' 1863, p. 39.</p> + + <p><a name="Nt_633" href="#NtA_633">[633]</a> Devay, 'Mariages + Consanguins,' pp. 97, 125. In conversation I have found two or three + naturalists of the same opinion.</p> + + <p><a name="Nt_634" href="#NtA_634">[634]</a> Müller has conclusively + argued against this belief, 'Elements of Phys.,' Eng. translat., vol. + ii., 1842, p. 1405.</p> + + <p><a name="Nt_635" href="#NtA_635">[635]</a> 'Act. Acad. St. + Petersburg,' 1780, part ii. p. 84, &c.</p> + + <p><a name="Nt_636" href="#NtA_636">[636]</a> 'Bastarderzeugung,' s. 249, + 255, 295.</p> + + <p><a name="Nt_637" href="#NtA_637">[637]</a> 'Nova Acta, St. + Petersburg,' 1794, p. 378; 1795, pp. 307, 313, 316; 1787, p. 407.</p> + + <p><a name="Nt_638" href="#NtA_638">[638]</a> 'De la Fécondation,' 1862, + p. 311.</p> + + <p><a name="Nt_639" href="#NtA_639">[639]</a> 'Amaryllidaceæ,' 1837, p. + 362.</p> + + <p><a name="Nt_640" href="#NtA_640">[640]</a> Abstracted in 'Gard. + Chronicle,' 1860, p. 1081.</p> + + <p><a name="Nt_641" href="#NtA_641">[641]</a> This was the opinion of the + elder De Candolle, as quoted in 'Dic. Class. d'Hist. Nat.,' tom. viii. p. + 405. Puvis, in his work, 'De la Dégénération,' 1837, p. 37, has discussed + this same point.</p> + + <p><a name="Nt_642" href="#NtA_642">[642]</a> 'Comptes Rendus,' Novembre + 21, 1864, p. 838.</p> + + <p><a name="Nt_643" href="#NtA_643">[643]</a> 'Nova Acta, St. + Petersburg,' 1794, p. 391.</p> + + <p><a name="Nt_644" href="#NtA_644">[644]</a> 'Bastarderzeugung,' s. 507, + 516, 572.</p> + + <p><a name="Nt_645" href="#NtA_645">[645]</a> 'Die Bastardbefruchtung,' + &c., 1865, s. 24.</p> + + <p><a name="Nt_646" href="#NtA_646">[646]</a> 'Bastarderzeugung,' s. 452, + 507.</p> + + <p><a name="Nt_647" href="#NtA_647">[647]</a> 'Die Bastardbefruchtung,' + s. 56.</p> + + <p><a name="Nt_648" href="#NtA_648">[648]</a> 'Bastarderzeugung,' s. + 423.</p> + + <p><a name="Nt_649" href="#NtA_649">[649]</a> 'Dritte Fortsetzung,' + &c., 1766, s. 85.</p> + + <p><a name="Nt_650" href="#NtA_650">[650]</a> 'Die Bastardbefruchtung,' + &c., 1865, s. 92; <i>see</i> also the Rev. M. J. Berkeley on the same + subject, in 'Journal of Royal Hort. Soc.,' 1866, p. 80.</p> + + <p><a name="Nt_651" href="#NtA_651">[651]</a> Dr. P. Lucas has given a + history of opinion on this subject: 'Héréd. Nat.,' 1847, tom. i. p. + 175.</p> + + <p><a name="Nt_652" href="#NtA_652">[652]</a> 'Hist. des Anomalies,' tom. + iii. p. 499.</p> + + <p><a name="Nt_653" href="#NtA_653">[653]</a> Idem., tom. iii. pp. 392, + 502.</p> + + <p><a name="Nt_654" href="#NtA_654">[654]</a> <i>See</i> his interesting + work, 'Métamorphoses de l'Homme,' &c., 1862, p. 129.</p> + + <p><a name="Nt_655" href="#NtA_655">[655]</a> 'Dritte Fortsetzung,' + &c., s. 123; 'Bastarderzeugung,' s. 249.</p> + + <p><a name="Nt_656" href="#NtA_656">[656]</a> 'Gardener's Chronicle,' + 1853, p. 183.</p> + + <p><a name="Nt_657" href="#NtA_657">[657]</a> Mr. Wildman, 'Floricultural + Soc.,' Feb. 7, 1843, reported in 'Gard. Chron.,' 1843, p. 86.</p> + + <p><a name="Nt_658" href="#NtA_658">[658]</a> Mr. Robson, in 'Journal of + Horticulture,' Feb. 13th, 1866, p. 122.</p> + + <p><a name="Nt_659" href="#NtA_659">[659]</a> 'Journal of Horticulture,' + 1861, p. 24.</p> + + <p><a name="Nt_660" href="#NtA_660">[660]</a> Ibid., 1862, p. 83.</p> + + <p><a name="Nt_661" href="#NtA_661">[661]</a> 'Gard. Chron.,' 1845, p. + 660.</p> + + <p><a name="Nt_662" href="#NtA_662">[662]</a> Ibid., 1863, p. 628.</p> + + <p><a name="Nt_663" href="#NtA_663">[663]</a> 'Journal of Hort.,' 1861, + pp. 64, 309.</p> + + <p><a name="Nt_664" href="#NtA_664">[664]</a> 'Des Variétés,' &c., p. + 76.</p> + + <p><a name="Nt_665" href="#NtA_665">[665]</a> Engel, 'Sur les Prop. + Médicales des Plantes,' 1860, pp. 10, 25. On changes in the odours of + plants, <i>see</i> Dalibert's Experiments, quoted by Beckman, + 'Inventions,' vol. ii. p. 344; and Nees, in Ferussac, 'Bull. des Sc. + Nat.,' 1824, tom. i. p. 60. With respect to the rhubarb, &c., + <i>see</i> also 'Gardener's Chronicle,' 1849, p. 355; 1862, p. 1123.</p> + + <p><a name="Nt_666" href="#NtA_666">[666]</a> Hooker, 'Flora Indica,' p. + 32.</p> + + <p><a name="Nt_667" href="#NtA_667">[667]</a> Naudin, 'Annales des Sc. + Nat.,' 4th series, Bot., tom. xi., 1859, p. 81. 'Gardener's Chronicle,' + 1859, p. 464.</p> + + <p><a name="Nt_668" href="#NtA_668">[668]</a> Moorcroft's 'Travels,' + &c., vol. ii. p. 143.</p> + + <p><a name="Nt_669" href="#NtA_669">[669]</a> 'Gardener's Chronicle,' + 1861, p. 1113.</p> + + <p><a name="Nt_670" href="#NtA_670">[670]</a> Royle, 'Productive + Resources of India,' p. 59.</p> + + <p><a name="Nt_671" href="#NtA_671">[671]</a> 'Personal Narrative,' Eng. + translat., vol. v. p. 101. This statement has been confirmed by Karsten + ('Beitrag zur Kenntniss der Rhynchoprion:' Moscow, 1864. s. 39), and by + others.</p> + + <p><a name="Nt_672" href="#NtA_672">[672]</a> 'Organic Chemistry,' Eng. + translat., 1st edit., p. 369.</p> + + <p><a name="Nt_673" href="#NtA_673">[673]</a> Prichard, 'Phys. Hist. of + Mankind,' 1851, vol. i. p. 155.</p> + + <p><a name="Nt_674" href="#NtA_674">[674]</a> Darwin, 'Journal of + Researches,' 1845, p. 434.</p> + + <p><a name="Nt_675" href="#NtA_675">[675]</a> These statements on disease + are taken from Dr. Boudin's 'Géographie et de Statistique Médicales,' + 1857, tom. i. p. xliv. and lii.; tom. ii. p. 315.</p> + + <p><a name="Nt_676" href="#NtA_676">[676]</a> E. Desor, quoted in the + 'Anthrop. Rev.,' 1863, p. 180. For much confirmatory evidence, <i>see</i> + Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 131.</p> + + <p><a name="Nt_677" href="#NtA_677">[677]</a> 'Ceylon,' by Sir J. E. + Tennent, vol. i., 1859, p. 89.</p> + + <p><a name="Nt_678" href="#NtA_678">[678]</a> Godron, 'De l'Espèce,' tom. + ii. p. 52.</p> + + <p><a name="Nt_679" href="#NtA_679">[679]</a> 'Journal of Horticultural + Soc.,' vol. vii., 1852, p. 117.</p> + + <p><a name="Nt_680" href="#NtA_680">[680]</a> 'Journal of Hort. Soc.,' + vol. i. p. 160.</p> + + <p><a name="Nt_681" href="#NtA_681">[681]</a> <i>See</i> Lecoq on the + Villosity of Plants, 'Geograph. Bot.,' tom. iii. pp. 287, 291; Gärtner, + 'Bastarderz.,' s. 261; Mr. Musters, on the Opuntia, in 'Gard. Chronicle,' + 1846, p. 444.</p> + + <p><a name="Nt_682" href="#NtA_682">[682]</a> 'Pom. Phys.,' p. 136.</p> + + <p><a name="Nt_683" href="#NtA_683">[683]</a> 'Ampelographie,' 1849, p. + 19.</p> + + <p><a name="Nt_684" href="#NtA_684">[684]</a> Gärtner, 'Bastarderz.,' s. + 606, has collected nearly all recorded facts. Andrew Knight (in + 'Transact. Hort. Soc.,' vol. ii. p. 160) goes so far as to maintain that + few varieties are absolutely permanent in character when propagated by + buds or grafts.</p> + + <p><a name="Nt_685" href="#NtA_685">[685]</a> Mr. Blyth, in 'Annals and + Mag. of Nat. Hist.,' vol. xx., 1847, p. 391.</p> + + <p><a name="Nt_686" href="#NtA_686">[686]</a> 'Natural History Review,' + 1862, p. 113.</p> + + <p><a name="Nt_687" href="#NtA_687">[687]</a> 'Journal of Roy. + Geographical Soc.,' vol. ix., 1839, p. 275.</p> + + <p><a name="Nt_688" href="#NtA_688">[688]</a> 'Travels in Bokhara,' vol. + iii. p. 151.</p> + + <p><a name="Nt_689" href="#NtA_689">[689]</a> <i>See</i> also, on the + influence of marshy pastures on the wool, Godron, 'L'Espèce,' tom. ii. p. + 22.</p> + + <p><a name="Nt_690" href="#NtA_690">[690]</a> Isidore Geoffroy St. + Hilaire, 'Hist. Nat. Gén.,' tom. iii. p. 438.</p> + + <p><a name="Nt_691" href="#NtA_691">[691]</a> Azara has made some good + remarks on this subject, 'Quadrupèdes du Paraguay,' tom. ii. p. 337. + <i>See</i> an account of a family of naked mice produced in England, + 'Proc. Zoolog. Soc.,' 1856, p. 38.</p> + + <p><a name="Nt_692" href="#NtA_692">[692]</a> 'Die Fauna der + Pfahlbauten,' 1861, s. 15.</p> + + <p><a name="Nt_693" href="#NtA_693">[693]</a> 'Schweinschædel,' 1864, s. + 99.</p> + + <p><a name="Nt_694" href="#NtA_694">[694]</a> 'Travels in Siberia,' Eng. + translat., vol. i. p. 228.</p> + + <p><a name="Nt_695" href="#NtA_695">[695]</a> A. R. Wallace, 'Travels on + the Amazon and Rio Negro,' p. 294.</p> + + <p><a name="Nt_696" href="#NtA_696">[696]</a> 'Naturgeschichte der + Stubenvögel,' 1840, s. 262, 308.</p> + + <p><a name="Nt_697" href="#NtA_697">[697]</a> 'Hist. Nat. Gén.,' tom. + iii. p. 402.</p> + + <p><a name="Nt_698" href="#NtA_698">[698]</a> 'Bull. de la Soc. Imp. + d'Acclimat.,' tom. viii. p. 351.</p> + + <p><a name="Nt_699" href="#NtA_699">[699]</a> <i>See</i> an account of + Mr. Gregson's experiments on the <i>Abraxus grossulariata</i>, 'Proc. + Entomolog. Soc.,' Jan. 6th, 1862: these experiments have been confirmed + by Mr. Greening, in 'Proc. of the Northern Entomolog. Soc.,' July 28th, + 1862. For the effects of food on caterpillars, see a curious account by + M. Michely, in 'Bull. de la Soc. Imp. d'Acclimat.,' tom. viii. p. 563. + For analogous facts from Dahlbom on Hymenoptera, <i>see</i> Westwood's + 'Modern Class. of Insects,' vol. ii. p. 98. <i>See</i> also Dr. L. + Möller, 'Die Abhängigkeit der Insecten,' 1867, s. 70.</p> + + <p><a name="Nt_700" href="#NtA_700">[700]</a> 'The Principles of + Biology,' vol. ii. 1866. The present chapters were written before I had + read Mr. Herbert Spencer's work, so that I have not been able to make so + much use of it as I should otherwise probably have done.</p> + + <p><a name="Nt_701" href="#NtA_701">[701]</a> 'Proc. Acad. Nat. Soc. of + Philadelphia,' Jan. 28th, 1862.</p> + + <p><a name="Nt_702" href="#NtA_702">[702]</a> <i>See</i> Mr. B. D. + Walsh's excellent papers in 'Proc. Entomolog. Soc. Philadelphia,' Dec. + 1866, p. 284. With respect to the willow, <i>see</i> idem, 1864, p. + 546.</p> + + <p><a name="Nt_703" href="#NtA_703">[703]</a> <i>See</i> his admirable + Histoire des Galles, in 'Annal. des Sc. Nat. Bot.,' 3rd series, tom. + xix., 1853, p. 273.</p> + + <p><a name="Nt_704" href="#NtA_704">[704]</a> Kirby and Spence's + 'Entomology,' 1818, vol. i. p. 450; Lucaze-Duthiers, idem, p. 284.</p> + + <p><a name="Nt_705" href="#NtA_705">[705]</a> 'Proc. Entomolog. Soc. + Philadelphia,' 1864, p. 558.</p> + + <p><a name="Nt_706" href="#NtA_706">[706]</a> Mr. B. D. Walsh, idem, p. + 633; and Dec. 1866, p. 275.</p> + + <p><a name="Nt_707" href="#NtA_707">[707]</a> Mr. B. D. Walsh, idem, + 1864, p. 545, 411, 495; and Dec. 1866, p. 278. <i>See</i> also + Lucaze-Duthiers.</p> + + <p><a name="Nt_708" href="#NtA_708">[708]</a> Lucaze-Duthiers, idem, pp. + 325, 328.</p> + + <p><a name="Nt_709" href="#NtA_709">[709]</a> 'Linnæa,' vol. xvii., 1843; + quoted by Dr. M. T. Masters, Royal Institution, March 16th, 1860.</p> + + <p><a name="Nt_710" href="#NtA_710">[710]</a> Hewett C. Watson, 'Cybele + Britannica,' vol. i., 1847, p. 11.</p> + + <p><a name="Nt_711" href="#NtA_711">[711]</a> 'Gardener's Chronicle,' + 1857, p. 629.</p> + + <p><a name="Nt_712" href="#NtA_712">[712]</a> 'Mémoire sur la Production + Artificielle des Monstrosités,' 1862, pp. 8-12; 'Recherches sur les + Conditions, &c., chez les Monstres,' 1863, p. 6. An abstract is given + of Geoffroy's Experiments by his son, in his 'Vie, Travaux, &c.,' + 1847, p. 290.</p> + + <p><a name="Nt_713" href="#NtA_713">[713]</a> Paget, 'Lectures on + Surgical Pathology,' 1853, vol. i. p. 483.</p> + + <p><a name="Nt_714" href="#NtA_714">[714]</a> 'Researches upon the Venom + of the Rattle-snake,' Jan. 1861, by Dr. Mitchell, p. 67.</p> + + <p><a name="Nt_715" href="#NtA_715">[715]</a> Mr. Sedgwick, in 'British + and Foreign Medico-Chirurg. Review,' July 1863, p. 175.</p> + + <p><a name="Nt_716" href="#NtA_716">[716]</a> 'An Essay on Generation,' + Eng. translat., p. 18; Paget, 'Lectures on Surgical Pathology,' 1853, + vol. i. p. 209.</p> + + <p><a name="Nt_717" href="#NtA_717">[717]</a> 'An Essay on Animal + Reproduction,' Eng. translat., 1769, p. 79.</p> + + <p><a name="Nt_718" href="#NtA_718">[718]</a> Carpenter's 'Principles of + Comp. Physiology,' 1854, p. 479.</p> + + <p><a name="Nt_719" href="#NtA_719">[719]</a> Charlesworth's 'Mag. of + Nat. Hist.,' vol. i., 1837, p. 145.</p> + + <p><a name="Nt_720" href="#NtA_720">[720]</a> Paget, 'Lectures on + Surgical Pathology,' vol. i. p. 239.</p> + + <p><a name="Nt_721" href="#NtA_721">[721]</a> Quoted by Carpenter, 'Comp. + Phys.,' p. 479.</p> + + <p><a name="Nt_722" href="#NtA_722">[722]</a> Paget, 'Lectures,' &c., + p. 257.</p> + + <p><a name="Nt_723" href="#NtA_723">[723]</a> These cases are given by + Blumenbach in his 'Essay on Generation,' pp. 52, 54.</p> + + <p><a name="Nt_724" href="#NtA_724">[724]</a> 'Cellular Pathology,' + trans. by Dr. Chance, 1860, pp. 27, 441.</p> + + <p><a name="Nt_725" href="#NtA_725">[725]</a> Paget, 'Lectures on + Pathology,' vol. i., 1853, p. 357.</p> + + <p><a name="Nt_726" href="#NtA_726">[726]</a> Paget, idem, p. 150.</p> + + <p><a name="Nt_727" href="#NtA_727">[727]</a> 'The Principles of + Biology,' vol. ii., 1866, chap. 3-5.</p> + + <p><a name="Nt_728" href="#NtA_728">[728]</a> 'Lectures on Pathology,' + 1853, vol. i. p. 71.</p> + + <p><a name="Nt_729" href="#NtA_729">[729]</a> 'Comptes Rendus,' Sept. + 26th, 1864, p. 539.</p> + + <p><a name="Nt_730" href="#NtA_730">[730]</a> 'The Principles of + Biology,' vol. ii. p. 243.</p> + + <p><a name="Nt_731" href="#NtA_731">[731]</a> Idem, vol. ii. p. 269.</p> + + <p><a name="Nt_732" href="#NtA_732">[732]</a> Idem, vol. ii. p. 273.</p> + + <p><a name="Nt_733" href="#NtA_733">[733]</a> Paget, 'Lectures on + Pathology,' vol. ii. p. 209.</p> + + <p><a name="Nt_734" href="#NtA_734">[734]</a> Müller's 'Phys.,' Eng. + translat., pp. 54, 791. Prof. Reed has given ('Physiological and Anat. + Researches,' p. 10) a curious account of the atrophy of the limbs of + rabbits after the destruction of the nerve.</p> + + <p><a name="Nt_735" href="#NtA_735">[735]</a> Quoted by Lecoq, in + 'Geograph. Bot.,' tom. i., 1854, p. 182.</p> + + <p><a name="Nt_736" href="#NtA_736">[736]</a> 'Das Abändern der Vögel,' + 1833, s. 74.</p> + + <p><a name="Nt_737" href="#NtA_737">[737]</a> Nathusius, 'Die Racen des + Schweines,' 1860, s. 53, 57; 'Vorstudien ... Schweineschædel,' 1864, s. + 103, 130, 133.</p> + + <p><a name="Nt_738" href="#NtA_738">[738]</a> 'Journal of Agriculture of + Highland Soc.,' July, 1860, p. 321.</p> + + <p><a name="Nt_739" href="#NtA_739">[739]</a> 'Principles of Biology,' + vol. ii. p. 263.</p> + + <p><a name="Nt_740" href="#NtA_740">[740]</a> 'Natural History Review,' + vol. iv., Oct. 1864, p. 617.</p> + + <p><a name="Nt_741" href="#NtA_741">[741]</a> 'Lectures on Surgical + Pathology,' 1853, vol. i. p. 27.</p> + + <p><a name="Nt_742" href="#NtA_742">[742]</a> Andersson, 'Travels in + South Africa,' p. 318. For analogous cases in South America, <i>see</i> + Aug. St. Hilaire, 'Voyage dans le Province de Goyaz,' tom. i. p. 71.</p> + + <p><a name="Nt_743" href="#NtA_743">[743]</a> <span class="correction" + title="Original reads `Birckell', corrected by errata, page viii." + >Brickell</span>'s 'Nat. Hist. of North Carolina,' 1739, p. 53.</p> + + <p><a name="Nt_744" href="#NtA_744">[744]</a> Livingstone, quoted by + Youatt on Sheep, p. 142. Hodgson, in 'Journal of Asiatic Soc. of Bengal,' + vol. xvi., 1847, p. 1006, &c. &c.</p> + + <p><a name="Nt_745" href="#NtA_745">[745]</a> 'Naturalist Library,' Dogs, + vol. ii. 1840, p. 104.</p> + + <p><a name="Nt_746" href="#NtA_746">[746]</a> 'De l'Espèce,' tom. i., + 1859, p. 367.</p> + + <p><a name="Nt_747" href="#NtA_747">[747]</a> 'Ceylon,' by Sir J. E. + Tennent, 1859, vol. ii. p. 531.</p> + + <p><a name="Nt_748" href="#NtA_748">[748]</a> For the foregoing + statements, <i>see</i> Hunter's 'Essays and Observations,' 1861, vol. ii. + p. 329; Dr. Edmondston, as quoted in Macgillivray's 'British Birds,' vol. + v. p. 550; Menetries, as quoted in Bronn's 'Geschichte der Natur,' B. ii. + s. 110.</p> + + <p><a name="Nt_749" href="#NtA_749">[749]</a> These statements on the + intestines are taken from Isidore Geoffroy St. Hilaire, 'Hist. Nat. + Gén.,' tom. iii. pp. 427, 441.</p> + + <p><a name="Nt_750" href="#NtA_750">[750]</a> Gilbert White, 'Nat. Hist. + Selbourne,' 1825, vol. ii. p. 121.</p> + + <p><a name="Nt_751" href="#NtA_751">[751]</a> Burdach, 'Traité de Phys.,' + tom. ii. p. 267, as quoted by Dr. P. Lucas, 'L'Héréd. Nat.,' tom. i. p. + 388.</p> + + <p><a name="Nt_752" href="#NtA_752">[752]</a> This and several other + cases are given by Colin, 'Physiologie Comp. des Animaux Dom.,' 1854, + tom. i. p. 426.</p> + + <p><a name="Nt_753" href="#NtA_753">[753]</a> M. Michely de Cayenne, in + 'Bull. Soc. d'Acclimat.,' tom. viii., 1861, p. 563.</p> + + <p><a name="Nt_754" href="#NtA_754">[754]</a> Quatrefages, 'Unité de + l'Espèce Humaine,' 1861, p. 79.</p> + + <p><a name="Nt_755" href="#NtA_755">[755]</a> 'Flora,' 1835, B. ii. p. + 504.</p> + + <p><a name="Nt_756" href="#NtA_756">[756]</a> Alph. De Candolle, + 'Géograph. Bot.,' tom. ii. p. 1078.</p> + + <p><a name="Nt_757" href="#NtA_757">[757]</a> Royle, 'Illustrations of + the Botany of the Himalaya,' p. 19.</p> + + <p><a name="Nt_758" href="#NtA_758">[758]</a> 'Gardener's Chronicle,' + 1850, pp. 204, 219.</p> + + <p><a name="Nt_759" href="#NtA_759">[759]</a> Rev. R. Everest, 'Journal + As. Soc. of Bengal,' vol. iii. p. 19.</p> + + <p><a name="Nt_760" href="#NtA_760">[760]</a> Youatt on Sheep, 1838, p. + 491.</p> + + <p><a name="Nt_761" href="#NtA_761">[761]</a> Royle, 'Prod. Resources of + India,' p. 153.</p> + + <p><a name="Nt_762" href="#NtA_762">[762]</a> Tegetmeier, 'Poultry Book,' + 1866, p. 102.</p> + + <p><a name="Nt_763" href="#NtA_763">[763]</a> Dr. R. Paterson, in a paper + communicated to Bot. Soc. of Canada, quoted in the 'Reader,' 1863. Nov. + 13th.</p> + + <p><a name="Nt_764" href="#NtA_764">[764]</a> <i>See</i> remarks by + Editor in 'Gard. Chronicle,' 1848, p. 5.</p> + + <p><a name="Nt_765" href="#NtA_765">[765]</a> 'Gard. Chronicle,' 1860, p. + 938. Remarks by Editor and quotation from Decaisne.</p> + + <p><a name="Nt_766" href="#NtA_766">[766]</a> J. de Jonghe, of Brussels, + in 'Gard. Chronicle,' 1857, p. 612.</p> + + <p><a name="Nt_767" href="#NtA_767">[767]</a> Ch. Martius, 'Voyage Bot. + Côtes Sept. de la Norvège,' p. 26.</p> + + <p><a name="Nt_768" href="#NtA_768">[768]</a> 'Journal de l'Acad. Hort. + de Gand,' quoted in 'Gard. Chron.,' 1859, p. 7.</p> + + <p><a name="Nt_769" href="#NtA_769">[769]</a> 'Gard. Chronicle,' 1851, p. + 396.</p> + + <p><a name="Nt_770" href="#NtA_770">[770]</a> Idem., 1862, p. 235.</p> + + <p><a name="Nt_771" href="#NtA_771">[771]</a> On the authority of Labat, + quoted in 'Gard. Chron.,' 1862, p. 235.</p> + + <p><a name="Nt_772" href="#NtA_772">[772]</a> MM. Edwards and Colin, + 'Annal. des Sc. Nat.,' 2nd series, Bot., tom. v. p. 22.</p> + + <p><a name="Nt_773" href="#NtA_773">[773]</a> 'Géograph. Bot.,' p. + 337.</p> + + <p><a name="Nt_774" href="#NtA_774">[774]</a> 'Swedish Acts,' Eng. + translat., 1739-40, vol. i. Kalm, in his 'Travels,' vol. ii. p. 166, + gives an analogous case with cotton-plants raised in New Jersey from + Carolina seed.</p> + + <p><a name="Nt_775" href="#NtA_775">[775]</a> De Candolle, 'Géograph. + Bot.,' p. 339.</p> + + <p><a name="Nt_776" href="#NtA_776">[776]</a> 'Gard. Chronicle,' 1862, p. + 235.</p> + + <p><a name="Nt_777" href="#NtA_777">[777]</a> Gallesio, 'Teoria della + Riproduzione Veg.,' 1816, p. 125; and 'Traité du Citrus,' 1811, p. + 359.</p> + + <p><a name="Nt_778" href="#NtA_778">[778]</a> 'Essai sur l'Hist. des + Orangers,' 1813, p. 20, &c.</p> + + <p><a name="Nt_779" href="#NtA_779">[779]</a> Alph. De Candolle, + 'Géograph. Bot.,' p. 882.</p> + + <p><a name="Nt_780" href="#NtA_780">[780]</a> 'Ch. Darwin's Lehre von der + Entstehung,' &c., 1862, s. 87.</p> + + <p><a name="Nt_781" href="#NtA_781">[781]</a> Decaisne, quoted in 'Gard. + Chronicle,' 1865, p. 271.</p> + + <p><a name="Nt_782" href="#NtA_782">[782]</a> For the magnolia, + <i>see</i> Loudon's 'Gard. Mag.,' vol. xiii., 1837, p. 21. For camellias + and roses, <i>see</i> 'Gard. Chron.,' 1860, p. 384. For the yew, 'Journal + of Hort.,' March 3rd, 1863, p. 174. For sweet potatoes, <i>see</i> Col. + von Siebold, in 'Gard. Chron.,' 1855, p. 822.</p> + + <p><a name="Nt_783" href="#NtA_783">[783]</a> The Editor, 'Gard. Chron.,' + 1861, p. 239.</p> + + <p><a name="Nt_784" href="#NtA_784">[784]</a> Loudon's 'Gard. Mag.,' vol. + xii., 1836, p. 378.</p> + + <p><a name="Nt_785" href="#NtA_785">[785]</a> 'Gardeners Chron.,' 1865, + p. 699.</p> + + <p><a name="Nt_786" href="#NtA_786">[786]</a> 'Arboretum et Fruticetum,' + vol. iii. p. 1376.</p> + + <p><a name="Nt_787" href="#NtA_787">[787]</a> Mr. Robson, in 'Journal of + Horticulture,' 1861, p. 23.</p> + + <p><a name="Nt_788" href="#NtA_788">[788]</a> Dr. Bonavia, 'Report of the + Agri.-Hort. Soc. of Oudh,' 1866.</p> + + <p><a name="Nt_789" href="#NtA_789">[789]</a> 'Cottage Gardener,' 1860, + April, 24th, p. 57.</p> + + <p><a name="Nt_790" href="#NtA_790">[790]</a> 'Gardener's Chronicle,' + 1841, p. 291.</p> + + <p><a name="Nt_791" href="#NtA_791">[791]</a> Mr. Beaton, in 'Cottage + Gardener,' March 20th, 1860, p. 377. Queen Mab will also stand stove + heat, <i>see</i> 'Gard. Chronicle,' 1845, p. 226.</p> + + <p><a name="Nt_792" href="#NtA_792">[792]</a> 'Gardener's Chronicle,' + 1841, p. 439.</p> + + <p><a name="Nt_793" href="#NtA_793">[793]</a> Quoted by Asa Gray, in 'Am. + Journ. of Sci.,' 2nd series, Jan. 1865, p. 106.</p> + + <p><a name="Nt_794" href="#NtA_794">[794]</a> For China, <i>see</i> + 'Mémoire sur les Chinois,' tom, xi., 1786, p. 60. Columella is quoted by + Carlier, in 'Journal de Physique,' tom. xxiv. 1784.</p> + + <p><a name="Nt_795" href="#NtA_795">[795]</a> Messrs. Hardy and Son, in + 'Gard. Chronicle,' 1856, p. 589.</p> + + <p><a name="Nt_796" href="#NtA_796">[796]</a> Isid. Geoffroy St. Hilaire, + 'Hist. Nat. des Anomalies,' 1836, tom. ii. pp. 210, 223, 224, 395; + 'Philosoph. Transact.,' 1775, p. 313.</p> + + <p><a name="Nt_797" href="#NtA_797">[797]</a> Pallas, quoted by Youatt on + Sheep, p. 25.</p> + + <p><a name="Nt_798" href="#NtA_798">[798]</a> Youatt on Cattle, 1834, p. + 174.</p> + + <p><a name="Nt_799" href="#NtA_799">[799]</a> 'Encyclop. Méthod.,' 1820, + p. 483: <i>see</i> p. 500, on the Indian zebu casting its horns. Similar + cases in European cattle were given in the third chapter.</p> + + <p><a name="Nt_800" href="#NtA_800">[800]</a> Pallas, 'Travels,' Eng. + translat., vol. i. p. 243.</p> + + <p><a name="Nt_801" href="#NtA_801">[801]</a> Mr. Beaton, in 'Journal of + Horticulture,' May 21, 1861, p. 133.</p> + + <p><a name="Nt_802" href="#NtA_802">[802]</a> Lecoq, 'De la Fécondation,' + 1862, p. 233.</p> + + <p><a name="Nt_803" href="#NtA_803">[803]</a> 'Annales du Muséum,' tom. + vi. p. 319.</p> + + <p><a name="Nt_804" href="#NtA_804">[804]</a> 'Hist. des Anomalies,' tom. + iii. p. 392. Prof. Huxley applies the same principle in accounting for + the remarkable, though normal, differences in the arrangement of the + nervous system in the Mollusca, in his great paper on the Morphology of + the Cephalous Mollusca, in 'Phil. Transact.,' 1853, p. 56.</p> + + <p><a name="Nt_805" href="#NtA_805">[805]</a> 'Eléments de Tératologie + Veg.,' 1841, p. 113.</p> + + <p><a name="Nt_806" href="#NtA_806">[806]</a> Prof. J. B. Simonds, on the + Age of the Ox, Sheep, &c., quoted in 'Gard. Chronicle,' 1854, p. + 588.</p> + + <p><a name="Nt_807" href="#NtA_807">[807]</a> 'Hist. des Anomalies,' tom. + i. p. 674.</p> + + <p><a name="Nt_808" href="#NtA_808">[808]</a> Quoted by Isid. Geoffroy, + idem, tom. i. p. 635.</p> + + <p><a name="Nt_809" href="#NtA_809">[809]</a> 'The Poultry Book,' by W. + B. Tegetmeier, 1866, p. 250.</p> + + <p><a name="Nt_810" href="#NtA_810">[810]</a> A. Walker on Intermarriage, + 1838, p. 160.</p> + + <p><a name="Nt_811" href="#NtA_811">[811]</a> 'The Farrier and + Naturalist,' vol. i., 1828, p. 456.</p> + + <p><a name="Nt_812" href="#NtA_812">[812]</a> Godron, 'Sur l'Espèce,' + tom. ii. p. 217.</p> + + <p><a name="Nt_813" href="#NtA_813">[813]</a> 'Quadrupèdes du Paraguay,' + tom. ii. p. 333.</p> + + <p><a name="Nt_814" href="#NtA_814">[814]</a> On Sheep, p. 142.</p> + + <p><a name="Nt_815" href="#NtA_815">[815]</a> 'Ueber Racen, Kreuzungen, + &c.,' 1825, s. 24.</p> + + <p><a name="Nt_816" href="#NtA_816">[816]</a> Quoted from Conolly, in + 'The Indian Field,' Feb. 1859, vol. ii. p. 266.</p> + + <p><a name="Nt_817" href="#NtA_817">[817]</a> 'Domesticated Animals of + the British Islands,' pp. 307, 368.</p> + + <p><a name="Nt_818" href="#NtA_818">[818]</a> 'Proceedings Zoolog. Soc.,' + 1833, p. 113.</p> + + <p><a name="Nt_819" href="#NtA_819">[819]</a> Sedgwick, 'Brit. and + Foreign Medico-Chirurg. Review,' April 1863, p. 453.</p> + + <p><a name="Nt_820" href="#NtA_820">[820]</a> 'Gard. Chronicle,' 1849, p. + 205.</p> + + <p><a name="Nt_821" href="#NtA_821">[821]</a> 'Embassy to the Court of + Ava,' vol. i. p. 320.</p> + + <p><a name="Nt_822" href="#NtA_822">[822]</a> 'Narrative of a Mission to + the Court of Ava in 1855,' p. 94.</p> + + <p><a name="Nt_823" href="#NtA_823">[823]</a> Those statements are taken + from Mr. Sedgwick, in the 'Medico-Chirurg. Review,' July 1861, p. 198; + April 1863, pp. 455 and 458. Liebreich is quoted by Professor Devay, in + his 'Mariages Consanguins,' 1862, p. 116.</p> + + <p><a name="Nt_824" href="#NtA_824">[824]</a> Loudon's 'Mag. of Nat. + Hist.,' vol. i., 1829, pp. 66, 178. <i>See</i> also Dr. P. Lucas, + 'L'Héréd. Nat.,' tom. i. p. 428, on the inheritance of deafness in + cats.</p> + + <p><a name="Nt_825" href="#NtA_825">[825]</a> 'Annales des Sc. Nat.' + Zoolog., 3rd series, 1847, tom. viii. p. 239.</p> + + <p><a name="Nt_826" href="#NtA_826">[826]</a> 'Gardener's Chron.,' 1864, + p. 1202.</p> + + <p><a name="Nt_827" href="#NtA_827">[827]</a> Verlot gives several other + instances, 'Des Variétés,' 1865, p. 72.</p> + + <p><a name="Nt_828" href="#NtA_828">[828]</a> 'Arbres Fruitiers,' 1836, + tom. ii. pp. 204, 226.</p> + + <p><a name="Nt_829" href="#NtA_829">[829]</a> 'Annales du Muséum,' tom. + xx. p. 188.</p> + + <p><a name="Nt_830" href="#NtA_830">[830]</a> 'Gardener's Chron.,' 1843, + p. 877.</p> + + <p><a name="Nt_831" href="#NtA_831">[831]</a> Ibid., 1845, p. 102.</p> + + <p><a name="Nt_832" href="#NtA_832">[832]</a> 'Hist. des Anomalies,' tom. + iii. p. 402. <i>See</i> also M. Camille Dareste, 'Recherches sur les + Conditions,' &c., 1863, pp. 16, 48.</p> + + <p><a name="Nt_833" href="#NtA_833">[833]</a> Rev. E. S. Dixon, + 'Ornamental Poultry,' 1848, p. 111; Isidore Geoffroy, 'Hist. Anomalies,' + tom. i. p. 211.</p> + + <p><a name="Nt_834" href="#NtA_834">[834]</a> 'On the Breeding of + Domestic Animals,' 1829, p. 6.</p> + + <p><a name="Nt_835" href="#NtA_835">[835]</a> Youatt on Cattle, 1834, p. + 283.</p> + + <p><a name="Nt_836" href="#NtA_836">[836]</a> Mr. Herbert Spencer + ('Principles of Biology,' 1864, vol. i. pp. 452, 468) takes a different + view; and in one place remarks: "We have seen reason to think that, as + fast as essential faculties multiply, and as fast as the number of organs + that co-operate in any given function increases, indirect equilibration + through natural selection becomes less and less capable of producing + specific adaptations; and remains fully capable only of maintaining the + general fitness of constitution to conditions." This view that natural + selection can do little in modifying the higher animals surprises me, + seeing that man's selection has undoubtedly effected much with our + domesticated quadrupeds and birds.</p> + + <p><a name="Nt_837" href="#NtA_837">[837]</a> Dr. Prosper Lucas + apparently disbelieves in any such connexion, 'L'Héréd. Nat.,' tom. ii. + pp. 88-94.</p> + + <p><a name="Nt_838" href="#NtA_838">[838]</a> 'British Medical Journal,' + 1862, p. 433.</p> + + <p><a name="Nt_839" href="#NtA_839">[839]</a> Boudin, 'Geograph. + Médicale,' tom. i. p. 406.</p> + + <p><a name="Nt_840" href="#NtA_840">[840]</a> This fact and the following + cases, when not stated to the contrary, are taken from a very curious + paper by Prof. Heusinger, in 'Wochenschrift für Heilkunde,' May 1846, s. + 277.</p> + + <p><a name="Nt_841" href="#NtA_841">[841]</a> Mr. Mogford, in the + 'Veterinarian,' quoted in 'The Field,' Jan. 22, 1861, p. 545.</p> + + <p><a name="Nt_842" href="#NtA_842">[842]</a> 'Edinburgh Veterinary + Journal,' Oct. 1860, p. 347.</p> + + <p><a name="Nt_843" href="#NtA_843">[843]</a> 'Hist. des Anomalies,' + 1832, tom. i. pp. 22, 537-556; tom. iii. p. 462.</p> + + <p><a name="Nt_844" href="#NtA_844">[844]</a> 'Comptes Rendus,' 1855, pp. + 855, 1029.</p> + + <p><a name="Nt_845" href="#NtA_845">[845]</a> Carpenter's 'Comp. Phys.,' + 1854, p. 480; <i>see</i> also Camille Dareste, 'Comptes Rendus,' March + 20th, 1865, p. 562.</p> + + <p><a name="Nt_846" href="#NtA_846">[846]</a> 'Elements of Physiology,' + Eng. translat, vol. i., 1838, p. 412. With respect to Vrolik, <i>see</i> + Todd's 'Cyclop. of Anat. and Phys.,' vol. iv., 1849-52, p. 973.</p> + + <p><a name="Nt_847" href="#NtA_847">[847]</a> 'Tératologie Vég.,' 1841, + livre iii.</p> + + <p><a name="Nt_848" href="#NtA_848">[848]</a> 'Hist. des Anomalies,' tom. + iii. pp. 4, 5, 6.</p> + + <p><a name="Nt_849" href="#NtA_849">[849]</a> 'Tératologie Vég.,' p. 156. + <i>See</i> also my paper on climbing plants in 'Journal of Linn. Soc. + Bot.,' vol. ix., 1865, p. 114.</p> + + <p><a name="Nt_850" href="#NtA_850">[850]</a> 'Mémoires du Muséum,' + &c., tom. viii. p. 178.</p> + + <p><a name="Nt_851" href="#NtA_851">[851]</a> Loudon's 'Encyclop. of + Gardening,' p. 829.</p> + + <p><a name="Nt_852" href="#NtA_852">[852]</a> Prichard, 'Phys. Hist. of + Mankind,' 1851, vol. i. p. 324.</p> + + <p><a name="Nt_853" href="#NtA_853">[853]</a> 'Annales des Sc. Nat.,' 1st + series, tom. xix. p. 327.</p> + + <p><a name="Nt_854" href="#NtA_854">[854]</a> 'Comptes Rendus,' Dec. + 1864, p. 1039.</p> + + <p><a name="Nt_855" href="#NtA_855">[855]</a> Ueber Fötale Rachites, + 'Würzburger Medicin. Zeitschrift,' 1860, B. i. s. 265.</p> + + <p><a name="Nt_856" href="#NtA_856">[856]</a> 'Tératologie Vég.,' p. 192. + Dr. M. Masters informs me that he doubts the truth of this conclusion; + but the facts to be given seem to be sufficient to establish it.</p> + + <p><a name="Nt_857" href="#NtA_857">[857]</a> 'Journal of Horticulture,' + July 2nd, 1861, p. 253.</p> + + <p><a name="Nt_858" href="#NtA_858">[858]</a> It would be worth trial to + fertilise with the same pollen the central and lateral flowers of the + pelargonium, and of some other highly cultivated plants, protecting them + of course from insects: then to sow the seed separately, and observe + whether the one or the other lot of seedlings varied the most.</p> + + <p><a name="Nt_859" href="#NtA_859">[859]</a> Quoted in 'Journal of + Horticulture,' Feb. 24, 1863, p. 152.</p> + + <p><a name="Nt_860" href="#NtA_860">[860]</a> 'Gardener's Chronicle,' + 1866, p. 612. For the Phalænopsis, <i>see</i> idem, 1867, p. 211.</p> + + <p><a name="Nt_861" href="#NtA_861">[861]</a> Mémoires ... des Végétaux,' + 1837, tom. ii. p. 170.</p> + + <p><a name="Nt_862" href="#NtA_862">[862]</a> 'Journal of Horticulture,' + July 23, 1861, p. 311.</p> + + <p><a name="Nt_863" href="#NtA_863">[863]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 137.</p> + + <p><a name="Nt_864" href="#NtA_864">[864]</a> Hugo von Mohl, 'The + Vegetable Cell,' Eng. tr., 1852, p. 76.</p> + + <p><a name="Nt_865" href="#NtA_865">[865]</a> The Rev. H. H. Dombrain, in + 'Journal of Horticulture,' 1861, June 4th, p. 174; and June 25th, p. 234; + 1862, April 29th, p. 83.</p> + + <p><a name="Nt_866" href="#NtA_866">[866]</a> 'Transact. Linn. Soc.,' + vol. xxiii., 1861, p. 360.</p> + + <p><a name="Nt_867" href="#NtA_867">[867]</a> 'Die Getreidearten,' 1843, + s. 208, 209.</p> + + <p><a name="Nt_868" href="#NtA_868">[868]</a> 'Gardener's Chronicle,' + 1850, p. 198.</p> + + <p><a name="Nt_869" href="#NtA_869">[869]</a> Quoted in 'Gardener's + Chron.,' 1866, p. 74.</p> + + <p><a name="Nt_870" href="#NtA_870">[870]</a> 'Ueber den Begriff der + Pflanzenart,' 1834, s. 14.</p> + + <p><a name="Nt_871" href="#NtA_871">[871]</a> 'Domesticated Animals,' + 1845, p. 351.</p> + + <p><a name="Nt_872" href="#NtA_872">[872]</a> Bechstein, 'Naturgeschichte + Deutschlands,' Band iv., 1795, s. 31.</p> + + <p><a name="Nt_873" href="#NtA_873">[873]</a> 'Proc. Entomolog. Soc. of + Philadelphia,' Oct. 1863, p. 213.</p> + + <p><a name="Nt_874" href="#NtA_874">[874]</a> Quoted by Paget, 'Lectures + on Pathology,' 1853, p. 159.</p> + + <p><a name="Nt_875" href="#NtA_875">[875]</a> Dr. Lachmann, also, + observes ('Annals and Mag. of Nat. History,' 2nd series, vol. xix., 1857, + p. 231) with respect to infusoria, that "fissation and gemmation pass + into each other almost imperceptibly." Again, Mr. W. C. Minor ('Annals + and Mag. of Nat. Hist.,' 3rd series, vol. xi. p. 328) shows that with + Annelids the distinction that has been made between fission and budding + is not a fundamental one. <i>See</i> Bonnet, 'Œuvres d'Hist. Nat.,' + tom. v., 1781, p. 339, for remarks on the budding-out of the amputated + limbs of Salamanders. <i>See</i>, also, Professor Clark's work 'Mind in + Nature,' New York, 1865, pp. 62, 94.</p> + + <p><a name="Nt_876" href="#NtA_876">[876]</a> Paget, 'Lectures on + Pathology,' 1853, p. 158.</p> + + <p><a name="Nt_877" href="#NtA_877">[877]</a> Idem, pp. 152, 164.</p> + + <p><a name="Nt_878" href="#NtA_878">[878]</a> On the Asexual Reproduction + of Cecydomyide Larvæ, translated in 'Annals and Mag. of Nat. Hist.,' + March 1866, pp. 167, 171.</p> + + <p><a name="Nt_879" href="#NtA_879">[879]</a> <i>See</i> some excellent + remarks on this head by Quatrefages, in 'Annales des Sc. Nat.,' Zoolog., + 3rd series, 1850, p. 138.</p> + + <p><a name="Nt_880" href="#NtA_880">[880]</a> 'Annals and Mag. of Nat. + Hist.,' 2nd series, vol. xx., 1857, pp. 153-455.</p> + + <p><a name="Nt_881" href="#NtA_881">[881]</a> 'Annales des Sc. Nat.,' 3rd + series, 1850, tom. xiii.</p> + + <p><a name="Nt_882" href="#NtA_882">[882]</a> 'Transact. Phil. Soc.,' + 1851, pp. 196, 208, 210; 1853, p. 245, 247.</p> + + <p><a name="Nt_883" href="#NtA_883">[883]</a> 'Beitrage zur Kenntniss,' + &c., 1844, s. 345.</p> + + <p><a name="Nt_884" href="#NtA_884">[884]</a> 'Nouvelles Archives du + Muséum,' tom. i. p. 27.</p> + + <p><a name="Nt_885" href="#NtA_885">[885]</a> As quoted by Sir J. Lubbock + in 'Nat. Hist. Review,' 1862, p. 345.</p> + + <p><a name="Nt_886" href="#NtA_886">[886]</a> 'Transact. Linn. Soc.,' + vol. xxiv., 1863, p. 62.</p> + + <p><a name="Nt_887" href="#NtA_887">[887]</a> 'Parthenogenesis,' 1849, + pp. 25-26. Prof. Huxley has some excellent remarks ('Medical Times,' + 1856, p. 637) on this subject, in reference to the development of + star-fishes, and shows how curiously metamorphosis graduates into + gemmation or zoid-formation, which is in fact the same as + metagenesis.</p> + + <p><a name="Nt_888" href="#NtA_888">[888]</a> Prof. J. Reay Greene, in + Günther's 'Record of Zoolog. Lit.,' 1865, p. 625.</p> + + <p><a name="Nt_889" href="#NtA_889">[889]</a> Fritz Müller's 'Für + Darwin,' 1864, s. 65, 71. The highest authority on crustaceans, Prof. + Milne Edwards, insists ('Annal. des Sci. Nat.,' 2nd series, Zoolog., tom. + iii. p. 322) on their metamorphoses differing even in closely allied + genera.</p> + + <p><a name="Nt_890" href="#NtA_890">[890]</a> Prof. Allman, in 'Annals + and Mag. of Nat. Hist.,' 3rd series, vol. xiii., 1864, p. 348; Dr. S. + Wright, idem, vol. viii., 1861, p. 127. <i>See</i> also p. 358 for + analogous statements by Sars.</p> + + <p><a name="Nt_891" href="#NtA_891">[891]</a> 'Tissus Vivants,' 1866, p. + 22.</p> + + <p><a name="Nt_892" href="#NtA_892">[892]</a> 'Cellular Pathology,' + translat. by Dr. Chance, 1860, pp. 14, 18, 83, 460.</p> + + <p><a name="Nt_893" href="#NtA_893">[893]</a> Paget, 'Surgical + Pathology,' vol. i., 1853, pp. 12-14.</p> + + <p><a name="Nt_894" href="#NtA_894">[894]</a> Idem, p. 19.</p> + + <p><a name="Nt_895" href="#NtA_895">[895]</a> Mantegazza, quoted in + 'Popular Science Review,' July 1865, p. 522.</p> + + <p><a name="Nt_896" href="#NtA_896">[896]</a> 'De la Production + Artificielle des Os,' p. 8.</p> + + <p><a name="Nt_897" href="#NtA_897">[897]</a> Isidore Geoffroy St. + Hilaire, 'Hist. des Anomalies,' tom. ii. pp. 549, 560, 562; Virchow, + idem, p. 484.</p> + + <p><a name="Nt_898" href="#NtA_898">[898]</a> For the most recent + classification of cells, <i>see</i> Ernst Häckel's 'Generelle + Morpholog.,' Band ii., 1866, s. 275.</p> + + <p><a name="Nt_899" href="#NtA_899">[899]</a> 'The Structure and Growth + of Tissues,' 1865, p. 21, &c.</p> + + <p><a name="Nt_900" href="#NtA_900">[900]</a> Dr. W. Turner, 'The present + Aspect of Cellular Pathology,' 'Edinburgh Medical Journal,' April, + 1863.</p> + + <p><a name="Nt_901" href="#NtA_901">[901]</a> This term is used by Dr. E. + Montgomery ('On the Formation of so-called Cells in Animal Bodies,' 1867, + p. 42), who denies that cells are derived from other cells by a process + of growth, but believes that they originate through certain chemical + changes.</p> + + <p><a name="Nt_902" href="#NtA_902">[902]</a> Prof. Huxley has called my + attention to the views of Buffon and Bonnet. The former ('Hist. Nat. + Gén.,' edit. of 1749, tom. ii. pp. 54, 62, 329, 333, 420, 425) supposes + that organic molecules exist in the food consumed by every living + creature; and that these molecules are analogous in nature with the + various organs by which they are absorbed. When the organs thus become + fully developed, the molecules being no longer required collect and form + buds or the sexual elements. If Buffon had assumed that his organic + molecules had been formed by each separate unit throughout the body, his + view and mine would have been closely similar.</p> + + <p>Bonnet ('Œuvres d'Hist. Nat.,' tom. v., part i., 1781, 4to + edit., p. 334) speaks of the limbs having germs adapted for the + reparation of all possible losses; but whether these germs are supposed + to be the same with those within the buds and sexual organs is not clear. + His famous but now exploded theory of <i>emboîtement</i> implies that + perfect germs are included within germs in endless succession, pre-formed + and ready for all succeeding generations. According to my view, the germs + or gemmules of each separate part were not originally pre-formed, but are + continually produced at all ages during each generation, with some handed + down from preceding generations.</p> + + <p>Prof. Owen remarks ('Parthenogenesis,' 1849, pp. 5-8), "Not all the + progeny of the primary impregnated germ-cell are required for the + formation of the body in all animals: certain of the derivative + germ-cells may remain unchanged and become included in that body which + has been composed of their metamorphosed and diversely combined or + confluent brethren: so included, any derivative germ-cell, or the nucleus + of such, may commence and repeat the same processes of growth by + imbibition, and of propagation by spontaneous fission, as those to which + itself owed its origin;" &c. By the agency of these germ-cells Prof. + Owen accounts for parthenogenesis, for propagation by self-division + during successive generations, and for the repairs of injuries. His view + agrees with mine in the assumed transmission and multiplication of his + germ-cells, but differs fundamentally from mine in the belief that the + primary germ-cell was formed within the ovarium of the female and was + fertilised by the male. My gemmules are supposed to be formed, quite + independently of sexual concourse, by each separate cell or unit + throughout the body, and to be merely aggregated within the reproductive + organs.</p> + + <p>Lastly, Mr. Herbert Spencer ('Principles of Biology,' vol. i., 1863-4, + chaps. iv. and viii.) has discussed at considerable length what he + designates as physiological units. These agree with my gemmules in being + supposed to multiply and to be transmitted from parent to child; the + sexual elements are supposed to serve merely as their vehicles; they are + the efficient agents in all the forms of reproduction and in the repairs + of injuries; they account for inheritance, but they are not brought to + bear on reversion or atavism, and this is unintelligible to me; they are + supposed to possess polarity, or, as I call it, affinity; and apparently + they are believed to be derived from each separate part of the whole + body. But gemmules differ from Mr. Spencer's physiological units, + inasmuch as a certain number, or mass of them, are, as we shall see, + requisite for the development of each cell or part. Nevertheless I should + have concluded that Mr. Spencer's views were fundamentally the same with + mine, had it not been for several passages which, as far as I understand + them, indicate something quite different. I will quote some of these + passages from pp. 254-256. "In the fertilised germ we have two groups of + physiological units, slightly different in their structures."... "It is + not obvious that change in the form of the part, caused by changed + action, involves such change in the physiological units throughout the + organism, that these, when groups of them are thrown off in the shape of + reproductive centres, will unfold into organisms that have this part + similarly changed in form. Indeed, when treating of Adaptation, we saw + that an organ modified by increase or decrease of function can but slowly + so react on the system at large as to bring about those correlative + changes required to produce a new equilibrium; and yet only when such new + equilibrium has been established, can we expect it to be <i>fully</i> + expressed in the modified physiological units of which the organism is + built—only then can we count on a complete transfer of the + modification to descendants."... "That the change in the offspring must, + other things equal, be in the same direction as the change in the parent, + we may dimly see is implied by the fact, that the change propagated + throughout the parental system is a change towards a new state of + equilibrium—a change tending to bring the actions of all organs, + reproductive included, into harmony with these new actions."</p> + + <p><a name="Nt_903" href="#NtA_903">[903]</a> M. Philipeaux ('Comptes + Rendus,' Oct. 1, 1866, p. 576, and June, 1867) has lately shown that when + the entire fore-limb, including the scapula, is extirpated, the power of + regrowth is lost. From this he concludes that it is necessary for + regrowth that a small portion of the limb should be left. But as in the + lower animals the whole body may be bisected and both halves be + reproduced, this belief does not seem probable. May not the early closing + of a deep wound, as in the case of the extirpation of the scapula, + prevent the formation or protrusion of the nascent limb?</p> + + <p><a name="Nt_904" href="#NtA_904">[904]</a> 'Annal. des Sc. Nat.,' 3rd + series, Bot., tom. xiv., 1850, p. 244.</p> + + <p><a name="Nt_905" href="#NtA_905">[905]</a> <i>See</i> some very + interesting papers on this subject by Prof. Lionel Beale, in 'Medical + Times and Gazette,' Sept. 9th, 1865, pp. 273, 330.</p> + + <p><a name="Nt_906" href="#NtA_906">[906]</a> Third Report of the R. + Comm. on the Cattle Plague, as quoted in 'Gard. Chronicle,' 1866, p. + 446.</p> + + <p><a name="Nt_907" href="#NtA_907">[907]</a> In a cod-fish, weighing 20 + lb., Mr. F. Buckland ('Land and Water,' 1867, p. 57) calculated the above + number of eggs. In another instance, Harmer ('Phil. Transact.,' 1767, p. + 280) found 3,681,760 eggs. For the Ascaris, <i>see</i> Carpenter's 'Comp. + Phys.,' 1854, p. 590. Mr. J. Scott, of the Royal Botanic Garden of + Edinburgh, calculated, in the same manner as I have done for some British + orchids ('Fertilisation of Orchids,' p. 344), the number of seeds in a + capsule of an Acropera, and found the number to be 371,250. Now this + plant produces several flowers on a raceme and many racemes during a + season. In an allied genus, Gongora, Mr. Scott has seen twenty capsules + produced on a single raceme: ten such racemes on the Acropera would yield + above seventy-four millions of seed. I may add that Fritz Müller informs + me that he found in a capsule of a Maxillaria, in South Brazil, that the + seed weighed 42½ grains: he then arranged half a grain of seed in a + narrow line, and by counting a measured length found the number in the + half-grain to be 20,667, so that in the capsule there must have been + 1,756,440 seeds! The same plant sometimes produces half-a-dozen + capsules.</p> + + <p><a name="Nt_908" href="#NtA_908">[908]</a> 'Annals and Mag. of Nat. + Hist.,' 3rd series, vol. viii., 1861, p. 490.</p> + + <p><a name="Nt_909" href="#NtA_909">[909]</a> Paget, 'Lectures on + Pathology,' p. 27; Virchow, 'Cellular Pathology,' translat. by Dr. + Chance, pp. 123, 126, 294; Claude Bernard, 'Des Tissus Vivants,' pp. 177, + 210, 337; Müller's 'Physiology,' Eng. translat., p. 290.</p> + + <p><a name="Nt_910" href="#NtA_910">[910]</a> Virchow, 'Cellular + Pathology,' trans. by Dr. Chance, 1860, pp. 60, 162, 245, 441, 454.</p> + + <p><a name="Nt_911" href="#NtA_911">[911]</a> Idem, pp. 412-426.</p> + + <p><a name="Nt_912" href="#NtA_912">[912]</a> <i>See</i> Rev. J. M. + Berkeley, in 'Gard. Chron.,' April 28th, 1866, on a bud developed on the + petal of the Clarkia. <i>See</i> also H. Schacht, 'Lehrbuch der Anat.,' + &c., 1859, Theile ii. s. 12, on adventitious buds.</p> + + <p><a name="Nt_913" href="#NtA_913">[913]</a> Mr. Herbert Spencer + ('Principles of Biology,' vol. ii. p. 430) has fully discussed the + antagonism between growth and reproduction.</p> + + <p><a name="Nt_914" href="#NtA_914">[914]</a> The male salmon is known to + breed at a very early age. The Triton and Siredon, whilst retaining their + larval branchiæ, according to Filippi and Duméril ('Annals and Mag. of + Nat. Hist.,' 3rd series, 1866, p. 157), are capable of reproduction. + Ernst Häckel has recently ('Monatsbericht Akad. Wiss. Berlin,' Feb. 2nd, + 1865) observed the surprising case of a medusa, with its reproductive + organs active, which produces by budding a widely different form of + medusa; and this latter also has the power of sexual reproduction. Krohn + has shown ('Annals and Mag. of Nat. Hist.,' 3rd series, vol. xix., 1862, + p. 6) that certain other medusæ, whilst sexually mature, propagate by + gemmæ.</p> + + <p><a name="Nt_915" href="#NtA_915">[915]</a> <i>See</i> his excellent + discussion on this subject in 'Nouvelles Archives du Muséum,' tom. i. p. + 151.</p> + + <p><a name="Nt_916" href="#NtA_916">[916]</a> Various physiologists have + insisted on this distinction between growth and development. Prof. + Marshall ('Phil. Transact.,' 1864, p. 544) gives a good instance in + microcephalous idiots, in which the brain continues to grow after having + been arrested in its development.</p> + + <p><a name="Nt_917" href="#NtA_917">[917]</a> 'Compte Rendu,' Nov. 14, + 1864, p. 800.</p> + + <p><a name="Nt_918" href="#NtA_918">[918]</a> As previously remarked by + Quatrefages, in his 'Metamorphoses de l'Homme,' &c., 1862, p. + 129.</p> + + <p><a name="Nt_919" href="#NtA_919">[919]</a> Günther's 'Zoological + Record,' 1864, p. 279.</p> + + <p><a name="Nt_920" href="#NtA_920">[920]</a> Sedgwick, in + 'Medico-Chirurg. Review,' April 1863, p. 454.</p> + + <p><a name="Nt_921" href="#NtA_921">[921]</a> Isid. Geoffroy St. Hilaire, + 'Hist. des Anomalies,' tom. i., 1832, pp. 435, 657; and tom. ii. p. + 560.</p> + + <p><a name="Nt_922" href="#NtA_922">[922]</a> Virchow, 'Cellular + Pathology,' 1860, p. 66.</p> + + <p><a name="Nt_923" href="#NtA_923">[923]</a> Moquin-Tandon, 'Tératologie + Veg.,' 1841, pp. 218, 220, 353. For the case of the pea, <i>see</i> + 'Gardener's Chron.,' 1866, p. 897.</p> + + <p><a name="Nt_924" href="#NtA_924">[924]</a> Müller's 'Physiology,' Eng. + translat., vol. i. p. 407.</p> + + <p><a name="Nt_925" href="#NtA_925">[925]</a> <i>See</i> some remarks to + this effect by Sir H. Holland in his 'Medical Notes,' 1839, p. 32.</p> + + <p><a name="Nt_926" href="#NtA_926">[926]</a> This is the view taken by + Prof. Häckel, in his 'Generelle Morphologie' (B. ii. s. 171), who says: + "Lediglich die partielle Identität der specifischconstituirten Materie im + elterlichen und im kindlichen Organismus, die Theilung dieser Materie bei + der Fortpflanzung, ist die Ursache der Erblichkeit."</p> + + <p><a name="Nt_927" href="#NtA_927">[927]</a> In these remarks I, in + fact, follow Naudin, who speaks of the elements or essences of the two + species which are crossed. See his excellent memoir in the 'Nouvelles + Archives du Muséum,' tom. i. p. 151.</p> + + <p><a name="Nt_928" href="#NtA_928">[928]</a> Godron, 'De l'Espèce,' + 1859, tom. ii. p. 44, &c.</p> + + <p><a name="Nt_929" href="#NtA_929">[929]</a> Journal Proc. Linn. Soc., + 1858, vol. iii. p. 60.</p> + + <p><a name="Nt_930" href="#NtA_930">[930]</a> 'The Quarterly Journal of + Science,' Oct. 1867, p. 486.</p> + + <p><a name="Nt_931" href="#NtA_931">[931]</a> M. Rufz de Lavison, in + 'Bull. Soc. Imp. d'Acclimat.,' Dec. 1862, p. 1009.</p> + + <p><a name="Nt_932" href="#NtA_932">[932]</a> 'Races of Man,' 1850, p. + 315.</p> + + <p><a name="Nt_933" href="#NtA_933">[933]</a> 'Travels in Peru,' Eng. + translat., p. 177.</p> + + <p><a name="Nt_934" href="#NtA_934">[934]</a> Youatt on Cattle, 1834, p + 200: on Pigs; <i>see</i> 'Gard. Chronicle,' 1854, p. 410.</p> + + <p><a name="Nt_935" href="#NtA_935">[935]</a> 'Die Pflanzen der + Pfahlbauten,' 1865.</p> + + <p><a name="Nt_936" href="#NtA_936">[936]</a> Morlot, 'Soc. Vaud. des + Scien. Nat,' Mars 1860, p. 298.</p> + + <p><a name="Nt_937" href="#NtA_937">[937]</a> Rütimeyer, 'Die Fauna der + Pfahlbauten,' 1861, s. 30.</p> + + <p><a name="Nt_938" href="#NtA_938">[938]</a> Godron, 'De l'Espèce,' tom. + i., 1859, p. 368.</p> + + <p><a name="Nt_939" href="#NtA_939">[939]</a> 'Géographie Botan.,' 1855, + p. 989.</p> + + <p><a name="Nt_940" href="#NtA_940">[940]</a> Pickering, 'Races of Man,' + 1850, p. 318.</p> + + <p><a name="Nt_941" href="#NtA_941">[941]</a> 'Journal of a Horticultural + Tour,' by a Deputation of the Caledonian Hist. 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