Characters, Hereditary and Acquired. 69 



from co-adaptation would lapse. But even then it 

 would lapse on the ground of fact. It would not 

 have been overturned, or in any way affected, by 

 Wallace's argument from artificial selection. For, in 

 that event, no such argument would be required, and, 

 if adduced, would be irrelevant, since no one has 

 ever alleged that there is any difficulty in under- 

 standing the mere confluence of adaptations by free- 

 intercrossing of the best adapted. 



Now, if we are agreed that the only question in debate 

 is the question of fact whether or not co-adaptation 

 ever occurs in nature, it appears to me that the best 

 field for debating the question is furnished by the 

 phenomena of reflex action. I can well perceive that 

 the instances adduced by Broca and Spencer in support 

 of their common argument such as the giraffe, the 

 elk, &c. are equivocal. But I think that many 

 instances which may be adduced of reflex action are 

 much more to the point. For it belongs to the very 

 nature of reflex action that it cannot work unless 

 all parts of the machinery concerned are already pre- 

 sent, and already co-ordinated, in the same organism. 

 It would be useless, in so far as such action is con- 

 cerned if the afferent and efferent nerves, the nerve- 

 centre, and the muscles organically grouped together, 

 were not all present from the very first in the same 

 individuals, and from the very first were not co- 

 ordinated as a definite piece of organic machinery. 



With respect to reflex actions, therefore, it is 

 desirable to begin by pointing out how widely the 



denial by arguing the totally different fact that adaptations may be 

 blended by free intercrossing ; for this latter fact has never been ques- 

 tioned, and has nothing to do with the one which he engaged in 

 disputing. 



