436 DARWINISM chap. 



will even then not equal, in each generation, the amount of 

 the fortuitous variations of the same j^art. If it be urged 

 that the effects of use would modify all the individuals of a 

 species, while the fortuitous variations to the amount named 

 only apply to a portion of them, it may be replied, that that 

 portion is sufficiently large to afford ample materials for 

 selection, since it often equals the numbers that can annually 

 survive ; while the recurrence in each successive generation of 

 a like amount of variation would render possible such a rapid 

 adjustment to new conditions that the effects of use or disuse 

 would be as nothing in comparison. It follows, that even 

 admitting the modifying effects of the environment, and that 

 such modifications are inherited, they Avould yet be entirely 

 swamped by the greater effects of fortuitous variation, and the 

 far more rapid cumulative results of the selection of such 

 variations. 



Supposed Action of the Environment in Initiating Variations. 



It is, however, urged that the reaction of the environment 

 initiates variations, which without it would never arise ; such, 

 for instance, as the origin of horns through the pressures and 

 irritations caused by butting, or otherwise using the head as a 

 weapon or for defence. Admitting, for the sake of argument, 

 that this is so, all the evidence we possess shows that, from the 

 very first appearance of the rudiment of such an organ, it would 

 vary to a greater extent than the amount of growth directly 

 produced by use ; and these variations Avould be subject to 

 selection, and would thus modify the organ in ways which use 

 alone Avould never bring about. We have seen that this hns 

 been the case Avith the branching antlers of the stag, which 

 have been modified by selection, so as to become useful 

 in other ways than as a mere weapon ; and the same has 

 almost certainly been the case with the variously curved 

 and t\nsted horns of antelopes. In like manner, every con- 

 ceivable rudiment would, from its first appearance, be subject 

 to the law of variation and selection, to which, thenceforth, 

 the direct effect of the environment would be altogether 

 subordinate. 



A very similar mode of reasoning will a})ply to the other 

 branch of the subject — the initiation of structures and organs 



