Aug. 20, 1874] 



NATURE 



315 



i 



ation could be carried ; but the great mass of them held that 

 never by any amount of internal or external change, nor by the 

 mixture of both, could the offspring of the same progenitor so 

 far deviate from each other as to constitute different species. 

 The function of the experimental philosopher is to combuie the 

 conditions of nature and loproduc; her results ; and tliis was 

 the method of Darwin.'** lie mide himself acquainted wiili what 

 could, without any manner of douljt, be done in the way of pro- 

 ducing variation. He associated hinnelf with pigeon- fanciers — 

 bought, begged, kept, and observed every breed that he could 

 obtain. Though derived Irom a common stock, the di\'ersities 

 of these pigeons were such that " a score of ihem might be chosen 

 ■which, if shown to an ornitliologist, and he were told that they 

 were wild birds, would certainly be ranked by him as well-defined 

 species." The simple principle which guides the pigeon-fancier, 

 as it does the cattle-breeder, is the selection of some variety that 

 strikes his fancy, and the propagation of this variety by inheri- 

 tance. Willi his eye still upon the p.irticular appearance which 

 he wishes to exaggerate, he selects it as it reappear; in successive 

 broods, and thus adds increment to increment imtil an astonish- 

 ing amount of divergence from the parent type is effected. Man 

 in this case does not produce the chmiiits of the variation. He 

 simply observes them, and by selection adds them together until 

 the required result has been obtained. " No man," says Mr. Dar- 

 win, "would ever try to make a fantail till he saw a pigeon with 

 a tail develojied in some slight degree in an unusual manner, or 

 a pouter until he saw a pigeon with a crop of unusual size." 

 Tims nature gives the hint, man acis upon it, and by tlie law of 

 inheritance exaggerates the deviition. 



Having thus satisfied himself by indubitable facts that the or- 

 ganisation of an animal or of a plant (for precisely the same 

 treatment applies to plants) is to some extent plastic, he passes 

 from variation under domestication to variation under nature. 

 Hitherto we have dealt with the adding together of small changes 

 by the conscious selection of man. Can Nature, thus select ? 

 Mr. Darwin's answer is, "Assuredly she can." The number of 

 living things produced is far in excess of the number that can be 

 supported ; hence at some period or other of their lives there 

 must be a struggle for existence ; and what is the infallible result ? 

 If one organism \vere a perfect copy of the other in regard to 

 strength, sliill, and agility, external conditions would decide. 

 Dut this is not the case. Here we have the fact of variety offer- 

 ing itself to nature, as in the former instance it offered itself to 

 man ; and tliose varieties wliich are least competent to cope with 

 surrounding conditions wid infallibly give way to those that are 

 competent. To use a familiar proverl), the weakest comes to the 

 wall. But the triumphant fraction ag.iinbreeds to over-production, 

 transmitting the qualities which secured its mainienance, but trans- 

 mitting them in different degree;. Tire struggle for food again 

 supervenes, and those to whom the favourable quality has l)een 

 transmitted in excess will assuredly triumph. It is easy to see 

 that we hive here the addition of increments favourable to the 

 individual still more rigorously carried out than in the case of 

 domestication ; for not only are unfavourable specimens not 

 selected l5y nature, but they are destroyed. This is what Mr. 

 Darwin calls "natural selection," which " acts by the preserva- 

 tion and accumulation of small inherited modifications, each pro- 

 fitable to the preserved being." With this idea he interpene- 

 trates and leavens the vast store of facts tliat he and others have 

 collected. We cannot, without shutting our eyes through fear or 

 prejudice, fail to see that Darwin is here dealing, not with 

 imaginary, but with true causes ; nor can we fail to discern what 

 vast modifications may be produced by natural selection in peiiods 

 sufliciently long. Each individual increment may resemble what 

 mathematicians call a " dilferential" (a quantity indefinHely 

 small); but definite and great clianges may obviously be pro- 

 duced by the integration of these infinitesimal quantities through 

 practically infinite time. 



If Darwin, like Bruno, rejects the notion of creative power 

 acting after human fashion, it certainly is not because he is 

 unacquainted with the numberless exquisite adaptations on which 

 this notion of a supernatural artificer has founded. His book is 

 a repository of the most startling facts of this description. Take 

 the marvellous observation which he cites from Dr. Criigcr, 

 where a bucket with an aperture, serving as a spout, is formed 

 in an orchid. Bees visit the flower : in eager search of material 

 for their combs they push each other into the bucket, the 



t The first step only tow.irds experimental demonstration has been taken. 

 Experiments now begun might, a couple of centuries hence, furnish dat.i of 

 incalculable value, which ought tg be supplied to the science of the future. 



drenched ones escaping from their involuntary bath by the spout. 

 Here they rub their backs against the viscid stigma of the flower 

 and obtain glue ; then against the pollen-masses, which are thus 

 stuck to the back of the bee and carried away. "When the 

 bee, thus provided, flies to another flower, or to the same flower 

 a second time, and is pushed by its comrades into the bucket, 

 and then crawls out by the pissage, the pollen-mass upon its 

 back necessarily comes first into contact with the viscid stigma," 

 which takes up the pollen ; and this is hovv that orchid is ferti- 

 lised. Or take this other case of the Catasdiaii. " Bees visit 

 these flowers in order to gnaw the labellum ; on doing this they 

 inevitably'tonch a lo.ig, tapering, sensitive projection. This, 

 when touched, transmits a sensation or vibration to a certain 

 membrane, which is instantly ruptured, setting free a spring, by 

 whicli the pollen-mass is shot forth like an arrow in the right 

 direction, and adheres by its viscid extremity to the back of the 

 bee." In this way the fertdising pollen is spread abroad. 



It is the mind thus stored with the choicest materials 

 of the teleologist that rejects teleology, seeking to refer these 

 wonders to natural causes. They illustrate, according to him, 

 the method of nature, not the "technic" of a man-like 

 artificer. The beauty of flowers is due to natural selection. 

 Those that distinguish themselves by vividly contrasting colours 

 from the surrounding green leaves are most readily seen, most 

 frequently visited by insects, most often fertilise 1, and hence 

 most favoured by natural selection. Coloured berries also readily 

 attract the attention of birds and beasts, which feed upon them, 

 spread their manured seeds abroad, thus giving trees and shrubs 

 possessing such berries a greater chance in the struggle for 

 existence. 



With profound analytic and synthetic skill, Mr. Darwin inves- 

 tigates the cell-making instinct of the hive-bee. His method of 

 dealing with it is representative. He falls back from the more 

 perfectly to the less perfectly developed instinct — from the hive- 

 bee I o the humble-bee, which uses its own cocoon as a comb, 

 and to classes of bees of intermediate skill, endeavouring to show 

 how the passage might be gradually made from the lowest to the 

 highest. The saving of wax is the most important point in the 

 economy of bees. Twelve to fifteen pounds of dry sugar are 

 said to be needed for the secretion of a single pound of wax. 

 The quantities of nectar necessary for the wax must therefore be 

 vast ; and every improvement of constructive instinct which 

 resalts in the saving of wax is a direct profit to the insect's life. 

 The time that would otherwise be devoted to the making of wax 

 is now devoted to the gathering and storing of honey for winter 

 food. He passes from the humble-bee with its rude cells, 

 through the Melipona with its more artistic cells, to the hive-bee 

 with its astonishing architecture. The bees place themselves at 

 equal distances apart upon the wax, sweep and excavate squal 

 spheres round the selected points. The spheres intersect, and 

 the planes of intersection are built up with thin laminre. 

 Hexagonal cells are thus formed. This mode of treating such 

 questions is, as I have said, representative. He habitually retires 

 from the more perfect and complex, to the less perfect and 

 simple, and carries you with him through stages oi perfecting, 

 adds increment to increment of infinitesimal change, and in this 

 way grad ually breaks down your reluctance to admit that the 

 exquisite climax of the whole could be a result of natural 

 selection. 



Mr. Darwin shirks no difiiculty ; and, saturated as the subject 

 was with his own thought, lie must have known, better than his 

 critics, the weakness as well ?.% the strength of his theory. This 

 of course would be ot little avail were his object a temporary 

 dialectic victory instead of the establishment of a truth which 

 he means to be everlasting. But he takes no pains to disguise 

 the weakness he has discerned ; nay, he takes every pains to 

 bring it into the strongest light. His vast resources enable 

 him to cope with objections started Iiy himself and others, so as 

 to leave the final impression upon the reader's mind that if they 

 be not completely answered they certainly are not fatal. Their 

 negative force being thus destroyed, you are free to be influenced 

 by the vast positive mass of evidence he is able to bring before 

 you. This largeness of knowledge and readiness of resource 

 render Mr. Darwin the most terrible of antagonists. Accom- 

 plished naturalists have levelled heavy and sustained criticisms 

 against him — not always with the view of fairly weighing his 

 theory, but with the express intention of exposing its weak 

 points only. This does not irritate him. He treats every ob- 

 jection with a soberness and thoroughness wdiich even Bishop 

 Butler might be proud to imitate, surrounding each fact with its 



