im.} A New Factor in Evolution, 44y 



counted for without the inheritance of acquired characters. 

 So also the evidence drawn from paleontology which cites 

 progressive variations resting on functional use and disuse. 

 Second, the evidence drawn from the facts of " determinate 

 variations ; " since by this principle we have the preservation 

 of such variations in phylogeny without the inheritance of ac- 

 quired characters. 



4. But this is n<>t Pretormism in the oh} *< n*e : since the adpa- 





11 set" the 



Hon of evolution ar< novelties of junction in whole or part 

 (although they utilize congenital variations of structure). 

 And it is only by the exercise of these novel functions that the 

 creatures are kept alive to propagate and thus produce further 

 variations of structure which may in time make the whole 

 function, with its adequate structure, congenital. Romanes' 

 argument from " partial co-adaptations " and " selective value," 

 seem to hold in the case of reflex and instinctive functions (ref. 

 4, 5), as against the old preformist or Weismannist view, al- 

 though the operation of Organic Selection, as now explained, 

 renders them ineffective when urged in support of Lam ark- 

 ism. " We may imagine creatures, whose hands were used 

 for holding only with the thumb and fingers on the same side 

 of the object held, to have first discovered, under stress of cir- 

 cumstances and with variations which permitted the further 

 adaptation, how to make use of the thumb for grasping op- 

 posite to the fingers, as we now do. Then let us suppose that 

 this proved of such utility that all the young that did not do 

 it were killed off; the next generation following would be 

 plastic, intelligent, or imitative, enough to do it also. They 

 would use the same co-ordinations and prevent natural selec- 

 tion getting its operation on them; and so instinctive 

 'thumb-grasping' might be waited for indefinitely by the 

 species and then be got as an instinct altogether apart from 

 use-inheritance " (ref. 4). " I have cited ' thumb-grasping ' be- 

 cause we can see in the child the anticipation, by intelligence 

 and imitation, of the use of the thumb for the adaptation 

 which the Simian probably gets entirely by instinct, and 

 which I think an isolated and weak-minded child, say, would 

 also come to do by instinct ' " (ref. 4). 



