460 NOTES. 



that even in these apathetic organisms liking and dislike play a certain 

 part. Whether Acliatinella is, in fact, spared all struggle in the matter 

 of food, cannot possibly be dctennined, to judge from the investigations 

 of Gulich. The merely hypothetical superabundance of food is no proof 

 of its real sufficiency ; if, for instance, the space where this abundance 

 is supplied is very limited, the animals desirous of feeding will get in 

 each other's way, and it is possible that this might give rise to some 

 quite unknown psychical influence. Many animals, as is well known, eat 

 freely only in solitude. This is very certainly not the case with snails, 

 but they may nevertheless desire a certain amount of elbow-room, a 

 point that has never been observed, or even thought of. But even sup- 

 posing that these positions of Wagner's were all proved to the utmost 

 extent of their very positive assertions which is by no means the case 

 still, the struggle of the Achatinelltz against the causec of the epi- 

 demics that decimate them is necessarily a competition, though of course 

 not in the same sense as is a duel fought for life or death between two 

 individuals. 



Note 112, 2'0ffc 202. Notwithstanding that Darwin's works are univer- 

 sally accessible, I will here quote the passages to which I particularly 

 refer. In the first place, with reference to the external conditions of 

 existence, I offer a few extracts : ' Neither migration nor isolation in 

 themselves can do anything. These principles come into play only 

 by bringing organisms into new relations with each other, and in a lesser 

 degree with the surrounding physical conditions ' (Origin ff Species). 



' Hence, though it must bs admitted that new conditions of existence 

 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 ' (Animals under Domestication, ch. xxiii.). 



' Such changes are manifestly due not to any one pair, but to all the 

 individuals having been subjected to the same conditions, aided, per- 

 haps, by the principle of reversion ' (Descent of Man, i. 236). ' Although 

 with our present knowledge we cannot account for the strongly marked 

 differences in colour between the races of man, either through correla- 

 tion with constitutional peculiarities or through the direct action of 

 climates, yet we must not quite ignore the latter agency, for there is 

 good reason to believe that some inherited effect is thus produced ' 

 (Descent of Man, i. 2-15, and on p. 246 he adduces reasons in support of 

 this statement). 



One more quotation : ' There can, however, be no doubt that changed 

 conditions induce an almost indefinite amount of fluctuating variability 

 by which the whole organisation is rendered in some degree plastic ' 

 (ibid. i. p. 113). ComparS with this what Darwin says as to the direct 

 external influences which affect the skull (ibid. p. 147). But it seems 

 to me to be proved by numerous passages in Darwin's works that he 



