98 THE ZOOLOGIST. 



tion being caused through one taking to climbing, or swimming, 

 or jumping. It is more than probable that the outward form 

 immediately begins to adapt itself by harmonious development 

 to the changed circumstances (such as the unique loss of a great 

 toe development in the Patas Monkey and digitigrade walking), 

 thus leaving the animals more related in blood relationship than 

 they appear (though this is, perhaps, not well illustrated in the 

 above example), through the internal essences being similar, or, 

 at most, more gradually acted on in later generations through a 

 change of diet on the part of the separating form. 



It is in the adult Patas that the curious doglike form sugges- 

 tive of high speed is most noticeable ; the young do not show it 

 so prominently. Hence I imagine the general want of comment 

 on this special development. 



One may deny the above divergence, that is, the apparent 

 difference in the rate of evolution of germ-plasm and structure, 

 but, although outward form and germ-plasm must be in real 

 unison, one cannot deny that, if one drew up a classification 

 based on germ-plasm affinity (which I have held in these notes 

 is shown in results of hybridism), this classification would cer- 

 tainly be apparently opposed in many cases to the one of struc- 

 tural similarity, as in the instances that I have given ; but that 

 I believe that this opposition would be only apparent, and have 

 nothing to do with the real harmony between germ-plasm and 

 structure, I have in these notes tried to make clear. 



One might imagine change of diet to be one of, if not the 

 greatest factor in inducing evolution, and environment of import- 

 ance chiefly in so far as it offers opportunity of this change. 

 Effects of change of diet would, one might conjecture, in time 

 affect, through the anabolic action of the chromatin, the internal 

 economy and blood of the animal, and one might expect that its 

 influence must begin to be felt before aught else. 



In the case of the Horse and Ass the difference in form and 

 habits seems more important than is generally supposed, and 

 appears to contrast somewhat with the congeniality of the germ- 

 plasm which results in conception. I might also remark here on 

 an instance given earlier in these notes — on the differentiation of 

 the Chaffinch groups from the other finches — that it is possible, 

 instead of the view of the divergence given above, that through 



