142 Determinate Evolution 



We come to the view, therefore, that evolution from 

 generation to generation has probably proceeded by the 

 operation of natural selection upon variations with the 

 assistance of the organic selection of coincident (i.e., 

 those which produce congenitally what coincides with the 

 acquisitions of the individuals) or correlated variations. 

 And we derive a view of the relation of ontogeny to phy- 

 logeny all through the animal series. All the influences 

 which work to assist the animal to make adjustments or 

 accommodations will unite to give directive determination 

 to the course of evolution. These influences we may call 

 'orthoplastic ' or directive influences. And the general 

 fact that evolution has a directive determination through 

 organic selection we may call ' Orthoplasy.' J 



As to detailed evidence of the action of organic selec- 

 tion, this is not the place to present it. It is well-nigh 

 coextensive, however, with that for natural selection ; for 

 the cases where natural selection operates to preserve 

 creatures because they adapt themselves to their environ- 

 ment are everywhere to be seen, and in all such cases 



the individuals of the earlier generation. For some influence, such as organic 

 selection, might have preserved only a remnant of the earlier generation, and 

 in this way the mean of the variations of the following generation may be 

 shifted and give the appearance of being determinate, while the variations 

 themselves remain indeterminate. And again, the paleontologists have no 

 means of saying how old one of these fossil creatures had to be in order to 

 develop the character in question. It may be that a certain age was necessary 

 and that the variations which he finds lacking would have existed if their 

 possessors had not fallen by natural selection before they were old enough to 

 develop this character and deposit it with their bones. 



1 These terms are akin to ' orthogenic ' and ' orthogenesis,' used by Eimer 

 {Verh. der Deutsch. Zool. Gesell., 1895); the latter are not adopted, how- 

 ever, for the exact meaning given above, since Eimer's view directly impli- 

 cates use-inheritance and ' determinate variations,' which are not made use of 

 here. Cf. Chap. XI. I, on 'Terminology.' 



