Characters, Hereditary and Acquired. 85 



scratching reflex. In the first place, co-adaptation 

 is present in a very high degree, because this shaking 

 reflex in the dog, unlike the skin-twitching reflex 

 in the horse, does not involve only a single muscle, 

 or even a single group of muscles : it involves more 

 or less the co-ordinated activity of many voluntary 

 muscles all over the body. Such, at any rate, is 

 the case when the action is performed by the in- 

 telligent volition of an adult dog ; and if a brainless 

 dog, or a young puppy, does not perform it so 

 extensively or so vigorously, this only goes to prove 

 that the reflex has not yet been sufficiently developed 

 to serve as a substitute for intelligent volition — i.e. 

 that it is useless, or a mere organic shadow of the 

 really adaptive substance. Again, even if this nascent 

 reflex had been so far developed as to have been 

 capable of superseding voluntary action, still we may 

 fairly doubt whether it could have proved of selective 

 value. For it is questionable whether the imme- 

 diate riddance of water after a wetting is a matter 

 of life and death to dogs in a state of nature. 

 Moreover, even if it were, every individual dog would 

 always have got rid of the irritation, and so of 

 the danc^er, by means of a voluntary shake — with 

 the double result that natural selection has never 

 had any opportunity of gradually building up 

 a special reflex mechanism for the purpose of 

 securing a shake, and that the canine race have 

 not had to wait for any such unnecessary process. 

 Lastly, such a process, besides being unnecessary, 

 must surely have been, under any circumstances, 

 impossible. For even if we were to suppose — again 

 for the sake of saving an hypothesis at any 



