Characters, Hereditary and Acquired. 63 



formation — reveals so many instances of adaptations 

 which in their nascent condition present such ex- 

 ceedingly minute degrees of adaptive value, that it 

 seems unreasonable to attribute their development to 

 a survival of the fittest in the complex struggle for 

 existence. But as this argument is in my opinion 

 of greatest force when it is applied to certain facts 

 of physiology with which I am about to deal, I will 

 not occupy space by considering any of the number- 

 less cases to which the Neo-Lamarckians apply it 

 within the region of palaeontology ^. 



Turning then to inherited actions, it is here that 

 we might antecedently expect to find our best evi- 

 dence of the Lamarckian principles, if these principles 

 have really had any share in the process of adaptive 

 evolution. For we know that in the life-time of 

 individuals it is action, and the cessation of action, 

 which produce nearly all the phenomena of acquired 

 adaptation — use and disuse in animals being merely 

 other names for action and the cessation of action. 

 Again, we know that it is where neuro-muscular 

 machinery is concerned that we meet with the most 

 conclusive evidence of the remarkable extent to 

 which action is capable of co-ordinating structures 

 for the ready performance of particular functions ; 

 so that even during the years of childhood " practice 

 makes perfect" to the extent of organizing neuro- 

 muscular adjustments, so elaborate and complete as 

 to be indistinguishable from those which in natural 



' There is now an extensive literatnre within thisregion. Theprincipal 

 writers are Cope, Scott and Osborn. Unfortunately, however, the 

 facts adduced are not crucial as test-cases between the rival theories — 

 nearly all of them, in fact, being equally susceptible of explanation by 

 either. 



