I860.] on Species and Races, and their Origin, 197 



necessities, and to have endeavoured to comply with them. The 

 Pigeons called Pouters, Tumblers, Fantails, &c., which the audience 

 had an opportunity of examining, are in his view, the result of so 

 nuiiiy long-continued experiments on the manufacture of species ; and 

 he considers that causes essentially similar to those which have 

 given rise to these birds are operative in nature now, and have in past 

 times been the agents in producing all the species we know. If 

 neither of these positions can be upset, Mr. Darwin's must be regarded 

 as a true theory of species, as well based as any other physical theory : 

 they require, therefore, the most careful and searching criticism. 



After pointing out the remarkable differences in structure and 

 habits between the Carrier, Pouter, Fantail, Tumbler, and the wild 

 Columha livia, the speaker expressed his entire agreement with Mr. 

 Darwin's conclusion, that all the former domesticated breeds had 

 arisen from the last-named wild stock ; and on the following 

 grounds — 1. That all interbreed freely with one another. 2. That 

 none of the domesticated breeds presents the slightest approximation 

 to any wild species but C. livia, whose characteristic markings are at 

 times exhibited by all. 3. That the known habits of the Indian 

 variety of the Rock Pigeon (C intermedia) render its domestication 

 easily intelligible. 4. That existing varieties connect the extremest 

 modifications of the domestic breeds by insensible links with C. livia. 

 5. That there is historical evidence of the divergence of existing breeds, 

 e.g. the Tumbler, from forms less unlike C. livia. 



The speaker then analyzed the process of selection by which the 

 domesticated breeds had been produced from the Wild Rock Pigeon ; 

 and he showed its possibility to depend upon two laws which hold good 

 for all species, viz., 1. That every species tends to vary. 2. That 

 variations are capable of hereditary transmission. The second law is 

 well understood ; but the speaker adverted to the miscomprehension 

 which appears to prevail regarding the first, and showed that the 

 variation of a species is by no means an adaptation to conditions in the 

 sense in which that phrase is commonly used. Pigeon-fanciers, in fact, 

 subject their pigeons to a complete uniformity of conditions ; but while 

 the similarly used feet, legs, skull, sacral vertebrae, tail feathers, oil 

 gland and crop undergo the most extraordinary modifications ; on the 

 other hand, the wings, whose use is hardly ever permitted to the choice 

 breeds, have hitherto shown no sign of diminution. Man has not as yet 

 been able to determine a variation ; he only favours those which arise 

 spontaneously, i.e. are determined by unknown conditions. 



It must be admitted that, by selection, a species may be made 

 to give rise experimentally to excessively different modifications ; and 

 the next question is. Do causes adequate to exert selection exist 

 in nature? On this point, the speaker referred his audience to 

 Mr. Darwin's chapter on the struggle for existence, as affording ample 

 satisfactory proof that such adequate natural causes do exist. 



There can be no question that just as man cherishes the varieties 

 he wishes to preserve, and destroys those he does not care about ; so 

 Vol. III. (No. 31.) p 



