212 TEAK-BOOK OF FACTS. 



hension which appears to prevail regarding the first, and showed 

 that the variation of a species is by no means an adaptation to con- 

 ditions 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 

 vertebra, tail feathers, oil gland, and crop undergo the most extra- 

 ordinary modifications ; on the other hand the wings, whose use i3 

 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 ; lie only favours those which ari.se 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 

 Straggle 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 lie wishes to preserve, and de- 

 stroys those he does not care about ; so nature (even if we consider 

 the physical world as a mere mechanism) must tend to cherish those 

 varieties which are better fitted to work harmoniously with the con- 

 ditions she offers, and to destroy the rest. There seems to be no 

 doubt, then, that modifications equivalent in extent to the four 

 breeds of pigeons, might be developed from a species by natural 

 causes ; and therefore, if it can be shown that these breeds have all 

 the characters which are ever found in species, Mr. Darwin's case 

 would be complete. However, there is as yet no proof that, by 

 selection, modifications having the physiological character of species 

 (i.e., whose offspring are incapable of propagation inter sc) have 

 ever been produced from a common stock. No doubt the numerous 

 indirect arguments brought forward by Mr. Darwin to weaken the 

 force of this objection are of great weight; no doubt it cannot be 

 proved that all species give rise to hybrids infertile inter se ; no 

 doubt (so far as the speaker's private conviction went), a well-con- 

 ducted series of experiments very probably would yield us deriva- 

 tives from a common stock, whose offspring should be infertile inter 

 te; but we must deal with hots as they stand, and at present it 

 nasi be admitted thai Mr. Darwin's theory does not account for all 

 the phenomena exhibited by species; and, so far, falls short of 



being a .satisfactory theory. 



l:l !•:■:! \ r anim w, FOhM. 



Dr. Goluxqwood has read to the British Association a paper 

 '■On Etecarreul Animal Form, and Its Significance in Systematic 

 y," The object of this oommonioation was to call attention to 

 the fn quenl recurrence of similar forms in widely separated groups of 

 the animal kingdom, similarities, therefore, whioh were unaccom- 

 panied by homologies of interna] structure. These analogies of 

 ram had greatly intlueiieoii th.. progres s oi cl tssification, by attract- 

 ing the attention of Hystcmati/.ers while as yet structural homologies 



